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Integrative Physiology of Exercise 2020 Virtual Event + (American Physiological Society’s (APS)Integrative Physiology of Exercise (IPE) 2020 conference, Virtual Event, 2020)
Petiz 2018 Chem Biol Interact + (Amidines are chemically characterized by t … Amidines are chemically characterized by the presence of two nitrogen atoms that bind to the same carbon atom in its structure. Several biological activities have been ascribed to these compounds. Pentamidine, an aromatic diamidine, is effective in the treatment against ''Pneumocystis carinii'' and leishmaniasis, but it can also have severe side effects. New amidine derivatives have been synthesized, among them N,N'-diphenyl-4-methoxy-benzamidine (methoxyamidine), which is effective against ''Leishmania amazonensis'' (LD50 = 20 μM) and ''Trypanosoma cruzi'' (LD50 = 59 nM). In the present study, methoxyamidine toxicity was evaluated in isolated rat liver mitochondria at the same range of concentrations that exert antiprotozoal activity. In these organelles, actively oxidizing glutamate + malate inhibited state 3 respiration (25 nmol mg-1 of protein) by ∼15%. The sites of inhibition in the respiratory chain were complex I and the segment between ubiquinone and complex III. Methoxyamidine also stimulated state 4 respiration by ∼32% and ∼43% at 50 and 65 nmol mg-1 of protein, respectively. Its uncoupling effect was confirmed by a dose-dependent increase in oxygen consumption in state 4 respiration that was induced by oligomycin, reaching up to ∼69% (65 nmol mg-1 of protein) and an increase in ATPase activity in intact mitochondria by ∼27% and ∼83% at 50 and 65 nmol mg-1 protein, respectively. Swelling that was supported by the oxidation of glutamate + malate in the presence of sodium acetate was reduced by methoxyamidine by ∼16% and 32% at 50 and 65 nmol mg-1 protein, respectively. Mitochondrial swelling in the absence of substrate and in the presence of K+ and valinomycin was inhibited by ∼20% at the same concentrations, suggesting that methoxyamidine affects mitochondrial membrane permeability and fluidity. Our data show that methoxyamidine has slight effects on the energy-linked functions of isolated mitochondria at concentrations that correspond to the LD50 against ''Leishmania amazonensis'' and ''Trypanosoma cruzi''. These findings may prompt further studies that evaluate methoxyamidine toxicity ''in vivo''.nst ''Leishmania amazonensis'' and ''Trypanosoma cruzi''. These findings may prompt further studies that evaluate methoxyamidine toxicity ''in vivo''.)
Hoefler 2016 Physiol Plant + (Amino acid catabolism is essential for adj … Amino acid catabolism is essential for adjusting pool sizes of free amino acids and takes part in energy production as well as nutrient remobilization. The carbon skeletons are generally converted to precursors or intermediates of the tricarboxylic acid cycle. In the case of cysteine, the reduced sulfur derived from the thiol group also has to be oxidized in order to prevent accumulation to toxic concentrations. Here we present a mitochondrial sulfur catabolic pathway catalyzing the complete oxidation of l-cysteine to pyruvate and thiosulfate. After transamination to 3-mercaptopyruvate, the sulfhydryl group from l-cysteine is transferred to glutathione by sulfurtransferase 1 and oxidized to sulfite by the sulfur dioxygenase ETHE1. Sulfite is then converted to thiosulfate by addition of a second persulfide group by sulfurtransferase 1. This pathway is most relevant during early embryo development and for vegetative growth under light-limiting conditions. Characterization of a double mutant produced from ''Arabidopsis thaliana'' T-DNA insertion lines for ETHE1 and sulfurtransferase 1 revealed that an intermediate of the ETHE1 dependent pathway, most likely a persulfide, interferes with amino acid catabolism and induces early senescence.© 2016 Scandinavian Plant Physiology Society.016 Scandinavian Plant Physiology Society.)
Girard 2018 mSphere + (Amino acids participate in several critica … Amino acids participate in several critical processes in the biology of trypanosomatids, such as osmoregulation, cell differentiation, and host cell invasion. Some of them provide reducing power for mitochondrial ATP synthesis. It was previously shown that alanine, which is formed mainly by the amination of pyruvate, is a metabolic end product formed when parasites are replicating in a medium rich in glucose and amino acids. It was shown as well that this amino acid can also be used for the regulation of cell volume and resistance to osmotic stress. In this work, we demonstrate that, despite it being an end product of its metabolism, ''Trypanosoma cruzi'' can take up and metabolize l-Ala through a low-specificity nonstereoselective active transport system. The uptake was dependent on the temperature in the range between 10 and 40°C, which allowed us to calculate an activation energy of 66.4 kJ/mol and estimate the number of transporters per cell at ~436,000. We show as well that, once taken up by the cells, l-Ala can be completely oxidized to CO2, supplying electrons to the electron transport chain, maintaining the electrochemical proton gradient across the mitochondrial inner membrane, and supporting ATP synthesis in ''T. cruzi'' epimastigotes. Our data demonstrate a dual role for Ala in the parasite's bioenergetics, by being a secreted end product of glucose catabolism and taken up as nutrient for oxidative mitochondrial metabolism.It is well known that trypanosomatids such as the etiological agent of Chagas' disease, ''Trypanosoma cruzi'', produce alanine as a main end product of their energy metabolism when they grow in a medium containing glucose and amino acids. In this work, we investigated if under starvation conditions (which happen during the parasite life cycle) the secreted alanine could be recovered from the extracellular medium and used as an energy source. Herein we show that indeed, in parasites submitted to metabolic stress, this metabolite can be taken up and used as an energy source for ATP synthesis, allowing the parasite to extend its survival under starvation conditions. The obtained results point to a dual role for Ala in the parasite's bioenergetics, by being a secreted end product of glucose catabolism and taken up as nutrient for oxidative mitochondrial metabolism.up as nutrient for oxidative mitochondrial metabolism.)
Guitart 2010 J Biol Chem + (Aminoacyl-tRNA synthetases (ARS) are modul … Aminoacyl-tRNA synthetases (ARS) are modular enzymes that aminoacylate transfer RNAs (tRNA) for their use by the ribosome during protein synthesis. ARS are essential and universal components of the genetic code that were almost completely established before the appearance of the last common ancestor of all living species. This long evolutionary history explains the growing number of functions being discovered for ARS, and for ARS homologues, beyond their canonical role in gene translation. Here we present a previously uncharacterized paralogue of seryl-tRNA synthetase named SLIMP (seryl-tRNA synthetase-like insect mitochondrial protein). SLIMP is the result of a duplication of a mitochondrial seryl-tRNA synthetase (SRS) gene that took place in early metazoans and was fixed in Insecta. Here we show that SLIMP is localized in the mitochondria, where it carries out an essential function that is unrelated to the aminoacylation of tRNA. The knockdown of SLIMP by RNA interference (RNAi) causes a decrease in respiration capacity and an increase in mitochondrial mass in the form of aberrant mitochondria.mass in the form of aberrant mitochondria.)
Kumar 2021 JCI Insight + (Ammonia is a cytotoxic metabolite with ple … Ammonia is a cytotoxic metabolite with pleiotropic molecular and metabolic effects, including senescence induction. During dysregulated ammonia metabolism, which occurs in chronic diseases, skeletal muscle becomes a major organ for nonhepatocyte ammonia uptake. Muscle ammonia disposal occurs in mitochondria via cataplerosis of critical intermediary metabolite α-ketoglutarate, a senescence-ameliorating molecule. Untargeted and mitochondrially targeted data were analyzed by multiomics approaches. These analyses were validated experimentally to dissect the specific mitochondrial oxidative defects and functional consequences, including senescence. Responses to ammonia lowering in myotubes and in hyperammonemic portacaval anastomosis rat muscle were studied. Whole-cell transcriptomics integrated with whole-cell, mitochondrial, and tissue proteomics showed distinct temporal clusters of responses with enrichment of oxidative dysfunction and senescence-related pathways/proteins during hyperammonemia and after ammonia withdrawal. Functional and metabolic studies showed defects in electron transport chain complexes I, III, and IV; loss of supercomplex assembly; decreased ATP synthesis; increased free radical generation with oxidative modification of proteins/lipids; and senescence-associated molecular phenotype-increased β-galactosidase activity and expression of p16INK, p21, and p53. These perturbations were partially reversed by ammonia lowering. Dysregulated ammonia metabolism caused reversible mitochondrial dysfunction by transcriptional and translational perturbations in multiple pathways with a distinct skeletal muscle senescence-associated molecular phenotype.senescence-associated molecular phenotype.)
Chowdhury 2000 Clin Chim Acta + (Amniocytes represent a population of foeta … Amniocytes represent a population of foetal cells that can be used for prenatal diagnosis in families with suspected mitochondrial oxidative phosphorylation (OXPHOS) defects. In this paper, we present a complex protocol for evaluation of the function of mitochondrial OXPHOS enzymes in cultured amniocytes using three independent and complementary methods: (a) spectrophotometry as a tool for determination of the capacities of mitochondrial respiratory-chain enzymes (NADH ubiquinone oxidoreductase, succinate- and glycerophosphate cytochrome c reductase, cytochrome c oxidase and citrate synthase); (b) polarography as a tool for the evaluation of mitochondrial OXPHOS enzyme functions in situ using digitonin-permeabilised amniocytes (rotenone-sensitive oxidation of pyruvate+malate, antimycin A-sensitive oxidation of succinate, KCN-sensitive oxidation of cytochrome c, ADP-activated substrate oxidation) and (c) cytofluorometric determination of tetramethyl rhodamine methyl ester (TMRM) fluorescence in digitonin-permeabilised amniocytes as a sensitive way to determine the mitochondrial membrane potential under steady-state conditions (state 4 with succinate). These protocols are presented together with reference control values using 9–22 independent cultures of amniocytes.g 9–22 independent cultures of amniocytes.)
Pozenel 2019 Cells + (Amniotic cells show exciting stem cell fea … Amniotic cells show exciting stem cell features, which has led to the idea of using living cells of human amniotic membranes (hAMs) in toto for clinical applications. However, under common cell culture conditions, viability of amniotic cells decreases rapidly, whereby reasons for this decrease are unknown so far. Recently, it has been suggested that loss of tissue tension ''in vivo'' leads to apoptosis. Therefore, the aim of this study was to investigate the effect of tissue distention on the viability of amniotic cells ''in vitro''. Thereby, particular focus was put on vital mitochondria-linked parameters, such as respiration and ATP synthesis. Biopsies of hAMs were incubated for 7-21 days either non-distended or distended. We observed increased B-cell lymphoma 2-associated X protein (BAX)/B-cell lymphoma (BCL)-2 ratios in non-distended hAMs at day seven, followed by increased caspase 3 expression at day 14, and, consequently, loss of viability at day 21. In contrast, under distention, caspase 3 expression increased only slightly, and mitochondrial function and cellular viability were largely maintained. Our data suggest that a mechano-sensing pathway may control viability of hAM cells by triggering mitochondria-mediated apoptosis upon loss of tension ''in vitro''. Further studies are required to elucidate the underlying molecular mechanisms between tissue distention and viability of hAM cells.sue distention and viability of hAM cells.)
Antona 2023 Cell Death Discov + (Among all cancers, colorectal cancer (CRC) … Among all cancers, colorectal cancer (CRC) is the 3rd most common and the 2nd leading cause of death worldwide. New therapeutic strategies are required to target cancer stem cells (CSCs), a subset of tumor cells highly resistant to present-day therapy and responsible for tumor relapse. CSCs display dynamic genetic and epigenetic alterations that allow quick adaptations to perturbations. Lysine-specific histone demethylase 1A (KDM1A also known as LSD1), a FAD-dependent H3K4me1/2 and H3K9me1/2 demethylase, was found to be upregulated in several tumors and associated with a poor prognosis due to its ability to maintain CSCs staminal features. Here, we explored the potential role of KDM1A targeting in CRC by characterizing the effect of KDM1A silencing in differentiated and CRC stem cells (CRC-SCs). In CRC samples, KDM1A overexpression was associated with a worse prognosis, confirming its role as an independent negative prognostic factor of CRC. Consistently, biological assays such as methylcellulose colony formation, invasion, and migration assays demonstrated a significantly decreased self-renewal potential, as well as migration and invasion potential upon KDM1A silencing. Our untargeted multi-omics approach (transcriptomic and proteomic) revealed the association of KDM1A silencing with CRC-SCs cytoskeletal and metabolism remodeling towards a differentiated phenotype, supporting the role of KDM1A in CRC cells stemness maintenance. Also, KDM1A silencing resulted in up-regulation of miR-506-3p, previously reported to play a tumor-suppressive role in CRC. Lastly, loss of KDM1A markedly reduced 53BP1 DNA repair foci, implying the involvement of KDM1A in the DNA damage response. Overall, our results indicate that KDM1A impacts CRC progression in several non-overlapping ways, and therefore it represents a promising epigenetic target to prevent tumor relapse.pigenetic target to prevent tumor relapse.)
Gnaiger 2013 Abstract Mito2013 + (Among all humans, the Polar Inuit of Thule … Among all humans, the Polar Inuit of Thule and Qaarnaak in Greenland are the northernmost population, limited to 302 in 1950 and dwindling to 180 in 2004. This human heritage of a culture and physiological type is endangered not only by a historical politically forced limitation of their territory, but by the current effects of global environmental pollution and climate change, causing social destabilization and a shift towards an unhealthy sedentary life style in contrast to the traditional active life style of Inuit hunters. 10 years ago the uncoupling hypothesis was presented for mitochondrial haplogroups of arctic populations suggesting that lower coupling of mitochondrial respiration to ATP production was selected for in favour of higher heat dissipation as an adaptation to cold climates [1,2]. It has been hypothesized that climatic pressures exerted selection for mitochondrial haplogroups in arctic populations as an adaptation to the cold, by increasing heat production through a higher mitochondrial proton leak. We studied muscle mitochondrial function in traditional Inuit hunters from Qaarnaak, Northern Greenland and sedentary Caucasian Danes who engaged in a 42 day ski sojourn across the polar ice caps (80-82o latitude). Small muscle biopsies were obtained from the leg (vastus lateralis) and arm (deltoid) muscles in both Inuit and Danes and mitochondrial function was assessed by high-resolution respirometry [3,4]. OXPHOS capacity in the leg was lower in Inuit compared to Danes consistent with differences in mitochondrial density. Nonetheless, Inuit had a higher OXPHOS capacity with fat substrate in both leg and arm muscles. LEAK respiration was proportionate with OXPHOS such that coupling control was equivalent between groups and across muscles of both arm and leg. After 42 days of skiing Danes demonstrated adaptive substrate control through an increase in fatty acid oxidation towards levels of the Inuit. Biochemical coupling efficiency was preserved across variations in mtDNA, muscle fibre type, uncoupling protein-3 content, muscle OXPHOS capacity, leg and arm muscle, and acclimatization level. This study refutes the hypothesis that uncoupling is higher in skeletal muscle of arctic haplotype populations and reveals that mitochondrial coupling control is tightly conserved across haplotype groups and training status despite large adaptive capacities for substrate oxidation.aptive capacities for substrate oxidation.)
Francisco 2018 J Neurochem + (Among mitochondrial NADP-reducing enzymes, … Among mitochondrial NADP-reducing enzymes, nicotinamide nucleotide transhydrogenase (NNT) establishes an elevated matrix NADPH/NADP+ by catalyzing the reduction of NADP+ at the expense of NADH oxidation coupled to inward proton translocation across the inner mitochondrial membrane. Here, we characterize NNT activity and mitochondrial redox balance in the brain using a congenic mouse model carrying the mutated ''Nnt'' gene from the C57BL/6J strain. The absence of NNT activity resulted in lower total NADPH sources activity in the brain mitochondria of young mice, an effect that was partially compensated in aged mice. Nonsynaptic mitochondria showed higher NNT activity than synaptic mitochondria. In the absence of NNT, an increased release of H2O2 from mitochondria was observed when the metabolism of respiratory substrates occurred with restricted flux through relevant mitochondrial NADPH sources or when respiratory complex I was inhibited. In accordance, mitochondria from ''Nnt''-/- brains were unable to sustain NADP in its reduced state when energized in the absence of carbon substrates, an effect aggravated after H2O2 bolus metabolism. These data indicate that the lack of NNT in brain mitochondria impairs peroxide detoxification, but peroxide detoxification can be partially counterbalanced by concurrent NADPH sources depending on substrate availability. Notably, only brain mitochondria from ''Nnt''-/- mice chronically fed a high-fat diet exhibited lower activity of the redox-sensitive aconitase, suggesting that brain mitochondrial redox balance requires NNT under the metabolic stress of a high-fat diet. Overall, the role of NNT in the brain mitochondria redox balance especially comes into play under mitochondrial respiratory defects or high-fat diet. This article is protected by copyright. All rights reserved.ay under mitochondrial respiratory defects or high-fat diet. This article is protected by copyright. All rights reserved.)
Sharma 2023 Biosci Biotechnol Biochem + (Among the branched chain amino acids (BCAA … Among the branched chain amino acids (BCAAs), leucine and isoleucine have been well-studied for their roles in improving mitochondrial function and reducing oxidative stress. However, role of valine in mitochondrial function regulation and oxidative stress management remains elusive. This study investigated valine effect on mitochondrial function and oxidative stress ''in vitro''. Valine increased expression of genes involved in mitochondrial biogenesis and dynamics. It upregulates mitochondrial function at Complexes I, II and IV levels of electron transport chain. Flow cytometry studies revealed, valine reduced oxidative stress by significantly lowering mitochondrial reactive oxygen species (ROS) and protein expression of 4 hydroxynonenal. Functional role of valine against oxidative stress was analyzed by XFe96 Analyzer. Valine sustained oxidative phosphorylation and improved ATP generation rates during oxidative stress. In conclusion, our findings shed more light on the critical function of valine in protecting mitochondrial function thereby preventing mitochondrial/cellular damage induced by oxidative stress.llular damage induced by oxidative stress.)
Foriel 2015 Abstract MiP2015 + (Among the wide range of mitochondrial diso … Among the wide range of mitochondrial disorders, defects in the oxidative phosphorylation (OxPhos) are the most prevalent. OxPhos deficiencies often lead to early death and are associated with severe and highly variable clinical symptoms. Despite intense efforts in the comprehension of the mechanisms underlying mitochondrial disorders, patients are still without effective treatment. The need of predictive ''in vivo'' models of the pathology is an important issue in the development of new therapeutics in order to study their therapeutic potential, toxicity and pharmacokinetics. Due to the extreme genetic and phenotypic heterogeneity of OxPhos disorders one cannot rely on a single in ''vivo model''. Here we present the method and strategy we use to create, characterize and validate a set of ''Drosophila melanogaster'' models of nuclear DNA-encoded OxPhos subunits and preliminary results of systematic evaluation of Khondrion´s lead compound. We primarily focus on complex I by knocking down the core and accessory subunits the most prone to mutation in patients and selecting phenotypes-readouts suitable for drug screening (death at critical stages of development, survival curves, ROS level).These models will represent a valuable tool with predictive power to evaluate new potential therapeutics as an initial step in the drug development process.tial step in the drug development process.)
Kohoutova 2018 Physiol Res + (Ample experimental evidence suggests that … Ample experimental evidence suggests that sepsis could interfere with any mitochondrial function; however, the true role of mitochondrial dysfunction in the pathogenesis of sepsis-induced multiple organ dysfunction is still a matter of controversy. This review is primarily focused on mitochondrial oxygen consumption in various animal models of sepsis in relation to human disease and potential sources of variability in experimental results documenting decrease, increase or no change in mitochondrial respiration in various organs and species. To date, at least three possible explanations of sepsis-associated dysfunction of the mitochondrial respiratory system and consequently impaired energy production have been suggested: 1. Mitochondrial dysfunction is secondary to tissue hypoxia. 2. Mitochondria are challenged by various toxins or mediators of inflammation that impair oxygen utilization (cytopathic hypoxia). 3. Compromised mitochondrial respiration could be an active measure of survival strategy resembling stunning or hibernation. To reveal the true role of mitochondria in sepsis, sources of variability of experimental results based on animal species, models of sepsis, organs studied, or analytical approaches should be identified and minimized by the use of appropriate experimental models resembling human sepsis, wider use of larger animal species in preclinical studies, more detailed mapping of interspecies differences and organ-specific features of oxygen utilization in addition to use of complex and standardized protocols evaluating mitochondrial respiration.cols evaluating mitochondrial respiration.)
Greenway 2019 J Evol Biol + (Ample sperm production is essential for su … Ample sperm production is essential for successful male reproduction in many species. The amount of sperm a male can produce is typically constrained by the size of his testes, which can be energetically expensive to grow and maintain. Whilst the economics of ejaculate allocation has been the focus of much theoretical and empirical literature, relatively little attention has been paid to individual adult variation and plasticity at the source of sperm production, the testes themselves. We experimentally address this issue using the insect ''Narnia femorata'' Stål (Hemiptera: Coreidae). We established the metabolic cost of testicular tissue, then quantified variation in individual testes mass in response to multiple mate quality and quantity treatments. We uncovered extreme variation across individuals and considerable short-term effects of mating activity on testes dry mass. Importantly, the observed variation in testes mass was associated with notable fitness consequences; females paired with males with larger testes had greater hatching success. Overall, pairing with a female resulted in a 11% reduction in dry testes mass. Despite this apparent considerable mating investment, we found no evidence of strategic allocation to higher quality females or longer-term changes in testes mass. The dynamic nature of testes mass and its metabolic cost is vital to consider in the context of re-mating rates, polyandry benefits and general mating system dynamics both in this species and more broadly.© 2019 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2019 European Society For Evolutionary Biology.ropean Society For Evolutionary Biology.)
Miwa 2015 Free Radic Biol Med + (Amplex Red is a fluorescent probe that is … Amplex Red is a fluorescent probe that is widely used to detect hydrogen peroxide (H2O2) in a reaction where it is oxidised to resorufin by horseradish peroxidase (HRP) as a catalyst. This assay is highly rated amongst other similar probes thanks to its superior sensitivity and stability. However, we report here that Amplex Red is readily convertedto resorufin by a carboxylesterase without requiring H2O2, horseradish peroxidase or oxygen: this reaction is seen in various tissue samples such as liver and kidney as well as in cultured cells, causing a serious distortion of H2O2 measurements. The reaction can be inhibited by Phenylmethyl sulfonyl fluoride (PMSF) at concentrations which do not disturb mitochondrial function nor the ability of the Amplex Red-HRP system to detect H2O2. ''In vitro'' experiments and ''in silico'' docking simulations indicate that carboxylesterases 1 and 2 recognise Amplex Red with the same kinetics as carboxylesterase-containing mitochondria. We propose two different approaches to correct for this problem and re-evaluate the commonly performed experimental procedure for the detection of H2O2 release from isolated liver mitochondria. Our results call for a serious re-examination of previous data.on of H2O2 release from isolated liver mitochondria. Our results call for a serious re-examination of previous data.)
Dębski 2016 Free Radic Biol Med + (Amplex® Red (10-acetyl-3,7-dihydroxyphenox … Amplex® Red (10-acetyl-3,7-dihydroxyphenoxazine) is a fluorogenic probe widely used to detect and quantify hydrogen peroxide in biological systems. Detection of hydrogen peroxide is based on peroxidase-catalyzed oxidation of Amplex® Red to resorufin. In this study we investigated the mechanism of one-electron oxidation of Amplex® Red and we present the spectroscopic characterization of transient species formed upon the oxidation. Oxidation process has been studied by a pulse radiolysis technique with one-electron oxidants (N3(•), CO3(•-),(•)NO2 and GS(•)). The rate constants for the Amplex® Red oxidation by N3(•) ((2)k=2.1·10(9)M(-1)s(-1), at pH=7.2) and CO3(•-) ((2)k=7.6·10(8)M(-1)s(-1), at pH=10.3) were determined. Two intermediates formed during the conversion of Amplex® Red into resorufin have been characterized. Based on the results obtained, the mechanism of transformation of Amplex® Red into resorufin, involving disproportionation of the Amplex® Red-derived radical species, has been proposed. The results indicate that peroxynitrite-derived radicals, but not peroxynitrite itself, are capable to oxidize Amplex® Red to resorufin. We also demonstrate that horseradish peroxidase can catalyze oxidation of Amplex® Red not only by hydrogen peroxide, but also by peroxynitrite, which needs to be considered when employing the probe for hydrogen peroxide detection.the probe for hydrogen peroxide detection.)
Lopez 2017 Sci Rep + (Amyloid precursor protein (APP) and its ex … Amyloid precursor protein (APP) and its extracellular domain, soluble APP alpha (sAPPα) play important physiological and neuroprotective roles. However, rare forms of familial Alzheimer's disease are associated with mutations in APP that increase toxic amyloidogenic cleavage of APP and produce amyloid beta (Aβ) at the expense of sAPPα and other non-amyloidogenic fragments. Although mitochondrial dysfunction has become an established hallmark of neurotoxicity, the link between Aβ and mitochondrial function is unclear. In this study we investigated the effects of increased levels of neuronal APP or Aβ on mitochondrial metabolism and gene expression, in human SH-SY5Y neuroblastoma cells. Increased non-amyloidogenic processing of APP, but not Aβ, profoundly decreased respiration and enhanced glycolysis, while mitochondrial DNA (mtDNA) transcripts were decreased, without detrimental effects to cell growth. These effects cannot be ascribed to Aβ toxicity, since higher levels of endogenous Aβ in our models do not cause oxidative phosphorylation (OXPHOS) perturbations. Similarly, chemical inhibition of β-secretase decreased mitochondrial respiration, suggesting that non-amyloidogenic processing of APP may be responsible for mitochondrial changes. Our results have two important implications, the need for caution in the interpretation of mitochondrial perturbations in models where APP is overexpressed, and a potential role of sAPPα or other non-amyloid APP fragments as acute modulators of mitochondrial metabolism.te modulators of mitochondrial metabolism.)
Krako 2016 Abstract MitoFit Science Camp 2016 + (Amyloid β oligomers (AβOs) are crucially i … Amyloid β oligomers (AβOs) are crucially involved in Alzheimer’s disease (AD). They are still ˝mysterious entities˝ in terms of their precise molecular composition, their in-cell formation, traffic and actions. We have recently established a subcellularly localized conformational-selective interference approach, based on the expression of an intrabody against AβOs in the endoplasmic reticulum (ER) [1]. This intrabody is a recombinant antibody domain (scFvA13), previously isolated in our laboratory, that selectively binds to AβOs, with high selectivity and specificity with respect to Aβ monomeric species or fibrils [2]. For these studies, we exploited the 7PA2 cells (familial AD CHO cell model), the gold standard for natural AβOs production. Mitochondrial membrane potential was evaluated following the mitochondrial electrophoretic accumulation of the membrane permeable fluorescent cationic probe JC-1. Mitochondrial respiration was measured by high-resolution respirometry in intact and permeabilized cells. The concentration of ATP was quantified by chemiluminometry under basal cell metabolic conditions. Recently, we described that 7PA2 cells have another characteristic relevant to Alzheimer’s disease – a severe mitochondrial dysfunction, due to a chronic AβOs exposure and production [3]. We have newly established cell line, the 7PA2-A13K, as the model for conformational-selective interference with AβOs inside the endoplasmic reticulum (ER). These cells show a significantly lower level of secreted AβOs, without their intracellular accumulation and most importantly, through this modulatory effects on the levels and assembly of AβOs, a strong rescue of mitochondrial dysfunctions and bioenergetic deficit occurs (Figure 1). These data provide an important evidence for the fact that the AβOs are formed inside a cell, precisely in the ER, from where they exert their toxic action on mitochondrial physiology. These data contribute to the recent findings about the importance of the ER – mitochondria interplay in the pathogenesis of Alzheimer’s disease and highlight the subcellular compartment, called MAM – mitochondria associated ER membranes - as an important cellular target for the intracellular actions of AβOs. Future studies, that will extend these findings from a well defined cell model to neurons and, possibly to human neurons, will have to take into account the importance of organelle continuity and cross-talk for the cell homeostasis and AD pathology. From a methodological point of view, these results provide the first example of a functional experimental approach, conformational selective interference (CSI), that could find many applications for the studies of protein modifications ''in vivo''.dies of protein modifications ''in vivo''.)
Ng 2019 J Biol Chem + (Amyloid β1-42 (Aβ1-42) peptide is involved … Amyloid β1-42 (Aβ1-42) peptide is involved in Alzheimer's disease (AD) pathogenesis and is prone to glycation, an irreversible process resulting in proteins with accumulated advanced glycated end products (AGEs). Nε-(carboxyethyl)lysine (CEL) is a common AD-associated AGE, occurring at either Lys-16 or Lys-28 of Aβ1-42. Methylglyoxal is commonly used for the unspecific glycation of Aβ1-42, which results in a complex mixture of AGE-modified peptides and makes interpretation of a causative AGE at a specific amino acid residue difficult. Here, we addressed this challenge by chemically synthesizing defined CEL glycations on Aβ1-42 at Lys-16 (Aβ-CEL16), Lys-28 (Aβ-CEL28), and both Lys-16 and -28 (Aβ-CEL16&28). We demonstrate that the double CEL glycation at Lys-16/28 of Aβ1-42 had the most profound impact on amyloid fibril formation. ''In silico'' predictions indicated that Aβ-CEL16&28 had a substantially decreased free-energy change, contributing to fibril destabilization, and a decreased aggregation rate. Single CEL glycations at Lys-28 had the least impact on fibril formation, and Lys-16 CEL glycations delayed fibril formation. We also tested these peptides for neuronal toxicity and impact on mitochondrial function in a retinoic acid-differentiated SH-SY5Y human neuroblastoma cell line and found that only Aβ-CEL16 and Aβ-CEL28 are neurotoxic, possibly through a non-mitochondrial pathway, whereas Aβ-CEL16&28 is not neurotoxic. Interestingly, Aβ-CEL16&28 depolarized the mitochondrial membrane potential, and Aβ-CEL16 increased mitochondrial respiration at complex II, possibly indicating mitophagy or an alternative metabolic route, respectively. In summary, our results provide insights relevant for potential therapeutic approaches against neurotoxic CEL glycated Aβ1-42.Published under license by The American Society for Biochemistry and Molecular Biology, Inc.ety for Biochemistry and Molecular Biology, Inc.)
Souza da Silva 2020 Mol Neurobiol + (Amyloid-β oligomers (AβOs) toxicity causes … Amyloid-β oligomers (AβOs) toxicity causes mitochondrial dysfunction, leading to synaptic failure in Alzheimer's disease (AD). Considering presynaptic high energy demand and tight Ca2+ regulation, impairment of mitochondrial function can lead to deteriorated neural activity and cell death. In this study, an AD mouse model induced by ICV (intracerebroventricular) injection of AβOs was used to investigate the toxicity of AβOs on presynaptic function. As a therapeutic approach, GUO (guanosine) was given by oral route to evaluate the neuroprotective effects on this AD model. Following 24 h and 48 h from the model induction, behavioral tasks and biochemical analyses were performed, respectively. AβOs impaired object recognition (OR) short-term memory and reduced glutamate uptake and oxidation in the hippocampus. Moreover, AβOs decreased spare respiratory capacity, reduced ATP levels, impaired Ca2+ handling, and caused mitochondrial swelling in hippocampal synaptosomes. Guanosine crossed the BBB, recovered OR short-term memory, reestablished glutamate uptake, recovered mitochondrial Ca2+ homeostasis, and partially prevented mitochondrial swelling. Therefore, this endogenous purine presented a neuroprotective effect on presynaptic mitochondria and should be considered for further studies in AD models.nsidered for further studies in AD models.)
Cacabelos 2016 Acta Neuropathol Commun + (Amyotrophic lateral sclerosis (ALS) is a m … Amyotrophic lateral sclerosis (ALS) is a motor neuron disease with a gender bias towards major prevalence in male individuals. Several data suggest the involvement of oxidative stress and mitochondrial dysfunction in its pathogenesis, though differences between genders have not been evaluated. For this reason, we analysed features of mitochondrial oxidative metabolism, as well as mitochondrial chain complex enzyme activities and protein expression, lipid profile, and protein oxidative stress markers, in the Cu,Zn superoxide dismutase with the G93A mutation (hSOD1-G93A)- transgenic mice and Neuro2A(N2A) cells overexpressing hSOD1-G93A.Our results show that overexpression of hSOD1-G93A in transgenic mice decreased efficiency of mitochondrial oxidative phosphorylation, located at complex I, revealing a temporal delay in females with respect to males associated with a parallel increase in selected markers of protein oxidative damage. Further, females exhibit a fatty acid profile with higher levels of docosahexaenoic acid at 30 days. Mechanistic studies showed that hSOD1-G93A overexpression in N2A cells reduced complex I function, a defect prevented by 17β-estradiol pretreatment. In conclusion, ALS-associated SOD1 mutation leads to delayed mitochondrial dysfunction in female mice in comparison with males, in part attributable to the higher oestrogen levels of the former. This study is important in the effort to further understanding of whether different degrees of spinal cord mitochondrial dysfunction could be disease modifiers in ALS.unction could be disease modifiers in ALS.)
Magri 2022 Abstract Bioblast + (Amyotrophic lateral sclerosis (ALS) is a f … Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease which affects motor neurons (MNs). Many familial and sporadic forms correlate with mutations in the gene encoding the antioxidant enzyme Cu/Zn Superoxide Dismutase (SOD1). Among mutants, the dismutase-active SOD1 G93A forms toxic aggregates on the cytosolic surface of outer mitochondrial membrane (OMM), using the Voltage-Dependent Anion Channel 1 (VDAC1) as binding site [1]. VDAC1 is the most abundant OMM pore-forming protein and allows the trafficking of metabolites (pyruvate, malate), ions, NAD+/NADH and ATP/ADP across the membrane; furthermore, it serves as an anchor for many cytosolic proteins, mostly for Hexokinases (HKs) [2]. However, in ALS MNs, the mitochondrial accumulation of SOD1 G93A impairs molecules exchange through VDAC1 and displaces HKs from mitochondria, promoting the organelle dysfunction and cell death [1-2].By a means of ''in vitro'' and ''in cellulo'' approaches, we previously demonstrated that HK1 and SOD1 G93A compete for the same mitochondrial binding site, VDAC1 [3]. Based on these observations, we developed a small synthetic peptide corresponding to the first 11 amino acid residues of the HK1 N-terminal domain (NHK1) [3]. NHK1 is able to modulates VDAC1 activity when it is reconstituted in artificial membranes; when added to ALS MNs, the peptide promotes a complete recovery of the cell viability in a dose-response manner [3-4]. By using High-Resolution Respirometry (HRR), we then analyzed the mitochondrial respiration profile of MN-like cells NSC34 stably expressing SOD1 G93A. Our results indicate that NHK1 promotes a partial increase of oxygen consumption corresponding to ROUTINE and OXPHOS state. As demonstrated by FCRs analysis, the peptide stimulates a significative decrease of the LEAK respiration while increases net respiration and coupling efficiency linked to OXPHOS state [4]. This effect is probably due to the reduction of ~70 % of VDAC1-SOD1 G93A aggregates observed in the mitochondrial fraction of cells treated with NHK1 [4].In conclusion, our results suggest that NHK1 drives the recovery of compromised mitochondrial respiration typical of ALS and provide new insights into the development of therapeutic molecules to fight the disease. Overall, our work helps to better understand the relationship between altered mitochondrial metabolism and MNs death.# Israelson A, Arbel N, da Cruz S, Ilieva H, Yamanaka K, Shoshan-Barmatz V, Cleveland DW (2010) Misfolded mutant SOD1 directly inhibits VDAC1 conductance in a mouse model of inherited ALS. https://doi.org/10.1016/j.neuron.2010.07.019# Magrì A, Reina S, De Pinto V (2018) VDAC1 as pharmacological target in cancer and neurodegeneration: focus on its role in apoptosis. https://doi.org/10.3389/fchem.2018.00108# Magrì A, Belfiore R, Reina S, Tomasello MF, Di Rosa MC, Guarino F, Leggio L, De Pinto V, Messina A (2016) Hexokinase I N-terminal based peptide prevents the VDAC1-SOD1 G93A interaction and re-establishes ALS cell viability. https://doi.org/10.1038/srep34802# Magrì A, Risiglione P, Caccamo A, Formicola B, Tomasello MF, Arrigoni C, Zimbone S, Guarino F, Re F, Messina A (2021) Small Hexokinase 1 peptide against toxic SOD1 G93A mitochondrial accumulation in ALS rescues the ATP-related respiration. https://doi.org/10.3390/biomedicines9080948ration. https://doi.org/10.3390/biomedicines9080948 )
Miquel 2014 Free Radic Biol Med + (Amyotrophic lateral sclerosis (ALS) is a f … Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by motor neuron degeneration that ultimately results in progressive paralysis and death. Growing evidence indicates that mitochondrial dysfunction and oxidative stress contribute to motor neuron degeneration in ALS. To further explore the hypothesis that mitochondrial dysfunction and nitroxidative stress contribute to disease pathogenesis at the ''in vivo'' level, we assessed whether the mitochondria-targeted antioxidant [10-(4,5-dimethoxy-2-methyl-3,6-dioxo-1,4- cyclohexadien-1-yl)decyl]triphenylphosphonium methanesulfonate (MitoQ) can modify disease progression in the SOD1G93A mouse model of ALS. To do this, we administered MitoQ (500µM) in the drinking water of SOD1G93A mice from a time when early symptoms of neurodegeneration become evident at 90 days of age until death. This regime is a clinically plausible scenario and could be more easily translated to patients as this corresponds to initiating treatment of patients after they are first diagnosed with ALS. MitoQ was detected in all tested tissues by liquid chromatography/mass spectrometry after 20 days of administration. MitoQ treatment slowed the decline of mitochondrial function, both in the spinal cord and quadriceps muscle as measured by high-resolution respirometry. Importantly, nitroxidative markers and pathological signs in the spinal cord of MitoQ-treated animals were markedly reduced and neuromuscular junctions were recovered associated to a significant increase in hind-limb strength. Finally, MitoQ treatment significantly prolonged the lifespan of SOD1G93A mice. Our results support a role for mitochondrial nitroxidative damage and dysfunction in the pathogenesis of ALS and suggest that mitochondria-targeted antioxidants may be of pharmacological use for ALS treatment. of pharmacological use for ALS treatment.)
Ladd 2017 Brain Res + (Amyotrophic lateral sclerosis (ALS) is a g … Amyotrophic lateral sclerosis (ALS) is a generally fatal neurodegenerative disease of adults that produces weakness and atrophy due to dysfunction and death of upper and lower motor neurons. We used RNA-sequencing (RNA-seq) to analyze expression of all mitochondrial DNA (mtDNA)-encoded respiratory genes in ALS and CTL human cervical spinal cords (hCSC) and isolated motor neurons. We analyzed with RNA-seq mtDNA gene expression in human neural stem cells (hNSC) exposed to recombinant human mitochondrial transcription factor A (rhTFAM), visualized in 3-dimensions clustered gene networks activated by rhTFAM, quantitated their interactions with other genes and determined their gene ontology (GO) families. RNA-seq and quantitative PCR (qPCR) analyses showed reduced mitochondrial gene expression in ALS hCSC and ALS motor neurons isolated by laser capture microdissection (LCM), and revealed that hNSC and CTL human cervical spinal cords were similar. Rats treated with i.v. rhTFAM showed a dose-response increase in brain respiration and an increase in spinal cord mitochondrial gene expression. Treatment of hNSC with rhTFAM increased expression of mtDNA-encoded respiratory genes and produced one major and several minor clusters of gene interactions. Gene ontology (GO) analysis of rhTFAM-stimulated gene clusters revealed enrichment in GO families involved in RNA and mRNA metabolism, suggesting mitochondrial-nuclear signaling. In postmortem ALS hCSC and LCM-isolated motor neurons we found reduced expression of mtDNA respiratory genes. In hNSC's rhTFAM increased mtDNA gene expression and stimulated mRNA metabolism by unclear mechanisms. rhTFAM may be useful in improving bioenergetic function in ALS.Copyright © 2017 Elsevier B.V. All rights reserved. © 2017 Elsevier B.V. All rights reserved.)
Martinez-Palma 2018 Neurotherapeutics + (Amyotrophic lateral sclerosis (ALS) is a f … Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by motor neuron (MN) degeneration and gliosis. Neonatal astrocytes obtained from the SOD1G93A rat model of ALS exhibit mitochondrial dysfunction and neurotoxicity that can be reduced by dichloroacetate (DCA), a metabolic modulator that has been used in humans, and shows beneficial effects on disease outcome in SOD1G93A mice. Aberrant glial cells (AbGC) isolated from the spinal cords of adult paralytic SOD1G93A rats exhibit highly proliferative and neurotoxic properties and may contribute to disease progression. Here we analyze the mitochondrial activity of AbGC and whether metabolic modulation would modify their phenotypic profile. Our studies revealed fragmented mitochondria and lower respiratory control ratio in AbGC compared to neonatal SOD1G93A and nontransgenic rat astrocytes. DCA (5 mM) exposure improved AbGC mitochondrial function, reduced their proliferative rate, and importantly, decreased their toxicity to MNs. Furthermore, oral DCA administration (100 mg/kg, 10 days) to symptomatic SOD1G93A rats reduced MN degeneration, gliosis, and the number of GFAP/S100β double-labeled hypertrophic glial cells in the spinal cord. DCA treatment of AbGC reduced extracellular lactate levels indicating that the main recognized DCA action, targeting the pyruvate dehydrogenase kinase/pyruvate dehydrogenase complex, may underlie our findings. Our results show that AbGC metabolic phenotype is related to their toxicity to MNs and indicate that its modulation can reduce glial mediated pathology in the spinal cord. Together with previous findings, these results further support glial metabolic modulation as a valid therapeutic strategy in ALS.on as a valid therapeutic strategy in ALS.)
Veyrat-Durebex 2019 Mol Neurobiol + (Amyotrophic lateral sclerosis (ALS) is cha … Amyotrophic lateral sclerosis (ALS) is characterized by a wide metabolic remodeling, as shown by recent metabolomics and lipidomics studies performed in samples from patient cohorts and experimental animal models. Here, we explored the metabolome and lipidome of fibroblasts from sporadic ALS patients (n = 13) comparatively to age- and sex-matched controls (n = 11), and the subcellular fraction containing the mitochondria and endoplasmic reticulum (mito-ER), given that mitochondrial dysfunctions and ER stress are important features of ALS patho-mechanisms. We also assessed the mitochondrial oxidative respiration and the mitochondrial genomic (mtDNA) sequence, although without yielding significant differences. Compared to controls, ALS fibroblasts did not exhibit a mitochondrial respiration defect nor an increased proportion of mitochondrial DNA mutations. In addition, non-targeted metabolomics and lipidomics analyses identified 124 and 127 metabolites, and 328 and 220 lipids in whole cells and the mito-ER fractions, respectively, along with partial least-squares-discriminant analysis (PLS-DA) models being systematically highly predictive of the disease. The most discriminant metabolomic features were the alteration of purine, pyrimidine, and energetic metabolisms, suggestive of oxidative stress and of pro-inflammatory status. The most important lipidomic feature in the mito-ER fraction was the disturbance of phosphatidylcholine PC (36:4p) levels, which we had previously reported in the cerebrospinal fluid of ALS patients and in the brain from an ALS mouse model. Thus, our results reveal that fibroblasts from sporadic ALS patients share common metabolic remodeling, consistent with other metabolic studies performed in ALS, opening perspectives for further exploration in this cellular model in ALS.exploration in this cellular model in ALS.)
Tungtur 2021 Sci Rep + (Amyotrophic lateral sclerosis (ALS) remain … Amyotrophic lateral sclerosis (ALS) remains a devastating motor neuron disease with limited treatment options. Oxaloacetate treatment has a neuroprotective effect in rodent models of seizure and neurodegeneration. Therefore, we treated the ALS model superoxide dismutase 1 (SOD1) G93A mice with oxaloacetate and evaluated their neuromuscular function and lifespan. Treatment with oxaloacetate beginning in the presymptomatic stage significantly improved neuromuscular strength measured during the symptomatic stage in the injected mice compared to the non-treated group. Oxaloacetate treatment starting in the symptomatic stage significantly delayed limb paralysis compared with the non-treated group. For lifespan analysis, oxaloacetate treatment did not show a statistically significant positive effect, but the treatment did not shorten the lifespan. Mechanistically, SOD1YG93A mice showed increased levels of tumor necrosis factor-α (TNFα) and peroxisome proliferative activated receptor gamma coactivator 1α (PGC-1α) mRNAs in the spinal cord. However, oxaloacetate treatment reverted these abnormal levels to that of wild-type mice. Similarly, the altered expression level of total NF-κB protein returned to that of wild-type mice with oxaloacetate treatment. These results suggest that the beneficial effects of oxaloacetate treatment in SOD1G93A mice may reflect the effects on neuroinflammation or bioenergetic stress.> mice may reflect the effects on neuroinflammation or bioenergetic stress.)
Sauer 1979 Biochem J + (An NAD(P)+-dependent 'malic' enzyme is sho … An NAD(P)+-dependent 'malic' enzyme is shown to be present in mitochondria from small-intestinal mucosa. The intracellular location, activity and regulatory kinetic properties of the enzyme suggest that it participates in the major energy-producing pathway for net oxidation of glutamine-derived tricarboxylic acid-cycle intermediates.ed tricarboxylic acid-cycle intermediates.)
Nagel 1982 J Biol Chem + (An NAD(P)-dependent malic enzyme with a sp … An NAD(P)-dependent malic enzyme with a specific activity of 40.6 mumol of NADH/min/mg of protein and an isoelectric point of 5.4 was purified to apparent homogeneity from canine small intestinal mucosal mitochondria. The purification procedure employed ammonium sulfate fractionation, Sepharose CL 6B gel filtration, chromatography on DEAE-cellulose to remove the interfering malate dehydrogenase, and affinity chromatography on 2',5'-ADP-Sepharose and NAD-agarose to take advantage of the dual coenzyme specificity. Antibody prepared from the purified enzyme produced a single peak upon cross-rocket immunoelectrophoresis against the mitochondrial sonicate. Continuous polyacrylamide gel electrophoresis showed NAD and NADP activity co-migrating with the native protein band. A single band of protein having an apparent Mr = 62,000 was seen on sodium dodecyl sulfate electrophoresis. At pH 7.3, gel filtration revealed a single peak of activity with NAD and NADP corresponding to an apparent Mr = 282,000. Gradient gel polyacrylamide electrophoresis at pH 9.0 indicated an additional broad band of activity corresponding to a Mr = 141,000. Under physiological conditions therefore the protein appears to exist as a tetramer of Mr = 282,000 composed of four equal subunits, whereas at elevated pH values during electrophoresis, partial dissociation to a dimeric species occurs. dissociation to a dimeric species occurs.)
Marshall 1996 Am J Respir Cell Mol Biol + (An NADPH-oxidase complex containing at lea … An NADPH-oxidase complex containing at least two protein components (gp91-phox and p22-phox) and a unique low redox potential (-245 mV) cytochrome b-245 is the source of superoxide generated for bacterial killing in neutrophils and has been suggested as the oxygen sensor in the carotid body. In pure cultures of smooth muscle cells from calf small pulmonary arteries (300 microns diameter) the presence of the 91 kD protein specific to this cytochrome was demonstrated by Western blot analysis with monoclonal antibody 48. Low-temperature-difference spectrophotometry of homogenates of these cells demonstrated the characteristic cytochrome b-245 spectrum when titrated between redox potentials of -152 and -345 mV, consistent with the low redox potential form. When these same cells were exposed to hypoxia (approximately 40 mmHg), superoxide production increased significantly from 1.4 +/- 0.2 to 73 +/- 12 nmoles.min-1 mg-1 protein. Hypoxic generation of superoxide was inhibited by the NADPH-oxidase inhibitor diphenyleneiodonium (DPI: 10 microM) but not by the mitochondrial inhibitor myxathiazole (10 microM). The hypoxic superoxide increase was significantly greater than that observed from smooth muscle cells from large pulmonary arteries or from large or small systemic arteries. Fluorescence immunocytochemistry revealed the presence of the NADPH-oxidase protein in the walls of pulmonary arteries in rat lung slices, and confocal microscopy showed the complex to be widely distributed in the vicinity of the arterial smooth muscle walls. In hypoxia or norepinephrine (NP)-induced vasoconstriction of pulmonary artery rings from cats, the sensitivity to inhibition by DPI was observed to be significantly greater for hypoxia (ED50 = 0.8 microM) than for NP-induced (ED50 = 13.4 microM) constriction. Together these observations demonstrate that the unique cytochrome b-245 containing NADPH-oxidase is present in pulmonary artery smooth muscle and that an NADPH-oxidase or NADH-oxidoreductase complex is activated to release superoxide by hypoxic conditions. It is concluded that a trans-membrane NADPH-oxidase is the most likely and that activation of this system may be involved in the initiation of hypoxic pulmonary vasoconstriction.ion of hypoxic pulmonary vasoconstriction.)
Mendham 2015 Abstract MiPschool Cape Town 2015 + (An acute bout of exercise activates downst … An acute bout of exercise activates downstream signaling cascades that ultimately result in mitochondrial biogenesis [1]. Elucidating the molecular signaling cascades that stimulate exercise-induced mitochondrial biogenesis carries significance for the prevention of physical-inactivity related diseases [1]. Traditionally, research investigating exercise-induced mitochondrial biogenesis has employed continuous aerobic exercise as the experimental model [2]. An alternative to these more traditional training modes is intermittent running in the form of football-based small-sided games (SSG), which has been reported to improve metabolic health in clinical populations [3]. Accordingly, this study aimed to assess changes in molecular signaling cascades that stimulate mitochondria biogenesis in response to an acute bout of SSG and continuous cycling (CYC) in sedentary, middle-aged men.Nine middle-aged, sedentary but disease-free men completed two respective 40 min exercise bouts (CYC and SSG) in a randomized, cross-over order. Heart rate (HR) and Rating of Perceived Exertion (RPE) were collected during each bout. Venous blood was collected at fasting, immediately, 30, 60 and 240 min post-exercise for measurement of glucose, insulin, cortisol and lactate. Muscle samples were collected at rest, 30 and 240 min post-exercise for the analysis of total PGC-1α, SIRT1, p38MAPK, CAMKIIα and p53, and phosphorylated proteins, p53Ser15, p38Thr180, CAMKIIThr286, AMPKThr172 and p38MAPKThr180/Tyr182. mRNA expression included, PGC-1α, p53, NRF1, NRF2, Tfam and cytochrome c.t;Thr180/Tyr182. mRNA expression included, PGC-1α, p53, NRF1, NRF2, Tfam and cytochrome c.)
Kamberov 2013 Cell + (An adaptive variant of the human Ectodyspl … An adaptive variant of the human Ectodysplasin receptor, EDARV370A, is one of the strongest candidates of recent positive selection from genome-wide scans. We have modeled EDAR370A in mice and characterized its phenotype and evolutionary origins in humans. Our computational analysis suggests the allele arose in central China approximately 30,000 years ago. Although EDAR370A has been associated with increased scalp hair thickness and changed tooth morphology in humans, its direct biological significance and potential adaptive role remain unclear. We generated a knockin mouse model and find that, as in humans, hair thickness is increased in EDAR370A mice. We identify new biological targets affected by the mutation, including mammary and eccrine glands. Building on these results, we find that EDAR370A is associated with an increased number of active eccrine glands in the Han Chinese. This interdisciplinary approach yields unique insight into the generation of adaptive variation among modern humans.of adaptive variation among modern humans.)
Devaux 2015 Abstract MiP2015 + (An adequate oxygen supply is crucial for v … An adequate oxygen supply is crucial for vertebrate survival because ATP is almost exclusively produced by mitochondria though oxidative phosphorlyaltion (OXPHOS). Anoxia leads to ATP depletion and altered metabolic pathways including succinate accumulation which during re-oxygenation triggers a reverse of electron flow to CI accompanied by an enhanced deleterious reactive oxygen species (ROS) production [1]. A few species are able to survive prolonged periods of hypoxia and anoxia at tropical temperatures [2,3]. Two closely related elasmobranchs have very different adative responses to anoxia [2] while both can survive prolonged periods of anoxia the epaulette shark enters a phase of metabolic depression in response to hypoxia or anoxia while the grey carpet shark maintains its metabolic rate but releases additional red blood cells to prolong survival. Mitochondria in heart fibers from the anoxia tolerant epaulette shark maintained mitochondrial efficiency with a low ROS release in response to oxygen limitation, including anoxia [4]. The extent of mitochondrial plasticity in response to diminished oxygen (hypoxia or anoxia) and the triggers involved in this adative process are currently being investigated in our laboratories.Our aim was to determine the response of mitochondrial complexes to elevated succinate after a bout of diminished oxygen in two closely related anoxia tolerant species. Sharks were acclimated in aerated sea-water (100L tanks) held at 22°C and were not fed 24 hours prior to sampling. Sharks were euthanised, the cerebellum isolated and homogenised in cold MiR05. Mitochondrial respiration was measured using high resolution respirometry (Oroboros Oxygraph-2k) with a SUIT protocol. Respiration flux (pmol O2 s-1 mg-1) was determined using DatLab 6.0 and statistical analysis were performed using SPSS™. Calculations were made to determine CI capacity, CII activation and coupling efficiency with and without a 20 min episode of anoxia followed by reoxygenation and stepwise succinate titrations (using a TIP2K microPump).ation and stepwise succinate titrations (using a TIP2K microPump).)
Varela-Lopez 2016 J Gerontol A Biol Sci Med Sci + (An age-dependent model of the periodontium … An age-dependent model of the periodontium was reproduced to evaluate the effect of life-long feeding on a low coenzyme Q10 dosage in n-6, n-3 polyunsaturated fatty acid or monounsaturated fatty acid-based diets on periodontal tissues of young and old rats. Results shown that exacerbated age-related alveolar bone loss previously associated to n-6 polyunsaturated fatty acid diet was attenuated by coenzyme Q10 Gene expression analysis suggests that involved mechanisms might be related to a restored capacity of mitochondria to adapt to aging in gingival cells from rats fed on n-6 polyunsaturated fatty acid. In particular, this could be due to an age-related increase of the rate of mitochondrial biogenesis and a better oxidative and respiratory balance in these animals. From the nutritional and clinical point of view, it is noteworthy that supplementation with coenzyme Q10 could counteract the negative effects of n-6 polyunsaturated fatty acid on alveolar bone loss (a major feature of periodontitis) associated to age.© The Author 2015. Published by Oxford University Press on behalf of The Gerontological Society of America. of The Gerontological Society of America.)
Ye 2013 Anal Biochem + (An approach has been developed to quantita … An approach has been developed to quantitate oxidative phosphorylation in harvested human skin fibroblasts that have been permeabilized with digitonin. In protocol 1, state 3 rates are measured with Complex I and II substrates, followed by uncoupled maximal oxidative capacity measured in the presence of these combined substrates, as well as through Complex IV. In protocol 2, state 3 rates are measured using palmitoylcarnitine to monitor fatty acid oxidation, and duroquinol to assess the flux through Complex III; uncoupled duroquinol oxidation measures maximal oxidative capacity through Complex III. The activity of citrate synthase is determined in every experiment as a marker of the amount of mitochondria per chamber. Data are expressed on the basis of cell count (per million fibroblasts), of protein, or of citrate synthase activity. Cell growth conditions are optimized and it is necessary to keep cultured cells from reaching confluency. Cultures in passages 3 to 10 show reproducible oxidative phosphorylation data. Based on the data from the 15 normal human skin fibroblast lines, we are evaluating the use of this approach to diagnose systemic mitochondrial disease and avoid issues associated with open skeletal muscle biopsy.sociated with open skeletal muscle biopsy.)
Schrauwen-Hinderling 2015 Antioxid Redox Signal + (An early hallmark in the development of ty … An early hallmark in the development of type 2 diabetes is the resistance to the effect of insulin in skeletal muscle and in the heart. Since mitochondrial function was found to be diminished in patients with type 2 diabetes, it was suggested that this defect might be involved in the etiology of insulin resistance. Although several hypotheses were suggested, yet unclear is the mechanistic link between these two phenomena. Herein, we review the evidence for disturbances in mitochondrial function in skeletal muscle and the heart in the diabetic state. Also the mechanisms involved in improving mitochondrial function are considered and, whenever possible, human data is cited. Reported evidence shows that interventions that improve skeletal muscle mitochondrial function also improve insulin sensitivity in humans. In the heart, available data from animal studies suggests that enhancement of mitochondrial function can reverse aging-induced changes in heart function, and can be protective against cardiomyopathy and heart failure.Mitochondria and their functions can be targeted with the aim of improving skeletal muscle insulin sensitivity and cardiac function. However, human clinical intervention studies are needed to fully substantiate the potential of mitochondria as a target to prevent cardiometabolic disease.target to prevent cardiometabolic disease.)
Fuhr 2018 EBioMedicine + (An endogenous molecular clockwork drives v … An endogenous molecular clockwork drives various cellular pathways including metabolism and the cell cycle. Its dysregulation is able to prompt pathological phenotypes including cancer. Besides dramatic metabolic alterations, cancer cells display severe changes in the clock phenotype with likely consequences in tumor progression and treatment response. In this study, we use a comprehensive systems-driven approach to investigate the effect of clock disruption on metabolic pathways and its impact on drug response in a cellular model of colon cancer progression. We identified distinctive time-related transcriptomic and metabolic features of a primary tumor and its metastatic counterpart. A mapping of the expression data to a comprehensive genome-scale reconstruction of human metabolism allowed for the in-depth functional characterization of 24 h-oscillating transcripts and pointed to a clock-driven metabolic reprogramming in tumorigenesis. In particular, we identified a set of five clock-regulated glycolysis genes, ''ALDH3A2'', ''ALDOC'', ''HKDC1'', ''PCK2'', and ''PDHB'' with differential temporal expression patterns. These findings were validated in organoids and in primary fibroblasts isolated from normal colon and colon adenocarcinoma from the same patient. We further identified a reciprocal connection of HKDC1 to the clock in the primary tumor, which is lost in the metastatic cells. Interestingly, a disruption of the core-clock gene ''BMAL1'' impacts on HKDC1 and leads to a time-dependent rewiring of metabolism, namely an increase in glycolytic activity, as well as changes in treatment response. This work provides novel evidence regarding the complex interplay between the circadian clock and metabolic alterations in carcinogenesis and identifies new connections between both systems with pivotal roles in cancer progression and response to therapy.ancer progression and response to therapy.)
Kang 2018 Exp Mol Med + (An excess of reactive oxygen species (ROS) … An excess of reactive oxygen species (ROS) relative to the antioxidant capacity causes oxidative stress, which plays a role in the development of Parkinson's disease (PD). Because mitochondria are both sites of ROS generation and targets of ROS damage, the delivery of antioxidants to mitochondria might prevent or alleviate PD. To transduce the antioxidant protein human metallothionein 1A (hMT1A) into mitochondria, we computationally designed a cell-penetrating artificial mitochondria-targeting peptide (CAMP). The recombinant CAMP-conjugated hMT1A fusion protein (CAMP-hMT1A) successfully localized to the mitochondria. Treating a cell culture model of PD with CAMP-hMT1A restored tyrosine hydroxylase expression and mitochondrial activity and reduced ROS production. Furthermore, injection of CAMP-hMT1A into the brain of a mouse model of PD rescued movement impairment and dopaminergic neuronal degeneration. CAMP-hMT1A delivery into mitochondria might be therapeutic against PD by alleviating mitochondrial damage, and we predict that CAMP could be used to deliver other cargo proteins to the mitochondria. other cargo proteins to the mitochondria.)
Greco 2003 FASEB J + (An extensive analysis has been carried out … An extensive analysis has been carried out of mitochondrial biochemical and bioenergetic properties of fibroblasts, mostly skin-derived, from a large group of subjects ranging in age between 20 wk fetal and 103 yr. A striking age-related change observed in a fundamental process underlying mitochondrial biogenesis and function was the very significant decrease in rate of mitochondrial protein synthesis in individuals above 40 yr. The analysis of endogenous respiration rate revealed a significant decrease in the age range from 40 to 90 yr and a tendency to uncoupling in the samples from subjects above 60 yr. A surprising finding was the occurrence of a subgroup of individuals >or=90 yr old whose skin fibroblasts exhibited an exceptionally high respiration rate. This high rate was not due to respiration uncoupling, rather pointing to a compensatory phenomenon, not involving an increase in mtDNA content, in the corresponding skin fibroblast populations, or, possibly, to a selection of a different cell type secondary to more extensive dermal atrophy. The most important aging-related phenotypic effects observed were those that affected the cell oxidative phosphorylation (OX-PHOS) capacity. These were, in particular, the very significant reduction in the ratio of uncoupled to oligomycin-inhibited endogenous respiration observed in intact fibroblasts, which pointed to a decrease with donor's age in the control of respiration by the mitochondrial membrane potential, the very significant decrease in efficiency of OX-PHOS, as determined by novel in situ measurements of P:O ratios, and, consistent with these results, the very significant reduction in the respiratory control ratios. These findings clearly pointed to a dramatic mitochondrial dysfunction, which would lead to a decrease in ATP synthesis rate, with the observed decline in mitochondrial protein synthesis rate being a likely contributing factor. These observations have important implications for understanding the biology of aging, as well as the pathogenesis of aging-related degenerative diseases.nesis of aging-related degenerative diseases.)
Sies 1997 Exp Physiol + (An imbalance between oxidants and antioxid … An imbalance between oxidants and antioxidants in favour of the oxidants, potentially leading to damage, is termed 'oxidative stress'. Oxidants are formed as a normal product of aerobic metabolism but can be produced at elevated rates under pathophysiological conditions. Antioxidant defense involves several strategies, both enzymatic and non-enzymatic. In the lipid phase, tocopherols and carotenes as well as oxy-carotenoids are of interest, as are vitamin A and ubiquinols. In the aqueous phase, there are ascorbate, glutathione and other compounds. In addition to the cytosol, the nuclear and mitochondrial matrices and extracellular fluids are protected. Overall, these low molecular mass antioxidant molecules add significantly to the defense provided by the enzymes superoxide dismutase, catalase and glutathione peroxidases.ase, catalase and glutathione peroxidases.)
Salin 2021 Mar Environ Res + (An important, but underappreciated, conseq … An important, but underappreciated, consequence of climate change is the reduction in crucial nutrient production at the base of the marine food chain: the long-chain omega-3 highly unsaturated fatty acids (n-3 HUFA). This can have dramatic consequences on consumers, such as fish as they have limited capacity to synthesise n-3 HUFA ''de novo''. The n-3 HUFA, such as docosahexaenoic acid (DHA, 22:6n-3) and eicosapentaenoic acid (EPA, 20:5n-3), are critical for the structure and function of all biological membranes. There is increasing evidence that fish will be badly affected by reductions in n-3 HUFA dietary availability, however the underlying mechanisms remain obscure. Hypotheses for how mitochondrial function should change with dietary n-3 HUFA availability have generally ignored ATP production, despite its importance to a cell's total energetics capacity, and in turn, whole-animal performance. Here we (i) quantified individual variation in mitochondrial efficiency (ATP/O ratio) of muscle and (ii) examined its relationship with content in EPA and DHA in muscle membrane of a primary consumer fish, the golden grey mullet ''Chelon auratus'', receiving either a high or low n-3 HUFA diet. Mitochondria of fish fed on the low n-3 HUFA diet had higher ATP/O ratio than those of fish maintained on the high n-3 HUFA diet. Yet, mitochondrial efficiency varied up about 2-fold among individuals on the same dietary treatment, resulting in some fish consuming half the oxygen and energy substrate to produce the similar amount of ATP than conspecific on similar diet. This variation in mitochondrial efficiency among individuals from the same diet treatment was related to individual differences in fatty acid composition of the membranes: a high ATP/O ratio was associated with a high content in EPA and DHA in biological membranes. Our results highlight the existence of interindividual differences in mitochondrial efficiency and its potential importance in explaining intraspecific variation in response to food chain changes.riation in response to food chain changes.)
Gnaiger 2015 Abstract MiP2015 + (An increasing number of metabolic and othe … An increasing number of metabolic and other diseases is recognized as being linked to mitochondrial physiology and dysfunction of oxidative phosphorylation ([[OXPHOS]]), which can be analyzed effectively and quantitatively by [[high-resolution respirometry]] (HRR). Instrumental quality control is a fundamental component of HRR applied in many laboratories [1]. Beyond the instrumental level, a standardized mt-laboratory quality management system (QMSmtf [2]) is required for establishing a global data base on mitochondrial function (mtf) in human cells and tissues, taking into account the variables of evolution, age, gender, life style and environment ([[MitoEAGLE]]). A QMSmtf requires the availability of a mt-reference sample which is functionally stable over time and across geographical space, as a basis of standard proficiency tests within and between reference laboratories. Mammalian mt-preparations (isolated mitochondria, tissue preparations) appear to be neither suitable for prolonged storage nor large scale production. Therefore, we focused on cryopreserved human cells [3]. Using the widely applied cell line HEK 293T we optimized cryopreservation to maintain cell viability and stabilize respiratory characteristics of intact and permeabilized cells over variable periods of time. HEK 293T cells were cultured under standard conditions with DMEM, were cryopreserved by cooling cells suspended in a freezing medium with fetal calf serum (FCS) and 10% dimethyl sulfoxide (DMSO), and stored at -80 °C for variable periods of time. Cells were thawed by addion of and careful mixing in pre-warmed PBS or MiR05. Cell counts and viability were assessed by determination of Trypan blue exclusion using an automated Countess cell counter. Respiration was measured in the Oroboros Oxygraph-2k applying standard substrate-uncoupler-inhibitor-titration ([[SUIT]]) protocols for permeabilized cells in [[MiR05]]. For HRR with intact cells, cyropreserved cells were suspended in pre-warmed DMEM. Results were compared with tests on cells cryopreserved with addition of the powerful antioxidant [[melatonin]] at 10 nM or 25 µM.[melatonin]] at 10 nM or 25 µM.)
Doerrier 2015 Abstract MiP2015 + (An increasing number of studies point to m … An increasing number of studies point to mitochondria as key regulators of many physiological and pathological conditions, related to life style (including physical exercise and nutrition), neurodegenerative diseases, metabolic disorders, inflammatory diseases, cancer, heart failure, and aging. Moreover, mitochondria are an important source of reactive oxygen species (ROS), which are needed for cell signaling. However, an increase in ROS production generates an oxidative stress which is implicated in the pathogenesis of many diseases. In particular, the NADH redox state is related to ROS production. Succinate is a substrate of succinate dehydrogenase (CII). For analysis of mitochondrial function with CII-linked substrates, rotenone (inhibitor of CI) is added to prevent accumulation of oxaloacetate (Oa), which is a strong competitive inhibitor of CII [1]. Ischaemic accumulation of succinate has been related to mitochondrial ROS production during reperfusion by reverse electron transfer [2]. In the present study, we used succinate with and without rotenone as a model for pathophysiological mitochondrial ROS-production.We investigated the effect of succinate (10 mM) alone, S, or succinate (10 mM) with rotenone (0.5 μM), S(Rot), on mitochondrial respiration, hydrogen peroxide (H2O2) production and NADH redox state in cardiac isolated mitochondria from C57BL/6 mice. Respiration media (37 °C) were optimized for the specific protocols. High-resolution respirometry (HRR) was applied with the O2k-Fluorometer (Oroboros , Innsbruck, Austria). H2O2 production was measured simultaneously using Amplex Ultrared [3]. NAD(P)H autofluorescence was monitored in a prototype NextGen-O2k, which combines HRR with O2k-Spectrofluorometry. Step changes of the fluorescence signal were calibrated with NADH and corrected for changes observed in chemical background tests. These methods allow analyzing simultaneously relevant bioenergetic parameters to assess mitochondrial function.Oxygen consumption levels were similar for S and S(Rot) in the LEAK state (without adenylates). However, H2O2 production was substantially higher with S in LEAK state. Adding ADP (2 mM) to S(Rot) to induce OXPHOS capacity, mitochondrial respiration increased by 70%. In contrast ADP titration to S induced a decline in respiration by 30% with respect to the LEAK state, which is the so-called “succinate paradox” [4].ed a decline in respiration by 30% with respect to the LEAK state, which is the so-called “succinate paradox” [4].)
Cagnone 2016 Sci Rep + (An increasing number of women fail to achi … An increasing number of women fail to achieve pregnancy due to either failed fertilization or embryo arrest during preimplantation development. This often results from decreased oocyte quality. Indeed, reduced mitochondrial DNA copy number (mitochondrial DNA deficiency) may disrupt oocyte quality in some women. To overcome mitochondrial DNA deficiency, whilst maintaining genetic identity, we supplemented pig oocytes selected for mitochondrial DNA deficiency, reduced cytoplasmic maturation and lower developmental competence, with autologous populations of mitochondrial isolate at fertilization. Supplementation increased development to blastocyst, the final stage of preimplantation development, and promoted mitochondrial DNA replication prior to embryonic genome activation in mitochondrial DNA deficient oocytes but not in oocytes with normal levels of mitochondrial DNA. Blastocysts exhibited transcriptome profiles more closely resembling those of blastocysts from developmentally competent oocytes. Furthermore, mitochondrial supplementation reduced gene expression patterns associated with metabolic disorders that were identified in blastocysts from mitochondrial DNA deficient oocytes. These results demonstrate the importance of the oocyte's mitochondrial DNA investment in fertilization outcome and subsequent embryo development to mitochondrial DNA deficient oocytes.nt to mitochondrial DNA deficient oocytes.)
Friederich 2017 Hum Mol Genet + (An infant presented with fatal infantile l … An infant presented with fatal infantile lactic acidosis and cardiomyopathy, and was found to have profoundly decreased activity of respiratory chain complex I in muscle, heart and liver. Exome sequencing revealed compound heterozygous mutations in NDUFB10, which encodes an accessory subunit located within the PD part of complex I. One mutation resulted in a premature stop codon and absent protein, while the second mutation replaced the highly conserved cysteine 107 with a serine residue. Protein expression of NDUFB10 was decreased in muscle and heart, and less so in the liver and fibroblasts, resulting in the perturbed assembly of the holoenzyme at the 830 kDa stage. NDUFB10 was identified together with three other complex I subunits as a substrate of the intermembrane space oxidoreductase CHCHD4 (also known as Mia40). We found that during its mitochondrial import and maturation NDUFB10 transiently interacts with CHCHD4 and acquires disulfide bonds. The mutation of cysteine residue 107 in NDUFB10 impaired oxidation and efficient mitochondrial accumulation of the protein and resulted in degradation of non-imported precursors. Our findings indicate that mutations in NDUFB10 are a novel cause of complex I deficiency associated with a late stage assembly defect and emphasize the role of intermembrane space proteins for the efficient assembly of complex I.s for the efficient assembly of complex I.)
SiouNing 2023 Molecules + (An infectious disease is the most apprehen … An infectious disease is the most apprehensive problem in aquaculture as it can lead to high mortality in aquatic organisms and massive economic loss. Even though significant progress has been accomplished in therapeutic, prevention, and diagnostic using several potential technologies, more robust inventions and breakthroughs should be achieved to control the spread of infectious diseases. MicroRNA (miRNA) is an endogenous small non-coding RNA that post-transcriptionally regulates the protein-coding genes. It involves various biological regulatory mechanisms in organisms such as cell differentiation, proliferation, immune responses, development, apoptosis, and others. Furthermore, an miRNA also acts as a mediator to either regulate host responses or enhance the replication of diseases during infection. Therefore, the emergence of miRNAs could be potential candidates for the establishment of diagnostic tools for numerous infectious diseases. Interestingly, studies have revealed that miRNAs can be used as biomarkers and biosensors to detect diseases, and can also be used to design vaccines to attenuate pathogens. This review provides an overview of miRNA biogenesis and specifically focuses on its regulation during infection in aquatic organisms, especially on the host immune responses and how miRNAs enhance the replication of pathogens in the organism. In addition to that, we explored the potential applications, including diagnostic methods and treatments, that can be employed in the aquaculture industry.n be employed in the aquaculture industry.)
Salvadego 2016 J Appl Physiol (1985) + (An integrative evaluation of oxidative met … An integrative evaluation of oxidative metabolism was carried out in 9 healthy young men (age, 24.1 ± 1.7 yr mean ± SD) before (CTRL) and after a 10-day horizontal bed rest carried out in normoxia (N-BR) or hypoxia (H-BR, FiO2 = 0.147). H-BR was designed to simulate planetary habitats. Pulmonary O2 uptake (''V''O2) and vastus lateralis fractional O2 extraction (changes in deoxygenated hemoglobin+myoglobin concentration, Δ[deoxy(Hb+Mb)] evaluated using near-infrared spectroscopy) were evaluated in normoxia and during an incremental cycle ergometer (CE) and one-leg knee extension (KE) exercise (aimed at reducing cardiovascular constraints to oxidative function). Mitochondrial respiration was evaluated ''ex vivo'' by high-resolution respirometry in permeabilized vastus lateralis fibers. During CE ''V''O2peak and Δ[deoxy(Hb+Mb)]peak were lower (''P'' < 0.05) after both N-BR and H-BR than during CTRL; during KE the variables were lower after N-BR but not after H-BR. During CE the overshoot of Δ[deoxy(Hb+Mb)] during constant work rate exercise was greater in N-BR and H-BR than CTRL, whereas during KE a significant difference vs. CTRL was observed only after N-BR. Maximal mitochondrial respiration determined ''ex vivo'' was not affected by either intervention. In N-BR, a significant impairment of oxidative metabolism occurred downstream of central cardiovascular O2 delivery and upstream of mitochondrial function, possibly at the level of the intramuscular matching between O2 supply and utilization and peripheral O2 diffusion. Superposition of hypoxia on bed rest did not aggravate, and partially reversed, the impairment of muscle oxidative function ''in vivo'' induced by bed rest. The effects of longer exposures will have to be determined.Copyright © 2016 the American Physiological Society.vivo'' induced by bed rest. The effects of longer exposures will have to be determined. Copyright © 2016 the American Physiological Society.)
CTCM 2019 Ankara TR + (An international symposium on cellular therapy in cardiovascular medicine (CTCM): stem cell opportunity, Ankara, Turkey, 2019)
Boardman 2020 Am J Physiol Heart Circ Physiol + (An ischemic insult is accompanied by an ac … An ischemic insult is accompanied by an acute increase in circulating fatty acid (FA), which can induce adverse changes related to cardiac metabolism/energetics. Although chronic hyperlipidemia contributes to the pathogenesis of obesity/diabetes-related cardiomyopathy, it unclear how these hearts are affected by an acute high FA-load. We hypothesize that adaptation to chronic FA exposure enhances the obese hearts' ability to handle an acute high FA-load. Diet-induced obese (DIO) and age-matched control (CON) mouse hearts were perfused in the presence of low or high FA-load (0.4 and 1.8 mM). Left ventricular (LV) function, FA oxidation rate, myocardial oxygen consumption and mechanical efficiency were assessed, followed by analysis of myocardial oxidative stress, mitochondrial respiration, protein acetylation as well as gene expression. Finally, ischemic tolerance was determined by examining LV functional recovery and infarct size. Under low FA conditions, DIO hearts showed mild LV dysfunction, oxygen wasting, mechanical inefficiency, and reduced mitochondrial OxPhos. High FA-load increased FA oxidation rates in both groups, but this did not alter any of the above parameters in DIO hearts. In contrast, CON hearts showed FA-induced mechanical inefficiency, oxidative stress and reduced OxPhos, as well as enhanced acetylation and activation of PPARα-dependent gene expression. While high FA-load did not alter functional recovery and infarct size in CON hearts, it increased ischemic tolerance in DIO hearts. Thus, this study demonstrates that acute FA-load affects normal and obese hearts differently, and that chronically elevated circulating FA levels render the DIO heart less vulnerable to the disadvantageous effects of an acute FA-load.sadvantageous effects of an acute FA-load.)
Haack 2010 Nat Genet + (An isolated defect of respiratory Complex … An isolated defect of respiratory Complex I activity is a frequent biochemical abnormality in mitochondrial disorders. Despite intensive investigation in recent years, in most instances, the molecular basis underpinning Complex I defects remains unknown. We report whole-exome sequencing of a single individual with severe, isolated Complex I deficiency. This analysis, followed by filtering with a prioritization of mitochondrial proteins, led us to identify compound heterozygous mutations in ACAD9, which encodes a poorly understood member of the mitochondrial acyl-CoA dehydrogenase protein family. We demonstrated the pathogenic role of the ACAD9 variants by the correction of the Complex I defect on expression of the wildtype ACAD9 protein in fibroblasts derived from affected individuals. ACAD9 screening of 120 additional Complex I-defective index cases led us to identify two additional unrelated cases and a total of five pathogenic ACAD9 alleles. a total of five pathogenic ACAD9 alleles.)
Wardle 2023 Issues Sci Technol + (An obsession with gauging accuracy of individual posts is misguided. To strengthen information ecosystems, focus on narratives and why people share what they do.)
Rodolphi 2017 Thesis + (Anabolic androgenic steroids (AAS) such as … Anabolic androgenic steroids (AAS) such as nandrolone decanoate (ND) are synthetic hormones derived from testosterone. It is known that one of the most important adverse effects of abusive administration of these steroids is the increase in aggressive behavior. Evidence indicates that high doses of AAS alter morphology and cause hyperactivation of glutamatergic synapses which correlates with an aggressive exacerbated phenotype. Physiologically, glutamate is considered the main excitatory neurotransmitter in the mammalian brain. At high glutamate levels, occurs neuronal hyperexcitability mainly through the ionotropic N-methyl-d-aspartate (NMDAr) type of glutamatergic receptors and, consequently, changes in mitochondrial metabolism. Existing transporters in astrocytes predominantly perform the termination of glutamatergic excitatory signaling. In this sense, the GLT-1 glutamate astrocytic transporter is responsible for more than 90% of glutamate removal from the synaptic cleft, contributing significantly to the maintenance of glutamatergic signaling homeostasis. Administration of the β-lactam antibiotic ceftriaxone (CEF) increases GLT-1 expression and decreases glutamatergic hyperexcitability, which could potentially counteract brain mechanisms associated to increased aggressive phenotype mediated by nandrolone decanoate (ND). However, a possible molecular and behavioral interaction has not yet been explored in context. Thus, the primary objective of this work was to investigate whether increased expression of the GLT-1 astrocyte transporter modulates the glutamatergic mechanisms involved in ND-induced aggressive phenotype, and mitochondrial activity. Sixty-day-old male CF-1 mice were divided into 4 groups: oil vehicle (VEH), nandrolone (ND), ceftriaxone (CEF) and nandrolone + ceftriaxone (ND / CEF). Nandrolone was injected subcutaneously (15mg / kg) for 19 days. Ceftriaxone (200mg / kg) or saline solution were administered intraperitoneally for 5 days. After the last injection, the latency for the first attack and the number of attacks on the intruder test were evaluated. The animals were sacrificed after the test, and homogeinized cortex were used for immunoquantification of GLT-1 and phosphorylation of the NMDAr pNR2Bser1232 subunit. Mitochondrial activity was evaluated in total brain sinaptossomes. Glutamate levels were measured in the cerebrospinal fluid. Compared to the vehicle group, treatment with ND significantly decreased the expression of GLT-1, increased glutamate levels and expression of the pNR2Bser1232 which was mechanistically associated with an increase in the aggressive phenotype; decrease in the latency and increase in the number of attacks. Also, ND decreased mitochondrial respiratory control. Administration of CEF significantly increased GLT-1 expression and decreased glutamate levels relative to the ND group, whereas pNR2Bser1232 levels and aggressive phenotype were similar to the control group. In the ND / CEF group the expression of GLT-1 and pNR2Bser1232, glutamate levels and aggressive phenotype were significantly lower than in the ND group, and similar to the control group. Furthermore, CEF was able to attenuate the alteration in the mitochondrial respiratory control caused by ND. Our results demonstrated that the levels of glutamate astrocytic transporter GLT-1 and pNR2Bser1232 are important mechanism behind the increased aggressive phenotype induced by ND, and decreased mitochondrial respiratory control. Also, this model reinforces the importance of glutamate levels and astrocytic molecular targets in the regulation of the aggressive phenotype.ce of glutamate levels and astrocytic molecular targets in the regulation of the aggressive phenotype.)
Putzer 1985 Comp Biochem Physiol + (Anaerobic processes were studied in ''Tubi … Anaerobic processes were studied in ''Tubifex'' and other aquatic invertebrates. After the aerobic-anoxic transition of Tubifex, succinate accumulated up to about 25 μmol/g Wd within the first hour of anoxia, but steady-state levels were established after 4hr at only 10 μmol/g Wd in an open-flow system.Proprionate accumulated after a lag of 30 min and reached steady-state concentrations of about 30 μmol/g Wd after 5 h of anoxia.Lactate concentrations did not increase above 4 μmol/g Wd under anoxia. Its accumulation was not induced by exposure to a blood extract, although ''Tubifex'' has the potential for lactate production.The initial rates of glycolytic endproduct accumulation were increased in the presence of the deproteinized blood extract by 60% (succinate, 0–30 min anoxia) and by 50% and 90% (proprionate, 30–60 min anoxia; 1% and 2% blood extract, respectively). The maximum and steady state levels of these metabolites were not influenced by the hydrolysate of blood.Aerobic and anaerobic heat dissipation of ''Lumbriculus variegatus'' was stimulated by the addition to the medium of a deproteinized hydrolysate of bovine blood. Oxygen uptake of ''Cyclops abyssorum'' increased similarly upon the addition of the blood extract under hypoxia.lops abyssorum'' increased similarly upon the addition of the blood extract under hypoxia.)
Keys 2014 Int J Epidemiol + (Analyses are reported on the correlation w … Analyses are reported on the correlation with height and with subcutaneous fat thickness of relative weight expressed as per cent of average weight at given height, and of the ratios weight/height, weight/height squared, and the ponderal index (cube root of weight divided by height) in 7424 ‘healthy’ men in 12 cohorts in five countries. Analyses are also reported on the relationship of those indicators of relative weight to body density in 180 young men and in 248 men aged 49–59. Judged by the criteria of correlation with height (lowest is best) and to measures of body fatness (highest is best), the ponderal index is the poorest of the relative weight indices studied. The ratio of weight to height squared, here termed the body mass index, is slightly better in these respects than the simple ratio of weight to height. The body mass index seems preferable over other indices of relative weight on these grounds as well as on the simplicity of the calculation and, in contrast to percentage of average weight, the applicability to all populations at all times.icability to all populations at all times.)
Kuznetsov 2008 Nat Protoc + (Analysis of mitochondrial function is cent … Analysis of mitochondrial function is central to the study of intracellular energy metabolism, mechanisms of cell death and pathophysiology of a variety of human diseases, including myopathies, neurodegenerative diseases and cancer. However, important properties of mitochondria differ ''in vivo'' and ''in vitro''. Here, we describe a protocol for the analysis of functional mitochondria ''in situ'', without the isolation of organelles, in selectively permeabilized cells or muscle fibers using digitonin or saponin. A specially designed substrate/inhibitor titration approach allows the step-by-step analysis of several mitochondrial complexes. This protocol allows the detailed characterization of functional mitochondria in their normal intracellular position and assembly, preserving essential interactions with other organelles. As only a small amount of tissue is required for analysis, the protocol can be used in diagnostic settings in clinical studies. The permeabilization procedure and specific titration analysis can be completed in 2 h.itration analysis can be completed in 2 h.)
Doerrier 2016 Mitochondrion + (Analysis of mitochondrial function is cruc … Analysis of mitochondrial function is crucial to understand their involvement in a given disease. High-resolution respirometry of permeabilized myocardial fibers in septic mice allows the evaluation of the bioenergetic system, maintaining mitochondrial ultrastructure and intracellular interactions, which are critical for an adequate functionality. OXPHOS and electron transport system (ET-pathway) capacities were assessed using different substrate combinations. Our findings show severe septic-dependent impairment in OXPHOS and ET capacities with mitochondrial uncoupling at early and late phases of sepsis. Moreover, sepsis triggers complex III (CIII)-linked alterations in supercomplexes structure, and loss of mitochondrial density. In these conditions, melatonin administration to septic mice prevented sepsis-dependent mitochondrial injury in mitochondrial respiration. Likewise, melatonin improved cytochrome b content and ameliorated the assembly of CIII in supercomplexes. These results support the use of permeabilized fibers to identify properly respiratory deficits and specific melatonin effects in sepsis. and specific melatonin effects in sepsis.)
Analytica China 2020 Shanghai CN + (Analytica China Exhibition, Shanghai, China, 2020)
Bousseau 2019 FASEB J + (Angiogenesis is a complex process leading … Angiogenesis is a complex process leading to the growth of new blood vessels from existing vasculature, triggered by local proangiogenic factors such as VEGF. An excess of angiogenesis is a recurrent feature of various pathologic conditions such as tumor growth. Phostines are a family of synthetic glycomimetic compounds that exhibit anticancer properties, and the lead compound 3-hydroxy-4,5-bis-benzyloxy-6-benzyloxymethyl-2-phenyl2-oxo-2λ5-[1,2]oxaphosphinane (PST 3.1a) shows antiglioblastoma properties both ''in vitro'' and ''in vivo''. In the present study, we assessed the effect of PST 3.1a on angiogenesis and endothelial metabolism. ''In vitro'', PST 3.1a (10 µM) inhibited all steps that regulate angiogenesis, including migration, proliferation, adhesion, and tube formation. ''In vivo'', PST 3.1a reduced intersegmental vessel formation and vascularization of the subintestinal plexus in zebrafish embryos and also altered pathologic angiogenesis and glioblastoma progression ''in vivo''. Mechanistically, PST 3.1a altered interaction of VEGF receptor 2 and glycosylation-regulating protein galectin-1, a key component regulating angiogenesis associated with tumor resistance. Thus, these data show that use of PST 3.1a is an innovative approach to target angiogenesis.nnovative approach to target angiogenesis.)
Atallah 2022 Biomedicines + (Angiogenesis is an essential process by wh … Angiogenesis is an essential process by which new blood vessels develop from existing ones. While adequate angiogenesis is a physiological process during, for example, tissue repair, insufficient and excessive angiogenesis stands on the pathological side. Fine balance between pro- and anti-angiogenic factors in the tissue environment regulates angiogenesis. Identification of these factors and how they function is a pressing topic to develop angiogenesis-targeted therapeutics. During the last decade, exciting data highlighted non-metabolic functions of intermediates of the mitochondrial Krebs cycle including succinate. Among these functions is the contribution of succinate to angiogenesis in various contexts and through different mechanisms. As the concept of targeting metabolism to treat a wide range of diseases is rising, in this review we summarize the mechanisms by which succinate regulates angiogenesis in normal and pathological settings. Gaining a comprehensive insight into how this metabolite functions as an angiogenic signal will provide a useful approach to understand diseases with aberrant or excessive angiogenic background, and may provide strategies to tackle them.and may provide strategies to tackle them.)
Chergova 2015 Abstract MiPschool London 2015 + (Angiogenesis is the process of new blood v … Angiogenesis is the process of new blood vessel formation from preexisting vasculature [1]. Endothelial cells (ECs) are responsible for the development of the vascular plexus. This process is very active during embryonic development whereas ECs are quiescent during adulthood. Reactivation of angiogenesis is related to various pathological states such as tumor growth. Angiogenesis requires remodeling and new tissue formation and therefore a higher demand in ATP. Mitochondria are essential cell organelles with pivotal role in processes of life and death and they are the main source of ATP in the cell. Nevertheless, it has been shown that VEGF, a key pro-angiogenic factor, is involved in mitochondrial biogenesis [2]. However, the role of mitochondria in the endothelium is poorly understood. Mitochondria are extremely dynamic structures. Their morphology is modulated through processes of fusion and fission in order to fulfill their diverse functions [3]. Mitochondrial morphology is orchestrated by a number of dynamin-like GTPases. Mitochondrial fusion depends on mitofusin 1 (MFN1), mitofusin 2 (MFN2) and Optic Atrophy 1 (OPA1). DRP1 is the key regulator of mitochondrial fission. The emerging of mitochondrial function in diverse cellular processes provoked our interest to study mitochondrial dynamics and the role of DRP1 in endothelial cells during angiogenesis.''In vitro'' we are approaching DRP1’s function in HUVEC cells (Human Umbilical Cord Endothelial Cells) under angiogenic stimulation or ablation. ''In vivo'' we will evaluate physiological angiogenesis using the mouse retinal neovascularization model [4] in the conditional endothelial knock out for DRP1.Our results show that VEGF treatment of HUVECs decreases DRP1 levels. Parallel to this inhibition of angiogenesis by the anti-angiogenic factor 16K prolactin causes an increase of DRP1 expression. Furthermore, we evaluated angiogenesis by measuring cell migration, proliferation and permeability in HUVECs with down-regulation of DRP1 (siRNAs) and we observed an upregulation of angiogenic parameters.Our preliminary data are suggesting a key role of mitochondrial dynamics in angiogenesis and a new function for DRP1 in endothelial cells. Our goal is to identify how pro and anti-angiogenic agents affect DRP1 and which are the molecular pathways through which DRP1 is affecting angiogenesis.ough which DRP1 is affecting angiogenesis.)
Kivelae 2014 EMBO Mol Med + (Angiogenic growth factors have recently be … Angiogenic growth factors have recently been linked to tissue metabolism. We have used genetic gain- and loss-of function models to elucidate the effects and mechanisms of action of vascular endothelial growth factor-B (VEGF-B) in the heart. A cardiomyocyte-specific VEGF-B transgene induced an expanded coronary arterial tree and reprogramming of cardiomyocyte metabolism. This was associated with protection against myocardial infarction and preservation of mitochondrial complex I function upon ischemia-reperfusion. VEGF-B increased VEGF signals via VEGF receptor-2 to activate Erk1/2, which resulted in vascular growth. Akt and mTORC1 pathways were upregulated and AMPK downregulated, readjusting cardiomyocyte metabolic pathways to favor glucose oxidation and macromolecular biosynthesis. However, contrasting with a previous theory, there was no difference in fatty acid uptake by the heart between the VEGF-B transgenic, gene-targeted or wildtype rats. Importantly, we also show that VEGF-B expression is reduced in human heart disease. Our data indicate that VEGF-B could be used to increase the coronary vasculature and to reprogram myocardial metabolism to improve cardiac function in ischemic heart disease.ardiac function in ischemic heart disease.)
Vorotnikov 2022 Biomedicines + (Angiopathy is a common complication of dia … Angiopathy is a common complication of diabetes mellitus. Vascular endothelium is among the first targets to experience blood-borne metabolic alterations, such as hyperglycemia and hyperlipidemia, the hallmarks of type 2 diabetes. To explore mechanisms of vascular dysfunction and eventual damage brought by these pathologic conditions and to find ways to protect vasculature in diabetic patients, various research approaches are used including in vitro endothelial cell-based models. We present an analysis of the data available from these models that identifies early endothelial cell apoptosis associated with oxidative stress as the major outcome of mimicking hyperglycemia and hyperlipidemia in vitro. However, the fate of endothelial cells observed in these studies does not closely follow it in vivo where massive endothelial damage occurs mainly in the terminal stages of diabetes and in conjunction with comorbidities. We propose that the discrepancy is likely in missing essentials that should be available to cultured endothelial cells to adjust the metabolic state and withstand the immediate apoptosis. We discuss the role of carnitine, creatine, and AMP-activated protein kinase (AMPK) in suiting the endothelial metabolism for long-term function in diabetic type milieu in vitro. Engagement of these essentials is anticipated to expand diabetes research options when using endothelial cell-based models. when using endothelial cell-based models.)
Havird 2019 Mitochondrion + (Angiosperm mitochondrial (mt) genes are ge … Angiosperm mitochondrial (mt) genes are generally slow-evolving, but multiple lineages have undergone dramatic accelerations in rates of nucleotide substitution and extreme changes in mt genome structure. While molecular evolution in these lineages has been investigated, very little is known about their mt function. Some studies have suggested altered respiration in individual taxa, although there are several reasons why mt variation might be neutral in others. Here, we develop a new protocol to characterize respiration in isolated plant mitochondria and apply it to species of ''Silene'' with mt genomes that are rapidly evolving, highly fragmented, and exceptionally large (~11 Mbp). This protocol, complemented with traditional measures of plant fitness, cytochrome c oxidase activity assays, and fluorescence microscopy, was also used to characterize inter- and intraspecific variation in mt function. Contributions of the individual "classic" OXPHOS complexes, the alternative oxidase, and external NADH dehydrogenases to overall mt respiratory flux were found to be similar to previously studied angiosperms with more typical mt genomes. Some differences in mt function could be explained by inter- and intraspecific variation. This study suggests that ''Silene'' species with peculiar mt genomes still show relatively normal mt respiration. This may be due to strong purifying selection on mt variants, coevolutionary responses in the nucleus, or a combination of both. Future experiments should explore such questions using a comparative framework and investigating other lineages with unusual mitogenomes.Copyright © 2019 Elsevier B.V. and Mitochondria Research Society. All rights reserved.a Research Society. All rights reserved.)
Havird 2018 bioRxiv + (Angiosperm mitochondrial (mt) genes are ge … Angiosperm mitochondrial (mt) genes are generally slow-evolving, but multiple lineages have undergone dramatic accelerations in rates of nucleotide substitution and extreme changes in mt genome structure. While molecular evolution in these lineages has been investigated, very little is known about their mt function. Here, we develop a new protocol to characterize respiration in isolated plant mitochondria and apply it to species of ''Silene'' with mt genomes that are rapidly evolving, highly fragmented, and exceptionally large (~11 Mbp). This protocol, complemented with traditional measures of plant fitness, cytochrome c oxidase activity assays, and fluorescence microscopy, was used to characterize inter- and intraspecific variation in mt function. Contributions of the individual "classic" OXPHOS complexes, the alternative oxidase, and external NADH dehydrogenases to overall mt respiratory flux were found to be similar to previously studied angiosperms with more typical mt genomes. Some differences in mt function could be explained by inter- and intraspecific variation, possibly due to local adaptation or environmental effects. Although this study suggests that these ''Silene'' species with peculiar mt genomes still show relatively normal mt function, future experiments utilizing the protocol developed here can explore such questions in a more detailed and comparative framework.a more detailed and comparative framework.)
Liu 2016 Apoptosis + (Angiotensin II (AngII) is an important fac … Angiotensin II (AngII) is an important factor that promotes the proliferation of cancer cells, whereas celastrol exhibits a significant antitumor activity in various cancer models. Whether celastrol can effectively suppress AngII mediated cell proliferation remains unknown. In this study, we studied the effect of celastrol on AngII-induced HepG2 cell proliferation and evaluated its underlying mechanism. The results revealed that AngII was able to significantly promote HepG2 cell proliferation via up-regulating AngII type 1 (AT1) receptor expression, improving mitochondrial respiratory function, enhancing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity, increasing the levels of reactive oxygen species (ROS) and pro-inflammatory cytokines. The excess ROS from mitochondrial dysfunction is able to cause the apoptosis of tumor cells via activating caspase3 signal pathway. In addition, the reaction between NO and ROS results in the formation of peroxynitrite (ONOO-), and then promoting cell damage. Celastrol dramatically enhanced ROS generation, thereby causing cell apoptosis through inhibiting mitochodrial respiratory function and boosting the expression levels of AngII type 2 (AT2) receptor without influencing NADPH oxidase activity. PD123319 as a special inhibitor of AT2R was able to effectively decrease the levels of inflammatory cytokines and endothelial nitric oxide synthase (eNOS) activity, but only partially attenuate the effect of celastrol on AnII mediated HepG2 cell proliferation. Thus, celastrol has the potential for use in liver cancer therapy. ROS derived from mitochondrial is an important factor for celastrol to suppress HepG2 cell proliferation.ial is an important factor for celastrol to suppress HepG2 cell proliferation.)
Menze 2009 J Biol Chem + (Anhydrobiotic animals survive virtually co … Anhydrobiotic animals survive virtually complete loss of cellular water. The mechanisms that explain this phenomenon are not fully understood but often include the accumulation of low molecular weight solutes such as trehalose and macromolecules like Late Embryogenesis Abundant (LEA) proteins. Here we report for the first time the occurrence of a mitochondria-targeted LEA gene (Afrlea3m) product in an animal species. The deduced molecular mass of the 307-amino acid polypeptide from the brine shrimp ''Artemia franciscana'' is 34 kDa. Bioinformatic analyses reveal features typical of a Group 3 LEA protein, and subcellular localization programs predict targeting of the mature peptide to the mitochondrial matrix, based on an N-terminal, amphipathic presequence. Real-time quantitative PCR shows that ''Afralea3m'' mRNA is expressed manyfold higher in desiccation-tolerant embryonic stages when compared with intolerant nauplius larvae. Mitochondrial localization of the protein was confirmed by transfection of human hepatoma cells (HepG2/C3A) with a nucleotide construct encoding the first 70 N-terminal amino acids of ''AfrLEA3m'' in-frame with the nucleotide sequence for green fluorescence protein. The chimeric protein was readily incorporated into mitochondria of these cells. Successful targeting of a protein to human mitochondria by use of an arthropod signaling sequence clearly reveals the highly conserved nature of such presequences, as well as of the import machinery. Finally, mitochondria isolated from A. franciscana embryos, which naturally contain ''AfrLEA3m'' and trehalose, exhibit resistance to water stress (freezing) as evidenced by an unchanged capacity for oxidative phosphorylation on succinate + rotenone, a resistance that is absent in mammalian mitochondria lacking AfrLEA3m.n mammalian mitochondria lacking AfrLEA3m.)
Zhang 2022 Mol Med Rep + (Animal models for Parkinson's disease (PD) … Animal models for Parkinson's disease (PD) are very useful in understanding the pathogenesis of PD and screening for new therapeutic approaches. The present study compared two commonly used neurotoxin‑induced mouse models of chronic PD to guide model selection, explore the pathogenesis and mechanisms underlying PD and develop effective treatments. The chronic PD mouse models were established via treatment with rotenone or 1‑methyl‑4‑phenyl‑1,2,3,6-tetrahydropyridine (MPTP) for 6 weeks. The effects of rotenone and MPTP in the mice were compared by assessing neurobehavior, neuropathology and mitochondrial function through the use of the pole, rotarod and open field tests, immunohistochemistry for tyrosine hydroxylase (TH), glial fibrillary acidic protein (GFAP), ionized calcium‑binding adapter molecule 1 (Iba‑1), neuronal nuclear antigen (NeuN) and (p)S129 α‑synuclein, immunofluorescence for GFAP, Iba‑1 and NeuN, western blotting for TH, oxygen consumption, complex I enzyme activity. The locomotor activity, motor coordination and exploratory behavior in both rotenone and MPTP groups were significantly lower compared with the control group. However, behavioral tests were no significant differences between the two groups. In the MPTP group, the loss of dopaminergic (DA) neurons in the substantia nigra (SN) pars compacta, the reduction of the tyrosine hydroxylase content in the SN and striatum and the astrocyte proliferation and microglial activation in the SN were more significant compared with the rotenone group. Notably, mitochondrial‑dependent oxygen consumption and complex I enzyme activity in the SN were significantly reduced in the rotenone group compared with the MPTP group. In addition, Lewy bodies were present only in SN neurons in the rotenone group. Although no significant differences in neurobehavior were observed between the two mouse models, the MPTP model reproduced the pathological features of PD more precisely in terms of the loss of DA neurons, decreased dopamine levels and neuroinflammation in the SN. On the other hand, the rotenone model was more suitable for studying the role of mitochondrial dysfunction (deficient complex I activity) and Lewy body formation in the SN, which is a characteristic pathological feature of PD. The results indicated that MPTP and rotenone PD models have advantages and disadvantages, therefore one or both should be selected based on the purpose of the study.elected based on the purpose of the study.)
Tsilidis 2013 PLOS Biol + (Animal studies generate valuable hypothese … Animal studies generate valuable hypotheses that lead to the conduct of preventive or therapeutic clinical trials. We assessed whether there is evidence for excess statistical significance in results of animal studies on neurological disorders, suggesting biases. We used data from meta-analyses of interventions deposited in Collaborative Approach to Meta-Analysis and Review of Animal Data in Experimental Studies (CAMARADES). The number of observed studies with statistically significant results (O) was compared with the expected number (E), based on the statistical power of each study under different assumptions for the plausible effect size. We assessed 4,445 datasets synthesized in 160 meta-analyses on Alzheimer disease (n = 2), experimental autoimmune encephalomyelitis (n = 34), focal ischemia (n = 16), intracerebral hemorrhage (n = 61), Parkinson disease (n = 45), and spinal cord injury (n = 2). 112 meta-analyses (70%) found nominally (p≤0.05) statistically significant summary fixed effects. Assuming the effect size in the most precise study to be a plausible effect, 919 out of 4,445 nominally significant results were expected versus 1,719 observed (p<10−9). Excess significance was present across all neurological disorders, in all subgroups defined by methodological characteristics, and also according to alternative plausible effects. Asymmetry tests also showed evidence of small-study effects in 74 (46%) meta-analyses. Significantly effective interventions with more than 500 animals, and no hints of bias were seen in eight (5%) meta-analyses. Overall, there are too many animal studies with statistically significant results in the literature of neurological disorders. This observation suggests strong biases, with selective analysis and outcome reporting biases being plausible explanations, and provides novel evidence on how these biases might influence the whole research domain of neurological animal literature.rch domain of neurological animal literature.)
Lau 2017 Dissertation + (Animals are highly dependent on oxygen (O& … Animals are highly dependent on oxygen (O2). The use of O2, however, comes with both advantages and disadvantages. On one hand, O2 is key to the process that produces chemical energy within mitochondria inside the cell, on the other hand the use of O2 generates reactive oxygen species (ROS), which are harmful byproducts. In this thesis, I investigated these two aspects of O2 use at mitochondria from a group of sculpin fishes that are distributed along the marine intertidal zone and are naturally exposed to daily fluctuations of O2. I found that more hypoxia tolerant sculpins improved O2 binding at the level of mitochondria. However, this increased O2 binding was not associated with increased aerobic energy production, and counterintuitively, there was higher ROS generation in more hypoxia tolerant sculpins. It is possible that higher ROS generation in hypoxia tolerant sculpins is part of the strategy in surviving the O2 variable intertidal.ssible that higher ROS generation in hypoxia tolerant sculpins is part of the strategy in surviving the O2 variable intertidal.)
Tian 2017 Front Genet + (Animals that are able to sustain life unde … Animals that are able to sustain life under hypoxic conditions have long captured the imagination of biologists and medical practitioners alike. Although the associated morphological modifications have been extensively described, the mechanisms underlying the evolution of hypoxia tolerance are not well understood. To provide such insights, we investigated genes in four major energy metabolism pathways, and provide evidence of distinct evolutionary paths to mammalian hypoxia-tolerance. Positive selection of genes in the oxidative phosphorylation pathway mainly occurred in terrestrial hypoxia-tolerant species; possible adaptations to chronically hypoxic environments. The strongest candidate for positive selection along cetacean lineages was the citrate cycle signaling pathway, suggestive of enhanced aerobic metabolism during and after a dive. Six genes with cetacean-specific amino acid changes are rate-limiting enzymes involved in the gluconeogenesis pathway, which would be expected to enhance the lactate removal after diving. Intriguingly, 38 parallel amino acid substitutions in 29 genes were observed between hypoxia-tolerant mammals. Of these, 76.3% were radical amino acid changes, suggesting that convergent molecular evolution drives the adaptation to hypoxic stress and similar phenotypic changes. This study provides further insights into life under low oxygen conditions and the evolutionary trajectories of hypoxia-tolerant species. trajectories of hypoxia-tolerant species.)
Salin 2016 J Exp Biol + (Animals, especially ectotherms, are highly … Animals, especially ectotherms, are highly sensitive to the temperature of their surrounding environment. Extremely high temperature, for example, induces a decline of average performance of conspecifics within a population, but individual heterogeneity in the ability to cope with elevating temperatures has rarely been studied. In this study, we examined inter-individual variation in feeding ability and consequent growth rate of juvenile brown trout Salmo trutta acclimated to a high temperature (19°C), and investigated the relationship between these metrics of whole-animal performances and among-individual variation in mitochondrial respiration capacity. Food was provided ''ad libitum'' yet intake varied ten-fold amongst individuals, resulting in some fish losing weight whilst others continued to grow. Almost half of the variation in food intake was related to variability in mitochondrial capacity: low intake (and hence growth failure) was associated with high LEAK respiration rates within liver and muscle mitochondria, and a lower coupling of muscle mitochondria. These observations, combined with the inability of fish with low food consumption to increase their intake despite ''ad libitum'' food levels, suggest a possible insufficient capacity of the mitochondria for maintaining ATP homeostasis. Individual variation in thermal performance is likely to confer variation in the upper limit of an organism's thermal niche and in turn affect the structure of wild populations in warming environments.© 2016. Published by The Company of Biologists Ltd.ublished by The Company of Biologists Ltd.)
ESCI 2014 + (Annual Scientific Meeting of the European Society for Clinical Investigation , Utrecht, The Netherlands; [http://www.esci.eu.com/meetings/ ESCI 2014])
Ravasz 2024 Sci Rep + (Anoxia halts oxidative phosphorylation (OX … Anoxia halts oxidative phosphorylation (OXPHOS) causing an accumulation of reduced compounds in the mitochondrial matrix which impedes dehydrogenases. By simultaneously measuring oxygen concentration, NADH autofluorescence, mitochondrial membrane potential and ubiquinone reduction extent in isolated mitochondria in real-time, we demonstrate that Complex I utilized endogenous quinones to oxidize NADH under acute anoxia. 13C metabolic tracing or untargeted analysis of metabolites extracted during anoxia in the presence or absence of site-specific inhibitors of the electron transfer system showed that NAD+ regenerated by Complex I is reduced by the 2-oxoglutarate dehydrogenase Complex yielding succinyl-CoA supporting mitochondrial substrate-level phosphorylation (mtSLP), releasing succinate. Complex II operated amphidirectionally during the anoxic event, providing quinones to Complex I and reducing fumarate to succinate. Our results highlight the importance of quinone provision to Complex I oxidizing NADH maintaining glutamate catabolism and mtSLP in the absence of OXPHOS.bolism and mtSLP in the absence of OXPHOS.)
Komlodi 2018b EBEC2018 + (Anoxia leads to over-reduction of mitochon … Anoxia leads to over-reduction of mitochondrial coenzyme Q (Q, quinone) pools rendering Complex I unable to oxidize NADH, leading to a profound decrease in the matrix NAD+/NADH ratio. As a consequence, the function of matrix dehydrogenases is impaired. Yet, under certain anoxic conditions catabolism of metabolites converging through the α-ketoglutarate dehydrogenase Complex (KGDHC) is known to occur, yielding succinyl-CoA, in turn supporting substrate-level phosphorylation substantiated by succinate-CoA ligase [1].Mitochondrial respiration and NADH autofluorescence were measured simultaneously with the NextGen-O2k (Oroboros Instruments, Innsbruck, Austria), and the redox state of the Q-pool was detected with a three-electrode system implanted into the O2k (Oroboros Q2k).We show that in isolated mouse liver mitochondria Complex I utilizes endogenous quinones oxidizing NADH during anoxia. Untargeted metabolomic analysis of matrix metabolites of mitochondria subjected to respiratory arrest due to anoxia and in the presence of specific inhibitors of respiratory complexes infer showed that NAD+ arising from Complex I is utilized by KGDHC yielding succinyl-CoA for succinate-CoA ligase, thus maintaining substrate-level phosphorylation during anoxia. Finally, by using custom-made 3D-printed plugs designed for standard fluorometric cuvettes, we show that under no conditions of respiratory arrest due to anoxia and/or pharmacological inhibition of the complexes did the mitochondria undergo swelling, which could potentially confound matrix metabolite estimations or bioenergetic parameters due to permeability transition.Our results highlight the importance of the availability of quinones in conjunction with the operation of Complex I in maintaining substrate-level phosphorylation during anoxia.ex I in maintaining substrate-level phosphorylation during anoxia.)
Ravasz 2019 Abstract IOC141 + (Anoxia leads to over-reduction of mitochon … Anoxia leads to over-reduction of mitochondrial quinone pools hampering Complex I from oxidizing NADH, leading to a profound decrease in the matrix NAD+/NADH ratio. As a consequence of this, the function of matrix dehydrogenases is impaired. Yet, under certain anoxic conditions catabolism of metabolites converging through the ketoglutarate dehydrogenase complex (KGDHC) is known to occur yielding succinyl-CoA, in turn supporting substrate-level phosphorylation substantiated by succinate-CoA ligase. Here, by measuring simultaneously oxygen partial pressure and NADH autofluorescence or quinone redox state we show that in isolated mitochondria Complex I utilizes endogenous quinones oxidizing NADH during anoxia. Untargeted metabolomic analysis of matrix metabolites of anoxic mitochondria and in the presence of ETS inhibitors inferred that NAD+ arising from Complex I is utilized by KGDHC yielding succinyl-CoA for succinate-CoA ligase, thus maintaining substrate-level phosphorylation during anoxia. The amount of endogenous quinones was estimated to be in the millimolar range and was unaffected by dietary intake of vitamin K3 (menadione). The quinone pools could be reduced by Complexes I and II and the electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) system during anoxia, exhibiting a descending order of affinity and reciprocally, increasing order of capacity. Our results highlight the importance of quinone availability in conjunction to Complex I-mediated NADH oxidation in maintaining substrate-level phosphorylation during anoxia.trate-level phosphorylation during anoxia.)
Ravasz 2018 Abstract The evolving concept of mitochondria + (Anoxia leads to over-reduction of mitochon … Anoxia leads to over-reduction of mitochondrial quinone pools hampering Complex I from oxidizing NADH, leading to a profound decrease in the matrix NAD+/NADH ratio. As a consequence of this, the function of matrix dehydrogenases is impaired. Yet, under certain anoxic conditions catabolism of metabolites converging through the ketoglutarate dehydrogenase Complex (KGDHC) is known to occur yielding succinyl-CoA, in turn supporting substrate-level phosphorylation substantiated by succinate-CoA ligase. Here, by measuring simultaneously oxygen partial pressure and NADH autofluorescence or quinone redox state we show that in isolated mitochondria Complex I utilizes endogenous quinones oxidizing NADH during anoxia. Untargeted metabolomic analysis of matrix metabolites of anoxic mitochondria and in the presence of ETC inhibitors inferred that NAD+ arising from Complex I is utilized by KGDHC yielding succinyl-CoA for succinate-CoA ligase, thus maintaining substrate-level phosphorylation during anoxia. The amount of endogenous quinones was estimated to be in the millimolar range and was unaffected by dietary intake of vitamin K3 (menadione). The quinone pools could be reduced by Complexes I and II and the electron transfer flavoprotein-ubiquinone oxidoreductase (ETF-QO) system during anoxia, exhibiting a descending order of affinity and reciprocally, increasing order of capacity. Our results highlight the importance of quinone availability in conjunction to Complex I-mediated NADH oxidation in maintaining substrate-level phosphorylation during anoxia.trate-level phosphorylation during anoxia.)
Buck 2012 Adv Exp Med Biol + (Anoxia rapidly elicits hyper-excitability … Anoxia rapidly elicits hyper-excitability and cell death in mammal brain but this is not so in anoxia-tolerant turtle brain where spontaneous electrical activity is suppressed by anoxia (i.e. spike arrest; SA). In anoxic turtle brain extracellular GABA concentrations increase dramatically and impact GABAergic synaptic transmission in a way that results in SA. Here we briefly review what is known about the regulation of glutamatergic signalling during anoxia and investigate the possibility that in anoxic turtle cortical neurons GABA(A/B) receptors play an important role in neuroprotection. Both AMPA and NMDA receptor currents decrease by about 50% in anoxic turtle cerebrocortex and therefore exhibit channel arrest, whereas GABA-A receptor currents increase twofold and increase whole-cell conductance. The increased post synaptic GABA-A receptor current is contrary to the channel arrest hypothesis but it does serve an important function. The reversal potential of the GABA-A receptor (E(GABA)) is only slightly depolarized relative to the resting membrane potential of the neuron and not sufficient to elicit an action potential. Therefore, when GABA-A receptors are activated, membrane potential moves to E(GABA) and prevents further depolarization by glutamatergic inputs during anoxia by a process termed shunting inhibition. Furthermore we discuss the presynaptic role of GABA-B receptors and show that increased endogenous GABA release during anoxia mediates SA by activating both GABA-A and B receptors and that this represents a natural oxygen-sensitive adaptive mechanism to protect brain from anoxic injury.anism to protect brain from anoxic injury.)
Gnaiger 1987 Physiol Zool + (Anoxic heat dissipation of ''Lumbriculus v … Anoxic heat dissipation of ''Lumbriculus variegatus'', as measured by direct calorimetry, is reduced by up to 85 % relative to aerobic rates. The decrease of anoxic heat dissipation and the diminution of activity peaks in the calorimetric output coincide with the disappearance of peristaltic movements under anoxia. A transfer from aerobic conditions with food to anoxia without food results in cessation of defecation when the gut is half emptied, whereas the gut is completely emptied under aerobic conditions within 6 and 8-10 h at 20 and 11 °C, respectively. The aerobic retention time of the food is independent of worm length (10-50 mm). After aerobic feeding the gut content is higher than after anoxic feeding at 6 °C. On return to aerobic conditions, heat dissipation increases immediately, whereas defecation is resumed only after a lag of 2 h. An anoxic component to the aerobic heat dissipation becomes apparent in relation to simultaneous respirometric measurements when feces accumulate in the calorimetric chamber. When the guts are completely emptied before the experiment, the theoretical oxycaloric equivalent yields an accurate estimate of heat dissipation, indicating that no significant net formation of anoxic end products occurs under aerobic conditions. Anoxic catabolism of glycogen may not fully explain the directly measured rates of heat dissipation under environmental anoxia. This has been suggested earlier for ''Lumbriculus'' and has since been confirmed for ''Tubifex'' on the basis of simultaneous calorimetric and biochemical measurements. Direct calorimetry is required to assess total rates of metabolic energy expenditure in anoxic oligochaetes.energy expenditure in anoxic oligochaetes.)
Martinez 2013 Marine Biol + (Antarctic fauna are highly adapted to the … Antarctic fauna are highly adapted to the frigid waters of the Southern Ocean. This study describes the ''in vitro'' temperature sensitivity of oxygen consumption rates measured in liver mitochondria from the pelagic notothenioid ''Pleuragramma antarcticum'' between 5 and 35 °C. Oxygen fluxes were measured after the addition of millimolar levels of pyruvate, malate, succinate and glutamate (LEAK) and saturating levels of ADP [oxidative phosphorylation (OXPHOS)]. OXPHOS respiration significantly decreased above 18.7 °C. A comparison of the oxidative capacities among ''P. antarcticum'' and other notothenioids showed significant differences in OXPHOS respiration, where benthic species exhibited about 50% lower OXPHOS capacities than ''P. antarcticum''. In addition, OXPHOS capacities normalized per milligram of mitochondrial protein of ''P''. antarcticum'' were up to eight times higher than those reported in the literature for other notothenioids. The comparatively high respiration rates measured in this study may be explained by our approach, which engaged both Complexes I and II under conditions of oxidative phosphorylation. OXPHOS capacities of independently activated Complexes I and II were found to range from 42 to 100% of rates obtained when both complexes were activated simultaneously in the same species. The remarkable tolerance of ''P. antarcticum'' OXPHOS toward warmer temperatures was unexpected for an Antarctic stenotherm and may indicate that thermal sensitivity of their mitochondria is not the driving force behind their stenothermy.he driving force behind their stenothermy.)
Strobel 2013 PLoS One + (Antarctic notothenioid fish are characteri … Antarctic notothenioid fish are characterized by their evolutionary adaptation to the cold, thermostable Southern Ocean, which is associated with unique physiological adaptations to withstand the cold and reduce energetic requirements but also entails limited compensation capacities to environmental change. This study compares the capacities of mitochondrial acclimation to ocean warming and acidification between the Antarctic nototheniid ''Notothenia rossii'' and the sub-Antarctic ''Lepidonotothen squamifrons'', which share a similar ecology, but different habitat temperatures. After acclimation of ''L. squamifrons'' to 9 °C and ''N. rossii'' to 7 °C (normocapnic/hypercapnic, 0.2 kPa CO2/2000 ppm CO2) for 4-6 weeks, we compared the capacities of their mitochondrial respiratory complexes I (CI) and II (CII), their P/O ratios (phosphorylation efficiency), proton leak capacities and mitochondrial membrane fatty acid compositions. Our results reveal reduced CII respiration rates in warm-acclimated ''L. squamifrons'' and cold hypercapnia-acclimated ''N. rossii''. Generally, ''L. squamifrons'' displayed a greater ability to increase CI contribution during acute warming and after warm-acclimation than N. rossii. Membrane unsaturation was not altered by warm or hypercapnia-acclimation in both species, but membrane fatty acids of warm-acclimated ''L. squamifrons'' were less saturated than in warm normocapnia-/hypercapnia-acclimated ''N. rossii''. Proton leak capacities were not affected by warm or hypercapnia-acclimation of ''N. rossii''. We conclude that an acclimatory response of mitochondrial capacities may include higher thermal plasticity of CI supported by enhanced utilization of anaplerotic substrates (via oxidative decarboxylation reactions) feeding into the citrate cycle. ''L. squamifrons'' possesses higher relative CI plasticities than N. rossii, which may facilitate the usage of energy efficient NADH-related substrates under conditions of elevated energy demand, possibly induced by ocean warming and acidification. The observed adjustments of electron transport system complexes with a higher flux through CI under warming and acidification suggest a metabolic acclimation potential of the sub-Antarctic ''L. squamifrons'', but only limited acclimation capacities for ''N. rossii''. acclimation capacities for ''N. rossii''.)
Skemiene 2020 J Bioenerg Biomembr + (Anthocyanins are considered as bioactive c … Anthocyanins are considered as bioactive components of plant-based diets that provide protection against ischemic cardiovascular pathologies by mechanisms dependent on their antioxidant and reductive capacities. However, it is not clear whether similar anthocyanin-mediated mechanisms can provide protection against ischemia-induced brain mitochondrial injury and cell death. In this study, we compared effects of three cyanidin-3-glycosides - glucoside (Cy3G), galactoside (Cy3Gal) and rutinoside (Cy3R), with pelargonxidin-3-glucoside (Pg3G) and found that at 10-20 μM concentrations they have no direct effect on respiratory functions of mitochondria isolated from normal or ischemia-damaged rat brain slices. However, intravenous injection of Cy3Gal and Cy3G (0,025 mg/kg or 0,05 mg/kg what matches 10 μM or 20 μM respectively) but not Cy3R in rats protected against ischemia-induced caspase activation and necrotic cell death, and reduced infarct size in cerebral cortex and cerebellum. These effects correlated with cytochrome c reducing capacity of cyanidin-3-glycosides. In contrast, intravenous injection of 0,025 mg/kg Pg3G which has the lowest cytochrome c reducing capacity among investigated anthocyanins, had no effect on ischemia-induced caspase activation and necrosis but reduced brain infarct size whereas intravenous injection of 0,05 mg/kg of Pg3G slightly promoted necrosis in the brain. Our data suggest that reductive rather than antioxidant capacities of anthocyanins may be important components in providing protection against ischemic brain damage. protection against ischemic brain damage.)
Skemiene 2015 FEBS J + (Anthocyanins, a subclass of flavonoids, ar … Anthocyanins, a subclass of flavonoids, are known to protect against myocardial ischemia; however, little is known about their direct, acute effects on mitochondria injured by the ischemic insult. In this study, the effects of delphinidin 3-O-glucoside (Dp3G), cyanidin 3-O-glucoside (Cy3G) and pelargonidin 3-O-glucoside (Pg3G) on the activity of complex I of the mitochondrial respiratory chain were studied in mitochondria isolated from normal rat hearts and rat hearts subjected to ischemia for 45 min. Cy3G and Dp3G increased the activity of complex I, measured in the presence or absence of coenzyme Q1 (CoQ1 ), in ischemia-damaged mitochondria, whereas in nonischemic mitochondria the effect was observed only in the absence of CoQ1. Dp3G and Cy3G but not Pg3G increased state 3 respiration and ATP synthesis with NADH-dependent substrates in mitochondria after ischemia. The results suggest that certain anthocyanins can act as electron acceptors at complex I, and bypass ischemia-induced inhibition, resulting in increased ATP production after ischemia. This study provides new information on a possible role of certain anthocyanins in the regulation of energy metabolism in mammalian cells.ertain anthocyanins in the regulation of energy metabolism in mammalian cells.)
Jirkovsky 2012 J Pharmacol Exp Ther + (Anthracycline anticancer drugs (e.g., doxo … Anthracycline anticancer drugs (e.g., doxorubicin or daunorubicin) can induce chronic cardiotoxicity and heart failure (HF), both of which are believed to be based on oxidative injury and mitochondrial damage. In this study, molecular and functional changes induced by chronic anthracycline treatment with progression into HF in post-treatment follow-up were analyzed with special emphasis on nuclear factor erythroid 2-related factor 2 (Nrf2) and peroxisome proliferator-activated receptor-γ coactivator-1α (PGC1α) pathways. Chronic cardiotoxicity was induced in rabbits with daunorubicin (3 mg/kg, weekly for 10 weeks), and the animals were followed for another 10 weeks. Echocardiography revealed a significant drop in left ventricular (LV) systolic function during the treatment with marked progression to LV dilation and congestive HF in the follow-up. Although daunorubicin-induced LV lipoperoxidation was found, it was only loosely associated with cardiac performance. Furthermore, although LV oxidized glutathione content was increased, the oxidized-to-reduced glutathione ratio itself remained unchanged. Neither Nrf2, the master regulator of antioxidant response, nor the majority of its target genes showed up-regulation in the study. However, down-regulation of manganese superoxide dismutase and NAD(P)H dehydrogenase [quinone] 1 were observed together with heme oxygenase 1 up-regulation. Although marked perturbations in mitochondrial functions were found, no induction of PGC1α-controlled mitochondrial biogenesis pathway was revealed. Instead, especially in the post-treatment period, an impaired regulation of this pathway was observed along with down-regulation of the expression of mitochondrial genes. These results imply that global oxidative stress need not be a factor responsible for the development of anthracycline-induced HF, whereas suppression of mitochondrial biogenesis might be involved.itochondrial biogenesis might be involved.)
Govender 2015 Abstract MiPschool Cape Town 2015 + (Anthracyclines, such as doxorubicin (DXR), … Anthracyclines, such as doxorubicin (DXR), are among the most valuable treatments for various cancers, but their clinical use is limited due to detrimental side-effects such as cardiotoxicity. DXR-induced cardiotoxicity is emerging as a critical issue among cancer survivors and is an area of much significance to the field of cardio-oncology. The abundance of mitochondria in cardiomyocytes closely links mitochondrial bioenergetics with myocardial function and viability [1]. It has been demonstrated that DXR specifically targets mitochondria and increases the generation of reactive oxygen species (ROS), decreases adenosine triphosphate (ATP) production and modulates mitochondrial sirtuin activity; thus, mitochondrial dysfunction has recently been recognized as a pivotal element in the development of DXR-induced cardiotoxicity [2]. In light of this scenario, both endogenously produced and exogenously administered melatonin during or prior chemotherapy shows great promise in this therapeutic avenue as demonstrated in various studies [3]. MLT is a potent anti-oxidant, is non-toxic, is dually oncostatic and cardio-protective, and has been shown to influence mitochondrial homeostasis and function [3,4]. Although a number of studies support the mitochondrial protective role of MLT, the exact mechanisms by which MLT confers mitochondrial protection in the context of DXR-induced cardiotoxicity remain to be elucidated. This study evaluated the role of MLT on mitochondrial function, mitochondrial dynamics and cell death during DXR-induced cardiotoxicity. H9C2 rat cardiac myoblasts were pre-treated with MLT (10 µM) for 24h followed by DXR treatment (3 µM) for 24h. Following treatment, mitochondrial reductive capacity and apoptotic cell death were assessed. Mitochondrial bioenergetic parameters was analysed using the XF96 analyser (extracellular flux). These results indicate a significant decrease in mitochondrial reductive capacity in response to DXR treatment versus the control (38.88 ± 0.3435 % vs 100%, ''p''< 0.0001). Cells pre-treated with MLT followed by DXR treatment showed a significant increase in mitochondrial reductive capacity versus the DXR treated group only (97.45 ± 0.3733 % vs 38.88 ± 0.3435 %, ''p''< 0.0001). Furthermore, a significant decrease in caspase 3/7 activity was detected when cells were pre-treated with MLT followed by DXR treatment versus the DXR treated group only (1.649 ± 0.084 fold vs 2.307± 0.1035 fold, ''p''< 0.001). ATP turnover was significantly increased when cells were pre-treated with MLT followed by DXR treatment versus the DXR treated group only (48.39 ± 3.797 % vs 64.43 ± 2.670 %, ''p''< 0.001). These results strongly indicate that pre-treatment with MLT confers a mitochondrial cardioprotective effect during DXR-induced cardiotoxicity by significantly increasing cardiac myocytes viability and influencing mitochondrial bioenergetics.viability and influencing mitochondrial bioenergetics.)
Jose 2018 Redox Biol + (Anti-cancer effects of local anesthetics h … Anti-cancer effects of local anesthetics have been reported but the mode of action remains elusive. Here, we examined the bioenergetic and REDOX impact of levobupivacaine on human prostate cancer cells (DU145) and corresponding non-cancer primary human prostate cells (BHP). Levobupivacaine induced a combined inhibition of glycolysis and oxidative phosphorylation in cancer cells, resulting in a reduced cellular ATP production and consecutive bioenergetic crisis, along with reactive oxygen species generation. The dose-dependent inhibition of respiratory chain complex I activity by levobupivacaine explained the alteration of mitochondrial energy fluxes. Furthermore, the potency of levobupivacaine varied with glucose and oxygen availability as well as the cellular energy demand, in accordance with a bioenergetic anti-cancer mechanism. The levobupivacaine-induced bioenergetic crisis triggered cytostasis in prostate cancer cells as evidenced by a S-phase cell cycle arrest, without apoptosis induction. In DU145 cells, levobupivacaine also triggered the induction of autophagy and blockade of this process potentialized the anti-cancer effect of the local anesthetic. Therefore, our findings provide a better characterization of the REDOX mechanisms underpinning the anti-effect of levobupivacaine against human prostate cancer cells.Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.ed by Elsevier B.V. All rights reserved.)
Gouspillou 2015 Sci Rep + (Anticancer treatments for childhood acute … Anticancer treatments for childhood acute lymphoblastic leukaemia (ALL) are highly effective but are now implicated in causing impaired muscle function in long-term survivors. However, no comprehensive assessment of skeletal muscle mitochondrial functions in long-term survivors has been performed and the presence of persistent chemotherapy-induced skeletal muscle mitochondrial dysfunction remains a strong possibility. Non-tumour-bearing mice were treated with two drugs that have been used frequently in ALL treatment (doxorubicin and dexamethasone) for up to 4 cycles at 3-week intervals and euthanized 3 months after the 4th cycle. Treated animals had impaired growth and lower muscle mass as well as reduced mitochondrial respiration and increased reactive oxygen species production per unit oxygen consumption. Mitochondrial DNA content and protein levels of key mitochondrial membrane proteins and markers of mitochondrial biogenesis were unchanged, but protein levels of Parkin were reduced. This suggests a novel pattern of chemotherapy-induced mitochondrial dysfunction in skeletal muscle that persists because of an acquired defect in mitophagy signaling. The results could explain the observed functional impairments in adult survivors of childhood ALL and may also be relevant to long-term survivors of other cancers treated with similar regimes.ther cancers treated with similar regimes.)
Lotkova 2011 Gen Physiol Biophys + (Antiinflammatory effect of statins mediate … Antiinflammatory effect of statins mediated by the reduction of cytokine IL-6 in hepatocytes have been reported. Contrary to beneficial effect, statins can increase susceptibility to mitochondrial dysfunction. Extrahepatic biliary obstruction is associated with oxidative stress, pro-inflammatory response and hepatocyte mitochondrial dysfunction. The aim of our study was to verify the effect of fluvastatin on cholestatic liver injury. Cholestasis was induced in Wistar rats by bile duct ligation. Fluvastatin (1 or 5 mg/kg) was administered after surgery and then daily for 7 days. The dose of 5 mg/kg led to the deterioration of hepatocellular injury. Despite lower production of IL-6, decrease in GSH content, rise of TGFß and inhibition of respiratory complex I in mitochondria were determined. The mRNA expressions of canalicular transporter Mdr1b and basolateral transporter Mrp3 increased in cholestatic liver. Fluvastatin administration then led to the attenuation of this change. Analogously, mRNA expression of conjugative enzyme Ugt1a1 was diminished by fluvastatin administration to cholestatic rats. We can conclude that decrease in the antioxidative status and mitochondrial dysfunction could at least in part participate on the deteriorating effect of fluvastatin. Whether these processes can be a consequence of the alteration in metabolism and transport of potentially toxic substances remains to verify.tially toxic substances remains to verify.)
James 2005 J Biol Chem + (Antioxidants, such as ubiquinones, are wid … Antioxidants, such as ubiquinones, are widely used in mitochondrial studies as both potential therapies and useful research tools. However, the effects of exogenous ubiquinones can be difficult to interpret because they can also be pro-oxidants or electron carriers that facilitate respiration. Recently we developed a mitochondria-targeted ubiquinone (MitoQ10) that accumulates within mitochondria. MitoQ10 has been used to prevent mitochondrial oxidative damage and to infer the involvement of mitochondrial reactive oxygen species in signaling pathways. However, uncertainties remain about the mitochondrial reduction of MitoQ10, its oxidation by the respiratory chain, and its pro-oxidant potential. Therefore, we compared MitoQ analogs of varying alkyl chain lengths (MitoQn, n = 3-15) with untargeted exogenous ubiquinones. We found that MitoQ10 could not restore respiration in ubiquinone-deficient mitochondria because oxidation of MitoQ analogs by complex III was minimal. Complex II and glycerol 3-phosphate dehydrogenase reduced MitoQ analogs, and the rate depended on chain length. Because of its rapid reduction and negligible oxidation, MitoQ10 is a more effective antioxidant against lipid peroxidation, peroxynitrite and superoxide. Paradoxically, exogenous ubiquinols also autoxidize to generate superoxide, but this requires their deprotonation in the aqueous phase. Consequently, in the presence of phospholipid bilayers, the rate of autoxidation is proportional to ubiquinol hydrophilicity. Superoxide production by MitoQ10 was insufficient to damage aconitase but did lead to hydrogen peroxide production and nitric oxide consumption, both of which may affect cell signaling pathways. Our results comprehensively describe the interaction of exogenous ubiquinones with mitochondria and have implications for their rational design and use as therapies and as research tools to probe mitochondrial function.rch tools to probe mitochondrial function.)
Viall 2013 J Autoimmun + (Antiphospholipid antibodies (aPL) are the … Antiphospholipid antibodies (aPL) are the strongest maternal risk factor for pre-eclampsia, a hypertensive disease of human pregnancy. Pre-eclampsia is triggered by a toxic factor released from the placenta that activates the maternal endothelium. Antiphospholipid antibodies cause the release of necrotic trophoblast debris from the placental syncytiotrophoblast and this debris can activate endothelial cells. In this study, we investigated how aPL affects syncytiotrophoblast death and production of necrotic trophoblast debris by examining the interaction between aPL and human first trimester placental explants. Human polyclonal and murine monoclonal aPL, but not control antibodies, were rapidly internalised by the syncytiotrophoblast. Inhibitors of endocytosis or the low-density lipoprotein receptor (LDLR) family, but not toll-like receptors, decreased the internalisation of aPL and prevented the release of necrotic trophoblast debris from the syncytiotrophoblast. Once internalised, aPL increased inner mitochondrial membrane leak and Cytochrome c release while depressing oxidative flux through Complex IV of the electron transport system in syncytiotrophoblast mitochondria. These data suggest that the human syncytiotrophoblast internalises aPL by antigen-dependent endocytosis involving LDLR family members. Once internalised by the syncytiotrophoblast, aPL affects the death-regulating mitochondria, causing extrusion of necrotic trophoblast debris which can activate maternal endothelial cells thereby contributing to the pathogenesis of pre-eclampsia.ting to the pathogenesis of pre-eclampsia.)
Quast 2022 Basic Res Cardiol + (Aortic valve stenosis (AS) is the most fre … Aortic valve stenosis (AS) is the most frequent valve disease with relevant prognostic impact. Experimental model systems for AS are scarce and comprehensive imaging techniques to simultaneously quantify function and morphology in disease progression are lacking. Therefore, we refined an acute murine AS model to closely mimic human disease characteristics and developed a high-resolution magnetic resonance imaging (MRI) approach for simultaneous in-depth analysis of valvular, myocardial as well as aortic morphology/pathophysiology to identify early changes in tissue texture and critical transition points in the adaptive process to AS. AS was induced by wire injury of the aortic valve. Four weeks after surgery, cine loops, velocity, and relaxometry maps were acquired at 9.4 T to monitor structural/functional alterations in valve, aorta, and left ventricle (LV). ''In vivo'' MRI data were subsequently validated by histology and compared to echocardiography. AS mice exhibited impaired valve opening accompanied by significant valve thickening due to fibrotic remodelling. While control mice showed bell-shaped flow profiles, AS resulted not only in higher peak flow velocities, but also in fragmented turbulent flow patterns associated with enhanced circumferential strain and an increase in wall thickness of the aortic root. AS mice presented with a mild hypertrophy but unaffected global LV function. Cardiac MR relaxometry revealed reduced values for both T1 and T2 in AS reflecting subtle myocardial tissue remodelling with early alterations in mitochondrial function in response to the enhanced afterload. Concomitantly, incipient impairments of coronary flow reserve and myocardial tissue integrity get apparent accompanied by early troponin release. With this, we identified a premature transition point with still compensated cardiac function but beginning textural changes. This will allow interventional studies to explore early disease pathophysiology and novel therapeutic targets.ophysiology and novel therapeutic targets.)
Wojewoda MiP2010 + (Apart from generally recognised role as AT … Apart from generally recognised role as ATP generators, mitochondria are also main reactive oxygen species (ROS) producers in the cells. Since we found that ROS level was altered in human NARP cells linked to NARP (Neuropathy, Ataxia and Retinitis Pigmentosa) syndrome and Rho0 cells [1], we hypothesised that ROS are implicated in regulation of mitochondrial biogenesis. We also used antioxidant (sodium selenite, 70 nM) that decreased ROS level in these cells [1] to establish to what extent these changes depended on ROS-mediated retrograde communication. Cell lines: human osteosarcoma cell lines: wild type (WT) cell line, cybrid cells (NARP) with default ATP synthase (mtDNA point mutation in subunit 6 of ATP synthase) and cells lacking mtDNA (Rho0). Laser scanning cytometry: ROS level, mitochondrial mass. Western blotting: the level of transcription factors and respiratory subunits; the level of respiratory subunits corresponds with the level of appropriate respiratory complexes since the chosen subunits are labile when their complexes are not assembled. Confocal imaging: localisation of NRF2 phosphorylated at Ser 40. Respiration: oxygen consumption measured with Clark type oxygen electrodeNuclear respiratory factors 1 and 2 (NRF1 and NRF2) are major regulators of respiratory gene expression. We found that the level of NRF1 was increased in NARP and Rho0 cells when compared with WT control. Selenium supplementation lead to further increase in NRF1 level. Since an increase in Akt/Protein kinase B phosphorylation at serine 473 (pAkt (Ser473)) was associated with activation of NRF1 transcriptional activity [2], we also assessed the level of pAkt (Ser473) in these cells. Subsequently, we established the activity of NRF2 (measured by its phosphorylation at serine 40 and found it altered in NARP and Rho0 cells. Comparison of pNRF2 (Ser 40) level with total level of NRF2 revealed that its activity was enhanced in cell lines with mtDNA defects. Moreover, we found that selenite further increased NRF2 phosphorylation. mtDNA defects in NARP and Rho0 cells also triggered adaptive changes at the level of respiratory subunits which were upregulated in NARP but downregulated in Rho0 cells. Selenite lowered the level of some respiratory subunits in WT and NARP cells without affecting their respiratory capacity.In cells with mtDNA defects the retrograde communication from mitochondria to nucleus modulates adaptive changes in mitochondrial biogenesis at the level of respiratory chain complexes via affecting nuclear respiratory factors. Because selenite supplementation affected both the level/activity of NRFs and the level of some respiratory subunits, we show that ROS play a significant role in the regulation of mitochondrial biogenesis.1. Wojewoda M, Duszyński J, Szczepanowska J (2010) Antioxidant defence systems and generation of reactive oxygen species in osteosarcoma cells with defective mitochondria; effect of selenium. Biochim. Biophys. Acta [doi:10.1016/j.bbabio.2010.01.035]2. Piantadosi CA, Suliman HB (2006) Mitochondrial transcription factor A induction by redox activation of nuclear respiratory factor 1. J. Biol. Chem. 281 324-333.tory factor 1. J. Biol. Chem. 281 324-333.)
Ratcliffe 2022 Clin Med (Lond) + (Apart from giving an overview of the findi … Apart from giving an overview of the findings themselves and their role in physiological oxygen homeostasis, I'd like to highlight the twists and turns of the experimental work, in particular the way that knowledge builds on knowledge in unexpected ways. Abraham Flexner, the US educationist, wrote a famous essay in the early twentieth century on the ‘usefulness of useless knowledge’.1 I'd like to paraphrase Flexner by emphasising the ‘importance of incomplete knowledge’. Our politicians are impatient for the utility of knowledge, perhaps not unreasonably, and our editors, perhaps less reasonably, are so often concerned with its completeness. Of course, most in tonight's audience will know that neither qualification of knowledge is valid. But nevertheless, I wish to emphasise the concerns I have, in case, in the face of societal or government impatience, or even that of our own peers, we lose our way.ience, or even that of our own peers, we lose our way.)
Ajime 2020 Nicotine Tob Res + (Apart from its adverse effects on the resp … Apart from its adverse effects on the respiratory system, cigarette smoking also induces skeletal muscle atrophy and dysfunction. Whether short-term smoking cessation can restore muscle mass and function is unknown. We therefore studied the impact of 1- and 2-weeks smoking cessation on skeletal muscles in a mouse model.Male mice were divided into 4 groups: Air-exposed (14 weeks); cigarette smoke (CS)-exposed (14 weeks); CS-exposed (13 weeks) followed by 1-week cessation; CS-exposed (12 weeks) followed by 2 weeks cessation to examine exercise capacity, physical activity levels, body composition, muscle function, capillarization, mitochondrial function and protein expression in the soleus, plantaris and diaphragm muscles.CS-induced loss of body and muscle mass was significantly improved within 1 week of cessation due to increased lean and fat mass. Mitochondrial respiration and protein levels of the respiratory complexes in the soleus were lower in CS-exposed mice, but similar to control values after 2 weeks of cessation. Exposing isolated soleus muscles to CS extracts reduced mitochondrial respiration that was reversed after removing the extract. While physical activity was reduced in all groups, exercise capacity, limb muscle force, fatigue resistance, fiber size and capillarization and diaphragm cytoplasmic HIF-1α were unaltered by CS-exposure. However, CS-induced diaphragm atrophy and increased capillary density was not seen after 2 weeks of smoking cessation.In male mice, two weeks smoking cessation reversed smoking-induced mitochondrial dysfunction, limb muscle mass loss and diaphragm muscle atrophy, highlighting immediate benefits of cessation on skeletal muscles.© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Research on Nicotine and Tobacco. All rights reserved. For permissions, please e-mail: [email protected].se e-mail: [email protected].)
Gomez-Valades 2021 Cell Metab + (Appropriate cristae remodeling is a determ … Appropriate cristae remodeling is a determinant of mitochondrial function and bioenergetics and thus represents a crucial process for cellular metabolic adaptations. Here, we show that mitochondrial cristae architecture and expression of the master cristae-remodeling protein OPA1 in proopiomelanocortin (POMC) neurons, which are key metabolic sensors implicated in energy balance control, is affected by fluctuations in nutrient availability. Genetic inactivation of OPA1 in POMC neurons causes dramatic alterations in cristae topology, mitochondrial Ca2+ handling, reduction in alpha-melanocyte stimulating hormone (α-MSH) in target areas, hyperphagia, and attenuated white adipose tissue (WAT) lipolysis resulting in obesity. Pharmacological blockade of mitochondrial Ca2+ influx restores α-MSH and the lipolytic program, while improving the metabolic defects of mutant mice. Chemogenetic manipulation of POMC neurons confirms a role in lipolysis control. Our results unveil a novel axis that connects OPA1 in POMC neurons with mitochondrial cristae, Ca2+ homeostasis, and WAT lipolysis in the regulation of energy balance.t;/sup> homeostasis, and WAT lipolysis in the regulation of energy balance.)
Cortassa 2019 Front Physiol + (Appropriate substrate selection between fa … Appropriate substrate selection between fats and glucose is associated with the success of interventions that maintain health such as exercise or caloric restriction, or with the severity of diseases such as diabetes or other metabolic disorders. Although the interaction and mutual inhibition between glucose and fatty-acids (FAs) catabolism has been studied for decades, a quantitative and integrated understanding of the control and regulation of substrate selection through central catabolic pathways is lacking. We addressed this gap here using a computational model representing cardiomyocyte catabolism encompassing glucose (Glc) utilization, pyruvate transport into mitochondria and oxidation in the tricarboxylic acid (TCA) cycle, β-oxidation of palmitate (Palm), oxidative phosphorylation, ion transport, pH regulation, and ROS generation and scavenging in cytoplasmic and mitochondrial compartments. The model is described by 82 differential equations and 119 enzymatic, electron transport and substrate transport reactions accounting for regulatory mechanisms and key players, namely pyruvate dehydrogenase (PDH) and its modulation by multiple effectors. We applied metabolic control analysis to the network operating with various Glc to Palm ratios. The flux and metabolites' concentration control were visualized through heat maps providing major insights into main control and regulatory nodes throughout the catabolic network. Metabolic pathways located in different compartments were found to reciprocally control each other. For example, glucose uptake and the ATP demand exert control on most processes in catabolism while TCA cycle activities and membrane-associated energy transduction reactions exerted control on mitochondrial processes namely β-oxidation. PFK and PDH, two highly regulated enzymes, exhibit opposite behavior from a control perspective. While PFK activity was a main rate-controlling step affecting the whole network, PDH played the role of a major regulator showing high sensitivity (elasticity) to substrate availability and key activators/inhibitors, a trait expected from a flexible substrate selector strategically located in the metabolic network. PDH regulated the rate of Glc and Palm consumption, consistent with its high sensitivity toward AcCoA, CoA, and NADH. Overall, these results indicate that the control of catabolism is highly distributed across the metabolic network suggesting that fuel selection between FAs and Glc goes well beyond the mechanisms traditionally postulated to explain the glucose-fatty-acid cycle.d to explain the glucose-fatty-acid cycle.)
Scattolin 2016 Abstract Mito Xmas Meeting Innsbruck + (Approximately 20% of T-cell acute lymphobl … Approximately 20% of T-cell acute lymphoblastic leukemia (T-ALL) patients do not respond to current therapy, and their clinical outcome is dismal.In the present study we show that leukemic cells isolated from T-ALL patients as well as cell lines stabilized ''in vitro'' or propagated ''in vivo'' as xenografts exhibit high levels of mitochondrial reactive oxygen species (ROS). Interestingly, raising mitochondrial ROS using NS1619, a small molecule that opens the mitochondrial BK K+ channel, induced death of leukemic cells from T-ALL patients and T-ALL cell lines but not of primary normal thymocytes or PBMC. These effects were enhanced by blunting ROS-scavenging pathways with dehydroepiandrosterone (DHEA), an inhibitor of the pentose phosphate pathway (PPP). The combination of NS1619 and DHEA led to proteolytic processing of OPA1, an inner mitochondrial membrane protein that controls cristae remodeling, cytochrome c release and apoptosis. OPA1 cleavage was dependent upon both ROS and the OMA1 mitochondrial protease. Furthermore, OPA1 cleavage induced by treatment with NS1619 and DHEA primed T-ALL cells to apoptosis induced by TNF-Related Apoptosis Inducing Ligand (TRAIL).These findings suggest that engaging the OMA1-OPA1 axis by raising mitochondrial ROS may prove to be an effective strategy for apoptotic priming of refractory T-ALL, which poses a major clinical challenge at present.LL, which poses a major clinical challenge at present.)
Silic-Benussi 2016a Abstract Mito Xmas Meeting Innsbruck + (Approximately 20% of T-cell acute lymphobl … Approximately 20% of T-cell acute lymphoblastic leukemia (T-ALL) patients do not respond to current therapy, and their clinical outcome is dismal. The PI3K/Akt/mTOR oncogenic pathway is commonly found hyper-activated in T-ALL. In addition to controlling cell growth and autophagy, mTORC1 influences mitochondrial activity and oxidative metabolism by controlling the interaction between YY1 and PGC1.In previous studies, we showed that T-ALL cells exhibit high levels of mitochondrial reactive oxygen species (ROS). ROS are powerful signalling molecules that can induce apoptosis through p53 activation, but may also increase cancer cell survival through PTEN oxidation, which results in an increased Akt activity. In the present study, we aimed at testing the possible cross-talk between mTOR and ROS in T-ALL. Interestingly, ''in vitro'' studies revealed that the mTORC1-inhibitor Everolimus increased ROS levels and induced cell death both in T-ALL cell lines and patient-derived T-ALL xenografts (PDTALL) but not in primary normal thymocytes. In addition, Everolimus increased the dexamethasone sensitivity of the glucocorticoid-resistant PDTALL19 ''in vitro''. The finding that Everolimus-induced cell death was reduced by pre-treatment with the ROS scavenger N-acetyl-cystein (NAC) indicates that this effect was ROS-dependen. ''In vivo'' experiments carried out using PDTALL cells showed that Everolimus significantly reduced the number of leukemic cells and increased the survival of treated-mice. These studies indicate a connection between mTOR and ROS, and suggest that mTORC1 inhibition may prove to be effective to overcome dexamethasone-resistance of refractory T-ALL patients.e-resistance of refractory T-ALL patients.)
Antona 2022 Cancers (Basel) + (Approximately 50% of colorectal cancer (CR … Approximately 50% of colorectal cancer (CRC) patients still die from recurrence and metastatic disease, highlighting the need for novel therapeutic strategies. Drug repurposing is attracting increasing attention because, compared to traditional ''de novo'' drug discovery processes, it may reduce drug development periods and costs. Epidemiological and preclinical evidence support the antitumor activity of antipsychotic drugs. Herein, we dissect the mechanism of action of the typical antipsychotic spiperone in CRC. Spiperone can reduce the clonogenic potential of stem-like CRC cells (CRC-SCs) and induce cell cycle arrest and apoptosis, in both differentiated and CRC-SCs, at clinically relevant concentrations whose toxicity is negligible for non-neoplastic cells. Analysis of intracellular Ca2+ kinetics upon spiperone treatment revealed a massive phospholipase C (PLC)-dependent endoplasmic reticulum (ER) Ca2+ release, resulting in ER Ca2+ homeostasis disruption. RNA sequencing revealed unfolded protein response (UPR) activation, ER stress, and induction of apoptosis, along with IRE1-dependent decay of mRNA (RIDD) activation. Lipidomic analysis showed a significant alteration of lipid profile and, in particular, of sphingolipids. Damage to the Golgi apparatus was also observed. Our data suggest that spiperone can represent an effective drug in the treatment of CRC, and that ER stress induction, along with lipid metabolism alteration, represents effective druggable pathways in CRC.h lipid metabolism alteration, represents effective druggable pathways in CRC.)
Ikaga 2015 Biochem Biophys Rep + (Aquaporin-8 (AQP8), a member of the aquapo … Aquaporin-8 (AQP8), a member of the aquaporin water channel family, is expressed in various tissue and cells, including liver, testis, and pancreas. AQP8 appears to have functions on the plasma membrane and/or on the mitochondrial inner membrane. Mitochondrial AQP8 with permeability for water, H2O2 and NH3 has been expected to have important role in various cells, but its information is limited to a few tissues and cells including liver and kidney. In the present study, we found that AQP8 was expressed in the mitochondria in mouse adipose tissues and 3T3-L1 preadipocytes, and investigated its role by suppressing its gene expression.AQP8-knocked down (shAQP8) cells were established using a vector expressing short hairpin RNA. Cellular localization of AQP8 was examined by western blotting and immunocytochemistry. Mitochondrial function was assessed by measuring mitochondrial membrane potential, oxygen consumption and ATP level measurements.In 3T3-L1 cells, AQP8 was expressed in the mitochondria. In shAQP8 cells, mRNA and protein levels of AQP8 were decreased by about 75%. The shAQP8 showed reduced activities of complex IV and ATP synthase; it is probable that the impaired mitochondrial water handling in shAQP8 caused suppression of the electron transport and ADP phosphorylation through inhibition of the two steps which yield water. The reduced activities of the last two steps of oxidative phosphorylation in shAQP8 cause low routine and maximum capacity of respiration and mitochondrial hyperpolarization.Mitochondrial AQP8 contributes to mitochondrial respiratory function probably through maintenance of water homeostasis.The AQP8-knocked down cells we established provides a model system for the studies on the relationships between water homeostasis and mitochondrial function.ies on the relationships between water homeostasis and mitochondrial function.)
Thoral 2023 J Exp Biol + (Aquatic ecosystems can exhibit seasonal va … Aquatic ecosystems can exhibit seasonal variation in resource availability and animals have evolved to cope with the associated caloric restriction. During winter in the NW Mediterranean Sea, the European sardine Sardina pilchardus naturally experiences caloric restriction due to a decrease in diversity and quantity of plankton. Ongoing global warming has, however, had deleterious effects on plankton communities such that food shortages may occur throughout the year, especially under warm conditions in the summer. We investigated the interactive effects of temperature and food availability on sardine metabolism, by continuously monitoring whole-animal respiration of groups of control (fed) and food-deprived sardines over a 60-day experiment in winter (12°C) or summer (20°C) conditions under natural photoperiod. In addition, we measured mitochondrial respiration of red muscle fibres, biometric variables and energy reserves, of individuals sampled at 30 and 60 days. This revealed that winter food deprivation elicits energy saving mechanisms at whole animal and cellular levels by maintaining a low metabolism to preserve energy reserves, allowing high survival. By contrast, despite energy saving mechanisms at the mitochondrial level, whole animal metabolic rate was high during food deprivation in summer, causing increased consumption of energy reserves at the muscular level and high mortality after 60 days. Furthermore, a 5-day refeeding did not improve survival and mortalities actually continued, suggesting that long-term food deprivation at high temperatures caused profound stress in sardines that potentially impaired nutrient absorption. potentially impaired nutrient absorption.)
Gnaiger 1987 Hydrobiol + (Aquatic oligochaetes are well known for th … Aquatic oligochaetes are well known for their ability to resist prolonged periods of anoxia. In fact, the observed mortality is more likely to result from laboratory stress (unnatural sediment, starvation, accumu1ation of toxic substances) than from lack of oxygen per se. ''Lumbriculus variegatus'' feeds under anoxia at 6 °C at a low rate and survives more than 40 days. A sudden transfer into anoxic water, however, results in a cessation of defaecation before the gut is half emptied, whereas the gut is completely emptied under aerobic conditions within 8-10 hours (11 °C).1Anoxic heat dissipation as measured by direct calorimetry2,3 is reduced by up to 80% relative to aerobic rates. The basal rate of oxygen uptake is independent of PO2 , above 3 kPa (15% air saturation), but the active rate shows a high degree of oxygen conformity. Whereas the theoretical oxycaloric equivalent yields an accurate estimation of aerobic heat dissipation in ''Lumbriculus'', anoxic catabolism of glycogen explains only up to 60% of the directly measured rates of anoxic heat dissipation in ''Lumbriculus'' and ''Tubifex''. Since unknown bioenergetic processes may be important under anoxia, direct calorimetry is required to assess total rates of energy expenditure in anoxic oligochaetes.s required to assess total rates of energy expenditure in anoxic oligochaetes.)
Kajma MiP2010 + (Arachidonic acid (AA) is a [[polyunsaturated fatty acid]] … Arachidonic acid (AA) is a [[polyunsaturated fatty acid]] (PUFA) which is highly concentrated in the membranes of the neuronal cells. Pathological conditions in the brain, such as ischemia increase the levels of AA in the cytoplasm [1]. Several lines of evidence indicate that the potent neuroprotective effect of PUFA may be linked with potassium channels. Moreover recent evidence suggests that potassium transport via channels presented in the inner mitochondrial membrane can trigger neuroprotection [2].In our study a single channel activity was measured with the use of patch-clamp of the mitoplasts isolated from embryonic hippocampal neurons. Mitoplasts were prepared from the sample of the mitochondria by addition to a hypotonic solution to induce swelling following outer membrane rapture. Our data provide evidence for the presence of large-conductance calcium activated potassium channels (mtBKCa) in the inner mitochondrial membrane of rat hippocampus. The channel conductance calculated based on current-voltage relations was equal to 288 pS. The activity of the channel deceased at low calcium concentration. Additionally, the channel activity was blocked by paxilline (inhibitor of the BKCa types channels). Moreover we demonstrated that the probability of opening of this channel is increased after the application of arachidonic acid. We also identified a novel channel which has current-voltage characteristics similar to the rectifying potassium channels. The channel conductance was equal to 60 pS. Patch-clamp studies showed that this channel is not sensitive to the known activators and inhibitors of mitochondrial potassium channels, but is regulated by arachidonic acid.In summary, the findings presented in this study provide new functional data suggesting the presence of the two channels in the rat hippocampus mitochondria: BKCa–type and rectifying potassium channel, both regulated by arachidonic acid.Grant sponsor: Ministry of Science and Higher Education P-N/031/20061. Adibhatla RM, Hatcher J F (2006) Phospholipase A2, reactive oxygen species, and lipid peroxidation in cerebral ischemia. Free Radical Biol. Med. 40: 376-387.2. Szewczyk A, Jarmuszkiewicz W, Kunz WS (2009) Mitochondrial potassium channels. IUBMB Life 61: 134-143.otassium channels. IUBMB Life 61: 134-143.)
Bauer 2013 Forensic Sci Int Genet (B) + (Archaeological excavations conducted at an … Archaeological excavations conducted at an early mediaeval cemetery in Volders (Tyrol, Austria) produced 141 complete skeletal remains dated between the 5th/6th and 12th/13th centuries. These skeletons represent one of the largest historical series of human remains ever discovered in the East Alpine region. Little historical information is available for this region and time period. The good state of preservation of these bioarchaeological finds offered the opportunity of performing molecular genetic investigations. Adequate DNA extraction methods were tested in the attempt to obtain as high DNA yields as possible for further analyses. Molecular genetic sex-typing using a dedicated PCR multiplex ("Genderplex") gave interpretable results in 88 remains, 78 of which had previously been sexed based on morphological features. We observed a discrepancy in sex determination between the two methods in 21 cases. An unbiased follow-up morphological examination of these finds showed congruence with the DNA results in all but five samples.h the DNA results in all but five samples.)
Brecht 2016 Toxicol In Vitro + (Arctigenin has previously been identified … Arctigenin has previously been identified as a potential anti-tumor treatment for advanced pancreatic cancer. However, the mechanism of how arctigenin kills cancer cells is not fully understood. In the present work we studied the mechanism of toxicity by arctigenin in the human pancreatic cell line, Panc-1, with special emphasis on the mitochondria. A comparison of Panc-1 cells cultured in glucose versus galactose medium was applied, allowing assessments of effects in glycolytic versus oxidative phosphorylation (OXPHOS)-dependent Panc-1 cells. For control purposes, the mitochondrial toxic response to treatment with arctigenin was compared to the anti-cancer drug, sorafenib, which is a tyrosine kinase inhibitor known for mitochondrial toxic off-target effects (Will et al., 2008). In both Panc-1 OXPHOS-dependent and glycolytic cells, arctigenin dissipated the mitochondrial membrane potential, which was demonstrated to be due to inhibition of the mitochondrial complexes II and IV. However, arctigenin selectively killed only the OXPHOS-dependent Panc-1 cells. This selective killing of OXPHOS-dependent Panc-1 cells was accompanied by generation of ER stress, mitochondrial membrane permeabilization and caspase activation leading to apoptosis and aponecrosis.Copyright © 2016 Elsevier Ltd. All rights reserved. © 2016 Elsevier Ltd. All rights reserved.)
Burtscher 2012 High Alt Med Biol + (Arnold Durig (1872-1961) grew up in the Au … Arnold Durig (1872-1961) grew up in the Austrian mountains in the period when intense exploration of the Alps started. As an enthusiastic mountaineer, scientist, and physician, he became one of the pioneers exploring physiological and pathophysiological aspects of humans sojourning to high altitudes. At the beginning of the 20th century, Durig was one of the great physiologists whose knowledge covered the whole field of physiology. Durig founded a renowned School and his students spread all over the world. He stayed in close contact with many colleagues and famous scientists, such as Albert Einstein and Sigmund Freud. Although he was an extremely productive and acknowledged physiologist and teacher at that time, his work and life are not very well known at the beginning of the 3rd millennium, even by high altitude physiologists. Thus, this article provides an overview on Durig's life and work, highlighting the most important scientific studies he performed at moderate and high altitudes, in an attempt to provide a few links to the development of high altitude research in the late 19th and early 20th centuries, complemented by some comments from a current Point of view.p>th centuries, complemented by some comments from a current Point of view.)
Zhang 2015 Stem Cells + (Arsenic is a global health hazard that imp … Arsenic is a global health hazard that impacts over 140 million individuals worldwide. Epidemiological studies reveal prominent muscle dysfunction and mobility declines following arsenic exposure; yet, mechanisms underlying such declines are unknown. The objective of this study was to test the novel hypothesis that arsenic drives a maladaptive fibroblast phenotype to promote pathogenic myomatrix remodeling and compromise the muscle stem (satellite) cell (MuSC) niche. Mice were exposed to environmentally-relevant levels of arsenic in drinking water before receiving a local muscle injury. Arsenic-exposed muscles displayed pathogenic matrix remodeling, defective myofiber regeneration and impaired functional recovery, relative to controls. When naïve human MuSCs were seeded onto 3D decellularized muscle constructs derived from arsenic-exposed muscles, cells displayed an increased fibrogenic conversion and decreased myogenicity, compared to cells seeded onto control constructs. Consistent with myomatrix alterations, fibroblasts isolated from arsenic-exposed muscle displayed sustained expression of matrix remodeling genes, the majority of which were mediated by NF-κB. Inhibition of NF-κB during arsenic exposure preserved normal myofiber structure and functional recovery after injury, suggesting that NF-κB signaling serves as an important mechanism of action for the deleterious effects of arsenic on tissue healing. Taken together, the results from this study implicate myomatrix biophysical and/or biochemical characteristics as culprits in arsenic-induced MuSC dysfunction and impaired muscle regeneration. It is anticipated that these findings may aid in the development of strategies to prevent or revert the effects of arsenic on tissue healing and, more broadly, provide insight into the influence of the native myomatrix on stem cell behavior.he native myomatrix on stem cell behavior.)
Chen 2019 Ecotoxicol Environ Saf + (Arsenic is a toxic metalloid that can caus … Arsenic is a toxic metalloid that can cause male reproductive malfunctions and is widely distributed in the environment. The aim of this study was to investigate the cytotoxicity of arsenic trioxide (ATO) induced GC-1 spermatogonial (spg) cells. Our results found that ATO increased the levels of catalase (CAT) and malonaldehyde (MDA) and reactive oxygen species (ROS), while decreasing glutathione (GSH) and the total antioxidant capacity (T-AOC). Therefore, ATO triggered oxidative stress in GC-1 spg cells. In addition, ATO also caused severe mitochondrial dysfunction that included an increase in residual oxygen consumption (ROX), and decreased the routine respiration, maximal and ATP-linked respiration (ATP-L-R), as well as spare respiratory capacity (SRC), and respiratory control rate (RCR); ATO also damaged the mitochondrial structure, including mitochondrial cristae disordered and dissolved, mitochondrial vacuolar degeneration. Moreover, degradation of p62, LC3 conversion, increasing the number of acidic vesicle organelles (AVOs) and autophagosomes and autolysosomes are demonstrated that the cytotoxicity of ATO may be associated with autophagy. Meanwhile, the metabolomics analysis results showed that 20 metabolites (10 increased and 10 decreased) were significantly altered with the ATO exposure, suggesting that maybe there are the perturbations in amino acid metabolism, lipid metabolism, glycan biosynthesis and metabolism, metabolism of cofactors and vitamins. We concluded that ATO was toxic to GC-1 spg cells via inducing oxidative stress, mitochondrial dysfunction and autophagy as well as the disruption of normal metabolism. This study will aid our understanding of the mechanisms behind ATO-induced spermatogenic toxicity.Copyright © 2019 Elsevier Inc. All rights reserved. 2019 Elsevier Inc. All rights reserved.)
Tweedie 2011 Am J Physiol Regul Integr Comp Physiol + (Artificial selection in rat has yielded hi … Artificial selection in rat has yielded high-capacity runners (HCR) and low-capacity runners (LCR) that differ in intrinsic (untrained) aerobic exercise ability and metabolic disease risk. To gain insight into how oxygen metabolism may have been affected by selection, we compared mitochondrial function, oxidative DNA damage (8-dihydroxy-guanosine; 8dOHG), and antioxidant enzyme activities in soleus muscle (Sol) and gastrocnemius muscle (Gas) of adult and aged LCR vs. HCR rats. In Sol of adult HCR rats, maximal ADP-stimulated respiration was 37% greater, whereas in Gas of adult HCR rats, there was a 23% greater complex IV-driven respiratory capacity and 54% greater leak as a fraction of electron transport capacity (suggesting looser mitochondrial coupling) vs. LCR rats. H2O2 emission per gram of muscle was 24-26% greater for both muscles in adult HCR rats vs. LCR, although H2O2 emission in Gas was 17% lower in HCR, after normalizing for citrate synthase activity (marker of mitochondrial content). Despite greater H2O2 emission, 8dOHG levels were 62-78% lower in HCR rats due to 62-96% higher superoxide dismutase activity in both muscles and 47% higher catalase activity in Sol muscle in adult HCR rats, with no evidence for higher 8 oxoguanine glycosylase (OGG1; DNA repair enzyme) protein expression. We conclude that genetic segregation for high running capacity has generated a molecular network of cellular adaptations, facilitating a superior response to oxidative stress.y has generated a molecular network of cellular adaptations, facilitating a superior response to oxidative stress.)
Moll 2016 bioRxiv + (As a consequence of the ongoing demographi … As a consequence of the ongoing demographic change, osteoporosis is considered as one of the mayor challenges for the health care system of the 21st century. However, the exact etiology of osteoporosis is far from being understood. Some evidence suggests that changes in stem cell metabolism might contribute to development of the disease. Therefore we evaluated whether differences of the morphology and/or the energy metabolism of mitochondria can be observed between human bone marrow derived mesenchymal stem cells obtained from osteoporotic patients as compared to non-osteoporotic controls. Mesenchymal stem cells were isolated from the bone marrow of senile osteoporotic and non osteoporotic patients, osteoporosis being assessed by dual energy X-ray absorptiometry. We then confirmed the stemness of the cells by FACS analysis of the expression of surface markers and by conducting multi-lineage differentiation experiments. And we finally investigated mitochondrial morphology and function with electron microscopy of cryo-fixed samples and by high-resolution respirometry, respectively. In addition we compared the energy metabolism of the stem cells to those of the osteosarcoma cell line MG-63. The data show, for the first time, the applicability on stem cells of the methods used here. Furthermore, our results indicated that there are no obvious differences detectable in mitochondrial morphology between cells from osteoporotic and non osteoporotic donors and that these cells also seem to be energetically indistinguishable with unchanged rates of ROUTINE respiration and respiratory capacity as well as unaltered oxygen consumption rates linked to different respiratory complexes. In summary, we could not detect any evidence indicating major changes of mitochondrial features in cells from osteoporotic patients.tures in cells from osteoporotic patients.)
Lemieux 2013 Abstract MiP2013 + (As a consequence of the rising overall obe … As a consequence of the rising overall obesity and aging of the population, insulin resistance (IR) and type 2 diabetes mellitus (T2DM) are becoming more prevalent in developing countries. Although evidence has been accumulating that T2DM is accompanied by mitochondrial dysfunction in muscles, the link between the mitochondrial dysfunction and the pathogenesis of T2DM remains unclear [1]. T2DM is a complex disease that causes various changes in the body metabolism. The difficulty is to identify mitochondrial defects involved in the cause of the disease rather than those that occur as consequences of the disease. Our study aims at understanding the role of mitochondrial metabolism in the muscle during the early stages of T2DM. The fructose-fed rat was used as the animal model of pre-diabetes. After only 6 weeks of a fructose-enriched diet (10% fructose added to the drinking water), rats showed clear signs of IR (glucose tolerance test). Mitochondrial respiration was measured in permeabilized muscle fibers using high-resolution respirometry (Oroboros Instruments, Austria) in the cardiac muscle and in two skeletal muscles, one oxidative (soleus) and one glycolytic (extensor digitorum longus, EDL). A wide range of substrates were used in order to cover the carbohydrate metabolism and the fatty acid oxidation. Acylcarnitine profiles were also measured in each tissue. The mitochondrial content was preserved in skeletal muscle as shown by the lack of difference of citrate synthase (CS) activity and Complex IV respiration. In the heart, CS activity was slightly, but significantly, reduced in the fructose-fed rats. The soleus muscle shows a decrease in Complex II respiration (succinate+rotenone) whereas the EDL muscle shows reduced Complex I and CI+II respiration in the presence of pyruvate but not when glutamate is used as a substrate. There is no defect in fatty acid oxidation with the soleus muscle in fructose-fed animals. The EDL muscle, however, shows a defect located in the long-chain acyl-CoA dehydrogenase (LCAD). Surprisingly, the mitochondrial dysfunction in the heart mirrors the mitochondrial dysfunction in the EDL muscle, rather than in the soleus.Our results highlight important early mitochondrial dysfunction associated with T2DM. The defects are clearly specific to the type of muscle studied. Furthermore, our study also points to the importance of differences between human and animal models because the role of LCAD in fatty acid oxidation is significant in rodent muscles but not in most human tissues [2].muscles but not in most human tissues [2].)
Floyd 2022 Lancet + (As a group of clinicians, we voice our con … As a group of clinicians, we voice our concerns about recent changes to publication fees. Having coauthored an original article together, we were faced with the dilemma of having to pay £2000 in publication fees. This contrasts with a situation only 2 years ago when publication in most journals was free of charge or only incurred a small administration fee. The situation was further compounded by the fact that these costs are similar across the major journals in our specialty (appendix). Our institution has no dedicated funds to cover publication fees, and we were faced with either having to pay ourselves or retracting the manuscript. It was later agreed that our department would cover the costs on a compassionate basis. cover the costs on a compassionate basis.)
Kaiser 2017 Science + (As a growing number of biologists formally … As a growing number of biologists formally share their papers in online repositories before any peer review or journal publication, it’s often said that they are catching up with physicists, who have posted preprints in the online arXiv server since 1991. But biomedical scientists actually made a start earlier, reveals a researcher who has traced the "forgotten experiment" in which the National Institutes of Health (NIH) created a preprint exchange in the 1960s that publishers ultimately forced to close.hat publishers ultimately forced to close.)
Wu 2022 Neuromolecular Med + (As a multi-functional cellular organelle, … As a multi-functional cellular organelle, mitochondrial metabolic reprogramming is well recognized as a hallmark of cancer. The center of mitochondrial metabolism is oxidative phosphorylation (OXPHOS), in which cells use enzymes to oxidize nutrients, thereby converting the chemical energy to the biological energy currency ATPs. OXPHOS also creates the mitochondrial membrane potential and serve as the driving force of other mitochondrial metabolic pathways and experiences significant reshape in the different stages of tumor progression. In this minireview, we reviewed the major mitochondrial pathways that are connected to OXPHOS and are affected in cancer cells. In addition, we summarized the function of novel bio-active molecules targeting mitochondrial metabolic processes such as OXPHOS, mitochondrial membrane potential and mitochondrial dynamics. These molecules exhibit intriguing preclinical and clinical results and have been proven to be promising antitumor candidates in recent studies.ng antitumor candidates in recent studies.)
Luo 2020 Int J Mol Sci + (As an essential organelle in nucleated euk … As an essential organelle in nucleated eukaryotic cells, mitochondria play a central role in energy metabolism, maintenance of redox balance, and regulation of apoptosis. Mitochondrial dysfunction, either due to the TCA cycle enzyme defects, mitochondrial DNA genetic mutations, defective mitochondrial electron transport chain, oxidative stress, or aberrant oncogene and tumor suppressor signaling, has been observed in a wide spectrum of human cancers. In this review, we summarize mitochondrial dysfunction induced by these alterations that promote human cancers.se alterations that promote human cancers.)
Mosegaard 2020 Int J Mol Sci + (As an essential vitamin, the role of ribof … As an essential vitamin, the role of riboflavin in human diet and health is increasingly being highlighted. Insufficient dietary intake of riboflavin is often reported in nutritional surveys and population studies, even in non-developing countries with abundant sources of riboflavin-rich dietary products. A latent subclinical riboflavin deficiency can result in a significant clinical phenotype when combined with inborn genetic disturbances or environmental and physiological factors like infections, exercise, diet, aging and pregnancy. Riboflavin, and more importantly its derivatives, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), play a crucial role in essential cellular processes including mitochondrial energy metabolism, stress responses, vitamin and cofactor biogenesis, where they function as cofactors to ensure the catalytic activity and folding/stability of flavoenzymes. Numerous inborn errors of flavin metabolism and flavoenzyme function have been described, and supplementation with riboflavin has in many cases been shown to be lifesaving or to mitigate symptoms. This review discusses the environmental, physiological and genetic factors that affect cellular riboflavin status. We describe the crucial role of riboflavin for general human health, and the clear benefits of riboflavin treatment in patients with inborn errors of metabolism.patients with inborn errors of metabolism.)
Hickey 2014 Abstract MiP2014 + (As approximately 80% of diabetics die from … As approximately 80% of diabetics die from heart failure, understanding diabetic cardiomyopathy is crucial. Mitochondria occupy 35-40% of the mammalian cardiomyocyte volume, supply 95% of the hearts’ ATP, and diabetic heart mitochondria show impaired structure, arrangement and function. We predict that bioenergetic inefficiencies are present in diabetic heart mitochondria; therefore, we explored mitochondrial proton and electron handling by linking oxygen flux within streptozotocin (STZ)-induced-diabetic Sprague-Dawley rat heart tissues, to steady-state ATP synthesis, reactive oxygen species (ROS) production and mitochondrial membrane potential (Δ''Ψ''). By coupling high-resolution respirometers with purpose-built fluorometers, we followed Magnesium Green (ATP synthesis), Amplex Ultra Red (ROS production) and safranin-O (Δ''Ψ''). Relative to control rats, the tissue-mass specific respiration of STZ-diabetic hearts was depressed in oxidative phosphorylating (OXPHOS) states. Steady-state ATP synthesis capacity was almost a third lower in STZ-diabetic heart and relative to O2 flux, this equates to an estimated 12% depression in OXPHOS efficiency. However, with anoxic transition, STZ-diabetic and control heart tissues showed similar ATP hydrolysis capacities through reversal of the F1/F0 ATP synthase. STZ-diabetic cardiac mitochondria also produced more net ROS, relative to oxygen flux (ROS/O) in the OXPHOS state. While Δ''Ψ'' did not differ between groups, the time to develop Δ''Ψ'' with the onset of OXPHOS was protracted in STZ-diabetic mitochondria. ROS/O is higher in life-like OXPHOS states, and potential delays in the time to develop Δ''Ψ'' may delay ATP synthesis with inter-beat fluctuations in ADP concentrations. Whereas diabetic cardiac mitochondria produce less ATP in normoxia, they consume as much ATP in anoxic infarct-like states (Fig. 1). in normoxia, they consume as much ATP in anoxic infarct-like states (Fig. 1).)
Pham 2014 Am J Physiol + (As approximately 80% of diabetics die from … As approximately 80% of diabetics die from heart failure, understanding diabetic cardiomyopathy is crucial. Mitochondria occupy 35-40% of mammalian cardiomyocyte volume, supply 95% of the hearts' ATP, and diabetic heart mitochondria show impaired structure, arrangement and function. We predict that bioenergetic efficiencies are present in diabetic heart mitochondria; therefore we explored mitochondrial proton and electron handling by linking oxygen flux within streptozotocin (STZ)-induced-diabetic Sprague-Dawley rat heart tissues, to steady-state ATP synthesis, Reactive Oxygen Species (ROS) production, and mitochondrial membrane potential (Δ''Ψ''). By coupling high-resolution respirometers with purpose-built fluorometers, we followed Magnesium Green (ATP synthesis), Amplex Ultra Red (ROS production), and safranin-O (Δ''Ψ''). Relative to control rats, the mass-specific respiration of STZ-diabetic hearts was depressed in oxidative phosphorylating (OXPHOS) states. Steady-state ATP synthesis capacity was almost a third lower in STZ-diabetic heart and relative to O2 flux, this equates to an estimated 12% depression in OXPHOS efficiency. However, with anoxic transition, STZ-diabetic and control heart tissues showed similar ATP hydrolysis capacities through reversal of the F1/F0 ATP-synthase. STZ-diabetic cardiac mitochondria also produced more net ROS relative to oxygen flux (ROS/O) in OXP. While Δ''Ψ'' did not differ between groups, the time to develop Δ''Ψ'' with the onset of OXPHOS was protracted in STZ-diabetic mitochondria. ROS/O is higher in life-like OXPHOS states and potential delays in the time to develop Δ''Ψ'' may delay ATP synthesis with inter-beat fluctuations in ADP concentrations. Whereas diabetic cardiac mitochondria produce less ATP in normoxia, they consume as much ATP in anoxic infarct-like states.as much ATP in anoxic infarct-like states.)
Grewal 2020 Exp Neurol + (As components of the Mediterranean diet (M … As components of the Mediterranean diet (MedDiet) olive polyphenols may play a crucial role for the prevention of Alzheimer's disease (AD). Since mitochondrial dysfunction is involved in both, brain ageing and early AD, effects of 10 different purified phenolic secoiridoids (hydroxytyrosol, tyrosol, oleacein, oleuroside, oleuroside aglycon, oleuropein, oleocanthal, ligstroside, ligstroside aglycone and ligustaloside B) and two metabolites (the plant metabolite elenolic acid and the mammalian metabolite homovanillic acid) were tested in very low doses on mitochondrial function in SH-SY5Y-APP695 cells - a cellular model of early AD. All tested secoiridoids significantly increased basal ATP levels in SY5Y-APP695 cells. Oleacein, oleuroside, oleocanthal and ligstroside showed the highest effect on ATP levels and were additionally tested on mitochondrial respiration. Only oleocanthal and ligstroside were able to enhance the capacity of respiratory chain complexes. To investigate their underlying molecular mechanism, the expression of genes associated with mitochondrial biogenesis, respiration and antioxidative capacity (PGC1-α, SIRT1, CREB1, NRF1, TFAM, complex I, IV and V, GPx1, SOD2, CAT) were determined using RT-PCR. Exclusively ligstroside increased mRNA expression of SIRT1, CREB1, complex I, and GPx1. Furthermore, oleocanthal but not ligstroside decreased Aβ 1-40 levels in SH-SY5Y-APP695 cells. To investigate the ''in vivo'' effects of purified secoiridoids, the two most promising compounds (oleocanthal and ligstroside) were tested in a mouse model of ageing. Female NMRI mice, aged 12 months, received a diet supplemented with 50 mg/kg diet oleocanthal or ligstroside for 6 months (equivalent to 6.25 mg/kg b.w.). Young (3 months) and aged (18 months) mice served as controls. Ligstroside fed mice showed improved spatial working memory. Furthermore, ligstroside restored brain ATP levels in aged mice and led to a significant life extension compared to aged control animals. Our findings indicate that purified ligstroside has outstanding performance on mitochondrial bioenergetics in models of early AD and brain ageing by mechanisms that may not interfere with Aβ production. Additionally, ligstroside expanded the lifespan in aged mice and enhanced cognitive function.Copyright © 2019. Published by Elsevier Inc.gnitive function. Copyright © 2019. Published by Elsevier Inc.)
Ponsot 2005 J Cell Physiol + (As energetic metabolism is crucial for mus … As energetic metabolism is crucial for muscles, they develop different adaptations to respond to fluctuating demand among muscle types. Whereas quantitative characteristics are known, no study described simultaneously quantitative and qualitative differences among muscle types in terms of substrates utilization patterns. This study thus defined the pattern of substrates preferential utilization by mitochondria from glycolytic gastrocnemius (GAS) and oxidative soleus (SOL) skeletal muscles and from heart left ventrical (LV) in rats. We measured in situ, ADP (2 mM)-stimulated, mitochondrial respiration rates from skinned fibers in presence of increasing concentrations of pyruvate (Pyr) + malate (Mal), palmitoyl-carnitine (Palm-C) + Mal, glutamate (Glut) + Mal, glycerol-3-phosphate (G3-P), lactate (Lact) + Mal. Because the fibers oxygen uptake (Vs) followed Michaelis-Menten kinetics in function of substrates level we determined the Vs and Km, representing maximal oxidative capacity and the mitochondrial sensibility for each substrate, respectively. Vs were in the order GAS < SOL < LV for Pyr, Glu, and Palm-C substrates, whereas in the order SOL = LV < GAS with G3-P. Moreover, the relative capacity to oxidize Palm-C is extremely higher in LV than in SOL. Vs was not stimulated by the Lact substrate. The Km was equal for Pyr among muscles, but much lower for G3-P in GAS and lower for Palm-C in LV. These results demonstrate qualitative mitochondrial tissue specificity for metabolic pathways. Mitochondria of glycolytic muscle fibers are well adapted to play a central role for maintaining a satisfactory cytosolic redox state in these fibers, whereas mitochondria of LV developed important capacities to use fatty acids. developed important capacities to use fatty acids.)
Salin 2015 Abstract MiP2015 + (As global temperatures rise, there is a gr … As global temperatures rise, there is a growing need to understand the proximate causes that determine the boundary of an organism’s thermal niche. Individuals can vary in how they respond to temperature increases, but the mechanisms responsible for this inter-individual variation are unclear.Here we tested the hypothesis that individual performance at high temperatures depends on mitochondrial respiratory properties. We assessed the food intake in an ''ad libitum'' diet, rate of growth in mass and length, and mitochondrial function in liver and white muscle of juvenile brown trout ''Salmo trutta'' gradually acclimated to the high testing temperature (19°C).Food intake and growth rate were highly variable amongst fish: food intake varied by 10 among individuals, some fish did not grow, some lost body weight whilst others grew and increased body mass. Around 50% of the individual variation in food intake was explained by liver and muscle mitochondrial function. Individuals with the highest LEAK respiration in liver and muscle exhibited the lowest food intake. Moreover, food intake was worst in individuals with a lower muscle phosphorylating respiration, and in turn a lower respiratory control ratio (RCR). After accounting for food intake, no aspect of mitochondrial function could explain individual variation in growth.Our results demonstrate that individuals with higher LEAK respiration and lower coupling in mitochondria (as estimated by the RCR) had the poorest performance, suggesting that their capacity for ATP production at 19°C could not support an adequate foraging. Our findings suggest that differences in the ability of mitochondria to generate ATP could shape the boundary of an individual’sthermal niche.boundary of an individual’s thermal niche.)
Fangue 2009 J Exp Biol + (As global temperatures rise, there is a gr … As global temperatures rise, there is a growing need to understand the physiological mechanisms that determine an organism's thermal niche. Here, we test the hypothesis that increases in mitochondrial capacity with cold acclimation and adaptation are associated with decreases in thermal tolerance using two subspecies of killifish (''Fundulus heteroclitus'') that differ in thermal niche. We assessed whole-organism metabolic rate, mitochondrial amount and mitochondrial function in killifish acclimated to several temperatures. Mitochondrial enzyme activities and mRNA levels were greater in fish from the northern subspecies, particularly in cold-acclimated fish, suggesting that the putatively cold-adapted northern subspecies has a greater capacity for increases in mitochondrial amount in response to cold acclimation. When tested at the fish's acclimation temperature, maximum ADP-stimulated (State III) rates of mitochondrial oxygen consumption ''in vitro'' were greater in cold-acclimated northern fish than in southern fish but did not differ between subspecies at higher acclimation temperatures. Whole-organism metabolic rate was greater in fish of the northern subspecies at all acclimation temperatures. Cold acclimation also changed the response of mitochondrial respiration to acute temperature challenge. Mitochondrial oxygen consumption was greater in cold-acclimated northern fish than in southern fish at low test temperatures, but the opposite was true at high test temperatures. These differences were reflected in whole-organism oxygen consumption. Our data indicate that the plasticity of mitochondrial function and amount differs between killifish subspecies, with the less high-temperature tolerant, and putatively cold adapted, northern subspecies having greater ability to increase mitochondrial capacity in the cold. However, there were few differences in mitochondrial properties between subspecies at warm acclimation temperatures, despite differences in both whole-organism oxygen consumption and thermal tolerance at these temperatures.d thermal tolerance at these temperatures.)
Cooper 2000 Sunderland (MA): Sinauer Associates + (As in the first edition, The Cell is focus … As in the first edition, The Cell is focused on the molecular biology of cells as a unifying theme, with specialized topics discussed throughout the book as examples of more general principles. Aspects of developmental biology, the immune system, the nervous system, and plant biology are thus discussed in their broader biological context in chapters covering areas such as genome structure, gene expression, DNA rearrangements, the plasma membrane, cell signaling, and the cell cycle. Relationships between cell biology and medicine are similarly discussed throughout the text, as well as being highlighted in the Molecular Medicine essays that are included as a special feature in each chapter. These discussions illustrate the striking impact of molecular and cellular biology on human health, and are intended to stimulate as well as inform those students interested in medicine.orm those students interested in medicine.)
Bullon 2016 Periodontol 2000 + (As many diseases have been shown to have s … As many diseases have been shown to have several or indirect causes (i.e. are multifactorial) the question is what is the relative importance of each factor in a given disease? Also, what happens when some diseases, although apparently disparate, share causative factors and/or tissue pathologies? Host inflammation response mechanisms are largely shared by the body's different tissues and systems and only recently has special attention been paid to the possible linkages among chronic periodontitis and other chronic systemic diseases. The aim of this review was to consider and discuss the mounting evidence that the basis for the inter-relationships between chronic periodontitis and atheromatous disease and diabetes lie at a fundamental intracellular level, namely oxidative stress and mitochondrial dysfunction, as a meeting background among such chronic diseases and periodontitis.© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd. Sons A/S. Published by John Wiley & Sons Ltd.)
Huerta-Sanchez 2014 Nature + (As modern humans migrated out of Africa, t … As modern humans migrated out of Africa, they encountered many new environmental conditions, including greater temperature extremes, different pathogens and higher altitudes. These diverse environments are likely to have acted as agents of natural selection and to have led to local adaptations. One of the most celebrated examples in humans is the adaptation of Tibetans to the hypoxic environment of the high-altitude Tibetan plateau1, 2, 3. A hypoxia pathway gene, EPAS1, was previously identified as having the most extreme signature of positive selection in Tibetans4, 5, 6, 7, 8, 9, 10, and was shown to be associated with differences in haemoglobin concentration at high altitude. Re-sequencing the region around EPAS1 in 40 Tibetan and 40 Han individuals, we find that this gene has a highly unusual haplotype structure that can only be convincingly explained by introgression of DNA from Denisovan or Denisovan-related individuals into humans. Scanning a larger set of worldwide populations, we find that the selected haplotype is only found in Denisovans and in Tibetans, and at very low frequency among Han Chinese. Furthermore, the length of the haplotype, and the fact that it is not found in any other populations, makes it unlikely that the haplotype sharing between Tibetans and Denisovans was caused by incomplete ancestral lineage sorting rather than introgression. Our findings illustrate that admixture with other hominin species has provided genetic variation that helped humans to adapt to new environments.elped humans to adapt to new environments.)
Zhao 2019 Pharmacol Res + (As one classic anticancer drug, clinical a … As one classic anticancer drug, clinical application of Doxorubicin (Dox) is limited due to its side effects. In our previous work, we have investigated the drug targets to treat Dox-induced cardiotoxicity, hepatotoxicity and nephrotoxicity. In this paper, the mechanisms and new drug-target associated with Dox-induced hepatotoxicity were explored. The results showed that Dox markedly inhibited cell viability and cellular respiration, induced cell morphologic change and increased ROS level. Moreover, Dox increased ALT and AST levels, caused pathological damage, increased MDA level and decreased SOD level in mice. Mechanism investigation showed that Dox markedly up-regulated the expression level of miR-128-3p, down-regulated Sirt1 expression level and affected the protein levels of Nrf2, Keap1, Sirt3, NQO1 and HO-1 to cause oxidative stress in liver. Furthermore, double-luciferase reporter assay, and co-transfection test showed that miR-128-3p directly targeted Sirt1. In addition, miR-128-3p mimics in AML-12 cells enhanced Dox-induced oxidative damage via inhibiting cellular respiration, increasing ROS level and mitochondrial superoxide formation. The protein levels of Sirt1, Nrf2, Sirt3, NQO1 and HO-1 in miR-128-3p mimic + Dox group were decreased compared with Dox group. Transfection of miR-128-3p inhibitor weakened Dox-induced oxidative damage via increasing cellular respiration, suppressing cellular ROS level and mitochondrial superoxide formation. The protein levels of Sirt1, Nrf2, Sirt3, NQO1 and HO-1 in miR-128-3p inhibitor + Dox group were increased compared with Dox group. In mice, Dox-induced liver damage was deteriorated by miR-128-3p agomir via increasing the levels of ALT, AST, MDA, and down-regulating the protein levels of Sirt1, Nrf2, Sirt3, NQO1 and HO-1. While, miR-128-3p antagomir alleviated liver injury via decreasing the levels of ALT, AST, MDA, and up-regulating the protein levels of Sirt1, Nrf2, Sirt3, NQO1 and HO-1. Our data showed that miRNA-128-3p aggravated Dox-induced liver injury by promoting oxidative stress via targeting Sirt1, which should be considered as one new drug target to treat Dox-induced liver injury.Copyright © 2019 Elsevier Ltd. All rights reserved. 2019 Elsevier Ltd. All rights reserved.)
Shirihai 2014 Abstract MiP2014 + (As our relationship with mitochondria evol … As our relationship with mitochondria evolves, we remain fascinated by the impact of this organelle in two seemingly unrelated conditions: aging and metabolic diseases. While aging involves insufficiency of mitochondrial quality control and turnover mechanisms (such as autophagy), type II diabetes and obesity are influenced by the ability of the organism to deal with excess nutrient environment. The observation that both conditions are impacted by the duration of exposure to excess nutrient environment raises the question: Are the tasks of handling nutrients in excess and maintaining quality control ever in conflict? Mitochondria go through continuous cycles of selective fusion and fission, referred to as the “mitochondrial life cycle”, to maintain the quality of their function [3-5]. Changes in mitochondrial architecture can represent an adaptation of mitochondria to respire according to the bioenergetic needs of the cell [2]. Conditions requiring high mitochondrial ATP synthesis capacity and/or efficiency, such as limited nutrient availability, are associated with mitochondrial elongation [1]; reviewed in [2], while conditions of excess energy supply and relatively low ATP demand, such as beta-cells exposed to excess nutrients, induce mitochondrial fragmentation [6]. This raises the possibility that mitochondrial fragmentation supports uncoupled respiration and thus increases energy expenditure by promoting nutrient oxidation towards heat production, rather than towards mitochondrial ATP synthesis. To test this hypothesis, we explored a system where a robust shift from coupled to uncoupled respiration and increased energy expenditure can occur. The brown adipocyte offers a unique system where transition to uncoupling can occur within minutes and in a physiological rather than pathological context. Therefore, it represents an attractive model for studying the regulation of energy expenditure induced by hormones. Our results indicate that norepinephrine induces changes to mitochondrial architecture that serve as an amplification pathway for uncoupling in brown adipocytes. Remarkably, we now have evidence that similar changes, though at a longer time scale, occur in the beta cells under excess nutrient environment. In the beta cell, nutrient–induced fragmentation is associated with increased uncoupling and the enhanced consumption of excess nutrients, thereby serving as an adaptive mechanism. Placement of bioenergetic adaptation and quality control as competing tasks of mitochondrial dynamics might provide a new mechanism, linking excess nutrient environment to progressive mitochondrial dysfunction, common to age-related diseases.sfunction, common to age-related diseases.)
Guan 1999 J Biotechnol + (As part of an overall aim to base the feed … As part of an overall aim to base the feeding of substrates to cultured animal cells on their actual metabolic needs,we have developed a stoichiometric approach centred on the macronutrients in the medium. Heat flux records theoverall metabolic activity and therefore was the sensitive indicator of changing metabolic requirement. Analyses weremade of the experimental measurements on two engineered cell lines in batch culture, the 2C11-12 macrophagehybridoma cell capable of the respiratory burst and the CHO320 constitutively producing human interferon-g. Thecrux was to construct simplified stoichiometric equations for the growth reactions to represent metabolic activity asit changed with time. Beforehand, it was essential to select the appropriate components for the equations. The choicewas then justified by constructing enthalpy balances in which the ratio of heat flux to enthalpy flux must be close tounity for validation. By combining the stoichiometric approach with heat flow measurements, it was shown boththeoretically and experimentally that the set of stoichiometric coefficients constituting a validated growth equation hasa one-to-one corresponding relationship to the metabolic activity of the average cell population. Thus, a strategy wasestablished for feeding the cells at any one time with the correct ratio of the major substrates, glucose and glutamine,in response to metabolic requirements that change with time.abolic requirements that change with time.)
DeBalsi 2017 Ageing Res Rev + (As regulators of bioenergetics in the cell … As regulators of bioenergetics in the cell and the primary source of endogenous reactive oxygen species (ROS), dysfunctional mitochondria have been implicated for decades in the process of aging and age-related diseases. Mitochondrial DNA (mtDNA) is replicated and repaired by nuclear-encoded mtDNA polymerase γ (Pol γ) and several other associated proteins, which compose the mtDNA replication machinery. Here, we review evidence that errors caused by this replication machinery and failure to repair these mtDNA errors results in mtDNA mutations. Clonal expansion of mtDNA mutations results in mitochondrial dysfunction, such as decreased electron transport chain (ETC) enzyme activity and impaired cellular respiration. We address the literature that mitochondrial dysfunction, in conjunction with altered mitochondrial dynamics, is a major driving force behind aging and age-related diseases. Additionally, interventions to improve mitochondrial function and attenuate the symptoms of aging are examined.enuate the symptoms of aging are examined.)
Dickinson 2013 Cell Death Differ + (As stem cells undergo differentiation, mit … As stem cells undergo differentiation, mitochondrial DNA (mtDNA) copy number is strictly regulated in order that specialized cells can generate appropriate levels of adenosine triphosphate (ATP) through oxidative phosphorylation (OXPHOS) to undertake their specific functions. It is not understood whether tumor-initiating cells regulate their mtDNA in a similar manner or whether mtDNA is essential for tumorigenesis. We show that human neural stem cells (hNSCs) increased their mtDNA content during differentiation in a process that was mediated by a synergistic relationship between the nuclear and mitochondrial genomes and results in increased respiratory capacity. Differentiating multipotent glioblastoma cells failed to match the expansion in mtDNA copy number, patterns of gene expression and increased respiratory capacity observed in hNSCs. Partial depletion of glioblastoma cell mtDNA rescued mtDNA replication events and enhanced cell differentiation. However, prolonged depletion resulted in impaired mtDNA replication, reduced proliferation and induced the expression of early developmental and pro-survival markers including POU class 5 homeobox 1 (OCT4) and sonic hedgehog (SHH). The transfer of glioblastoma cells depleted to varying degrees of their mtDNA content into immunocompromised mice resulted in tumors requiring significantly longer to form compared with non-depleted cells. The number of tumors formed and the time to tumor formation was relative to the degree of mtDNA depletion. The tumors derived from mtDNA depleted glioblastoma cells recovered their mtDNA copy number as part of the tumor formation process. These outcomes demonstrate the importance of mtDNA to the initiation and maintenance of tumorigenesis in glioblastoma multiforme. tumorigenesis in glioblastoma multiforme.)
Rodgers 2021 Elife + (As the final outputs of the Reproducibility Project: Cancer Biology are published, it is clear that preclinical research in cancer biology is not as reproducible as it should be.)
Rai 2022 G3 (Bethesda) + (As the fruit fly, Drosophila melanogaster, … As the fruit fly, Drosophila melanogaster, progresses from one life stage to the next, many of the enzymes that compose intermediary metabolism undergo substantial changes in both expression and activity. These predictable shifts in metabolic flux allow the fly meet stage-specific requirements for energy production and biosynthesis. In this regard, the enzyme glycerol-3-phosphate dehydrogenase 1 (GPDH1) has been the focus of biochemical genetics studies for several decades and, as a result, is one of the most well-characterized Drosophila enzymes. Among the findings of these earlier studies is that GPDH1 acts throughout the fly lifecycle to promote mitochondrial energy production and triglyceride accumulation while also serving a key role in maintaining redox balance. Here, we expand upon the known roles of GPDH1 during fly development by examining how depletion of both the maternal and zygotic pools of this enzyme influences development, metabolism, and viability. Our findings not only confirm previous observations that Gpdh1 mutants exhibit defects in larval development, lifespan, and fat storage but also reveal that GPDH1 serves essential roles in oogenesis and embryogenesis. Moreover, metabolomics analysis reveals that a Gpdh1 mutant stock maintained in a homozygous state exhibits larval metabolic defects that significantly differ from those observed in the F1 mutant generation. Overall, our findings highlight unappreciated roles for GPDH1 in early development and uncover previously undescribed metabolic adaptations that could allow flies to survive the loss of this key enzyme.es to survive the loss of this key enzyme.)
MitoEAGLE Task Group States and rates + (As the knowledge base and importance of mi … As the knowledge base and importance of mitochondrial physiology to human health expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow guidelines of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols to the nomenclature of classical bioenergetics. We endeavour to provide a balanced view on mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of databases of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery.ucation, and ultimately further discovery.)
Radogna 2021 Methods Mol Biol + (As the powerhouse of the cell, mitochondri … As the powerhouse of the cell, mitochondria, plays a crucial role in many aspects of life, whereby mitochondrial dysfunctions are associated with pathogenesis of many diseases, like neurodegenerative diseases, obesity, cancer, and metabolic as well as cardiovascular disorders. Mitochondria analysis frequently starts with isolation and enrichment procedures, which have become increasingly important in biomedical research. Unfortunately, isolation procedures can easily cause changes in the structural integrity of mitochondria during in vitro handling having impact on their function. This carries the risk that conclusions about isolated mitochondria may be drawn on the basis of experimental artifacts. Here we critically review a commonly used isolation procedure for mitochondria utilizing differential (gradient) centrifugation and depict major challenges to achieve "functional" mitochondria as basis for comprehensive physiological studies.s for comprehensive physiological studies.)
Lehr 2021 Methods Mol Biol + (As the powerhouse of the cell, mitochondri … As the powerhouse of the cell, mitochondria, plays a crucial role in many aspects of life, whereby mitochondrial dysfunctions are associated with pathogenesis of many diseases, like neurodegenerative diseases, obesity, cancer, and metabolic as well as cardiovascular disorders. Mitochondria analysis frequently starts with isolation and enrichment procedures, which have become increasingly important in biomedical research. Unfortunately, isolation procedures can easily cause changes in the structural integrity of mitochondria during ''in vitro'' handling having impact on their function. This carries the risk that conclusions about isolated mitochondria may be drawn on the basis of experimental artifacts. Here we critically review a commonly used isolation procedure for mitochondria utilizing differential (gradient) centrifugation and depict major challenges to achieve "functional" mitochondria as basis for comprehensive physiological studies.s for comprehensive physiological studies.)
De Jager 2017 Adv Exp Med Biol + (As ultraviolet (UV) radiation is naturally … As ultraviolet (UV) radiation is naturally and ubiquitously emitted by the sun, almost everyone is exposed to it on a daily basis, and it is necessary for normal physiological function. Human exposure to solar UV radiation thus has important health implications. The generation of reactive oxygen species (ROS) by UV radiation is one of the mechanisms through which UV light can manifest its possible detrimental effects on health. When an imbalance develops due to ROS generation exceeding the body's antioxidant defence mechanisms, oxidative stress can develop. Oxidative stress can lead to cellular damage (e.g. lipid peroxidation and DNA fragmentation), apoptosis and cell death. Broadly UV can induce ROS by affecting the cellular components directly or by means of photosensitization mechanisms. More specifically UV light can induce ROS by affecting the enzyme catalase and up-regulating nitric oxide synthase (NOS) synthesis. It may also cause a decrease in protein kinase C (PKC) expression leading to increased ROS production. UVR is capable of modifying DNA and other chromophores resulting in elevated ROS levels. The effects of raised ROS levels can vary based on the intracellular oxidant status of the cell. It is therefore important to protect yourself against the potentially harmful effects of UV light as it can lead to pathological UV-induced ROS production.to pathological UV-induced ROS production.)
Levett 2012 FASEB J + (Ascent to high altitude is associated with … Ascent to high altitude is associated with a fall in the partial pressure of inspired oxygen (hypobaric hypoxia). For oxidative tissues such as skeletal muscle, resultant cellular hypoxia necessitates acclimatization to optimize energy metabolism and restrict oxidative stress, with changes in gene and protein expression that alter mitochondrial function. It is known that lowlanders returning from high altitude have decreased muscle mitochondrial densities, yet the underlying transcriptional mechanisms and time course are poorly understood. To explore these, we measured gene and protein expression plus ultrastructure in muscle biopsies of lowlanders at sea level and following exposure to hypobaric hypoxia. Subacute exposure (19 d after initiating ascent to Everest base camp, 5300 m) was not associated with mitochondrial loss. After 66 d at altitude and ascent beyond 6400 m, mitochondrial densities fell by 21%, with loss of 73% of subsarcolemmal mitochondria. Correspondingly, levels of the transcriptional coactivator PGC-1α fell by 35%, suggesting down-regulation of mitochondrial biogenesis. Sustained hypoxia also decreased expression of electron transport chain complexes I and IV and UCP3 levels. We suggest that during subacute hypoxia, mitochondria might be protected from oxidative stress. However, following sustained exposure, mitochondrial biogenesis is deactivated and uncoupling down-regulated, perhaps to improve the efficiency of ATP production. improve the efficiency of ATP production.)
Mui 2018 Am J Mens Health + (Asian Americans develop health complicatio … Asian Americans develop health complications at lower BMIs than other racial/ethnic groups. Given increasing overweight and obesity rates nationwide, growing numbers of Asian American men, and limited research on overweight and obesity in this population, understanding overweight and obesity differences across Asian subgroups of men is crucial to advancing health equity. This study examined overweight and obesity prevalence both among ethnic subgroups of Asian American men and compared to non-Hispanic White (NHW) men. Prevalence ratios were derived from 2002 to 2015 National Health Interview Survey data to determine associations between race/ethnicity and (a) overweight, and (b) obesity, across (''N'' = 221,376) racial/ethnic groups of men (Chinese; Filipino; Asian Indian; Other Asian; NHW). Overweight and obesity for all Asian subgroups were defined using Asian-specific BMI cut points. Adjusted overweight prevalence was higher across all Asian subgroups compared to NHW men, except Filipinos. No significant pairwise relationships were observed for overweight prevalence among Asian subgroups. Filipinos had higher adjusted obesity prevalence compared to NHW men. Comparing among Asian American men, Asian Indians and Other Asians had higher adjusted obesity prevalence relative to Chinese. Filipinos had higher adjusted obesity prevalence compared to all other Asian subgroups (Chinese; Asian Indian; Other Asian). The current findings highlight the need for use of (a) WHO-recommended Asian-specific BMI cut points and (b) data disaggregated by Asian American subgroup, to provide more accurate depictions of overweight and obesity rates and associated health risks. Accounting for subgroup differences is necessary to ensure Asian American men receive equitable, appropriate care.n men receive equitable, appropriate care.)
Misra 2009 J Assoc Physicians India + (Asian Indians exhibit unique features of o … Asian Indians exhibit unique features of obesity; excess body fat, abdominal adiposity, increased subcutaneous and intra-abdominal fat, and deposition of fat in ectopic sites (liver, muscle, etc.). Obesity is a major driver for the widely prevalent metabolic syndrome and type 2 diabetes mellitus (T2DM) in Asian Indians in India and those residing in other countries. Based on percentage body fat and morbidity data, limits of normal BMI are narrower and lower in Asian Indians than in white Caucasians. In this consensus statement, we present revised guidelines for diagnosis of obesity, abdominal obesity, the metabolic syndrome, physical activity, and drug therapy and bariatric surgery for obesity in Asian Indians after consultations with experts from various regions of India belonging to the following medical disciplines; internal medicine, metabolic diseases, endocrinology, nutrition, cardiology, exercise physiology, sports medicine and bariatric surgery, and representing reputed medical institutions, hospitals, government funded research institutions, and policy making bodies. It is estimated that by application of these guidelines, additional 10-15 % of Indian population would be labeled as overweight/obese and would require appropriate management. Application of these guidelines on countrywide basis is also likely to have a deceleration effect on the escalating problem of T2DM and cardiovascular disease. These guidelines could be revised in future as appropriate, after another large and countrywide consensus process. Till that time, these should be used by clinicians, researchers and policymakers dealing with obesity and related diseases.dealing with obesity and related diseases.)
Farrugia 2019 Sci Rep + (Aspirin is a widely used anti-inflammatory … Aspirin is a widely used anti-inflammatory and antithrombotic drug also known in recent years for its promising chemopreventive antineoplastic properties, thought to be mediated in part by its ability to induce apoptotic cell death. However, the full range of mechanisms underlying aspirin's cancer-preventive properties is still elusive. In this study, we observed that aspirin impaired both the synthesis and transport of acetyl-coenzyme A (acetyl-CoA) into the mitochondria of manganese superoxide dismutase (MnSOD)-deficient Saccharomyces cerevisiae EG110 yeast cells, but not of the wild-type cells, grown aerobically in ethanol medium. This occurred at both the gene level, as indicated by microarray and qRT-PCR analyses, and at the protein level as indicated by enzyme assays. These results show that in redox-compromised MnSOD-deficient yeast cells, but not in wild-type cells, aspirin starves the mitochondria of acetyl-CoA and likely causes energy failure linked to mitochondrial damage, resulting in cell death. Since acetyl-CoA is one of the least-studied targets of aspirin in terms of the latter's propensity to prevent cancer, this work may provide further mechanistic insight into aspirin's chemopreventive behavior with respect to early stage cancer cells, which tend to have downregulated MnSOD and are also redox-compromised.ated MnSOD and are also redox-compromised.)
Lichtenberger 2019 Cancer Res + (Aspirin, when administered at low doses, h … Aspirin, when administered at low doses, has emerged as a powerful anticancer drug due to both chemopreventive activity against many forms of cancer and its ability to block metastases when administered postdiagnosis. Platelets, which are often elevated in circulation during the latter stages of cancer, are known to promote epithelial-mesenchymal transition, cancer cell growth, survival in circulation, and angiogenesis at sites of metastases. Low-dose aspirin has been demonstrated to block this procarcinogenic action of platelets. In this article, we present evidence that aspirin's unique ability to irreversibly inhibit platelet cyclooxygenase-1 is a key mechanism by which aspirin exerts anticancer activity. which aspirin exerts anticancer activity.)
Chojnacka 2022 Mol Biol Cell + (Assembly of the dimeric complex III (CIII& … Assembly of the dimeric complex III (CIII2) in the mitochondrial inner membrane is an intricate process in which several accessory proteins are involved as assembly factors. Despite numerous studies, this process has yet to be fully understood. Here we report the identification of human OCIAD2 (ovarian carcinoma immunoreactive antigen-like protein 2) as an assembly factor for CIII2. OCIAD2 was found to be deregulated in several carcinomas and also in some neurogenerative disorders; however, its nonpathological role had not been elucidated. We have shown that OCIAD2 localizes to mitochondria and interacts with electron transport chain (ETC) proteins. Complete loss of OCIAD2 using gene editing in HEK293 cells resulted in abnormal mitochondrial morphology, a substantial decrease of both CIII2 and supercomplex III2+IV, and a reduction in CIII enzymatic activity. Identification of OCIAD2 as a protein required for assembly of functional CIII2 provides a new insight into the biogenesis and architecture of the ETC. Elucidating the mechanism of OCIAD2 action is important both for the understanding of cellular metabolism and for an understanding of its role in malignant transformation.understanding of cellular metabolism and for an understanding of its role in malignant transformation.)
Brand 2011 Biochem J + (Assessing mitochondrial dysfunction requir … Assessing mitochondrial dysfunction requires definition of the dysfunction to be investigated. Usually, it is the ability of the mitochondria to make ATP appropriately in response to energy demands. Where other functions are of interest, tailored solutions are required. Dysfunction can be assessed in isolated mitochondria, in cells or in vivo, with different balances between precise experimental control and physiological relevance. There are many methods to measure mitochondrial function and dysfunction in these systems. Generally, measurements of fluxes give more information about the ability to make ATP than do measurements of intermediates and potentials. For isolated mitochondria, the best assay is mitochondrial respiratory control: the increase in respiration rate in response to ADP. For intact cells, the best assay is the equivalent measurement of cell respiratory control, which reports the rate of ATP production, the proton leak rate, the coupling efficiency, the maximum respiratory rate, the respiratory control ratio and the spare respiratory capacity. Measurements of membrane potential provide useful additional information. Measurement of both respiration and potential during appropriate titrations enables the identification of the primary sites of effectors and the distribution of control, allowing deeper quantitative analyses. Many other measurements in current use can be more problematic, as discussed in the present review.matic, as discussed in the present review.)
Niehusmann 2011 Epilepsy Behav + (Assessment for epilepsy surgery may requir … Assessment for epilepsy surgery may require invasive measures such as implantation of intracranial electrodes or the Wada test. These investigations are commonly well tolerated. However, complications, including visual disturbances of various etiologies, have been reported. Here we describe two patients with pharmacoresistant temporal lobe epilepsy (TLE) who displayed loss of vision in the context of presurgical assessment and in whom mutations associated with Leber's hereditary optic neuropathy (LHON) were detected. Genetic analysis revealed in one patient the frequent mitochondrial G11778A LHON mutation in ND4. In the second patient, the mitochondrial C4640A mutation in ND2 was detected. This rare LHON mutation enhanced the sensitivity of the patient's muscle and brain tissue to amobarbital, a known blocker of the mitochondrial respiratory chain. Mitochondrial dysfunction has been reported in epilepsy. Thus, the presence of LHON mutations can be a rare cause of visual disturbances in patients with epilepsy and may have predisposed to development of epilepsy.ve predisposed to development of epilepsy.)
Cikankova 2019 Naunyn Schmiedebergs Arch Pharmacol + (Assessment of drug-induced mitochondrial d … Assessment of drug-induced mitochondrial dysfunctions is important in drug development as well as in the understanding of molecular mechanism of therapeutic or adverse effects of drugs. The aim of this study was to investigate the effects of three typical antipsychotics (APs) and seven atypical APs on mitochondrial bioenergetics. The effects of selected APs on citrate synthase, electron transport chain complexes (ETC), and mitochondrial complex I- or complex II-linked respiratory rate were measured using mitochondria isolated from pig brain. Complex I activity was decreased by chlorpromazine, haloperidol, zotepine, aripiprazole, quetiapine, risperidone, and clozapine. Complex II + III was significantly inhibited by zotepine, aripiprazole, quetiapine, and risperidone. Complex IV was inhibited by zotepine, chlorpromazine, and levomepromazine. Mitochondrial respiratory rate was significantly inhibited by all tested APs, except for olanzapine. Typical APs did not exhibit greater efficacy in altering mitochondrial function compared to atypical APs except for complex I inhibition by chlorpromazine and haloperidol. A comparison of the effects of APs on individual respiratory complexes and on the overall mitochondrial respiration has shown that mitochondrial functions may not fully reflect the disruption of complexes of ETC, which indicates AP-induced modulation of other mitochondrial proteins. Due to the complicated processes associated with mitochondrial activity, it is necessary to measure not only the effect of the drug on individual mitochondrial enzymes but also the respiration rate of the mitochondria or a similar complex process. The experimental approach used in the study can be applied to mitochondrial toxicity testing of newly developed drugs.toxicity testing of newly developed drugs.)
Perry 2011 Biochem J + (Assessment of mitochondrial ADP-stimulated … Assessment of mitochondrial ADP-stimulated respiratory kinetics in permeabilized fibre (pfi) bundles is increasingly used in clinical diagnostic and basic research settings. However, estimates of the ''K''m for ADP vary considerably (~20-300 μM) and tend to overestimate respiration at rest. Noting that pfi bundles spontaneously contract during respiration experiments, we systematically determined the impact of contraction, temperature and oxygenation on ADP-stimulated respiratory kinetics. BLEB ('''blebbistatin'''), a myosin II ATPase inhibitor, blocked contraction under all conditions and yielded high ''K''m values for ADP of >~250 and ~80 μM in red and white rat pfi bundles respectively. In the absence of BLEB, pfi bundles contracted and the ''K''m for ADP decreased ~2-10-fold in a temperature-dependent manner. pfi bundles were sensitive to hyperoxia (increased ''K''m) in the absence of BLEB (contracted) at 30 °C but not 37 °C. In pfi bundles from humans, contraction elicited high sensitivity to ADP (''K''m<100 μM), whereas blocking contraction (+BLEB) and including a phosphocreatine/creatine ratio of 2:1 to mimic the resting energetic state yielded a ''K''m for ADP of ~1560 μM, consistent with estimates of ''in vivo'' resting respiratory rates of <1% maximum. These results demonstrate that the sensitivity of muscle to ADP varies over a wide range in relation to contractile state and cellular energy charge, providing evidence that enzymatic coupling of energy transfer within skeletal muscle becomes more efficient in the working state.ing evidence that enzymatic coupling of energy transfer within skeletal muscle becomes more efficient in the working state.)
Meszaros 2018 Mt Med Hinxton + (Assessment of mitochondrial respiration at … Assessment of mitochondrial respiration at higher-than-physiological oxygen (O2) concentrations has become a standard in biomedical research. In contrast, the impact of mitochondrial O2 kinetics on (patho)physiology is largely neglected. To facilitate further studies, we developed the automatized software module ''O2'''kinetics'''''. Using this advanced tool, we re-evaluated the O2 dependence of mitochondrial respiration in various respiratory states, experimental conditions, and in the presence of cytochrome c oxidase (CIV) inhibitors.Mitochondria isolated from mouse brain, heart and liver were incubated at 37 °C in Oroboros O2k High-Resolution FluoRespirometers. Using substrate-uncoupler-inhibitor titration (SUIT) protocols with various fuel substrate combinations in OXPHOS-, LEAK- and ET-states, we investigated the effect of pathway and coupling control on mitochondrial ''p50'' (O2 partial pressure at half-maximum O2 flux, ''JO2''). Kinetic data was obtained during aerobic-anaerobic transitions with high time-resolution at data sampling intervals of 0.2 s. ''p50'' values were calculated using the ''O2'''kinetics''''' software for automatic correction and calibration steps. Depending on experimental temperature and respiratory state, ''p50'' ranged from 0.006 to 0.07 kPa for NADH-linked LEAK respiration with glutamate&malate, N(GM)''L'', and NADH-&succinate-linked OXPHOS capacity including GM and pyruvate, NS(GMP)''P'', in agreement with and extending data published previously. In heart and liver mitochondria, the ''p50'' was higher in OXPHOS- compared to LEAK-states, increasing proportionally with CIV turnover. Upon inhibition of CIV, ''p50'' increased several-fold up to 0.15 kPa, NS(GM)''P'', which was not reflected in ''JO2'' at kinetic O2 saturation. In diagnostic experiments, increasing ''p50'' values correlated well with decreasing CIV activity, as measured upon addition of ascorbate and TMPD.Mitochondrial ''p50'' measurement is a quick, highly accurate and sensitive way for early detection of reduced CIV excess capacity, as affinity of mitochondria for O2 decreases already at a slight CIV inhibition. Determination of mitochondrial O2 dependence has implications in a wide range of biomedical research topics, particularly in studies with CIV mutations (e.g. Leigh syndrome), or with small inhibitory molecules (nitric oxide). ''O2'''kinetics''''' provides a fast and simple method for the detection of CIV impairment and extends standard OXPHOS analysis to the intracellular O2 regime ''in vivo'', reflecting low physiological O2 concentrations or tissue hypoxia.tory molecules (nitric oxide). ''O2'''kinetics''''' provides a fast and simple method for the detection of CIV impairment and extends standard OXPHOS analysis to the intracellular O2 regime ''in vivo'', reflecting low physiological O2 concentrations or tissue hypoxia.)
Daradics 2022 PLoS One + (Associating Liver Partition and Portal vei … Associating Liver Partition and Portal vein ligation for Staged hepatectomy (ALPPS) is a modification of two-stage hepatectomy profitable for patients with inoperable hepatic tumors by standard techniques. Unfortunately, initially poor postoperative outcome was associated with ALPPS, in which mitochondrial dysfunction played an essential role. Inhibition of cyclophilins has been already proposed to be efficient as a mitochondrial therapy in liver diseases. To investigate the effect of Cyclophilin D (CypD) depletion on mitochondrial function, biogenesis and liver regeneration following ALPPS a CypD knockout (KO) mice model was created.Male wild type (WT) (n = 30) and CypD KO (n = 30) mice underwent ALPPS procedure. Animals were terminated pre-operatively and 24, 48, 72 or 168 h after the operation. Mitochondrial functional studies and proteomic analysis were performed. Regeneration rate and mitotic activity were assessed.The CypD KO group displayed improved mitochondrial function, as both ATP production (P < 0.001) and oxygen consumption (P < 0.05) were increased compared to the WT group. The level of mitochondrial biogenesis coordinator peroxisome proliferator-activated receptor γ co-activator 1-α (PGC1-α) was also elevated in the CypD KO group (P < 0.001), which resulted in the induction of the mitochondrial oxidative phosphorylation system. Liver growth increased in the CypD KO group compared to the WT group (P < 0.001).Our study demonstrates the beneficial effect of CypD depletion on the mitochondrial vulnerability following ALPPS. Based on our results we propose that CypD inhibition should be further investigated as a possible mitochondrial therapy following ALPPS.d as a possible mitochondrial therapy following ALPPS.)
Budai 2018 Br J Surg + (Associating liver partition and portal vei … Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a two-stage strategy to induce rapid regeneration of the remnant liver. The technique has been associated with high mortality and morbidity rates. This study aimed to evaluate mitochondrial function, biogenesis and morphology during ALPPS-induced liver regeneration.Male Wistar rats (n = 100) underwent portal vein ligation (PVL) or ALPPS. The animals were killed at 0 h (without operation), and 24, 48, 72 or 168 h after intervention. Regeneration rate and proliferation index were assessed. Mitochondrial oxygen consumption and adenosine 5'-triphosphate (ATP) production were measured. Mitochondrial biogenesis was evaluated by protein level measurements of peroxisome proliferator-activated receptor γ co-activator (PGC) 1-α, nuclear respiratory factor (NRF) 1 and 2, and mitochondrial transcription factor α. Mitochondrial morphology was evaluated by electron microscopy.Regeneration rate and Ki-67 index were significantly raised in the ALPPS group compared with the PVL group (regeneration rate at 168 h: mean(s.d.) 291·2(21·4) versus 245·1(13·8) per cent, P < 0·001; Ki-67 index at 24 h: 86·9(4·6) versus 66·2(4·9) per cent, P < 0·001). In the ALPPS group, mitochondrial function was impaired 48 h after the intervention compared with that in the PVL group (induced ATP production); (complex I: 361·9(72·3) versus 629·7(165·8) nmol per min per mg, P = 0·038; complex II: 517·5(48·8) versus 794·8(170·4) nmol per min per mg, P = 0·044). Markers of mitochondrial biogenesis were significantly lower 48 and 72 h after ALPPS compared with PVL (PGC1-α at 48 h: 0·61-fold decrease, P = 0·045; NRF1 at 48 h: 0·48-fold decrease, P = 0·028). Mitochondrial size decreased significantly after ALPPS (0·26(0·05) versus 0·40(0·07) μm2 ; P = 0·034).Impaired mitochondrial function and biogenesis, along with the rapid energy-demanding cell proliferation, may cause hepatocyte dysfunction after ALPPS. Surgical relevance Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a well known surgical strategy that combines liver partition and portal vein ligation. This method induces immense regeneration in the future liver remnant. The rapid volume increase is of benefit for resectability, but the mortality and morbidity rates of ALPPS are strikingly high. Moreover, lagging functional recovery of the remnant liver has been reported recently. In this translational study, ALPPS caused an overwhelming inflammatory response that interfered with the peroxisome proliferator-activated receptor γ co-activator 1-α-coordinated, stress-induced, mitochondrial biogenesis pathway. This resulted in the accumulation of immature and malfunctioning mitochondria in hepatocytes during the early phase of liver regeneration (bioenergetic destabilization). These findings might explain some of the high morbidity if confirmed in patients.© 2018 BJS Society Ltd Published by John Wiley & Sons Ltd.© 2018 BJS Society Ltd Published by John Wiley & Sons Ltd.)
Skulachev 2014 Abstract MiP2014 + (Assuming that mitochondria are sources of … Assuming that mitochondria are sources of reactive oxygen species (ROS), causing a number of pathologies, predicts that mitochondria-targeted antioxidants should decrease intracellular ROS and cure humans suffering from various ROS-linked diseases much stronger than non-targeted antioxidants or antioxidants targeted to compartments other than mitochondria. The first observation of this kind was done by Murphy’s group, where mitochondria-targeted CoQ derivative MitoQ was found to inhibit ROS-induced apoptosis of cell cultures at 5∙102 times lower concentration than non-targeted CoQ [1]. Later, Chernyak’s group in our laboratory showed an even larger difference between mitochondria-targeted plastoquinones (SkQ1 or SkQR1) and non-targeted N-acetyl cysteine (NAC) and trolox [2-4]. The stronger effect of SkQs, compared to MitoQ, was mainly due to a much larger window between anti- and prooxidant activities of these quinones. A 106 difference between doses of SkQ1 and NAC was shown in our group by Kopnin and coworkers, who studied an increase in lifespan of p53-/- mice who died due to lymphoma [5]. Such a great advantage of SkQ1 over NAC could be predicted if one takes into account that (1) the antioxidant effect of SkQ1 results in a prevention of the chain reaction of cardiolipin peroxidation, localized in the inner mitochondrial membrane; and (2) extracellular SkQ1, in contrast to NAC, electrophoretically accumulates by a factor of 10 in cytosol, 103 in the mitochondrial matrix and 104 in the membrane, because of a high octanol/water distribution coefficient. As a result, SkQ1 concentration in the inner mitochondrial membrane can be 108 (10∙103∙104) times higher than extramitochondrial [SkQ1] [6,7]. Large differences between acting concentrations of SkQ1 and those of vitamin E or NAC were revealed by Kolosova and coworkers when studying progeric OXYS rats (age-dependent development of cataract, retinopathy and an IGF-1 decrease were investigated) [5-8]. Rabinovich and his colleagues succeeded in an ''in vivo'' targeting of catalase to mitochondria [9-12]. In particular, an antiprogeric effect was observed in “mutator” mice defective in the proof-reading domain of mitochondrial DNA polymerase [12]. Such mice were shown to have an elevated content of mitochondrial H2O2 [13]. Targeting of catalase to nucleus or peroxisomes proved to be much less effective than to mitochondria [9]. The final aim of ROS studies is certainly the treatment of ROS-induced pathologies in humans. There is already a precedent when a mitochondria-targeted antioxidant - eye drops Visomitin containing 250 nM SkQ1, which is an efficient treatment of the previously incurable disease “dry eye syndrome” [14,15] - were officially recommended as a medicine and became available in pharmacies. Clinical trials of this drug showed that it is also beneficial in two other age-related diseases, i.e. cataract and glaucoma. Again, SkQ1 proved to be much more efficient than thymolol, a non-targeted antioxidant. beneficial in two other age-related diseases, i.e. cataract and glaucoma. Again, SkQ1 proved to be much more efficient than thymolol, a non-targeted antioxidant.)
Ederle 2019 J Clin Med + (Asthma is a chronic inflammatory lung synd … Asthma is a chronic inflammatory lung syndrome with an increasing prevalence and a rare but significant risk of death. Its pathophysiology is complex, and therefore we investigated at the systemic level a potential implication of oxidative stress and of peripheral blood mononuclear cells' (PBMC) mitochondrial function. Twenty severe asthmatic patients with severe exacerbation (GINA 4-5) and 20 healthy volunteers participated at the study. Mitochondrial respiratory chain complexes activities using different substrates and reactive oxygen species (ROS) production were determined in both groups by high-resolution respirometry and electronic paramagnetic resonance, respectively. Healthy PBMC were also incubated with a pool of plasma of severe asthmatics or healthy controls. Mitochondrial respiratory chain complexes activity (+52.45%, p = 0.015 for VADP) and ROS production (+34.3%, p = 0.02) were increased in asthmatic patients. Increased ROS did not originate mainly from mitochondria. Plasma of severe asthmatics significantly increased healthy PBMC mitochondrial dioxygen consumption (+56.8%, p = 0.031). In conclusion, such asthma endotype, characterized by increased PMBCs mitochondrial oxidative capacity and ROS production likely related to a plasma constituent, may reflect activation of the immune system. Further studies are needed to determine whether increased PBMC mitochondrial respiration might have protective effects, opening thus new therapeutic approaches.tive effects, opening thus new therapeutic approaches.)
Cabral-Costa 2022 MitoFit + (Astrocytes are a heterogenous population o … Astrocytes are a heterogenous population of macroglial cells spread throughout the central nervous system with diverse functions, expression signatures, and intricate morphologies. Their subcellular compartments contain a distinct range of mitochondria, with functional microdomains exhibiting widespread activities, such as controlling local metabolism and Ca2+ signaling. Ca2+ is an ion of utmost importance, both physiologically and pathologically, and participates in critical central nervous system processes, including synaptic plasticity, neuron-astrocyte integration, excitotoxicity, and mitochondrial physiology and metabolism. The mitochondrial Ca2+ handling system is formed by the mitochondrial Ca2+ uniporter complex (MCUc), which mediates Ca2+ influx, and the mitochondrial Na+/Ca2+ exchanger (NCLX), responsible for most mitochondrial Ca2+ efflux, as well as additional components, including the mitochondrial permeability transition pore (mtPTP). Over the last decades, mitochondrial Ca2+ handling has been shown to be key for brain homeostasis, acting centrally in physiopathological processes such as astrogliosis, astrocyte-neuron activity integration, energy metabolism control, and neurodegeneration. In this review we discuss the current state of knowledge of the mitochondrial Ca2+ handling system molecular composition, highlighting its impact on astrocytic homeostasis. state of knowledge of the mitochondrial Ca2+ handling system molecular composition, highlighting its impact on astrocytic homeostasis. )
Vandenberg 2021 Neurochem Int + (Astrocytes, glial cells within the brain, … Astrocytes, glial cells within the brain, work to protect neurons during high levels of activity by maintaining oxidative homeostasis via regulation of energy supply and antioxidant systems. In recent years, mitochondrial dysfunction has been highlighted as an underlying factor of pathology in many neurological disorders. In animal studies of Fragile X Syndrome (FXS), the leading genetic cause of autism, higher levels of reactive oxygen species, lipid peroxidation, and protein oxidation within the brain indicates that mitochondria function is also altered in FXS. Despite their integral contribution to redox homeostasis within the CNS, the role of astrocytes on the occurrence or progression of neurodevelopmental disorders in this way is rarely considered. This study specifically examines changes to astrocyte mitochondrial function and antioxidant expression that may occur in FXS. Using the Fmr1 knockout (KO) mouse model, mitochondrial respiration and reactive oxygen species (ROS) emission were analyzed in primary cortical astrocytes. While mitochondrial respiration was similar between genotypes, ROS emission was significantly elevated in Fmr1 KO astrocytes. Notably, NADPH-oxidase 2 expression in Fmr1 KO astrocytes was also enhanced but only changes in catalase antioxidant enzyme expression were noted. Characterization of astrocyte factors involved in redox imbalance is invaluable to uncovering potential sources of oxidative stress in neurodevelopmental disorders and more specifically, the intercellular mechanisms that contribute to dysfunction in FXS.sms that contribute to dysfunction in FXS.)
Kunz 1997 Anal Biochem + (At 488 nm argon-ion laser excitation human … At 488 nm argon-ion laser excitation human mononuclear cells emit flavoprotein-related autofluorescence signals. Approximately 60% of these are caused by the mitochondrial flavoproteins α-lipoamide dehydrogenase and electron transfer flavoprotein, having differences in their fluorescence emission spectra. At the emission wavelength of 530 nm the redox changes of α-lipoamide dehydrogenase fluorescence in human mononuclear cells can be monitored by flow cytometry. This allows the estimation of the steady-state reduction level of this flavoprotein being in redox equilibrium with the mitochondrial NAD-system. We applied this method to elucidate the possible impairment of mitochondrial function in subpopulations of mononuclear cells of patients harboring deletions of the mitochondrial DNA in skeletal muscle. In the monocyte fraction of three patients and in the lymphocyte fraction of one patient we observed in the presence of the mitochondrial substrate octanoate elevated steady-state reduction levels of α-lipoamide dehydrogenase. This is an indication for the presence of respiratory chain-inhibited mitochondria in mononuclear cell subpopulations of the described patients. These data were confirmed by conventional determinations of maximal oxygen consumption rates of digitonin-permeabilized cells. Therefore, the flow cytometric determination of flavoprotein-caused autofluorescence changes is a useful and sensitive method for the detection of an impairment of mitochondrial respiratory chain in subpopulations of heterogeneous cell suspensions.lations of heterogeneous cell suspensions.)
World Health Organization 2010 IPECP + (At a time when the world is facing a short … At a time when the world is facing a shortage of health workers, policy-makers are looking for innovative strategies that can help them develop policy and programmes to bolster the global health workforce. The ''Framework for Action on Interprofessional Education and Collaborative Practice'' highlights the current status of interprofessional collaboration around the world, identifies the mechanisms that shape successful collaborative teamwork and outlines a series of action items that policy-makers can apply within their local health system (Figure 1). The goal of the Framework is to provide strategies and ideas that will help health policy-makers implement the elements of interprofessional education and collaborative practice that will be most beneficial in their own jurisdiction.* The World Health Organization (WHO) and its partners recognize interprofessional collaboration in education and practice as an innovative strategy that will play an important role in mitigating the global health workforce crisis.* Interprofessional education occurs when students from two or more professions learn about, from and with each other to enable effective collaboration and improve health outcomes.* Interprofessional education is a necessary step in preparing a “collaborative practice-ready” health workforce that is better prepared to respond to local health needs.* A collaborative practice-ready health worker is someone who has learned how to work in an interprofessional team and is competent to do so.* Collaborative practice happens when multiple health workers from different professional backgrounds work together with patients, families, carers and communities to deliver the highest quality of care. It allows health workers to engage any individual whose skills can help achieve local health goals.* After almost 50 years of enquiry, the World Health Organization and its partners acknowledge that there is sufficient evidence to indicate that effective interprofessional education enables effective collaborative practice.* Collaborative practice strengthens health systems and improves health outcomes.* Integrated health and education policies can promote effective interprofessional education and collaborative practice.* A range of mechanisms shape effective interprofessional education and collaborative practice. These include: :- supportive management practices :- identifying and supporting champions :- the resolve to change the culture and attitudes of health workers:- a willingness to update, renew and revise existing curricula :- appropriate legislation that eliminates barriers to collaborative practice.* Mechanisms that shape interprofessional education and collaborative practice are not the same in all health systems. Health policy-makers should utilize the mechanisms that are most applicable and appropriate to their own local or regional context.* Health leaders who choose to contextualize, commit and champion interprofessional education and collaborative practice position their health system to facilitate achievement of the health-related Millennium Development Goals (MDGs).* The ''Framework for Action on Interprofessional Education and Collaborative Practice'' provides policy-makers with ideas on how to implement interprofessional education and collaborative practice within their current context. ractice within their current context. )
Sharaf 2017 Aquat Toxicol + (At excess levels, zinc (Zn) disrupts mitoc … At excess levels, zinc (Zn) disrupts mitochondrial functional integrity and induces oxidative stress in aquatic organisms. Although much is known about the modulation of Zn toxicity by calcium (Ca) in fish, their interactions at the mitochondrial level have scarcely been investigated. Here we assessed the individual and combined effects of Zn and Ca on the relationship between mitochondrial respiration, ROS and membrane potential (ΔΨmt) in rainbow trout liver mitochondria. We tested if cation uptake through the mitochondrial calcium uniporter (MCU) is a prerequisite for Zn- and/or Ca-induced alteration of mitochondrial function. Furthermore, using our recently developed real-time multi-parametric method, we investigated the changes in respiration, ΔΨmt, and reactive oxygen species (ROS, as hydrogen peroxide (H2O2)) release associated with Ca-induced mitochondrial depolarization imposed by transient and permanent openings of the mitochondrial permeability transition pore (mPTP). We found that independent of the MCU, Zn precipitated an immediate depolarization of the ΔΨmt that was associated with relatively slow enhancement of H2O2 release, inhibition of respiration and reversal of the positive correlation between ROS and ΔΨmt. In contrast, an equitoxic dose of Ca caused transient depolarization, and stimulation of both respiration and H2O2 release, effects that were completely abolished when the MCU was blocked. Contrary to our expectation that mitochondrial transition ROS Spike (mTRS) would be sensitive to both Zn and Ca, only Ca suppressed it. Moreover, Zn and Ca in combination immediately depolarized the ΔΨmt, and caused transient and sustained stimulation of respiration and H2O2 release, respectively. Lastly, we uncovered and characterized an mPTP-independent Ca-induced depolarization spike that was associated with exposure to moderately elevated levels of Ca. Importantly, we showed the stimulation of ROS release associated with highly elevated but not unrealistic Ca loads was not the cause but a result of mPTP opening in the high conductance mode.Copyright © 2017 Elsevier B.V. All rights reserved.Ca loads was not the cause but a result of mPTP opening in the high conductance mode. Copyright © 2017 Elsevier B.V. All rights reserved.)
McClelland 1998 Proc Natl Acad Sci U S A + (At high altitude (HA), carbohydrate (CHO) … At high altitude (HA), carbohydrate (CHO) is thought to be the preferred fuel because of its higher yield of ATP per mole of O2. We used indirect calorimetry and D-[6-3H]glucose infusions to determine total CHO and circulatory glucose utilization during exercise in HA-acclimated and sea level (SL) rats. We hypothesized that the percent contribution of CHO to total metabolism (VO2) is determined by exercise intensity relative to an aerobic maximum (% VO2max). HA rats run under hypoxia (FIO2 = 0.12) showed a decrease in VO2max compared with SL (67.55 +/- 1.26 vs. 89.30 +/- 1.23 ml kg-1 min-1). When exercised at 60% of their respective VO2max, both groups showed the same relative use of CHO (38 +/- 3% and 38 +/- 5% of VO2, at the beginning of exercise, in HA and SL, respectively). In both HA and SL, circulatory glucose accounted for approximately 20% of VO2, the balance was provided by muscle glycogen (approximately 18% of VO2). After 20 min at a higher intensity of 80% VO2max, 54 +/- 5% (HA) and 59 +/- 4% (SL) of VO2 was accounted for by CHO. We conclude the following: (i) the relative contributions of total CHO, circulatory glucose, and muscle glycogen do not increase after HA acclimation because the O2-saving advantage of CHO is outweighed by limited CHO stores; and (ii) relative exercise intensity is the major determinant of metabolic fuel selection at HA, as well as at SL.ic fuel selection at HA, as well as at SL.)
Murray 2015 Exp Physiol + (At high-altitude barometric pressure falls … At high-altitude barometric pressure falls, challenging oxygen delivery to the tissues. Thus, whilst hypoxia is not the only physiological stress encountered at high-altitude, low arterial PO2 is a sustained feature, even after allowing adequate time for acclimatisation. Cardiac and skeletal muscle energy metabolism is altered in subjects at, or returning from, high-altitude. In the heart, energetic reserve falls, as indicated by lower phosphocreatine-to-ATP ratios. The underlying mechanism is unknown but in the hypoxic rat heart fatty acid oxidation and respiratory capacity are decreased, whilst pyruvate oxidation is also lower after sustained hypoxic exposure. In skeletal muscle, there is not a consensus. With prolonged exposure to extreme high-altitude (> 5500 m) a loss of muscle mitochondrial density is seen, but this was not observed in a simulated ascent of Everest in hypobaric chambers. At more moderate high-altitude, decreased respiratory capacity may occur without changes in mitochondrial volume density, and fat oxidation may be downregulated, though this is not seen in all studies. The underlying mechanisms, including the possible role of hypoxia-signalling pathways, remain to be resolved, particularly in light of confounding factors in the high-altitude environment. In high-altitude adapted Tibetan natives, however, there is evidence of natural selection centred around the hypoxia-inducible factor (HIF) pathway, and metabolic features in this population (e.g. low cardiac PCr/PCr, increased cardiac glucose uptake, lower muscle mitochondrial densities), share similarities with those in acclimatised lowlanders, supporting a possible role for the HIF pathway in the metabolic response of cardiac and skeletal muscle energy metabolism to high-altitude. This article is protected by copyright. All rights reserved. protected by copyright. All rights reserved.)
Yu 2023 Biochim Biophys Acta Bioenerg + (At low inner mitochondrial membrane potent … At low inner mitochondrial membrane potential (ΔΨ) oxaloacetate (OAA) accumulates in the organelles concurrently with decreased complex II-energized respiration. This is consistent with ΔΨ-dependent OAA inhibition of succinate dehydrogenase. To assess the metabolic importance of this process, we tested the hypothesis that perturbing metabolic clearance of OAA in complex II-energized mitochondria would alter O2 flux and, further, that this would occur in both ΔΨ and tissue-dependent fashion. We carried out respiratory and metabolite studies in skeletal muscle and interscapular brown adipose tissue (IBAT) directed at the effect of OAA transamination to aspartate (catalyzed by the mitochondrial form of glutamic-oxaloacetic transaminase, Got2) on complex II-energized respiration. Addition of low amounts of glutamate to succinate-energized mitochondria at low ΔΨ increased complex II (succinate)-energized respiration in muscle but had little effect in IBAT mitochondria. The transaminase inhibitor, aminooxyacetic acid, increased OAA concentrations and impaired succinate-energized respiration in muscle but not IBAT mitochondria at low but not high ΔΨ. Immunoblotting revealed that Got2 expression was far greater in muscle than IBAT mitochondria. Because we incidentally observed metabolism of OAA to pyruvate in IBAT mitochondria, more so than in muscle mitochondria, we also examined the expression of mitochondrial oxaloacetate decarboxylase (ODX). ODX was detected only in IBAT mitochondria. In summary, at low but not high ΔΨ, mitochondrial transamination clears OAA preventing loss of complex II respiration: a process far more active in muscle than IBAT mitochondria. We also provide evidence that OAA decarboxylation clears OAA to pyruvate in IBAT mitochondria.oxylation clears OAA to pyruvate in IBAT mitochondria.)
Cadenas 2006 Biochim Biophys Acta + (At low oxygen levels, mitochondrial respir … At low oxygen levels, mitochondrial respiration is controlled by the nitric oxide (NO)-cytochrome c oxidase (COX) signaling pathway, since NO is a membrane-permeant second messenger and competitive inhibitor of COX (1). It is now well established that oxygraphs, with Teflon-coated stirrer bars and other plastic materials of high oxygen solubility, yield high rates of oxygen back-diffusion into the chamber when oxygen levels decline, causing artefacts of respiratory measurements. High-resolution respirometry with the Oroboros O2k reduces such back-diffusion by at least an order of magnitude, and incorporates automatic instrumental background corrections, treating the ‘closed’ chamber essentially as an open system with oxygen transport between the aqueous phase and the system boundary (2). For measurement of NO in experimental chambers, however, the same instrumental problem of gas exchange between hydrophobic plastic materials and the aqueous medium has not been addressed, despite the high partition coefficient of NO between aqueous and organic phases (3). To address these problems, we incorporated an NO sensor (ISO-NOP, WPI) into a Hansatech oxygraph chamber and a high-resolution respirometer (O2k), for simultaneous recording of respiration and NO. The NO sensor was calibrated by addition of known concentrations of KNO2 under reducing conditions (KI/H2SO4) at 37 ºC and the response of the NO sensor in terms of accuracy, stability and reproducibility of the signal was compared between the two chambers. Measurements were taken in 1 ml (Hansatech) or 2 ml (O2k) closed chambers at 37 ºC, using their standard Teflon- or PEEK-coated stirrer bars, respectively. The titanium stopper of the O2k chamber was replaced by a polyvinylidenfluorid (PVDF) stopper, including a second inlet (2 mm diameter) for the NO sensor in addition to the capillary used for extrusion of gas bubbles and titration of chemicals. The PVDF stopper showed identical characteristics to titanium in terms of minimum back-diffusion of oxygen in aerobic-anaerobic transitions, can be cleaned with 70 % and pure ethanol, and offers increased flexibility for accommodation of various additional electrodes for multi-sensor applications. We compared the response of the NO sensor in the determination of the release of NO from a chemical source (DETA-NO) and the endogenous release from controlled intracellular NO production. We determined the inhibition of respiration caused by NO under physiological oxygen concentrations using conventional and high-resolution respirometry (2).ntrations using conventional and high-resolution respirometry (2).)
Reijne 2016 PLOS ONE + (At old age, humans generally have declinin … At old age, humans generally have declining muscle mass and increased fat deposition, which can increase the risk of developing cardiometabolic diseases. While regular physical activity postpones these age-related derangements, this is not always possible in the elderly because of disabilities or risk of injury. Whole-body vibration (WBV) training may be considered as an alternative to physical activity particularly in the frail population. To explore this possibility, we characterized whole-body and organ-specific metabolic processes in 6-month and 25-month old mice, over a period of 14 weeks of WBV versus sham training. WBV training tended to increase blood glucose turnover rates and stimulated hepatic glycogen utilization during fasting irrespective of age. WBV was effective in reducing white fat mass and hepatic triglyceride content only in old but not in young mice and these reductions were related to upregulation of hepatic mitochondrial uncoupling of metabolism (assessed by high-resolution respirometry) and increased expression of uncoupling protein 2. Because these changes occurred independent of changes in food intake and whole-body metabolic rate (assessed by indirect calorimetry), the liver-specific effects of WBV may be a primary mechanism to improve metabolic health during aging, rather than that it is a consequence of alterations in energy balance.sequence of alterations in energy balance.)
Miller 2017 PLOS ONE + (At the annual Iditarod Race, Alaskan Huski … At the annual Iditarod Race, Alaskan Huskies repeatedly run for up to 8 hours at 16 km/h to complete 1600 km. We previously demonstrated high rates of mitochondrial protein synthesis in Alaskan Huskies, which we suspected allowed rapid remodeling of mitochondrial proteins in response to energetic stress. The purpose of this study was to examine mitochondrial respiration in permeabilized skeletal muscle fibers of Alaskan Huskies in the offseason (Non-raced) and following the 1600 km Iditarod Sled Dog Race (Raced). We hypothesized that compared to Non-raced Huskies, raced Huskies that completed a 1600 km race would have greater mitochondrial respiratory capacities, and improvements in capacities of oxidative phosphorylation (OXPHOS) based on NADH-generating substrates as compared to fatty acids. Using high-resolution respirometry (HRR) we investigated the respiration of permeabilized muscle fibers from Alaskan Huskies. Maximum capacities were 254±26 pmol.s-1.mg-1 for OXPHOS (coupled, P) and 254±37 pmol.s-1.mg-1 for the electron transfer-pathway (ET-pathway; non-coupled, E). After racing respiratory capacities from NADH-linked substrates, but not fat-derived substrates increased. Finally, the OXPHOS to ET capacity ratio (P/E) increased after racing from 0.90±0.03 to 0.97±0.02. From our previous studies and the current study, we conclude that Alaskan Huskies maintain high mitochondrial protein turnover to facilitate rapid adaptation to environmental extremes and energetic challenges.urnover to facilitate rapid adaptation to environmental extremes and energetic challenges.)
Koendjbiharie 2021 FEMS Microbiol Rev + (At the junction between the glycolysis and … At the junction between the glycolysis and the tricarboxylic acid cycle-as well as various other metabolic pathways-lies the phosphoenolpyruvate (PEP)-pyruvate-oxaloacetate node (PPO-node). These three metabolites form the core of a network involving at least eleven different types of enzymes, each with numerous subtypes. Obviously, no single organism maintains each of these eleven enzymes; instead, different organisms possess different subsets in their PPO-node, which results in a remarkable degree of variation, despite connecting such deeply conserved metabolic pathways as the glycolysis and the tricarboxylic acid cycle. The PPO-node enzymes play a crucial role in cellular energetics, with most of them involved in (de)phosphorylation of nucleotide phosphates, while those responsible for malate conversion are important redox enzymes. Variations in PPO-node therefore reflect the different energetic niches that organisms can occupy. In this review, we give an overview of the biochemistry of these eleven PPO-node enzymes. We attempt to highlight the variation that exists, both in PPO-node compositions, as well as in the roles that the enzymes can have within those different settings, through various recent discoveries in both bacteria and archaea that reveal deviations from canonical functions.eveal deviations from canonical functions.)
National Academies of Sciences, Engineering, and Medicine 2023 Navigating infodemics + (At the request of the Centers for Disease … At the request of the Centers for Disease Control and Prevention (CDC), the National Academies of Sciences, Engineering, and Medicine hosted a two-day public workshop on April 10-11, 2023 to examine the history of public health infodemics, the impact of infodemics on trust in the public health enterprise, and tools and practices used to address infodemics.At the outset of the workshop, Howard Koh, Harvard T.H. Chan School of Public Health, described the term “infodemic” as the rapid spread of large amounts of sometimes conflicting or inaccurate information that can impede the ability of individuals, communities, and authorities to protect health and effectively respond in a crisis. Even a deluge of accurate information can overwhelm the public. In times of emergency, there may also be situations in which people do not have access to the information they need. In his closing remarks, Griffis called for increased understanding of how to resource institutions at all levels to reduce the harmful effects of mis- and disinformation. To this end, CDC conducts regular meetings with other federal agencies to coordinate responses to emerging misinformation. Furthermore, CDC is working to: (1) build improved misinformation monitoring and alert systems; (2) develop a more systematic approach to misinformation through the agency; (3) create, in collaboration with academic institutions, a system to increase sentinel data collection and social listening; (4) establish rapid response infrastructure to provide the public with accurate information from trusted community sources; and (5) develop tools for public health to predict the virality of vaccine misinformation. CDC continually strives to disseminate accurate information as it is needed through appropriate channels in order to empower the public to make decisions that support their health and wellbeing.s that support their health and wellbeing.)
Nickel 2018 IOC130 + (At the request of the author, this abstract is not made available online.)
Can 2018 IOC130 + (At the request of the author, this abstract is not made available online.)
Janowska 2018 IOC134 + (At the request of the author, this abstract is not made available online.)
Ganetzky 2018 IOC134 + (At the request of the author, this abstract is not made available online.)
Revenco 2019 Abstract IOC141 + (At the request of the author, this abstract is not made available online.)
Mueller 2023 Abstract IOC160 + (At the request of the author, this abstract is not made available online.)
Edman 2023 Abstract IOC160 + (At the request of the author, this abstract is not made available online.)
Rice 2023 Abstract IOC160 + (At the request of the author, this abstract is not made available online.)
Alves 2023 Abstract IOC162 + (At the request of the author, this abstract is not made available online.)
Panajatovic 2017 IOC124 + (At the request of the authors, this abstract is not made available online.)
Simon 2022 Function (Oxf) + (At-risk alcohol use is associated with mul … At-risk alcohol use is associated with multisystemic effects and end-organ injury, and significantly contributes to global health burden. Several alcohol-mediated mechanisms have been identified, with bioenergetic maladaptation gaining credence as an underlying pathophysiological mechanism contributing to cellular injury. This evidence-based review focuses on the current knowledge of alcohol-induced bioenergetic adaptations in metabolically active tissues: liver, cardiac and skeletal muscle, pancreas, and brain. Alcohol metabolism itself significantly interferes with bioenergetic pathways in tissues, particularly the liver. Alcohol decreases states of respiration in the electron transport chain, and activity and expression of respiratory complexes, with a net effect to decrease ATP content. In addition, alcohol dysregulates major metabolic pathways, including glycolysis, the tricarboxylic acid cycle, and fatty acid oxidation. These bioenergetic alterations are influenced by alcohol-mediated changes in mitochondrial morphology, biogenesis, and dynamics. The review highlights similarities and differences in bioenergetic adaptations according to tissue type, pattern of (acute vs. chronic) alcohol use, and energy substrate availability. The compromised bioenergetics synergizes with other critical pathophysiological mechanisms, including increased oxidative stress and accelerates cellular dysfunction, promoting senescence, programmed cell death, and end-organ injury.ogrammed cell death, and end-organ injury.)
Masci 2008 Biochim Biophys Acta + (Ataxia Telangiectasia (AT) patients are pa … Ataxia Telangiectasia (AT) patients are particularly sensitive to oxidative–nitrosative stress. Nitric oxide (NO) controls mitochondrial respiration via the reversible inhibition of complex IV. The mitochondrial response to NO of AT lymphoblastoid cells was investigated. Cells isolated from three patients and three intrafamilial healthy controls were selected showing within each group a normal diploid karyotype and homogeneous telomere length. Different complex IV NO-inhibition patterns were induced by varying the electron flux through the respiratory chain, using exogenous cell membrane permeable electron donors. Under conditions of high electron flux the mitochondrial NO inhibition of respiration was greater in AT than in control cells (P ≤ 0.05). This property appears peculiar to AT, and correlates well to the higher concentration of cytochrome c detected in the AT cells. This finding is discussed on the basis of the proposed mechanism of reaction of NO with complex IV. It is suggested that the peculiar response of AT mitochondria to NO stress may be relevant to the mitochondrial metabolism of AT patients.e mitochondrial metabolism of AT patients.)
Scheede-Bergdahl 2017 Can J Physiol Pharmacol + (Atherosclerosis is one of the leading caus … Atherosclerosis is one of the leading causes of morbidity and mortality in the Western world. Although the clinical manifestations of this disease are well documented, the etiology and progression remain to be fully understood. Recently, the mitochondria have been implicated in important cellular processes involved in development of atherosclerosis. Despite the link between mitochondria and atherosclerosis, early-phase mechanisms of the disease have yet to be elucidated. The aim of this project was to explore the role of mitochondria in vascular smooth muscle (VSMC) dedifferentiation. A murine ''in vitro'' model, involving organ culture of aortic tissue in serum-free media, was used. Mitochondrial function was measured by high-resolution respirometry. Proteins associated with the VSMC phenotype switch, as well as mitochondrial density, were assessed by immunoblotting. The findings show that intrinsic mitochondrial Complex I activity is significantly upregulated during VSMC dedifferentiation. Diminished coupling between phosphorylation and oxidation was also found, indicating a greater ADP:ATP ratio. This data suggests increased leak in the electron transport chain and altered mitochondrial function specifically at Complex I. This project provides important information regarding the role of mitochondria in the early atherosclerotic process and that detectable changes in mitochondrial function and expression are related to VSMC dedifferentiation.ion are related to VSMC dedifferentiation.)
Chowdhury 2010 Am J Physiol Endocrinol Metab + (Atherosclerotic cardiovascular disease is … Atherosclerotic cardiovascular disease is the leading cause of mortality in the Western world. Dysfunction of the mitochondrial respiratory chain and overproduction of reactive oxygen species (ROS) are associated with atherosclerosis and cardiovascular disease. Oxidation increases the atherogenecity of LDL. Oxidized LDL may be apoptotic or nonapoptotic for vascular endothelial cells (EC), depending on the intensity of oxidation. A previous study demonstrated that nonapoptotic oxidized LDL increased activity of mitochondrial complex I in human umbilical vein EC. The present study examined the impact of extensively oxidized LDL (eoLDL) on oxygen consumption and the activities of key enzymes in the mitochondrial respiratory chain of cultured porcine aortic EC. Oxygraphy detected that eoLDL significantly reduced oxygen consumption in various mitochondrial complexes. Treatment with eoLDL significantly decreased NADH-ubiquinone dehydrogenase (complex I), succinate cytochrome c reductase (complex II/III), ubiquinone cytochrome c reductase (complex III), and cytochrome c oxidase (complex IV) activities and the NAD+-to-NADH ratio in EC compared with mildly oxidized LDL, LDL, or vehicle. Butylated hydroxytoluene, a potent antioxidant, normalized eoLDL-induced reductions in complex I and III enzyme activity in EC. Mitochondria-associated intracellular ROS and release of ROS from EC were significantly increased after eoLDL treatment. These findings suggest that eoLDL impairs enzyme activity in mitochondrial respiratory chain complexes and increases ROS generation from mitochondria of arterial EC. Collectively, these effects could contribute to vascular injury and atherogenesis under conditions of hypercholesterolemia and oxidative stress.nditions of hypercholesterolemia and oxidative stress.)
Leo 2021 Conserv Physiol + (Atlantic herring (''Clupea harengus'') is … Atlantic herring (''Clupea harengus'') is a benthic spawner, therefore its eggs are prone to encounter different water conditions during embryonic development, with bottom waters often depleted of oxygen and enriched in CO2. Some Atlantic herring spawning grounds are predicted to be highly affected by ongoing Ocean Acidification and Warming with water temperature increasing by up to +3°C and CO2 levels reaching ca. 1000 μatm (RCP 8.5). Although many studies investigated the effects of high levels of CO2 on the embryonic development of Atlantic herring, little is known about the combination of temperature and ecologically relevant levels of CO2. In this study, we investigated the effects of Ocean Acidification and Warming on embryonic metabolic and developmental performance such as mitochondrial function, respiration, hatching success (HS) and growth in Atlantic herring from the Oslo Fjord, one of the spawning grounds predicted to be greatly affected by climate change. Fertilized eggs were incubated under combinations of two PCO2 conditions (400 μatm and 1100 μatm) and three temperatures (6, 10 and 14°C), which correspond to current and end-of-the-century conditions. We analysed HS, oxygen consumption (MO2) and mitochondrial function of embryos as well as larval length at hatch. The capacity of the electron transport system (ETS) increased with temperature, reaching a plateau at 14°C, where the contribution of Complex I to the ETS declined in favour of Complex II. This relative shift was coupled with a dramatic increase in MO2 at 14°C. HS was high under ambient spawning conditions (6-10°C), but decreased at 14°C and hatched larvae at this temperature were smaller. Elevated PCO2 increased larval malformations, indicating sub-lethal effects. These results indicate that energetic limitations due to thermally affected mitochondria and higher energy demand for maintenance occur at the expense of embryonic development and growth.mally affected mitochondria and higher energy demand for maintenance occur at the expense of embryonic development and growth.)
Leo 2018 Conserv Physiol + (Atlantic herring (Clupea harengus) is a be … Atlantic herring (Clupea harengus) is a benthic spawner, therefore its eggs are prone to encounter different water conditions during embryonic development, with bottom waters often depleted of oxygen and enriched in CO2. Some Atlantic herring spawning grounds are predicted to be highly affected by ongoing Ocean Acidification and Warming with water temperature increasing by up to +3°C and CO2 levels reaching ca. 1000 μatm (RCP 8.5). Although many studies investigated the effects of high levels of CO2 on the embryonic development of Atlantic herring, little is known about the combination of temperature and ecologically relevant levels of CO2. In this study, we investigated the effects of Ocean Acidification and Warming on embryonic metabolic and developmental performance such as mitochondrial function, respiration, hatching success (HS) and growth in Atlantic herring from the Oslo Fjord, one of the spawning grounds predicted to be greatly affected by climate change. Fertilized eggs were incubated under combinations of two PCO2 conditions (400 μatm and 1100 μatm) and three temperatures (6, 10 and 14°C), which correspond to current and end-of-the-century conditions. We analysed HS, oxygen consumption (MO2) and mitochondrial function of embryos as well as larval length at hatch. The capacity of the electron transport system (ETS) increased with temperature, reaching a plateau at 14°C, where the contribution of Complex I to the ETS declined in favour of Complex II. This relative shift was coupled with a dramatic increase in MO2 at 14°C. HS was high under ambient spawning conditions (6-10°C), but decreased at 14°C and hatched larvae at this temperature were smaller. Elevated PCO2 increased larval malformations, indicating sub-lethal effects. These results indicate that energetic limitations due to thermally affected mitochondria and higher energy demand for maintenance occur at the expense of embryonic development and growth.pense of embryonic development and growth.)
Koopman 2022 Abstract Bioblast + (Attachment of cargo molecules to lipophili … Attachment of cargo molecules to lipophilic triphenylphosphonium (TPP+) cations is a widely applied key technology for mitochondrial targeting. We previously demonstrated that the vitamin E-derived antioxidant (Trolox; 500 nM; 96 h) increases the levels of active mitochondrial Complex I (CI), the first complex of the electron transfer system (ETS), in primary human skin fibroblasts (PHSFs) of Leigh Syndrome (LS) patients with isolated CI deficiency. Primed by this finding, we here studied the cellular effects of mitochondria-targeted Trolox (MitoE10), mitochondria-targeted ubiquinone (MitoQ10) and their mitochondria-targeting moiety decylTPP (C10-TPP+). Relative to vehicle (DMSO), chronic treatment (100 nM, 96 h) with these molecules of PHSFs from a healthy subject and an LS patient with isolated CI deficiency (''NDUFS7-V122M'' mutation) did not greatly affect cell viability. Unexpectedly, this treatment significantly reduced CI levels/activity, lowered the amount of ETS supercomplexes, inhibited mitochondrial oxygen consumption, increased extracellular acidification, altered mitochondrial morphology and stimulated the levels of hydroethidine-oxidizing ROS.We conclude that the mitochondria-targeting decylTPP moiety is responsible for the observed effects and advocate that every study employing alkylTPP-mediated mitochondrial targeting should routinely include control experiments with the corresponding alkylTPP moiety. routinely include control experiments with the corresponding alkylTPP moiety.)
Poole 2020 J Physiol + (August Krogh twice won the prestigious int … August Krogh twice won the prestigious international Steegen Prize, for nitrogen metabolism (1906) and overturning the concept of active transport of gases across the pulmonary epithelium (1910). Despite this, at the beginning of 1920, the consummate experimentalist was relatively unknown worldwide and even among his own University of Copenhagen faculty. But, in early 1919, he had submitted three papers to Dr Langley, then editor of The Journal of Physiology in England. These papers coalesced anatomical observations of skeletal muscle capillary numbers with O2 diffusion theory to propose a novel active role for capillaries that explained the prodigious increase in blood-muscle O2 flux from rest to exercise. Despite his own appraisal of the first two papers as "rather dull" to his friend, the eminent Cambridge respiratory physiologist, Joseph Barcroft, Krogh believed that the third one, dealing with O2 supply and capillary regulation, was "interesting". These papers, which won Krogh an unopposed Nobel Prize for Physiology or Medicine in 1920, form the foundation for this review. They single-handedly transformed the role of capillaries from passive conduit and exchange vessels, functioning at the mercy of their upstream arterioles, into independent contractile units that were predominantly closed at rest and opened actively during muscle contractions in a process he termed 'capillary recruitment'. Herein we examine Krogh's findings and some of the experimental difficulties he faced. In particular, the boundary conditions selected for his model (e.g. heavily anaesthetized animals, negligible intramyocyte O2 partial pressure, binary open-closed capillary function) have not withstood the test of time. Subsequently, we update the reader with intervening discoveries that underpin our current understanding of muscle microcirculatory control and place a retrospectroscope on Krogh's discoveries. The perspective is presented that the imprimatur of the Nobel Prize, in this instance, may have led scientists to discount compelling evidence. Much as he and Marie Krogh demonstrated that active transport of gases across the blood-gas barrier was unnecessary in the lung, capillaries in skeletal muscle do not open and close spontaneously or actively, nor is this necessary to account for the increase in blood-muscle O2 flux during exercise. Thus, a contemporary model of capillary function features most muscle capillaries supporting blood flow at rest, and, rather than capillaries actively vasodilating from rest to exercise, increased blood-myocyte O2 flux occurs predominantly via elevating red blood cell and plasma flux in already flowing capillaries. Krogh is lauded for his brilliance as an experimentalist and for raising scientific questions that led to fertile avenues of investigation, including the study of microvascular function.uding the study of microvascular function.)
Radenkovic 2017 Biochem Pharmacol + (Auranofin is a thiol-reactive gold (I)-con … Auranofin is a thiol-reactive gold (I)-containing compound with potential asa chemotherapeutic. Auranofin has the capacity to selectively inhibit endogenous antioxidant enzymes thioredoxin reductase (TrxR) and glutathione peroxidase (GPx), resulting in oxidative stress and the initiation of a pro-apoptotic cascade. The effect of Auranofin exposure on TrxR and GPx, and the potential for cellular protection through selenium supplementation was examined in the non-cancerous human cell line Swan-71. Auranofin exposure resulted in a concentration dependent differential inhibition of selenoprotein antioxidants. Significant inhibition of TrxR was observed at 20nM Auranofin with inhibition of GPx from 10µM. Significant increases in reactive oxygen species (ROS) were associated with antioxidant inhibition at Auranofin concentrations of 100nM (TrxR inhibition) and 10µM (TrxR and GPx inhibition), respectively. Evaluation of mitochondrial respiration demonstrated significant reductions in routine and maximal respiration at both 100nM and 10μM Auranofin. Auranofin treatment at concentrations of 10μM and higher concentrations resulted in a ∼68% decrease in cellular viability and was associated with elevations in pro-apoptotic markers cytochrome c flux control factor (FCFc) at concentration of 100nM and mitochondrial Bax at 10μM. The supplementation of selenium (100nM) prior to treatment had a generalized protective affect through the restoration of antioxidant activity with a significant increase in TrxR and GPx activity, a significant reduction in ROS and associated improvement in mitochondrial respiration and cellular viability (10µM ∼48% increase). Selenium supplementation reduced the FCFc at low doses of Auranofin (<10μM) however no effect was noted on either FCFc or Bax at concentrations above 10μM. The inhibition of antioxidant systems in non-cancerous cells by Auranofin is strongly dose dependent, and this inhibition can be altered by selenium exposure. Therefore, Auranofin dose and the selenium status of patients are important considerations in the therapeutic use of Auranofin as an agent of chemosensitization. Auranofin as an agent of chemosensitization.)
AussieMit 2018 Melbourne AU + (AussieMit 2018, Melbourne, Australia, 2018)
AussieMit 2020 Sydney AU + (AussieMit 2020, Sydney, Australia, 2020)
AussieMit 2022 Sydney AU + (AussieMit 2022, Sydney, Australia, 2022)
Gama Perez 2023 MiP2023 + (Authors: [[Gama Perez Pau]] … Authors: [[Gama Perez Pau]] Chronic overfeeding has a profound metabolic impact on multiple tissues. Consequently, unraveling the differential adaptations in each of them is fundamental to understand the progression of obesity-related comorbidities. In our laboratory we have tackled this issue in a model of obesity and weight loss induced by a combined nutritional and exercise intervention. This model has enabled us to identify visceral adipose tissue as the most vulnerable organ to such stress, not only by the magnitude of changes observed in the obese state but most importantly, because of the permanent alterations we observe even after the restoration of adequate weight and metabolic health. Whether this fingerprint is a distinctive trait of the visceral fat or it is affecting other depots is still unsolved, although the recognized developmental, morphological as well as functional differences among fat depots might drive a differential response.To this end, we aim to explore the subcutaneous adipose tissue behavior in our model, characterizing those significant indicators of vulnerability already identified in the visceral depot. These include linear regression models to correlate tissue mass and body weight, histological and immunohistochemical analysis to characterize the morphological remodeling of the tissue, the assessment of transcriptional changes in both tissues, as well as the impact on mitochondria through the evaluation of OXPHOS capacities and the quantification of mitochondrial DNA.This comparative analysis suggests that unlike visceral fat, the detrimental impact of chronic overfeeding is blunted in subcutaneous adipose tissue, with no apparent consequences on its metabolic plasticity. Among the important points to consider, these findings could represent a relevant concern for the study of obesity-related pathophysiology in humans since, thus far, most longitudinal studies exploring adipose tissue responses to weight fluctuations have been addressed in subcutaneous biopsies due to ethical constrains.ed in subcutaneous biopsies due to ethical constrains.)
Yardeni 2021 Proc Natl Acad Sci U S A + (Autism spectrum disorders (ASDs) are chara … Autism spectrum disorders (ASDs) are characterized by a deficit in social communication, pathologic repetitive behaviors, restricted interests, and electroencephalogram (EEG) aberrations. While exhaustive analysis of nuclear DNA (nDNA) variation has revealed hundreds of copy number variants (CNVs) and loss-of-function (LOF) mutations, no unifying hypothesis as to the pathophysiology of ASD has yet emerged. Based on biochemical and physiological analyses, it has been hypothesized that ASD may be the result of a systemic mitochondrial deficiency with brain-specific manifestations. This proposal has been supported by recent mitochondrial DNA (mtDNA) analyses identifying both germline and somatic mtDNA variants in ASD. If mitochondrial defects do predispose to ASD, then mice with certain mtDNA mutations should present with autism endophenotypes. To test this prediction, we examined a mouse strain harboring an mtDNA ND6 gene missense mutation (P25L). This mouse manifests impaired social interactions, increased repetitive behaviors and anxiety, EEG alterations, and a decreased seizure threshold, in the absence of reduced hippocampal interneuron numbers. EEG aberrations were most pronounced in the cortex followed by the hippocampus. Aberrations in mitochondrial respiratory function and reactive oxygen species (ROS) levels were also most pronounced in the cortex followed by the hippocampus, but absent in the olfactory bulb. These data demonstrate that mild systemic mitochondrial defects can result in ASD without apparent neuroanatomical defects and that systemic mitochondrial mutations can cause tissue-specific brain defects accompanied by regional neurophysiological alterations.y regional neurophysiological alterations.)
Kim 2018 Pflugers Arch + (Autophagy and mitophagy are important for … Autophagy and mitophagy are important for training-inducible muscle adaptations, yet it remains unclear how these systems are regulated throughout the adaptation process. Here, we studied autophagic and mitophagic flux in the skeletal muscles of Sprague-Dawley rats (300-500 g) exposed to chronic contractile activity (CCA; 3 h/day, 9 V, 10 Hz continuous, 0.1 ms pulse duration) for 1, 2, 5, and 7 days (N = 6-8/group). In order to determine the flux rates, colchicine (COL; 0.4 mg/ml/kg) was injected 48 h before tissue collection, and we evaluated differences of autophagosomal protein abundances (LC3-II and p62) between colchicine- and saline-injected animals. We confirmed that CCA resulted in mitochondrial adaptations, including improved state 3 respiration as early as day 1 in permeabilized muscle fibers, as well significant increases in mitochondrial respiratory capacity and marker proteins in IMF mitochondria by day 7. Mitophagic and autophagic flux (LC3-II and p62) were significantly decreased in skeletal muscle following 7 days of CCA. Notably, the mitophagic system seemed to be downregulated prior (day 3-5) to changes in autophagic flux (day 7), suggesting enhanced sensitivity of mitophagy compared to autophagy with chronic muscle contraction. Although we detected no significant change in the nuclear translocation of TFEB, a regulator of lysosomal biogenesis, CCA increased total TFEB protein, as well as LAMP1, in skeletal muscle. Thus, chronic muscle activity reduces mitophagy in parallel with improved mitochondrial function, and this is supported by enhanced lysosomal degradation capacity.y enhanced lysosomal degradation capacity.)
Kim 2019 Pflugers Arch + (Autophagy and mitophagy are important for … Autophagy and mitophagy are important for training-inducible muscle adaptations, yet it remains unclear how these systems are regulated throughout the adaptation process. Here, we studied autophagic and mitophagic flux in the skeletal muscles of Sprague-Dawley rats (300-500 g) exposed to chronic contractile activity (CCA; 3 h/day, 9 V, 10 Hz continuous, 0.1 ms pulse duration) for 1, 2, 5, and 7 days (N = 6-8/group). In order to determine the flux rates, colchicine (COL; 0.4 mg/ml/kg) was injected 48 h before tissue collection, and we evaluated differences of autophagosomal protein abundances (LC3-II and p62) between colchicine- and saline-injected animals. We confirmed that CCA resulted in mitochondrial adaptations, including improved state 3 respiration as early as day 1 in permeabilized muscle fibers, as well significant increases in mitochondrial respiratory capacity and marker proteins in IMF mitochondria by day 7. Mitophagic and autophagic flux (LC3-II and p62) were significantly decreased in skeletal muscle following 7 days of CCA. Notably, the mitophagic system seemed to be downregulated prior (day 3-5) to changes in autophagic flux (day 7), suggesting enhanced sensitivity of mitophagy compared to autophagy with chronic muscle contraction. Although we detected no significant change in the nuclear translocation of TFEB, a regulator of lysosomal biogenesis, CCA increased total TFEB protein, as well as LAMP1, in skeletal muscle. Thus, chronic muscle activity reduces mitophagy in parallel with improved mitochondrial function, and this is supported by enhanced lysosomal degradation capacity.y enhanced lysosomal degradation capacity.)
Dutta 2013 Autophagy + (Autophagy is a cellular self-digestion pro … Autophagy is a cellular self-digestion process that mediates protein quality control and serves to protect against neurodegenerative disorders, infections, inflammatory diseases and cancer. Current evidence suggests that autophagy can selectively remove damaged organelles such as the mitochondria. Mitochondria-induced oxidative stress has been shown to play a major role in a wide range of pathologies in several organs, including the heart. Few studies have investigated whether enhanced autophagy can offer protection against mitochondrially-generated oxidative stress. We induced mitochondrial stress in cardiomyocytes using antimycin A (Ama), which increased mitochondrial superoxide generation, decreased mitochondrial membrane potential and depressed cellular respiration. In addition, Ama augmented nuclear DNA oxidation and cell death in cardiomyocytes. Interestingly, although oxidative stress has been proposed to induce autophagy, treatment with Ama did not result in stimulation of autophagy or mitophagy in cardiomyocytes. Our results showed that the MTOR inhibitor rapamycin induced autophagy, promoted mitochondrial clearance and protected cardiomyocytes from the cytotoxic effects of Ama, as assessed by apoptotic marker activation and viability assays in both mouse atrial HL-1 cardiomyocytes and human ventricular AC16 cells. Importantly, rapamycin improved mitochondrial function, as determined by cellular respiration, mitochondrial membrane potential and morphology analysis. Furthermore, autophagy induction by rapamycin suppressed the accumulation of ubiquitinylated proteins induced by Ama. Inhibition of rapamycin-induced autophagy by pharmacological or genetic interventions attenuated the cytoprotective effects of rapamycin against Ama. We propose that rapamycin offers cytoprotection against oxidative stress by a combined approach of removing dysfunctional mitochondria as well as by degrading damaged, ubiquitinated proteins. We conclude that autophagy induction by rapamycin could be utilized as a potential therapeutic strategy against oxidative stress-mediated damage in cardiomyocytes. stress-mediated damage in cardiomyocytes.)
Leduc-Gaudet 2023 Nat Commun + (Autophagy is a critical process in the reg … Autophagy is a critical process in the regulation of muscle mass, function and integrity. The molecular mechanisms regulating autophagy are complex and still partly understood. Here, we identify and characterize a novel FoxO-dependent gene, d230025d16rik which we named Mytho (Macroautophagy and YouTH Optimizer), as a regulator of autophagy and skeletal muscle integrity ''in vivo''. Mytho is significantly up-regulated in various mouse models of skeletal muscle atrophy. Short term depletion of MYTHO in mice attenuates muscle atrophy caused by fasting, denervation, cancer cachexia and sepsis. While MYTHO overexpression is sufficient to trigger muscle atrophy, MYTHO knockdown results in a progressive increase in muscle mass associated with a sustained activation of the mTORC1 signaling pathway. Prolonged MYTHO knockdown is associated with severe myopathic features, including impaired autophagy, muscle weakness, myofiber degeneration, and extensive ultrastructural defects, such as accumulation of autophagic vacuoles and tubular aggregates. Inhibition of the mTORC1 signaling pathway in mice using rapamycin treatment attenuates the myopathic phenotype triggered by MYTHO knockdown. Skeletal muscles from human patients diagnosed with myotonic dystrophy type 1 (DM1) display reduced Mytho expression, activation of the mTORC1 signaling pathway and impaired autophagy, raising the possibility that low Mytho expression might contribute to the progression of the disease. We conclude that MYTHO is a key regulator of muscle autophagy and integrity.gulator of muscle autophagy and integrity.)
De Castro IP 2013 Cell Death Dis + (Autophagy is a critical regulator of organ … Autophagy is a critical regulator of organellar homeostasis, particularly of mitochondria. Upon the loss of membrane potential, dysfunctional mitochondria are selectively removed by autophagy through recruitment of the E3 ligase Parkin by the PTEN-induced kinase 1 (PINK1) and subsequent ubiquitination of mitochondrial membrane proteins. Mammalian sequestrome-1 (p62/SQSTM1) is an autophagy adaptor, which has been proposed to shuttle ubiquitinated cargo for autophagic degradation downstream of Parkin. Here, we show that loss of ''ref(2)P'', the ''Drosophila'' orthologue of mammalian ''P62'', results in abnormalities, including mitochondrial defects and an accumulation of mitochondrial DNA with heteroplasmic mutations, correlated with locomotor defects. Furthermore, we show that expression of Ref(2)P is able to ameliorate the defects caused by loss of Pink1 and that this depends on the presence of functional Parkin. Finally, we show that both the PB1 and UBA domains of Ref(2)P are crucial for mitochondrial clustering. We conclude that Ref(2)P is a crucial downstream effector of a pathway involving Pink1 and Parkin and is responsible for the maintenance of a viable pool of cellular mitochondria by promoting their aggregation and autophagic clearance.heir aggregation and autophagic clearance.)
Setz 2018 Hear Res + (Autophagy is a highly evolutionary conserv … Autophagy is a highly evolutionary conserved quality control defense mechanism within cells, which has also been implicated in cell death processes. In the mammalian inner ear, autophagy has been shown to play a role during early morphogenesis as well as in adult cochlear hair cells exposed to ototoxic insults. Mitophagy, a selective autophagic cell process targeting mitochondria, hasn't been studied in the inner ear so far. On this work, we searched for molecular indicators of mitophagy within House Ear Institute-Organ of Corti-1 (HEI-OC1) cells as well as in the organ of Corti (OC). We first tested for the expression of ''Pink1''/''Park2'' mRNA in 5-day-old C57BL/6 mice's cochleae using RT-PCR. We focused on the induction of mitophagy in HEI-OC1 cells as well as in the OC and investigated a possible mitophagic potential of the aminoglycoside agent gentamicin. The induction of mitophagy in HEI-OC1 cells was detected by objectivizing the translocation of fluorescence-tagged LC3 to mitochondria using confocal microscopy after a 6-h incubation with a well-described mitochondrial uncoupler and mitophagy-inducing agent: carbonyl cyanide m-chlorophenyl hydrazone (CCCP). Incubation with gentamicin generated no mitochondrial translocation of LC3. Protein levels of COXIV, Atg5/12 and LC3 were evaluated by an immunoblot analysis after a 24-h CCCP treatment as well as gentamicin. We demonstrated mitophagy after CCCP exposure in HEI-OC1 cells by showing a downregulation of COXIV. A downregulation of COXIV could also be visualized in the OC after CCCP. A significant oxygen consumption rate (OCR) changed in cells treated with CCCP as well as significant morphological changes of mitochondria by electron microscopy (EM) strengthen this assumption. Gentamicin exposure generated no impact on OCR or mitochondrial morphological changes by EM. Finally, we demonstrated changes in the expression of Atg12 and LC3 proteins in both the OC and HEI-OC1 cells after CCCP exposure but not after gentamicin. Our data indicate that gentamicin had no impact in the activation of mitophagy-neither in the HEI-OC1 cell line nor in the OC. Therefore, we speculate that mitophagic-independent mechanisms may underly aminoglycoside ototoxicity.ms may underly aminoglycoside ototoxicity.)
Kataura 2022 Dev Cell + (Autophagy is an essential catabolic proces … Autophagy is an essential catabolic process that promotes the clearance of surplus or damaged intracellular components. Loss of autophagy in age-related human pathologies contributes to tissue degeneration through a poorly understood mechanism. Here, we identify an evolutionarily conserved role of autophagy from yeast to humans in the preservation of nicotinamide adenine dinucleotide (NAD) levels, which are critical for cell survival. In respiring mouse fibroblasts with autophagy deficiency, loss of mitochondrial quality control was found to trigger hyperactivation of stress responses mediated by NADases of PARP and Sirtuin families. Uncontrolled depletion of the NAD(H) pool by these enzymes ultimately contributed to mitochondrial membrane depolarization and cell death. Pharmacological and genetic interventions targeting several key elements of this cascade improved the survival of autophagy-deficient yeast, mouse fibroblasts, and human neurons. Our study provides a mechanistic link between autophagy and NAD metabolism and identifies targets for interventions in human diseases associated with autophagic, lysosomal, and mitochondrial dysfunction. lysosomal, and mitochondrial dysfunction.)
Wilson 2023 Trends Cell Biol + (Autophagy is an intracellular degradation … Autophagy is an intracellular degradation pathway that recycles subcellular components to maintain metabolic homeostasis. NAD is an essential metabolite that participates in energy metabolism and serves as a substrate for a series of NAD+-consuming enzymes (NADases), including PARPs and SIRTs. Declining levels of autophagic activity and NAD represent features of cellular ageing, and consequently enhancing either significantly extends health/lifespan in animals and normalises metabolic activity in cells. Mechanistically, it has been shown that NADases can directly regulate autophagy and mitochondrial quality control. Conversely, autophagy has been shown to preserve NAD levels by modulating cellular stress. In this review we highlight the mechanisms underlying this bidirectional relationship between NAD and autophagy, and the potential therapeutic targets it provides for combatting age-related disease and promoting longevity.e-related disease and promoting longevity.)
Ljubojevic-Holzer 2021 Cardiovasc Res + (Autophagy protects against the development … Autophagy protects against the development of cardiac hypertrophy and failure. While aberrant Ca2+ handling promotes myocardial remodelling and contributes to contractile dysfunction, the role of autophagy in maintaining Ca2+ homeostasis remains elusive. Here, we examined whether Atg5 deficiency-mediated autophagy promotes early changes in subcellular Ca2+ handling in ventricular cardiomyocytes, and whether those alterations associate with compromised cardiac reserve capacity, which commonly precedes the onset of heart failure.RT-qPCR and immunoblotting demonstrated reduced Atg5 gene and protein expression and decreased abundancy of autophagy markers in hypertrophied and failing human hearts. The function of ATG5 was examined using cardiomyocyte-specific Atg5-knockout mice (Atg5-/-). Before manifesting cardiac dysfunction, Atg5-/- mice showed compromised cardiac reserve in response to β-adrenergic stimulation. Consequently, effort intolerance and maximal oxygen consumption were reduced during treadmill-based exercise tolerance testing. Mechanistically, cellular imaging revealed that Atg5 deprivation did not alter spatial and functional organization of intracellular Ca2+ stores or affect Ca2+ cycling in response to slow pacing or upon acute isoprenaline administration. However, high frequency stimulation exposed stunted amplitude of Ca2+ transients, augmented nucleoplasmic Ca2+ load and increased CaMKII activity, especially in the nuclear region of hypertrophied Atg5-/- cardiomyocytes. These changes in Ca2+ cycling were recapitulated in hypertrophied human cardiomyocytes. Finally, ultrastructural analysis revealed accumulation of mitochondria with reduced volume and size distribution, meanwhile functional measurements showed impaired redox balance in Atg5-/- cardiomyocytes, implying energetic unsustainability due to overcompensation of single mitochondria, particularly under increased workload.Loss of cardiac Atg5-dependent autophagy reduces mitochondrial abundance and causes subtle alterations in subcellular Ca2+ cycling upon increased workload in mice. Autophagy-related impairment of Ca2+ handling is progressively worsened by β-adrenergic signalling in ventricular cardiomyocytes, thereby leading to energetic exhaustion and compromised cardiac reserve.ed impairment of Ca2+ handling is progressively worsened by β-adrenergic signalling in ventricular cardiomyocytes, thereby leading to energetic exhaustion and compromised cardiac reserve.)
Morselli 2011 J Cell Biol + (Autophagy protects organelles, cells, and … Autophagy protects organelles, cells, and organisms against several stress conditions. Induction of autophagy by resveratrol requires the nicotinamide adenine dinucleotide-dependent deacetylase sirtuin 1 (SIRT1). In this paper, we show that the acetylase inhibitor spermidine stimulates autophagy independent of SIRT1 in human and yeast cells as well as in nematodes. Although resveratrol and spermidine ignite autophagy through distinct mechanisms, these compounds stimulate convergent pathways that culminate in concordant modifications of the acetylproteome. Both agents favor convergent deacetylation and acetylation reactions in the cytosol and in the nucleus, respectively. Both resveratrol and spermidine were able to induce autophagy in cytoplasts (enucleated cells). Moreover, a cytoplasm-restricted mutant of SIRT1 could stimulate autophagy, suggesting that cytoplasmic deacetylation reactions dictate the autophagic cascade. At doses at which neither resveratrol nor spermidine stimulated autophagy alone, these agents synergistically induced autophagy. Altogether, these data underscore the importance of an autophagy regulatory network of antagonistic deacetylases and acetylases that can be pharmacologically manipulated.that can be pharmacologically manipulated.)
Van Bergen 2011 PLoS One + (Autosomal Dominant Optic Atrophy (ADOA) is … Autosomal Dominant Optic Atrophy (ADOA) is the most common inherited optic atrophy where vision impairment results from specific loss of retinal ganglion cells of the optic nerve. Around 60% of ADOA cases are linked to mutations in the OPA1 gene. OPA1 is a fission-fusion protein involved in mitochondrial inner membrane remodelling. ADOA presents with marked variation in clinical phenotype and varying degrees of vision loss, even among siblings carrying identical mutations in OPA1. To determine whether the degree of vision loss is associated with the level of mitochondrial impairment, we examined mitochondrial function in lymphoblast cell lines obtained from six large Australian OPA1-linked ADOA pedigrees. Comparing patients with severe vision loss (visual acuity [VA]<6/36) and patients with relatively preserved vision (VA>6/9) a clear defect in mitochondrial ATP synthesis and reduced respiration rates were observed in patients with poor vision. In addition, oxidative phosphorylation (OXPHOS) enzymology in ADOA patients with normal vision revealed increased complex II+III activity and levels of complex IV protein. These data suggest that OPA1 deficiency impairs OXPHOS efficiency, but compensation through increases in the distal complexes of the respiratory chain may preserve mitochondrial ATP production in patients who maintain normal vision. Identification of genetic variants that enable this response may provide novel therapeutic insights into OXPHOS compensation for preventing vision loss in optic neuropathies.or preventing vision loss in optic neuropathies.)
Lesage 2016 Am J Hum Genet + (Autosomal-recessive early-onset parkinsoni … Autosomal-recessive early-onset parkinsonism is clinically and genetically heterogeneous. The genetic causes of approximately 50% of autosomal-recessive early-onset forms of Parkinson disease (PD) remain to be elucidated. Homozygozity mapping and exome sequencing in 62 isolated individuals with early-onset parkinsonism and confirmed consanguinity followed by data mining in the exomes of 1,348 PD-affected individuals identified, in three isolated subjects, homozygous or compound heterozygous truncating mutations in vacuolar protein sorting 13C (VPS13C). VPS13C mutations are associated with a distinct form of early-onset parkinsonism characterized by rapid and severe disease progression and early cognitive decline; the pathological features were striking and reminiscent of diffuse Lewy body disease. In cell models, VPS13C partly localized to the outer membrane of mitochondria. Silencing of VPS13C was associated with lower mitochondrial membrane potential, mitochondrial fragmentation, increased respiration rates, exacerbated PINK1/Parkin-dependent mitophagy, and transcriptional upregulation of PARK2 in response to mitochondrial damage. This work suggests that loss of function of VPS13C is a cause of autosomal-recessive early-onset parkinsonism with a distinctive phenotype of rapid and severe progression.Copyright © 2016 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.shed by Elsevier Inc. All rights reserved.)
Angebault 2015 Am J Hum Genet + (Autosomal-recessive optic neuropathies are … Autosomal-recessive optic neuropathies are rare blinding conditions related to retinal ganglion cell (RGC) and optic-nerve degeneration, for which only mutations in ''TMEM126A'' and ''ACO2'' are known. In four families with early-onset recessive optic neuropathy, we identified mutations in ''RTN4IP1'', which encodes a mitochondrial ubiquinol oxydo-reductase. ''RTN4IP1'' is a partner of ''RTN4'' (also known as NOGO), and its ortholog Rad8 in ''C. elegans'' is involved in UV light response. Analysis of fibroblasts from affected individuals with a ''RTN4IP1'' mutation showed loss of the altered protein, a deficit of mitochondrial respiratory complex I and IV activities, and increased susceptibility to UV light. Silencing of RTN4IP1 altered the number and morphogenesis of mouse RGC dendrites ''in vitro'' and the eye size, neuro-retinal development, and swimming behavior in zebrafish ''in vivo''. Altogether, these data point to a pathophysiological mechanism responsible for RGC early degeneration and optic neuropathy and linking ''RTN4IP1'' functions to mitochondrial physiology, response to UV light, and dendrite growth during eye maturation.and dendrite growth during eye maturation.)
D'Souza 2018 J Lipid Res + (Autotaxin (ATX) is an adipokine that gener … Autotaxin (ATX) is an adipokine that generates the bioactive lipid, lysophosphatidic acid (LPA). ATX-LPA signaling has been implicated in diet-induced obesity and systemic insulin resistance. However, it remains unclear whether the ATX-LPA pathway influences insulin function and energy metabolism in target tissues, particularly skeletal muscle, the major site of insulin-stimulated glucose disposal. The objective of this study was to test whether the ATX-LPA pathway impacts tissue insulin signaling and mitochondrial metabolism in skeletal muscle during obesity. Male mice with heterozygous ATX deficiency (ATX+/-) were protected from obesity, systemic insulin resistance, and cardiomyocyte dysfunction following high-fat high-sucrose (HFHS) feeding. HFHS-fed ATX+/- mice also had improved insulin-stimulated AKT phosphorylation in white adipose tissue, liver, heart, and skeletal muscle. Preserved insulin-stimulated glucose transport in muscle from HFHS-fed ATX+/- mice was associated with improved mitochondrial pyruvate oxidation in the absence of changes in fat oxidation and ectopic lipid accumulation. Similarly, incubation with LPA decreased insulin-stimulated AKT phosphorylation and mitochondrial energy metabolism in C2C12 myotubes at baseline and following palmitate-induced insulin resistance. Taken together, our results suggest that the ATX-LPA pathway contributes to obesity-induced insulin resistance in metabolically relevant tissues. Our data also suggest that LPA directly impairs skeletal muscle insulin signaling and mitochondrial function.directly impairs skeletal muscle insulin signaling and mitochondrial function.)
Albertini 2012 Aging (Albany NY) + (Availability of methionine is known to mod … Availability of methionine is known to modulate the rate of aging in model organisms, best illustrated by the observation that dietary methionine restriction extends the lifespan of rodents. However, the underlying mechanisms are incompletely understood. In eukaryotic cells, methionine can be converted to cysteine through the reverse transsulfuration pathway thereby modulating intracellular methionine availability. Whereas previous results obtained in yeast and fruit flies suggest that alterations in the reverse transsulfuration pathway modulate the rate of aging, it is not known whether this function is conserved in evolution. Here we show that depletion of cystathionine beta synthase (CBS), a rate limiting enzyme in the reverse transsulfuration pathway, induces premature senescence in human endothelial cells. We found that CBS depletion induces mild mitochondrial dysfunction and increases the sensitivity of endothelial cells to homocysteine, a known inducer of endothelial cell senescence and an established risk factor for vascular disease. Our finding that CBS deficiency induces endothelial cell senescence ''in vitro'', involving both mitochondrial dysfunction and increased susceptibility of the cells to homocysteine, suggests a new mechanism linking CBS deficiency to vascular aging and disease. deficiency to vascular aging and disease.)
Ravera 2018 Biol Cell + (BACKGROUND INFORMATION: Energy demand in h … BACKGROUND INFORMATION: Energy demand in human platelets is very high, to carry out their functions. As for most human cells, the aerobic metabolism represents the primary energy source in platelets, even though mitochondria are negligibly represented. Following the hypothesis that other structures could be involved in chemical energy production, in this work, we have investigated the functional expression of an extramitochondrial aerobic metabolism in platelets.RESULTS: Oximetric and luminometric analyses showed that platelets consume large amounts of oxygen and produce ATP in the presence of common respiring substrates, such as pyruvate + malate or succinate, although morphological electron microscopy analysis showed that these contain few mitochondria. However, evaluation of the anaerobic glycolytic metabolism showed that only 13% of consumed glucose was converted to lactate. Interestingly, the highest OXPHOS activity was observed in the presence of NADH, not a readily permeant respiring substrate for mitochondria. Also, oxygen consumption and ATP synthesis fuelled by NADH were not affected by atractyloside, an inhibitor of the adenine nucleotide translocase, suggesting that these processes may not be ascribed to mitochondria. Functional data were confirmed by immunofluorescence microscopy and Western blot analyses, showing a consistent expression of the β subunit of F1 Fo -ATP synthase and COXII, a subunit of Complex IV, but a low signal of translocase of the inner mitochondrial membrane (a protein not involved in OXPHOS metabolism). Interestingly, the NADH-stimulated oxygen consumption and ATP synthesis increased in the presence of the physiological platelets agonists, thrombin or collagen.CONCLUSIONS: Data suggest that in platelets, aerobic energy production is mainly driven by an extramitochondrial OXPHOS machinery, originated inside the megakaryocyte, and that this metabolism plays a pivotal role in platelet activation.SIGNIFICANCE: This work represents a further example of the existence of an extramitochondrial aerobic metabolism, which can contribute to the cellular energy balance.contribute to the cellular energy balance.)
Regueira 2009 Liver Int + (BACKGROUND/AIMS: Genes encoding for some o … BACKGROUND/AIMS:Genes encoding for some of the mitochondrial proteins are under the control of the transcriptional factor hypoxia inducible factor-1 alpha (HIF-1 alpha), which can accumulate under normoxic conditions in inflammatory states. The aim of this study was to evaluate the effects of cobalt chloride (CoCl2, a hypoxia mimicking agent), tumour necrosis factor-alpha (TNF-alpha) and toll-like receptor (TLR) -2, -3 and -4 agonists on HIF-1 alpha accumulation, and further on HIF-1 alpha-mediated modulation of mitochondrial respiration in cultured human hepatocytes.METHODS:The human hepatoma cell line HepG2 was used in this study. Cells were treated with CoCl2, TNF-alpha and TLR-2, -3 and -4 agonists. HIF-1 alpha was determined by Western blotting and mitochondrial respiration in stimulated cells by high-resolution respirometry.RESULTS:CoCl2, TNF-alpha and TLR agonists induced the expression of HIF-1 alpha in a time-dependent fashion. TNF-alpha and CoCl2, but not TLR agonists, induced a reduction in complex I-, II- and IV-dependent mitochondrial oxygen consumption. TNF-alpha-associated reduction of cellular oxygen consumption was abolished through inhibition of HIF-1 alpha activity by chetomin (CTM). Pretreatment with cyclosporine A prevented CoCl2-induced reduction of complex I- and II-dependent mitochondrial oxygen consumption and TNF-alpha-induced reduction of complex-I-dependent respiration, implicating the involvement of the mitochondrial permeability transition pore openings. TNF-alpha and TLR-2, -3 and -4 agonists induced the expression of vascular endothelial growth factor, which was partially abolished by the blockage of HIF-1 alpha with CTM.CONCLUSIONS:The data suggest that HIF-1 alpha modulates mitochondrial respiration during CoCl2 and TNF-alpha stimulation, whereas it has no effect when induced with TLR-2, -3 and -4 agonists.>2 and TNF-alpha stimulation, whereas it has no effect when induced with TLR-2, -3 and -4 agonists.)
Escribano-Lopez 2019 Cell Physiol Biochem + (BACKGROUND/AIMS: Mitochondria-targeted ant … BACKGROUND/AIMS:Mitochondria-targeted antioxidants such as mitoquinone (MitoQ) have demonstrated protective effects against oxidative damage in several diseases. The increase in reactive oxygen species (ROS) production during glucose metabolism in β cells can be exacerbated under hyperglycaemic conditions such as type 2 diabetes (T2D), thus contributing to β cell function impairment. In the present work, we aimed to evaluate the effect of MitoQ on insulin secretion, oxidative stress, endoplasmic reticulum (ER) stress and nuclear factor kappa B (NFκB) signalling in a pancreatic β cell line under normoglycaemic (NG, 11.1 mM glucose), hyperglycaemic (HG, 25 mM glucose) and lipidic (palmitic acid (PA), 0.5mM) conditions.METHODS:We incubated the pancreatic β cell line INS-1E with or without MitoQ (0.5µM) under NG, HG and PA conditions. We then assessed the following parameters: glucose-induced insulin secretion, O₂ consumption (with a Clark-type electrode); mitochondrial function, oxidative stress parameters and calcium levels (by fluorescence microscopy); ER stress markers and NFκB-p65 protein levels (by western blotting).RESULTS:MitoQ increased insulin secretion and prevented the enhancement of ROS production and O₂ consumption and decrease in GSH levels that are characteristic under HG conditions. MitoQ also reduced protein levels of ER stress markers (GRP78 and P-eIF2α) and the proinflammatory nuclear transcription factor NFκB-p65, both of which increased under HG. MitoQ did not significantly alter ER stress markers under lipidic conditions.CONCLUSION:Our findings suggest that treatment with MitoQ modulates mitochondrial function, which in turn ameliorates endoplasmic reticulum stress and NFκB activation, thereby representing potential benefits for pancreatic β cell function.l benefits for pancreatic β cell function.)
Johnson 2016 Transfusion + (BACKGROUND: Alternatives to room temperat … BACKGROUND:Alternatives to room temperature storage of platelets (PLTs) may be beneficial to extend the limited shelf life and support transfusion logistics in rural and military areas. The aim of this study was to assess the morphologic, metabolic, and functional aspects of PLTs stored at room temperature or in refrigerated conditions or cryopreserved.STUDY DESIGN AND METHODS:A three-arm pool-and-split study was carried out using buffy coat-derived PLTs stored in 30% plasma/70% SSP+. The three matched treatment arms were room temperature stored (20-24°C), cold-stored (2-6°C), and cryopreserved (-80°C with dimethyl sulfoxide). Liquid-stored PLTs were tested over a 21-day period, while cryopreserved PLTs were examined immediately after thawing and after 6 and 24 hours of storage at room temperature.RESULTS:Cold-stored and cryopreserved PLTs underwent a significant shape change, although the cryopreserved PLTs appeared to recover from this during subsequent storage. Glycolytic metabolism was reduced in cold-stored PLTs, but accelerated in cryopreserved PLTs, while oxidative phosphorylation was negatively affected by both storage conditions. PLT aggregation was potentiated by cold storage and diminished by cryopreservation in comparison to room temperature-stored PLTs. Cold storage and cryopreservation resulted in faster clot formation (R-time; thromboelastography), which was associated with an increase in microparticles.CONCLUSION:Cold storage and cryopreservation of PLTs led to morphologic and metabolic changes. However, storage under these conditions appears to maintain or even enhance certain aspects of in vitro PLT function. certain aspects of in vitro PLT function.)
Johnson 2014 Transfusion + (BACKGROUND: Cryopreservation of platelets … BACKGROUND:Cryopreservation of platelets (PLTs) at -80°C with dimethyl sulfoxide (DMSO) can extend the shelf life from 5 days to 2 years. Cryopreserved PLTs are reported to have a greater in vivo hemostatic effect than liquid-stored PLTs. As such, the aim of this study was to understand the mechanisms responsible for the hemostatic potential of cryopreserved PLTs and the contribution of the reconstitution solution to this activity.STUDY DESIGN AND METHODS:DMSO (5% final concentration) was added to buffy coat-derived PLTs, followed by prefreeze removal of DMSO and storage at -80°C. Cryopreserved PLTs (n=8 per group) were thawed at 37°C, reconstituted with either 1 unit of thawed frozen plasma or PLT additive solution (PAS-G). In vitro assays were performed before freezing and after thawing to assess the hemostatic activity of PLTs.RESULTS:Cryopreserved PLTs expressed high levels of phosphatidylserine and contained significantly more phosphatidylserine-positive PLT microparticles than liquid-stored PLTs. This was accompanied by a significant decrease in the time to clot formation and clot strength, as measured by thromboelastography. The supernatant from cryopreserved PLTs was sufficient to reduce the phosphatidylserine-dependent clotting time and increase the thrombin generation potential. Overall, plasma-reconstituted cryopreserved PLTs were more procoagulant than those reconstituted in PAS-G.CONCLUSION:PLT cryopreservation results in the generation of phosphatidylserine-expressing PLT microparticles which contribute to the hemostatic activity. Understanding the hemostatic activity of these components may assist in extending the use of these specialized components beyond military applications.d components beyond military applications.)
Angiulli 2015 Biochim Biophys Acta + (BACKGROUND: ''Leishmania infantum'' is a p … BACKGROUND:''Leishmania infantum'' is a protozoan of the trypanosomatid family causing ''visceral leishmaniasis''. ''Leishmania'' parasites are transmitted by the bite of phlebotomine sand flies to the human host and are phagocyted by macrophages. The parasites synthesize N1-N8-bis(glutationyl)-spermidine (trypanothione, TS2), which furnishes electrons to the tryparedoxin-tryparedoxin peroxidase couple to reduce the reactive oxygen species produced by macrophages. Trypanothione is kept reduced by trypanothione reductase (TR), a FAD-containing enzyme essential for parasite survival.METHODS:The enzymatic activity has been studied by stopped-flow, absorption spectroscopy, and amperometric measurements.RESULTS:The study reported here demonstrates that the steady-state parameters change as a function of the order of substrates addition to the TR-containing solution. In particular, when the reaction is carried out by adding NADPH to a solution containing the enzyme and trypanothione, the KM for NADPH decreases six times compared to the value obtained by adding TS2 as last reagent to start the reaction (1.9 vs. 12 μM). More importantly, we demonstrate that TR is able to catalyze the oxidation of NADPH also in the absence of trypanothione. Thus, TR catalyzes the reduction of O2 to water through the sequential formation of C(4a)-(hydro)peroxyflavin and sulfenic acid intermediates. This NADPH:O2 oxidoreductase activity is shared by ''Saccharomyces cerevisiae'' glutathione reductase (GR).CONCLUSIONS:TR and GR, in the absence of their physiological substrates, may catalyze the electron transfer reaction from NADPH to molecular oxygen to yield water.GENERAL SIGNIFICANCE:TR and GR are promiscuous enzymes.d water. GENERAL SIGNIFICANCE: TR and GR are promiscuous enzymes.)
Montaigne 2014 Circulation + (BACKGROUND: -Obesity and diabetes mellitus … BACKGROUND:-Obesity and diabetes mellitus (DM) are independently associated with the development of heart failure. In this study, we determined the respective effects of obesity, insulin resistance and DM on intrinsic contraction and mitochondrial function of the human myocardium before the onset of cardiomyopathy.METHODS AND RESULTS:-Right atrial myocardium was obtained from 141 consecutive patients, presenting no sign of cardiomyopathy. We investigated (i) ex vivo isometric contraction (ii) mitochondrial respiration and calcium retention capacity (iii) respiratory chain complex activities and oxidative stress status. DM was associated with a pronounced impairment of intrinsic contraction, mitochondrial dysfunction and increased myocardial oxidative stress, irrespective of weight status. By contrast, obesity was associated with less pronounced contractile dysfunction without any significant perturbation of mitochondrial function or oxidative stress status. Tested as continuous variables, glycated haemoglobin (HbA1C), but neither body mass index nor the insulin resistance index HOMA-IR, was independently associated with cardiac mitochondrial function. Furthermore, DM was associated with cardiac mitochondrial network fragmentation and significant decreased expression of the mitochondrial fusion related protein MFN1. Myocardial MFN1 content was inversely proportional to HbA1C.CONCLUSIONS:-Worsening of intrinsic myocardial contraction in the transition from obesity to DM is likely related to worsening of cardiac mitochondrial function, since impaired mitochondrial function and dynamics, as well as contractile dysfunction are observed in diabetic patients but not in "metabolically healthy" obese patients at early stage in insulin resistance.ents at early stage in insulin resistance.)
Syrjanen 2015 Front Zool + (BACKGROUND: Carbonic anhydrases (CAs, EC 4 … BACKGROUND:Carbonic anhydrases (CAs, EC 4.2.1.1) are ubiquitous enzymes that catalyze the reversible hydration reaction of carbon dioxide. CAs are present as six structurally divergent enzyme families: α, β, γ, δ, ζ and η. β-CAs have a wide distribution across different species including invertebrates. Previously, we showed that Drosophila melanogaster β-CA is a highly active mitochondrial enzyme. In this study, we investigated the function of Drosophila β-CA by silencing the expression of the β-CA gene using UAS/GAL4-based RNA interference (RNAi) in Drosophila in vivo.RESULTS:Crossing β-CA RNAi lines over ubiquitous Actin driver flies did not produce any viable progeny, indicating that β-CA expression is required for fly development. RNAi silencing of β-CA ubiquitously in adult flies did not affect their survival rate or function of mitochondrial electron transport chain. Importantly, β-CA RNAi led to impaired reproduction. All β-CA knockdown females were sterile, and produced few or no eggs. Whole ovaries of knockdown females looked normal but upon cadherin staining, there was an apparent functional defect in migration of border cells, which are considered essential for normal fertilization.CONCLUSIONS:These results indicate that although Drosophila β-CA is dispensable for survival of adult flies, it is essential for female fertility.ies, it is essential for female fertility.)
Jackson 2014 J Med Genet + (BACKGROUND: Defects of the mitochondrial r … BACKGROUND:Defects of the mitochondrial respiratory chain complex II (succinate dehydrogenase (SDH) complex) are extremely rare. Of the four nuclear encoded proteins composing complex II, only mutations in the 70 kDa flavoprotein (SDHA) and the recently identified complex II assembly factor (SDHAF1) have been found to be causative for mitochondrial respiratory chain diseases. Mutations in the other three subunits (SDHB, SDHC, SDHD) and the second assembly factor (SDHAF2) have so far only been associated with hereditary paragangliomas and phaeochromocytomas. Recessive germline mutations in SDHB have recently been associated with complex II deficiency and leukodystrophy in one patient.METHODS AND RESULTS:We present the clinical and molecular investigations of the first patient with biochemical evidence of a severe isolated complex II deficiency due to compound heterozygous SDHD gene mutations. The patient presented with early progressive encephalomyopathy due to compound heterozygous p.E69 K and p.*164Lext*3 SDHD mutations. Native polyacrylamide gel electrophoresis and western blotting demonstrated an impaired complex II assembly. Complementation of a patient cell line additionally supported the pathogenicity of the novel identified mutations in SDHD.CONCLUSIONS:This report describes the first case of isolated complex II deficiency due to recessive SDHD germline mutations. We therefore recommend screening for all SDH genes in isolated complex II deficiencies. It further emphasises the importance of appropriate genetic counselling to the family with regard to SDHD mutations and their role in tumorigenesis.mutations and their role in tumorigenesis.)
Errea 2015 J Neuroinflammation + (BACKGROUND: In brain inflammatory diseases … BACKGROUND:In brain inflammatory diseases, axonal damage is one of the most critical steps in the cascade that leads to permanent disability. Thus, identifying the initial events triggered by inflammation or oxidative stress that provoke axonal damage is critical for the development of neuroprotective therapies. Energy depletion due to mitochondrial dysfunction has been postulated as an important step in the damage of axons. This prompted us to study the effects of acute inflammation and oxidative stress on the morphology, transport, and function of mitochondria in axons.METHODS:Mouse cerebellar slice cultures were challenged with either lipopolysaccharide (LPS) or hydrogen peroxide (H2O2) ex vivo for 24 h. Axonal mitochondrial morphology was evaluated by transmission electron microscopy (TEM) and mitochondrial transportation by time-lapse imaging. In addition, mitochondrial function in the cerebellar slice cultures was analyzed through high-resolution respirometry assays and quantification of adenosine triphosphate (ATP) production.RESULTS:Both conditions promoted an increase in the size and complexity of axonal mitochondria evident in electron microscopy images, suggesting a compensatory response. Such compensation was reflected at the tissue level as increased respiratory activity of complexes I and IV and as a transient increase in ATP production in response to acute inflammation. Notably, time-lapse microscopy indicated that mitochondrial transport (mean velocity) was severely impaired in axons, increasing the proportion of stationary mitochondria in axons after LPS challenge. Indeed, the two challenges used produced different effects: inflammation mostly reducing retrograde transport and oxidative stress slightly enhancing retrograde transportation.CONCLUSIONS:Neuroinflammation acutely impairs axonal mitochondrial transportation, which would promote an inappropriate delivery of energy throughout axons and, by this way, contribute to axonal damage. Thus, preserving axonal mitochondrial transport might represent a promising avenue to exploit as a therapeutic target for neuroprotection in brain inflammatory diseases like multiple sclerosis.ammatory diseases like multiple sclerosis.)
Vijgen 2013 Surg Obes Relat Dis + (BACKGROUND: Obesity and type 2 diabetes ar … BACKGROUND:Obesity and type 2 diabetes are associated with impaired skeletal muscle mitochondrial metabolism. As an intrinsic characteristic of an individual, skeletal muscle mitochondrial dysfunction could be a risk factor for weight gain and obesity-associated co-morbidities, such as type 2 diabetes. On the other hand, impaired skeletal muscle metabolism could be a consequence of obesity. We hypothesize that marked weight loss after bariatric surgery recovers skeletal muscle mitochondrial function.METHODS:Skeletal muscle mitochondrial function as assessed by high-resolution respirometry was measured in 8 morbidly obese patients (body mass index [BMI], 41.3±4.7 kg/m2; body fat, 48.3%±5.2%) before and 1 year after bariatric surgery (mean weight loss: 35.0±8.6 kg). The results were compared with a lean (BMI 22.8±1.1 kg/m2; body fat, 15.6%±4.7%) and obese (BMI 33.5±4.2 kg/m2; body fat, 34.1%±6.3%) control group.RESULTS:Before surgery, adenosine diphosphate (ADP)-stimulated (state 3) respiration on glutamate/succinate was decreased compared with lean patients (9.5±2.4 versus 15.6±4.4 O2 flux/mtDNA; P<.05). One year after surgery, mitochondrial function was comparable to that of lean controls (after weight loss, 12.3±5.5; lean, 15.6±4.4 O2 flux/mtDNA). In addition, we observed an increased state 3 respiration on a lipid substrate after weight loss (10.0±3.2 versus 14.0±6.6 O2 flux/mtDNA; P< .05).CONCLUSIONS:We conclude that impaired skeletal muscle mitochondrial function is a consequence of obesity that recovers after marked weight loss. obesity that recovers after marked weight loss.)
Leo 2017 Front Zool + (BACKGROUND: Ocean acidification and warmin … BACKGROUND:Ocean acidification and warming are happening fast in the Arctic but little is known about the effects of ocean acidification and warming on the physiological performance and survival of Arctic fish.RESULTS:In this study we investigated the metabolic background of performance through analyses of cardiac mitochondrial function in response to control and elevated water temperatures and PCO2 of two gadoid fish species, Polar cod (Boreogadus saida), an endemic Arctic species, and Atlantic cod (Gadus morhua), which is a temperate to cold eurytherm and currently expanding into Arctic waters in the wake of ocean warming. We studied their responses to the above-mentioned drivers and their acclimation potential through analysing the cardiac mitochondrial function in permeabilised cardiac muscle fibres after 4 months of incubation at different temperatures (Polar cod: 0, 3, 6, 8 °C and Atlantic cod: 3, 8, 12, 16 °C), combined with exposure to present (400μatm) and year 2100 (1170μatm) levels of CO2. OXPHOS, proton leak and ATP production efficiency in Polar cod were similar in the groups acclimated at 400μatm and 1170μatm of CO2, while incubation at 8 °C evoked increased proton leak resulting in decreased ATP production efficiency and decreased Complex IV capacity. In contrast, OXPHOS of Atlantic cod increased with temperature without compromising the ATP production efficiency, whereas the combination of high temperature and high PCO2 depressed OXPHOS and ATP production efficiency.CONCLUSIONS:Polar cod mitochondrial efficiency decreased at 8 °C while Atlantic cod mitochondria were more resilient to elevated temperature; however, this resilience was constrained by high PCO2. In line with its lower habitat temperature and higher degree of stenothermy, Polar cod has a lower acclimation potential to warming than Atlantic cod.on potential to warming than Atlantic cod.)
Bosy-Westphal 2004 Int J Obes Relat Metab Disord + (BACKGROUND: In normal-weight subjects, r … BACKGROUND: In normal-weight subjects, resting energy expenditure (REE) can be accurately calculated from organ and tissue masses applying constant organ-specific metabolic rates. This approach allows a precise correction for between-subjects variation in REE, explained by body composition. Since a decrease in organ metabolic rate with increasing organ mass has been deduced from interspecies comparison including human studies, the validity of the organ- and tissue-specific REE calculation remains to be proved over a wider range of fat-free mass (FFM).DESIGN: In a cross-sectional study on 57 healthy adults (35 females and 22 males, 19-43 y; 14 underweight, 25 intermediate weight and 18 obese), magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA) were used to assess the masses of brain, internal organs, skeletal muscle (MM), bone and adipose tissue. REE was measured by indirect calorimetry (REEm) and calculated from detailed organ size determination by MRI and DXA (REEc1), or in a simplified approach exclusively from DXA (REEc2).RESULTS: We found a high agreement between REEm and REEc1 over the whole range of FFM (28-86 kg). REE prediction errors were -17 +/- 505, -145 +/- 514 and -141 +/- 1058 kJ/day in intermediate weight, underweight and obese subjects, respectively (n.s.). Regressing REEm on FFM resulted in a significant positive intercept of 1.6 MJ/day that could be reduced to 0.5 MJ/day by adjusting FFM for the proportion of MM/organ mass. In a multiple regression analysis, MM and liver mass explained 81% of the variance in REEm. DXA-derived REE prediction showed a good agreement with measured values (mean values for REEm and REEc2 were 5.72 +/- 1.87 and 5.82 +/- 1.51 MJ/day; difference n.s.).CONCLUSION: Detailed analysis of metabolically active components of FFM allows REE prediction over a wide range of FFM. The data provide indirect evidence for a view that, for practical purposes within humans, the specific metabolic rate is constant with increasing organ mass. Nonlinearity of REE on FFM was partly explained by FFM composition. A simplified REE prediction algorithm from regional DXA measurements has to be validated in future studies.nts has to be validated in future studies.)
Haugen 2003 Am J Clin Nutr + (BACKGROUND: The necessity of a 12-h fast … BACKGROUND: The necessity of a 12-h fast before resting metabolic rate (RMR) is measured is often a barrier to measuring RMR.OBJECTIVE: We compared RMR measurements obtained in the morning and afternoon and across repeated days to elucidate the magnitude and sources of variability.DESIGN: Healthy men (n = 12) and women (n = 25) aged 21-67 y, with body mass indexes (in kg/m(2)) ranging from 17 to 34 and body fat ranging from 6% to 54%, completed 4 RMR measurements. RMR measurements were made in the morning (after a 12-h fast and 12 h postexercise) and in the afternoon (after a 4-h fast and 12 h postexercise) on 2 separate days with the ventilated-hood technique. Body composition was assessed by dual-energy X-ray absorptiometry.RESULTS: Mean (+/- SE) afternoon RMR was significantly higher than morning RMR on both visit 1 (1593.5 +/- 35.6 compared with 1508.0 +/- 31.5 kcal/d; P = 0.001) and visit 2 (1602 +/- 29.3 compared with 1511.4 +/- 35.9 kcal/d; P = 0.001). The 2 morning measurements (r = 0.93) and the 2 afternoon measurements (r = 0.93) were highly correlated, and no significant differences between measurements were observed. The mean difference between the morning and afternoon measurements was 99.0 +/- 35.8 kcal/d (6%).CONCLUSIONS: Repeated morning and evening measurements of RMR were stable and highly correlated. Day-to-day measurements of RMR were not significantly different. RMR measured in the afternoon after a 4-h fast and exercise was approximately 100 kcal/d higher than RMR measured in the morning.d higher than RMR measured in the morning.)
Sabia 2009 Am J Clin Nutr + (BACKGROUND: The extent to which cognition … BACKGROUND: The extent to which cognition in late midlife is influenced by lifetime obesity is unclear.OBJECTIVE: We examined the association between body mass index (BMI) over the adult life course and cognition in late midlife and assessed the cumulative effects of obesity and underweight.DESIGN: Data from the Whitehall II Study were examined. BMI at 25 y (early adulthood) was self-reported at phase 1 and was measured in early midlife (mean age = 44 y; phase 1) and in late midlife (mean age = 61 y; phase 7). Cognition (''n'' = 5131) was assessed in late midlife (phase 7) by using the Mini-Mental State Examination and tests of memory and executive function, all of which were standardized to ''T'' scores (mean +/- SD: 50 +/- 10).RESULTS: Both underweight and obesity were associated with lower cognition in late midlife and with early adulthood, early midlife, and late midlife measures of BMI. Being obese at 2 or 3 occasions was associated with lower Mini-Mental State Examination scores and scores of memory and executive function in analyses adjusted for age, sex, and education [difference (95% CI) in mean ''T'' scores compared with normal-weight group: -1.51 (-2.77, -0.25), -1.27 (-2.46, -0.07), and -1.35 (-2.45, -0.24), respectively]. Participants who were underweight at > or =2 occasions from early adulthood to late midlife had lower executive function [difference (95% CI) in mean ''T'' score: -4.57 (-6.94, -2.20)]. A large increase in BMI from early to late midlife was associated with lower executive function.CONCLUSIONS: Long-term obesity and long-term underweight in adulthood are associated with lower cognitive scores in late midlife. Public health messages should promote a healthy weight at all ages. should promote a healthy weight at all ages.)
Pon 2011 Malar J + (BACKGROUND: ''Anopheles stephensi'' mitoch … BACKGROUND: ''Anopheles stephensi'' mitochondrial malic enzyme (ME) emerged as having a relevant role in the provision of pyruvate for the Krebs' cycle because inhibition of this enzyme results in the complete abrogation of oxygen uptake by mitochondria. Therefore, the identification of ME in mitochondria from immortalized A. stephensi (ASE) cells and the investigation of the stereoselectivity of malate analogues are relevant in understanding the physiological role of ME in cells of this important malaria parasite vector and its potential as a possible novel target for insecticide development.METHODS: To characterize the mitochondrial ME from immortalized ASE cells (Mos. 43; ASE), mass spectrometry analyses of trypsin fragments of ME, genomic sequence analysis and biochemical assays were performed to identify the enzyme and evaluate its activity in terms of cofactor dependency and inhibitor preference.RESULTS: The encoding gene sequence and primary sequences of several peptides from mitochondrial ME were found to be highly homologous to the mitochondrial ME from Anopheles gambiae (98%) and 59% homologous to the mitochondrial NADP+-dependent ME isoform from Homo sapiens. Measurements of ME activity in mosquito mitochondria isolated from ASE cells showed that (i) Vmax with NAD+ was 3-fold higher than that with NADP+, (ii) addition of Mg2+ or Mn2+ increased the Vmax by 9- to 21-fold, with Mn2+ 2.3-fold more effective than Mg2+, (iii) succinate and fumarate increased the activity by 2- and 5-fold, respectively, at sub-saturating concentrations of malate, (iv) among the analogs of L-malate tested as inhibitors of the NAD+-dependent ME catalyzed reaction, small (2- to 3-carbons) organic diacids carrying a 2-hydroxyl/keto group behaved as the most potent inhibitors of ME activity (e.g., oxaloacetate, tartronic acid and oxalate).CONCLUSIONS: The biochemical characterization of Anopheles stephensi ME is of critical relevance given its important role in bioenergetics, suggesting that it is a suitable target for insecticide development.itable target for insecticide development.)
Ejarque 2019 Int J Obes (Lond) + (BACKGROUND: A functional population of adi … BACKGROUND: A functional population of adipocyte precursors, termed adipose-derived stromal/stem cells (ASCs), is crucial for proper adipose tissue (AT) expansion, lipid handling, and prevention of lipotoxicity in response to chronic positive energy balance. We previously showed that obese human subjects contain a dysfunctional pool of ASCs. Elucidation of the mechanisms underlying abnormal ASC function might lead to therapeutic interventions for prevention of lipotoxicity by improving the adipogenic capacity of ASCs.METHODS: Using epigenome-wide association studies, we explored the impact of obesity on the methylation signature of human ASCs and their differentiated counterparts. Mitochondrial phenotyping of lean and obese ASCs was performed. TBX15 loss- and gain-of-function experiments were carried out and western blotting and electron microscopy studies of mitochondria were performed in white AT biopsies from lean and obese individuals.RESULTS: We found that DNA methylation in adipocyte precursors is significantly modified by the obese environment, and adipogenesis, inflammation, and immunosuppression were the most affected pathways. Also, we identified TBX15 as one of the most differentially hypomethylated genes in obese ASCs, and genetic experiments revealed that TBX15 is a regulator of mitochondrial mass in obese adipocytes. Accordingly, morphological analysis of AT from obese subjects showed an alteration of the mitochondrial network, with changes in mitochondrial shape and number.CONCLUSIONS: We identified a DNA methylation signature in adipocyte precursors associated with obesity, which has a significant impact on the metabolic phenotype of mature adipocytes. metabolic phenotype of mature adipocytes.)
Heymsfield 2007 Am J Clin Nutr + (BACKGROUND: Although Quetelet first report … BACKGROUND: Although Quetelet first reported in 1835 that adult weight scales to the square of stature, limited or no information is available on how anatomical body compartments, including adipose tissue (AT), scale to height.OBJECTIVE: We examined the critical underlying assumptions of adiposity-body mass index (BMI) relations and extended these analyses to major anatomical compartments: skeletal muscle (SM), bone, residual mass, weight (AT+SM+bone), AT-free mass, and organs (liver, brain).DESIGN: This was a cross-sectional analysis of 2 body-composition databases: one including magnetic resonance imaging and dual-energy X-ray absorptiometry (DXA) estimates of evaluated components in adults (total ''N''=411; organs=76) and the other a larger DXA database (''N''=1346) that included related estimates of fat, fat-free mass, and bone mineral mass.RESULTS: Weight, primary lean components (SM, residual mass, AT-free mass, and fat-free mass), and liver scaled to height with powers of approximately 2 (all ''P''<0.001); bone and bone mineral mass scaled to height with powers >2 (2.31-2.48), and the fraction of weight as bone mineral mass was significantly (''P''<0.001) correlated with height in women. AT scaled weakly to height with powers of approximately 2, and adiposity was independent of height. Brain mass scaled to height with a power of 0.83 (''P''=0.04) in men and nonsignificantly in women; the fraction of weight as brain was inversely related to height in women (''P''=0.002).CONCLUSIONS: These observations suggest that short and tall subjects with equivalent BMIs have similar but not identical body composition, provide new insights into earlier BMI-related observations and thus establish a foundation for height-normalized indexes, and create an analytic framework for future studies.nd create an analytic framework for future studies.)
Morse 2012 J Infect Dis + (BACKGROUND: Although human immunodeficienc … BACKGROUND: Although human immunodeficiency virus (HIV) infection and antiretroviral therapy (ART) affect mitochondrial DNA (mtDNA) content and function, comprehensive evaluations of their effects on mitochondria in muscle, adipose tissue, and blood cells are limited.METHODS: Mitochondrial DNA quantification, mitochondrial genome sequencing, and gene expression analysis were performed on muscle, adipose tissue, and peripheral blood mononuclear cell (PBMC) samples from untreated HIV-positive patients, HIV-positive patients receiving nucleoside reverse transcriptase inhibitor (NRTI)-based ART, and HIV-negative controls.RESULTS: The adipose tissue mtDNA/nuclear DNA (nDNA) ratio was increased in untreated HIV-infected patients (ratio, 353) and decreased in those receiving ART (ratio, 162) compared with controls (ratio, 255; P < .05 for both comparisons); the difference between the 2 HIV-infected groups was also significant (P = .002). In HIV-infected participants, mtDNA/nDNA in adipose tissue correlated with the level of activation (CD38+ /HLA-DR+) for CD4+ and CD8+ lymphocytes. No significant differences in mtDNA content were noted in muscle or PMBCs among groups. Exploratory DNA microarray analysis identified differential gene expression between patient groups, including a subset of adipose tissue genes.CONCLUSIONS: HIV infection and ART have opposing effects on mtDNA content in adipose tissue; immune activation may mediate the effects of HIV, whereas NRTIs likely mediate the effects of ART.reas NRTIs likely mediate the effects of ART.)
Gallagher 2000 Am J Clin Nutr + (BACKGROUND: Although international interes … BACKGROUND: Although international interest in classifying subject health status according to adiposity is increasing, no accepted published ranges of percentage body fat currently exist. Empirically identified limits, population percentiles, and z scores have all been suggested as means of setting percentage body fat guidelines, although each has major limitations.OBJECTIVE: The aim of this study was to examine a potential new approach for developing percentage body fat ranges. The approach taken was to link healthy body mass index (BMI; in kg/m(2)) guidelines established by the National Institutes of Health and the World Health Organization with predicted percentage body fat.DESIGN: Body fat was measured in subjects from 3 ethnic groups (white, African American, and Asian) who were screened and evaluated at 3 universities [Cambridge (United Kingdom), Columbia (United States), and Jikei (Japan)] with use of reference body-composition methods [4-compartment model (4C) at 2 laboratories and dual-energy X-ray absorptiometry (DXA) at all 3 laboratories]. Percentage body fat prediction equations were developed based on BMI and other independent variables.RESULTS: A convenient sample of 1626 adults with BMIs < or =35 was evaluated. Independent percentage body fat predictor variables in multiple regression models included 1/BMI, sex, age, and ethnic group (''R'': values from 0.74 to 0.92 and SEEs from 2.8 to 5.4 % fat). The prediction formulas were then used to prepare provisional healthy percentage body fat ranges based on published BMI limits for underweight (<18.5), overweight (> or =25), and obesity (> or =30).CONCLUSION: This proposed approach and initial findings provide the groundwork and stimulus for establishing international healthy body fat ranges.or establishing international healthy body fat ranges.)
Bredholt T 2009 Mol Cancer + (BACKGROUND: An organic extract of the recr … BACKGROUND: An organic extract of the recreational herb khat (''Catha edulis'' Forsk.) triggers cell death in various leukemia cell lines ''in vitro''. The chemotherapeutics camptothecin, a plant alkaloid topoisomerase I inhibitor, was tested side-by-side with khat in a panel of acute myeloid leukemia cell lines to elucidate mechanisms of toxicity.RESULTS: Khat had a profound effect on MOLM-13 cells inducing mitochondrial damage, chromatin margination and morphological features of autophagy. The effects of khat on mitochondrial ultrastructure in MOLM-13 correlated with strongly impaired routine respiration, an effect neither found in the khat-resistant MV-4-11 cells nor in camptothecin treated cells. Enforced expression of anti-apoptotic Bcl-2 protein provided protection against camptothecin-induced cell death and partly against khat toxicity. Khat-induced cell death in MOLM-13 cells included reduced levels of anti-apoptotic Mcl-1 protein, while both khat and camptothecin induced c-FLIPL cleavage and procaspase-8 activation.CONCLUSION: Khat activated a distinct cell death pathway in sensitive leukemic cells as compared to camptothecin, involving mitochondrial damage and morphological features of autophagy. This suggests that khat should be further explored in the search for novel experimental therapeutics.earch for novel experimental therapeutics.)
Heymsfield 2014 Am J Clin Nutr + (BACKGROUND: Body mass index (BMI) is formu … BACKGROUND: Body mass index (BMI) is formulated on the assumption that body weight (BW) scales to height with a power of 2 (BW∝height(2)), independent of sex and race-ethnicity. Powers differing from 2 are observed in studies of selected samples, thus raising the question if BMI is a generalizable metric that makes BW independent of height across populations.OBJECTIVES: The objectives were to test the hypothesis that adult BW scales to height with a power of 2 independent of sex and race-ethnicity and to advance an understanding of BMI as a measure of shape by extending allometric analyses to waist circumference (WC).DESIGN: We conducted cross-sectional subject evaluations, including body composition, from the NHANES and the Korean NHANES (KNHANES). Variations of the allometric model (Y = αX(β)) were used to establish height scaling powers (β ± SE) across non-Hispanic white and black, Mexican American, and Korean men and women.RESULTS: Exploratory analyses in population samples established age and adiposity as important independent determinants of height scaling powers (i.e., β). After age and adiposity in the next series of analyses were controlled for, BW scaling powers were nonsignificantly different between race/ethnic groups within each sex group; WC findings were similar in women, whereas small but significant between-race differences were observed in the men. Sex differences in β values were nonsignificant except for BW in non-Hispanic blacks and WC in Koreans (''P'' < 0.05). Nationally representative powers for BW were (NHANES/KNHANES) 2.12 ± 0.05/2.11 ± 0.06 for men and 2.02 ± 0.04/1.99 ± 0.06 for women and for WC were 0.66 ± 0.03/0.67 ± 0.05 for men and 0.61 ± 0.04/0.56 ± 0.05 for women.CONCLUSIONS: Adult BW scales to height with a power of ∼2 across the 8 sex and race/ethnic groups, an observation that makes BMI a generalizable height-independent measure of shape across most populations. WC also follows generalizable scaling rules, a finding that has implications for defining body shape in populations who differ in stature.y shape in populations who differ in stature.)
Romero-Corral 2008 Int J Obes (Lond) + (BACKGROUND: Body mass index (BMI) is the m … BACKGROUND: Body mass index (BMI) is the most widely used measure to diagnose obesity. However, the accuracy of BMI in detecting excess body adiposity in the adult general population is largely unknown.METHODS: A cross-sectional design of 13 601 subjects (age 20-79.9 years; 49 % men) from the Third National Health and Nutrition Examination Survey. Bioelectrical impedance analysis was used to estimate body fat percent (BF%). We assessed the diagnostic performance of BMI using the World Health Organization reference standard for obesity of BF%>25 % in men and>35 % in women. We tested the correlation between BMI and both BF% and lean mass by sex and age groups adjusted for race.RESULTS: BMI-defined obesity (> or =30 kg m(-2)) was present in 19.1 % of men and 24.7 % of women, while BF%-defined obesity was present in 43.9 % of men and 52.3 % of women. A BMI> or =30 had a high specificity (men=95 %, 95 % confidence interval (CI), 94-96 and women=99 %, 95 % CI, 98-100), but a poor sensitivity (men=36 %, 95 % CI, 35-37 and women=49 %, 95 % CI, 48-50) to detect BF%-defined obesity. The diagnostic performance of BMI diminished as age increased. In men, BMI had a better correlation with lean mass than with BF%, while in women BMI correlated better with BF% than with lean mass. However, in the intermediate range of BMI (25-29.9 kg m(-2)), BMI failed to discriminate between BF% and lean mass in both sexes.CONCLUSIONS: The accuracy of BMI in diagnosing obesity is limited, particularly for individuals in the intermediate BMI ranges, in men and in the elderly. A BMI cutoff of> or =30 kg m(-2) has good specificity but misses more than half of people with excess fat. These results may help to explain the unexpected better survival in overweight/mild obese patients.pected better survival in overweight/mild obese patients.)
Hood 2019 Nutr Diabetes + (BACKGROUND: Body mass index (BMI) represen … BACKGROUND: Body mass index (BMI) represents a normalization of weight to height and is used to classify adiposity. While the capacity of BMI as an adiposity index has been experimentally validated in Caucasians, but there has been little testing Asian populations.METHODS: To determine whether weight scales to height squared in Asian Indians across the general population and in Asian Indian tribes an allometric analysis on the power law model, ''W'' =''αHβ'', where ''W'' is weight (kg) and ''H'' is height (m) was performed on cross-sectional weight and height data from India (''N'' = 43,880) collected through the Anthropological Survey of India. The database contained males 18-84 years of age spanning 161 districts of 14 states and including 33 different tribes (''N'' = 5,549). Models were developed that were unadjusted and adjusted for tribe membership. The Korean National Health and Nutrition Examination Survey (KNHANES) was used to compare to height-weight data from the Anthropological Survey of India and to calculate BMI thresholds for obesity status using a receiver operating characteristic.RESULTS: The unadjusted power was ''β'' = 2.08 (s = 0.02). The power for the general population (non-tribal) was ''β'' = 2.11 (s = 0.02). Powers when adjusted for tribe ranged from 1.87 to 2.35 with 24 of the 33 tribes resulting in statistically significant (''p'' < 0.05) differences in powers from the general population. The coefficients of the adjusted terms ranged from -0.22 to 0.26 and therefore the scaling exponent does not deviate far from 2. Thresholds for BMI classification of overweight in the KNHANES database were BMI = 21 kg/m2 (AUC = 0.89) for males 18 kg/m2 (AUC = 0.97) for females. Obesity classification was calculated as BMI = 26 kg/m2 (AUC = 0.81) and 23 kg/m2 (AUC = 0.83) for females.CONCLUSIONS: Our study confirms that weight scales to height squared in Asian Indian males even after adjusting for tribe membership. We also demonstrate that optimal BMI thresholds are lower in a Korean population in comparison to currently used BMI thresholds. These results support the application of BMI in Asian populations with potentially lower thresholds.opulations with potentially lower thresholds.)
Sperrin 2016 J Public Health (Oxf) + (BACKGROUND: Body mass index (BMI) tends to … BACKGROUND: Body mass index (BMI) tends to be higher among shorter adults, especially women. The dependence of BMI-height correlation on age and calendar time may inform us about temporal determinants of BMI.METHODS: Series of cross-sectional surveys: Health Survey for England, 1992-2011. We study the Benn Index, which is the coefficient in a regression of log(weight) on log(height). This is adjusted for age, gender and calendar time, allowing for non-linear terms and interactions.RESULTS: By height quartile, mean BMI decreased with increasing height, more so in women than in men (P < 0.001). The decrease in mean BMI in the tallest compared with the shortest height quartile was 0.77 in men (95% CI 0.69, 0.86) and 1.98 in women (95% CI 1.89, 2.08). Regression analysis of log(weight) on log(height) revealed that the inverse association between BMI and height was more pronounced in older adults and stronger in women than in men, with little change over calendar time.CONCLUSIONS: Unlike early childhood, where taller children tend to have higher BMI, adults, especially women and older people, show an inverse BMI-height association. BMI is a heterogeneous measure of weight-for-height; height may be an important and complex determinant of BMI trajectory over the life course.© The Author 2015. Published by Oxford University Press on behalf of Faculty of Public Health. Press on behalf of Faculty of Public Health.)
Silbert 2016 J Alzheimers Dis + (BACKGROUND: Computer use is becoming a com … BACKGROUND: Computer use is becoming a common activity in the daily life of older individuals and declines over time in those with mild cognitive impairment (MCI). The relationship between daily computer use (DCU) and imaging markers of neurodegeneration is unknown.OBJECTIVE: The objective of this study was to examine the relationship between average DCU and volumetric markers of neurodegeneration on brain MRI.METHODS: Cognitively intact volunteers enrolled in the Intelligent Systems for Assessing Aging Change study underwent MRI. Total in-home computer use per day was calculated using mouse movement detection and averaged over a one-month period surrounding the MRI. Spearman's rank order correlation (univariate analysis) and linear regression models (multivariate analysis) examined hippocampal, gray matter (GM), white matter hyperintensity (WMH), and ventricular cerebral spinal fluid (vCSF) volumes in relation to DCU. A voxel-based morphometry analysis identified relationships between regional GM density and DCU.RESULTS: Twenty-seven cognitively intact participants used their computer for 51.3 minutes per day on average. Less DCU was associated with smaller hippocampal volumes (''r'' = 0.48, ''p'' = 0.01), but not total GM, WMH, or vCSF volumes. After adjusting for age, education, and gender, less DCU remained associated with smaller hippocampal volume (''p'' = 0.01). Voxel-wise analysis demonstrated that less daily computer use was associated with decreased GM density in the bilateral hippocampi and temporal lobes.CONCLUSIONS: Less daily computer use is associated with smaller brain volume in regions that are integral to memory function and known to be involved early with Alzheimer's pathology and conversion to dementia. Continuous monitoring of daily computer use may detect signs of preclinical neurodegeneration in older individuals at risk for dementia.in older individuals at risk for dementia.)
Pearson-Stuttard 2018 Lancet Diabetes Endocrinol + (BACKGROUND: Diabetes and high body-mass in … BACKGROUND: Diabetes and high body-mass index (BMI) are associated with increased risk of several cancers, and are increasing in prevalence in most countries. We estimated the cancer incidence attributable to diabetes and high BMI as individual risk factors and in combination, by country and sex.METHODS: We estimated population attributable fractions for 12 cancers by age and sex for 175 countries in 2012. We defined high BMI as a BMI greater than or equal to 25 kg/m2. We used comprehensive prevalence estimates of diabetes and BMI categories in 2002, assuming a 10-year lag between exposure to diabetes or high BMI and incidence of cancer, combined with relative risks from published estimates, to quantify contribution of diabetes and high BMI to site-specific cancers, individually and combined as independent risk factors and in a conservative scenario in which we assumed full overlap of risk of diabetes and high BMI. We then used GLOBOCAN cancer incidence data to estimate the number of cancer cases attributable to the two risk factors. We also estimated the number of cancer cases in 2012 that were attributable to increases in the prevalence of diabetes and high BMI from 1980 to 2002. All analyses were done at individual country level and grouped by region for reporting.FINDINGS: We estimated that 5·7 % of all incident cancers in 2012 were attributable to the combined effects of diabetes and high BMI as independent risk factors, corresponding to 804 100 new cases. 187 600 (24·5 %) of 766 000 cases of liver cancer and 121 700 (38·4 %) of 317 000 cases of endometrial cancer were attributable to these risk factors. In the conservative scenario, about 4·5 % (629 000 new cases) of all incident cancers assessed were attributable to diabetes and high BMI combined. Individually, high BMI (544 300 cases) was responsible for almost twice as many cancer cases as diabetes (293 300 cases). 25·8 % of diabetes-related cancers (equating to 75 600 new cases) and 31·9 % of high BMI-related cancers (174 040 new cases) were attributable to increases in the prevalence of these risk factors from 1980 to 2002.INTERPRETATION: A substantial number of cancer cases are attributable to diabetes and high BMI. As the prevalence of these cancer risk factors increases, clinical and public health efforts should focus on identifying optimal preventive and screening measures for whole populations and individual patients.FUNDING: NIHR and Wellcome Trust.Copyright © 2018 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license. Published by Elsevier Ltd. All rights reserved.Corrected and republished from: Worldwide burden of cancer attributable to diabetes and high body-mass index: a comparative risk assessment [Lancet Diabetes Endocrinol 2018]sessment [Lancet Diabetes Endocrinol 2018])
Cohen 2008 Am J Clin Nutr + (BACKGROUND: During the past 40 y, there ha … BACKGROUND: During the past 40 y, there has been a trend toward more eating away from home, increased food availability, the opportunity to order extra-large portion sizes, and general weight gain.OBJECTIVE: Because shorter people need fewer calories than taller people to maintain their weight, our goal was to determine whether the body mass index (BMI)-height relation has changed over time.DESIGN: Data are from 3581 nonpregnant women and 3091 men examined in the 1959-1962 National Health Examination Survey and 4651 nonpregnant women and 4691 men examined in the 2001-2004 National Health and Nutrition Examination Survey. We tested whether the relation between BMI and height has changed for men and women, after adjustment for other demographic changes.RESULTS: In the past, on average, shorter American men and women had significantly higher BMIs than taller people. However, taller people have been increasing their BMI during the past 40 y at a faster rate than shorter people.CONCLUSIONS: This study documents that the obesity epidemic has changed the height-BMI relation. The data cannot identify causal pathways, and there are numerous explanations. A plausible hypothesis is that changes in the food environment may have eliminated constraints on weight gain for taller people that existed in a more calorie-constrained environment.in a more calorie-constrained environment.)
Rhein 2010 PloS One + (BACKGROUND: Energy deficiency and mitochon … BACKGROUND: Energy deficiency and mitochondrial failure have been recognized as a prominent, early event in Alzheimer's disease (AD). Recently, we demonstrated that chronic exposure to amyloid-beta (Abeta) in human neuroblastoma cells over-expressing human wild-type amyloid precursor protein (APP) resulted in (i) activity changes of Complexes III and IV of the oxidative phosphorylation system (OXPHOS) and in (ii) a drop of ATP levels which may finally instigate loss of synapses and neuronal cell death in AD. Therefore, the aim of the present study was to investigate whether standardized Ginkgo biloba extract LI 1370 (GBE) is able to rescue Abeta-induced defects in energy metabolism.METHODOLOGY/PRINCIPAL FINDINGS: We used a high-resolution respiratory protocol to evaluate OXPHOS respiratory capacity under physiological condition in control (stably transfected with the empty vector) and APP cells after treatment with GBE. In addition, oxygen consumption of isolated mitochondria, activities of mitochondrial respiratory enzymes, ATP and reactive oxygen species (ROS) levels as well as mitochondrial membrane mass and mitochondrial DNA content were determined. We observed a general antioxidant effect of GBE leading to an increase of the coupling state of mitochondria as well as energy homeostasis and a reduction of ROS levels in control cells and in APP cells. GBE effect on OXPHOS was even preserved in mitochondria after isolation from treated cells. Moreover, these functional data were paralleled by an up-regulation of mitochondrial DNA. Improvement of the OXPHOS efficiency was stronger in APP cells than in control cells. In APP cells, the GBE-induced amelioration of oxygen consumption most likely arose from the modulation and respective normalization of the Abeta-induced disturbance in the activity of mitochondrial Complexes III and IV restoring impaired ATP levels possibly through decreasing Abeta and oxidative stress level.CONCLUSIONS/SIGNIFICANCE: Although the underlying molecular mechanisms of the mode of action of GBE remain to be determined, our study clearly highlights the beneficial effect of GBE on the cellular OXPHOS performance and restoration of Abeta-induced mitochondrial dysfunction.f Abeta-induced mitochondrial dysfunction.)
Ekelund 2016 Lancet + (BACKGROUND: High amounts of sedentary beha … BACKGROUND: High amounts of sedentary behaviour have been associated with increased risks of several chronic conditions and mortality. However, it is unclear whether physical activity attenuates or even eliminates the detrimental effects of prolonged sitting. We examined the associations of sedentary behaviour and physical activity with all-cause mortality.METHODS: We did a systematic review, searching six databases (PubMed, PsycINFO, Embase, Web of Science, Sport Discus, and Scopus) from database inception until October, 2015, for prospective cohort studies that had individual level exposure and outcome data, provided data on both daily sitting or TV-viewing time and physical activity, and reported effect estimates for all-cause mortality, cardiovascular disease mortality, or breast, colon, and colorectal cancer mortality. We included data from 16 studies, of which 14 were identified through a systematic review and two were additional unpublished studies where pertinent data were available. All study data were analysed according to a harmonised protocol, which categorised reported daily sitting time and TV-viewing time into four standardised groups each, and physical activity into quartiles (in metabolic equivalent of task [MET]-hours per week). We then combined data across all studies to analyse the association of daily sitting time and physical activity with all-cause mortality, and estimated summary hazard ratios using Cox regression. We repeated these analyses using TV-viewing time instead of daily sitting time.FINDINGS: Of the 16 studies included in the meta-analysis, 13 studies provided data on sitting time and all-cause mortality. These studies included 1 005 791 individuals who were followed up for 2-18·1 years, during which 84 609 (8·4%) died. Compared with the referent group (ie, those sitting <4 h/day and in the most active quartile [>35·5 MET-h per week]), mortality rates during follow-up were 12-59% higher in the two lowest quartiles of physical activity (from HR=1·12, 95% CI 1·08-1·16, for the second lowest quartile of physical activity [<16 MET-h per week] and sitting <4 h/day; to HR=1·59, 1·52-1·66, for the lowest quartile of physical activity [<2·5 MET-h per week] and sitting >8 h/day). Daily sitting time was not associated with increased all-cause mortality in those in the most active quartile of physical activity. Compared with the referent (<4 h of sitting per day and highest quartile of physical activity [>35·5 MET-h per week]), there was no increased risk of mortality during follow-up in those who sat for more than 8 h/day but who also reported >35·5 MET-h per week of activity (HR=1·04; 95% CI 0·99-1·10). By contrast, those who sat the least (<4 h/day) and were in the lowest activity quartile (<2·5 MET-h per week) had a significantly increased risk of dying during follow-up (HR=1·27, 95% CI 1·22-1·31). Six studies had data on TV-viewing time (N=465 450; 43 740 deaths). Watching TV for 3 h or more per day was associated with increased mortality regardless of physical activity, except in the most active quartile, where mortality was significantly increased only in people who watched TV for 5 h/day or more (HR=1·16, 1·05-1·28).sed only in people who watched TV for 5 h/day or more (HR=1·16, 1·05-1·28).)
Bienholz 2011 Abstract IOC65 + (BACKGROUND: Hypoxia/reoxygenation (H/R) of … BACKGROUND: Hypoxia/reoxygenation (H/R) of proximal tubules leads to persistent ATP depletion due to decreased mitochondrial membrane potential (MMP) resulting from nonesterified fatty acid (NEFA)-mediated uncoupling that is paradoxically accompanied by respiratory inhibition rather than the stimulation expected for uncoupled states.METHODS: Since NEFA have been reported to directly inhibit electron transport in some settings we assessed respiratory function in isolated, permeabilized rabbit tubules after H/R as a function of NEFA availability.RESULTS: Compared to respiration supported by the complex II-dependent substrate, succinate, which was highly uncoupled after H/R but relatively well preserved (ADP-stimulated respiration (S3) of permeabilized tubules 71.0±8.5% of normoxic control (NC)), respiration supported by complex I-dependent substrates that normally predominate in cells was also uncoupled, but S3 was reduced to 26.9±3.3% of NC, P < 0.001 vs. succinate, N=5. With complex I substrates, acutely lowering NEFA after permeabilization improved coupling but only minimally increased S3. In contrast, lowering NEFA during 60 min. of reoxygenation prior to permeabilization increased S3 supported by complex I substrates, but it remained lower (55.7±7.5% of NC) than with succinate after the same treatment, 80.0±4.8%, p < 0.02. MMP at the end of H/R was much lower with complex I substrates (30.7±9.2% NC) than with succinate (67.4±4.5%), P < 0.004. Lowering NEFA during 60 min. of reoxygenation strongly improved recovery and decreased the MMP difference between complex I substrates (73.3±5.1% of NC) and succinate (83.4±6.6%).CONCLUSION: The studies indicate that selectively impaired utilization of complex I substrates to support respiration after H/R promotes NEFA-induced deenergization and is only minimally improved by acutely removing NEFA. In the presence of NEFA, the higher efficiency of complex I substrates to support electron transport does not mitigate the impact of the impaired respiration on MMP. However, lowering NEFA within cells for 60 min. allows strong recovery of MMP despite persistence of some respiratory impairment.despite persistence of some respiratory impairment.)
Bonthuis 2013 PLOS ONE + (BACKGROUND: In children with either delaye … BACKGROUND: In children with either delayed or accelerated growth, expressing the body mass index (BMI) to chronological age might lead to invalid body composition estimates. Reference to height-age has been suggested for such populations; however its validity has not been demonstrated.METHODS: Anthropometric data of healthy children were obtained from the German KiGGS survey. We selected three samples with different height distributions representing short stature (mean height SDS: -1.6), normal stature (height SDS: 0), and tall stature (height SDS: +1.6), and compared BMI-for-age and BMI-for-height-age between these samples across the paediatric age range. Differences between samples were tested using Kruskal-Wallis one-way analysis of variance and permutation tests.RESULTS: At a given age, BMI was distributed towards lower values in short, and towards higher values in tall subjects as compared to a population with average height distribution. Expressing BMI to height-age eliminated these differences in boys with a short stature from 4 years to 14 years of age, in tall boys from 4 to 16 years, in short girls aged 2-10 years or tall girls aged 2-17 years.CONCLUSION: From late infancy to adolescent age, BMI distribution co-varies with height distribution and referencing to height-age appears appropriate within this age period. However, caution is needed when data about pubertal status are absent.hen data about pubertal status are absent.)
Tompuri 2015 Clin Physiol Funct Imaging + (BACKGROUND: In the exercise testing measur … BACKGROUND: In the exercise testing measures of cardiorespiratory fitness need to be scaled by body size or composition to enable comparison between individuals. Traditionally used weight-proportional measures are potentially confounded by body adiposity that hampers their interpretation and applicability in the clinical assessment of cardiorespiratory fitness.OBJECTIVE: We aimed to find the most appropriate measure of body size or composition for scaling of measures of cardiorespiratory fitness among children.METHODS: We assessed body weight and height, maximal workload (''W''max) and maximal oxygen uptake (''V''O2max) using cycle ergometer exercise test with respiratory gas analysis and body lean mass (LM) and fat mass (FM) by dual-energy X-ray absorptiometry and by bioimpedance analysis among 38 children. The data were analysed using Pearson's coefficients for correlation and stepwise linear regression models.RESULTS: Lean mass (''r'' > 0.54) and height (''r'' > 0.51) had stronger positive correlations with absolute ''W''max and ''V''O2max than weight (''r'' > 0.30) in girls and boys. None of the measures of body size or composition correlated with LM-proportional ''W''max or ''V''O2max in girls or boys. Only LM correlated positively with height-proportional ''W''max (''r'' = 0.65) and ''V''O2max (''r'' = 0.71) in boys. FM correlated negatively with weight-proportional ''W''max (''r'' < -0.58) and ''V''O2max (''r'' < -0.64) in girls and boys. FM was even stronger determinant of weight-proportional ''W''max (''β'' = -0.68) and ''V''O2max (''β'' = -0.61) than exercise performance in multivariate linear regression models.CONCLUSIONS: While assessing cardiorespiratory fitness, LM is the most appropriate measure of body size or composition for scaling of ''W''max and ''V''O2max, because scaling by body weight introduces confounding by body adiposity.ss, LM is the most appropriate measure of body size or composition for scaling of ''W''max and ''V''O2max, because scaling by body weight introduces confounding by body adiposity.)
Kuper 2014 BMC Public Health + (BACKGROUND: Indians may be particularly vu … BACKGROUND: Indians may be particularly vulnerable to cardiometabolic disease, potentially due to higher body fat for a given BMI, or a tendency towards depositing abdominal adiposity. The aim of the study is to assess whether different measures of the distribution of adiposity (abdominal versus whole body) or amount of adiposity (DXA versus traditional anthropometric) are better at predicting prevalent cardiometabolic risk markers in an Indian population.METHODS: Participants were recruited from the Indian Migration Study (IMS) and the Andhra Pradesh Children and Parent Study (APCAPS). Participants attended a clinic in Hyderabad, India, January 2009-December 2010. Adiposity was measured by conventional anthropometry (including weight, height, waist) and DXA scanning (whole body and abdominal). Blood samples were taken and assessed for fasting plasma glucose, insulin, cholesterol, and triglycerides and blood pressure was measured. Lifestyle data were collected by questionnaire.RESULTS: We invited 4 617 participants to the clinic (1 995 IMS; 2 622 APCAPS) and examined 918 from IMS (46 %) and 1 451 from APCAPS (55 %). There were strong and consistent relationships between adiposity and cardiometabolic risk factors. Cardiometabolic risk factors did not appear to be more strongly associated with DXA measures as opposed to BMI, or skinfold measures of body fat. There was some evidence that WHR was more closely related to diabetes than total body adiposity, but this was not apparent for the other measures of abdominal adiposity (DXA measures, waist circumference) or other cardiometablic risk factors.CONCLUSIONS: No strong evidence supports that DXA measures or abdominal measures of adiposity are better at predicting the prevalence of cardiometabolic risk factors in comparison to BMI.tabolic risk factors in comparison to BMI.)
Nouette-Gaulain 2009 Anesthesiology + (BACKGROUND: Local anesthetics offer the be … BACKGROUND: Local anesthetics offer the benefits of extended analgesia with greater patient satisfaction and faster rehabilitation compared with intravenous morphine. These benefits, however, can be offset by adverse iatrogenic muscle pain caused by bupivacaine. Here, the authors describe the mechanisms of local anesthetic-induced myotoxicity and a partial protective effect of recombinant human erythropoietin (rhEPO).METHODS: The authors developed a rat analgesia model with femoral nerve catheter and a cell culture model of human skeletal muscle myoblasts to study local anesthetic effects. Rats were randomly assigned to four different groups: daily intraperitoneal injection with 5,000 U/kg rhEPO or saline coupled to a perineural catheter injection with 1 ml/kg bupivacaine, 0.25%, or saline. In psoas rat muscle, oxygen consumption rates were measured using a Clark-type electrode in saponin-skinned fibers. Mitochondrial adenosine triphosphate synthesis rates were determined by bioluminescence. Enzymatic activity of mitochondrial respiratory chain complexes was measured on tissue homogenates using spectrophotometric procedures, and mitochondrial morphology was analyzed by transmission electron microscopy. In addition, the interaction between bupivacaine and rhEPO was investigated on human skeletal muscle myoblasts by fluorescence microscopy using mitotracker green and using the lipophilic cation JC-1.RESULTS: Bupivacaine caused impairment of mitochondrial structure and bioenergetics in rats. Human myoblasts treated with bupivacaine showed a dose-dependent decrease in mitochondrial membrane potential associated with unusual morphologies. Impairment of mitochondrial bioenergetics was prevented partially by the use of rhEPO coadministered with bupivacaine.CONCLUSIONS: The authors demonstrated a dose- and time-dependent protective effect of rhEPO against bupivacaine-induced myotoxicity in regional analgesia.induced myotoxicity in regional analgesia.)
Xu 1999 Structure + (BACKGROUND: Malic enzymes catalyze the oxi … BACKGROUND: Malic enzymes catalyze the oxidative decarboxylation of malate to pyruvate and CO2 with the concomitant reduction of NAD(P)+ to NAD(P)H. They are widely distributed in nature and have important biological functions. Human mitochondrial NAD(P)+-dependent malic enzyme (mNAD-ME) may have a crucial role in the metabolism of glutamine for energy production in rapidly dividing cells and tumors. Moreover, this isoform is unique among malic enzymes in that it is a cooperative enzyme, and its activity is controlled allosterically.RESULTS: The crystal structure of human mNAD-ME has been determined at 2.5 A resolution by the selenomethionyl multiwavelength anomalous diffraction method and refined to 2.1 A resolution. The structure of the monomer can be divided into four domains; the active site of the enzyme is located in a deep cleft at the interface between three of the domains. Three acidic residues (Glu255, Asp256 and Asp279) were identified as ligands for the divalent cation that is required for catalysis by malic enzymes.CONCLUSIONS: The structure reveals that malic enzymes belong to a new class of oxidative decarboxylases. The tetramer of the enzyme appears to be a dimer of dimers. The active site of each monomer is located far from the tetramer interface. The structure also shows the binding of a second NAD+ molecule in a pocket 35 A away from the active site. The natural ligand for this second binding site may be ATP, an allosteric inhibitor of the enzyme.TP, an allosteric inhibitor of the enzyme.)
Lucchinetti 2012 Anesthesiology + (BACKGROUND: Mesenchymal stem cells (MSC) a … BACKGROUND: Mesenchymal stem cells (MSC) are self-renewing clonal progenitor cells of nonhematopoietic tissues that exhibit a marked tropism to wounds and tumors. The authors' studies aimed at exploring how local anesthetics would affect MSC biology.METHODS: Proliferation, colony formation, ''in vitro'' wound healing, and bone differentiation assays of culture-expanded bone-marrow-derived murine MSC were performed in the presence of increasing concentrations of lidocaine, ropivacaine, and bupivacaine. Cytotoxicity was monitored by measuring lactate dehydrogenase activity and phosphatidylserine exposure/propidium iodide staining (early apoptotic cells/necrotic cells). Measurements of mitochondrial function in intact and permeabilized cells, transcriptional changes, and changes in nuclear factor κ-light-chain-enhancer of activated B cells signaling in MSC treated with ropivacaine were used to further characterize the biologic effects of local anesthetics on MSC.RESULTS: All local anesthetics reduced MSC proliferation at 100 μM, consistent with cell cycle delay or arrest at the G0/1-S phase transition. They increased lactate dehydrogenase release and the number of annexin V-positive MSC but not necrotic MSC. Colony formation was decreased, differentiation into osteoblasts impaired, and ''in vitro'' wound healing delayed. Mitochondrial respiration and adenosine 5'-triphosphate concentrations were reduced. Microarray analysis revealed significant expression changes in lysosomal genes and genes controlling sterol metabolism, indicating an impaired phospholipid metabolism in the lysosome. Multiple transcriptional programs related to cell differentiation, tumorigenesis, and metastasis were negatively affected by ropivacaine.CONCLUSIONS: The authors' studies demonstrate that local anesthetics significantly affect important aspects of MSC biology. These experiments provide novel rationales for the perioperative use of local anesthetics in patients with cancer but also highlight the potentially detrimental effects of local anesthetics on wound healing.cts of local anesthetics on wound healing.)
Gispert 2009 PLoS One + (BACKGROUND: Parkinson's disease (PD) is an … BACKGROUND: Parkinson's disease (PD) is an adult-onset movement disorder of largely unknown etiology. We have previously shown that loss-of-function mutations of the mitochondrial protein kinase PINK1 (PTEN induced putative kinase 1) cause the recessive PARK6 variant of PD.METHODOLOGY/PRINCIPAL FINDINGS: Now we generated a PINK1 deficient mouse and observed several novel phenotypes: A progressive reduction of weight and of locomotor activity selectively for spontaneous movements occurred at old age. As in PD, abnormal dopamine levels in the aged nigrostriatal projection accompanied the reduced movements. Possibly in line with the PARK6 syndrome but in contrast to sporadic PD, a reduced lifespan, dysfunction of brainstem and sympathetic nerves, visible aggregates of α-synuclein within Lewy bodies or nigrostriatal neurodegeneration were not present in aged PINK1-deficient mice. However, we demonstrate PINK1 mutant mice to exhibit a progressive reduction in mitochondrial preprotein import correlating with defects of core mitochondrial functions like ATP-generation and respiration. In contrast to the strong effect of PINK1 on mitochondrial dynamics in ''Drosophila melanogaster'' and in spite of reduced expression of fission factor ''Mtp18'', we show reduced fission and increased aggregation of mitochondria only under stress in PINK1-deficient mouse neurons.CONCLUSION: Thus, aging ''Pink1(-/-)'' mice show increasing mitochondrial dysfunction resulting in impaired neural activity similar to PD, in absence of overt neuronal death.to PD, in absence of overt neuronal death.)
Raji 2016 J Alzheimers Dis + (BACKGROUND: Physical activity (PA) can be … BACKGROUND: Physical activity (PA) can be neuroprotective and reduce the risk for Alzheimer's disease (AD). In assessing physical activity, caloric expenditure is a proxy marker reflecting the sum total of multiple physical activity types conducted by an individual.OBJECTIVE: To assess caloric expenditure, as a proxy marker of PA, as a predictive measure of gray matter (GM) volumes in the normal and cognitively impaired elderly persons.METHODS: All subjects in this study were recruited from the Institutional Review Board approved Cardiovascular Health Study (CHS), a multisite population-based longitudinal study in persons aged 65 and older. We analyzed a sub-sample of CHS participants 876 subjects (mean age 78.3, 57.5% F, 42.5% M) who had i) energy output assessed as kilocalories (kcal) per week using the standardized Minnesota Leisure-Time Activities questionnaire, ii) cognitive assessments for clinical classification of normal cognition, mild cognitive impairment (MCI), and AD, and iii) volumetric MR imaging of the brain. Voxel-based morphometry modeled the relationship between kcal/week and GM volumes while accounting for standard covariates including head size, age, sex, white matter hyperintensity lesions, MCI or AD status, and site. Multiple comparisons were controlled using a False Discovery Rate of 5 percent.RESULTS: Higher energy output, from a variety of physical activity types, was associated with larger GM volumes in frontal, temporal, and parietal lobes, as well as hippocampus, thalamus, and basal ganglia. High levels of caloric expenditure moderated neurodegeneration-associated volume loss in the precuneus, posterior cingulate, and cerebellar vermis.CONCLUSION: Increasing energy output from a variety of physical activities is related to larger gray matter volumes in the elderly, regardless of cognitive status.e elderly, regardless of cognitive status.)
Meyer 2010 Eur J Cardiovasc Prev Rehabil + (BACKGROUND: Population strategies to incre … BACKGROUND: Population strategies to increase physical activity are an essential part of cardiovascular disease prevention. However, little data exist on lifestyle interventions that are easy to integrate into everyday life such as using stairs instead of elevators at the workplace.DESIGN: Pre and postintervention study.METHODS: A 12-week promotional campaign for stair use consisting in posters and floor stickers at the point of choice between stairs and elevators at each hospital floor was organized in a university hospital building. In 77 selected employees with an inactive lifestyle, physical activity, aerobic fitness, anthropometrics, blood pressure, lipids, insulin sensitivity, and C-reactive protein were assessed at baseline, 12 weeks, and 6 months.RESULTS: During the intervention median daily number of ascended and descended one-story staircase units was 20.6/day (14.2-28.1) compared with 4.5/day (1.8-7.2) at baseline (''P''<0.001). At 12 weeks, estimated maximal aerobic capacity had increased by 9.2±15.1% (''P''<0.001) corresponding with approximately 1 MET. There were significant declines in waist circumference (-1.7±2.9%), weight (-0.7±2.6%), fat mass (-1.5±8.4%), diastolic blood pressure (-1.8±8.9%), and low-density lipoprotein cholesterol (-3.0±13.5%). At 6 months, the median daily number of ascended and descended one-story staircase units had decreased to 7.2 (3.5-14.0). Benefits on estimated maximal aerobic capacity (+5.9±12.2%, ''P''=0.001) and fat mass (-1.4±8.4%, ''P''=0.038) persisted.CONCLUSION: Encouraging stair use at work is effective for improving fitness, body composition, blood pressure, and lipid profile in asymptomatic individuals with an inactive lifestyle and thus may be a simple way to significantly reduce cardiovascular disease risk at the population level.iovascular disease risk at the population level.)
Grocott 2009 N Engl J Med + (BACKGROUND: The level of environmental hyp … BACKGROUND: The level of environmental hypobaric hypoxia that affects climbers at the summit of Mount Everest (8848 m [29,029 ft]) is close to the limit of tolerance by humans. We performed direct field measurements of arterial blood gases in climbers breathing ambient air on Mount Everest.METHODS: We obtained samples of arterial blood from 10 climbers during their ascent to and descent from the summit of Mount Everest. The partial pressures of arterial oxygen (PaO(2)) and carbon dioxide (PaCO(2)), pH, and hemoglobin and lactate concentrations were measured. The arterial oxygen saturation (SaO(2)), bicarbonate concentration, base excess, and alveolar-arterial oxygen difference were calculated.RESULTS: PaO(2) fell with increasing altitude, whereas SaO(2) was relatively stable. The hemoglobin concentration increased such that the oxygen content of arterial blood was maintained at or above sea-level values until the climbers reached an elevation of 7100 m (23,294 ft). In four samples taken at 8400 m (27,559 ft)--at which altitude the barometric pressure was 272 mm Hg (36.3 kPa)--the mean PaO(2) in subjects breathing ambient air was 24.6 mm Hg (3.28 kPa), with a range of 19.1 to 29.5 mm Hg (2.55 to 3.93 kPa). The mean PaCO(2) was 13.3 mm Hg (1.77 kPa), with a range of 10.3 to 15.7 mm Hg (1.37 to 2.09 kPa). At 8400 m, the mean arterial oxygen content was 26% lower than it was at 7100 m (145.8 ml per liter as compared with 197.1 ml per liter). The mean calculated alveolar-arterial oxygen difference was 5.4 mm Hg (0.72 kPa).CONCLUSIONS: The elevated alveolar-arterial oxygen difference that is seen in subjects who are in conditions of extreme hypoxia may represent a degree of subclinical high-altitude pulmonary edema or a functional limitation in pulmonary diffusion.ctional limitation in pulmonary diffusion.)
Ding 2016 Lancet + (BACKGROUND: The pandemic of physical inact … BACKGROUND: The pandemic of physical inactivity is associated with a range of chronic diseases and early deaths. Despite the well documented disease burden, the economic burden of physical inactivity remains unquantified at the global level. A better understanding of the economic burden could help to inform resource prioritisation and motivate efforts to increase levels of physical activity worldwide.METHODS: Direct health-care costs, productivity losses, and disability-adjusted life-years (DALYs) attributable to physical inactivity were estimated with standardised methods and the best data available for 142 countries, representing 93·2% of the world's population. Direct health-care costs and DALYs were estimated for coronary heart disease, stroke, type 2 diabetes, breast cancer, and colon cancer attributable to physical inactivity. Productivity losses were estimated with a friction cost approach for physical inactivity related mortality. Analyses were based on national physical inactivity prevalence from available countries, and adjusted population attributable fractions (PAFs) associated with physical inactivity for each disease outcome and all-cause mortality.FINDINGS: Conservatively estimated, physical inactivity cost health-care systems international $ (INT$) 53·8 billion worldwide in 2013, of which $31·2 billion was paid by the public sector, $12·9 billion by the private sector, and $9·7 billion by households. In addition, physical inactivity related deaths contribute to $13·7 billion in productivity losses, and physical inactivity was responsible for 13·4 million DALYs worldwide. High-income countries bear a larger proportion of economic burden (80·8% of health-care costs and 60·4% of indirect costs), whereas low-income and middle-income countries have a larger proportion of the disease burden (75·0% of DALYs). Sensitivity analyses based on less conservative assumptions led to much higher estimates.INTERPRETATION: In addition to morbidity and premature mortality, physical inactivity is responsible for a substantial economic burden. This paper provides further justification to prioritise promotion of regular physical activity worldwide as part of a comprehensive strategy to reduce non-communicable diseases.ategy to reduce non-communicable diseases.)
Sarti 2011 Biochim Biophys Acta + (BACKGROUND: The reactions between Complex … BACKGROUND: The reactions between Complex IV (cytochrome c oxidase, CcOX) and nitric oxide (NO) were described in the early 60's. The perception, however, that NO could be responsible for physiological or pathological effects, including those on mitochondria, lags behind the 80's, when the identity of the endothelial derived relaxing factor (EDRF) and NO synthesis by the NO synthases were discovered. NO controls mitochondrial respiration, and cytotoxic as well as cytoprotective effects have been described. The depression of OXPHOS ATP synthesis has been observed, attributed to the inhibition of mitochondrial Complex I and IV particularly, found responsible of major effects.SCOPE OF REVIEW: The review is focused on CcOX and NO with some hints about pathophysiological implications. The reactions of interest are reviewed, with special attention to the molecular mechanisms underlying the effects of NO observed on cytochrome c oxidase, particularly during turnover with oxygen and reductants. MAJOR CONCLUSIONS ANDGENERAL SIGNIFICANCE: The NO inhibition of CcOX is rapid and reversible and may occur in competition with oxygen. Inhibition takes place following two pathways leading to formation of either a relatively stable nitrosyl-derivative (CcOX-NO) of the enzyme reduced, or a more labile nitrite-derivative (CcOX-NO(2)(-)) of the enzyme oxidized, and during turnover. The pathway that prevails depends on the turnover conditions and concentration of NO and physiological substrates, cytochrome c and O(2). All evidence suggests that these parameters are crucial in determining the CcOX vs NO reaction pathway prevailing in vivo, with interesting physiological and pathological consequences for cells. This article is part of a Special Issue entitled: Respiratory Oxidases.cial Issue entitled: Respiratory Oxidases.)
Hereng 2011 Hum Reprod + (BACKGROUND: There has been an ongoing deba … BACKGROUND: There has been an ongoing debate in the reproductive field about whether mammalian spermatozoa rely on glycolysis, oxidative phosphorylation or both for their energy production. Recent studies have proposed that human spermatozoa depend mainly on glucose for motility and fertilization but the mechanism behind an efficient glycolysis in human spermatozoa is not well understood. Here, we demonstrate how human spermatozoa utilize exogenous pyruvate to enhance glycolytic ATP production, motility, hyperactivation and capacitation, events that are crucial for male fertility.METHODS: Purified human spermatozoa from healthy donors were incubated under capacitating conditions (including albumin, bicarbonate and glucose) and tested for changes in ATP levels, motility, hyperactivation and tyrosine phosphorylation after treatment with pyruvate. The experiments were repeated in the presence of sodium cyanide in order to assess the contribution from mitochondrial respiration. The metabolism of (13)C labeled glucose and pyruvate was traced by a combination of liquid chromatography and mass spectrometry.RESULTS: The treatment of human spermatozoa with exogenous pyruvate increased intracellular ATP levels, progressive motility and hyperactivation by 56, 21 and 130%, respectively. In addition, added pyruvate induced a significant increase in tyrosine phosphorylation levels. Blocking of the electron transport chain did not markedly affect the results, indicating that the mechanism is independent of oxidative phosphorylation. However, the observed effects could be counteracted by oxamate, an inhibitor of lactate dehydrogenase (LDH). Metabolic tracing experiments revealed that the observed rise in ATP concentration resulted from an enhanced glycolytic flux, which was increased by more than 50% in the presence of exogenous pyruvate. Moreover, all consumed (13)C labeled pyruvate added was converted to lactate rather than oxidized in the tricarboxylic acid cycle.CONCLUSIONS: Human spermatozoa seem to rely mainly, if not entirely, on glycolysis as the source of ATP fueling the energy-demanding processes of motility and capacitation. The efficient glycolysis is dependent on exogenous pyruvate, which indirectly feeds the accelerated glycolysis with NAD(+) through the LDH-mediated conversion of pyruvate to lactate. Pyruvate is present in the human female reproductive tract at concentrations in accordance with our results. As seen in other mammals, the motility and fertility of human spermatozoa seem to be dictated by the available energy substrates present in the conspecific female.strates present in the conspecific female.)
Hoeks 2011 PLoS One + (BACKGROUND: Type 2 diabetes mellitus and m … BACKGROUND: Type 2 diabetes mellitus and muscle insulin resistance have been associated with reduced capacity of skeletal muscle mitochondria, possibly as a result of increased intake of dietary fat. Here, we examined the hypothesis that a prolonged high-fat diet consumption (HFD) increases the saturation of muscle mitochondrial membrane phospholipids causing impaired mitochondrial oxidative capacity and possibly insulin resistance.METHODOLOGY: C57BL/6J mice were fed an 8-week or 20-week low fat diet (10 kcal%; LFD) or HFD (45 kcal%). Skeletal muscle mitochondria were isolated and fatty acid (FA) composition of skeletal muscle mitochondrial phospholipids was analyzed by thin-layer chromatography followed by GC. High-resolution respirometry was used to assess oxidation of pyruvate and fatty acids by mitochondria. Insulin sensitivity was estimated by HOMA-IR.PRINCIPAL FINDINGS: At 8 weeks, mono-unsaturated FA (16∶1n7, 18∶1n7 and 18∶1n9) were decreased (-4.0%, p<0.001), whereas saturated FA (16∶0) were increased (+3.2%, p<0.001) in phospholipids of HFD vs. LFD mitochondria. Interestingly, 20 weeks of HFD descreased mono-unsaturated FA while n-6 poly-unsaturated FA (18∶2n6, 20∶4n6, 22∶5n6) showed a pronounced increase (+4.0%, p<0.001). Despite increased saturation of muscle mitochondrial phospholipids after the 8-week HFD, mitochondrial oxidation of both pyruvate and fatty acids were similar between LFD and HFD mice. After 20 weeks of HFD, the increase in n-6 poly-unsaturated FA was accompanied by enhanced maximal capacity of the electron transport chain (+49%, p = 0.002) and a tendency for increased ADP-stimulated respiration, but only when fuelled by a lipid-derived substrate. Insulin sensitivity in HFD mice was reduced at both 8 and 20 weeks.CONCLUSIONS/INTERPRETATION: Our findings do not support the concept that prolonged HF feeding leads to increased saturation of skeletal muscle mitochondrial phospholipids resulting in a decrease in mitochondrial fat oxidative capacity and (muscle) insulin resistance.oxidative capacity and (muscle) insulin resistance.)
NCD-RisC 2017 Lancet + (BACKGROUND: Underweight, overweight, and o … BACKGROUND: Underweight, overweight, and obesity in childhood and adolescence are associated with adverse health consequences throughout the life-course. Our aim was to estimate worldwide trends in mean body-mass index (BMI) and a comprehensive set of BMI categories that cover underweight to obesity in children and adolescents, and to compare trends with those of adults.METHODS: We pooled 2416 population-based studies with measurements of height and weight on 128·9 million participants aged 5 years and older, including 31·5 million aged 5-19 years. We used a Bayesian hierarchical model to estimate trends from 1975 to 2016 in 200 countries for mean BMI and for prevalence of BMI in the following categories for children and adolescents aged 5-19 years: more than 2 SD below the median of the WHO growth reference for children and adolescents (referred to as moderate and severe underweight hereafter), 2 SD to more than 1 SD below the median (mild underweight), 1 SD below the median to 1 SD above the median (healthy weight), more than 1 SD to 2 SD above the median (overweight but not obese), and more than 2 SD above the median (obesity).FINDINGS: Regional change in age-standardised mean BMI in girls from 1975 to 2016 ranged from virtually no change (-0·01 kg/m2 per decade; 95% credible interval -0·42 to 0·39, posterior probability [PP] of the observed decrease being a true decrease=0·5098) in eastern Europe to an increase of 1·00 kg/m2 per decade (0·69-1·35, PP>0·9999) in central Latin America and an increase of 0·95 kg/m2 per decade (0·64-1·25, PP>0·9999) in Polynesia and Micronesia. The range for boys was from a non-significant increase of 0·09 kg/m2 per decade (-0·33 to 0·49, PP=0·6926) in eastern Europe to an increase of 0·77 kg/m2 per decade (0·50-1·06, PP>0·9999) in Polynesia and Micronesia. Trends in mean BMI have recently flattened in northwestern Europe and the high-income English-speaking and Asia-Pacific regions for both sexes, southwestern Europe for boys, and central and Andean Latin America for girls. By contrast, the rise in BMI has accelerated in east and south Asia for both sexes, and southeast Asia for boys. Global age-standardised prevalence of obesity increased from 0·7% (0·4-1·2) in 1975 to 5·6% (4·8-6·5) in 2016 in girls, and from 0·9% (0·5-1·3) in 1975 to 7·8% (6·7-9·1) in 2016 in boys; the prevalence of moderate and severe underweight decreased from 9·2% (6·0-12·9) in 1975 to 8·4% (6·8-10·1) in 2016 in girls and from 14·8% (10·4-19·5) in 1975 to 12·4% (10·3-14·5) in 2016 in boys. Prevalence of moderate and severe underweight was highest in India, at 22·7% (16·7-29·6) among girls and 30·7% (23·5-38·0) among boys. Prevalence of obesity was more than 30% in girls in Nauru, the Cook Islands, and Palau; and boys in the Cook Islands, Nauru, Palau, Niue, and American Samoa in 2016. Prevalence of obesity was about 20% or more in several countries in Polynesia and Micronesia, the Middle East and north Africa, the Caribbean, and the USA. In 2016, 75 (44-117) million girls and 117 (70-178) million boys worldwide were moderately or severely underweight. In the same year, 50 (24-89) million girls and 74 (39-125) million boys worldwide were obese.INTERPRETATION: The rising trends in children's and adolescents' BMI have plateaued in many high-income countries, albeit at high levels, but have accelerated in parts of Asia, with trends no longer correlated with those of adults.h trends no longer correlated with those of adults.)
Paech 2017 Arch Toxicol + (BAL30072 is a new monocyclic β-lactam anti … BAL30072 is a new monocyclic β-lactam antibiotic under development which provides a therapeutic option for the treatment of severe infections caused by multi-drug-resistant Gram-negative bacteria. Despite the absence of liver toxicity in preclinical studies in rats and marmosets and in single dose clinical studies in humans, increased transaminase activities were observed in healthy subjects in multiple-dose clinical studies. We, therefore, initiated a comprehensive program to find out the mechanisms leading to hepatocellular injury using HepG2 cells (human hepatocellular carcinoma cell line), HepaRG cells (inducible hepatocytes derived from a human hepatic progenitor cell line), and human liver microtissue preparations. Our investigations demonstrated a concentration- and time-dependent reduction of the ATP content of BAL30072-treated HepG2 cells and liver microtissues. BAL30072 impaired oxygen consumption by HepG2 cells at clinically relevant concentrations, inhibited complexes II and III of the mitochondrial electron transport chain, increased the production of reactive oxygen species (ROS), and reduced the mitochondrial membrane potential. Furthermore, BAL 30072 impaired mitochondrial fatty acid metabolism, inhibited glycolysis, and was associated with hepatocyte apoptosis. Co-administration of N-acetyl-L-cysteine partially protected hepatocytes from BAL30072-mediated toxicity, underscoring the role of oxidative damage in the observed hepatocellular toxicity. In conclusion, BAL30072 is toxic for liver mitochondria and inhibits glycolysis at clinically relevant concentrations. Impaired hepatic mitochondrial function and inhibition of glycolysis can explain liver injury observed in human subjects receiving long-term treatment with this compound.ng long-term treatment with this compound.)

10th World Gene Convention 2019 Qingdao CN + (BIT’s 10th World Gene Convention-2019 (WGC-2019), Qingdao, China, 2019)

Gururaja Rao 2019 Cells + (BKCa channels, orig … BKCa channels, originally discovered in ''Drosophila melanogaster'' as slowpoke (slo), are recognized for their roles in cellular and organ physiology. Pharmacological approaches implicated BKCa channels in cellular and organ protection possibly for their ability to modulate mitochondrial function. However, the direct role of BKCa channels in regulating mitochondrial structure and function is not deciphered. Here, we demonstrate that BKCa channels are present in fly mitochondria, and slo mutants show structural and functional defects in mitochondria. slo mutants display an increase in reactive oxygen species and the modulation of ROS affected their survival. We also found that the absence of BKCa channels reduced the lifespan of ''Drosophila'', and overexpression of human BKCa channels in flies extends life span in males. Our study establishes the presence of BKCa channels in mitochondria of ''Drosophila'' and ascertains its novel physiological role in regulating mitochondrial structural and functional integrity, and lifespan.a'' and ascertains its novel physiological role in regulating mitochondrial structural and functional integrity, and lifespan.)
Crislip 2022 Biomolecules + (BMAL1 is a core mammalian circadian clock … BMAL1 is a core mammalian circadian clock transcription factor responsible for the regulation of the expression of thousands of genes. Previously, male skeletal-muscle-specific BMAL1-inducible-knockout (iMS-BMAL1 KO) mice have been described as a model that exhibits an aging-like phenotype with an altered gait, reduced mobility, muscle weakness, and impaired glucose uptake. Given this aging phenotype and that chronic kidney disease is a disease of aging, the goal of this study was to determine if iMS-BMAL1 KO mice exhibit a renal phenotype. Male iMS-BMAL1 KO and control mice were challenged with a low potassium diet for five days. Both genotypes responded appropriately by conserving urinary potassium. The iMS-BMAL1 KO mice excreted less potassium during the rest phase during the normal diet but there was no genotype difference during the active phase. Next, iMS-BMAL1 KO and control mice were used to compare markers of kidney injury and assess renal function before and after a phase advance protocol. Following phase advance, no differences were detected in renal mitochondrial function in iMS-BMAL1 KO mice compared to control mice. Additionally, the glomerular filtration rate and renal morphology were similar between groups in response to phase advance. Disruption of the clock in skeletal muscle tissue activates inflammatory pathways within the kidney of male mice, and there is evidence of this affecting other organs, such as the lungs. However, there were no signs of renal injury or altered function following clock disruption of skeletal muscle under the conditions tested.eletal muscle under the conditions tested.)
BMES-SIG & MIG Conclave 2023 Virtual + (BMES-SIG & MIG Conclave, Virtual, 2023)
BMT 2022 Innsbruck AT + (BMT 2022, Innsbruck, 2022)
Osiki 2016 FASEB J + (Background Beta-oxidation is often measure … BackgroundBeta-oxidation is often measured using respirometry with octanoylcarnitine + malate as substrates in cells. Malate is necessary to ensure continuous oxidation of octanoylcarnitine. However, since malate is metabolized in the TCA cycle, it is not clear if its inclusion as a co-substrate allows for a valid assessment of beta-oxidation when TCA cycle function is compromised.AimTo investigate the validity of beta-oxidation assessment using octanoylcarnitine + malate as a substrate combination in skeletal muscle when mitochondrial (mt) aconitase is inhibited.MethodsSoleus muscle fibres (1.5–2mg) from healthy male Wistar rats were permeabilized with saponin and incubated for 45 minutes with 1mM oxalomalic acid (aconitase inhibitor) or 1mM 2-mercaptoacetate, an inhibitor of MCAD – the rate-limiting enzyme of octanoylcarnitine oxidation. Respiration at Leak, Oxphos and ET-pathway states were measured using an Oroboros oxygraph. Citrate and 2-oxoglutarate in the respiratory media were measured using CG-MS. Activities of aconitase and MCAD were determined spectrophotometrically.ResultsOxalomalic acid (1mM) and 1mM of 2-mercaptoacetate caused 24% and 58% inhibition of acnonitase and MCAD, respectively. Oxygen flux at Oxphos (0.5 ± 0.3 pmol.S−1.mg−1) and ET-pathway (0.6 ± 0.2 pmol.S−1.mg−1) decreased in 2-mercaptoacetate-treated samples by 62.5% and 60%, respectively, but were unchanged with oxalomalic acid treatment. Respiration at leak state was similar for all treatments. Citrate level in the medium increased by 2-fold at Oxphos state after 30 minutes.ConclusionOctanoylcarnitine + malate allows for a valid assessment of beta-oxidation capacity using respirometry under conditions where mt-aconitase has been inhibited.Support or Funding InformationSupport: 1. The research unit for Exercise Science & Sports Medicine at the University of Cape Town 2. The National Research Foundation (NRF), South Africa, for funding the research.FootnotesThis abstract is from the Experimental Biology 2016 Meeting. There is no full text article associated with this abstract published in The FASEB Journal. this abstract published in The FASEB Journal.)
Nesci 2016 Biochim Biophys Acta + (Background The mitochondrial F1FO-ATP synt … BackgroundThe mitochondrial F1FO-ATP synthase has not only the known life function in building most cellular ATP, but also, as recently hinted, an amazing involvement in cell death. Accordingly, the two-faced enzyme complex, which catalyzes both ATP synthesis and ATP hydrolysis, has been involved in the mitochondrial permeability transition, the master player in apoptosis and necrosis. Nitrite, a cellular nitric oxide reservoir, has a recognized role in cardiovascular protection, through still unclear mechanisms.MethodsIn swine heart mitochondria the effect of nitrite on the F1FO-ATPase activity activated by Ca2+, henceforth defined as Ca-ATPase(s), or by the natural cofactor Mg2+, was investigated by evaluating ATP hydrolysis under different assay conditions.ResultsCa2+ is far less efficient than the natural cofactor Mg2+ in the ATPase activation. However, when activated by Ca2+ the ATPase activity is especially responsive to nitrite, which acts as uncompetitive inhibitor and up to 2 mM inhibits the Ca2+-activated-ATPase(s), probably by promoting dytirosine formation on the enzyme proteins, leaving the Mg-ATPase(s) unaffected. Most likely these ATPases refer to the same F1FO complex, even if coexistent ATPases may overlap.ConclusionsThe preferential inhibition by nitrite of the Ca-ATPase(s), due to post-translational tyrosine modifications, may prevent the calcium-dependent functionality of the mitochondrial F1FO complex and related events.General significanceIn mitochondria the preferential inhibition of the Ca-ATPase activity/ies by nitrite concentrations which do not affect the coexistent Mg-ATPase(s) may quench the negative events linked to the calcium-dependent functioning mode of the F1FO complex under pathological conditions.egative events linked to the calcium-dependent functioning mode of the F1FO complex under pathological conditions.)
Rector 2010 J Hepatol + (Background & aims: In this study, we s … Background & aims: In this study, we sought to determine the temporal relationship between hepatic mitochondrial dysfunction, hepatic steatosis and insulin resistance, and to examine their potential role in the natural progression of non-alcoholic fatty liver disease (NAFLD) utilising a sedentary, hyperphagic, obese, Otsuka Long-Evans Tokushima Fatty (OLETF) rat model.Methods: OLETF rats and their non-hyperphagic control Long-Evans Tokushima Otsuka (LETO) rats were sacrificed at 5, 8, 13, 20, and 40 weeks of age (n=6-8 per group).Results: At 5 weeks of age, serum insulin and glucose and hepatic triglyceride (TG) concentrations did not differ between animal groups; however, OLETF animals displayed significant (p<0.01) hepatic mitochondrial dysfunction as measured by reduced hepatic carnitine palmitoyl-CoA transferase-1 activity, fatty acid oxidation, and cytochrome c protein content compared with LETO rats. Hepatic TG levels were significantly elevated by 8 weeks of age, and insulin resistance developed by 13 weeks in the OLETF rats. NAFLD progressively worsened to include hepatocyte ballooning, perivenular fibrosis, 2.5-fold increase in serum ALT, hepatic mitochondrial ultrastructural abnormalities, and increased hepatic oxidative stress in the OLETF animals at later ages. Measures of hepatic mitochondrial content and function including beta-hydroxyacyl-CoA dehydrogenase activity, citrate synthase activity, and immunofluorescence staining for mitochondrial carbamoyl phosphate synthetase-1, progressively worsened and were significantly reduced at 40 weeks in OLETF rats compared to LETO animals.Conclusions: Our study documents that hepatic mitochondrial dysfunction precedes the development of NAFLD and insulin resistance in the OLETF rats. This evidence suggests that progressive mitochondrial dysfunction contributes to the natural history of obesity-associated NAFLD. the natural history of obesity-associated NAFLD.)
Noz 2019 J Am Heart Assoc + (Background Low-grade inflammation, largely … Background Low-grade inflammation, largely mediated by monocyte-derived macrophages, contributes to atherosclerosis. Sedentary behavior is associated with atherosclerosis and cardiovascular diseases (CVD). We examined whether reducing sedentary behavior and improving walking time improves monocyte inflammatory phenotype in subjects with increased cardiovascular risk. Methods and Results Across 2 waves, 16 individuals with increased cardiovascular risk performed a 16-week intervention study (age 64±6 years, body mass index 29.9±4.3 kg/m2), using a device with vibration feedback to promote physical activity. Before and after intervention, we objectively examined physical activity (ActivPAL), cytokine production capacity after ''ex vivo'' stimulation in peripheral blood mononuclear cells, metabolism of peripheral blood mononuclear cells, circulating cytokine concentrations, and monocyte immunophenotype. Overall, no significant increase in walking time was found (1.9±0.7 to 2.2±1.2 h/day, P=0.07). However, strong, inverse correlations were observed between the change in walking time and the change in production of interleukin (IL)-1β, IL-6, IL-8, and IL-10 after lipopolysaccharide stimulation (rs=-0.655, -0.844, -0.672, and -0.781, respectively, all P<0.05). After intervention optimization based on feedback from wave 1, participants in wave 2 (n=8) showed an increase in walking time (2.2±0.8 to 3.0±1.3 h/day, P=0.001) and attenuated cytokine production of IL-6, IL-8, and IL-10 (all P<0.05). Glycolysis (P=0.08) and maximal OXPHOS (P=0.04) of peripheral blood mononuclear cells decreased after intervention. Lower IL-6 concentrations (P=0.06) and monocyte percentages (P<0.05), but no changes in monocyte subsets were found. Conclusions Successfully improving walking time shifts innate immune function towards a less proinflammatory state, characterized by a lower capacity to produce inflammatory cytokines, in individuals with increased cardiovascular risk.y cytokines, in individuals with increased cardiovascular risk.)
Poles 2021 Front Immunol + (Background and aims: The systemic host res … Background and aims: The systemic host response in sepsis is frequently accompanied by central nervous system (CNS) dysfunction. Evidence suggests that excessive formation of neutrophil extracellular traps (NETs) can increase the permeability of the blood-brain barrier (BBB) and that the evolving mitochondrial damage may contribute to the pathogenesis of sepsis-associated encephalopathy. Kynurenic acid (KYNA), a metabolite of tryptophan catabolism, exerts pleiotropic cell-protective effects under pro-inflammatory conditions. Our aim was to investigate whether exogenous KYNA or its synthetic analogues SZR-72 and SZR-104 affect BBB permeability secondary to NET formation and influence cerebral mitochondrial disturbances in a clinically relevant rodent model of intraabdominal sepsis.Methods: Sprague-Dawley rats were subjected to fecal peritonitis (0.6 g kg-1 ip) or a sham operation. Septic animals were treated with saline or KYNA, SZR-72 or SZR-104 (160 µmol kg-1 each ip) 16h and 22h after induction. Invasive monitoring was performed on anesthetized animals to evaluate respiratory, cardiovascular, renal, hepatic and metabolic parameters to calculate rat organ failure assessment (ROFA) scores. NET components (citrullinated histone H3 (CitH3); myeloperoxidase (MPO)) and the NET inducer IL-1β, as well as IL-6 and a brain injury marker (S100B) were detected from plasma samples. After 24h, leukocyte infiltration (tissue MPO) and mitochondrial complex I- and II-linked (CI-CII) oxidative phosphorylation (OXPHOS) were evaluated. In a separate series, Evans Blue extravasation and the edema index were used to assess BBB permeability in the same regions.Results: Sepsis was characterized by significantly elevated ROFA scores, while the increased BBB permeability and plasma S100B levels demonstrated brain damage. Plasma levels of CitH3, MPO and IL-1β were elevated in sepsis but were ameliorated by KYNA and its synthetic analogues. The sepsis-induced deterioration in tissue CI-CII-linked OXPHOS and BBB parameters as well as the increase in tissue MPO content were positively affected by KYNA/KYNA analogues.Conclusion: This study is the first to report that KYNA and KYNA analogues are potential neuroprotective agents in experimental sepsis. The proposed mechanistic steps involve reduced peripheral NET formation, lowered BBB permeability changes and alleviation of mitochondrial dysfunction in the CNS.n of mitochondrial dysfunction in the CNS.)
Distefano 2012 Abstract IOC68 + (Background: Aging is associated with reduc … Background: Aging is associated with reductions in skeletal muscle mitochondria function as evidenced by a decreased capacity for ATP production and mitochondrial protein content [1,2,3]. Aging is also associated with changes in body composition, including increased adiposity, and a loss of aerobic fitness. Both are factors that confound an examination of the relationship between mitochondrial function and aging per se. The objective of this study was to determine whether the respiratory properties of permeabilized skeletal muscle fibers are altered with chronological age, or more related to age associated changes in adiposity and aerobic fitness.Methods: A total of 63 participants were assigned to one of the following groups: Young (Y, 26.9 ± 0.9 yrs, ''n''=30), Middle-aged (M, 41.2 ± 2.4 yrs, ''n''=13), or Elderly (77.7 ± 1.1 yrs, ''n''=20). Following an overnight fast, a percutaneous muscle biopsy of vastus lateralis was obtained. Maximal coupled (St.''P''), maximal non-coupled (St.''E''), and LEAK state (St.''L'') respiration was determined in saponin permeabilized muscle fiber bundles using high-resolution respirometry. ''V''O2peak was determined by a graded exercise test. Total body fat and fat free mass were assessed by whole body DEXA.Results: The Y group had significantly greater levels of St.''P'' respiration (220 ± 15 pmol O2 s-1mg-1) compared to M (166 ± 13 pmol O2 s-1mg-1, ''P'' = 0.02) and O groups (170 ± 13 pmol O2 s-1mg-1, ''P'' = 0.014). There was no difference in St.''P'' respiration between M and O groups. Similar group differences were also observed for St.''E'' and St.''L'' respiration. The Y group exhibited a higher ''V''O2peak (46 ± 2.9 ml min-1kg-1) compared to M (28 ± 1.8 ml min-1kg-1, ''P''<0.01) and O (21 ± 2.2 ml min-1kg-1, ''P''<0.01) groups. When the three groups were combined, St.''P'' respiration was positively correlated with ''V''O2peak (''R'' = 0.631, ''P''<0.01), and negatively correlated with age (''R'' = -0.324, ''P'' = 0.01), BMI (''R'' =-0.371, ''P''<0.01), fasting glucose (''R'' = -0.252, ''P'' = 0.047), and fat mass (''R'' = -0.516, ''P'' = <0.01).Conclusions: Our data suggest that age related changes in body composition and aerobic fitness may be more important to mitochondrial dysfunction than chronological age per se.References: 1. Petersen KF, Befroy D, Dufour S, Dziura J, Ariyan C, Rothman DL, DiPietro L, Cline GW, Shulman GI (2003) Mitochondrial dysfunction in the elderly: Possible role in insulin resistance. Science 300: 1140-1142.2. Conley KE, Jubrias SA, Esselman PC (2000) Oxidative capacity and ageing in human muscle. J Physiol 526: 203-210.3. Short KR, Bigelow ML, Kahl J, Singh R, Coenen-Schimke J, Raghavakaimal S, Nair KS (2005) Decline in skeletal muscle mitochondrial function with aging in humans. Proc Natl Acad Sci U S A 102: 5618-5623.idative capacity and ageing in human muscle. J Physiol 526: 203-210. 3. Short KR, Bigelow ML, Kahl J, Singh R, Coenen-Schimke J, Raghavakaimal S, Nair KS (2005) Decline in skeletal muscle mitochondrial function with aging in humans. Proc Natl Acad Sci U S A 102: 5618-5623.)
Haslam 2007 Obes Rev + (Background: Although there have been major … Background: Although there have been major advances in the study of obesity, Aibo clearly demonstrates that the one thing the battle against obesity does not need is new scientific invention. Reaven’s utterances proved pivotal, and nothing since has carried the gravitas of his proclamation. Aibo, on the other hand, will be consigned to history’s waste bin. Uniquely among chronic diseases, lack of scientific knowledge is not a barrier to the successful treatment of a person who is obese. Whereas cancer treatment requires new drugs and heart disease updated techniques, obesity is different. We already know enough about the causes and how to manage it by diet, activity, drugs and surgery. The history of obesity is a history of failure. Looking back in time, however, gives us many insights as to treatment in the future. Obesity in history: Obesity is changing, but its origins can be traced back 30 000 years, to our prehistoric ancestors. Survival of the fittest dictated that individuals who stored energy in the most efficient way would survive the inevitable fast and famine that would follow times of plenty. This has been attributed to the ‘thrifty gene’ (although no such individual gene exists), ensuring the continued dominance of our hunter–gatherer predecessors. But natural selection has turned on us. Life now favours inefficient phenotypes who fail to store energy in adipose depots, while those who lay down fat in the abdomen are condemned to premature death. To fight obesity, we are flying in the face of evolution and instinct, consciously countermanding the urge to eat for survival, and be as inactive as possible in order to conserve energy.The situation today: The UK is now in the throes of an obesity epidemic, and risks following in the footsteps of America, where obesity has already delivered an epidemic of diabetes. Writers and physicians over many centuries have dedicated their life’s work to teach the preservation of health, and warn of the dire consequences of ignoring good diet and activity. However, their wisdom has been disregarded. Life expectancy has been improving for centuries; advances in hygiene, science, public health and medicine have allowed longer and more productive lives. Obesity threatens to undo many of these gains. Could it even herald a reduction in life expectancy in coming generations? Instead of spending precious resources inventing novel scientific gadgets, the works of our forefathers should be revisited, and the simple lessons learned from history used to once again prioritize the preservation of health.ain prioritize the preservation of health.)
Pühringer 2021 High Alt Med Biol + (Background: Altitude exposure reduces maxi … Background: Altitude exposure reduces maximal oxygen uptake (''V''O2max). Usually, the reduction is not restored with acclimatization (at least at altitudes above 2500 m) and is more pronounced in highly trained athletes compared to nonathletes. It still remains to be elucidated whether these also apply for well-acclimatized individuals (i.e., mountain guides) acutely exposed to moderate altitude (i.e., 2000 m). Methods: A total of 128 acclimatized male mountain guides of the Austrian armed forces (42.2 ± 7.0 years, 177.8 ± 5.6 cm, 77.2 ± 7.0 kg) of different fitness levels performed 2 incremental cycle ergometer tests 1 week apart, one at low (600 m) and one at moderate altitude (2000 m). Oxygen uptake, heart rate (HR), and lactate concentration were measured during the tests. Results: In acclimatized mountain guides, lower baseline ''V''O2max levels were associated with better preservation of ''V''O2max at moderate altitude compared to higher levels. At moderate altitude, physiological responses (HR and blood lactate at 100 W) at a submaximal exercise intensity of 100 W remained unchanged or were even slightly reduced in both groups. Conclusions: Long-term acclimatization to moderate altitude may prevent the ''V''O2max decline at a moderate altitude of 2 000 m particularly in subjects with lower ''V''O2max levels, that is, below the 80th percentile (for age and sex). In people with higher fitness levels, ''V''O2max may still be negatively affected. These results are of practical relevance, for example, for workers, athletes, ski and mountain guides, military staff, or rescue staff who regularly or continuously have to perform at moderate altitude.e of practical relevance, for example, for workers, athletes, ski and mountain guides, military staff, or rescue staff who regularly or continuously have to perform at moderate altitude.)
Reiss 2022 Exp Gerontol + (Background: Alzheimer's disease (AD) is th … Background: Alzheimer's disease (AD) is the most prevalent form of dementia worldwide and is characterized by progressive memory loss and cognitive impairment. Our understanding of AD pathogenesis is limited and no effective disease-modifying treatment is available. Mitochondria are cytoplasmic organelles critical to the homeostatic regulation of glucose and energy in the cell.Methods: Mitochondrial abnormalities are found early in the course of AD and dysfunctional mitochondria are involved in AD progression. The resulting respiratory chain impairment, neuronal apoptosis, and generation of reactive oxygen species are highly damaging to neurons. Restoration of mitochondrial function may provide a novel therapeutic strategy for AD.Results: This review discusses the specifics of mitochondrial fragmentation, imbalances in fission and fusion, and DNA damage seen in AD and the contribution of compromised mitochondrial activity to AD etiopathogenesis. It explores how an understanding of the processes underlying mitochondrial failure may lead to urgently needed treatment innovations. It considers individual mitochondrial proteins that have emerged as promising drug targets and evaluates neuroprotective agents that could improve the functional state of mitochondria in the setting of AD.Conclusions: There is great promise in exploring original approaches to preserving mitochondrial viability as a means to achieve breakthroughs in treating AD.s to achieve breakthroughs in treating AD.)
Wider 2023 Crit Care + (Background: Brain injury is a leading caus … Background: Brain injury is a leading cause of morbidity and mortality in patients resuscitated from cardiac arrest. Mitochondrial dysfunction contributes to brain injury following cardiac arrest; therefore, therapies that limit mitochondrial dysfunction have the potential to improve neurological outcomes. Generation of reactive oxygen species (ROS) during ischemia-reperfusion injury in the brain is a critical component of mitochondrial injury and is dependent on hyperactivation of mitochondria following resuscitation. Our previous studies have provided evidence that modulating mitochondrial function with specific near-infrared light (NIR) wavelengths can reduce post-ischemic mitochondrial hyperactivity, thereby reducing brain injury during reperfusion in multiple small animal models.Methods: Isolated porcine brain cytochrome c oxidase (COX) was used to investigate the mechanism of NIR-induced mitochondrial modulation. Cultured primary neurons from mice expressing mitoQC were utilized to explore the mitochondrial mechanisms related to protection with NIR following ischemia-reperfusion. Anesthetized pigs were used to optimize the delivery of NIR to the brain by measuring the penetration depth of NIR to deep brain structures and tissue heating. Finally, a model of out-of-hospital cardiac arrest with CPR in adult pigs was used to evaluate the translational potential of NIR as a noninvasive therapeutic approach to protect the brain after resuscitation.Results: Molecular evaluation of enzyme activity during NIR irradiation demonstrated COX function was reduced in an intensity-dependent manner with a threshold of enzyme inhibition leading to a moderate reduction in activity without complete inhibition. Mechanistic interrogation in neurons demonstrated that mitochondrial swelling and upregulation of mitophagy were reduced with NIR treatment. NIR therapy in large animals is feasible, as NIR penetrates deep into the brain without substantial tissue heating. In a translational porcine model of CA/CPR, transcranial NIR treatment for two hours at the onset of return of spontaneous circulation (ROSC) demonstrated significantly improved neurological deficit scores and reduced histologic evidence of brain injury after resuscitation from cardiac arrest.Conclusions: NIR modulates mitochondrial function which improves mitochondrial dynamics and quality control following ischemia/reperfusion. Noninvasive modulation of mitochondria, achieved by transcranial treatment of the brain with NIR, mitigates post-cardiac arrest brain injury and improves neurologic functional outcomes.d improves neurologic functional outcomes.)
Serafim 2021 Eur J Clin Invest + (Background: Changes in the nutritional env … Background: Changes in the nutritional environment in utero induced by maternal obesity (MO) lead to foetal metabolic dysfunction predisposing offspring to later-life metabolic diseases. Since mitochondria play a crucial role in hepatic metabolism and function, we hypothesized that MO prior to conception and throughout pregnancy programmes foetal sheep liver mitochondrial phenotype.Material and methods: Ewes ate an obesogenic diet (150% requirements; MO), or 100% requirements (CTR), from 60 days prior to conception. Foetal livers were removed at 0.9 gestation. We measured foetal liver mitochondrial DNA copy number, activity of superoxide dismutase, cathepsins B and D and selected protein content, total phospholipids and cardiolipin and activity of mitochondrial respiratory chain complexes.Results: A significant decrease in activities of mitochondrial complexes I, II-III and IV, but not aconitase, was observed in MO. In the antioxidant machinery, there was a significant increase in activity of total superoxide dismutase (SOD) and SOD2 in MO. However, no differences were found regarding autophagy-related protein content (p62, beclin-I, LC3-I, LC3-II and Lamp2A) and cathepsin B and D activities. A 21.5% decrease in total mitochondrial phospholipid was observed in MO.Conclusions: The data indicate that MO impairs foetal hepatic mitochondrial oxidative capacity and affects total mitochondrial phospholipid content. In addition, MO affects the regulation of foetal liver redox pathways, indicating metabolic adaptations to the higher foetal lipid environment. Consequences of in utero programming of foetal hepatic metabolism may persist and compromise mitochondrial bioenergetics in later life, and increase susceptibility to metabolic diseases.ease susceptibility to metabolic diseases.)
Picard 2018 Biol Psychiatry + (Background: Chronic life stress, such as t … Background: Chronic life stress, such as the stress of caregiving, can promote pathophysiology, but the underlying cellular mechanisms are not well understood. Chronic stress may induce recalibrations in mitochondria leading to changes either in mitochondrial content per cell, or in mitochondrial functional capacity (i.e., quality).Methods: Here we present a functional index of mitochondrial health (MHI) for human leukocytes that can distinguish between these two possibilities. The MHI integrates nuclear and mitochondrial DNA-encoded respiratory chain enzymatic activities and mitochondrial DNA copy number. We then use the MHI to test the hypothesis that daily emotional states and caregiving stress influence mitochondrial function by comparing healthy mothers of a child with an autism spectrum disorder (high-stress caregivers, ''n'' = 46) with mothers of a neurotypical child (control group, ''n'' = 45).Results: The MHI outperformed individual mitochondrial function measures. Elevated positive mood at night was associated with higher MHI, and nightly positive mood was also a mediator of the association between caregiving and MHI. Moreover, MHI was correlated to positive mood on the days preceding, but not following the blood draw, suggesting for the first time in humans that mitochondria may respond to proximate emotional states within days. Correspondingly, the caregiver group, which had higher perceived stress and lower positive and greater negative daily affect, exhibited lower MHI. This effect was not explained by a mismatch between nuclear and mitochondrial genomes.Conclusions: Daily mood and chronic caregiving stress are associated with mitochondrial functional capacity. Mitochondrial health may represent a nexus between psychological stress and health.s between psychological stress and health.)
Bhatraju 2020 N Engl J Med + (Background: Community transmission of coro … Background: Community transmission of coronavirus 2019 (Covid-19) was detected in the state of Washington in February 2020.Methods: We identified patients from nine Seattle-area hospitals who were admitted to the intensive care unit (ICU) with confirmed infection with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Clinical data were obtained through review of medical records. The data reported here are those available through March 23, 2020. Each patient had at least 14 days of follow-up.Results: We identified 24 patients with confirmed Covid-19. The mean (±SD) age of the patients was 64±18 years, 63 % were men, and symptoms began 7±4 days before admission. The most common symptoms were cough and shortness of breath; 50 % of patients had fever on admission, and 58 % had diabetes mellitus. All the patients were admitted for hypoxemic respiratory failure; 75 % (18 patients) needed mechanical ventilation. Most of the patients (17) also had hypotension and needed vasopressors. No patient tested positive for influenza A, influenza B, or other respiratory viruses. Half the patients (12) died between ICU day 1 and day 18, including 4 patients who had a do-not-resuscitate order on admission. Of the 12 surviving patients, 5 were discharged home, 4 were discharged from the ICU but remained in the hospital, and 3 continued to receive mechanical ventilation in the ICU.Conclusions: During the first 3 weeks of the Covid-19 outbreak in the Seattle area, the most common reasons for admission to the ICU were hypoxemic respiratory failure leading to mechanical ventilation, hypotension requiring vasopressor treatment, or both. Mortality among these critically ill patients was high. (Funded by the National Institutes of Health.).ed by the National Institutes of Health.).)
Catania 2019 Orphanet J Rare Dis + (Background: Complex I (CI or NADH:ubiquino … Background: Complex I (CI or NADH:ubiquinone oxidoreductase) deficiency is the most frequent cause of mitochondrial respiratory chain defect. Successful attempts to rescue CI function by introducing an exogenous NADH dehydrogenase, such as the NDI1 from Saccharomyces cerevisiae (ScNDI1), have been reported although with drawbacks related to competition with CI. In contrast to ScNDI1, which is permanently active in yeast naturally devoid of CI, plant alternative NADH dehydrogenases (NDH-2) support the oxidation of NADH only when the CI is metabolically inactive and conceivably when the concentration of matrix NADH exceeds a certain threshold. We therefore explored the feasibility of CI rescue by NDH-2 from Arabidopsis thaliana (At) in human CI defective fibroblasts.Results: We showed that, other than ScNDI1, two different NDH-2 (AtNDA2 and AtNDB4) targeted to the mitochondria were able to rescue CI deficiency and decrease oxidative stress as indicated by a normalization of SOD activity in human CI-defective fibroblasts. We further demonstrated that when expressed in human control fibroblasts, AtNDA2 shows an affinity for NADH oxidation similar to that of CI, thus competing with CI for the oxidation of NADH as opposed to our initial hypothesis. This competition reduced the amount of ATP produced per oxygen atom reduced to water by half in control cells.Conclusions: In conclusion, despite their promising potential to rescue CI defects, due to a possible competition with remaining CI activity, plant NDH-2 should be regarded with caution as potential therapeutic tools for human mitochondrial diseases.ic tools for human mitochondrial diseases.)
Furihata 2021 BMC Pharmacol Toxicol + (Background: Doxorubicin (DOX) is widely us … Background: Doxorubicin (DOX) is widely used as an effective chemotherapeutic agent for cancers; however, DOX induces cardiac toxicity, called DOX-induced cardiomyopathy. Although DOX-induced cardiomyopathy is known to be associated with a high cumulative dose of DOX, the mechanisms of its long-term effects have not been completely elucidated. Pioglitazone (Pio) is presently contraindicated in patients with symptomatic heart failure owing to the side effects. The concept of drug repositioning led us to hypothesize the potential effects of Pio as a premedication before DOX treatment, and to analyze this hypothesis in mice.Methods: First, for the hyperacute (day 1) and acute (day 7) DOX-induced dysfunction models, mice were fed a standard diet with or without 0.02% (wt/wt) Pio for 5 days before DOX treatment (15 mg/kg body weight [BW] via intraperitoneal [i.p.] administration). The following 3 treatment groups were analyzed: standard diet + vehicle (Vehicle), standard diet + DOX (DOX), and Pio + DOX. Next, for the chronic model (day 35), the mice were administrated DOX once a week for 5 weeks (5 mg/kg BW/week, i.p.).Results: In the acute phase after DOX treatment, the percent fractional shortening of the left ventricle (LV) was significantly decreased in DOX mice. This cardiac malfunction was improved in Pio + DOX mice. In the chronic phase, we observed that LV function was preserved in Pio + DOX mice.Conclusions: Our findings may provide a new pathophysiological explanation by which Pio plays a role in the treatment of DOX-induced cardiomyopathy, but the molecular links between Pio and DOX-induced LV dysfunction remain largely elusive.ced LV dysfunction remain largely elusive.)
Zuccolotto-dos-Reis 2021 Eur J Clin Invest + (Background: Freezing human biopsies is com … Background: Freezing human biopsies is common in clinical practice for storage. However, this technique disrupts mitochondrial membranes, hampering further analyses of respiratory function. To contribute to laboratorial diagnosis of mitochondrial diseases, this study sought to develop a respirometry approach using O2k (Oroboros Ins.) to measure the whole electron transport chain (ETC) activity in homogenates of frozen skeletal muscle biopsies.Patients and methods: We enrolled 16 patients submitted to muscle biopsy in the process of routine diagnostic investigation: four with mitochondrial disease and severe mitochondrial dysfunction; seven with exercise intolerance and multiple deletions of mitochondrial DNA, presenting mild to moderate mitochondrial dysfunction; five without mitochondrial disease, as controls. Whole homogenates of muscle fragments were prepared using grinder-type equipment. O2 consumption rates were normalized using citrate synthase activity.Results: Transmission electron microscopy confirmed mitochondrial membrane discontinuation, indicating increased permeability of mitochondrial membranes in homogenates from frozen biopsies. O2 consumption rates in the presence of acetyl-CoA lead to maximum respiratory rates sensitive to rotenone, malonate and antimycin. This protocol of acetyl-CoA-driven respiration (ACoAR), applied in whole homogenates of frozen muscle, was sensitive enough to identify ETC abnormality, even in patients with mild to moderate mitochondrial dysfunction. We demonstrated adequate repeatability of ACoAR and found significant correlation between O2 consumption rates and enzyme activity assays of individual ETC complexes.Conclusions: We present preliminary data on a simple, low cost and reliable procedure to measure respiratory function in whole homogenates of frozen skeletal muscle biopsies, contributing to diagnosis of mitochondrial diseases in humans.Keywords: acetyl-CoA-driven respiration; electron transport chain; frozen skeletal muscle biopsy; high-resolution respirometry; mitochondrial diseases; oxygen consumption rate.ondrial diseases; oxygen consumption rate.)
Guralnik 1995 N Engl J Med + (Background: Functional assessment is an im … Background: Functional assessment is an important part of the evaluation of elderly persons. We conducted this study to determine whether objective measures of physical function can predict subsequent disability in older persons.Methods: This prospective cohort study included men and women 71 years of age or older who were living in the community, who reported no disability in the activities of daily living, and who reported that they were able to walk one-half mile (0.8 km) and climb stairs without assistance. The subjects completed a short battery of physical-performance tests and participated in a follow-up interview four years later. The tests included an assessment of standing balance, a timed 8-ft (2.4-m) walk at a normal pace, and a timed test of five repetitions of rising from a chair and sitting down.Results: Among the 1122 subjects who were not disabled at base line and who participated in the four-year follow-up, lower scores on the base-line performance tests were associated with a statistically significant, graduated increase in the frequency of disability in the activities of daily living and mobility-related disability at follow-up. After adjustment for age, sex, and the presence of chronic disease, those with the lowest scores on the performance tests were 4.2 to 4.9 times as likely to have disability at four years as those with the highest performance scores, and those with intermediate performance scores were 1.6 to 1.8 times as likely to have disability.Conclusions: Among nondisabled older persons living in the community, objective measures of lower-extremity function were highly predictive of subsequent disability. Measures of physical performance may identify older persons with a preclinical stage of disability who may benefit from interventions to prevent the development of frank disability.event the development of frank disability.)
Lin 2017 Neuro Oncol + (Background: Glioma is the most common form … Background: Glioma is the most common form of primary malignant brain tumor in adults, with approximately 4 cases per 100 000 people each year. Gliomas, like many tumors, are thought to primarily metabolize glucose for energy production; however, the reliance upon glycolysis has recently been called into question. In this study, we aimed to identify the metabolic fuel requirements of human glioma cells.Methods: We used database searches and tissue culture resources to evaluate genotype and protein expression, tracked oxygen consumption rates to study metabolic responses to various substrates, performed histochemical techniques and fluorescence-activated cell sorting-based mitotic profiling to study cellular proliferation rates, and employed an animal model of malignant glioma to evaluate a new therapeutic intervention.Results: We observed the presence of enzymes required for fatty acid oxidation within human glioma tissues. In addition, we demonstrated that this metabolic pathway is a major contributor to aerobic respiration in primary-cultured cells isolated from human glioma and grown under serum-free conditions. Moreover, inhibiting fatty acid oxidation reduces proliferative activity in these primary-cultured cells and prolongs survival in a syngeneic mouse model of malignant glioma.Conclusions: Fatty acid oxidation enzymes are present and active within glioma tissues. Targeting this metabolic pathway reduces energy production and cellular proliferation in glioma cells. The drug etomoxir may provide therapeutic benefit to patients with malignant glioma. In addition, the expression of fatty acid oxidation enzymes may provide prognostic indicators for clinical practice.ognostic indicators for clinical practice.)
Agrillo 2020 PLOS ONE + (Background: Humans and non-human animals s … Background: Humans and non-human animals share an approximate non-verbal system for representing and comparing numerosities that has no upper limit and for which accuracy is dependent on the numerical ratio. Current evidence indicates that the mechanism for keeping track of individual objects can also be used for numerical purposes; if so, its accuracy will be independent of numerical ratio, but its capacity is limited to the number of items that can be tracked, about four. There is, however, growing controversy as to whether two separate number systems are present in other vertebrate species.Methodology/Principal Findings: In this study, we compared the ability of undergraduate students and guppies to discriminate the same numerical ratios, both within and beyond the small number range. In both students and fish the performance was ratio-independent for the numbers 1–4, while it steadily increased with numerical distance when larger numbers were presented.Conclusions/Significance: Our results suggest that two distinct systems underlie quantity discrimination in both humans and fish, implying that the building blocks of uniquely human mathematical abilities may be evolutionarily ancient, dating back to before the divergence of bony fish and tetrapod lineages.rgence of bony fish and tetrapod lineages.)
Kaczynski FENS Forum 2010 + (Background: L-arginine (2-amino-5-guanidin … Background: L-arginine (2-amino-5-guanidino-pentanoic acid) is an important amino acid for birds, carnivores and mammals. Its metabolism is complex and is only partially known. L-arginine is a substrate for nitric oxide (NO) which penetrates freely across cell membranes. The enhanced generation of NO may reduce necrosis and apoptosis in ischemia/reperfusion-induced injury in ratliver. NO donors also protect the ischemic heart from apoptosis and mitochondrial dysfunction via PKG-mediated blockage of mitochondrial permeability transition pores and subsequenced cytochrome ''c'' release. It is anticipated that NO through cGMP-dependent mechanisms can activatesurvival paths in hippocampal neurons and prevent apoptosis.Aims: The study of the mitochondria-related antiapoptotic influence of L-arginine against proapoptotic, proinflammatory, and metabolic stressor staurosporine in human glioblastoma LN-18 (brain cell line).Methods: The cultured glioblastoma LN-18 cells were preincubated with L-arginine (L-arg; 0.1, 0.3 or 1 mM) for 24 hours and were challenged with staurosporine (STS; 0.025 microM) for the last four hours of incubation. Measurement of the mitochondrial respiration rates was performed using Oxygraph-2k (OROBOROS®). The ATP generation was followed by using luminescence method withLuciferase/Luciferine (ATP Lite, Parkin Elmer) commercial kits. Additionally the changes in the internal mitochondrial membrane potential by the high-content cell analysis confocal fluorescent microscopy which allows prolonged imaging of live cells in controlled environment (BD Pathway 855 Bioimager) are presently performed with the usage of TMRM (for active mitochondria staining) andHoechst (for nucleus staining).Results: L-arginine per se at 0.3 mM to 1 mM increased ATP generation, but this effect was reduced by the presence of the proapoptotic staurosporine.Conclusions: L-arginine seems to increase ATP generation in LN-18 cells, however this effect could not overcome the influence of staurosporine. The possible influence on mitochondrial membrane potential will be presented.Supported by the Polish-Norwegian Research Found no. PNRF-104-Al-1/07.egian Research Found no. PNRF-104-Al-1/07.)
Kaczynski 2010 FENS Abstr + (Background: L-arginine (2-amino-5-guanidin … Background: L-arginine (2-amino-5-guanidino-pentanoic acid) is an important amino acid for birds, carnivores and mammals. Its metabolism is complex and is only partially known. L-arginine is a substrate for nitric oxide (NO) which penetrates freely across cell membranes. The enhanced generation of NO may reduce necrosis and apoptosis in ischemia/reperfusion-induced injury in ratliver. NO donors also protect the ischemic heart from apoptosis and mitochondrial dysfunction via PKG-mediated blockage of mitochondrial permeability transition pores and subsequenced cytochrome c release. It is anticipated that NO through cGMP-dependent mechanisms can activatesurvival paths in hippocampal neurons and prevent apoptosis.Aims: The study of the mitochondria-related antiapoptotic influence of L-arginine against proapoptotic, proinflammatory, and metabolic stressor staurosporine in human glioblastoma LN-18 (brain cell line).Methods: The cultured glioblastoma LN-18 cells were preincubated with L-arginine (L-arg; 0.1, 0.3 or 1 mM) for 24 hours and were challenged with staurosporine (STS; 0.025 microM) for the last four hours of incubation. Measurement of the mitochondrial respiration rates was performed usingOxygraph-2k (OROBOROS®). The ATP generation was followed by using luminescence method with Luciferase/Luciferine (ATP Lite, Parkin Elmer) commercial kits. Additionally the changes in the internal mitochondrial membrane potential by the high-content cell analysis confocal fluorescent microscopy which allows prolonged imaging of live cells in controlled environment (BD Pathway 855Bioimager) are presently performed with the usage of TMRM (for active mitochondria staining) and Hoechst (for nucleus staining).Results: L-arginine per se at 0.3 mM to 1 mM increased ATP generation, but this effect was reduced by the presence of the proapoptotic staurosporine.Conclusions: L-arginine seems to increase ATP generation in LN-18 cells, however this effect could not overcome the influence of staurosporine. The possible influence on mitochondrial membrane potential will be presented.rial membrane potential will be presented.)
Petrilli 2020 medRxiv + (Background: Little is known about factors … Background: Little is known about factors associated with hospitalization and critical illness in Covid-19 positive patients. Methods: We conducted a cross-sectional analysis of all patients with laboratory-confirmed Covid-19 treated at a single academic health system in New York City between March 1, 2020 and April 2, 2020, with follow up through April 7, 2020. Primary outcomes were hospitalization and critical illness (intensive care, mechanical ventilation, hospice and/or death). We conducted multivariable logistic regression to identify risk factors for adverse outcomes, and maximum information gain decision tree classifications to identify key splitters. Results: Among 4,103 Covid-19 patients, 1,999 (48.7 %) were hospitalized, of whom 981/1,999 (49.1 %) have been discharged home, and 292/1,999 (14.6 %) have died or were discharged to hospice. Of 445 patients requiring mechanical ventilation, 162/445 (36.4 %) have died. Strongest hospitalization risks were age ≥75 years (OR 66.8, 95 % CI, 44.7-102.6), age 65-74 (OR 10.9, 95 % CI, 8.35-14.34), BMI>40 (OR 6.2, 95 % CI, 4.2-9.3), and heart failure (OR 4.3 95 % CI, 1.9-11.2). Strongest critical illness risks were admission oxygen saturation <88 % (OR 6.99, 95 % CI 4.5-11.0), d-dimer>2500 (OR 6.9, 95 % CI, 3.2-15.2), ferritin >2500 (OR 6.9, 95 % CI, 3.2-15.2), and C-reactive protein (CRP) >200 (OR 5.78, 95 % CI, 2.6-13.8). In the decision tree for admission, the most important features were age >65 and obesity; for critical illness, the most important was SpO2<88, followed by procalcitonin >0.5, troponin <0.1 (protective), age >64 and CRP>200. Conclusions: Age and comorbidities are powerful predictors of hospitalization; however, admission oxygen impairment and markers of inflammation are most strongly associated with critical illness.markers of inflammation are most strongly associated with critical illness.)
Stensvold 2012 Metab Syndr Relat Disord + (Background: Metabolic syndrome is associat … Background: Metabolic syndrome is associated with chronic low-grade inflammation, a condition thought to play a key role in the pathogenesis of the syndrome. Among a number of proinflammatory cytokines, interleukin-18 (IL-18) seems to be the best marker for inflammation among people with metabolic syndrome. The aim of this study was to examine the effect of aerobic training versus strength training on circulating IL-18 and other proinflammatory markers in people with metabolic syndrome. Methods: Thirty-one inactive men and women with metabolic syndrome were randomized to either high-intensity aerobic interval training ('''AIT''', ''n''=11), strength training ('''ST''', ''n''=10), or a control group (''n''=10). Exercise training was carried out three times per week for 12 weeks. Serum insulin, high-sensitivity C-reactive protein (hsCRP), IL-18, IL-6, and tumor necrosis factor-α (TNF-α) were measured before and after the intervention. Results: Serum IL-18 was reduced by 43% after AIT (''P''<0.001). Although there was no change in TNF-α from baseline after AIT, the levels were lower compared to the ST (''P''=0.032) and control groups (''P''=0.039) after the intervention. Total body fat was reduced after AIT (from 33.9±7.3% to 32.2±7.9%, ''P''<0.001) and ST (from 31.2±3.9% to 29.7±3.4%, ''P''=0.025). There were no changes in serum IL-6, insulin, or hsCRP within or between the groups. Conclusion: Both ST and AIT reduced fat mass. However, only the latter intervention was associated with a more favorable inflammatory status among people with metabolic syndrome. Clinical Trial Registration Information: http://clinicaltrials.gov/show/NCT00986024/ion: http://clinicaltrials.gov/show/NCT00986024/)
Huete-Ortega 2018 Biotechnol Biofuels + (Background: Microalgae accumulate lipids w … Background: Microalgae accumulate lipids when exposed to stressful conditions such as nutrient limitation that can be used to generate biofuels. Nitrogen limitation or deprivation is a strategy widely employed to elicit this response. However, this strategy is associated with a reduction in the microalgal growth, leading to overall poor lipid productivities. Here, we investigated the combined effect of a reduced source of nitrogen (ammonium) and super-saturating light intensities on the growth and induction of lipid accumulation in two model but diverse microalgal species, Phaeodactylum tricornutum and Nannochloropsis oceanica. We hypothesized that the lower energy cost of assimilating ammonium would allow the organisms to use more reductant power for lipid biosynthesis without compromising growth and that this would be further stimulated by the effect of high light (1000 µmol m-2 s-1) stress. We studied the changes in growth and physiology of both species when grown in culture media that either contained nitrate or ammonium as the nitrogen source, and an additional medium that contained ammonium with tungsten in place of molybdenum and compared this with growth in media without nitrogen. We focused our investigation on the early stages of exposure to the treatments to correspond to events relevant to induction of lipid accumulation in these two species.Results: At super-saturating light intensities, lipid productivity in P. tricornutum increased twofold when grown in ammonium compared to nitrogen free medium that increased further when tungsten was present in the medium in place of molybdenum. Conversely, N. oceanica growth and physiology was not compromised by the high light intensities used, and the use of ammonium had a negative effect on the lipid productivity, which was even more marked when tungsten was present.Conclusions: Whilst the use of ammonium and super-saturating light intensities in P. tricornutum was revealed to be a good strategy for increasing lipid biosynthesis, no changes in the lipid productivity of N. oceanica were observed, under these conditions. Both results provide relevant direction for the better design of processes to produce biofuels in microalgae by manipulating growth conditions without the need to subject them to genetic engineering manipulation. them to genetic engineering manipulation.)
Szczerbinski 2021 Cells + (Background: Mitochondrial dysfunction has … Background: Mitochondrial dysfunction has been implicated in the pathogenesis of type 2 diabetes, but its contribution to the early stages of dysglycemia remains poorly understood. By collecting a high-resolution stage-based spectrum of dysglycemia, our study fills this gap by evaluating derangement in both the function and quantity of mitochondria. We sampled mitochondria in skeletal muscle and subcutaneous adipose tissues of subjects with progressive advancement of dysglycemia under a three-month exercise intervention. Methods: We measured clinical metabolic parameters and gathered skeletal muscle and adipose tissue biopsies before and after the three-month exercise intervention. We then assayed the number of mitochondria via citrate synthase (CS) activity and functional parameters with high-resolution respirometry. Results: In muscle, there were no differences in mitochondrial quantity or function at baseline between normoglycemics and prediabetics. However, the intervention caused improvement in CS activity, implying an increase in mitochondrial quantity. By contrast in adipose tissue, baseline differences in CS activity were present, with the lowest CS activity coincident with impaired fasting glucose and impaired glucose tolerance (IFG + IGT). Finally, CS activity, but few of the functional metrics, improved under the intervention. Conclusions: We show that in prediabetes, no differences in the function or amount of mitochondria (measured by CS activity) in skeletal muscle are apparent, but in adipose tissue of subjects with IFG + IGT, a significantly reduced activity of CS was observed. Finally, metabolic improvements under the exercise correlate to improvements in the amount, rather than function, of mitochondria in both tissues.function, of mitochondria in both tissues.)
Zhang 2021 PLOS ONE + (Background: Mitochondrial dysfunction is i … Background: Mitochondrial dysfunction is involved in many complex diseases. Efficient and accurate evaluation of mitochondrial functionality is crucial for understanding pathology as well as facilitating novel therapeutic developments. As a popular platform, Seahorse extracellular flux (XF) analyzer is widely used for measuring mitochondrial oxygen consumption rate (OCR) in living cells. A hidden feature of Seahorse XF OCR data is that it has a complex data structure, caused by nesting and crossing between measurement cycles, wells and plates. Surprisingly, statistical analysis of Seahorse XF data has not received sufficient attention, and current methods completely ignore the complex data structure, impairing the robustness of statistical inference.Results: To rigorously incorporate the complex structure into data analysis, here we developed a Bayesian hierarchical modeling framework, OCRbayes, and demonstrated its applicability based on analysis of published data sets.Conclusions: We showed that OCRbayes can analyze Seahorse XF OCR experimental data derived from either single or multiple plates. Moreover, OCRbayes has potential to be used for diagnosing patients with mitochondrial diseases.sing patients with mitochondrial diseases.)
Besancon 2020 Res Integr Peer Rev + (Background: Our aim is to highlight the be … Background: Our aim is to highlight the benefits and limitations of open and non-anonymized peer review. Our argument is based on the literature and on responses to a survey on the reviewing process of alt.chi, a more or less open review track within the so-called Computer Human Interaction (CHI) conference, the predominant conference in the field of human-computer interaction. This track currently is the only implementation of an open peer review process in the field of human-computer interaction while, with the recent increase in interest in open scientific practices, open review is now being considered and used in other fields.Methods: We ran an online survey with 30 responses from alt.chi authors and reviewers, collecting quantitative data using multiple-choice questions and Likert scales. Qualitative data were collected using open questions.Results: Our main quantitative result is that respondents are more positive to open and non-anonymous reviewing for alt.chi than for other parts of the CHI conference. The qualitative data specifically highlight the benefits of open and transparent academic discussions. The data and scripts are available on https://osf.io/vuw7h/, and the figures and follow-up work on http://tiny.cc/OpenReviews.Conclusion: While the benefits are quite clear and the system is generally well-liked by alt.chi participants, they remain reluctant to see it used in other venues. This concurs with a number of recent studies that suggest a divergence between support for a more open review process and its practical implementation. process and its practical implementation.)
Qingxian 2020 Lancet + (Background: Patients with obesity are at i … Background: Patients with obesity are at increased risk of exacerbations from viral respiratory infections. However, the association of obesity with severity of corona virus disease 2019 (COVID-19) is unclear. We hereby examined this association using data from the only referral hospital in Shenzhen, China.Methods: 383 COVID-19 patients admitted from 11 January to 16 February 2020 in the Third People’s Hospital of Shenzhen, China were included. Underweight was defined by body mass index (BMI) lower than 18·5 kg/m2, normal weight by 18·5-23·9 kg/m2 , overweight by 24·0- 27·9 kg/m2 and obesity as ≥28 kg/m2.Findings: Of them, 53·1 % were normal weight, 4·2 % were underweight, 32·0 % were overweight, and 10·7 % were obese. Patients with obesity, versus without, were tended to have cough (''P''=0·03) and fever (''P''=0·06). After adjusting for potential confounders, compared to normal weight, overweight showed 86 % higher, and obesity group showed 2·42-fold higher odds of developing severe pneumonia. Despite a non-significant sex interaction was found (''P''=0·09), the association appeared to be more pronounced in men than in women. The odds ratios (95 % confidence intervals) for severe pneumonia in overweight and obesity was 1·96 (0·78-4·98) and 5·70 (1·83-17·76) in men, and 1·51 (0·57-4·01) and 0·71 (0·07-7·3) in women, respectively.Interpretation: This is the first study showing that obesity, especially in men, significantly increases the risk of developing severe pneumonia in COVID-19 patients. As the 2019n-Cov may continue to spread worldwide, clinicians should maintain a high level of attention in obese patients. Obese patients should be carefully managed with prompt and aggressive treatment.aged with prompt and aggressive treatment.)
Caspi 2020 J Am Heart Assoc + (Background: People with chronic heart fail … Background: People with chronic heart failure (CHF) experience severe skeletal muscle dysfunction, characterized by mitochondrial abnormalities, which exacerbates the primary symptom of exercise intolerance. However, the molecular triggers and characteristics underlying mitochondrial abnormalities caused by CHF remain poorly understood.Methods and Results: We recruited 28 patients with CHF caused by reduced ejection fraction and 9 controls. We simultaneously biopsied skeletal muscle from the pectoralis major in the upper limb and from the vastus lateralis in the lower limb. We phenotyped mitochondrial function in permeabilized myofibers from both sites and followed this by complete RNA sequencing to identify novel molecular abnormalities in CHF skeletal muscle. Patients with CHF presented with upper and lower limb skeletal muscle impairments to mitochondrial function that were of a similar deficit and indicative of a myopathy. Mitochondrial abnormalities were strongly correlated to symptoms. Further RNA sequencing revealed a unique transcriptome signature in CHF skeletal muscle characterized by a novel triad of differentially expressed genes related to deficits in energy metabolism including adenosine monophosphate deaminase 3, pyridine nucleotide‐disulphide oxidoreductase domain 2, and lactate dehydrogenase C.Conclusions: Our data suggest an upper and lower limb metabolic myopathy that is characterized by a unique transcriptome signature in skeletal muscle of humans with CHF.ure in skeletal muscle of humans with CHF.)
Mehta 2008 Chest + (Background: Pulmonary vasoconstriction in … Background: Pulmonary vasoconstriction in response to hypoxia is unusual inasmuch as local exposure of nonpulmonary vasculature to hypoxia results in vasodilation. It has been suggested that pulmonary artery smooth-muscle cells may relax in response to intracellular generation of reactive oxygen species (ROS) and that the production of ROS decreases under hypoxia. However, other workers report increased ROS production in human pulmonary artery smooth-muscle cells (HPASMC) during hypoxia.Methods: Using dihydrodichlorofluorescein diacetate, dihydroethidium, and Amplex Red (Molecular Probes; Eugene, OR), we estimated ROS generation by confluent primary cultures of HPASMC and human coronary artery smooth-muscle cells (HCASMC) under normoxia (20%) and acute hypoxia (5%).Results: All three assay systems showed that HPASMC production of ROS is decreased under hypoxia and to a greater extent than the decrease in ROS production by HCASMC. A substantially greater percentage of normoxic ROS production by HPASMC is mitochondrial (> 60%) compared to HCASMC (< 30%).Conclusions: These results support the conclusion that ROS generation decreases, rather than increases, in HPASMC during hypoxia. However, as ROS production also decreases in HCASMC during hypoxia, the reason for the opposite change in vascular tone is not yet apparent.ite change in vascular tone is not yet apparent.)
Liu 2009 J Biomed Sci + (Background: Reactive oxygen species (ROS) … Background: Reactive oxygen species (ROS) play an important role in aging and age-related diseases such as Parkinson's disease and Alzheimer's disease. Much of the ROS production under conditions of toxic stress is from mitochondria, and multiple antioxidants prevent ROS accumulation. The aim of this study is to examine the specificity of the interaction between the antioxidants and ROS production in stressed cells.Methods: Using fluorescent dyes for ROS detection and mitochondrial inhibitors of known specificities, we studied ROS production under three conditions where ROS are produced by mitochondria: oxidative glutamate toxicity, state IV respiration induced by oligomycin, and tumor necrosis factor-induced cell death.Results: We demonstrated that there are at least four mitochondrial ROS-generating sites in cells, including the flavin mononucleotide (FMN) group of complex I and the three ubiquinone-binding sites in complexes I, II and III. ROS production from these sites is modulated in an insult-specific manner and the sites are differentially accessible to common antioxidants.Conclusion: The inhibition of ROS accumulation by different antioxidants is specific to the site of ROS generation as well as the antioxidant. This information should be useful for devising new interventions to delay aging or treat ROS-related diseases.delay aging or treat ROS-related diseases.)
Pollack 2017 J Gerontol A Biol Sci Med Sci + (Background: Resveratrol, a plant-derived p … Background: Resveratrol, a plant-derived polyphenol, has been reported to improve glucose metabolism and vascular function and to extend life span in animal models, but studies in humans have been inconclusive.Methods: In a randomized, double-blind crossover study, we treated older glucose-intolerant adults (''N'' = 30) with resveratrol (2-3 g/daily) or placebo, each for 6 weeks. A standard mixed-meal test was used to assess insulin sensitivity (Matsuda index) and secretion (C-peptide deconvolution) and vascular function by reactive hyperemia peripheral arterial tonometry. Skeletal muscle samples were obtained for gene expression using RNA-Seq analysis and to assess mitochondrial morphology.Results: There were no changes in glucose tolerance, insulin sensitivity, weight, blood pressure, or lipid profile following resveratrol treatment. Fasting reactive hyperemia index improved with resveratrol (2.02 ± 0.2 vs 1.76 ± 0.02, p = .002). RNA-Seq analysis yielded 140 differentially expressed transcripts (corrected p-value ≤ .05), predominantly associated with mitochondrial genes and noncoding RNA. Ingenuity Pathway Analysis confirmed that mitochondrial dysfunction (p = 2.77 × 10-12) and oxidative phosphorylation (p = 1.41 × 10-11) were the most significantly perturbed pathways. Mitochondrial number, but not size, was increased.Conclusions: Resveratrol treatment of older adults with impaired glucose regulation may have beneficial effects on vascular function, but not glucose metabolism or insulin sensitivity. Changes in gene expression suggest effects similar to those observed with caloric restriction, which has been shown to increase life and health span in animal models, although its significance for humans is uncertain. Future human studies should address the appropriate dose range and low bioavailability of resveratrol.© The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: [email protected].ease e-mail: [email protected].)
Aya 2022 Eur J Pharmacol + (Background: Sodium-glucose cotransporter 2 … Background: Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been demonstrated to have beneficial effects on HF in large clinical trials; however, the mechanisms remain to be elucidated. The aim of this study was to clarify the mechanisms by which empagliflozin, one of SGLT2 inhibitors, affects heart failure.Method and results: Eight-week-old male mice deficient for heart and skeletal muscle-specific manganese superoxide dismutase (MnSOD-cKO mice), a murine model of dilated cardiomyopathy, were given food mixed with or without 10 mg/kg empagliflozin for 7 weeks and evaluated. Both the survival rate and cardiac fibrosis were significantly improved in the empagliflozin group. The capacity for oxidative phosphorylation in cardiac mitochondria was significantly upregulated as measured with Oxygraph-2k respirometer, and blood lactate levels produced by anaerobic metabolism were significantly lower in the empagliflozin group. Energy expenditure was significantly improved in the empagliflozin group, measured by respiratory gas analysis, with a concomitant reduction in serum leptin concentration and increase in food intake. A moderate amount of glucose was excreted in urine in the empagliflozin group; however, the available energy substrate in the body nonetheless expanded because of the much higher caloric intake.Conclusions: We conclude that empagliflozin improved cardiac mitochondrial function and upregulated energy metabolism even in HF in mice. These findings provide novel mechanisms for the beneficial effects of SGLT2 inhibitors on HF.eficial effects of SGLT2 inhibitors on HF.)
Cronshaw 2019 Photobiomodul Photomed Laser Surg + (Background: The clinical therapeutic benef … Background: The clinical therapeutic benefits of Photobiomodulation (PBM) therapy have been well established in many clinical scenarios. However, we are far from having developed a complete understanding of the underlying mechanisms of photon-biological tissue interactions. Concurrent to ongoing PBM studies, there are several parallel fields with evidences from cell and tissue physiology such as evolutionary biology, photobiology, and microbiology among others. Objective: This review is focused on extrapolating evidences from an expanded range of studies that may contribute to a better understanding of PBM mechanisms especially focusing on analgesia. Further, the choice of a PBM device source and relevant dosimetry with regards to specific mechanisms are discussed to enable broader clinical use of PBM therapies. Materials and methods: This discussion article is referenced from an expanded range of peer reviewed publications, including literature associated with evolutionary biology, microbiology, oncology, and photo-optical imaging technology, amongst others. Results and discussion: Materials drawn from many disparate disciplines is described. By inference from the current evidence base, a novel theory is offered to partially explain the cellular basis of PBM-induced analgesia. It is proposed that this may involve the activity of a class of transmembrane proteins known as uncoupling proteins. Furthermore, it is proposed that this may activate the heat stress protein response and that intracellur microthermal inclines may be of significance in PBM analgesia. It is suggested that the PBM dose response as a simple binary model of PBM effects as represented by the Arndt-Schulz law is clinically less useful than a multiphasic biological response. Finally, comments are made concerning the nature of photon to tissue interaction that can have significance in regard to the effective choice and delivery of dose to clinical target. Conclusions: It is suggested that a re-evaluation of phototransduction pathways may lead to an improvement in outcome in phototheraphy. An enhanced knowledge of safe parameters and a better knowledge of the mechanics of action at target level will permit more reliable and predictable clinical gain and assist the acceptance of PBM therapy within the wider medical community.herapy within the wider medical community.)
Ward 2015 Abstract IOC106 + (Background: The heart is a highly aerobic … Background: The heart is a highly aerobic organ with more than 90% of ATP regenerated by oxidative phosphorylation (OXPHOS) in the mitochondria. Mitochondrial dysfunction has been identified as a hallmark in the transition of compensatory hypertrophy to heart failure. However, the contribution of mitochondrial dysfunction to the contractile deficit is debated.Objectives: To determine if mitochondrial energy supply compromises contractile function in right ventricular (RV) hypertrophy.Methods: Rats were injected with monocrotaline (MCT) to induce pulmonary artery hypertension and RV hypertrophy, or saline (CON) for age-matched controls. Four weeks post-injection, multicellular cardiac trabeculae (length 2-3 mm, diameter 150-250 µm) were micro-dissected from the RV and mounted on an inverted microscope between a force transducer and a length changer. Steady-state force and intracellular Ca2+ transients were measured prior to saponin "skinning" of the sarcolemma to allow buffer access to the cytosol without damaging organelle membranes. Contraction and relaxation of the trabeculae was then assessed using buffered Ca2+ solutions, with and without exogenous ATP added to the superfusate.Results: MCT trabeculae produced similar force to CON despite having lower Ca2+ transients. Following skinning, CON trabeculae showed no change in the maximum Ca2+-activated force when exogenous ATP was removed from superfusate, while MCT trabeculae showed smaller contractures without exogenous ATP when stimulated with saturating Ca2+.Discussion: In this MCT model of compensated right ventricular hypertrophy there appears to be only a small contribution of mitochondrial dysfunction to contraction/relaxation when intracellular Ca2+ is controlled. This protocol can be used to further examine energy specific deficits in the failing heart, and to investigate the effects of drugs that modulate mitochondrial energy supply on contractile function. heart, and to investigate the effects of drugs that modulate mitochondrial energy supply on contractile function.)
Bociaga-Jasik 2013 Pharmacol Rep + (Background: The iatrogenic, HIV-related li … Background: The iatrogenic, HIV-related lipodystrophy is associated with development of the significant metabolic and cardiovascular complications. The underlying mechanisms of antiretroviral (ARV) drugs are not completely explored. Methods: The aim of the study was to characterize effects of the protease inhibitor (PI) - saquinavir (SQV) on metabolic functions, and gene expression during differentiation in cells (Chub-S7) culture. Results: SQV in concentrations observed during antiretroviral therapy (ART) significantly decreased mitochondrial membrane potential (MMP), oxygen consumption and ATP generation. The effects were greater in already differentiated cells. This was accompanied by characteristic changes in the expression of the genes involved in endoplasmic reticulum (ER) stress, and differentiation (lipid droplet formation) process such as: WNT10a, C/EBPa, AFT4, CIDEC, ADIPOQ, LPIN1. Conclusions: The results indicate that SQV affects not only metabolic (mitochondrial) activity of adipocytes, but affects the expression of genes related to differentiation and to a lesser extent to cell apoptosis. and to a lesser extent to cell apoptosis.)
Wohlwend 2013 Thesis + (Background: The mechanistically relation b … Background: The mechanistically relation between low oxygen metabolism and poor health remains unresolved.Methods: To pursue this aspect further, we measured mitochondrial oxidative phosphorylation (OXPHOS) capacity in permeabilized fibres of gastrocnemius (GASTRO) and left ventricle (LV) of the heart in 22 female rats artificially inbred for low- and high running capacity (LCR; HCR, respectively) for 30 generations. The rats were randomized to either sedate (LCRsed; HCRsed) or aerobic interval training (AIT) sessions 5 times a week for 1 month and then 2 times a week for 8 months (LCRext; HCRext).Results: There was a significant effect of training and inbreeding on maximal oxygen uptake in these rats. Baseline results for GASTRO in LCRsed compared to HCRsed showed reduced fat oxidation, CI-, CII linked respiration and maximal OXPHOS (CI- and CII linked respiration). Activity of the TCA cycle enzyme citrate synthase (CS) was lower in LCR compared to HCR. Mitochondrial content independent calculations indicated an enzyme defect in β-oxidation, and that mitochondrial coupling efficiency of electron transfer during β-oxidationwas impaired in LCRsed compared to HCRsed. AIT improved all these variables such that there was no difference in fat oxidation, CI-, CII linked respiration or maximal OXPHOS between LCRext and HCRext. These improvements were likely due to an increase in mitochondrial density, but also qualitative improvementsparticularly in fat oxidation (coupling efficiency and relative flux) were found.Baseline results for LV in LCRsed compared to HCRsed showed reduced CII linked respiration, maximal OXPHOS and similar activity of CS in LCRsed compared to HCRsed. Flux ratios as well as mitochondrial coupling efficiency during β-oxidation were similar between LCRsed and HCRsed. AIT improved maximalOXPHOS such that there was no difference between LCRext and HCRext. Interestingly, AIT had no effect on CS-activity in neither LCR nor HCR, suggesting primarily qualitative adjustments to exercise training in heart,mainly within β-oxidation and CII linked respiration. There was no dyscoupling effect as a result of phosphorylative constraint on electron transfer through complex I-IV by ATPsynthase in GASTRO or in LV, suggesting that ET-pathway rather than the phosphorylation system is limiting maximal ATP production in rats.Conclusions: Sedentary rats that contrast in intrinsic low- and high aerobic capacity differ significantly in OXHPOS, mitochondrial coupling efficiency and coupling control in GASTRO as well as in maximal OXPHOS in LV. Nine months of AIT was able to reverse all these initial impairments of mitochondrial function both in the heart and in the periphery, possibly through an interplay of different mechanisms. These findings might explain some of the poor health features of low capacity rats and suggest training-induced plasticity.s and suggest training-induced plasticity.)
Bilan 2014 Biochim Biophys Acta + (Background: The ratio of NAD(+)/NADH is a … Background: The ratio of NAD(+)/NADH is a key indicator that reflects the overall redox state of the cells. Until recently, there were no methods for real time NAD(+)/NADH monitoring in living cells. Genetically encoded fluorescent probes for NAD(+)/NADH are fundamentally new approach for studying the NAD(+)/NADH dynamics.Methods: We developed a genetically encoded probe for the nicotinamide adenine dinucleotide, NAD(H), redox state changes by inserting circularly permuted YFP into redox sensor T-REX from Thermus aquaticus. We characterized the sensor in vitro using spectrofluorometry and in cultured mammalian cells using confocal fluorescent microscopy.Results: The sensor, named RexYFP, reports changes in the NAD(+)/NADH ratio in different compartments of living cells. Using RexYFP, we were able to track changes in NAD(+)/NADH in cytoplasm and mitochondrial matrix of cells under a variety of conditions. The affinity of the probe enables comparison of NAD(+)/NADH in compartments with low (cytoplasm) and high (mitochondria) NADH concentration. We developed a method of eliminating pH-driven artifacts by normalizing the signal to the signal of the pH sensor with the same chromophore.Conclusion: RexYFP is suitable for detecting the NAD(H) redox state in different cellular compartments.General significance: RexYFP has several advantages over existing NAD(+)/NADH sensors such as smallest size and optimal affinity for different compartments. Our results show that normalizing the signal of the sensor to the pH changes is a good strategy for overcoming pH-induced artifacts in imaging.vercoming pH-induced artifacts in imaging.)
Lettieri-Barbato 2019 Mol Metab + (Background: Thermogenic adipocytes reorgan … Background: Thermogenic adipocytes reorganize their metabolism during cold exposure. Metabolic reprogramming requires readily available bioenergetics substrates, such as glucose and fatty acids, to increase mitochondrial respiration and produce heat via the uncoupling protein 1 (UCP1). This condition generates a finely-tuned production of mitochondrial reactive oxygen species (ROS) that support non-shivering thermogenesis.Scope of review: Herein, the findings underlining the mechanisms that regulate ROS production and control of the adaptive responses tuning thermogenesis in adipocytes are described. Furthermore, this review describes the metabolic responses to substrate availability and the consequence of mitochondrial failure to switch fuel oxidation in response to changes in nutrient availability. A framework to control mitochondrial ROS threshold to maximize non-shivering thermogenesis in adipocytes is provided.Major conclusions: Thermogenesis synchronizes fuel oxidation with an acute and transient increase of mitochondrial ROS that promotes the activation of redox-sensitive thermogenic signaling cascade and UCP1. However, an overload of substrate flux to mitochondria causes a massive and damaging mitochondrial ROS production that affects mitochondrial flexibility. Finding novel thermogenic redox targets and manipulating ROS concentration in adipocytes appears to be a promising avenue of research for improving thermogenesis and counteracting metabolic diseases.esis and counteracting metabolic diseases.)
Mikulas 2020 Materials + (Background: Triethylene glycol dimethacryl … Background: Triethylene glycol dimethacrylate (TEGDMA) monomers released from resin matrix are toxic to dental pulp cells, induce apoptosis, oxidative stress and decrease viability. Recently, mitochondrial complex I (CI) was identified as a potential target of TEGDMA. In isolated mitochondria supported by CI, substrates oxidation and ATP synthesis were inhibited, reactive oxygen species production was stimulated. Contrary to that, respiratory Complex II was not impaired by TEGDMA. The beneficial effects of electron carrier compound methylene blue (MB) are proven in many disease models where mitochondrial involvement has been detected. In the present study, the bioenergetic effects of MB on TEGDMA-treated isolated mitochondria and on human dental pulp stem cells (DPSC) were analyzed.Methods: Isolated mitochondria and DPSC were acutely exposed to low millimolar concentrations of TEGDMA and 2 μM concentration of MB. Mitochondrial and cellular respiration and glycolytic flux were measured by high resolution respirometry and by Seahorse XF extracellular analyzer. Mitochondrial membrane potential was measured fluorimetrically.Results: MB partially restored the mitochondrial oxidation, rescued membrane potential in isolated mitochondria and significantly increased the impaired cellular O2 consumption in the presence of TEGDMA.Conclusion: MB is able to protect against TEGDMA-induced CI damage, and might provide protective effects in resin monomer exposed cells.Copyright © 2018. Published by Elsevier Inc.pyright © 2018. Published by Elsevier Inc.)
Matsumoto 2021 Circ Heart Fail + (Background: We recently reported that trea … Background: We recently reported that treatment with rhBDNF (recombinant human brain-derived neurotrophic factor) improved the reduced exercise capacity of mice with heart failure (HF) after myocardial infarction (MI). Since BDNF is reported to enhance fatty acid oxidation, we herein conducted an in vivo investigation to determine whether the improvement in exercise capacity is due to the enhancement of the fatty acid oxidation of skeletal muscle via the AMPKα-PGC1α (adenosine monophosphate-activated protein kinase-ɑ-proliferator-activated receptor-r coactivator-1ɑ) axis.Methods: MI and sham operations were conducted in C57BL/6J mice. Two weeks postsurgery, we randomly divided the MI mice into groups treated with rhBDNF or vehicle for 2 weeks. AMPKα-PGC1α signaling and mitochondrial content in the skeletal muscle of the mice were evaluated by Western blotting and transmission electron microscopy. Fatty acid β-oxidation was examined by high-resolution respirometry using permeabilized muscle fiber. BDNF-knockout mice were treated with 5-aminoimidazole-4-carboxamide-1-beta-d-riboruranoside, an activator of AMPK.Results: The rhBDNF treatment significantly increased the expressions of phosphorylated AMPKα and PGC1α protein and the intermyofibrillar mitochondrial density in the MI mice. The lowered skeletal muscle mitochondrial fatty acid oxidation was significantly improved in the rhBDNF-treated MI mice. The reduced exercise capacity and mitochondrial dysfunction of the BDNF-knockout mice were improved by 5-aminoimidazole-4-carboxamide-1-beta-d-riboruranoside.Conclusions: Beneficial effects of BDNF on the exercise capacity of mice with HF are mediated through an enhancement of fatty acid oxidation via the activation of AMPKα-PGC1α in skeletal muscle. BDNF may become a therapeutic option to improve exercise capacity as an alternative or adjunct to exercise training.ternative or adjunct to exercise training.)
Zucker 2020 Biol Sex Differ + (Background: Women experience adverse drug … Background: Women experience adverse drug reactions, ADRs, nearly twice as often as men, yet the role of sex as a biological factor in the generation of ADRs is poorly understood. Most drugs currently in use were approved based on clinical trials conducted on men, so women may be overmedicated. We determined whether sex differences in drug pharmacokinetics, PKs, predict sex differences in ADRs.Methods: Searches of the ISI Web of Science and PubMed databases were conducted with combinations of the terms: drugs, sex or gender, pharmacokinetics, pharmacodynamics, drug safety, drug dose, and adverse drug reaction, which yielded over 5000 articles with considerable overlap. We obtained information from each relevant article on significant sex differences in PK measures, predominantly area under the curve, peak/maximum concentrations, and clearance/elimination rates. ADRs were identified from every relevant article and recorded categorically as female-biased, male-biased, or not sex-biased.Results: For most of the FDA-approved drugs examined, elevated blood concentrations and longer elimination times were manifested by women, and these PKs were strongly linked to sex differences in ADRs. Of the 86 drugs evaluated, 76 had higher PK values in women; for 59 drugs with clinically identifiable ADRs, sex-biased PKs predicted the direction of sex-biased ADRs in 88 % of cases. Ninety-six percent of drugs with female-biased PK values were associated with a higher incidence of ADRs in women than men, but only 29 % of male-biased PKs predicted male-biased ADRs. Accessible PK information is available for only a small fraction of all drugs.Conclusions: Sex differences in pharmacokinetics strongly predict sex-specific ADRs for women but not men. This sex difference was not explained by sex differences in body weight. The absence of sex-stratified PK information in public records for hundreds of drugs raises the concern that sex differences in PK values are widespread and of clinical significance. The common practice of prescribing equal drug doses to women and men neglects sex differences in pharmacokinetics and dimorphisms in body weight, risks overmedication of women, and contributes to female-biased adverse drug reactions. We recommend evidence-based dose reductions for women to counteract this sex bias.ons for women to counteract this sex bias.)
Forte 2019 Biochim Biophys Acta Bioenerg + (Bacteria can not only encounter carbon mon … Bacteria can not only encounter carbon monoxide (CO) in their habitats but also produce the gas endogenously. Bacterial respiratory oxidases, thus, represent possible targets for CO. Accordingly, host macrophages were proposed to produce CO and release it into the surrounding microenvironment to sense viable bacteria through a mechanism that in ''Escherichia'' (''E.'') ''coli'' was suggested to involve the targeting of a bd-type respiratory oxidase by CO. The aerobic respiratory chain of ''E. coli'' possesses three terminal quinol:O2-oxidoreductases: the heme-copper oxidase bo3 and two copper-lacking bd-type oxidases, bd-I and bd-II. Heme-copper and bd-type oxidases differ in the mechanism and efficiency of proton motive force generation and in resistance to oxidative and nitrosative stress, cyanide and hydrogen sulfide. Here, we investigated at varied O2 concentrations the effect of CO gas on the O2 reductase activity of the purified cytochromes bo3, bd-I and bd-II of ''E. coli''. We found that CO, in competition with O2, reversibly inhibits the three enzymes. The inhibition constants Ki for the bo3, bd-I and bd-II oxidases are 2.4 ± 0.3, 0.04 ± 0.01 and 0.2 ± 0.1 μM CO, respectively. Thus, in ''E. coli'', bd-type oxidases are more sensitive to CO inhibition than the heme-copper cytochrome bo3. The possible physiological consequences of this finding are discussed.Copyright © 2019 Elsevier B.V. All rights reserved.The possible physiological consequences of this finding are discussed. Copyright © 2019 Elsevier B.V. All rights reserved.)
Luef 2015 Nat Commun + (Bacteria from phyla lacking cultivated rep … Bacteria from phyla lacking cultivated representatives are widespread in natural systems and some have very small genomes. Here we test the hypothesis that these cells are small and thus might be enriched by filtration for coupled genomic and ultrastructural characterization. Metagenomic analysis of groundwater that passed through a ~0.2-μm filter reveals a wide diversity of bacteria from the WWE3, OP11 and OD1 candidate phyla. Cryogenic transmission electron microscopy demonstrates that, despite morphological variation, cells consistently have small cell size (0.009±0.002 μm3). Ultrastructural features potentially related to cell and genome size minimization include tightly packed spirals inferred to be DNA, few densely packed ribosomes and a variety of pili-like structures that might enable inter-organism interactions that compensate for biosynthetic capacities inferred to be missing from genomic data. The results suggest that extremely small cell size is associated with these relatively common, yet little known organisms.h these relatively common, yet little known organisms.)
Kaila 2021 Nat Rev Microbiol + (Bacteria power their energy metabolism usi … Bacteria power their energy metabolism using membrane-bound respiratory enzymes that capture chemical energy and transduce it by pumping protons or Na+ ions across their cell membranes. Recent breakthroughs in molecular bioenergetics have elucidated the architecture and function of many bacterial respiratory enzymes, although key mechanistic principles remain debated. In this Review, we present an overview of the structure, function and bioenergetic principles of modular bacterial respiratory chains and discuss their differences from the eukaryotic counterparts. We also discuss bacterial supercomplexes, which provide central energy transduction systems in several bacteria, including important pathogens, and which could open up possible avenues for treatment of disease.possible avenues for treatment of disease.)
MiPNet28.08 Oroboros O2k Series J manual + (Baglivo E, Grings M, Gnaiger E (2023) Mitochondr Physiol Network 28.08(02)1-22.)
Scott 2009 Am J Physiol Regul Integr Comp Physiol + (Bar-headed geese fly at altitudes of up to … Bar-headed geese fly at altitudes of up to 9,000 m on their biannual migration over the Himalayas. To determine whether the flight muscle of this species has evolved to facilitate exercise at high altitude, we compared the respiratory properties of permeabilized muscle fibers from bar-headed geese and several low-altitude waterfowl species. Respiratory capacities were assessed for maximal ADP stimulation (with single or multiple inputs to the electron transport system) and cytochrome oxidase excess capacity (with an exogenous electron donor) and were generally 20–40% higher in bar-headed geese when creatine was present. When respiration rates were extrapolated to the entire pectoral muscle mass, bar-headed geese had a higher mass-specific aerobic capacity. This may represent a surplus capacity that counteracts the depressive effects of hypoxia on mitochondrial respiration. However, there were no differences in activity for mitochondrial or glycolytic enzymes measured in homogenized muscle. The [ADP] leading to half-maximal stimulation (''K''m) was approximately twofold higher in bar-headed geese (10 vs. 4–6 µM), and, while creatine reduced ''K''m by 30% in this species, it had no effect on ''K''m in low-altitude birds. Mitochondrial creatine kinase may therefore contribute to the regulation of oxidative phosphorylation in flight muscle of bar-headed geese, which could promote efficient coupling of ATP supply and demand. However, this was not based on differences in creatine kinase activity in isolated mitochondria or homogenized muscle. The unique differences in bar-headed geese existed without prior exercise or hypoxia exposure and were not a result of phylogenetic history, and may, therefore, be important evolutionary specializations for high-altitude flight.therefore, be important evolutionary specializations for high-altitude flight.)
Scott 2009 Proc Biol Sci + (Bar-headed geese migrate over the Himalaya … Bar-headed geese migrate over the Himalayas at up to 9000 m elevation, but it is unclear how they sustain the high metabolic rates needed for flight in the severe hypoxia at these altitudes. To better understand the basis for this physiological feat, we compared the flight muscle phenotype of bar-headed geese with that of low altitude birds (barnacle geese, pink-footed geese, greylag geese and mallard ducks). Bar-headed goose muscle had a higher proportion of oxidative fibres. This increased muscle aerobic capacity, because the mitochondrial volume densities of each fibre type were similar between species. However, bar-headed geese had more capillaries per muscle fibre than expected from this increase in aerobic capacity, as well as higher capillary densities and more homogeneous capillary spacing. Their mitochondria were also redistributed towards the subsarcolemma (cell membrane) and adjacent to capillaries. These alterations should improve O2 diffusion capacity from the blood and reduce intracellular O2 diffusion distances, respectively. The unique differences in bar-headed geese were much greater than the minor variation between low altitude species and existed without prior exercise or hypoxia exposure, and the correlation of these traits to flight altitude was independent of phylogeny. In contrast, isolated mitochondria had similar respiratory capacities, O2 kinetics and phosphorylation efficiencies across species. Bar-headed geese have therefore evolved for exercise in hypoxia by enhancing the O2 supply to flight muscle.or exercise in hypoxia by enhancing the O2 supply to flight muscle.)
Douros 2019 JCI Insight + (Bariatric surgeries including vertical sle … Bariatric surgeries including vertical sleeve gastrectomy (VSG) ameliorate obesity and diabetes. Weight-loss and accompanying increases to insulin sensitivity contribute to improved glycemia after surgery, however, studies in humans also suggest weight-independent actions of bariatric procedures to lower blood glucose, possibly by improving insulin secretion. To evaluate this hypothesis, we compared VSG operated mice with pair-fed, sham-surgical controls (PF-Sham) 2 weeks after surgery. This paradigm yielded similar post-operative body weight and insulin sensitivity between VSG and calorically restricted PF-Sham animals. However, VSG improved glucose tolerance and markedly enhanced insulin secretion during oral nutrient and intraperitoneal glucose challenges compared to controls. Islets from VSG mice displayed a unique transcriptional signature enriched for genes involved in Ca2+ signaling and insulin secretion pathways. This finding suggests that bariatric surgery leads to intrinsic changes within the islet that alter function. Indeed, islets isolated from VSG mice had increased glucose-stimulated insulin secretion and a left-shifted glucose sensitivity curve compared to islets from PF-Sham mice. Isolated islets from VSG animals showed corresponding increases in the pulse duration of glucose-stimulated Ca2+ oscillations. Together these findings demonstrate a weight-independent improvement in glycemic control following VSG, which is, in part, driven by improved insulin secretion and associated with substantial changes in islet gene expression. These results support a model in which β-cells play a key role in the adaptation to bariatric surgery and the improved glucose tolerance that is typical of these procedures.he improved glucose tolerance that is typical of these procedures.)
West 1999 J Appl Physiol + (Barometric pressures (PB) near the summit … Barometric pressures (PB) near the summit of Mt. Everest (altitude 8, 848 m) are of great physiological interest because the partial pressure of oxygen is very near the limit for human survival. Until recently, the only direct measurement on the summit was 253 Torr, which was obtained in October 1981, but, despite being only one data point, this value has been used by several investigators. Recently, two new studies were carried out. In May 1997, another direct measurement on the summit was within approximately 1 Torr of 253 Torr, and meteorologic data recorded at the same time from weather balloons also agreed closely. In the summer of 1998, over 2,000 measurements were transmitted from a barometer placed on the South Col (altitude 7,986 m). The mean PB values during May, June, July, and August were 284, 285, 286, and 287 Torr, respectively, and there was close agreement with the PB-altitude (h) relationship determined from the 1981 data. The PB values are well predicted from the equation PB = exp (6.63268 - 0.1112 h - 0.00149 h2), where h is in kilometers. The conclusion is that on days when the mountain is usually climbed, during May and October, the summit pressure is 251-253 Torr.ober, the summit pressure is 251-253 Torr.)
Chicco 2016c Abstract MitoFit Science Camp 2016 + (Barth Syndrome (3-methylglutaconic aciduri … Barth Syndrome (3-methylglutaconic aciduria type II; BTHS) is a childhood onset cardioskeletal myopathy that results from mutations in the tafazzin gene encoding a phospholipid transacylase responsible for remodeling cardiolipin in the inner mitochondrial membrane. Cardiolipin is known to be required for optimal function and assembly of respiratory supercomplexes in the inner membrane, but precisely how loss of tafazzin function impairs mitochondrial respiratory function leading to BTHS is unclear. We utilized high-resolution respirometry (HHR) with a variety of substrate combinations to investigate the sites of cardiac mitochondrial dysfunction in the tafazzin shRNA (Taz) mouse model of BTHS, which exhibits ~90% tafazzin deficiency and cardiolipin abnormalities characteristic of BTHS in humans. Initial HRR studies revealed 50% lower rates of Complex I (CI)-linked OXPHOS respiration in Taz mitochondria compared to wild-type (WT) controls using pyruvate & malate as substrates, while succinate (CII)-supported OXPHOS and maximal enzymatic capacities of complexes I, II-IV and IV were only suppressed by 12-20%. Surprisingly, CI-linked OXPHOS supported by glutamate & malate was 50% higher in Taz, approximating rates of maximal pyruvate-supported OXPHOS in WT, arguing against CI as a primary site of OXPHOS limitation in Taz. To investigate fatty acid-supported OXPHOS, long- (16:0; palmitate) and medium-chain (8:0; octanoate) fatty acids were supplied bound to carnitine (CPT1-independent) or CoA (CPT1-dependent) to address effects on mitochondrial fatty acid transport, activation and acyl-CoA dehydrogenase isozyme-specific function [1]. Results demonstrated significant impairment of respiration supported by both medium and long-chain acyl-carnitines in Taz compared to WT mitochondria, which was blunted when palmitoyl-CoA & carnitine were used as substrates. Interestingly, metabolomic analysis of cardiac tissues revealed an 41% decrease in pantothenic acid that corresponded to a similar loss of mitochondrial CoA content in Taz compared to WT hearts. To test the hypothesis that CoA deficiency limits pyruvate and fatty acid oxidation in Taz, mitochondria were pre-incubated with 100 μM CoA to restore levels prior to repeating HRR experiments with pyruvate or palmitoylcarnitine (& malate). This increased CoA content in both Taz and WT mitochondria and partially rescued OXPHOS supported by substrates to near WT levels, despite having no significant effect on OXPHOS rates with either substrate in WT.ficant effect on OXPHOS rates with either substrate in WT.)
Johnson 2018 J Mol Cell Cardiol + (Barth Syndrome (BTHS) is an X-linked reces … Barth Syndrome (BTHS) is an X-linked recessive disorder characterized by cardiomyopathy and muscle weakness. The underlying cause of BTHS is a mutation in the tafazzin (TAZ) gene, a key enzyme of cardiolipin biosynthesis. The lack of CL arising from loss of TAZ function results in destabilization of the electron transport system, promoting oxidative stress that is thought to contribute to development of cardioskeletal myopathy. Indeed, ''in vitro'' studies demonstrate that mitochondria-targeted antioxidants improve contractile capacity in TAZ-deficient cardiomyocytes. The purpose of the present study was to determine if resolving mitochondrial oxidative stress would be sufficient to prevent cardiomyopathy and skeletal myopathy ''in vivo'' using a mouse model of BTHS. To this end we crossed mice that overexpress catalase in the mitochondria (MCAT mice) with TAZ-deficient mice (TAZKD) to produce TAZKD mice that selectively overexpress catalase in the mitochondria (TAZKD+MCAT mice). TAZKD+MCAT mice exhibited decreased mitochondrial H2O2 emission and lipid peroxidation compared to TAZKD littermates, indicating decreased oxidative stress. Despite the improvements in oxidative stress, TAZKD+MCAT mice developed cardiomyopathy and mild muscle weakness similar to TAZKD littermates. These findings indicate that resolving oxidative stress is not sufficient to suppress cardioskeletal myopathy associated with BTHS.fficient to suppress cardioskeletal myopathy associated with BTHS.)
Kutschka 2023 Basic Res Cardiol + (Barth Syndrome (BTHS) is an inherited card … Barth Syndrome (BTHS) is an inherited cardiomyopathy caused by defects in the mitochondrial transacylase TAFAZZIN (Taz), required for the synthesis of the phospholipid cardiolipin. BTHS is characterized by heart failure, increased propensity for arrhythmias and a blunted inotropic reserve. Defects in Ca2+-induced Krebs cycle activation contribute to these functional defects, but despite oxidation of pyridine nucleotides, no oxidative stress developed in the heart. Here, we investigated how retrograde signaling pathways orchestrate metabolic rewiring to compensate for mitochondrial defects. In mice with an inducible knockdown (KD) of TAFAZZIN, and in induced pluripotent stem cell-derived cardiac myocytes, mitochondrial uptake and oxidation of fatty acids was strongly decreased, while glucose uptake was increased. Unbiased transcriptomic analyses revealed that the activation of the eIF2α/ATF4 axis of the integrated stress response upregulates one-carbon metabolism, which diverts glycolytic intermediates towards the biosynthesis of serine and fuels the biosynthesis of glutathione. In addition, strong upregulation of the glutamate/cystine antiporter xCT increases cardiac cystine import required for glutathione synthesis. Increased glutamate uptake facilitates anaplerotic replenishment of the Krebs cycle, sustaining energy production and antioxidative pathways. These data indicate that ATF4-driven rewiring of metabolism compensates for defects in mitochondrial uptake of fatty acids to sustain energy production and antioxidation. acids to sustain energy production and antioxidation.)
Claiborne 2013 Thesis + (Barth Syndrome is a mitochondrial disease … Barth Syndrome is a mitochondrial disease associated with exercise intolerance andcardioskeletal myopathy resulting from mutations in the tafazzin (taz) gene. The present studycharacterized skeletal muscle mitochondrial function and exercise capacity of a taz shRNAmouse model of Barth Syndrome (90% taz-deficient), and examined the effect of exercisetraining on these parameters. Mitochondrial respiratory function was assessed, in mitochondriafreshly isolated from hindlimb muscles, using an Oroboros O2K respirometer with pyruvate +malate as substrates, oligomycin as an ATP synthase inhibitor, and carbonyl cyanide 4-(trifluoromethoxy) phenylhydrazone (FCCP) to establish maximal activity. A pre-training GXTrevealed profound exercise intolerance, which corresponded to reduced respiratory capacity,citrate synthase (CS) and ETC complex 1 protein content of muscle mitochondria in the taz vs.age-matched wild-type (WT) mice. Based on the pre-training GXT, exercise training wasconducted at 12-17 m/min, 0% grade for 60 min/d, 5d/wk, for 4 wks. Exercise training elicited a99% increase in GXT run time in the taz mice ''P'' < 0.01 vs. pre-training), but failed to increasetimes to those of sedentary WT mice. Training significantly decreased state 3 respiratorycapacity of muscle mitochondria from exercised mice (wild type sedentary (WTS): 4992.59 ±371.35, wild type exercised (WTX): 3779.60 ± 561.43, taz sedentary (TazS): 2978.50 ± 383.53,TazS: 1827.55 ± 525.17 (pmolO2/(s*mg), ''P'' = 0.02, Sed. vs. Ex.), and significantly decreasedmitochondrial CS activity in taz mice (WTS: 4.48 ± 0.51, WTX: 3.87 ± 0.69, TazS: 3.21 ± 0.54,taz exercised (TazX): 1.63 ± 0.69 (relative absorbance/gram of protein) (RU/g), ''P'' = 0.01).Training also tended to reduce mitochondrial lactate dehydrogenase (LDH) and monocarboxylatetransporter 1 (MCT1) activities, MnSOD content, and 4-hydroxnonenal-protein adducts (index ofoxidative stress), but tended to increase mitochondrial UCP3 in exercised WT and taz mice.Interestingly, training significantly increased muscle levels of CS (WTS: 1.491 ± 0.112, WTX:1.792 ± 0.143, TazS: 1.325 ± 0.108, TazX: 1.550 ± 0.143 (RU/g),'' P'' = 0.05 Sed. v. Ex.),suggesting increased muscle mitochondrial content with training. This study indicates thatexercise training improves functional capacity of taz deficient mice and induces selectivemitochondrial protein remodeling during mitochondrial biogenesis that perhaps mitigatesoxidative stress while adapting to increased metabolic demand.while adapting to increased metabolic demand.)
Chicco 2013 Abstract MiP2013 Poster + (Barth Syndrome is a mitochondrial disease … Barth Syndrome is a mitochondrial disease associated with exercise intolerance and cardioskeletal myopathy resulting from mutations in the tafazzin (taz) gene. Taz encodes a phospholipid transacylase believed to be important for the remodeling of cardiolipin and maintaining optimal mitochondrial membrane function. The present study characterized skeletal muscle mitochondrial function and exercise capacity of a new taz shRNA mouse model of Barth Syndrome (90% taz-deficient), and examined the effect of exercise training on these parameters. Mitochondrial respiratory function was assessed in mitochondria freshly isolated from hindlimb muscles using an Oroboros Oxygraph-2k with pyruvate+malate as substrates. A pre-training treadmill graded exercise test (GXT) revealed profound exercise intolerance in taz mice, which corresponded to reduced respiratory capacity, citrate synthase (CS) and ET-pathway Complex I protein content of muscle mitochondria in the taz vs. age-matched wild-type (WT) mice. Based on the pre-training GXT, exercise training was conducted at 12-17 m/min, 0% grade for 60 min/d, 5 d/wk. Exercise training elicited a 99% increase in GXT run time in the taz mice (P<0.01 vs. pre-training), but failed to increase levels to that of sedentary WT mice. Unexpectedly, training significantly decreased OXPHOS capacity of isolated muscle mitochondria from exercised mice (WTS: 4993 ± 371, WTX: 3780 ± 561, TazS: 2979 ± 384, TazS: 1828 ± 525 (pmol/(s*mg), P=0.02 Sed. vs. Ex.), and significantly decreased mitochondrial CS activity in taz mice (WTS: 4.48 ± 0.51, WTX: 3.87 ± 0.69, TazS: 3.21 ± 0.54, TazX: 1.63 ± 0.69 (RU/g), P=0.01). Training tended to reduce mitochondrial lactate dehydrogenase (LDH) and monocarboxylate transporter 1 (MCT1) activities, MnSOD content, and 4-hydroxnonenal-protein adducts (index of oxidative stress), but tended to increase mitochondrial UCP3 in exercised WT and taz mice. Interestingly, training significantly increased CS activity in total muscle homogenates (WTS: 1.491 ± 0.112, WTX: 1.792 ± 0.143, TazS: 1.325 ± 0.108, TazX: 1.550 ± 0.143 (RU/g), P=0.05 Sed. v. Ex.), suggesting a training-induced increase in whole-muscle oxidative capacity despite a lower OXPHOS capacity per mg protein of isolated mitochondria. This study indicates that exercise training improves functional capacity of taz deficient mice despite persistent mitochondrial respiratory dysfunction, and induces selective remodeling of mitochondria in skeletal muscle perhaps to mitigate oxidant production from a dysfunctional respiratory system while adapting to increased metabolic demand.while adapting to increased metabolic demand.)
Le 2020 J Biol Chem + (Barth syndrome (BTHS) is a mitochondrial m … Barth syndrome (BTHS) is a mitochondrial myopathy resulting from mutations in the tafazzin (TAZ) gene encoding a phospholipid transacylase required for cardiolipin remodeling. Cardiolipin is phospholipid of the inner mitochondrial membrane essential for the function of numerous mitochondrial proteins and processes. However, it is unclear how tafazzin deficiency impacts cardiac mitochondrial metabolism. To address this question while avoiding confounding effects of cardiomyopathy on mitochondrial phenotype, we utilized Taz-shRNA "knockdown" (TazKD) mice, which exhibit defective cardiolipin remodeling and respiratory supercomplex instability characteristic of human BTHS, but normal cardiac function into adulthood. Consistent with previous reports from other models, mitochondrial H2O2 emission and oxidative damage were greater in TazKD than in wild-type (WT) hearts, but there were no differences in oxidative phosphorylation coupling efficiency or membrane potential. Fatty acid and pyruvate oxidation capacities were 40-60% lower in TazKD mitochondria, but an upregulation of glutamate oxidation supported respiration rates approximating those with pyruvate and palmitoylcarnitine in WT. Deficiencies in mitochondrial CoA and shifts in the cardiac acyl-CoA profile paralleled changes in fatty acid oxidation enzymes and acyl-CoA thioesterases suggesting limitations of CoA availability or "trapping" in TazKD mitochondrial metabolism. Incubation of TazKD mitochondria with exogenous CoA partially rescued pyruvate and palmitoylcarnitine oxidation capacities, implicating dysregulation of CoA-dependent intermediary metabolism rather than respiratory chain defects in the bioenergetic impacts of tafazzin-deficiency. These findings support links among cardiolipin abnormalities, respiratory supercomplex instability and mitochondrial oxidant production, and shed new light on the distinct metabolic consequences of tafazzin-deficiency in the mammalian heart.l oxidant production, and shed new light on the distinct metabolic consequences of tafazzin-deficiency in the mammalian heart.)
Kiebish 2013 J Lipid Res + (Barth syndrome is a complex metabolic diso … Barth syndrome is a complex metabolic disorder caused by mutations in the mitochondrial transacylase Tafazzin. Recently, an inducible Tafazzin shRNA knockdown mouse model was generated to deconvolute the complex bioenergetic phenotype of this disease. To investigate the underlying cause of hemodynamic dysfunction in Barth syndrome, we interrogated the cardiac structural and signaling lipidome of this mouse model as well as its myocardial bioenergetic phenotype. A decrease in the distribution of cardiolipin molecular species and robust increases in monolysocardiolipin and dilysocardiolipin were demonstrated. Additionally, the contents of choline and ethanolamine glycerophospholipid molecular species containing precursors for lipid signaling at the sn-2 position were altered. Lipidomic analyses revealed specific dysregulation of HETEs, prostanoids, as well as oxidized linoleic and docosahexaenoic metabolites. Bioenergetic interrogation uncovered differential substrate utilization as well as deceases in Complex III and CV activities. Transgenic expression of cardiolipin synthase or iPLA2γ ablation in Tafazzin deficient mice did not rescue the observed phenotype. These results underscore the complex nature of alterations in cardiolipin metabolism mediated by Tafazzin loss of function. Collectively, we identified specific lipidomic, bioenergetic and signaling alterations in a murine model that parallel those of Barth syndrome thereby providing novel insights into the pathophysiology of this debilitating disease.hophysiology of this debilitating disease.)
Chicco 2013 Abstract IOC79 + (Barth syndrome is an X-linked cardioskelet … Barth syndrome is an X-linked cardioskeletal myopathy that results from mutations in the Tafazzin (Taz) gene encoding a phospholipid transacylase required for the remodeling of the cardiolipin. Cardiolipin is an inner mitochondrial membrane phospholipid essential for the function of several mitochondrial proteins, but how Taz deficiency and defective cardiolipin remodeling influences mammalian mitochondrial function is unclear. We recently characterized the cardiac mitochondrial phenotype of a new Taz shRNA mouse model of BTHS by high resolution respirometry (HRR) on isolated mitochondria and permeabilized heart fibers, complemented by cardiac metabolomics and mitochondrial proteomic profiling. HRR revealed 40-60% lower rates of oxidative phosphorylation in Taz shRNA compared to wild-type (WT) mitochondria using pyruvate and palmitoylcarnitine (+ malate) as substrates in isolated subsarcolemmal and interfibrillar mitochondria, as well as permeabilized cardiac muscle fibers. Less robust impairments were seen in complex II-supported respiration (12%) and maximal enzymatic activity of respiratory complexes 1 (17%) and 4 (26%) in Taz shRNA vs. WT mitochondria. Unexpectedly, glutamate + malate respiration was markedly elevated in Taz shRNA vs. WT, reaching respiratory rates equal to those obtained with pyruvate and fatty acid substrates in WT mitochondria and fibers. Analysis of the Taz shRNA mitochondrial proteome revealed deficiencies in enzymes involved in amino acid catabolism, respiratory complex 1 assembly and fatty acid oxidation, while stress response enzymes, acyl-CoA thioesterases, and malate dehydrogenase were elevated. Cardiac metabolomics revealed a marked deficiency in pantothenic acid that paralleled 43% lower levels of CoA in Taz shRNA vs. WT mitochondria. To further investigate the potential role of CoA deficiency on the observed respiratory phenotype, isolated mitochondria were incubated with exogenous CoA prior to respirometry experiments, which significantly improved OXPHOS rates using pyruvate as a substrate. Taken together, our studies indicate that while Taz deficiency elicits expected impairments in respiratory chain function, the primary defect is a selective impairment of carbohydrate and lipid oxidation, perhaps due to a deficiency in mitochondria CoA that deserves further investigation.a CoA that deserves further investigation.)
Schulte 2013 Abstract MiP2013 + (Based on its presumed role in altering who … Based on its presumed role in altering whole-animal metabolic rate, the mitochondrion has become the focus of hypotheses that address the process of thermal adaptation. It has been proposed that temperature-induced limitations on mitochondrial function (due to passive thermal effects on biochemical activity or an imbalance between O2 supply and demand at low temperatures) affect whole organism performance and, as a result, cold-adapted or –acclimated species compensate with increased mitochondrial density and/or activity [1]. To address this hypothesis we use Fundulus heteroclitus, a teleost species with genetically distinct, locally adapted subpopulations (Northern, Southern, and Hybrid) which reside over a large thermal gradient. During acute high temperature shifts (37 °C), liver mitochondria isolated from 5 °C acclimated Northern Fundulus heteroclitus lose the capacity to perform oxidative phosphorylation. This phenomenon is not observed with fish acclimated to 15 and 25 °C, which is indicative of a cost of acclimation to low temperatures [2].To investigate the functional differences in mitochondrial properties as a result of low temperature acclimation we have acclimated Northern and Southern Fundulus heteroclitus to 5, 15 and 33 °C. We compare the kinetics of liver mitochondrial ADP-phosphorylation, proton conductance, and substrate oxidation during acute shifts to 5, 15, and 33 °C. In addition, we compare the rates of basal and maximum reactive oxygen species (ROS) production to assess its contribution as a result of proton conductance. Our current results indicate that during acute shifts to high temperature, cold-acclimated Northern killifish exhibit equivalent levels of LEAK respiration (i.e., proton leak) as room- and warm-temperature acclimated killifish while maintaining a lower membrane potential. This equivalent level of proton leak is reflected in no difference in ROS production when compared to the 15 °C acclimation. In addition, warm-acclimation appears to result in increased basal ROS production, while lowering maximal ROS. These results indicate that there are changes in mitochondrial function associated with low-temperature acclimation.sociated with low-temperature acclimation.)
Mkrtchyan 2018 Biochim Biophys Acta + (Based on the fact that traumatic brain inj … Based on the fact that traumatic brain injury is associated with mitochondrial dysfunction we aimed at localization of mitochondrial defect and attempted to correct it by thiamine.Interventional controlled experimental animal study was used. Adult male Sprague-Dawley rats were subjected to lateral fluid percussion traumatic brain injury. Thiamine was administered 1 h prior to trauma; cortex was extracted for analysis 4 h and 3 d after trauma.Increased expression of inducible nitric oxide synthase (iNOS) and tumor necrosis factor receptor 1 (TNF-R1) by 4 h was accompanied by a decrease in mitochondrial respiration with glutamate but neither with pyruvate nor succinate. Assays of TCA cycle flux-limiting 2-oxoglutarate dehydrogenase complex (OGDHC) and functionally linked enzymes (glutamate dehydrogenase, glutamine synthetase, pyruvate dehydrogenase, malate dehydrogenase and malic enzyme) indicated that only OGDHC activity was decreased. Application of the OGDHC coenzyme precursor thiamine rescued the activity of OGDHC and restored mitochondrial respiration. These effects were not mediated by changes in the expression of the OGDHC sub-units (E1k and E3), suggesting post-translational mechanism of thiamine effects. By the third day after TBI, thiamine treatment also decreased expression of TNF-R1. Specific markers of unfolded protein response did not change in response to thiamine.Our data point to OGDHC as a major site of damage in mitochondria upon traumatic brain injury, which is associated with neuroinflammation and can be corrected by thiamine. Further studies are required to evaluate the pathological impact of these findings in clinical settings.Copyright © 2018. Published by Elsevier B.V.pyright © 2018. Published by Elsevier B.V.)
Schniertshauer 2023 Curr Issues Mol Biol + (Based on the knowledge that many diseases … Based on the knowledge that many diseases are caused by defects in the metabolism of the cells and, in particular, in defects of the mitochondria, mitochondrial medicine starts precisely at this point. This new form of therapy is used in numerous fields of human medicine and has become a central focus within the field of medicine in recent years. With this form of therapy, the disturbed cellular energy metabolism and an out-of-balance antioxidant system of the patient are to be influenced to a greater extent. The most important tool here is mitotropic substances, with the help of which attempts are made to compensate for existing dysfunction. In this article, both mitotropic substances and accompanying studies showing their efficacy are summarized. It appears that the action of many mitotropic substances is based on two important properties. First, on the property of acting antioxidantly, both directly as antioxidants and via activation of downstream enzymes and signaling pathways of the antioxidant system, and second, via enhanced transport of electrons and protons in the mitochondrial respiratory chain.ns in the mitochondrial respiratory chain.)
Pfeiffer 2017 Free Radic Biol Med + (Bcl-xL is an anti-a … Bcl-xL is an anti-apoptotic protein that localizes to the outer mitochondrial membrane and influences mitochondrial bioenergetics by controlling Ca2+ influx into mitochondria. Here, we analyzed the effect of mitochondrial Bcl-xL on mitochondrial shape and function in knockout (KO), wild type and rescued mouse embryonic fibroblast cell lines. Mitochondria of KO cells were more fragmented, exhibited a reduced ATP concentration, and reduced oxidative phosphorylation (OXPHOS) suggesting an increased importance of ATP generation by other means. Under steady-state conditions, acidification of the growth medium as a readout for glycolysis was similar, but upon inhibition of ATP synthase with oligomycin, KO cells displayed an instant increase in glycolysis. In addition, forced energy production through OXPHOS by replacing glucose with galactose in the growth medium rendered KO cells more susceptible to mitochondrial toxins. KO cells had increased cellular reactive oxygen species and were more susceptible to oxidative stress, but had higher glutathione levels, which were however more rapidly consumed under conditions of oxidative stress. This coincided with an increased activity and protein abundance of the pentose phosphate pathway protein glucose-6-phosphate dehydrogenase, which generates NADPH necessary to regenerate reduced glutathione. KO cells were also less susceptible to pharmacological inhibition of the pentose phosphate pathway. We conclude that mitochondrial Bcl-xL is involved in maintaining mitochondrial respiratory capacity. Its deficiency causes oxidative stress, which is associated with an increased glycolytic capacity and balanced by an increased activity of the pentose phosphate pathway.alanced by an increased activity of the pentose phosphate pathway.)
Beatson Conference 2018 Glasgow UK + (Beatson International Cancer Conference, Glasgow, United Kingdom, 2018)
Chaix 2014 Cell Metab + (Because current therapeutics for obesity a … Because current therapeutics for obesity are limited and only offer modest improvements, novel interventions are needed. Preventing obesity with time-restricted feeding (TRF; 8–9 hr food access in the active phase) is promising, yet its therapeutic applicability against preexisting obesity, diverse dietary conditions, and less stringent eating patterns is unknown. Here we tested TRF in mice under diverse nutritional challenges. We show that TRF attenuated metabolic diseases arising from a variety of obesogenic diets, and that benefits were proportional to the fasting duration. Furthermore, protective effects were maintained even when TRF was temporarily interrupted by ad libitum access to food during weekends, a regimen particularly relevant to human lifestyle. Finally, TRF stabilized and reversed the progression of metabolic diseases in mice with preexisting obesity and type II diabetes. We establish clinically relevant parameters of TRF for preventing and treating obesity and metabolic disorders, including type II diabetes, hepatic steatosis, and hypercholesterolemia.patic steatosis, and hypercholesterolemia.)
Nunez-Figueredo 2014 Brain Res Bull + (Because mitochondrial oxidative stress and … Because mitochondrial oxidative stress and impairment are important mediators of neuronal damage in neurodegenerative diseases and in brain ischemia/reperfusion, in the present study, we evaluated theantioxidant and mitoprotective effect of a new promising neuroprotective molecule, JM-20, in mitochondriaand synaptosomes isolated from rat brains. JM-20 inhibited succinate-mediated H2O2 generation in both mitochondria and synaptosomes incubated in depolarized (high K+) medium at extremely low micromolar concentration and with identical IC50 values of 0.91 μM. JM-20 also repressed glucoseinducedH2O2 generation stimulated by rotenone or by antimycin A in synaptosomes incubated in high sodium-polarized medium at extremely low IC50 values of 0.395 μM and 2.452 μM, respectively. JM-20 was unable to react directly with H2O2 or with superoxide anion radicals but displayed a cathodic reductionpeak at −0.71 V, which is close to that of oxygen (−0.8 V), indicating high electron affinity. JM-20 also inhibited uncoupled respiration in mitochondria or synaptosomes and was a more effective inhibitor in the presence of the respiratory substrates glutamate/malate than in the presence of succinate. JM-20 also prevented Ca2+ -induced mitochondrial permeability transition pore opening, membrane potential dissipation and cytochrome ''c'' release, which are key pathogenic events during stroke. This molecule also prevented Ca2+ influx into synaptosomes and mitochondria; the former effect was a consequence of the latter because JM-20 inhibition followed the patterns of carbonyl cyanide p-trifluoromethoxyphenyl hydrazone (FCCP), which is a classic mitochondrial uncoupler. Because the mitochondrion is considered an important source and target of neuronal cell death signaling after an ischemic insult, the antioxidant and protective effects of JM-20 against the deleterious effects of Ca2+ observed at the mitochondrial level in this study may endow this molecule with the ability to succeed in mitochondrion-targeted strategiesto combat ischemic brain damage.2+ observed at the mitochondrial level in this study may endow this molecule with the ability to succeed in mitochondrion-targeted strategies to combat ischemic brain damage.)
Ulgherait 2020 Nat Commun + (Because old age is associated with defects … Because old age is associated with defects in circadian rhythm, loss of circadian regulation is thought to be pathogenic and contribute to mortality. We show instead that loss of specific circadian clock components Period (Per) and Timeless (Tim) in male ''Drosophila'' significantly extends lifespan. This lifespan extension is not mediated by canonical diet-restriction longevity pathways but is due to altered cellular respiration via increased mitochondrial uncoupling. Lifespan extension of per mutants depends on mitochondrial uncoupling in the intestine. Moreover, upregulated uncoupling protein UCP4C in intestinal stem cells and enteroblasts is sufficient to extend lifespan and preserve proliferative homeostasis in the gut with age. Consistent with inducing a metabolic state that prevents overproliferation, mitochondrial uncoupling drugs also extend lifespan and inhibit intestinal stem cell overproliferation due to aging or even tumorigenesis. These results demonstrate that circadian-regulated intestinal mitochondrial uncoupling controls longevity in ''Drosophila'' and suggest a new potential anti-aging therapeutic target.w potential anti-aging therapeutic target.)
Larsen 2018 Physiol Rep + (Bed rest leads to impaired glucose toleran … Bed rest leads to impaired glucose tolerance. Whether this is linked to maladaptation's in skeletal muscle mitochondrial function and in particular to the level of reactive oxygen species (ROS) is at present unknown. The aim of this longitudinal study was to quantify skeletal muscle mitochondrial function (respiratory capacity and ROS production) together with glucose tolerance after 4 days of strict bed rest in healthy young male subjects (n = 14). Mitochondrial function was determined in permeabilized muscle fibers using high-resolution respirometry and fluorometry, mitochondrial content (citrate synthase [CS] activity) and antioxidant protein expression levels were assessed in parallel to this. Glucose tolerance was determined by means of oral glucose tolerance tests. Intrinsic mitochondrial respiratory capacity was augmented after the bed rest period (CI + IIP : 0.43 ± 0.12 vs. 0.55 ± 0.14 [pmol/sec/mg]/CS activity), due to a decreased CS activity (158 ± 39 vs. 129 ± 25 mU/mg dw.). No differences were observed in ROS production (per mg of tissue or when normalized to CS activity). Furthermore, the protein content for catalase was increased while superoxide dismutase and glutathione peroxidase remained unaffected. These findings were accompanied by an impaired glucose tolerance after the bed rest period (Matsuda index: 12 ± 6 vs. 9 ± 5). The change in intrinsic mitochondrial respiratory capacity could be an early indication in the development of impaired glucose tolerance. The increased catalase protein content might explain that no change was seen in ROS production after 4 days of bed rest. Whether these findings can be extrapolated to lifestyle-dependent decrements in physical activity and the development of type-2-diabetes remains unknown.nd the development of type-2-diabetes remains unknown.)
Hards 2018 Proc Natl Acad Sci U S A + (Bedaquiline (BDQ), an inhibitor of the myc … Bedaquiline (BDQ), an inhibitor of the mycobacterial F1Fo-ATP synthase, has revolutionized the antitubercular drug discovery program by defining energy metabolism as a potent new target space. Several studies have recently suggested that BDQ ultimately causes mycobacterial cell death through a phenomenon known as uncoupling. The biochemical basis underlying this, in BDQ, is unresolved and may represent a new pathway to the development of effective therapeutics. In this communication, we demonstrate that BDQ can inhibit ATP synthesis in ''Escherichia coli'' by functioning as a H+/K+ ionophore, causing transmembrane pH and potassium gradients to be equilibrated. Despite the apparent lack of a BDQ-binding site, incorporating the ''E. coli'' Fo subunit into liposomes enhanced the ionophoric activity of BDQ. We discuss the possibility that localization of BDQ at F1Fo-ATP synthases enables BDQ to create an uncoupled microenvironment, by antiporting H+/K+ Ionophoric properties may be desirable in high-affinity antimicrobials targeting integral membrane proteins.t;+/K+ Ionophoric properties may be desirable in high-affinity antimicrobials targeting integral membrane proteins.)
Teulier 2016 Proc Biol Sci + (Bees are thought to be strict users of car … Bees are thought to be strict users of carbohydrates as metabolic fuel for flight. Many insects, however, have the ability to oxidize the amino acid proline at a high rate, which is a unique feature of this group of animals. The presence of proline in the haemolymph of bees and in the nectar of plants led to the hypothesis that plants may produce proline as a metabolic reward for pollinators. We investigated flight muscle metabolism of hymenopteran species using high-resolution respirometry performed on permeabilized muscle fibres. The muscle fibres of the honeybee, ''Apis mellifera'', do not have a detectable capacity to oxidize proline, as those from the migratory locust, ''Locusta migratoria'', used here as an outgroup representative. The closely related bumblebee, ''Bombus impatiens'', can oxidize proline alone and more than doubles its respiratory capacity when proline is combined with carbohydrate-derived substrates. A distant wasp species, ''Vespula vulgaris'', exhibits the same metabolic phenotype as the bumblebee, suggesting that proline oxidation is common in hymenopterans. Using a combination of mitochondrial substrates and inhibitors, we further show that in ''B. impatiens'', proline oxidation provides reducing equivalents and electrons directly to the electron transport system. Together, these findings demonstrate that some bee and wasp species can greatly enhance the oxidation of carbohydrates using proline as fuel for flight.© 2016 The Author(s).as fuel for flight. © 2016 The Author(s).)
Shick 1988 Amer Zool + (Behaviors to conserve water during interti … Behaviors to conserve water during intertidal exposure at the same time impair respiratory gas exchange, so that observed responses to emersion may reflect compromises between these incompatible needs. Behavioral isolation of the tissues from air results in the complete or partial reliance on anoxic energy metabolism, which is most reliably measured directly as heat dissipation. Combined direct calorimetry and indirect calorimetry (respirometry) enable the partitioning of total metabolic heat dissipation into its aerobic and anoxic components, which may vary according to physical and biological factors. The mussel ''Mytilus edulis'' is tolerant of anoxia and saves water and energy during aerial exposure in its rocky intertidal habitat by closing its shell valves and becoming largely anoxic. Like most suspension feeders in this habitat, its compensation for reduced feeding time involves energy conservation; there is little evidence for energy supplementation such as increases in feeding rate or absorption efficiency. Ammonia production continues during aerial exposure and is involved in acid-base balance in the hemolymph and mantle cavity fluid. Infaunal cockles (''Cardium edule'') and mussels (''Geukensia demissa'') gape their shell valves, remain largely aerobic and have high rates of heat dissipation during intertidal exposure, a response which appears related to the lower desiccation potential and exploitation of richer trophic resources in their soft-sediment habitats. The variable expansion of the symbiotic sea anemone ''Anthopleura elegantissima'' reflects interaction among the responses to desiccation, irradiance and continued photosynthesis by its zooxanthellae during exposure to air. its zooxanthellae during exposure to air.)
Mayeur 2013 PhD Thesis + (Being small size at birth from malnutritio … Being small size at birth from malnutrition is associated with an increasedrisk to develop type 2 diabetes and cardiovascular and metabolic diseases in adulthood.The placental capacity to supply adequate amount of nutrients and oxygen to the fetusrepresents one of the main determiner of the fetal growth. Despite its critical roles duringprenatal development, few studies have investigated the effects of maternal diet on theplacental physiology and functions. Our aim was to explore the placental adaptive proteomicprocesses implicated in response to a maternal suboptimal nutrition.Rat term placentas from 70% food-restricted(FR30) mothers were used for a proteomic screen. Placental mitochondrial functions wereevaluated using molecular and functional approaches and ATP production was measured.RESULTS – FR30 drastically reduced both placental and fetal weights. FR30 placentasdisplayed 14 identified proteins differentially expressed, including several mitochondrialproteins suggesting specific alterations of these organelles. FR30 induced a marked increaseof placental mtDNA content and changes in mitochondrial functions including modulation ofthe expression of numerous genes implicated in both mitochondrial biogenesis andbioenergetic pathways. Mitochondria under FR30 conditions showed higher oxygenconsumption but fail to maintain their critical ATP production.We provide first evidence that maternal suboptimal nutrition inducesmitochondrial abnormalities in the placenta of growth-restricted fetuses. Although maternalcalorie restriction induces mitochondrial adaptive processes such as an increase of bothmitochondrial biogenesis and bioenergetic efficiency; placental ATP production wasdrastically reduced. This disturbance may be implicated in reduction of the placental capacityto actively transport nutrients that may strengthen the effect of maternal undernutrition on thedevelopment of the fetus. Our data suggest that placental mitochondrial defects may beimplicated, at least in part, in pathologies of feto-placental growth., in pathologies of feto-placental growth.)
NCD-RisC 2016 Elife + (Being taller is associated with enhanced l … Being taller is associated with enhanced longevity, and higher education and earnings. We reanalysed 1472 population-based studies, with measurement of height on more than 18.6 million participants to estimate mean height for people born between 1896 and 1996 in 200 countries. The largest gain in adult height over the past century has occurred in South Korean women and Iranian men, who became 20.2 cm (95 % credible interval 17.5-22.7) and 16.5 cm (13.3-19.7) taller, respectively. In contrast, there was little change in adult height in some sub-Saharan African countries and in South Asia over the century of analysis. The tallest people over these 100 years are men born in the Netherlands in the last quarter of 20th century, whose average heights surpassed 182.5 cm, and the shortest were women born in Guatemala in 1896 (140.3 cm; 135.8-144.8). The height differential between the tallest and shortest populations was 19-20 cm a century ago, and has remained the same for women and increased for men a century later despite substantial changes in the ranking of countries.ntial changes in the ranking of countries.)
Pena-Corona 2023 Front Pharmacol + (Being the first or second cause of death w … Being the first or second cause of death worldwide, cancer represents the most significant clinical, social, and financial burden of any human illness. Despite recent progresses in cancer diagnosis and management, traditional cancer chemotherapies have shown several adverse side effects and loss of potency due to increased resistance. As a result, one of the current approaches is on with the search of bioactive anticancer compounds from natural sources. Neopeltolide is a marine-derived macrolide isolated from deep-water sponges collected off Jamaica's north coast. Its mechanism of action is still under research but represents a potentially promising novel drug for cancer therapy. In this review, we first illustrate the general structural characterization of neopeltolide, the semi-synthetic derivatives, and current medical applications. In addition, we reviewed its anticancer properties, primarily based on in vitro studies, and the possible clinical trials. Finally, we summarize the recent progress in the mechanism of antitumor action of neopeltolide. According to the information presented, we identified two principal challenges in the research, i) the effective dose which acts neopeltolide as an anticancer compound, and ii) to unequivocally establish the mechanism of action by which the compound exerts its antiproliferative effect.pound exerts its antiproliferative effect.)
Shaikh 2014 Circulation + (Bendavia is a cell permeable, mitochondria … Bendavia is a cell permeable, mitochondria-targeting peptide currently being tested in clinical trials for acute coronary syndromes, heart failure, and renal disease. In a series of studies, we have shown that Bendavia reduces cellular injury by targeting the mitochondrial inner membrane. In particular, Bendavia targets cardiolipin, a mitochondrial phospholipid that acts as “glue” to hold respiratory protein complex subunits together. In this study, we tested the hypothesis that Bendavia would improve post-ischemic mitochondrial function by sustaining native respiratory protein complexes. We utilized blue native gels (non-denaturing conditions) alongside high-resolution respirometry in permeabilized myocardial fibers to directly link changes in protein complexes to mitochondrial function. Rat hearts were subjected to ischemia-reperfusion (I/R) with or without 1nM Bendavia perfusion beginning at the onset of reperfusion. The native expression of mitochondrial Complexes III and V were significantly reduced after I/R, and were restored with Bendavia (see Figure). The appearance of degradation bands was also noted in hearts after I/R, and these products of protein complex breakdown were also significantly reduced with Bendavia treatment. Respirometry studies in permeabilized ventricular fibers showed lower Complex I-dependent respiration after I/R (208±19 v 42±9 pmol O2/mg*s) in control v I/R, respectively; ''p''<0.05. Complex II-dependent respiration was also suppressed (753±41 v 168±13 pmol/mg*s in control versus I/R; ''p''<0.05). Treatment with Bendavia led to significantly improved Complexes I- (100±13pmol O2/mg*s) and II-dependent (334±63pmol O2/mg*s) respiration (''p''<0.05 versus untreated IR for both). Taken together, these data indicate that Bendavia is protecting myocardium by preserving native mitochondrial respiratory complexes and sustaining mitochondrial function.ry complexes and sustaining mitochondrial function.)
Brown DA 2014 Abstract MiP2014 + (Bendavia is a cytoprotective mitochondria- … Bendavia is a cytoprotective mitochondria-targeting peptide [1-4], currently being tested in the EMBRACE-STEMI trial for reducing injury during acute coronary syndromes. We previously showed that the cardioprotective effects of Bendavia involved improving cardiolipin-dependent mitochondrial membrane fluidity. As membrane fluidity influences the ability of proteins to assemble, we hypothesized that a consequence of augmented membrane fluidity would be higher expression of mitochondrial respiratory supercomplexes.Rat hearts (''N''=42) were subjected to ischemia-reperfusion (I/R) with our without 1 nM Bendavia perfusion, beginning at the onset of reperfusion. Left ventricular tissue was split into one of two study arms: 1. Supercomplex expression using blue-native gel electrophoresis (BN-PAGE), or 2. High-resolution respirometry using permeabilized ventricular fibers. For BN-PAGE studies, respiratory supercomplex bands were decreased with I/R, and restored with Bendavia (Fig. 1). High-resolution respirometry studies indicated suppressed Complex I-dependent respiration after I/R (208±19 v 42±9 pmol O2∙s-1.mg-1) in control v I/R, respectively; ''P''<0.05. Complex II-dependent respiration was also lower (753±41 v 168±13 pmol∙s-1∙mg-1 in control versus I/R; ''P''<0.05). Perfusion with Bendavia during reperfusion significantly increased Complex I- (100±13 pmol O2∙s-1.mg-1) and II-dependent (334±63 pmol O2∙s-1.mg-1) respiration (''P''<0.05 versus untreated IR for both). Taken together, these data suggest that Bendavia’s protective mechanism of action involves preserving supercomplex-dependent mitochondrial function during cardiac reperfusion.both). Taken together, these data suggest that Bendavia’s protective mechanism of action involves preserving supercomplex-dependent mitochondrial function during cardiac reperfusion.)
Felser 2014 Toxicology II + (Benzbromarone is an uricosuric structurall … Benzbromarone is an uricosuric structurally related to amiodarone and a known mitochondrial toxicant. The aim of the current study was to improve our understanding in the molecular mechanisms of benzbromarone-associated hepatic mitochondrial toxicity. In HepG2 cells and primary human hepatocytes, ATP levels started to decrease in the presence of 25-50 μM benzbromarone for 24-48 h, whereas cytotoxicity was observed only at 100 μM. In HepG2 cells, benzbromarone decreased the mitochondrial membrane potential starting at 50 μM following incubation for 24 h. Additionally, in HepG2 cells, 50 μM benzbromarone for 24 h induced mitochondrial uncoupling,and decreased mitochondrial ATP turnover and maximal respiration. This was accompanied by an increased lactate concentration in the cell culture supernatant, reflecting increased glycolysis as a compensatory mechanism to maintain cellular ATP. Investigation of the electron transport chain revealed a decreased activity of all relevant enzyme complexes. Furthermore, treatment with benzbromarone was associated with increased cellular ROS production, which could be located specifically to mitochondria. In HepG2 cells and in isolated mouse liver mitochondria, benzbromarone also reduced palmitic acid metabolism due to an inhibition of the long-chain acyl CoA synthetase. In HepG2 cells, benzbromarone disrupted the mitochondrial network, leading to mitochondrial fragmentation and a decreased mitochondrial volume per cell. Cell death occurred by both apoptosis and necrosis. The study demonstrates that benzbromarone not only affects the function of mitochondria in HepG2 cells and human hepatocytes, but is also associated with profound changes in mitochondrial structure which may be associated with apoptosis.re which may be associated with apoptosis.)
Van der Kooij 2018 Mol Psychiatry + (Benzodiazepines can ameliorate social dist … Benzodiazepines can ameliorate social disturbances and increase social competition, particularly in high-anxious individuals. However, the neural circuits and mechanisms underlying benzodiazepines' effects in social competition are not understood. Converging evidence points to the mesolimbic system as a potential site of action for at least some benzodiazepine-mediated effects. Furthermore, mitochondrial function in the nucleus accumbens (NAc) has been causally implicated in the link between anxiety and social competitiveness. Here, we show that diazepam facilitates social dominance, ameliorating both the competitive disadvantage and low NAc mitochondrial function displayed by high-anxious rats, and identify the ventral tegmental area (VTA) as a key site of action for direct diazepam effects. We also show that intra-VTA diazepam infusion increases accumbal dopamine and DOPAC, as well as activity of dopamine D1- but not D2-containing cells. In addition, intra-NAc infusion of a D1-, but not D2, receptor agonist facilitates social dominance and mitochondrial respiration. Conversely, intra-VTA diazepam actions on social dominance and NAc mitochondrial respiration are blocked by pharmacological NAc micro-infusion of a mitochondrial complex I inhibitor or an antagonist of D1 receptors. Our data support the view that diazepam disinhibits VTA dopaminergic neurons, leading to the release of dopamine into the NAc where activation of D1-signaling transiently facilitates mitochondrial function, that is, increased respiration and enhanced ATP levels, which ultimately enhances social competitive behavior. Therefore, our findings critically involve the mesolimbic system in the facilitating effects of diazepam on social competition and highlight mitochondrial function as a potential therapeutic target for anxiety-related social dysfunctions.t for anxiety-related social dysfunctions.)
Vinogradov 2005 Biochemistry (Mosc) + (Besides major NADH-, succinate-, and other … Besides major NADH-, succinate-, and other substrate oxidase reactions resulting in four-electron reduction of oxygen to water, the mitochondrial respiratory chain catalyzes one-electron reduction of oxygen to superoxide radical O(2)(-.) followed by formation of hydrogen peroxide. In this paper the superoxide generation by Complex I in tightly coupled bovine heart submitochondrial particles is quantitatively characterized. The rate of superoxide formation during Deltamu(H(+))-controlled respiration with succinate depends linearly on oxygen concentration and contributes approximately 0.4% of the overall oxidase activity at saturating (0.25 mM) oxygen. The major part of one-electron oxygen reduction during succinate oxidation (approximately 80%) proceeds via Complex I at the expense of its Deltamu(H(+))-dependent reduction (reverse electron transfer). At saturating NADH the rate of O(2)(-.) formation is substantially smaller than that with succinate as the substrate. In contrast to NADH oxidase, the rate-substrate concentration dependence for the superoxide production shows a maximum at low (approximately 50 microM) concentrations of NADH. NAD+ and NADH inhibit the succinate-supported superoxide generation. Deactivation of Complex I results in almost complete loss of its NADH-ubiquinone reductase activity and in increase in NADH-dependent superoxide generation. A model is proposed according to which complex I has two redox active nucleotide binding sites. One site (F) serves as an entry for the NADH oxidation and the other one (R) serves as an exit during either the succinate-supported NAD+ reduction or superoxide generation or NADH-ferricyanide reductase reaction.n or NADH-ferricyanide reductase reaction.)
Martinez 2015 Thesis + (Besides of the 23 chromosome pairs located … Besides of the 23 chromosome pairs located in the nucleous (nDNA), the human genome also includes many DNA molecules placed in mitochondria and known as mitochondrial DNA (mtDNA). mtDNA encodes 13 subunits very important for the oxidative phosphorylation system (OXPHOS) and RNAs required for its expression. Because of its location and genetic particularities, mtDNA accumulates mutations faster than nDNA. Many of these mutations result into a serious disease. The construction of cellular models are the key to study these mutations.In his work we used the cell line HepG2, beacause its utility in ''in vitro'' studies. We studied their differentiation into mature hepatocytes and tried to remove its mtDNA to build transmitochondrial cell lines.NA to build transmitochondrial cell lines.)
Kuznetsov 2022 Antioxidants (Basel) + (Besides their main function for energy pro … Besides their main function for energy production in form of ATP in processes of oxidative phosphorylation (OxPhos), mitochondria perform many other important cellular functions and participate in various physiological processes that are congregated. For example, mitochondria are considered to be one of the main sources of reactive oxygen species (ROS) and therefore they actively participate in the regulation of cellular redox and ROS signaling. These organelles also play a crucial role in Ca2+ signaling and homeostasis. The mitochondrial OxPhos and their cellular functions are strongly cell/tissue specific and can be heterogeneous even within the same cell, due to the existence of mitochondrial subpopulations with distinct functional and structural properties. However, the interplay between different functions of mitochondria is not fully understood. The mitochondrial functions may change as a response to the changes in the cellular metabolism (signaling in). On the other hand, several factors and feedback signals from mitochondria may influence the entire cell physiology (signaling out). Numerous interactions between mitochondria and the rest of cell, various cytoskeletal proteins, endoplasmic reticulum (ER) and other cellular elements have been demonstrated, and these interactions could actively participate in the regulation of mitochondrial and cellular metabolism. This review highlights the important role of the interplay between mitochondrial and entire cell physiology, including signaling from and to mitochondria.luding signaling from and to mitochondria.)
Rose 2019 Adis + (Best known for their role in generating ad … Best known for their role in generating adenosine triphosphate (ATP) through oxidative phosphorylation, mitochondria are responsible for a wide variety of vital cellular processes including apoptosis, maintenance of calcium homeostasis, redox signaling, steroid synthesis, and lipid metabolism. The mitochondria are dynamic organelles, responding to changing cellular physiology, nutrient availability, and energy demands by changing in function as well as shape, size, distribution, and number. Given the many important roles of the mitochondria for normal cellular function, it is not surprising that mitochondrial dysfunction is involved in a wide variety of diseases and medical disorders. Despite several mechanisms to combat the leakage of electrons that accompanies electron transfer during the process of oxidative phosphorylation, mitochondria are the primary producers of reactive oxygen species (ROS) in most cell types. Given the importance of mitochondria in health and disease, the effects of the antioxidant and glutathione precursor, N-acetylcysteine (NAC), on mitochondrial function have been examined in many studies of a wide variety of medical conditions. The purpose of this review is to conduct a systematic review of the literature on the effects of NAC on mitochondrial metabolism.ffects of NAC on mitochondrial metabolism.)
Schoettl 2015 Fatty Acid Oxidation O2k-Network Discussion Forum + (Beta oxidation in adipocytes (white and brown), HEK293 cells, isolated mitochondria from liver, adipocytes, brain, etc.)
Mitochondrial Interest Group 2014 + (Bethesda, MD, US [http://sigs.nih.gov/mito … Bethesda, MD, US [http://sigs.nih.gov/mito/Pages/default.aspx Mitochondrial Interest Group] A Mitochondrial Etiology of Metabolic and Degenerative Diseases Cancer and Ageing - lecture by Dr. Wallace and Transformational Medicine in the Mitochondrial Age Symposium.dicine in the Mitochondrial Age Symposium.)
Escoll 2019 Immunometabolism + (Beyond oxidative phosphorylation (OXPHOS), … Beyond oxidative phosphorylation (OXPHOS), mitochondria have also immune functions against infection, such as the regulation of cytokine production, the generation of metabolites with antimicrobial proprieties and the regulation of inflammasome-dependent cell death, which seem in turn to be regulated by the metabolic status of the organelle. Although OXPHOS is one of the main metabolic programs altered during infection, the mechanisms by which pathogens impact the mitochondrial electron transport chain (ETC) complexes to alter OXPHOS are not well understood. Similarly, how changes on ETC components affect infection is only starting to be characterized. Herein we summarize and discuss the existing data about the regulation of ETC complexes and super-complexes during infection, in order to shed some light on the mechanisms underlying the regulation of the mitochondrial OXPHOS machinery when intracellular pathogens infect eukaryotic host cells.ar pathogens infect eukaryotic host cells.)
Franko 2016 Diabetes + (Bezafibrate (BEZ), a pan activator of pero … Bezafibrate (BEZ), a pan activator of peroxisome proliferator-activated receptors (PPARs), has been generally used to treat hyperlipidemia for decades. Clinical trials with type 2 diabetes patients indicated that BEZ also has beneficial effects on glucose metabolism, although the underlying mechanisms of these effects remain elusive. Even less is known about a potential role for BEZ in treating type 1 diabetes. Here we show that BEZ markedly improves hyperglycemia and glucose and insulin tolerance in streptozotocin (STZ)-treated mice, an insulin-deficient mouse model of type 1 diabetes. BEZ treatment of STZ mice significantly suppressed the hepatic expression of genes that are annotated in inflammatory processes, whereas the expression of PPAR and insulin target gene transcripts was increased. Furthermore, BEZ-treated mice also exhibited improved metabolic flexibility as well as an enhanced mitochondrial mass and function in the liver. Finally, we show that the number of pancreatic islets and the area of insulin positive cells tended to be higher in BEZ-treated mice. Our data suggest that BEZ may improve impaired glucose metabolism by augmenting hepatic mitochondrial performance, suppressing hepatic inflammatory pathways, and improving insulin sensitivity and metabolic flexibility. Thus, BEZ treatment might also be useful for patients with impaired glucose tolerance or diabetes.© 2016 by the American Diabetes Association. Readers may use this article as long as the work is properly cited, the use is educational and not for profit, and the work is not altered.t for profit, and the work is not altered.)
NTS/INA Meeting 2017 Florianopolis Brazil + (Biennial Meeting on Metabolic derangements predisposing to neurotoxicity and neurodegenerative disease, Florianopolis, Brazil.)
Zhao 2021 Trends Cancer + (Biguanides are a class of antidiabetic dru … Biguanides are a class of antidiabetic drugs that includes phenformin and metformin; however, the former was withdrawn from approval in many countries due to its toxicity. Findings from retrospective epidemiological studies in diabetic populations and preclinical laboratory models have demonstrated that biguanides possess antitumor activities that suggest their repurposing for cancer prevention and treatment. However, a better understanding of how these biguanides behave as antitumor agents is needed to guide their improved applications in cancer therapy, spurring increased interest in their pharmacology. Here, we present evidence for proposed mechanisms of action related to their antitumor activity, including their effects on central carbon metabolism in cancer cells and immune-modulating activity, and then review progress on biguanide repurposing in cancer therapeutics and the possible re-evaluation of phenformin as a cancer therapeutic agent. phenformin as a cancer therapeutic agent.)
Schwarzkopf 2013 Pharmazie + (Bilobalide, an active constituent of Ginkg … Bilobalide, an active constituent of Ginkgo biloba, is known to have neuroprotective properties, but its mode of action remains unclear. In this study, bilobalide significantly reduced brain damage in mice (indicated by TTC staining) when given before transient middle cerebral artery occlusion (tMCAO). As measured by microdialysis in the ischemic striatum, local perfusion with bilobalide (10 microM) reduced ischemia-induced glutamate release by 70% while glucose levels were not affected. Mitochondria isolated from ischemic brain showed a decrease of respiration compared to non-ischemic controls. Treatment with bilobalide (10 mg/kg) before tMCAO improved respiratory capacity of complex I significantly when measured ex vivo. In addition, mitochondrial swelling induced ex vivo by calcium was used to estimate opening of the mitochondrial permeability transition pore. In this assay, the changes induced by tMCAO were completely reversed when mice had received pretreatment with bilobalide. We conclude that neuroprotection by bilobalide involves a mechanism in which the drug reverses ischemia-induced changes in mitochondria, leading to a reduction of glutamate release.ading to a reduction of glutamate release.)
Garlid AO 2012 Abstract Bioblast + (Binding of cardiac glycosides to the Na,K- … Binding of cardiac glycosides to the Na,K-ATPase has two effects: increased contractility (inotropy) and cardioprotection against ischemia-reperfusion injury [1]. Cardioprotection is mediated by caveolar vesicles (signalosomes) that bud off the plasma membrane, move to mitochondria, and use a terminal kinase to phosphorylate an outer membrane protein. This activates inner membrane PKCεs, causing opening of the mitochondrial ATP-sensitive K+ channel ([[Mitochondrial ATP-sensitive K+ channel|mtKATP]]) and inhibition of the mitochondrial permeability transition (mtPT). These events are assayed ''in vitro'' using purified signalosomes from treated hearts and mitochondria from untreated hearts [2]. The terminal kinase of GPCR signalosomes is PKG [2]; however PKG does not mediate cardioprotection by [[ouabain]], so we set out to determine the terminal kinases used by the ouabain signalosome. Rat hearts perfused with ouabain yielded a signalosome fraction that was caveolar in nature and enriched with caveolins 1 and 3, Src, PKCε and the α-1-subunit of the Na+,K+-ATPase. Electron microscopy of purified signalosomes revealed vesicles approximately 140 nM in diameter that were found by immunogold labeling to be decorated with caveolin-3. Ouabain signalosomes from heart opened mtKATP in mitochondria isolated from untreated hearts and liver. The terminal kinases of the ouabain signalosome are Src and PKCε, which together phosphorylated an endogenous outer membrane p38MAPK. We conclude (1) that ouabain cardioprotection utilizes the signalosome mechanism; (2) that the terminal kinases acting on mitochondria are Src and PKCε, (3) that this is a general mechanism of cell signaling, given that signalosomes from rat heart open mtKATP in rat liver mitochondria. (4) that ouabain cardioprotection acts via a mitochondrial p38 MAPK.Digitalis has been used in the treatment of heart failure since 1785. It was thought for many years that its efficacy was due to its positive inotropic effect. This may not be the case. Cardioprotection in both rat and rabbit is seen with concentrations of ouabain that have no inotropic effect.# [http://www.ncbi.nlm.nih.gov/pubmed/17306295 Pasdois P, Beauvoit B, Costa AD, Vinassa B, Tariosse L, Bonoron-Adèle S, Garlid KD, Dos Santos P (2007) Sarcoplasmic ATP-sensitive potassium channel blocker HMR1098 protects the ischemic heart: implication of calcium, Complex I, reactive oxygen species and mitochondrial ATPsensitive potassium channel. J Mol Cell Cardiol 42: 631-642.]# [http://www.ncbi.nlm.nih.gov/pubmed/19118560 Garlid KD, Costa AD, Quinlan CL, Pierre SV, Dos Santos P (2009) Cardioprotective signaling to mitochondria. J Mol Cell Cardiol 46: 858-866. Open Access]e SV, Dos Santos P (2009) Cardioprotective signaling to mitochondria. J Mol Cell Cardiol 46: 858-866. Open Access])
Gnaiger 2022 Abstract Bioblast-eds + (Bioblast 2022 is a follow-up of Bioblast 2 … Bioblast 2022 is a follow-up of Bioblast 2012 [1] and the first life conference linked to the journal ''Bioenergetics Communications'' [2]. It can be seen in the line of MiP''conferences'' of the Mitochondrial Physiology Society [3], which was founded at the 3rd MiP''conference'' in 2003 [4]. The last one took place in 2019 in Belgrade, RS within the COST Action MitoEAGLE [5]. The MitoEAGLE Summit was prevented from happening by the pandemic lockdown. Instead, the MitoEAGLE Consortium of 666 coauthors completed the first publication in ''Bioenergetics Communications'' [6]. In the tradition of Bioblast and MiP [1,7], Bioblast 2022 is presented with the beauty of Odra Noel's ''MiPArt'' and is honored by her presence at the conference. We celebrate 30 years Oroboros Instruments. As a follow-up of the MitoEAGLE project [8], the MiP''society'' and the Oroboros Ecosystem are the drivers of ''Bioenergetics Communications''. The endosymbiotic theories link the mitochondria and plastids to their free-living ancestors. Together, these are the bioblasts in spotlight of bioenergetics. Bioblasts and interactions with their hosts are the topics of ''Bioenergetics Communications'', inaugurating the concept of ''Living Communications''. # Gnaiger E, Meissner B, Laner V, eds (2012) Bioblast 2012: Mitochondrial Competence. https://bioblast.at/index.php/MiPNet17.12_Bioblast_2012# Bioenergetics Communications BEC - https://www.bioenergetics-communications.org/index.php/bec/index# Mitochondrial Physiology Society - https://www.mitophysiology.org/index.php/Mitochondrial_Physiology_Society # Gnaiger E, Renner K, eds (2003) 3rd Conference on Mitochondrial Physiology. Schröcken, Austria, Sept 2003. https://www.mitophysiology.org/index.php/MiPNet08.10_MiP2003# Lalic Nebojsa, Krako Jakovljevic Nina (2019) 14th Conference on Mitochondrial Physiology: Mitochondrial function: changes during life cycle and in noncommunicable diseases - COST MitoEAGLE perspectives and MitoEAGLE WG and MC Meeting. https://www.mitophysiology.org/index.php/MiP2019/MitoEAGLE_Belgrade_RS# Gnaiger E et al ― MitoEAGLE Task Group (2020) Mitochondrial physiology. https://doi.org/10.26124/bec:2020-0001.v1 # Gnaiger E (2010) Seven years Mitochondrial Physiology Society and a welcome to MiP2010: Bioblasts – the aliens with permanent residence in our cells. - https://wiki.bioblast.at/index.php/Gnaiger_2010_Abstract_MiP2010# COST Action CA15203 (2016-2021): MitoEAGLE - https://mitoeagle.org/index.php/MitoEAGLE16-2021): MitoEAGLE - https://mitoeagle.org/index.php/MitoEAGLE )
Gnaiger 2014 Abstract MiP2014 + (Biochemical '''cell ergometry''' aims at m … Biochemical '''cell ergometry''' aims at measurement of ''J''O2,max (compare ''V''O2,max in exercise ergometry of humans and animals) of cell respiration linked to phosphorylation of ADP to ATP. The corresponding [[OXPHOS-capacity]] is based on saturating concentrations of ADP, [ADP]*, and inorganic phosphate, [Pi]*, available to the mitochondria. This is metabolically opposite to uncoupling respiration, which yields [[ET-capacity]]. The OXPHOS state can be established experimentally by selective [[permeabilized cells |permeabilization of cell membranes]] with maintenance of intact mitochondria, titrations of ADP and Pi to evaluate kinetically saturating conditions, and establishing fuel substrate combinations which reconstitute physiological [[TCA cycle]] function.[[TCA cycle]] function.)
Kunz 1999 J Neurochem + (Biochemical micromethods were used for the … Biochemical micromethods were used for the investigation of changes in mitochondrial oxidative phosphorylation associated with cytochrome c oxidase deficiency in brain cortex from Movbr (mottled viable brindled) mice, an animal model of Menkes’ copper deficiency syndrome. Enzymatic analysis of cortex homogenates from Movbr mice showed an approximately twofold decreasein cytochrome c oxidase and a 1.4-fold decrease in NADH:cytochrome c reductase activities as compared with controls. Assessment of mitochondrial respiratory function was performed using digitonin-treated homogenates of the cortex, which exhibited the main characteristics of isolated brain mitochondria. Despite the substantial changes in respiratory chain enzyme activities, no significant differences were found in maximal pyruvate or succinate oxidation rates of brain cortex homogenates from Movbr and control mice. Inhibitor titrations wereused to determine flux control coefficients of NADH:CoQ oxidoreductase and cytochrome c oxidase on the rate of mitochondrial respiration. Application of amobarbital to titrate the activity of NADH:CoQ oxidoreductase showed very similar flux control coefficients for control and mutant animals. Alternately, titration of respiration with azide revealed for Movbr mice significantly sharper inhibition curves than for controls, indicating a more than twofold elevated flux control coefficient of cytochrome c oxidase. Owing to the reserve capacity of respiratory chain enzymes, the reported changes in activities do not seem to affect whole-brain high-energy phosphates, as observed in a previous study using 31P NMR.bserved in a previous study using 31P NMR.)
Von Brand 1966 Academic Press + (Biochemistry of Parasites presents the bio … Biochemistry of Parasites presents the biochemical aspects of parasitology. The topics covered in the book include inorganic substances; carbohydrate relationships of parasites; parasitic metabolism of carbohydrates and transport mechanisms; distribution of lipids in the bodies of parasites; and disturbances in the host's protein metabolism during parasitic infections.in metabolism during parasitic infections.)
Walczak 2018 FASEB J + (Bioenergetic failure, oxidative stress, an … Bioenergetic failure, oxidative stress, and changes in mitochondrial morphology are common pathologic hallmarks of amyotrophic lateral sclerosis (ALS) in several cellular and animal models. Disturbed mitochondrial physiology has serious consequences for proper functioning of the cell, leading to the chronic mitochondrial stress. Mitochondria, being in the center of cellular metabolism, play a pivotal role in adaptation to stress conditions. We found that mitochondrial dysfunction and adaptation processes differ in primary fibroblasts derived from patients diagnosed with either sporadic or familial forms of ALS. The evaluation of mitochondrial parameters such as the mitochondrial membrane potential, the oxygen consumption rate, the activity and levels of respiratory chain complexes, and the levels of ATP, reactive oxygen species, and Ca2+ show that the bioenergetic properties of mitochondria are different in sporadic ALS, familial ALS, and control groups. Comparative statistical analysis of the data set (with use of principal component analysis and support vector machine) identifies and distinguishes 3 separate groups despite the small number of investigated cell lines and high variability in measured parameters. These findings could be a first step in development of a new tool for predicting sporadic and familial forms of ALS and could contribute to knowledge of its pathophysiology.ibute to knowledge of its pathophysiology.)
Khan 2015 Abstract MiPschool Cape Town 2015 + (Bioenergetic health index (BHI) profiling … Bioenergetic health index (BHI) profiling is an emerging concept in the field of mitochondrial research [1]. In general, bioenergetics is the study of balance between energy intake and energy utilization for life sustaining processes. Mitochondrion serves as an early warning signal of bioenergetics crisis in patient populations. Any changes in bioenergetics are the first signal to determine the progression of mitochondrial disorders that are complex and multifactorial. In order to achieve the above, the platelets from the patient’s blood samples were extracted and subjected to high throughput assays such as XF Extracellular Flux Analyzer, BHI can be calculated to represent the patient’s composite mitochondrial profile by monitoring the bioenergetic health of immune cells such as monocytes, lymphocytes, neutrophils and platelets from blood [2]. This approach can be a step towards personalized cell based measurements to quantify bioenergetic health index. The study will be discussed in detail later.e study will be discussed in detail later.)
Kaambre 2013 Front Physiol + (Bioenergetic profiling of cancer cells is … Bioenergetic profiling of cancer cells is of great potential because it can bring forward new and effective therapeutic strategies along with early diagnosis. Metabolic Control Analysis (MCA) is a methodology that enables quantification of the flux control exerted by different enzymatic steps in a metabolic network thus assessing their contribution to the system's function. Our main goal is to demonstrate the applicability of MCA for in situ studies of energy metabolism in human breast and colorectal cancer cells as well as in normal tissues. We seek to determine the metabolic conditions leading to energy flux redirection in cancer cells. A main result obtained is that the adenine nucleotide translocator exhibits the highest control of respiration in human breast cancer thus becoming a prospective therapeutic target. Additionally, we present evidence suggesting the existence of mitochondrial respiratory supercomplexes that may represent a way by which cancer cells avoid apoptosis. The data obtained show that MCA applied in situ can be insightful in cancer cell energetic research.ightful in cancer cell energetic research.)
Bioenergetics Exhibition - Art meets Gentle Science + (Bioenergetics - Art meets Gentle Science in Sickness and in Health. A [[Gentle Science]] project initiated by [[Iyer S |Shilpa Iyer]]. Science Museum of Virginia, Richmond VA, US.)
Truu 2017 Abstract IOC122 + (Bioenergetics is a fast growing field in c … Bioenergetics is a fast growing field in cancer research, where many promising outcomes could provide targeted cancer treatment. Energy metabolism specific literature is characterized by many contradictions, concluding that cancer cells metabolize their increased glucose uptake via glycolysis rather than more energy efficient oxidative phosphorylation (OXPHOS). Furthermore, the majority of these conclusions are the outcome of only ''in vitro'' studies on cell culture models, without taking into consideration the factors arising from the tumor microenvironment giving significant effects ''in vivo''. We have conducted quantitative cellular respiration analysis on normal colon tissue, colorectal cancer (HCC) clinical tissue samples and CaCo-2 cell cultures. Our results show that HCC is not a fully glycolytic tumor and OXPHOS system might be the main source of ATP. Comparing healthy colon, HCC tissue and CaCo-2 cells, we found elevated rates of maximal ADP-activated respiration and greater activity of respiratory complex (C) II over CI in both HCC and CaCo-2 cells, whereas the opposite result in healthy tissue was present. These results indicate that the bioenergetic profile of Caco-2 cells corresponds generally to HCC tissue. Further research is in progress to generate a full cancer development model consisting of cell cultures, clinical polyps and malignant versus healthy tissue samples.d malignant versus healthy tissue samples.)
Huete-Ortega 2018 AlgaEurope2018 + (Bioenergetics is the study of energy trans … Bioenergetics is the study of energy transformations in cells, mitochondria, and chloroplasts as a basis to perform biochemical work. In algal chloroplasts solar energy is acquired and assimilated through photosynthesis to synthesize the organic matter required for growth, which is associated with production of oxygen, while mitochondrial respiration consumes oxygen to transform organic matter into the chemical energy that fuels cellular activity. Energetic coupling between chloroplasts and mitochondria has been described in algae. For example, mitochondrial physiology is involved in mitigating light stress in the photosynthetic pathway or chloroplast-generated reducing equivalents replace photophosphorylation as a source of ATP in the mitochondria. Therefore, a good functionality and cross-talk between both organelles is necessary to maintain metabolic integrity. High-resolution respirometry (HRR) is widely used to assess mitochondrial respiration and other bioenergetic parameters of isolated mitochondria, cultured cells, tissue preparations and human biopsies. In the biomedical field of mitochondrial physiology and its clinical applications, studies with HRR relate to degenerative diseases and life style-linked preventive medicine. I propose to extend the experimental options of the Oroboros O2k developed by Oroboros Instruments for HRR to the study of algae bioenergetics for biotechnological purposes. Outstanding applications include: i) research on mitochondrial respiration, photosynthesis and other bioenergetic parameters in algae, including the metabolic interactions between mitochondria and chloroplasts and their effects on production of biomass and organic molecules; ii) analysis of functional alterations of algae mutants generated for biotechnology; iii) optimization of cryopreservation in algae strains used in biotechnology by diagnostic evaluation of bioenergetic functionality. evaluation of bioenergetic functionality.)
Ebanks 2022 Abstract Bioblast + (Biological ageing is one of the biggest ri … Biological ageing is one of the biggest risk factors for a range of diseases, including cancers, neurodegenerative disease, and heart disease. Mitochondrial dysfunction is associated with both ageing and diseases of ageing. As exercise is increasingly being viewed as a potential anti-ageing therapy, we sought to assess the impact of exercise on the fitness and lifespan of ''D. melanogaster''[1]. In addition, we assessed the exercise-induced changes to mitochondrial physiology through high-resolution respirometry and label-free mass spectrometry. Exercise in late life extends the lifespan of male and female ''D. melanogaster'' compared with those exercised throughout their entire lifetime. Exercise also increases Complex-II-linked respiration and upregulates the expression of proteins from the electron transfer Complexes I, III, IV.# Ebanks B, Wang Y, Katyal G, Sargent C, Ingram TL, Bowman A, Moisoi N, Chakrabarti L (2021) Exercising ''D. melanogaster'' modulates the mitochondrial proteome and physiology. The effect on lifespan depends upon age and sex. https://doi.org/10.3390/ijms222111606. https://doi.org/10.3390/ijms222111606 )
Schmidt 2021 J Biol Chem + (Biological energy transduction underlies a … Biological energy transduction underlies all physiological phenomena in cells. The metabolic systems that support energy transduction have been of great interest due to their association with numerous pathologies including diabetes, cancer, rare genetic diseases, and aberrant cell death. Commercially available bioenergetics technologies (e.g. extracellular flux analysis, high resolution respirometry, fluorescent dye kits, etc.) have made practical assessment of metabolic parameters widely accessible. This has facilitated an explosion in the number of studies exploring, in particular, the biological implications of oxygen consumption rate (OCR) and substrate level phosphorylation via glycolysis (i.e. via extracellular acidification rate (ECAR)). Though these technologies have demonstrated substantial utility and broad applicability to cell biology research, they are also susceptible to historical assumptions, experimental limitations, and other caveats that have led to premature and/or erroneous interpretations. This review enumerates various important considerations for designing and interpreting cellular and mitochondrial bioenergetics experiments, some common challenges and pitfalls in data interpretation, and some potential ‘next steps’ to be taken that can address these highlighted challenges. can address these highlighted challenges.)
Austvold 2024 Front Physiol + (Biological magnetic field sensing that giv … Biological magnetic field sensing that gives rise to physiological responses is of considerable importance in quantum biology. The radical pair mechanism (RPM) is a fundamental quantum process that can explain some of the observed biological magnetic effects. In magnetically sensitive radical pair (RP) reactions, coherent spin dynamics between singlet and triplet pairs are modulated by weak magnetic fields. The resulting singlet and triplet reaction products lead to distinct biological signaling channels and cellular outcomes. A prevalent RP in biology is between flavin semiquinone and superoxide (O2•−) in the biological activation of molecular oxygen. This RP can result in a partitioning of reactive oxygen species (ROS) products to form either O2•− or hydrogen peroxide (H2O2). Here, we examine magnetic sensing of recombinant human electron transfer flavoenzyme (ETF) reoxidation by selectively measuring O2•− and H2O2 product distributions. ROS partitioning was observed between two static magnetic fields at 20 nT and 50 μT, with a 13% decrease in H2O2 singlet products and a 10% increase in O2•− triplet products relative to 50 µT. RPM product yields were calculated for a realistic flavin/superoxide RP across the range of static magnetic fields, in agreement with experimental results. For a triplet born RP, the RPM also predicts about three times more O2•− than H2O2, with experimental results exhibiting about four time more O2•− produced by ETF. The method presented here illustrates the potential of a novel magnetic flavoprotein biological sensor that is directly linked to mitochondria bioenergetics and can be used as a target to study cell physiology.ore O2•− produced by ETF. The method presented here illustrates the potential of a novel magnetic flavoprotein biological sensor that is directly linked to mitochondria bioenergetics and can be used as a target to study cell physiology.)
Blanco 2017 Academic Press + (Biological oxidations do not take place by … Biological oxidations do not take place by direct transfer of electrons (e−) from substrate to oxygen. They are carried out in successive stages by different e− acceptors with increasing reduction potential. This allows for a stepwise release of energy and its best utilization by the cell. The respiratory chain, located in the mitochondrial inner membrane, comprises a series of H or electrons (e−) acceptors arranged according to increasing reduction potential, associated with enzymes that catalyze e− transfer. It is composed of complex I or NADH–ubiquinone reductase, complex II or succinate–ubiquinone reductase, ubiquinone or coenzyme Q, complex III or ubiquinone–cytochrome c reductase, cytochrome c, located on the outer face of inner membrane, complex IV or cytochrome oxidase. Finally 4 e− are transferred to 2 O atoms, which with 4 H+ form 2 H2O. The energy produced by the flow of e− is coupled to phosphoryl transfer, synthesizing adenosine triphosphate (ATP) from ADP in a process known as oxidative phosphorylation. Each e− pair from substrates of NAD-linked dehydrogenases generates three molecules of ATP, while substrates oxidized by FAD-dependent enzymes produce two ATP. The chemio-osmotic hypothesis explains the mechanism underlying oxidative phosphorylation. The energy generated by the flow of reducing equivalents is used to pump protons from the mitochondrial matrix outward into the inner membrane, at the site of complexes I, III, and IV. The proton gradient created across the mitochondrial inner membrane drives proton flux through the F1F0 or ATP synthase complex, which couples proton transport to phosphate addition to ADP. Compounds that reduce or eliminate the proton gradient inhibit phosphorylation. Inhibitors can block e− transfer at different levels of the respiratory chain. Rotenone, amytal, and other barbiturates act at the level of complex I; antimycin A, at complex III; and cyanide, carbon monoxide, and azide, on complex IV. Inhibitors of oxidative phosphorylation include proton and K+ ionophores, which suppress the mitochondrial electrical potential gradient, acting as uncoupling agents, and compounds, such as oligomycin, which interfere with the function of the F1F0 ATPase. Brown fat present in infants and hibernating animals has thermogenin, a protein that inhibits ATP synthesis, uncoupling mitocondrial function and contributing to maintain body temperature. Oxidative phosphorylation is mainly controlled by ADP levels. Phosphorylation at substrate level is another way to generate ATP by phosphoryl transfer from high energy metabolites.ryl transfer from high energy metabolites.)
Koch 2021 Trends Ecol Evol + (Biologists have long appreciated the criti … Biologists have long appreciated the critical role that energy turnover plays in understanding variation in performance and fitness among individuals. Whole-organism metabolic studies have provided key insights into fundamental ecological and evolutionary processes. However, constraints operating at subcellular levels, such as those operating within the mitochondria, can also play important roles in optimizing metabolism over different energetic demands and time scales. Herein, we explore how mitochondrial aerobic metabolism influences different aspects of organismal performance, such as through changing adenosine triphosphate (ATP) and reactive oxygen species (ROS) production. We consider how such insights have advanced our understanding of the mechanisms underpinning key ecological and evolutionary processes, from variation in life-history traits to adaptation to changing thermal conditions, and we highlight key areas for future research.e highlight key areas for future research.)
Biophysical Society Symposium 2015 + (Biophysical Society – Bioenergetics Subgroup Mini-Symposium, Baltimore, MD, USA)
Scaini 2015 Abstract IOC106 + (Bipolar disorder (BD) presents a complex a … Bipolar disorder (BD) presents a complex alternating clinical course withrecurrent mood changes including manic and depressive episodes. Moreover,studies show that changes in energy metabolism are involved in thepathophysiology of BD and that omega-3 (ω3) fatty acids have beneficialproperties in the central nervous system, by modulate energy metabolism.Thus, in the present study we evaluate the effect of ω3 fatty acids alone or incombination with lithium or valproate on bioenergetic parameters, namelyrespiratory complexes (CI, CII, CII–III, CIV), malate dehydrogenase, succinatedehydrogenase, citrate synthase and creatine kinase activities. We observeda significant decrease of succinate dehydrogenase, complexes II and IV andcreatine kinase activities in hippocampus of animals submitted to fenproporexadministration, as compared to the control group. Additionally, the ω3 fattyacids in combination with VPA or Li were able to reverse the decrease insuccinate dehydrogenase, complexes II and IV activities. However, thedecrease in CK activity was reversed only with ω3 fatty acids in associationwith VPA. The present findings support the idea that ω3 fatty acid plays animportant role in the modulation of energy metabolism, and exercise essentialantioxidant capacity in the central nervous system, suggesting that the ω3fatty acids may be a possible contributing in BD therapy. be a possible contributing in BD therapy.)
Moon 2012 J Korean Med Sci + (Bisphenol A (BPA) has been reported to pos … Bisphenol A (BPA) has been reported to possess hepatic toxicity. We investigated the hypothesis that BPA, below the no observed adverse effect level (NOAEL), can induce hepatic damage and mitochondrial dysfunction by increasing oxidative stress in the liver. Two doses of BPA, 0.05 and 1.2 mg/kg body weight/day, were administered intraperitoneally for 5 days to mice. Both treatments impaired the structure of the hepatic mitochondria, although oxygen consumption rate and expression of the respiratory complex decreased only at the higher dose. The hepatic levels of malondialdehyde (MDA), a naturally occurring product of lipid peroxidation, increased, while the expression of glutathione peroxidase 3 (GPx3) decreased, after BPA treatment. The expression levels of proinflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) also increased. In HepG2 cells, 10 or 100 nM of BPA also decreased the oxygen consumption rate, ATP production, and the mitochondrial membrane potential. In conclusion, doses of BPA below the NOAEL induce mitochondrial dysfunction in the liver, and this is associated with an increase in oxidative stress and inflammation.ease in oxidative stress and inflammation.)
Maciocci 2019 eLife + (Blending the traditional manuscript with l … Blending the traditional manuscript with live code, data and interactive figures, we showcase a new way for researchers to tell their full story. In September 2017 eLife announced the start of the Reproducible Document Stack (RDS) project, a collaboration between Substance, Stencila and eLife to support the development of an open-source technology stack aimed at enabling researchers to publish reproducible manuscripts through online journals. Reproducible manuscripts enrich the traditional narrative of a research article with code, data and interactive figures that can be executed in the browser, downloaded and explored, giving readers a direct insight into the methods, algorithms and key data behind the published research.Today eLife, in collaboration with Substance, Stencila and Tim Errington, Director of Research ar the Center for Open Science, US, published its first reproducible article, based on one of Errington’s papers in the Reproducibility Project: Cancer Biology. This reproducible version of the article showcases some of what’s possible with the new RDS tools, and we invite researchers to explore the newly available opportunities to tell their story.ailable opportunities to tell their story.)
Tyrrell 2016 Redox Biol + (Blood based bioenergetic profiling strateg … Blood based bioenergetic profiling strategies are emerging as potential reporters of systemic mitochondrial function; however, the extent to which these measures reflect the bioenergetic capacity of other tissues is not known. The premise of this work is that highly metabolically active tissues, such as skeletal and cardiac muscle, are susceptible to differences in systemic bioenergetic capacity. Therefore, we tested whether the respiratory capacity of blood cells, monocytes and platelets, are related to contemporaneous respirometric assessments of skeletal and cardiac muscle mitochondria. 18 female vervet/African green monkeys (''Chlorocebus aethiops sabaeus'') of varying age and metabolic status were examined for this study. Monocyte and platelet maximal capacity correlated with maximal oxidative phosphorylation capacity of permeabilized skeletal muscle (R=0.75, 95% confidence interval [CI]: 0.38-0.97; R=0.51, 95%CI: 0.05-0.81; respectively), isolated skeletal muscle mitochondrial respiratory control ratio (RCR; R=0.70, 95%CI: 0.35-0.89; R=0.64, 95%CI: 0.23-0.98; respectively), and isolated cardiac muscle mitochondrial RCR (R=0.55, 95%CI: 0.22-0.86; R=0.58, 95%CI: 0.22-0.85; respectively). These results suggest that blood based bioenergetic profiling may be used to report on the bioenergetic capacity of muscle tissues. Blood cell respirometry represents an attractive alternative to tissue based assessments of mitochondrial function in human studies based on ease of access and the minimal participant burden required by these measures.Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.shed by Elsevier B.V. All rights reserved.)
Mahapatra 2024 J Gerontol A Biol Sci Med Sci + (Blood based mitochondrial bioenergetic pro … Blood based mitochondrial bioenergetic profiling is a feasible, economical, and minimally invasive approach that can be used to examine mitochondrial function and energy metabolism in human subjects. In this study, we use two complementary respirometric techniques to evaluate mitochondrial bioenergetics in both intact and permeabilized peripheral blood mononuclear cells (PBMCs) and platelets to examine sex dimorphism in mitochondrial function among older adults. Employing equal numbers of PBMCs and platelets to assess mitochondrial bioenergetics, we observe significantly higher respiration rates in female compared to male participants. Mitochondrial bioenergetic differences remain significant after controlling for independent parameters including demographic parameters (age, years of education), and cognitive parameters (mPACC5, COGDX). Our study illustrates that circulating blood cells, immune cells in particular, have distinctly different mitochondrial bioenergetic profiles between females and males. These differences should be taken into account as blood based bioenergetic profiling is now commonly used to understand the role of mitochondrial bioenergetics in human health and aging.l bioenergetics in human health and aging.)
Pignanelli 2019 Thesis + (Blood flow restriction during resistance e … Blood flow restriction during resistance exercise is an effective method for increasing muscular size and strength. However, skeletal muscle adaptations to low-load resistance exercise (LL-RE) and low-load blood flow restriction resistance exercise (LL-BFR) performed to repetition failure are lacking. Whole-body and skeletal muscle physiological outcomes were measured following 6-weeks of LL-RE and LL-BFR training to repetition failure using a within-subject design. Similar muscle strength and size outcomes occurred despite lower total exercise volume with LL-BFR. Both groups increased power output during the first-third of an endurance task and only LL-BFR training sustained a greater power output during the midpoint by 18%. Capillary contacts of type I muscle fibers increased similarly for both groups and only LL-RE training increased mitochondrial respiratory capacity by 20%. Overall, differences in muscle fatigue between LL-RE and LL-BFR may exist and are not explained by muscular strength and size or muscle microvascular and mitochondrial properties.icrovascular and mitochondrial properties.)
Lasalvia 2018 PLOS ONE + (Blood is a fluid connective tissue of huma … Blood is a fluid connective tissue of human body, where it plays vital functions for the nutrition, defense and well-being of the organism. When circulating in peripheral districts, it is exposed to some physical stresses coming from outside the human body, as electromagnetic fields (EMFs) which can cross the skin. Such fields may interact with biomolecules possibly inducing non thermal-mediated biological effects at the cellular level. In this study, the occurrence of biochemical/biological modifications in human peripheral blood lympho-monocytes exposed in a reverberation chamber for times ranging from 1 to 20 h to EMFs at 1.8 GHz frequency and 200 V/m electric field strength was investigated. Morphological analysis of adherent cells unveiled, in some of these, appearance of an enlarged and deformed shape after EMFs exposure. Raman spectra of the nuclear compartment of cells exposed to EMFs revealed the onset of biochemical modifications, mainly consisting in the reduction of the DNA backbone-linked vibrational modes. Respirometric measurements of mitochondrial activity in intact lympho-monocytes resulted in increase of the resting oxygen consumption rate after 20 h of exposure, which was coupled to a significant increase of the FoF1-ATP synthase-related oxygen consumption. Notably, at lower time-intervals of EMFs exposure (i.e. 5 and 12 h) a large increase of the proton leak-related respiration was observed which, however, recovered at control levels after 20 h exposure. Confocal microscopy analysis of the mitochondrial membrane potential supported the respiratory activities whereas no significant variations in the mitochondrial mass/morphology was observed in EMFs-exposed lympho-monocytes. Finally, altered redox homeostasis was shown in EMFs-exposed lympho-monocytes, which progressed differently in nucleated cellular subsets. These results suggest the occurrence of adaptive mechanisms put in action, likely via redox signaling, to compensate for early impairments of the oxidative phosphorylation system caused by exposure to EMFs. Overall the data presented warn for health safety of people involved in long-term exposure to electromagnetic fields, although further studies are required to pinpoint the leukocyte cellular subset(s) selectively targeted by the EMFs action and the mechanisms by which it is achieved.nd the mechanisms by which it is achieved.)
Siewiera 2022 Int J Mol Sci + (Blood platelet dysfunctions are strongly i … Blood platelet dysfunctions are strongly involved in the development of the micro- and macrovascular complications in diabetes mellitus (DM). However, the molecular causes of abnormal platelet activation in DM remain unclear. Experimental data suggests that platelet mitochondria can regulate the prothrombotic phenotype of platelets, and changes in these organelles may influence platelet activation and modify platelet responses to stimulation. The present study evaluates the impact of DM on mitochondrial respiratory parameters and blood platelet activation/reactivity in a rat model of experimental diabetes following 1, 2.5 and 5 months of streptozotocin (STZ)-induced diabetes. Moreover, a mild inhibition of the mitochondrial respiratory chain with the use of metformin under ''in vitro'' and ''in vivo'' conditions was tested as a method to reduce platelet activation and reactivity. The platelets were studied with a combination of flow cytometry and advanced respirometry. Our results indicate that prolonged exposure of blood platelets to high concentrations of glucose, as in diabetes, can result in elevated blood platelet mitochondrial respiration; this may be an effect of cell adaptation to the high availability of energy substrates. However, as these alterations occur later than the changes in platelet activation/reactivity, they may not constitute the major reason for abnormal platelet functioning in DM. Moreover, metformin was not able to inhibit platelet activation and reactivity under ''in vitro'' conditions despite causing a decrease in mitochondrial respiration. This indicates that the beneficial effect of metformin on the coagulation system observed ''in vivo'' can be related to other mechanisms than via the inhibition of platelet activation.via the inhibition of platelet activation.)
Siewiera 2021 Int J Mol Sci + (Blood platelets are considered as promisin … Blood platelets are considered as promising candidates as easily-accessible biomarkers of mitochondrial functioning. However, their high sensitivity to various stimulus types may potentially affect mitochondrial respiration and lead to artefactual outcomes. Therefore, it is crucial to identify the factors associated with platelet preparation that may lead to changes in mitochondrial respiration. A combination of flow cytometry and advanced respirometry was used to examine the effect of blood anticoagulants, the media used to suspend isolated platelets, respiration buffers, storage time and ADP stimulation on platelet activation and platelet mitochondria respiration. Our results clearly show that all the mentioned factors can affect platelet mitochondrial respiration. Briefly, (i) the use of EDTA as anticoagulant led to a significant increase in the dissipative component of respiration (LEAK), (ii) the use of plasma for the suspension of isolated platelets with MiR05 as a respiration buffer allows high electron transfer capacity and low platelet activation, and (iii) ADP stimulation increases physiological coupling respiration (ROUTINE). Significant associations were observed between platelet activation markers and mitochondrial respiration at different preparation steps; however, the fact that these relationships were not always apparent suggests that the method of platelet preparation may have a greater impact on mitochondrial respiration than the platelet activation itself.ation than the platelet activation itself.)
Nauta 2016 Thesis + (Blood vessels are crucial in the mammalian … Blood vessels are crucial in the mammalian body for the delivery of oxygen, nutrients andsignaling molecules, such as hormones, to cells and the removal of waste product from thesecells. Endothelial cells (ECs) line the entire vasculature. In the healthy body, most ECs arequiescent; the cells hardly divide. Nonetheless, the endothelium performs manyphysiological functions, such as vasoregulation by producing vasoactive factors includingnitric oxide (NO) and endothelin-1 (ET-1) required for adequate distribution of bloodbetween the tissues; formation of a barrier between blood and surrounding tissues that allowsoptimal exchange of oxygen, nutrients and hormones; hemostasis; and the recruitment ofleukocytes at sites of inflammation (3). Dysfunction of the endothelium is associated withmany diseases, such as atherosclerosis, hypertension, thrombosis and improper inflammatoryactivation of tissues; endothelial barrier dysfunction leads to vascular leakage, which isrelated to pathological conditions, including sepsis (21), acute lung injury (47), and cancer(25). Improper functioning of tissues often results in inadequate perfusion and the need foradditional blood supply. This can occur by neovascularization, a process in which endothelialcells play a central role. This thesis investigates the effect of long-term hypoxia on theresponse of endothelial cells that leads to improved vascularization.ls that leads to improved vascularization.)
Mahapatra 2018 Clin Sci (Lond) + (Blood-based bioenergetic profiling has pro … Blood-based bioenergetic profiling has promising applications as a minimally invasive biomarker of systemic bioenergetic capacity. In the present study, we examined peripheral blood mononuclear cell (PBMC) mitochondrial function and brain morphology in a cohort of African Americans with long-standing Type 2 diabetes. Key parameters of PBMC respiration were correlated with white matter, gray matter, and total intracranial volumes. Our analyses indicate that these relationships are primarily driven by the relationship of systemic bioenergetic capacity with total intracranial volume, suggesting that systemic differences in mitochondrial function may play a role in overall brain morphology.y play a role in overall brain morphology.)
Marie 2018 Cell Death Dis + (Blue light is an identified risk factor fo … Blue light is an identified risk factor for age-related macular degeneration (AMD). We investigated oxidative stress markers and mitochondrial changes in A2E-loaded retinal pigment epithelium cells under the blue-green part of the solar spectrum that reaches the retina to better understand the mechanisms underlying light-elicited toxicity.Primary retinal pigment epithelium cells were loaded with a retinal photosensitizer, AE2, to mimic aging. Using a custom-made illumination device that delivers 10 nm-wide light bands, we demonstrated that A2E-loaded RPE cells generated high levels of both hydrogen peroxide (H2O2) and superoxide anion (O2•-) when exposed to blue-violet light. In addition, they exhibited perinuclear clustering of mitochondria with a decrease of both their mitochondrial membrane potential and their respiratory activities. The increase of oxidative stress resulted in increased levels of the oxidized form of glutathione and decreased superoxide dismutase (SOD) and catalase activities. Furthermore, mRNA expression levels of the main antioxidant enzymes (SOD2, catalase, and GPX1) also decreased.Using an innovative illumination device, we measured the precise action spectrum of the oxidative stress mechanisms on A2E-loaded retinal pigment epithelium cells. We defined 415-455 nm blue-violet light, within the solar spectrum reaching the retina, to be the spectral band that generates the highest amount of reactive oxygen species and produces the highest level of mitochondrial dysfunction, explaining its toxic effect. This study further highlights the need to filter these wavelengths from the eyes of AMD patients.udy further highlights the need to filter these wavelengths from the eyes of AMD patients.)
Gnaiger 2020 APS Chicago + (Body mass excess accumulated in sedentary … Body mass excess accumulated in sedentary lifestyles leads to deceleration of running speed. How does obesity, however, cause dementia and psychological disorders? Systemic decline of mitochondrial fitness from muscle to brain links the obesogenic lifestyle to common comorbidities. mitObesity represents the world-wide leading cause of early aging, neurodegeneration, and deaths.arly aging, neurodegeneration, and deaths.)
Dagan 2013 Nutr J + (Body mass index (BMI) is more commonly use … Body mass index (BMI) is more commonly used than waist circumference as a measure of adiposity in clinical and research settings. The purpose of this study was to compare the associations of BMI and waist circumference with cardiorespiratory fitness.In a cross-sectional study of 403 healthy men and women aged 50 ± 8.8 years, BMI and waist circumference were measured. Cardiorespiratory fitness was assessed from estimated maximal O2 uptake (VO2max), as calculated from a maximal fitness test.Mean BMI (kg/m2) was 27.8 ± 3.7 and 25.5 ± 4.6; and mean waist circumference (cm) 94.1 ± 9.7 and 84.3 ± 10.4 for men and women, respectively. Both men and women reported an average of 2.5 hours of weekly sports related physical activity, and 18% were current smokers. Correlation coefficients between both BMI and waist circumference, and VO2max were statistically significant in men (r= -0.280 and r= -0.377, respectively, p>0.05 for both) and in women (r= -0.514 and r= -0.491, respectively, p>0.05 for both). In women, the contribution of BMI to the level of VO2max in a regression model was greater, while in men waist circumference contributed more to the final model. In these models, age, hours of training per week, and weekly caloric expenditure in sport activity, significantly associated with VO2max, while smoking did not.The differences observed between the sexes in the associations of BMI and waist circumference with VO2max support the clinical use of both obesity measures for assessment of cardiorespiratory fitness.res for assessment of cardiorespiratory fitness.)
Diverse Populations Collaborative Group 2005 Am J Phys Anthropol + (Body mass index (BMI, weight (kg)/height ( … Body mass index (BMI, weight (kg)/height (m)(2)) is the most widely used weight-height index worldwide. This universal use of BMI assumes that the rationale for its use is universally applicable. We examine two possible rationales for using BMI as a universal measure. The first rationale is that BMI is strongly correlated with weight, but is independent of height. The second rationale is that BMI correctly captures the relationship between weight and height, which implies that the slope of log weight regressed on log height is 2. We examined the weight-height relationship in 25 diverse population samples of men and women from the US, Europe, and Asia. The analysis included 72 subgroups with a total of 385,232 adults aged 25 years and older. Although BMI was highly correlated with weight in all studies, a significant, negative correlation between BMI and height was found in 31 out of 40 subgroups of men (r=-0.004 to -0.133) and 32 of 32 groups of women (r=-0.016 to -0.205). When log weight was regressed on log height, the 95% confidence intervals (CI) of the slopes did not include 2 in 25 out of 40 male subgroups. The summary estimate of the slopes across studies of men was 1.92 (95% CI, 1.87-1.97). For women, slopes were lower than 2 in 28 of 32 subgroups with a summary estimate of 1.45 (95% CI, 1.39-1.51). In most of the populations, BMI is not independent of height; weight does not universally vary with the square of height; and the relationship between weight and height differs significantly between males and females. The use of a single BMI standard for both men and women cannot be justified on the basis of weight-height relationships. the basis of weight-height relationships.)
Apovian 2016 Am J Manag Care + (Body mass index of 30 kg/m2< … Body mass index of 30 kg/m2 or higher is used to identify individuals with obesity. In the last 3 decades, the worldwide prevalence of obesity has increased 27.5 % for adults and 47.1 % for children. Obesity is the result of complex relationships between genetic, socioeconomic, and cultural influences. Consumption patterns, urban development, and lifestyle habits influence the prevalence of obesity. The condition may be the result of disease or pharmacologic treatment. It may also be a risk factor for the development of comorbid conditions. Persons who are obese have less school attendance, reduced earning potential, and higher healthcare costs that may result in an economic burden on society. A review of the prevalence and economic consequences of obesity is provided. Potential causes and comorbidities associated with obesity are also discussed.orbidities associated with obesity are also discussed.)
Weir 2019 StatPearls + (Body mass index or BMI is a statistical in … Body mass index or BMI is a statistical index using a person's weight and height to provide an estimate of body fat in males and females of any age. It is calculated by taking a person's weight, in kilograms, divided by their height, in meters squared, or BMI = weight (in kg)/ height^2 (in m^2). The number generated from this equation is then the individual's BMI number. The National Institute of Health (NIH) now uses BMI to define a person as underweight, normal weight, overweight, or obese instead of traditional height vs. weight charts. These classifications for BMI are in use by the NIH and the World Health Organization (WHO) for White, Hispanic, and Black individuals. The cutoffs underestimate the obesity risk in the Asian and South Asian populations, so their classification has slight alterations. The BMI number and classifications are listed below.[1][2] However, individual variations do exist, and BMI is insufficient as the sole means of classifying a person as obese or malnourished. In certain populations, like elite athletes and body-builders, an elevated BMI does not directly correlate to their health status due to their increased muscle mass and weight falsely increasing their BMI. Moreover, in the pediatric population, BMI allows comparison between children of the same sex and age. For children, a BMI that is less than the fifth percentile is underweight and above the 95th percentile is considered obese.[3]he 95th percentile is considered obese.[3])
NCD-RisC 2019 Nature + (Body-mass index (BMI) has increased steadi … Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities1,2. This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity3-6. Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55 % of the global rise in mean BMI from 1985 to 2017-and more than 80 % in some low- and middle-income regions-was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing-and in some countries reversal-of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories.ssive consumption of low-quality calories.)
De Oliveira 2014 Cell Tiss Res + (Bone marrow cells (BMCs) are the main type … Bone marrow cells (BMCs) are the main type of cells used for transplantation therapies. Obesity, a major world health problem, has been demonstrated to affect various tissues, including bone marrow. This could compromise the success of such therapies. One of the main mechanisms underlying the pathogenesis of obesity is mitochondrial dysfunction, and recent data have suggested an important role for mitochondrial metabolism in the regulation of stem cell proliferation and differentiation. Since the potential use of BMCs for clinical therapies depends on their viability and capacity to proliferate and/or differentiate properly, the analysis of mitochondrial function and cell viability could be important approaches for evaluating BMC quality in the context of obesity. We therefore compared BMCs from a control group (CG) and an obese group (OG) of mice and evaluated their mitochondrial function, proliferation capacity, apoptosis, and levels of proteins involved in energy metabolism. BMCs from OG had increased apoptosis and decreased proliferation rates compared with CG. Mitochondrial respiratory capacity, biogenesis, and the coupling between oxidative phosphorylation and ATP synthesis were significantly decreased in OG compared with CG, in correlation with increased levels of uncoupling protein 2 and reduced peroxisome proliferator-activated receptor-coactivator 1α content. OG also had decreased amounts of the glucose transporter GLUT-1 and insulin receptor (IRβ). Thus, Western-diet-induced obesity leads to mitochondrial dysfunction and reduced proliferative capacity in BMCs, changes that, in turn, might compromise the success of therapies utilizing these cells.uccess of therapies utilizing these cells.)
Connell 2021 J Nutr + (Boosting NAD+ via s … Boosting NAD+ via supplementation with niacin equivalents has been proposed as a potential modality capable of promoting healthy aging and negating age-dependent declines of skeletal muscle mass and function.We investigated the efficacy of NAD+-precursor supplementation (tryptophan, nicotinic acid, and nicotinamide) on skeletal muscle mitochondrial function in physically compromised older adults.A randomized, double-blind, controlled trial was conducted in 14 (female/male: 4/10) community-dwelling, older adults with impaired physical function [age, 72.9 ± 4.0 years; BMI, 25.2 ± 2.3 kg/m2]. Participants were supplemented with 207.5 mg niacin equivalents/day [intervention (INT)] and a control product (CON) that did not contain niacin equivalents, each for 32 days. The primary outcomes tested were mitochondrial oxidative capacity and exercise efficiency, analyzed by means of paired Student's t-tests. Secondary outcomes, such as NAD+ concentrations, were analyzed accordingly.Following supplementation, skeletal muscle NAD+ concentrations [7.5 ± 1.9 compared with 7.9 ± 1.6 AU, respectively] in INT compared with CON conditions were not significantly different compared to the control condition, whereas skeletal muscle methyl-nicotinamide levels were significantly higher under NAD+-precursor supplementation [INT, 0.098 ± 0.063 compared with CON, 0.025 ± 0.014; P = 0.001], suggesting an increased NAD+ metabolism. Conversely, neither ADP-stimulated [INT, 82.1 ± 19.0 compared with CON, 84.0 ± 19.2; P = 0.716] nor maximally uncoupled mitochondrial respiration [INT, 103.4 ± 30.7 compared with CON, 108.7 ± 33.4; P = 0.495] improved under NAD+-precursor supplementation, nor did net exercise efficiency during the submaximal cycling test [INT, 20.2 ± 2.77 compared with CON, 20.8 ± 2.88; P = 0.342].Our findings are consistent with previous findings on NAD+ efficacy in humans, and we show in community-dwelling, older adults with impaired physical function that NAD+-precursor supplementation through L-tryptophan, nicotinic acid, and nicotinamide does not improve mitochondrial or skeletal muscle function.;sup>+-precursor supplementation through L-tryptophan, nicotinic acid, and nicotinamide does not improve mitochondrial or skeletal muscle function.)
Karabatsiakis 2015 Abstract MiP2015 + (Borderline personality disorder (BPD) is c … Borderline personality disorder (BPD) is characterised by a pervasive pattern of instability of interpersonal relationships, self-image, affects, and marked by impulsivity [1]. Beside the pronounced psychological stress, patients with BPD show an increased risk for somatic disorders and an impaired immunity. The resulting high burden of patients suffering from BPD is associated with conditions of chronic stress, which negatively influences the reactivity of the cellular immune system [2,3]. So far, the underlying pathophysiological processes and long-term consequences of BPD on cellular immunity and energy metabolism are hardly explored.Here, we report first data on mitochondrial functioning and the quantity of mitochondria in immune cells from female patients with BPD (''n'' = 24), which were compared to an age- and gender-matched group of healthy controls (''n'' = 13). The severity of BPD symptoms was measured by the self-report questionnaire ''Borderline Symptom List'' (BSL), the severity of depressive symptoms by the ''Beck Depression Inventory'' (BDI). Peripheral blood mononuclear cells (PBMC) were isolated from whole blood (15 ml) using Ficoll dense gradient centrifugation. Total PBMC were cryopreserved in Mannheim and after thawing in Ulm, the respiratory activity was assessed in living cells in a high-resolution oxygraph 2k. Characterization of mitochondrial activity included the following parameters: ROUTINE, LEAK, uncoupled (ET-pathway), and Residual oxygen consumption (ROX). Respiration was controlled for the intracellular amount of mitochondria, which was assessed with the citrate synthase activity (CSA) assay, a spectrophotometric technique [4].We found no statistically significant alterations of mitochondrial activity in patients with BPD compared to controls. Interestingly, within the BPD group ATP turnover-related oxygen consumption was significantly correlated with both the severity of BPD (BSL sum score, ''r'' = 0.592, ''p'' = 0.010) and depressive symptoms (BDI sum score, ''r'' = 0.735, ''p'' = 0.001). Furthermore, there was a significant effect of depressive symptoms (BDI sum score) on residual oxygen consumption (ROX), the amount of oxygen consumed independently from ATP-production (''r'' = 0.450, ''p'' = 0.053). Finally, the CSA assay revealed no significant difference in the amount of mitochondria between the two groups. Chronic stress associated with BPD seems to negatively affect the homeostasis of immune cells, which has to be counteracted by a higher production of ATP. The increase of ROX subject to the severity of depressive symptoms provides evidence for the production of reactive oxygen species (ROS) in a dose-dependent manner. Consequently, the severity of depressive symptoms seems to have a stronger impact on mitochondrial functioning in immune cells than the severity of BPD. To address the question of a possible usage of mitochondrial respiration in immune cells as a new marker for the biological effects of BPD treatment, follow-up intervention studies with a longitudinal design are necessary. with a longitudinal design are necessary.)
Jusic 2019 ESCI2019 + (Bosnia and Herzegovina is one of the inclu … Bosnia and Herzegovina is one of the inclusiveness target countries (ITC) which joined the [[Management Committee MitoEAGLE |COST Action CA15203 MitoEAGLE]] in October 2018. A long transitional after-war period resulted in marginalization of science and slow development of academic and scientific research network in Bosnia and Herzegovina. The lack of top experts and permanent ‘’brain drain’’ explains why most Bosnian scientists apply only for limited national grants and have no chance to get some international grants because they are not sufficiently competitive compared to other West European research teams.The main goal of joining the COST Action MitoEAGLE is to engage in international and multidisciplinary collaborations that could be helpful in establishing high-level performance of the research group at the home institution. This multidisciplinary group will include experienced researchers from the human molecular genetics and cardiovascular fields. The aims of this group will be: introduction of novel methods for studying the role of noncoding RNAs in cardiovascular disease and mitochondrial function, either by regulating mitochondrial or nuclear genes that are known to influence mitochondrial function. Building such an interdisciplinary group will represent a significant result of the COST Action and will contribute to its goal to share knowledge and expertise. All involved institutions will gain experience and visibility by international and multidisciplinary collaborations.In conclusion, joining to the COST Action MitoEAGLE can open an opportunity particularly for young scientists to discover different ways to lead a scientific group and establish collaborations for future professional projects. As a result, early career researchers can create their own international network that will improve their future professional development and strengthen contacts between academic and industrial partners as a driving force for innovation. This will improve the skills of students and researchers to plan suitable outreach activities to the general public towards a better understanding of research and its implications on knowledge, society, and science development.owledge, society, and science development.)
Targeting Mitochondrial Dysfunction & Toxicity 2014 + (Boston, MA, USA; [http://www.healthtech.com/mitochondrial-targeting Targeting Mitochondrial Dysfunction & Toxicity - Treating Disease and Improving Drug Safety].)
Coen 2015 Diabetes + (Both Roux-en-Y gastric bypass (RYGB) surge … Both Roux-en-Y gastric bypass (RYGB) surgery and exercise can improve insulin sensitivity in individuals with severe obesity. However, the impact of RYGB with or without exercise on skeletal muscle mitochondria, intramyocellular lipids, and insulin sensitivity index (SI) is unknown. We conducted a randomized exercise trial in patients (''n'' = 101) who underwent RYGB surgery and completed either a 6-month moderate exercise (EX) or a health education control (CON) intervention. SI was determined by intravenous glucose tolerance test. Mitochondrial respiration and intramyocellular triglyceride, sphingolipid, and diacylglycerol content were measured in ''vastus lateralis'' biopsy specimens. We found that EX provided additional improvements in SI and that only EX improved cardiorespiratory fitness, mitochondrial respiration and enzyme activities, and cardiolipin profile with no change in mitochondrial content. Muscle triglycerides were reduced in type I fibers in CON, and sphingolipids decreased in both groups, with EX showing a further reduction in a number of ceramide species. In conclusion, exercise superimposed on bariatric surgery-induced weight loss enhances mitochondrial respiration, induces cardiolipin remodeling, reduces specific sphingolipids, and provides additional improvements in insulin sensitivity.ic sphingolipids, and provides additional improvements in insulin sensitivity.)
Attane 2012 Diabetes + (Both acute and chronic apelin treatment ha … Both acute and chronic apelin treatment have been shown to improve insulin sensitivity in mice. However, the effects of apelin on fatty acid oxidation (FAO) during obesity-related insulin resistance have not yet been addressed. Thus, the aim of the current study was to determine the impact of chronic treatment on lipid use, especially in skeletal muscles. High-fat diet (HFD)-induced obese and insulin-resistant mice treated by an apelin injection (0.1 μmol/kg/day i.p.) during 4 weeks had decreased fat mass, glycemia, and plasma levels of triglycerides and were protected from hyperinsulinemia compared with HFD PBS-treated mice. Indirect calorimetry experiments showed that apelin-treated mice had a better use of lipids. The complete FAO, the oxidative capacity, and mitochondrial biogenesis were increased in soleus of apelin-treated mice. The action of apelin was AMP-activated protein kinase (AMPK) dependent since all the effects studied were abrogated in HFD apelin-treated mice with muscle-specific inactive AMPK. Finally, the apelin-stimulated improvement of oxidative capacity led to decreased levels of acylcarnitines and enhanced insulin-stimulated glucose uptake in soleus. Thus, by promoting complete lipid use in muscle of insulin-resistant mice through mitochondrial biogenesis and tighter matching between FAO and the tricarboxylic acid cycle, apelin treatment could contribute to insulin sensitivity improvement.ribute to insulin sensitivity improvement.)
Korge 2015 Biochim Biophys Acta + (Both extremes of redox balance are known t … Both extremes of redox balance are known to cause cardiac injury, with mounting evidence revealing that the injury induced by both oxidative and reductive stress is oxidative in nature. During reductive stress, when electron acceptors are expected to be mostly reduced, some redox proteins can donate electrons to O2 instead, which increases reactive oxygen species (ROS) production. However, the high level of reducing equivalents also concomitantly enhances ROS scavenging systems involving redox couples such as NADPH/NADP+ and GSH/GSSG. Here our objective was to explore how reductive stress paradoxically increases net mitochondrial ROS production despite the concomitant enhancement of ROS scavenging systems. Using recombinant enzymes and isolated permeabilized cardiac mitochondria, we show that two normally antioxidant matrix NADPH reductases, glutathione reductase and thioredoxin reductase, generate H2O2 by leaking electrons from their reduced flavoprotein to O2 when electron flow is impaired by inhibitors or because of limited availability of their natural electron acceptors, GSSG and oxidized thioredoxin. The spillover of H2O2 under these conditions depends on H2O2 reduction by peroxiredoxin activity, which may regulate redox signaling in response to endogenous or exogenous factors. These findings may explain how ROS production during reductive stress overwhelms ROS scavenging capability, generating the net mitochondrial ROS spillover causing oxidative injury. These enzymes could potentially targeted to increase cancer cell death or modulate H2O2-induced redox signaling to protect the heart against ischemia/reperfusion damage.heart against ischemia/reperfusion damage.)
Baekkerud 2019 Cardiovasc Toxicol + (Both human and animal studies have shown m … Both human and animal studies have shown mitochondrial and contractile dysfunction in hearts of type 2 diabetes mellitus (T2DM). Exercise training has shown positive effects on cardiac function, but its effect on the mitochondria have been insufficiently explored. The aim of this study was to assess the effect of exercise training on mitochondrial function in T2DM hearts. We divided T2DM mice (db/db) into a sedentary and an interval training group at 8 weeks of age and used heterozygote db/+ as controls. After 8 weeks of training, we evaluated mitochondrial structure and function, as well as the levels of mRNA and proteins involved in key metabolic processes from the left ventricle. db/db animals showed decreased oxidative phosphorylation capacity and fragmented mitochondria. Mitochondrial respiration showed a blunted response to Ca2+ along with reduced protein levels of the mitochondrial calcium uniporter. Exercise training ameliorated the reduced oxidative phosphorylation in complex (C) I + II, CII and CIV, but not CI or Ca2+ response. Mitochondrial fragmentation was partially restored. mRNA levels of isocitrate, succinate and oxoglutarate dehydrogenase were increased in db/db mice and normalized by exercise training. Exercise training induced an upregulation of two transcripts of peroxisome proliferator activated receptor gamma coactivator 1 alpha (PGC1α1 and PGC1α4) previously linked to endurance training adaptations and strength training adaptations, respectively. The T2DM heart showed mitochondrial dysfunction at multiple levels and exercise training ameliorated some, but not all mitochondrial dysfunctions.training ameliorated some, but not all mitochondrial dysfunctions.)
Kristian 2007 J Neurochem + (Both isolated brain mitochondria and mitoc … Both isolated brain mitochondria and mitochondria in intact neurons are capable of accumulating large amounts of calcium, which leads to formation in the matrix of calcium- and phosphorus-rich precipitates, the chemical composition of which is largely unknown. Here, we have used inhibitors of the mitochondrial permeability transition (MPT) to determine how the amount and rate of mitochondrial calcium uptake relate to mitochondrial morphology, precipitate composition, and precipitate retention. Using isolated rat brain (RBM) or liver mitochondria (RLM) Ca(2+)-loaded by continuous cation infusion, precipitate composition was measured in situ in parallel with Ca(2+) uptake and mitochondrial swelling. In RBM, the endogenous MPT inhibitors adenosine 5'-diphosphate (ADP) and adenosine 5'-triphosphate (ATP) increased mitochondrial Ca(2+) loading capacity and facilitated formation of precipitates. In the presence of ADP, the Ca/P ratio approached 1.5, while ATP or reduced infusion rates decreased this ratio towards 1.0, indicating that precipitate chemical form varies with the conditions of loading. In both RBM and RLM, the presence of cyclosporine A in addition to ADP increased the Ca(2+) capacity and precipitate Ca/P ratio. Following MPT and/or depolarization, the release of accumulated Ca(2+) is rapid but incomplete; significant residual calcium in the form of precipitates is retained in damaged mitochondria for prolonged periods.amaged mitochondria for prolonged periods.)
Fuller 2020 J Appl Physiol (1985) + (Both lipid oversupply and poor mitochondri … Both lipid oversupply and poor mitochondrial function (low respiration and elevated H2O2 emission) have been implicated in the development of hepatic steatosis and liver injury. Mitophagy, the targeted degradation of low functioning mitochondria, is critical for maintaining mitochondrial quality control. Here, we used intralipid injections combined with acute (4day) and chronic (4-7wk) high-fat diets (HFD) to examine if hepatic mitochondrial respiration would decrease and H2O2 emission would increase with lipid overload. We tested these effects in male and female wild type (WT) mice and mice null for a critical mediator of mitophagy, BNIP3 (BNIP3 KO) housed at thermoneutral temperatures. Intralipid injection was successful in elevating serum triglycerides and NEFAs but had no impact on hepatic mitochondrial respiratory function or H2O2 emission. However, female mice had greater mitochondrial respiration on the acute HFD, lower H2O2 emission across both HFD durations, and were protected against hepatic steatosis. Unexpectedly, BNIP3 KO animals had greater hepatic mitochondrial respiration, better coupled respiration, and increased electron chain protein content after the 4day HFD compared to WT animals. Altogether, these data suggest that acute lipid overload delivered by a single intralipid bolus does not alter hepatic mitochondrial outcomes, but rather sex and genotype profoundly impact hepatic mitochondrial respiration and H2O2 emission.ondrial outcomes, but rather sex and genotype profoundly impact hepatic mitochondrial respiration and H2O2 emission.)
Bespalov 2019 Eur Neuropsychopharmacol + (Both positive and negative (null or neutra … Both positive and negative (null or neutral) results are essential for the progress of science and its self-correcting nature. However, there is general reluctance to publish negative results, and this may be due a range of factors (e.g., the widely held perception that negative results are more difficult to publish, the preference to publish positive findings that are more likely to generate citations and funding for additional research). It is particularly challenging to disclose negative results that are not consistent with previously published positive data, especially if the initial publication appeared in a high impact journal. Ideally, there should be both incentives and support to reduce the costs associated with investing efforts into preparing publications with negative results. We describe here a set of criteria that can help scientists, reviewers and editors to publish technically sound, scientifically high-impact negative (or null) results originating from rigorously designed and executed studies. Proposed criteria emphasize the importance of collaborative efforts and communication among scientists (also including the authors of original publications with positive results).ginal publications with positive results).)
Tomec 1975 Arch Biochem Biophys + (Bovine fetal heart mitochondria oxidize pa … Bovine fetal heart mitochondria oxidize palmitoyl-CoA in the presence of I-carnitineat 2-148 of the rate they oxidize palmitoyl-I-camitine when incubation times are lessthan 5 min. The initial low oxidation rate with palmitoyl-CoA is not significantlychanged by increasing the concentration of ADP in the incubation. Preincubation offetal heart mitochondria with palmitofl-CoA plus carnitine for 10 min before initiatingoxidation with ADP leads to oxidation rates that are comparable to those obtained in calfheart mitochondria. The total camitine palmitoyltransferase activity in fetal heartmitochondria is not strikingly different from calf heart mitochondria. The palmitoyl-CoA saturation curves show that deficiency in “overt” carnitine palmitoyltransferase(A)activity in fetal heart mitochondria cannot account for these observations. Our resultsshow an abnormal CoA saturation curve of fetal heart mitochondrial transferase activitybut the relationship of this finding to the lag period before maximal oxidation ofpalmitoyl-CoA is not known.l oxidation of palmitoyl-CoA is not known.)
Frawley 2017 Chem Res Toxicol + (Bovine pulmonary artery endothelial cells … Bovine pulmonary artery endothelial cells (BPAEC) respond in a dose-dependent manner to millimolar (0-10) levels of sodium sulfide (NaHS). No measurable increase in caspase-3 activity and no change in the extent of autophagy (or mitophagy) were observed in BPAEC. However, lactate dehydrogenase levels increased in the BPAEC exposed NaHS, which indicated necrotic cell death. In the case of galactose-conditioned BPAEC, the toxicity of NaHS was increased by 30% compared to that observed in BPAEC maintained in the regular glucose-containing culture medium, which indicated a link between mitochondrial oxidative phosphorylation and the mechanism of toxicant action. This is consistent with the widely held view that cytochrome c oxidase (complex IV of the mitochondrial electron-transport system) is the principal molecular target involved in the acute toxicity of "sulfide" (H2S/HS-). In support of this view, elevated NO (which can reverse cytochrome c oxidase inhibition) ameliorated the toxicity of NaHS and, conversely, suppression of endogenous NO production exacerbated the observed toxicity. Respirometric measurements showed the BPAEC to possess a robust sulfide oxidizing system, which was able to out-compete cytochrome c oxidase for available H2S/HS- at micromolar concentrations. This detoxification system has previously been reported by other groups in several cell types, but notably, not neurons. The findings appear to provide some insight into the question of why human survivors of H2S inhalation frequently present at the clinic with respiratory insufficiency/pulmonary edema, while acutely poisoned laboratory animals tend to either succumb to cardiopulmonary paralysis or fully recover without any intervention.uccumb to cardiopulmonary paralysis or fully recover without any intervention.)
Thomsen 2017 Neurobiol Aging + (Brain aging is accompanied by declining mi … Brain aging is accompanied by declining mitochondrial respiration. We hypothesized that mitochondrial morphology and dynamics would reflect this decline. Using hippocampus and frontal cortex of a segmental progeroid mouse model lacking Cockayne syndrome protein B (CSBm/m) and C57Bl/6 (WT) controls and comparing young (2-5 months) to middle-aged mice (13-14 months), we found that complex I-linked state 3 respiration (CI) was reduced at middle age in CSBm/m hippocampus, but not in CSBm/m cortex or WT brain. In hippocampus of both genotypes, mitochondrial size heterogeneity increased with age. Notably, an inverse correlation between heterogeneity and CI was found in both genotypes, indicating that heterogeneity reflects mitochondrial dysfunction. The ratio between fission and fusion gene expression reflected age-related alterations in mitochondrial morphology but not heterogeneity. Mitochondrial DNA content was lower, and hypoxia-induced factor 1α mRNA was greater at both ages in CSBm/m compared to WT brain. Our findings show that decreased CI and increased mitochondrial size heterogeneity are highly associated and point to declining mitochondrial quality control as an initial event in brain aging.d and point to declining mitochondrial quality control as an initial event in brain aging.)
Reutzel 2020 Oxid Med Cell Longev + (Brain aging is one of the major risk facto … Brain aging is one of the major risk factors for the development of several neurodegenerative diseases. Therefore, mitochondrial dysfunction plays an important role in processes of both, brain aging and neurodegeneration. Aged mice including NMRI mice are established model organisms to study physiological and molecular mechanisms of brain aging. However, longitudinal data evaluated in one cohort are rare but are important to understand the aging process of the brain throughout life, especially since pathological changes early in life might pave the way to neurodegeneration in advanced age. To assess the longitudinal course of brain aging, we used a cohort of female NMRI mice and measured brain mitochondrial function, cognitive performance, and molecular markers every 6 months until mice reached the age of 24 months. Furthermore, we measured citrate synthase activity and respiration of isolated brain mitochondria. Mice at the age of three months served as young controls. At six months of age, mitochondria-related genes (complex IV, creb-1, β-AMPK, and Tfam) were significantly elevated. Brain ATP levels were significantly reduced at an age of 18 months while mitochondria respiration was already reduced in middle-aged mice which is in accordance with the monitored impairments in cognitive tests. mRNA expression of genes involved in mitochondrial biogenesis (cAMP response element-binding protein 1 (creb-1), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α), nuclear respiratory factor-1 (Nrf-1), mitochondrial transcription factor A (Tfam), growth-associated protein 43 (GAP43), and synaptophysin 1 (SYP1)) and the antioxidative defense system (catalase (Cat) and superoxide dismutase 2 (SOD2)) was measured and showed significantly decreased expression patterns in the brain starting at an age of 18 months. BDNF expression reached, a maximum after 6 months. On the basis of longitudinal data, our results demonstrate a close connection between the age-related decline of cognitive performance, energy metabolism, and mitochondrial biogenesis during the physiological brain aging process.ing the physiological brain aging process.)
Brown G 2014 Abstract MiP2014 + (Brain inflammation may contribute to neuro … Brain inflammation may contribute to neuronal loss in infectious, ischemic, traumatic and neurodegenerative brain pathologies. We and others have shown that: a) brain inflammation induces the expression in microglia and astrocytes of inducible nitric oxide synthase (iNOS), which produces high levels of NO, b) NO derivatives peroxynitrite and S-nitrosothiols inactivate mitochondrial Complex I, resulting in a stimulation of oxidant production by mitochondria, c) oxidant production by microglia contributes to their inflammatory activation, and d) activated microglia can cause neuronal loss by eating them alive [1-4]. Thus, we were interested in whether activated microglia may inhibit their mitochondrial Complex I, resulting in sustained activation and phagocytosis of live neurons.There is evidence that in Parkinson’s disease and general brain aging mitochondrial Complex I is inhibited in affected parts of the brain. Rotenone is an environmental toxin and Complex I inhibitor that can cause activation of microglia and a Parkinson’s like pathology in rodents. We, therefore, tested whether it could cause microglia to phagocytose live neurons.We found that low nanomolar levels of rotenone could indeed activate microglial phagocytosis and cause neurons to phagocytose co-cultured neurons [5]. Removal of microglia or inhibition of phagocytic signalling prevented rotenone-induced neuronal loss, leaving viable neurons [5].Low levels of brain inflammation during ageing may cause partial inhibition of Complex I, resulting in oxidant production which sustains inflammation, and induces microglia to phagocytose synapses and cell bodies of live neurons. This process may be exacerbated in Parkinson’s disease and prevented by blocking inflammation or phagocytic signalling.ing inflammation or phagocytic signalling.)
Rekuviene 2018 Thesis + (Brain ischemia is a condition in which the … Brain ischemia is a condition in which there is insufficient blood flow resulting in deprivation of oxygen and energy supply that quickly affect energy-demanding neuronal cells and cause their death. Mitochondrial damage, particularly opening of mitochondrial permeability transition pore, is thought to be critical in ischemic brain damage. Recent data suggest that pharmacological compounds that affect the electron flow through complex I and reduce its activity may play an important role in regulation of mitochondrial permeability transition pore and can be crucial for cell viability and survival rate. However, little is known about the role of respiratory complex I in regulation of permeability transition and systemic effects of complex I inhibitors, their specificity and molecular mechanisms on brain mitochondrial functions and cell viability during ischemia. The aim of this study is to investigate the effect of respiratory chain complex I inhibitors on regulation of mitochondrial permeability transition pore, mitochondrial functions and cell viability in rat brain cortex and cerebellum during global ischemia. In this study it has been shown that respiratory complex I might be a potential therapeutic target in ischemic brain pathology by regulating mitochondrial permeability transition pore. These novel results can be used in new research of stroke treatment, management and recovery, reducing the risk of complications, extending expectancy and quality of life. extending expectancy and quality of life.)
Stepanova 2019 Antioxid Redox Signal + (Brain ischemia/reperfusion (I/R) is associ … Brain ischemia/reperfusion (I/R) is associated with impairment of mitochondrial function. However, the mechanisms of mitochondrial failure are not fully understood. This work was undertaken to determine the mechanisms and time course of mitochondrial energy dysfunction after reperfusion following neonatal brain hypoxia-ischemia (HI) in mice.HI/reperfusion decreased the activity of mitochondrial complex I, which was recovered after 30 min of reperfusion and then declined again after 1 h. Decreased complex I activity occurred in parallel with a loss in the content of non-covalently-bound membrane flavin mononucleotide (FMN). FMN dissociation from the enzyme is caused by succinate-supported reverse electron transfer. Administration of FMN precursor riboflavin prior to HI/reperfusion was associated with decreased infarct volume, attenuation of neurological deficit and preserved complex I activity compared to vehicle-treated mice. ''In vitro'', the rate of FMN release during oxidation of succinate was not affected by the oxygen level and amount of endogenously produced ROS.Our data suggest that dissociation of FMN from mitochondrial complex I may represent a novel mechanism of enzyme inhibition defining respiratory chain failure in I/R. Strategies preventing FMN release during HI and reperfusion may limit the extent of energy failure and cerebral HI injury. The proposed mechanism of acute I/R-induced complex I impairment is distinct from the generally accepted mechanism of oxidative stress-mediated I/R injury.Our study is the first to highlight a critical role of mitochondrial complex I-FMN dissociation in the development of HI-reperfusion injury of the neonatal brain.-reperfusion injury of the neonatal brain.)
Bahire 2023 Mitochondrion + (Brain ischemia/reperfusion injury results … Brain ischemia/reperfusion injury results in a variable mixture of cellular damage, but little is known about possible patterns of mitochondrial dysfunction from the scope of hemispheric processes. The current study used high-resolution fluorespirometry to compare ipsi- and contralateral hemispheres' linked respiration and ROS emission after 60-minutes of filament induced middle cerebral artery occlusion (fMCAo) and 2, 24, 72, and 168 h after reperfusion in mice. Our findings highlight that experimental ischemic stroke resulted in higher mitochondrial respiration in the contralateral compared to the ipsilateral hemisphere and highest ROS emission in ipsilateral hemisphere. The largest difference between the ipsilateral and contralateral hemispheres was observed 2 h after reperfusion in Complex I and II ETS state. Oxygen flux returns to near baseline 72 h after reperfusion without any changes thereafter in Complex I and II respiration. Studying the effects of brain mitochondrial functionality after ischemic stroke in each cerebral hemisphere separately provides a better understanding about the molecular and compensatory processes of the contralateral hemisphere, a region of the brain often neglected in stroke research. brain often neglected in stroke research.)
Takahashi 2016 Exp Gerontol + (Brain mitochondrial function declines with … Brain mitochondrial function declines with age; however, the accompanying behavioral and histological alterations that are characteristic of Parkinson's disease (PD) are poorly understood. We found that the mitochondrial oxygen consumption rate (OCR) and coenzyme Q (CoQ) content were reduced in aged (15-month-old) male mice compared to those in young (6-month-old) male mice. Concomitantly, motor functions, including the rate of movement and exploratory and voluntary motor activities, were significantly reduced in the aged mice compared to the young mice. In the motor cortex of the aged mouse brain, the accumulation of α-synuclein (α-syn) phosphorylated at serine129 (Ser129) significantly increased, and the level of vesicular glutamate transporter 1 (VGluT1) decreased compared with that in the young mouse brain. The administration of exogenous water-soluble CoQ10 to aged mice via drinking water restored the mitochondrial OCR, motor function, and phosphorylated α-syn and VGluT1 levels in the motor cortex. These results suggest that early-onset motor impairment and the increased accumulation of Ser129-phosphorylated α-syn in the motor cortex are ameliorated by the exogenous administration of CoQ10.Copyright © 2016 Elsevier Inc. All rights reserved.. Copyright © 2016 Elsevier Inc. All rights reserved.)
Guillot de Suduiraut 2020 Eur J Neurosci + (Brain mitochondrial function is critical f … Brain mitochondrial function is critical for numerous neuronal processes. We recently identified a link between brain energy and social dominance, where higher levels of mitochondrial function resulted in increased social competitive ability. The underlying mechanism of this link, however, remains unclear. Here we investigated the contribution of astrocytic release of adenosine triphosphate (ATP) through the type 2 inositol 1,4,5‐triphosphate receptor to social dominance behavior. Mice lacking the type 2 inositol 1,4,5‐triphosphate receptor were characterized for their social dominance behavior, as well as their performance on a nonsocial task, the Morris Water Maze. In parallel, we also examined mitochondrial function in the medial prefrontal cortex, nucleus accumbens, and hippocampus to investigate how deficiencies in astrocytic ATP could modulate overall mitochondrial function. While knockout mice showed similar competitive ability compared to their wildtype littermates, dominant knockout mice exhibited a significant delay in exerting their dominance during the initial encounter. Otherwise, there were no differences in anxiety and exploratory traits, spatial learning and memory, or brain mitochondrial function in either light or dark circadian phases. Our findings point to a marginal role of astrocytic ATP through IP3R2 in social competition, suggesting that, under basal conditions, the neuronal compartment is predominant for social dominance exertion.predominant for social dominance exertion.)
Malinska 2010 Biochim Biophys Acta + (Brain seizure activity is characterised by … Brain seizure activity is characterised by intense activation of mitochondrial oxidative phosphorylation. This stimulation of oxidative phosphorylation is in the low magnesium model of seizure-like events accompanied by substantial increase in formation of reactive oxygen species (ROS). However, it has remained unclearwhich ROSgenerating sites can be attributed to this phenomenon. Here, we report stimulatory effects of calcium ions and uncouplers, mimickingmitochondrial activation, on ROS generation of isolated rat andmouse brainmitochondria. Since these stimulatory effectswere visiblewith superoxide sensitive dyes, butwith hydrogen peroxide sensitive dyes only in the additional presence of SOD, we conclude that the complex redox properties of the ‘Qo’ center at respiratory chain complex III are very likely responsible for these observations. In accordancewith this hypothesis redox titrations of the superoxide production of antimycin-inhibited submitochondrial particles with thesuccinate/fumarate redox couple confirmed for brain tissue a bell-shapeddependencywith amaximal superoxide production rate at+10 mV(pH=7.4). This reflects the complex redox properties of a semiquinone specieswhichis the direct electron donor for oxygen reduction in complex III-dependent superoxide production. Therefore, we conclude that under conditions of increased energy load the complex III site can contribute to superoxideproduction of brain mitochondria, which might be relevant for epilepsy-related seizure activity.ant for epilepsy-related seizure activity.)
Yusoff 2015 J Cancer Res Ther + (Brain tumor is molecularly a heterogeneous … Brain tumor is molecularly a heterogeneous group of diseases, and genetic factors seem to play a crucial role in its genesis. Even though multiple alterations in the nuclear-encoded genes such as tumor suppressor and oncogenes are believed to play a key role in brain tumorigenesis, the involvement of the mitochondrial genome to this event remains controversial to date. Mitochondrial DNA (mtDNA) has been suspected to be associated with the carcinogenesis because of its high sensitivity to mutations and inefficient repair mechanisms in comparison to nuclear DNA. Thus, defects in mtDNA could also lead to the development of brain tumor. By virtue of their clonal nature and high copy number, mtDNA mutations may provide a new effective molecular biomarker for the cancer detection. It has been suggested that establishing mtDNA defective pattern might be useful in cancer diagnostics and detection, the prognosis of cancer outcome, and/or the response to certain treatments. This mini-review gives a brief overview on the several aspects of mtDNA, with a particular focus on its role in tumorigenesis and progression of brain tumor. Understanding the role of mitochondria and brain tumor development could potentially translate into therapeutic strategies for patients with these tumors.strategies for patients with these tumors.)
De Jong 2022 Nutrients + (Breaking up sedentary behavior with short- … Breaking up sedentary behavior with short-frequent bouts of physical activity (PA) differentially influences metabolic health compared with the performance of a single-continuous bout of PA matched for total active time. However, the underlying mechanisms are unknown. We compared skeletal muscle mitochondrial respiration (high-resolution respirometry) and molecular adaptations (RNA sequencing) following 4-day exposure to breaks vs. energy-matched single-continuous PA bout in inactive adults with overweight/obesity. Participants (9M/10F, 32.2 ± 6.4 years, 30.3 ± 3.0 kg/m2) completed three 4-day interventions of a randomized cross-over study: SED, sedentary control; MICRO, 5 min brisk walking each hour for 9 h; ONE: 45 min/d continuous brisk walking bout. Fasted muscle biopsies were collected on day 5. Mitochondrial coupling in the presence of lipid-associated substrates was higher after ONE (4.8 ± 2.5) compared to MICRO (3.1 ± 1.1, ''p'' = 0.02) and SED (2.3 ± 1.0, ''p'' = 0.001). Respiratory rates did not differ across groups with carbohydrate-associated substrates. In pathways associated with muscle contraction transcription signaling, ONE and MICRO similarly enhanced Oxidative Phosphorylation and Sirtuin Signaling expression (''p'' < 0.0001, for both). However, ONE (''p'' < 0.001, for all), but not MICRO, had greater pathway enrichment, including Ca++, mTOR, AMPK, and HIF1α signaling, than SED. Although breaking up sedentary behavior triggered skeletal muscle molecular adaptations favoring oxidative capacity, it did not improve mitochondrial function over the short term.capacity, it did not improve mitochondrial function over the short term.)
Cruz-Gregorio 2022 Antioxidants (Basel) + (Breast cancer (BC) is the second most comm … Breast cancer (BC) is the second most common cancer worldwide in women. During the last decades, the mortality due to breast cancer has progressively decreased due to early diagnosis and the emergence of more effective new treatments. However, human epidermal growth factor receptor 2 (HER2) and triple-negative breast cancer (TNBC) remain with poor prognoses. In our research group, we are proposing the GK-1 immunomodulatory peptide as a new alternative for immunotherapy of these aggressive tumors. GK-1 reduced the growth rate of established tumors and effectively reduced lung metastasis in the 4T1 experimental murine model of breast cancer. Herein, the effect of GK-1 on the redox state, mitochondrial metabolism, and autophagy of triple-negative tumors that can be linked to cancer evolution was studied. GK-1 decreased catalase activity, reduced glutathione (GSH) content and GSH/oxidized glutathione (GSSG) ratio while increased hydrogen peroxide (H2O2) production, GSSG, and protein carbonyl content, inducing oxidative stress (OS) in tumoral tissues. This imbalance between reactive oxygen species (ROS) and antioxidants was related to mitochondrial dysfunction and uncoupling, characterized by reduced mitochondrial respiratory parameters and dissipation of mitochondrial membrane potential (ΔΨm), respectively. Furthermore, GK-1 likely affected autophagy flux, confirmed by elevated levels of p62, a marker of autophagy flux. Overall, the induction of OS, dysfunction, and uncoupling of the mitochondria and the reduction of autophagy could be molecular mechanisms that underlie the reduction of the 4T1 breast cancer induced by GK-1.t underlie the reduction of the 4T1 breast cancer induced by GK-1.)
Victorino 2015 Tumour Biol + (Breast cancer is a prevalent neoplastic di … Breast cancer is a prevalent neoplastic disease among women worldwide which treatments still present several side effects and resistance. Considering that cancer cells present derangements in their energetic homeostasis, and that peroxisome proliferator-activated receptor- gamma coactivator 1 (PGC-1) is crucial for cellular metabolism and redox signaling, the main objective of this study was to investigate whether there is a relationship between PGC-1 expression, the proliferation of breast cancer cells and the mechanisms involved. We initially assessed PGC-1β expression in complementary DNA (cDNA) from breast tumor of patients bearing luminal A, luminal B, and HER2-overexpressed and triple negative tumors. Our data showed that PGC-1β expression is increased in patients bearing HER2-overexpressing tumors as compared to others subtypes. Using quantitative PCR and immunoblotting, we showed that breast cancer cells with HER2-amplification (SKBR-3) have greater expression of PGC-1β as compared to a non-tumorous breast cell (MCF-10A) and higher proliferation rate. PGC-1β expression was knocked down with short interfering RNA in HER2-overexpressing cells, and cells decreased proliferation. In these PGC-1β-inhibited cells, we found increased citrate synthase activity and no marked changes in mitochondrial respiration. Glycolytic pathway was decreased, characterized by lower intracellular lactate levels. In addition, after PGC-1β knockdown, SKBR-3 cells showed increased reactive oxygen species production, no changes in antioxidant activity, and decreased expression of ERRα, a modulator of metabolism. In conclusion, we show an association of HER2-overexpression and PGC-1β. PGC-1β knockdown impairs HER2-overexpressing cells proliferation acting on ERRα signaling, metabolism, and redox balance. signaling, metabolism, and redox balance.)
Wang 2023 Cancer Cell Int + (Breast cancer is the leading cause of canc … Breast cancer is the leading cause of cancer death for women worldwide. Most of the breast cancer death are due to disease recurrence and metastasis. Increasingly accumulating evidence indicates that mitochondria play key roles in cancer progression and metastasis. Our recent study revealed that transmembrane protein PRRG4 promotes the metastasis of breast cancer. However, it is not clear whether PRRG4 can affect the migration and invasion of breast cancer cells through regulating mitochondria function.RNA-seq analyses were performed on breast cancer cells expressing control and PRRG4 shRNAs. Quantitative PCR analysis and measurements of mitochondrial ATP content and oxygen consumption were carried out to explore the roles of PRRG4 in regulating mitochondrial function. Luciferase reporter plasmids containing different lengths of promoter fragments were constructed. Luciferase activities in breast cancer cells transiently transfected with these reporter plasmids were analyzed to examine the effects of PRRG4 overexpression on promoter activity. Transwell assays were performed to determine the effects of PRRG4-regulated pathway on migratory behaviors of breast cancer cells.Analysis of the RNA-seq data revealed that PRRG4 knockdown decreased the transcript levels of all the mitochondrial protein-encoding genes. Subsequently, studies with PRRG4 knockdown and overexpression showed that PRRG4 expression increased mitochondrial DNA (mtDNA) content. Mechanistically, PRRG4 via Src activated STAT3 in breast cancer cells. Activated STAT3 in turn promoted the transcription of mtDNA polymerase POLG through a STAT3 DNA binding site present in the POLG promoter region, and increased mtDNA content as well as mitochondrial ATP production and oxygen consumption. In addition, PRRG4-mediated activation of STAT3 also enhanced filopodia formation, migration, and invasion of breast cancer cells. Moreover, PRRG4 elevated migratory behaviors and mitochondrial function of breast cancer cells through POLG.Our results indicate that PRRG4 via the Src-STAT3-POLG axis enhances mitochondrial function and promotes migratory behaviors of breast cancer cells.igratory behaviors of breast cancer cells.)
Mann 2020 Sci Rep + (Breast cancer patients are commonly treate … Breast cancer patients are commonly treated with taxane (e.g. docetaxel) chemotherapy, despite poor outcomes and eventual disease relapse. We previously identified the Bcl-2-associated death promoter (BAD) as a prognostic indicator of good outcome in taxane-treated breast cancer patients. We also demonstrated that BAD expression in human breast carcinoma cells generated larger tumors in mouse xenograft models. These paradoxical results suggest that BAD-expressing tumors are differentially sensitive to taxane treatment. We validated this here and show that docetaxel therapy preferentially reduced growth of BAD-expressing xenograft tumors. We next explored the cellular mechanism whereby BAD sensitizes cells to docetaxel. Taxanes are microtubule inhibiting agents that cause cell cycle arrest in mitosis whereupon the cells either die in mitosis or aberrantly exit (mitotic slippage) and survive as polyploid cells. In response to docetaxel, BAD-expressing cells had lengthened mitotic arrest with a higher proportion of cells undergoing death in mitosis with decreased mitotic slippage. Death in mitosis was non-apoptotic and not dependent on Bcl-XL interaction or caspase activation. Instead, cell death was necroptotic, and dependent on ROS. These results suggest that BAD is prognostic for favourable outcome in response to taxane chemotherapy by enhancing necroptotic cell death and inhibiting the production of potentially chemoresistant polyploid cells.otentially chemoresistant polyploid cells.)
Krischek 2017 Animal + (Broiler eggs were either incubated at 37.8 … Broiler eggs were either incubated at 37.8°C during the whole incubation period (control), or at higher (38.8°C, group H) and lower temperatures (36.8°C, group L) from embryonic day (ED) 7 up to ED 10 (ED 7 to 10) or from ED 10 up to ED 13 (ED 10 to 13). Before and after this temperature treatment the eggs were incubated at 37.8°C. The day-old chicks were weighted, sexed and fed up to day 35. On days 1 and 35 samples were taken from the breast and leg muscles for analyzing of the mitochondrial respiratory activity (MRA) and from the breast muscles for analysis of the cross-sectional areas (CSA) and the glycogen phosphorylase (GP), phosphofructokinase (PFK), lactate dehydrogenase (LDH), citrate synthase (CS) and cytochrome oxidase (COX) activities. Statistical analysis showed that treatment (control, group H, group L), sex and their interaction, but not the treatment period (ED 7 to 10; ED 10 to 13), significantly influenced the results. Group H chicks had lower (P⩽0.05) body and heart weights but higher (P⩽0.05) liver weights, CSA values, leg MRA as well as PFK, LDH, CS, GP and COX activities compared with the group L chicks. The results of the control chicks differ (P⩽0.05) from those of the group H (body, heart weight, COX), the group L chicks (liver weight, PFK, LDH, CS, GP) or the birds of both other groups (CSA). The group H broiler had higher (P⩽0.05) body and leg weights as well as LDH, CS, COX and GP activities than the group L broilers. The BWs and the LDH and GP results of the control broiler differ (P⩽0.05) from those of both other groups or from the results of the group H (CS) and group L broiler (COX). Female broilers had lower (P⩽0.05) body, breast and leg weights, but higher (P⩽0.05) CSA, LDH, CS and GP activities than the male animals. Analysis of treatment×sex interaction showed that group H hens had higher (P⩽0.05) body and breast weights, LDH and GP activities compared with the group L hens, whereas in the male broiler no effect of the interaction could be found, except for the lower (P⩽0.05) CSA values in the group H than group L cocks. The treatment effects are probably due to altered embryonic activity and related molecular mechanisms. The sex-related differences in the broiler indicate that these alterations already occur in the embryos and chicks, but become significant with the sexual dimorphism after hatch.nt with the sexual dimorphism after hatch.)
Wang 2019 Artif Cells Nanomed Biotechnol + (Bronchial epithelial mitochondrial dysfunc … Bronchial epithelial mitochondrial dysfunction including impaired mitochondrial biogenesis has been linked with the initiation and development of bronchial asthma. Montelukast, a robust antagonist of cysteinyl leukotriene receptors, has been widely applied for the therapies of bronchial asthma. However, the effects of montelukast in airway epithelial mitochondrial dysfunction are less reported. In the present study, we report that montelukast treatment in human bronchial epithelial cells of Beas-2b increased the expressions of PGC-1α, NRF-1 and TFAM. As expected, montelukast promoted mitochondrial biogenesis in Beas-2b cells through increasing mitochondrial mass, mtDNA/nDNA and the expression of cytochrome B. Importantly, we found that montelukast caused a functional gain in mitochondria of Beas-2b cells. Mechanistically, we found that montelukast treatment increased intracellular cAMP levels and activation of CREB. Blockage of CREB with H89 abolished montelukast-induced expression of PGC-1α. These findings report a novel pharmacological function of montelukast in stimulating mitochondrial biogenesis in Beas-2b cells, mediating by the CREB/PGC-1α pathway.lls, mediating by the CREB/PGC-1α pathway.)
Beaufils 2021 J Allergy Clin Immunol + (Bronchial remodeling is a key feature of a … Bronchial remodeling is a key feature of asthma that is already present in preschoolers with wheezing. Moreover, bronchial smooth muscle (BSM) remodeling at preschool age is predictive of asthma at school age. However, the mechanism responsible for BSM remodeling in preschoolers with wheezing remains totally unknown. In contrast, in adult asthma, BSM remodeling has been associated with an increase in BSM cell proliferation related to increased mitochondrial mass and biogenesis triggered by an altered calcium homeostasis. Indeed, BSM cell proliferation was decreased ''in vitro'' by the calcium channel blocker gallopamil.Our aim was to investigate the mechanisms involved in BSM cell proliferation in preschoolers with severe wheezing, with special attention to the role of mitochondria and calcium signaling.Bronchial tissue samples obtained from 12 preschool controls without wheezing and 10 preschoolers with severe wheezing were used to measure BSM mass and establish primary BSM cell cultures. BSM cell proliferation was assessed by manual counting and flow cytometry, ATP content was assessed by bioluminescence, mitochondrial respiration was assessed by using either the Seahorse or Oroboros technique, mitochondrial mass and biogenesis were assessed by immunoblotting, and calcium response to carbachol was assessed by confocal microscopy. The effect of gallopamil was also evaluated.BSM mass, cell proliferation, ATP content, mitochondrial respiration, mass and biogenesis, and calcium response were all increased in preschoolers with severe wheezing compared with in the controls. Gallopamil significantly decreased BSM mitochondrial biogenesis and mass, as well as cell proliferation.Mitochondria are key players in BSM cell proliferation in preschoolers with severe wheezing and could represent a potential target to treat BSM remodeling at an early stage of the disease.modeling at an early stage of the disease.)
Chang 2023 Front Endocrinol (Lausanne) + (Brown adipocytes is a specialized fat cell … Brown adipocytes is a specialized fat cell that dissipates nutrient-derived chemical energy in the form of heat, instead of ATP synthesis. This unique feature provides a marked capacity for brown adipocyte mitochondria to oxidize substrates independent of ADP availability. Upon cold exposure, brown adipocytes preferentially oxidize free fatty acids (FFA) liberated from triacylglycerol (TAG) in lipid droplets to support thermogenesis. In addition, brown adipocytes take up large amounts of circulating glucose, concurrently increasing glycolysis and de novo FA synthesis from glucose. Given that FA oxidation and glucose-derived FA synthesis are two antagonistic mitochondrial processes in the same cell, it has long been questioned how brown adipocytes run FA oxidation and FA synthesis simultaneously. In this review, I summarize mechanisms regulating mitochondrial substrate selection and describe recent findings of two distinct populations of brown adipocyte mitochondria with different substrate preferences. I further discuss how these mechanisms may permit a concurrent increase in glycolysis, FA synthesis, and FA oxidation in brown adipocytes.sis, and FA oxidation in brown adipocytes.)
Schilperoort 2018 EMBO Mol Med + (Brown adipose tissue (BAT) activation stim … Brown adipose tissue (BAT) activation stimulates energy expenditure in human adults, which makes it an attractive target to combat obesity and related disorders. Recent studies demonstrated a role for G protein-coupled receptor 120 (GPR120) in BAT thermogenesis. Here, we investigated the therapeutic potential of GPR120 agonism and addressed GPR120-mediated signaling in BAT. We found that activation of GPR120 by the selective agonist TUG-891 acutely increases fat oxidation and reduces body weight and fat mass in C57Bl/6J mice. These effects coincided with decreased brown adipocyte lipid content and increased nutrient uptake by BAT, confirming increased BAT activity. Consistent with these observations, GPR120 deficiency reduced expression of genes involved in nutrient handling in BAT Stimulation of brown adipocytes ''in vitro'' with TUG-891 acutely induced O2 consumption, through GPR120-dependent and GPR120-independent mechanisms. TUG-891 not only stimulated GPR120 signaling resulting in intracellular calcium release, mitochondrial depolarization, and mitochondrial fission, but also activated UCP1. Collectively, these data suggest that activation of brown adipocytes with the GPR120 agonist TUG-891 is a promising strategy to increase lipid combustion and reduce obesity.ategy to increase lipid combustion and reduce obesity.)
Chondronikola 2014 + (Brown adipose tissue (BAT) has attracted s … Brown adipose tissue (BAT) has attracted scientific interest as an antidiabetic tissue owing to its ability to dissipate energy as heat. Despite a plethora of data concerning the role of BAT in glucose metabolism in rodents, the role of BAT (if any) in glucose metabolism in humans remains unclear. To investigate whether BAT activation alters whole-body glucose homeostasis and insulin sensitivity in humans, we studied seven BAT-positive (BAT(+)) men and five BAT-negative (BAT(-)) men under thermoneutral conditions and after prolonged (5-8 h) cold exposure (CE). The two groups were similar in age, BMI, and adiposity. CE significantly increased resting energy expenditure, whole-body glucose disposal, plasma glucose oxidation, and insulin sensitivity in the BAT(+) group only. These results demonstrate a physiologically significant role of BAT in whole-body energy expenditure, glucose homeostasis, and insulin sensitivity in humans, and support the notion that BAT may function as an antidiabetic tissue in humans.ction as an antidiabetic tissue in humans.)
Chondronikola 2015 Int J Obes (Lond) + (Brown adipose tissue (BAT) has been propos … Brown adipose tissue (BAT) has been proposed as a potential target tissue against obesity and its related metabolic complications. Although the molecular and functional characteristics of BAT have been intensively studied in rodents, only a few studies have used human BAT specimens due to the difficulty of sampling human BAT deposits. We established a novel positron emission tomography and computed tomography-guided Bergström needle biopsy technique to acquire human BAT specimens from the supraclavicular area in human subjects. Forty-three biopsies were performed on 23 participants. The procedure was tolerated well by the majority of participants. No major complications were noted. Numbness (9.6%) and hematoma (2.3%) were the two minor complications noted, which fully resolved. Thus, the proposed biopsy technique can be considered safe with only minimal risk of adverse events. Adoption of the proposed method is expected to increase the sampling of the supraclavicular BAT depot for research purposes so as to augment the scientific knowledge of the biology of human BAT.fic knowledge of the biology of human BAT.)
Yin 2013 Cell Metab + (Brown adipose tissue (BAT) is an energy-di … Brown adipose tissue (BAT) is an energy-dispensing thermogenic tissue that plays an important role in balancing energy metabolism. Lineage-tracing experiments indicate that brown adipocytes are derived from myogenic progenitors during embryonic development. However, adult skeletal muscle stem cells (satellite cells) have long been considered uniformly determined toward the myogenic lineage. Here, we report that adult satellite cells give rise to brown adipocytes and that microRNA-133 regulates the choice between myogenic and brown adipose determination by targeting the 3'UTR of Prdm16. Antagonism of microRNA-133 during muscle regeneration increases uncoupled respiration, glucose uptake, and thermogenesis in local treated muscle and augments whole-body energy expenditure, improves glucose tolerance, and impedes the development of diet-induced obesity. Finally, we demonstrate that miR-133 levels are downregulated in mice exposed to cold, resulting in de novo generation of satellite cell-derived brown adipocytes. Therefore, microRNA-133 represents an important therapeutic target for the treatment of obesity.eutic target for the treatment of obesity.)
Arruda 2008 Endocrinology + (Brown adipose tissue (BAT) is involved in … Brown adipose tissue (BAT) is involved in rat and mice thermoregulation, and heat produced by BAT depends on the concerted action of thyroid hormones and catecholamines. Little is known about cold-induced thermogenesis in mammals that have little or no BAT, such as rabbits. In these animals, thermogenesis primarily occurs in skeletal muscle. In this work, we have studied the effect of cold acclimation (4 C for 10 d) in normal and hypothyroid rabbits. It is known that hypothyroid rats die after a few hours of cold exposure. We now show that, different from rats, hypothyroid rabbits sustain their body temperature and survive after 10 d cold exposure. When compared with rabbits kept at room temperature, the muscles of cold-exposed rabbits showed a dark red color characteristic of oxidative muscle fibers. According to this pattern, we observed that in both normal and hypothyroid rabbits, cold exposure promotes an increase in oxygen consumption by skeletal muscle mitochondria. Moreover, in red muscle, cold acclimation induces an increase in the expression and activity of sarcoplasmic reticulum Ca2+ ATPase isoform 1 (SERCA1), one of the muscle enzymes involved in heat production. We conclude that rabbit cold tolerance is probably related to increased muscle oxidative metabolism and heat production by SERCA1 and that these changes are not completely dependent on normal thyroid function.e not completely dependent on normal thyroid function.)
Capek 2018 J Burn Res + (Brown adipose tissue (BAT) is responsible … Brown adipose tissue (BAT) is responsible for non-shivering thermogenesis in mammals owing to the expression of uncoupling protein-1 (UCP-1), which uncouples mitochondrial respiration from ATP production. It has recently been observed that adult humans have functional BAT. While it has been theorized that uncoupled mitochondrial respiration contributes to the hypermetabolic response to burns, whether patients with severe burns have functional BAT remains unknown.We collected sub-platysmal adipose tissue (sPAT) (n=5 samples) from patients undergoing reconstructive surgeries and peri-renal adipose tissue (pRAT) (n=2 samples) from patients at autopsy. Sub-cutaneous white adipose tissue (scWAT) samples were also collected. High-resolution respirometry was performed on permeabilized tissue samples to determine respiration. Titration of the UCP-1 inhibitor guanosine diphosphate (GDP) was used to determine the presence or absence of BAT in sPAT and scWAT. Histology was also performed on pRAT and scWAT samples.The average of patients providing sPAT was 9 ± 1 years. sPAT adipose tissue had a respiratory capacity 26-fold higher than scWAT (68.5 ± 39.7 vs. 2.6 ± 1.5 pmol/s/mg, p<0.001). GDP titration reduced respiration in sPAT (-38.9 ± 17.7 pmol/s/mg) but not scWAT mitochondria (-0.08 ± 0.07 pmol/s/mg), providing direct evidence of functional BAT within sPAT. Histological analysis showed that pRAT had distinct areas with an abundance of small multi-locular cells (adipocytes containing numerous small lipid droplets), whereas scWAT exhibited larger mainly uni-locular cells (adipocytes containing one large lipid droplet).We provide novel functional and histological evidence of BAT in patients with severe burns. The functional signature of UCP-1 in sPAT of burned patients indicates that this BAT is thermogenic, and therefore may contribute to the hypermetabolic response to burn injury.We have identified BAT in burned patients as a component of the metabolic response to burn injury. The regulatory and homeostatic qualities of this tissue render it a potential target to modulate the hypermetabolic response to burn injury.e the hypermetabolic response to burn injury.)
McFarlane 2016 Thesis + (Brown adipose tissue (BAT) is the major th … Brown adipose tissue (BAT) is the major thermogenic tissue in smalleutherian mammals. In hibernators, seasonal modifications of BAT are welldocumented but little is known about its functional regulation during hibernation. BAT metabolism is activated by sympathetic stimulation, so I hypothesized that further regulation at the mitochondrial level, as seen in other hibernator tissues, would be of little advantage. Contrary to my predictions, respiration rates of BAT mitochondria isolated from torpid thirteen-lined ground squirrels were suppressed by up to 62% compared with rates from individuals that aroused to interbout euthermia (IBE), when measured at 37°C. At 10°C, however, these rates did not differ between torpor and IBE. Contrary to these results, activities of electron transport system enzymes and brown adipocyte respiration did not differ between torpor and IBE, regardless of assay temperature. The data suggest that BAT mitochondria become less temperature sensitive during torpor, allowing sustained function at low body temperatures.stained function at low body temperatures.)
De Meis 2010 PLoS One + (Brown adipose tissue (BAT) mitochondria th … Brown adipose tissue (BAT) mitochondria thermogenesis is regulated by uncoupling protein 1 (UCP 1), GDP and fatty acids. In this report, we observed fusion of the endoplasmic reticulum (ER) membrane with the mitochondrial outer membrane of rats BAT. Ca2+-ATPase (SERCA 1) was identified by immunoelectron microscopy in both ER and mitochondria. This finding led us to test the Ca2+ effect in BAT mitochondria thermogenesis. We found that Ca2+ increased the rate of respiration and heat production measured with a microcalorimeter both in coupled and uncoupled mitochondria, but had no effect on the rate of ATP synthesis. The Ca2+ concentration needed for half-maximal activation varied between 0.08 and 0.11 µM. The activation of respiration was less pronounced than that of heat production. Heat production and ATP synthesis were inhibited by rotenone and KCN. Liver mitochondria have no UCP1 and during respiration synthesize a large amount of ATP, produce little heat, GDP had no effect on mitochondria coupling, Ca2+ strongly inhibited ATP synthesis and had little or no effect on the small amount of heat released. These findings indicate that Ca2+ activation of thermogenesis may be a specific feature of BAT mitochondria not found in other mitochondria such as liver.tion of thermogenesis may be a specific feature of BAT mitochondria not found in other mitochondria such as liver.)
Porter 2017 Adipocyte + (Brown adipose tissue (BAT) mitochondria ar … Brown adipose tissue (BAT) mitochondria are distinct from their counterparts in other tissues in that ATP production is not their primary physiologic role. BAT mitochondria are equipped with a specialized protein known as uncoupling protein 1 (UCP1). UCP1 short-circuits the electron transport chain, allowing mitochondrial membrane potential to be transduced to heat, making BAT a tissue capable of altering energy expenditure and fuel metabolism in mammals without increasing physical activity. The recent discovery that adult humans have metabolically active BAT has rekindled an interest in this intriguing tissue, with the overarching aim of manipulating BAT function to augment energy expenditure as a countermeasure for obesity and the metabolic abnormalities it incurs. Subsequently, there has been heightened interest in quantifying BAT function and more specifically, determining UCP1-mediated thermogenesis in BAT specimens - including in those obtained from humans. In this article, BAT mitochondrial bioenergetics will be described and compared with more conventional mitochondria in other tissues. The biochemical methods typically used to quantify BAT mitochondrial function will also be discussed in terms of their specificity for assaying UCP1 mediated thermogenesis. Finally, recent data concerning BAT UCP1 function in humans will be described and discussed.in humans will be described and discussed.)
Tang 2022 Sci China Life Sci + (Brown adipose tissue (BAT) plays an essent … Brown adipose tissue (BAT) plays an essential role in non-shivering thermogenesis. The phosphatidylinositol transfer protein, cytoplasmic 1 (PITPNC1) is identified as a lipid transporter that reciprocally transfers phospholipids between intracellular membrane structures. However, the physiological significance of PITPNC1 and its regulatory mechanism remain unclear. Here, we demonstrate that PITPNC1 is a key player in thermogenesis of BAT. While Pitpnc1-/- mice do not differ with wildtype mice in body weight and insulin sensitivity on either chow or high-fat diet, they develop hypothermia when subjected to acute cold exposure at 4°C. The Pitpnc1-/- brown adipocytes exhibit defective β-oxidation and abnormal thermogenesis-related metabolism pathways in mitochondria. The deficiency of lipid mobilization in Pitpnc1-/- brown adipocytes might be the result of excessive accumulation of phosphatidylcholine and a reduction of phosphatidic acid. Our findings have uncovered significant roles of PITPNC1 in mitochondrial phospholipid homeostasis and BAT thermogenesis.es of PITPNC1 in mitochondrial phospholipid homeostasis and BAT thermogenesis.)
Porter 2016 Cell Metab + (Brown adipose tissue (BAT) plays an import … Brown adipose tissue (BAT) plays an important role in mammalian thermoregulation. The component of BAT mitochondria that permits this function is the inner membrane carrier protein uncoupling protein 1 (UCP1). To the best of our knowledge, no studies have directly quantified UCP1 function in human BAT. Further, whether human and rodent BAT have comparable thermogenic function remains unknown. We employed high-resolution respirometry to determine the respiratory capacity, coupling control, and, most importantly, UCP1 function of human supraclavicular BAT and rodent interscapular BAT. Human BAT was sensitive to the purine nucleotide GDP, providing the first direct evidence that human BAT mitochondria have thermogenically functional UCP1. Further, our data demonstrate that human and rodent BAT have similar UCP1 function per mitochondrion. These data indicate that human and rodent BAT are qualitatively similar in terms of UCP1 function.Copyright © 2016 Elsevier Inc. All rights reserved. © 2016 Elsevier Inc. All rights reserved.)
Pravenec 2017 Physiol Res + (Brown adipose tissue (BAT) plays an import … Brown adipose tissue (BAT) plays an important role in lipid and glucose metabolism in rodents and possibly also in humans. Identification of genes responsible for BAT function would shed light on underlying pathophysiological mechanisms of metabolic disturbances. Recent linkage analysis in the BXH/HXB recombinant inbred (RI) strains, derived from Brown Norway (BN) and spontaneously hypertensive rats (SHR), identified two closely linked quantitative trait loci (QTL) associated with glucose oxidation and glucose incorporation into BAT lipids in the vicinity of Wars2 (tryptophanyl tRNA synthetase 2 (mitochondrial)) gene on chromosome 2. The SHR harbors L53F WARS2 protein variant that was associated with reduced angiogenesis and Wars2 thus represents a prominent positional candidate gene. In the current study, we validated this candidate as a quantitative trait gene (QTG) using transgenic rescue experiment. SHR-Wars2 transgenic rats with wild type Wars2 gene when compared to SHR, showed more efficient mitochondrial proteosynthesis and increased mitochondrial respiration, which was associated with increased glucose oxidation and incorporation into BAT lipids, and with reduced weight of visceral fat. Correlation analyses in RI strains showed that increased activity of BAT was associated with amelioration of insulin resistance in muscle and white adipose tissue. In summary, these results demonstrate important role of Wars2 gene in regulating BAT function and consequently lipid and glucose metabolism.consequently lipid and glucose metabolism.)
Chang 2017 J Biol Chem + (Brown adipose tissue dissipates energy as … Brown adipose tissue dissipates energy as heat, a process that relies on a high abundance of mitochondria and high levels of electron transport chain (ETC) complexes within these mitochondria. Two regulators of mitochondrial respiration and heat production in brown adipocytes are the transcriptional coactivator PGC-1α and its splicing isoform NT-PGC-1α, which control mitochondrial gene expression in the nucleus. Surprisingly, we found that, in brown adipocytes, some NT-PGC-1α localizes to mitochondria, whereas PGC-1α resides in the nucleus. Here we sought to investigate the role of NT-PGC-1α in brown adipocyte mitochondria. Immunocytochemistry, immunotransmission electron microscopy, and biochemical analyses indicated that NT-PGC-1α was located in the mitochondrial matrix in brown adipocytes. NT-PGC-1α was specifically enriched at the D-loop region of the mtDNA, which contains the promoters for several essential ETC complex genes, and was associated with LRP130, an activator of mitochondrial transcription. Selective expression of NT-PGC-1α and PGC-1α in PGC-1α-/- brown adipocytes similarly induced expression of nuclear DNA-encoded mitochondrial ETC genes, including the key mitochondrial transcription factor A (TFAM). Despite having comparable levels of TFAM expression, PGC-1α-/- brown adipocytes expressing NT-PGC-1α had higher expression of mtDNA-encoded ETC genes than PGC-1α-/- brown adipocytes expressing PGC-1α, suggesting a direct effect of NT-PGC-1α on mtDNA transcription. Moreover, this increase in mtDNA-encoded ETC gene expression was associated with enhanced respiration in NT-PGC-1α-expressing PGC-1α-/- brown adipocytes. Our findings reveal a previously unappreciated and isoform-specific role for NT-PGC-1α in the regulation of mitochondrial transcription in brown adipocytes and provide new insight into the transcriptional control of mitochondrial respiration.© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.r Biochemistry and Molecular Biology, Inc.)
Emmett 2017 Nature + (Brown adipose tissue is a thermogenic orga … Brown adipose tissue is a thermogenic organ that dissipates chemical energy as heat to protect animals against hypothermia and to counteract metabolic disease. However, the transcriptional mechanisms that determine the thermogenic capacity of brown adipose tissue before environmental cold are unknown. Here we show that histone deacetylase 3 (HDAC3) is required to activate brown adipose tissue enhancers to ensure thermogenic aptitude. Mice with brown adipose tissue-specific genetic ablation of HDAC3 become severely hypothermic and succumb to acute cold exposure. Uncoupling protein 1 (UCP1) is nearly absent in brown adipose tissue lacking HDAC3, and there is also marked downregulation of mitochondrial oxidative phosphorylation genes resulting in diminished mitochondrial respiration. Remarkably, although HDAC3 acts canonically as a transcriptional corepressor, it functions as a coactivator of oestrogen-related receptor α (ERRα) in brown adipose tissue. HDAC3 coactivation of ERRα is mediated by deacetylation of PGC-1α and is required for the transcription of Ucp1, Ppargc1a (encoding PGC-1α), and oxidative phosphorylation genes. Importantly, HDAC3 promotes the basal transcription of these genes independently of adrenergic stimulation. Thus, HDAC3 uniquely primes Ucp1 and the thermogenic transcriptional program to maintain a critical capacity for thermogenesis in brown adipose tissue that can be rapidly engaged upon exposure to dangerously cold temperature. exposure to dangerously cold temperature.)
Crisan 2008 Stem Cells + (Brown adipose tissue uncoupling protein-1 … Brown adipose tissue uncoupling protein-1 (UCP1) plays a major role in the control of energy balance in rodents. It has long been thought, however, that there is no physiologically relevant UCP1 expression in adult humans. In this study we show, using an original approach consisting of sorting cells from various tissues and differentiating them in an adipogenic medium, that a stationary population of skeletal muscle cells expressing the CD34 surface protein can differentiate ''in vitro'' into genuine brown adipocytes with a high level of UCP1 expression and uncoupled respiration. These cells can be expanded in culture, and their UCP1 mRNA expression is strongly increased by cell-permeating cAMP derivatives and a peroxisome-proliferator-activated receptor-gamma (PPARgamma) agonist. Furthermore, UCP1 mRNA was detected in the skeletal muscle of adult humans, and its expression was increased ''in vivo'' by PPARgamma agonist treatment. All the studies concerning UCP1 expression in adult humans have until now been focused on the white adipose tissue. Here we show for the first time the existence in human skeletal muscle and the prospective isolation of progenitor cells with a high potential for UCP1 expression. The discovery of this reservoir generates a new hope of treating obesity by acting on energy dissipation.g obesity by acting on energy dissipation.)
Whitehead 2021 Nat Commun + (Brown and beige adipose tissue are emergin … Brown and beige adipose tissue are emerging as distinct endocrine organs. These tissues are functionally associated with skeletal muscle, adipose tissue metabolism and systemic energy expenditure, suggesting an interorgan signaling network. Using metabolomics, we identify 3-methyl-2-oxovaleric acid, 5-oxoproline, and β-hydroxyisobutyric acid as small molecule metabokines synthesized in browning adipocytes and secreted via monocarboxylate transporters. 3-methyl-2-oxovaleric acid, 5-oxoproline and β-hydroxyisobutyric acid induce a brown adipocyte-specific phenotype in white adipocytes and mitochondrial oxidative energy metabolism in skeletal myocytes both ''in vitro'' and ''in vivo''. 3-methyl-2-oxovaleric acid and 5-oxoproline signal through cAMP-PKA-p38 MAPK and β-hydroxyisobutyric acid via mTOR. In humans, plasma and adipose tissue 3-methyl-2-oxovaleric acid, 5-oxoproline and β-hydroxyisobutyric acid concentrations correlate with markers of adipose browning and inversely associate with body mass index. These metabolites reduce adiposity, increase energy expenditure and improve glucose and insulin homeostasis in mouse models of obesity and diabetes. Our findings identify beige adipose-brown adipose-muscle physiological metabokine crosstalk.muscle physiological metabokine crosstalk.)
Cannon 2008 Methods Mol Biol + (Brown and white adipose tissues in mammals … Brown and white adipose tissues in mammals have a number of similar properties, such as lipid storage and adipokine production, but also distinctive properties. The energy-storing white adipose tissue has few mitochondria and low oxidative capacity. The heat-producing brown adipose tissue has a high density of mitochondria and high oxidative capacity. Mitochondrial function can be investigated in cells and organelles isolated from both brown and white adipose tissues. This chapter describes methods for successful isolation of suitable preparations of adipose tissues and their subsequent use. Questions concerning thermogenic capacity of the tissues, their potential influence on whole body metabolism, and specific properties of the mitochondria and their mode of function may be addressed using these methods.tion may be addressed using these methods.)
Wu 2012 Cell + (Brown fat generates heat via the mitochond … Brown fat generates heat via the mitochondrial uncoupling protein UCP1, defending against hypothermia and obesity. Recent data suggest that there are two distinct types of brown fat: classical brown fat derived from a myf-5 cellular lineage and UCP1-positive cells that emerge in white fat from a non-myf-5 lineage. Here, we report the isolation of "beige" cells from murine white fat depots. Beige cells resemble white fat cells in having extremely low basal expression of UCP1, but, like classical brown fat, they respond to cyclic AMP stimulation with high UCP1 expression and respiration rates. Beige cells have a gene expression pattern distinct from either white or brown fat and are preferentially sensitive to the polypeptide hormone irisin. Finally, we provide evidence that previously identified brown fat deposits in adult humans are composed of beige adipocytes. These data provide a foundation for studying this mammalian cell type with therapeutic potential.lian cell type with therapeutic potential.)
Mayeuf-Louchart 2019 Cell Rep + (Browning induction or transplantation of b … Browning induction or transplantation of brown adipose tissue (BAT) or brown/beige adipocytes derived from progenitor or induced pluripotent stem cells (iPSCs) can represent a powerful strategy to treat metabolic diseases. However, our poor understanding of the mechanisms that govern the differentiation and activation of brown adipocytes limits the development of such therapy. Various genetic factors controlling the differentiation of brown adipocytes have been identified, although most studies have been performed using ''in vitro'' cultured pre-adipocytes. We investigate here the differentiation of brown adipocytes from adipose progenitors in the mouse embryo. We demonstrate that the formation of multiple lipid droplets (LDs) is initiated within clusters of glycogen, which is degraded through glycophagy to provide the metabolic substrates essential for ''de novo'' lipogenesis and LD formation. Therefore, this study uncovers the role of glycogen in the generation of LDs.Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.ed by Elsevier Inc. All rights reserved.)
Shi 2024 Clin Sci (Lond) + (Browning of white adipose tissue is hallma … Browning of white adipose tissue is hallmarked by increased mitochondrial density and metabolic improvements. However, it remains largely unknown how mitochondrial turnover and quality control are regulated during adipose browning. In the present study, we found that mice lacking adipocyte FoxO1, a transcription factor that regulates autophagy, adopted an alternate mechanism of mitophagy to maintain mitochondrial turnover and quality control during adipose browning. Post-developmental deletion of adipocyte FoxO1 (adO1KO) suppressed Bnip3 but activated Fundc1/Drp1/OPA1 cascade, concurrent with up-regulation of Atg7 and CTSL. In addition, mitochondrial biogenesis was stimulated via the Pgc1α/Tfam pathway in adO1KO mice. These changes were associated with enhanced mitochondrial homeostasis and metabolic health (e.g., improved glucose tolerance and insulin sensitivity). By contrast, silencing Fundc1 or Pgc1α reversed the changes induced by silencing FoxO1, which impaired mitochondrial quality control and function. Ablation of Atg7 suppressed mitochondrial turnover and function, causing metabolic disorder (e.g., impaired glucose tolerance and insulin sensitivity), regardless of elevated markers of adipose browning. Consistently, suppression of autophagy via CTSL by high-fat diet was associated with a reversal of adO1KO-induced benefits. Our data reveal a unique role of FoxO1 in coordinating mitophagy receptors (Bnip3 and Fundc1) for a fine-tuned mitochondrial turnover and quality control, underscoring autophagic clearance of mitochondria as a prerequisite for healthy browning of adipose tissue.te for healthy browning of adipose tissue.)
Rodrigues 2014 Abstract MiP2014 + (Buccal cancer affects 3% of all cases of c … Buccal cancer affects 3% of all cases of cancer in the world. The most common malignant tumors of the oral cavity are of the spinocellular type and are characterized by invasive growth, frequently perineural. Although the main etiological factors, tobacco and alcohol, are known, at this point the biochemical features associated with the progression of the disease are largely fragmentary.We investigated the bioenergetics of oral tongue squamous cell carcinoma (OTSCC) metastatic spread. An orthotopic model was developed by the implantation of SCC-9 ZsGreen cells into the tongue of BALB/c nude mice. The animals were sacrificed 60 days later and the axillary lymph nodes collected. Fragments of positive lymph nodes were used for explants cultures, from which the LN-1 ZsGreen cell line was isolated. The retransplantation generated LN-2 ZsGreen cell lines. LN1 and LN2 present degrees of aggressiveness as measured by their metastatic behavior [1]. When compared for ATP content, SCC9, LN1 and LN2 cells displayed similar profiles. All three were strongly sensitive to glycolytic inhibitors as 2-DOG and iodocetamide, but were quasi-insensitive to respiratory the inhibitors rotenone and antimycin A. These results indicate that SCC9, LN1 and LN2 primarily depend on glycolysis for ATP synthesis, although their mitochondria were not dysfunctional. Our results with high-resolution respirometry (HRR) show that mitochondrial function is similar in all three cell lines. Interestingly, oxygen consumption of digitonin permeabilized cells displayed a decreased activity of Complex I- but not of Complex II-linked respiration. Furthermore, mitochondrial content was decreased. Interestingly, the content of Complex III increased linearly with the metastatic behavior of the cells. Since many types of cancer involve defects in respiratory complexes, it is possible that the observed reduced activity of Complex I is compensated by an enhanced activity of Complex III. Alternatively, in the more aggressive cells electrons bypassing Complex I may increase the speed of the entire electron transfer-pathway, therefore facilitating ROS production, migration and invasion. To investigate whether tongue cancer cells used specific energy substrates in a differential manner, palmitoyl CoA was added to the incubation medium. Stimulation of OXPHOS capacity by SCC9 and LN1 cells, and, less so, by the more aggressive LN2 cells was observed only with palmitoyl CoA+malate. Additionally, inhibition of beta-oxidation using etomoxir induced a decrease in ATP levels in LN1 and LN2 cells. These results suggest that mitochondria of tongue metastatic cells can select specific energy substrates such as amino acids and/or fatty acids to maintain redox balance and ATP balance during invasion.x balance and ATP balance during invasion.)
UNESCO 2021 Open Science + (Building on the essential principles of ac … Building on the essential principles of academic freedom, research integrity and scientific excellence, [[Open Science]] sets a new paradigm that integrates into the scientific enterprise practices for reproducibility, transparency, sharing and collaboration resulting from the increased opening of scientific contents, tools and processes. Open science is defined as an inclusive construct that combines various movements and practices aiming to make multilingual scientific knowledge openly available, accessible and reusable for everyone, to increase scientific collaborations and sharing of information for the benefits of science and society, and to open the processes of scientific knowledge creation, evaluation and communication to societal actors beyond the traditional scientific community. It comprises all scientific disciplines and aspects of scholarly practices, including basic and applied sciences, natural and social sciences and the humanities, and it builds on the following key pillars: open scientific knowledge, open science infrastructures, science communication, open engagement of societal actors and open dialogue with other knowledge systems.pen dialogue with other knowledge systems.)
Masson 2017 Sci Rep + (Bumblebees (''Bombus terrestris'') fly at … Bumblebees (''Bombus terrestris'') fly at low ambient temperatures where other insects cannot, and to do so they must pre-warm their flight muscles. While some have proposed mechanisms, none fully explain how pre-flight thermogenesis occurs. Here, we present a novel hypothesis based on the less studied mitochondrial glycerol 3-phosphate dehydrogenase pathway (mGPDH). Using calorimetry, and high resolution respirometry coupled with fluorimetry, we report substrate oxidation by mGPDH in permeabilised flight muscles operates, ''in vitro'', at a high flux, even in the absence of ADP. This may be facilitated by an endogenous, mGPDH-mediated uncoupling of mitochondria. This uncoupling increases ETS activity, which results in increased heat release. Furthermore, passive regulation of this mechanism is achieved via dampened temperature sensitivity of mGPDH relative to other respiratory pathways, and subsequent consumption of its substrate, glycerol 3-phosphate (G3P), at low temperatures. Mitochondrial GPDH may therefore facilitate pre-flight thermogenesis through poor mitochondrial coupling. We calculate this can occur at a sufficient rate to warm flight muscles until shivering commences, and until flight muscle function is adequate for bumblebees to fly in the cold.dequate for bumblebees to fly in the cold.)
Hickey 2016 Abstract MitoFit Science Camp 2016 + (Bumblebees (''Bombus terrestris'') have be … Bumblebees (''Bombus terrestris'') have been seen as enigmatic species, firstly due to their large size and the miscalculation that they theoretically cannot fly, and secondly because on cold days they can fly while other insect species cannot. It was initially proposed that bumblebees may heat flight muscles through futile cycles within glycolysis, however this has in part been dispelled because heat formed by this mechanism accounts for approximately 12% of that required to warm the thorax [1]. This made us question whether there are other heat sources, as heat derived within muscle may come from different sources. Ion (calcium) cycling has been invoked for modified non contractile rectus muscles of billfish heater organs, this likely cannot apply for insect flight muscles. Actin myosin cross-bridging events generate heat in shivering, through the gross inefficiency of molecular movements. While bumblebees do appear to shiver, this may only occur once permissible temperatures are reached (15-20oC). Lastly high levels of mitochondrial release heat occur with respiration, and this is accelerated through the induction of inefficiency through uncoupling. Mitochondrial heat generation in bumblebees has been largely discounted as they appear to lack uncoupling proteins, and if muscles are not contracting through shivering there is little ADP to drive high levels of respiration in the absence of uncoupling proteins. However, we contend that glycerol 3 phosphate of the glycerol 3 phosphate (G3P) shuttle lacks efficiency through poor coupling both of the electron transport system to oxidative phosphorylation and in terms of NADH oxidation. This system can then generate sufficient heat to warm the thorax in the absence ADP.eat to warm the thorax in the absence ADP.)
Kladnicka 2019 Physiol Res + (Burden of obesity is increasing in the con … Burden of obesity is increasing in the contemporary world. Although multifactorial in origin, appropriate mitochondrial function of adipocytes emerges as a factor essential for healthy adipocyte differentiation and adipose tissue function. Our study aimed to evaluate mitochondrial functions of human adipose-derived mesenchymal stem cells committed to adipogenesis. On days 0, 4, 10, and 21 of adipogenesis, we have characterized adipocyte proliferation and viability, quantified lipid accumulation in maturing cells, performed qualitative and quantitative analysis of mitochondria, determined mitochondrial respiration of cells using high-resolution respirometry, and evaluated mitochondrial membrane potential. In the course of adipogenesis, mitochondrial oxygen consumption progressively increased in states ROUTINE and E (capacity of the electron transfer system). State LEAK remained constant during first days of adipogenesis and then increased probably reflecting uncoupling ability of maturing adipocytes. Citrate synthase activity and volume of mitochondrial networks increased during differentiation, particularly between days 10 and 21. In addition, lipid accumulation remained low until day 10 and then significantly increased. In conclusion, during first days of adipogenesis, increased mitochondrial respiration is needed for transition of differentiating cells from glycolytic to oxidative metabolism and clonal expansion of preadipocytes and then more energy is needed to acquire typical metabolic phenotype of mature adipocyte.l metabolic phenotype of mature adipocyte.)
Wetzel 2017 Thesis + (Burn injury is a significant problem that … Burn injury is a significant problem that affects approximately half a million people in the U.S. annually. One of the major complications emerging from burn injury is hyperglycemia, which can last for weeks following the initial trauma. The primary cause of hyperglycemia is dysregulated AMPK signaling and mitochondrial complex activity, which regulates both glucose uptake and cellular energy status. Current therapeutic methods to counter hyperglycemia include tight euglycemic control and/or intensive insulin treatment, which are associated with increases in hypoglycemia and mortality, but also accelerate wound healing rates, potentially decreasing scarring. Alternatives to insulin therapy include biguanide drugs such as metformin. Metformin downregulates gluconeogenesis, and reduces blood glucose levels by activating glucose transport via GLUT4 in muscle cells. Importantly metformin has been shown to decrease mitochondrial respiratory complex I activity in hepatocytes. However its effects in dermal fibroblasts are unknown. Furthermore, up to 90 percent of burn patients develop hypertrophic scars due to dysregulated collagen secretion, which can lead to functional impairment due to excessive collagen deposition associated with hypertrophic scarring. In this study the hypothesis is that in dermal fibroblasts metformin will alter mitochondrial oxidative phosphorylation and alter cAMP and AMPK signaling activity, resulting in increased wound healing and improved mitochondrial function. Our experimental data shows that metformin induced AMPK phosphorylation, reduced mTOR phosphorylation, and downregulated cAMP accumulation in dermal fibroblasts. Fibroblast proliferation and migration were downregulated in hyperglycemic conditions with metformin exposure. Expression of mitochondrial biogenesis genes were altered by metformin treatment. Significantly, metformin specifically upregulated oxygen flux activity in fibroblasts, which was independent of AMPK activity. Metformin also altered expression of epithelial-mesenchymal transition (EMT) genes and markers. The primary EMT pathway regulated by metformin was SMAD3, which was decreased by metformin treatment resulting in decreased collagen I gene expression. Metformin also reduced total collagen secretion in low glucose conditions. These results indicate that metformin alters metabolism in fibroblasts through mitochondrial respiratory chain independently of AMPK. This will allow a better understanding of the effects of metformin on fibroblasts leading to new therapeutic options to prevent burn injury complications for wound healing in burn patients.ations for wound healing in burn patients.)
Patil 2015 Abstract MiPschool Greenville 2015 + (Burn patients are at increased risk of dev … Burn patients are at increased risk of developing wound infection and sepsis leading to multi-organ failure and death [1]. Previous studies show that T cell dysfunction and low absolute lymphocyte counts are major contributing factors to increased mortality in non-burned septic patients [2]. Although impaired antimicrobial immunity has been described in burn patients, the changes in adaptive immunity after burn injury and infection have not been investigated. We used a clinically relevant mouse model of burn wound infection to assess the adaptive immune system function.A 35% TBSA full thickness burn was induced and the wound was infected with ''Pseudomonas aeruginosa'' on day 4 post-burn. Lymphocyte, macrophage and dendritic cell counts and phenotype in spleen and wound draining lymph nodes were characterized by flow cytometry.We observed a significant decline (>80%) in blood absolute lymphocyte count and CD4+ and CD8+ T cell counts in the spleen and burn-draining lymph nodes of wound infected mice (WI) as compared to non-infected burn mice (see figure). WI also lead to a significant decrease in the expression of the co-stimulatory receptor CD28 on both CD4+ and CD8+ cells in spleen and lymph nodes. PD-1 expression was not affected. Dendritic cell counts were significantly decreased on day 2 post WI in the spleen (3x106 vs 4x106 in sham) and in lymph nodes (2x105 vs 6x105 in sham). WI also lead to a significant decrease in F4/80+ macrophage cell counts (48x105 vs 81x105); decrease in expression of MHCII on dendritic cells (29 vs 49 %); and an increase in the expression of PD-L1 on dendritic cells (31 vs 23%), macrophages (25 vs 10%) and Ly6C+ inflammatory monocytes (19 vs 11%) in the spleen, as compared to control. These changes were associated with significant kidney and liver injury and approximately 75 % mortality at day 3 after WI. PD-L1 is an inhibitory ligand expressed on the antigen presenting cells which interacts with PD-1 receptor on T lymphocytes and downregulate their function [3]. Importantly, treatment of wound infected mice with anti-PD-L1 antibody (50 µg, IP) every other day, starting one day before burn injury improved 7 day survival by approximately 30%. We show that adaptive immune system functions are impaired following burn injury and wound infection and associated with a decrease in host resistance to infection. Anti-PD-L1 antibody might have therapeutic benefit in prevention and/or treatment of burn wound associated sepsis.or treatment of burn wound associated sepsis.)
Bhattarai 2015 Abstract MiPschool Greenville 2015 + (Burn victims undergo prolonged immobilizat … Burn victims undergo prolonged immobilization and become profoundly cachectic after injury [1,2]. Loss of muscle mass and function leads to reduced quality of life in burn survivors. Rehabilitative exercise training (RET) has been shown to increase muscle mass and strength while also increasing peak oxygen uptake (peak ''V''O2) in burn survivors [2]. However, the mechanisms responsible for these improvements in physiological function are not fully understood. Here, we studied the impact of chronic RET on whole body (peak ''V''O2) and skeletal muscle ([[OXPHOS]]) oxidative capacity.Fourteen children (7-17 years) with burns covering ≥30% of their total body surface area were studied. After discharge from hospital, patients performed a 6-week supervised RET program. RET consisted of both resistive and aerobic exercise performed at least 3-times weekly on non-consecutive days. Peak ''V''O2 and muscle OXPHOS capacity were determined before and after the RET program. Peak ''V''O2 was determined using a modified Bruce protocol treadmill test. Muscle OXPHOS capacity was determined in permeabilized muscle fibers by high-resolution respirometry.Peak ''V''O2 increased significantly after RET (33.0±2.2 vs. 28.1± 1.7 ml.min-1.kg-1; ''P''<0.001). Muscle OXPHOS capacity increased by 43% after RET (46.7±4.5 vs. 32.5±4.9 pmol.s-1.mg-1, ''P''<0.05).In agreement with the published literature, RET increases aerobic exercise capacity in burn survivors. Here, we show that this is accompanied by an increase in skeletal muscle OXPHOS capacity. We suggest that RET improves whole body physiological function in burn survivors at least part, by improving skeletal muscle OXPHOS capacity.PHOS capacity. We suggest that RET improves whole body physiological function in burn survivors at least part, by improving skeletal muscle OXPHOS capacity.)
Wen 2020 Biomedicines + (Burn-induced cardiac dysfunction is though … Burn-induced cardiac dysfunction is thought to involve mitochondrial dysfunction, although the mechanisms responsible are unclear. In this study, we used our established model of in vivo burn injury to understand the genetic evidence of burn-induced mitochondrial confusion dysfunction by describing cardiac mitochondrial metabolism-related gene expression after burn. Cardiac tissue was collected at 24 hours after burn injury. An O2K respirometer system was utilized to measure the cardiac mitochondrial function. Oxidative phosphorylation complex activities were determined using enzyme activity assays. RT Profiler PCR array was used to identify the differential regulation of genes involved in mitochondrial biogenesis and metabolism. The quantitative qPCR and Western blotting were applied to validate the differentially expressed genes. Burn-induced cardiac mitochondrial dysfunction was supported by the finding of decreased state 3 respiration, decreased mitochondrial electron transport chain activity in complex I, III, IV, and V, and decreased mitochondrial DNA-encoded gene expression as well as decreased levels of the corresponding proteins after burn injury. Eighty-four mitochondrial metabolism-related gene profiles were measured. The mitochondrial gene profile showed that 29 genes related to mitochondrial energy and metabolism was differentially expressed. Of these 29 genes, 16 were more than 2-fold upregulated and 13 were more than 2-fold downregulated. All genes were validated using qPCR and partial genes were correlated with their protein levels. This study provides preliminary evidence that a large percentage of mitochondrial metabolism-related genes in cardiomyocytes were significantly affected by burn injury.ere significantly affected by burn injury.)
Weiss 2022 J Cell Mol Med + (Butyrate is a short-chain fatty acid that … Butyrate is a short-chain fatty acid that is produced by commensal microbes within the intestinal microbiome through fermentation of dietary fibre. Microbial-derived butyrate has been shown to promote immunologic and metabolic homeostasis, in part through its beneficial effects on mitochondrial function, and thus has been proposed as a possible anti-inflammatory therapy. We tested the hypothesis that butyrate could mitigate the decrease in mitochondrial respiration in immune cells under septic conditions as a preliminary step towards better understanding the potential for butyrate as a novel therapy in sepsis. Mitochondrial respiration and content (measured as citrate synthase activity) were compared within four Epstein-Barr virus-transformed lymphoblast (LB) cell lines exposed to either control media or lipopolysaccharide (LPS) 100 ng/ml. Both co-incubation of LBs with LPS + butyrate and treatment with butyrate after LPS stimulation reversed the decrease in mitochondrial respiration observed in LBs exposed to LPS without butyrate. Neither LPS nor butyrate led to significant changes in citrate synthase activity. The preliminary findings support further investigation of a potential mitochondrial-based mechanism through which butyrate may help to mitigate the immuno-inflammatory response in sepsis.he immuno-inflammatory response in sepsis.)
Purhonen 2014 Abstract MiP2014 + (By author request, this abstract has been removed because it contains preliminary observations with a minor conflict with the final results.)
Endlicher 2019 Physiol Res + (By determining the calcium retention capac … By determining the calcium retention capacity (CRC) of rat liver mitochondria, we confirmed and extended previous observations describing the activation of mitochondrial swelling by phosphate and tert-butyl hydroperoxide (t-BHP). Using CRC measurements, we showed that both phosphate and t-BHP decrease the extent of calcium accumulation required for the full mitochondrial permeability transition pore (MPTP) opening to 35 % of control values and to only 15 % when both phosphate and t-BHP are present in the medium. When changes in fluorescence were evaluated at higher resolution, we observed that in the presence of cyclosporine A fluorescence values return after each Ca2+ addition to basal values obtained before the Ca2+ addition. This indicates that the MPTP remains closed. However, in the absence of cyclosporine A, the basal fluorescence after each Ca2+ addition continuously increased. This increase was potentiated both by phosphate and t-BHP until the moment when the concentration of intramitochondrial calcium required for the full opening of the MPTP was reached. We conclude that in the absence of cyclosporine A, the MPTP is slowly opened after each Ca2+ addition and that this rate of opening can be modified by various factors such as the composition of the media and the experimental protocol used.y various factors such as the composition of the media and the experimental protocol used.)
Krishnathas 2017 Med Chem Comm + (By probing the quinone substrate binding s … By probing the quinone substrate binding site of mitochondrial complex I with a focused set ofquinazoline-based compounds, we identified substitution patterns as being critical for the observed inhibition. The structure activity relationship study also resulted in the discovery of the quinazoline 4-N-[2-(4-phenoxyphenyl)ethyl]quinazoline-4,6-diamine (EVP4593) as a highly potent inhibitor of the multisubunitmembrane protein. EVP4593 specifically and effectively reduces the mitochondrial complex I-dependent respiration with no effect on the respiratory chain complexes II–IV. Similar to established Q-site inhibitors, EVP4593 elicits the release of reactive oxygen species at the flavin site of mitochondrial complex I. Recently, EVP4593 was nominated as a lead compound for the treatment of Huntingtons disease. Our results challenge the postulated primary mode-of-action of EVP4593 as an inhibitor of NF-κB pathway activation and/or store-operated calcium influx.tion and/or store-operated calcium influx.)
Timon-Gomez 2020 STAR Protoc + (By using negatively charged Coomassie bril … By using negatively charged Coomassie brilliant blue G-250 dye to induce a charge shift on proteins, blue native polyacrylamide gel electrophoresis (BN-PAGE) allows resolution of enzymatically active multiprotein complexes extracted from cellular or subcellular lysates while retaining their native conformation. BN-PAGE was first developed to analyze the size, composition, and relative abundance of the complexes and supercomplexes that form the mitochondrial respiratory chain and OXPHOS system. Here, we present a detailed protocol of BN-PAGE to obtain robust and reproducible results. For complete details on the use and execution of this protocol, please refer to Lobo-Jarne et al. (2018) and Timón-Gómez et al. (2020). al. (2018) and Timón-Gómez et al. (2020).)
Xu 2017 J Hum Genet + (By using next-generation sequencing target … By using next-generation sequencing targeted to MitoExome including the entire mtDNA and exons of 1033 genes encoding the mitochondrial proteome, we described here a novel m.11240C>T mutation in the mitochondrial ND4 gene from a patient with Leigh syndrome. High mutant loads of m.11240C>T were detected in blood, urinary epithelium, oral mucosal epithelium cells, and skin fibroblasts of the patient. Decreased mitochondrial complex I activity was found in transmitochondrial cybrids containing the m.11240C>T mutation with biochemical analysis. Furthermore, functional investigations confirmed that mitochondria with the m.11240C>T variant exhibited lower adenosine triphosphate-related mitochondrial respiration. However, complex I assembly in mutant cybrids was not affected. While this mutation was located in the fourth hydrophobic trans-membrane region of ND4 gene, we suggested that mutation of m.11240C>T might impair the proton pumping channel of complex I but had little effect on the complex I assembly. In conclusion, we identified m.11240C>T as a novel mitochondrial disease-related mtDNA mutation.t;T as a novel mitochondrial disease-related mtDNA mutation.)
Jung 1944 Walter-Verlag + (C.G. Jung weist nach, daß die beobachtbaren Phänomene des Unbewußten, nämlich Träume und Visionen, bildhafte Zusammenhänge hervorbringen, wie sie auch in der Symbolik der Alchemie angetroffen werden.)
Bentebibel 2006 Biochemistry + (C75 is a potential drug for the treatment … C75 is a potential drug for the treatment of obesity. It was first identified as a competitive, irreversible inhibitor of fatty acid synthase (FAS). It has also been described as a malonyl-CoA analogue that antagonizes the allosteric inhibitory effect of malonyl-CoA on carnitine palmitoyltransferase I (CPT I), the main regulatory enzyme involved in fatty acid oxidation. On the basis of MALDI-TOF analysis, we now provide evidence that C75 can be transformed to its C75-CoA derivative. Unlike the activation produced by C75, the CoA derivative is a potent competitive inhibitor that binds tightly but reversibly to CPT I. IC50 values for yeast-overexpressed L- or M-CPT I isoforms, as well as for purified mitochondria from rat liver and muscle, were within the same range as those observed for etomoxiryl-CoA, a potent inhibitor of CPT I. When a pancreatic INS(823/13), muscle L6E9, or kidney HEK293 cell line was incubated directly with C75, fatty acid oxidation was inhibited. This suggests that C75 could be transformed in the cell to its C75-CoA derivative, inhibiting CPT I activity and consequently fatty acid oxidation. In vivo, a single intraperitoneal injection of C75 in mice produced short-term inhibition of CPT I activity in mitochondria from the liver, soleus, and pancreas, indicating that C75 could be transformed to its C75-CoA derivative in these tissues. Finally, in silico molecular docking studies showed that C75-CoA occupies the same pocket in CPT I as palmitoyl-CoA, suggesting an inhibiting mechanism based on mutual exclusion. Overall, our results describe a novel role for C75 in CPT I activity, highlighting the inhibitory effect of its C75-CoA derivative.hibitory effect of its C75-CoA derivative.)
Moreno-Ortega 2015 Neuropharmacology + (CALHM1 is a Ca2+ ch … CALHM1 is a Ca2+ channel discovered in 2008, which plays a key role in the neuronal electrical activity, among other functions. However, there are no known efficient blockers able to modulate its Ca2+ handling ability. We herein describe that benzothiazepine CGP37157 and its newly synthesized analogue ITH12575 reduced Ca2+ influx through CALHM1 at low micromolar concentrations. These results could serve as a starting point for the development of more selective CALHM1 ligands using CGP37157 as a hit compound, which would help to study the physiological role of CALHM1 in the control of [2+]cyt in excitable cells, as well as its implication in CNS diseases.Copyright © 2015 Elsevier Ltd. All rights reserved.l as its implication in CNS diseases. Copyright © 2015 Elsevier Ltd. All rights reserved.)
Stouth 2023 Autophagy + (CARM1 (coactivator associated arginine met … CARM1 (coactivator associated arginine methyltransferase 1) has recently emerged as a powerful regulator of skeletal muscle biology. However, the molecular mechanisms by which the methyltransferase remodels muscle remain to be fully understood. In this study, carm1 skeletal muscle-specific knockout (mKO) mice exhibited lower muscle mass with dysregulated macroautophagic/autophagic and atrophic signaling, including depressed AMP-activated protein kinase (AMPK) site-specific phosphorylation of ULK1 (unc-51 like autophagy activating kinase 1; Ser555) and FOXO3 (forkhead box O3; Ser588), as well as MTOR (mechanistic target of rapamycin kinase)-induced inhibition of ULK1 (Ser757), along with AKT/protein kinase B site-specific suppression of FOXO1 (Ser256) and FOXO3 (Ser253). In addition to lower mitophagy and autophagy flux in skeletal muscle, carm1 mKO led to increased mitochondrial PRKN/parkin accumulation, which suggests that CARM1 is required for basal mitochondrial turnover and autophagic clearance. carm1 deletion also elicited PPARGC1A (PPARG coactivator 1 alpha) activity and a slower, more oxidative muscle phenotype. As such, these carm1 mKO-evoked adaptations disrupted mitophagy and autophagy induction during food deprivation and collectively served to mitigate fasting-induced muscle atrophy. Furthermore, at the threshold of muscle atrophy during food deprivation experiments in humans, skeletal muscle CARM1 activity decreased similarly to our observations in mice, and was accompanied by site-specific activation of ULK1 (Ser757), highlighting the translational impact of the methyltransferase in human skeletal muscle. Taken together, our results indicate that CARM1 governs mitophagic, autophagic, and atrophic processes fundamental to the maintenance and remodeling of muscle mass. Targeting the enzyme may provide new therapeutic approaches for mitigating skeletal muscle atrophy.es for mitigating skeletal muscle atrophy.)
Patyal 2022 Int J Mol Sci + (CCG-1423 is a Rho A pathway inhibitor that … CCG-1423 is a Rho A pathway inhibitor that has been reported to inhibit Rho/SRF-mediated transcriptional regulation. Serum response factor and its cofactors, which include ternary complex factors and myocardin-related transcription factors, regulate various cellular functions. In this study, we observed that CCG-1423 modulates the mitochondrial functions. The effect of this small molecule drug was determined by measuring mitochondrial function using an XFe96 Analyzer and an Oxygraph 2k (O2k) high-resolution respirometer. CCG-1423 treatment significantly reduced oxidative phosphorylation in a dose-dependent manner. However, CCG-1423 increased the glycolytic rate. We also observed that histone 4 at lysine-16 underwent hyperacetylation with the treatment of this drug. Immunolabeling with F-actin and MitoTracker revealed the alteration in the actin cytoskeleton and mitochondria. Taken together, our findings highlight a critical role of CCG-1423 in inhibiting the transcription of SRF/p49 and PGC-1α, β, resulting in the downregulation of mitochondrial genes, leading to the repression of mitochondrial oxidative phosphorylation and overall ATP reduction. This study provides a better understanding of the effects of CCG-1423 on mitochondria, which may be useful for the assessment of the potential clinical application of CCG-1423 and its derivatives.plication of CCG-1423 and its derivatives.)
Van der Windt 2012 Immunity + (CD8(+) T cells undergo major metabolic cha … CD8(+) T cells undergo major metabolic changes upon activation, but how metabolism influences the establishment of long-lived memory T cells after infection remains a key question. We have shown here that CD8(+) memory T cells, but not CD8(+) T effector (Teff) cells, possessed substantial mitochondrial spare respiratory capacity (SRC). SRC is the extra capacity available in cells to produce energy in response to increased stress or work and as such is associated with cellular survival. We found that interleukin-15 (IL-15), a cytokine critical for CD8(+) memory T cells, regulated SRC and oxidative metabolism by promoting mitochondrial biogenesis and expression of carnitine palmitoyl transferase (CPT1a), a metabolic enzyme that controls the rate-limiting step to mitochondrial fatty acid oxidation (FAO). These results show how cytokines control the bioenergetic stability of memory T cells after infection by regulating mitochondrial metabolism.on by regulating mitochondrial metabolism.)
Blunsom 2018 Biochim Biophys Acta + (CDP diacylglycerol synthase (CDS) catalyse … CDP diacylglycerol synthase (CDS) catalyses the conversion of phosphatidic acid (PA) to CDP-diacylglycerol, an essential intermediate in the synthesis of phosphatidylglycerol, cardiolipin and phosphatidylinositol (PI). CDS activity has been identified in mitochondria and endoplasmic reticulum of mammalian cells apparently encoded by two highly-related genes, CDS1 and CDS2. Cardiolipin is exclusively synthesised in mitochondria and recent studies in cardiomyocytes suggest that the peroxisome proliferator-activated receptor γ coactivator 1 (PGC-1α and β) serve as transcriptional regulators of mitochondrial biogenesis and up-regulate the transcription of the CDS1 gene. Here we have examined whether CDS1 is responsible for the mitochondrial CDS activity. We report that differentiation of H9c2 cells with retinoic acid towards cardiomyocytes is accompanied by increased expression of mitochondrial proteins, oxygen consumption, and expression of the PA/PI binding protein, PITPNC1, and CDS1 immunoreactivity. Both CDS1 immunoreactivity and CDS activity were found in mitochondria of H9c2 cells as well as in rat heart, liver and brain mitochondria. However, the CDS1 immunoreactivity was traced to a peripheral p55 cross-reactive mitochondrial protein and the mitochondrial CDS activity was due to a peripheral mitochondrial protein, TAMM41, not an integral membrane protein as expected for CDS1. TAMM41 is the mammalian equivalent of the recently identified yeast protein, Tam41. Knockdown of TAMM41 resulted in decreased mitochondrial CDS activity, decreased cardiolipin levels and a decrease in oxygen consumption. We conclude that the CDS activity present in mitochondria is mainly due to TAMM41, which is required for normal mitochondrial function.equired for normal mitochondrial function.)
Hunter 2012 Biochem Pharmacol + (CEN-209 (SN30000) is a second-generation b … CEN-209 (SN30000) is a second-generation benzotriazine di-N-oxide currently in advanced preclinical development as a hypoxia-activated prodrug (HAP). Herein we describe the DNA repair-, hypoxia- and one-electron reductase-dependence of CEN-209 cytotoxicity. We deployed mutant CHO cell lines to generate DNA repair profiles for CEN-209, and compared the profiles with those for other HAPs. Hypoxic selectivity of CEN-209 was significantly greater than PR-104A and the nitro-chloromethylbenzindoline (nCBI/SN29428) and comparable to tirapazamine and TH-302. CEN-209 was selective for homologous recombination (HR) repair-deficient cells (Rad51d−/−), but less so than nitrogen mustard prodrugs TH-302 and PR-104A. Further, DNA repair profiles for CEN-209 differed under oxic and hypoxic conditions, with oxic cytotoxicity more dependent on HR. This feature was conserved across all three members of the benzotriazine di-N-oxide class examined (tirapazamine, CEN-209 and CEN-309/SN29751). Enhancing one-electron reduction of CEN-209 by forced expression of a soluble form of NADPH:cytochrome P450 oxidoreductase (sPOR) increased CEN-209 cytotoxicity more markedly under oxic than hypoxic conditions. Comparison of oxygen consumption, H2O2 production and metabolism of CEN-209 to the corresponding 1-oxide and nor-oxide reduced metabolites suggested that enhanced oxic cytotoxicity in cells with high one-electron reductase activity is due to futile redox cycling. This study supports the hypothesis that both oxic and hypoxic cell killing by CEN-209 is mechanistically analogous to tirapazamine and is dependent on oxidative DNA damage repaired via multiple pathways. However, HAPs that generate DNA interstrand cross-links, such as TH-302 and PR-104, may be more suitable than benzotriazine di-N-oxides for exploiting reported HR repair defects in hypoxic tumour cells.HR repair defects in hypoxic tumour cells.)
CFAS Symposium 2023 Copenhagen DK + (CFAS 2023 Symposium on “Exercise as Medicine”, Copenhagen, Denmark, 2023)
Maiti 2015 PhD Thesis + (CLPP (caseinolytic mitochondrial matrix pe … CLPP (caseinolytic mitochondrial matrix peptidase proteolytic subunit) is a highly conserved serine protease. Molecular and structural studies in ''E. coli'' and other prokaryotes have revealed CLPP specific substrates and the mechanisms underlying their identification and subsequent degradation. These studies showed that ClpXP is involved in DNA damage repair, stationary-phase gene expression, and ssrA-mediated protein quality control. Similarly, diverse roles for the eukaryotic CLPP have been suggested. In the filamentous fungus ''Podospora anserine'' ''Clpp'' depletion promotes longevity. In ''Caenorhabditis elegans'' it has been demonstrated that CLPP have a central role in mediating the UPRmt signals. Loss of function CLPP mutations in humans cause Perrault syndrome that results in ovarian failure and sensorineural hearing loss accompanied with shorter stature. Despite this we still have a very limited knowledge about the functional role of eukaryotic CLPP, its specific substrates and underlying molecular mechanism. In order to decipher the ''in vivo'' role of CLPP in mammals we have developed a CLPP deficient mouse model (''Clpp-/-''). Interestingly, only about half of ''Clpp'' knockout mice according to Mendelian proportion (12,5%) are born from intercrossing of ''Clpp+/-'' mice. These mice are infertile and born ~ 30% smaller than littermates. CLPP deficient mice faithfully replicate the phenotypes observed in human patients. On the molecular level CLPP deficiency leads to an early specific decrease in Complex I activity, followed by a decrease in Complex IV activity later in life. Furthermore, we observed a decrease in mitochondrial translation, which is compensated for by upregulation of mitochondrial transcription. This suggests a direct or indirect role of CLPP in the process of mitochondrial protein synthesis. Gradient sedimentation analysis demonstrates an increase in the steady state levels of small ribosomal subunits, while large ribosomal subunits and monosomes are present in almost normal levels. We also observed an impairment of 12S rRNA assembly into monosomes leading to lower loading of mtmRNAs. This indicates complications in the function of monosomes. Search for CLPXP substrates and interactors revealed two candidates that are likely to be involved in this process. We show that ERAL1 is one of the substrates of CLPP that is likely causing defective 12S rRNA assembly into the small ribosomal subunit. Additionally, p32, a CLPP interactor is permanently bound to the mitoribosomes. We believe that through interaction with CLPXP, these proteins are involved in resolution of stalled ribosomes. We are currently working further on elucidating the molecular mechanism underlying impaired mitochondrial translation.idating the molecular mechanism underlying impaired mitochondrial translation.)
Kodama 2009 JAMA + (CONTEXT: Epidemiological studies have indi … CONTEXT: Epidemiological studies have indicated an inverse association between cardiorespiratory fitness (CRF) and coronary heart disease (CHD) or all-cause mortality in healthy participants.OBJECTIVE: To define quantitative relationships between CRF and CHD events, cardiovascular disease (CVD) events, or all-cause mortality in healthy men and women.DATA SOURCES AND STUDY SELECTION: A systematic literature search was conducted for observational cohort studies using MEDLINE (1966 to December 31, 2008) and EMBASE (1980 to December 31, 2008). The Medical Subject Headings search terms used included exercise tolerance, exercise test, exercise/physiology, physical fitness, oxygen consumption, cardiovascular diseases, myocardial ischemia, mortality, mortalities, death, fatality, fatal, incidence, or morbidity. Studies reporting associations of baseline CRF with CHD events, CVD events, or all-cause mortality in healthy participants were included.DATA EXTRACTION: Two authors independently extracted relevant data. CRF was estimated as maximal aerobic capacity (MAC) expressed in metabolic equivalent (MET) units. Participants were categorized as low CRF (< 7.9 METs), intermediate CRF (7.9-10.8 METs), or high CRF (> or = 10.9 METs). CHD and CVD were combined into 1 outcome (CHD/CVD). Risk ratios (RRs) for a 1-MET higher level of MAC and for participants with lower vs higher CRF were calculated with a random-effects model.DATA SYNTHESIS: Data were obtained from 33 eligible studies (all-cause mortality, 102 980 participants and 6910 cases; CHD/CVD, 84 323 participants and 4485 cases). Pooled RRs of all-cause mortality and CHD/CVD events per 1-MET higher level of MAC (corresponding to 1-km/h higher running/jogging speed) were 0.87 (95 % confidence interval [CI], 0.84-0.90) and 0.85 (95 % CI, 0.82-0.88), respectively. Compared with participants with high CRF, those with low CRF had an RR for all-cause mortality of 1.70 (95 % CI, 1.51-1.92; P < .001) and for CHD/CVD events of 1.56 (95% CI, 1.39-1.75; P < .001), adjusting for heterogeneity of study design. Compared with participants with intermediate CRF, those with low CRF had an RR for all-cause mortality of 1.40 (95 % CI, 1.32-1.48; ''P'' < .001) and for CHD/CVD events of 1.47 (95 % CI, 1.35-1.61; ''P'' < .001), adjusting for heterogeneity of study design.CONCLUSIONS: Better CRF was associated with lower risk of all-cause mortality and CHD/CVD. Participants with a MAC of 7.9 METs or more had substantially lower rates of all-cause mortality and CHD/CVD events compared with those with a MAC of less 7.9 METs./CVD events compared with those with a MAC of less 7.9 METs.)
Chomentowski 2011 J Clin Endocrinol Metab + (CONTEXT: Insulin resistance is accompanied … CONTEXT: Insulin resistance is accompanied by lower lipid oxidation during fasting and metabolic inflexibility. Whether these abnormalities correlate with mitochondrial content in skeletal muscle is unknown.OBJECTIVE: The objective of the study was to investigate whether decreased fasting lipid oxidation, metabolic inflexibility, and impaired glucose disposal correlate with reduced mitochondrial content in intermyofibrillar vs. subsarcolemmal (SS) subpopulations.DESIGN: Forty sedentary adults with a wide spectrum of insulin sensitivity were studied: insulin-sensitive lean subjects, insulin-resistant nondiabetic subjects, and subjects with type 2 diabetes mellitus. Glucose disposal was measured by euglycemic clamp and [6,6-D(2)]-glucose methodology. Fuel oxidation and metabolic flexibility (during clamps) were assessed by indirect calorimetry. Maximum aerobic capacity was assessed by treadmill testing. Intermyofibrillar and SS mitochondrial content were measured by quantitative electron microscopy of muscle biopsy samples.RESULTS: Intermyofibrillar mitochondrial content was lower in the insulin-resistant nondiabetic subjects and type 2 diabetes mellitus groups, significantly correlating with glucose disposal in both men (R = 0.72, P < 0.01) and women (R = 0.53, P < 0.01). In contrast, SS mitochondrial content was similar among groups. Lower intermyofibrillar mitochondrial content was not explained by mitochondrial size, altered fiber-type distribution, or differences in maximum aerobic capacity. Intermyofibrillar mitochondrial content was significantly correlated with fasting respiratory quotient (R = -0.46, P = 0.003) and metabolic flexibility (R = 0.38, P = 0.02).CONCLUSIONS: In obese-insulin-resistant subjects with or without diabetes, intermyofibrillar mitochondrial content is decreased. This is not entirely explained by fitness status or fiber-type composition. SS mitochondrial content is unaffected, suggesting independent mitochondrial pool regulation. Lower mitochondrial content correlates with lower fasting lipid oxidation and metabolic inflexibility, suggesting it may be intrinsically linked to abnormal fuel utilization patterns of obesity-associated insulin resistance.tterns of obesity-associated insulin resistance.)
Hatch 1998 JAMA + (CONTEXT: Many journals provide peer review … CONTEXT: Many journals provide peer reviewers with written instructions regarding review criteria, such as the originality of results, but little research has been done to investigate ways to improve or facilitate the peer review task.OBJECTIVE: To assess the value that peer reviewers place on receipt of supplemental materials (eg, abstracts of related papers and preprints of related unpublished manuscripts).DESIGN: Questionnaire survey sent to all 733 peer reviewers recruited by the Journal of the National Cancer Institute to review 356 manuscripts consecutively sent out for review from February 24, 1997, through January 16, 1998. The inclusion of supplemental materials with manuscript review packages was optional.MAIN OUTCOME MEASURE: The peer reviewers' assessment of the actual or potential usefulness of supplemental materials on the performance of peer review.RESULTS: A total of 481 (66%) of 733 questionnaires were returned. Of the 471 respondents' questionnaires that could be used, 217 (46%) indicated that they received abstracts, and 44 (10%) of 458 respondents indicated that they received preprints. Higher proportions of peer reviewers who received supplemental materials than those who had not received them felt that they were (or would be) useful to them when reviewing the manuscript (63% [95% confidence interval (CI), 57%-69%] vs 45% [95% CI, 38%-52%]; P<.001) and to the peer review process in general (80% [95% CI, 75%-85%] vs 64% [95% CI, 58%-70%]; P<.001).CONCLUSION: The majority of respondents indicated that supplemental materials helped (or would have helped) them evaluate manuscripts and valued them more highly when they actually received them.em more highly when they actually received them.)
Wei 1999 JAMA + (CONTEXT: Recent guidelines for treatment o … CONTEXT: Recent guidelines for treatment of overweight and obesity include recommendations for risk stratification by disease conditions and cardiovascular disease (CVD) risk factors, but the role of physical inactivity is not prominent in these recommendations.OBJECTIVE: To quantify the influence of low cardiorespiratory fitness, an objective marker of physical inactivity, on CVD and all-cause mortality in normal-weight, overweight, and obese men and compare low fitness with other mortality predictors.DESIGN: Prospective observational data from the Aerobics Center Longitudinal Study.SETTING: Preventive medicine clinic in Dallas, Tex.PARTICIPANTS: A total of 25714 adult men (average age, 43.8 years [SD, 10.1 years]) who received a medical examination during 1970 to 1993, with mortality follow-up to December 31, 1994.MAIN OUTCOME MEASURES: Cardiovascular disease and all-cause mortality based on mortality predictors (baseline CVD, type 2 diabetes mellitus, high serum cholesterol level, hypertension, current cigarette smoking, and low cardiorespiratory fitness) stratified by body mass index.RESULTS: During the study period, there were 1025 deaths (439 due to CVD) during 258781 man-years of follow-up. Overweight and obese men with baseline CVD or CVD risk factors were at higher risk for all-cause and CVD mortality compared with normal-weight men without these predictors. Using normal-weight men without CVD as the referent, the strongest predictor of CVD death in obese men was baseline CVD (age- and examination year-adjusted relative risk [RR], 14.0; 95 % confidence interval [CI], 9.4-20.8); RRs for obese men with diabetes mellitus, high cholesterol, hypertension, smoking, and low fitness were similar and ranged from 4.4 (95 % CI, 2.7-7.1) for smoking to 5.0 (95 % CI, 3.6-7.0) for low fitness. Relative risks for all-cause mortality in obese men ranged from 2.3 (95 % CI, 1.7-2.9) for men with hypertension to 4.7 (95 % CI, 3.6-6.1) for those with CVD at baseline. Relative risk for all-cause mortality in obese men with low fitness was 3.1 (95 % CI, 2.5-3.8) and in obese men with diabetes mellitus 3.1 (95 % CI, 2.3-4.2) and as slightly higher than the RRs for obese men who smoked or had high cholesterol levels. Low fitness was an independent predictor of mortality in all body mass index groups after adjustment for other mortality predictors. Approximately 50 % (''N'' = 1674) of obese men had low fitness, which led to a population-attributable risk of 39 % for CVD mortality and 44 % for all-cause mortality. Baseline CVD had population attributable risks of 51 % and 27 % for CVD and all-cause mortality, respectively.CONCLUSIONS: In this analysis, low cardiorespiratory fitness was a strong and independent predictor of CVD and all-cause mortality and of comparable importance with that of diabetes mellitus and other CVD risk factors.betes mellitus and other CVD risk factors.)
Wijers 2011 J Clin Endocrinol Metab + (CONTEXT: Recently, brown adipose tissue (B … CONTEXT: Recently, brown adipose tissue (BAT) gained interest as a possible target for cold-induced thermogenesis, and therefore a target for treatment of obesity in adult humans. However, mitochondrial uncoupling takes place not only in BAT but also in skeletal muscle tissue. Both tissues may be involved in cold-induced thermogenesis, which is presumably regulated by the sympathetic nervous system.OBJECTIVE: Here we studied whether blockade of β-adrenergic receptors using propranolol diminishes cold-induced thermogenesis and mitochondrial uncoupling in skeletal muscle tissue.DESIGN: Ten lean subjects participated in this study and stayed twice (control and β-blockade using propranolol) for 84 h in a respiration chamber-the first 36 h for baseline measurements, followed by 48 h of mild cold exposure (16 °C). Energy expenditure was measured continuously. After 36 and 84 h, muscle biopsies were taken in which mitochondrial uncoupling was studied.RESULTS: Energy expenditure increased upon mild cold exposure (+5.0 ± 1.2 W; ''P'' < 0.005), i.e. cold-induced thermogenesis. However, contrary to our hypothesis, this cold-induced thermogenesis was not diminished after β-blockade (+4.7 ± 2.1 W for blockade vs. +5.1 ± 1.4 W for control; ''P'' = 0.59 for interaction cold blockade). Skeletal muscle mitochondrial uncoupling was significantly related to cold-induced thermogenesis in the control situation (''r''(2) = 0.650; ''P'' < 0.01). There was no such relation during β-blockade.CONCLUSIONS: Our results suggest that skeletal muscle mitochondrial uncoupling may be involved in cold-induced thermogenesis and that this may be regulated by β(2)-receptors. When the β(1)- and β(2)-receptors are blocked, a β(3)-regulated process like mitochondrial uncoupling in BAT might take over the role of skeletal muscle mitochondrial uncoupling.ole of skeletal muscle mitochondrial uncoupling.)
Joshi 2007 JAMA + (CONTEXT: South Asians have high rates of a … CONTEXT: South Asians have high rates of acute myocardial infarction (AMI) at younger ages compared with individuals from other countries but the reasons for this are unclear.OBJECTIVE: To evaluate the association of risk factors for AMI in native South Asians, especially at younger ages, compared with individuals from other countries.DESIGN, SETTING, AND PARTICIPANTS: Standardized case-control study of 1732 cases with first AMI and 2204 controls matched by age and sex from 15 medical centers in 5 South Asian countries and 10,728 cases and 12,431 controls from other countries. Individuals were recruited to the study between February 1999 and March 2003.MAIN OUTCOME MEASURE: Association of risk factors for AMI.RESULTS: The mean (SD) age for first AMI was lower in South Asian countries (53.0 [11.4] years) than in other countries (58.8 [12.2] years; ''P''<.001). Protective factors were lower in South Asian controls than in controls from other countries (moderate- or high-intensity exercise, 6.1 % vs 21.6 %; daily intake of fruits and vegetables, 26.5 % vs 45.2 %; alcohol consumption > or =once/wk, 10.7 % vs 26.9 %). However, some harmful factors were more common in native South Asians than in individuals from other countries (elevated apolipoprotein B(100) /apolipoprotein A-I ratio, 43.8 % vs 31.8 %; history of diabetes, 9.5 % vs 7.2 %). Similar relative associations were found in South Asians compared with individuals from other countries for the risk factors of current and former smoking, apolipoprotein B100/apolipoprotein A-I ratio for the top vs lowest tertile, waist-to-hip ratio for the top vs lowest tertile, history of hypertension, history of diabetes, psychosocial factors such as depression and stress at work or home, regular moderate- or high-intensity exercise, and daily intake of fruits and vegetables. Alcohol consumption was not found to be a risk factor for AMI in South Asians. The combined odds ratio for all 9 risk factors was similar in South Asians (123.3; 95 % confidence interval [CI], 38.7-400.2] and in individuals from other countries (125.7; 95 % CI, 88.5-178.4). The similarities in the odds ratios for the risk factors explained a high and similar degree of population attributable risk in both groups (85.8 % [95 % CI, 78.0 %-93.7 %] vs 88.2 % [95 % CI, 86.3 %-89.9 %], respectively). When stratified by age, South Asians had more risk factors at ages younger than 60 years. After adjusting for all 9 risk factors, the predictive probability of classifying an AMI case as being younger than 40 years was similar in individuals from South Asian countries and those from other countries.CONCLUSION: The earlier age of AMI in South Asians can be largely explained by higher risk factor levels at younger ages.ed by higher risk factor levels at younger ages.)
Bialas 2018 Int J Chron Obstruct Pulmon Dis + (COPD represents a major global health issu … COPD represents a major global health issue, which is often accompanied by cardiovascular diseases. A considerable body of evidence suggests that cardiovascular risk is elevated by the activation of blood platelets, which in turn is exacerbated by inflammation. As reactive oxygen species are believed to be an important factor in platelet metabolism and functioning, the aim of our study was to perform a complex assessment of mitochondrial function in platelets in chronic smoke exposed animals with COPD-like lung lesions.Eight-week-old, male Dunkin Hartley guinea pigs (the study group) were exposed to the cigarette smoke from commercial unfiltered cigarettes (0.9 mg/cig of nicotine content) or to the air without cigarette smoke (control group), using the Candela Constructions® exposure system. The animals were exposed for 4 hours daily, 5 days a week, with 2×70 mL puff/minute, until signs of dyspnea were observed. The animals were bled, and isolated platelets were used to monitor blood platelet respiration. The mitochondrial respiratory parameters of the platelets were monitored ''in vitro'' based on continuous recording of oxygen consumption by high-resolution respirometry.An elevated respiration trend was observed in the LEAK-state (adjusted for number of platelets) in the smoke-exposed animals: 6.75 (5.09) vs 2.53 (1.28) (pmol O2/[s · 1×108 platelets]); bootstrap-boosted P1α=0.04. The study group also demonstrated lowered respiration in the ET-state (normalized for protein content): 12.31 (4.84) vs 16.48 (1.72) (pmol O2/[s · mg of protein]); bootstrap-boosted P1α=0.049.Our results suggest increased proton and electron leak and decreased electron transfer system capacity in platelets from chronic smoke-exposed animals. These observations may also indicate that platelets play an important role in the pathobiology of COPD and its comorbidities and may serve as a background for possible therapeutic targeting. However, these preliminary outcomes should be further validated in studies based on larger samples.g. However, these preliminary outcomes should be further validated in studies based on larger samples.)
Paprocka 2022 Metabolites + (COQ8A-ataxia is a mitochondrial disease in … COQ8A-ataxia is a mitochondrial disease in which a defect in coenzyme Q10 synthesis leads to dysfunction of the respiratory chain. The disease is usually present as childhood-onset progressive ataxia with developmental regression and cerebellar atrophy. However, due to variable phenotype, it may be hard to distinguish from other mitochondrial diseases and a wide spectrum of childhood-onset cerebellar ataxia. COQ8A-ataxia is a potentially treatable condition with the supplementation of coenzyme Q10 as a main therapy; however, even 50% may not respond to the treatment. In this study we review the clinical manifestation and management of COQ8A-ataxia, focusing on current knowledge of coenzyme Q10 supplementation and approach to further therapies. Moreover, the case of a 22-month-old girl with cerebellar ataxia and developmental regression will be presented.evelopmental regression will be presented.)
EU-METAHEART MC2 Meeting 2024 Antalya TR + (COST CA22169 METAHEART Management Committee meeting MC2, Antalya, Turkey, 2024)
Brown 2020 BMJ + (COVID-19 (Coronavirus) mortality dispropor … COVID-19 (Coronavirus) mortality disproportionately impacts BAME (Black, Asian and Minority Ethnic) UK individuals, African Americans, Swedish Somalis,[1] and the institutionalised; particularly care-home residents. COVID-19 severity and mortality, appear related to vitamin D deficiency, [2-12] helping explain higher COVID-19 mortality rates in BAME and the obese.[13] Obesity is a strong COVID-19 risk factor, as are co-morbidities, including diabetes, cardio-vascular disease; and sedentary lifestyle; all are dependent on mitochondrial functionality.[14] Fat cells accrete vitamin D.[15] The obese consistently have proportionately lower vitamin D status (serum 25-hydroxyvitamin D [25(OH)D]).[16](serum 25-hydroxyvitamin D [25(OH)D]).[16])
CRUK Beatson Institute Workshop 2022 Glasgow UK + (CRUK Beatson Institute Workshop, Glasgow, United Kingdom, 2022)
Ryu 2010 FEBS Lett + (Ca(2+) channels that underlie mitochondria … Ca(2+) channels that underlie mitochondrial Ca(2+) transport first reported decades ago have now just recently been precisely characterized electrophysiologically. Numerous data indicate that mitochondrial Ca(2+) uptake via these channels regulates multiple intracellular processes by shaping cytosolic and mitochondrial Ca(2+) transients, as well as altering the cellular metabolic and redox state. On the other hand, mitochondrial Ca(2+) overload also initiates a cascade of events that leads to cell death. Thus, characterization of mitochondrial Ca(2+) channels is central to a comprehensive understanding of cell signaling. Here, we discuss recent progresses in the biophysical and electrophysiological characterization of several distinct mitochondrial Ca(2+) channels.Copyright 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.shed by Elsevier B.V. All rights reserved.)
Endlicher 2009 Acta Medica (Hradec Kralove) + (Ca(2+)-induced opening of the mitochondria … Ca(2+)-induced opening of the mitochondrial permeability transition pore (MPTP) is involved in induction of apoptotic and necrotic processes. We studied sensitivity of MPTP to calcium using the model of Ca(2+)-induced, cyclosporine A-sensitive mitochondrial swelling. Presented data indicate that the extent of mitochondrial swelling (dA520/4 min) induced by addition of 25 microM Ca2+ is seven-fold higher in liver than in heart mitochondria (0.564 +/- 0.08/0.077 +/- 0.01). The extent of swelling induced by 100 microM Ca2+ was in liver tree times higher than in heart mitochondria (0.508 +/- 0.05/ 0.173 +/- 0.02). Cyclosporine A sensitivity showed that opening of the MPTP is involved. We may thus conclude that especially at low Ca2+ concentration heart mitochondria are more resistant to damaging effect of Ca2+ than liver mitochondria. These finding thus support hypothesis that there exist tissue specific strategies of cell protection against induction of the apoptotic and necrotic processes.n of the apoptotic and necrotic processes.)
McMillin-Wood 1980 Biochim Biophys Acta + (Ca/+ transport and respiratory characteris … Ca/+ transport and respiratory characteristics of two preparations of cardiac mitochondria (Palmer, J.W., Tandler, B. and Hoppel, C.L. (1977) J. Biol. Chem. 252, 8731-8739) isolated using polytron homogenization (subsarcolemmal mitochondria) and limited Nagarse exposure (intermyofibrillar mitochondria) are described. The Nagarse procedure yields mitochondria with 50% higher rates of oxidative phosphorylation than the polytron-prepared mitochondria in both rat and dog. Rat hear intermyofibrillar mitochondria contain 50% more cytochrome aa3 than the polytron preparation, whereas in the dog, cytochrome aa3 content is not significantly different. Cytochrome oxidase activities and cytochrome c, c1 and b contents were comparable in both populations of rat and dog heart mitochondria. The V of succinate-supported Ca2+ accumulation for Nagarse-prepared mitochondria from rat heart was 1.8-fold higher than the polytron-prepared mitochondria. In dog heart, the Nagarse preparation showed a 3.0-fold higher V for Ca2+ uptake compared to the polytron preparation. A lower apparent affinity for Ca2+ was demonstrated in the intermyofibrillar mitochondria for both species (Km is 2-2.5-fold higher). The Hill coefficient was 1 both mitochondrial types. Subsarcolemmal mitochondria from both species were treated with Nagarse to determine the role of this treatment on the observed differences. Nagarse did not alter any kinetic parameter of Ca2+ uptake. The properties of these mitochondria with reference to their presumed intracellular location may pertain to the role of mitochondria as an intracellular Ca2+ buffering mechanism in contractile tissue.buffering mechanism in contractile tissue.)
Lidron 2016 Abstract Mito Xmas Meeting Innsbruck + (Ca2+ is a fundament … Ca2+ is a fundamental signalling molecule which decodes a variety of extra-and intra-cellular inputs and regulates diverse biological processes, from egg fertilization to organogenesis and tissue specific function, such as contraction in skeletal muscle and neuronal firing in brain. Mitochondria are one of the most important targets and regulators of cellular Ca2+ signalling. In 2011, the molecular complex responsible for the entry of Ca2+ in mitochondria, the mitochondrial Ca2+ uniporter (MCU), was identified by our and Mootha’s groups, opening the path for the biochemical and molecular characterization of the mechanisms underlying mitochondria contribution to Ca2+ signalling. Our work aims to explore the contribution of MCU and mitochondrial Ca2+ dynamics in the regulation of vertebrate development and organogenesis implementing the zebrafish (danio rerio) as a model organism. Our experimental strategy consists in knocking down drMCU expression during zebrafish embryonic development. Western blot analysis reveals an efficient MCU knocking down after 48-72 hpf, accompanied by reduced Ca2+ uptake in morphant embryo cells. The down regulation of MCU is extraordinarily maintained up to 8 dpf, suggesting a strong maternal contribution to MCU expression during early stages. Despite MCU morphant fish develop without gross morphological abnormalities, to a deeper analysis they present an altered skeletal muscle structure and a compromised motor neuron differentiation. Concluding, our data indicate a role of MCU in early zebrafish development and in particular we found that MCU is required for the differentiation and maturation of skeletal musculature and of motor neuron network.ular we found that MCU is required for the differentiation and maturation of skeletal musculature and of motor neuron network.)
Khamoui 2020 Physiol Genomics + (Cachexia is a life-threatening complicatio … Cachexia is a life-threatening complication of cancer traditionally characterized by weight loss and muscle dysfunction. Cachexia, however, is a systemic disease that also involves remodeling of non-muscle organs. The liver exerts major control over systemic metabolism yet its role in cancer cachexia is not well-understood. To advance the understanding of how the liver contributes to cancer cachexia, we used quantitative proteomics and bioinformatics to identify hepatic pathways and cellular processes dysregulated in mice with moderate and severe colon-26 tumor-induced cachexia. ~300 differentially expressed proteins identified during the induction of moderate cachexia were also differentially regulated in the transition to severe cachexia. KEGG pathways enrichment revealed representation by oxidative phosphorylation, indicating altered hepatic mitochondrial function as a common feature across cachexia severity. Glycogen catabolism was also observed in cachexic livers along with decreased pyruvate dehydrogenase protein X component (Pdhx), increased lactate dehydrogenase A chain (Ldha), and increased lactate transporter Mct1. Together this suggests altered lactate metabolism and transport in cachexic livers, which may contribute to energetically inefficient inter-organ lactate cycling. Acyl-CoA synthetase-1 (ACSL1), known for activating long-chain fatty acids, was decreased in moderate and severe cachexia based on LC-MS/MS and immunoblotting. ACSL1 showed strong linear relationships with percent body weight change and muscle fiber size (R2=0.73-0.76, P<0.01). Mitochondrial coupling efficiency, which is compromised in cachexic livers to potentially increase energy expenditure and weight loss, also showed a linear relationship with ACSL1. These findings suggest altered mitochondrial and substrate metabolism of the liver in cancer cachexia, and possible hepatic targets for intervention.nd possible hepatic targets for intervention.)
Branca 2020 Front Cell Dev Biol + (Cadmium (Cd) is a well-known heavy metal a … Cadmium (Cd) is a well-known heavy metal and environmental toxicant and pollutant worldwide, being largely present in every kind of item such as plastic (toys), battery, paints, ceramics, contaminated water, air, soil, food, fertilizers, and cigarette smoke. Nowadays, it represents an important research area for the scientific community mainly for its effects on public health. Due to a half-life ranging between 15 and 30 years, Cd owns the ability to accumulate in organs and tissues, exerting deleterious effects. Thus, even at low doses, a Cd prolonged exposure may cause a multiorgan toxicity. Mitochondria are key intracellular targets for Cd-induced cytotoxicity, but the underlying mechanisms are not fully elucidated. The present review is aimed to clarify the effects of Cd on mitochondria and, particularly, on the mitochondrial electron transport chain.he mitochondrial electron transport chain.)
Zhang 2020 Chemosphere + (Cadmium (Cd) is a widespread environment c … Cadmium (Cd) is a widespread environment contaminant due to the development of electroplating and metallurgical industry. Cd can be enriched by organisms via food chain, causing the enlarged environmental problems and posing threats to the health of humans. Polydatin (PD), a natural stilbenoid compound derived from ''Polygonum cuspidatum'', shows pronouncedly curative effect on oxidative damage. In this work, the protective effects of PD on oxidative damage induced by Cd in ''Musca domestica'' (housefly) larvae were evaluated. The larvae were exposed to Cd and/or PD, subsequently, the oxidative stress status, mitochondria activity, oxidative phosphorylation efficiency, and survival rate were assessed. Cd exposure generated significant increases of malondialdehyde (MDA), reactive oxygen species (ROS) and 8-hydroxy-2-deoxyguanosine (8-oxoG) in the housefly larvae, causing mitochondrial dysfunction and survival rate decline. Interestingly, pretreatment with PD exhibited obviously mitochondrial protective effects in the Cd-exposed larvae, as evidenced by reduced MDA, ROS and 8-oxoG levels, and increased activities of superoxide dismutase (SOD), mitochondrial electron transfer chain, and mitochondrial membrane potential, as well as respiratory control ratio. These results suggested that PD could attenuate Cd-induced damage via maintaining redox balance, stimulating SOD activity, and regulating mitochondria activity in housefly larvae. As a natural polyphenolic chemical, PD can act as a potential candidate compounds to relieve Cd injury.Copyright © 2020 Elsevier Ltd. All rights reserved. 2020 Elsevier Ltd. All rights reserved.)
Wright 2013 Abstract MiP2013 + (Calcium (Ca2+) is an important intracellul … Calcium (Ca2+) is an important intracellular signalling molecule in mammalian tissues, and has been associated with the regulation of diverse processes, including contraction, secretion, autophagy, ion pumping, and the activation of metabolic enzymes. Mitochondria maintain a calcium gradient between the matrix and the cytoplasm, via the actions of specific transporters in the inner mitochondrial membrane. Under conditions of metabolic dysfunction (such as insulin resistance), mitochondrial calcium homeostasis is often altered (for a recent review, see [1]).With the recent identification of the mitochondrial calcium uniporter (MCU) and associated regulatory proteins, as well as the use of targeted aequorin probes, we are now able to investigate the role of mitochondrial Ca2+ in the regulation of whole-cell adipocyte metabolism [2,3]. Preliminary data suggest that the induction of insulin resistance (by treatment with 100 nM insulin for 24 h) in cultured adipocytes alters the expression of key components of the uniporter (+75% MCUa and +42% MCUb compared to control, P<0.05), and increases Ca2+ uptake into the mitochondria (+76%, P<0.05). Similarly, feeding mice a high-fat-high-sugar diet alters the expression of these genes in visceral white adipose tissue (+54% MCUa and +127% MCUb compared to chow-fed control, P<0.05). Additionally, we saw that direct manipulation of mitochondrial calcium by overexpression of MCUb in cultured adipocytes was able to alter a number of metabolic parameters, including mitochondrial membrane potential, NADH dynamics, and the rate of glucose oxidation. The mechanism and significance of these metabolic alterations is currently under investigation.We theorise that mitochondrial calcium plays an important role in the orchestration of metabolic homeostasis in adipocytes. As such, the MCU may represent an interesting node of metabolic regulation - and therefore therapeutic potential - in times of metabolic dysregulation.ic potential - in times of metabolic dysregulation.)
Vilas-Boas 2023 J Biol Chem + (Calcium (Ca2+) is a … Calcium (Ca2+) is a key regulator in diverse intracellular signaling pathways, and has long been implicated in metabolic control and mitochondrial function. Mitochondria can actively take up large amounts of Ca2+, thereby acting as important intracellular Ca2+ buffers and affecting cytosolic Ca2+ transients. Excessive mitochondrial matrix Ca2+ is known to be deleterious due to opening of the mitochondrial permeability transition pore (mPTP) and consequent membrane potential dissipation, leading to mitochondrial swelling, rupture, and cell death. Moderate Ca2+ within the organelle, on the other hand, can directly or indirectly activate mitochondrial matrix enzymes, possibly impacting on ATP production. Here, we aimed to determine in a quantitative manner if extra or intramitochondrial Ca2+ modulate oxidative phosphorylation in mouse liver mitochondria and intact hepatocyte cell lines. To do so, we monitored the effects of more modest versus supra-physiological increases in cytosolic and mitochondrial Ca2+ on oxygen consumption rates. Isolated mitochondria present increased respiratory control ratios (a measure of oxidative phosphorylation efficiency) when incubated with low (2.4 ± 0.6 μM) and medium (22.0 ± 2.4 μM) Ca2+ concentrations in the presence of complex I-linked substrates pyruvate plus malate and α-ketoglutarate, respectively, but not complex II-linked succinate. In intact cells, both low and high cytosolic Ca2+ led to decreased respiratory rates, while ideal rates were present under physiological conditions. High Ca2+ decreased mitochondrial respiration in a substrate-dependent manner, mediated by mPTP. Overall, our results uncover a Goldilocks effect of Ca2+ on liver mitochondria, with specific "just right" concentrations that activate oxidative phosphorylation. Overall, our results uncover a Goldilocks effect of Ca2+ on liver mitochondria, with specific "just right" concentrations that activate oxidative phosphorylation.)
Clapham 2007 Cell + (Calcium ions (Ca(2+)) impact nearly every … Calcium ions (Ca(2+)) impact nearly every aspect of cellular life. This review examines the principles of Ca(2+) signaling, from changes in protein conformations driven by Ca(2+) to the mechanisms that control Ca(2+) levels in the cytoplasm and organelles. Also discussed is the highly localized nature of Ca(2+)-mediated signal transduction and its specific roles in excitability, exocytosis, motility, apoptosis, and transcription.s, motility, apoptosis, and transcription.)
Giorgi 2018 Nat Rev Mol Cell Biol + (Calcium ions (Ca2+) are some of the most v … Calcium ions (Ca2+) are some of the most versatile signalling molecules, and they have many physiological functions, prominently including muscle contraction, neuronal excitability, cell migration and cell growth. By sequestering and releasing Ca2+, mitochondria serve as important regulators of cellular Ca2+. Mitochondrial Ca2+ also has other important functions, such as regulation of mitochondrial metabolism, ATP production and cell death. In recent years, identification of the molecular machinery regulating mitochondrial Ca2+ accumulation and efflux has expanded the number of (patho)physiological conditions that rely on mitochondrial Ca2+ homeostasis. Thus, expanding the understanding of the mechanisms of mitochondrial Ca2+ regulation and function in different cell types is an important task in biomedical research, which offers the possibility of targeting mitochondrial Ca2+ machinery for the treatment of several disorders.ry for the treatment of several disorders.)
Endlicher 2018 Cesk Fysiol + (Calcium ions play an important role in cel … Calcium ions play an important role in cell metabolism regulation. Mitochondrial permeability transition pore (MPTP) has recently attracted considerable attention. Short, reversible opening of this pore protects cells from oxidative damage, but its long lasting, irreversible opening induces the processes leading to cell death. A wide variety of substances was successfully proven to influence MPTP function either positively or negatively, however the molecular structure of this membrane pore remains unclear. This work summarizes up to date knowledge of MPTP function and regulation, efforts to elucidate molecular structure of the pore and finally we provide a review of diseases with MPTP involved in pathogenesis.seases with MPTP involved in pathogenesis.)
Glancy 2013 Biochemistry + (Calcium is believed to regulate mitochondr … Calcium is believed to regulate mitochondrial oxidative phosphorylation, thereby contributing to the maintenance of cellular energy homeostasis. Skeletal muscle, with an energy conversion dynamic range of up to 100-fold, is an extreme case for evaluating the cellular balance of ATP production and consumption. This study examined the role of Ca(2+) in the entire oxidative phosphorylation reaction network in isolated skeletal muscle mitochondria and attempted to extrapolate these results back to the muscle, ''in vivo''. Kinetic analysis was conducted to evaluate the dose-response effect of Ca(2+) on the maximal velocity of oxidative phosphorylation (VmaxO) and the ADP affinity. Force-flow analysis evaluated the interplay between energetic driving forces and flux to determine the conductance, or effective activity, of individual steps within oxidative phosphorylation. Measured driving forces [extramitochondrial phosphorylation potential (ΔGATP), membrane potential, and redox states of NADH and cytochromes bH, bL, c1, c, and a,a3] were compared with flux (oxygen consumption) at 37 °C; 840 nM Ca(2+) generated an ∼2-fold increase in VmaxO with no change in ADP affinity (∼43 μM). Force-flow analysis revealed that Ca(2+) activation of VmaxO was distributed throughout the oxidative phosphorylation reaction sequence. Specifically, Ca(2+) increased the conductance of Complex IV (2.3-fold), Complexes I and III (2.2-fold), ATP production/transport (2.4-fold), and fuel transport/dehydrogenases (1.7-fold). These data support the notion that Ca(2+) activates the entire muscle oxidative phosphorylation cascade, while extrapolation of these data to the exercising muscle predicts a significant role of Ca(2+) in maintaining cellular energy homeostasis.n maintaining cellular energy homeostasis.)
Young 2021 J Biol Chem + (Calcium signaling is essential for regulat … Calcium signaling is essential for regulating many biological processes. Endoplasmic reticulum (ER) inositol trisphosphate receptors (IP3R) and the mitochondrial Ca2+ uniporter (MCU) are key proteins that regulate intracellular Ca2+ concentration. Mitochondrial Ca2+ accumulation activates Ca2+-sensitive dehydrogenases of the tricarboxylic acid (TCA) cycle that maintain the biosynthetic and bioenergetics needs of both normal and cancer cells. However, the interplay between calcium signaling and metabolism is not well understood. In this study, we used human cancer cell lines (HEK293, HeLa) with stable knockouts of all three IP3R isoforms (TKO) or MCU to examine metabolic and bioenergetic responses to the chronic loss of cytosolic and/or mitochondrial Ca2+ signaling. Our results show that TKO cells (exhibiting total loss of Ca2+ signaling) are viable, displaying a lower proliferation and oxygen consumption rate, with no significant changes in ATP levels, even when made to rely solely on the TCA cycle for energy production. MCU KO cells also maintained normal ATP levels, but showed increased proliferation, oxygen consumption, and metabolism of both glucose and glutamine. However, MCU KO cells were unable to maintain ATP levels and died when relying solely on the TCA cycle for energy. We conclude that constitutive Ca2+ signaling is dispensable for the bioenergetic needs of both IP3R TKO and MCU KO human cancer cells, likely due to adequate basal glycolytic and TCA cycle flux. However, in MCU KO cells, the higher energy expenditure associated with increased proliferation and oxygen consumption makes these cells more prone to bioenergetic failure under conditions of metabolic stress.roliferation and oxygen consumption makes these cells more prone to bioenergetic failure under conditions of metabolic stress.)
Moon 2016 J Biol Chem + (Calcium-independent phospholipase A2γ (iPL … Calcium-independent phospholipase A2γ (iPLA2γ) is a mitochondrial enzyme that produces lipid second messengers that facilitate opening of the mitochondrial permeability transition pore (mPTP) and contribute to the production of oxidized fatty acids in myocardium. To specifically identify the roles of iPLA2γ in cardiac myocytes, we generated cardiac myocyte-specific iPLA2γ knock-out (CMiPLA2γKO) mice by removing the exon encoding the active site serine (Ser-477). Hearts of CMiPLA2γKO mice exhibited normal hemodynamic function, glycerophospholipid molecular species composition, and normal rates of mitochondrial respiration and ATP production. In contrast, CMiPLA2γKO mice demonstrated attenuated Ca(2+)-induced mPTP opening that could be rapidly restored by the addition of palmitate and substantially reduced production of oxidized polyunsaturated fatty acids (PUFAs). Furthermore, myocardial ischemia/reperfusion (I/R) in CMiPLA2γKO mice (30 min of ischemia followed by 30 min of reperfusion ''in vivo'') dramatically decreased oxidized fatty acid production in the ischemic border zones. Moreover, CMiPLA2γKO mice subjected to 30 min of ischemia followed by 24 h of reperfusion ''in vivo'' developed substantially less cardiac necrosis in the area-at-risk in comparison with their WT littermates. Furthermore, we found that membrane depolarization in murine heart mitochondria was sensitized to Ca(2+) by the presence of oxidized PUFAs. Because mitochondrial membrane depolarization and calcium are known to activate iPLA2γ, these results are consistent with salvage of myocardium after I/R by iPLA2γ loss of function through decreasing mPTP opening, diminishing production of proinflammatory oxidized fatty acids, and attenuating the deleterious effects of abrupt increases in calcium ion on membrane potential during reperfusion.© 2016 by The American Society for Biochemistry and Molecular Biology, Inc.r Biochemistry and Molecular Biology, Inc.)
Chen 2015 Am J Physiol Endocrinol Metab + (Caloric restriction (CR) attenuates age-re … Caloric restriction (CR) attenuates age-related muscle loss. However, the underlying mechanism responsible for this attenuation is not fully understood. This study evaluated the role of energy metabolism in the CR-induced attenuation of muscle loss. The aims of this study were twofold: 1) to evaluate the effect of CR on energy metabolism and determine its relationship with muscle mass, and 2) to determine whether the effects of CR are age dependent. Young and middle-aged rats were randomized into either 40% CR or ''ad libitum'' (AL) diet groups for 14 wk. Major energy-producing pathways in muscles, i.e., glycolysis and mitochondrial oxidative phosphorylation (OXPHOS), were examined. We found that the effects of CR were age dependent. CR improved muscle metabolism and normalized muscle mass in middle-aged animals but not young animals. CR decreased glycolysis and increased the cellular dependency for OXPHOS vs. glycolysis in muscles of middle-aged rats, which was associated with the improvement of normalized muscle mass. The metabolic reprogramming induced by CR was related to modulation of pyruvate metabolism and increased mitochondrial biogenesis. Compared with animals fed AL, middle-aged animals with CR had lower lactate dehydrogenase A content and greater mitochondrial pyruvate carrier content. Markers of mitochondrial biogenesis, including AMPK activation levels and SIRT1 and COX-IV content, also showed increased levels. In conclusion, 14 wk of CR improved muscle metabolism and preserved muscle mass in middle-aged animals but not in young developing animals. CR-attenuated age-related muscle loss is associated with reprogramming of the metabolic pathway from glycolysis to OXPHOS.tabolic pathway from glycolysis to OXPHOS.)
Niemann 2022 Biology (Basel) + (Caloric restriction (CR) extends lifespan … Caloric restriction (CR) extends lifespan in many species, including mammals. CR is cardioprotective in senescent myocardium by correcting pre-existing mitochondrial dysfunction and apoptotic activation. Furthermore, it confers cardioprotection against acute ischemia-reperfusion injury. Here, we investigated the role of AMP-activated protein kinase (AMPK) in mediating the cardioprotective CR effects in failing, postinfarct myocardium.Ligation of the left coronary artery or sham operation was performed in rats and mice. Four weeks after surgery, left ventricular (LV) function was analyzed by echocardiography, and animals were assigned to different feeding groups (control diet or 40% CR, 8 weeks) as matched pairs. The role of AMPK was investigated with an AMPK inhibitor in rats or the use of alpha 2 AMPK knock-out mice.CR resulted in a significant improvement in LV function, compared to postinfarct animals receiving control diet in both species. The improvement in LV function was accompanied by a reduction in serum BNP, decrease in LV proapoptotic activation, and increase in mitochondrial biogenesis in the LV. Inhibition or loss of AMPK prevented most of these changes.The failing, postischemic heart is protected from progressive loss of LV systolic function by CR. AMPK activation is indispensable for these protective effects.ndispensable for these protective effects.)
Boutant 2016 Cell Rep + (Caloric restriction (CR) has been shown to … Caloric restriction (CR) has been shown to prevent the onset of insulin resistance and to delay age-related physiological decline in mammalian organisms. SIRT1, a NAD(+)-dependent deacetylase enzyme, has been suggested to mediate the adaptive responses to CR, leading to the speculation that SIRT1 activation could be therapeutically used as a CR-mimetic strategy. Here, we used a mouse model of moderate SIRT1 overexpression to test whether SIRT1 gain of function could mimic or boost the metabolic benefits induced by every-other-day feeding (EODF). Our results indicate that SIRT1 transgenesis does not affect the ability of EODF to decrease adiposity and improve insulin sensitivity. Transcriptomic analyses revealed that SIRT1 transgenesis and EODF promote very distinct adaptations in individual tissues, some of which can even be metabolically opposite, as in brown adipose tissue. Therefore, whereas SIRT1 overexpression and CR both improve glucose metabolism and insulin sensitivity, the etiologies of these benefits are largely different.Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.shed by Elsevier Inc. All rights reserved.)
Johnson 2016 Diabetes + (Caloric restriction (CR) improves insulin … Caloric restriction (CR) improves insulin sensitivity and reduces the incidence of diabetes in obese individuals. The underlying mechanisms whereby CR improves insulin sensitivity are not clear. We evaluated the effect of 16 weeks of CR on whole-body insulin sensitivity by pancreatic clamp before and after CR in 11 obese participants (BMI = 35 kg/m(2)) compared with 9 matched control subjects (BMI = 34 kg/m(2)). Compared with the control subjects, CR increased the glucose infusion rate needed to maintain euglycemia during hyperinsulinemia, indicating enhancement of peripheral insulin sensitivity. This improvement in insulin sensitivity was not accompanied by changes in skeletal muscle mitochondrial oxidative capacity or oxidant emissions, nor were there changes in skeletal muscle ceramide, diacylglycerol, or amino acid metabolite levels. However, CR lowered insulin-stimulated thioredoxin-interacting protein (TXNIP) levels and enhanced nonoxidative glucose disposal. These results support a role for TXNIP in mediating the improvement in peripheral insulin sensitivity after CR.n peripheral insulin sensitivity after CR.)
Serna 2020 J Bioenerg Biomembr + (Caloric restriction (CR) is widely known t … Caloric restriction (CR) is widely known to increase life span and resistance to different types of injuries in several organisms. We have previously shown that mitochondria from livers or brains of CR animals exhibit higher calcium uptake rates and lower sensitivity to calcium-induced mitochondrial permeability transition (mPT), an event related to the resilient phenotype exhibited by these organs. Given the importance of calcium in metabolic control and cell homeostasis, we aimed here to uncover possible changes in mitochondrial calcium handling, redox balance and bioenergetics in cardiac and skeletal muscle mitochondria in response to six months of CR. Unexpectedly, we found that CR does not alter the susceptibility to mPT in muscle (cardiac or skeletal), nor calcium uptake rates. Despite the lack in changes in calcium transport properties, CR consistently decreased respiration in the presence of ATP synthesis in heart and soleus muscle. In heart, such changes were accompanied by a decrease in respiration in the absence of ATP synthesis, lower maximal respiratory rates and a reduced rate of hydrogen peroxide release. Hydrogen peroxide release was unaltered by CR in skeletal muscle. No changes were observed in inner membrane potentials and respiratory control ratios. Together, these results highlight the tissue-specific bioenergetic and ion transport effects induced by CR, demonstrating that resilience against calcium-induced mPT is not present in all tissues.induced mPT is not present in all tissues.)
Lanza 2012 Cell Metab + (Caloric restriction (CR) mitigates many de … Caloric restriction (CR) mitigates many detrimental effects of aging and prolongs life span. CR has been suggested to increase mitochondrial biogenesis, thereby attenuating age-related declines in mitochondrial function, a concept that is challenged by recent studies. Here we show that lifelong CR in mice prevents age-related loss of mitochondrial oxidative capacity and efficiency, measured in isolated mitochondria and permeabilized muscle fibers. We find that these beneficial effects of CR occur without increasing mitochondrial abundance. Whole-genome expression profiling and large-scale proteomic surveys revealed expression patterns inconsistent with increased mitochondrial biogenesis, which is further supported by lower mitochondrial protein synthesis with CR. We find that CR decreases oxidant emission, increases antioxidant scavenging, and minimizes oxidative damage to DNA and protein. These results demonstrate that CR preserves mitochondrial function by protecting the integrity and function of existing cellular components rather than by increasing mitochondrial biogenesis.Copyright © 2012 Elsevier Inc. All rights reserved. © 2012 Elsevier Inc. All rights reserved.)
Menezes-Filho 2017 Free Radic Biol Med + (Caloric restriction (CR) promotes lifespan … Caloric restriction (CR) promotes lifespan extension and protects against many pathological conditions, including ischemia/reperfusion injury to the brain, heart and kidney. In the liver, ischemia/reperfusion damage is related to excessive mitochondrial Ca2+ accumulation, leading to the mitochondrial permeability transition. Indeed, liver mitochondria isolated from animals maintained on CR for 4 months were protected against permeability transition and capable of taking up Ca2+ at faster rates and in larger quantities. These changes were not related to modifications in mitochondrial respiratory activity, but rather to a higher proportion of ATP relative to ADP in CR liver mitochondria. Accordingly, both depletion of mitochondrial adenine nucleotides and loading mitochondria with exogenous ATP abolished the differences between CR and ad libitum (AL) fed groups. The prevention against permeability transition promoted by CR strongly protected against ''in vivo'' liver damage induced by ischemia/reperfusion. Overall, our results show that CR strongly protects the liver against ischemia/reperfusion and uncover a mechanism for this protection, through a yet undescribed diet-induced change in liver mitochondrial Ca2+ handling related to elevated intramitochondrial ATP.Copyright © 2017 Elsevier Inc. All rights reserved.d intramitochondrial ATP. Copyright © 2017 Elsevier Inc. All rights reserved.)
Amigo 2016 Aging Cell + (Caloric restriction (CR) protects against … Caloric restriction (CR) protects against many cerebral pathological conditions that are associated with excitotoxic damage and calcium overload, although the mechanisms are still poorly understood. Here we show that CR strongly protects against excitotoxic insults ''in vitro'' and ''in vivo'' in a manner associated with significant changes in mitochondrial function. CR increases electron transport chain activity, enhances antioxidant defenses, and favors mitochondrial calcium retention capacity in the brain. These changes are accompanied by a decrease in cyclophilin D activity and acetylation and an increase in Sirt3 expression. This suggests that Sirt3-mediated deacetylation and inhibition of cyclophilin D in CR promote the inhibition of mitochondrial permeability transition, resulting in enhanced mitochondrial calcium retention. Altogether, our results indicate that enhanced mitochondrial calcium retention capacity underlies the beneficial effects of CR against excitotoxic conditions. This protection may explain the many beneficial effects of CR in the aging brain.© 2016 The Authors. Aging Cell published by the Anatomical Society and John Wiley & Sons Ltd.tomical Society and John Wiley & Sons Ltd.)
Wang 2023 Nature + (Caloric restriction that promotes weight l … Caloric restriction that promotes weight loss is an effective strategy for treating non-alcoholic fatty liver disease and improving insulin sensitivity in people with type 2 diabetes1. Despite its effectiveness, in most individuals, weight loss is usually not maintained partly due to physiological adaptations that suppress energy expenditure, a process known as adaptive thermogenesis, the mechanistic underpinnings of which are unclear2,3. Treatment of rodents fed a high-fat diet with recombinant growth differentiating factor 15 (GDF15) reduces obesity and improves glycaemic control through glial-cell-derived neurotrophic factor family receptor α-like (GFRAL)-dependent suppression of food intake4-7. Here we find that, in addition to suppressing appetite, GDF15 counteracts compensatory reductions in energy expenditure, eliciting greater weight loss and reductions in non-alcoholic fatty liver disease (NAFLD) compared to caloric restriction alone. This effect of GDF15 to maintain energy expenditure during calorie restriction requires a GFRAL-β-adrenergic-dependent signalling axis that increases fatty acid oxidation and calcium futile cycling in the skeletal muscle of mice. These data indicate that therapeutic targeting of the GDF15-GFRAL pathway may be useful for maintaining energy expenditure in skeletal muscle during caloric restriction. maintaining energy expenditure in skeletal muscle during caloric restriction.)
Pardo 2018 FASEB J + (Calorie restriction (CR) exerts remarkable … Calorie restriction (CR) exerts remarkable, beneficial effects on glucose homeostasis by mechanisms that are not fully understood. Given the relevance of white adipose tissue (WAT) in glucose homeostasis, we aimed at identifying the main cellular processes regulated in WAT in response to CR in a pathologic context of obesity. For this, a gene-expression profiling study was first conducted in mice fed ''ad libitum'' or subjected to 40% CR. We found that the gene network related to mitochondria was the most highly upregulated in WAT by CR. To study the role that increased mitochondrial biogenesis plays on glucose homeostasis following CR, we generated a mouse model devoid of the coactivators peroxisome proliferator-activated receptor gamma coactivator 1 (PGC-1)α and PGC-1β specifically in adipocytes. Our results show that mice lacking PGC-1s in adipocytes are unable to increase mitochondrial biogenesis in WAT upon CR. Despite a blunted induction of mitochondrial biogenesis in response to calorie deprivation, mice lacking adipose PGC-1s still respond to CR by improving their glucose homeostasis. Our study demonstrates that PGC-1 coactivators are major regulators of CR-induced mitochondrial biogenesis in WAT and that increased mitochondrial biogenesis and oxidative function in adipose tissue are not required for the improvement of glucose homeostasis mediated by CR.ent of glucose homeostasis mediated by CR.)
Gnaiger 1990 Biochim Biophys Acta + (Calorimetric and respirometric studies of … Calorimetric and respirometric studies of cultured cells show that both neoplastic and non-neoplastic cell types maintain an anaerobic contribution to their total heat flux. In many mammalian cells this can be explained quantitatively by lactate production observed under fully aerobic conditions. Uncoupling and enhanced futile substrate cycling increase the ratio of heat flux to oxygen flux, the calorimetric-respirometric (CR) ratio. The interpretation of calorimetric and respirometric measurements requires an energy balance approach in which experimentally measured CR ratios are compared with thermochemically derived oxycaloric equivalents. The oxycaloric equivalent is the enthalpy change per mole of oxygen consumed, and equals −470 kJ / mol O2 in the aerobic catabolism of glucose, assuming that catabolism is 100% dissipative (the net efficiency of metabolic heat transformation is zero). CR ratios more negative than −470 kJ / mol O2 have been reported in well-oxygenated cell cultures and are discussed in terms of integrated aerobic and anaerobic metabolism.discussed in terms of integrated aerobic and anaerobic metabolism.)
Targeting Mitochondrial Dysfunction & Toxicity 2015 + (Cambridge Healthtech Institute, Cambridge MA, USA; [http://www.healthtech.com/mitochondrial-targeting Targeting Mitochondrial Dysfunction & Toxicity - Treating Disease and Improving Drug Safety].)
Lin 2020 EBioMedicine + (Canagliflozin (CANA) administration increa … Canagliflozin (CANA) administration increases the risk of lower limb amputation in the clinic. The present study aimed to investigate whether and how CANA interferes with the intracellular physiological processes of bone marrow derived mesenchymal stem cells (BM-MSCs) and its contribution to ischaemic lower limb.The ''in vivo'' blood flow recovery in ischaemic lower limbs following CANA treatment was evaluated. The cellular function of BM-MSCs after CANA treatment were also assessed ''in vitro''. ''In silico'' docking analysis and mutant substitution assay were conducted to confirm the interaction of CANA with glutamate dehydrogenase 1 (GDH1).Following CANA treatment, attenuated angiogenesis and hampered blood flow recovery in the ischaemic region were detected in diabetic and non-diabetic mice, and inhibition of the proliferation and migration of BM-MSCs were also observed. CANA was involved in mitochondrial respiratory malfunction in BM-MSCs and the inhibition of ATP production, cytochrome c release and vessel endothelial growth factor A (VEGFA) secretion, which may contribute to reductions in the tissue repair capacity of BM-MSCs. The detrimental effects of CANA on MSCs result from the inhibition of GDH1 by CANA (evidenced by ''in silico'' docking analysis and H199A-GDH1/N392A-GDH1 mutant substitution).Our work highlights that the inhibition of GDH1 activity by CANA interferes with the metabolic activity of the mitochondria, and this interference deteriorates the retention of and VEGFA secretion by MSCs.Copyright © 2020 The Authors. Published by Elsevier B.V. All rights reserved.ed by Elsevier B.V. All rights reserved.)
Hawley 2016 Diabetes + (Canagliflozin, dapagliflozin, and empaglif … Canagliflozin, dapagliflozin, and empagliflozin, all recently approved for treatment of type 2 diabetes, were derived from the natural product phlorizin. They reduce hyperglycemia by inhibiting glucose reuptake by sodium/glucose cotransporter (SGLT) 2 in the kidney, without affecting intestinal glucose uptake by SGLT1. We now report that canagliflozin also activates AMPK, an effect also seen with phloretin (the aglycone breakdown product of phlorizin), but not to any significant extent with dapagliflozin, empagliflozin, or phlorizin. AMPK activation occurred at canagliflozin concentrations measured in human plasma in clinical trials and was caused by inhibition of Complex I of the respiratory chain, leading to increases in cellular AMP or ADP. Although canagliflozin also inhibited cellular glucose uptake independently of SGLT2, this did not account for AMPK activation. Canagliflozin also inhibited lipid synthesis, an effect that was absent in AMPK knockout cells and that required phosphorylation of acetyl-CoA carboxylase (ACC) 1 and/or ACC2 at the AMPK sites. Oral administration of canagliflozin activated AMPK in mouse liver, although not in muscle, adipose tissue, or spleen. Because phosphorylation of ACC by AMPK is known to lower liver lipid content, these data suggest a potential additional benefit of canagliflozin therapy compared with other SGLT2 inhibitors.© 2016 by the American Diabetes Association.2016 by the American Diabetes Association.)
Abcam 2018 Cambridge UK + (Cancer and Metabolism conference, Cambridge, United Kingdom, 2018)
Kunz 2020 J Biol Chem + (Cancer cachexia is characterized by reduct … Cancer cachexia is characterized by reductions in peripheral lean muscle mass. Prior studies have primarily focused on increased protein breakdown as the driver of cancer-associated muscle wasting. Therapeutic interventions targeting catabolic pathways have, however, largely failed to preserve muscle mass in cachexia, suggesting that other mechanisms might be involved. In pursuit of novel pathways, we used untargeted metabolomics to search for metabolite signatures that may be linked with muscle atrophy. We injected seven-week old C57/BL6 mice with LLC1 tumor cells or vehicle. After 21 days, tumor-bearing mice exhibited reduced body and muscle mass and impaired grip strength compared to controls, which was accompanied by lower synthesis rates of mixed muscle protein and the myofibrillar and sarcoplasmic muscle fractions. Reductions in protein synthesis were accompanied by mitochondrial enlargement and reduced coupling efficiency in tumor-bearing mice. To generate mechanistic insights into impaired protein synthesis, we performed untargeted metabolomic analyses of plasma and muscle and found increased concentrations of two methylarginines, asymmetric dimethylarginine (ADMA) and NG-monomethyl-L-arginine, in tumor-bearing mice compared to control mice. Compared to healthy controls, human cancer patients were also found to have higher levels of ADMA in the skeletal muscle. Treatment of C2C12 myotubes with ADMA impaired protein synthesis and reduced mitochondrial protein quality. These results suggest that increased levels of ADMA and mitochondrial changes may contribute to impaired muscle protein synthesis in cancer cachexia and could point to novel therapeutic targets by which to mitigate cancer cachexia.gets by which to mitigate cancer cachexia.)
Plecita-Hlavata 2015 J Bioenerg Biomembr + (Cancer cell bioenergetics, maintaining mix … Cancer cell bioenergetics, maintaining mixed aerobic glycolysis (Warburg phenotype) and oxidative phosphorylation (OXPHOS), is not fully elucidated. Hypoxia-dependent OXPHOS suppression determines aerobic glycolysis. To elucidate further details, we studied hypoxic adaptation (up to 72 h at 5% oxygen) of hepatocellular carcinoma HepG2 cells. The key regulatory component, hypoxia-inducible factor (HIF)-1α (HIF-1α) was stabilized at 5 h in 5% oxygen for all three studied regimens, i.e. in glycolytic cells at 5 mM or 25 mM glucose, or in aglycemic (OXPHOS) cells when glucose was replaced by galactose. However, the conventional HIF-mediated suppression of respiration was prevented at aglycemia, which correlated with a high proportion of unphosphorylated pyruvate dehydrogenase (PDH) at 5% oxygen. Such a modified HIF response in OXPHOS cells, termed as a non-canonical one, contrasted to conventional respiration suppression down to 45% or 43%, observed in hypoxia-adapted glycolytic cells at 5 mM or 25 mM glucose, respectively. These hypoxic glycolytic cells had normally highly phosphorylated PDH and most likely utilized pyruvate by aminotransferase reaction of glutaminolysis to feed at least suppressed respiration. Also, glycolytic cells were rather resistant towards the staurosporine-induced apoptosis, whereas aglycemic (OXPHOS) HepG2 cells exhibited much higher susceptibility. We conclude that aglycemia modulates the hypoxic HIF signaling toward a non-canonical response that is unable to carry out complete PDH phosphorylation, allowing a high pyruvate input for OXPHOS from the elevated glycolysis, which together with ongoing glutaminolysis maintain a virtually unchanged respiration. Similar OXPHOS revival may explain distinct tumor sensitivity to chemotherapy and other pharmacological interventions.y and other pharmacological interventions.)
De Sales 2018 Molecules + (Cancer cells demand high ATP provisions to … Cancer cells demand high ATP provisions to support proliferation, and targeting of energy metabolism is a good strategy to increase their sensitivity to treatments. In Brazil, wine manufacture is expanding, increasing the amount of pomace that is produced. We determined the phenolic composition and antioxidant properties of a dark skin Grape Pomace Extract and its effects on metabolism and redox state in human hepatocarcinoma HepG2 cells. The material and the methods used represented the industrial process since pomace derived from white wine production and the extract concentrated by pilot plant scale reverse osmosis. Grape pomace extract was rich in polyphenols, mainly anthocyanins, and presented high antioxidant capacity. Short-term metabolic effects, irrespective of any cytotoxicity, involved increased mitochondrial respiration and antioxidant capacity and decreased glycolytic metabolism. Long-term incubation was cytotoxic and cells died by necrosis and GPE was not toxic to non-cancer human fibroblasts. To the best of our knowledge, this is the first report to characterize pomace extract from white wine production from Brazilian winemaking regarding its effects on energy metabolism, suggesting its potential use for pharmaceutical and nutraceutical purposes.pharmaceutical and nutraceutical purposes.)
Bastian 2016 Cancer Lett + (Cancer cells have a unique metabolic profi … Cancer cells have a unique metabolic profile and mitochondria have been shown to play an important role in chemoresistance, tumor progression and metastases. This unique profile can be exploited by mitochondrial-targeted anticancer therapies. A small anticancer molecule, AG311, was previously shown to possess anticancer and antimetastatic activity in two cancer mouse models and to induce mitochondrial depolarization. This study defines the molecular effects of AG311 on the mitochondria to elucidate its observed efficacy. AG311 was found to competitively inhibit complex I activity at the ubiquinone-binding site. Complex I as a target for AG311 was further established by measuring oxygen consumption rate in tumor tissue isolated from AG311-treated mice. Cotreatment of cells and animals with AG311 and dichloroacetate, a pyruvate dehydrogenase kinase inhibitor that increases oxidative metabolism, resulted in synergistic cell kill and reduced tumor growth. The inhibition of mitochondrial oxygen consumption by AG311 was found to reduce HIF-1α stabilization by increasing oxygen tension in hypoxic conditions. Taken together, these results suggest that AG311 at least partially mediates its antitumor effect through inhibition of complex I, which could be exploited in its use as an anticancer agent.Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.Elsevier Ireland Ltd. All rights reserved.)