Guerra-Alvarez 2015 J Neurochem

Guerra-Álvarez M, Moreno-Ortega AJ, Navarro E, Fernández-Morales JC, Egea J, López MG, Cano-Abad MF (2015) Positive allosteric modulation of alpha-7 nicotinic receptors promotes cell death by inducing Ca²⁺ release from the endoplasmic reticulum. J Neurochem 133:309-19.

» PMID: 25650007

Guerra-Alvarez M, Moreno-Ortega AJ, Navarro E, Fernandez-Morales JC, Egea J, Lopez MG, Cano-Abad MF (2015) J Neurochem

Abstract: Positive allosteric modulation of α7 isoform of nicotinic acetylcholine receptors (α7-nAChRs) is emerging as a promising therapeutic approach for central nervous system disorders such as schizophrenia or Alzheimer's disease. However, its effect on Ca²⁺ signaling and cell viability remains controversial. This study focuses on how the type II positive allosteric modulator (PAM II) PNU120596 affects intracellular Ca²⁺ signaling and cell viability. We used human SH-SY5Y neuroblastoma cells overexpressing α7-nAChRs (α7-SH) and their control (C-SH). We monitored cytoplasmic and endoplasmic reticulum (ER) Ca²⁺ with Fura-2 and the genetically encoded cameleon targeting the ER, respectively. Nicotinic inward currents were measured using patch-clamp techniques. Viability was assessed using methylthiazolyl blue tetrazolium bromide or propidium iodide staining. We observed that in the presence of a nicotinic agonist, PNU120596 (i) reduced viability of α7-SH but not of C-SH cells; (ii) significantly increased inward nicotinic currents and cytosolic Ca²⁺ concentration; (iii) released Ca²⁺ from the ER by a Ca²⁺ -induced Ca²⁺ release mechanism only in α7-SH cells; (iv) was cytotoxic in rat organotypic hippocampal slice cultures; and, lastly, all these effects were prevented by selective blockade of α7-nAChRs, ryanodine receptors, or IP3 receptors. In conclusion, positive allosteric modulation of α7-nAChRs with the PAM II PNU120596 can lead to dysregulation of ER Ca²⁺ , overloading of intracellular Ca²⁺ , and neuronal cell death. This study focuses on how the type II positive allosteric modulator PNU120596 (PAM II PNU12) affects intracellular Ca²⁺ signaling and cell viability. Using SH-SY5Y neuroblastoma cells overexpressing α7-nAChRs (α7-SH) and their control (C-SH), we find that PAM of α7-nAChRs with PNU120596: (i) increases inward calcium current (ICa ) and cytosolic Ca²⁺ concentration ([Ca²⁺ ]cyt ); (ii) releases Ca²⁺ from the ER ([Ca²⁺]ER ) by a Ca²⁺ -induced Ca²⁺ release mechanism; and (iv) reduces cell viability. These findings were corroborated in rat hippocampal organotypic cultures. [Ca²⁺]cyt , cytosolic Ca²⁺ concentration; [Ca²⁺]ER , endoplasmic reticulum Ca²⁺ concentration; α7 nAChR, α7 isoform of nicotinic acetylcholine receptors; α7-SH, SH-SY5Y stably overexpressing α7 nAChRs cells; C-SH, control SH-SY5Y cells; Nic, nicotine; PNU12, PNU120596.

Labels: Pathology: Alzheimer's

Organism: Human, Rat Tissue;cell: Nervous system