%0 Journal Article
%T Mitochondria Express ¦Á7 Nicotinic Acetylcholine Receptors to Regulate Ca2+ Accumulation and Cytochrome c Release: Study on Isolated Mitochondria
%A Galyna Gergalova
%A Olena Lykhmus
%A Olena Kalashnyk
%A Lyudmyla Koval
%A Volodymyr Chernyshov
%A Elena Kryukova
%A Victor Tsetlin
%A Sergiy Komisarenko
%A Maryna Skok
%J PLOS ONE
%D 2012
%I Public Library of Science (PLoS)
%R 10.1371/journal.pone.0031361
%X Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels that mediate synaptic transmission in the muscle and autonomic ganglia and regulate transmitter release in the brain. The nAChRs composed of ¦Á7 subunits are also expressed in non-excitable cells to regulate cell survival and proliferation. Up to now, functional ¦Á7 nAChRs were found exclusively on the cell plasma membrane. Here we show that they are expressed in mitochondria and regulate early pro-apoptotic events like cytochrome c release. The binding of ¦Á7-specific antibody with mouse liver mitochondria was revealed by electron microscopy. Outer membranes of mitochondria from the wild-type and ¦Â2£¿/£¿ but not ¦Á7£¿/£¿ mice bound ¦Á7 nAChR-specific antibody and toxins: FITC-labeled ¦Á-cobratoxin or Alexa 555-labeled ¦Á-bungarotoxin. ¦Á7 nAChR agonists (1 ¦ÌM acetylcholine, 10 ¦ÌM choline or 30 nM PNU-282987) impaired intramitochondrial Ca2+ accumulation and significantly decreased cytochrome c release stimulated with either 90 ¦ÌM CaCl2 or 0.5 mM H2O2. ¦Á7-specific antagonist methyllicaconitine (50 nM) did not affect Ca2+ accumulation in mitochondria but attenuated the effects of agonists on cytochrome c release. Inhibitor of voltage-dependent anion channel (VDAC) 4,4¡ä-diisothio-cyano-2,2¡ä-stilbene disulfonic acid (0.5 ¦ÌM) decreased cytochrome c release stimulated with apoptogens similarly to ¦Á7 nAChR agonists, and VDAC was co-captured with the ¦Á7 nAChR from mitochondria outer membrane preparation in both direct and reverse sandwich ELISA. It is concluded that ¦Á7 nAChRs are expressed in mitochondria outer membrane to regulate the VDAC-mediated Ca2+ transport and mitochondrial permeability transition.
%U http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0031361