[摘要]：Despite compelling evidence supporting key roles for glycogen synthase kinase 3 beta (GSK3 beta), mitochondrial adenosine triphosphate-sensitive K+ (mitoK(ATP)) channels, and mitochondrial connexin 43 (Cx43) in cytoprotection, it is not clear how these signaling modules are linked mechanistically. By patch-clamping the inner membrane of murine cardiac mitochondria, we found that inhibition of GSK3 beta activated mitoK(ATP). PKC activation and protein phosphatase 2a inhibition increased the open probability of mitoK(ATP) channels through GSK3 beta, and this GSK3 beta signal was mediated via mitochondrial Cx43. Moreover, (i) PKC-induced phosphorylation of mitochondrial Cx43 was reduced in GSK3 beta-S9A mice; (ii) Cx43 and GSK3 beta proteins associated in mitochondria; and (iii) SB216763-mediated reduction of infarct size was abolished in Cx43 KO mice in vivo, consistent with the notion that GSK3 beta inhibition results in mitoK(ATP) opening via mitochondrial Cx43. We therefore directly targeted mitochondrial Cx43 by the Cx43 C-terminal binding peptide RRNYRRNY for cardioprotection, circumventing further upstream pathways. RRNYRRNY activated mitoK(ATP) channels via Cx43. We directly recorded mitochondrial Cx43 channels that were activated by RRNYRRNY and blocked by the Cx43 mimetic peptide (43)GAP27. RRNYRRNY rendered isolated cardiomyocytes in vitro and the heart in vivo resistant to ischemia/reperfusion injury, indicating that mitochondrial Cx43- and/or mitoK(ATP)-mediated reduction of infarct size was not undermined by RRNYRRNY-related opening of sarcolemmal Cx43 channels. Our results demonstrate that GSK3 beta transfers cytoprotective signaling through mitochondrial Cx43 onto mitoK(ATP) channels and that Cx43 functions as a channel in mitochondria, being an attractive target for drug treatment against cardiomyocyte injury.
