Differential roles of GSK-3? during myocardial ischemia and ischemia/reperfusion.

ABSTRACT: Inhibition of glycogen synthase kinase-3 (GSK-3) protects the heart during ischemia/reperfusion (I/R), yet the underlying mechanisms of cardioprotection afforded by beta isoform-specific inhibition GSK-3 remain to be elucidated.We studied the molecular mechanism mediating the effect of GSK-3? activation/inhibition upon myocardial injury during prolonged ischemia and I/R.Beta isoform-specific inhibition of GSK-3 by dominant negative GSK-3? in transgenic mice (Tg-DnGSK-3?) or in heterozygous GSK-3? knock-out mice (GSK-3?+/-) significantly increased, whereas activation of GSK-3? in constitutively active GSK-3? knock-in mice (?KI) significantly decreased, myocardial ischemic injury after prolonged ischemia. In contrast, inhibition of GSK-3? in Tg-DnGSK-3? or GSK-3?+/- significantly reduced, while activation of GSK-3? in ?KI significantly enhanced, myocardial I/R injury. Inhibition of GSK-3? stimulated mTOR signaling and inhibited autophagy through a rapamycin-sensitive (mTOR dependent) mechanism. Rapamycin enhanced autophagy and, at the same time, abolished the effects of GSK-3? inhibition on both prolonged ischemic injury and I/R injury. Importantly, the influence of rapamycin over the effects of GSK-3? inhibition on myocardial injury was reversed by inhibition of autophagy.Our results suggest that beta isoform-specific inhibition of GSK-3 exacerbates ischemic injury but protects against I/R injury by modulating mTOR and autophagy.

SUBMITTER: Zhai P 

PROVIDER: S-EPMC3158807 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature