Modulation of the mitochondrial permeability transition pore complex in GSK-3beta-mediated myocardial protection

J Mol Cell Cardiol. 2007 Nov;43(5):564-70. doi: 10.1016/j.yjmcc.2007.08.010. Epub 2007 Aug 23.

Abstract

Recently we found that the level of anti-infarct tolerance afforded by ischemic preconditioning (IPC) and erythropoietin (EPO) infusion was closely correlated with the level of Ser9-phospho-GSK-3beta upon reperfusion in the heart. To get an insight into the mechanism by which phospho-GSK-3beta protects the myocardium from ischemia/reperfusion injury, we examined the effects of IPC and EPO on interactions between GSK-3beta and subunits of the mitochondrial permeability transition pore (mPTP) in this study. Rat hearts were subjected to 25-min global ischemia and 5-min reperfusion in vitro with or without IPC plus EPO infusion (5 units/ml) before ischemia. Ventricular tissues were sampled before or after ischemia/reperfusion to separate subcellular fractions for immunoblotting and immunoprecipitation. Reperfusion increased mitochondrial GSK-3beta by 2-fold and increased phospho-GSK-3beta level in all fractions examined. Major subunits of mPTP, adenine nucleotide translocase (ANT) and voltage-dependent anion channel (VDAC), were co-immunoprecipitated with GSK-3beta after reperfusion. Phospho-GSK-3beta was co-immunoprecipitated with ANT but not with VDAC. IPC+EPO significantly increased the levels of GSK-3beta and phospho-GSK-3beta that were co-immunoprecipitated with ANT to 145+/-8% and 143+/-16%, respectively, of baseline but did not induce phospho-GSK-3beta-VDAC binding. A PKC inhibitor and a PI3 kinase inhibitor suppressed the IPC+EPO-induced increase in the level of phospho-GSK-3beta-ANT complex. The level of cyclophilin D co-immunoprecipitated with ANT after reperfusion was significantly reduced to 39+/-10% of the control by IPC+EPO. These results suggest that reduction in affinity of ANT to cyclophilin D by increased phospho-GSK-3beta binding to ANT may be responsible for suppression of mPTP opening and myocardial protection afforded by IPC+EPO.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Disease Models, Animal
  • Erythropoietin / pharmacology
  • Glycogen Synthase Kinase 3 / physiology*
  • Glycogen Synthase Kinase 3 beta
  • In Vitro Techniques
  • Intracellular Membranes / physiology*
  • Kinetics
  • Mitochondria, Heart / enzymology
  • Mitochondria, Heart / physiology*
  • Mitochondrial Membrane Transport Proteins / drug effects
  • Mitochondrial Membrane Transport Proteins / physiology*
  • Myocardial Ischemia / physiopathology
  • Phosphorylation
  • Rats
  • Rats, Sprague-Dawley
  • Reperfusion Injury / prevention & control
  • Ventricular Function

Substances

  • Mitochondrial Membrane Transport Proteins
  • mitochondrial permeability transition pore
  • Erythropoietin
  • Glycogen Synthase Kinase 3 beta
  • Gsk3b protein, rat
  • Glycogen Synthase Kinase 3