Proteomic and metabolomic analysis of cardioprotection: Interplay between protein kinase C epsilon and delta in regulating glucose metabolism of murine hearts

We applied a combined proteomic and metabolomic approach to obtain novel mechanistic insights in PKC epsilon-mediated cardioprotection. Mitochondrial and cytosolic proteins from control and transgenic hearts with constitutively active or dominant negative PKC epsilon were analyzed using difference in-gel electrophoresis (DICE). Among the differentially expressed proteins were creatine kinase, pyruvate kinase, lactate clehydrogenase, and the cytosolic isoforms of aspartate amino transferase and malate dehydrogenase, the two enzymatic components of the malate aspartate shuttle, which are required for the import of reducing equivalents from glycolysis across the inner mitochondrial membrane. These enzymatic changes appeared to be dependent on PKC epsilon activity, as they were not observed in mice expressing inactive PKC epsilon. High-resolution proton nuclear magnetic resonance (H-1-NMR) spectroscopy confirmed a pronounced effect of PKC epsilon activity on cardiac glucose and energy metabolism: normoxic hearts with constitutively active PKC epsilon had significantly lower concentrations of glucose, lactate, glutamine and creatine, but higher levels of choline, glutamate and total adenosine nucleotides. Moreover, the depletion of cardiac energy metabolites was slower during ischemia/reperfusion injury and glucose metabolism recovered faster upon reperfusion in transgenic hearts with active PKC epsilon. Notably, inhibition of PKC epsilon resulted in compensatory phosphorylation and mitochondrial translocation of PKC delta. Taken together, our findings are the first evidence that PKC epsilon activity modulates cardiac glucose metabolism and provide a possible explanation for the synergistic effect of PKC delta and PKC epsilon in cardioprotection. (C) 2008 Elsevier Inc. All rights reserved.