Abstract 14773: Ischemic Preconditioning Induces Rapid Changes In Oxidative Phosphorylation Proteins And Attenuates Protein Oxidation During Ischemia-reperfusion By Mechanisms Independent Of Cytosolic Signaling.
Ischemic preconditioning (IP) cannot be applied to patients with unexpected ischemia, but understanding its mechanisms could lead to the development of new cardioprotective strategies. In this study we used high-throughput quantitative differential mitochondrial proteomics to get insight into the ultimate molecular mechanisms responsible for preconditioning protection.
Methods and Results: Mitochondria were isolated from rat hearts submitted to 2 cycles of 5min ischemia and 5min of reperfusion (IP) or control perfusion in a Langendorff apparatus. High-throughput proteomics analysis by 16O/18O labeling and mass spectrometry allowed differential quantitation of more than 400 proteins (from which more than 95% were mitochondrial), but only 10 proteins were found to be differentially increased (FDR <5%) by IP treatment. However, system biology analysis using a novel statistical model, where mitochondrial proteins were integrated into ontological categories, revealed a statistically significant and internally consistent increase in the group of oxidative phosphorylation (OxPhos) proteins. In a series of experiments of ischemia/reperfusion in which ischemia was limited to 20min to avoid cell death (no LDH release), complex I and complex II-mediated respiration was significantly depressed upon reperfusion and proteomic analysis demonstrated a selective reduction in OxPhos proteins. All these changes were attenuated by IP. A novel redox high-throughput proteomic analysis of mitochondria obtained from these sub-lethal experiments, revealed an increase in the abundance of peptides containing oxidized cysteine residues, which was abolished when hearts were previously submitted to IP. Furthermore, the changes in abundance of Oxphos proteins induced by IP were reproduced in vitro, when simulated ischemia was achieved by oxygen exhaustion from isolated respiring mitochondria (15min, pH 6.7) and subsequently reoxygenated for additional 5min in an oxygen chamber.
Conclusion: IP causes immediate changes in OxPhos mitochondrial proteins and attenuates protein oxidation during subsequent ischemia/reperfusion by mechanisms independent of cytosolic signaling.
- © 2011 by American Heart Association, Inc.