Abstract P277: Cardioprotection Enabled by Proteomic Remodeling of the Mitochondrial Respiratory Chain
The mitochondrial respiratory chain is a collection of five multi-protein complexes, whose unobstructed functionality represents a pivotal element at the crossroads of cell death or survival. However, its molecular composition and stochiometric information remains elusive and the adaptive abilities of the chain remain largely unknown.
We employed a quantitative proteomic approach to investigate the hypothesis that cardioprotection against ischemic injury is afforded by a salutary proteomic remodeling of the mitochondrial respiratory chain.
The respiratory chain of cardiac mitochondria isolated from wild type (WT) mice and from mice expressing a constitutively active protein kinase Cε (AE-PKCε) were characterized using 15N-stable isotope labeled murine models (SILAM), as well as a label-free method in conjunction with high resolution LC-MS/MS, respectively. Enzymatic function of electron transport chain and the ATP synthase were evaluated (n=7/group); and mitochondrial superoxide production was examined by ESR-spectroscopy (n=3/group).
Three novel and important observations are made: (i) five individual respiratory complexes exhibited a molar ratio of 1:1:1.4:1.2:4.5 in the WT-heart; (ii) subunits within the five complexes encoded by the mitochondrial genome were expressed at much lower abundance (p<0.05) than those encoded by the nuclear genome; and (iii) Genetic cardioprotection by AE-PKCε elicited a proteomic remodeling of complex I and III, mitochondria from AE-PKCε exhibited an increased expression of multiple subunits, including the catalytic complex III subunit Cyc1. This finding was accompanied by a preserved complex III activity (p<0.05), as well as tempered superoxide production (p<0.01) subsequent to Ca2+-induced damage.
This is the first study documenting a salutary proteomic remodeling of the mitochondrial respiratory machinery in cardioprotection. Quantitative proteomics technology enabled novel information and new insights into mitochondrial biology.
- © 2011 by American Heart Association, Inc.