Proteomic analysis of mitochondrial proteins in cardiomyocytes from chronic stressed rat

Chronic restraint stress induces cardiac dysfunction as well as cardiomyocyte injury including severe ultrastructural alteration and cell death, but its mechanism and molecular basis remain unclear. Mitochondria play a key role in regulating cell life. For exploring mitochondrial proteins which correlate with stress-induced injury, two-dimensional electrophoresis and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS) were applied. After comparing the protein profiles of myocardial mitochondria between a chronic restraint stress group and a control group, 11 protein spots were found altered, seven of which were identified by MALDI-TOF MS. Among the seven proteins, five proteins involved in the Krebs cycle and lipid metabolism in mitochondria decreased after chronic restraint stress. They were identified as carnitine palmitoyltransferase 2, mitochondrial acyl-CoA thioesterase 1, isocitrate dehydrogenase 3 (NAD+) alpha, fumarate hydratase 1 and pyruvate dehydrogenase beta. The last two proteins, creatine kinase and prohibitin, increased after chronic restraint stress. Biochemical tests for energy metabolism in mitochondria also supported the proteomic results. These findings provide clues for understanding the mechanism of dysfunction or injury in cardiomyocytes induced by chronic stress.