Comparative proteomics of myocardial mitochondrial proteins in aging rats

AIM:To identify the proteins related to aging in the mitochondria of the heart. METHODS:Mitochondria were isolated from the hearts of adult (10-week) and old (12-month) rats (n=3). Total proteins extracted from the mitochondria were applied to the two-dimensional gel electrophoresis. The differentially expressed protein spots evaluated by a software were subjected to in-gel digestion, and analyzed by the matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS). ATP content in the heart was also measured. RESULTS:Eighty-four differentially expressed protein spots were observed, and fifteen of them were analyzed by MALDI-TOF- MS. Four proteins including creatine kinase, peroxiredoxin 2, Tu translation elongation factor and isocitrate dehydrogenase were up-regulated and 11 proteins including succinate dehydrogenase, malate dehydrogenase, aconitate hydratase, NADH dehydrogenase, ATP synthase H+ transporting, ATP synthase beta chain, heat shock protein 60, glucose-regulated protein 78, prohibitin, Aldehyde dehydrogenase 2 and voltage-dependent anion channel exhibited down-regulation in the aging group compared to the adult one. ATP content in the heart of old rats was significantly reduced as compared to that in adult rats (n=5, P<0.01). CONCLUSION:Significant changes in the mitochondrial protein expression in the aging heart were identified by the 2-DE electrophoretogram with high resolution and reproducibility. The functions of these identified proteins need to be further investigated.