Proteomic analysis of mitochondrial proteins in a mouse model of type 2 diabetes

Objective: Impaired mitochondrial function may contribute to the onset of contractile dysfunction with insulin resistance/type 2 diabetes. Our aim was therefore to determine alterations in the mitochondrial proteome of a mouse model of obesity/type 2 diabetes. Methods: Mitochondrial proteins were isolated from hearts collected from 18- to 20-week-old female db/db mice and compared to matched controls. We performed two-dimensional polyacrylamide gel electrophoresis to determine differentially expressed proteins. Peptides of interest were further analysed by mass spectrometry and Mascot software was employed to identify protein matches. Results: Our data showed that ATP synthase D chain, ubiquinol cytochrome-C reductase core protein 1 and electron transfer flavoprotein subunit alpha peptide levels were altered with obesity. Moreover, we found coordinate down-regulation of contractile proteins in the obese heart, i.e. alpha-smooth muscle actin, alpha-cardiac actin, myosin heavy-chain alpha and myosin-binding protein C. Conclusion: We propose that decreased contractile protein levels may contribute to contractile dysfunction of hearts from diabetic mice.