Proteomic analysis of mitochondrial proteins of basal and lipolytically (isoproterenol and TNF-alpha)-stimulated adipocytes.

The regulation of adipocyte lipolysis is increasingly believed to influence insulin resistance, in a process that may be associated with mitochondrial dysfunction. However, the molecular basis of the relationship between mitochondrial protein expression, lipolytic responsiveness, and insulin resistance remains unknown. A set of proteins that shows altered abundances in the mitochondria of untreated and treated 3T3-L1 adipocytes with TNF-alpha or isoproterenol was identified. These include the proteins associated with energy production, including fatty acid oxidation, TCA cycle, and oxidative phosphorylation. Proteins associated with oxidative stress dissipation were down-regulated in lipolytically stimulated adipocytes. Lipolytic stimulation with isoproterenol and TNF-alpha, which is also a potent proinflammatory cytokine, showed some noticeable differences in mitochondrial protein expression. For example, isoproterenol markedly enhanced the expression of prohibitin which is involved in the integrity of mitochondria but TNF-alpha did not. These results provide valuable information on mitochondrial dysfunction associated with oxidative stress induced by lipolytic stimulation.