Time-dependent hepatic proteome analysis in lean and diet-induced obese mice.

C57BL/6J mice have been widely used as a diet-induced obesity model because they trigger common features of the human metabolic syndrome. In the present study, C57BL/6J male mice were fed either a high-fat diet (HFD) or normal diet (ND) during a 24-week period, and then the age-dependent liver proteome of mice in two groups was analyzed using 2-DE combined with MALDI-TOF-MS. Among identified proteins, up-regulated proteins were subdivided to early (during the first 4 weeks) and late (20~24 weeks) markers that played a role in diet-induced obesity development. Important early markers included ketohexokinase and prohibitin, and late markers included the 75 kDa glucose-regulated protein, citrate synthase, and selenium-binding liver protein. Of these, the 75 kDa glucoseregulated protein has already been linked to obesity; however, prohibitin protein involved in obesity was identified for the first time in this study. In order to validate the proteomic results and gain insight into metabolic changes between the two groups, we further confirmed the expression pattern of some proteins of interest by Western blot analysis. Combined results of proteomic analysis with Western blot analysis revealed that antioxidant enzymes were progressively decreased, whereas cytoskeletal proteins were time-dependently increased in HFD mice.