Investigation of early proteomic changes in liver affected by non-alcoholic steatohepatitis

The increasing number of obesity in western society is a major cause for higher incidence of metabolic aberrations as insulin resistance and non-alcoholic fatty liver disease (NAFLD). Non-alcoholic steatohepatitis (NASH) is the most severe form of NAFLD, characterized by liver steatosis and inflammation leading to a significant deterioration in liver function, possibly culminating in liver cirrhosis. However, the exact mechanism of NASH development is still unclear.An established mouse model system for NASH is used to assess the early changes in hepatic protein regulation. Wild-type mice are fed with a high-fat diet facilitating the development of adipositas and NASH. Proteomic changes in different compartments of murine liver cells are investigated in a time course. The analyses of protein-related changes are accomplished by means of two-dimensional differential gel electrophoresis (DIGE), followed by protein identification using liquid chromatography-mass spectrometry. In a complementary approach, changes in protein abundances are quantified by a shotgun approach using stable-istotope labelling. Furthermore, results will be confirmed using functional assays. The grade of steatosis was determined by histological examination. During the course of time, a microvesicular steatosis with mild inflammatory infiltration was confirmed. The degree of inflammation and fibrosis was assessed by quantitative real-time-PCR of relevant marker genes. The liver proteome was examined for differentially regulated proteins by DIGE. An upregulation of various proteins involved in lipid metabolism as well as primary energy metabolism could be shown. Also, various proteins participating in one carbon metabolism were shown to be regulated in early disease progression. For several proteins, a graduated regulation over the experimental course was observed.

metabolomics - mouse model - non-alcoholic steatohepatitis - proteomics