This is an R21 developmental grant application to support a collaborative international project (PA-96-033). A collaboration between two United States investigators, Drs. W. Bosron and N. Kedishvili, with two Italian investigators, Drs. A. Casini and A. galli has been established. Drs. W. Bosron and N. Kedishvili have expertise in the characterization of dehydrogenases and hydrolases involved in retinoid metabolism. Drs. Casini and Galli have expertise in the preparation and culture of stellate cells and the characterization of biochemical events associated with stellate cell activation leading to alcohol-induced hepatic fibrosis. The overall goal of the research proposal is to identify the metabolic pathways of retinyl ester metabolism in hepatic stellate cells when they become activated to form myofibroblast-like cells. Hepatic stellate cells are the main reservoir of Vitamin A in liver. When animals are chronically exposed to alcohol or other hepatotoxins, the stellate cells become activated and transform into myofibroblast-like cells. These transformed cells are the sites of collagen synthesis and extracellular matrix formation in alcohol-induced hepatic fibrosis. One of the earliest events in stellate cell activation is the hydrolysis in retinyl palmitate esters. Multiple retinyl ester hydrolase and retinol dehydrogenase activities have been reported in human, rabbit and rat liver. However, the specific enzymes and genes involved in retinyl ester metabolism during the activation of hepatic stellate cells have not been identified.
The specific aims are to develop methods to prepare stellate cells from rat, rabbit and/or human liver to identify the isoenzymes of retinyl ester hydrolases and retinol dehydrogenases present during stellate cell activation. The enzyme activation will be measured in cells. The catalytic and molecular properties of the retinyl palmitate hydrolases and retinol dehydrogenases will be characterized. The studies should provide new information on the role of retinoid metabolism in alcohol-induced liver disease.
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|Sanghani, Sonal P; Davis, Wilhelmina I; Dumaual, Natividad G et al. (2002) Identification of microsomal rat liver carboxylesterases and their activity with retinyl palmitate. Eur J Biochem 269:4387-98|