RETINOID METABOLISM IN STELLATE CELLS

这是一份R21发展奖助金申请，用于支持一项国际合作计划（PA-96-033）。两位美国调查人员的合作。博斯隆（W. Bosron）和凯迪什维利（N. Kedishvili），以及两名意大利调查人员。A.卡西尼和A.加利已经建立。Drs。W. Bosron和N. Kedishvili在涉及类视黄醇代谢的脱氢酶和水解酶的表征方面具有专业知识。Drs。Casini和Galli在星状细胞的制备和培养以及与星状细胞激活相关的生化事件表征方面具有专长，这些生化事件导致酒精诱导的肝纤维化。本研究计划的总体目标是确定肝星状细胞激活形成肌成纤维细胞样细胞时视黄醇酯代谢的代谢途径。肝星状细胞是肝脏中维生素A的主要储存库。当动物长期暴露于酒精或其他肝毒素时，星状细胞被激活并转化为肌成纤维细胞样细胞。这些转化的细胞是酒精诱导的肝纤维化中胶原合成和细胞外基质形成的部位。星状细胞活化的最早事件之一是视黄醇棕榈酸酯的水解。在人、兔和大鼠肝脏中有多种视黄醇酯水解酶和视黄醇脱氢酶活性。然而，在肝星状细胞活化过程中参与视黄醇酯代谢的特定酶和基因尚未确定。具体目的是建立从大鼠、兔和/或人肝脏中制备星状细胞的方法，以鉴定在星状细胞活化过程中存在的视黄醇酯水解酶和视黄醇脱氢酶的同工酶。酶的激活将在细胞中测量。研究了棕榈酸视黄醇水解酶和视黄醇脱氢酶的催化性质和分子性质。这些研究应该为类视黄醇代谢在酒精性肝病中的作用提供新的信息。

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.