ETHANOL EFFECTS ON PROTEOLYTIC SYSTEMS IN THE LIVER

乙醇对肝脏蛋白水解系统的影响

• 批准号: 2682971
• 负责人: Terrence M. Donohue
• 金额: $ 20.1万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-08-01 至 2000-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2682971
• 关键词: alcoholic beverage consumption; carbohydrate receptor; detoxification; endopeptidases; ethanol; gene expression; immunocytochemistry; intracellular transport; laboratory rat; liver cells; liver metabolism; lysosomes; mannose 6 phosphate; membrane biogenesis; nuclear factor kappa beta; proteasome; protein metabolism; protein transport; proteolysis; ubiquitin

DESCRIPTION: (Adapted from the Investigator's Abstract) The hypotheses of this proposal are: 1) chronic ethanol consumption impairs lysosome biogenesis by preventing processing and trafficking of lysosomal hydrolases, causing their placement at other intracellular or extracellular sites; 2) ethanol administration alters the ubiquitin-proteasome pathway by inactivating the proteasome which could lead to accumulation of modified proteins. Ethanol may differentially influence the proteasome in Kupffer cells. In Specific Aim 1, lysosome biogenesis will be measured by examining the processing, and compartmentalization of the protease, cathepsin L in hepatocytes isolated from control and ethanol-fed rats. This enzyme follows a specific pathway through vesicular compartments en route to the lysosome and the investigator's Aim 1 is to determine the step(s) at which this process is impaired by ethanol, because misrouting of cathepsin L and other hydrolases could potentially cause cell damage due to their potent hydrolytic capacities. In Specific Aim 1b they will examine whether ethanol influences the distribution of the mannose-6-phosphate receptor by subcellular fractionation immunocytochemistry and functional assay studies. This receptor mediates lysosome assembly by targeting cathepsin L and other hydrolases to the lysosome. The investigators postulate that ethanol may change its intracellular distribution as well as its ligand affinity for procathepsin L. In Specific Aim 2, the components of the ubiquitin-proteasome pathway will be examined in whole livers as well as parenchymal and Kupffer cells of control and ethanol-fed rats subjected to both ad lib and intra gastric feeding regimens. This nonlysosomal proteolytic pathway has a crucial role in: 1) the degradation of altered proteins; and 2) the activation of the transcription factor NFkappaB which initiates transcription of genes involved in the inflammatory and immune responses. The investigators postulate that while ethanol may down-regulate the proteasome in liver parenchymal cells, its activity may be regulated differentially in Kupffer cells, since they play a paracrine role in the pathogenesis of alcoholic liver disease.

描述：（改编自研究者摘要） 这一建议是：1）慢性乙醇消耗损害溶酶体 通过阻止溶酶体水解酶的加工和运输， 导致它们在其他细胞内或细胞外位点的放置; 2） 乙醇给药改变了泛素-蛋白酶体途径， 使蛋白酶体失活，这可能导致修饰的 proteins. 乙醇对枯否细胞蛋白酶体的影响 细胞 在具体目标1中，溶酶体生物发生将通过检查 蛋白酶组织蛋白酶L的加工和区室化 从对照和乙醇喂养的大鼠分离的肝细胞。 这种酶遵循 通过囊泡隔室到达溶酶体的特定途径 研究者的目标1是确定这一点的步骤， 由于组织蛋白酶L和其他蛋白酶的错误路由， 水解酶由于其强大的生物活性， 水解能力 在具体目标1b中，他们将研究乙醇是否 影响甘露糖-6-磷酸受体的分布， 亚细胞分级免疫细胞化学和功能测定研究。 该受体通过靶向组织蛋白酶L和其他受体介导溶酶体组装。 水解酶到溶酶体。 研究人员假设乙醇可能 改变其细胞内分布以及其对 前组织蛋白酶在具体目标2中， 泛素-蛋白酶体途径将在整个肝脏中进行检查， 对照组和乙醇喂养大鼠的实质和枯否细胞， 自由进食和胃内进食方案。 这个非溶酶体的 蛋白水解途径在以下方面具有关键作用：1）改变的蛋白质的降解， 蛋白质;和2）转录因子NF κ B的激活， 启动参与炎症和免疫反应的基因的转录， 应答 研究人员假设，虽然乙醇可能会下调 肝实质细胞中的蛋白酶体，其活性可能受到调节 库普弗细胞中的差异，因为它们在细胞中起着旁分泌作用。 酒精性肝病的发病机制。