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《调查者摘要》) 这一建议是：1)长期饮酒损害溶酶体 防止溶酶体水解酶的加工和运输的生物发生， 导致它们被放置在其他胞内或胞外位置；2) 乙醇通过以下途径改变泛素-蛋白酶体途径 使蛋白酶体失活可能导致修饰后的 蛋白质。乙醇可能对库普弗蛋白酶体产生不同的影响 细胞。在具体目标1中，溶酶体的生物发生将通过检查 组织蛋白酶L的加工和区划 从对照组和乙醇喂养的大鼠分离出肝细胞。这种酶跟随着 通过囊泡间隔到达溶酶体的一种特殊途径 而调查员的目标1是确定这个步骤(S) 乙醇损害了这一过程，因为组织蛋白L等人的错误路线 由于水解酶的效力，可能会导致细胞损伤。 水解力。在特定的目标1b中，他们将检查乙醇 通过影响甘露糖-6-磷酸受体的分布 亚细胞分级、免疫细胞化学和功能分析研究。 该受体通过靶向组织蛋白酶L等介导溶酶体组装 水解酶作用于溶酶体。调查人员推测，乙醇可能 改变其在细胞内的分布以及对其配体的亲和力 Proathepsin L.在特定目标2中， 泛素-蛋白酶体途径将在整个肝脏以及 对照组和酒精喂养大鼠的实质细胞和枯否细胞 自由进食和胃内进食。这种非溶酶体 蛋白分解途径在以下几个方面起着至关重要的作用：1)改变的降解 蛋白质；以及2)转录因子NFkappaB的激活，它 启动炎症和免疫相关基因的转录 回应。研究人员推测，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 在Kupffer细胞中不同，因为它们在 酒精性肝病的发病机制。