ETHANOL EFFECTS ON PROTEOLYTIC SYSTEMS IN THE LIVER

这项研究的中心假设是乙醇 消耗通过影响溶酶体抑制肝蛋白水解， 肝脏中的溶酶体外蛋白水解途径。 一种乙醇诱导的 蛋白质降解的抑制是主要因素之一 负责乙醇诱导的蛋白质在肝脏中的积累， 导致肝肿大的现象， 喝酒 我们在这些研究中的目的是检查两个关键的肝脏 大鼠肝脏中的蛋白水解系统，并确定它们在多大程度上 受急性和/或慢性乙醇给药的影响。 的制度 分析的是肝自噬/溶酶体系统和泛素 蛋白水解途径 这些通路负责完成 大多数细胞内蛋白质的降解。 破坏他们的 细胞内功能可导致肝细胞中其它紊乱 功能 本提案的具体目标是审查 急性和/或慢性乙醇消耗对1）形成和成熟 2）内源性蛋白水解活性， 以及HSP-70介导的肝溶酶体蛋白水解活性3） 肝脏泛素含量以及泛素依赖性结合， 大鼠肝提取物中的蛋白水解活性，以及4） 这些蛋白水解系统位于肝小叶的不同区域。 的 后一个目标将是重要的，在确定是否有任何关系 存在于乙醇诱导的肝蛋白水解减少和 乙醇引起的特异性细胞损伤。 我们的调查将利用最近更新的技术， 从对照组肝脏富集和分离自噬空泡 和乙醇喂养的大鼠。 我们将从形态学上分析这些空泡， 为了确定乙醇摄入是否会影响 这些细胞器的形成、成熟和蛋白水解能力。 我们 然后将评估乙醇消费的影响，以及 乙醇的初始氧化产物乙醛，对形成和 泛素-蛋白质缀合物的降解。 最后，我们将分析 蛋白质含量、蛋白质转化率以及 上述蛋白水解系统在分离的静脉周围和门静脉周围 来自对照和乙醇喂养大鼠的肝细胞。 由于肝脏负责调节血清蛋白，氨基 酸、脂质和葡萄糖水平，了解其影响很重要 酒精中毒或肝脏蛋白质代谢。

The central hypothesis of the proposed investigation is that ethanol consumption inhibits hepatic proteolysis by affecting the lysosomal and extralysosomal proteolytic pathways in the liver. An ethanol-elicited inhibition of protein degradation is one of the principal factors responsible for ethanol-induced protein accumulation in the liver, a phenomenon which contributes to hepatomegaly resulting from chronic drinking. Our aim in these investigations is to examine two key hepatic proteolytic systems in rat liver and to determine to what degree they are affected by acute and,/or chronic ethanol administration. The systems to be analyzed are the hepatic autophagic/lysosomal system and the ubiquitin proteolytic pathway. These pathways are responsible for the complete degradation of most intracellular proteins. Disruption of their intracellular function(s) may lead to other disturbances in liver cell function. The specific objectives of this proposal are to examine the effects of acute and/or chronic ethanol consumption on 1) The formation and maturation of hepatic autophagic vacuoles, 2) endogenous proteolytic activities as well as HSP-70-mediated proteolytic activities of liver lysosomes 3) the content of hepatic ubiquitin as well as ubiquitin dependent conjugation and proteolytic activities in rat liver extracts, and 4) the activities of these proteolytic systems in different zones of the hepatic lobule. The latter objective will be important in determining whether any relationship exists between the ethanol-induced reduction in hepatic proteolysis and ethanol-elicited specific cell injury. Our investigation will utilize recently updated techniques for the enrichment and isolation of autophagic vacuoles from the livers of control and ethanol-fed rats. We will analyze these vacuoles morphologically and biochemically in order to determine whether ethanol ingestion affects the formation, maturation and proteolytic capacities of these organelles. We will then assess the effects of ethanol consumption, as well as that of ethanol's initial oxidation product acetaldehyde, on the formation and the degradation of ubiquitin-protein conjugates. Finally, we will analyze the protein content, the rates of protein catabolism, as well as the aforementioned proteolytic systems in isolated perivenous and periportal hepatocytes from control and ethanol-fed rats. Since the liver is responsible for the regulation of serum protein, amino acid, lipid and glucose levels, it is important to understand the effects of ethanol toxicity or hepatic protein metabolism.