ETHANOL OXIDATION EFFECTS ON EGF SIGNAL TRANSDUCTION

乙醇氧化对 EGF 信号转导的影响

• 批准号: 2769205
• 负责人: Dahn Louis Clemens
• 金额: $ 8.34万
• 依托单位: UNIVERSITY OF NEBRASKA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-25 至 2002-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2769205
• 关键词: acetaldehyde; alcohol dehydrogenase; biological signal transduction; cell growth regulation; cell line; cellular pathology; epidermal growth factor; ethanol; hepatotoxin; liver cells; oxidation reduction reaction; receptor mediated endocytosis; toxin metabolism

DESCRIPTION: (Adapted from Investigator's Abstract) One of the more pronounced hepatic dysfunctions observed in animals chronically fed ethanol is a impairment in receptor-mediated endocytosis. Receptor-mediated endocytosis is responsible for the uptake and degradation of many biologically important molecules including hormones, growth factors and cytokines. Receptor-mediated endocytosis is also involved in the regulation of the expression of surface receptors and signal transduction. Thus, alterations in hepatic receptor-mediated endocytosis could be detrimental to the liver. Although, impairment in receptor-mediated endocytosis is well established in hepatocytes isolated from ethanol fed animals, the mechanism(s) of this impairment have yet to be elucidated. Furthermore, the direct involvement of ethanol metabolism in this defect has yet to be demonstrated. Many mechanisms for the hepatic cell injury associated with chronic ethanol abuse have been proposed. One attractive, though unproven mechanism, proposes that acetaldehyde forms acetaldehyde-protein adducts and through their accumulation eventually causes hepatic dysfunction. One of the main reasons that these underlying mechanisms of chronic ethanol oxidation have not been determined has been the lack of a stable in vitro hepatic model system for the study of chronic ethanol oxidation. The PI recently developed a cell line of hepatic origin that metabolized ethanol to acetaldehyde and produces acetaldehyde-protein adducts and proposes to use this cell line (HAD cells) to investigate impairments in epidermal growth factor signal transduction. The hypothesis is that alcohol dehydrogenase mediated oxidation of ethanol impairs the biological activities of the epidermal growth factor receptor. Inactivation of this receptor dramatically alters the ability of hepatocytes to respond appropriately to extracellular signals. Epidermal growth factor is an important hepatic mitogen. The binding of epidermal growth factor to its receptor activates an intrinsic tyrosine kinase, which initiates a signal transduction cascade resulting in cell proliferation. The Specific Aims of this proposal are: 1) Determine what processes of epidermal growth factor receptor-mediated endocytosis are impaired by ethanol oxidation and exposure to acetaldehyde; 2) Investigate the effect of ethanol oxidation on the signal transduction pathway of the epidermal growth factor receptor in the recombinant HAD cells; 3) Investigate the possibility that acetaldehyde-protein adducts are responsible for the observed ethanol induced impairment of the epidermal growth factor receptor; and 4) Investigate the effects of ethanol oxidation on the mitogenic activities of epidermal growth factor in the recombinant HAD cells. By completing these studies, it is hoped that the investigators can determine the effects of chronic ethanol oxidation and exposure to acetaldehyde on the signal transduction of epidermal growth factor, thus leading to a greater understanding of the mechanisms of induced liver injury.

描述：（改编自研究者摘要）其中之一 长期喂食乙醇的动物观察到明显的肝功能障碍 是受体介导的内吞作用的损伤。 受体介导 内吞作用负责许多物质的摄取和降解 生物学上重要的分子，包括激素、生长因子和 细胞因子。 受体介导的内吞作用也参与调节 表面受体的表达和信号转导。 因此， 肝受体介导的内吞作用的改变可能不利于 肝脏。 尽管受体介导的内吞作用受损是很好的 在从乙醇喂养的动物中分离出的肝细胞中建立的 这种损害的机制尚未阐明。 此外， 乙醇代谢是否直接参与该缺陷尚未得到证实 证明了。 与肝细胞损伤相关的多种机制 有人提出长期滥用乙醇。 一种有吸引力的，但未经证实的 机制，提出乙醛形成乙醛-蛋白质加合物，并且 它们的积累最终会导致肝功能障碍。 之一 慢性乙醇的这些潜在机制的主要原因 氧化尚未确定，一直缺乏稳定的体外 用于研究慢性乙醇氧化的肝模型系统。 PI 最近开发了一种肝源性细胞系，可以将乙醇代谢为 乙醛并产生乙醛-蛋白质加合物并建议使用 该细胞系（HAD 细胞）用于研究表皮生长损伤 因子信号转导。 假设乙醇脱氢酶 乙醇介导的氧化损害了生物活性 表皮生长因子受体。 该受体失活 显着改变肝细胞适当反应的能力 细胞外信号。 表皮生长因子是一种重要的肝细胞因子 有丝分裂原。 表皮生长因子与其受体的结合激活 一种内在的酪氨酸激酶，启动信号转导级联 从而导致细胞增殖。 该提案的具体目标是： 1）确定表皮生长因子受体介导的哪些过程 乙醇氧化和接触乙醛会损害内吞作用； 2) 研究乙醇氧化对信号转导的影响 重组HAD中表皮生长因子受体的通路 细胞； 3) 研究乙醛-蛋白质加合物的可能性 造成观察到的乙醇诱导的表皮损伤 生长因子受体； 4) 研究乙醇氧化的影响 重组人表皮生长因子促有丝分裂活性的研究 HAD细胞。 通过完成这些研究，希望研究人员 可以确定慢性乙醇氧化和暴露于乙醇的影响 乙醛对表皮生长因子信号转导的影响，因此 从而更好地了解诱导肝的机制 受伤。