Alcohol-Induced Regulation of Hepatic Protein Synthesis

酒精诱导的肝蛋白质合成调节

• 批准号: 7034004
• 负责人: THOMAS C VARY
• 金额: $ 17.4万
• 依托单位: PENNSYLVANIA STATE UNIV HERSHEY MED CTR
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7034004
• 关键词: acetaldehyde; acetates; alcoholic beverage consumption; alcoholism /alcohol abuse; amides; animal tissue; butanols; enzyme activity; ethanol; fungal proteins; genetically modified animals; laboratory mouse; liver function; liver metabolism; messenger RNA; pathologic process; phosphorylation; posttranslational modifications; protein biosynthesis; protein kinase; protein structure function; pyrazoles; translation factor

DESCRIPTION (provided by applicant): Alcohol consumption results in damage to multiple organs, especially liver. An early effect of alcohol intoxication is the inhibition of hepatic protein synthesis. However the underlying mechanisms responsible for the inhibition are not known. Liver has 1 of the highest protein synthetic rates in the body and hepatic proteins are critically important for whole body metabolism of drugs, fat, amino acids, and glucose. Therefore, ameliorating the alcohol-induced defect in hepatic protein synthesis could have wide reaching consequences beyond alcoholic liver disease. The long-term goal of these studies is to elucidate the mechanism underlying the alcohol-induced decreases in hepatic protein synthesis in order to devise ways to reverse the defect. Preliminary data indicates that alcohol causes a defect in the formation of the 43S preinitiation complex [controlled by eukaryotic initiation factor 2 (elF2) and elF2B]; through phosphorylation of the a-subunit of elF2 at Ser51. Ethanol or its metabolites may cause a selective activation of 1 of the known elF2 kinases (PERK, GCN2, PKR or HRI) or inhibit elF2a phosphatase activity. Our hypothesis is that ethanol or its metabolites cause selective activation of 1 or more of the 4 kinases responsible for phosphorylation of elF2a and/or inhibition of phosphatase, and that augmented phosphorylation of elF2a affects the translation of mRNA into protein following acute ethanol intoxication. Using mice as a model system will allow us to manipulate the genome to genetically oblate the kinases involved in elF2 phosphorylation to determine the effect of alcohol intoxication following knockout of elF2 kinases. 2 specific aims are proposed to test this hypothesis and elucidate the mechanisms underlying this defect in hepatic protein synthesis using pharmacological, biochemical, physiological, and transgenic approaches. Specific Aim 1 will examine the effects of inhibitors of ethanol metabolism, individual ethanol metabolites or derived components on elF2a phosphorylation to establish if the effects of ethanol to increase phosphorylation of elF2a require its metabolism. Specific Aim 2 will determine which of the elF2 kinases are responsible for the increased phosphorylation of elF2 following acute alcohol intoxication, using mice strains genetically engineered to be deficient in individual and multiple elF2 kinases. In addition, we will examine the potential role of decreased phosphatase activity as a means to increase phosphorylation of elF2a. This exploratory R21 proposal deals with a new direction in the alcohol field and offers the promise of providing mechanism(s) into ethanol effects on translational control and ethanol-induced cellular damage in liver.

描述（由申请人提供）：饮酒会导致多个器官受损，尤其是肝脏。酒精中毒的早期影响是抑制肝脏蛋白质合成。然而，导致抑制的潜在机制尚不清楚。肝脏是体内蛋白质合成率最高的区域之一，肝脏蛋白质对于药物、脂肪、氨基酸和葡萄糖的全身代谢至关重要。因此，改善酒精引起的肝脏蛋白质合成缺陷可能会产生除酒精性肝病之外的广泛影响。这些研究的长期目标是阐明酒精引起的肝蛋白质合成减少的机制，以便设计出扭转这种缺陷的方法。初步数据表明，酒精会导致43S前起始复合物的形成缺陷[由真核起始因子2（elF2）和elF2B控制]；通过 eF2 的 a 亚基 Ser51 磷酸化。乙醇或其代谢物可能导致 1 种已知 eF2 激酶（PERK、GCN2、PKR 或 HRI）选择性激活或抑制 eF2a 磷酸酶活性。我们的假设是，乙醇或其代谢物会选择性激活负责 eF2a 磷酸化和/或磷酸酶抑制的 4 种激酶中的 1 种或多种，​​并且 eF2a 磷酸化增强会影响急性乙醇中毒后 mRNA 翻译成蛋白质。使用小鼠作为模型系统将使我们能够操纵基因组，从基因上消除参与 eF2 磷酸化的激酶，以确定敲除 eF2 激酶后酒精中毒的影响。提出了 2 个具体目标来检验这一假设，并利用药理学、生化、生理学和转基因方法阐明肝蛋白质合成缺陷的机制。具体目标 1 将检查乙醇代谢抑制剂、单个乙醇代谢物或衍生成分对 eF2a 磷酸化的影响，以确定乙醇增加 eF2a 磷酸化的作用是否需要其代谢。具体目标 2 将使用经过基因改造缺乏单个和多个 eF2 激酶的小鼠品系，确定哪些 eF2 激酶导致急性酒精中毒后 eF2 磷酸化增加。此外，我们将研究降低磷酸酶活性作为增加 eF2a 磷酸化的手段的潜在作用。这一探索性 R21 提案涉及酒精领域的新方向，并有望为乙醇对肝脏翻译控制和乙醇诱导的细胞损伤的影响提供机制。