Role of Sumoylation in Alcoholic Liver Disease

苏酰化在酒精性肝病中的作用

• 批准号: 9043309
• 负责人: Maria Lauda Tomasi
• 金额: $ 15.67万
• 依托单位: CEDARS-SINAI MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-20 至 2018-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9043309
• 关键词: Role; Sumoylation; Alcoholic; Liver; Disease

DESCRIPTION (provided by applicant): Alcohol abuse is a leading factor in mortality from liver disease and increases the risk for a wide range of adverse health effects. The liver, as the primary site of alcohol metabolism, is a major target of injury. The spectrum of Alcoholic Liver Diseases (ALD) includes simple steatosis, alcoholic hepatitis, fibrosis, cirrhosis, and hepatocellular carcinoma. Sumoylation is a post-translational modification that modulates multiple cellular processes such as signal transduction, stress responses, cellular trafficking, protein-protein interactions, protein-DNA interactions and transcriptional activity. SUMO is comprised of four distinct proteins in humans (SUMO-1, -2, 3- and -4). Sumoylation is often increased under oxidative stress. We recently reported that ubiquitin conjugating enzyme 9 (Ubc9), the sole E2 enzyme of sumoylation, is induced in intragastric ethanol- infusion (EI) treated mice but the functional significance of this is unknown. Consistently, we found SUMO-1, -3 and Ubc9 mRNA levels are increased the livers of EI mice. Also, EI mice show an overall increase in protein sumoylation by SUMO-1 but only minor changes in sumoylation by SUMO-2/3. Ethanol treatment of primary mouse hepatocytes leads to increased reactive oxygen species (ROS) and triglyceride production. In addition, we found increased expression of Ubc9 and SUMO genes, Cyp2e1 and an overall increase in SUMO-1 protein sumoylation like in EI livers. Silencing of Ubc9 prevented ethanol-induced fat accumulation, ROS production and increased Cyp2e1 expression in primary mouse hepatocytes. In LX-2 cells (activated human hepatic stellate cells or HSCs), ethanol treatment also increased Ubc9 expression, ROS production and HSC activation markers. Blocking Ubc9 induction prevented all of these and induced apoptosis in HSCs. Finally, we found that lipopolysaccharide (LPS) and Ubc9 RNAi treatment alone increased expression of proinflammatory cytokines in RAW cells (macrophage cell line); but when LPS and Ubc9 RNAi were combined, the expression of these cytokines increased further. Interestingly, LPS treatment decreased Ubc9 protein level (mRNA level was unchanged). This proposal is testing the novel hypothesis that there is dysregulation in sumoylation that contributes to the pathogenesis of ALD in a cell-type specific manner. Three specific aims are proposed to examine: 1) the role of sumoylation in ethanol-induced changes in hepatocytes, 2) the role of sumoylation in ethanol-induced HSC activation, and 3) the role of sumoylation in Kupffer cell activation in ALD. If successfully completed, these studies should provide highly novel information on the role of sumoylation in the development of ALD and may provide novel therapeutic strategies, which is of high public health priority.

描述（由申请人提供）：酗酒是肝病死亡的一个主要因素，并增加了各种不良健康影响的风险。肝脏作为酒精代谢的主要场所，是主要的损伤目标。酒精性肝病 (ALD) 包括单纯性脂肪变性、酒精性肝炎、纤维化、肝硬化和肝细胞癌。 Sumoylation 是一种翻译后修饰，可调节多种细胞过程，例如信号转导、应激反应、细胞运输、蛋白质-蛋白质相互作用、蛋白质-DNA 相互作用和转录活性。 SUMO 由人类的四种不同蛋白质（SUMO-1、-2、3- 和 -4）组成。氧化应激下苏酰化通常会增加。我们最近报道，泛素结合酶 9 (Ubc9)（唯一的苏酰化 E2 酶）在胃内乙醇输注 (EI) 处理的小鼠中被诱导，但其功能意义尚不清楚。一致地，我们发现 EI 小鼠肝脏中 SUMO-1、-3 和 Ubc9 mRNA 水平增加。此外，EI 小鼠显示 SUMO-1 的蛋白质苏酰化总体增加，但 SUMO-2/3 的苏酰化仅发生微小变化。原代小鼠肝细胞的乙醇处理导致活性氧（ROS）和甘油三酯的产生增加。此外，我们发现 Ubc9 和 SUMO 基因、Cyp2e1 的表达增加，并且 SUMO-1 蛋白苏酰化整体增加，就像在 EI 肝脏中一样。 Ubc9 的沉默可防止乙醇诱导的脂肪积累、ROS 产生以及原代小鼠肝细胞中 Cyp2e1 表达的增加。在 LX-2 细胞（激活的人肝星状细胞或 HSC）中，乙醇处理还增加了 Ubc9 表达、ROS 产生和 HSC 激活标记物。阻断 Ubc9 诱导可阻止所有这些并诱导 HSC 凋亡。最后，我们发现单独使用脂多糖（LPS）和 Ubc9 RNAi 治疗可增加 RAW 细胞（巨噬细胞系）中促炎细胞因子的表达；但当LPS和Ubc9 RNAi联合使用时，这些细胞因子的表达进一步增加。有趣的是，LPS 处理降低了 Ubc9 蛋白水平（mRNA 水平未改变）。该提案正在测试新的假设，即 sumoylation 的失调以细胞类型特异性的方式导致 ALD 的发病机制。提出了三个具体目标来检查：1）苏酰化在乙醇诱导的肝细胞变化中的作用，2）苏酰化在乙醇诱导的 HSC 激活中的作用，3）苏酰化在 ALD 中库普弗细胞激活中的作用。如果成功完成，这些研究应提供关于苏酰化在 ALD 发展中的作用的高度新颖的信息，并可能提供新颖的治疗策略，这是公共卫生的高度优先事项。