Effects of Ethanol on Proteasome-HCV Core Protein Interactions

描述（由申请人提供）：在HCV感染中，约70%的患者发生持续病毒血症和慢性感染过程。酒精滥用强烈加速HCV感染的进展。HCV结构蛋白之一，称为核心蛋白，诱导肝细胞中的氧化应激，并且这被乙醇进一步增强。氧化应激调节许多酶的功能，包括多催化蛋白质降解酶，蛋白酶体。这种酶降解氧化修饰的蛋白质、信号转导因子并加工用于抗原呈递的肽。我们推测HCV核心蛋白通过直接与酶相互作用和间接诱导低水平的氧化应激来增强蛋白酶体活性。然而，在乙醇暴露的肝细胞中，核心蛋白对蛋白酶体的激活被乙醇代谢阻断，从而抑制蛋白酶体活性。潜在地，蛋白酶体活性的这些变化可能影响蛋白质降解和用于抗原呈递的肽的产生。为了验证这一假设，我们提出了两个具体目标。目的1探讨HCV核心蛋白激活蛋白酶体的机制，并确定乙醇代谢是否阻断核心蛋白激活蛋白酶体。目的2将确定HCV核心蛋白是否影响HCV核心表达细胞和核心表达对照和乙醇喂养的转基因小鼠中的蛋白酶体活性和总体细胞内蛋白水解。这项研究的结果将有助于阐明酒精增强HCV进展的机制，提供蛋白酶体功能改变与HCV肽段加工之间的联系，以供受感染的肝细胞呈递。这项调查也将提供框架，为未来的HCV发病机制的研究，即蛋白酶体依赖的调节细胞因子信号和MHC I类限制性介绍HCV抗原的细胞毒性T淋巴细胞。乙醇代谢可抑制细胞因子信号转导和抗原呈递。Lay语言摘要：这项研究将扩大我们对丙型肝炎病毒蛋白和乙醇如何调节降解蛋白质的酶的机制的了解。这项研究的结果将部分解释为什么与不饮酒的患者相比，免疫系统在酒精患者中清除HCV的能力较低。我们设想这项研究将有潜在的治疗应用，有助于改善慢性丙型肝炎治疗和疫苗开发

DESCRIPTION (provided by applicant): In HCV infection, about 70% of patients develop persistent viremia and chronic course of infection. Alcohol abuse strongly accelerates the progression of HCV infection. One of HCV structural proteins, known as core protein, induces oxidative stress in liver cells, and this is further potentiated by ethanol. Oxidative stress modulates the functions of many enzymes, including the multi-catalytic protein-degrading enzyme, the proteasome. This enzyme degrades oxidatively modified proteins, signal transduction factors and processes peptides for antigen presentation. We hypothesize that HCV core protein enhances proteasome activity by directly interacting with the enzyme and indirectly, by inducing low levels of oxidative stress. However, in ethanol-exposed liver cells, proteasome activation by core protein is blocked by ethanol metabolism, which suppresses proteasome activity. Potentially, these changes in proteasome activity may affect protein degradation and generation of peptides for antigen presentation. To test this hypothesis, we propose two Specific Aims. Aim 1 will ascertain the mechanism(s) of proteasome activation by HCV core protein and determine whether ethanol metabolism blocks proteasome activation by core protein. Aim 2 will determine whether HCV core protein affects proteasome activity and overall intracellular proteolysis in HCV core-expressing cells and in core-expressing control and ethanol-fed transgenic mice. The results derived from this study will help clarify the mechanism of alcohol-potentiated HCV progression, providing a link between altered proteasome function and processing of HCV peptides for presentation by infected liver cells. This investigation will also provide the framework for future HCV pathogenetic studies, namely, proteasome-dependent regulation of cytokine signaling and MHC class I-resticted presentation of HCV antigens to cytotoxic T-lymphocytes. Both transduction of cytokine signals and antigen presentation can be suppressed by ethanol metabolism. Lay Language Summary: The proposed study will expand our knowledge in the mechanisms of how hepatitis C viral protein and ethanol regulate the enzyme, which degrades proteins. The results of this investigation will partially explain why the immune system is less able to clear HCV in alcoholic compared to in non-drinking patients. We envision that this research will potentially have therapeutic applications, helping to improve chronic hepatitis C treatment and vaccine development