Proteomics of Oxidant-Induced Mitochondrial Damage in an Animal Model of NASH

描述（由申请人提供）： 与肥胖和II型糖尿病相关的非酒精性脂肪性肝炎（NASH）正在成为慢性肝病最常见的病因之一。最近的证据支持NASH的“两次打击”假说，其中“第一次打击”涉及肝细胞中脂肪的积累，这是胰岛素抵抗的结果，随后是“第二次打击”，这需要线粒体功能障碍以及氧化和亚硝化应激。因此，假设该蛋白质在NASH的发展中起核心作用，其破坏能量代谢和过量氧化剂产生有助于病理学。氧化应激导致线粒体损伤的机制可能涉及线粒体蛋白的翻译后修饰。线粒体蛋白的氧化修饰将损害线粒体生物能量学，并导致氧化剂的进一步增加，这被认为在从单纯性脂肪肝到NASH的进展中起关键作用。NASH中线粒体这些变化的分子途径和靶点是未知的，也是本申请的焦点。阻碍阐明NASH的分子机制和靶向治疗的发展的一个因素是缺乏适当的实验动物模型。初步数据表明，给小鼠喂食高脂饮食再现了伴有线粒体功能障碍的NASH的关键组织病理学特征。基于这些观察，假设不能适应与肥胖相关的代谢改变导致线粒体氧化剂的过度产生，这导致蛋白质的翻译后修饰、线粒体功能受损和NASH。该探索性项目的第一个目的是表征和量化小鼠中响应高脂饮食的NASH和线粒体损伤的发展。该模型的使用将有助于未来的研究与转基因和/或基因敲除小鼠模型，以调查机制的保护，从代谢应激的肝线粒体。第二个目的是表征响应NASH的肝线粒体蛋白质组的翻译后修饰。使用新的蛋白质组学方法完成这些研究将能够鉴定NASH中代谢途径和/或蛋白质的分子缺陷，这些分子缺陷可以通过针对NASH的治疗和预防策略来靶向。公共卫生相关性（非专业描述）-研究报告称，世界上肥胖症的患病率正在上升。肥胖与严重的健康问题有关，包括心脏病和糖尿病，并被认为是发展慢性非酒精相关肝病的最常见危险因素。这项应用中的研究非常重要，因为它们将确定导致肥胖相关肝脏疾病的潜在因素，这将导致发现新的治疗方法。

DESCRIPTION (provided by applicant): Nonalcoholic steatohepatitis (NASH) associated with obesity and type II diabetes is emerging as one of the most common etiologies of chronic liver disease. Recent evidence supports a "two-hit" hypothesis for NASH with the "first-hit" involving the accumulation of fat in hepatocytes as a consequence of insulin resistance followed by the "second-hit", which entails mitochondrial dysfunction and oxidative and nitrosative stress. Thus, the mitochondrion is postulated to play a central role in the development of NASH with disrupted energy metabolism and excess oxidant production contributing to pathology. The mechanism by which oxidative stress leads to mitochondrial damage is likely to involve the post-translational modification of mitochondrial proteins. Oxidative modifications to mitochondrial proteins will impair mitochondrial bioenergetics and lead to further increases in oxidants, which are proposed to play a key role in the progression from simple fatty liver to NASH. The molecular pathways and targets that underlie these changes to mitochondria in NASH are unknown and the focus of this application. One factor that has hindered progress in elucidating the molecular mechanisms of NASH and development of targeted therapeutics is the lack of appropriate experimental animal models. Preliminary data indicate that feeding a high-fat diet to mice reproduces the key histopathologic features of NASH with mitochondrial dysfunction. Based on these observations it is hypothesized that the inability to adapt to the metabolic alterations associated with obesity results in the overproduction of mitochondrial oxidants, which leads to post-translational modification of proteins, impaired mitochondrial function, and NASH. The first aim of this exploratory project is to characterize and quantify the development of NASH and mitochondrial damage in response to a high-fat diet in mice. The use of this model will facilitate future studies with transgenic and/or knockout mouse models to investigate mechanisms of protection from metabolic stress in liver mitochondria. The second aim is to characterize post-translational modifications to the hepatic mitochondria proteome in response to NASH. Completion of these studies using novel proteomic approaches will enable the identification of the molecular defects in metabolic pathways and/or proteins in NASH that can be targeted by mitochondria-specific therapeutic strategies for treatment and prevention. Public health relevance (lay description) - Studies report an increasing prevalence of obesity in the world. Obesity is associated with serious health problems including heart disease and diabetes and is recognized as the most common risk factor for development of chronic non alcohol-related liver diseases. The studies in this application are important as they will identify the underlying factors responsible for obesity-related liver diseases, which will lead to the discovery of new treatments.