A METABOLIC BIOMARKER OF HEPATIC NADH/NAD+ RATIO

项目摘要 非酒精性脂肪肝(NAFLD)是世界上最常见的慢性肝病，是一种 导致严重发病率和死亡率的原因不断增加。尽管它对全球健康的影响越来越大，但有 目前还没有FDA批准的治疗方法。虽然NAFLD的病理生理学很复杂， 越来越多的证据支持肝脏NADH/NAD+水平改变的直接作用。然而，测试 鉴于现有工具的局限性，NADH/NAD+在肝脏生理学中的作用是具有挑战性的 以精确的方式操纵它，以及缺乏循环中的NADH/NAD+生物标志物，这是不稳定的 在大多数临床和人类研究环境中，测量细胞内代谢物是不切实际的。 Mootha实验室已经开发出一种名为LbNOX的基因编码新陈代谢工具，可以直接和精确地 在不同的组织和细胞隔间操纵细胞NADH/NAD+。在前期工作中，我已经 在体外和体内使用这一工具来鉴定循环代谢物α-羟基丁酸酯(αHB)是 对肝脏NADH/NAD+变化敏感。αHb此前已被证明是胰岛素的生物标记物 对GCKR基因的抗性和多态敏感，而GCKR基因又与NAFLD相关。 我们的初步工作还表明，LbNOX在体内改善了肝脏胰岛素抵抗，而GCKR影响 肝细胞NADH/NAD+。这些发现将GCKR、非酒精性脂肪肝、αHb和肝脏NADH/NAD+联系起来。中环 这一假设认为αHb是肝脏NADH/NAD+的循环生物标志物 与肝脏胰岛素抵抗和脂肪变性有因果关系，以及肝脏的遗传调节因子 NADH/NAD+对肝脏脂肪变性和胰岛素抵抗的影响 在这个提案中，我将使用体外和体内肝脏LbNOX表达的组合来进一步定义 肝脏胰岛素抵抗、肝脏脂肪变性和肝脏NADH/NAD+之间的因果联系。我会给你下定义 LbNOX改善肝脏胰岛素抵抗的机制及GCKR的机制 影响肝脏NADH/NAD+。 我是一名临床和研究肝病专家，致力于作为一名内科科学家的研究生涯，专门研究 肝病的代谢方面。拟议的研究计划将使我能够发展新的知识和 新陈代谢、代谢组学和肝脏生理学方面的专业知识，并提供动物模型方面的经验 慢性肝病。在整个拟议的研究中，我将以正式的研究咨询为指导 由新陈代谢、非酒精性脂肪肝和肝脏生理学方面的杰出导师和专家组成的委员会，全部在 由麻省理工学院、博德研究所和附属机构组成的一流研究环境的设置。 我提出的这项研究，以及我在这项研究中的导师和合作者的指导，将对我有所帮助 确保我成功地过渡到科学独立。

PROJECT ABSTRACT Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the world, and is an increasing cause of significant morbidity and mortality. Despite its growing impact on global health there are currently no FDA-approved therapies for treatment. While the pathophysiology of NAFLD is complex, increasing evidence supports a direct role of alterations in hepatic NADH/NAD+ levels. However, testing the role of NADH/NAD+ in hepatic physiology is challenging given the limitations of existing tools with which to manipulate it in a precise manner, and the lack of circulating biomarkers for NADH/NAD+ which, as unstable intracellular metabolites, would be impractical to measure in most clinical and human research settings. The Mootha lab has developed a genetically encoded metabolic tool, called LbNOX, to directly and precisely manipulate cellular NADH/NAD+ in different tissues and cellular compartments. In preliminary work, I have used this tool both in vitro and in vivo to identify that a circulating metabolite, α-hydroxybutyrate (αHB) is sensitive to alterations in hepatic NADH/NAD+. αHB, has previously been shown to be a biomarker of insulin resistance and sensitive to polymorphisms in the gene GCKR, which in turn has been associated with NAFLD. Our preliminary work also shows LbNOX improves hepatic insulin resistance in vivo, and that GCKR influences hepatocyte NADH/NAD+. These findings link GCKR, NAFLD, αHB, and hepatic NADH/NAD+. The central hypothesis of this proposal is that αHB is a circulating biomarker of hepatic NADH/NAD+ which is causally linked to hepatic insulin resistance and steatosis, and that genetic modulators of hepatic NADH/NAD+ influence hepatic steatosis and insulin resistance In this proposal, I will use a combination of in vitro and in vivo hepatic LbNOX expression to further define the causal connection between hepatic insulin resistance, hepatic steatosis, and hepatic NADH/NAD+. I will define the mechanism by which LbNOX improves hepatic insulin resistance, and the mechanism by which GCKR influences hepatic NADH/NAD+. I am a clinical and research hepatologist dedicated to a research career as a physician scientist specializing in metabolic aspects of liver disease. The proposed research plan will allow me to develop new knowledge and expertise in metabolism, metabolomics, and hepatic physiology, and provide experience with animal models of chronic liver disease. Throughout the proposed research I will be guided by a formal research advisory committee comprised of outstanding mentors and experts in metabolism, NAFLD, and hepatic physiology, all in the setting of a stellar research environment comprised of MGH, the Broad Institute, and affiliated institutions. The research proposed, along with the guidance of my mentors and collaborators in this research, will help ensure my successful transition to scientific independence.