Reversible Mitochondrial Protein Acetylation and Metabolic Regulation

描述（由申请人提供）：这是一个R24资助的竞争性更新，重点是SIRT3，主要的线粒体蛋白脱乙酰酶。由于NIH的预算限制，我们的初始资金仅限于两年，但我们相信，在这笔赠款的前18个月，我们在形成一个跨学科团队方面取得了很大进展，该团队定义了SIRT3的新生物学功能及其在调节全身代谢中的作用。我们发现SIRT3的表达在禁食和糖尿病时在肝脏和肌肉中受到不同的调节。在肝脏中，禁食期间SIRT3增加导致脂肪酸氧化途径中关键线粒体酶的脱乙酰化，并增加其酶活性。相比之下，SIRT3在禁食期间在肌肉中的表达减少，导致丙酮酸脱氢酶和电子传递链的几个组分的过度乙酰化。SIRT3KO的代谢组学分析揭示了脂肪酸、葡萄糖和氨基酸氧化调节中可能的组织特异性差异，这将在本申请中进一步探索。这些研究清楚地表明，SIRT3KO小鼠在肝脏中具有缺陷的脂肪酸氧化，并且在肌肉中具有降低的代谢灵活性和降低的ATP水平，以及由于增加的ROS和应激激酶的激活而具有胰岛素抗性。此外，置于高脂肪饮食的SIRT3KO小鼠显示出加速发展的综合征，其模拟具有肥胖、2型糖尿病、脂质异常和脂肪性肝炎的人类代谢综合征。这些发现共同指出了可逆线粒体蛋白乙酰化作为线粒体代谢的关键调节剂的作用，以及SIRT3作为2型糖尿病和代谢综合征发病机制中的潜在重要因素。该提案的总体目标是扩展这些研究，以完全确定蛋白质乙酰化和SIRT3在线粒体功能和代谢控制中的作用。我们将利用我们高度协作和多学科的团队，利用基于质谱的蛋白质组学，代谢组学，分子生物学，广泛的生理测试和独特的动物模型的力量，进一步扩大我们对线粒体功能和代谢调节这一重要过程的理解。

DESCRIPTION (provided by applicant): This is a competitive renewal of an R24 grant focused on SIRT3, the major mitochondrial protein deacetylase. Our initial funding was limited to two years due to NIH budget constraints, but we believe that during the first 18 months of this grant we have made great progress in forming and an interdisciplinary team that has defined novel biological functions of SIRT3 and its role in regulation of systemic metabolism. We have found that SIRT3 expression is differentially regulated in liver and muscle in fasting and diabetes. In liver, increased SIRT3 during fasting leads to deacetylation of key mitochondrial enzymes in the fatty acid oxidation pathway and to an increase in their enzymatic activities. In contrast, SIRT3 expression decreases in muscle during fasting, leading to hyperacetylation of pyruvate dehydrogenase and several components of the electron transport chain. Metabolomic analysis of SIRT3KO reveals possible tissue-specific differences in regulation of fatty acid, glucose, and amino acid oxidation that will be explored further in the current application. These studies clearl show that SIRT3KO mice have defective fatty acid oxidation in liver and reduced metabolic flexibility and reduced ATP levels in muscle, as well as insulin resistance due to increased ROS and activation of stress kinases. Furthermore, SIRT3KO mice placed on a high fat diet show accelerated development of a syndrome that mimics human metabolic syndrome with obesity, type 2 diabetes, lipid abnormalities, and steatohepatitis. Together these findings point to a role of reversible mitochondrial protein acetylation as a key regulator of mitochondrial metabolism and SIRT3 as a potentially important factor in the pathogenesis of type 2 diabetes and the metabolic syndrome. The overall goal of this proposal is to extend these studies to completely define the role of protein acetylation and SIRT3 in mitochondrial function and control of metabolism. We will take advantage of our highly collaborative and multidisciplinary team harnessing the power of mass spectrometry-based proteomics, metabolomics, molecular biology, extensive physiological testing and unique animal models to further expand our understanding of this important process in regulation of mitochondrial function and metabolism.