Role of Muscle Ketone Metabolism in Mediating the Metabolic Benefits of Weight Loss

项目摘要 促进酮产生的饮食方案由于其促进体重的能力而越来越受欢迎 减肥和改善代谢健康。酮（例如乙酰乙酸酯和3-羟基丁酸酯（3OHB））通过以下方法产生： 当葡萄糖低时，肝脏和脑及周围组织氧化。虽然该领域在很大程度上 重点关注酮对大脑和心脏的积极影响，骨骼肌中酮氧化的作用 在很大程度上被忽视和调查。我们实验室的数据表明骨骼肌 是3OHB清除的主要部位，因此我们推测骨骼肌3OHB氧化对于 “生酮”饮食减肥方案的最佳代谢益处。为此，此应用程序将 催化3OHB氧化第一步的酶，D-β-羟基丁酸脱氢酶（BDH 1）， 改善全身葡萄糖代谢和能量平衡，因为肥胖后体重减轻。中央 本提案的目的是确定骨骼肌BDH 1是否在介导健康中起关键作用 促进生酮和减肥的饮食方案的好处。BDH 1催化接近平衡的 将酮氧化与线粒体NAD（H）氧化还原状态偶联的反应。在此，我们提出了一个新的 将BDH 1定位为线粒体氧化还原缓冲剂的概念模型， 禁食和再喂养期间的健康。我们的概念模型和中心目标将受到 继研究。首先，我们使用一种新的小鼠模型，其具有可诱导的骨骼肌特异性BDH 1缺失 为了确定BDH 1对骨骼肌线粒体生物能量学和葡萄糖代谢的影响， 对禁食和再喂养的反应。第二，我们将测试肌肉BDH 1是需要的假设， 典型的西方饮食的热量限制喂养的代谢益处。第三，我们将应用基因工程 在原代人骨骼肌细胞中，测试了酮诱导的肌细胞氧化还原转变的假设， 状态影响葡萄糖摄取和下游代谢。这些研究的结果将扩大我们的 了解骨骼肌BDH 1和酮氧化与长期目标的功能相关性 确定新的治疗靶点，以预防肥胖引起的代谢疾病。重要的是这 该项目将提供酮代谢、细胞遗传工程、13 C 稳定同位素示踪和计算13 C代谢通量分析。职业发展计划将是 通过包括Muoio博士（杜克分子生理学研究所，DMPI）在内的优秀导师团队实施 作为主要导师，Newgard博士（DMPI）作为共同导师，Zhang博士（DMPI）和Crawford博士（UMN）作为 咨询委员会成员。DMPI是一个理想的培训环境，因为它包含一个多元化的团队 具有营养代谢和多组学技术专门知识的研究人员;包括稳定同位素 在一栋楼里追踪该奖项提供的培训和职业发展机会 将确保威廉姆斯博士作为代谢研究人员的独立职业生涯有一个特殊的开始。

PROJECT SUMMARY Dietary regimens that promote ketone production are gaining popularity due to their ability to facilitate weight loss and improve metabolic health. Ketones (e.g. acetoacetate and 3-hydroxybutyrate (3OHB)) are produced by the liver and oxidized by the brain and peripheral tissues when glucose is low. Whereas the field has largely focused on the positive effects of ketones on the brain and heart, the role of ketone oxidation in skeletal muscle has been largely overlooked and under investigated. Data from our laboratory suggests that the skeletal muscle is a major site of 3OHB clearance, therefore we postulate that skeletal muscle 3OHB oxidation is necessary for optimal metabolic benefits of ‘ketogenic’ dietary weight loss regimens. To this end, this application links the enzyme that catalyzes the first step of 3OHB oxidation, D-ꞵ-hydroxybutyrate dehydrogenase (BDH1), to improved whole-body glucose metabolism and energy homeostasis due to post-obesity weight loss. The central objective of this proposal is to determine if skeletal muscle BDH1 plays a key role in mediating the health benefits of dietary regimens that promote ketogenesis and weight loss. BDH1 catalyzes a near-equilibrium reaction that couples ketone oxidation to the mitochondrial NAD(H) redox state. Herein, we propose a novel conceptual model that positions BDH1 as a mitochondrial redox buffer that promotes optimal skeletal muscle health during fasting and refeeding. Our conceptual model and central objective will be rigorously tested by the following studies. First, we use a novel mouse model with an inducible skeletal muscle-specific deletion of BDH1 to determine the impact of BDH1 on skeletal muscle mitochondrial bioenergetics and glucose metabolism in response to fasting and refeeding. Second, we will test the hypothesis that muscle BDH1 is required for the metabolic benefits of calorie-restricted feeding of a typical Western diet. Third, we will apply genetic engineering in primary human skeletal muscle cells test the hypothesis that ketone-induced shifts in the myocellular redox state impact glucose uptake and downstream metabolism. Results from these studies will expand our understanding of the functional relevance of skeletal muscle BDH1 and ketone oxidation with the long term goal of identifying new therapeutic targets for the prevention of obesity-induced metabolic disease. Importantly, this project will provide advanced training and mentoring in ketone metabolism, cellular genetic engineering, 13C stable isotope tracing, and computational 13C metabolic flux analysis. The career development plan will be implemented via a team of outstanding mentors including Dr. Muoio (Duke Molecular Physiology Institute, DMPI) as the primary mentor, Dr. Newgard (DMPI) as the co-mentor, and Drs. Zhang (DMPI) and Crawford (UMN) as members of the advisory committee. The DMPI is an ideal environment for training as it contains a diverse team of researchers with expertise in nutrient metabolism and multi-omics technologies; including stable isotope tracing all within a single building. The opportunities for training and career development provided by this award will ensure Dr. Williams has an exceptional start to her independent career as a metabolic researcher.