Defining mechanisms of succinate regulation over adipose tissue thermogenesis

琥珀酸调节脂肪组织产热的机制 项目概要： 肥胖是2型糖尿病、心血管疾病和许多癌症的主要危险因素。产热棕 米色脂肪组织可以分解代谢储存的脂肪，并有效地抗肥胖。抗肥胖活性 产热脂肪细胞的产生需要外周信号的激活， 机制是利用这些细胞的治疗活性的关键。 我们最近发现线粒体代谢产物琥珀酸是一种有效的分子激活剂， 棕色和米色脂肪细胞的产热呼吸。值得注意的是，这些细胞可以利用琥珀酸来驱动 通过将其从循环中隔离出来，这是一种新发现的独特的产热活动 脂肪细胞我们目前的目标是研究控制这一新发现的途径的分子机制 琥珀酸依赖性产热，并确定其生理后果。 为了建立我们的琥珀酸产热途径的鉴定，我们提出了具体的假设来检验 这将决定棕色和米色脂肪细胞获得和利用琥珀酸的机制， 控制其抗肥胖活性。基于广泛的初步数据，我们假设 质膜转运蛋白单羧酸转运蛋白1（MCT 1）特异性调控琥珀酸摄取 在棕色脂肪细胞中。我们的研究结果使我们假设，MCT 1是受独特的调控， 产热脂肪细胞，其重新利用其活性以促进琥珀酸摄取。 在目标1中，使用遗传、生物化学和质谱方法的组合，我们将建立 MCT 1被重新利用以驱动棕色中琥珀酸吸收的定量贡献和机制 和米色脂肪细胞，以及抑制这一途径的分子后果。在目标2中，使用新鼠标 在产热脂肪中的MCT 1消融模型（MCT 1 TF-KO已经在实验室中），我们将建立体内 产热脂肪细胞选择性抑制琥珀酸摄取的生理后果。在目标3中， 将建立琥珀酸控制棕色和米色产热呼吸的机制 脂肪细胞我们将建立在我们的发现，即琥珀酸的产热活性需要它的氧化， 随后产生活性氧物质和修饰蛋白质上的半胱氨酸残基。我们将 应用我们实验室开发的新质谱方法来绘制琥珀酸诱导的ROS修饰 产热蛋白质。此外，我们将使用新开发的主要功能丧失遗传模型， 产热效应子，以确定它们对琥珀酸诱导的能量消耗的相对重要性。 总之，我们将确定脂肪组织琥珀酸摄取和产热的机制，以及其 在操纵代谢疾病中的因果作用。我们预测，这些发现将表征一种新的激活 脂肪组织产热的抗肥胖作用所需的途径，这可能导致新的 治疗肥胖和糖尿病的药理学方法。

Defining mechanisms of succinate regulation over adipose tissue thermogenesis PROJECT SUMMARY: Obesity is a major risk factor for type-2 diabetes, cardiovascular disease, and many cancers. Thermogenic brown and beige adipose tissues can catabolize stored fat and are potently anti-obesogenic. The anti-obesity activity of thermogenic adipocytes requires activation by peripheral signals, and the identification of these activating mechanisms is key to leveraging the therapeutic activity of these cells. We recently discovered that the mitochondrial metabolite succinate is a potent molecular activator of thermogenic respiration in brown and beige adipocytes. Remarkably, these cells can utilize succinate to drive thermogenesis by sequestering it from the circulation, which is a newfound unique activity of thermogenic adipocytes. Our current objective is to investigate the molecular mechanisms that control this newfound pathway of succinate-dependent thermogenesis, and to also determine its physiological consequences. To build on our identification of the succinate thermogenesis pathway we propose specific hypotheses to test that will determine the mechanisms through which brown and beige adipocytes acquire and utilize succinate to control their anti-obesity activity. Based on extensive preliminary data, we hypothesize an essential role for the plasma membrane transporter monocarboxylate transporter 1 (MCT1) in controlling succinate uptake specifically in brown adipocytes. Our findings have led us to hypothesize that MCT1 is subject to unique regulation in thermogenic adipocytes that re-purposes its activity to facilitate succinate uptake. In Aim 1 using a combination of genetic, biochemical, and mass spectrometry approaches, we will establish the quantitative contribution and mechanisms through which MCT1 is repurposed to drive succinate uptake in brown and beige adipocytes, and the molecular consequences of inhibiting this pathway. In Aim 2, using a new mouse model of MCT1 ablation in thermogenic fat (MCT1 TF-KO already in the lab) we will establish the in vivo physiological consequences of selective inhibition of succinate uptake by thermogenic adipocytes. In Aim 3 we will establish the mechanisms through which succinate controls thermogenic respiration in brown and beige adipocytes. We will build on our discovery that the thermogenic activity of succinate requires its oxidation, consequent generation of reactive oxygen species, and modification of cysteine residues on proteins. We will apply new mass spectrometry approaches developed by our lab to map succinate-induced ROS modifications of thermogenic proteins. In addition, we will use newly developed loss of function genetic models of the major thermogenic effectors to establish their relative importance for succinate-induced energy expenditure. Together, we will determine the mechanisms of adipose tissue succinate uptake and thermogenesis, and its causal role in manipulating metabolic disease. We predict that these findings will characterize a novel activation pathway that is required for the anti-obesity effects of adipose tissue thermogenesis, which could lead to new pharmacological approaches to treat obesity and diabetes.