Defining mechanisms of succinate regulation over adipose tissue thermogenesis

琥珀酸调节脂肪组织产热的机制研究 项目总结： 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。生热棕色 米色脂肪组织可以分解储存的脂肪，具有很强的抗肥胖作用。抗肥胖的活动 生热脂肪细胞需要外周信号的激活，并对这些激活进行鉴定 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生热呼吸。值得注意的是，这些细胞可以利用琥珀酸驱动 通过将其从循环中隔离出来的生热作用，这是新发现的一种独特的生热活动 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 研究依赖琥珀酸的生热作用，并确定其生理后果。 为了建立我们对琥珀酸生热途径的认识，我们提出了一些具体的假设来检验。 这将决定棕色和米色脂肪细胞获取和利用琥珀酸的机制 控制他们的减肥活动。基于大量的初步数据，我们假设 质膜转运体单羧酸转运体1(MCT1)对琥珀酸摄取的特异性控制 在棕色脂肪细胞中。我们的发现使我们假设MCT1受到独特的 生热脂肪细胞重新利用其活性来促进琥珀酸摄取。 在目标1中，结合使用遗传、生化和质谱学方法，我们将建立 棕色中MCT1被重新定位以促进琥珀酸吸收的数量贡献和机制 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，使用一只新鼠标 MCT1在生热脂肪中的消融模型(MCT1 Tf-KO已在实验室中)我们将在体内建立 选择性抑制生热脂肪细胞摄取琥珀酸的生理后果。在《目标3》中我们 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基础上，即琥珀酸的生热活性需要它的氧化， 随后产生活性氧物种，半胱氨酸残基对蛋白质进行修饰。我们会 应用本实验室开发的新的质谱学方法绘制琥珀酸诱导的ROS修饰图 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 以确定其对琥珀酸诱导的能量消耗的相对重要性。 我们将一起确定脂肪组织琥珀酸摄取和产热的机制，以及它的 在操纵代谢性疾病中的因果作用。我们预测，这些发现将描述一种新的激活 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.