Regulation of fatty acid metabolism in adipocytes

脂肪细胞脂肪酸代谢的调节

基本信息

批准号：
10541010
负责人：
Shannon Marie Reilly
金额：
$ 42.38万
依托单位：
WEILL MEDICAL COLL OF CORNELL UNIV
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-12-03 至 2025-11-30
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10541010
关键词：
Acyltransferase Adipocytes Adipose tissue Adrenergic Agents Adrenergic Receptor Agonist Animals Binding Biological Biological Assay Body Weight decreased Catecholamines Cations Cell Respiration Cells Co-Immunoprecipitations Crete Cyclic AMP Data Defect Dependence Development Energy Metabolism Esterification Event Exhibits Fasting Fatty Acids Female Glycerol High Fat Diet Homeostasis Hypertriglyceridemia In Vitro Intake Knockout Mice Lead Link Lipids Lipolysis MAPK8 gene Maps Metabolic Metabolic Diseases Modeling Mus Mutant Strains Mice Nature Nerve Nonesterified Fatty Acids Nutrient Obesity Oxides Pathway interactions Phosphorylation Phosphorylation Site Phosphotransferases Physiological Post-Translational Protein Processing Process Protein Isoforms Proteins Proteomics Public Health Receptor Activation Regulation Regulatory Pathway Role Signal Pathway Signal Transduction Stat3 protein Sympathetic Nervous System Techniques Time Triglycerides Weight Gain alpha-glycerophosphoric acid beta-adrenergic receptor design diet-induced obesity energy balance experimental study fatty acid metabolism fatty acid oxidation feeding improved in vivo insight male mutant non-genomic novel novel therapeutic intervention obesity development oxidation preference recruit response reuptake therapeutic target

项目摘要

The regulation of energy storage and utilization in adipocytes is a dynamic process that influences overall energy homeostasis. Adipocytes store nutrients in lipid droplets as triglycerides (TG), and mobilize them as needed. While these cells respond to sympathetic signals by increasing TG lipolysis to release free fatty acids (FFA) and glycerol, they also reabsorb FFA for re-esterification as triglycerides or alternatively for oxidation. Activation of b-adrenergic receptors and downstream cyclic AMP signaling not only increases lipolysis, but also promotes fatty acid oxidation at the expense of re-esterification, although the underlying mechanisms remain poorly understood. We hypothesize that catecholamines direct fatty acids for oxidation through regulation of signal transducer and activator of transcription 3 (STAT3) and suppression of glycerol-3-phosphate acyltransferase 3 (GPAT3). Our preliminary data demonstrate that STAT3 specifically undergoes Ser727 phosphorylation at the lipid droplet in response to stimulation of b-3 adrenergic receptors and activation of lipolysis in adipocytes. The pool of lipid droplet-associated STAT3 binds to and inhibits GPAT3, effectively suppressing GPAT3-catalyzed re-esterification, to promote fatty acid oxidation. Adipocyte-specific Stat3 KO mice exhibit normal rates of lipolysis, but manifest a specific defect in lipolysis-driven oxidative metabolism, resulting in reduced energy expenditure and increased adiposity on high fat diet. The experiments outlined in this proposal are designed to expand insights into this novel function of STAT3, determining its metabolic consequences and delineating the mechanism of action. Aim 1 will focus on the stimulation of STAT3 phosphorylation by catecholamines in vivo, delineating the signaling pathway and specific kinase(s) responsible for the critical STAT3 Ser727 phosphorylation event. The interaction of STAT3 with GPAT3 will be investigated in aim 2 using co-immunoprecipitation and in vitro binding assays. Additionally, the mechanism by which STAT3 interaction results in suppression of GPAT3 activity will be investigated using in vitro GPAT activity assays and proteomic approaches. Finally, in aim 3, the physiological relevance of this novel regulatory pathway in the development of obesity in males and females will be examined. Additionally, non-phosphorylatable STAT3 S727A mutant adipocytes and mice will be employed to determine the in vivo role of this phosphorylation site. These studies will provide a more complete understanding of the regulation of lipolysis-driven oxidative metabolism, and will improve our understanding of this energy expending pathway in white adipose tissue. This may lead to the development of new therapeutic approaches to curtail obesity and the devastating metabolic diseases with which obesity is associated.

脂肪细胞能量储存和利用的调节是一个动态过程，影响整体能量稳态。脂肪细胞将营养物质以甘油三酯（TG）的形式储存在脂滴中。根据需要动员它们，而这些细胞通过增加 TG 脂肪分解来响应交感神经信号。释放游离脂肪酸 (FFA) 和甘油，它们还会重新吸收 FFA 以重新酯化为甘油三酯，或者激活 b 肾上腺素能受体和下游。环AMP信号不仅增加脂肪分解，而且还促进脂肪酸氧化尽管其基本机制仍知之甚少，但再酯化的过程仍然存在。儿茶酚胺通过信号转导器的调节引导脂肪酸氧化转录激活剂 3 (STAT3) 和甘油-3-磷酸酰基转移酶 3 的抑制 (GPAT3)。我们的初步数据表明，STAT3 在脂滴上特异性地经历 Ser727 磷酸化，以响应 b-3 肾上腺素受体的刺激和脂肪细胞中脂肪分解的激活。脂滴相关的 STAT3 池结合并抑制 GPAT3，有效抑制 GPAT3 催化的再酯化，促进脂肪细胞特异性 Stat3 KO 小鼠表现出正常的脂肪酸氧化率。脂肪分解，但在脂肪分解驱动的氧化代谢中表现出特定的缺陷，导致高脂肪饮食中能量消耗减少和肥胖增加。本提案中概述的实验旨在扩大对 STAT3 这种新功能的了解，确定其代谢后果和。描绘作用机制目标 1 将重点关注儿茶酚胺在体内刺激 STAT3 磷酸化，描绘负责关键 STAT3 Ser727 的信号传导途径和特定激酶。目标 2 中将使用免疫共沉淀和体外结合测定来研究 STAT3 与 GPAT3 的相互作用。此外，还将使用体外 GPAT 活性测定和蛋白质组学来研究 STAT3 相互作用导致 GPAT3 活性抑制的机制。最后，在目标 3 中，将检查这种新的调节途径在男性和女性肥胖发展中的生理相关性。将利用脂肪细胞和小鼠来确定该磷酸化位点的体内作用，这些研究将为脂肪分解驱动的氧化代谢的调节提供更全面的了解，并将提高我们对白色脂肪组织中这种能量消耗途径的理解。这可能会导致新的治疗方法的开发，以减少肥胖和与肥胖相关的破坏性代谢疾病。