Lipolysis

描述（由申请人提供）： 6.项目概述/摘要目标：为了将脂肪用作能量，脂肪组织中的三酰甘油（TAG）必须被动员为游离脂肪酸（FFA），然后释放到循环中，即，脂肪分解脂解的控制是复杂的，涉及多种机制。脂肪分解的对应点是脂滴形成，这一过程也没有完全理解。本提案的目的是了解调节脂解和脂滴代谢的细胞和分子机制。我们将测试两个假设：1）激素敏感脂肪酶（HSL）和波形蛋白之间的物理相互作用参与HSL向脂滴的移位，从而促进脂解。2)波形蛋白在脂肪脂质代谢中具有双重功能，通过允许液滴经由小液滴的融合扩大来促进脂滴形成，同时还促进脂滴的水解。研究计划和方法：为了检验第一个假设，将使用显微镜和生物物理技术确定HSL和波形蛋白之间发生相互作用的细胞区室的位置，将使用波形蛋白敲除小鼠和体外敲减检查HSL-波形蛋白相互作用的生理重要性，并将使用突变分析鉴定HSL-波形蛋白相互作用的决定因素。为了检验第二个假设，将通过显微镜在野生型细胞和缺乏波形蛋白的细胞中比较脂滴形成的动力学，并通过生物物理技术检查脂滴相关蛋白与波形蛋白的相互作用。此外，野生型和波形蛋白缺失小鼠将被喂食正常或高脂肪饮食，并将确定对肥胖、碳水化合物和脂质代谢以及脂肪基因表达的影响。对退伍军人医疗保健的潜在影响：退伍军人事务部提供护理的大部分患者都是肥胖的。这些肥胖的退伍军人往往有更复杂的医疗课程，并有比非肥胖患者更差的医疗结果。VA中的肥胖患者具有多种医学问题，包括高血压、糖尿病、高脂血症、肺病、骨关节炎、痛风和癌症。这些病症有助于动脉粥样硬化的发展，其中冠状动脉疾病（心绞痛、心肌梗塞或心力衰竭）、外周血管疾病和脑血管疾病（中风）极为普遍。患有所有这些疾病的患者的特征在于FFA通量的异常调节。了解调节FFA释放的基本机制以及脂解作用如何影响脂肪细胞的整体生物学，将有助于描述肥胖和其他以循环FFA水平异常为特征的疾病中加速动脉粥样硬化的异常。 公共卫生相关性： 7.正如在一般人群中观察到的那样，大部分接受医学评估并由VA提供护理的患者都是肥胖的。这些肥胖的退伍军人往往有更复杂的医疗课程，并有比非肥胖患者更差的医疗结果。VA中的肥胖患者具有多种医学问题，包括高血压、糖尿病、高脂血症、肺病、骨关节炎、痛风和癌症。这些病症有助于动脉粥样硬化的发展，其中冠状动脉疾病（心绞痛、心肌梗塞或心力衰竭）、外周血管疾病和脑血管疾病（中风）极为普遍。患有所有这些疾病的患者的特征是游离脂肪酸（FFA）调节异常。了解调节FFA释放的基本机制以及这如何影响脂肪细胞的整体生物学，将对描绘导致肥胖症和其他以循环FFA水平异常为特征的疾病中加速动脉粥样硬化的异常具有意义。

DESCRIPTION (provided by applicant): 6. Project Summary/Abstract Objectives: For fat to be utilized for energy, it is necessary for the triacylglycerols (TAG) in adipose tissue to be mobilized to free fatty acids (FFA) and then released into the circulation, i.e., lipolysis. The control of lipolysis is complex and involves multiple mechanisms. The counterpoint to lipolysis is lipid droplet formation, a process that is also not fully understood. The objective of this proposal is to understand the cellular and molecular mechanisms regulating lipolysis and lipid droplet metabolism. We will test 2 hypotheses: 1) A physical interaction between hormone sensitive lipase (HSL) and vimentin participates in the translocation of HSL to the lipid droplet, thus facilitating lipolysis. 2) Vimentin has a dual function in adipose lipid metabolism, facilitating lipid droplet formation by allowing droplets to enlarge via the fusion of small droplets, while also facilitating the hydrolysis of lipid droplets. Research Plan and Methods: To test the first hypothesis, the location of the cellular compartment where the interaction between HSL and vimentin occurs will be determined using microscopy and biophysical techniques, the physiological importance of the HSL-vimentin interaction will be examined using vimentin knockout mice and in vitro knockdown, and the determinants of the HSL-vimentin interaction will be identified using mutational analyses. To test the second hypothesis, the dynamics of lipid droplet formation will be compared by microscopy in wild-type cells and cells lacking vimentin, and the interaction of droplet-associated proteins with vimentin will be examined by biophysical techniques. In addition, wild-type and vimentin null mice will be fed normal or high fat diets and the effects on adiposity, carbohydrate and lipid metabolism and adipose gene expression will be determined. Potential Impact on Veterans Health Care: A large proportion of patients for whom care is provided by the VA are obese. These obese veterans tend to have more complicated medical courses, and to have worse medical outcomes than nonobese patients. The obese patients within the VA have multiple medical problems, including hypertension, diabetes mellitus, hyperlipidemia, pulmonary disease, osteoarthritis, gout, and cancer. These conditions contribute to the development of atherosclerosis, with coronary artery disease (angina, myocardial infarction or cardiac failure), peripheral vascular disease and cerebrovascular disease (stroke) being extremely prevalent. Patients with all of these conditions are characterized by abnormal regulation of FFA flux. Understanding the basic mechanisms regulating FFA release and how lipolysis impacts the overall biology of adipose cells will have implications for delineating the abnormalities contributing to the accelerated atherosclerosis seen in obesity and in other conditions characterized by abnormal levels of circulating FFA. PUBLIC HEALTH RELEVANCE: 7. Project Narrative Just as observed in the general population, a large proportion of patients who are medically evaluated and for whom care is provided by the VA are obese. These obese veterans tend to have more complicated medical courses, and to have worse medical outcomes than nonobese patients. The obese patients within the VA have multiple medical problems, including hypertension, diabetes mellitus, hyperlipidemia, pulmonary disease, osteoarthritis, gout, and cancer. These conditions contribute to the development of atherosclerosis, with coronary artery disease (angina, myocardial infarction or cardiac failure), peripheral vascular disease and cerebrovascular disease (stroke) being extremely prevalent. Patients with all of these conditions are characterized by abnormal regulation of free fatty acids (FFA). Understanding the basic mechanisms regulating FFA release and how this impacts the overall biology of adipose cells will have implications for delineating the abnormalities contributing to the accelerated atherosclerosis seen in obesity and in other conditions characterized by abnormal levels of circulating FFA.