Lipolysis

描述(由申请人提供)： 6.项目摘要/摘要目的：为了利用脂肪作为能量，脂肪组织中的三酰甘油(TAG)必须被动员成游离脂肪酸(FFA)，然后释放到循环中，即脂解。脂解的控制是复杂的，涉及多种机制。与脂肪分解相反的是脂滴的形成，这一过程也没有完全被理解。这项建议的目的是了解调节脂解和脂滴代谢的细胞和分子机制。我们将检验两个假设：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了HSL向脂滴的移位，从而促进了脂解。2)Vimentin在脂肪代谢中具有双重功能，通过小液滴的融合使液滴扩大，从而促进脂滴的形成，同时也促进脂滴的水解。研究计划和方法：为了验证第一个假设，将使用显微镜和生物物理技术确定HSL和Vimentin之间相互作用的细胞室的位置，将使用Vimentin基因敲除小鼠和体外基因敲除来检验HSL-Vimentin相互作用的生理意义，并将使用突变分析确定HSL-Vimentin相互作用的决定因素。为了验证第二个假设，将在显微镜下比较野生型细胞和缺乏波形蛋白的细胞中脂滴形成的动力学，并将通过生物物理技术检查液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的小鼠将被喂以正常或高脂肪饲料，并将测定其对肥胖、碳水化合物和脂肪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：退伍军人管理局提供护理的患者中有很大一部分是肥胖的。这些肥胖的退伍军人往往有更复杂的医疗过程，而且比非肥胖患者的医疗结果更差。退伍军人管理局内的肥胖患者有多种医疗问题，包括高血压、糖尿病、高脂血症、肺部疾病、骨关节炎、痛风和癌症。这些情况导致动脉粥样硬化的发展，冠状动脉疾病(心绞痛、心肌梗死或心力衰竭)、外周血管疾病和脑血管疾病(中风)非常普遍。所有这些情况的患者都以FFA流量调节异常为特征。了解调节FFA释放的基本机制以及脂肪分解如何影响脂肪细胞的整体生物学将有助于描绘导致肥胖和其他以循环FFA水平异常为特征的动脉粥样硬化加速的异常。 公共卫生相关性： 7.项目叙述正如在普通人群中观察到的那样，接受医学评估并由退伍军人管理局提供护理的患者中，有很大一部分是肥胖的。这些肥胖的退伍军人往往有更复杂的医疗过程，而且比非肥胖患者的医疗结果更差。退伍军人管理局内的肥胖患者有多种医疗问题，包括高血压、糖尿病、高脂血症、肺部疾病、骨关节炎、痛风和癌症。这些情况导致动脉粥样硬化的发展，冠状动脉疾病(心绞痛、心肌梗死或心力衰竭)、外周血管疾病和脑血管疾病(中风)非常普遍。所有这些情况的患者都以自由脂肪酸(FFA)调节异常为特征。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有助于描述导致肥胖和其他以循环FFA异常水平为特征的动脉粥样硬化加速的异常。

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.