Perilipin and cellular triacylglycerol metabolism

Perilipin 和细胞三酰甘油代谢

• 批准号: 8282929
• 负责人: DAWN L BRASAEMLE
• 金额: $ 31.43万
• 依托单位: RUTGERS, THE STATE UNIV OF N.J.
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-15 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8282929
• 关键词: 1,2-diacylglycerol; Abbreviations; Address; Adipocytes; Adipose tissue; Adrenergic Receptor; Affect; Alanine; Amino Acids; Anisotropy; Area; Binding; Blood; Blood Circulation; Bovine Serum Albumin; CAR receptor; Cell Culture Techniques; Cell model; Cell surface; Cells; Coenzyme A; Complex; Cultured Cells; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Cytoplasm; DEXA; Development; Diglycerides; Docking; Drops; Dual-Energy X-Ray Absorptiometry; Embryo; Energy Supply; Energy Transfer; Energy-Generating Resources; Enzyme Tests; Enzymes; Exercise; Fasting; Fatty Acids; Fatty Liver; Fibroblasts; Fluorescence Recovery After Photobleaching; Forms Controls; Glycerides; Goals; Health; Hydrolase; Hydrolysis; Individual; Insulin Resistance; Knockout Mice; Lipase; Lipids; Lipolysis; Liver; Mediating; Metabolic; Metabolic Control; Metabolism; Modeling; Molecular; Molecular and Cellular Biology; Mus; Muscle; Mutate; Mutation; NIH 3T3 Cells; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Peptides; Peripheral; Phospholipid Metabolism; Phosphorylation; Phosphorylation Site; Phosphotransferases; Play; Polyacrylamide Gel Electrophoresis; Positioning Attribute; Process; Protein Kinase C; Proteins; Recombinants; Recruitment Activity; Regulation; Research; Reverse Transcriptase Polymerase Chain Reaction; Role; Serine; Site; Sodium Dodecyl Sulfate-PAGE; Structure; Surface; Syndrome; Techniques; Testing; Therapeutic Intervention; Tissues; Transgenic Mice; Triglycerides; United States National Institutes of Health; Variant; Work; controlled release; enzyme activity; feeding; in vivo; insulin sensitivity; lipid metabolism; lipine; lysophosphatidic acid acyltransferase; methylxanthine; mouse model; novel; perilipin; perilipin A; protein protein interaction; public health relevance; research study; scaffold; selective expression; sterol esterase; trafficking

DESCRIPTION (provided by applicant): Adipocytes store the body's major energy supply in the form of triacylglycerols (TAGs) packaged into perilipin- coated lipid droplets. Dysregulation of adipose TAG metabolism in obese individuals leads to release of excess fatty acids into circulation, which contributes to the development of health complications including peripheral insulin resistance and hepatic steatosis. The regulation of adipose TAG storage and hydrolysis is complex; our understanding of these processes is rudimentary and incomplete. The proposed studies investigate the molecular mechanisms by which perilipin controls and coordinates TAG metabolism and lipid droplet dynamics. The overarching hypothesis of these studies is that perilipin forms a scaffold at the surfaces of lipid droplets in adipocytes that serves as an organizing center for lipid metabolic enzymes and trafficking factors. Under basal conditions, when TAG storage predominates over a low level of basal lipolysis, the perilipin scaffold binds CGI- 58, a Coenzyme A-dependent lysophosphatidic acid acyltransferase and co-activator of adipose triglyceride lipase (ATGL). When cell surface ¿-adrenergic receptors are stimulated, cellular cAMP levels increase and protein kinase A (PKA) is activated. Perilipin is phosphorylated by PKA on as many as 6 serine residues; phosphorylation of these sites promotes lipolysis through several different mechanisms. Phosphorylation of PKA sites 1, 2, and 3 in the amino terminus of perilipin promotes the docking of PKA-phosphorylated hormone- sensitive lipase (HSL) on lipid droplets through a protein-protein interaction with perilipin, and HSL gains access to TAG and diacylglycerol substrates. Phosphorylation of carboxyl terminal PKA sites 4, 5, and 6 facilitates lipolysis by as yet poorly understood mechanisms, which include the promotion of lipid droplet fragmentation into myriad lipid micro-droplets with increased surface area for lipase (ATGL) binding. The goals of the proposed study are to 1) investigate the role of serine 517 (within PKA site 6) in lipid droplet association of perilipin and control of lipolysis using techniques of cellular and molecular biology, 2) investigate the role of PKA-mediated phosphorylation of serine 492 (within PKA site 5) in lipid droplet remodeling in a cultured cell model and lipolysis in both cells and mice, and 3) investigate the mechanisms by which CGI-58 co-activates ATGL, and perilipin serves as a platform for regulation of TAG hydrolysis by ATGL. Mutated variants of peri- lipin and CGI-58 will be studied in cultured cells and a novel transgenic mouse model of adipose-selective expression of mutated perilipin on a perilipin null background. The information gained from these studies will contribute to a long-term goal of defining lipid droplet-associated factors that control TAG metabolism in adipocytes. PUBLIC HEALTH RELEVANCE: Adipocytes (fat cells) in adipose tissue store the major energy reserves of the body as triacylglycerols in struc- tures called lipid droplets. Obese individuals have enlarged lipid droplets in adipocytes when compared to lean individuals. Lipid droplets are covered with perilipin, a protein which controls the metabolism of triacylglycerols, and hence, the release of fatty acids into the blood for use as a source of energy by various tissues of the body. Obesity is characterized by inappropriate and excessive release of fatty acids into circulation; these fatty acids are taken up by muscle and liver and contribute to the development of insulin resistance (which occurs in type II diabetes) and fatty liver. Our understanding of the mechanisms by which perilipin controls triacylglycerol (fat) metabolism in adipocytes is incomplete; the proposed research will increase understanding of these mechanisms, and identify potential new targets for therapeutic intervention to control release of fatty acids from adipose tissue.

描述（由适用提供）：脂肪细胞以包装到围脂蛋白涂层的脂质液滴中的三酰基甘油（TAG）形式存储人体的主要能量供应。肥胖个体中脂肪TAG代谢的失调导致多余的脂肪酸释放到循环中，这有助于发展健康并发症，包括周围胰岛素抵抗和肝脂肪变性。脂肪标签存储和水解的调节很复杂。我们对这些过程的理解是基本的和不完整的。拟议的研究研究了紫脂蛋白控制和协调TAG代谢和脂质液滴动力学的分子机制。这些研究的总体假设是，peri蛋白在脂肪细胞中脂质液滴的表面形成支架，这是脂质代谢酶和运输因素的组织中心。在基本条件下，当TAG储存主要在低水平的碱性脂肪分解上时，Perillipin支架结合了CGI-58，CGI-58是辅酶A依赖性溶血磷脂酰基转移酶和脂肪甘油甘油三酸酯脂肪酶（ATGL）的共激活剂。当刺激细胞表面�-肾上腺素受体时，细胞cAMP水平增加并激活蛋白激酶A（PKA）。 PERIPIN被PKA磷酸化多达6个丝氨酸残留物。这些位点的磷酸化通过几种不同的机制促进脂解。 PLIPIN氨基末端PKA位点1、2和3的磷酸化促进了通过与蛋白质 - 蛋白质相互作用的脂质液滴对脂质液滴的PKA磷酸化激素 - 敏感性脂肪酶（HSL）的对接，与Perilipin与HSL的蛋白质相互作用，以及HSL GAINS的访问，访问HSL的GAINS和DIACYCEROLSESLATES和DIACYCEROLSESLATES。羧基末端PKA位点4、5和6的磷酸化促进了脂肪分解，但尚未理解的机制，其中包括促进脂质液滴碎片碎片碎裂到众多的脂质微滴滴中，而脂肪酶（ATGL）结合的表面积增加了。 The goals of the proposed study are to 1) investigate the role of serine 517 (within PKA site 6) in lipid droplet association of perilipin and control of lipolysis using techniques of cellular and molecular biology, 2) investigate the role of PKA-mediated phosphorylation of serine 492 (within PKA site 5) in lipid droplet remodeling in a cultured cell model and lipolysis in both cells and小鼠和3）研究CGI-58共同激活ATGL的机制，并且Perilipin是ATGL调节TAG水解的平台。培养基和CGI-58的突变变体将在培养的细胞中进行研究，并在脂肪蛋白无效背景上突变脂蛋白的脂肪选择性表达的新型转基因小鼠模型。从这些研究中获得的信息将有助于定义脂质液滴相关因素，以控制脂肪细胞中的代谢。 公共卫生相关性：脂肪组织中的脂肪细胞（脂肪细胞）存储人体的主要能量储量为三酰基甘油在称为脂质液滴的结构中。与精益个体相比，肥胖个体的脂肪细胞中脂质液滴增加。脂质液滴覆盖着紫脂蛋白，一种控制三酰甘油的代谢的蛋白质，因此，将脂肪酸释放到血液中，以通过身体各个时机用作能量来源。肥胖的特征是脂肪酸不适当和过量释放到循环中。这些脂肪酸被肌肉和肝脏吸收，并有助于胰岛素抵抗的发展（发生在II型糖尿病中）和脂肪肝。我们对脂肪素控制脂肪细胞中三酰基甘油（脂肪）代谢的机制的理解是不完整的。拟议的研究将增加对这些机制的理解，并确定治疗干预措施的潜在新靶标，以控制脂肪酸从脂肪组织中释放。