The regulation of adipocyte lipolysis by insulin

胰岛素对脂肪细胞脂肪分解的调节

基本信息

批准号：
8335458
负责人：
Morris Jay Birnbaum
金额：
$ 34.8万
依托单位：
UNIVERSITY OF PENNSYLVANIA
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-09-20 至 2015-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8335458
关键词：
1,2-diacylglycerol Acute Adipocytes Adipose tissue Applications Grants Biological Assay Biosensor Catecholamines Ceramides Cyclic AMP Cyclic AMP-Dependent Protein Kinases Cyclic Nucleotides Data Deposition Development Dietary Fats Diglycerides Disease Enzymes Epidemic Event Fasting Fatty Acids Fatty acid glycerol esters Fluorescence Resonance Energy Transfer Genetic Genetic screening method Hormonal Hydrolysis Hyperinsulinism Image Individual Insulin Insulin Receptor Insulin Resistance Intracellular Second Messenger Isotopes Laboratories Life Lipids Lipolysis Liver Metabolic syndrome Modeling Mus Muscle Non-Insulin-Dependent Diabetes Mellitus Nonesterified Fatty Acids Nutritional Obesity PDE 3B Paper Pathway interactions Phosphatidylinositols Phosphorylation Phosphotransferases Physiological Play Predisposition Principal Investigator Process Protein Kinase Proto-Oncogene Proteins c-akt Publishing Regulation Resistance Role Scaffolding Protein Second Messenger Systems Signal Transduction Site Specificity Surface Testing Time Tissues Triglycerides United States Work beta adrenergic agent glucose metabolism in vivo insulin signaling lipid metabolism loss of function novel perilipin prevent programs relating to nervous system research study

项目摘要

DESCRIPTION (provided by applicant): During times of fasting, energy stored in the adipocyte as triglyceride is released for use by muscle, liver and other tissues. This process, termed lipolysis, is highly regulated by hormonal, neural and nutritional inputs. There is subtantial evdence that resistance to the actions of insulin to antagonize lipolysis is an early and important step in the development of type 2 diabetes mellitus and the metabolic syndrome. The intracellular second messenger most frequently used to convey the signal for increased lipolysis is cyclic AMP, which accumulates in reponse to beta-adrenergic agents and activates protein kinase A. Much is known about signaling downstream of protein kinase A, including a major substrate, perilipin, present on the triglyceride lipid droplet. Insulin antagonizes the process of lipolysis, and there is a generally accepted model to explain the acute suppression of adipocyte lipolysis, though it has not been studied in detail. The canonical model of insulin signaling describes phosphoinositide 3'-kinase-dependent activation of Akt (protein kinase B), which then phosphorylates and stimulates phosphodiesterase 3B (PDE3B), leading to a decrease in intracellular cyclic AMP. Previous work from the laboratory of the principal investigator has revealed, however, an alternative pathway of insulin action that comes into play upon sub-maximal stimulation of lipolysis. Preliminary data indicate that this signaling cascade functions independently of Akt and that the critical signaling events occur on the surface the lipid droplet. The studies described in this grant proposal will formally test the hypothesis of an alternative pathway for anti-lipolytic signaling. Experiments include the use of FRET biosensors to determine the precise intracellular sites of PKA activation in cultured adipocytes and the identification of scaffolding proteins that target regulatory molecules ot the lipid droplet. The requirement for Akt and PDE3B phosphorylation in the suppression of lipolysis will be tested for the first time by genetic loss of function experiments. Lastly, the contribution of this novel pathway for the suppression of fat cell lipolysis will be assessed for physiological relevance through in vivo experiments in genetically modified mice.

描述（由申请人提供）：在禁食时期，脂肪细胞中存储的能量作为甘油三酸酯释放，供肌肉，肝脏和其他组织使用。该过程称为脂解，受荷尔蒙，神经和营养输入高度调节。锥虫症是对胰岛素对脂解的作用的抗性是2型糖尿病型糖尿病和代谢综合征发展的早期和重要步骤。细胞内的第二信使最常用于传达增加脂肪分解的信号的是环状AMP，它积累了对β-肾上腺素能剂并激活蛋白激酶A。，存在于甘油三酸酯脂质液滴上。胰岛素拮抗脂解的过程，并且有一个公认的模型来解释脂肪细胞脂解的急性抑制，尽管尚未详细研究。胰岛素信号传导的规范模型描述了Akt（蛋白激酶B）的磷酸肌醇3'-激酶依赖性激活，然后磷酸化并刺激磷酸二酯酶3B（PDE3B），从而导致细胞内循环蛋白透射AMP的降低。然而，主要研究者实验室的先前工作表明，在脂肪溶解的下最大刺激下发挥了胰岛素作用的另一种途径。初步数据表明，该信号级联反应独立于AKT，并且关键信号事件发生在脂质液滴表面上。该赠款提案中描述的研究将正式检验抗脂肪解释信号传导的替代途径的假设。实验包括使用FRET生物传感器来确定培养的脂肪细胞中PKA激活的精确细胞内部位，以及鉴定靶向调节分子的脚手架蛋白的鉴定，这些蛋白质的蛋白质是脂质液滴的。 AKT和PDE3B磷酸化在脂肪解抑制中的需求将首次通过功能实验的遗传丧失来测试。最后，将通过在遗传修饰的小鼠中的体内实验评估这一新型途径对抑制脂肪细胞脂解抑制的贡献。