Regulation of Hepatic Glucose Homeostasis by Phosphatidylcholine Transfer Protein

磷脂酰胆碱转移蛋白对肝葡萄糖稳态的调节

• 批准号: 8389815
• 负责人: Baran Ersoy
• 金额: $ 5.84万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-06-08 至 2013-06-07
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8389815
• 关键词: Acyl Coenzyme A; Binding; Binding Proteins; Biochemical; Biological Assay; Cell Culture System; Cell Line; Cell membrane; Chemicals; Complex; Cultured Cells; Data; Defect; Development; Diabetes Mellitus; Diet; Disease; Doctor of Philosophy; Exhibits; Extrahepatic; Fasting; Fatty acid glycerol esters; Feedback; Health; Hepatic; In Vitro; Insulin; Insulin Resistance; Intervention; Intracellular Membranes; Laboratories; Lead; Lecithin; Link; Lipid Binding; Lipids; Liver; Liver diseases; Measures; Mediating; Medication Management; Membrane; Metabolic; Mission; Molecular; Mus; National Institute of Diabetes and Digestive and Kidney Diseases; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Outcome Study; Pathway interactions; Phenotype; Phospholipids; Physiological; Play; Prevention; Proteins; Public Health; Reagent; Recombinants; Regulation; Research; Research Proposals; Resistance; Role; Small Interfering RNA; Surface Plasmon Resonance; Testing; Tissues; Tuberous sclerosis protein complex; Tunicamycin; blood glucose regulation; endoplasmic reticulum stress; glucose metabolism; glucose production; improved; insulin sensitivity; insulin signaling; lipid metabolism; loss of function; member; new therapeutic target; non-alcoholic fatty liver; novel; novel therapeutic intervention; phosphatidylcholine transfer protein; polyunsaturated phosphatidylcholine; protein complex; protein function; research study; response; sensor

DESCRIPTION (provided by applicant): Obesity-induced resistance to insulin action is the primary pathophysiological defect that predisposes to type 2 diabetes and non-alcoholic fatty liver disease (NAFLD). Because current management options remain limited, identification of new regulatory mechanisms that govern the metabolic response to insulin should serve to identify novel opportunities for pharmacologic intervention. The objective of this research is to explore the role of membrane phosphatidylcholine (PC) composition in the regulation of hepatic lipid and glucose metabolism. The rationale is that the identification of a novel mechanism that regulates hepatic insulin sensitivity could lead to the identification of new therapeutic targets for the treatment of NAFLD and type 2 diabetes. Guided by extensive preliminary data, the central hypothesis of this research plan is that phosphatidylcholine transfer protein (PC-TP) functions as a sensor of PC molecular species and controls glucose homeostasis by forming a regulatory complex together with thioesterase superfamily member 2 (THEM2) and tuberous sclerosis complex 2 (TSC2), which modulates insulin signaling potentialy via endoplasmic reticulum (ER) stress. This will be tested in two specific aims: 1) Define the mechanisms by which PC-TP and THEM2 regulate insulin signaling through TSC2 interactions; 2) Determine the role of PC molecular species on binding and activation of THEM2 and TSC2 by PC-TP. In aim 1, the effect of siRNA-mediated silencing of PC-TP and THEM2 expression on insulin signaling will be determined in cell culture systems by measuring the activity of key effectors. The role of TSC2 in the PC-TP- and THEM2-mediated regulation of insulin signaling will be probed in cell lines lacking TSC2 expression. The potential roles of PC-TP and THEM2 in the induction of ER stress will be studied using chemical reagent tunicamycin in cultured cells and prolonged high-fat diet in Pctp-/- and Them2-/- mice. It is anticipated that PC-TP and THEM2 will regulate hepatocellular insulin signaling directly both by forming a novel protein complex with TSC2 and by modulating ER stress. This is important because increased ER stress is associated with development of insulin resistance in association with obesity. In aim2, the influence of PC molecular species on the interactions between purified recombinant PC-TP and THEM2 or TSC2 will be examined in vitro by puldown assays and by surface plasmon resonance. The efect of the PC molecular species bound to PC-TP on the activity regulation of THEM2 and TCS2 will be detected in vitro by measuring their fatty acyl-CoA thioesterase and GAP activity, respectively. We expect that polyunsaturated PC molecular species bound to PC-TP will promote interactions with THEM2 and TSC2 and stimulate the activity of these proteins. Overall, this proposal will elucidate mechanisms by which membrane phospholipid composition regulates glucose metabolism, which is significant because the faty acyl composition of the membrane phosphatidylcholines varies in health and disease. These studies are expected to identify new therapeutic targets for the management of type 2 diabetes and NAFLD.

描述（由申请方提供）：肥胖诱导的胰岛素抵抗是导致2型糖尿病和非酒精性脂肪肝（NAFLD）的主要病理生理缺陷。由于目前的管理选择仍然有限，确定新的调节机制，管理胰岛素的代谢反应，应有助于确定新的机会，药物干预。本研究的目的是探讨膜磷脂酰胆碱（PC）成分在肝脏脂糖代谢调节中的作用。其基本原理是，确定一种调节肝脏胰岛素敏感性的新机制可能导致确定治疗NAFLD和2型糖尿病的新治疗靶点。本研究计划的中心假设是，磷脂酰胆碱转运蛋白（PC-TP）作为PC分子种类的传感器，通过与硫酯酶超家族成员2（THEM 2）和结节性硬化症复合物2（TSC 2）一起形成调节复合物来控制葡萄糖稳态，该复合物可能通过内质网（ER）应激来调节胰岛素信号传导。这将在两个具体目标中进行测试：1）定义PC-TP和THEM 2通过TSC 2相互作用调节胰岛素信号传导的机制; 2）确定PC分子种类对THEM 2和TSC 2通过PC-TP的结合和活化的作用。在目的1中，将通过测量关键效应物的活性来确定细胞培养系统中siRNA介导的PC-TP和THEM 2表达沉默对胰岛素信号传导的影响。将在缺乏TSC 2表达的细胞系中探索TSC 2在PC-TP和THEM 2介导的胰岛素信号传导调节中的作用。将在培养的细胞中使用化学试剂衣霉素并在Pctp-/-和Them 2-/-小鼠中延长高脂饮食来研究PC-TP和Them 2在ER应激诱导中的潜在作用。预期PC-TP和THEM 2将通过与TSC 2形成新的蛋白质复合物和通过调节ER应激直接调节肝细胞胰岛素信号传导。这一点很重要，因为ER应激增加与肥胖相关的胰岛素抵抗的发展有关。在aim 2中，PC分子种类对纯化的重组PC-TP和THEM 2或TSC 2之间的相互作用的影响将通过下拉测定和表面等离子体共振在体外进行检查。通过分别测定THEM 2和TCS 2的脂肪酰辅酶A硫酯酶和GAP活性，体外检测与PC-TP结合的PC分子种类对THEM 2和TCS 2活性调节的影响。我们预计，结合到PC-TP的多不饱和PC分子种类将促进与THEM 2和TSC 2的相互作用，并刺激这些蛋白质的活性。总的来说，这个建议将阐明膜磷脂组合物调节葡萄糖代谢的机制，这是重要的，因为膜磷脂酰胆碱的脂肪酰基组合物在健康和疾病中变化。这些研究有望为2型糖尿病和NAFLD的管理确定新的治疗靶点。