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: 8200744
• 负责人: Baran Ersoy
• 金额: $ 5.58万
• 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/8200744
• 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. PUBLIC HEALTH RELEVANCE: The proposed studies will examine the mechanism by which a novel protein complex regulates hepatic glucose metabolism in response to changes in the composition of cell membranes. This research is relevant to public health because it is anticipated that the results will improve our understanding of the relationships between obesity and insulin resistance. The proposed studies are relevant to the mission of the NIDDK because they are expected to identify new therapeutic approaches for the management of common disorders related to insulin resistance.

描述（由申请人提供）：肥胖引起的胰岛素作用抵抗是易患 2 型糖尿病和非酒精性脂肪肝 (NAFLD) 的主要病理生理缺陷。由于当前的管理选择仍然有限，因此确定控制胰岛素代谢反应的新调节机制应有助于确定药物干预的新机会。本研究的目的是探讨膜磷脂酰胆碱（PC）成分在肝脂质和葡萄糖代谢调节中的作用。其基本原理是，调节肝脏胰岛素敏感性的新机制的确定可能有助于确定治疗 NAFLD 和 2 型糖尿病的新治疗靶点。在大量初步数据的指导下，该研究计划的中心假设是磷脂酰胆碱转移蛋白（PC-TP）作为PC分子种类的传感器发挥作用，并通过与硫酯酶超家族成员2（THEM2）和结节性硬化症复合体 2 (TSC2)，可通过内质网 (ER) 应激调节胰岛素信号传导。这将在两个具体目标上进行测试：1）定义 PC-TP 和 THEM2 通过 TSC2 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PC-TP结合和激活THEM2和TSC2的作用。在目标 1 中，将通过测量关键效应子的活性来确定细胞培养系统中 siRNA 介导的 PC-TP 和 THEM2 表达沉默对胰岛素信号传导的影响。将在缺乏 TSC2 表达的细胞系中探讨 TSC2 在 PC-TP 和 THEM2 介导的胰岛素信号传导调节中的作用。将使用培养细胞中的化学试剂衣霉素和 Pctp-/- 和 Them2-/- 小鼠的长期高脂肪饮食来研究 PC-TP 和 THEM2 在诱导 ER 应激中的潜在作用。预计 PC-TP 和 THEM2 将通过与 TSC2 形成新型蛋白质复合物以及调节 ER 应激来直接调节肝细胞胰岛素信号传导。这很重要，因为内质网应激的增加与肥胖相关的胰岛素抵抗的发展有关。在 Target2 中，PC 分子种类对纯化重组 PC-TP 与 THEM2 或 TSC2 之间相互作用的影响将通过 Pulldown 测定和表面等离振子共振在体外进行检查。与 PC-TP 结合的 PC 分子种类对 THEM2 和 TCS2 活性调节的影响将通过分别测量其脂肪酰基辅酶 A 硫酯酶和 GAP 活性在体外检测。我们预计与 PC-TP 结合的多不饱和 PC 分子种类将促进与 THEM2 和 TSC2 的相互作用并刺激这些蛋白质的活性。总体而言，该提案将阐明膜磷脂成分调节葡萄糖代谢的机制，这很重要，因为膜磷脂酰胆碱的脂肪酰基成分在健康和疾病中会有所不同。这些研究有望确定治疗 2 型糖尿病和 NAFLD 的新治疗靶点。 公共健康相关性：拟议的研究将研究一种新型蛋白质复合物响应细胞膜组成的变化而调节肝葡萄糖代谢的机制。这项研究与公共卫生相关，因为预计结果将增进我们对肥胖与胰岛素抵抗之间关系的理解。拟议的研究与 NIDDK 的使命相关，因为它们有望找到新的治疗方法来管理与胰岛素抵抗相关的常见疾病。