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）：肥胖引起的对胰岛素作用的耐药性是易感2型糖尿病和非酒精性脂肪肝疾病（NAFLD）的主要病理生理缺陷。由于当前管理方案仍然有限，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理干预的新机会。这项研究的目的是探索膜磷脂酰胆碱（PC）组成在调节肝脂质和葡萄糖代谢中的作用。理由是，调节肝胰岛素敏感性的新型机制的鉴定可以导致鉴定出治疗NAFLD和2型糖尿病的新治疗靶标。 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网状（ER）应力。这将以两个特定的目的进行测试：1）定义PC-TP和THEM2通过TSC2相互作用调节胰岛素信号的机制； 2）确定PC分子物种在PC-TP通过PC-TSC2结合和激活的作用。在AIM 1中，通过测量关键效应子的活性，将在细胞培养系统中确定siRNA介导的PC-TP和HET2表达对胰岛素信号传导的影响。在缺乏TSC2表达的细胞系中，将探测TSC2在PC-TP及其2介导的胰岛素信号传导调节中的作用。 PC-TP和它们2在培养细胞中的化学试剂中，将研究PC-TP和HET2在诱导ER应激中的潜在作用，并在PCTP-/ - 和tum2-/ - 小鼠中延长高脂饮食。可以预料，PC-TP和HET2将通过与TSC2形成新型蛋白质复合物并通过调节ER应力来直接调节肝细胞胰岛素信号传导。这很重要，因为增加的ER应激与肥胖相关的胰岛素抵抗的发展有关。在AIM2中，PC分子物种对纯化的重组PC-TP与TSC2之间相互作用的影响将通过脉冲测定和表面等离子体共振在体外检查。将分别通过测量其脂肪酰基-COA硫酯酶和GAP活性来检测到与PC-TP的PC分子物种的效率。我们期望与PC-TP结合的多不饱和PC分子物种将促进与它们的相互作用2和TSC2，并刺激这些蛋白质的活性。总体而言，该提案将阐明膜磷脂组成调节葡萄糖代谢的机制，这很重要，因为膜磷脂酰胆碱的胖酰基组成在健康和疾病上会有所不同。预计这些研究将确定2型糖尿病和NAFLD管理的新治疗靶标。 公共卫生相关性：拟议的研究将检查新型蛋白质复合物对细胞膜组成变化的响应而调节肝葡萄糖代谢的机制。这项研究与公共卫生有关，因为预计结果将提高我们对肥胖和胰岛素抵抗之间关系的理解。拟议的研究与NIDDK的使命有关，因为他们有望确定与胰岛素抵抗相关的常见疾病的治疗的新治疗方法。