ABCs of Cholesterol Regulation in the Insulin Secretory Pathway

胰岛素分泌途径中胆固醇调节的基础知识

基本信息

批准号：
8856221
负责人：
John David Castle
金额：
$ 34.37万
依托单位：
UNIVERSITY OF VIRGINIA
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-09-01 至 2017-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8856221
关键词：
ATP binding cassette transporter 1 ATP phosphohydrolase ATP-Binding Cassette Transporters Address Affect Anabolism Area B-Lymphocytes Biochemical Biological Biological Assay Cell Line Cells Cholesterol Cholesterol Homeostasis Collaborations Complement Cytoplasmic Granules Data Defect Diabetes Mellitus Docking Endocrine Equilibrium Etiology Exocytosis Failure Figs - dietary Fluorescence Microscopy Genetic Glucose Goals Health Homeostasis Image Insulin Investigation Islet Cell Islets of Langerhans Life Lipids Lipoproteins Membrane Microscopic Modeling Non-Insulin-Dependent Diabetes Mellitus Pancreas Pathway interactions Plasma Procedures Process Proteins Regulation Research Role Secretory Vesicles Series Sorting - Cell Movement Testing Thiazolidinediones Time Work aminophospholipid transporter analog base biophysical techniques cell type diabetic genetic regulatory protein glucose tolerance humoral immunity deficiency impaired glucose tolerance insulin granule insulin secretion insulinoma islet prospective protein function response restoration translocase two-photon uptake

项目摘要

DESCRIPTION (provided by applicant): This proposal addresses a new area in diabetes-related research regarding cholesterol distribution and its regulatory roles in the insulin secretory pathway. Recent studies including those forming the basis of this proposal have shown that deficiencies in pancreatic � cells in the ATP-binding cassette transporters ABCA1 and ABCG1, which have been implicated to promote cellular export of cholesterol to plasma lipoproteins by most cell types, impair systemic glucose tolerance through inhibition of insulin secretion. Moreover, expression of these transporters is reduced in models of type 2 diabetes and also figures in glucose sensitivity in response to anti-diabetic thiazolidinediones. Detailed analysis of ABCG1 in islet cells and islet-derived cell lines has shown unexpectedly that this transporter mostly resides in the membranes of insulin granules; its deficiency leads to enlargement of granules, reduced granule cholesterol content and reduced ability of granules to undergo exocytosis in response to glucose or K+ stimulation. It appears as if granule formation and/or maturation are perturbed. Preliminary findings show that ABCA1 also localizes to granules and that its deficiency causes similar intracellular effects as caused by reduced ABCG1. Strikingly, all changes elicited by ABCG1 deficiency are reversed by addition of exogenous cholesterol, identifying cholesterol as the likely common denominator. Taken together, these observations have led to the working hypothesis that ABCG1, in collaboration with ABCA1 and other lipid regulatory proteins, functions in the formation of insulin granules by promoting assembly of a cholesterol-enriched limiting membrane that is able to support the sorting and export activities of the regulated secretory pathway. To explore this hypothesis, a combination of cell biological and biochemical/biophysical approaches will be used on pancreatic islet derived cells and insulinoma cell lines to pursue four specific aims. First, ABCA1's functions alongside ABCG1 in insulin's secretory pathway will be tested using procedures already successfully applied to ABCG1. Second, lipid composition and protein sorting activities within the secretory pathway will be examined to evaluate the roles of the two ABCs in cholesterol dependent granule formation/maturation. Third, using isolated insulin granule fractions, fluorescent lipid analogs will be employed to assay ABC transporter and related lipid translocation mechanisms that are thought to contribute to insulin granule formation. Fourth, real-time microscopic imaging will be used to identify the level(s) at which ABC deficiency affects insulin granule exocytosis. The proposed studies highlight the insulin granule as a major cholesterol regulatory compartment; they represent the first exploration of intracellular roles of ABCs A1 and G1 that are unrelated to cellular cholesterol efflux; and they complement ongoing investigations by others seeking to understand mechanisms of insulin granule exocytosis and perturbations that might relate to � cell failure in type 2 diabetes.

描述（由申请人提供）：该提案涉及与糖尿病相关的娱乐活动中有关Cholestol分布的新区域，胰岛素分泌途径是ATP结合盒ABCA1和ABCG1的胰岛素分泌途径。 OST细胞类型将胆固醇的出口到血浆脂肪素，损害全身性葡萄糖抑制作用，对2型糖尿病的S分泌。颗粒的胰岛素颗粒，对葡萄糖的反应或颗粒的刺激，就像颗粒的形成一样。，将胆固醇确定为可能的共同点。假设ND生物化学/生物物理方法将与ABCG1一起在胰岛素的秘密意愿过程中使用ABCG1成功地应用于ABCG1 ，胰岛素分数将用于测定ABC转运蛋白和相关的脂质易位HANISP，这些脂质易位有助于胰岛素颗粒的形成REPRESENT THE First EXPLORATION OFCS ABCS ABCS ABCS ABCS ABCS ABCS ABCS ABCS ABCS ABCS ABCS ABCS ATIONS BY OTHERS SEEKING TO UNDERSTAND MECHANISMS of INSULIN GRANULE EXOCYTOSIS AND PERTURBATIONS THAT MIGHT RELATE to