Regulatory Mechanisms of GLUT4 Exocytosis

GLUT4胞吐作用的调控机制

• 批准号: 8828678
• 负责人: Jingshi Shen
• 金额: $ 33.17万
• 依托单位: UNIVERSITY OF COLORADO
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8828678
• 关键词: Address; Adipocytes; Adipose tissue; Biological Assay; Biological Models; Blood Glucose; C2 Domain; Cell surface; Cells; Chimeric Proteins; Complex; Data; Development; Diet; Disease; Epidemic; Exocytosis; Fatty acid glycerol esters; Fluorescence Resonance Energy Transfer; GLUT4 gene; Glucose; Glucose Transporter; Goals; Health; Insulin; Insulin Resistance; Kinetics; Knockout Mice; Knowledge; Light; Liposomes; Measures; Mediating; Membrane; Membrane Fusion; Molecular; Munc18c protein; Mus; Muscle; N-terminal; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Pathogenesis; Pathway interactions; Physiological; Play; Process; Proteins; Reaction; Recombinant Proteins; Research; Role; SNAP receptor; System; Therapeutic Intervention; Vesicle; Work; base; biophysical analysis; blood glucose regulation; feeding; glucose uptake; in vivo; insulin secretion; loss of function mutation; novel; novel strategies; reconstitution; syntaxin binding protein 1

DESCRIPTION (provided by applicant): As the epidemic of insulin resistance and type 2 diabetes emerges worldwide, there is an urgent need to understand how insulin maintains blood glucose homeostasis at the molecular level. A major function of insulin is to promote glucose uptake into muscle and adipose tissues, a process mediated by the glucose transporter GLUT4. Upon insulin stimulation, GLUT4 is relocated from intracellular storage vesicles to the cell surface through regulated exocytosis. The exocytosis of GLUT4 vesicles requires the SNARE proteins as the core fusion machinery, as well as a group of fusion regulators. Loss-of-function mutations of the SNAREs or fusion regulators abrogate insulin-triggered GLUT4 exocytosis and disrupt blood glucose homeostasis. Moreover, imbalances in the GLUT4 vesicle fusion proteins have been implicated in obesity-associated insulin resistance. While the physiological importance of the SNAREs and fusion regulators is clear, it remains poorly understood how they act in concert to mediate and regulate GLUT4 vesicle fusion. The overall goal of this proposal is to answer this key question using novel and complementary approaches. We will first define the molecular mechanisms and functional interactions of the vesicle fusion proteins using a novel reconstituted fusion system. We will use both recombinant proteins and native proteins isolated from mouse adipocytes. We will then characterize GLUT4 vesicle fusion proteins in 3T3-L1 adipocytes and in adipocytes isolated from knockout mice. Finally, we will determine whether and how the activities of the vesicle fusion proteins are impaired in insulin resistance, using hig fat diet-fed mice as a model system. If successfully accomplished, this research will substantially broaden our knowledge about the regulatory mechanisms of GLUT4 exocytosis. The findings will also shed light upon the diseases associated with glucose imbalances such as insulin resistance and type 2 diabetes, and will facilitate the development of novel strategies for therapeutic intervention.

描述（由申请人提供）：随着胰岛素抵抗的流行和2型糖尿病的流行，全世界都出现了，迫切需要了解胰岛素如何在分子水平上保持血糖稳态。胰岛素的主要功能是促进葡萄糖吸收肌肉和脂肪组织，这是由葡萄糖转运蛋白Glut4介导的过程。胰岛素刺激后，通过调节的胞吐作用将GLUT4从细胞内存储囊泡重新定位到细胞表面。 Glut4囊泡的胞吐作用需要核心蛋白作为核心融合机械以及一组融合调节剂。网罗或融合调节剂的功能丧失突变消除了胰岛素触发的GLUT4胞吐作用并破坏血糖稳态。此外，GLUT4囊泡融合蛋白的失衡已与肥胖相关的胰岛素抵抗有关。虽然SNARES和融合调节剂的生理重要性很明显，但仍然很糟糕地了解它们如何共同调节和调节Glut4囊泡融合。该提案的总体目标是使用新颖和互补方法回答这个关键问题。我们将首先使用新型的重构融合系统来定义囊泡融合蛋白的分子机制和功能相互作用。我们将使用从小鼠脂肪细胞分离的重组蛋白和天然蛋白。然后，我们将表征3T3-L1脂肪细胞中的Glut4囊泡融合蛋白以及从基因敲除小鼠分离的脂肪细胞中。最后，我们将使用希格脂肪饮食喂养的小鼠作为模型系统来确定囊泡融合蛋白的活性以及如何在胰岛素抵抗中受损。如果成功完成，这项研究将大大扩大我们对GLUT4胞吐作用的调节机制的了解。这些发现还将阐明与葡萄糖失衡相关的疾病，例如胰岛素抵抗和2型糖尿病，并促进发展新型策略的发展 治疗干预。