Proinsulin ER export and beta cell ER homeostasis in health and diabetes

健康和糖尿病中胰岛素原 ER 输出和 β 细胞 ER 稳态

• 批准号: 9135632
• 负责人: Xuequn Chen
• 金额: $ 15.3万
• 依托单位: WAYNE STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-15 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9135632
• 关键词: Address; Affect; Animal Model; Apoptosis; Beta Cell; Biogenesis; Biological Assay; Capsid Proteins; Cell Death; Cell Line; Cell Survival; Cell physiology; Cellular biology; Chronic; Coated vesicle; Coupled; Defect; Development; Diabetes Mellitus; Diabetic mouse; Endoplasmic Reticulum; Enzymes; Equilibrium; Failure; Functional disorder; GTP Binding; Genes; Genetic; Glucose; Golgi Apparatus; Guanosine Triphosphate Phosphohydrolases; Health; Homeostasis; Human; In Vitro; Insulin; Islet Cell; Knowledge; Lipids; Measures; Membrane; Molecular; Molecular Chaperones; Monitor; Non-Insulin-Dependent Diabetes Mellitus; Organelles; Pathogenesis; Pathway interactions; Physiological; Play; Positioning Attribute; Process; Production; Proinsulin; Protein Biosynthesis; Protein Export Pathway; Proteins; Proteomics; Rodent; Role; Structure of beta Cell of islet; Systems Biology; Techniques; Testing; Time; Toxic effect; United States; Vesicle; Western Blotting; base; diabetic; endoplasmic reticulum stress; genome wide association study; immunocytochemistry; innovation; islet; novel; novel therapeutics; protein complex; protein folding; type I and type II diabetes

 DESCRIPTION (provided by applicant): Up to date, most of the diabetes-associated genes identified in genome-wide association studies are enriched in the pancreatic beta cells. Beta cell failure plays a central role in the development and progression of type 2 diabetes (T2D). The endoplasmic reticulum (ER) is a central organelle for the massive production and processing of proinsulin. ER homeostasis is critical for normal beta cell function and is maintained by the delicate balance between protein synthesis, folding, export and degradation. In contrast, the disruption of ER homeostasis, by many genetic and environmental diabetes-causing factors, induces ER stress and causes beta cell death in T2D. Compared to our knowledge in protein synthesis, folding and degradation in beta cell ER, the role of ER export in proinsulin biogenesis and ER homeostasis is much less understood. This proposal addresses this knowledge gap. We have obtained strong preliminary results demonstrating that ER exit of proinsulin requires COPII (coat protein complex II) coated vesicles and defective COPII dependent ER export strongly induces ER stress. In addition to our results, evidence has recently begun to emerge that reduced ER-Golgi transport is causative to lipotoxicity-induced ER stress in beta cells. On the basis of these novel findings, we aim to determine how glucose- and lipid-toxicity affect the ER export of protein cargo, particularly proinsulin, in beta cells and how defective ER export, in turn, contributes to ER stress and beta cell dysfunction. Over a thousand proteins, referred to as the proteostasis network, have been proposed to maintain ER homeostasis. However, to date, only a very small number of ER proteins have been investigated for their involvement in ER stress or proinsulin biogenesis in beta cells. A systematic proteomics analysis is needed to comprehensively understand how different diabetes-causing conditions perturb beta cell ER homeostasis at the onset of T2D. In this proposal, using systems biology approaches, we will test the central hypothesis that diabetogenic factors such as glucolipotoxicity disrupt beta cell ER function through perturbing ER protein homeostasis and COPII dependent ER export. There are two specific aims in this proposal: 1) Determine how COPII dependent ER export is regulated in health and diabetes; 2) Determine how ER chaperones and folding enzymes are altered in diabetes and how these changes affect beta cell ER export. This study will use state-of-the-art quantitative proteomics and other systems biology approaches to characterize the molecular mechanisms by which diabetes-causing conditions differentially alter ER homeostasis. The emphasis will be on the ER export, an under-investigated component of beta cell ER homeostasis.

 描述（由申请人提供）：迄今为止，在全基因组关联研究中鉴定的大多数糖尿病相关基因在胰腺β细胞中富集。β细胞衰竭在2型糖尿病（T2 D）的发展和进展中起着核心作用。内质网（ER）是胰岛素原大量产生和加工的中心细胞器。ER稳态对于正常β细胞功能至关重要，并且通过蛋白质合成、折叠、输出和降解之间的微妙平衡来维持。相比之下，许多遗传和环境糖尿病引起因素对ER稳态的破坏，诱导ER应激并导致T2 D中的β细胞死亡。相对于我们对β细胞ER中蛋白质合成、折叠和降解的了解，ER输出在胰岛素原生物合成和ER稳态中的作用还不太清楚。本建议弥补了这一知识差距。我们已经获得了强有力的初步结果表明，ER退出胰岛素原需要COPII（外壳蛋白复合物II）包被的囊泡和有缺陷的COPII依赖ER出口强烈诱导ER应力。除了我们的研究结果，最近开始出现的证据表明，减少ER-高尔基体运输是导致脂毒性诱导的ER压力β细胞。在这些新发现的基础上，我们的目标是确定葡萄糖和脂质毒性如何影响β细胞中蛋白质货物，特别是胰岛素原的ER输出，以及有缺陷的ER输出如何反过来导致ER应激和β细胞功能障碍。已经提出了超过一千种蛋白质，称为蛋白质稳态网络，以维持ER稳态。然而，到目前为止，只有非常少的ER蛋白质已被调查，他们参与ER应激或胰岛素原在β细胞的生物合成。需要进行系统的蛋白质组学分析，以全面了解不同的糖尿病引起的条件如何在T2 D发病时扰乱β细胞ER稳态。在这个建议中，使用系统生物学方法，我们将测试的核心假设，糖尿病的因素，如糖脂毒性破坏β细胞ER功能，通过扰乱ER蛋白稳态和COPII依赖的ER出口。该提案有两个具体目标：1）确定COPII依赖性ER输出在健康和糖尿病中如何调节; 2）确定ER伴侣和折叠酶在糖尿病中如何改变以及这些变化如何影响β细胞ER输出。这项研究将使用最先进的定量蛋白质组学和其他系统生物学方法来表征糖尿病引起的条件差异改变ER稳态的分子机制。重点将放在ER出口，一个研究不足的β细胞ER稳态的组成部分。