Sec61 and ER Stress in Beta-cell Function and Type 2 Diabetes

β 细胞功能和 2 型糖尿病中的 Sec61 和 ER 应激

• 批准号: 7652064
• 负责人: Nicholas Gekakis
• 金额: $ 47.48万
• 依托单位: SCRIPPS RESEARCH INSTITUTE, THE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7652064
• 关键词: Affect; Age; Animals; Apoptosis; Autopsy; Beta Cell; Candidate Disease Gene; Cell Death; Cell physiology; Cells; Data; Defect; Development; Diabetes Mellitus; Diabetic mouse; Electron Microscopy; Endoplasmic Reticulum; Failure; Family; Functional disorder; Genes; Genetic; Genetic Predisposition to Disease; Genetic Screening; Human; Human Genetics; Insulin Resistance; Lead; Literature; Maps; Molecular Chaperones; Mus; Mutant Strains Mice; Mutation; Nature; Non-Insulin-Dependent Diabetes Mellitus; Oxidative Stress; Pancreas; Peripheral; Pharmaceutical Preparations; Phenotype; Play; Process; Prospective Studies; Protein Import; Protein translocation; Proteins; Relative (related person); Role; Syndrome; Testing; Tissues; Up-Regulation; Yeasts; cytokine; design; diabetic; endoplasmic reticulum stress; genome wide association study; insulin secretion; mouse model; mutant; neonatal diabetes mellitus; novel; protein folding; public health relevance; research study; response; transcription factor

DESCRIPTION (provided by applicant): In a phenotype-driven, genetic screen to identify novel genes that affect ¿-cell function, we found a mutation in Sec61a1 in a family of mice with diabetes. Sec61a1 encodes the protein conducting subunit of the endoplasmic reticulum (ER) translocation channel, which is responsible for protein import into the ER. Diabetes in Sec61a1 mutant mice is correlated with ¿-cell apoptosis and massively distended ER. The distended ER is consistent with ER stress, an accumulation of unfolded proteins within the ER. The cell mounts a response to ER stress, the unfolded protein response, which includes up regulation of protein folding chaperones (e.g. Bip), and, in the case that ER stress cannot be relieved, up regulation of the proapoptotic transcription factor Chop. Bip and Chop are both up regulated in diabetic Sec61a1 mutant animals. Thus, our hypothesis is that Sec61a1 mutation leads to ER stress, ¿-cell apoptosis, and diabetes. The experiments in this proposal are designed to test this hypothesis, to understand the mechanism by which Sec61a1 mutation leads to ER stress, and to ask if ER stress plays a role in the ¿-cell dysfunction that is part of type 2 diabetes. PUBLIC HEALTH RELEVANCE: The development of type 2 diabetes (T2D) is a two-hit process involving insulin resistance in peripheral tissues and a failure of pancreatic ¿-cells to compensate for insulin resistance by increased insulin secretion. Prospective studies in humans have established the causative role of both insulin resistance and ¿-cell dysfunction in T2D. What is the nature of the ¿-cell failure that accompanies T2D? Autopsy studies have shown that T2D is associated with a relative decrease in ¿-cell mass due to apoptosis, a finding that has been supported in mouse models. There is evidence in the literature to support any of several mechanisms of ¿-cell loss, including oxidative stress, glucotoxicity, lipotoxicity, and cytokine-induced cell death. In these studies we will examine the role of endoplasmic reticulum (ER) stress and ER stress-induced apoptosis in ¿- cell dysfunction. Evidence for a role of ER stress in ¿-cell death comes from human genetic syndromes marked by neonatal diabetes, and various mouse models including a novel mouse model of diabetes from our own lab. Via a forward genetic approach in the mouse, we have identified a family of diabetic mice with a mutation in the ER translocation channel protein Sec61a1. Preliminary data indicate that the mice become diabetic because they lose ¿-cells beginning at about four weeks of age. This loss correlates with an increase in ER stress. The mechanism of ER stress likely relates to a defect in protein processing or degradation due to the Sec6a1 mutation. The studies described herein seek to exploit this and other mouse models of diabetes to answer some fundamental questions about the nature of ¿-cell dysfunction in T2D. How does this mutation in Sec61a1 lead to ER stress, ¿-cell apoptosis, and diabetes and does ER stress play a role in the ¿- cell dysfunction normally seen in T2D? It is hoped that an increased understanding of ¿-cell dysfunction will lead to more effective drugs against T2D.

描述（由申请人提供）：在表型驱动的遗传筛选中识别影响 ¿ -细胞功能，我们在糖尿病小鼠家族中发现了 Sec61a1 的突变，该突变编码内质网 (ER) 易位通道的蛋白质传导亚基，该亚基负责 Sec61a1 突变小鼠的 ER 中的蛋白质输入。与 ¿ 相关-细胞凋亡和内质网大量扩张。扩张的内质网与内质网应激一致，即内质网内未折叠蛋白的积累。细胞对内质网应激产生反应，即未折叠蛋白反应，其中包括蛋白折叠伴侣的上调。 Bip)，并且，在 ER 应激无法缓解的情况下，促凋亡转录因子 Bip 和 Chop 的上调在糖尿病患者中均上调。 Sec61a1 突变动物因此，我们的假设是 Sec61a1 突变导致 ER 应激，¿本提案中的实验旨在检验这一假设，了解 Sec61a1 突变导致 ER 应激的机制，并探讨 ER 应激是否在 ¿ -细胞功能障碍是 2 型糖尿病的一部分。 公共卫生相关性：2 型糖尿病 (T2D) 的发展是一个双重打击过程，涉及外周组织的胰岛素抵抗和胰腺功能衰竭。 -细胞通过增加胰岛素分泌来补偿胰岛素抵抗 人类前瞻性研究已经确定了胰岛素抵抗和 ¿ -T2D 细胞功能障碍的本质是什么？ - 伴随 T2D 的细胞衰竭？尸检研究表明 T2D 与 ¿ - 细胞凋亡导致的细胞质量，这一发现已在小鼠模型中得到支持。文献中有证据支持 ¿ 的几种机制中的任何一种。 -细胞损失，包括氧化应激、糖毒性、脂毒性和细胞因子诱导的细胞死亡。在这些研究中，我们将研究内质网 (ER) 应激和 ER 应激诱导的细胞凋亡的作用。 - 内质网应激在 ¿ 中发挥作用的证据。 -细胞死亡来自以新生儿糖尿病为标志的人类遗传综合征，以及各种小鼠模型，包括我们自己实验室的新型糖尿病小鼠模型。通过小鼠的正向遗传方法，我们已经鉴定出一个具有突变的糖尿病小鼠家族。 ER 易位通道蛋白 Sec61a1 的初步数据表明，小鼠患糖尿病是因为它们失去了 ¿ -细胞在大约四周龄时开始。这种损失与内质网应激的增加相关。内质网应激的机制可能与由于 Sec6a1 突变导致的蛋白质加工或降解缺陷有关。其他糖尿病小鼠模型可以回答有关糖尿病本质的一些基本问题 ¿ -T2D 中的细胞功能障碍如何导致 ER 应激？ -细胞凋亡、糖尿病以及内质网应激是否在其中发挥作用？ - T2D 中常见的细胞功能障碍希望增加对 ¿ -细胞功能障碍将导致更有效的抗T2D药物的出现。