Regulating stress response to promote postnatal beta-cell function and survival

调节应激反应以促进产后 β 细胞功能和存活

• 批准号: 10580784
• 负责人: Guoqiang Gu
• 金额: $ 48.71万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10580784
• 关键词: 5' Flanking Region; ATF6 gene; Adult; Affect; Anabolism; Apoptotic; Attenuated; Beta Cell; Cell Death; Cell Line; Cell Proliferation; Cell Survival; Cell Transplantation; Cell physiology; Cells; Cessation of life; ChIP-seq; Compensation; Complex; Development; Diabetes Mellitus; Disease; Down-Regulation; Failure; Family; Functional disorder; Gene Activation; Gene Expression; Genes; Genetic Transcription; Glucose; Glucose Intolerance; Goals; Heat-Shock Response; Histone Deacetylase; Histone Deacetylation; Histones; Homeostasis; Human; Hyperglycemia; Hypoglycemia; Immunodeficient Mouse; In Vitro; Insulin; Insulin Resistance; Interruption; Islet Cell; Islets of Langerhans; Knowledge; Lead; Link; Mediating; Messenger RNA; Metabolic; Metabolic stress; Mitochondria; Modeling; Molecular; Molecular Target; Mus; Myelin; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Open Reading Frames; Output; Oxidative Stress; Peripheral; Persons; Physiology; Process; Production; Proinsulin; Proteins; Proteomics; Publishing; Reactive Oxygen Species; Regulation; Repression; Role; Stress; Structure of beta Cell of islet; Testing; Tissues; Translations; Up-Regulation; Workload; biological adaptation to stress; blood glucose regulation; derepression; gain of function; gene product; gene repression; glucose metabolism; improved; in vivo; in vivo evaluation; insulin secretion; islet; islet stem cells; knock-down; loss of function; novel; paralogous gene; postnatal; prevent; recruit; response; stressor; transcription factor; transcriptome sequencing

Workload-induced pancreatic islet β-cell dysfunction, loss-of identity, and cell death, commonly known as β-cell failure, is the hallmark of type 2 diabetes (T2D). This disease usually starts with obesity-induced insulin resistance, when peripheral tissues need higher levels of circulating insulin for glucose storage and usage. Islet β-cells compensate by expanding β-cell mass and increasing insulin output per cell, which requires upregulated insulin biosynthesis and oxidative glucose metabolism. These produce unfolded proinsulin in the ER and reactive oxygen species (ROS) in mitochondria, which at high levels can decimate β cells. Thus, β cells constantly activate stress response by stimulating the activity of several early-stage SRGs, including Atf6, IRE1, PERK, Hsf1, and Nurf2, to lead to: 1) attenuated overall protein translation; 2) enhanced translation of some SRG mRNAs that have special features such as upstream open reading frame (uORF) 5’ to the main ORF; 3) upregulated expression of some late-stage SRGs. The overall effect of these responses is to remove unfolded proteins/ROS for proteomic homeostasis and sustainable β-cell function. However, over-activating some late-stage SRGs such as Atf4 and Hsps induces β-cell failure by turning on some proapoptotic genes or by exceedingly lowering overall protein translation. Thus, it is imperative for β-cells to limit the levels of failure- causing SRGs for sustainable high-level of insulin output. An emerging model from our recent published findings is that a transcriptional complex containing Myt TFs and Sin3 can selectively repressing these failure- causing SRGs. Myt TFs are a family of three myelin transcription factors (Myt1, 2, and 3) highly expressed in islet cells. Sin3, including Sin3a and Sin3b, is a coregulator that represses transcription by recruiting histone deacetylases (HDACs) to modify histones. We showed that Myt TFs and Sin3 can form a transcription complex in β cells. Inactivating these genes in mouse and human β cells causes cell dysfunction and/or death while overactivating late-stage β-cell-failure-causing SRGs but not early stage SRGs. Intriguingly, Myt TFs, particularly Myt3, is induced by obesity-related stressors in mouse and human β cells, likely mediated by an uORF in 5’ flanking region of Myt3 mRNA. Importantly, MYT3 down-regulation accompanies human β-cell failure in T2D development. Our overarching hypothesis is that the stress-responsive Myt TFs, particularly Myt3, promote -cell function/survival by repressing late-stage SRGs via Sin3-mediated histone de-acetylation under both normal physiology and metabolic stress. Aim 1 will establish how MYT TFs repress SRG expression in a human β cell line and how manipulating MYT-TF levels will affect primary human β-cell function and survival. Aim 2 will define how metabolic stressors up-regulate Myt3 production and how this upregulation enable β-cell compensation under metabolic stress. We expect to uncover a tunable mechanism that can be explored for preventing/delaying β-cell failure and T2D.

工作负荷诱导的胰岛β细胞功能障碍、身份丧失和细胞死亡，通常称为 2型糖尿病（T2 D）是一种常见的糖尿病。这种疾病通常始于肥胖引起的胰岛素 当外周组织需要更高水平的循环胰岛素来储存和使用葡萄糖时，胰岛素抵抗。 胰岛β细胞通过扩大β细胞群和增加每个细胞的胰岛素输出来补偿，这需要 上调胰岛素生物合成和氧化葡萄糖代谢。这些蛋白质产生未折叠的胰岛素原， 线粒体中的ER和活性氧（ROS），其在高水平下可大量杀伤β细胞。因此，β 细胞通过刺激几种早期SRG，包括Atf 6， IRE 1 κ B、PERK、Hsf 1和Nurf 2，导致：1）减弱整体蛋白质翻译; 2）增强蛋白质翻译。 一些具有特殊特征的SRG mRNA，如上游开放阅读框（uORF）5'到主要的 3）上调了一些晚期SRG的表达。这些反应的总体效果是消除 未折叠蛋白/ROS用于蛋白质组稳态和可持续的β细胞功能。然而，过度激活 一些晚期SRG如Atf 4和Hsps通过开启一些促凋亡基因或 通过极大地降低整体蛋白质翻译。因此，β细胞必须限制失败的水平- 导致SRG持续高水平的胰岛素输出。一个新兴的模型，从我们最近发表的 研究发现，含有Myt TF和Sin 3的转录复合物可以选择性地抑制这些失败- 导致SRG。Myt TF是一个由三种髓鞘转录因子（Myt 1、2和3）组成的家族，在神经胶质瘤中高度表达。 胰岛细胞Sin 3，包括Sin 3a和Sin 3b，是通过募集组蛋白来抑制转录的共调节子 去乙酰化酶（HDAC）修饰组蛋白。我们发现Myt转录因子和Sin 3可以形成一个转录复合物， 在β细胞中。在小鼠和人β细胞中失活这些基因会导致细胞功能障碍和/或死亡， 过度激活晚期β细胞衰竭引起的SRG，但不激活早期SRG。有趣的是，Myt TF， 特别是Myt 3，在小鼠和人β细胞中由肥胖相关的应激源诱导，可能由 Myt 3 mRNA 5'侧翼区的uORF。重要的是，MYT 3下调伴随着人类β细胞 T2 D发展的失败。我们的总体假设是，应激反应Myt TF，特别是 Myt 3通过Sin 3介导的组蛋白去乙酰化抑制晚期SRG来促进细胞功能/存活 在正常的生理和代谢压力下。目标1将确定MYT TF如何抑制SRG 在人β细胞系中的表达以及操纵MYT-TF水平将如何影响原代人β细胞 功能和生存。目的2将定义代谢应激源如何上调Myt 3的产生，以及这如何影响Myt 3的表达。 上调使得β-细胞能够在代谢应激下补偿。我们希望能发现一种可调节的机制 可以探索用于预防/延迟β-细胞衰竭和T2 D。