Biochemical mechanisms of beta cell protection through bromodomain inhibition

通过溴结构域抑制保护 β 细胞的生化机制

基本信息

批准号：
10427263
负责人：
Brian Christopher Smith
金额：
$ 38.5万
依托单位：
MEDICAL COLLEGE OF WISCONSIN
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-09-20 至 2024-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10427263
关键词：
Acetylation Amino Acids Anti-Inflammatory Agents Attenuated Autoimmune Diabetes Autoimmune Diseases B Cell Proliferation Beta Cell Binding Biochemical Biological Blood Glucose Bromodomain CRISPR/Cas technology Cell Death Cells Chemicals Childhood Cytoprotection DNA Repair Data Development Diabetes Mellitus Early treatment Epigenetic Process Family Family member Gene Expression Genetic Genetic Transcription Goals Histones Immune Immune system Immunologics Impairment Inbred NOD Mice Individual Inflammation Inflammation Mediators Inflammatory Insulin Interleukin-1 beta Intervention Islets of Langerhans Lead Learning Lysine Macrophage Activation Mediating Mediator of activation protein Memory Mitochondria Molecular Monozygotic twins Nitric Oxide Oxidative Stress Pancreas Pathway interactions Patients Phenotype Population Production Proteins Reaction Reader Reagent Recovery Regulation Role Testing Therapeutic Transcriptional Regulation cell type cytokine design effective therapy immune system function inhibitor innovation insulinoma islet macrophage mouse model new therapeutic target novel novel therapeutics patient population pediatric patients prevent protective effect response tool transcription factor

项目摘要

PROJECT SUMMARY Autoimmune diabetes is characterized by an inflammatory reaction in and around pancreatic islets followed by selective destruction of insulin producing β-cells. Low concordance rates of autoimmune diabetes in monozygotic twins indicate an important but poorly understood role for epigenetic factors in diabetes initiation and progression. Bromodomains are epigenetic “readers” of lysine acetylation on histones and transcription factors; bromodomain binding to acetylated histones/proteins regulates transcription in a cell-type dependent manner. Early treatment of non-obese diabetic (NOD) mice with an inhibitor of the bromodomain and extraterminal (BET) family (Brd2-4) was recently shown to suppress development of autoimmune diabetes. The protective effects of BET inhibition correlated with anti-inflammatory and pro-proliferative phenotypes in macrophages and β-cells, respectively; however, the mechanisms are poorly understood. We hypothesize that Brd4 regulates β-cell proliferation and macrophage inflammation in islets, and that inhibition of Brd2 and Brd3 are liabilities of pan-BET inhibitors in autoimmune diseases. Consistent with this hypothesis, pan-BET inhibition is associated with impaired learning and memory as well as reduced immune system function. As epigenetic intervention in autoimmune diabetes represents a novel therapeutic target in a primarily pediatric population, off-target effects must be minimized. Brd4 inhibition as a therapeutic strategy in autoimmune diabetes will be examined in three specific aims: Aim 1) Test the hypothesis that Brd4 inhibition prevents macrophage activation and production of inflammatory mediators known to damage β-cells. Studies will build on our preliminary data showing that pan-BET inhibitors attenuate macrophage production of inflammatory mediators such as IL-1β and nitric oxide. Aim 2) Test the hypothesis that Brd4 inhibition protects β-cells from cytokine-mediated damage by stimulating DNA damage repair pathways and protecting mitochondria from damage. Studies will use insulinoma cells deficient in Brd2, Brd3, and Brd4 and chemical inhibitors to explore the role of BET proteins in the regulation of β-cell responses to inflammatory mediators and the activation of defense pathways that facilitate β-cell recovery from oxidative stress. Aim 3) Develop selective Brd4 inhibitors for effective treatment of autoimmune diabetes. We provide evidence to support our innovative approach to selectively inhibit Brd4 using covalent targeting of a specific amino acid residue unique to Brd4. Biochemical, molecular, immunological, cell biological, genetic, and chemical biological approaches will be used to investigate the molecular and cellular pathways through which BET inhibition protects β-cells and to develop novel tools and reagents to selectively target the BET family of transcriptional regulators. Our long-term goals are to elucidate the cell-type specific mechanisms of transcriptional regulation by BET bromodomains and develop novel therapeutics to selectively inhibit the activity of individual BET proteins as an initial step in the design of strategies to halt the development and progression of autoimmune diabetes.

项目概要自身免疫性糖尿病的特征是胰岛内及其周围发生炎症反应，然后选择性破坏产生胰岛素的 β 细胞，自身免疫性糖尿病的一致性率较低。同卵双胞胎表明表观遗传因素在糖尿病发生中发挥着重要但人们知之甚少的作用溴结构域是组蛋白赖氨酸乙酰化和转录的表观遗传“读者”。因子；溴结构域与乙酰化组蛋白/蛋白质的结合调节细胞类型依赖性转录用布罗莫结构域抑制剂对非肥胖糖尿病（NOD）小鼠进行早期治疗。末端外 (BET) 家族 (Brd2-4) 最近被证明可以抑制自身免疫性糖尿病的发展。 BET 抑制的保护作用与抗炎和促增殖表型相关分别是巨噬细胞和β细胞；然而，人们对其机制知之甚少。 Brd4 调节胰岛中的 β 细胞增殖和巨噬细胞炎症，并抑制 Brd2 和 Brd3 是泛BET抑制剂在自身免疫性疾病中的作用，与这一假设一致，泛BET。抑制与学习和记忆受损以及免疫系统功能降低有关。自身免疫性糖尿病的表观遗传干预代表了主要儿科疾病的新治疗靶点作为自身免疫治疗策略，必须尽量减少 Brd4 抑制的脱靶效应。糖尿病将通过三个具体目标进行检查：目标 1) 检验 Brd4 抑制可预防糖尿病的假设巨噬细胞的激活和炎症介质的产生会损害 β 细胞。我们的初步数据显示泛 BET 抑制剂可减弱巨噬细胞产生炎症目标 2) 检验 Brd4 抑制可保护 β 细胞免受影响的假设。通过刺激 DNA 损伤修复途径并保护线粒体免受细胞因子介导的损伤研究将使用缺乏 Brd2、Brd3 和 Brd4 的胰岛素瘤细胞以及化学抑制剂来探索 BET 蛋白在调节 β 细胞对炎症介质的反应和激活促进 β 细胞从氧化应激中恢复的防御途径目标 3) 开发选择性 Brd4 抑制剂。我们提供证据来支持我们的创新方法。使用 Brd4 特有的特定氨基酸残基的共价靶向来选择性抑制 Brd4，将使用分子、免疫学、细胞生物学、遗传和化学生物学方法研究 BET 抑制保护 β 细胞的分子和细胞途径，并开发选择性靶向 BET 转录调控因子家族的新工具和试剂我们的长期目标。旨在阐明 BET 溴结构域转录调节的细胞类型特异性机制和开发新的疗法来选择性抑制单个 BET 蛋白的活性，作为该研究的第一步设计阻止自身免疫性糖尿病发生和进展的策略。