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

• 批准号: 10216248
• 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
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-20 至 2023-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10216248
• 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/antagonist; innovation; insulinoma; islet; macrophage; mouse model; new therapeutic target; novel; novel therapeutics; patient population; pediatric patients; prevent; protective effect; response; tool; transcription factor

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.

项目摘要 自身免疫性糖尿病的特征是胰岛和周围的炎症反应。 胰岛素产生β细胞的选择性破坏。自身免疫性糖尿病的一致性低 单卵双胞胎表明表观遗传因素在糖尿病开始 和进展。溴化局是组蛋白和转录上赖氨酸乙酰化的表观遗传“读者” 因素；与乙酰化的神经蛋白/蛋白质结合溴d域，调节依赖性细胞类型的转录 方式。早期治疗非肥胖糖尿病（NOD）小鼠的抑制剂和 最近证明，外部周期（BET）家族（BRD2-4）抑制自身免疫性糖尿病的发展。 BET抑制作用的受保护作用与抗炎和促销表型有关 巨噬细胞和β细胞分别；但是，这些机制知之甚少。我们假设这一点 BRD4调节胰岛中的β细胞增殖和巨噬细胞注射，并抑制BRD2和BRD3 是自身免疫性疾病中泛抑制剂的负债。与这个假设一致 抑制与学习和记忆力受损以及免疫系统功能降低有关。作为 自身免疫性糖尿病的表观遗传干预代表原发性小儿的新型热靶标 人口，脱靶效应必须最小化。 BRD4抑制作自身免疫性的治疗策略 糖尿病将以三个特定目的进行检查：目标1）测试BRD4抑制作用的假设 巨噬细胞的激活和炎症介质的生产已知损坏β细胞。研究将建立 关于我们的初步数据，表明泛膏抑制剂减弱了炎症的巨噬细胞的产生 IL-1β和一氧化氮等介体。目标2）检验BRD4抑制保护β细胞免受的假设 细胞因子介导的损伤，通过刺激DNA损伤修复途径并保护线粒体免受 损害。研究将使用缺乏BRD2，BRD3和BRD4和化学抑制剂的胰岛素瘤细胞来探索 BET蛋白在调节β细胞对炎症介质的反应中的作用以及激活 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 有效治疗自身免疫性糖尿病。我们提供证据以支持我们的创新方法 使用特定的氨基酸保留率的共价靶向BRD4独有的靶向有选择地抑制BRD4。生化， 分子，免疫学，细胞生物学，遗传和化学生物学方法将用于 研究分子和细胞途径，通过这些途径抑制可以保护β细胞并发展 新颖的工具和试剂，以选择性地针对转录调节器的BET家族。我们的长期目标 阐明通过BET溴结构域和 开发新的疗法以选择性地抑制单个BET蛋白的活性，这是 制定停止自身免疫性糖尿病的发展和发展的策略。