DNA Repair and Mitochondrial Dysfunction in T Cell Aging

T 细胞衰老过程中的 DNA 修复和线粒体功能障碍

• 批准号: 10457649
• 负责人: Cornelia M. Weyand
• 金额: $ 28.23万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-12-20 至 2024-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10457649
• 关键词: DNA; Repair; Mitochondrial; Dysfunction; Cell

Project Summary Aging of T lymphocytes has detrimental effects on the health of older individuals; rendering them susceptible to cancer, infection, and unopposed tissue inflammation. Older T cells are prone to differentiate into inflammatory effector cells, rapidly invading into peripheral tissues and promoting inflammatory tissue damage. Multiple biologic processes have been implicated in mediating T cell aging; including defective DNA repair, telomeric damage, membrane restructuring into invasive protrusions and reprogramming of cellular bioenergetics. T cell aging is accelerated by 20-30 years in patients with the inflammatory syndrome rheumatoid arthritis (RA), providing an excellent model system to study molecular, structural and behavioral abnormalities in old T cells. Work supported during the previous funding period has identified the DNA nuclease MRE11A as a key player in T cell aging. T cells from RA patients and from older healthy donors share the transcriptional repression of MRE11A. T cells low in MRE11A protein accumulate damaged telomeres and induce robust tissue inflammation with a signature of uncontrolled innate and adaptive immunity. Preliminary data show that MRE11Alow T cells also lack expression of the nuclease in mitochondria, leading to oxidative damage and cytoplasmic leakage of mitochondrial DNA (mtDNA). In the cytoplasm, oxidized mtDNA promotes NLRP3 inflammasome assembly, triggers caspase 1 activation and ultimately induces T cell lytic death. Here, we examine the hypothesis that mitochondrial stress is a driver of T cell aging and that the age-related decline of the DNA repair nuclease MRE11A exposes T cells to mitochondrial DNA leakage, inflammasome activation and ultimately to pyroptotic death. We have assembled key enabling resources to mechanistically study how mitochondrial MRE11A protects T cells from aging; including a large cohort of RA patients in whom T cells are pre-aged and a chimeric mouse model in which tissue inflammation is induced in engrafted human synovium to corroborate in vitro data by in vivo studies. Aim 1 examines mechanistically how MRE11A affects mitochondrial function, generation of ATP and ROS, glucose utilization and lipogenesis. The aim will connect mitochondrial DNA repair to oxygen consumption in the electron transfer chain and acetyl-CoA oxidation in the tricarboxylic acid cycle. Aim 2 investigates how MRE11A guides a mitochondrial stress defense program by preventing mtDNA release into the cytoplasm. In loss-of-function and gain-of-function experiments we will probe how MRE11A regulates inflammasome assembly, caspase 1 activation and T cell pyroptosis. Aim 3 will identify mechanisms through which MRE11A deficiency induces tissue inflammation. We will test how caspase 1-dependent cleavage of the pro-inflammatory cytokines IL-1 and IL-18 and of the membrane pore former gasdermin D drive tissue damage. These experiments will explore in vitro and in vivo how failed mitochondrial DNA repair causes T cell lysis, release of alarmins into the extracellular space and initiation of noninfectious inflammation.

项目概要 T 淋巴细胞的老化对老年人的健康产生不利影响，使其容易受到感染； 癌症、感染和未对抗的组织炎症很容易分化为炎症。 效应细胞，迅速侵入周围组织并促进炎症组织损伤。 生物过程与介导 T 细胞衰老有关，包括缺陷 DNA 修复、端粒修复； T 细胞损伤、膜重组为侵入性突起以及细胞生物能的重新编程。 炎症综合征类风湿性关节炎 (RA) 患者的衰老速度加快 20-30 岁， 为研究老T细胞的分子、结构和行为异常提供了一个优秀的模型系统。 上一资助期间支持的工作已确定 DNA 核酸酶 MRE11A 是该领域的关键参与者。 T 细胞老化。来自 RA 患者和老年健康捐献者的 T 细胞都受到转录抑制。 MRE11A 蛋白含量低的 T 细胞会积累受损的端粒并诱发强烈的组织炎症 初步数据显示，MRE11Alow T 细胞具有不受控制的先天免疫和适应性免疫的特征。 线粒体中也缺乏核酸酶的表达，导致氧化损伤和细胞质渗漏 线粒体 DNA (mtDNA) 在细胞质中，氧化的 mtDNA 促进 NLRP3 炎性体组装， 触发 caspase 1 激活并最终诱导 T 细胞裂解性死亡。在此，我们检验以下假设： 线粒体应激是 T 细胞衰老的驱动因素，并且 DNA 修复核酸酶与年龄相关的下降 MRE11A 使 T 细胞暴露于线粒体 DNA 渗漏、炎性体激活并最终 我们已经收集了关键的支持资源来机械地研究线粒体如何死亡。 MRE11A 保护 T 细胞免于衰老；包括一大群 RA 患者，其中 T 细胞已提前衰老 嵌合小鼠模型，在雕刻的人类滑膜中诱导组织炎症，以证实 目标 1 从机制上检查 MRE11A 如何影响线粒体功能。 ATP 和 ROS 的产生、葡萄糖利用和脂肪生成，目的是将线粒体 DNA 修复联系起来。 电子传递链中的氧消耗和三羧酸循环中的乙酰辅酶A氧化。 目标 2 研究 MRE11A 如何通过阻止 mtDNA 释放来指导线粒体应激防御程序 在功能丧失和功能获得实验中，我们将探讨 MRE11A 如何调节。 Aim 3 将通过炎症小体组装、caspase 1 激活和 T 细胞焦亡来确定机制。 MRE11A 缺陷会引起组织炎症，我们将测试 caspase 1 依赖性裂解的情况。 促炎细胞因子 IL-1 和 IL-18 以及膜孔形成剂gasdermin D 驱动组织损伤。 这些实验将在体外和体内探索线粒体 DNA 修复失败如何导致 T 细胞裂解， 警报素释放到细胞外空间并引发非感染性炎症。