Role of TET dioxygenase associated immune mechanisms in cardiac injury and repair

项目摘要/摘要 克隆性造血术(CHIP)被定义为体细胞造血细胞的扩张 无血液病个体的血细胞克隆。最近确定的外显子组测序 表观遗传调节因子频繁突变的造血干细胞和祖细胞(例如， DNA甲基胞嘧啶双加氧酶TET2)，在老化过程中表现出克隆扩张的生长优势。 有趣的是，携带体细胞TET2突变的CHIP个体倾向于具有冠状动脉心血管疾病的高风险 疾病(CVD)。这一发现预示着剖析新型致病物质的分子时代的到来。 芯片-CVD融合的潜在机制。在模拟克隆造血的动物研究中，TET2 LOF 已被发现会加速动脉粥样硬化和心力衰竭。虽然这些研究提供了详细的 TET2的表型特征、潜在分子机制和因果关系 芯片中的LOF和增加的CVD风险在很大程度上仍未解决。PI的实验室已经开发出一套 独特的工具来解决这一关键的临床相关知识差距，包括(I)组织特异性TET2缺陷 带有报告基因的小鼠模型(髓系或HSPC中TET2的特异性消融) 在心脏损伤期间的体内实时谱系追踪；和(Ii)基于dCas9的表观基因组编辑工具，允许 表观表型与表型之间因果关系的探讨。该团队提议测试 假设TET2控制增强子的活性，该增强子调节关键基因的表达 维持单核/巨噬细胞在对缺血损伤的修复反应中的适当功能(例如， 心肌梗死或心肌梗塞)。目标1将解决TET2缺失如何损害髓系细胞和活跃的HSPC 参与心肌梗死后的心脏修复过程。AIM 2将解决TET2缺陷如何扰乱增强子 促炎症向修复性单核细胞转化所必需的关键基因的活性，从而 干扰单核细胞心肌梗死后的双相反应以影响炎症和炎症的及时消退 心脏修复。将进一步测试恢复TET2/5hmC功能的想法，以干预心肌梗死后的组织修复。 这项研究引入了一个新的维度来剖析心血管疾病的发病机制，重点是 心血管系统和免疫-造血系统。这一项目的竣工预计将产生 关于体细胞TET2突变相关的克隆性造血如何增加糖尿病风险的新见解 心血管疾病(CVD)，并在压力下损害心脏功能。更具临床相关性的发现 这项研究还有望建立针对有缺陷的表观遗传学的临床前理论基础 监管机构预防和治疗心血管疾病。

Project Summary/ Abstract Clonal hematopoiesis of indeterminate potential (CHIP) is defined as an expansion of somatic hematopoietic blood cell clone in individual without hematological disorders. Recent exome sequencing identified hematopoietic stem and progenitor cells (HSPCs) with frequent mutations of epigenetic regulators (e.g., the DNA methylcytosine dioxygenase TET2) that exhibited growth advantage with clonal expansion during aging. Interestingly, CHIP individuals with somatic TET2 mutations tend to have high risk of coronary cardiovascular diseases (CVD). This discovery heralds the advent of a molecular era in the dissection of novel pathogenic mechanisms underlying CHIP-CVD convergence. In animal studies that mimic clonal hematopoiesis, Tet2 LOF has been found to accelerate atherosclerosis and heart failure. While these studies provided detailed phenotypic characterizations, the underlying molecular mechanisms and the causal relations between TET2 LOF in CHIP and increased CVD risk remain largely unresolved. The PI’s laboratory has developed a set of unique tools to address this critical clinically-relevant knowledge gap, including (i) tissue specific Tet2-deficient mouse models (specific ablation of Tet2 in the myeloid lineage or in HSPCs) with reporter genes to enable real-time lineage tracing in vivo during cardiac injury; and (ii) dCas9 based epigenome editing tools that allow the interrogation of causal effects between epigenotypes and phenotypes. The team proposes to test the hypothesis that Tet2 controls the activity of enhancers that regulate the expression of key genes required for maintaining the proper function of monocytes/ macrophages in the reparative response to ischemic injury (e.g., myocardial infarction or MI). Aim 1 will address how Tet2 loss impairs myeloid cells and HSPCs that actively participate in the post-MI cardiac repair process. Aim 2 will address how Tet2 deficiency disrupts enhancer activities in key genes that are essential for proinflammatory to reparative monocyte conversion, thereby perturbing the biphasic post-MI response of monocyte to compromise timely resolution of inflammation and cardiac repair. The idea of restoring Tet2/5hmC function will be further tested to intervene post-MI tissue repair. This study introduces a new dimension to dissect CVD pathogenesis by focusing on the interplay between the cardiovascular system and the immune-hematopoietic system. Completion of this project is anticipated to yield novel insights on how somatic TET2 mutations-associated clonal hematopoiesis increases the risk of cardiovascular disease (CVD) and impairs cardiac function under stress. More clinically relevant, discoveries made in this study are also expected to establish the preclinical rationale for targeting defective epigenetic regulators to prevent and treat CVD.