TET2-mediated transcriptional and epigenetic control of normal and malignant hematopoiesis

TET2介导的正常和恶性造血的转录和表观遗传控制

• 批准号: 9922386
• 负责人: Jianlong Wang
• 金额: $ 41.28万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9922386
• 关键词: Acute Erythroblastic Leukemia; Address; Adult; Age-Years; Binding; Biology; Cell physiology; Cells; Clonal Expansion; Collaborations; DNA; Data; Development; Dioxygenases; Ensure; Epigenetic Process; Family; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Genomics; Goals; Grant; Hematologic Neoplasms; Hematology; Hematopoiesis; Hematopoietic; Hematopoietic stem cells; Hydroxylation; Impairment; Individual; Intervention; Knock-in; Lead; Malignant - descriptor; Malignant Neoplasms; Mediating; Modification; Mus; Mutate; Mutation; Myelogenous; Myeloproliferative disease; Oncogenic; Oxides; Pathogenesis; Patients; Play; Proteins; RNA; RNA-Binding Proteins; RUNX1 gene; Regulation; Reporting; Role; Second Primary Neoplasms; Site; Testing; Therapeutic; Transcript; Transcriptional Activation; Tumor Suppressor Genes; demethylation; embryonic stem cell; in vivo; member; mouse model; mutant; novel; novel therapeutics; oxidation; pluripotency; premalignant; recruit; success; tumor

TET2 is one of the most commonly mutated genes in adult myeloid malignancies and in normal individuals over 70 years of age. Tet2-loss leads to increased expansion of hematopoietic stem/progenitor cells (HSPCs) and subsequent development of myeloid malignancies in mice. Thus, TET2 mutations constitute a suitable target for intervention at the early stages of HSPC clonal expansion. To exploit TET2 mutations therapeutically, a better understanding of the mechanisms by which Tet2-loss leads to premalignant HSPC dysregulation and myeloid malignancy development is essential. As a member of the methylcytosine dioxygenase family, TET2 converts 5mC to 5hmC, which can be relatively stable or be further oxidized to 5fC and 5caC. We have reported the requirement of catalytic activity of TET2 in its tumor-suppressive functions in HSPCs. Recently, we identified a novel mechanism of hematological malignancy via the increased mutational burden at genomic sites where TET2 binds and, counterintuitively, with gained 5hmC upon TET2-loss. In addition, we discovered a novel role of TET2 in RNA hydroxymethylation (hm5C) and target transcripts destabilization via its partner and RNA-binding protein (RBP) PSPC1 in mouse embryonic stem cells. Importantly, we found that PSPC1 and its heterodimer partner NONO are both abundantly expressed in HSPCs. Our studies raise two critical questions on TET2 biology in normal and malignant hematopoiesis: 1) How does gained 5hmC contribute to the pathogenesis of myeloid malignancy? 2) Is catalytic activity of TET2 relevant and functional at the RNA hm5C level in HSPCs? We hypothesize that TET2 may exert enzymatic functions through preferential 5hmC- to-5fC/5caC oxidation leading to DNA demethylation and transcriptional activation of tumor suppressor genes and through RNA hm5C modification and consequent destabilization of oncogenic RNAs. We will study how dysregulation of DNA-5hmC and RNA-hm5C mediated epigenetic control upon TET2 mutations can lead to malignant hematopoiesis by three specific aims. Aim 1) Define preferential TET2-mediated 5hmC-5fC/5caC oxidation for DNA demethylation in HSPCs and its dysregulation for the pathogenesis of myeloid malignancy using our newly created 5hmC stalling and catalytically inactive knock-in mutant Tet2 mouse models. Aim 2) Determine the functional significance of the TET2-RUNX1 partnership for TET2 genomic localization and target gene expression in HSPCs. RUNX1, a TET2 binding partner, is reported to be enriched in regions of increased 5hmC, but not in hypo-5hmC regions in TET2 mutant AML. We will study RUNX1 functions in regulating TET2 genomic occupancy in HSPCs and examine the potential role of RUNX1 in imparting unique TET2 functions in preferential 5hmC-to-5fC/5caC oxidation during normal and malignant hematopoiesis. Aim 3) Investigate RBP- mediated TET2 recruitment for RNA hm5C modification and destabilization of oncogenic RNAs in HSPCs and its dysregulation in hematological malignancy. We will also investigate how mutation of TET2 may impair its PSPC1 association in HSPCs leading to malignant hematopoiesis.

TET2是成年髓样恶性肿瘤中最常见的突变基因之一，正常 70岁以上的个人。 TET2损失导致造血的膨胀增加 茎/祖细胞（HSPC）以及随后在小鼠中骨髓恶性肿瘤的发展。 因此，TET2突变构成了在HSPC早期阶段进行干预的合适靶标 克隆扩张。为了通过治疗利用TET2突变，对 TET2损坏导致前HSPC失调和髓样恶性肿瘤的机制 发展至关重要。作为甲基胞嘧啶二氧酶家族的成员，TET2转换5MC 到5HMC，可以相对稳定或进一步氧化为5FC和5CAC。我们 已经报道了TET2在其肿瘤抑制功能中的催化活性的要求 HSPC。最近，我们通过增加了血液性恶性肿瘤的新型机制 TET2结合并违反直觉的基因组部位的突变负担，并获得了5HMC tet2-loss。此外，我们发现了TET2在RNA羟甲基（HM5C）和 目标转录本通过其伴侣和RNA结合蛋白（RBP）PSPC1在小鼠中不稳定 胚胎干细胞。重要的是，我们发现PSPC1及其异二聚体伙伴Nono是 两者都在HSPC中大量表达。我们的研究就TET2提出了两个关键问题 正常和恶性造血的生物学：1）获得5HMC如何有助于 髓样恶性肿瘤的发病机理？ 2）是TET2相关和功能的催化活性 HSPC中的RNA HM5C水平？我们假设TET2可能通过 优先5HMC-TO-5FC/5CAC氧化导致DNA脱甲基和转录 激活肿瘤抑制基因并通过RNA HM5C修饰并因此 致癌RNA的稳定。我们将研究DNA-5HMC和RNA-HM5C的失调 TET2突变对TET2突变的介导的表观遗传控制会导致三个恶性造血作用 具体目标。 AIM 1）定义DNA的优先TET2介导的5HMC-5FC/5CAC氧化 HSPC中的去甲基化及其对使用我们 新创建的5HMC失速和催化性的敲入突变体TET2小鼠模型。目标2） 确定TET2-RUNX1伙伴关系TET2基因组定位的功能意义 和HSPC中的靶基因表达。据报道，TET2结合伙伴Runx1富含 在TET2突变体AML中增加了5HMC的区域，但在Hypo-5HMC区域中不增加。我们将学习runx1 调节HSPC中TET2基因组占用率的功能并检查Runx1在 在正常和 恶性造血。目标3）研究RNA HM5C的RBP介导的TET2募集 HSPC中致癌RNA的修饰和不稳定及其在血液学中的失调 恶性。我们还将研究TET2突变如何损害其HSPC中的PSPC1关联 导致恶性造血。