The function and underlying mechanism of TET1 in myelodysplastic syndromes

TET1在骨髓增生异常综合征中的功能及机制

• 批准号: 10304942
• 负责人: Jianjun Chen
• 金额: $ 55.49万
• 依托单位: BECKMAN RESEARCH INSTITUTE/CITY OF HOPE
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-03-10 至 2023-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10304942
• 关键词: Acute Myelocytic Leukemia; Address; Anemia; Animal Genetics; Animal Model; Attenuated; Basic Science; Blood Cells; Bone Marrow Transplantation; Cell Differentiation process; Cells; ChIP-seq; Chromosome abnormality; Clonal Hematopoietic Stem Cell; Control Groups; DNA; DNA Methylation; Data; Data Set; Development; Dioxygenases; Disease; Down-Regulation; Dysmyelopoietic Syndromes; EZH2 gene; Epigenetic Process; FLT3 gene; Family; Future; Gene Expression Profiling; Gene Mutation; Genes; Goals; Hematopoiesis; Hematopoietic; Hematopoietic stem cells; Histones; Human; In Vitro; Knock-out; Lead; Leukopenia; MLL gene; MLL-rearranged leukemia; Maintenance; Malignant - descriptor; Malignant Neoplasms; Modeling; Modification; Molecular; Mus; Mutate; Mutation; Myelogenous; Myeloproliferative disease; NPM1 gene; Oncogenic; Pathogenesis; Pathologic; Patients; Phenotype; Play; Protein translocation; Reporting; Research Design; Risk; Role; Sampling; Signal Pathway; Signal Transduction; Solid; Thrombocytopenia; Translational Research; Transplant Recipients; Tumor Suppressor Genes; Tumor Suppressor Proteins; Validation; Work; Xenograft procedure; cohort; cytopenia; demethylation; gain of function; gene translocation; genome-wide; granulocyte-monocyte progenitors; hematopoietic differentiation; high risk; in vivo; insight; knock-down; loss of function; loss of function mutation; member; mutant; new therapeutic target; novel; overexpression; peripheral blood; progenitor; success; t(8; 21)(q22; q22); transcriptome sequencing; transplant model; whole genome

PROJECT SUMMARY (ABSTRACT): Title: The function and underlying mechanism of TET1 in myelodysplastic syndromes. Background: Myelodysplastic syndromes (MDS) is a heterogenous group of clonal hematopoietic stem cell disorders, characterized by peripheral blood (PB) cytopenias (e.g., anemia, leukopenia, and thrombocytopenia). Although chromosomal abnormalities, gene mutations and some histone/DNA epigenetic changes have been reported in MDS, the molecular mechanisms underlying the pathogenesis of MDS have not been well understood. TET1, the founding member of the TET methylcytosine dioxygenase family, was first identified as a fusion partner of the MLL gene in acute myeloid leukemia (AML). In contrast to the previous thought that all three TET genes (TET1/2/3) may function as tumor suppressor genes in cancers, our recent work showed that TET1 is overexpressed in certain subtypes of AMLs, and plays a critical oncogenic role in the development of such AMLs. However, the role of TET1 in MDS remains unknown. Recently, in analysis of a genome-wide gene expression profiling dataset of a large cohort of human primary MDS patients, we found that TET1 is also aberrantly overexpressed in all the major subtypes of MDS analyzed, which was confirmed by qPCR in our in-house MDS samples. Tet1 is also overexpressed in various murine MDS models. We then showed that knockdown of TET1 expression substantially promoted differentiation of MDS cells, and forced expression of wild-type TET1 (but not catalytic inactive TET1 mutant) caused the opposite phenomenon. TET1 depletion also significantly inhibited MDS progression and diminished cytopenias in vivo. Furthermore, we have identified a set of potential/candidate target genes of TET1 in MDS, and some of them have been implicated in the pathogenesis of MDS. Objective/Hypothesis: TET1 plays an essential role in MDS pathogenesis through epigenetically regulating expression of a set of essential target genes. Specific Aims: (1) To determine whether TET1 is required for the development and maintenance of MDS; (2) To determine whether forced expression of TET1 can promote MDS development and progression, and whether TET1 function is dependent on its catalytic activity; and (3) To decipher the molecular mechanism(s) underlying the pathological role of TET1 in MDS. Study Design: 1) We will conduct loss-of-function studies in genetic animal MDS models and patient-derived xeno-transplantation (PDX) MDS models to determine whether Tet1/TET1 expression/function is required for both development and maintenance of MDS (Aim 1). 2) We will conduct gain-of-function studies with the above MDS models to determine whether forced expression of Tet1/TET1 can promote MDS development and progression via a catalytic activity-dependent mechanism (Aim 2). 3) We will perform genome-wide ChIP-seq, 5hmC-seq, and RNA-seq to identify all direct targets of TET1 in MDS, followed by the validation/functional studies of a set of top targets of TET1 in vitro and in vivo, to elucidate the molecular mechanism underlying TET1’s role (Aim 3).

项目概要（摘要）： 标题：TET1 在骨髓增生异常综合征中的功能和潜在机制。 背景：骨髓增生异常综合征（MDS）是一组异质的克隆性造血干细胞 以外周血 (PB) 血细胞减少为特征的疾病（例如贫血、白细胞减少和血小板减少）。 尽管染色体异常、基因突变和一些组蛋白/DNA 表观遗传变化已有报道 在MDS中，MDS发病机制的分子机制尚未被充分了解。 TET1，即 TET 甲基胞嘧啶双加氧酶家族的创始成员，首次被鉴定为 急性髓系白血病 (AML) 中的 MLL 基因。与之前的想法相反，所有三个 TET 基因 (TET1/2/3)可能作为癌症中的抑癌基因，我们最近的工作表明TET1是 在 AML 的某些亚型中过度表达，并在此类 AML 的发展中发挥关键的致癌作用。 然而，TET1 在 MDS 中的作用仍不清楚。最近，在对全基因组基因表达的分析中 通过对一大群人类原发性 MDS 患者的分析数据集，我们发现 TET1 也存在异常 在所分析的所有主要 MDS 亚型中均过表达，这在我们内部 MDS 中通过 qPCR 得到了证实 样品。 Tet1 在各种小鼠 MDS 模型中也过度表达。然后我们展示了 TET1 的敲低 表达显着促进MDS细胞的分化，并强制表达野生型TET1（但不 催化失活的 TET1 突变体）引起了相反的现象。 TET1 耗竭也显着抑制 MDS 进展和体内血细胞减少减少。此外，我们还确定了一组潜在/候选者 TET1在MDS中的靶基因，其中一些与MDS的发病机制有关。 目的/假设：TET1 通过表观遗传调控在 MDS 发病机制中发挥重要作用 一组重要靶基因的表达。 具体目标： (1) 确定MDS的开发和维护是否需要TET1； (2) 确定TET1的强制表达是否可以促进MDS的发生和进展，以及 TET1的功能是否取决于其催化活性； (3) 破译分子机制 TET1 在 MDS 中的病理作用的基础。 研究设计： 1）我们将在遗传动物MDS模型和患者来源的模型中进行功能丧失研究 异种移植 (PDX) MDS 模型以确定 Tet1/TET1 表达/功能是否是两者所必需的 MDS 的开发和维护（目标 1）。 2）我们将利用上述MDS进行功能获得研究 确定 Tet1/TET1 的强制表达是否可以促进 MDS 发生和进展的模型 通过催化活性依赖机制（目标 2）。 3) 我们将进行全基因组 ChIP-seq、5hmC-seq、 和 RNA-seq 来识别 MDS 中 TET1 的所有直接靶点，然后对一组进行验证/功能研究 体外和体内 TET1 的主要靶标，以阐明 TET1 作用的分子机制（目标 3）。