Role of the TET1 short isoform in MDS development and maintenance

项目总结 最近的研究表明，在正常情况下，通过替代启动子进行普遍的转录调控 组织和癌症。大多数替代启动子如何促进肿瘤的形成、诊断或 治疗方法仍不清楚。Tet1首先被确定为AML的MLL合作伙伴。它属于Tet(十- 11个易位)蛋白家族(Tet1/2和Tet3)，可将5-甲基胞嘧啶(5mC)氧化为5-甲基胞嘧啶(5-mC)。 羟甲基胞嘧啶(5HmC)和其他氧-MC中间体，从而促进DNA去甲基化。 有趣的是，我们发现了TET1的一个短的亚型(称为TET1-S)，它包含一个催化结构域 但缺乏N-末端的CXXC结构域，并受另一种启动子控制，在 人骨髓(BM)细胞。此外，TET1-S在骨髓增生异常的骨髓细胞中上调 综合征(MDS)患者与健康人的比较。我们发现TET1-S在骨髓中有表达 与TET1-F相比，细胞水平要高得多。然而，它在造血系统中的作用尚不清楚。 根据我们的初步结果，我们假设TET1-S在维持性心力衰竭中起着重要作用 造血干细胞(HSCs)及其上调通过破坏MDS而参与MDS的发展 HSCs功能正常，造血功能正常。为了检验这一假设，我们将确定1)致癌作用 以及Tet1-S在MDS发病机制中的作用机制；2)MDS是否需要Tet1-S 3)Tet1-S调控HSPC基因表达的分子机制 和红系祖细胞。我们将使用多种基因组方法系统地分析 Tet1-S过表达对5mhC/MC分布、染色质可及性和基因的进行性影响 在造血干/祖细胞中表达。 我们的工作将对TET1-S上调在MDS AS发病机制中的独特作用提供新的见解 以及它在维持HSPC表观遗传景观和基因调控方面的具体作用和机制。

PROJECT SUMMARY Recent studies have revealed pervasive transcriptional regulation through alternative promoters in normal tissues and cancer. How the majority of alternative promoters contribute to tumor formation, diagnosis or treatment remains unknown. Tet1 was first identified as an MLL partner in AML. It belongs to the Tet (ten- eleven translocation) family of proteins (Tet1/2 and Tet3), which oxidize 5-methylcytosine (5mC) into 5- hydroxymethylcytosine (5hmC), and other oxi-mC intermediates, thereby facilitating DNA demethylation. Interestingly, we found that a short isoform of TET1 (referred to as TET1-S), which contains a catalytic domain but lacks the N-terminal CXXC domain, and is under control of an alternative promoter, was expressed in human bone marrow (BM) cells. Additionally, TET1-S was upregulated in BM cells from Myelodysplastic Syndrome (MDS) patients as compared to healthy individuals. We showed that TET1-S is expressed in BM cells at a much higher level compared with TET1-F. However, its role in the hematopoietic system is unknown. Based on our preliminary results, we hypothesize that Tet1-S plays an important role in the maintenance of hematopoietic stem cells (HSCs) and its upregulation contributes to the development of MDS by disrupting normal function of HSCs and hematopoiesis. To test this hypothesis, we will determine 1) the oncogenic role and underlying mechanisms of Tet1-S in the pathogenesis of MDS, 2) whether Tet1-S is required for the development of MDS, and 3) the molecular mechanisms by which Tet1-S regulates gene expression in HSPCs and erythroid progenitor cells. We will employ multiple genomic approaches to systematically analyze the progressive effects of Tet1-S overexpression on 5mhC/mC distribution, chromatin accessibility and gene expression in hematopoietic stem/progenitor cells. Our work will provide new insights into the distinct role of TET1-S upregulation in the pathogenesis of MDS as well as its specific role and mechanisms in maintaining epigenetic landscapes and gene regulation in HSPCs.