Dissecting the canonical and non-canonical functions of Tet2 in hematopoietic stem cells and hematologic disorders

摘要 骨髓增生异常综合征（MDS）包括一组克隆性恶性血液病，其特征在于 无效造血加上形态发育不良，一般仍然无法治愈现有的非- 移植治疗10 - 11易位（泰特）蛋白质构成了一个酶家族， 通过DNA去甲基化来适当调节基因表达，TET 2是最常见的基因表达调控因子之一。 MDS中的突变基因Tet 2在造血中的作用已经在敲除小鼠中进行了大量研究; Tet 2缺失 导致造血进行性缺陷，包括造血干细胞的异常自我更新 （HSC）和Tet 2缺陷小鼠发展成慢性粒单核细胞白血病样疾病。然而，由于这些 由于小鼠缺乏完整的蛋白质，因此尚不清楚Tet 2的非催化功能如何促进HSC功能 和MDS发病机制。为了描述Tet 2的催化和非催化功能，我们有 建立Tet 2催化失活小鼠。使用这种新的遗传小鼠模型，我们获得了 有令人信服的证据表明Tet 2催化突变小鼠的血液学表型不如Tet 2 敲除小鼠这些初步的发现使我们假设，除了它在DNA中的酶作用外， 由于Tet 2的羟基化/去甲基化作用，Tet 2对于HSC的适当管理和MDS的抑制至关重要。 不依赖催化剂的方式。在这项研究中，我们将进行比较表观基因组，转录组和 Tet 2催化突变体和敲除小鼠的血液学分析，以确定 Tet 2在HSC稳态和MDS抑制中的作用我们有三个主要目标：（1）确定贡献 非催化Tet 2对HSC自我更新和分化的作用;（2）确定非催化Tet 2对HSC自我更新和分化的抑制作用。 Tet 2在Tet 2缺失驱动的MDS中的催化功能，以及（3）鉴定Tet 2的非催化靶点 用于抑制异常HSC稳态和MDS发展。这项研究将具有重大意义。 通过定义TET 2的非催化功能对MDS病因学的贡献对MDS领域的影响，以及 可以为MDS和其他血液病的治疗和管理带来新的治疗方法， 紊乱

ABSTRACT Myelodysplastic syndromes (MDS) comprise a group of clonal hematologic malignancies characterized by ineffective hematopoiesis coupled with morphologic dysplasia, and generally remains incurable by existing non- transplant therapy. The Ten-eleven translocation (TET) proteins constitute a family of enzymes that assure proper regulation of gene expression through DNA demethylation, and TET2 is one of the most frequently mutated genes in MDS. Tet2’s roles in hematopoiesis have largely been studied in knockout mice; Tet2 deletion causes progressive defects in hematopoiesis, including the aberrant self-renewal of hematopoietic stem cells (HSCs), and Tet2-deficient mice develop a chronic myelomonocytic leukemia-like disease. However, as these mice lack the entire protein, it is not known how the non-catalytic functions of Tet2 contribute to HSC function and MDS pathogenesis. In order to delineate the catalytic and non-catalytic functions of Tet2, we have established Tet2 catalytically inactive mice. Using this new genetic mouse model, we have obtained the compelling evidence that Tet2 catalytic mutant mice have less pronounced hematologic phenotypes than Tet2 knockout mice. These preliminary findings led us to hypothesize that, in addition to its enzymatic roles in DNA hydroxylation/demethylation, Tet2 is critical for the proper governance of HSCs and suppression of MDS in a catalytic-independent manner. In this study, we will conduct a comparative epigenomic, transcriptomic and hematologic analyses of Tet2 catalytic mutant and knockout mice to establish the non-catalytic requirements of Tet2 in HSC homeostasis and MDS suppression. We have three main goals: (1) to determine the contributions of non-catalytic Tet2 functions to HSC self-renewal and differentiation, (2) to define the suppressive roles of non- catalytic functions of Tet2 in loss-of-Tet2-driven MDS, and (3) to identify non-catalytic targets of Tet2 responsible for suppressing aberrant HSC homeostasis and MDS development. The proposed research will have a major impact on the MDS field by defining the contribution of the non-catalytic functions of TET2 to MDS etiology, and can lead to new therapeutic approaches for the treatment and management of MDS and other hematologic disorders.