Role of TET2 mutations in malignant transformation and acute myeloid leukemia

项目总结 TET2突变的鉴定及随后发现的DNMT3a和IDH1/2突变 髓系恶性肿瘤导致了这样的认识：DNA甲基化模式的动态变化 体细胞突变是造血转化的关键。Tet蛋白为铁/α-酮戊二酸 依赖于(Fe++/α-KG)的双加氧酶，并能将DNA5-甲基胞嘧啶(5mC)修饰为5-甲基胞嘧啶(5mC)。 羟基/甲酰基/羧基-胞嘧啶(5hmC，5fC，5caC)，导致随后的DNA去甲基化。TET2是 以一系列髓系恶性肿瘤的体细胞突变为靶点，包括10%-20%的急性髓系白血病。我们的 实验室已经领导了在髓系白血病和活体中表征TET2突变谱的研究 研究表明，TET2是一种单倍体不足的肿瘤抑制因子，可以增加造血干细胞 细胞自我更新和髓样转化。在这个奖项的支持下，我们能够详细地学习TET2 在白血病中起作用。我们鉴定了TET2相互作用的蛋白质，通过模拟TET2建立了疾病模型 与共发生的髓系疾病等位基因一致的变化，描绘了Tet1和TET2在 造血功能，采用技术在全基因组范围内定位TET2介导的5hmC沉积 在动物模型中恢复了TET2的活性，并确定了可以靶向TET2突变的化合物 髓系白血病。此外，我们还能够证明TET2突变是克隆中的一种启动事件 造血(CH)，然后为更多的躯体改变奠定基础，然后驱动 进展为髓系转化。这使我们处于极佳的地位，可以解决重大的新问题 与TET2在髓系白血病发生和发展中的分子作用有关的问题：1) 获得髓系中关键的TET2/协同突变的突变顺序和/或细胞室 转变？2)即使存在额外的突变，我们也能抑制疾病的进展吗？ 事件，如果我们恢复野生型TET2的表达和功能？3)之间有功能差异吗 TET2缺失和TET2错义突变在白血病患者子集中可见？我们将解决 通过使用最先进的小鼠模型、表观基因组图谱技术、 并对原发患者样本进行研究，以阐明TET2介导的转化的新机制。

PROJECT SUMMARY The identification of TET2 mutations and the subsequent discovery of DNMT3a and IDH1/2 mutations in myeloid malignancies has led to the realization that dynamic changes in DNA methylation patterns induced by somatic mutations are critical to hematopoietic transformation. The TET proteins are iron/α-ketoglutarate (Fe++/α-KG)-dependent dioxygenases and are able to modify 5-methylcytosine (5mC) on DNA to 5- hydroxy/formyl/carboxly-cytosine (5hmC, 5fC, 5caC), which leads to subsequent DNA demethylation. TET2 is targeted by somatic mutations in a spectrum of myeloid malignancies, including 10-20% of AML. Our laboratories have led studies characterizing the mutational spectra of TET2 in myeloid leukemias and in in vivo studies demonstrating that TET2 is a haploinsufficient tumor suppressor, which increases hematopoietic stem cell self-renewal and myeloid transformation. Supported by this award we were able to study in detail TET2 function in leukemia. We identified TET2 interacting proteins, generated disease models by modeling Tet2 alterations in concert with co-occurring myeloid disease alleles, delineated the relative role of Tet1 and Tet2 in hematopoietic function, employed techniques to map TET2-mediated 5hmC deposition at a genome-wide scale, and restored Tet2 activity in animal models and identified compounds that can target TET2-mutant myeloid leukemia. Moreover, we were able to show that TET2 mutations are an initiating event in clonal hematopoiesis (CH) that then “seeds” the ground for additional somatic alterations, which then drive progression to myeloid transformation. This places us in an excellent position to address significant new questions relating to the molecular roles of TET2 in the initiation and progression of myeloid leukemia: 1) Are mutational order and/or cell compartment which acquires TET2/cooperating mutations critical in myeloid transformation? 2) Can we suppress disease progression, even in the presence of additional mutational events, if we restore wild-type TET2 expression and function? 3) Are there functional differences between TET2 loss and TET2 missense mutations that are seen in a subset of leukemia patients? We will address these important questions through the use of state-of-the art mouse models, epigenomic profiling techniques, and studies in primary patient samples to elucidate novel mechanisms of TET2-mediated transformation.