A Mouse Model of DNMT3A-Associated Hematologic Malignancy

描述（由申请方提供）：从头DNA甲基转移酶3A（DNMT 3A）突变与多种血液恶性肿瘤相关，包括骨髓性和淋巴性白血病;然而，此类突变导致其发生的机制尚不清楚。鼠造血干细胞（HSC）中Dnmt 3a功能的丧失导致HSC急剧扩增并抑制分化，而没有明显的白血病，这表明其他基因中的共发生突变对于白血病发展的重要性。在这里，我们的首要目标是深入了解潜在的病理生理机制，通过该机制，DNMT 3A突变改变了疾病的进程，给出了类似的突变谱。我们假设Dnmt 3a通过阻止干细胞自我更新基因的抑制、抑制分化和扩增靶细胞群体来使干细胞和/或早期祖细胞丧失转化的启动子，所述靶细胞群体然后对继发性致癌命中的影响敏感。我们预计，细胞环境，在细胞类型，年龄和甲基化程度的损失影响类型的白血病的发展。通过使用我们的小鼠模型研究Dnmt 3a突变的作用，我们希望阐明DNMT 3A突变如何导致一系列恶性肿瘤。为了实现这一目标，我们将使用Dnmt 3a-FLT 3-ITD模型来检查突变类型对骨髓与淋巴恶性肿瘤的产生的影响。将FLT 3-ITD引入Dnmt 3a突变型HSC和祖细胞中，并检查所产生疾病的类型和潜伏期。我们还将研究生物环境在衰老方面的作用。此外，我们将研究合作FLT 3突变的靶细胞类型对疾病结局的影响。最后，将检查Dnmt 3a突变加速和改变FLT 3-ITD表达影响的机制。具体而言，将比较具有和不具有Dnmt 3a突变的类似恶性肿瘤的全基因组甲基化谱和基因表达模式。甲基化改变也将与在携带DNMT 3A突变的类似人类白血病中发现的那些进行比较。最终，这些数据将使我们能够广泛地确定DNA甲基化在人类白血病发展中的作用。总之，这些方法将有助于深入了解DNMT 3A突变促进各种人类血液恶性肿瘤的方式，并导致开发DNMT 3A相关恶性肿瘤的新治疗方法。

DESCRIPTION (provided by applicant): Mutations of the de novo DNA methyltransferase 3A (DNMT3A) are associated with multiple hematologic malignancies, including both myeloid and lymphoid leukemias; however, the mechanisms through which such mutations contribute to their development is obscure. Loss of Dnmt3a function in murine hematopoietic stem cells (HSCs) led to dramatic HSC expansion and inhibited differentiation without frank leukemia suggesting the importance of co-occurring mutations in other genes for leukemia development. Here, our overarching goal is to gain insight into the underlying pathophysiologic mechanisms through which DNMT3A mutations alter the course of disease given an otherwise similar mutational profile. We hypothesize that Dnmt3a loss primes stem cells and/or early progenitors for transformation by preventing the repression of stem cell self-renewal genes, inhibiting differentiation, and expanding a target cell population that is then sensitized to the impact of secondary oncogenic hits. We expect that the cellular milieu, in terms of cell type, age, and degree of methylation loss influences the type of leukemia that develops. By investigating the role of Dnmt3a mutations using our mouse model, we hope to elucidate how DNMT3A mutations contribute to an array of malignancies. Toward this goal, we will examine the influence of the mutation type on the generation of myeloid versus lymphoid malignancies using a Dnmt3a-FLT3-ITD model. FLT3-ITD will be introduced into Dnmt3a-mutant HSCs and progenitors and the type and latency of disease generated will be examined. We will also examine the role of the organismal milieu in terms of aging. In addition, we will examine the influence of the target cell type of cooperating FLT3 mutations on the disease outcome. Finally, the mechanism through which Dnmt3a mutation accelerates and alters the impact of FLT3-ITD expression will be examined. Specifically, the whole genome methylation profile and gene expression patterns of similar malignancies with and without Dnmt3a mutations will be compared. Methylation alterations will also be compared with those found in similar human leukemias harboring DNMT3A mutations. Ultimately, these data will allow us to identify the role of DNA methylation broadly, and at specific loci in human leukemia development. Together, these approaches will lend insight into the manner in which DNMT3A mutations promote a variety of human hematologic malignancies and lead to development of new therapeutic approaches for DNMT3A-associated malignancies.