Genetic modulators of erythro-megakaryocytic development

描述（申请人提供）：编码转录因子加塔-1的基因的体细胞突变与唐氏综合征（DS，21三体）儿童的急性巨核细胞白血病（AMKL）相关，尽管这种遗传相互作用的机制尚不清楚。在初步研究中，我证明了21三体本身增加了人类红细胞和巨核细胞祖细胞的增殖能力。在平行的小鼠研究中，我使用遗传操作的胚胎干细胞来显示加塔-1的缺失促进了双能巨核细胞-红系前体细胞（MEP）的扩增，MEP是一种类似于AMKL母细胞的群体。通过突变MEP的遗传互补，我发现加塔-1部分通过抑制原癌基因PU.1/Sfpi 1的转录来抑制骨髓分化的程序。AMKL相关的GATA 1突变减弱了这种作用。总之，我的研究结果产生了两个相关的假设：首先，GATA 1突变和21三体对造血产生不同的影响，它们共同作用促进白血病。其次，加塔-1通过抑制PU.1/Sfpi 1转录促进正常造血，并且该过程可能通过与DS-AMKL相关的遗传改变而变得失调。本申请旨在支持指导研究经验，以阐明加塔-1如何控制正常造血以及失调的加塔-1和DS如何在白血病发生中协同作用。我将扩展我在DS胎儿造血方面的研究，以了解21三体扩增红细胞和巨核细胞祖细胞的机制（目的1）。我将在体外和小鼠中研究人类造血祖细胞中改变的加塔-1和21三体之间的功能相互作用（目的2）。最后，我将研究野生型和AMKL相关的加塔-1突变体抑制PU的机制。1/SfpH癌基因转录（Aim 3）。如果成功的话，我的研究将为正常红巨核细胞发育的转录控制以及AMKL如何干扰这一过程提供见解。这项研究的更广泛的影响是更好地了解谱系特异性转录因子如何在正常组织发育和癌症中发挥作用。结合我在此应用程序中的培训和结构化指导，我相信拟议的研究将为正常和恶性造血提供新的见解，并为建立我作为儿科医生科学家的职业生涯提供坚实的基础。

DESCRIPTION (provided by applicant): Somatic mutations in the gene encoding transcription factor GATA-1 are associated with acute megakaryoblastic leukemia (AMKL) in children with Down syndrome (DS, trisomy 21), although the mechanisms underlying this genetic interaction are unknown. In preliminary studies, I demonstrated that trisomy 21 itself increases the proliferative capacity of human erythroid and megakaryocyte progenitors. In parallel murine studies, I used genetically manipulated embryonic stem cells to show that loss of GATA-1 promotes the expansion of bipotential megakaryocyte-erythroid precursors (MEPs), a population that resembles AMKL blasts. Through genetic complementation of the mutant MEPs, I discovered that GATA-1 represses a program of myeloid differentiation, in part by inhibiting transcription of the protooncogene PU.1/Sfpi1. This effect is attenuated by AMKL-associated GATA1 mutations. Together, my findings generate two related hypotheses: First, GATA1 mutations and trisomy 21 produce distinct effects on hematopoiesis, which act together to promote leukemia. Second, GATA-1 promotes normal hematopoiesis by repressing PU.1/Sfpi1 transcription and this process may become dysregulated through genetic alterations associated with DS-AMKL. This application is to support a mentored research experience to elucidate how GATA-1 controls normal hematopoiesis and how dysregulated GATA-1 and DS synergize in leukemogenesis. I will extend my studies in DS fetal hematopoiesis to understand the mechanisms by which trisomy 21 expand erythroid and megakaryocytic progenitors (Aim 1). I will examine functional interactions between altered GATA-1 and trisomy 21 in human hematopoietic progenitors in vitro and in mice (Aim 2). Lastly, I will study the mechanisms by which wild type and AMKL-associated mutant forms of GATA-1 repress PU. 1/SfpH oncogene transcription (Aim 3). If successful, my research will provide insights into the transcriptional control of normal erythromegakaryocytic development and how this process becomes disturbed in AMKL. The broader impact of this research is to better understand how a lineage-specific transcription factor functions in normal tissue development and cancer. Combined with my training and structured mentoring in this application, I believe that the proposed research will provide novel new insights into normal and malignant hematopoiesis and provide a strong foundation to establish my career as a pediatric physician-scientist.