The role of NPM1 in preserving a hematopoietic stem cell identity

NPM1基因突变被认为是急性髓系白血病(AML)发病的驱动因素。 核磷蛋白(NPM1)属于核磷蛋白/核浆蛋白(NPM)家族的核伴侣蛋白， 其中有三个基因：NPM1、NPM2(核纤溶酶)和NPM3，其蛋白质功能包括 染色质重塑、基因组稳定性、核糖体生物发生和胚胎发生。在人类中，NPM1具有 三种亚型，其中亚型1是主要类型，也是唯一在小鼠中表达的亚型。我的 博士后研究集中在一个基本的表观遗传学特征上，涉及双亲的局部循环 核小体，这表明被抑制但不活跃的染色质结构域是遗传的。在尝试 鉴定促进小鼠染色质抑制域遗传的组蛋白伴侣蛋白(S) 胚胎干细胞(MESCs)，我发现NPM1在这一过程中起着至关重要的作用(初步 数据)。虽然NPM1在细胞中的作用已经被很好地描述，但它在正常造血中的功能 仍然不为人知。 关于造血干细胞(HSCs)，表观基因组具有自我更新和分化的功能 HSC染色质状态的遗传在细胞周期中持续存在的功能。在这项提案中，我们将 确定NPM1在构建HSCs可遗传表观基因组中的分子基础并确定 这一过程中的异常功能有助于NPM1驱动的癌症突变的病因学。作为物种- 小鼠和人的NPM1生物学存在特定的差异，我们建议补充人类和 利用体外人和体内小鼠HSC分化系统的小鼠NPM1生物学。这些系统 包括体外人诱导多能干细胞(IPSCs)分化和衍生造血细胞 祖细胞(HPC)的去向和生长素诱导的变性(AID)小鼠NPM1耗竭模型的建立 NPM1蛋白在体内以靶向和调控的方式在HSC中表达。将人类IPSC技术与 辅助小鼠NPM1模型有可能在评估必要基因的功能方面开创先例 在疾病中经常发生突变的基因。在这种情况下，识别NPM1介导的染色质机制 构建可遗传的造血干细胞表观基因组及其在白血病中的异常功能所必需的。

NPM1 gene mutations are considered driver mutations in the pathogenesis of acute myeloid leukemia (AML). Nucleophosmin (NPM1) belongs to the nucleophosmin/nucleoplasmin (NPM) family of nuclear chaperones, of which there are three genes: NPM1, NPM2 (nucleoplasmin), and NPM3, whose protein functions include chromatin remodeling, genome stability, ribosome biogenesis, and embryogenesis. In humans, NPM1 has three isoforms of which isoform 1 is the predominant type and is the only one expressed in mouse. My postdoctoral studies focused on a fundamental epigenetic feature involving the local recycling of parental nucleosomes, which showed that repressed, but not active, chromatin domains are inherited. While attempting to identify a histone chaperone(s) that facilitates the inheritance of repressed chromatin domains in mouse embryonic stem cells (mESCs), I discovered that NPM1 plays an essential role in this process (preliminary data). While the role of NPM1 in the cell has been well characterized, its function in normal hematopoiesis remains unknown. With regard to hematopoietic stem cells (HSCs), the epigenome confers self-renewal and differentiation functions wherein inheritance of HSC chromatin states is persistent across cell cycles. In this proposal, we will identify the molecular basis of NPM1 in constructing the heritable epigenome of HSCs and determine whether aberrant function in this process contributes to the etiology of NPM1-driven cancer mutations. As species- specific differences exist between mouse and human NPM1 biology, we propose to complement human and mouse NPM1 biology utilizing in vitro human and in vivo mouse HSC differentiation systems. These systems include in vitro human induced Pluripotent Stem Cells (iPSCs) to differentiate and derive a hematopoietic progenitor cell (HPC) fate and developing an Auxin-induced degron (AID) mouse model for NPM1 to deplete NPM1 protein in vivo in a targeted and regulated manner in HSCs. Integrating human iPSC technology with an AID mouse model for NPM1 has the potential to set a precedent in assessing the function of essential genes that are frequently mutated in disease. In this instance, identifying NPM1 mediated chromatin mechanisms necessary for constructing the heritable epigenome of HSCs and its aberrant function in leukemia.