Biochemistry of Leukemia Virus Core-Binding Factor

总结 这项提案的目标是了解造血干细胞（HSC）是如何在体内形成的。 胚胎成人骨髓中的所有HSC都是前造血干细胞（前造血干细胞）的后代。 造血干细胞（HSC），从造血内皮（HE）细胞分化在主要的尾动脉的 胚胎然而，只有一个造血细胞的子集，从HE细胞分化， 动脉是前HSC，而许多是定向淋巴-骨髓偏向祖细胞。我们 生成了一个全面的单细胞数据集， 从动脉内皮细胞到淋巴-骨髓偏向的祖细胞和前HSC。此数据集 是一个强大的工具，用于产生和测试新的概念，在HSC个体发育。一个发现来自 该分析是HE细胞的内皮细胞前体，我们将其命名为pre-HE。前HE细胞是 过渡群体，其中有限数量的细胞将被指定为HE。我们 发现前HE细胞分化成HE细胞的效率由以下决定： RUNX1的水平，RUNX1是一种在HE细胞中表达的转录因子，对HE至关重要 细胞规格我们还确定了Runx1基因中的一个候选增强子， 在前HE细胞中可获得。该提案的一个目标是确定Runx1前HE增强子是否 是前HE细胞分化为HE细胞所必需的，并且转录因子和 上游信号通路调节该增强子的活性。第二个重要发现是 我们定义了淋巴-骨髓偏向祖细胞和前- HSC，并鉴定了在这些群体中的每一个中特异性表达的基因。其中一 基因，Mecom，这是已知的调节成人HSC增殖和功能，是更高的 在前-HSC中的表达比在淋巴-髓样偏向的祖细胞中的表达更高。我们将确定 内皮细胞中Mecom的表达调节生成的前HSC的数量 在造血发育过程中。了解动脉HE细胞是如何被指定和专门化的 将有助于指导正在进行的从其他细胞来源产生HSC的努力。

Summary The goal of this proposal is to understand how hematopoietic stem cells (HSCs) form in the embryo. All HSCs in the adult bone marrow are descendants of pre-hematopoietic stem cells (pre- HSCs) that differentiate from hemogenic endothelial (HE) cells in the major caudal arteries of the embryo. However, only a subset of hematopoietic cells that differentiate from HE cells in the arteries are pre-HSCs, while many are committed lympho-myeloid biased progenitors. We generated a comprehensive single cell dataset that captures the entire developmental trajectory from arterial endothelial cells to lympho-myeloid biased progenitors and pre-HSCs. This dataset is a powerful tool for generating and testing novel concepts in HSC ontogeny. One discovery from this analysis is an endothelial cell precursor of HE cells that we named pre-HE. Pre-HE cells are a transitional population from which a limited number of cells will be specified as HE. We discovered that the efficiency at which pre-HE cells differentiate into HE cells is determined by the levels of RUNX1, a transcription factor that is expressed in HE cells and is essential for HE cell specification. We also identified a candidate enhancer in the Runx1 gene that first becomes accessible in pre-HE cells. One goal of this proposal is to determine if the Runx1 pre-HE enhancer is required for the differentiation of pre-HE cells into HE cells, and which transcription factors and upstream signaling pathways regulate the activity of this enhancer. A second important finding is that we defined the molecular differences between lympho-myeloid biased progenitors and pre- HSCs, and identified genes specifically expressed in each of these populations. One of these genes, Mecom, which is known to regulate adult HSC proliferation and function, is more highly expressed in pre-HSCs than in lympho-myeloid biased progenitors. We will determine if the expression of Mecom in endothelial cells regulates the number of pre-HSCs that are generated during hematopoietic ontogeny. Understanding how arterial HE cells are specified and specialized will help guide ongoing efforts to generate HSCs from other cell sources.