JAK/STAT Signaling in Hematopoietic Stem Cells

描述（由申请人提供）：这项工作的长期目标是 识别和表征可能在正常和免疫系统中起重要作用的基因， 和恶性造血具体来说，我们感兴趣的是定义 造血干细胞（HSC）自我更新与分化的调节因子 细胞命运的决定造血干细胞对骨髓（BM） 用于遗传疾病和癌症的移植，作为基因治疗的靶点， 和作为体外产生血细胞产物的前体。离体 维持原始特性和功能活性的HSC扩增 仍然是一个重要的研究目标，考虑到数量 HSC的潜在应用。生长因子信号转导 已知途径通过以下方式影响HSC沿沿着特定谱系的分化 作为存活因子来防止细胞凋亡， 增殖信号HSC与BM相互作用的额外调节 基质微环境可由生长因子刺激引起。我们的目标 确定JAKISTAT信号的要求 HSC对特异性生长因子的应答中的转导途径， 在短期离体过程中， 文化HSCs中存在多种信号转导途径 配体与细胞表面受体结合后， 路径可能是多余的。因此，STAT在原始细胞中的作用 血细胞生成水平不能从血液生化分析预测， 分化细胞我们的初步研究表明， 缺乏STAT 5a和STAT 5 b表达的小鼠显示出显著的 竞争性的长期繁殖活动，而不减少绝对 干细胞数量然而，需要确定缺陷是否 与细胞周期诱导、细胞凋亡或归巢/植入改变相关 能力我们建议利用分子遗传学方法， 逆转录病毒介导的基因转移和纯合基因破坏， 描述和区分STAT 3和STAT 5在 造血干细胞功能将处理以下具体目标 本研究1)我们将确定STAT 5在生长因子 造血干细胞中活跃的信号通路。2)我们将 确定STAT 3在生长因子信号通路中的作用， 在造血干细胞中。总之，这项工作将提供洞察力， HSC的基础生物学，并可能最终导致新的方法， 体外扩增可移植干细胞用于治疗方法， 可以用于临床。

DESCRIPTION (provided by applicant): The long-term objectives of this work are to identify and characterize genes that may play important roles in both normal and malignant hematopoiesis. Specifically, we are interested in defining regulators of hematopoietic stem cell (HSC) self-renewal versus differentiation cell fate decisions. HSCs are potentially useful for bone marrow (BM) transplantation for genetic disease and cancer, as targets for gene therapy, and as precursors for generation of blood cell products in vitro. Ex vivo expansion of HSCs that maintain primitive properties and functional activity continues to be an important research objective, considering the number of potential applications for use of HSCs. Growth factor signal transduction pathways are known to affect HSC differentiation along specific lineages by acting as survival factors to prevent apoptosis and by imparting a proliferative signal. Additional modulation of interactions of HSCs with the BM stromal microenvironment can be caused by growth factor stimulation. Our goal for this project is to determine the requirement for the JAKISTAT signal transduction pathway in the response of HSCs to specific growth factors that can activate STATs and also maintain HSC activity during short-term ex vivo culture. Multiple signal transduction pathways could be utilized in HSCs following ligand binding to the cell surface receptor and therefore these pathways could be redundant. For this reason, the role of STATs in primitive levels of hematopoiesis cannot be predicted from biochemical analysis of differentiated cells. Our initial studies have revealed that stem cells from mice lacking STAT5a and STAT5b expression show a marked deficiency in competitive long-term repopulating activity without a reduction in the absolute stem cell number. However, it needs to be determined whether the defect is related to cell cycle induction, apoptosis, or alteration in homing/engraftment ability. We propose to utilize molecular genetic approaches such as retroviral-mediated gene transfer and homozygous gene disruption in mice to characterize and distinguish the functional roles of STAT3 and STAT5 in hematopoietic stem cell function. The following specific aims will be addressed in this study. 1) We will determine the role of STAT5 in growth factor signaling pathways that are active in hematopoietic stem cells. 2) We will determine the role of STAT3 in growth factor signaling pathways that are active in hematopoietic stem cells. Altogether, this work will provide insight into the basic biology of HSCs and perhaps ultimately lead to novel methods for expansion of transplantable stem cells in vitro for therapeutic approaches that could be used clinically.