JAK/STAT Signaling in Hematopoietic Stem Cells

描述(申请人提供)：这项工作的长期目标是 识别和表征可能在两种正常情况下都发挥重要作用的基因 和恶性血液病。具体地说，我们有兴趣定义 造血干细胞自我更新与分化的调控 细胞命运的决定。造血干细胞对骨髓(BM)有潜在用途 基因疾病和癌症的移植，作为基因治疗的目标， 并作为体外生成血细胞产品的前体。体外实验 保持原始属性和功能活动的HSC的扩展 仍然是一个重要的研究目标，考虑到 HSCs的潜在应用。生长因子信号转导 已知的途径是通过以下途径影响特定谱系的HSC分化 作为生存因子防止细胞凋亡，并通过传递一种 增殖信号。HSCs与BM相互作用的附加调制 间质微环境可由生长因子刺激引起。我们的目标 该项目的目的是确定JAKISTAT信号的要求 肝星状细胞对特定生长因子反应的转导途径 可以激活STATS并在短期体外保持HSC活性 文化。在造血干细胞中可以利用多种信号转导途径 在配体与细胞表面受体结合后，因此这些 路径可能是多余的。因此，统计信息在原语中的作用 从生物化学分析不能预测造血水平 分化的细胞。我们的初步研究表明，来自 缺乏Stat5a和STAT5b表达的小鼠表现出明显的 在不减少绝对值的情况下进行竞争性的长期再填充活动 干细胞数量。然而，需要确定缺陷是否为 与细胞周期诱导、细胞凋亡或归巢/植入改变有关 才能。我们建议利用分子遗传学方法，如 逆转录病毒介导的小鼠基因转移和纯合子基因破坏 表征和区分STAT3和STAT5在 造血干细胞功能。将实现以下具体目标 在这项研究中。1)我们将确定STAT5在生长因子中的作用 活跃在造血干细胞中的信号通路。2)我们会 确定STAT3在活跃的生长因子信号通路中的作用 在造血干细胞中。总之，这项工作将提供对 造血干细胞的基本生物学，并可能最终导致新的方法 可移植干细胞的体外扩增用于治疗 可用于临床。

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.