Regulation of Hematopoietic Stem Cell Self Renewal

造血干细胞自我更新的调控

• 批准号: 8113186
• 负责人: Marie-Dominique Filippi
• 金额: $ 19.13万
• 依托单位: CINCINNATI CHILDRENS HOSP MED CTR
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-08-01 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8113186
• 关键词: Address; Biological Assay; Blood; Blood Cells; Bone Marrow; CDKN2A gene; Cell Cycle Kinetics; Cell Polarity; Cell Separation; Cell division; Cell physiology; Cells; Centrosome; Clinical; Commit; Cues; Cytoskeleton; Data; Defect; Development; Devices; Disease; Engraftment; Equilibrium; Family; Future; Genes; Hematopoiesis; Hematopoietic Stem Cell Transplantation; Hematopoietic System; Hematopoietic stem cells; Homeostasis; Image; Immune; Immunofluorescence Immunologic; In Vitro; Injury; Insulin; Insulin-Like Growth Factor I; Life; Malignant Neoplasms; Mediating; Mesenchymal; Molecular; Null Lymphocytes; Organism; Pancytopenia; Pathway interactions; Patients; Physiological; Play; Process; Production; Property; Protocols documentation; Regulation; Regulatory Pathway; Role; Secondary to; Signal Pathway; Signal Transduction; Stem cells; Stress; Testing; Time; Tissues; Transplantation; Undifferentiated; adult stem cell; daughter cell; design; exhaustion; hematopoietic stem cell fate; in vivo; insulin signaling; leukemia; member; mutant; novel therapeutic intervention; prevent; public health relevance; reconstitution; regenerative; rho; rho GTP-Binding Proteins; segregation; self-renewal; stem cell fate; success

DESCRIPTION (provided by applicant): Tissue diversity is created through stem cell asymmetric self renewal division. Stem cell fate decision during division is thus fundamental for tissue homeostasis. Like other types of adult stem cells, hematopoietic stem cells (HSC) can produce daughter cells with distinct fates. Since both uncontrolled HSC expansion as well as loss of HSC is fatal for the organism, the decision of self renewal versus differentiation must be tightly controlled. An understanding of the molecular mechanism(s) of HSC fate decision is thus of considerable clinical importance. This application focuses on understanding the role of p190-B RhoGAP, a negative regulator of Rho GTPase activity, in HSC self renewal and fate decision. Our analysis of p190-B-null HSC shows that p190-B is essential for the regulation of HSC self renewal following transplantation. We show that loss of p190-B results in enhanced long term engraftment during serial transplantation. While the number of WT HSCs in the bone marrow of secondary recipients decreases in comparison with primary recipients, the numbers of p190-B-null HSCs is maintained between the secondary and primary recipients. At the same time, p190-B-null HSCs retain multipotential lineage differentiation. Thus, loss of p190-B prevents HSC exhaustion to maintain hematopoiesis during serial transplantation. At a mechanistic level, p190-B-deficiency did not alter HSC cell cycle kinetics or survival both in vivo and in vitro - thus, suggesting that p190-B modulates HSC self renewal activity as the cells divide. These data suggest the hypothesis that p190-B is a critical regulator of HSC self renewal by modulating HSC fate decision during divisions. We propose to identify the signaling pathway modulated by p190-B in HSC self renewal; and to determine the mechanism(s) by which p190-B and the associated signaling pathway regulates HSC fate decision. We plan to use functional assays of HSC functions, video microcopy, immunofluorescence imaging to examine (Aim 1) the role of IGF-1 signaling and p16Ink4a in p190-B-mediated HSC self renewal; (Aim 2) determine the role of p190-B and downstream signaling pathway identified in aim1 in mechanism of cell polarity that influences the segregation of cell fate determinant to control the balance of asymmetric/symmetric self renewal divisions. We believe that analysis of p190-B-null HSC offers a rare opportunity to identify stem cell-specific genes that are important for HSC fate decision. If our hypothesis that p190-B regulates HSC fate decision via IGF-1/p16Ink4a is validated, this will significantly change the view of IGF-1 signaling and p16Ink4a functions in HSC self renewal. The tremendous potential of HSC to reconstitute the hematopoietic system has allowed the development of clinical HSC transplantation to treat a wide variety of diseases. The proposed studies are expected to provide rationales to devise new therapeutic approaches of clinical HSC transplantation protocols. PUBLIC HEALTH RELEVANCE: Hematopoietic stem cell self renewal is a fundamental process to maintain continuous blood cell production throughout life. Deregulation of HSC self renewal leads to cancer or tissue degeneration. The tremendous potential of HSC to reconstitute the hematopoietic system has allowed the development of clinical HSC transplantation to treat a wide variety of diseases, including bone marrow failure or leukemias. The success of HSC transplantation is however limited due to our inability to control HSC functions. The studies proposed in this application will provide important information of the physiologic role of p190-B RhoGAP in the regulation of HSC self renewal. Therefore, our study will guide designing strategies to modulate HSC functions via inhibition of p190-B Rho GAP that could be used in the future to device new therapeutic approaches of clinical HSC transplantation protocols.

描述（由申请人提供）：组织多样性是通过干细胞不对称自我更新分裂产生的。因此，分裂过程中干细胞的命运决定对于组织稳态至关重要。与其他类型的成体干细胞一样，造血干细胞（HSC）可以产生具有不同命运的子细胞。由于不受控制的 HSC 扩增和 HSC 损失对生物体都是致命的，因此必须严格控制自我更新与分化的决定。因此，了解 HSC 命运决定的分子机制具有相当大的临床重要性。本应用重点了解 p190-B RhoGAP（Rho GTP 酶活性的负调节因子）在 HSC 自我更新和命运决定中的作用。我们对 p190-B-null HSC 的分析表明，p190-B 对于移植后 HSC 自我更新的调节至关重要。我们发现 p190-B 的缺失会导致连续移植过程中长期植入的增强。虽然与初次受者相比，二次受者骨髓中的 WT HSC 数量有所减少，但 p190-B-null HSC 的数量在二次受者和初次受者之间保持不变。同时，p190-B-null HSC 保留多能谱系分化。因此，p190-B 的缺失可防止 HSC 在连续移植过程中耗尽以维持造血功能。在机制水平上，p190-B 缺陷不会改变 HSC 细胞周期动力学或体内和体外存活 - 因此，表明 p190-B 在细胞分裂时调节 HSC 自我更新活性。这些数据表明，p190-B 通过调节分裂期间 HSC 的命运决定，是 HSC 自我更新的关键调节因子。我们建议鉴定 p190-B 在 HSC 自我更新中调节的信号通路；并确定 p190-B 和相关信号通路调节 HSC 命运决定的机制。我们计划使用 HSC 功能分析、视频显微镜、免疫荧光成像来检查（目标 1）IGF-1 信号传导和 p16Ink4a 在 p190-B 介导的 HSC 自我更新中的作用； （目标2）确定p190-B和aim1中确定的下游信号通路在细胞极性机制中的作用，影响细胞命运决定因素的分离，以控制不对称/对称自我更新分裂的平衡。我们相信，p190-B-null HSC 的分析为鉴定对 HSC 命运决定重要的干细胞特异性基因提供了难得的机会。如果我们关于 p190-B 通过 IGF-1/p16Ink4a 调节 HSC 命运决定的假设得到验证，这将显着改变 IGF-1 信号传导和 p16Ink4a 在 HSC 自我更新中功能的观点。造血干细胞重建造血系统的巨大潜力使得临床造血干细胞移植的发展能够治疗多种疾病。拟议的研究预计将为设计临床 HSC 移植方案的新治疗方法提供依据。 公众健康相关性：造血干细胞自我更新是维持一生持续血细胞生成的基本过程。 HSC 自我更新的失调会导致癌症或组织退化。造血干细胞重建造血系统的巨大潜力使得临床造血干细胞移植的发展能够治疗多种疾病，包括骨髓衰竭或白血病。然而，由于我们无法控制 HSC 功能，HSC 移植的成功受到限制。本申请中提出的研究将提供 p190-B RhoGAP 在 HSC 自我更新调节中的生理作用的重要信息。因此，我们的研究将指导设计通过抑制 p190-B Rho GAP 来调节 HSC 功能的策略，该策略可在未来用于设计临床 HSC 移植方案的新治疗方法。