Molecular Genetic Study of Stem Cells, Cancer Stem Cells

干细胞、癌症干细胞的分子遗传学研究

• 批准号: 7338821
• 负责人: xianyu s Hou
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7338821
• 关键词: Molecular; Genetic; Study; Stem; Cells

Investigate the molecular mechanism that regulates male germline stem cell self-renewal or differentiation in DrosophilaAt the tip of the Drosophila testis (apex) is a germinal proliferation center, which contains the germline and somatic stem cells that maintain spermatogenesis. Each germline stem cell (GSC) is encysted by two somatic stem cells (SSCs). Both GSCs and SSCs anchor to a group of 12 nondividing somatic cells, called the "hub," through cell adhesion molecules. The hub defines the stem-cell niche by expressing the growth factor Unpaired (Upd), which activates the JAK/STAT pathway in GSCs to regulate stem-cell self-renewal. We have undertaken a number of genetic experiments in the last two years to further understand stem cell regulation and the role of the JAK/STAT signaling in this system. We have been focusing on:A-1. Identifying the signal (s) that regulates stem cell anchoring to the niche.In a genetic screen for mutations that interact with the JAK/STAT signal transduction pathway in regulating male GSC fates, we identified a small GTPase Rap guanine nucleotide exchange factor (Gef26) from our library of P-element mutations. We demonstrated that Rap-GEF/Rap signaling controls stem cell anchoring to the niche through regulating DE-cadherin-mediated cell adhesion (Wang et al., Dev. Cell 10:117-126, 2006). A-2. Identifying the downstream target of the JAK/STAT signal transduction pathway. Birt-Hogg-Dub (BHD) syndrome gene is a novel kidney tumor suppressor that was recently cloned by Dr. Berton Zbar's group in our laboratory. Dr. Zbar and I started collaboration on a project of studying the BHD gene's function in Drosophila. Through the use of RNAi to decrease expression of the Drosophila BHD homologue (DBHD), we have demonstrated that DBHD is required for male GSC maintenance in the fly testis. Further genetic interaction experiments suggest that DBHD regulates GSC maintenance downstream of the JAK/STAT and Dpp/TGF-? signal transduction pathways. These findings suggest that the BHD protein may regulate tumorigenesis through modulating stem cells in human (Manuscript submitted).A-3. Understanding how the GSCs and SSCs coordinate their self-renewal and differentiation. In many tissues, two or more types of stem cells share a niche, and how the stem cells coordinate their self-renewal and differentiation is poorly understood. In the Drosophila testis, germline stem cells (GSCs) and somatic stem cells (SSCs) contact each other and share a niche (the hub). The hub expresses a growth factor Unpaired (Upd) that activates the JAK/STAT pathway in GSCs to regulate the stem cell self-renewal. However, it is not clear how SSC cells are regulated and how SSCs and GSCs coordinate their self-renewal or differentiation. Through generating stat mutant SSC clones and selectively manipulating the JAK/STAT signaling level in either SSCs or GSCs, we demonstrated that the JAK/STAT signaling also regulates self-renewal of SSCs, but the JAK/STAT signaling in GSCs and in SSCs function differentially in coordinating self-renewal or differentiation of GSCs and SSCs. The somatic JAK/STAT signaling is essential for self-renewal and maintenance of both SSCs and GSCs; the germline JAK/STAT signaling is required for GSC self-renewal and maintenance but negatively regulates these functions in SSCs. These data suggest that a single signal from the niche regulates the self-renewal of both GSCs and SSCs; GSC-SSC interaction maintains their stability and coordinates their self-renewal or differentiation. (Manuscript submitted).A-4. Knocking out the mouse orthologs of Gef26. There are two mouse orthologs of Gef26, RapGEF1 and RapGEF2. There is a RapGEF1 mutant ES cell line available from Bay Genomics. We have purchased the ES cell line and are in the process of generating the RapGEF1 gene knockout mouse.

研究调节果蝇中男性种系干细胞自我更新或分化的分子机制。果蝇睾丸（APEX）的尖端是一个生发增殖中心，其中包含维持精子发生的生殖细胞和体细胞。每个种系干细胞（GSC）都被两个体细胞（SSC）所包含。 Both GSCs and SSCs anchor to a group of 12 nondividing somatic cells, called the "hub," through cell adhesion molecules.集线器通过表达未配对的生长因子（UPD）来定义干细胞生态位，该因子激活GSC中的JAK/STAT途径以调节干细胞自我更新。在过去的两年中，我们进行了许多基因实验，以进一步了解干细胞调节以及JAK/STAT信号在该系统中的作用。我们一直专注于：A-1。在调节男性GSC命运时与JAK/STAT信号转导途径相互作用的突变的遗传筛选中，确定了调节干细胞的信号，在调节男性GSC命运时，我们发现了一个小的GTPase RAP RAP核苷酸核苷酸交换因子（GEF26）来自我们的P元素库中的库。我们证明了RAP-GEF/RAP信号传导通过调节去钙粘蛋白介导的细胞粘附来控制干细胞锚定位于细分市场上（Wang等，Dev。Cell10：117-126，2006）。 A-2。识别JAK/STAT信号转导途径的下游目标。 Birt-Hogg-Dub（BHD）综合征基因是一种新型的肾脏肿瘤抑制剂，最近由Berton Zbar博士的小组克隆在我们的实验室中。我和Zbar博士开始在研究果蝇中研究BHD基因功能的项目。通过使用RNAi降低果蝇BHD同源物（DBHD）的表达，我们证明了DBHD是蝇睾丸中雄性GSC维持所必需的。进一步的遗传相互作用实验表明，DBHD​​调节JAK/STAT和DPP/TGF-下游的GSC维护？信号转导途径。这些发现表明，BHD蛋白可以通过调节人的干细胞（手稿提交）.A-3来调节肿瘤发生。了解GSC和SSC如何协调其自我更新和差异化。在许多组织中，两种或多种类型的干细胞共享一个小众，以及干细胞如何协调其自我更新和分化的理解很少。在果蝇睾丸中，种系干细胞（GSC）和体细胞（SSC）相互接触并共享一个小众（枢纽）。枢纽表达了一个未配对的生长因子（UPD），该生长因子激活GSC中的JAK/STAT途径以调节干细胞自我更新。但是，尚不清楚如何调节SSC细胞以及SSC和GSC如何协调其自我更新或分化。通过生成SCSS或GSC中JAK/Stat信号级别的Stat Stat突变体SSC克隆，并有选择地操纵JAK/Stat信号级别，我们证明了JAK/Stat信号还调节了SSC的自我更新，但是GSC中的JAK/Stat信号在GSC中和SSC中的JAK/Stat信号在sscs中的功能差异化，可在GORDICINICS和SSC中差异化。体细胞/统计信号对于自我更新和维护SSC和GSC至关重要。 GSC自我更新和维护需要种系JAK/STAT信号传导，但对SSC中的这些功能负面调节。这些数据表明，来自利基市场的单个信号调节了GSC和SSC的自我更新。 GSC-SSC相互作用保持其稳定性，并协调其自我更新或差异化。 （提交手稿）.A-4。淘汰GEF26的小鼠直系同源物。 GEF26，Rapgef1和Rapgef2有两个小鼠直系同源物。海湾基因组学可用Rapgef1突变体ES细胞系。我们已经购买了ES细胞系，并且正在生成Rapgef1基因敲除鼠标。