Mechanisms of tubule interconnection

 描述(申请人提供)：肾脏疾病在美国影响着2000多万人，是第八大死因。它也是高血压和糖尿病等慢性疾病代价最高的并发症之一。肾脏再生的进展可能减缓或逆转肾衰竭的进展，这将对人类健康产生重大影响。基于细胞的肾脏再生疗法的一个长期目标是使用工程化的肾祖细胞来产生新的肾单位，并替换受损肾脏中的受损肾单位。肾前体细胞也被探索用于在工程或天然器官支架中体外生成肾单位。在任何一种情况下，肾单位的功能都需要一个用于滤液流动、处理和动态平衡的专利管腔；即适当的管道。肾发育过程中，S形体远端的细胞侵入输尿管上皮，正常建立肾小管腔间连接。然而，在成熟的肾脏中，移植的肾祖细胞可能会分化为小管，但无法连接到现有的分支收集系统，对肾脏功能没有贡献。这项建议旨在通过确定介导肾小管-集合管融合的生长因子来克服这一障碍，并确定在肾脏再生过程中如何诱导小管相互连接。利用斑马鱼成年肾脏作为同步肾小管-集合管融合的模型，我们将1)用小分子抑制物筛选成熟的Wnt和Fgf信号通路，并检测小管的相互连接；2)检测生长因子的时空限制性表达或显性阴性的小GTP酶信号抑制物对肾小管-集合管融合的影响。这些研究将为以细胞和组织为基础的肾脏再生治疗所需的基本但未被充分研究的细胞机制提供重要的新见解。

 DESCRIPTION (provided by applicant): Kidney disease affects more than 20 million people in the United States and is the 8th leading cause of death. It is also one of the costliest complications of chronic illness, such as hypertension and diabetes. Advances in kidney regeneration that could slow or reverse progression to kidney failure will have a major impact on human health. A long-term goal of cell-based therapies for kidney regeneration is to use engineered renal progenitor cells to generate new nephrons and replace damaged nephrons in injured kidneys. Renal progenitor cells are also being explored for use in generating nephrons ex vivo in engineered or natural organ scaffolds. In either case, nephron function requires a patent lumen for filtrate flow, processing, and homeostasis; i.e., proper plumbing. Tubule lumen interconnections are established normally during renal development by invasion of the ureter epithelium by cells of the distal S-shaped body. However, in a mature kidney, implanted renal progenitor cells may differentiate into tubules but fail to connect to an existing branched collecting system and do not contribute to kidney function. This proposal aims to overcome this hurdle by identifying growth factors that mediate nephron tubule-collecting duct fusion and determine how tubule interconnection can be induced during renal regeneration. Using the zebrafish adult kidney as a model of synchronous nephron tubule-collecting duct fusion we will 1) screen well-established Wnt and FGF signaling pathways with small molecule inhibitors and assay tubule interconnection and 2) test the effect of spatially and temporally restricted expression of growth factors or dominant negative small GTPase signaling inhibitors on nephron tubule- collecting duct fusion. These studies will provide important new insights about an essential but understudied cellular mechanism that is required for cell and tissue-based renal regeneration therapies.