Defining Cell Lineages in the Bladder Urothelium

描述（由申请人提供）：揭示正常组织发育和更新的调控机制不仅是发育生物学的主要目标之一，也是阐明病理过程发展机制的重要步骤。尿路上皮形成和维持的方式在很大程度上是未知的，尿路上皮干细胞的存在是有争议的。该建议旨在定义膀胱尿路上皮细胞谱系和分化程序。我们最近已经证明，p53同源p63是所需的基底和中间细胞的尿路上皮的发展。 此外，通过进行囊胚互补实验，我们已经表明，伞细胞的urothelium的p63阳性的基底和中间细胞可以独立地开发和维护。这些结果挑战了目前认为基底/中间细胞是伞细胞的祖细胞的观点，并支持基底/中间细胞和伞细胞代表完全独立的细胞谱系的假设。本提案的目的是就这一假设是否正确提供一个明确的答案。事实上，虽然p63阳性的基底/中间细胞不是伞细胞形成所必需的，但p63阳性的基底/中间细胞在其他情况下（即在衰老期间或细胞损伤后）或与其他细胞类型结合时可能表现出干细胞能力。在这里，我们建议通过1）确定p63阳性的基底细胞和中间细胞是否需要在衰老过程中或细胞损伤后的尿路上皮伞细胞的更新2）确定是否p63阳性的基底细胞和中间细胞产生伞细胞通过进行遗传谱系追踪的中心假设进行测试。这些研究将阐明膀胱上皮细胞之间的谱系关系，并提供重要的见解尿路上皮干细胞的性质。

DESCRIPTION (provided by applicant): Unraveling the mechanisms regulating the development and renewal of normal tissues is not only one of the main goals of developmental biology but also an essential step for the elucidation of the mechanisms underlying the development of pathological processes. The way the urothelium is formed and maintained is largely unknown and the existence of urothelial stem cells is controversial. This proposal aims at defining cell lineages and differentiation programs in the bladder urothelium. We have recently demonstrated that the p53-homologue p63 is required for the development of basal and intermediate cells of the urothelium. Additionally, by performing blastocyst complementation experiments we have shown that umbrella cells of the urothelium of can develop and be maintained independently from p63-positive basal and intermediate cells. These results challenge the current view that basal/intermediate cells are the progenitors of umbrella cells and support the hypothesis that basal/intermediate cells and umbrella cells represent entirely independent cell lineages. The goal of this proposal is to provide a definitive answer on whether or not this hypothesis is correct. In fact, although p63-positive basal/intermediate cells are not required for the formation of umbrella cells, it is possible that p63-positive basal/intermediate cells exhibit stem cells capabilities in other circumstances (i.e. during aging or after cell damage) or in conjunction with other cell types. Here we propose to test the central hypothesis by 1) determining if p63-positive basal and intermediate cells are required for the renewal of urothelial umbrella cells during aging or after cell injury 2) determining if p63-positive basal and intermediate cells give rise to umbrella cells by performing genetic lineage tracing. These studies will clarify lineage relationships among bladder epithelial cells and provide important insights into the nature of urothelial stem cells.