The Role of Planar Cell Polarity Signals in Shaping Kidney Tubules

描述（由申请人提供）：哺乳动物和两栖动物肾小管的形成都需要Wnt通路。在肾脏中，异常的Wnt信号传导与肾母细胞瘤、囊性疾病以及肾细胞癌等发育病理有关。我们小组和其他人最近的研究表明，规范(？-catenin介导的)Wnt信号对于诱导肾元发育至关重要。此外，研究表明原发性纤毛是Wnt信号从规范到非规范转换所必需的，并且原发性纤毛形成或信号传导缺陷导致膀胱发生。各种组织在形态发生过程中使用非规范Wnt （PCP：“平面细胞极性”）途径来促进包括细胞极化和细胞骨架调节在内的过程。非规范Wnt信号的缺失导致PCP，是许多发育或后期缺陷的基础，如多囊肾病和肾病。利用非洲爪蟾（Xenopus laevis）胚胎，在某些情况下补充斑马鱼（Danio rerio）胚胎，本研究首次评估了非规范Wnt PCP成分在肾小管形态发生中的作用。我们的假设是PCP成分Daam1、WGEF、Prickle和Strabismus是初级纤毛形成所必需的，而初级纤毛又是肾脏形态发生所必需的。爪蟾具有多种实验优势，包括易于引入外源性构建体来阻断或激活信号通路、快速发育和易于观察外胚层下形成的肾脏。其次，使用转基因方法，我们将在活体动物中解决PCP/非规范Wnt信号在形成和移动正在经历/促成肾小管形态发生的细胞中的作用。最后，将进行过表达筛选，以发现小管形成的新调节因子。总的来说，这项工作在评估PCP成分在肾脏发育中的作用方面是新颖的；利用转基因方法在非洲爪蟾活体胚胎中观察和/或靶向肾脏发育；并进行无偏见的过表达筛选，以揭示参与肾小管形成的额外和可能的新成分。总之，我们将加强我们对肾脏形态发生的理解，这可能与获得对人类后期病理的见解有关。

DESCRIPTION (provided by applicant): Formation of renal tubules in both mammals and amphibians requires Wnt pathways. In kidney, aberrant Wnt signaling has been linked to developmental pathologies such as Wilms tumor and cystic diseases, as well as with renal cell carcinoma. Recent studies from our group and others indicate that canonical (?-catenin- mediated) Wnt signaling is essential for induction of nephron development. Additionally, studies suggest that primary cilia are required for a switch from canonical to non-canonical Wnt signaling, and that defects in primary cilia formation or signaling lead to cystogenesis. Varied tissues undergoing morphogenesis employ non-canonical Wnt (PCP: "planar cell polarity") pathways to promote processes including cell polarization and cytoskeletal modulation. Deficiencies in non-canonical Wnt signaling, which contributes to PCP, underlie a number of developmental or later defects, such as polycystic kidney disease and nephronophthisis. Using Xenopus laevis (frog) embryos, supplemented in some contexts with embryos of Danio rerio (zebrafish), this proposal first assesses the roles of non-canonical Wnt PCP components in kidney tubule morphogenesis. Our hypothesis is that the PCP components Daam1, WGEF, Prickle and Strabismus are required for primary cilia formation, which is in turn required for nephric morphogenesis. Xenopus offers experimental advantages including the facile introduction of exogenous constructs to block or activate signaling pathways, rapid development and easy visualization of the forming kidney under the surface ectoderm. Second, using transgenic approaches, we will address in living animals the role of PCP/ non-canonical Wnt signals in shaping and moving cells that are undergoing/ contributing to kidney tubule morphogenesis. Finally, an over-expression screen will be performed to discover new regulators of tubule formation. Overall, this work is novel in assessing the roles of the PCP components in kidney development; in utilizing transgenic approaches in Xenopus laevis to visualize and/ or target kidney development in living embryos; and in performing an unbiased over- expression screen to reveal additional and likely novel components involved in kidney tubulogenesis. In sum, we will enhance our understanding of kidney morphogenesis, which is likely to be relevant to obtaining insights on later pathologies that arise in humans.