The Role of Planar Cell Polarity Signals in Shaping Kidney Tubules

描述(申请人提供)：哺乳动物和两栖动物的肾小管的形成都需要Wnt通路。在肾脏中，Wnt信号的异常与发育病理如肾母细胞瘤和囊性疾病以及肾细胞癌有关。我们小组和其他人最近的研究表明，规范的(-连环素介导的)Wnt信号对于诱导肾单位发育是必不可少的。此外，研究表明，初级纤毛是从规范的Wnt信号向非规范的Wnt信号转换所必需的，初级纤毛形成或信号的缺陷会导致囊变。许多经历形态发生的组织使用非规范的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。导致PCP的非典型Wnt信号的缺陷是许多发育或后来的缺陷的基础，如多囊肾病和肾单位病。利用非洲爪哇(Frog)胚胎，在某些情况下补充斑马鱼(Danio Rerio)的胚胎，这项建议首先评估了非规范的Wnt PCP组分在肾小管形态发生中的作用。我们的假设是，初级纤毛的形成需要PCP组分Daam1、Wgef、棘突和斜视，而初级纤毛的形成又需要肾脏的形态发生。非洲爪哇提供了实验上的优势，包括容易地引入外源结构来阻断或激活信号通路，快速发展和易于观察到表面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研究PCP/非规范Wnt信号在正在经历/促进肾小管形态形成的细胞的形成和移动中的作用。最后，将进行过度表达筛查，以发现小管形成的新调节因子。总体而言，这项工作在以下方面是新颖的：评估PCP组分在肾脏发育中的作用；利用非洲爪哇的转基因方法可视化和/或靶向活胚胎中的肾脏发育；以及进行无偏见的过度表达筛选，以揭示参与肾小管形成的其他和可能的新成分。总而言之，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来出现的病理的洞察相关。

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.