Novel Role of Nephron Epithelialization in Nuclear Signaling

项目摘要/摘要： 核仁上皮化在核信号转导中的新作用 先天性肾脏和尿路畸形(CAKUT)是导致儿童终末期肾脏疾病的最常见原因，需要进行肾脏移植。它们发生在几乎2%的新生儿中，占所有出生缺陷的近四分之一。然而，只有14%的病例有已知的遗传原因。许多CAKUT病例是由肾脏正常功能所需的上皮小管组成的肾单位形成缺陷所致。先前的研究表明，无论是平面细胞极性(PCP)途径的破坏还是胞外囊泡复合体的破坏都会导致肾小管畸形，表明这些成分是正常肾小管形成所必需的。在我们以前的研究中，我们独立地评估了PCP和胞外包囊复合体是如何促进小管形成的。我们研究了不同的模型，Daam1是一种福尔曼蛋白，它组装肌动蛋白细丝作为Wnt/Plane细胞极性途径的一部分，Dnmbp/Tuba通过促进肾单位前体细胞之间细胞-细胞接触的产生促进小管形成。我们发现了一种新的机制，利用Wnt/PCP Forin蛋白Daam1驱动肾单位祖细胞之间的细胞连接形成，通过聚合肌动蛋白来稳定贴壁连接处的钙粘附素，从而产生小管。此外，我们的结果表明，胞囊相关成分Dnmbp促进了连接成分的靶向，从而启动了肾单位祖细胞之间这些细胞接触的形成。尽管取得了这些进展，但我们还不知道细胞-细胞接触的形成如何影响发育中的肾单位的小管上皮化和形态发生的发育过程。为了解决这一重大问题，我们将以我们的重要发现为基础，通过以下方式评估细胞连接形成如何影响肾小管的发育：1)确定DAAM1和DNMBP之间的相互作用如何调节肾单位祖细胞之间的细胞-细胞接触形成；2)确定DAAM1‘S在连接形成过程中是否调控β-catenin在肾脏发生过程中的连接与Wnt信号作用。总体而言，本申请中提出的实验将有助于对细胞如何相互作用和通信以执行与多个器官系统相关的管状发生的新理解。对参与肾脏发育的细胞生物学机制的定量评估是一个新的研究领域，它将有助于对肾小管形成过程中的上皮化和形态发生机制有价值的见解。

PROJECT SUMMARY/ABSTRACT: NOVEL ROLE OF NEPHRON EPITHELIALIZATION IN NUCLEAR SIGNALING Congenital anomalies of the kidney and urinary tract (CAKUT) are the most common cause of pediatric end- stage renal disease resulting in the need for kidney transplant. They occur in almost 2% of births, making up nearly one-fourth of all birth defects. However, only 14% of cases have a known genetic cause. Many CAKUT cases result from defects in the formation of nephrons, which are composed of epithelial tubules that are required for the proper function of the kidney. Prior studies indicate that disruption of either the planar cell polarity (PCP) pathway or exocyst vesicle complex result in malformation of the nephric tubules, indicating that these components are required for proper tubule formation. In our previous studies, we evaluated how tubulogenesis is facilitated through the PCP and exocyst complexes independently. We investigated distinct models by which Daam1, a formin protein that assembles actin filaments as part of the Wnt/planar cell polarity pathway, and Dnmbp/Tuba, which regulates exocytic vesicle targeting, facilitate tubulogenesis by promoting the generation of cell-cell contacts between nephron progenitor cells. We discovered a novel mechanism that utilizes the Wnt/PCP formin protein Daam1 to drive cell junction formation between nephron progenitor cells to generate tubules by polymerizing actin to stabilize cadherin at adherens junctions. Additionally, our results indicate that the exocyst-associated component Dnmbp facilitates the targeting of junctional components to initiate formation of these cell contacts between nephron progenitors. Despite this progress, we do not understand how the formation of cell-cell contacts influences the developmental processes of tubule epithelialization and morphogenesis in developing nephrons. To address this significant question, we will build upon on our important discoveries to evaluate how cell junction formation impacts the development of the nephric tubules by: 1) Identifying how the interaction between Daam1 and Dnmbp regulates cell-cell contact formation between nephron progenitors and 2) Determining whether Daam1’s role in junction formation regulates beta-catenin’s junctional versus Wnt signaling roles during nephrogenesis. Overall, the experiments proposed in this application will facilitate a new understanding of how cells interact and communicate to carry out tubulogenesis that has relevance in multiple organ systems. The quantitative evaluation of cell biological mechanisms involved in nephric development is a new area of study that will contribute valuable insights into epithelialization and morphogenesis mechanisms underlying tubulogenic processes.