The cellular and molecular mechanisms regulating renal proximal tubule morphogenesis

项目总结(见说明)： 先天性肾脏和尿路异常(CAKUT)是5岁以下儿童终末期肾脏疾病的主要原因，大约每500名新生儿中就有1人发生。在与CAKUT相关的几个基因突变中，有Notch信号通路基因Jagge-1和Notch2的突变。Notch途径基因突变预计会降低Notch信号活性水平，与Alagille综合征(ALGS)有关，Alagille综合征的一个组成部分是形成小的多囊、发育不良的肾脏。最近，Hajdu-Cheney综合征，也涉及肾囊肿，与Notch2基因突变有关。尽管Notch通路突变与包括较小肾脏和肾囊肿在内的人类儿科综合征相关，但Notch信号调节肾单位形成的潜在细胞和分子机制才刚刚开始了解。该项目的目的是提高我们对调控肾近端小管形态发生的细胞和分子机制的了解，从而有助于更好地选择治疗方案和更好地管理CAKUT患者。我们建议利用Notch信号通路作为分子手柄来确定调控肾近端小管形态发生的细胞和分子机制。我们最近发现，在小鼠肾脏发育过程中降低Notch信号的水平会导致小的多囊、发育不良的肾脏，证明Notch信号在肾小管形态发生中起关键作用。在目标1中，我们将使用Notch信号缺陷的小鼠肾脏和三个Notch信号失活的肾细胞系来鉴定Notch信号在肾小管形态发生过程中调节肾上皮细胞分裂的细胞过程和基因。此外，在AIM2中，我们将确定Notch信号在调节肾近端小管形态发生中相互作用的蛋白质和途径。这将涉及验证这样一种假设，即部分使Notch信号失活的Notch途径基因突变将改变PKD2+/-小鼠的肾脏疾病。它还将涉及对与Notch2细胞内结构域相互作用的蛋白质的无偏见筛选。这些研究将提高我们对调控肾近端小管形态发生的细胞和分子机制的理解，以及一般情况下上皮细胞在分裂时保持单层的机制。

PROJECT SUMMARY (See instructions): Congenital abnormalities of the kidney and urinary tract (CAKUT) are the leading cause of end stage renal disease among children under 5 years, with an occurrence of approximately 1 in 500 newborns. Among the several genetic mutations that have been linked to CAKUT are mutations in Notch signaling pathway genes, Jagged-1 and Notch2. Mutations in Notch pathway genes, predicted to reduce the level of Notch signaling activity, are associated with Alagille Syndrome (ALGS), one component of which is the formation of small multi-cystic, dysplastic kidneys. Recently, the Hajdu-Cheney syndrome, also involving renal cysts, is associated with mutations in Notch2. Although the Notch pathway mutations are correlated with human pediatric syndromes including smaller kidneys and renal cysts, the underlying cellular and molecular mechanisms by which Notch signaling regulates nephron formation are only beginning to be understood. The objective of this project is to improve our understanding of the cellular and molecular mechanisms regulating renal proximal tubule morphogenesis and hence to contribute to better treatment options and better management of patients suffering from CAKUT. We propose to utilize the Notch signaling pathway as a molecular handle to identify the cellular and molecular mechanisms regulating renal proximal tubule morphogenesis. We have recently identified that reducing the level of Notch signaling during kidney development in mice results in small multi-cystic, dysplastic kidneys, proving that Notch signaling plays a critical role in renal tubule morphogenesis. In aim 1 we will use the mice with Notch signaling deficient kidneys, and three renal cell lines with Notch signaling inactivation to identify the cellular processes and genes by which Notch signaling regulates renal epithelial cell division during tubule morphogenesis. Additionally, in aim2 we will identify proteins and pathways that Notch signaling interacts with in regulating renal proximal tubule morphogenesis. This will involve testing the hypothesis that mutations in the Notch pathway genes that partially inactivate Notch signaling will modify the kidney disease in Pkd2 +/- mice. It will also involve an unbiased screen for proteins that interact with the intracellular domain of Notch2. These studies will improve our understanding of the cellular and molecular mechanisms regulating renal proximal tubule morphogenesis and in general the mechanisms by which epithelia are retained as a monolayer while they divide.