Ras signaling and tubulogenesis in the C. elegans excretory (renal) system

描述（由申请人提供）：试管是大多数人体器官的构建模块。 输卵管发育缺陷会导致严重的出生缺陷，而输卵管维护缺陷会导致许多常见的健康问题，如肾脏疾病，心脏病和中风。 因此，重要的是要了解管道最初是如何形成和维持的。单细胞管是一类特殊的非常微小的管，直径只有一个细胞。 哺乳动物的毛细血管床中有许多这样的管道，与大脑和肾脏等器官连接。单细胞管似乎也是脉管系统中更大口径管的前体。尽管如此，关于单细胞管如何在体内发育或它们在多大程度上依赖于与更复杂的多细胞管相同的极性途径，人们知之甚少。 我们将在C. elegans排泄系统，一个简单的肾样器官，仅由3个单细胞管细胞组成。我们已经确认了 EGF-Ras-ERK通路和多个其他基因对于该器官中的管发育或维持是重要的。 我们将利用这些和其他现有的突变体来深入了解两个主要问题。目的1）是什么建立了“顶端向内”的极性，并控制上皮连接形成单细胞管？我们将（a）使用实时成像来可视化WT和各种突变体中的小管发生，以询问细胞接触的模式有利于单细胞管发育~（B）系统地测试单细胞管发育中已知极性调节剂的需求~和（c）进行无偏遗传筛选以找到对单细胞管发育重要的更多基因。目的2）一旦形成，单细胞管连接和管腔是如何维持的，是什么触发了它们的解体？我们将（a）测试两种新发现的顶端定位跨膜蛋白在顶端结构域组织中的作用~（B）测试这些蛋白中的一种的下调是否涉及EMT样撤回~和（c）鉴定管维持所需的其他基因。我们的实验利用了该系统非常简单的解剖结构和强大的成像和遗传方法，在C。elegans来解决有关单细胞管的核心问题，这些问题也与所有管的生物学相关。

DESCRIPTION (provided by applicant): Tubes are the building blocks of most human organs. Defects in tube development cause serious birth defects, while defects in tube maintenance underlie many common health problems such as kidney disease, heart disease and stroke. It is therefore important to understand how tubes initially form and are maintained. Unicellular tubes are a special class of very tiny tubes, just one cell in diameter. Mammals have many such tubes in the capillary beds that interface with organs such as the brain and kidney. Unicellular tubes also appear to be precursors to larger bore tubes in the vasculature. Despite this, very little is known about how unicellular tubes develop in vivo or to what degree they rely on the same polarity pathways as more complex multicellular tubes. We will identify molecular requirements for unicellular tube development and maintenance in the C. elegans excretory system, a simple renal-like organ consisting of only 3 unicellular tube cells. We've identified the EGF-Ras-ERK pathway and multiple other genes as important for tube development or maintenance in this organ. We will use these and other existing mutants to gain insight into two main questions. Aim 1) What establishes "apical inward" polarity and controls where epithelial junctions form to create a unicellular tube? We will (a) use live imaging to visualize tubulogenesis in WT and various mutants to ask what patterns of cell contact favor unicellular tube development~ (b) Systematically test the requirements for known polarity regulators in unicellular tube development~ and (c) Conduct unbiased genetic screens to find more genes important for unicellular tube development. Aim 2) Once formed, how are unicellular tube junctions and lumen maintained, and what triggers their disassembly? We will (a) Test the roles of two newly discovered apically-localized transmembrane proteins in apical domain organization~ (b) Test if downregulation of one of these proteins is involved in EMT-like withdrawal~ and (c) Identify additional genes required for tube maintenance. Our experiments take advantage of the system's very simple anatomy and powerful imaging and genetic approaches possible in C. elegans to address central questions about unicellular tubes that are also relevant to the biology of all tubes.