EPITHELIAL MORPHOGENESIS IN DEVELOPMENT AND DISEASE

描述（由申请人提供）：上皮细胞由极化的细胞片组成，其主要功能是建立保护身体免受环境影响的屏障。上皮细胞有很高的更新和损伤修复能力来维持这一屏障。不幸的是，上皮细胞也是与癌症有关的最常见的细胞类型。基于钙粘蛋白的粘附连接（AJ）介导初始上皮细胞-细胞粘附，使细胞组装成极化的多细胞组织。然而，AJ一旦形成就不是静态的。虽然我们对新生AJ的形成了解很多，但AJ在形成的上皮中的维持和重塑通常是一个不太清楚的过程。Rho gtpase是上皮粘附、细胞形状和极化的关键调节因子。Rho GTPases在响应细胞粘附时激活不同效应器的能力被认为是其功能多样性的原因，然而某些效应器是否可以被分配到特定的角色以及这些角色是什么，特别是在体内，是不确定的。在哺乳动物中存在多个Rho GTPase家族成员和效应物，使其在体内功能的测定变得复杂。相比之下，果蝇只有一个Rho和Cdc42成员，大多数效应蛋白有一个或几个成员，允许更直接的分析。在过去的3年里，我们一直在研究Rho gtpase在果蝇上皮重塑和形态发生中的作用。我们的累积结果表明，在重塑上皮中，Rho1和Cdc42相互影响活性以调节AJ重塑和细胞张力，而在增殖上皮中，Cdc42极性复合物通过调节Rho1活性来调节凋亡诱导的代偿性增殖。我们现在将确定介导Rho1和Cdc42串扰的候选物质，并确定它们是如何起作用的。我们将在果蝇或哺乳动物细胞系中同时使用果蝇遗传学和分子和细胞生物学方法。除了表面钙粘蛋白外，胞质蛋白也被招募来形成AJ。这些蛋白将钙粘蛋白粘附到调节细胞骨架或细胞存活/增殖的活性上。含有适配器或支架蛋白的LIM结构域的Ajuba家族就是这样的蛋白质。与Rho GTPases一样，在过去的3年里，由于组织表达的重叠和家族成员的功能冗余，我们在确定其在哺乳动物体内上皮形态发生中的作用方面的努力一直具有挑战性。果蝇只有一个基因，djub。我们已经证明，djub作为Hippo信号通路的一个组成部分，是一个重要的基因和一个新的上皮器官大小调节因子。我们现在将确定Ajuba LIM蛋白如何调节哺乳动物和果蝇的Hippo信号通路，从而影响上皮组织的生长。

DESCRIPTION (provided by applicant): Epithelia are composed of polarized sheets of cells whose main function is to establish a barrier that protects the body from its environment. Epithelia have a high capacity for renewal and injury repair to maintain this barrier. Unfortunately, epithelial cells are also the most common cell type implicated in cancer. Cadherin-based adherens junctions (AJ) mediate initial epithelial cell-cell adhesion allowing cells to assemble into polarized multicellular tissues. Once formed AJ are not static, however. While much is known about nascent AJ formation the maintenance and remodeling of AJ in a formed epithelia is, in general, a less well-understood process. Rho GTPases are critical regulators of epithelial adhesion, cell shape, and polarization. The ability of Rho GTPases to activate different effectors, in response to cell adhesion, is believed to be responsible for their functional diversity, yet whether certain effectors can be assigned to specific roles and what those roles are, especially in vivo, are uncertain. The presence of multiple Rho GTPase family members and effectors in mammals complicates determination of their function in vivo. In contrast Drosophila have only one Rho and Cdc42 member and most effector proteins have one or few members, allowing for a more straightforward analysis. Over the past 3 years we have been studying the role of Rho GTPases in epithelial remodeling and morphogenesis in Drosophila. Our accumulated results indicate that in remodeling epithelia Rho1 and Cdc42 influence each other's activity to regulate AJ remodeling and cell tension, whereas in a proliferating epithelium the Cdc42 polarity complex regulates apoptosis induced compensatory proliferation by modulating Rho1 activity. We will now identify candidates mediating Rho1 and Cdc42 crosstalk and determine how they do so. We shall use both drosophila genetics and molecular and cellular biological approaches in drosophila or mammalian cell lines. In addition to surface cadherins, cytosolic proteins are recruited to forming AJ. These proteins couple cadherin adhesion to activities that modulate the cytoskeleton or cell survival/proliferation. The Ajuba family of LIM domain containing adapter or scaffolding proteins are such proteins. As with Rho GTPases, our efforts, over the past 3 years, determining their role in mammalian epithelial morphogenesis, in vivo, has been challenging due to overlapping tissue expression and functional redundancy of family members. Drosophila has a single gene, djub. We have shown that djub is an essential gene and a novel regulator of epithelial organ size as a component of the Hippo signaling pathway. We will now determine how Ajuba LIM proteins regulate the Hippo signaling pathway in mammals and drosophila, to influence epithelial tissue growth.