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。上皮细胞具有很高的更新和损伤修复能力，以维持这一屏障。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，允许细胞组装成极化的多细胞组织。然而，一旦形成，AJ就不是静态的。虽然对新生AJ的形成有很多了解，但在形成的上皮中AJ的维持和重塑通常是一个不太清楚的过程。Rho GTP酶是上皮粘附、细胞形状和极化的关键调节剂。Rho GTP酶响应细胞粘附而激活不同效应物的能力被认为是其功能多样性的原因，然而某些效应物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 GTdR家族成员和效应子使得它们在体内的功能的确定复杂化。相比之下，果蝇只有一个Rho和Cdc 42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 GTP酶在果蝇上皮重塑和形态发生中的作用。我们积累的结果表明，在重塑上皮Rho 1和Cdc 42相互影响的活性，以调节AJ重塑和细胞张力，而在增殖上皮Cdc 42极性复合物调节细胞凋亡诱导的代偿性增殖，通过调节Rho 1活性。我们现在将识别介导Rho 1和Cdc 42串扰的候选者，并确定它们如何做到这一点。我们将在果蝇或哺乳动物细胞系中使用果蝇遗传学和分子及细胞生物学方法。 除了表面钙粘蛋白，胞质蛋白被招募形成AJ。这些蛋白质将钙粘蛋白粘附与调节细胞骨架或细胞存活/增殖的活性偶联。含有接头或支架蛋白的LIM结构域的Ajuba家族就是这样的蛋白质。与Rho GTP酶一样，在过去3年中，由于重叠的组织表达和家族成员的功能冗余，我们在体内确定其在哺乳动物上皮形态发生中的作用的努力一直具有挑战性。果蝇只有一个基因，djub。我们已经表明，djub是一个必不可少的基因和一个新的调节上皮器官大小的组成部分的河马信号通路。我们现在将确定筋骨草LIM蛋白如何调节哺乳动物和果蝇中的Hippo信号通路，以影响上皮组织生长。

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.