Cadherin-p120 signaling in motility and invasiveness

描述（由申请人提供）：p120 catenin通过与经典钙粘蛋白高度保守的近膜结构域相互作用影响细胞-细胞粘附，并在细胞质和细胞核中具有额外的作用。最近的三份报告表明，细胞质p120可以调节RhoA、Rac和Cdc42的活性，导致细胞形态改变和运动增加。钙粘蛋白结合阻断了这些细胞质p120效应，提示了一种优雅的、以前意想不到的调节粘附和运动细胞表型之间平衡的机制。这些观察结果也为失去e -钙粘蛋白表达的癌细胞所显示的转移表型提供了潜在的解释。我们的长期目标是了解、预防或开发肿瘤转移的治疗方法。具体而言，在本项目中，我们寻求(1)阐明p120影响不同Rho gtpase的机制，(2)验证细胞质p120可以在体外和体内促进侵袭性的假设，以及(3)阐明激酶在p120功能中的作用。在Aim 1中，将使用p120的结构-功能分析和选择性解偶联突变体，并测试特异性蛋白质-蛋白质相互作用，以确定p120是否通过相同或不同的机制影响RhoA， Rac和Cdc42。在Aim 2中，我们将在体外测试不结合钙粘蛋白的p120是否促进细胞运动并诱导侵袭性。在将细胞注射到裸鼠体内后，还将测试影响培养细胞中p120定位或功能的治疗方法对侵袭性的影响。最后，在Aim3中，我们将测试p120-激酶结合在Rho gtpase活性、钙粘蛋白功能、细胞骨架动力学和细胞运动中的作用。通过探索p120连环蛋白在钙粘蛋白和Rho信号级联整合中的作用，我们希望确定p120是否作为细胞接触敏感开关，介导接触抑制运动，以及钙粘蛋白介导的侵袭性抑制。我们期望阐明p120的功能和物理相互作用域将允许未来一代靶向特定p120功能的化合物，作为新型癌症治疗的基础。我们认为，由于p120在正常细胞中与钙粘蛋白结合，因此选择性地靶向p120在钙粘蛋白不偶联状态下促进侵袭的功能，对于钙粘蛋白缺乏的恶性细胞将是唯一有效的。

DESCRIPTION (provided by applicant): p120 catenin affects cell-cell adhesion by interacting with the highly conserved juxtamembrane domain of classical cadherins, and has additional roles in both the cytoplasm and the nucleus. Three recent reports indicate that cytoplasmic p120 can modulate the activities of RhoA, Rac, and Cdc42, leading to altered cell morphology and increased motility. Cadherin binding blocks these cytoplasmic p120 effects, suggesting an elegant and previously unexpected mechanism for regulating the balance between adhesive and motile cellular phenotypes. These observations also provide a potential explanation for the metastatic phenotype shown by cancer cells that have lost E-cadherin expression. Our long-term goal is to understand, and prevent or develop treatments for, tumor metastasis. Specifically, in this project, we seek to (1) elucidate the mechanism(s) by which p120 affects different Rho GTPases, (2) test the hypothesis that cytoplasmic p120 can promote invasiveness in vitro and in vivo, and (3) clarify the role of kinesin in p120 function. In Aim 1 structure-function analysis and selective uncoupled mutants of p120 will be used, and specific protein-protein interactions tested, to determine whether p120 affects RhoA, Rac and Cdc42 via the same or distinct mechanisms. In Aim 2, we will test in vitro whether cadherin-unbound p120 promotes cell motility and induces invasiveness. Treatments that affect p120 localization or function in cultured cells will also be tested for their effects on invasiveness, after injection of the cells into nude mice. Finally, in Aim3 we will test the role of the p120-kinesin association in the activity of Rho GTPases, cadherin function, cytoskeletal dynamics and cell motility. By exploring the role of p120 catenin in the integration of cadherin and Rho signaling cascades, we expect to determine whether p120 acts as a cell contact-sensitive switch, mediating contact inhibition of motility, and cadherin-mediated suppression of invasiveness. We expect that elucidating p120's functional and physical interaction domains will allow the future generation of compounds that target particular p120 functions, as the basis of novel cancer treatments. We believe that because p120 is bound to cadherins in normal cells, selectively targeting the p120 functions that promote invasiveness in the cadherin-uncoupled state would be uniquely effective in cadherin-deficient malignant cells.