Role of Rap1 in cadherin and integrin mediated cross-talk in oral keratinocytes

描述(由申请人提供)：上皮细胞黏附和迁移的破坏是胚胎发育、伤口愈合、癌症发展和进展等生理和病理过程的基础。钙粘附素和整合素是黏附和迁移的中心蛋白受体。虽然钙粘附素和整合素之间似乎存在着重要的关系，但它们之间的分子串扰尚未得到很好的描述，但一个有前途的研究领域是ras样蛋白Rap1及其信号级联。最近对小鼠甲状腺和人类乳腺细胞的研究支持Rap1在钙粘附素和整合素之间的相互作用。特别是内吞的钙粘附素刺激Rap1，而Rap1启动整合素受体。后者与纤维连接蛋白等配体结合，触发RAD介导的信号事件，促进细胞迁移。这些研究表明，Rap1通过一种由内向外的信号机制在连接细胞黏附和迁移中发挥关键作用；然而，这一点在角质形成细胞中尚未被研究。与这一作用一致，我们在角质形成细胞中的初步研究表明，活性的RAP1促进了与纤维连接蛋白的黏附，这可能是增加迁移的一个机制。E-钙粘素刺激的Rap1也可能通过p-连环蛋白的核转运诱导细胞迁移，当E-cad内吞时，p-连环蛋白被释放。这一应用的中心假设是，细胞黏附的破坏刺激了RAP1，RAP1通过激活整合素受体和p-CAT的核运输来促进口腔角质形成细胞的细胞迁移。本研究的目的是确定1)细胞间黏附的破坏和E-cad的内吞是否刺激RAP1；2)激活的RAP1在向内向外信号转导A5p1中的作用；3)E-cad刺激的RAP1通过A5p1整合素和p-CAT在细胞迁移中的作用。拟议的研究将确定新的信号机制，通过这些机制，Rap1整合口腔角质形成细胞中的细胞黏附和迁移信号网络。这些发现将有助于设计合理的策略来治疗口腔黏膜的慢性伤口或肿瘤。

DESCRIPTION (provided by applicant): Disruptions in epithelial cell adhesion and migration are fundamental to physiologic and pathologic processes such as embryonic development, wound healing, development and progression of cancer. Cadherins and integrins are the central protein receptors in adhesion and migration. Although there appears to be an important relationship between cadherins and integrins their molecular cross-talk is not well characterized, but a promising area of research is the ras-like protein rap1 and its signaling cascade. Recent studies in mouse thyroid and human breast cells support a role for rap1 in the cross-talk between cadherins and integrins. Specifically endocytosed cadherin stimulates rap1, which primes integrin receptors. The latter bind ligands, such as fibronectin, which trigger rad-mediated signaling events to facilitate cell migration. These studies suggest that rap1 plays a critical role in linking cell adhesion and migration via an inside-out signaling mechanism; however, this has not been investigated in keratinocytes. Consistent with this role, our preliminary studies in keratinocytes suggest that active rap1 facilitates adhesion to fibronectin, a possible mechanism for increased migration. E-cadherin-stimulated rap1 may also induce cell migration via nuclear transport of p-catenin, which is released when E-cad is endocytosed. The central hypothesis of this application is that disruption of cell adhesion stimulates rap1, which enhances cell migration of oral keratinocytes via activation of integrin receptors and via nuclear transport of p-cat. The goals of the proposed study are to determine 1) whether disruption of cell-cell adhesion and endocytosis of E-cad stimulate rap1; 2) the role of active rap1 in inside-out signaling to a5p1; 3) the role of E-cad stimulated rap1 in cell migration via a5p1 integrin and p-cat. The proposed studies will identify novel signaling mechanisms through which rap1 integrates cell adhesion, and migration signaling networks in oral keratinocytes. These findings will facilitate the design of rational strategies to treat chronic wounds or tumors of the oral mucosa.