Wells Clark D, Fawcett James P, Traweger Andreas, Yamanaka Yojiro, Goudreault Marilyn, Elder Kelly, Kulkarni Sarang, Gish Gerald, Virag Cristina, Lim Caesar, Colwill Karen, Starostine Andrei, Metalnikov Pavel, Pawson Tony
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, ON M5G 1X5, Canada.
Cell. 2006 May 5;125(3):535-48. doi: 10.1016/j.cell.2006.02.045.
Using functional and proteomic screens of proteins that regulate the Cdc42 GTPase, we have identified a network of protein interactions that center around the Cdc42 RhoGAP Rich1 and organize apical polarity in MDCK epithelial cells. Rich1 binds the scaffolding protein angiomotin (Amot) and is thereby targeted to a protein complex at tight junctions (TJs) containing the PDZ-domain proteins Pals1, Patj, and Par-3. Regulation of Cdc42 by Rich1 is necessary for maintenance of TJs, and Rich1 is therefore an important mediator of this polarity complex. Furthermore, the coiled-coil domain of Amot, with which it binds Rich1, is necessary for localization to apical membranes and is required for Amot to relocalize Pals1 and Par-3 to internal puncta. We propose that Rich1 and Amot maintain TJ integrity by the coordinate regulation of Cdc42 and by linking specific components of the TJ to intracellular protein trafficking.
通过对调控Cdc42 GTP酶的蛋白质进行功能和蛋白质组学筛选，我们鉴定出了一个以Cdc42 RhoGAP Rich1为中心的蛋白质相互作用网络，该网络在MDCK上皮细胞中组织顶端极性。Rich1与支架蛋白血管动蛋白（Amot）结合，从而定位于包含PDZ结构域蛋白Pals1、Patj和Par-3的紧密连接（TJ）处的蛋白质复合物。Rich1对Cdc42的调控对于维持紧密连接是必需的，因此Rich1是这种极性复合物的重要介质。此外，Amot与Rich1结合的卷曲螺旋结构域对于定位于顶端膜是必需的，并且是Amot将Pals1和Par-3重新定位到内部点状结构所必需的。我们提出，Rich1和Amot通过对Cdc42的协同调控以及通过将紧密连接的特定成分与细胞内蛋白质运输相联系来维持紧密连接的完整性。
