Sung Bong Hwan, Yeo Myoung Gu, Oh Hye Jin, Song Woo Keun
Center for Distributed Sensor Network (CDSN), Department of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 500-712, Korea.
Mol Cells. 2008 Feb 29;25(1):131-7.
Crk-associated substrate (CAS) is a focal adhesion protein that is involved in integrin signaling and cell migration. CAS deficiency reduces the migration and spreading of cells, both of which are processes mediated by Rac activation. We examined the functions of v-Crk, the oncogene product of the CT10 virus p47gag-crk, which affects cell migration and spreading, membrane ruffling, and Rac activation in CAS-deficient mouse embryonic fibroblasts (CAS-/- MEFs). CAS-/- MEFs showed less spreading than did CAS+/+ MEFs, but spreading was recovered in mutant cells that expressed v-Crk (CAS-/-v-Crk MEF). We observed that the reduction in spreading was linked to the formation of membrane ruffles, which were accompanied by Rac activation. In CAS-/- MEFs, Rac activity was significantly reduced, and Rac was not localized to the membrane. In contrast, Rac was active and localized to the membrane in CAS-/-v-Crk MEFs. Lamellipodia protrusion and ruffle retraction velocities were both reduced in CAS-/- MEFs, but not in CAS-/-v-Crk MEFs. We also found that microinjection of anti-gag antibodies inhibited the migration of CAS-/-v-Crk MEFs. These findings indicate that v-Crk controls cell migration and membrane dynamics by activating Rac in CAS-deficient MEFs.
Crk相关底物（CAS）是一种粘着斑蛋白，参与整合素信号传导和细胞迁移。CAS缺陷会降低细胞的迁移和铺展，这两个过程均由Rac激活介导。我们研究了CT10病毒p47gag-crk的癌基因产物v-Crk在缺乏CAS的小鼠胚胎成纤维细胞（CAS-/- MEF）中的功能，v-Crk会影响细胞迁移、铺展、膜皱襞形成以及Rac激活。与CAS+/+ MEF相比，CAS-/- MEF的铺展较少，但在表达v-Crk的突变细胞（CAS-/-v-Crk MEF）中铺展得以恢复。我们观察到铺展减少与膜皱襞形成有关，膜皱襞形成伴随着Rac激活。在CAS-/- MEF中，Rac活性显著降低，且Rac未定位到细胞膜。相反，在CAS-/-v-Crk MEF中，Rac具有活性且定位到细胞膜。CAS-/- MEF中片状伪足突出和皱襞回缩速度均降低，但在CAS-/-v-Crk MEF中未降低。我们还发现显微注射抗gag抗体可抑制CAS-/-v-Crk MEF的迁移。这些发现表明，v-Crk通过在缺乏CAS的MEF中激活Rac来控制细胞迁移和膜动力学。
