Vossmeyer D, Kaufmann C, Löster K, Lucka L, Horstkorte R, Reutter W, Danker K
Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Arnimallee 22, Berlin-Dahlem, D-14195, Germany.
Exp Cell Res. 2000 Apr 10;256(1):321-7. doi: 10.1006/excr.2000.4831.
Integrins are heterodimeric transmembrane proteins that mediate substrate adhesion and migration but also the bidirectional transfer of information across the plasma membrane via their cytoplasmic domains. We addressed the question of whether the very short cytoplasmic tail of the alpha1 integrin subunit of alpha1beta1 integrin is required for alpha1beta1-specific adhesion, spreading, and migration. For this purpose we transfected the alpha1 integrin subunit and two cytoplasmically truncated alpha1 subunits into Chinese hamster ovary (CHO) cells. Elimination of the entire cytoplasmic domain of the alpha1 subunit does not affect adhesion but leads to inhibition of spreading and stress fiber formation. The defect in spreading could not be rescued by lysophosphatidic acid, which has been reported to stimulate actin stress fiber formation via Rho. Additionally, deletion of the entire cytoplasmic domain of the alpha1 subunit abolishes migration toward alpha1beta1-specific substrates. Migration and stress fiber formation are similar in CHO-alpha1 cells and CHO cells carrying an alpha1 subunit still containing the conserved GFFKR motif. So, the GFFKR motif of the alpha1 subunit is essential and sufficient for these processes.
整合素是异二聚体跨膜蛋白，它们介导底物黏附与迁移，还能通过其胞质结构域在质膜上进行信息的双向传递。我们探讨了α1β1整合素的α1整合素亚基非常短的胞质尾对于α1β1特异性黏附、铺展和迁移是否必需。为此，我们将α1整合素亚基和两个胞质截短的α1亚基转染到中国仓鼠卵巢（CHO）细胞中。去除α1亚基的整个胞质结构域不影响黏附，但会导致铺展和应力纤维形成受到抑制。溶血磷脂酸无法挽救铺展缺陷，据报道溶血磷脂酸可通过Rho刺激肌动蛋白应力纤维形成。此外，删除α1亚基的整个胞质结构域会消除向α1β1特异性底物的迁移。在CHO-α1细胞和携带仍含有保守GFFKR基序的α1亚基的CHO细胞中，迁移和应力纤维形成相似。因此，α1亚基的GFFKR基序对于这些过程至关重要且足够。
