Hungerford J E, Compton M T, Matter M L, Hoffstrom B G, Otey C A
Department of Cell Biology, School of Medicine, University of Virginia, Charlottesville 22908, USA.
J Cell Biol. 1996 Dec;135(5):1383-90. doi: 10.1083/jcb.135.5.1383.
The tyrosine kinase called pp125FAK is believed to play an important role in integrin-mediated signal transduction. pp125FAK is associated both functionally and spatially with integrins, which are the cell surface receptors for extracellular matrix components. Although the precise function of pp125FAK is not known, two possibilities have been proposed: pp125FAK may regulate the assembly of focal adhesions in spreading or migrating cells, or pp125FAK may participate in a signal transduction cascade to inform the nucleus that the cell is anchored. To test these models in living cells, a peptide representing the focal adhesion kinase (FAK)-binding site of the beta 1 tail was coupled to carrier protein and injected into cultured cells to competitively inhibit the binding of pp125FAK to endogenous integrin, thus inhibiting activation of pp125FAK on a cell-by-cell basis. In addition, an antibody directed against an epitope adjacent to the focal adhesion targeting sequence on pp125FAK was microinjected, as an alternative means of inhibiting pp125FAK activation. It was observed that when rounded cells were injected with either the integrin peptide or the anti-FAK antibody, the cells rapidly began to apoptose, within 4 h after injection. These results indicate that pp125FAK may play a critical role in suppressing apoptosis in fibroblasts.
名为pp125FAK的酪氨酸激酶被认为在整合素介导的信号转导中起重要作用。pp125FAK在功能和空间上都与整合素相关联，整合素是细胞外基质成分的细胞表面受体。尽管pp125FAK的确切功能尚不清楚，但已提出两种可能性：pp125FAK可能调节铺展或迁移细胞中粘着斑的组装，或者pp125FAK可能参与信号转导级联反应，向细胞核告知细胞已锚定。为了在活细胞中测试这些模型，将代表β1尾巴粘着斑激酶（FAK）结合位点的肽与载体蛋白偶联，并注入培养细胞中，以竞争性抑制pp125FAK与内源性整合素的结合，从而在逐个细胞的基础上抑制pp125FAK的激活。此外，还显微注射了一种针对pp125FAK上粘着斑靶向序列附近表位的抗体，作为抑制pp125FAK激活的另一种方法。观察到，当向圆形细胞注射整合素肽或抗FAK抗体时，细胞在注射后4小时内迅速开始凋亡。这些结果表明，pp125FAK可能在抑制成纤维细胞凋亡中起关键作用。
