Han D C, Shen T L, Guan J L
Cancer Biology Laboratories, Department of Molecular Medicine, Cornell University, Ithaca, New York 14853, USA.
J Biol Chem. 2000 Sep 15;275(37):28911-7. doi: 10.1074/jbc.M001997200.
We have previously described Grb7 association with focal adhesion kinase (FAK) and its possible roles in cell migration. In this paper, we investigated the mechanisms by which Grb7 and its association with FAK regulate cell migration. We found that deletion of the Grb7 SH2 domain eliminated partial Grb7 localization to focal contacts and its ability to stimulate cell migration. Replacement of the SH2 domain with the focal adhesion targeting sequence from FAK resulted in the focal contacts localization of the chimeric molecule and restored its activity to stimulate cell migration. We also found that Grb7 could be phosphorylated by FAK, which was dependent on the FAK kinase activity but not the presence of the Src family kinases. Cell adhesion also enhanced Grb7 phosphorylation in FAK+/+ cells but not FAK-/- cells, suggesting that Grb7 is a physiological substrate of FAK. Furthermore, both Grb7 and the chimeric molecule did not increase migration of FAK-/- cells, although the chimeric molecule was targeted to the focal contacts. Last, we showed that other Grb7 family members could not stimulate cell migration under similar experimental conditions. Together, these results demonstrate a role for Grb7 targeting to focal contacts and its phosphorylation by FAK in the regulation of cell migration.
我们之前已经描述过Grb7与粘着斑激酶（FAK）的关联及其在细胞迁移中的可能作用。在本文中，我们研究了Grb7及其与FAK的关联调节细胞迁移的机制。我们发现，Grb7的SH2结构域缺失消除了Grb7部分定位于粘着斑的现象及其刺激细胞迁移的能力。用来自FAK的粘着斑靶向序列替换SH2结构域导致嵌合分子定位于粘着斑，并恢复了其刺激细胞迁移的活性。我们还发现，Grb7可被FAK磷酸化，这依赖于FAK激酶活性而非Src家族激酶的存在。细胞粘附也增强了FAK+/+细胞而非FAK-/-细胞中Grb7的磷酸化，表明Grb7是FAK的生理底物。此外，尽管嵌合分子定位于粘着斑，但Grb7和嵌合分子均未增加FAK-/-细胞的迁移。最后，我们表明在类似实验条件下，其他Grb7家族成员不能刺激细胞迁移。总之，这些结果证明了Grb7定位于粘着斑及其被FAK磷酸化在细胞迁移调节中的作用。
