Inhibition of integrin-mediated cell adhesion but not directional cell migration requires catalytic activity of EphB3 receptor tyrosine kinase - Role of RHO family small GTPases
Inhibition of integrin-mediated cell adhesion but not directional cell migration requires catalytic activity of EphB3 receptor tyrosine kinase - Role of RHO family small GTPases
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DOI：
10.1074/jbc.m411383200
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发表时间：
2005-01-14
影响因子：
4.8
通讯作者：
Wang, BC
中科院分区：
文献类型：
--
作者：
Miao, H;Strebhardt, K;Wang, BC
遗传学研究表明，Eph受体酪氨酸激酶通过不完全理解的机制具有激酶依赖性和激酶非依赖性功能。我们在这里报告，肝配蛋白B1刺激内源性EphB激酶在LS 174 T结直肠上皮细胞抑制整合素介导的粘附和HGF/SF诱导的定向细胞迁移。使用野生型（WT）或激酶缺陷型（KD-EphB 3）稳定转染的293细胞，我们发现，抑制整合素介导的细胞粘附和诱导细胞变圆是激酶依赖性的。出乎意料的是，在两个独立的测定中，KD-和WT-EphB 3均显著抑制定向细胞迁移。在肝配蛋白-B1刺激后，Rac 1和Cdc 42的活性在被诱导迁移的WT-和KD-EphB 3-表达细胞中均降低。药理学证据表明，Rac 1/Cdc 42活性降低导致RhoA信号相对增加有助于抑制作用。此外，EphB 3介导的对细胞粘附而非迁移的抑制作用被整联蛋白激活抗体消除，表明细胞迁移的抑制不是因为整联蛋白功能的下调。这些结果揭示了在调节细胞粘附和迁移中对EphB 3催化活性的不同需求，并表明虽然EphB 3的催化活性是抑制整联蛋白介导的细胞粘附所需的，但WT-和KD-EphB 3受体共有的Rho GTP酶的不同信号传导途径介导定向细胞迁移的抑制。
Genetic studies have shown that Eph receptor tyrosine kinases have both kinase-dependent and kinase-independent functions through incompletely understood mechanisms. We report here that ephrin-B1 stimulation of endogenous EphB kinases in LS174T colorectal epithelial cells inhibited integrin-mediated adhesion and HGF/SF-induced directional cell migration. Using 293 cells stably transfected with wild type (WT)- or kinase-deficient (KD-EphB3), we found that inhibition of integrin-mediated cell adhesion and induction of cell rounding was kinase-dependent. Unexpectedly, in two independent assays, both KD- and WT-EphB3 significantly inhibited directional cell migration. Upon ephrin-B1 stimulation, the activities of Rac1 and Cdc42 were reduced in both WT- and KD- EphB3-expressing cells that were induced to migrate. Pharmacological evidence demonstrates that a relative increase in RhoA signaling as a result of decreased Rac1/ Cdc42 activities contributes to the inhibitory effects. Furthermore, EphB3-mediated inhibitory effect on cell adhesion but not migration was abolished by the integrin activating antibodies, suggesting that the inhibition of cell migration is not because of down-regulation of integrin function. These results uncover a differential requirement for EphB3 catalytic activity in the regulation of cell adhesion and migration, and suggest that while catalytic activity of EphB3 is required for inhibition of integrin-mediated cell adhesion, a distinct signaling pathway to Rho GTPases shared by WT- and KD- EphB3 receptor mediates inhibition of directional cell migration.