Role of paxillin isoforms and their tyrosine phosphorylation in cell migration.

基于肌动蛋白的细胞骨架组织和局部黏附形成的时间和空间调节在细胞迁移中起着至关重要的作用。我们发现，在上皮-间充质细胞转分化和细胞迁移过程中，paxlin和pi3ocas的酪氨酸磷酸化是整合素激活的一个显著事件。酪氨酸磷酸化p130^&lt；Cas&gt；已被证明促进细胞迁移。我们发现，在几个不同的实验细胞系统中，巴西林CC的酪氨酸磷酸化作用可以减少触角蛋白趋化细胞的迁移和跨细胞侵袭活动，而p130^&lt；Cas和gt；的酪氨酸磷酸化作用与巴氏杆菌相反。每一个磷酸化缺失突变体都是每种表型的显性负值。此外，我们还发现过表达paxlin a降低了NMuMG细胞的细胞饱和密度，而过表达pi30^&lt；Cas&gt；这些效应似乎也依赖于酪氨酸磷酸化事件。生长阶段的细胞生长速度和形态没有明显改变，细胞也没有转化。加入表皮生长因子后，α高表达细胞的饱和密度增加，而p130；我们认为，Paxlin a和p130^&lt；Cas&gt的酪氨酸磷酸化可能通过不同的信号通路对整合素介导的几种细胞事件产生相反的影响。我们还发现，巴西林与几个ARFGAP结合。ARFGAP是细胞内膜运输的调节者。目前，我们从酪氨酸磷酸化及其与ARFGAP的相互作用等方面分析了巴西林在调节细胞迁移活性中的作用。

Temporal and spatial regulation of actin-based cytoskeletal organization and focal adhesion formation play an essential role in cell migration. We found that tyrosine phosphorylation of paxillin and pi3OCas was a prominent event upon integrin activation during epithelial-mesenchymal transdifferentiation and cell migration. Tyrosine phosphorylation of p130^<Cas> has been demonstrated to facilitate cell migration. We showed that tyrosine phosphorylation of paxillin cc acts to reduce haptotactic cell migration as well as transcellular invasive activities in several different experimental cell systems, whereas tyrosine phosphorylation of p130^<Cas> exerts opposing effects to those of paxillina. Each of the phosphorylation-null mutant acted as dominant-negatives for each phenotype. Moreover, we found that overexpression of paxillin a reduced the cell saturation density of NMuMG cells while overexpression of pi30^<Cas> increased it. These effects also seemed to be dependent on the tyrosine phosphorylation events. Cell growth rates and morphologies at growing phases were not significantly altered, nor were cells transformed. Addition of epidermal growth factor increased saturation density of the paxillin α-overexpressing cells, while no further increment was observed in p130^<Cas>-overexpressing cells. We propose that tyrosine phosphorylation of paxillin a and p130^<Cas> exert opposing effects on several integrin-mediated cellular events, possibly through different signaling pathways. We also found that paxillin binds to several ARFGAPs. ARFGAPs are regulators of intracellular membrane trafficking. We currently analysing role of paxillin from aspects of its tyrosine phosphorylation and its interaction with ARFGAPs, in regulation of cell migratory activity.