Zhang Hongquan, Li Zhilun, Viklund Eva-Karin, Strömblad Staffan
Karolinska Institutet, Department of Microbiology, Pathology, and Immunology, SE-141 86 Huddinge, Sweden.
J Cell Biol. 2002 Sep 30;158(7):1287-97. doi: 10.1083/jcb.200207008.
p21-activated kinase 1 (PAK1) can affect cell migration (Price et al., 1998; del Pozo et al., 2000) and modulate myosin light chain kinase and LIM kinase, which are components of the cellular motility machinery (Edwards, D.C., L.C. Sanders, G.M. Bokoch, and G.N. Gill. 1999. Nature Cell Biol. 1:253-259; Sanders, L.C., F. Matsumura, G.M. Bokoch, and P. de Lanerolle. 1999. SCIENCE: 283:2083-2085). We here present a novel cell motility pathway by demonstrating that PAK4 directly interacts with an integrin intracellular domain and regulates carcinoma cell motility in an integrin-specific manner. Yeast two-hybrid screening identified PAK4 binding to the cytoplasmic domain of the integrin beta 5 subunit, an association that was also found in mammalian cells between endogenous PAK4 and integrin alpha v beta 5. Furthermore, we mapped the PAK4 binding to the membrane-proximal region of integrin beta 5, and identified an integrin-binding domain at aa 505-530 in the COOH terminus of PAK4. Importantly, engagement of integrin alpha v beta 5 by cell attachment to vitronectin led to a redistribution of PAK4 from the cytosol to dynamic lamellipodial structures where PAK4 colocalized with integrin alpha v beta 5. Functionally, PAK4 induced integrin alpha v beta 5-mediated, but not beta1-mediated, human breast carcinoma cell migration, while no changes in integrin cell surface expression levels were observed. In conclusion, our results demonstrate that PAK4 interacts with integrin alpha v beta 5 and selectively promotes integrin alpha v beta 5-mediated cell migration.
p21激活激酶1（PAK1）可影响细胞迁移（普赖斯等人，1998年；德尔波佐等人，2000年），并调节肌球蛋白轻链激酶和LIM激酶，它们是细胞运动机制的组成部分（爱德华兹，D.C.，L.C.桑德斯，G.M.博科奇，和G.N.吉尔。1999年。《自然细胞生物学》1:253 - 259；桑德斯，L.C.，F.松村，G.M.博科奇，和P.德兰尼罗勒。1999年。《科学》：283:2083 - 2085）。我们在此展示了一条新的细胞运动途径，即证明PAK4直接与整合素细胞内结构域相互作用，并以整合素特异性方式调节癌细胞迁移。酵母双杂交筛选鉴定出PAK4与整合素β5亚基的细胞质结构域结合，这种关联在内源性PAK4与整合素αvβ5之间的哺乳动物细胞中也被发现。此外，我们确定了PAK4与整合素β5膜近端区域的结合，并在PAK4的COOH末端的第505 - 530位氨基酸处鉴定出一个整合素结合结构域。重要的是，细胞附着于玻连蛋白导致整合素αvβ5的结合，从而使PAK4从细胞质重新分布到动态的片状伪足结构，在那里PAK4与整合素αvβ5共定位。在功能上，PAK4诱导整合素αvβ5介导而非β1介导的人乳腺癌细胞迁移，同时未观察到整合素细胞表面表达水平的变化。总之，我们的结果表明PAK4与整合素αvβ5相互作用，并选择性地促进整合素αvβ5介导的细胞迁移。
