Laminin-10/11 and Fibronectin Differentially Regulate Integrin- dependent Rho and Rac Activation via p130Cas-CrkII-DOCK180 Pathway

This research was originally published in the Journal of Biological Chemistry. Jianguo Gu, Yasuhiro Sumida, Noriko Sanzen and Kiyotoshi Sekiguchi. Laminin-10/11 and Fibronectin Differentially Regulate Integrin- dependent Rho and Rac Activation via p130Cas-CrkII-DOCK180 Pathway. J. Biol. Chem. 2001; 276: 27090–27097 © the American Society for Biochemistry and Molecular Biology
The α5 chain-containing laminin isoforms, laminins-10 and -11 (laminin-10/11), are the major components of the basement membrane, having potent cell-adhesive activity. We examined the cell-adhesive and integrin-mediated signaling activities of laminin-10/11 in comparison to fibronectin, the best characterized extracellular adhesive ligand. We found that laminin-10/11 are more active than fibronectin in promoting cell migration and preferentially activate Rac, not Rho, via the p130Cas-CrkII-DOCK180 pathway. Cells adhering to fibronectin develop stress fibers and focal contacts, whereas cells adhering to laminin-10/11 do not, consistent with the high cell migration-promoting activity of laminin-10/11. Pull-down assays of GTP-loaded Rac and Rho demonstrated the preferential activation of Rac on laminin-10/11, in contrast to the activation of Rho on fibronectin. Activation of Rac by laminin-10/11 was associated with the phosphorylation of p130Cas and an increased formation of a p130Cas-CrkII-DOCK180 complex. Cell migration on laminin-10/11 was suppressed by the expression of either a dominant-negative Rac or CrkII mutants defective in p130Casor DOCK180 binding. This is the first report demonstrating a distinct activation of Rho family GTPases resulting from adhesion to different extracellular ligands.