Required role of focal adhesion kinase (FAK) for integrin-stimulated cell migration.
FAK localizes to sites of transmembrane integrin receptor clustering and facilitates intracellular signaling events. FAK-null (FAK-) fibroblasts exhibit a rounded morphology, defects in cell migration, and an elevated number of cell-substratum contact sites. Here we show that stable re-expression of epitope-tagged FAK reversed the morphological defects of the FAK- cells through the dynamic regulation of actin structures and focal contact sites in fibronectin (FN) stimulated cells. FAK re-expressing fibroblasts (clones DA2 and DP3) exhibit a characteristic fibrillar shape and display indistinguishable FN receptor-stimulated migration properties compared to normal fibroblasts. Expression of various FAK mutants in the FAK- cells showed that FAK kinase activity, the Tyr-397/SH2 domain binding site, and the first proline-rich SH3 binding region in the FAK C-terminal domain were individually needed to promote full FAK-mediated FAK- cell migration to FN whereas direct paxillin binding to FAK was not required. Expression of the FAK Phe-397 mutant did not promote FAK- cell migration and overexpression of p50(csk) in DA2 cells inhibited migration to FN suggesting that Src-family PTKs play important roles in FAK-mediated motility events. Expression of the FAK C-terminal domain, FRNK, promoted FAK dephosphorylation at Tyr-397 and potently blocked FAK-mediated cell migration. This dominant-negative effect of FRNK was reversed by a point mutation (Leu-1034 to Ser) which prevented FRNK localization to focal contact sites. Our results show that FAK functions as a key regulator of fibronectin receptor stimulated cell migration events through the recruitment of both SH2 and SH3 domain-containing signaling proteins to sites of integrin receptor clustering.
The Scripps Research Institute, Department of Immunology, IMM26, La Jolla, CA 92037, USA.
D J
DJ
Sieg
C R
CR
Hauck
D D
DD
Schlaepfer
D000199:Actins / Q000032:analysis / Q000378:metabolism; D000818:Animals; D015815:Cell Adhesion Molecules / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003598:Cytoskeletal Proteins / Q000032:analysis; D000939:Epitopes / Q000235:genetics; D005347:Fibroblasts / Q000737:chemistry / Q000166:cytology / Q000201:enzymology; D005353:Fibronectins / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D015971:Gene Expression Regulation, Enzymologic; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed / Q000502:physiology; D051419:Paxillin; D010641:Phenotype; D010750:Phosphoproteins / Q000032:analysis; D010766:Phosphorylation; D011392:Proline / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D011505:Protein-Tyrosine Kinases / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D016608:Talin / Q000032:analysis; D014162:Transfection; D016596:Vinculin / Q000032:analysis; D018909:src Homology Domains / Q000502:physiology
D000199:Actins; D015815:Cell Adhesion Molecules; D003598:Cytoskeletal Proteins; D000939:Epitopes; D005353:Fibronectins; D016023:Integrins; D051419:Paxillin; D010750:Phosphoproteins; C496062:Pxn protein, mouse; D016608:Talin; D016596:Vinculin; D011392:Proline; C113183:FAK-related nonkinase; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse