PDGF and FGF induce focal adhesion kinase (FAK) phosphorylation at Ser-910: dissociation from Tyr-397 phosphorylation and requirement for ERK activation.
A rapid increase in the tyrosine phosphorylation of focal adhesion kinase (FAK) has been extensively documented in cells stimulated by multiple signaling molecules, but very little is known about the regulation of FAK phosphorylation at serine residues. Stimulation of Swiss 3T3 cells with platelet-derived growth factor (PDGF) promoted a striking increase in the phosphorylation of FAK at Ser-910, as revealed by site-specific antibodies that recognized the phosphorylated state of this residue. FAK phosphorylation at Ser-910 could be distinguished from that at Tyr-397 in terms of dose-response relationships and kinetics. Furthermore, the selective phosphoinositide 3-kinase (PI 3-kinase) inhibitors wortmannin and LY 294002 abrogated FAK phosphorylation at Tyr-397 but did not interfere with PDGF-induced FAK phosphorylation at Ser-910. Conversely, treatment with U0126, a potent inhibitor of MEK-mediated ERK activation, prevented FAK phosphorylation at Ser-910 induced by PDGF but did not interfere with PDGF-induced FAK phosphorylation at Tyr-397. These results were extended using growth factors that either stimulate, fibroblast growth factor (FGF), or do not stimulate (insulin) the ERK pathway activation in Swiss 3T3 cells. FGF but not insulin promoted a striking ERK-dependent phosphorylation of FAK at Ser-910. Our results indicate that FAK phosphorylation at Tyr-397 and FAK phosphorylation at Ser-910 are induced in response to PDGF stimulation through different signaling pathways, namely PI 3-kinase and ERK, respectively.
Hunger-Glaser
Isabel
I
Division of Digestive Diseases, Department of Medicine, David Geffen School of Medicine, CURE: Digestive Diseases Research Center and Molecular Biology Institute, University of California, Los Angeles, California, USA.
Fan
Robert S
RS
Perez-Salazar
Eduardo
E
Rozengurt
Enrique
E
D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007700:Kinetics; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000378:metabolism*; D012694:Serine / Q000378:metabolism*; D041701:Swiss 3T3 Cells; D014443:Tyrosine / Q000378:metabolism*; D000077191:Wortmannin
D000730:Androstadienes; D002070:Butadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D009570:Nitriles; D010982:Platelet-Derived Growth Factor; C113580:U 0126; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D014443:Tyrosine; D012694:Serine; D005346:Fibroblast Growth Factors; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse; D020928:Mitogen-Activated Protein Kinases; D000077191:Wortmannin