title: FAK phosphorylation at Ser-843 inhibits Tyr-397 phosphorylation, cell spreading and migration.
abstract: Multiple stimuli promote the tyrosine phosphorylation and activation of focal adhesion kinase (FAK), which ultimately facilitates migration. Little is known about the effect of adhesion-dependent signals and cytoskeleton organization on the regulation of FAK phosphorylation at serine sites, or about the role of FAK serine phosphorylation in cell migration. Here, we show that FAK phosphorylation at Ser-843 is strikingly increased when adherent cells are removed from the substratum and held in suspension or by treatment of adherent cells with cytochalasin D, conditions that disrupt the F-actin cytoskeleton and promote focal adhesion disassembly. Notably, the increase in Ser-843 phosphorylation was accompanied by a concomitant sharp decrease in Tyr-397 phosphorylation. To further examine the cause-effect relationship between these two phosphorylation sites we generated Ser-843 phosphorylation-deficient and phosphorylation-mimicking FAK mutants. We found that mutation of Ser-843 to aspartic acid (FAK[S843D]) markedly decreased FAK Tyr-397 phosphorylation in integrin-stimulated cells. While the migratory defect of FAK-deficient fibroblasts was rescued by stable re-expression of WT FAK or FAK[S843A], stable re-expression of FAK[S843D] failed to restore the ability of the cells to migrate into the denuded area of a wound. Our results indicate that increased FAK phosphorylation at Ser-843 represses FAK phosphorylation at Tyr-397, thus suggesting a mechanism of cross-talk between these phosphorylation sites that could regulate FAK-mediated cell shape and migration.
authors.affiliation: 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 90095, USA.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Jacamo
authors.forename: Xiaohua
authors.initials: X
authors.lastname: Jiang
authors.forename: J Adrian
authors.initials: JA
authors.lastname: Lunn
authors.forename: Enrique
authors.initials: E
authors.lastname: Rozengurt
mesh_terms: D000595:Amino Acid Sequence / Q000502:physiology; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D048430:Cell Shape / Q000187:drug effects / Q000502:physiology; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051379:Mice; D018345:Mice, Knockout; D009154:Mutation / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D051381:Rats; D012694:Serine / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D015638:Cytochalasin D; D014443:Tyrosine; D012694:Serine; D051416:Focal Adhesion Protein-Tyrosine Kinases