title: Cortactin tyrosine phosphorylation promotes its deacetylation and inhibits cell spreading.
abstract: BACKGROUND
  Cortactin is a classical Src kinase substrate that participates in actin cytoskeletal dynamics by activating the Arp2/3 complex and interacting with other regulatory proteins, including FAK. Cortactin has various domains that may contribute to the assembly of different protein platforms to achieve process specificity. Though the protein is known to be regulated by post-translational modifications such as phosphorylation and acetylation, how tyrosine phosphorylation regulates cortactin activity is poorly understood. Since the basal level of tyrosine phosphorylation is low, this question must be studied using stimulated cell cultures, which are physiologically relevant but unreliable and difficult to work with. In fact, their unreliability may be the cause of some contradictory findings about the dynamics of tyrosine phosphorylation of cortactin in different processes.
  
  
  RESULTS
  In the present study, we try to overcome these problems by using a Functional Interaction Trap (FIT) system, which involves cotransfecting cells with a kinase (Src) and a target protein (cortactin), both of which are fused to complementary leucine-zipper domains. The FIT system allowed us to control precisely the tyrosine phosphorylation of cortactin and explore its relationship with cortactin acetylation.
  
  
  CONCLUSIONS
  Using this system, we provide definitive evidence that a competition exists between acetylation and tyrosine phosphorylation of cortactin and that phosphorylation inhibits cell spreading. We confirmed the results from the FIT system by examining endogenous cortactin in different cell types. Furthermore, we demonstrate that cell spreading promotes the association of cortactin and FAK and that tyrosine phosphorylation of cortactin disrupts this interaction, which may explain how it inhibits cell spreading.
authors.affiliation: Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, Madrid, Spain.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Meiler
authors.forename: Elvira
authors.initials: E
authors.lastname: Nieto-Pelegrín
authors.forename: Narcisa
authors.initials: N
authors.lastname: Martinez-Quiles
mesh_terms: D000107:Acetylation; D000818:Animals; D002460:Cell Line; D051356:Cortactin / Q000235:genetics / Q000378:metabolism*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D006655:Histone Deacetylases / Q000172:deficiency; D006801:Humans; D051379:Mice; D010766:Phosphorylation; D011485:Protein Binding; D021381:Protein Transport / Q000235:genetics; D013379:Substrate Specificity; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D051356:Cortactin; D014443:Tyrosine; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019061:src-Family Kinases; D006655:Histone Deacetylases