Roles of Gab1 and SHP2 in Paxillin Tyrosine Dephosphorylation and Src Activation in Response to Epidermal Growth Factor

• Published in: The Journal of biological chemistry 2004-02, Vol.279 (9), p.8497-8505
• Main Authors: Ren, Yuan, Meng, Songshu, Mei, Lin, Zhao, Z. Joe, Jove, Richard, Wu, Jie
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing; Binding Sites; Cell Movement; Csk protein; CSK Tyrosine-Protein Kinase; Cytoskeletal Proteins - metabolism; Enzyme Activation - drug effects; Enzyme Inhibitors - pharmacology; Epidermal Growth Factor - pharmacology; Gab1 protein; Humans; Intracellular Signaling Peptides and Proteins; Mitogen-Activated Protein Kinases - metabolism; Mutation; Paxillin; Phosphoproteins - genetics; Phosphoproteins - metabolism; Phosphotyrosine - metabolism; Protein Tyrosine Phosphatase, Non-Receptor Type 11; Protein Tyrosine Phosphatases - genetics; Protein Tyrosine Phosphatases - metabolism; Protein-Tyrosine Kinases - metabolism; Recombinant Fusion Proteins; SHP2 protein; src-Family Kinases - antagonists & inhibitors; src-Family Kinases - metabolism; Transfection; Tumor Cells, Cultured
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M312575200

Epidermal growth factor (EGF) induces paxillin tyrosine dephosphorylation and Src activation, but the signaling pathways that mediate these responses were largely undefined. We found that Gab1, a docking protein for the SHP2 protein-tyrosine phosphatase in EGF-stimulated cells, was associated with paxillin. SHP2 dephosphorylated paxillin and caused dissociation of Csk, a negative regulator of Src, from paxillin but had no effect on paxillin-Src association. A lower level of Src Tyr-530 phosphorylation was detected in paxillin-associated Src in EGF-stimulated cells. Expression of an SHP2 binding defective mutant of Gab1 (Gab1FF) or a catalytically inactive mutant of SHP2 (SHP2DN) prevented paxillin tyrosine dephosphorylation and Src activation induced by EGF. Importantly, Gab1FF blocked paxillin-SHP2 complex formation, Src Tyr-530 dephosphorylation, Erk activation, and cell migration induced by EGF. Inhibition of Src tyrosine kinase activity abrogated EGF-stimulated Erk activation and cell migration. Together, these results reveal that Gab1 recruits SHP2 to dephosphorylate paxillin, leading to dissociation of Csk from the paxillin-Src complex and Src activation and that Src is an SHP2 effector involved in EGF-stimulated Erk activation and cell migration.