Hepatocyte Growth Factor/scatter factor-induces phosphorylation of cortactin in A431 cells in a Src kinase-independent manner.
The Hepatocyte Growth Factor receptor transduces proliferating and scattering signals in epithelial and endothelial cells. We have explored potential interactions of the HGF/SF receptor beta-subunit (p145(beta MET)) with F-actin binding partners aiming to identify novel downstream effectors implicated in HGF/SF pluripotent signalling. Cortactin, a p80/85 F-actin binding protein, was found phosphorylated on tyrosine in response to HGF-SF in A431 human epidermoid carcinoma cells, expressing the HGF/SF receptor (c-MET). The HGF/SF receptor was enriched in the detergent-insoluble fraction and was found to co-precipitate with cortactin and to associate in vitro with cortactin. The Grb2 small adapter protein known to associate via its Src homology 2 domain (SH2) with the MET C-terminus, was also associated with cortactin. Transient transfection of A431 cells with dominant-negative Grb2 constructs has revealed that the Grb2-C-SH3 domain possesses a central role in cortactin phosphorylation in response to HGF/SF. Finally, tyrosine phosphorylation of cortactin was found uncoupled of endogenous c-Src kinase activity, thus further supporting the hypothesis that cortactin is a direct target of the MET kinase. We propose that cortactin may constitute a docking site for MET-derived signals within the cytoskeleton.
Crostella
L
L
Laboratory of Cell Biology, Institute of Hepatology, Department of Medicine, Royal Free and University College London Medical School, London WC1E 6HX, UK.
Lidder
S
S
Williams
R
R
Skouteris
G G
GG
D048868:Adaptor Proteins, Signal Transducing; D000081247:CSK Tyrosine-Protein Kinase; D002458:Cell Fractionation; D051356:Cortactin; D003599:Cytoskeleton / Q000378:metabolism; D003902:Detergents; D051380:GRB2 Adaptor Protein; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D022781:Hepatocytes; D006801:Humans; D008840:Microfilament Proteins / Q000378:metabolism*; D017830:Octoxynol; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D018909:src Homology Domains; D019061:src-Family Kinases
D048868:Adaptor Proteins, Signal Transducing; C495868:CTTN protein, human; D051356:Cortactin; D003902:Detergents; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D008840:Microfilament Proteins; D011506:Proteins; D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D017830:Octoxynol; D011505:Protein-Tyrosine Kinases; D019859:Proto-Oncogene Proteins c-met; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human