The proto-oncogene Fgr regulates cell migration and this requires its plasma membrane localization.
Fgr participates in integrin signaling in myeloid leukocytes. To examine the role of its specific domains in regulating cell migration, we expressed various Fgr molecules in COS-7 cells. Full-length, membrane-bound Fgr, but not an N-terminal truncation mutant that distributed to an intracellular compartment, increased cell migration on fibronectin and enhanced phosphorylation of the p85 subunit of phosphatidylinositol 3-kinase (PI3K), cortactin and focal adhesion kinase (FAK) at Y397 and Y576. Fgr increased Rac GTP loading, and phosphorylation of the Rac GEF Vav2, and bound to a protein complex formed by the Rho inhibitor p190RhoGAP and FAK, increasing p190RhoGAP phosphorylation, in a manner absolutely dependent on membrane localization. A kinase-defective truncation mutant of Fgr increased cell migration, albeit to a much lower extent than full-length Fgr, and was found to associate with the plasma membrane, to activate Rac and to form complexes with p190RhoGAP/FAK. Formation of complexes between p190RhoGAP, Fgr, and the FAK-related protein Pyk2 were also detected in murine macrophages. These findings suggest that the proto-oncogene Fgr regulates cell migration impinging on a signaling pathway implicating FAK/Pyk2 and leading to activation of Rac and the Rho inhibitor p190RhoGAP.
Continolo
Silvia
S
Department of Pathology, Section of General Pathology, University of Verona, Verona, Italy.
Baruzzi
Anna
A
Majeed
Meytham
M
Caveggion
Elena
E
Fumagalli
Laura
L
Lowell
Clifford A
CA
Berton
Giorgio
G
D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism*; D002465:Cell Movement / Q000502:physiology*; D002522:Chlorocebus aethiops; D051356:Cortactin; D004789:Enzyme Activation; D005353:Fibronectins / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D049452:Green Fluorescent Proteins / Q000378:metabolism; D015151:Immunoblotting; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000378:metabolism; D018613:Microscopy, Confocal; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D019061:src-Family Kinases
D051356:Cortactin; D005353:Fibronectins; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D049452:Green Fluorescent Proteins; D008840:Microfilament Proteins; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; D019061:src-Family Kinases; C495869:Cttn protein, mouse; C496051:Ptk2 protein, mouse; C053102:proto-oncogene proteins c-fgr