GIT1 is a novel MEK1-ERK1/2 scaffold that localizes to focal adhesions.
Cell polarity is critical for cell migration and requires localized signal transduction in subcellular domains. Recent evidence demonstrates that activation of ERK1/2 (extracellular-signal-regulated kinase 1/2) in focal adhesions is essential for cell migration. GIT1 (G-protein-coupled receptor kinase-interacting protein 1) has been shown to bind paxillin and regulate focal-adhesion disassembly. We have previously reported that GIT1 binds to MEK1 [MAPK (mitogen-activated protein kinase)/ERK kinase 1] and acts as a scaffold to enhance ERK1/2 activation in response to EGF (epidermal growth factor). In the present study we show that GIT1 associates with ERK1/2 in focal adhesions and this association increases after EGF stimulation. The CC (coiled-coil) domain of ERK1/2 is required for association with GIT1, translocation to focal adhesions, and cell spreading and migration. Immunofluorescent staining showed that, after EGF stimulation, GIT1 co-localized with pERK1/2 (phosphorylated ERK1/2) in focal adhesions. The binding of GIT1 and ERK1/2 was functionally important, since transfecting an ERK2 mutant lacking the CC domain [ERK2(del CC)] significantly decreased pERK1/2 translocation to focal adhesions, cell spreading and migration induced by EGF. In summary, the CC domain of ERK1/2 is necessary for binding to GIT1, for ERK1/2 activation in focal adhesions, and for cell spreading and migration.
Zhang
Ning
N
The First Affiliated Hospital of Nanjing Medical University, Jiangsu 210029, China.
Cai
Weihua
W
Yin
Guoyong
G
Nagel
David J
DJ
Berk
Bradford C
BC
D048868:Adaptor Proteins, Signal Transducing / Q000032:analysis* / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000032:analysis* / Q000378:metabolism; D002465:Cell Movement; D004815:Epidermal Growth Factor / Q000378:metabolism; D022001:Focal Adhesions / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D048369:MAP Kinase Kinase 1 / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D051419:Paxillin / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction
D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; C485647:GIT1 protein, human; D051419:Paxillin; D004815:Epidermal Growth Factor; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048369:MAP Kinase Kinase 1