Focal adhesion kinase pp125FAK and the beta 1 integrin subunit are constitutively complexed in HaCaT cells.
Binding of integrins to the extracellular matrix (ECM) activates various signal transduction pathways and regulates gene expression in many cell types. Integrin-dependent cytoplasmic protein/protein interactions are necessary for activation of those signal transduction cascades. In our studies we investigated a possible association of pp125FAK, an adhesion involved tyrosine kinase, with the integrin beta 1 subunit. Further we wanted to know to which extent protein tyrosine phosphorylation affects cell adhesion to the ECM and the possible beta 1 integrin/pp125FAK complex. We were able to show that in HaCaT cells (a human keratinocyte derived cell line) the integrin beta 1 subunit is associated with tyrosine kinase pp125FAK. This association was observed in ECM-adherent cells and nonadherent cells and is independent of tyrosine phosphorylation. However, cell adhesion of HaCaT cells to specific substrates requires tyrosine phosphorylation since genistein treatment that blocks phosphorylation of many cellular proteins as pp125FAK led to a reduced substrate adhesion.
Danker
K
K
Institut für Molekularbiologie und Biochemie, Freie Universität Berlin, Germany. kdanker@zedat.fu-berlin.de
Gabriel
B
B
Heidrich
C
C
Reutter
W
W
D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology*; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005109:Extracellular Matrix / Q000378:metabolism; D005353:Fibronectins; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism*; D046911:Macromolecular Substances; D009363:Neoplasm Proteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D011102:Polyhydroxyethyl Methacrylate; D011107:Polylysine; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000187:drug effects; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology*; D013449:Sulfonamides; D014407:Tumor Cells, Cultured
D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D005353:Fibronectins; D019012:Integrin beta1; D007546:Isoquinolines; D046911:Macromolecular Substances; D009363:Neoplasm Proteins; D013449:Sulfonamides; D011107:Polylysine; D011102:Polyhydroxyethyl Methacrylate; D019833:Genistein; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496050:PTK2 protein, human; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide