Focal Adhesion Kinase pp125FAKand the β1 Integrin Subunit Are Constitutively Complexed in HaCaT Cells

• Published in: Experimental cell research Vol. 239; no. 2; pp. 326 - 331
• Main Authors: Danker, Kerstin, Gabriel, Boris, Heidrich, Claudia, Reutter, Werner
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01-03-1998
• Subjects: focal adhesion kinase; integrins; signal transduction; signal transduction; focal adhesion kinase; integrins
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1006/excr.1997.3916

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 β1 subunit. Further we wanted to know to which extent protein tyrosine phosphorylation affects cell adhesion to the ECM and the possible β1 integrin/pp125FAKcomplex. We were able to show that in HaCaT cells (a human keratinocyte derived cell line) the integrin β1 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 pp125FAKled to a reduced substrate adhesion.