Transformation of rat fibroblasts by phospholipase C-γ1 overexpression is accompanied by tyrosine dephosphorylation of paxillin

We previously have shown that the overexpression of phospholipase C-γ1 (PLC-γ1) in rat 3Y1 fibroblasts results in malignant transformation (Chang, J.-S., Noh, D.Y., Park, I.A., Kim, M.J., Song, H., Ryu, S.H. and Suh, P.-G. (1997) Cancer Res. 57, 5465-5468). The transformed cells, which initially are in an elongated and flat form after seeding in plastic dishes, become rounded during continued culture. We found that tyrosine dephosphorylation of paxillin accompanies this morphological change of the transformed cells and that PLC-γ1 co-immunoprecipitates together with paxillin and vice versa, but not after the cells have become round. Transformed cells growing on fibronectin-pre-coated dishes regain their flat morphology and this is accompanied by paxillin tyrosine phosphorylation. Furthermore, immunoprecipitation analysis showed that paxillin forms a heteromeric complex with PLC-γ1 in cells grown on fibronectin. These results suggest that a complex formation between paxillin and PLC-γ1 may play a role in cell-substrate adhesion. Copyright (C) 1999 Federation of European Biochemical Societies.