Rho stimulates tyrosine phosphorylation of focal adhesion kinase, p130 and paxillin.
The small GTP-binding protein Rho rapidly stimulates the formation of focal adhesions and actin stress fibres when microinjected into serum-starved Swiss 3T3 fibroblasts. This response is inhibited by tyrosine kinase inhibitors. Addition of growth factors such as lysophosphatidic acid and bombesin to Swiss 3T3 cells stimulates a similar response, which is dependent on endogenous Rho proteins. To investigate signalling events regulated by Rho, we have scrape loaded Rho into serum-starved cells. Activated Rho stimulates the tyrosine phosphorylation of a number of proteins, including three proteins known to localise to focal adhesions, pp125FAK, p130 and paxillin. Rho-induced phosphorylation of pp125FAK, p130 and paxillin is observed in the absence of stress fibre formation and is, therefore, independent of Rho-induced actin polymerisation. We propose that the tyrosine kinase, pp125FAK, and the putative adapter proteins, paxillin and p130, are components of a Rho-regulated signal transduction pathway, and that these protein tyrosine phosphorylation events are likely to be important for the regulation of focal adhesion formation.
Flinn
H M
HM
Ludwig Institute for Cancer Research, University College London School of Medicine, UK.
Ridley
A J
AJ
D016475:3T3 Cells; D000199:Actins / Q000648:ultrastructure; D000209:Acute-Phase Proteins / Q000276:immunology*; D000818:Animals; D000941:Antigens / Q000276:immunology*; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D050719:Crk-Associated Substrate Protein; D003598:Cytoskeletal Proteins / Q000378:metabolism; D003599:Cytoskeleton / Q000648:ultrastructure; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D007150:Immunohistochemistry; D051379:Mice; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins; D050717:Retinoblastoma-Like Protein p130
D000199:Actins; D000209:Acute-Phase Proteins; D000941:Antigens; C493842:Bcar1 protein, mouse; D015815:Cell Adhesion Molecules; D050719:Crk-Associated Substrate Protein; D003598:Cytoskeletal Proteins; D051419:Paxillin; D010750:Phosphoproteins; D011506:Proteins; C496062:Pxn protein, mouse; D050717:Retinoblastoma-Like Protein p130; C010781:acute-phase protein rho; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse