Requirement for Rho in integrin signalling.
Overnight culture of Swiss 3T3 cells in serum-free medium leads to loss of focal adhesions and associated actin stress fibres, although the cells remain well spread. The small GTP-binding protein Rho is required for the formation of stress fibres and focal adhesions induced by growth factors such as lysophosphatidic acid (LPA) in serum-starved Swiss 3T3 cells, and for the LPA-induced tyrosine phosphorylation of several focal adhesion proteins. Plating of cells on extracellular matrix proteins also stimulates protein tyrosine phosphorylation and the formation of stress fibres and focal adhesions in the absence of added growth factors. These responses were inhibited in cells scrape-loaded with the Rho inhibitor C3 transferase. Focal adhesion and stress fibre formation was also triggered by addition of a peptide GRGDS, which is recognised by a number of integrins and is contained within the cell binding domain of a variety of extracellular matrix proteins. The activity of the GRGDS peptide was blocked by microinjecting cells with C3 transferase, suggesting that peptide binding to integrins stimulates a Rho-dependent assembly of focal adhesions. These experiments indicate that Rho is involved in signalling downstream of integrins.
Barry
S T
ST
Department of Biochemistry, University of Leicester, UK.
Flinn
H M
HM
Humphries
M J
MJ
Critchley
D R
DR
Ridley
A J
AJ
D016475:3T3 Cells; D036002:ADP Ribose Transferases / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D001905:Botulinum Toxins; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules; D016895:Culture Media, Serum-Free; D003598:Cytoskeletal Proteins / Q000378:metabolism; D005353:Fibronectins / Q000494:pharmacology; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D019204:GTP-Binding Proteins / Q000378:metabolism*; D016023:Integrins / Q000378:metabolism*; D051379:Mice; D009687:Nuclear Proteins / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology; D051419:Paxillin; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases; D015398:Signal Transduction; D020741:rho GTP-Binding Proteins
D000199:Actins; D015815:Cell Adhesion Molecules; D016895:Culture Media, Serum-Free; D003598:Cytoskeletal Proteins; D005353:Fibronectins; D016023:Integrins; D009687:Nuclear Proteins; D009842:Oligopeptides; D051419:Paxillin; D010750:Phosphoproteins; C496062:Pxn protein, mouse; C095383:nucleolar phosphoprotein p130; C049554:glycyl-arginyl-glycyl-aspartyl-serine; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496051:Ptk2 protein, mouse; D001905:Botulinum Toxins; D019204:GTP-Binding Proteins; D020741:rho GTP-Binding Proteins