Requirement for Rho in Integrin Signalling |
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Authors: | Simon T Barry Helen M Flinn Martin J Humphries David R Critchley Anne J Ridley |
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Institution: |
a Department of Biochemistry, University of Leicester, University Road, Leicester, UK
b Ludwig Institute for Cancer Research, Courtauld Building, 91, Riding House Street, London, UK
c School of Biological Sciences, University of Manchester Oxford Road, Manchester, UK
d Department of Biochemistry and Molecular Biology, University College London, Goner Street, London, UK |
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Abstract: | 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. |
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Keywords: | Rho focal adhesions integrins tyrosine phosphorylation actin cytoskeleton |
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