Kiely, P. A., Baillie, G. S. , Barrett, R., Buckley, D. A., Adams, D. R., Houslay, M. D. and O'Connor, R. (2009) Phosphorylation of RACK1 on tyrosine 52 by c-Abl is required for IGF-I-mediated regulation of focal adhesion kinase (FAK). Journal of Biological Chemistry, 284, pp. 20263-20274. (doi: 10.1074/jbc.M109.017640) (PMID:19423701) (PMCID:PMC2740452)
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Abstract
Focal Adhesion Kinase (FAK) activity is controlled by growth factors and adhesion signals in tumor cells. The scaffolding protein RACK1 (Receptor for Activated C Kinases) integrates Insulin-like Growth Factor I (IGF-I) and integrin signalling, but whether RACK1 is required for FAK function is unknown. Here we show that association of FAK with RACK1 is required for both FAK phosphorylation and dephosphorylation in response to IGF-I. Suppression of RACK1 by siRNA ablates FAK phosphorylation, and reduces cell adhesion, cell spreading and clonogenic growth. Peptide array and mutagenesis studies localise the FAK-binding interface to blades I-III of the RACK1 a-propeller and specifically identify a set of basic and hydrophobic amino acids (Arg47, Tyr52, Arg57, Arg60, Phe65, Lys127 and Lys130) as key determinants for association with FAK. Mutation of tyrosine 52 alone is sufficient to disrupt interaction of RACK1 with FAK in cells where endogenous RACK1 is suppressed by siRNA. Cells expressing a Y52F mutant RACK1 are impaired in adhesion, growth and foci formation. Comparative analyses of homology models and crystal structures for RACK1 orthologues suggest a role for Tyr52 as a site for phosphorylation that induces conformational change in RACK1, switching the protein into a FAK-binding state. Tyrosine 52 is further shown to be phosphorylated by c-Abl kinase, and the c-Abl inhibitor STI571 disrupts FAK interaction with RACK1. We conclude that FAK association with RACK1 is regulated by phosphorylation of Tyr52. Our data reveal a novel mechanism whereby IGF-I and c-Abl control RACK1 association with FAK to facilitate adhesion signalling
Item Type: | Articles |
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Status: | Published |
Refereed: | Yes |
Glasgow Author(s) Enlighten ID: | Houslay, Professor Miles and Baillie, Professor George |
Authors: | Kiely, P. A., Baillie, G. S., Barrett, R., Buckley, D. A., Adams, D. R., Houslay, M. D., and O'Connor, R. |
Subjects: | Q Science > QH Natural history > QH345 Biochemistry |
College/School: | College of Medical Veterinary and Life Sciences > School of Molecular Biosciences College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience |
Journal Name: | Journal of Biological Chemistry |
Journal Abbr.: | J Biol Chem. |
Publisher: | American Society for Biochemistry and Molecular Biology, Inc. |
ISSN: | 0021-9258 |
ISSN (Online): | 1083-351X |
Published Online: | 07 May 2009 |
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