Tyrosine 302 in RACK1 is essential for insulin-like growth factor-I-mediated competitive binding of PP2A and {beta}1 integrin and for tumor cell proliferation and migration

Kiely, P. A., Baillie, G. S. , Lynch, M. J., Houslay, M. D. and O'Connor, R. (2008) Tyrosine 302 in RACK1 is essential for insulin-like growth factor-I-mediated competitive binding of PP2A and {beta}1 integrin and for tumor cell proliferation and migration. Journal of Biological Chemistry, 283(34), pp. 22952-22961. (doi: 10.1074/jbc.M800802200)

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Publisher's URL: http://dx.doi.org/10.1074/jbc.M800802200

Abstract

Insulin-like growth factor (IGF)-I regulates a mutually exclusive interaction of PP2A and {beta}1 integrin with the WD repeat scaffolding protein RACK1. This interaction is required for the integration of IGF-I receptor (IGF-IR) and adhesion signaling. Here we investigated the nature of the binding site for PP2A and {beta}1 integrin in RACK1. A WD7 deletion mutant of RACK1 did not associate with PP2A but retained some interaction with {beta}1 integrin, whereas a WD6/WD7 mutant lost the ability to bind to both PP2A and {beta}1 integrin. Using immobilized peptide arrays representing the entire RACK1 protein, we identified a common cluster of amino acids (FAGY) at positions 299-302 within WD7 of RACK1 which were essential for binding of both PP2A and {beta}1 integrin to RACK1. PP2A showed a higher level of association with a peptide in which Tyr-302 was phosphorylated compared with an unphosphorylated peptide, whereas beta1 integrin binding was not affected by phosphorylation. RACK1 mutants in which either the FAGY cluster or Tyr-302 were mutated to AAAF, or Phe, respectively, did not interact with either PP2A or {beta}1 integrin. These mutants were unable to rescue the decrease in PP2A activity caused by suppression of RACK1 in MCF-7 cells with small interfering RNA. MCF-7 cells and R+ (IGF-IR-overexpressing fibroblasts) expressing these mutants exhibited decreased proliferation and migration, whereas R- cells (IGF-IR null fibroblasts) were unaffected. Taken together, the data demonstrate that Tyr-302 in RACK1 is required for interaction with PP2A and {beta}1 integrin, for regulation of PP2A activity, and for IGF-I-mediated cell migration and proliferation

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Houslay, Professor Miles and Baillie, Professor George
Authors: Kiely, P. A., Baillie, G. S., Lynch, M. J., 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:19 June 2008
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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
438301Phosphodiesterase-4 isoforms - intracellular targeting, regulation and potential therapeutic targetsMiles HouslayMedical Research Council (MRC)G0600765Institute of Neuroscience and Psychology