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Role of the paxillin/poly(A)-binding protein 1 complex in mRNA trafficking during cell migration

Reference	BB/C003527/1
Principal Investigator / Supervisor	Dr Igor Barsukov
Co-Investigators / Co-Supervisors	Dr Jim Norman
Institution	University of Leicester
Department	Biochemistry
Funding type	Research
Value (£)	216,359
Status	Completed
Type	Research Grant
Start date	09/05/2005
End date	08/11/2006
Duration	18 months

Abstract

During cell migration the adaptor protein, paxillin, is recruited to integrin complexes at the cell's leading edge and is thought to be involved in positioning multiprotein complexes that are key to the maintenance of polarity during cell migration. One of the mechanisms by which cells generate and maintain polarity is by trafficking and localising mRNA transcripts to particular subcellular locations, and it is therefore of interest that we have recently identified poly(A)-binding protein 1 (PABP1) as a novel ligand for paxillin. PABP1 associates with paxillin with high affinity, and the resulting complex shuttles in and out of the nucleus and localises to the leading edge of migrating cells. In preliminary studies, mutants of PABP1 that cannot bind paxillin are inefficiently exported from the nucleus and are thus unable to reach the leading edge of migrating cells. Furthermore, cells expressing these mutants are unable to migrate directionally, raising the possibility that PABP1 must associate with paxillin to maintain cell polarity during migration.Recent NMR and crystallographic studies of the complex formed between paxillin and focal adhesion kinase highlight the dangers of undertaking mutagenesis studies without detailed information on the structure of the intermolecular complex. We therefore propose a detailed structural analysis of the paxillin/PABP1 complex using biochemical and biophysical technologies. We have demonstrated the feasibility of this approach by collecting preliminary NMR spectra showing a domain/domain interaction between paxillin and PABP1. We propose to pursue these approaches to obtain detailed information of the intermolecular contacts between paxillin and PABP1, and how these relate to the association of PABP1 with mRNA and components of the translation apparatus. Using this information we will construct mutants of PABP1 that have reduced affinity for paxillin, and synthesise peptide antagonists of paxillin/PABP1 interaction. These willbe designed to have minimal effect on the folding of PABP1, its association with mRNA and ability to enhance poly(A)-dependent translation. These mutant PABP1s and cell permeant peptides will allow determination of the requirement for paxillin in the export of mRNA from the nucleus and its transport to the leading edge of migrating cells. We will also measure various parameters of cell movement on 2D and 3D matrices following disruption of the paxillin/PABP1 complex and evaluate the requirement for this aspect of mRNA trafficking during directional migration. We anticipate that this parallel application of biochemical, biophysical and cell biological approaches will yield valuable information concerning the molecular mechanisms by which mRNA is trafficked in migrating cells and how this relates to the development of cell polarity.

Summary

unavailable

Committee	Closed Committee - Biochemistry & Cell Biology (BCB)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

Associated awards:

BB/C003527/2 Role of the paxillin/poly(A)-binding protein 1 complex in mRNA trafficking during cell migration

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