The role of paxillin in the signalling of the alphavbeta3/talin/kindlin complex

Integrins are cell-surface receptors required for cell adhesion, migration, proliferation, differentiation and survival. Many studies propose that signalling by integrins requires the recruitment of the cytoplasmic adapter protein paxillin. However, how paxillin is recruited to integrins is not yet understood. My thesis results support our hypothesis that paxillin coordinates the signal transmission upon integrin beta3 activation. The colocalisation assay of endogenous paxillin with transfected 3 WT and mutant constructs showed that paxillin colocalises better with the constructs having a functional beta3 NPLY motif than those with no functional motif. Motif involved in signal transmission downstream of the integrin. The paxillin constructs deletions showed that LIM 1 and LIM 3 are responsible of paxillin localisation at focal adhesion. Mutational studies led us to design a mutation patch, LIM 3.1, showing less focal adhesions specificity than the LIM 3 constructs suggesting an impaired interaction. This has been confirmed with the FRAP assay as LIM 3 shows specificity to the tyrosine of the beta3 NPLY motif whereas LIM 3.1 does not