E-cadherin controls β-catenin and NF-κB transcriptional activity in mesenchymal gene expression

11 pages, 7 figures.-- et al.E-cadherin and its transcriptional repressor Snail1 (Snai1) are two factors that control epithelial phenotype. Expression of Snail1 promotes the conversion of epithelial cells to mesenchymal cells, and occurs concomitantly with the downregulation of E-cadherin and the upregulation of expression of mesenchymal genes such as those encoding fibronectin and LEF1. We studied the molecular mechanism controlling the expression of these genes in mesenchymal cells. Forced expression of E-cadherin strongly downregulated fibronectin and LEF1 RNA levels, indicating that E-cadherin-sensitive factors are involved in the transcription of these genes. E-cadherin overexpression decreased the transcriptional activity of the fibronectin promoter and reduced the interaction of beta-catenin and NF-kappaB with this promoter. Similar to beta-catenin, NF-kappaB was found, by co-immunoprecipitation and pull-down assays, to be associated with E-cadherin and other cell-adhesion components. Interaction of the NF-kappaB p65 subunit with E-cadherin or beta-catenin was reduced when adherens junctions were disrupted by K-ras overexpression or by E-cadherin depletion using siRNA. These conditions did not affect the association of p65 with the NF-kappaB inhibitor IkappaBalpha. The functional significance of these results was stressed by the stimulation of NF-kappaB transcriptional activity, both basal and TNF-alpha-stimulated, induced by an E-cadherin siRNA. Therefore, these results demonstrate that E-cadherin not only controls the transcriptional activity of beta-catenin but also that of NF-kappaB. They indicate too that binding of this latter factor to the adherens junctional complex prevents the transcription of mesenchymal genes.G. S. was supported by a fellowship from the UAB; M.E. and D.C. from the Ministerio de Educación; C.A., from the FIS (Fondo de Investigaciones Sanitarias), and M.P. from the AGAUR (Agència de Gestió d’Ajuts Universitaris i de Recerca). S.P. was supported by a La Cierva contract. This research was funded by FIS grants 01/3060 and 03/0925 to J.B., SAF2006-00339 to A.G.H., BFU2006-03203 to M.D., and SAF2004-01015 to A.M. Partial support through grants from the Instituto Carlos III (RTICCC, C03710), Comunidad de Madrid (S-GEN-0266-2006) and the Generalitat de Catalunya (2005SGR00970) is also appreciated.Peer reviewe