Vinexinss, an atypical "sensor" of retinoic acid receptor gamma signaling: union and sequestration, separation, and phosphorylation.
Fiche publication
Date publication
novembre 2010
Auteurs
Membres identifiés du Cancéropôle Est :
Dr KIEFFER Bruno, Dr ROCHETTE-EGLY Cécile, Dr VONESCH Jean-Luc
Tous les auteurs :
Lalevee S, Bour G, Quinternet M, Samarut E, Kessler P, Vitorino M, Bruck N, Delsuc MA, Vonesch JL, Kieffer B, Rochette-Egly C
Lien Pubmed
Résumé
The transcriptional activity of nuclear retinoic acid receptors (RARs) relies on the association/dissociation of coregulators at the ligand-binding domain. However, we determined that the N-terminal domain (NTD) also plays a role through its phosphorylation, and we isolated vinexinbeta, a cytoskeleton protein with three SH3 domains, as a new partner of the RARgamma NTD. Here we deciphered the mechanism of the interaction and its role in RARgamma-mediated transcription. By combining molecular and biophysical (surface plasmon resonance, NMR, and fluorescence resonance energy transfer) approaches, we demonstrated that the third SH3 domain of vinexinbeta interacts with a proline-rich domain (PRD) located in RARgamma NTD and that phosphorylation at a serine located in the PRD abrogates the interaction. The affinity of the interaction was also evaluated. In vivo, vinexinbeta represses RARgamma-mediated transcription and we dissected the underlying mechanism in chromatin immunoprecipitation experiments performed with F9 cells expressing RARgamma wild type or mutated at the phosphorylation site. In the absence of retinoic acid (RA), vinexinbeta does not occupy RARgamma target gene promoters and sequesters nonphosphorylated RARgamma out of promoters. In response to RA, RARgamma becomes phosphorylated and dissociates from vinexinbeta. This separation allows RARgamma to occupy promoters. This is the first report of an RAR corepressor association/dissociation out of promoters and regulated by phosphorylation.
Référence
FASEB J. 2010 Nov;24(11):4523-34