Vinexinß, an atypical "sensor" of retinoic acid receptor gamma signaling: union and sequestration, separation, and phosphorylation

FASEB J. 2010 Nov;24(11):4523-34. doi: 10.1096/fj.10-160572. Epub 2010 Jul 15.

Abstract

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 vinexinβ, a cytoskeleton protein with three SH3 domains, as a new partner of the RARγ NTD. Here we deciphered the mechanism of the interaction and its role in RARγ-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 vinexinβ interacts with a proline-rich domain (PRD) located in RARγ NTD and that phosphorylation at a serine located in the PRD abrogates the interaction. The affinity of the interaction was also evaluated. In vivo, vinexinβ represses RARγ-mediated transcription and we dissected the underlying mechanism in chromatin immunoprecipitation experiments performed with F9 cells expressing RARγ wild type or mutated at the phosphorylation site. In the absence of retinoic acid (RA), vinexinβ does not occupy RARγ target gene promoters and sequesters nonphosphorylated RARγ out of promoters. In response to RA, RARγ becomes phosphorylated and dissociates from vinexinβ. This separation allows RARγ to occupy promoters. This is the first report of an RAR corepressor association/dissociation out of promoters and regulated by phosphorylation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / metabolism*
  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Cell Line, Tumor
  • Chlorocebus aethiops
  • Mice
  • Molecular Sequence Data
  • Mutation / genetics
  • Phosphorylation
  • Promoter Regions, Genetic
  • Protein Binding
  • Receptors, Retinoic Acid / genetics
  • Receptors, Retinoic Acid / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Signal Transduction*

Substances

  • Adaptor Proteins, Signal Transducing
  • Receptors, Retinoic Acid
  • Recombinant Proteins
  • retinoic acid receptor gamma