Ternary complexes and cooperative interplay between NCoA-62/Ski-interacting protein and steroid receptor coactivators in vitamin D receptor-mediated transcription.

The vitamin D receptor (VDR) is a ligand-dependent transcriptional factor that binds to vitamin D-responsive elements as a heterodimer with retinoid X receptor (RXR) to regulate target gene transcription. The steroid receptor coactivator (SRC) proteins are coactivators that interact with the AF-2 domain of VDR to augment 1,25-dihydroxyvitamin D3-dependent transcription. ...
In contrast, NCoA-62/Ski-interacting protein (SKIP) is a distinct, activation function-2-independent coactivator for VDR. The current study examined whether these two distinct classes of coactivators impact functionally on VDR-mediated transcription. Using a ternary complex binding assay, we observed a marked preference for the direct interaction of NCoA-62/SKIP with the VDR-RXR heterodimer as compared with the VDR-VDR homodimer or VDR monomer. The liganded VDR also formed a ternary complex with NCoA-62/SKIP and SRC proteins in vitro. Competition experiments using LXXLL peptides showed that NCoA-62/SKIP and SRC coactivators contact different domains of the VDR-RXR heterodimer. Synergistic interplays were observed between NCoA-62/SKIP and SRC coactivators in VDR-mediated transcriptional assays, and protein interference assays indicated a requirement for both NCoA-62/SKIP and SRCs in VDR- mediated transcription. These studies suggest that the ligand-dependent and simultaneous interaction of NCoA-62/SKIP and SRC coactivators with distinct interaction domains within the VDR-RXR heterodimer results in cooperative interplays between coactivators in VDR-mediated transcription.
Mesh Terms:
Amino Acid Sequence, Animals, COS Cells, Dimerization, Histone Acetyltransferases, Humans, Nuclear Proteins, Nuclear Receptor Coactivator 1, Nuclear Receptor Coactivators, Protein Binding, Protein Conformation, Receptors, Calcitriol, Transcription Factors, Transcription, Genetic
J. Biol. Chem.
Date: Nov. 02, 2001
Download Curated Data For This Publication
Switch View:
  • Interactions 15