Inhibition of 1,25-dihydroxyvitamin D3-dependent transcription by synthetic LXXLL peptide antagonists that target the activation domains of the vitamin D and retinoid X receptors.

Published

Journal Article

The vitamin D receptor (VDR) is known to mediate the biological actions of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] through its ability to regulate cellular programs of gene expression. Although RXR appears to participate as a heterodimeric partner with the VDR, absolute evidence for its role remains equivocal in vivo. To test this role and to investigate the requirement for comodulator interaction, we identified VDR- and retinoid X receptor (RXR)-interacting LXXLL peptides and examined whether these molecules could block vitamin D and 9-cis retinoic acid (9-cis RA) response. We used a mammalian cell two-hybrid system to screen a series of nuclear receptor (NR)-reactive LXXLL peptides previously identified through phage display screening for hormone-dependent reactivity with either VDR or RXR. Three categories of peptides were identified: those reactive with both VDR and RXR, those selective for RXR, and those unreactive to either receptor. Peptide fusion proteins were then examined in MC3T3-E1 cells for their ability to block induction of the osteocalcin (OC) promoter by 1,25(OH)2D3 or stimulation of a retinoic acid response element-thymidine kinase (RARE-TK) reporter by 9-cis-RA. Peptides that interacted with both VDR and RXR blocked 1,25(OH)2D3-dependent transcription by up to 75%. Control LXXLL sequences derived from Src-1 and Grip also suppressed 1,25(OH)2D3-induced transactivation; peptides that interacted with RXR blocked 9-cis-RA-induced transcription. Interestingly, two RXR-interacting peptides were also found to block 1,25(OH)2D3 response effectively. These studies support the idea that comodulator recruitment is essential for VDR- and RXR-mediated gene expression and that RXR is required for 1,25(OH)2D3-induced OC gene transcription. This approach may represent a novel means of assessing the contribution of RXR in various endogenous biological responses to 1,25(OH)2D3.

Full Text

Duke Authors

Cited Authors

  • Pathrose, P; Barmina, O; Chang, C-Y; McDonnell, DP; Shevde, NK; Pike, JW

Published Date

  • December 2002

Published In

Volume / Issue

  • 17 / 12

Start / End Page

  • 2196 - 2205

PubMed ID

  • 12469913

Pubmed Central ID

  • 12469913

International Standard Serial Number (ISSN)

  • 0884-0431

Digital Object Identifier (DOI)

  • 10.1359/jbmr.2002.17.12.2196

Language

  • eng

Conference Location

  • United States