Vitamin D receptors repress basal transcription and exert dominant negative activity on triiodothyronine-mediated transcriptional activity

J Biol Chem. 1996 May 3;271(18):10910-6. doi: 10.1074/jbc.271.18.10910.

Abstract

We have examined vitamin D receptor (VDR), thyroid hormone receptor (TR), and retinoid X receptor beta (RXR beta) binding to vitamin D response elements (VDREs), two thyroid hormone response elements (TREs) (DR4 and F2), and a retinoic acid response element (DR5). VDR/RXR bound well to the VDREs and to DR4 and DR5 using the electrophoretic mobility shift assay. Surprisingly, VDR/RXR also bound well to F2, which contains half-sites arranged as an inverted palindrome. In co-transfection experiments using CV-1 cells, we observed that VDR repressed basal transcription in the absence of ligand on DR3 and osteopontin VDREs and F2, but had no effect on DR4 or DR5. VDR selectively mediated ligand-dependent transcription on only VDREs. VDR also exhibited dominant negative activity as it blocked triiodothyronine (T3)-mediated transcriptional activity on DR4 and F2. These results demonstrate that VDR/RXR heterodimers can bind promiscuously to a wide range of hormone response elements, including inverted palindromes. Moreover, they show that unliganded VDRs, similar to TRs and retinoic acid receptors, can repress basal transcription. Last, they also suggest a novel repressor function of VDR on T3-mediated transcription which may be significant in tissues where VDR and TR are co-expressed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Chickens
  • DNA-Binding Proteins
  • Fungal Proteins / metabolism
  • Humans
  • Molecular Sequence Data
  • Oligodeoxyribonucleotides
  • Receptors, Calcitriol / physiology*
  • Receptors, Retinoic Acid / metabolism
  • Recombinant Fusion Proteins / metabolism
  • Repressor Proteins / metabolism*
  • Retinoid X Receptors
  • Saccharomyces cerevisiae Proteins*
  • Transcription Factors / metabolism
  • Transcription, Genetic / physiology*
  • Triiodothyronine / physiology*

Substances

  • DNA-Binding Proteins
  • Fungal Proteins
  • GAL4 protein, S cerevisiae
  • Oligodeoxyribonucleotides
  • Receptors, Calcitriol
  • Receptors, Retinoic Acid
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Retinoid X Receptors
  • Saccharomyces cerevisiae Proteins
  • Transcription Factors
  • Triiodothyronine