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Updated: Aug 14, 2025

Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists
Published on: November 15, 2013
Agonist-controlled competition of RAR and VDR nuclear receptors for heterodimerization with RXR is manifested in
Bálint Rehó1, Lina Fadel1, Peter Brazda2
1Department of Biophysics and Cell Biology, Faculty of Medicine, Doctoral School of Molecular Medicine, University of Debrecen, Debrecen, Hungary.
Nuclear receptors (NRs) like retinoic acid receptor (RAR) and vitamin D receptor (VDR) compete for DNA binding sites. This competition, influenced by ligands and retinoid X receptor (RXR), impacts NR therapies.
Area of Science:
- Molecular Biology
- Cell Biology
- Endocrinology
Background:
- Nuclear receptors (NRs) interact with retinoid X receptor (RXR) in a ligand-dependent manner.
- Previous studies indicated competition among NRs for RXR heterodimerization.
Purpose of the Study:
- To investigate competition in DNA binding between retinoic acid receptor (RAR) and vitamin D receptor (VDR).
- To understand the role of RXR and specific ligands in this DNA binding competition.
Main Methods:
- Live-cell imaging using fluorescence correlation spectroscopy.
- Monitoring the mobility and DNA binding of RAR and VDR.
- Utilizing specific agonists and coexpression of NRs and RXR.
Main Results:
- RAR and VDR exhibit competitive DNA binding, influenced by RXR availability and specific agonists.
- RAR demonstrates dominant DNA binding over VDR, especially in the absence of ligands or when both ligands are present.
- Agonists modulate DNA-bound fractions, with RAR's binding enhanced by its agonist and diminished by VDR's agonist, and vice versa.
Conclusions:
- Competition for RXR and DNA binding sites occurs between RAR and VDR in an agonist-dependent manner.
- RAR generally dominates VDR in DNA binding, affecting therapeutic outcomes.
- Understanding NR competition may help ameliorate side effects of NR-ligand therapies and refine NR action models.
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