TRANSCRIPTION REGULATION BY RAR/RXR

(activated by their ligand retinoic acid)

The RAR/RXR heterodimer binds to a specific sequence of bases in DNA, called a DNA element, or retinoic acid responsive element (RARE).
The consensus sequence for the half binding site is AGGTCA.

Original source: Bastien and Rochette-Egly 2004. Nuclear retinoid receptors and the transcription of retinoid-target genes. Gene 328:1-16

Figure Three-step mechanism of retinoid receptor action.
(A) In the absence of ligand, retinoid receptors bound to response elements located in the promoter of target genes are associated with histone deacetylase-containing (HDAC) complexes tethered through corepressors and repress transcription.
(B) Upon ligand binding, the corepressors dissociate, allowing the recruitment of coactivators associated with complexes displaying histone acetyltransferase (HAT), methyltransferase, kinase or ATP-dependent remodeling (SWI/SNF) activities that decompact repressive chromatin.
(C) In the third step, the coactivators dissociate and the SMCC mediator complex assembles. Then the mediator expedites entry of the RNA Pol II and the general transcription factors to the promoter, resulting in transcription initiation.