A Study of Allostery Within Liganded RARα:RXR Heterodimers at the Genome Scale [CUT&Run]

We provide evidence of coordination between heterodimeric nuclear hormone receptor ligands at the genome scale to reveal three unique transcriptional outcomes. First, when stimulated in pancreatic acinar cells, distinct doubly-liganded complexes of the retinoic acid receptor-α (RARα) and retinoid-X-receptor (RXR) bind divergent DNA hormone response elements (HRE). Furthermore, the link between ligand pairs and HRE specificity is correlated with RNA transcript formation. Second, RXR ligands can function as either silent partners or as cooperative effectors on distinct HREs, also with correlated transcriptional outcomes. Third, the absence of unique binding sites on DNA by unliganded RARα:RXR suggests that productive HRE recognition and binding is an exclusive feature of the agonist-bound heterodimer. To achieve the above, DNA-bound heterodimers of RARα:RXR were isolated separately with an RARα-specific antibody, RARα-specific and RXR-specific agonists and the pan-ligand, 9-cis retinoic acid, using the CUT&RUN technique. At each liganded state, transcriptional activity was detected by mRNA sequencing.