FXR and RXRA binding in mouse liver
The Farnesoid-X-Receptor (FXR) is a nuclear receptor (NR) known to obligately heterodimerize with Retinoid-X-Receptor (RXR). FXR is expressed as four isoforms (a1-a4) that drive transcription from IR-1 (inverted repeat-1) DNA motifs. More recently, FXR isoforms a2/a4 were found to activate transcription predominantly from non-canonical ER-2 (everted repeat-2) DNA motifs, mediating most metabolic effects of general FXR activation.Here, we explored whether  co-occupancy of FXR and RXR in the mouse liver has an influence on DNA motif binding preference. We found RXR acts as a molecular switch, promoting FXRa2 activation from IR-1 instead of ER-2 motifs. Our results showcase FXR as the first NR with RXR-dependent and independent modes of activation, highlighting a potential new layer of complexity for other RXR-heterodimerizing NRs. Overall design: To investigate their binding profile and co-occupancy, we performed ChIP-seq for FXR and RXRA from male mouse liver Please note that the following sample raw data was analyzed in the current study as described below: Experiment Title Run BioSample GSM1899653 FXRChIP_MVEH8 SRR2541540 SAMN04123807