Fig. 7: Synergistic actions of FDN and steroids.
a Superposition of the structures of FDN-bound PXR and PXR bound to E2 and END (orange, PDB code 7AXK). b FDN docking pose obtained in the presence of E2. The docking pose (in gray) matches the PXR: FDN crystallographic structure (in violet, RMSD = 1.67 Å), and correctly reproduces the H-bond with residue Q285. c FDN docking pose obtained in the presence of EE2. The docking pose (in gray) matches the crystallographic structure (in violet, RMSD = 1.52 Å), and correctly reproduces the H-bond with residue Q285. d Crystal structure overlaying differential HDX indicates alternations in the structural conformation of PXR-SRC1 due to SR12813, FDN, FDN/E2, or FDN/EE2 (PDB ID: 3HVL) binding. Structures are color-coded according to the color bar at the bottom of the figure where colors represent differences in deuterium uptake (%D). Regions highlighted in black are areas not covered in HDX analysis. e Fractional uptake difference heatmaps showing variations of deuterium uptake between ligand-bound PXR-SRC1. f, g HG5LN GAL4-PXR-LBD cells were exposed to different concentrations of FDN in combination with E2 or EE2 (n = 4). Dashed lines represent the theoretical activation curves obtained for the additive combination of individual compound activities calculated using the Bliss independence model86. Assays were performed in at least three independent experiments, and data are expressed as mean ± SEM. h RT-qPCR analysis of Mdr1, Cyp3a4, and Cyp1a1 mRNA expression in hPXR-overexpressing LS174T cells treated for 48 h with solvent (0.1% DMSO) or the indicated ligands (RIF and FDN at 10 μM; E2 and EE2 at 3 μM). Results were obtained from three separate experiments performed in triplicate. i–k RT-qPCR analysis of Cyp3a4, Ugt1a1, and Mdr1 mRNA expression in human ileum organoids treated for 24 h with solvent (0.1% DMSO) or the indicated ligands (RIF and FDN at 10 μM; EE2 at 3 μM). Results were obtained from three separate experiments performed in quadruplicate. h–k Data were analyzed by two-way ANOVA with multiple comparisons and are expressed as mean ± SD. E2 17β-estradiol, EE2 17α-ethinylestradiol, END endosulfan, FDN furanodienone, PCN pregnenolone-16a carbonitrile, RIF rifampicin. Source data are provided in the Source Data file.
