Differential regulation of CYP3A4 promoter activity by a new class of natural product derivatives binding to pregnane X receptor.
The pregnane X receptor (PXR) regulates drug metabolism by regulating the expression of drug-metabolizing enzymes such as cytochrome P450 3A4 (CYP3A4), which is involved in the metabolism of >50% of clinically prescribed drugs. The activity of PXR can be controlled by the binding of small molecule agonists or antagonists. Because of its unique ligand binding pocket, PXR binds promiscuously to structurally diverse chemicals. To study the structure-activity relationship, novel modulators for PXR are needed. Here we report the virtual screening of ∼25,000 natural product derivatives from the ZINC database using the Molecular Operating Environment docking software tool against the PXR-rifampicin complex X-ray crystal structure. Our screening resulted in identification of compounds based on the lowest S score, which measures Gibbs free energy. Interestingly, we found that the compounds that bind directly to PXR, as revealed in an intrinsic tryptophan fluorescence assay, modulate CYP3A4 promoter activity differentially in HepG2 cells. Mutational analysis and docking studies showed that these compounds bind broadly in the ligand binding pocket but interact with different amino acid residues. We further investigated the mechanism of binding by analyzing the functional groups that are important for distinguishing agonists from antagonists. The approach we used to identify novel modulators that bind to PXR can be useful for finding novel modulators of PXR.
Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA.
Monimoy
M
Banerjee
Taosheng
T
Chen
D001665:Binding Sites; D001688:Biological Products / Q000737:chemistry* / Q000494:pharmacology; D002460:Cell Line; D051544:Cytochrome P-450 CYP3A / Q000235:genetics* / Q000378:metabolism; D062126:Databases, Chemical; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D017930:Genes, Reporter; D056945:Hep G2 Cells; D057166:High-Throughput Screening Assays; D006801:Humans; D008156:Luciferases; D062105:Molecular Docking Simulation; D000077297:Pregnane X Receptor; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011987:Receptors, Steroid / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
D001688:Biological Products; D000077297:Pregnane X Receptor; D011987:Receptors, Steroid; D011994:Recombinant Proteins; D008156:Luciferases; D051544:Cytochrome P-450 CYP3A; C510163:CYP3A4 protein, human
Drug metabolism; Molecular docking; Natural product derivative; PXR