Regulation of sulfotransferase enzymes by prototypical microsomal enzyme inducers in mice

In the present study, the regulation of the mRNA of 11 sulfotransferases (Sults) and two 3'-phosphoadenosine 5'-phosphosulfate synthase (PAPSs) isozymes by 15 microsomal enzyme inducers (MEI) in livers of male mice and five MEIs in livers of female mice was examined. These MEIs represent the transcriptionally mediated pathways: aryl hydrocarbon receptor (AhR), pregnane X receptor (PXR), constitutive androstane receptor (CAR), peroxisomal proliferator-activated receptor alpha (PPAR alpha), and NF-E2-related factor 2 (Nrf2). AhR ligands suppress the expression of Sults, especially the Sult1 isoenzymes in female mice. CAR activators up-regulate several Sults and PAPSs2 in female but not in male mice. PXR ligands cause marked induction of Sult1e1 in male, Sult2a1/2a2 in female, and PAPSs2 in both male and female mice. PPAR alpha ligands do not have a marked effect on Sult expression in males, but they tend to suppress the expression of several Sult isoforms in female mice. Nrf2 activators appear to induce the mRNA expression of Sults in male and have mixed effects in female mice. In silico analysis indicated the presence of putative binding sites for all five transcription factors in the promoter region of many Sult and PAPSs isoforms. In conclusion, induction of Sults by typical MEIs is not as marked as the induction of P450 enzymes in mice. In addition to gender differences in basal expression of Sults, there is also a marked gender difference in the inducibility of various Sult isoenzymes in mice by MEIs.