Dmd055178 796..802

Sulfotransferase (SULT) 2A1 catalyzes sulfonation of drugs and endogenous compounds and plays an important role in xenobiotic metabolism as well as in the maintenance of steroid and lipid homeostasis. A recent study showed that 17b-estradiol (E2) increases the mRNA levels of SULT2A1 in human hepatocytes. Here we report the underlying molecular mechanisms. E2 enhanced SULT2A1 expression in human hepatocytes and HepG2-ER cells (HepG2 stably expressing ERa). SULT2A1 induction by E2 was abrogated by antiestrogen ICI 182,780, indicating a key role of ERa in the induction. Results from deletion and mutation assays of SULT2A1 promoter revealed three cis-elements located within –257/+140 region of SULT2A1 that are potentially responsible for the induction. Chromatin immunoprecipitation assay verified the recruitment of ERa to the promoter region. Electrophoretic mobility shift assays revealed that AP-1 proteins bind to one of the ciselements. Interestingly, SULT2A1 promoter assays using ERa mutants revealed that the DNA-binding domain of ERa is indispensable for SULT2A1 induction by E2, suggesting that direct ERa binding to the SULT2A1 promoter is also necessary for the induction. Taken together, our results indicate that E2 enhances SULT2A1 expression by both the classical and nonclassical mechanisms of ERa action.