Transcriptional Regulation of Human UDP-Glucuronosyltransferase 2B10 by Farnesoid X Receptor in Human Hepatoma HepG2 Cells. 
Little is known about transcriptional regulators of UDP-glucuronosyltransferase 2B10 (UGT2B10), an enzyme known to glucuronidate many chemicals and drugs such as nicotine and tricyclic antidepressants.  Here, we uncovered that UGT2B10 was transcriptionally regulated by farnesoid X receptor (FXR), the bile acid sensing nuclear receptor.  GW4064 and chenodeoxycholic acid (two specific FXR agonists) treatment of HepG2 cells led to a significant increase in the mRNA level of UGT2B10.  The treated cells also showed enhanced glucuronidation activities toward amitriptyline (an UGT2B10 probe substrate).  In reporter gene assays, the extent of UGT2B10 activation by the FXR agonists was positively correlated with the amount of cotransfected FXR.  Consistently, knockdown of FXR by shRNA attenuated the induction effect on UGT2B10 expression.  Furthermore, a combination of electrophoretic mobility shift assay and chromatin immunoprecipitation showed that the FXR receptor trans-activated UGT2B10 through its specific binding to the -209- to -197-bp region (an IR1 element) of the UGT2B10 promoter.  In summary, our results for the first time established FXR as a transcriptional regulator of human UGT2B10.