TY - JOUR T1 - NRF2-independent regulation of CAR by the pro-oxidants cadmium and isothiocyanate in hUGT1 mice JF - Drug Metabolism and Disposition JO - Drug Metab Dispos DO - 10.1124/dmd.119.089508 SP - dmd.119.089508 AU - Miles Paszek AU - Robert H. Tukey Y1 - 2019/01/01 UR - http://dmd.aspetjournals.org/content/early/2019/11/08/dmd.119.089508.abstract N2 - Environmental toxicants such as heavy metals from contaminated water or soil and isothiocyanates (ITC) from dietary sources act as pro-oxidants by directly generating reactive oxygens species (ROS) or through depleting cellular antioxidants such as glutathione. Toxicants can alter drug metabolism and it was reported that CYP2B10 and UGT1A1 are induced by phenethyl isothiocyanate (PEITC) through the constitutive androstane receptor (CAR). The possibility that NRF2, the master regulator of the antioxidant response, could co-activate CAR was investigated in neonatal hUGT1/Nrf2-/- mice. Neonatal mice were treated with PEITC or cadmium (Cd2+) by oral gavage for two days. Both PEITC and Cd2+ induced UGT1A1 RNA and protein in intestinal tissues in both hUGT1/Nrf2+/- and hUGT1/Nrf2-/- neonates, indicating NRF2-independent regulation of UGT1A1. Increases in CYP2B10 RNA in intestinal tissues were observed following PEITC or Cd2+ exposure. Activation of intestinal CAR by Cd2+ exposure was directly assessed by nuclear fractionation and Western blot analyses at 0.5, 1, 2, and 4 hours after treatment in hUGT1 neonates and after 48 hours in hUGT1/Nrf2+/- and hUGT1/Nrf2-/- neonates. CAR localized to the nucleus independent of NRF2 48 hours after exposure. Substantial CAR localization to the nucleus occurred at the 2- and 4-hour time points, coinciding with a decrease in cytoplasmic ERK1/2 phosphorylation and a nuclear increase in P38/p-P38 content. This suggests a novel oxidative stress-MAPK-CAR axis exists with phenotypic consequences.SIGNIFICANCE STATEMENT Pro-oxidant toxicants can alter drug metabolism through activation of CAR, independent of the NRF2-KEAP1 signaling pathway. The changes in proteins associated with drug metabolism are likely mediated through an oxidative stress-MAPK-CAR axis that have been linked to increases in intestinal maturation ER -