RT Journal Article
SR Electronic
T1 Role of Constitutive Androstane Receptor in Toll-Like Receptor-Mediated Regulation of Gene Expression of Hepatic Drug-Metabolizing Enzymes and Transporters
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 172
OP 181
DO 10.1124/dmd.113.053850
VO 42
IS 1
A1 Pranav Shah
A1 Tao Guo
A1 David D. Moore
A1 Romi Ghose
YR 2014
UL http://dmd.aspetjournals.org/content/42/1/172.abstract
AB Impairment of drug disposition in the liver during inflammation has been attributed to downregulation of gene expression of drug-metabolizing enzymes (DMEs) and drug transporters. Inflammatory responses in the liver are primarily mediated by Toll-like receptors (TLRs). We have recently shown that activation of TLR2 or TLR4 by lipoteichoic acid (LTA) and lipopolysaccharide (LPS), respectively, leads to the downregulation of gene expression of DMEs/transporters. However, the molecular mechanism underlying this downregulation is not fully understood. The xenobiotic nuclear receptors, pregnane X receptor (PXR) and constitutive androstane receptor (CAR), regulate the expression of DMEs/transporter genes. Downregulation of DMEs/transporters by LTA or LPS was associated with reduced expression of PXR and CAR genes. To determine the role of CAR, we injected CAR+/+ and CAR−/− mice with LTA or LPS, which significantly downregulated (∼40%–60%) RNA levels of the DMEs, cytochrome P450 (Cyp)3a11, Cyp2a4, Cyp2b10, uridine diphosphate glucuronosyltransferase 1a1, amine N-sulfotransferase, and the transporter, multidrug resistance-associated protein 2, in CAR+/+ mice. Suppression of most of these genes was attenuated in LTA-treated CAR−/− mice. In contrast, LPS-mediated downregulation of these genes was not attenuated in CAR−/− mice. Induction of these genes by mouse CAR activator 1,4-bis-[2-(3,5-dichloropyridyloxy)]benzene was sustained in LTA- but not in LPS-treated mice. Similar observations were obtained in humanized CAR mice. We have replicated these results in primary hepatocytes as well. Thus, LPS can downregulate DME/transporter genes in the absence of CAR, whereas the effect of LTA on these genes is attenuated in the absence of CAR, indicating the potential involvement of CAR in LTA-mediated downregulation of DME/transporter genes.