Regulation of xenobiotic and bile acid metabolism by the nuclear pregnane X receptor.
The nuclear pregnane X receptor (PXR; NR1I2) is an integral component of the body's defense mechanism against chemical insult (chemoprotection). PXR is activated by a diverse array of lipophilic chemicals, including xenobiotics and endogenous substances, and regulates the expression of cytochromes P450, conjugating enzymes, and transporters involved in the metabolism and elimination of these potentially harmful chemicals from the body. Among the chemicals that bind and activate PXR is the toxic bile acid lithocholic acid; activation of PXR, in turn, protects against the severe liver damage caused by this bile acid.Thus, PXR serves as a physiological sensor of lithocholic acid and perhaps other bile acids and coordinately regulates genes involved in their detoxification. Interestingly, both the antibiotic rifampicin and the herbal antidepressant St. John's wort activate PXR and have anticholestatic properties, which suggests that more potent, selective PXR agonists may be useful in the treatment of biliary cholestasis or other diseases characterized by the accumulation of bile acids or other toxins in the liver.
Kliewer
Steven A
SA
Nuclear Receptor Discovery Research, GlaxoSmithKline, 5 Moore Drive, Room V118.1B, Research Triangle Park, NC 27709, USA. sak15922@gsk.com
Willson
Timothy M
TM
D000818:Animals; D001189:Aryl Hydrocarbon Hydroxylases; D001647:Bile Acids and Salts / Q000378:metabolism*; D051544:Cytochrome P-450 CYP3A; D003577:Cytochrome P-450 Enzyme System / Q000502:physiology; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D010089:Oxidoreductases, N-Demethylating / Q000502:physiology; D000077297:Pregnane X Receptor; D018160:Receptors, Cytoplasmic and Nuclear / Q000502:physiology*; D011987:Receptors, Steroid / Q000502:physiology*; D013045:Species Specificity; D015262:Xenobiotics / Q000378:metabolism*
D001647:Bile Acids and Salts; C000625852:NR1I2 protein, human; D000077297:Pregnane X Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D015262:Xenobiotics; D003577:Cytochrome P-450 Enzyme System; D001189:Aryl Hydrocarbon Hydroxylases; D051544:Cytochrome P-450 CYP3A; D010089:Oxidoreductases, N-Demethylating