title: Role of CAR and PXR in xenobiotic sensing and metabolism.
abstract: BACKGROUND
  The xenobiotic detoxification system, which protects the human body from external chemicals, comprises drug-metabolizing enzymes and transporters whose expressions are regulated by pregnane X receptor (PXR) and the constitutive androstane receptor (CAR). The progress made in a large number of recent studies calls for a timely review to summarize and highlight these key discoveries.
  
  
  METHODS
  This review summarizes recent advances in elucidating the roles of PXR and CAR in the xenobiotic detoxification system. It also highlights the progress in understanding the regulation of PXR and CAR activity at the post-translational levels, as well as the structural basis for the regulation of these two xenobiotic sensors.
  
  
  CONCLUSIONS
  Future efforts are needed to discover novel agonists and antagonists with species and isoform selectivity, to systematically understand the regulation of PXR and CAR at multiple levels (transcriptional, post-transcriptional and post-translational levels) in response to xenobiotics exposure, and to solve the structures of the full-length receptors, which will be enabled by improved protein expression and purification techniques and approaches. In addition, more efforts will be needed to validate PXR and CAR as disease-related therapeutic targets and thus expand their roles as master xenobiotic sensors.
authors.affiliation: St. Jude Children's Research Hospital, Department of Chemical Biology and Therapeutics, 262 Danny Thomas Place, Memphis, TN 38105, USA.
authors.forename: Yue-Ming
authors.initials: YM
authors.lastname: Wang
authors.forename: Su Sien
authors.initials: SS
authors.lastname: Ong
authors.forename: Sergio C
authors.initials: SC
authors.lastname: Chai
authors.forename: Taosheng
authors.initials: T
authors.lastname: Chen
mesh_terms: D000818:Animals; D000090702:Constitutive Androstane Receptor; D004347:Drug Interactions; D005786:Gene Expression Regulation; D006801:Humans; D008658:Inactivation, Metabolic; D008024:Ligands; D023421:Models, Animal; D000077297:Pregnane X Receptor; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics / Q000378:metabolism*; D011987:Receptors, Steroid / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D015262:Xenobiotics / Q000378:metabolism*
chemical_list: D000090702:Constitutive Androstane Receptor; D008024:Ligands; D000077297:Pregnane X Receptor; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D015262:Xenobiotics