title: Use of comprehensive screening methods to detect selective human CAR activators.
abstract: The so-called human xenosensors, constitutive androstane receptor (hCAR), pregnane X receptor (hPXR) and aryl hydrocarbon receptor (hAhR), participate in drug metabolism and transport as well as in several endogenous processes by regulating the expression of their target genes. While the ligand specificities for hPXR and hAhR are relatively well described, this property of hCAR still remains fairly unclear. Identifying hCAR agonists for drug development and for studying hCAR biology are hindered mainly by the unique properties of the receptor, such as the high constitutive activity and complex signaling network but also by the lack of robust and reliable assays and cellular models. Here, validated reporter assays for these three xenosensors are presented and thereafter used to screen a large set of chemicals in order to find novel selective hCAR ligands. We introduce a novel selective hCAR agonist, FL81, which can be used as a stable positive control in hCAR activity assays. Our established receptor-selective ligand identification methods consisting of supporting biological assays and molecular modeling techniques are then used to study FL81 as well as other discovered ligands, such as diethylstilbestrol, o,p'-DDT, methoxychlor and permethrin, for their ability to specifically activate hCAR and to regulate the CYP enzyme expression and function.
authors.affiliation: University of Eastern Finland, School of Pharmacy and Biocenter Kuopio, Yliopistonranta 1C, FI-70211 Kuopio, Finland. Jenni.Kublbeck@uef.fi
authors.forename: Jenni
authors.initials: J
authors.lastname: Küblbeck
authors.forename: Tuomo
authors.initials: T
authors.lastname: Laitinen
authors.forename: Johanna
authors.initials: J
authors.lastname: Jyrkkärinne
authors.forename: Timo
authors.initials: T
authors.lastname: Rousu
authors.forename: Ari
authors.initials: A
authors.lastname: Tolonen
authors.forename: Tobias
authors.initials: T
authors.lastname: Abel
authors.forename: Tanja
authors.initials: T
authors.lastname: Kortelainen
authors.forename: Jouko
authors.initials: J
authors.lastname: Uusitalo
authors.forename: Timo
authors.initials: T
authors.lastname: Korjamo
authors.forename: Paavo
authors.initials: P
authors.lastname: Honkakoski
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Molnár
mesh_terms: D051792:Basic Helix-Loop-Helix Proteins / Q000819:agonists*; D045744:Cell Line, Tumor; D000090702:Constitutive Androstane Receptor; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D015394:Molecular Structure; D000077297:Pregnane X Receptor; D011485:Protein Binding; D018336:Receptors, Aryl Hydrocarbon / Q000819:agonists*; D018160:Receptors, Cytoplasmic and Nuclear / Q000819:agonists*; D011987:Receptors, Steroid / Q000819:agonists*; D015203:Reproducibility of Results; D054852:Small Molecule Libraries
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D000090702:Constitutive Androstane Receptor; D003577:Cytochrome P-450 Enzyme System; D000077297:Pregnane X Receptor; D018336:Receptors, Aryl Hydrocarbon; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D054852:Small Molecule Libraries; C111235:AHR protein, human