title: Liver X receptor regulates expression of MRP2 but not that of MDR1 and BCRP in the liver.
abstract: Liver X receptors (LXRs) belong to the nuclear hormone receptor superfamily. Multidrug resistance-associated protein 2 (MRP2), multidrug resistance 1 (MDR1) and breast cancer resistance protein (BCRP) play an important role in the efflux of a broad range of endogenous and xenobiotic compounds from hepatocytes. Since the effects of LXR activation on there transporters have been obscure, we investigated the effects of LXR agonists, TO901317 and 25-hydroxycholesterol, on MRP2, MDR1, BCRP expression in HepG2 cells and the rat liver. In an in vitro study, TO901317 increased ABCA1, an LXR target gene, and MRP2 mRNA and protein levels. On the other hand, TO901317 had little effect on MDR1 and BCRP mRNA levels. In an in vivo study, Abca1 and Mrp2 mRNA and protein levels were increased by TO901317, but TO901317 had no effect on Mdr1a and Bcrp mRNA levels in the rat liver. Moreover, TO901317-induced MRP2 mRNA expression was blocked by LXRalpha knockdown. In this study, we demonstrated that LXR activation induced expression of MRP2 but not that of MDR1 and BCRP in hepatocytes. The results suggest that agonists for LXR activate transcription of the MRP2 gene in order to promote excretion of endogenous and xenobiotic compounds from hepatocytes into bile.
authors.affiliation: Laboratory of Clinical Pharmaceutics and Therapeutics, Division of Pharmasciences, Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-12-jo, Nishi-6-chome, Kita-ku, Sapporo 060-0812, Japan.
authors.forename: Ikumi
authors.initials: I
authors.lastname: Chisaki
authors.forename: Masaki
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Shirou
authors.initials: S
authors.lastname: Itagaki
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hirano
authors.forename: Ken
authors.initials: K
authors.lastname: Iseki
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000235:genetics* / Q000378:metabolism; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D049109:Cell Proliferation; D005786:Gene Expression Regulation; D056945:Hep G2 Cells; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000494:pharmacology; D006888:Hydroxycholesterols / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D008099:Liver / Q000378:metabolism*; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D000071518:Liver X Receptors; D008297:Male; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics* / Q000378:metabolism; D057093:Orphan Nuclear Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013449:Sulfonamides / Q000494:pharmacology; D014162:Transfection; D005466:Fluorocarbons; D000096926:Benzenesulfonamides
chemical_list: D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000070997:ATP Binding Cassette Transporter, Subfamily G, Member 2; D018528:ATP-Binding Cassette Transporters; D006845:Hydrocarbons, Fluorinated; D006888:Hydroxycholesterols; D000071518:Liver X Receptors; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D009363:Neoplasm Proteins; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D013449:Sulfonamides; C513055:ABCB1 protein, human; C000715087:ABCC2 protein, human; C116614:ABCG2 protein, human; C000605213:NR1H3 protein, human; C000605215:Nr1h3 protein, rat; C423915:T0901317; D005466:Fluorocarbons; D000096926:Benzenesulfonamides; C007997:25-hydroxycholesterol