title: Chelerythrine stimulates GSH transport by rat Mrp2 (Abcc2) expressed in canine kidney cells.
abstract: Rat multidrug resistant protein 2 (Mrp2; Abcc2), an ATP-driven pump located on the canalicular domain of hepatocytes, exports glutathione S-conjugates (GS-X) and GSH among its wide variety of substrates. Previous studies have shown that chelerythrine (CHEL), a quaternary benzophenanthridine cation, reacts with GSH to form a reversible adduct under physiological conditions. Here we report that CHEL can strongly stimulate GSH efflux by Mrp2, when it is constitutively expressed in polarized canine kidney cells, thereby leading to the depletion of cellular GSH. Transepithelial transport experiments indicate that Mrp2 transports GSH and CHEL with a 1:1 stoichiometry, which can be readily inhibited by GS-bimane, a GS-X substrate for Mrp2. Moreover, CHEL can block Mrp2-mediated leukotriene C4 uptake by membrane vesicles with an IC50 approximately 100 microM in the presence of GSH, but not S-methyl GSH or ophthalmic acid. Thus the thiol group of GSH is required for inhibition of Mrp2 in the presence of CHEL. Our results suggest that CHEL stimulates GSH efflux by forming a reversible GS-CHEL adduct, which is transported by Mrp2 and dissociates extracellularly.
authors.affiliation: Research Center for Liver Diseases, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
authors.forename: Huan
authors.initials: H
authors.lastname: Lou
authors.forename: Murad
authors.initials: M
authors.lastname: Ookhtens
authors.forename: Andrew
authors.initials: A
authors.lastname: Stolz
authors.forename: Neil
authors.initials: N
authors.lastname: Kaplowitz
mesh_terms: D000470:Alkaloids; D000818:Animals; D053119:Benzophenanthridines; D001692:Biological Transport / Q000187:drug effects; D001643:Bridged Bicyclo Compounds / Q000493:pharmacokinetics / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D004285:Dogs; D005978:Glutathione / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D007700:Kinetics; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism*; D010617:Phenanthridines / Q000493:pharmacokinetics / Q000494:pharmacology*; D051381:Rats; D013438:Sulfhydryl Compounds / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology
chemical_list: D000470:Alkaloids; D053119:Benzophenanthridines; D001643:Bridged Bicyclo Compounds; D002121:Calcium Channel Blockers; D005978:Glutathione; D026901:Membrane Transport Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D010617:Phenanthridines; D013438:Sulfhydryl Compounds; D014700:Verapamil; C080120:glutathione-bimane; C016299:chelerythrine