title: LPS-induced downregulation of MRP2 and BSEP in human liver is due to a posttranscriptional process.
abstract: Endotoxin-induced cholestasis in rodents is caused by hepatic downregulation of transporters, including the basolateral Na+-dependent taurocholate transporter (ntcp) and the canalicular bile salt export pump (bsep) and multidrug resistance-associated protein 2 (mrp2). Details about the regulation of the human transporter proteins during this process are lacking. We used precision-cut human and rat liver slices to study the regulation of transporter expression during LPS-induced cholestasis. We investigated the effect of LPS on nitrate/nitrite and cytokine production in relation to the expression of inducible nitric oxide synthase, NTCP, BSEP, and MRP2 both at the level of mRNA with RT-PCR and protein using immunofluorescence microscopy. In liver slices from both species, LPS-induced expression of inducible nitric oxide synthase was detected within 1-3 h and remained increased over 24 h. In rat liver slices, this was accompanied by a significant decrease of rat ntcp and mrp2 mRNA levels, whereas bsep levels were not affected. These results are in line with previous in vivo studies and validate our liver slice technique. In LPS-treated human liver slices, NTCP mRNA was downregulated and showed an inverse correlation with the amounts of TNF-alpha and Il-1beta produced. In contrast, MRP2 and BSEP mRNA levels were not affected under these conditions. However, after 24-h LPS challenge, both proteins were virtually absent in human liver slices, whereas marker proteins remained detectable. In conclusion, we show that posttranscriptional mechanisms play a more prominent role in LPS-induced regulation of human MRP2 and BSEP compared with the rat transporter proteins.
authors.affiliation: Department Pharmacokinetics and Drug Delivery, University of Groningen, 9713 AV Groningen, The Netherlands. M.G.L.Elferink@farm.rug.nl
authors.forename: Marieke G L
authors.initials: MG
authors.lastname: Elferink
authors.forename: Peter
authors.initials: P
authors.lastname: Olinga
authors.forename: Annelies L
authors.initials: AL
authors.lastname: Draaisma
authors.forename: Marjolijn T
authors.initials: MT
authors.lastname: Merema
authors.forename: Klaas Nico
authors.initials: KN
authors.lastname: Faber
authors.forename: Maarten J H
authors.initials: MJ
authors.lastname: Slooff
authors.forename: Dirk K F
authors.initials: DK
authors.lastname: Meijer
authors.forename: Geny M M
authors.initials: GM
authors.lastname: Groothuis
mesh_terms: D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000818:Animals; D056486:Chemical and Drug Induced Liver Injury / Q000378:metabolism; D002648:Child; D015536:Down-Regulation; D005260:Female; D005455:Fluorescent Antibody Technique; D006801:Humans; D066298:In Vitro Techniques; D007375:Interleukin-1 / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008297:Male; D018613:Microscopy, Confocal; D024101:Mitochondrial Proteins / Q000378:metabolism*; D000089762:Multidrug Resistance-Associated Protein 2; D029363:Organic Anion Transporters, Sodium-Dependent / Q000235:genetics; D011499:Protein Processing, Post-Translational; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D012269:Ribosomal Proteins / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D027981:Symporters / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: C093491:ABCB11 protein, human; C000715087:ABCC2 protein, human; D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters; D007375:Interleukin-1; D008070:Lipopolysaccharides; C093947:MRP2 protein, S cerevisiae; D024101:Mitochondrial Proteins; D000089762:Multidrug Resistance-Associated Protein 2; D029363:Organic Anion Transporters, Sodium-Dependent; D012333:RNA, Messenger; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; D027981:Symporters; D014409:Tumor Necrosis Factor-alpha; C071908:sodium-bile acid cotransporter