title: ABCG5 and ABCG8 are expressed in gallbladder epithelial cells.
abstract: Gallbladder epithelial cells (GBEC) are exposed to high biliary cholesterol concentrations on their apical (AP) surface. The mechanisms of cholesterol absorption and efflux by these cells are not known. We hypothesized that ABCG5 and ABCG8 are expressed in GBEC and mediate AP cholesterol efflux. Human gallbladder cDNA expressed message for ABCG5 and ABCG8. Cultured murine GBEC also expressed abcg5 and abcg8 mRNA and protein, as did cultured canine GBEC. Interestingly, treatment with model bile containing supersaturating concentrations of cholesterol, or treatment with LXRalpha/RXR ligands, did not lead to differences in expression of ABCG5 or ABCG8 in the murine or the canine cells. The subcellular localization of ABCG5 and ABCG8 did show alterations, with predominantly intracellular localization at baseline and predominantly AP localization following treatment with model bile or LXRalpha ligand. GBEC therefore express ABCG5 and ABCG8; these sterol transporters may play a role in mediating AP cholesterol efflux in the gallbladder epithelium.
authors.affiliation: Division of Gastroenterology, University of Washington School of Medicine, Box 356424, 1959 NE Pacific St., Seattle, WA 98195, USA.
authors.forename: Aimee
authors.initials: A
authors.lastname: Tauscher
authors.forename: Rahul
authors.initials: R
authors.lastname: Kuver
mesh_terms: D064286:ATP Binding Cassette Transporter 1; D000071018:ATP Binding Cassette Transporter, Subfamily G, Member 5; D000071019:ATP Binding Cassette Transporter, Subfamily G, Member 8; D018528:ATP-Binding Cassette Transporters / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D001646:Bile; D016764:Cell Polarity; D002478:Cells, Cultured; D004268:DNA-Binding Proteins; D004285:Dogs; D004847:Epithelial Cells / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D005704:Gallbladder / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D008024:Ligands; D008074:Lipoproteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D000071518:Liver X Receptors; D051379:Mice; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger / Q000096:biosynthesis; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D018168:Receptors, Retinoic Acid / Q000378:metabolism; D047488:Retinoid X Receptors; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: C416945:ABCG5 protein, human; C462600:ABCG5 protein, mouse; C416946:ABCG8 protein, human; C462601:ABCG8 protein, mouse; D064286:ATP Binding Cassette Transporter 1; D000071018:ATP Binding Cassette Transporter, Subfamily G, Member 5; D000071019:ATP Binding Cassette Transporter, Subfamily G, Member 8; D018528:ATP-Binding Cassette Transporters; D004268:DNA-Binding Proteins; D008024:Ligands; D008074:Lipoproteins; D000071518:Liver X Receptors; C000605213:NR1H3 protein, human; C000605214:Nr1h3 protein, mouse; D057093:Orphan Nuclear Receptors; D012333:RNA, Messenger; D018160:Receptors, Cytoplasmic and Nuclear; D018168:Receptors, Retinoic Acid; D047488:Retinoid X Receptors; D014157:Transcription Factors