title: Molecular cloning and characterization of the murine bile salt export pump.
abstract: Hepatic bile salt secretion and bile formation are essential functions of the mammalian liver, and the rate-limiting step of hepatocellular secretion of bile salts is canalicular secretion. Recently, the rat sister-of-p-glycoprotein/bile salt export pump (spgp/BSEP) was demonstrated to encode for the rat ATP-dependent canalicular bile salt export protein, and mutations of human BSEP were identified as the cause of PFIC 2. Since mouse models are vital for studies in hepatocellular transport and metabolism, cloning and characterization of the murine gene are essential. In this study, we have cloned a full-length, functional cDNA for the mBsep. The deduced amino acid sequence encodes for a 1321-amino-acid protein and is 94% similar to rat and 89% similar to human bsep. Western immunoblotting using an antibody directed against a carboxy-terminal peptide of mbsep protein reveals a 160kDa protein, which is highly enriched in mouse canalicular membranes. Transfection of mBSEP into Sf-9 insect cells or mammalian Balb-3T3 cells confers functional transport of the bile salt taurocholate. The mBsep mRNA is expressed in murine liver, but not in other tissues. Hepatic mBsep levels appear highly regulated, being markedly diminished in both LPS and estrogen models of cholestasis. These data are important for further murine studies of hepatocellular transport physiology and metabolism.
authors.affiliation: Section of Digestive and Liver Diseases, University of Illinois at Chicago College of Medicine and Chicago Veteran's Administration Medical Center, Westside Division, 840 S. Wood St. (M/C) 787, Chicago, IL 60612, USA. rmgreen@uic.edu
authors.forename: R M
authors.initials: RM
authors.lastname: Green
authors.forename: F
authors.initials: F
authors.lastname: Hoda
authors.forename: K L
authors.initials: KL
authors.lastname: Ward
mesh_terms: D016475:3T3 Cells; D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002756:Cholagogues and Choleretics / Q000493:pharmacokinetics; D002779:Cholestasis / Q000378:metabolism; D003001:Cloning, Molecular; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D051381:Rats; D017386:Sequence Homology, Amino Acid; D013656:Taurocholic Acid / Q000493:pharmacokinetics; D014162:Transfection
chemical_list: C093491:ABCB11 protein, human; D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters; C490549:Abcb11 protein, mouse; C490548:Abcb11 protein, rat; D002756:Cholagogues and Choleretics; D013656:Taurocholic Acid