title: Impaired uptake of conjugated bile acids and hepatitis b virus pres1-binding in na(+) -taurocholate cotransporting polypeptide knockout mice.
abstract: The Na(+) -taurocholate cotransporting polypeptide (NTCP) mediates uptake of conjugated bile acids (BAs) and is localized at the basolateral membrane of hepatocytes. It has recently been recognized as the receptor mediating hepatocyte-specific entry of hepatitis B virus and hepatitis delta virus. Myrcludex B, a peptide inhibitor of hepatitis B virus entry, is assumed to specifically target NTCP. Here, we investigated BA transport and Myrcludex B binding in the first Slc10a1-knockout mouse model (Slc10a1 encodes NTCP). Primary Slc10a1(-/-) hepatocytes showed absence of sodium-dependent taurocholic acid uptake, whereas sodium-independent taurocholic acid uptake was unchanged. In vivo, this was manifested as a decreased serum BA clearance in all knockout mice. In a subset of mice, NTCP deficiency resulted in markedly elevated total serum BA concentrations, mainly composed of conjugated BAs. The hypercholanemic phenotype was rapidly triggered by a diet supplemented with ursodeoxycholic acid. Biliary BA output remained intact, while fecal BA excretion was reduced in hypercholanemic Slc10a1(-/-) mice, explained by increased Asbt and Ostα/β expression. These mice further showed reduced Asbt expression in the kidney and increased renal BA excretion. Hepatic uptake of conjugated BAs was potentially affected by down-regulation of OATP1A1 and up-regulation of OATP1A4. Furthermore, sodium-dependent taurocholic acid uptake was inhibited by Myrcludex B in wild-type hepatocytes, while Slc10a1(-/-) hepatocytes were insensitive to Myrcludex B. Finally, positron emission tomography showed a complete abrogation of hepatic binding of labeled Myrcludex B in Slc10a1(-/-) mice.
  
  
  CONCLUSIONS
  The Slc10a1-knockout mouse model supports the central role of NTCP in hepatic uptake of conjugated BAs and hepatitis B virus preS1/Myrcludex B binding in vivo; the NTCP-independent hepatic BA uptake machinery maintains a (slower) enterohepatic circulation of BAs, although it is occasionally insufficient to clear BAs from the circulation.
authors: Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, AMC, Amsterdam, The Netherlands.
authors: Davor
authors: D
authors: Slijepcevic
authors: Department of Infectious Diseases and of Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany.|Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors: Christina
authors: C
authors: Kaufman
authors: Department of Molecular Cancer Research, Section of Metabolic Diseases, University Medical Center Utrecht, Utrecht, The Netherlands.
authors: Catharina G K
authors: CG
authors: Wichers
authors: Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, AMC, Amsterdam, The Netherlands.
authors: Eduardo H
authors: EH
authors: Gilglioni
authors: Department of Infectious Diseases and of Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany.
authors: Florian A
authors: FA
authors: Lempp
authors: Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, AMC, Amsterdam, The Netherlands.
authors: Suzanne
authors: S
authors: Duijst
authors: Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, AMC, Amsterdam, The Netherlands.
authors: Dirk R
authors: DR
authors: de Waart
authors: Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, AMC, Amsterdam, The Netherlands.
authors: Ronald P J Oude
authors: RP
authors: Elferink
authors: Department of Nuclear Medicine, University Hospital Heidelberg, Heidelberg, Germany.
authors: Walter
authors: W
authors: Mier
authors: Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, Zurich, Switzerland.
authors: Bruno
authors: B
authors: Stieger
authors: Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, AMC, Amsterdam, The Netherlands.
authors: Ulrich
authors: U
authors: Beuers
authors: Department of Infectious Diseases and of Molecular Virology, University Hospital Heidelberg, Heidelberg, Germany.|German Center for Infection Research, Heidelberg University, Heidelberg, Germany.
authors: Stephan
authors: S
authors: Urban
authors: Tytgat Institute for Liver and Intestinal Research and Department of Gastroenterology and Hepatology, AMC, Amsterdam, The Netherlands.
authors: Stan F J
authors: SF
authors: van de Graaf
mesh_terms: D000818:Animals; D001646:Bile / Q000737:chemistry; D005243:Feces / Q000737:chemistry; D005260:Female; D006515:Hepatitis B virus / Q000378:metabolism*; D055666:Lipopeptides; D008099:Liver / Q000378:metabolism*; D008297:Male; D018345:Mice, Knockout; D029363:Organic Anion Transporters, Sodium-Dependent / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D013656:Taurocholic Acid / Q000097:blood* / Q000652:urine; D014580:Ursodeoxycholic Acid; D014759:Viral Envelope Proteins / Q000378:metabolism*
chemical_list: C096362:L protein, hepatitis B virus; D055666:Lipopeptides; D029363:Organic Anion Transporters, Sodium-Dependent; D027981:Symporters; D014759:Viral Envelope Proteins; C571888:myrcludex-B; C071908:sodium-bile acid cotransporter; D013656:Taurocholic Acid; D014580:Ursodeoxycholic Acid
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