title: N-Glycosylation of the Na+-Taurocholate Cotransporting Polypeptide (NTCP) Determines Its Trafficking and Stability and Is Required for Hepatitis B Virus Infection.
abstract: The sodium/bile acid cotransporter NTCP was recently identified as a receptor for hepatitis B virus (HBV). NTCP is glycosylated and the role of glycans in protein trafficking or viral receptor activity is not known. NTCP contains two N-linked glycosylation sites and asparagine amino acid residues N5 and N11 were mutated to a glutamine to generate NTCP with a single glycan (NTCP-N5Q or NTCP- N11Q) or no glycans (NTCP- N5,11Q). HepG2 cells expressing NTCP with a single glycan supported HBV infection at a comparable level to NTCP-WT. The physiological function of NTCP, the uptake of bile acids, was also not affected in cells expressing these single glycosylation variants, consistent with their trafficking to the plasma membrane. However, glycosylation-deficient NTCP (NTCP-N5,11Q) failed to support HBV infection, showed minimal cellular expression and was degraded in the lysosome. This affected the physiological bile acid transporter function of NTCP-N5,11Q in a similar fashion. In conclusion, N-glycosylation is required for efficient NTCP localization at the plasma membrane and subsequent HBV infection and these characteristics are preserved in NTCP carrying a single carbohydrate moiety.
authors.affiliation: Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Monique D
authors.initials: MD
authors.lastname: Appelman
authors.affiliation: Institute of Virology, Technische Universität München / Helmholtz Zentrum München, München, Germany.|Institute for Advanced Study, Technische Universität München, München, Germany.
authors.forename: Anindita
authors.initials: A
authors.lastname: Chakraborty
authors.affiliation: Institute of Virology, Technische Universität München / Helmholtz Zentrum München, München, Germany.|Institute for Advanced Study, Technische Universität München, München, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Protzer
authors.affiliation: Institute for Advanced Study, Technische Universität München, München, Germany.|Centre for Human Virology, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Jane A
authors.initials: JA
authors.lastname: McKeating
authors.affiliation: Tytgat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, the Netherlands.|Department of Gastroenterology and Hepatology, Academic Medical Center, Amsterdam, the Netherlands.
authors.forename: Stan F J
authors.identifier: http://orcid.org/0000-0003-4238-4359
authors.initials: SF
authors.lastname: van de Graaf
mesh_terms: D006031:Glycosylation; D056945:Hep G2 Cells; D006509:Hepatitis B / Q000378:metabolism* / Q000821:virology; D006515:Hepatitis B virus; D006801:Humans; D016297:Mutagenesis, Site-Directed; D029363:Organic Anion Transporters, Sodium-Dependent / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport / Q000502:physiology; D027981:Symporters / Q000235:genetics / Q000378:metabolism*
chemical_list: D029363:Organic Anion Transporters, Sodium-Dependent; D027981:Symporters; C071908:sodium-bile acid cotransporter