title: Essential role of the prion protein N terminus in subcellular trafficking and half-life of cellular prion protein.
abstract: Aberrant metabolism and conformational alterations of the cellular prion protein (PrP(c)) are the underlying causes of transmissible spongiform encephalopathies in humans and animals. In cells, PrP(c) is modified post-translationally and transported along the secretory pathway to the plasma membrane, where it is attached to the cell surface by a glycosylphosphatidylinositol anchor. In surface biotinylation assays we observed that deletions within the unstructured N terminus of murine PrP(c) led to a significant reduction of internalization of PrP after transfection of murine neuroblastoma cells. Truncation of the entire N terminus most significantly inhibited internalization of PrP(c). The same deletions caused a significant prolongation of cellular half-life of PrP(c) and a delay in the transport through the secretory pathway to the cell surface. There was no difference in the glycosylation kinetics, indicating that all PrP constructs equally passed endoplasmic reticulum-based cellular quality control. Addition of the N terminus of the Xenopus laevis PrP, which does not encode a copper-binding repeat element, to N-terminally truncated mouse PrP restored the wild type phenotype. These results provide deeper insight into the life cycle of the PrP(c), raising the novel possibility of a targeting function of its N-proximal part by interacting with the secretory and the endocytic machinery. They also indicate the conservation of this targeting property in evolution.
authors.affiliation: Gene Center Munich, Max von Pettenkofer Institute for Virology, Faculty of Medicine, Ludwig-Maximilians-University, Feodor-Lynen-Strasse 25, D-81377 Munich, Germany.
authors.forename: Max
authors.initials: M
authors.lastname: Nunziante
authors.forename: Sabine
authors.initials: S
authors.lastname: Gilch
authors.forename: Hermann M
authors.initials: HM
authors.lastname: Schätzl
mesh_terms: D000818:Animals; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D006207:Half-Life; D007700:Kinetics; D051379:Mice; D010641:Phenotype; D018621:PrPC Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*; D021381:Protein Transport; D013347:Subcellular Fractions / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014982:Xenopus laevis
chemical_list: D017261:Glycosylphosphatidylinositols; D018621:PrPC Proteins