title: Inhibition of complex glycosylation increases the formation of PrPsc.
abstract: N-linked glycans with complex structure have a major role in the biological activity of a wide variety of cell surface and secreted glycoproteins. Here, we show that geldanamycin, an inhibitor of Hsp90, interferes with the formation of complex glycosylated mammalian prion protein (PrPC). Similarly to inhibitors of alpha-mannosidases, geldanamycin stabilized a high mannose PrPC glycoform and prevented the subsequent processing into complex structures. Moreover, a PrP/Grp94 complex could be isolated from geldanamycin-treated cells, suggesting that Grp94 might play a role in the processing of PrPC in the endoplasmic reticulum. Inhibition of complex glycosylation did not interfere with the glycosylphosphatidylinositol (GPI) anchor attachment and cellular trafficking of high mannose PrPC to the outer leaflet of the plasma membrane. In scrapie-infected neuroblastoma cells, however, high mannose PrPC glycoforms were preferred substrates for the formation of PrP-scrapie (PrPSc). Our study reveals that complex glycosylation is dispensable for the cellular trafficking of PrPC, but modulates the formation of PrPSc.
authors.affiliation: Department of Cellular Biochemistry, Max-Planck-Institute for Biochemistry, 82152 Martinsried, Germany.
authors.forename: Konstanze F
authors.initials: KF
authors.lastname: Winklhofer
authors.forename: Ulrich
authors.initials: U
authors.lastname: Heller
authors.forename: Anja
authors.initials: A
authors.lastname: Reintjes
authors.forename: Jörg
authors.initials: J
authors.lastname: Tatzelt
mesh_terms: D000818:Animals; D016227:Benzoquinones; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006031:Glycosylation / Q000187:drug effects; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D047029:Lactams, Macrocyclic; D008358:Mannose / Q000378:metabolism*; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D018620:PrPSc Proteins / Q000187:drug effects / Q000378:metabolism*; D011809:Quinones / Q000494:pharmacology
chemical_list: D016227:Benzoquinones; D004791:Enzyme Inhibitors; D018840:HSP70 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D008565:Membrane Proteins; D018620:PrPSc Proteins; D011809:Quinones; C018551:glucose-regulated proteins; D008358:Mannose; C001277:geldanamycin