Glycoform-Selective Prion Formation in Sporadic and Familial Forms of Prion Disease

Xiangzhu Xiao,Qingzhong Kong,Tetsuyuki Kitamoto,Jean-Louis Laplanche,Jean-Philippe Brandel,Yian Zhan,Ignazio Cali,Baiya Li,Jue Yuan,Brian A Cobb,Wen-Quan Zou,Stéphane Haïk,Hubert Laude,Mohammed Moudjou,Robert B Petersen,Pierluigi Gambetti,Jan Langeveld

doi:10.1371/journal.pone.0058786

Abstract

The four glycoforms of the cellular prion protein (PrPC) variably glycosylated at the two N-linked glycosylation sites are converted into their pathological forms (PrPSc) in most cases of sporadic prion diseases. However, a prominent molecular characteristic of PrPSc in the recently identified variably protease-sensitive prionopathy (VPSPr) is the absence of a diglycosylated form, also notable in familial Creutzfeldt-Jakob disease (fCJD), which is linked to mutations in PrP either from Val to Ile at residue 180 (fCJDV180I) or from Thr to Ala at residue 183 (fCJDT183A). Here we report that fCJDV180I, but not fCJDT183A, exhibits a proteinase K (PK)-resistant PrP (PrPres) that is markedly similar to that observed in VPSPr, which exhibits a five-step ladder-like electrophoretic profile, a molecular hallmark of VPSPr. Remarkably, the absence of the diglycosylated PrPres species in both fCJDV180I and VPSPr is likewise attributable to the absence of PrPres glycosylated at the first N-linked glycosylation site at residue 181, as in fCJDT183A. In contrast to fCJDT183A, both VPSPr and fCJDV180I exhibit glycosylation at residue 181 on di- and monoglycosylated (mono181) PrP prior to PK-treatment. Furthermore, PrPV180I with a typical glycoform profile from cultured cells generates detectable PrPres that also contains the diglycosylated PrP in addition to mono- and unglycosylated forms upon PK-treatment. Taken together, our current in vivo and in vitro studies indicate that sporadic VPSPr and familial CJDV180I share a unique glycoform-selective prion formation pathway in which the conversion of diglycosylated and mono181 PrPC to PrPSc is inhibited, probably by a dominant-negative effect, or by other co-factors.

Highlights

Prion diseases are a group of fatal transmissible spongiform encephalopathies affecting both animals and humans
Using a combination of in vivo and in vitro assays, our current study indicates that the absence of the diglycosylated PrPSc in both variably protease-sensitive prionopathy (VPSPr) and fCJDV180I results from a glycoform-selective prion formation pathway associated with the inability of the diand mono-glycosylated PrPC at N-linked glycosylation site at residue 181 (N181) to convert into PrPSc in the brain
In contrast to sporadic CJD (sCJD), both fCJDV180I and VPSPr exhibit monoand un-glycosylated proteinase K (PK)-resistant PrP bands but virtually no diglycosylated PrP when probed with the 3F4 antibody (Fig. 1A)

Summary

Introduction

Prion diseases are a group of fatal transmissible spongiform encephalopathies affecting both animals and humans. Human prion diseases are highly heterogeneous: They can be inherited, sporadic, or acquired, and include various forms of CreutzfeldtJakob disease (CJD), Gerstmann-Straussler-Scheinker (GSS) disease, fatal insomnia, and kuru. K (PK)-resistant PrP27–30 (PrPres) is the molecular hallmark of all human prion diseases. All but one are associated generally with PrP mutations showing different PrP banding patterns, as in GSS and familial CJD. GSS is characterized by the presence of additional small PK-resistant PrP fragments, whereas fCJD linked to either PrPT183A or PrPV180I mutations exhibits a PrPres that lacks the diglycosylated PrP species [2,3,4]

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Conclusion