Glycosylation of PrPC determines timing of neuroinvasion and targeting in the brain following transmissible spongiform encephalopathy infection by a peripheral route.

The Roslin Institute and R(D)SVS University of Edinburgh, Roslin, Midlothian EH25 9PS, Scotland, United Kingdom.
Journal of Virology (Impact Factor: 4.65). 04/2010; 84(7):3464-75. DOI: 10.1128/JVI.02374-09
Source: PubMed

ABSTRACT Transmissible spongiform encephalopathy (TSE) infectivity naturally spreads from site of entry in the periphery to the central nervous system where pathological lesions are formed. Several routes and cells within the host have been identified as important for facilitating the infectious process. Expression of the glycoprotein cellular PrP (PrP(C)) is considered a key factor for replication of infectivity in the central nervous system (CNS) and its transport to the brain, and it has been suggested that the infectious agent propagates from cell to cell via a domino-like effect. However, precisely how this is achieved and what involvement the different glycoforms of PrP have in these processes remain to be determined. To address this issue, we have used our unique models of gene-targeted transgenic mice expressing different glycosylated forms of PrP. Two TSE strains were inoculated intraperitoneally into these mice to assess the contribution of diglycosylated, monoglycosylated, and unglycosylated PrP in spreading of infectivity to the brain. This study demonstrates that glycosylation of host PrP has a profound effect in determining the outcome of disease. Lack of diglycosylated PrP slowed or prevented disease onset after peripheral challenge, suggesting an important role for fully glycosylated PrP in either the replication of the infectious agent in the periphery or its transport to the CNS. Moreover, mice expressing unglycosylated PrP did not develop clinical disease, and mice expressing monoglycosylated PrP showed strikingly different neuropathologic features compared to those expressing diglycosylated PrP. This demonstrates that targeting in the brain following peripheral inoculation is profoundly influenced by the glycosylation status of host PrP.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Prion diseases are characterized by tissue accumulation of a misfolded, β-sheet enriched, isoform (PrPSc) of the cellular prion protein (PrPC). At variance with PrPC, PrPSc shows a partial resistance to protease digestion, and forms highly aggregated and detergent-insoluble polymers, two properties that have been consistently used to distinguish the two proteins. In recent years, however, the idea that PrPSc itself comprises heterogeneous species has grown. Most importantly, a putative PK-sensitive form of PrPSc (sPrPSc) is being increasingly investigated for its possible role in prion infectivity, neurotoxicity, and strain variability. The study of sPrPSc, however, remains technically challenging because of the need of separating it from PrPC without using proteases. In this study we have systematically analyzed both PK-resistance and aggregation state of purified PrPSc across the whole spectrum of the currently characterized human prion strains. The results show that PrPSc isolates manifest significant strain-specific differences in their PK digestion profile that are only partially explained by differences in the size of aggregates, suggesting that other factors, likely acting on PrPSc aggregate stability, determine its resistance to proteolysis. Fully protease-sensitive low molecular weight aggregates were detected in all isolates but in a limited proportion of the overall PrPSc (i.e., <10%), which argue against a significant role of slow-sedimenting PK-sensitive PrPSc in the biogenesis of prion strains. Finally, we highlight the limitations of current operational definitions of sPrPSc and of the quantitative analytical measurements that are not based on the isolation of a fully PK-sensitive PrPSc form.
    Journal of Biological Chemistry 07/2013; 288(39). DOI:10.1074/jbc.M113.477547 · 4.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Creutzfeldt-Jakob disease (CJD) is a heterogenic neurodegenerative disorder associated with abnormal post-translational processing of cellular prion protein (PrPc). CJD displays distinctive clinical and pathological features which correlate with the genotype at the codon 129 (methionine or valine: M or V respectively)) in the prion protein gene and with size of the protease-resistant core of the abnormal prion protein PrPsc (type 1: 20/21 kDa and type 2: 19 kDa). MM1 and VV2 are the most common sporadic CJD (sCJD) subtypes. PrP mRNA expression levels in the frontal cortex and cerebellum are reduced in sCJD in a form subtype-dependent. Total PrP protein levels and PrPsc levels in the frontal cortex and cerebellum accumulate differentially in sCJD MM1 and sCJD VV2 with no relation between PrPsc deposition and spongiform degeneration and neuron loss, but with microgliosis, and IL6 and TNF-α response. In the CSF, reduced PrPc, the only form present in this compartment, occurs in sCJD MM1 and VV2. PrP mRNA expression is also reduced in the frontal cortex in advanced stages of Alzheimer disease, Lewy body disease, progressive supranuclear palsy and frontotemporal lobe degeneration, but PrPc levels in brain varies from one disease to another. Reduced PrPc levels in CSF correlate with PrP mRNA expression in brain, which in turn reflects severity of degeneration in sCJD.
    Prion 09/2013; 7(5). DOI:10.4161/pri.26416 · 1.97 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A novel thermolysin digestion method for the molecular strain-typing of ruminant TSEs has been developed which resulted in the clearance of cellular prion protein (PrP C) from healthy sheep or cattle brain homogenates, while digestion of scrapie or BSE infected samples resulted in the generation of the full-length disease-related isoform, PrP Sc . Using antibodies against the amino terminal region of PrP it was possible to distinguish ovine scrapie from ovine BSE, permitting the potential identification of BSE infected sheep within the UK flock. The identification of a disease-associated, endogenously-generated fragment of PrP (termed C2) in scrapie infected sheep is also described. Absent in healthy brain homogenates, the neuroanatomical distribution of both C2 fragments and thermolysin-resistant PrP Sc permitted the classification of four groups within a sample of natural scrapie cases which may be representative of scrapie strain heterogeneity in the UK.

Full-text (2 Sources)

Available from
May 27, 2014