Influence of Mabs on PrPSc Formation Using In Vitro and Cell-Free Systems

Binggong Chang,Robert Petersen,Richard Rubenstein,Thomas Wisniewski

doi:10.1371/journal.pone.0041626

Binggong Chang, Robert Petersen + Show 2 more

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https://doi.org/10.1371/journal.pone.0041626

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Abstract

PrPSc is believed to serve as a template for the conversion of PrPC to the abnormal isoform. This process requires contact between the two proteins and implies that there may be critical contact sites that are important for conversion. We hypothesized that antibodies binding to either PrPcor PrPSc would hinder or prevent the formation of the PrPC–PrPSc complex and thus slow down or prevent the conversion process. Two systems were used to analyze the effect of different antibodies on PrPSc formation: (i) neuroblastoma cells persistently infected with the 22L mouse-adapted scrapie stain, and (ii) protein misfolding cyclic amplification (PMCA), which uses PrPSc as a template or seed, and a series of incubations and sonications, to convert PrPC to PrPSc. The two systems yielded similar results, in most cases, and demonstrate that PrP-specific monoclonal antibodies (Mabs) vary in their ability to inhibit the PrPC–PrPSc conversion process. Based on the numerous and varied Mabs analyzed, the inhibitory effect does not appear to be epitope specific, related to PrPC conformation, or to cell membrane localization, but is influenced by the targeted PrP region (amino vs carboxy).

Highlights

Prion diseases are a group of fatal neurodegenerative disorders that are associated with conformational conversion of the cellular prion protein, PrPC, which is mainly a-helical with very few beta sheets, into a b-sheet-rich form, PrPSc [1,2,3,4,5]
The mechanism by which PrPC is converted to the abnormal isoform is still not clear, but it is presumed to involve a PrPC–PrPSc complex, with the latter serving as a conformational template [6]
PrPSc serves as a template that binds to PrPC and produces a conformational conversion into the abnormal isoform

Summary

Introduction

Prion diseases are a group of fatal neurodegenerative disorders that are associated with conformational conversion of the cellular prion protein, PrPC, which is mainly a-helical with very few beta sheets, into a b-sheet-rich form, PrPSc [1,2,3,4,5]. The mechanism by which PrPC is converted to the abnormal isoform is still not clear, but it is presumed to involve a PrPC–PrPSc complex, with the latter serving as a conformational template [6]. PrPSc serves as a template that binds to PrPC and produces a conformational conversion into the abnormal isoform This raises the issue of whether there are critical contact sites that mediate conversion. If this is the case, interfering with or blocking complex formation should prevent the PrPC to PrPSc conversion process. Previous reports have described anti-PrP antibodies that can stop or hinder the conversion process add reference 44 and renumber [7,8,9,10,11,12,13,14]

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