Quiescin-sulfhydryl oxidase inhibits prion formation in vitro.

Yi-An Zhan,Gong-Xiang Wang,Qingzhong Kong,Manuel Camacho Martinez,Shizhong Bu,Robert B Petersen,Jan Steyaert,Zerui Wang,Liang Zeng,Sylvain Lehmann,Alexandre Wohlkonig,Jacqueline Mikol,Wen-Quan Zou,Yu Li,Johnny Dang,Li Cui,Romany Abskharon,Jue Yuan

doi:10.18632/aging.101132

Abstract

Prions are infectious proteins that cause a group of fatal transmissible diseases in animals and humans. The scrapie isoform (PrPSc) of the cellular prion protein (PrPC) is the only known component of the prion. Several lines of evidence have suggested that the formation and molecular features of PrPSc are associated with an abnormal unfolding/refolding process. Quiescin-sulfhydryl oxidase (QSOX) plays a role in protein folding by introducing disulfides into unfolded reduced proteins. Here we report that QSOX inhibits human prion propagation in protein misfolding cyclic amplification reactions and murine prion propagation in scrapie-infected neuroblastoma cells. Moreover, QSOX preferentially binds PrPSc from prion-infected human or animal brains, but not PrPC from uninfected brains. Surface plasmon resonance of the recombinant mouse PrP (moPrP) demonstrates that the affinity of QSOX for monomer is significantly lower than that for octamer (312 nM vs 1.7 nM). QSOX exhibits much lower affinity for N-terminally truncated moPrP (PrP89-230) than for the full-length moPrP (PrP23-231) (312 nM vs 2 nM), suggesting that the N-terminal region of PrP is critical for the interaction of PrP with QSOX. Our study indicates that QSOX may play a role in prion formation, which may open new therapeutic avenues for treating prion diseases.

Highlights

Prions cause a group of fatal transmissible neurodegenerative disorders including CreutzfeldtJakob disease (CJD) in humans, scrapie in sheep and goats, bovine spongiform encephalopathy (BSE) in cattle, and chronic wasting disease (CWD) in deer and elk
To determine whether Quiescin‐sulfhydryl oxidase (QSOX) and PrPSc or QSOX and PrPC interact, we incubated brain homogenates from sCJD or non-CJD patients with QSOX conjugated to magnetic beads. g5p- and OCD4- conjugated beads were used as positive controls while protein disulfide isomerase (PDI)-conjugated beads were used as a negative control
No PrP was captured by QSOX-beads from non-CJD in either untreated or Proteinase K (PK)-treated samples

Summary

Introduction

Prions cause a group of fatal transmissible neurodegenerative disorders including CreutzfeldtJakob disease (CJD) in humans, scrapie in sheep and goats, bovine spongiform encephalopathy (BSE) in cattle, and chronic wasting disease (CWD) in deer and elk. A misfolded prion protein (PrPSc) is the only known component of the infectious pathogens. PrPSc is derived from the cellular prion protein (PrPC). The key molecular event in the pathogenesis of all prion diseases is the conversion of PrPC into PrPSc. The molecular conversion is believed to result from an abnormal unfolding/refolding process that can be triggered by mutations, seeding by exogenous PrPSc or for unknown reasons. The mechanism underlying the conversion remains unclear

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Results

Conclusion