Protease-Sensitive Conformers in Broad Spectrum of Distinct PrPSc Structures in Sporadic Creutzfeldt-Jakob Disease Are Indicator of Progression Rate

Abstract

The origin, range, and structure of prions causing the most common human prion disease, sporadic Creutzfeldt-Jakob disease (sCJD), are largely unknown. To investigate the molecular mechanism responsible for the broad phenotypic variability of sCJD, we analyzed the conformational characteristics of protease-sensitive and protease-resistant fractions of the pathogenic prion protein (PrPSc) using novel conformational methods derived from a conformation-dependent immunoassay (CDI). In 46 brains of patients homozygous for polymorphisms in the PRNP gene and exhibiting either Type 1 or Type 2 western blot pattern of the PrPSc, we identified an extensive array of PrPSc structures that differ in protease sensitivity, display of critical domains, and conformational stability. Surprisingly, in sCJD cases homozygous for methionine or valine at codon 129 of the PRNP gene, the concentration and stability of protease-sensitive conformers of PrPSc correlated with progression rate of the disease. These data indicate that sCJD brains exhibit a wide spectrum of PrPSc structural states, and accordingly argue for a broad spectrum of prion strains coding for different phenotypes. The link between disease duration, levels, and stability of protease-sensitive conformers of PrPSc suggests that these conformers play an important role in the pathogenesis of sCJD.

Prion Infectivity Plateaus and Conversion to Symptomatic Disease Originate from Falling Precursor Levels and Increased Levels of Oligomeric PrP Sc Species

“…The validation of CDI has been reported by the authors and other laboratories (9)(10)(11)(12)(13)(14)(15)(16)(17)(18). Here, we utilized the recently modified protocol that adapts CDI to murine samples (5).…”

Prion disease tempo determined by host-dependent substrate reduction

“…The calibration and validation aspect of CDI has been reported on extensively by us and others (5,14,15,(56)(57)(58)(59)(60)(61)(62). Briefly, the PK-untreated sample containing PrP is divided into native and denatured aliquot, and the later is denatured with 4 M Gdn HCl for 5 minutes at 80°C.…”

“…The separate calibration for the PK-treated and untreated sample is critical for correct results due to the approximately 3.5-fold lower affinity of mAb 3F4 with denatured full-length human PrP(23-231, 129M) compared to PrP(90-231, 129M) (14,56).…”

Analysis of Conformational Stability of Abnormal Prion Protein Aggregates across the Spectrum of Creutzfeldt-Jakob Disease Prions

“…In particular, a systematic analysis of the conformational stability of PrP Sc aggregates across the spectrum of human prions is still lacking. Previous studies focused on the comparison between sCJD subtypes MM1 and MM2 (31)(32)(33) or between variant CJD (vCJD) and the most common sCJD type MM1 (34). Furthermore, only the unfolding induced by GdnHCl was addressed, whereas the thermostability of PrP Sc has never been explored in CJD.…”