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Updated: May 4, 2026
Protein Misfolding Cyclic Amplification of Prions
Published on: November 7, 2012
Prion disease tempo determined by host-dependent substrate reduction
Abstract:
The symptoms of prion infection can take years or decades to manifest following the initial exposure. Molecular markers of prion disease include accumulation of the misfolded prion protein (PrPSc), which is derived from its cellular precursor (PrPC), as well as downregulation of the PrP-like Shadoo (Sho) glycoprotein. Given the overlapping cellular environments for PrPC and Sho, we inferred that PrPC levels might also be altered as part of a host response during prion infection. Using rodent models, we found that, in addition to changes in PrPC glycosylation and proteolytic processing, net reductions in PrPC occur in a wide range of prion diseases, including sheep scrapie, human Creutzfeldt-Jakob disease, and cervid chronic wasting disease. The reduction in PrPC results in decreased prion replication, as measured by the protein misfolding cyclic amplification technique for generating PrPSc in vitro. While PrPC downregulation is not discernible in animals with unusually short incubation periods and high PrPC expression, slowly evolving prion infections exhibit downregulation of the PrPC substrate required for new PrPSc synthesis and as a receptor for pathogenic signaling. Our data reveal PrPC downregulation as a previously unappreciated element of disease pathogenesis that defines the extensive, presymptomatic period for many prion strains.
Insights
Prion diseases involve misfolded prion protein (PrPSc) accumulation. This study reveals that cellular prion protein (PrPC) reduction occurs in various prion infections, impacting disease progression and offering a new therapeutic target.
Area of Science:
- Neuroscience
- Molecular Biology
- Infectious Diseases
Background:
- Prion diseases are characterized by the accumulation of misfolded prion protein (PrPSc).
- The cellular precursor, PrPC, and Shadoo (Sho) glycoprotein share cellular environments, suggesting PrPC levels might also change during prion infection.
- Prion disease symptoms manifest years after exposure, indicating a long presymptomatic period.
Purpose of the Study:
- To investigate alterations in cellular prion protein (PrPC) levels during prion infection.
- To determine if PrPC reduction impacts prion replication and disease pathogenesis.
- To identify potential molecular markers and therapeutic targets for prion diseases.
Main Methods:
- Rodent models of prion infection were utilized.
- Changes in PrPC glycosylation and proteolytic processing were analyzed.
- Prion replication was measured using the protein misfolding cyclic amplification (PMCA) technique.
Main Results:
- Net reductions in PrPC were observed across various prion diseases, including sheep scrapie, human Creutzfeldt-Jakob disease, and cervid chronic wasting disease.
- Reduced PrPC levels correlated with decreased prion replication in vitro.
- PrPC downregulation was evident in slowly evolving prion infections, affecting PrPSc synthesis and pathogenic signaling.
Conclusions:
- PrPC downregulation is a significant, previously unrecognized factor in prion disease pathogenesis.
- Reduced PrPC levels contribute to the extended presymptomatic phase of prion infections.
- Targeting PrPC reduction may offer a novel therapeutic strategy for prion diseases.
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