Prion disease tempo determined by host-dependent substrate reduction
Charles E. Mays, … , David Westaway, Jiri G. Safar
Charles E. Mays, … , David Westaway, Jiri G. Safar
Published January 16, 2014
Citation Information: J Clin Invest. 2014;124(2):847-858. https://doi.org/10.1172/JCI72241.
View: Text | PDF
Research Article Neuroscience

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.

Authors

Charles E. Mays, Chae Kim, Tracy Haldiman, Jacques van der Merwe, Agnes Lau, Jing Yang, Jennifer Grams, Michele A. Di Bari, Romolo Nonno, Glenn C. Telling, Qingzhong Kong, Jan Langeveld, Debbie McKenzie, David Westaway, Jiri G. Safar

×

Figure 7

PrPC downregulation examined in cell culture models and by PMCA.

Options: View larger image (or click on image) Download as PowerPoint
PrPC downregulation examined in cell culture models and by PMCA. (A) W...
(A) Western blot analysis was used to show PK sensitivity of cell lysates derived from uninfected N2a, ScN2a (chronically infected with RML scrapie prions), uninfected RK13 Elk21–, and RKE21+ (chronically infected with elk CWD prions). (B) CDI was used to evaluate the relative downregulation of PrPC in these cell lines. (C) Western blot analysis was used to show PK sensitivity of RK13 cells stably expressing either PrPC-A or PrPC-B following exposure to RML prions. (D) CDI was applied to quantify the PrPC levels in RK13 cells stably expressing PrPC-A following treatment with healthy (square) or RML-infected brain material (circle). Normal RK13 cells treated with RML-infected brain material (box with circle) were used as a control. (E) PrPSc replication rate was evaluated using double PMCA titrations to assess the effect of decreasing PrPC input and titrated amounts of PrPSc “seed” from mouse-adapted RML prions. The columns and data points and error bars represent average ± SEM measured in triplicate. **P < 0.01, ***P < 0.001, determined by ANOVA.