Leveraging the dominant-negative effect of the kuru-protective G127V prion protein variant as a novel therapeutic...

Prion diseases are fatal neurodegenerative disorders with no approved therapies that halt or reverse disease progression. Given that cellular prion protein (PrP^C) expression is required for prion propagation and neurotoxicity, reducing its expression is a promising therapeutic strategy. However, complete PrP ablation, as seen in knockout models that do not artifactually upregulate the adjacent Doppel gene, causes subtle developmental and behavioral abnormalities, leaving the long-term safety profile of PrP^C reduction in humans incompletely resolved. Here, we explore a complementary strategy that harnesses the dominant-negative effect of the naturally protective G127V PrP variant found in kuru-resistant individuals in Papua New Guinea. In CAD5 cell lines, we demonstrate that inducible expression of G126V PrP (the mouse equivalent of human G127V) along with WT PrP prevents and suppresses prion infection in a dose-dependent manner. Extending this approach to CAD5 cells that express bank vole PrP, we further show that the protective effect of G127V spans a wide range of naturally and artificially derived prion strains, highlighting the generality of the dominant-negative approach. We also demonstrate that this dominant-negative effect can be recapitulated in primary cultures of cerebellar astrocytes. Remarkably, prion resistance persists even after G126V expression had ceased, indicating a sustained protective effect that could obviate the need for continuous transgene expression in a therapeutic setting. Finally, we find that anchorless, recombinant G127V PrP retains a potent dominant-negative activity, suggesting the use of this protein as a biological therapeutic. Together, these findings define a framework for development of G127V, a naturally protective and evolutionarily selected PrP variant, as a therapeutic agent to treat or prevent prion diseases.