Redox mechanisms and their pathological role in prion diseases: The road to ruin

Prion diseases, also known as transmissible spongiform encephalopathies, are rare, progressive, and fatal neurodegenerative disorders, which are caused by the accumulation of the misfolded cellular prion protein (PrPC). The resulting cytotoxic prion species, referred to as the scrapie prion isoform (PrPSc), assemble in aggregates and interfere with neuronal pathways, ultimately rendering neurons dysfunctional. As the prion protein physiologically interacts with redox-active metals, an altered redox balance within the cell can impact these interactions, which may lead to and facilitate further misfolding and aggregation. The initiation of misfolding and the aggregation processes will, in turn, induce microglial activation and neuroinflammation, which leads to an imbalance in cellular redox homeostasis and enhanced redox stress. Potential approaches for therapeutics target redox signalling, and this review illustrates the pathways involved in the above processes.