Thienyl Pyrimidine Derivatives with PrPSc Oligomer-Inducing Activity are a Promising Tool to Study Prions

Transmissible spongiform encephalopathies (TSEs), also called prion diseases, are fatal, infectious, genetic or sporadic neurodegenerative disorders of humans and animals. In humans, TSEs are represented by Creutzfeldt-Jakob disease (CJD), Gerstmann-Straussler-Scheinker syndrome, Fatal Familial Insomnia and Kuru. In animals, the most prominent prion diseases are scrapie of sheep and goats, bovine spongiform encephalopathy (BSE) of cattle and chronic wasting disease (CWD) of deer and elk. A critical event in prion diseases is the accumulation in the central nervous system (CNS) of the abnormally folded PrPSc protein that is the protease-resistant isoform of a normal cellular protein encoded by the host and called PrPC. PrPSc (also known as rPrPSc or PrP27-30) represents the main marker of prion diseases and is routinely used in the reference method for the diagnosis of prion diseases. Most of the therapeutic strategies developed so far aimed at identifying compounds that diminish the levels of PrPSc, with variable success when tested in vivo. In this review, we present an alternative approach in which small molecules that induce PrPSc oligomers are identified. By using virtual and cellular screenings, we found several thienyl pyrimidine compounds that trigger PrPSc oligomerization and trap prion infectivity.