1)The search for anti-prion compounds has been encouraged by the fact that transmissible spongiform encephalopathies (TSEs) share molecular mechanisms with more prevalent neurodegenerative pathologies, such as Parkinson's and Alzheimer's diseases. Cellular prion protein conversion into protease-resistant forms (PrPRes or PrPSc) is a critical step in the development of TSEs, thus being one of the main targets in the screening for anti-prion compounds. In this work, three trimethoxychalcones (J1, J8, J20) and one oxadiazole (Y17), previously identified in vitro as potential anti-prion compounds, were evaluated through different approaches in order to gain inferences about their mechanism of action. None of them changed PrPC expression in N2a cells as shown by real-time RT-PCR. Among them, J8 and Y17 were effective in RT-QuIC reactions using mouse rPrP23231 as substrate and PrPSc seeds from mouse and human brain. However, when rPrP90231, which lacks the N-terminal domain, was used as substrate, only J8 remained effective, indicating that this region is important for Y17 activity, while J8 seems to interact with the globular domain of PrP. Furthermore, these compounds prompted the cellular internalization of this protein. In agreement with RT-QuIC results, a PrP fibrillation assay showed that these two compounds delayed PrP conversion into the amyloid form and also reduced the fibril content. Based on these results, we hypothesize that J8 and Y17 may act as multi-target ligands, since their efficacy is attributed not only to the conversion inhibition, but also to cellular effects. 2) We and our collaborators have tested the anti-scrapie effects of select anti-PrP oligonucleotides. Both prophylactic and post-exposure treatments of mice inoculated with scrapie are ongoing.
