Probing the chemistry and conformational change underlying autocatalytic selfpropagation of misfolded prion protein
2009: 2 years / Grant: 54 000 euros
Project: The objective of PrioGrasp project was to enrich our knowledge about conversion and aggregation phenomenon in prion diseases. In particular, it was proposed to determine which cofactors were involved in prion replication and to decipher their exact role. This project was based on previous studies showing that heparan sulfates, glycosamino glycanes, small RNA, metal ions were involved in PrPC conversion into PrPTSE and were able to improve PMCA amplification of PrPTSE.
Main results and related published data: First of all the adaptation of the PMCA method was
performed in the laboratory. Of note,Fourier transform infrared (FT-IR)spectroscopical monitoring of
structuralchangesshowed conformational alterationsin hamsterscrapie progenyseeds,suggesting
modification of the strains characteristics. However, this could be partially reversed when PMCA
products were reinoculated into the original host species.
Severalcompounds were also tested for their effect on the seeding activity of PrP using 263K hamster scrapie prions. Metal ions (Fe, Mn, Zn, Cu), chelating agent such as EDTA, RNA digesting enzyme (Benzonase) were tested. EDTA was shown to increase the PMCA amplification in a concentration dependant way. Fe2+, Fe3+, Zn2+ seemed to decrease the amplification, while nothing happened with Cu2+ and Mn2+. RNA cofactor enhancer was recently confirmed in a collaborative work with experiments reporting that the benzonase PMCA inhibitory effect could be reversed by adding RNA purified from scrapie-associated fibril (SAF) preparations. These small RNAs purified from SAF, when coupled with recombinant PrP were also capable to induce scrapie in hamster.