Visit our Expo - Redox and Inflammation signaling 2012

Session XII : Cell death and neurodegenerative diseases Poster XII, 25
Characterization of the pro-apoptotic intracellular mechanisms induced by a toxic
conformer of the recombinant human prion protein fragment 90-231
Valentina Villa1, Alessandro Corsaro1, Stefano Thellung1, Domenico Paludi2, Katia
Chiovitti3, Valentina Venezia1, Mario Nizzari1, Claudio Russo4, Gennaro Schettini1,
Antonio Aceto3 and Tullio Florio1
1Section of Pharmacology, Dept. Oncology Biology and Genetics, University of Genova,
Italy. 2Dept. Scienze degli Alimenti, Veterinary School, University of Teramo, Italy.
3Section of Biochemistry, Dept. Biomedical Sciences, University G. D’Annunzio of
Chieti, Italy. 4Dept. Health Sciences, University of Molise, Campobasso Italy.
Prion diseases comprise a group of fatal neurodegenerative disorders that affect both animals
and humans. The transition of the prion protein (PrP) from a mainly alpha structured isoform
(PrPC) to a prevalent beta sheet-containing protein (PrPSc) is believed to represent a major
pathogenetic mechanism in prion diseases. To investigate the linkage between PrP
neurotoxicity and its conformation, we used a recombinant prion protein fragment
corresponding to the amino acidic sequence 90-231 of human prion protein (hPrP90-231).
Using thermal denaturation, we set up an experimental model to induce the process of
conversion from PrPC to PrPSc .We report that partial thermal denaturation converts hPrP90-
231 into a beta sheet-rich isoform, displaying a temperature and time-dependent conversion
into oligomeric structures that share some physico-chemical characteristics with brain PrPSc.
SH-SY5Y cells were chosen to characterize the potential neurotoxic effect of hPrP90-231 in
its different structural conformations. We demonstrated that hPrP90-231 in beta
conformation, but not when alpha structured, powerfully affected the survival of this cells.
hPrP90-231 beta structured caused DNA fragmentation and a significant increase in caspase-3
proteolytic activity (maximal effects +170%), suggesting the occurrence of apoptotic cell
death. Finally we investigated the involvement of MAP kinases in the regulation of beta
hPrP90-231 dependent apoptosis. We observed that the p38 MAP kinase blocker SB203580
prevented the apoptotic cell death evoked by hPrP90-231 and Western blot analysis revealed
that the exposure of the cells to the peptide induced p38 phosphorylation. In conclusion, we
demonstrate that the hPrP90-231 pro-apoptotic activity is mediated by p38 and caspase-3
activation. (grants by MIUR PRIN 2004 and FIRB 2001 to TF)
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