NR AOZD
AU Simoneau,S.; Wopfner,F.; Rezaei,H.; Grosclaude,J.; Schätzl,H.M.; Lasmezas,C.I.
TI Differential neuronal toxicity of discrete forms of PrP revealed in vitro
QU International Conference - Prion diseases: from basic research to intervention concepts - TSE-Forum, 08.10.-10.10.2003, Gasteig, München - Poster session - BR-93
PT Konferenz-Poster
AB The mechanisms of neuronal toxicity linked to the accumulation of pathogenic prion protein (called PrPres as opposed to the cellular form PrPc) are still unresolved. Model peptides encompassing mainly the hydrophobic domain of PrP have hitherto evidenced two possible mechanisms, one of them depending on membrane expressed PrPc, the other on the destabilizing insertion of the peptide into the membrane. Recent experiments suggest that the conversion of PrP from an alpha-helical protease-sensitive to a beta-sheeted protease-resistant form requires the formation of a dimeric PrP intermediate (Jansen et al. Biol. Chem. 2001). We wanted to investigate which forms of the full-length prion protein constitute the neurotoxic entities during prion diseases. To this purpose, embryonic cortical neurons originating from normal and PrP knockout mice were exposed to several preparations of recombinant prion proteins including i) recombinant mouse PrP, sheep PrP either in a mainly a-helical conformation or in a "ß-sheeted" form and ii) a covalently-linked PrP dimer (mainly a-helical). Cell viability was measured using an MTT test. We found that both "ß-sheeted" or dimeric PrP exerted significant toxicity on pure primary cortical neurons while a-helical monomeric PrP was not toxic (sheep) or less toxic than the dimer (mouse). Both exhibited a neurotoxic effect at a concentration of 3 µM compared with 100 µM for the neurotoxic peptide PrP105-132. Investigation of the mechanisms involved show that the dimer is internalized, that toxicity is independent of the presence of endogenous PrP, and that it can be counteracted with heparan sulfate mimetics (Adjou et al. JGV Direct 2003) or a monoclonal antibody directed against amino acids 106-126 of PrP. The data presented in this study suggest that the toxicity of prion proteins be linked to enhanced penetration into the cell due to enhanced bulk positive charge (dimer) or hydrophobicity (ß-sheeted PrP) and that the hydrophobic PrP106-126 domain is required for this toxicity.
AD S. Simoneau, C.I. Lasmézas, Laboratory for Prion Pathogenesis, Atomic Energy Commission, Fontenay-aux-Roses, France; F. Wopfner, H.M. Schätzl, Institute of Virology, Technical University of Munich, Germany; H. Rezaei, J. Grosclaude, Virologie et Immunologie Moléculaires, INRA, Jouy-en-Josas, France
SP englisch
PO Deutschland