NR AXKP
AU Corsaro,A.; Thellung,S.; Villa,V.; Raggi,F.; Chiovitti,K.; D'Arrigo,C.; Russo,C.; Perico,A.; Aceto,A.; Florio,T.
TI Identification of a Mild-Denatured Monomer as the Neurotoxic Isoform of Human PrP 90-231 (hPrP90-231)
QU International Conference - Prion 2007 (26.-28.9.2007) Edinburgh International Conference Centre, Edinburgh, Scotland, UK - Book of Abstracts: Protein Misfolding P01.52
IA http://www.prion2007.com/pdf/Prion Book of Abstracts.pdf
PT Konferenz-Poster
AB
Background: The identification of the PrP conformer responsible of the neurotoxic events during prion disease is critical for developing effective therapeutic strategies against prion diseases. Because of its high tendency to aggregate, the major difficulties in the understanding the cytotoxic structure of the PrP are largely due to its heterogeneous nature which often consists of a mixture of monomers, fibrils and nonfibrillar oligomeric species. Previous studies indicated that either soluble oligomeric species or amyloid fibrils, generated from the full-length PrP and a variety of its fragments, are cytotoxic. However, in spite of numerous investigations, to date, the relationship between toxicity and structural state of the protein still remains uncertain.
Objective: The aim of the present study was the identification of the cytotoxic conformations of hPrP90-231, as well as the understanding of the molecular mechanisms by which it may cause neuronal death.
Result: We demonstrate that a mild-denaturated monomer of the human PrP fragment 90-231 (hPrP90-231, incubated for 1h at 53°), represents the unique toxic PrP specie for SH-SY5Y neuroblastoma cells. When thermal treatment is further prolonged (3 or 5 days of incubation at 37°), the protein becomes structured in macro-aggregates and fibrils. Their addition to the culture medium does not determine reduction of cellular viability, similarly to what observed with the native hPrP90-231. Thus, neither the native state nor macro-aggregates but only the mild-denatured monomers possess cytotoxic effects. Using spectroscopic and immunocytochemical techniques we demonstrate that this toxic conformer is characterized by a higher exposure of hydrophobic regions that favors the cellular uptake of the protein and the formation of insoluble PrP aggregates that trigger pro-apoptotic "cell death" signals.
Conclusion: Our results indicate that the toxic conformers of hPrP90-231 are constituted by monomers and/or small oligomers characterized by a high content of ß structures and by an increased exposure of hydrophobic regions.
AD A. Corsaro, S. Thellung, V. Villa, F. Raggi, T. Florio, University of Genova Section of Pharmacology, Dept. Oncology Biology and Genetics, Italy; K. Chiovitti, A. Aceto, University G. D'Annunzio of Chieti, Dept. Biomedical Sciences, Section of Biochemistry, Italy; C. D'Arrigo, A. Perico, Institute for Macromolecular Studies-Division of Genova (ISMac-CNR), Italy; C. Russo, University of Molise, Dept. Health Sciences, Italy
SP englisch
PO Schottland