The Journal of Neuroscience, February 14, 2007, 27(7):1576-1583; doi:10.1523/JNEUROSCI.5145-06.2007
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Neurobiology of Disease
Neurotoxic and Gliotrophic Activity of a Synthetic Peptide Homologous to GerstmannSträusslerScheinker Disease Amyloid Protein
Luana Fioriti,1,2
Nadia Angeretti,1
Laura Colombo,1
Ada De Luigi,1
Alessio Colombo,1
Claudia Manzoni,1
Michela Morbin,3
Fabrizio Tagliavini,3
Mario Salmona,1
Roberto Chiesa,1,2 and
Gianluigi Forloni1
1Istituto di Ricerche Farmacologiche "Mario Negri," 20157 Milano, Italy, 2Dulbecco Telethon Institute, 20157 Milano, Italy, and 3Istituto Neurologico Nazionale "Carlo Besta," 20133 Milano, Italy
Correspondence should be addressed to Gianluigi Forloni, Department of Neuroscience, Istituto di Ricerche Farmacologiche "Mario Negri," Via Eritrea 63, 20157 Milano, Italy. Email: forloni{at}marionegri.it
Amyloid fibrils in GerstmannSträusslerScheinker (GSS) disease are composed of a fragment of the prion protein (PrP), the N and C termini of which correspond to ragged residues 8190 and 144153. A synthetic peptide spanning the sequence 82146 (PrP 82146) polymerizes into protease-resistant fibrils with the tinctorial properties of amyloid. We investigated the biological activity of PrP 82146 and of two nonamyloidogenic variants of PrP 82146 with scrambled amino acid sequence 106126 or 127146. Cortical neurons prepared from rat and mouse embryos were chronically exposed to the PrP 82146 peptides (1050 µM). PrP 82146 and the partially scrambled peptides induced neuronal death with a similar doseresponse pattern, indicating that neurotoxicity was independent of amyloid fibril formation. Neurotoxicity was significantly reduced by coadministration of an anti-oligomer antibody, suggesting that PrP 82146 oligomers are primarily responsible for triggering cell death. Neurons from PrP knock-out (Prnp0/0) mice were significantly less sensitive to PrP 82146 toxicity than neurons expressing PrP. The gliotrophic effect of PrP 82146 was determined by [methyl-3H]-thymidine incorporation in cultured astrocytes. Treatment with PrP 82146 stimulated [methyl-3H]-thymidine uptake 3.5-fold. This activity was significantly less when the 106126 or 127146 regions were disrupted, indicating that PrP 82146 amyloid activates the gliotrophic response. Prnp0/0 astrocytes were insensitive to the proliferative stimulus of PrP 82146. These results underline the role of cerebral accumulation of abnormally folded PrP fragments and indicate that cellular PrP governs the pathogenic process.
Key words: prion; amyloid; apoptosis; neuron; astrocytes; neurotoxicity
Received Sept. 22, 2006;
revised Dec. 22, 2006;
accepted Dec. 24, 2006.
Correspondence should be addressed to Gianluigi Forloni, Department of Neuroscience, Istituto di Ricerche Farmacologiche "Mario Negri," Via Eritrea 63, 20157 Milano, Italy. Email: forloni{at}marionegri.it
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