Excitotoxicity through NMDA receptors mediates cerebellar granule neuron apoptosis induced by prion protein 90-231 fragment

Thellung, S., Gatta, E., Pellistri, F., Corsaro, A., Villa, V., Vassalli, M. , Robello, M. and Florio, T. (2013) Excitotoxicity through NMDA receptors mediates cerebellar granule neuron apoptosis induced by prion protein 90-231 fragment. Neurotoxicity Research, 23, pp. 301-314. (doi: 10.1007/s12640-012-9340-9) (PMID:22855343)

Abstract

Prion diseases recognize, as a unique molecular trait, the misfolding of CNS-enriched prion protein (PrPC) into an aberrant isoform (PrPSc). In this work, we characterize the in vitro toxicity of amino-terminally truncated recombinant PrP fragment (amino acids 90-231, PrP90-231), on rat cerebellar granule neurons (CGN), focusing on glutamatergic receptor activation and Ca2+ homeostasis impairment. This recombinant fragment assumes a toxic conformation (PrP90-231TOX) after controlled thermal denaturation (1 h at 53 °C) acquiring structural characteristics identified in PrPSc (enrichment in β-structures, increased hydrophobicity, partial resistance to proteinase K, and aggregation in amyloid fibrils). By annexin-V binding assay, and evaluation of the percentage of fragmented and condensed nuclei, we show that treatment with PrP90-231TOX, used in pre-fibrillar aggregation state, induces CGN apoptosis. This effect was associated with a delayed, but sustained elevation of [Ca2+]i. Both CGN apoptosis and [Ca2+]i increase were not observed using PrP90-231 in PrPC-like conformation. PrP90-231TOX effects were significantly reduced in the presence of ionotropic glutamate receptor antagonists. In particular, CGN apoptosis and [Ca2+]i increase were largely reduced, although not fully abolished, by pre-treatment with the NMDA antagonists APV and memantine, while the AMPA antagonist CNQX produced a lower, although still significant, effect. In conclusion, we report that CGN apoptosis induced by PrP90-231TOX correlates with a sustained elevation of [Ca2+]i mediated by the activation of NMDA and AMPA receptors.

• Item Type: Articles
• Additional Information: This study has been supported by grants from Italian Ministry of University and Research (MIUR-PRIN 2008, and Accordi di Programma FIRB, Project No. RBAP11HSZS, 2011).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Vassalli, Professor Massimo
• Authors: Thellung, S., Gatta, E., Pellistri, F., Corsaro, A., Villa, V., Vassalli, M., Robello, M., and Florio, T.
• College/School: College of Science and Engineering > School of Engineering > Biomedical Engineering
• Journal Name: Neurotoxicity Research
• Publisher: Springer
• ISSN: 1029-8428
• ISSN (Online): 1476-3524
• Published Online: 02 August 2012