Domain-Specific Activation of Death-Associated Intracellular Signalling Cascades by the Cellular Prion Protein in Neuroblastoma Cells
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The biological functions of the cellular prion protein remain poorly understood. In fact, numerous studies have aimed to determine specific functions for the different protein domains. Studies of cellular prion protein (PrPC) domains through in vivo expression of molecules carrying internal deletions in a mouse Prnp null background have provided helpful data on the implication of the protein in signalling cascades in affected neurons. Nevertheless, understanding of the mechanisms underlying the neurotoxicity induced by these PrPC deleted forms is far from complete. To better define the neurotoxic or neuroprotective potential of PrPC N-terminal domains, and to overcome the heterogeneity of results due to the lack of a standardized model, we used neuroblastoma cells to analyse the effects of overexpressing PrPC deleted forms. Results indicate that PrPC N-terminal deleted forms were properly processed through the secretory pathway. However, PrPΔF35 and PrPΔCD mutants led to death by different mechanisms sharing loss of alpha-cleavage and activation of caspase-3. Our data suggest that both gain-of-function and loss-of-function pathogenic mechanisms may be associated with N-terminal domains and may therefore contribute to neurotoxicity in prion disease. Dissecting the molecular response induced by PrPΔF35 may be the key to unravelling the physiological and pathological functions of the prion protein.
KeywordsCellular prion protein Neurotoxicity Truncated prion protein
The authors thank Prof. D. Harris (University of Boston) for kindly providing pcDNA-PrP plasmid and Prof. A. Aguzzi (University Hospital of Zurich) for pcDNA-ΔF35 plasmid. The authors thank Tom Yohannan for the editorial advice, M. Martínez-Vicente from M. Vila’s Lab for her guidance in MMP experiments, and M. Segura for the technical assistance. This research was supported by the Spanish Ministry of Science and Innovation (BFU2012-32617), FP7-PRIORITY, the Generalitat de Catalunya (SGR2014-1218), CIBERNED (PI2014/02-4 and PRY-14-114), La Caixa Obra Social Foundation, La Marató de TV3, and the Basque Foundation of Health and Innovation Research (BIO12/AL/004) to JADR. R.G. was supported by Instituto de Salud Carlos Tercero (FIS, PI11-00075). C.V, S.V., and A.M. were supported by the Spanish Ministry of Science and Innovation. O.N. was supported by Fundación Ramón Areces.
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