Could α-synuclein amyloid-like aggregates trigger a prionic neuronal invasion?

Parkinson's disease (PD), a progressive neurodegenerative disease primarily affecting voluntary and controlled movement, is characterized by abnormal accumulations of α-synuclein (α-syn) in intraneuronal Lewy bodies. In the last years, the increased number of evidences from both the in vitro and in vivo studies has shown the ability of α-syn to misfold in amyloid conformations and to spread via neuron-to-neuron transmission, suggesting a prion-like behaviour. However, in contrast to prion protein (PrP), α-syn transmission is far from neuronal invasion. The high neuronal toxicity of both mature fibres and oligomeric species, as well as the intracellular localization of the protein and the difficulty to be secreted, could be key factors impeding the prion ability of α-syn aggregates.