The Familial α-Synuclein A53E Mutation Enhances Cell Death in Response to Environmental Toxins Due to a Larger Population of Oligomers.

Amyloid formation of α-synuclein (α-Syn) and its familial mutations are directly linked with Parkinson's disease (PD) pathogenesis. Recently, a new familial α-Syn mutation (A53E) was discovered, associated with an early onset aggressive form of PD, which delays α-Syn aggregation. When we overexpressed wild-type (WT) and A53E proteins in cells, showed neither toxicity nor aggregate formation, suggesting merely overexpression may not recapitulate the PD phenotype in cell models. We hypothesized that cells expressing the A53E mutant might possess enhanced susceptibility to PD-associated toxicants compared to that of the WT. When cells were treated with PD toxicants (dopamine and rotenone), cells expressing A53E showed more susceptibility to cell death along with compromised mitochondrial potential and an increased production of reactive oxygen species. The higher toxicity of A53E could be due to more oligomers being formed in cells as confirmed by a dot blot assay using amyloid specific OC and A11 antibody and using an  in vitro aggregation study. The cellular model presented here suggests that along with familial mutation, environmental and other cellular factors might play a crucial role in dictating PD pathogenesis.