α-synuclein protects naive but not dbcAMP-treated dopaminergic cell types from 1-methyl-4-phenylpyridinium toxicity

The pre-synaptic protein, α-synuclein, has been associated with the pathogenesis of Parkinson's disease. The present study indicates that α-synuclein, but not its mutants (A53T, A30P), can protect CNS dopaminergic cells from the parkinsonism-inducing drug 1-methyl-4-phenylpyridinium (MPP⁺), whereas it cannot protect from the dopaminergic toxin, 6-hydroxydopamine, hydrogen-peroxide, or the β-amyloid peptide, A-β. Protection from MPP⁺ was directly correlated with the preservation of mitochondrial function. Specifically, α-synuclein rescued cells from MPP⁺ mediated decreases in mitochondrial dehydrogenase activity and loss of ATP levels by utilizing ketosis. It also prevented toxin-induced activation of the creatine kinase/creatine phosphate system. Similarly, α-synuclein protected cells from the complex I inhibitor rotenone and 3-nitroproprionic acid, a complex II inhibitor. Wild-type α-synuclein-mediated neuroprotection and subsequent alterations in energy were not found in dbcAMP-differentiated cells. These results suggest that the normal physiological role for α-synuclein may change during development.