NADPH Oxidase 1 Mediates Alpha-Synucleinopathy in Parkinson’s Disease
The NOX1–Alpha-Synuclein Axis
The accumulation of misfolded alpha-synuclein is the pathological hallmark of Parkinson’s disease, yet the mechanism driving its aggregation and the resulting toxicity to dopaminergic neurons remained poorly understood. Starting from the premise that oxidative stress increases the expression and aggregation of this protein, this study investigated the role of NADPH oxidase 1 (NOX1), an enzyme specialised in the production of reactive oxygen species, in the regulation of alpha-synuclein in dopaminergic neurons.
Using paraquat-induced models of Parkinson’s disease, both in vitro and in vivo, the authors showed that exposure to the toxin simultaneously raises the levels of NOX1 and alpha-synuclein in differentiated human dopaminergic cells. Building on this observation, NOX1 knockdown significantly reduced not only the expression but also the aggregation of the protein. This effect was confirmed in rats exposed to paraquat, where the selective silencing of NOX1 in the substantia nigra, achieved through an adeno-associated virus vector encoding a specific shRNA, markedly attenuated the increase in alpha-synuclein and ubiquitin, as well as the formation of proteinase K resistant aggregates and A11 oligomers. In parallel, substantial reductions in oxidative stress and in the loss of dopaminergic neurons were observed.
Taken together, these results reveal a new mechanism by which alpha-synuclein acquires its neuropathological character, mediated by NOX1-derived oxidative stress and acting both at the transcriptional level and in the post-translational aggregation process. By positioning NOX1 as a crucial intermediary between an environmental factor that generates oxidative stress and alpha-synuclein pathology, the work reinforces the link between oxidative stress and disease progression and points to this enzyme as a promising therapeutic target for Parkinson’s disease and other synucleinopathies.