ECHS1-NOX4 interaction suppresses rotenone-induced dopaminergic neurotoxicity through inhibition of mitochondrial ROS production

BACKGROUND: Parkinson's disease (PD) is the most common neurodegenerative movement disorder with uncleared mechanisms. Short-chain enoyl-CoA hydratase 1 (ECHS1) is a mitochondrial enzyme critical for the β-oxidation of fatty acids and ATP production. This study aims to explore the roles of ECHS1 in PD by using rotenone-induced experimental PD models. METHODS: To evaluate the role of ECHS1 in rotenone-induced dopaminergic neurodegeneration, adeno-associated virus (AAV)-ECHS1 was stereotactically injected into the substantia nigra region of mice to overexpress ECHS1. Motor function of mice among groups was detected by rotarod test and gait analysis. Neurodegeneration, mitochondrial dysfunction and apoptosis were determined by immunohistochemistry, immunofluorescence staining, Western blot or kits, respectively. RESULTS: The expression and activity of ECHS1 were decreased in PD mice and positive correlations between ECHS1 reduction and dopaminergic neurodegeneration were observed. Overexpression of ECHS1 by AAV delivery attenuated loss of dopaminergic neuron and motor deficits in PD mice. Mechanistically, ECHS1 attenuated rotenone-induced mitochondrial swelling and loss of cristae as well as decrease of ATP production, mitochondrial membrane potential, complex I/IV activities and oxygen consumption rate (OCR). Mitochondrial ROS (mtROS)-targeted antioxidant mito-TEMPO prevented ECHS1 silence-mediated mitochondrial dysfunction. Furthermore, we found that ECHS1 interacted with NADPH oxidase 4 (NOX4), resulting in decrease of NOX4 activation and subsequent reduction of mtROS production and mitochondrial dysfunction. Finally, inhibition of NOX4 by GLX351322 or mtROS production by mito-TEMPO greatly reduced ECHS1 silence-mediated apoptosis in rotenone-treated SH-SY5Y cells. CONCLUSIONS: ECHS1 counteracted dopaminergic neurodegeneration through inhibition of mtROS and restoration of mitochondrial function via interaction with NOX4. Given the central role of mitochondrial dysfunction in PD pathogenesis, elucidating the role of ECHS1 holds great promise for uncovering novel therapeutic targets.