Neurexin 2 p.G849D variant, implicated in Parkinson's disease, increases reactive oxygen species, and reduces cell viability and mitochondrial membrane potential in SH-SY5Y cells

Parkinson's disease (PD) is a neurodegenerative movement disorder, affecting 1-2% of the human population over 65. A previous study by our group identified a p.G849D variant in neurexin 2 alpha (NRXN2) co-segregating with PD, prompting validation of its role using experimental methods. This novel variant had been found in a South African family with autosomal dominant PD. NRXN2 alpha is an essential synaptic maintenance protein with multiple functional roles at the synaptic cleft. The aim of the present study was to investigate the potential role of the translated protein NRXN2 alpha and the observed mutant in PD by performing functional studies in an in vitro model. Wild-type and mutant NRXN2 alpha plasmids were transfected into SH-SY5Y cells to assess the effect of the mutant on cell viability and apoptosis [(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) Assay; ApoTox-Glo (TM) Triplex Assay)], mitochondrial membrane potential (MMP; MitoProbe (TM) JC-1 Assay), mitochondrial network analysis (MitoTracker(R)) and reactive oxygen species (ROS; ROS-Glo (TM) H2O2 Assay). Cells transfected with the mutant NRXN2 alpha plasmid showed decreased cell viability and MMP. They also exhibited increased ROS production. However, these cells showed no changes in mitochondrial fragmentation. Our findings led us to speculate that the p.G849D variant may be involved in a toxic feedback loop leading to neuronal death in PD. Mitochondrial dysfunction and synaptic dysfunction have been linked to PD. Therefore, findings from this exploratory study are in line with previous studies connecting these two processes and warrants further investigation into the role of this variant in other cellular and animal models.

Automated summary

The aim of this study was to investigate the potential role of the translated protein NRXN2 alpha and a specific mutant in Parkinson's disease (PD). Functional studies in an in vitro model showed that cells transfected with the mutant NRXN2 alpha plasmid exhibited decreased cell viability, decreased mitochondrial membrane potential, and increased reactive oxygen species production. These findings suggest that the p.G849D variant may be involved in neuronal death in PD.