NDUFA4 Deletion Upregulates VDAC1 to Promote Mitochondrial Damage, Endoplasmic Reticulum Expansion, and Neuronal Apoptosis.

Background: Dandy-Walker malformation (DWM) is a rare congenital brain defect whose mechanism is still not fully understood. Genetic studies have suggested that NADH Dehydrogenase 1 alpha Subcomplex 4 (NDUFA4) may be associated with DWM; however, the functional consequences of NDUFA4 dysregulation in experimental neural models remain unclear. In this study, we investigated the cellular effects of NDUFA4 deficiency, rather than aiming to establish a causal mechanism for DWM. Methods: NDUFA4-related differentially expressed proteins were analyzed using iTRAQ tandem mass spectrometry, followed by functional, pathway, and protein interaction network analyses. Then, voltage-dependent anion Channel 1 (VDAC1), apoptosis-, endoplasmic reticulum (ER) stress-related proteins, and ETC Complex IV activity were assessed in NDUFA4 knockout mice. After NDUFA4 and VDAC1 knockdown, cell proliferation, apoptosis, mitochondrial status, and ER function were evaluated by CCK-8, Edu staining, flow cytometry, and Western blot in C8-D1A cells. In addition, the interaction between NDUFA4 and VDAC1 was evaluated using immunofluorescence and coimmunoprecipitation. Results: NDUFA4 knockout upregulated VDAC1, ER stress- and apoptosis-related proteins, and inhibited ETC complex IV activity in mice. NDUFA4 knockdown inhibited proliferation and promoted apoptosis, ER stress, and mitochondrial damage in C8-D1A cells, and these changes were partially reversed by VDAC1 knockdown. Moreover, NDUFA4 and VDAC1 colocalized in C8-D1A cells and mouse cerebellar tissue, and NDUFA4 was found to interact with VDAC1. Conclusions: NDUFA4 deletion was associated with VDAC1 upregulation, mitochondrial damage, ER stress, and apoptosis-related changes in our experimental models. These findings may provide insight into cellular changes potentially relevant to DWM; however, they do not establish a direct causal relationship.