Complex I deficiency in m.3243A>G fibroblasts is alleviated by reducing NADH accumulation

Frontiers in Physiology

Physiology

Haiyan Yu¹  Jiaxi Yu²  Meng Yu²  Tongling Liufu²  Zhaoxia Wang³  Jianwen Deng³  Guogang Xing⁴  Yue Tian⁴  Yichun Ou⁴ 

[1] Department of Clinical Laboratory, Peking University First Hospital, Beijing, China;Department of Neurology, Peking University First Hospital, Beijing, China;Department of Neurology, Peking University First Hospital, Beijing, China;Beijing Key Laboratory of Neurovascular Disease Discovery, Beijing, China;Neuroscience Research Institute, Peking University, Beijing, China;

关键词: complex I;    m.3243 A>G;    mitochondrial disease;    mitoLbNOX;    NADH;    nr;   

DOI  :  10.3389/fphys.2023.1164287

 received in 2023-02-21, accepted in 2023-08-03,  发布年份 2023

来源: Frontiers

【 摘 要 】

Introduction: Mitochondrial disease is a spectrum of debilitating disorders caused by mutations in the mitochondrial DNA (mtDNA) or nuclear DNA that compromises the respiratory chain. Mitochondrial 3243A>G (m.3243 A>G) is the most common mutation showing great heterogeneity in phenotype. Previous studies have indicated that NADH: ubiquinone oxidoreductase (complex I) deficiency accompanied by a decreased nicotinamide adenine dinucleotide (NAD+)/reduced NAD+ (NADH) ratio may play a pivotal role in the pathogenesis of m.3243A>G mutation.Methods: To evaluate the potential effects of strategies targeting the imbalanced NAD+/NADH ratio in m.3243A>G mutation, we treated fibroblasts derived from patients with the m.3243 A>G mutation using nicotinamide riboside (NR) or mitochondria-targeted H2O-forming NADH oxidase (mitoLbNOX).Results: M.3243 A>G fibroblasts showed a significant reduction in complex I core subunit 6, complex I enzymatic activity, complex I-dependent oxygen consumption rate (OCR), and adenosine triphosphate (ATP) production compared to the controls. The NAD+/NADH ratio was also significantly reduced in m.3243 A>G fibroblasts, and, using fluorescence lifetime imaging microscopy, we also found that the NADH level was elevated in m.3243 A>G fibroblasts. After NR treatment, the NAD+/NADH ratio, complex I-dependent OCR, and ATP levels increased, whereas NADH levels remained unchanged. More excitingly, after treatment with mitoLbNOX, the NAD+/NADH ratio, complex I-independent OCR, and ATP levels increased more pronouncedly compared with the NR treatment group, accompanied by significantly reduced NADH levels.Discussion: The present study suggests that compared with repletion of NAD+ alone, the combination of this therapeutic modality with alleviation of NADH overload may amplify the treatment effect of restoring NAD+/NADH balance in m.3243A>G fibroblasts.

【 授权许可】

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Copyright © 2023 Liufu, Yu, Yu, Yu, Tian, Ou, Deng, Xing and Wang.