Department of Neurology, The First Hospital of Jilin University, Changchun 130000, China.
Department of Neurosurgery, The First Hospital of Jilin University, Changchun 130000, China.
Biomed Pharmacother. 2023 Aug;164:114958. doi: 10.1016/j.biopha.2023.114958. Epub 2023 May 30.
UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE) myopathy is an autosomal recessive disease characterized by rimmed vacuoles (RVs). Previous studies have shown that metformin protects against several neuromuscular disorders. In the present study, we summarize the clinical features of three GNE patients with the p.D207V mutation. The pathogenesis of GNE myopathy is described, and the significance of metformin in this disease is observed. Skin biopsy-derived fibroblasts from patients with GNE myopathy, carrying a D207V mutation in GNE, were cultured. GNE fibroblasts and control fibroblasts were treated under normal culture conditions, serum starvation conditions, or serum starvation + metformin conditions. Histopathological and immunohistochemical analyses of muscle samples showed that autophagy was involved in the formation of RVs in the muscle of patients. Starved GNE fibroblasts showed decreased autophagy-related proteins and impaired autophagic flow (p < 0.05). The mRFP-GFP-LC3 assay showed that the fusion of autophagosomes with lysosomes was partially blocked in GNE cells. Notably, metformin treatment upregulated the expression of autophagy proteins, increased the number of autolysosomes (p < 0.001), and influenced the viability of GNE cells (p < 0.001). Furthermore, adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) and phosphorylated (p)-AMPK expression levels were upregulated in serum-starved GNE fibroblasts, while the mammalian target of rapamycin (mTOR) and p-mTOR expression levels were downregulated in both groups. Metformin treatment inhibited the AMPK-mTOR signaling pathway. Our results suggest that metformin plays a protective role in the GNE fibroblast by restoring autophagic flux and through the AMPK/mTOR-independent pathway.
UDP-N-乙酰氨基葡萄糖 2-差向异构酶/N-乙酰甘露糖胺激酶（GNE）肌病是一种常染色体隐性疾病，其特征为边缘空泡（RVs）。先前的研究表明，二甲双胍可预防多种神经肌肉疾病。在本研究中，我们总结了 3 名携带 GNE 突变 p.D207V 的 GNE 患者的临床特征。描述了 GNE 肌病的发病机制，并观察了二甲双胍在该疾病中的意义。培养了携带 GNE 突变的 GNE 肌病患者的皮肤活检衍生成纤维细胞。在正常培养条件、血清饥饿条件或血清饥饿+二甲双胍条件下处理 GNE 成纤维细胞和对照成纤维细胞。肌肉样本的组织病理学和免疫组织化学分析表明自噬参与了患者肌肉中 RV 的形成。饥饿的 GNE 成纤维细胞显示自噬相关蛋白减少，自噬流受损（p<0.05）。mRFP-GFP-LC3 测定表明，自噬体与溶酶体的融合在 GNE 细胞中部分受阻。值得注意的是，二甲双胍治疗上调了自噬蛋白的表达，增加了自噬溶酶体的数量（p<0.001），并影响了 GNE 细胞的活力（p<0.001）。此外，血清饥饿的 GNE 成纤维细胞中 AMP 激活的蛋白激酶（AMPK）和磷酸化（p）-AMPK 表达水平上调，而两组中哺乳动物雷帕霉素靶蛋白（mTOR）和 p-mTOR 表达水平下调。二甲双胍治疗抑制了 AMPK-mTOR 信号通路。我们的结果表明，二甲双胍通过恢复自噬流并通过 AMPK/mTOR 非依赖性途径在 GNE 成纤维细胞中发挥保护作用。
