Department of Neurology, Tohoku University School of Medicine, Sendai 980-8574, Japan.
The Institute of Development, Aging and Cancer, Tohoku University, Sendai 980-8575, Japan.
Mol Ther. 2020 Apr 8;28(4):1133-1153. doi: 10.1016/j.ymthe.2020.02.006. Epub 2020 Feb 12.
Mutations in dysferlin are responsible for a group of progressive, recessively inherited muscular dystrophies known as dysferlinopathies. Using recombinant proteins and affinity purification methods combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS), we found that AMP-activated protein kinase (AMPK)γ1 was bound to a region of dysferlin located between the third and fourth C2 domains. Using ex vivo laser injury experiments, we demonstrated that the AMPK complex was vital for the sarcolemmal damage repair of skeletal muscle fibers. Injury-induced AMPK complex accumulation was dependent on the presence of Ca, and the rate of accumulation was regulated by dysferlin. Furthermore, it was found that the phosphorylation of AMPKα was essential for plasma membrane repair, and treatment with an AMPK activator rescued the membrane-repair impairment observed in immortalized human myotubes with reduced expression of dysferlin and dysferlin-null mouse fibers. Finally, it was determined that treatment with the AMPK activator metformin improved the muscle phenotype in zebrafish and mouse models of dysferlin deficiency. These findings indicate that the AMPK complex is essential for plasma membrane repair and is a potential therapeutic target for dysferlinopathy.
肌营养不良蛋白基因突变是一组进行性、隐性遗传性肌肉疾病的原因，这些疾病被称为肌营养不良症。我们使用重组蛋白和亲和纯化方法结合液相色谱-串联质谱（LC-MS/MS），发现 AMP 激活的蛋白激酶（AMPK）γ1 与肌营养不良蛋白的一个区域结合，该区域位于第三和第四个 C2 结构域之间。通过体外激光损伤实验，我们证明了 AMPK 复合物对于骨骼肌纤维的肌膜损伤修复至关重要。损伤诱导的 AMPK 复合物积累依赖于 Ca 的存在，并且积累的速度受肌营养不良蛋白调节。此外，发现 AMPKα 的磷酸化对于质膜修复是必不可少的，并且用 AMPK 激活剂处理可挽救在表达减少的肌营养不良蛋白的永生化人类肌管和肌营养不良蛋白缺失的小鼠纤维中观察到的膜修复障碍。最后，确定 AMPK 激活剂二甲双胍的治疗可改善肌营养不良症斑马鱼和小鼠模型的肌肉表型。这些发现表明 AMPK 复合物对于质膜修复是必需的，并且是肌营养不良症的潜在治疗靶点。
