Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, China.
Department of Neurology, Children's Hospital of Fudan University, Shanghai, China.
J Cachexia Sarcopenia Muscle. 2020 Oct;11(5):1306-1320. doi: 10.1002/jcsm.12581. Epub 2020 Aug 31.
Duchenne muscular dystrophy (DMD) is a progressive muscle disease caused by the loss of dystrophin, which results in inflammation, fibrosis, and the inhibition of myoblast differentiation in skeletal muscle. Catalpol, an iridoid glycoside, improves skeletal muscle function by enhancing myogenesis; it has potential to treat DMD. We demonstrate the positive effects of catalpol in dystrophic skeletal muscle.
mdx (loss of dystrophin) mice (n = 18 per group) were treated with catalpol (200 mg/kg) for six consecutive weeks. Serum analysis, skeletal muscle performance and histology, muscle contractile function, and gene and protein expression were performed. Molecular docking and ligand-target interactions, RNA interference, immunofluorescence, and plasmids transfection were utilized to explore the protective mechanism in DMD by which catalpol binding with transforming growth factor-β-activated kinase 1 (TAK1) in skeletal muscle.
Six weeks of catalpol treatment improved whole-body muscle health in mdx mice, which was characterized by reduced plasma creatine kinase (n = 18, -35.1%, P < 0.05) and lactic dehydrogenase (n = 18, -10.3%, P < 0.05) activity. These effects were accompanied by enhanced grip strength (n = 18, +25.4%, P < 0.05) and reduced fibrosis (n = 18, -29.0% for hydroxyproline content, P < 0.05). Moreover, catalpol treatment protected against muscle fatigue and promoted muscle recovery in the tibialis anterior (TA) and diaphragm (DIA) muscles (n = 6, +69.8%, P < 0.05 and + 74.8%, P < 0.001, respectively), which was accompanied by enhanced differentiation in primary myoblasts from DMD patients (n = 6, male, mean age: 4.7 ± 1.9 years) and mdx mice. In addition, catalpol eliminated p-TAK1 overexpression in mdx mice (n = 12, -21.3%, P < 0.05) and primary myoblasts. The catalpol-induced reduction in fibrosis and increased myoblast differentiation resulted from the inhibition of TAK1 phosphorylation, leading to reduced myoblast trans-differentiation into myofibroblasts. Catalpol inhibited the phosphorylation of TAK1 by binding to TAK1, possibly at Asp-206, Thr-208, Asn-211, Glu-297, Lys-294, and Tyr-293.
Our findings show that catalpol and TAK1 inhibitors substantially improve whole-body muscle health and the function of dystrophic skeletal muscles and may provide a novel therapy for DMD.
杜氏肌营养不良症（DMD）是一种进行性肌肉疾病，由肌营养不良蛋白的缺失引起，导致骨骼肌炎症、纤维化和成肌细胞分化抑制。梓醇是一种环烯醚萜糖苷，通过增强成肌作用改善骨骼肌功能；它具有治疗 DMD 的潜力。我们展示了梓醇在营养不良骨骼肌中的积极作用。
18 只 mdx（肌营养不良蛋白缺失）小鼠/组连续 6 周给予梓醇（200mg/kg）治疗。进行血清分析、骨骼肌性能和组织学、肌肉收缩功能以及基因和蛋白表达检测。利用分子对接和配体-靶相互作用、RNA 干扰、免疫荧光和质粒转染，探讨梓醇与骨骼肌中转化生长因子-β激活激酶 1（TAK1）结合，通过这种方式保护 DMD 的机制。
梓醇治疗 6 周可改善 mdx 小鼠的整体肌肉健康，其特征为血浆肌酸激酶（n=18，-35.1%，P<0.05）和乳酸脱氢酶（n=18，-10.3%，P<0.05）活性降低。这些作用伴随着握力增强（n=18，+25.4%，P<0.05）和纤维化减少（n=18，羟脯氨酸含量-29.0%，P<0.05）。此外，梓醇治疗可预防胫骨前肌（TA）和膈肌（DIA）肌肉疲劳和促进其恢复（n=6，分别+69.8%，P<0.05 和+74.8%，P<0.001），同时伴随着 DMD 患者（n=6，男性，平均年龄：4.7±1.9 岁）和 mdx 小鼠原代成肌细胞分化增强。此外，梓醇消除了 mdx 小鼠（n=12，-21.3%，P<0.05）和原代成肌细胞中 p-TAK1 的过度表达。梓醇诱导的纤维化减少和成肌细胞分化增加是由于 TAK1 磷酸化受到抑制，导致成肌细胞向肌成纤维细胞的转化减少。梓醇通过与 TAK1 结合抑制 TAK1 磷酸化，可能在 Asp-206、Thr-208、Asn-211、Glu-297、Lys-294 和 Tyr-293 处结合。
我们的研究结果表明，梓醇和 TAK1 抑制剂可显著改善全身肌肉健康和营养不良骨骼肌功能，可能为 DMD 提供新的治疗方法。
