Qiu Jiaying, Zhu Jianwei, Zhang Ru, Liang Wenpeng, Ma Wenjing, Zhang Qiuyu, Huang Ziwei, Ding Fei, Sun Hualin
School of Biology and Basic Medical Sciences, Medical College of Soochow University, Suzhou 215123, China.
Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Jiangsu Clinical Medicine Center of Tissue Engineering and Nerve Injury Repair, Co-Innovation Center of Neuroregeneration, Nantong University, Nantong 226001, China.
Ann Transl Med. 2019 Sep;7(18):456. doi: 10.21037/atm.2019.08.39.
Skeletal muscle atrophy, characterized by accelerated protein degradation, occurs in such conditions as unloading, immobilization, fasting, and denervation. Effective treatments for skeletal muscle atrophy are not yet available. Considering that microRNAs (miRs) may play an important role in the regulation of muscle atrophy, in the present study, we aimed to examine the effect of miR-125b-5p-based therapeutic strategies on skeletal muscle atrophy, and to explore the underlying mechanisms.
Fasting-induced atrophic mouse C2C12 myotubes and denervated rat tibialis anterior (TA) muscles were used as and models of skeletal muscle atrophy, respectively. The morphological parameters of skeletal muscle were measured by immunostaining-based quantification. The interaction between miR-125b-5p and TRAF6 3'-UTR was detected by luciferase reporter analysis. The mRNA and protein expressions were determined by real-time qPCR and Western blot analysis respectively. The miR mimics/agomir and miR inhibitor/antagomir were transfected into C2C12 myotubes and TA muscles respectively to alter the expression of miR-125b-5p.
The expression of miR-125b-5p was down-regulated in both atrophic C2C12 myotubes and denervated TA muscles. The interaction between miR-125b-5p and TRAF6 3'-UTR was identified. Overexpression of miR-125b-5p protected skeletal muscle samples from atrophy and by targeting TRAF6 through inactivation of several ubiquitin-proteasome system (UPS)- and autophagy-lysosome system (ALS)-related proteins.
Overexpression of miR-125b-5p may provide a promising therapeutic approach to treat muscle atrophy.
骨骼肌萎缩以蛋白质降解加速为特征，发生于诸如失重、固定、禁食和去神经支配等情况。目前尚无有效的骨骼肌萎缩治疗方法。鉴于微小RNA（miR）可能在肌肉萎缩的调节中发挥重要作用，在本研究中，我们旨在研究基于miR-125b-5p的治疗策略对骨骼肌萎缩的影响，并探索其潜在机制。
将禁食诱导的萎缩小鼠C2C12肌管和去神经支配的大鼠胫前肌（TA）分别用作骨骼肌萎缩的体外和体内模型。通过基于免疫染色的定量方法测量骨骼肌的形态学参数。通过荧光素酶报告基因分析检测miR-125b-5p与TRAF6 3'-UTR之间的相互作用。分别通过实时定量PCR和蛋白质免疫印迹分析测定mRNA和蛋白质表达。将miR模拟物/激动剂和miR抑制剂/拮抗剂分别转染到C2C12肌管和TA肌肉中以改变miR-125b-5p的表达。
萎缩的C2C12肌管和去神经支配的TA肌肉中miR-125b-5p的表达均下调。鉴定出miR-125b-5p与TRAF6 3'-UTR之间的相互作用。miR-125b-5p的过表达通过使几种泛素-蛋白酶体系统（UPS）和自噬-溶酶体系统（ALS）相关蛋白失活，靶向TRAF6，从而保护骨骼肌样本免于萎缩。
miR-125b-5p的过表达可能为治疗肌肉萎缩提供一种有前景的治疗方法。
