Table1_Apol9a regulates myogenic differentiation via the ERK1/2 pathway in C2C12 cells.DOCX

Background: The rising prevalence of obesity and its complications is a big challenge for the global public health. Obesity is accompanied by biological dysfunction of skeletal muscle and the development of muscle atrophy. The deep knowledge of key molecular mechanisms underlying myogenic differentiation is crucial for discovering novel targets for the treatment of obesity and obesity-related muscle atrophy. However, no effective target is currently known for obesity-induced skeletal muscle atrophy.
Methods: Transcriptomic analyses were performed to identify genes associated with the regulation of myogenic differentiation and their potential mechanisms of action. C2C12 cells were used to assess the myogenic effect of Apol9a through immunocytochemistry, western blotting, quantitative polymerase chain reaction, RNA interference or overexpression, and lipidomics.
Results: RNA-seq of differentiated and undifferentiated C2C12 cells revealed that Apol9a expression significantly increased following myogenic differentiation and decreased during obesity-induced muscle atrophy. Apol9a silencing in these C2C12 cells suppressed the expression of myogenesis-related genes and reduced the accumulation of intracellular triglycerides. Furthermore, RNA-seq and western blot results suggest that Apol9a regulates myogenic differentiation through the activation of extracellular signal-regulated kinase 1/2 (ERK1/2). This assumption was subsequently confirmed by intervention with PD98059.
Conclusion: In this study, we found that Apol9a regulates myogenic differentiation via the ERK1/2 pathway. These results broaden the putative function of Apol9a during myogenic differentiation and provide a promising therapeutic target for intervention in obesity and obesity-induced muscle atrophy.

研究背景：肥胖及其并发症的患病率持续攀升，已成为全球公共卫生面临的重大挑战。肥胖常伴随骨骼肌生物学功能异常与肌肉萎缩的发生。深入阐明肌源性分化的关键分子机制，对于发掘肥胖及肥胖相关肌肉萎缩的新型治疗靶点具有重要意义。然而，目前尚无针对肥胖诱导性骨骼肌萎缩的有效治疗靶点。研究方法：本研究通过转录组分析，筛选参与肌源性分化调控的基因并解析其潜在作用机制。以C2C12细胞为实验模型，采用免疫细胞化学、蛋白质免疫印迹、定量聚合酶链反应、RNA干扰、过表达及脂质组学技术，评估Apol9a的肌源性调控效应。研究结果：对分化与未分化C2C12细胞的转录组测序（RNA-seq）分析显示，Apol9a的表达水平在肌源性分化过程中显著上调，而在肥胖诱导的肌肉萎缩过程中则显著下调。在C2C12细胞中沉默Apol9a，可抑制肌生成相关基因的表达，并减少细胞内甘油三酯的积累。进一步的转录组测序与蛋白质免疫印迹结果表明，Apol9a通过激活细胞外调节蛋白激酶1/2（ERK1/2）通路调控肌源性分化，该结论随后通过PD98059干预实验得到验证。研究结论：本研究证实，Apol9a通过ERK1/2通路调控肌源性分化。本研究结果拓展了Apol9a在肌源性分化过程中的潜在功能，并为肥胖及肥胖诱导性肌肉萎缩的干预治疗提供了极具潜力的治疗靶点。