Mi Lin, Li Youlei, Zhang Qiangling, Zhao Chen, Peng Ying, Yang Gongshe, Zheng Xueli
a Laboratory of Animal Fat Deposition and Muscle Development, College of Animal Science and Technology, Northwest A&F University, Yangling, China.
Biochem Cell Biol. 2015 Feb;93(1):8-15. doi: 10.1139/bcb-2014-0079. Epub 2014 Sep 2.
MicroRNAs (miRNAs) are novel and potent regulators in myogenesis. However, the molecular mechanisms that many miRNAs regulate myoblast proliferation and differentiation which are largely unknown. Here, we found that miR-139-5p increased during C2C12 myoblast proliferation, while presenting an inverse trend during C2C12 myoblast differentiation. Flow cytometry and EdU incorporation assay showed that miR-139-5p slowed down the growth of C2C12 cells. Additional study demonstrated that ectopic introduction of miR-139-5p into C2C12 cells blocked myoblast differentiation. Importantly, we demonstrated for the first time that Wnt1, which is associated with the Wnt/β-catenin signaling pathway, was a direct target of miR-139-5p. Moreover, we found that the expression level of Wnt1 was suppressed significantly (p < 0.01) by miR-139-5p, which triggered inhibition of Wnt/β-catenin signaling through upregulation of glycogen synthase kinase 3 beta (GSK-3β; p < 0.05) and downregulation of p-GSK-3β (p < 0.01), β-catenin (p < 0.05), and nuclear β-catenin (p < 0.01). Taken together, these results suggest that miR-139-5p is an important negative regulator in myogenesis through blocking the Wnt1-mediated Wnt/β-catenin signaling pathway.
微小RNA（miRNA）是成肌过程中新型且强大的调节因子。然而，许多miRNA调节成肌细胞增殖和分化的分子机制在很大程度上尚不清楚。在此，我们发现miR-139-5p在C2C12成肌细胞增殖过程中增加，而在C2C12成肌细胞分化过程中呈现相反趋势。流式细胞术和EdU掺入试验表明，miR-139-5p减缓了C2C12细胞的生长。进一步的研究表明，将miR-139-5p异位导入C2C12细胞会阻断成肌细胞分化。重要的是，我们首次证明与Wnt/β-连环蛋白信号通路相关的Wnt1是miR-139-5p的直接靶点。此外，我们发现miR-139-5p显著抑制Wnt1的表达水平（p<0.01），通过上调糖原合酶激酶3β（GSK-3β；p<0.05）和下调p-GSK-3β（p<0.01）、β-连环蛋白（p<0.05）和核β-连环蛋白（p<0.01）引发Wnt/β-连环蛋白信号通路的抑制。综上所述，这些结果表明miR-139-5p通过阻断Wnt1介导的Wnt/β-连环蛋白信号通路，在成肌过程中是一个重要的负调节因子。
