MiR-195/497 Inhibited Myoblast Proliferation through Targeting Igf1r, Insr and Cyclin Related Genes and Were Negatively Transcriptional Regulated By NF-Kb

It has been reported that miRNAs played important roles in the skeletal muscle development. In our previous study, expression of miR-195 and miR-497 were up-regulated during muscle development in pigs. In this study, the roles of these two miRNAs in myogenesis process and their transcriptional regulation were investigated attentively. Our results showed that miR-195 and miR-497 were closely linked and they were both increased along with muscle development and differentiation of myoblasts. MiR-195 and miR-497 have similar bio-functions and they could inhibit the proliferation, but not the differentiation of C2C12 cells. Four key genes for cell cycle and proliferation, Igf1r, Insr, Ccnd2 and Ccne1, have been identified for the first time to be targeted by these two miRNAs directly in C2C12 cells. In addition, we confirmed that miR-195 and miR-497 have similar expression patterns. The important myogenic regulator, NF-κB, could bind to the promoter region of the miR-195 and miR-497 cluster and directly negatively regulated their transcription in C2C12 cells. In conclusion, we demonstrated a novel pathway related to proliferation of myoblasts, which is NF-κB-miR195/497-Igf1r/Insr-Ccnd2/Ccne1. Our results offered new evidence for miR-195 and miR-497 in myogenesis.