MiR-199b represses porcine muscle satellite cells proliferation by targeting JAG1.

Pig is a useful medical model for humans due to its similarity in size and physiology. Skeletal muscle plays an essential role in body movement. However, the skeletal muscle injuries are common. Skeletal muscle function maintenance largely depends on preserving the regenerative capacity of muscle. Muscle satellite cells proliferation plays an essential role in postnatal muscle growth and regeneration. Therefore, understanding the mechanisms associated with muscle satellite cells proliferation is essential for devising the alternative treatments for muscle injury. Previous studies showed JAG1-Notch1 signaling pathway and miRNAs regulate the skeletal muscle development. JAG1-Notch1 signal pathway regulates the transcription of certain types of miRNAs which further affects target gene expression. However, the specific relationship between JAG1-Notch1 signal pathway and miRNAs during muscle development has not been established. We found overexpression of intracellular domain of the Notch1 protein (N1ICD) in porcine muscle satellite cells (PSCs) decreased miR-199b level. We demonstrated that miR-199b inhibits PSCs proliferation using the overexpression and inhibition of miR-199b experiment. We also found JAG1, the miR-199b target gene, promotes PSCs proliferation through activating the Notch1 signal pathway. Furthermore, we demonstrated miR-199b forms a feedback loop with the JAG1-Notch1 signal pathway to maintain the PSCs niche homeostasis. Our results of miRNAs and genes work collaboratively in regulating PSCs proliferation expand our understanding in PSCs proliferation mechanism. Furthermore, this finding indicates miR-199b is a potential therapeutic target for muscle atrophy.