MiR-27b promotes sheep skeletal muscle satellite cell proliferation by targeting .

To investigate the role of miR-27b in sheep skeletal muscle development, here we first cloned the sequence of sheep pre-miR-27b, then further investigated its expression pattern in sheep skeletal muscle , the relationship of miR-27b expression and sheep skeletal muscle satellite cell proliferation and differentiation , and then finally confirmed its target gene during this development process. MiR-27b sequence, especially its mature sequence, was conservative among different species. MiR-27b highly expressed in sheep skeletal muscle than other tissues. In skeletal muscle of Suffolk and Bashbay sheep, miR-27b was upregulated during foetal period and downregulated during postnatal period significantly (<0.01), but it still kept a relatively higher expression level in skeletal muscle of postnatal Suffolk sheep than Bashbay. There is a potential target site of miR-27b on 3'-UTR of sheep myostatin () mRNA, and the double luciferase reporter assay proved that miR-27b could successfully bind on this site. When sheep satellite cells were in the proliferation status, miR-27b was upregulated and was downregulated significantly (<0.01). When miR-27b mimics was transfected into sheep satellite cells, the cell proliferation was promoted and the protein level of was significantly downregulated (<0.01). Moreover, miR-27b regulated its target gene by translation repression at an early step, and followed by inducing mRNA degradation in sheep satellite cells. Based on these results, we confirm that miR-27b could promote sheep skeletal muscle satellite cell proliferation by targeting and suppressing its expression.