Abstract：MicroRNA is a class of noncoding small RNA. It is involed in the regulation of many parts of life processes, and plays an important role in cell proliferation, differentiation and tissue development. In order to study the roles of microRNA-31 in wool follicle development of sheep, we collected wool follicle samples from Tibetan sheep(Ovis aries) during three different phases including anagen, catagen and telogen. The results showed that there was a significance change of the expression of microRNA-31 during wool follicle development by quantitative Real-time (qPCR). Results showed that the expression of microRNA-31 was decreased from anagen to telogen and the expression in anagen was about 1.5 fold than catagen (P<0.01). In addition, we predicted the precursor sequence of sheep microRNA-31 by miRdeep2 software and found that it was located on the negative strand of sheep chromosome 2 from 89 779 078 to 89 779 137 nucleotides (OAR2.0 version) . Furthermore, we predicted the target genes by RNA22 software. We found that two candidate genes, Keratin17(KRT17) and distal-less homebox3 (DLX3), existed potential binding sites of microRNA-31 in sheep. Then we detected the expression variation of KRT17 and DLX3 genes in anagen, catagen and telogen wool follicle samples by qPCR. As a result, the expression of KRT17 was increased from anagen to telogen. The level in telogen was almost 3 fold than anagen (P<0.01). It was a reverse pattern of the expression of microRNA-31. However, the expression of DLX3 in catagen was higher than the other two phases (catagen and telogen)(P<0.01). Conclusion, we suggested that microRNA-31 may play an impotent role during wool follicle development, and KRT17 probably is one of the target genes which are regulated by microRNA-31.
