Bmo-miR-9A down regulates the expression of Bm-ase gene in vitro.

MicroRNAs (miRNAs) are a class of non-protein coding small RNAs of 18-24 nucleotides in length that regulate expression of genes at post-transcriptional levels and play multiple roles in biological processes. Bm-ase plays an important role in the course of nerve development of the silkworm, Bombyx mori. Bmo-miR-9a is a conservative miRNA. By using target prediction software RNA22 and RNAhybrid, we found a target site of Bmo-miR-9a in the 3'UTR of Bm-ase gene. To verify the regulation function of Bmo-miR-9a on the expression of Bm-ase gene, a Bmo-miR-9a over-expressing vector and Bm-ase 3'UTR fused firefly luciferase gene reporter plasmid were constructed, respectively. Then they were used to co-transfect the BmN cells. The result showed that luciferase activity in the co-transfected cells was suppressed compared with the control. A similar result was obtained when BmN cells were co-transfected with artificial synthetic Bmo-miR-9a mimics and Bm-ase 3'UTR fused luciferase reporter plasmid. These results suggest that Bmo-miR-9a can down regulate the expression of Bm-ase gene.