Bmo-miR-79 downregulates the expression of BmEm4 in the silkworm, Bombyx mori

Abstract MicroRNA is an important regulation factor in insect development and metamorphosis. It has been reported that E(spl)m4 is a miRNA-targeted gene, as well as the target of the Notch signaling pathway in Drosophila . The expression of E(spl)m4 can be regulated by microRNA and further affect the neural development of Drosophila . Here, we found that BmEm4 , an ortholog of E(spl)m4 from Bombyx mori , was the target gene of bmo-miR-79 , with target sites containing the Brd and K boxes of the BmEm4 _3′UTR, which was validated by the dual luciferase reporter (DLR) assay. Furthermore, bmo-miR-79 mimics can inhibit the expression of BmEm4 in BmN cells after transfection, and bmo-miR-79 can also inhibit the expression of BmEm4 in different developmental stages of Bombyx mori at a posttranscriptional level, to different degrees. The EMSA test further showed that bmo-miR-79 could bind to BmAGO2, which is the Bombyx mori argonaute2 protein, suggesting that bmo-miR-79 might regulate the expression of BmEm4 by forming miRISC complexes with BmAGO2. Taken together, bmo-miR-79 could regulate the expression of BmEm4 mediated by BmAGO2 and further affect its function in the silkworm Bombyx mori .