The microRNA miR-14 Regulates Egg-Laying by Targeting EcR in Honeybees (Apis mellifera)

SIMPLE SUMMARY: Honeybees (Apis mellifera) are important pollinators and commonly used for honey production. The oviposition behavior in honeybees is complex and errors in oviposition could affect the development of the bee colony. Ecdysone receptor (EcR) and miR-14 were previously reported to play important roles in egg-laying. Moreover, EcR was predicted to be the target gene of miR-14 and may form miR-14-EcR cross-talk. By knocking down and overexpression of miR-14 and EcR in queen model, the effect of RNA expression of miR-14 and EcR on the number of eggs laid by honeybee queens was analyzed. We found that the expression of miR-14 and EcR was associated with the egg number of queens. In specific, inhibition of miR-14 expression enhanced the egg number, while overexpression of EcR enhanced the egg number in honeybee queens. ABSTRACT: Honeybees (Apis mellifera) are important pollinators and are commonly used for honey production. The oviposition behavior in honeybees is complex and errors in oviposition could affect the development of the bee colony. Recent studies reported that RNA–RNA cross-talk played a critical role in several biological processes, including reproduction. Ecdysone receptor (EcR) and miR-14 were previously reported to play important roles in egg-laying. Moreover, EcR was predicted to be the target gene of miR-14 and may form miR-14-EcR cross-talk. In this study, knocking down and overexpression of miR-14 and EcR in queen model were implemented. The effect of RNA expression of miR-14 and EcR on the number of eggs laid by honeybee queens were analyzed. Further, luciferase assay was used to confirm the target relation between miR-14 and 3′UTR of EcR. The results showed that the expression of miR-14 and EcR was associated with the number of eggs laid by queens. In specific, inhibition of miR-14 expression enhanced the number of eggs laid, while overexpression of EcR enhanced the number of eggs laid. Lastly, we determined that miR-14 directly targets the mRNA of EcR. These findings suggest that the cross-talk of miR-14-EcR plays an important role in the number of eggs laid by honeybee queens.