Abstract
BackgroundTicks are blood-sucking arthropods that can transmit diseases to humans and animals. These arthropods are the second most important vectors of pathogens. MicroRNAs are a class of conserved small noncoding RNAs that play regulatory roles in gene expression at the post-transcriptional level. Molting is an important biological process in arthropods. Research on the molting process is important for understanding tick physiology and control.MethodsDual-luciferase reporter assays were used to assess the role of miRNA let-7 in ecdysteroid receptor (ECR) biology. The expression levels of ECR and let-7 were measured by real-time qPCR before and after tick molting. To explore the function of let-7 and ECR, we performed overexpression and knocking down of let-7 and RNAi of ECR in tick nymphs. The biological function of let-7 in molting was explored by injecting nymphs, ten days after engorgement, with let-7 agomir for overexpression and let-7 antagomir for knocking down. The rate of molting was then determined. ECR dsRNA was injected into ticks to evaluate the function of ECR by gene silencing. The expression of ECR and let-7 was measured using RT-qPCR. All data were analyzed using GraphPad Prism v.6.ResultsThe results of the luciferase assay using a eukaryotic expression system revealed that ECR was a natural target of let-7. Let-7 overexpressed by agomir affected the rate of molting (P < 0.01) and the period of molting (P < 0.01). Let-7 antagomir for knockdown affected the period of molting (P < 0.01), but there was no effect on the rate of molting (P = 0.27). ECR dsRNA gene silencing significantly affected the rate of molting (P < 0.05).ConclusionsThis study demonstrated that let-7 can regulate the expression of ECR and that let-7 can affect molting in ticks. Our results help to understand the regulation of let-7 by 20-hydroxyecdysone (20E) and will provide a reference for functional analysis studies of microRNAs in ticks.
Highlights
Ticks are blood-sucking arthropods that can transmit diseases to humans and animals
We identified three AamECR isoforms (AamECRA1, AamECRA2 and AamECRA3) and the AamECR3′-UTR isoforms in H. asiaticum
MiRNA represses ecdysteroid receptor (ECR) expression in BHK‐CDC cells The Dual luciferase reporter (DLR) assay was used to assess the effect of let-7 on ECR expression in BHK-CDC cells
Summary
Ticks are blood-sucking arthropods that can transmit diseases to humans and animals. These arthropods are the second most important vectors of pathogens. MicroRNAs (miRNAs) are a class of small non-coding RNAs with a length of 21–24 nucleotides These molecules are involved in the post-transcriptional regulation of mRNAs in plants and animals [6, 7]. Let-7 is the second miRNA identified in Caenorhabditis elegans and is evolutionally conserved in bilateral animals [6, 9]. This molecule is essential in the heterochrony pathway, playing a role in
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