GSE123407
A microRNA profile of saliva and role of miR-375 in Haemaphysalis longicornis (Ixodida: Ixodidae)
Tick saliva contains many bioactive molecules that are involved in attachment to the host, blood feeding and transmission of pathogens. MicroRNAs (miRNAs) are a class of short non-coding RNAs with a length of 19-24 nucleotides. They act as regulators of gene expression by binding to their target mRNA at the post-transcriptional level and control a variety of cellular functions, including regulation of growth, metabolism, and development. The detection and characterizations of miRNAs from tick saliva may help explain the molecular mechanisms involved in the interaction between ticks, pathogens, and hosts. They may also contribute to the discovery of vaccines, which can control ticks and the pathogens they transmit. An RNA library was generated from the saliva of fed adult Haemaphysalis longicornis ticks, and it contained 17.4 million clean reads of 18-30 nucleotides. Overall, 319 known miRNAs and 1 novel miRNA were found. The 10 most abundantly expressed miRNAs present in tick saliva were miR-100_2, miR-315, miR-184_1, miR-100-5p_2, miR-5307, miR-184-3p_3, Let-7-5p_6, miR-71_5, miR-1-3p_6, and miR-10-5p_2. The miR-375, one of the abundantly expressed, was subjected to Quantitative Real-Time PCR analysis (qRT-PCR) in various tick developmental stages, as well as in different tissues isolated from adult ticks. The expression of miR-375 in different tick development stages was highest in unfed nymphs and lowest in the egg stage. In the tissues of adult ticks, miR-375 was most highly expressed in the salivary gland. To investigate the possible role of miR-375, Ant-375 was used to inhibit the miR-375. Treated group (Ant-375) had a reduced number of eggs (t(10)= 2.652, P=0.0242), eggs that were partially desiccated, and reduced egg hatchability (t(10)=2.272, P=0.044) compared to Ms-Ant and the non-injected control. This is the first study to investigate the miRNAs profile in tick saliva and the role of miR-375 in H. longicornis. The identification and characterization of miRNA in tick saliva may help to reveal the molecular mechanisms of interactions among ticks, pathogens, and hosts and suggest new vaccine strategies to control tick borne diseases. Overall design: Construction of the small RNA (sRNA) library from the saliva of fed adult H. longicornis, using Hiseq technology and their role in H. longicornis