Distinctive microRNA profiles in the salivary glands of Haemaphysalis longicornis related to tick blood-feeding

Abstract

The salivary glands are vital to the biological success of ticks and they are a major route of pathogen transmission. Tick salivary glands undergo remarkable growth and differentiation during the blood-feeding period. MicroRNAs (miRNAs) are noncoding small RNA molecules found in diverse organisms that regulate gene expression at the post-transcriptional level. To explore transcriptional differences in the miRNAs of fed and unfed tick (Haemaphysalis longicornis) salivary glands, we investigated small RNA (sRNA) transcriptomes derived from the salivary glands and made a comparative analysis of miRNA profiles related to tick blood-feeding in the salivary glands. We generated two small RNA libraries from the salivary glands of unfed and fed H. longicornis, and obtained 14.8 and 10.3 million reads of 18-30 nt, respectively. The unfed-specific sRNAs were clearly richer than the fed-specific sRNAs in terms of the unique and total sRNAs. Overall, 769 conserved miRNA families were found in unfed samples, whereas 440 conserved miRNA families were found in fed samples. Six of the ten most abundant miRNA were found in both the unfed and fed tick salivary glands, i.e., miR-1, miR-375, bantam, miR-184, miR-739, and miR-263a. We found that known miRNA homologs displayed a wide variety of expression profiles in unfed and fed tick salivary glands. After blood-feeding, 162 known miRNAs were upregulated. The six main upregulated miRNAs were mir-1810, mir-2138, mir-2140, mir-425*, mir-429, and mir-516*. Likewise, 231 known miRNAs were downregulated after blood-feeding. The six main downregulated miRNAs were miR-2941-1*, miR-10-5p, miR-2973, miR-1183, miR-4006b-5p, and miR-881. We found that distinct microRNA profiles in the salivary glands of H. longicornis were relating to tick blood feeding. The differential expression of miRNAs in unfed and fed tick salivary glands supported their involvement at new levels in the regulation of tick blood-feeding. Our data provide an important resource for a more detailed functional analysis of miRNAs in this species.

African swine fever virus-like integrated elements in a soft tick genome – an ancient virus vector arms race?

“…The distribution of the read lengths showed a distinct bimodal distribution in all libraries with one peak at 22nt, representing siRNAs, and one at 28-29nt, representing piRNAs (as shown by the typical U-bias at the 5'-end) ( Supplementary Table 10, and Supplementary Figure 1) (23). This is in accordance with small RNA sequencing data from hard ticks (24,25). By mapping the resulting data (siRNA and piRNA fractions) against the ASFLI-element-containing contigs, we identified siRNAs and piRNAs homologous to different ASFLI-elements ( Supplementary Figures 2 and 3).…”

In silico target network analysis of de novo-discovered, tick saliva-specific microRNAs reveals important combinatorial effects in their interference with vertebrate host physiology

“…There are only some restricted data on arthropod miRNAs in arthropod physiology (Lucas and Raikhel 2013;Luhur et al 2013;He et al 2015), especially in mosquitoes (for review, see Asgari 2014;Blair and Olson 2015). Knowledge about tick miRNAs is sparse and limited to sequences, potential tissue localization, and evolution in only five tick species (Barrero et al 2011;Zhou et al 2013;Luo et al 2015;Shao et al 2015;Wang et al 2015) and to their potential interactions with Flaviviruses (Tsetsarkin et al 2016). Accordingly, miRNAs have been reported in the literature for the following tick species (alphabetically): Haemaphysalis longicornis (Zhou et al 2013), Hyalomma anatolicum (Luo et al 2015), Rhipicephalus haemaphysaloides , Rhipicephalus (Boophilus) microplus (Barrero et al 2011), and Rhipicephalus sanguineus (Shao et al 2015).…”

Ixodes tick saliva suppresses the keratinocyte cytokine response to TLR2/TLR3 ligands during early exposure to Lyme borreliosis

“…The difference in concentration between OspC and the lipopeptide is therefore not as high, as calculated theoretically. This TLR crosstalk might also involve micro‐RNAs as they have been shown to be induced in KC inflammatory response induced by different TLR agonists and they are present in salivary glands of unfed and fed ticks . This aspect deserves further investigation as these miRNAs regulate gene expression and are involved in numerous processes such as cell proliferation, apoptosis and stress response.…”