MicroRNA-1 promotes the development of and prolongs engorgement time inHyalomma anatolicum anatolicum(Acari: Ixodidae) ticks

Abstract

MicroRNAs act as mRNA posttranscriptional regulators, playing important roles in cell differentiation, transcriptional regulation, growth and development. In this study, microRNA expression profiles of Hyalomma anatolicum anatolicum ticks at different developmental stages were detected by high-throughput sequencing and functionally assessed. In total, 2,585,169, 1,252,678, 1,558,217 and 1,155,283 unique reads were obtained from eggs, larvae, nymphs and adults, respectively, with 42, 46, 45 and 41 conserved microRNAs in these stages, respectively. Using eggs as a control, 48, 43 and 39 microRNAs were upregulated and 3, 10 and 9 downregulated in larvae, nymphs and adults, respectively. microRNA-1 (miR-1) was expressed in high abundance throughout Ha. anatolicum development, with an average of nearly one million transcripts, and it is highly conserved among tick species. Quantitative real-time PCR (qPCR) showed that miR-1 expression gradually increased with tick development, reaching the highest level at engorgement. Differential tissue expression was detected, with significantly higher levels in the salivary glands and epidermis than in the midgut. Inhibition assays showed no significant change in body weight or spawning time or amount between experimental and control groups, but there was a significant difference (p<0.01) in engorgement time. With miR-1 inhibition, ticks displayed obvious deformities during later development. To more fully explain the microRNA mechanism of action, the miR-1 family was analyzed regarding target gene; members acting on Hsp60 include miR-5, miR-994, miR-969, and miR-1011, which jointly play a role. Therefore, microRNAs are critical for normal tick development, and the primary structure of the mature sequence of miR-1 is highly conserved. Nonetheless, different developmental stages and tissues show different expression patterns, with a certain role in prolonging feeding. miR-1, together with other family members, regulates mRNA function and may be used as a molecular marker for species origin and evolution analysis and internal reference gene selection.

Host Immune Responses to Salivary Components - A Critical Facet of Tick-Host Interactions

“…Although miRNAs have been identified and secreted via tick-derived EVs, limited studies have been conducted on the differential expression of miRNAs, with the exception of tick species that include all developmental stages of R. microplus ( Barrero et al., 2011 ), gender-based dynamics in R. sanguineus ( Shao et al., 2015 ), lipopolysaccharide-induced patterns in R. haemaphysaloides ( Wang et al., 2015 ), differential expression in SG of Hae. longicornis ( Zhou et al., 2013 ; Malik et al., 2019 ) and H. anatolicum ( Luo et al., 2021 ), and the saliva of I. ricinus ( Hackenberg et al., 2017 ). A subsequent study has shown the existence of some significant miRNAs in the EV-like structures secreted by tick sialome (36 known and 34 novel miRNAs), which may be used in tick–host interface modulation ( Nawaz et al., 2020 ).…”