Ovary Proteome Analysis Reveals RH36 Regulates Reproduction via Vitellin Uptake Mediated by HSP70 Protein in Hard Ticks.

Fangfang Wang,Guanghua Wang,Jinlin Zhou,Jie Cao,Yongzhi Zhou,Houshuang Zhang,Ceyan Kuang,Yanan Wang

doi:10.3389/fcimb.2020.00093

Abstract

Ticks are blood-sucking vector arthropods, which play an important role in transmitting pathogens between humans and animals. RH36 is an immunomodulatory protein expressed in the salivary glands, but not other organs, of partially fed Rhipicephalus haemaphysaloides ticks, and it reaches its peak on the day of tick engorgement. RH36 gene silencing inhibited tick blood feeding and induced a significant decrease in tick oviposition, indicating that another function of immunosuppressor RH36 was regulating tick reproduction. Why did RH36 protein expressed uniquely in the salivary gland regulate tick reproduction? RH36 regulated positively the expression of vitellogenin in ovary, which indicated RH36 protein played an important role in the integration of nutrition and reproduction. According to proteomic analysis, heat shock protein 70 (HSP70) was significantly down-regulated in the immature ovary of post-engorged ticks. In addition, gene silencing of HSP70 not only inhibited tick blood-sucking and the expression of vitellogenin, but also increased tick death rate. These results suggested RH36 affected tick vitellogenin uptake and then regulated ovary cell maturation by modulating the expression of HSP70 protein, and finally controlled tick oviposition.

Highlights

Ticks transmit a wide range of zoonosis, such as tick-borne encephalitis (Grabowski et al, 2017), Lyme disease (Ehrmann et al, 2018), tick-borne spotted fever (Han et al, 2018), anaplasmosis (Parola and Raoult, 2001; Eisen and Eisen, 2018), and babesiosis (Kotal et al, 2015)
RH36 protein was expressed at higher levels in 7-day-fed and saturated ticks and subsequently decreased after engorgement, which was highly consistent with the time of tick ovarian development (Figure 1B)
RH36 was induced by blood feeding and expressed in salivary glands, but not in other organs such as ovary and hemolymph (Figure 1)

Summary

Introduction

Ticks transmit a wide range of zoonosis, such as tick-borne encephalitis (Grabowski et al, 2017), Lyme disease (Ehrmann et al, 2018), tick-borne spotted fever (Han et al, 2018), anaplasmosis (Parola and Raoult, 2001; Eisen and Eisen, 2018), and babesiosis (Kotal et al, 2015). These pathogens are transmitted via tick saliva to their vertebrate host when ticks feed on host. Based on 3D structures of P36 from Dermacentor andersoni, a predicted conserved antigenic region was identified, located

Methods

Results

Conclusion