Role of the venus kinase receptor in the female reproductive physiology of the desert locust, Schistocerca gregaria

Cynthia Lenaerts,Jolien Palmans,Rik Verdonck,Jozef Vanden Broeck,Elisabeth Marchal

doi:10.1038/s41598-017-11434-3

Cynthia Lenaerts, Jolien Palmans + Show 3 more

Open Access

https://doi.org/10.1038/s41598-017-11434-3

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Journal: Scientific Reports	Publication Date: Sep 15, 2017
Citations: 11	License type: open-access

Affiliation: KU Leuven

Abstract

Venus kinase receptors (VKR) are a subfamily of invertebrate receptor tyrosine kinases, which have only recently been discovered. They contain an intracellular tyrosine kinase domain and an extracellular Venus FlyTrap domain. VKRs have been functionally and pharmacologically characterized in only two invertebrate species, namely the human parasite Schistosoma mansoni and the mosquito Aedes aegypti, where they play a crucial role in oogenesis. Here, we report the characterization of a VKR in the desert locust, Schistocerca gregaria. We performed an in-depth profiling study of the SgVKR transcript levels in different tissues throughout the female adult stage. Using the RNA interference technique, the possible role of SgVKR was investigated. SgVKR knockdown had significant effects on ovarian ecdysteroid levels and on the size of oocytes during the vitellogenic stage. SgVKR is probably involved in the complex cross-talk between several important pathways regulating female reproductive physiology. Contrary to A. aegypti and S. mansoni, we cannot conclude that this receptor is essential for reproduction, since silencing SgVKR did not affect fecundity or fertility. Considering the evolutionary distance between A. aegypti and S. gregaria, as well as the differences in regulation of their female reproductive physiology, this article constitutes a valuable asset in better understanding VKRs.

Highlights

In 2003, a novel receptor tyrosine kinase (RTK) was discovered in the human parasite, Schistosoma mansoni[1]
The TK domain of Venus kinase receptors (VKR) closely resembles that of insulin-like peptide receptors (InR) and contains all motifs that are crucial for tyrosine kinase activity, such as the ATP binding site (GxGxxG), the catalytic loop implicated in the phosphotransfer (HRDxAxRN), and the two putative autophosphorylation sites (YY)[4]
Based on similarities with previously predicted and identified VKRs2,4, we identified the typical VFT module (VFTM) and TK domains (Fig. 1, grey and black highlights)

Summary

Introduction

In 2003, a novel receptor tyrosine kinase (RTK) was discovered in the human parasite, Schistosoma mansoni[1]. RNAi-mediated knockdown of AaVKR resulted in significantly lower ecdysteroid and vitellogenin production, leading to disabled egg formation. Another proof of AaVKR being the OEH receptor, was the lack of vitellogenin biosynthesis in the dsVKR treated females upon injection of OEH5. Neuroparsins act as anti-gonadotropic factors in S. gregaria, while in A. aegypti the neuroparsin-like OEH exerts a gonadotropic role. Given these differences in the regulation of female reproductive physiology between A. aegypti and S. gregaria, this study represents a valuable asset to better understand the role of the VKR subfamily throughout evolution. Using RNAi, we investigate the possible cross-talk of this receptor with several major hormonal pathways involved in female reproductive physiology, as well as its role in the maturation of oocytes, copulation behavior and post-copulation events

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