Hou Qiu-Li, Chen Er-Hu, Jiang Hong-Bo, Wei Dan-Dan, Gui Shun-Hua, Wang Jin-Jun, Smagghe Guy
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400715, PR China; Academy of Agricultural Sciences, Southwest University, Chongqing 400715, PR China.
Key Laboratory of Entomology and Pest Control Engineering, College of Plant Protection, Southwest University, Chongqing 400715, PR China; Academy of Agricultural Sciences, Southwest University, Chongqing 400715, PR China.
Insect Biochem Mol Biol. 2017 Nov;90:1-13. doi: 10.1016/j.ibmb.2017.09.006. Epub 2017 Sep 15.
Energy homeostasis requires continuous compensation for fluctuations in energy expenditure and availability of food resources. In insects, energy mobilization is under control of the adipokinetic hormone (AKH) where it is regulating the nutritional status by supporting the mobilization of lipids. In this study, we characterized the gene coding for the AKH receptor (AKHR) and investigated its function in the oriental fruit fly (Bactrocera dorsalis) that is economically one of the most important pest insects of tropical and subtropical fruit. Bacdo-AKHR is a typical G protein-coupled receptor (GPCR) and phylogenetic analysis confirmed that Bacdo-AKHR is closely related to insect AKHRs from other species. When expressed in Chinese hamster ovary (CHO) cells, Bacdo-AKHR exhibited a high sensitivity and selectivity for AKH peptide (EC = 19.3 nM). Using qPCR, the developmental stage and tissue-specific expression profiles demonstrated that Bacdo-AKHR was highly expressed in both the larval and adult stages, and also specifically in the fat body and midgut of the adult with no difference in sex. To investigate the role of AKHR in B. dorsalis, RNAi assays were performed with dsRNA against Bacdo-AKHR in adult flies of both sexes and under starvation and feeding condition. As major results, the knockdown of this gene resulted in triacylglycerol (TAG) accumulation. With RNAi-males, we observed a severe decrease in their sexual courtship activity when starved, but there was a partial rescue in copulation when refed. Also in RNAi-males, the tethered-flight duration declined compared with the control group when starved, which is confirming the dependency on energy metabolism. In RNAi-females, the sexual behavior was not affected, but their fecundity was decreased. Our findings indicate an interesting role of AKHR in the sexual behavior of males specifically. The effects are associated with TAG accumulation, and we also reported that the conserved role of AKH-mediated system in B. dorsalis is nutritional state-dependent. Hence, we provided further understanding on the multiple functions of AKH/AKHR in B. dorsalis.
能量稳态需要持续补偿能量消耗和食物资源可用性的波动。在昆虫中，能量动员受促脂动激素（AKH）控制，它通过支持脂质动员来调节营养状态。在本研究中，我们对促脂动激素受体（AKHR）的编码基因进行了表征，并研究了其在东方果实蝇（Bactrocera dorsalis）中的功能，东方果实蝇是热带和亚热带水果经济上最重要的害虫之一。Bacdo-AKHR是一种典型的G蛋白偶联受体（GPCR），系统发育分析证实Bacdo-AKHR与其他物种的昆虫AKHR密切相关。当在中国仓鼠卵巢（CHO）细胞中表达时，Bacdo-AKHR对AKH肽表现出高敏感性和选择性（EC = 19.3 nM）。使用qPCR，发育阶段和组织特异性表达谱表明Bacdo-AKHR在幼虫和成虫阶段均高表达，并且在成虫的脂肪体和中肠中也特异性表达，无性别差异。为了研究AKHR在桔小实蝇中的作用，在饥饿和进食条件下，对两性成年果蝇进行了针对Bacdo-AKHR的dsRNA的RNA干扰试验。主要结果是，该基因的敲低导致三酰甘油（TAG）积累。对于RNA干扰雄性果蝇，我们观察到饥饿时其求偶活动严重下降，但重新喂食后交配有所恢复。同样在RNA干扰雄性果蝇中，饥饿时与对照组相比，系留飞行持续时间下降，这证实了对能量代谢的依赖性。在RNA干扰雌性果蝇中，性行为未受影响，但繁殖力下降。我们的研究结果表明AKHR在雄性性行为中具有有趣的作用。这些影响与TAG积累有关，并且我们还报道了AKH介导的系统在桔小实蝇中的保守作用是营养状态依赖性的。因此，我们对桔小实蝇中AKH/AKHR的多种功能有了进一步的了解。
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