管氏肿腿蜂毒液IMP-L2通过胰岛素信号通路抑制寄主生长发育的作用机制

Due to the unique physiology functions associated with parasitoid venoms, they are appealing potentially pest control agents. So far, only few venom proteins from parasitoids have been functionally clarified, and the mechanisms of how they act the physiological function is unclear. Previously, we found that IMP-L2 is rich in the venom of Scleroderma guani with the ability to reduce pupal weight of its host, Tenebrio molitor. With the recent advantages of the relationship between IMP-L2 and insulin like peptide at the upstream of insulin signaling pathway involved in developmental regulation in Drosophila, we hypothesize that hosts development would be inhibited by IMP-L2 in venom of S. guani via insulin signaling pathway. Based on previously accumulated achievements, this program aims to confirm this hypothesis from the following aspects. Firstly, the venomous IMP-L2 gene of S. guani will be cloned and expressed. The binding of this venom protein to insulin like peptides of T. molitor will be characterized. The regulation of all member genes of insulin signaling pathway of T. molitor by this venom protein will be clarified. Also, the physiological response of T. molitor to this regulation will be assessed. By comprehensive analysis of results derived from this program, the mechanism of hosts development inhibited by venomous IMP-L2 of S. guani via insulin signaling pathway will be illustrated. This study will facilitate us to reveal the functional action mechanism of parasitoid venoms and the regulatory mechanism at the upstream of insulin signaling pathway. Additionally, the cloned venom gene would be used to develop new insecticides or transgenic resistant plants.

寄生蜂毒液因具独特的生理功能而在害虫防治中有很高的潜在利用价值，但至今仅极少数毒液蛋白的功能被探明，且其发挥生理功能的作用机理尚不清楚。申请者前期研究发现管氏肿腿蜂毒液富含IMP-L2并初步证实其能降低寄主黄粉甲蛹的体重，基于果蝇IMP-L2与调控生长发育相关的胰岛素信号通路上游的类胰岛素多肽关系研究新进展，提出“管氏肿腿蜂毒液IMP-L2通过胰岛素信号通路抑制寄主生长发育”的假设。本项目拟在上述研究基础上，克隆表达管氏肿腿蜂毒液IMP-L2基因，解析该毒液蛋白与黄粉甲类胰岛素多肽的互作，探明其对黄粉甲胰岛素信号通路成员的调控，明确其调控胰岛素信号通路而引起的黄粉甲生理响应，最终阐明毒液IMP-L2通过胰岛素信号通路抑制寄主生长发育的作用机制。本研究不仅有助于揭示寄生蜂毒液功能蛋白的作用机理以及胰岛素信号通路的上游调控机制，而且克隆获得的毒液基因有望用于研发新型杀虫制剂或转基因抗虫植物。

寄生蜂毒液具有独特的生理功能，在害虫防治中有很高的潜在利用价值，但至今仅极少数毒液蛋白的功能及其作用机理被探明。本项目以管氏肿腿蜂为研究对象，在前期初步研究提示该蜂毒液IMP-L2具有抑制寄主生长发育功能的基础上，旨在揭示内在的机制，开展了系列研究，取得了以下研究结果：克隆获得了管氏肿腿蜂毒液IMP-L2基因，明确了其在不同组织和发育阶段的表达特征，发现寄生能上调其表达量；成功利用杆状病毒表达载体对管氏肿腿蜂毒液IMP-L2基因进行了真核表达，并纯化得到了其基因表达产物；初步鉴定获得了与管氏肿腿蜂毒液IMP-L2互作的潜在寄主蛋白；发现管氏肿腿蜂毒液IMP-L2能调控寄主胰岛素/雷帕霉素（IIS/TOR）和激素（保幼激素和蜕皮激素）信号通路，并影响寄主的营养代谢。现有研究结果分析表明，管氏肿腿蜂毒液IMP-L2通过与潜在的寄主蛋白互作，进而调控寄主IIS/TOR和激素信号通路以及营养代谢，最终导致寄主生长发育受到抑制。研究结果，不仅有助于揭示寄生蜂毒液抑制寄主生长发育的机制，而且丰富和发展了寄生蜂与寄主互作的分子机理。

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