Functional Analysis of Insect Molting Fluid Proteins on the Protection and Regulation of Ecdysis*
Functional Analysis of Insect Molting Fluid Proteins on the Protection and Regulation of Ecdysis*
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DOI：
10.1074/jbc.m114.599597
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发表时间：
2014-11
期刊：
影响因子：
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通讯作者：
Jie Zhang;A. Lu;Lulu Kong;Qiaoli Zhang;E. Ling
中科院分区：
文献类型：
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作者：
Jie Zhang;A. Lu;Lulu Kong;Qiaoli Zhang;E. Ling
背景：昆虫发生周期性蜕皮，蜕皮液在新旧角质层中积累。结果：蜕皮液是一种含有多种未知蛋白的混合物，具有抑制微生物感染和调节蜕皮的作用。结论：昆虫产生蜕皮液是为了保护纤弱昆虫，保证蜕皮成功。意义：蜕皮蛋白可能是未来农药开发的有用靶点。蜕皮虫周期性蜕皮时，蜕皮液在新旧角质层之间积累。昆虫蜕皮的自然缺陷通常与主要发生在蜕皮液中的黑化（一种免疫反应）有关，这表明蜕皮液可能影响免疫，也可能影响蜕皮。为了解决这一假设，蛋白质组学分析了家蚕在三种不同类型的蜕皮过程中的蜕皮液。在每一种蜕皮液中都新发现了许多蛋白质，包括与免疫相关的蛋白质。换毛液在体外抑制细菌的生长。球孢白僵菌（Beauveria bassiana）是一种昆虫病原真菌，它可以逃避幼虫的免疫反应，在蜕皮过程中被幼虫迅速识别，随后在蜕皮液和旧角质层中发生黑色素化。真菌分生孢子萌发延迟，且在pharate龄期昆虫血液中未检测到菌丝。蜕皮液保护表皮极薄的脆弱的pharate稚虫免受微生物的侵害。为了探究蜕皮液在蜕皮调控中的作用，基于蛋白相似性，选择32个基因对Tribolium castaneum的蜕皮调控进行RNAi分析。Tribolium castaneum是一种研究被膜发育的常用模型，因为在家蚕中很难实现RNAi。我们发现了24种脱毛蛋白在敲除后会影响蜕皮，它们具有不同的生理功能，包括旧角质层蛋白的循环利用、蜕皮液压力平衡、脱毒以及蜕皮液的信号检测和传递。我们报道了昆虫分泌蜕皮液对蜕皮的保护和调节作用，这为今后通过阻断昆虫蜕皮开发新型农药指明了一条途径。
Background: Periodical ecdysis occurs in insects with molting fluids accumulated among the old and new cuticles. Results: Molting fluid is a mixture containing many unknown proteins to inhibit microbian infection and regulate ecdysis. Conclusion: Insects produce molting fluids for protecting delicate insects and guaranteeing successful ecdysis. Significance: Molting proteins may be targets useful for pesticide development in the future. Molting fluid accumulates between the old and new cuticles during periodical ecdysis in Ecdysozoa. Natural defects in insect ecdysis are frequently associated with melanization (an immunity response) occurring primarily in molting fluids, suggesting that molting fluid may impact immunity as well as affect ecdysis. To address this hypothesis, proteomic analysis of molting fluids from Bombyx mori during three different types of ecdysis was performed. Many proteins were newly identified, including immunity-related proteins, in each molting fluid. Molting fluids inhibited the growth of bacteria in vitro. The entomopathogenic fungi Beauveria bassiana, which can escape immune responses in feeding larvae, is quickly recognized by larvae during ecdysis, followed by melanization in molting fluid and old cuticle. Fungal conidia germination was delayed, and no hyphae were detected in the hemocoels of pharate instar insects. Molting fluids protect the delicate pharate instar insects with extremely thin cuticles against microorganisms. To explore the function of molting fluids in ecdysis regulation, based on protein similarity, 32 genes were selected for analysis in ecdysis regulation through RNAi in Tribolium castaneum, a model commonly used to study integument development because RNAi is difficult to achieve in B. mori. We identified 24 molting proteins that affected ecdysis after knockdown, with different physiological functions, including old cuticle protein recycling, molting fluid pressure balance, detoxification, and signal detection and transfer of molting fluids. We report that insects secrete molting fluid for protection and regulation of ecdysis, which indicates a way to develop new pesticides through interrupting insect ecdysis in the future.