组蛋白H3K27甲基化修饰调控家蚕蜕皮激素合成的分子机制研究

蜕皮激素（20E）参与昆虫生长发育调节，其合成调控机制研究具有重要理论意义和应用价值；组蛋白H3第27位赖氨酸三甲基化（H3K27me3）是一种表观遗传修饰，其在动植物基因表达沉默及生长发育中发挥关键作用。本项目前期研究发现，家蚕和果蝇20E合成器官前胸腺中H3K27me3甲基化水平的降低可抑制20E合成酶基因转录及20E合成，并导致幼虫不能向蛹变态发育，但具体作用机制尚不清楚。鉴于此，本项目拟综合应用基因敲除、RNAi、转基因过表达、ChIP-seq、RNA-seq、EMSA等方法，深入分析H3K27me3甲基化修饰在家蚕和果蝇20E合成及生长发育过程中的功能，鉴定前胸腺中H3K27me3甲基化修饰作用的靶基因并解析靶基因对20E合成的调控机制。相关研究结果有助于丰富完善昆虫20E合成及变态发育的表观遗传调控机制，并可为家蚕生长发育性状的定向遗传改造以及农林害虫的生物防治提供新的线索。

The steroid hormone 20-hydroxyecdysone (20E) is involved in the control of insect growth and development and the study on regulatory mechanism underlying 20E biosynthesis has great theoretical significance and potential application. The trimethylation at lysine 27 of histone H3 (H3K27me3) is an epigenetic marker and plays important roles in gene silencing and developmental programming in the animal and plant kingdoms. Our recent investigations in silkworm and fruit fly showed that the reduction of the H3K27me3 levels in 20E-producing organ prothoracic gland repressed both the transcription of the steroidogenic enzyme genes and 20E biosynthesis, and disrupted larval-pupal transition. However, the molecular mechanism of H3K27me3 regulation on 20E biosynthesis remains unclear. Therefore, in this study, by using multiple approaches including knockout, RNAi, transgenic overexpression, ChIP-seq, RNA-seq, and EMSA, we are planning to systematically characterize the effects of H3K27me3 modification on 20E biosynthesis and developmental transition in silkworm and fruit fly, to identify potential targets of H3K27me3 modification in the prothoracic gland, and to decipher the regulatory mechanism of H3K27me3 targets in 20E biosynthesis. The results from this study will not only update the epigenetically regulatory network of both 20E biosynthesis and development in insect, but also provide novel clues for genetic manipulation of silkworm development and biological control of agricultural and forestry pests.