保幼激素调控家蚕蜕皮激素合成的新机制

保幼激素（JH）和蜕皮激素（20E）协同调控昆虫生长和发育。已有研究报道表明，JH和20E的滴度随昆虫生长发育而发生此消彼长的周期性变化，且JH能抑制20E的合成；我们的前期研究显示，家蚕及果蝇20E合成酶基因启动子上含有JH信号转导关键分子Kr-h1的潜在结合位点，且家蚕Kr-h1过表达可抑制20E合成酶基因启动子的活性。这暗示Kr-h1可以直接抑制20E合成酶基因的转录。鉴于此，本项目拟以家蚕和果蝇为研究材料，综合利用基因敲除、转基因过表达、GAL4/UAS介导的RNAi、定量RT-PCR和转录组测序等方法，系统分析Kr-h1对20E合成酶基因转录的抑制作用；进一步通过荧光素酶报告基因分析、EMSA、ChIP及启动子DNA甲基化检测等实验，解析家蚕Kr-h1直接抑制20E合成酶基因转录的分子机制。相关研究结果有助于揭示家蚕JH调控20E合成的新机制，完善JH和20E的互作网络。

Juvenile hormone (JH) and 20-hydroxyecdysone (20E) cooperate to control the growth and development in insect. Previous reports demonstrated that the titers of JH and 20E exhibit periodic changes during insect larval development in a reciprocal manner. Our recent investigations showed that the promoters of the steroidogenic enzyme genes of the silkworm and fruit fly contain potential binding sites for transcription factor Kr-h1 that is involved in JH signaling. The overexpression of silkworm Kr-h1 significantly repressed the transcriptional activities of the steroidogenic enzyme gene promoters. These findings suggest that Kr-h1 may directly repress the transcription of the steroidogenic enzyme genes. In this study, using the silkworm and fruit fly as excellent models and combining the approaches of knock out, transgenic overexpression, GAL4/UAS mediated RNAi and real time RT-PCR, we are planning to systematically characterize the inhibitory roles of Kr-h1 in regulating the transcription of the steroidogenic enzyme genes. Furthermore, we will decipher the molecular mechanism underlying the Kr-h1 modulated inhibition of the transcription of the steroidogenic enzyme genes by using the methods of luciferase reporter assay, EMSA, ChIP, and DNA methylation analysis of the promoter region. We hope that the results from this study can provide new insights into the JH regulation of silkworm ecdysteroidogenesis and will be helpful for renewing the interaction network between JH and 20E in insect.