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昆虫蜕皮激素(20-羟基蜕皮酮)与蜕皮激素受体(EcR)和超气门蛋白(USP)相互作用启动蜕皮级联反应过程,由EcR和USP组成的复合物是蜕皮激素的作用靶标.为研究家蚕EcR-A基因(BmEcR-A)的转录调控机制,利用双荧光素酶报告系统和Bac-to-Bac表达系统制备含5'端长度不同BmEcR-A基因启动子片段的重组杆状病毒,分别将重组杆状病毒感染家蚕后检测启动子的活性.结果表明,在BmEcR-A启动子的-637～-518 bp和-278～-177 bp区域存在正调控元件,并且能被0.002g/L 20E诱导.通过构建含5 '端长度不同BmEcR-A启动子片段的荧光素酶报告质粒,在细胞水平上进一步分析BmEcR-A启动子活性区域,结果显示:在-637～-612 bp和-278～-177 bp区域包含BmEcR-A基因启动子转录调控必需的重要调控元件;当删除-197～-177 bp区域后,启动子活性明显增强,推测在该区域可能含有一个转录抑制因子结合位点.研究结果提示:上述启动子区域包含有转录调控元件的结合位点,是进一步研究BmEcR-A启动子核心区域的重要线索.“,”Insect molting hormone (20-hydroxyecdysone,20E) interacts with ecdysone receptor (EcR) and ultraspiracle protein (USP) to initiate the cascade reaction of molting process.EcR and USP complex is the target of ecdysone action.In order to analyze the transcriptional regulatory mechanism of Bombyx mori EcR-A gene (BmEcR-A),dual-luciferase reporter assay and Bac-to-Bac expression system were employed to prepare recombinant baculoviruses containing various 5'-end truncated promoter fragments of BmEcR-A gene.The prepared recombinant baculoviruses were used to infect silkworm for measuring promoter activity.The results showed that there existed positive regulatory elements at position-637 to-518 bp and-278 to-177 bp in BmEcR-A promoter region,both of which could be induced by 0.002 g/L 20E.Through construction of luciferase reporter plasmid containing various lengths of 5'-end truncated BmEcR-A promoter for further analysis of BmEcR-A promoter activity at cellular level,it was found that the fragment of -637 to-612 bp and-278 to-177 bp contained important regulatory elements that were necessary for transcriptional regulation of BmEcR-A promoter.When the fragment of-197 to-177 bp was deleted,the promoter activity was obviously increased,suggesting that this region contains potential binding site of transcriptional repressor.These data demonstrate that the above promoter region contains binding sites of transcriptional regulators,which is an important clue for further investigation on core promoter region of BmEcR-A gene.