Faculty of Agriculture, Utsunomiya University, Utsunomiya, Tochigi, Japan.
Arch Insect Biochem Physiol. 2024 Aug;116(4):e22143. doi: 10.1002/arch.22143.
JH and ecdysone signaling regulate insect metamorphosis through the master transcription factors, Krüppel homolog 1 (kr-h1), Broad-Complex (BR-C), and E93. Ecdysone signaling activates successively expressed ecdysone responsive transcription factors (ERTFs), and the interaction between ERTFs determines the expression profiles of ERTFs themselves. Through the construction of expressed sequence tag (EST) database of Bombyx mori from many tissues, the existence of a large number of cuticular protein (CP) genes was identified in wing disc cDNA library of the 3 days after the start of wandering (W3). From the genomic analysis, 12 types of CP clusters of CP genes were identified. DNA sequences of CP genes revealed the duplication of CP genes, which suggests to reflect the insect evolution. These CP genes responded to ecdysone and ecdysone pulse; therefore, CP genes were applied for the analysis of transcriptional regulation by ERTF. The binding sites of ERTF have been reported to exist upstream of CP genes in several insects, and the activation of CP genes occurred by the binding of ERTFs. Through the analysis, the following were speculated; the successive appearance of ERTFs and the activation of target genes resulted in the successively produced CPs and cuticular layer. The sequence of the ERTF and CP gene expression was the same at larval to pupal and pupal to adult transformation. The involvement of several ERTFs in one CP gene expression was also clarified; BmorCPG12 belongs to group showing expression peak at W3 and was regulated by two ERTFs; BHR3 and ßFTZ-F1, BmorCPH2 belongs to group showing expression peak at P0 and was regulated by two ERTFs; ßFTZ-F1 and E74A. The involvement of BHR39 as a negative regulator of CP gene expression was found. Larval, pupal, and adult cuticular layers were supposed to be constructed by the combination of different and similar types of CPs, through the expressed timing of CP genes.
JH 和蜕皮激素信号通过主转录因子 Krüppel 同源物 1 (kr-h1)、宽复合体 (BR-C) 和 E93 调节昆虫变态。蜕皮激素信号激活依次表达的蜕皮激素反应转录因子 (ERTF)，ERTF 之间的相互作用决定了 ERTF 自身的表达谱。通过构建来自多种组织的家蚕表达序列标签 (EST) 数据库，在起始蜕皮后 3 天 (W3) 的翅盘 cDNA 文库中鉴定出大量表皮蛋白 (CP) 基因的存在。从基因组分析中，鉴定出 12 种 CP 基因簇。CP 基因的 DNA 序列揭示了 CP 基因的复制，这表明反映了昆虫的进化。这些 CP 基因对蜕皮激素和蜕皮激素脉冲有反应；因此，CP 基因被应用于 ERTF 转录调控的分析。已经报道在几种昆虫中，ERTF 的结合位点存在于 CP 基因的上游，CP 基因的激活是通过 ERTF 的结合发生的。通过分析，推测 ERTF 的相继出现和靶基因的激活导致了相继产生的 CPs 和表皮层。ERTF 和 CP 基因表达的序列在幼虫到蛹和蛹到成虫的转化中是相同的。几个 ERTF 参与一个 CP 基因表达的情况也得到了澄清；BmorCPG12 属于在 W3 表达峰出现的组，由两个 ERTF 调节；BHR3 和ßFTZ-F1，BmorCPH2 属于在 P0 表达峰出现的组，由两个 ERTF 调节；ßFTZ-F1 和 E74A。发现 BHR39 作为 CP 基因表达的负调节剂参与其中。幼虫、蛹和成虫的表皮层通过 CP 基因表达的不同和相似类型的组合来构建，通过 CP 基因的表达时间。
