类固醇激素在整个动物生命周期中影响各种生物过程,包括新陈代谢,抗应力,繁殖,和寿命。在昆虫中,类固醇激素,20-羟基蜕皮激素(20E),是蜕皮和变态的中枢激素调节剂,并在组织形态发生中起作用。例如,羊膜膜收缩,这是果蝇背侧闭合(DC)的主要驱动力,20E生物合成的胚胎突变体有缺陷。这里,我们发现20E信号调节了晚期胚胎发育过程中羊膜和其他背侧组织中几个DC参与者的转录,包括拉链,编码非肌肉肌球蛋白。典型的蜕皮激素信号传导通常涉及蜕皮激素受体(EcR)和Ultraspacle异二聚体与响应基因启动子内的蜕皮激素响应元件(EcRE)的结合,以驱动表达。在DC期间,然而,我们提供的证据表明,20E信号传导通过EcR和AP-1转录因子亚基之间的直接相互作用与JNK级联平行,Jun,它们一起与含有AP-1结合位点但没有EcRE的基因组区域结合以控制基因表达。我们的工作证明了果蝇中20E信号的一种新的作用方式,可能在DC之外发挥作用,并可能提供对哺乳动物类固醇激素受体与AP-1相互作用的进一步见解。
Steroid hormones influence diverse biological processes throughout the animal life cycle, including metabolism, stress resistance, reproduction, and lifespan. In insects, the steroid hormone, 20-hydroxyecdysone (20E), is the central hormone regulator of molting and metamorphosis, and plays roles in tissue morphogenesis. For example, amnioserosa contraction, which is a major driving force in Drosophila dorsal closure (DC), is defective in embryos mutant for 20E biosynthesis. Here, we show that 20E signaling modulates the transcription of several DC participants in the amnioserosa and other dorsal tissues during late embryonic development, including zipper, which encodes for non-muscle myosin. Canonical ecdysone signaling typically involves the binding of Ecdysone receptor (EcR) and Ultraspiracle heterodimers to ecdysone-response elements (EcREs) within the promoters of responsive genes to drive expression. During DC, however, we provide evidence that 20E signaling instead acts in parallel to the JNK cascade via a direct interaction between EcR and the AP-1 transcription factor subunit, Jun, which together binds to genomic regions containing AP-1 binding sites but no EcREs to control gene expression. Our work demonstrates a novel mode of action for 20E signaling in Drosophila that likely functions beyond DC, and may provide further insights into mammalian steroid hormone receptor interactions with AP-1.