The Drosophila Zinc Finger Transcription Factor Ouija Board Controls Ecdysteroid Biosynthesis through Specific Regulation of spookier.
The Drosophila Zinc Finger Transcription Factor Ouija Board Controls Ecdysteroid Biosynthesis through Specific Regulation of spookier.
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DOI：
10.1371/journal.pgen.1005712
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发表时间：
2015-12
期刊：
影响因子：
4.5
通讯作者：
Niwa R
中科院分区：
文献类型：
--
作者：
Komura-Kawa T;Hirota K;Shimada-Niwa Y;Yamauchi R;Shimell M;Shinoda T;Fukamizu A;O'Connor MB;Niwa R
类固醇激素对于多细胞生物中的许多生物事件至关重要。在昆虫中，主要的类固醇激素是蜕皮类固醇，它在调节蜕皮和变态中发挥重要作用。在幼虫和蛹发育过程中，脱皮类固醇是在前胸腺（PG）中通过一系列羟基化和氧化步骤从膳食胆固醇合成的。除一种已知的蜕皮类固醇生物合成酶外，所有的表达均仅限于 PG，但负责产生如此精致的组织特异性调节的转录调节网络才刚刚开始被阐明。在这里，我们报告了果蝇果蝇 PG 中蜕皮类固醇产生所必需的 C2H2 型锌指转录因子显灵板 (Ouib) 的鉴定和表征。 ouib 的表达主要限于 PG，ouib 基因无效突变体会导致幼虫发育停滞，可以通过施用活性蜕皮类固醇来挽救。有趣的是，ouib 突变动物表现出一种蜕皮类固醇生物合成酶表达的强烈减少，更令人毛骨悚然。使用基于细胞培养的荧光素酶报告基因测定，Ouib 蛋白通过与 spok PG 增强子元件中特定的约 15 bp 响应元件结合来刺激 spok 的转录。最值得注意的是，ouib 突变体的发育停滞表型是通过功能等效的 spookier 旁系同源物的过度表达来挽救的。这些观察结果表明，Ouib 的主要生物学功能是在果蝇发育过程中特异性调节令人毛骨悚然的转录。类固醇激素对于多细胞生物的发育和繁殖至关重要。几乎所有类固醇生物合成基因的空间限制性表达是类固醇生成细胞特化的关键。在过去的十年中，昆虫已成为主要类固醇激素——蜕皮类固醇生物合成研究的焦点。然而，控制蜕皮类固醇生物合成基因的转录调控机制在很大程度上尚不清楚。在这里，我们展示了一种新型锌指转录因子通灵板（Ouib）对于激活一种蜕皮类固醇生物合成基因的表达至关重要，这种基因在蜕皮类固醇产生细胞中更为诡异。 Ouib 是第一个主要在类固醇生成器官中表达的无脊椎动物转录因子，并且通过诱导类固醇生成基因的表达对于发育至关重要。此外，这是第一份显示通过转录调控对类固醇激素生物合成进行催化步骤特异性控制的报告。
Steroid hormones are crucial for many biological events in multicellular organisms. In insects, the principal steroid hormones are ecdysteroids, which play essential roles in regulating molting and metamorphosis. During larval and pupal development, ecdysteroids are synthesized in the prothoracic gland (PG) from dietary cholesterol via a series of hydroxylation and oxidation steps. The expression of all but one of the known ecdysteroid biosynthetic enzymes is restricted to the PG, but the transcriptional regulatory networks responsible for generating such exquisite tissue-specific regulation is only beginning to be elucidated. Here, we report identification and characterization of the C2H2-type zinc finger transcription factor Ouija board (Ouib) necessary for ecdysteroid production in the PG in the fruit fly Drosophila melanogaster. Expression of ouib is predominantly limited to the PG, and genetic null mutants of ouib result in larval developmental arrest that can be rescued by administrating an active ecdysteroid. Interestingly, ouib mutant animals exhibit a strong reduction in the expression of one ecdysteroid biosynthetic enzyme, spookier. Using a cell culture-based luciferase reporter assay, Ouib protein stimulates transcription of spok by binding to a specific ~15 bp response element in the spok PG enhancer element. Most remarkable, the developmental arrest phenotype of ouib mutants is rescued by over-expression of a functionally-equivalent paralog of spookier. These observations imply that the main biological function of Ouib is to specifically regulate spookier transcription during Drosophila development. Steroid hormones are crucial for development and reproduction in multicellular organisms. The spatially-restricted expression of almost all steroid biosynthesis genes is key to the specialization of steroid producing cells. In the last decade, insects have become the focus for research on the biosynthesis of the principal steroid hormones, ecdysteroids. However, the transcriptional regulatory mechanisms controlling the ecdysteroid biosynthesis genes are largely unknown. Here we show that a novel zinc finger transcription factor Ouija board (Ouib) is essential for activating the expression of one ecdysteroid biosynthesis gene, spookier, in the ecdysteroid producing cells. Ouib is the first invertebrate transcription factor that is predominantly expressed in the steroidogenic organs and essential for development via inducing expression of the steroidogenic gene. In addition, this is the first report showing the catalytic step-specific control of steroid hormone biosynthesis through transcriptional regulation.