The Drosophila short gastrulation gene prevents Dpp from autoactivating and suppressing neurogenesis in the neuroectoderm
The Drosophila short gastrulation gene prevents Dpp from autoactivating and suppressing neurogenesis in the neuroectoderm
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DOI：
10.1101/gad.10.22.2922
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发表时间：
1996-11-15
影响因子：
10.5
通讯作者：
Bier, E
中科院分区：
文献类型：
--
作者：
Biehs, B;Francois, V;Bier, E
短胃（SOG）基因在包含果蝇胚胚胚的神经外胚层的宽外侧条带中表达。 SOG编码一种预测的分泌蛋白质，该蛋白质非自主功能拮抗胚胎背侧区域中TGF-beta样脱皮术（DPP）信号通路的活性。最近，已经显示SOG和DPP在功能上等同于它们各自的Xenopus同源物Chordin和BMP-4。在本报告中，我们提供了第一个直接证据，表明SOG在胚胚胚的侧面区域扮演局部角色，以反对神经外胚层中的DPP活性。在背区域，DPP信号既抑制神经发生，又保持了促进背细胞命运的基因的表达（背面化）。我们表明，DPP还可以在神经外胚层中执行这两个功能。在野生型胚胎中，DPP诱导神经外胚层中包括本身（自动激活）的背面标记表达的能力被SOG阻断。我们建议SOG保护神经外胚层免受DPP扩散和自动激活产生的侵入性正反馈回路。我们表明，DPP信号传导的两个函数，神经抑制和背面是由DPP活性的不同阈值触发的。上科斯的实验表明，所有观察到的SOG活性都可以通过发挥专用DPP拮抗剂的SOG来解释。最后，我们提供了证据表明，SOG在胚胚胚中充当可扩散的形态学。这些数据强烈支持以下观点：果蝇SOG和DPP基因的一级系统发育保守的功能以及同源的爪诺替蛋白和BMP-4基因是将原始胚胎过胚层分散到神经和非神经域。
The short gastrulation (sog) gene is expressed in broad lateral stripes comprising the neuroectoderm of the Drosophila blastoderm embryo. sog encodes a predicted secreted protein that functions nonautonomously to antagonize the activity of the TGF-beta-like Decapentaplegic (Dpp) signaling pathway in the dorsal region of the embryo. Recently, it has been shown that sog and dpp are functionally equivalent to their respective Xenopus homologs chordin and BMP-4. In this report we provide the first direct evidence that sog plays a local role in the lateral region of the blastoderm embryo to oppose Dpp activity in the neuroectoderm. In the dorsal region, Dpp signaling both suppresses neurogenesis and maintains expression of genes that promote dorsal cell fates (dorsalization). We show that Dpp also can perform both of these functions in the neuroectoderm. In wild-type embryos, the ability of Dpp to induce expression of dorsal markers including itself (autoactivation) in the neuroectoderm is blocked by sog. We propose that Sog protects the neuroectoderm from an invasive positive feedback loop created by Dpp diffusion and autoactivation. We show that the two functions of Dpp signaling, neural suppression and dorsalization, are triggered by distinct thresholds of Dpp activity. Epistasis experiments reveal that all observed sog activity can be accounted for by Sog functioning as a dedicated Dpp antagonist. Finally, we provide evidence that Sog functions as a diffusible morphogen in the blastoderm embryo. These data strongly support the view that the primary phylogenetically conserved function of the Drosophila sog and dpp genes and the homologous Xenopus chordin and BMP-4 genes is to subdivide the primitive embryonic ectoderm into neural versus non-neural domains.