Shadow Enhancers Mediate Dynamic Shifts of Gap Gene Expression in the Drosophila Embryo.
Shadow Enhancers Mediate Dynamic Shifts of Gap Gene Expression in the Drosophila Embryo.
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DOI：
10.1016/j.cub.2016.02.054
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发表时间：
2016-05-09
期刊：
影响因子：
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通讯作者：
Levine M
中科院分区：
文献类型：
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作者：
El-Sherif E;Levine M
果蝇的模式形成基因通常包含成对的主增强子和影子增强子，它们具有重叠的活性。有人提出，这种调控“冗余”有助于确保在诸如温度升高等应激条件下基因表达的可靠激活。也有证据表明，影子增强子有助于在调控因子水平（如母体的 bicoid梯度）发生微小变化时产生清晰的基因表达开/关边界。在此，我们使用实时成像方法来观察间隙基因Krüppel和knirps的时间动态，它们分别对胸部和腹部的模式形成至关重要。先前对固定胚胎的分析表明Krüppel和knirps表达模式向前偏移。在此我们使用计算可视化方法来揭示这些偏移的精确时间动态，并进一步表明影子增强子对这一过程至关重要。我们讨论了增强子优势的潜在机制，即一个增强子抑制另一个增强子以促进时间动态。
Drosophila patterning genes often contain pairs of primary and shadow enhancers that possess overlapping activities. It has been suggested that this regulatory “redundancy” helps ensure reliable activation of gene expression under stressful conditions such as increases in temperature. There is also evidence that shadow enhancers help produce sharp on/off boundaries of gene expression in response to small changes in the levels of regulatory factors, such as the maternal Bicoid gradient. Here, we use live-imaging methods to visualize the temporal dynamics of the gap genes Kruppel and knirps, which are essential for the patterning of the thorax and abdomen, respectively. Previous analyses of fixed embryos suggested anterior shifts of the Kruppel and knirps expression patterns. Here we use computational visualization methods to reveal the precise temporal dynamics of these shifts and further suggest that shadow enhancers are crucial for this process. We discuss potential mechanisms for enhancer dominance, whereby one enhancer represses the other to foster temporal dynamics.