The gap protein knirps mediates both quenching and direct repression in the Drosophila embryo
The gap protein knirps mediates both quenching and direct repression in the Drosophila embryo
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DOI：
10.1002/j.1460-2075.1996.tb00735.x
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发表时间：
1996-07-15
期刊：
影响因子：
11.4
通讯作者：
Levine, M
中科院分区：
文献类型：
--
作者：
Arnosti, DN;Gray, S;Levine, M
在果蝇胚胎发育过程中，转录抑制对于建立基因表达的局部模式是必不可少的。已有研究表明，knirps孤儿受体（kni）可能通过竞争抑制转录，并排除bicoid（bcd）激活剂与靶启动子重叠位点的结合，从而抑制转录。在转基因胚胎中异源增强子内的上游激活子，kni抑制的范围类似于50-100 bp，使得模块化启动子中的邻近增强子自由地与转录复合物相互作用然而，当在启动子近端区域中结合时，kni也可以抑制转录复合物。在该位置，kni在一个模块化启动子中作为一个显性阻遏物发挥作用，并阻断多个增强子。我们的研究表明，短程阻遏代表了一种灵活的基因调控形式，表现出增强子或启动子特异性效应，这取决于阻遏物结合位点的位置。
Transcriptional repression is essential for establishing localized patterns of gene expression during Drosophila embryogenesis. Several mechanisms of repression have been proposed, including competition, quenching and direct repression of the transcription complex, Previous studies suggest that the knirps orphan receptor (kni) may repress transcription via competition, and exclude the binding of the bicoid (bcd) activator to an overlapping site in a target promoter, Here we present evidence that kni can quench, or locally inhibit, upstream activators within a heterologous enhancer in transgenic embryos, The range of kni repression is similar to 50-100 bp, so that neighboring enhancers in a modular promoter are free to interact with the transcription complex (enhancer autonomy), However, kni can also repress the transcription complex when bound in promoter-proximal regions, In this position, kni functions as a dominant repressor and blocks multiple enhancers in a modular promoter, Our studies suggest that short-range repression represents a flexible form of gene regulation, exhibiting enhancer- or promoter-specific effects depending on the location of repressor binding sites.