Small S, Blair A, Levine M
Department of Biology, New York University, New York 10003, USA.
Dev Biol. 1996 May 1;175(2):314-24. doi: 10.1006/dbio.1996.0117.
Previous studies on the regulation of the segmentation gene even-skipped (eve) have centered on the transcription of stripe 2. Here, we characterize another enhancer module contained within the complex eve promoter that directs expression of stripes 3 and 7. This enhancer is approximately 500 bp in length and maps approximately 3.3 kb upstream of the transcription start site. The stripe 3 + 7 enhancer appears to be regulated by one or more ubiquitously distributed activators, including components of a JAK-Stat pathway. The two-stripe pattern results via multiple tiers of repressors which delimit this ubiquitous activation. The zinc finger repressor hunchback appears to be responsible for establishing the anterior border of stripe 3 and the posterior border of stripe 7. knirps, a member of the nuclear receptor family of transcription factors, appears to establish the posterior border of stripe 3 and the anterior border of stripe 7. Activator and repressor proteins bind in vitro to several sites within the enhancer. These findings suggest a general model for the regulation of segmentation stripes, whereby enhancers integrate positional information provided by broadly distributed activators and spatially restricted repressors.
以往关于体节极性基因“偶数跳动”（eve）调控的研究主要集中在条纹2的转录上。在此，我们鉴定了包含在复杂的eve启动子中的另一个增强子模块，它指导条纹3和条纹7的表达。这个增强子长度约为500碱基对，位于转录起始位点上游约3.3千碱基处。条纹3 + 7增强子似乎受一种或多种广泛分布的激活因子调控，包括JAK-Stat信号通路的成分。通过多层阻遏物产生双条纹模式，这些阻遏物限制了这种广泛的激活。锌指阻遏物驼背似乎负责确定条纹3的前边界和条纹7的后边界。核受体家族转录因子成员克尼普斯似乎确定条纹3的后边界和条纹7的前边界。激活蛋白和阻遏蛋白在体外与增强子内的几个位点结合。这些发现提示了一个体节条纹调控的通用模型，即增强子整合广泛分布的激活因子和空间受限的阻遏物提供的位置信息。
