Sasaki H, Hogan B L
Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, TN 37232-2175, USA.
Genes Cells. 1996 Jan;1(1):59-72. doi: 10.1046/j.1365-2443.1996.04004.x.
Axial pattern formation in vertebrate embryos depends on signals from the node and, later, from the notochord and floor plate. Previous studies have shown that HNF-3 beta, a member of the winged-helix transcription factor family, plays key roles in the development of all three organizing centres.
Enhancer analysis of HNF-3 beta has therefore been performed using lacZ reporter gene constructs in transgenic mouse embryos. This has led to the identification of independent node/notochord and floor plate enhancers, at positions far upstream (-15 to -14 kb) and downstream (+6 to +11 kb) of the transcription star site, respectively. The node/notochord enhancer activity has been localized to a 520 bp fragment. Floor plate gene expression requires a combination of two separate fragments of the enhancer. Deletion analysis of one of these fragments (400 bp) has identified subregions required for the initiation and the maintenance of floor plate expression, and for the suppression of ectopic expression within the neural tube.
We conclude that HNF-3 beta gene expression in the node/notochord and in the floor plate are controlled through different enhancers, which consist of positive and negative elements.
脊椎动物胚胎中的轴向模式形成依赖于来自节点以及随后来自脊索和底板的信号。先前的研究表明，翼状螺旋转录因子家族成员HNF-3β在所有三个组织中心的发育中起关键作用。
因此，已在转基因小鼠胚胎中使用lacZ报告基因构建体对HNF-3β进行了增强子分析。这导致分别在转录起始位点上游（-15至-14 kb）和下游（+6至+11 kb）的位置鉴定出独立的节点/脊索和底板增强子。节点/脊索增强子活性已定位到一个520 bp的片段。底板基因表达需要增强子的两个单独片段的组合。对这些片段之一（400 bp）的缺失分析已确定了启动和维持底板表达以及抑制神经管内异位表达所需的亚区域。
我们得出结论，节点/脊索和底板中HNF-3β基因的表达是通过不同的增强子控制的，这些增强子由正性和负性元件组成。
