DORSAL TWIST INTERACTIONS ESTABLISH SNAIL EXPRESSION IN THE PRESUMPTIVE MESODERM OF THE DROSOPHILA EMBRYO
DORSAL TWIST INTERACTIONS ESTABLISH SNAIL EXPRESSION IN THE PRESUMPTIVE MESODERM OF THE DROSOPHILA EMBRYO
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DOI：
10.1101/gad.6.8.1518
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发表时间：
1992-08-01
影响因子：
10.5
通讯作者：
LEVINE, M
中科院分区：
文献类型：
--
作者：
IP, YT;PARK, RE;LEVINE, M
果蝇中胚层分化的第一步是激活两个调控基因，twist（twi）和snail（sna），在早期胚胎的腹侧区域。SNA是在整个假定的中胚层中均匀表达的转录阻遏物。其尖锐的侧面界限有助于建立中胚层和神经外胚层之间的界限。遗传学研究表明，sna是背侧（dl）形态发生蛋白的靶点，这种相互作用为确定形态发生蛋白梯度如何建立一个尖锐的开/关阈值反应提供了一个模型。我们目前的证据表明，dl和twi直接激活sna的表达。在sna启动子的限定区域内的dl-和twi-结合位点的定点诱变表明，这两种蛋白质（分别含有Rel和螺旋-环-螺旋结构域）倍增地起作用以确保sna的强的、均匀的表达，特别是在dl的量逐渐减少的腹侧区域中。这些结果与尖锐的sna边界是由较浅的dl梯度和较陡的twi梯度相乘而形成的可能性是一致的。
The first step in the differentiation of the Drosophila mesoderm is the activation of two regulatory genes, twist (twi) and snail (sna), in ventral regions of early embryos. sna is a transcriptional repressor that is uniformly expressed throughout the presumptive mesoderm. Its sharp lateral limits help to establish the boundary between the mesoderm and neuroectoderm. Genetic studies suggest that sna is a target of the dorsal (dl) morphogen, and this interaction provides a model for determining how a morphogen gradient establishes a sharp, on/off threshold response. We present evidence that dl and twi directly activate sna expression. Site-directed mutagenesis of dl- and twi-binding sites within defined regions of the sna promoter suggest that the two proteins (containing the Rel and helix-loop-helix domains, respectively) function multiplicatively to ensure strong, uniform expression of sna, particularly in ventral-lateral regions where there are diminishing amounts of dl. These results are consistent with the possibility that the sharp sna borders are formed by multiplying the shallow dl gradient and the steeper twi gradient.