A MORPHOGENETIC GRADIENT OF HUNCHBACK PROTEIN ORGANIZES THE EXPRESSION OF THE GAP GENES KRUPPEL AND KNIRPS IN THE EARLY DROSOPHILA EMBRYO
A MORPHOGENETIC GRADIENT OF HUNCHBACK PROTEIN ORGANIZES THE EXPRESSION OF THE GAP GENES KRUPPEL AND KNIRPS IN THE EARLY DROSOPHILA EMBRYO
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DOI：
10.1038/346577a0
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发表时间：
1990-08-09
期刊：
影响因子：
64.8
通讯作者：
TAUTZ, D
中科院分区：
文献类型：
--
作者：
HULSKAMP, M;PFEIFLE, C;TAUTZ, D
果蝇胚胎的分段依赖于早期胚胎中母体基因和合子基因之间相互作用的层次结构（参见参考文献1-3）。前部区域由thebicoid（bcd）基因产物组成，在胚胎的前半部分形成浓度梯度4 -6。差距基因也参与建立身体计划，驼背（hb）被表达的母亲和合子7，10。bcd基因产物直接激活hbis的合子表达，导致胚胎细分为前半部分表达合子提供的hb蛋白，后半部分不表达。对母体提供的hb蛋白的类似作用是由基因型引起的，基因型抑制母体提供的转录本在后半部分的翻译。这种血红蛋白的调节是腹部发育的先决条件，因为血红蛋白在后半部分的存在抑制了后节14，17，18。这种抑制机制表明，后分割可能不直接依赖于母体的位置线索，但完全组织在合子水平。在这里，我们报告进一步的证据来支持这一假设，并表明hb蛋白本身是至关重要的参与组织腹部分割。不同浓度的hb蛋白决定了差距基因Krüppel（Kr）表达的前后边界和差距基因knirps（kni）表达的前边界，从而定义了三个位置值。这些调节途径以一种多余的方式控制，部分由bcd控制，部分由母体hb基因产物控制。
SEGMENTATIONof theDrosophilaembryo depends on a hierarchy of interactions among the maternal and zygotic genes in the early embryo (see refs 1–3 for reviews). The anterior region is organized maternally by thebicoid(bcd) gene product, which forms a concentration gradient in the anterior half of the embyro4–6. The gap genes are also involved in establishing the body plan, withhunchback(hb) being expressed both maternally and zygotically7,10. Zygotic expression ofhbis directly activated by thebcdgene product, leading to a subdivision of the embryo into an anterior half expressing zygotically provided hb protein and a posterior half that does not. A similar effect on maternally provided hb protein is caused by the genenanos, which represses the translation of maternally provided transcripts in the posterior half. This regulation of hb protein is a prerequisite for abdomen development, because the presence of hb protein in the posterior half represses posterior segmentation14,17,18. This repression mechanism suggests that posterior segmentation might not directly depend on maternal positional cues, but be solely organized at the zygotic level. Here we report further evidence to support this hypothesis and show that thehbprotein itself is crucially involved in organizing abdominal segmentation. Differential concentrations ofhbprotein determine the anterior and posterior borders of expression of the gap geneKrüppel(Kr) and the anterior border of the gap geneknirps(kni), thus defining three positional values. These regulatory pathways are controlled in a redundant way, in part bybcdand in part by the maternalhbgene product.