Tremml G, Bienz M
Zoologisches Institut, Universität Zürich, Switzerland.
Development. 1992 Oct;116(2):447-56. doi: 10.1242/dev.116.2.447.
Extracellular signal proteins induce the homeotic gene labial (lab) to high levels of localised expression in the endoderm of Drosophila embryos. We aimed to identify cis-regulatory elements within the lab gene that respond to this induction by analysing the activity of stably integrated reporter gene constructs. Dissection of lab 5' flanking sequences reveals two types of response elements. One of these mediates lab dependent activity, providing evidence that lab induction in the endoderm is autoregulatory. The other element, to a large extent independent of lab function, responds to decapentaplegic (dpp), a signal molecule related to mammalian TGF-beta. Our evidence suggests that lab induction in the endoderm reflects coordinate action of two distinct factors one of which may be lab protein itself, and another whose localised activity or expression in the midgut depends on the dpp signal.
细胞外信号蛋白可诱导同源异型基因唇（lab）在果蝇胚胎内胚层中高水平局部表达。我们旨在通过分析稳定整合的报告基因构建体的活性，鉴定lab基因内对这种诱导作出反应的顺式调控元件。对lab 5'侧翼序列的剖析揭示了两种类型的反应元件。其中一种介导依赖lab的活性，这表明内胚层中的lab诱导是自动调节的。另一个元件在很大程度上独立于lab功能，对与哺乳动物转化生长因子-β相关的信号分子——骨形态发生蛋白（dpp）作出反应。我们的证据表明，内胚层中的lab诱导反映了两种不同因子的协同作用，其中一种可能是lab蛋白本身，另一种在中肠中的局部活性或表达取决于dpp信号。
