Common functions of central and posterior Hox genes for the repression of head in the trunk of Drosophila
Common functions of central and posterior Hox genes for the repression of head in the trunk of Drosophila
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DOI：
10.1242/dev.009662
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发表时间：
2008-01-15
期刊：
影响因子：
4.6
通讯作者：
Kerridge, Stephen
中科院分区：
文献类型：
--
作者：
Coiffier, Delphine;Charroux, Bernard;Kerridge, Stephen
HOX基因定位于复合体中，编码保守的同源结构域转录因子，主要是因为它们的特殊功能而被研究：沿着前后轴形成不同的结构。它们可能是通过复制和发散产生的，来自一个独特的基因，这表明HOX基因可能保留了共同的功能。同源结构域序列的比较将HOX蛋白分为前、中、后三类，分别反映了它们在头部、躯干和尾部的表达模式。然而，支持这种分类的功能数据很少。在这里，我们重新研究了果蝇中HOX基因的一种常见活动：躯干中头部的抑制。首先，我们证明了中枢和后部HOX基因阻止头部特异基因Optix在躯干中的表达，为分类提供了功能基础。Optix功能缺失突变影响胚胎头部发育，而异位表达Optix强烈干扰躯干发育。其次，我们证明了非HOX基因Teashirt、外牙和同胸是抑制Optix所必需的，并且无翼信号和增强有助于这种抑制。我们认为，HOX基因的一个进化早期功能是用后来出现的针对躯干的新功能来修改原始的头部形态。
Hox genes are localised in complexes, encode conserved homeodomain transcription factors and have mostly been studied for their specialised functions: the formation of distinct structures along the anteroposterior axis. They probably derived via duplication followed by divergence, from a unique gene, suggesting that Hox genes may have retained a common function. The comparison of their homeodomain sequences groups Hox proteins into Anterior, Central and Posterior classes, reflecting their expression patterns in the head, trunk and tail, respectively. However, functional data supporting this classification are rare. Here, we re-examine a common activity of Hox genes in Drosophila: the repression of head in the trunk. First, we show that central and posterior Hox genes prevent the expression of the head specific gene optix in the trunk, providing a functional basis for the classification. Loss-of-function mutations of optix affect embryonic head development, whereas ectopic Optix expression strongly perturbs trunk development. Second, we demonstrate that the non-Hox genes teashirt, extradenticle and homothorax are required for the repression of optix and that Wingless signalling and Engrailed contribute to this repression. We propose that an evolutionary early function of Hox genes was to modify primitive head morphology with novel functions specialising the trunk appearing later on.