Manfroid Isabelle, Caubit Xavier, Kerridge Stephen, Fasano Laurent
Laboratoire de Génétique et Physiologie du Développement, UMR 9943 CNRS-Université, IBDM-INSERM-Université de la Méditerranée, Campus de Luminy, Case 907, F-13288 Marseille, Cedex 09, France.
Development. 2004 Mar;131(5):1065-73. doi: 10.1242/dev.00977.
Drosophila teashirt (tsh) functions as a region-specific homeotic gene that specifies trunk identity during embryogenesis. Based on sequence homology, three tsh-like (Tsh) genes have been identified in the mouse. Their expression patterns in specific regions of the trunk, limbs and gut raise the possibility that they may play similar roles to tsh in flies. By expressing the putative mouse Tsh genes in flies, we provide evidence that they behave in a very similar way to the fly tsh gene. First, ectopic expression of any of the three mouse Tsh genes, like that of tsh, induces head to trunk homeotic transformation. Second, mouse Tsh proteins can rescue both the homeotic and the segment polarity phenotypes of a tsh null mutant. Third, following ectopic expression, the three mouse Tsh genes affect the expression of the same target genes as tsh in the Drosophila embryo. Fourth, mouse Tsh genes, like tsh, are able to induce ectopic eyes in adult flies. Finally, all Tsh proteins contain a motif that recruits the C-terminal binding protein and contributes to their repression function. As no other vertebrate or fly protein has been shown to induce such effects upon ectopic expression, these results are consistent with the idea that the three mouse Tsh genes are functionally equivalent to the Drosophila tsh gene when expressed in developing Drosophila embryos.
果蝇的teashirt（tsh）基因作为一种区域特异性同源异型基因，在胚胎发育过程中决定躯干特征。基于序列同源性，在小鼠中已鉴定出三个类似tsh的（Tsh）基因。它们在躯干、四肢和肠道特定区域的表达模式提示，它们可能在果蝇中发挥与tsh类似的作用。通过在果蝇中表达推测的小鼠Tsh基因，我们提供的证据表明，它们的行为与果蝇的tsh基因非常相似。首先，三个小鼠Tsh基因中的任何一个异位表达，与tsh一样，都会诱导头部到躯干的同源异型转化。其次，小鼠Tsh蛋白可以挽救tsh基因敲除突变体的同源异型和体节极性表型。第三，异位表达后，三个小鼠Tsh基因影响果蝇胚胎中与tsh相同的靶基因的表达。第四，小鼠Tsh基因与tsh一样，能够在成年果蝇中诱导异位眼的形成。最后，所有Tsh蛋白都含有一个基序，该基序招募C末端结合蛋白并有助于其抑制功能。由于尚未显示其他脊椎动物或果蝇蛋白在异位表达时会诱导此类效应，这些结果与以下观点一致：当在发育中的果蝇胚胎中表达时，三个小鼠Tsh基因在功能上等同于果蝇的tsh基因。
