Goriely A, Stella M, Coffinier C, Kessler D, Mailhos C, Dessain S, Desplan C
Howard Hughes Medical Institute, The Rockefeller University, New York, NY 10021, USA.
Development. 1996 May;122(5):1641-50. doi: 10.1242/dev.122.5.1641.
We have cloned a Drosophila homologue (D-gsc) of the vertebrate homeobox gene goosecoid (gsc). In the Gsc proteins, the pressure for conservation has been imposed on the homeodomain, the functional domain of the protein: sequence homology is limited to the homeodomain (78% identity) and to a short stretch of 7 aminoacids also found in other homeoproteins such as Engrailed. Despite this weak homology, D-gsc is able to mimic gsc function in a Xenopus assay, as shown by its ability to rescue the axis development of a UV-irradiated embryo. Moreover, our data suggest that the position of insect and vertebrate gsc homologues within a regulatory network has also been conserved: D-gsc expression is controlled by decapentaplegic, orthodenticle, sloppy-paired and tailless whose homologues control gsc expression (for BMP4 and Otx-2), or are expressed at the right time and the right place (for XFKH1/Pintallavis and Tlx) to be interacting with gsc during vertebrate development. However, the pattern of D-gsc expression in ectodermal cells of the nervous system and foregut cannot easily be reconciled with that of vertebrate gsc mesodermal expression, suggesting that its precise developmental function might have diverged. Still, this comparison of domains of expression and functions among Gsc proteins could shed light on a common origin of gut formation and/or on basic cellular processes. The identification of gsc target genes and/or other genes involved in similar developmental processes will allow the definition of the precise phylogenetic relationship among Gsc proteins.
我们克隆了脊椎动物同源异型盒基因鹅膏蕈氨酸（gsc）的果蝇同源物（D-gsc）。在Gsc蛋白中，保守压力施加于该蛋白的功能域——同源异型域：序列同源性仅限于同源异型域（78%的同一性）以及在其他同源蛋白（如 engrailed）中也存在的一段7个氨基酸的短序列。尽管同源性较弱，但在非洲爪蟾实验中，D-gsc能够模拟gsc的功能，这体现在它拯救紫外线照射胚胎轴发育的能力上。此外，我们的数据表明，昆虫和脊椎动物gsc同源物在调控网络中的位置也得以保守：D-gsc的表达受果蝇的decapentaplegic、orthodenticle、sloppy-paired和tailless基因控制，这些基因的同源物在脊椎动物发育过程中控制gsc的表达（对于BMP4和Otx-2），或者在正确的时间和位置表达（对于XFKH1/Pintallavis和Tlx）以便与gsc相互作用。然而，D-gsc在神经系统和前肠外胚层细胞中的表达模式，难以与脊椎动物gsc在中胚层的表达模式相协调，这表明其精确的发育功能可能已经发生了分化。尽管如此，对Gsc蛋白表达和功能域的这种比较，可能有助于揭示肠道形成的共同起源和/或基本细胞过程。鉴定gsc靶基因和/或参与类似发育过程的其他基因，将有助于明确Gsc蛋白之间精确的系统发育关系。
