Nakamura S, Stock D W, Wydner K L, Bollekens J A, Takeshita K, Nagai B M, Chiba S, Kitamura T, Freeland T M, Zhao Z, Minowada J, Lawrence J B, Weiss K M, Ruddle F H
Department of Biology, Yale University, New Haven, Connecticut 06511, USA.
Genomics. 1996 Dec 15;38(3):314-24. doi: 10.1006/geno.1996.0634.
We have cloned a new Dlx gene (Dlx7) from human and mouse that may represent the mammalian orthologue of the newt gene NvHBox-5. The homeodomains of these genes are highly similar to all other vertebrate Dlx genes, and regions of similarity also exist between mammalian Dlx7 and a subset of vertebrate Dlx genes downstream of the homeodomain. The sequence divergence between human and mouse Dlx7 in these regions is greater than that predicted from comparisons of other vertebrate Dlx genes, however, and there is little sequence similarity upstream of the homeodomain both between these two genes and with other Dlx genes. We present evidence for alternative splicing of mouse Dlx7 upstream of the homeodomain that may account for some of this divergence. We have mapped human DLX7 distal to the 5' end of the HOXB cluster at an estimated distance of between 1 and 2 Mb by FISH. Both the human and the mouse Dlx7 are shown to be closely linked to Dlx3 in a convergently transcribed orientation. These mapping results support the possibility that vertebrate distal-less genes have been duplicated in concert with the Hox clusters.
我们已经从人和小鼠中克隆出一个新的Dlx基因（Dlx7），它可能是蝾螈基因NvHBox-5在哺乳动物中的直系同源基因。这些基因的同源结构域与所有其他脊椎动物的Dlx基因高度相似，并且在哺乳动物Dlx7与同源结构域下游的一部分脊椎动物Dlx基因之间也存在相似区域。然而，在这些区域中，人和小鼠Dlx7之间的序列差异大于从其他脊椎动物Dlx基因比较中预测的差异，并且在这两个基因之间以及与其他Dlx基因之间，同源结构域上游几乎没有序列相似性。我们提供了小鼠Dlx7在同源结构域上游存在可变剪接的证据，这可能解释了部分这种差异。我们通过荧光原位杂交（FISH）将人类DLX7定位到HOXB簇5'端的远端，估计距离在1至2兆碱基之间。人和小鼠的Dlx7都显示出与Dlx3以反向转录方向紧密连锁。这些定位结果支持了脊椎动物远端缺失基因与Hox簇协同复制的可能性。
