The ParaHox gene cluster is an evolutionary sister of the Hox gene cluster
The ParaHox gene cluster is an evolutionary sister of the Hox gene cluster
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DOI：
10.1038/31933
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发表时间：
1998-04-30
期刊：
影响因子：
64.8
通讯作者：
Holland, PWH
中科院分区：
文献类型：
--
作者：
Brooke, NM;Garcia-Fernàndez, J;Holland, PWH
Hox基因簇的基因仅限于动物界，在不同动物门的轴向模式形成中起着核心作用。尽管其具有进化和发育上的重要意义，但Hox基因簇的起源尚不清楚。普遍的观点是，一个原始的Hox基因簇是在接近动物起源时通过串联基因重复产生的。在Hox基因簇之外发现了几个与Hox基因具有高度序列同一性的同源框基因，它们被称为“分散的”类Hox基因；这些基因可能是从一个不断扩展的基因簇中转位出来的。在此我们表明，这些分散的同源框基因中的三个在头索动物文昌鱼中形成了一个新的基因簇。我们认为这个“ParaHox”基因簇是Hox基因簇的一个古老的旁系同源物（进化上的姊妹）；这两个基因簇是由一个原Hox基因簇重复产生的。此外，我们表明文昌鱼的ParaHox基因在前部、中部和后部组织中具有共线性的发育表达模式。我们提出，通过基因簇重复产生不同的Hox和ParaHox基因促进了寒武纪大爆发期间身体复杂性的增加。
Genes of the Hox cluster are restricted to the animal kingdom and play a central role in axial patterning in divergent animal phyla(1). Despite its evolutionary and developmental significance, the origin of the Hox gene cluster is obscure. The consensus is that a primordial Hox cluster arose by tandem gene duplication close to animal origins(2-5). Several homeobox genes with high sequence identity to Hox genes are found outside the Hox cluster and are known as 'dispersed' Hox-like genes; these genes may have been transposed away from an expanding clusters. Here we show that three of these dispersed homeobox genes form a novel gene cluster in the cephalochordate amphioxus, We argue that this 'ParaHox' gene cluster is an ancient paralogue (evolutionary sister) of the Hox gene cluster; the two gene clusters arose by duplication of a ProtoHox gene cluster. Furthermore, we show that amphioxus ParaHox genes have co-linear developmental expression patterns in anterior, middle and posterior tissues. We propose that the origin of distinct Hox and ParaHox genes by gene-duster duplication facilitated an increase in body complexity during the Cambrian explosion.