Sponge Pax cDNA related to Pax-2/5/8 and ancient gene duplications in the Pax family
Sponge Pax cDNA related to Pax-2/5/8 and ancient gene duplications in the Pax family
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DOI：
10.1007/pl00006421
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发表时间：
1998-12-01
影响因子：
3.9
通讯作者：
Miyata, T
中科院分区：
文献类型：
--
作者：
Hoshiyama, D;Suga, H;Miyata, T
Pax 基因家族的成员编码含有 DNA 结合配对结构域的转录因子，该结构域参与发育控制和中枢神经系统 (CNS) 的形成。根据配对型同源盒和八肽的存在与否，将家族成员分为六个类或亚家族。为了粗略估计 Pax 家族不同类别因基因重复而分化的时间，我们从淡水海绵 Ephydatia Fluviatilis 中克隆并测序了 Pax 相关 cDNA sPax-2/5/8，除了配对结构域外，它还编码配对型同源盒和八肽。基于配对结构域序列的系统发育树表明 sPax-2/5/8 是脊椎动物 Pax-2/5/8 的同源物。也有人认为，产生不同类别的大部分基因复制已经在副动物-真后生动物分裂之前的动物进化的早期阶段完成。在古代基因复制很久之后，脊索动物谱系上发生了进一步的基因复制，产生了每个亚科的成员，并在鱼类四足动物分裂之前完成。这表明，参与三叶细胞中枢神经系统特征形成的Pax基因的主要类别早在三叶细胞寒武纪大爆发之前就已经存在，并且具有新功能的新基因的产生与寒武纪大爆发之间没有直接联系。 Pax家族中发现的基因多样化模式与我们分析的涉及信号转导的五个基因家族中的基因多样化模式相似。此外，Pax 蛋白的进化速率已被证明在动物进化过程中随着生物体复杂性的增加而降低。
Members of the Pax gene family encode transcription factors containing a DNA-binding paired domain which is involved in developmental control and the formation of the central nervous system (CNS). The family members are classified into six classes or subfamilies, depending on the presence or absence of paired-type homeobox and octapeptide. To obtain rough estimates of times when the different classes of the Pax family diverged by gene duplication, we cloned and sequenced a Pax-related cDNA, sPax-2/5/8, from Ephydatia fluviatilis, a freshwater sponge, which encodes a paired-type homeobox and an octapeptide, in addition to a paired domain. A phylogenetic tree based on the paired domain sequences suggest that sPax-2/5/8 is a homologue of vertebrate Pax-2/5/8. It was also suggested that the majority of gene duplications that gave rise to distinct classes has been completed in the very early evolution of animals before the parazoan-eumetazoan split. Long after the ancient gene duplications, further gene duplications that gave rise to members in each subfamily occurred on the chordate lineages and completed before the fish-tetrapod split. This suggests that the major classes of the Pax genes involved in the formation of CNS characteristic of triploblasts had already existed long before the Cambrian explosion of triploblasts, and there is no direct link between the creation of new genes with novel functions and the Cambrian explosion. The pattern of gene diversification found in the Pax family is similar to those in five gene families involved in the signal transduction analyzed by us. Furthermore, the evolutionary rates of the Pax proteins have been shown to decrease with increasing organismal complexity during animal evolution.