Role of Pax genes in eye evolution:: A cnidarian PaxB gene uniting Pax2 and Pax6 functions
Role of Pax genes in eye evolution:: A cnidarian PaxB gene uniting Pax2 and Pax6 functions
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DOI：
10.1016/s1534-5807(03)00325-3
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发表时间：
2003-11-01
影响因子：
11.8
通讯作者：
Piatigorsky, J
中科院分区：
文献类型：
--
作者：
Kozmik, Z;Daube, M;Piatigorsky, J
对具有复杂眼睛的立方水母Tripedalia cystophora的PaxB进行了表征。PaxB是在这种刺胞动物中发现的唯一的Pax基因，在幼虫、视网膜、透镜和平衡囊中表达。PaxB含有Pax 2/5/8型配对结构域和八肽，但含有Pax 6 prd型同源结构域。PaxB的Pax 2/ 5/8样性质包括配对结构域、激活和抑制结构域的DNA结合特异性，以及拯救果蝇Pax 2眼突变体spa（pol）的能力。与Pax 6一样，Pax 13激活水母晶状体蛋白和果蝇视紫红质rh 6启动子并诱导果蝇的小异位眼。Pax 6被认为是眼睛发育的“主”控制基因。我们的数据表明，水母PaxB（一种PaxB样蛋白）的祖先是眼睛进化中原始的Pax蛋白，并且Pax 6样基因在与刺胞动物分离后在三成细胞中进化，这增加了刺胞动物和复杂的三成细胞眼睛独立出现的可能性。
PaxB from Tripedalia cystophora, a cubomedusan jellyfish possessing complex eyes (ocelli), was characterized. PaxB, the only Pax gene found in this cnidarian, is expressed in the larva, retina, lens, and statocyst. PaxB contains a Pax2/5/8-type paired domain and octapeptide, but a Pax6 prd-type homeodomain. Pax2/ 5/8-like properties of PaxB include a DNA binding specificity of the paired domain, activation and inhibitory domains, and the ability to rescue spa(pol), a Drosophila Pax2 eye mutant. Like Pax6, Pax13 activates jellyfish crystallin and Drosophila rhodopsin rh6 promoters and induces small ectopic eyes in Drosophila. Pax6 has been considered a "master" control gene for eye development. Our data suggest that the ancestor of jellyfish PaxB, a PaxB-Iike protein, was the primordial Pax protein in eye evolution and that Pax6-like genes evolved in triploblasts after separation from Cnidaria, raising the possibility that cnidarian and sophisticated triploblastic eyes arose independently.