Development of a chordate anterior-posterior axis without classical retinoic acid signaling
Development of a chordate anterior-posterior axis without classical retinoic acid signaling
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DOI：
10.1016/j.ydbio.2007.02.032
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发表时间：
2007-05-15
影响因子：
2.7
通讯作者：
Postlethwait, John H.
中科院分区：
文献类型：
--
作者：
Canestro, Cristian;Postlethwait, John H.
视黄酸（RA）的发育信号被认为是脊索动物身体计划起源所必需的创新。尾索动物Oikopleura dioica在整个生命过程中保持着一个脊索动物的身体计划，但它的基因组似乎缺乏RA合成，降解和接收的基因。这表明RA机制在幼虫进化过程中丢失的假设，并预测Oikopleura发展已成为独立的RA信号。这一预测提出了一个问题，即脊索动物体平面的前后组织可以在没有RA的经典形态发生作用的情况下发展。为了解决这个问题，我们进行了药理学治疗和发育分子标记物的分析，以调查RA是否在Oikopleura胚胎的前后轴向模式中起作用。结果表明，RA不会导致同源异型posteriorization在Oikopleura，因为它在脊椎动物和头索动物，并表明，脊索动物可以开发的典型的RA的形态发生作用的情况下，身体计划。Oikopleura和海鞘证据的比较表明，缺乏RA诱导的同源异形posteriorization是一个共同的衍生特征的尾索动物。我们讨论了可能的关系，RA在尿索动物发育的基因组事件，如霍克斯集群破裂的作用改变的背景下，一个新的理解脊索动物发生。(c)2007年爱思唯尔公司All rights reserved.
Developmental signaling by retinoic acid (RA) is thought to be an innovation essential for the origin of the chordate body plan. The larvacean urochordate Oikopleura dioica maintains a chordate body plan throughout life, and yet its genome appears to lack genes for RA synthesis, degradation, and reception. This suggests the hypothesis that the RA-machinery was lost during larvacean evolution, and predicts that Oikopleura development has become independent of RA-signaling. This prediction raises the problem that the anterior-posterior organization of a chordate body plan can be developed without the classical morphogenetic role of RA. To address this problem, we performed pharmacological treatments and analyses of developmental molecular markers to investigate whether RA acts in anterior-posterior axial patterning in Oikopleura embryos. Results revealed that RA does not cause homeotic posteriorization in Oikopleura as it does in vertebrates and cephalochordates, and showed that a chordate can develop the phylotypic body plan in the absence of the classical morphogenetic role of RA. A comparison of Oikopleura and ascidian evidence suggests that the lack of RA-induced homeotic posteriorization is a shared derived feature of urochordates. We discuss possible relationships of altered roles of RA in urochordate development to genomic events, such as rupture of the Hox-cluster, in the context of a new understanding of chordate phylogeny. (c) 2007 Elsevier Inc. All rights reserved.