Is retinoic acid genetic machinery a chordate innovation?
Is retinoic acid genetic machinery a chordate innovation?
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DOI：
10.1111/j.1525-142x.2006.00113.x
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发表时间：
2006-09-01
影响因子：
2.9
通讯作者：
Albalat, Ricard
中科院分区：
文献类型：
--
作者：
Canestro, Cristian;Postlethwait, John H.;Albalat, Ricard
许多脊索功能的发展依赖于维甲酸(RA)。由于RA在发育过程中的作用似乎仅限于脊索动物，先前有人提出，RA遗传机制的“发明”，包括RA结合核激素受体(RARS)，以及RA合成和降解酶Aldh1a(Raldh)和Cyp26，是导致脊索体计划的发育机制起源的重要一步。我们对12种后口动物的基因组数据库中的RA机制进行了详尽的调查，从而验证了这一假设。我们重建了这些基因在后口动物中的进化，并首次表明RA遗传机制--即Aldh1a、Cyp26和Rar同源基因--存在于非脊索后口动物中。这一发现表明，RA遗传机制在后口进化的早期就已经存在，因此，不是一种脊索性创新。这一新的进化观点反对这样的假设，即RA代谢和信号基础基因家族的获得是脊索动物起源的关键事件。我们提出了一个新的假说，认为RA机械基因的谱系特异性复制和丢失可能与后口的形态辐射有关。
Development of many chordate features depends on retinoic acid (RA). Because the action of RA during development seems to be restricted to chordates, it had been previously proposed that the "invention" of RA genetic machinery, including RA-binding nuclear hormone receptors (Rars), and the RA-synthesizing and RA-degrading enzymes Aldh1a (Raldh) and Cyp26, respectively, was an important step for the origin of developmental mechanisms leading to the chordate body plan. We tested this hypothesis by conducting an exhaustive survey of the RA machinery in genomic databases for twelve deuterostomes. We reconstructed the evolution of these genes in deuterostomes and showed for the first time that RA genetic machinery-that is Aldh1a, Cyp26, and Rar orthologs-is present in nonchordate deuterostomes. This finding implies that RA genetic machinery was already present during early deuterostome evolution, and therefore, is not a chordate innovation. This new evolutionary viewpoint argues against the hypothesis that the acquisition of gene families underlying RA metabolism and signaling was a key event for the origin of chordates. We propose a new hypothesis in which lineage-specific duplication and loss of RA machinery genes could be related to the morphological radiation of deuterostomes.