Fujiwara Shigeki, Kawamura Kazuo
Laboratory of Molecular and Cellular Biotechnology, Faculty of Science, Kochi University, Kochi 780-8520, Japan.
Zoolog Sci. 2003 Jul;20(7):809-18. doi: 10.2108/zsj.20.809.
Retinoic acid (RA) regulates many of the chordate-specific and vertebrate-specific characters. These include the anteroposterior pattern of the dorsally located central nervous system, pharynx with gill slits, neural crest cells, limb morphogenesis and anteroposteriorly organized vertebrae. The necessity of endogenous RA and the RA receptor (RAR) has been demonstrated by mutant analyses, vitamin A-deficient animals and various other methods. Since RAR has been identified only in chordates, the acquisition of the RAR-mediated RA signaling pathway is thought to be an important event for the innovation of the chordate body plan. RA-synthesizing aldehyde dehydrogenases and RA-degrading enzymes also seem to be chordate-specific. The expression pattern of these genes in ascidian embryos is similar to that in vertebrate embryos. These results suggest that the RA signaling cascade, with various regulators and modifiers, had been already well established in the common chordate ancestor. RA also regulates morphogenesis during the asexual reproduction of ascidians, suggesting that RA may also have played a part in producing diversity within the chordate groups.
视黄酸（RA）调控许多脊索动物特有的和脊椎动物特有的特征。这些特征包括位于背部的中枢神经系统的前后模式、带有鳃裂的咽、神经嵴细胞、肢体形态发生以及前后排列的椎骨。通过突变分析、维生素A缺乏动物以及各种其他方法，已证明内源性RA和视黄酸受体（RAR）的必要性。由于RAR仅在脊索动物中被鉴定出来，因此RAR介导的RA信号通路的获得被认为是脊索动物身体结构创新的一个重要事件。合成RA的醛脱氢酶和降解RA的酶似乎也是脊索动物特有的。这些基因在海鞘胚胎中的表达模式与在脊椎动物胚胎中的相似。这些结果表明，具有各种调节因子和修饰因子的RA信号级联在共同的脊索动物祖先中就已确立。RA还调控海鞘无性繁殖过程中的形态发生，这表明RA可能也在脊索动物群体内产生多样性方面发挥了作用。
