Comprehensive analysis of the ascidian genome reveals novel insights into the molecular evolution of ion channel genes
Comprehensive analysis of the ascidian genome reveals novel insights into the molecular evolution of ion channel genes
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DOI：
10.1152/physiolgenomics.00229.2004
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发表时间：
2005-08-11
影响因子：
4.6
通讯作者：
Mori, Y
中科院分区：
文献类型：
--
作者：
Okamura, Y;Nishino, A;Mori, Y
通过膜离子通道的离子通量在神经元信号传导和体内电解质的稳态控制中起着至关重要的作用。尽管我们知道各自的离子通道，离子通道基因的多样化是如何使动物适应物理环境的仍然是未知的。在这里，我们系统地调查了多达160个假定的离子通道基因的基因组中的玻璃海鞘和比较它们与相应的基因组的线虫Chafelium habditis elegans，果蝇黑腹果蝇，和更密切相关的脊椎动物的基因组。玻璃海鞘具有一组所谓的“原型”基因，用于调节神经元兴奋性的离子通道，或用于神经递质受体，这表明在海鞘/脊椎动物分化之前，哺乳动物中负责神经元信号传导的基因似乎主要通过祖先基因组中更受限制的成员的基因复制而多样化.大多数负责调节神经元兴奋性和痛觉的基因在海鞘基因组中缺失，这表明这些基因是在尿索动物分化后出现的。相反，编码连接蛋白、瞬时受体电位相关通道和氯离子通道的趋异基因，这些通道参与稳态控制，表明海鞘谱系特有的基因复制事件。由于玻璃海鞘基因组中存在多个无脊椎动物特有的通道基因，现存的脊椎动物冠群不仅通过基因/基因组复制获得了新的通道基因，而且丢弃了一些在无脊椎动物中存在的古老基因。这种基础脊索动物中离子通道基因的全基因组信息使我们能够开始将基因的创新和重塑与更近的脊索动物对其物理环境的适应相关联。
Ion fluxes through membrane ion channels play crucial roles both in neuronal signaling and the homeostatic control of body electrolytes. Despite our knowledge about the respective ion channels, just how diversification of ion channel genes underlies adaptation of animals to the physical environment remains unknown. Here we systematically survey up to 160 putative ion channel genes in the genome of Ciona intestinalis and compare them with corresponding gene sets from the genomes of the nematode Chaenorhabditis elegans, the fruit fly Drosophila melanogaster, and the more closely related genomes of vertebrates. Ciona has a set of so- called " prototype" genes for ion channels regulating neuronal excitability, or for neurotransmitter receptors, suggesting that genes responsible for neuronal signaling in mammals appear to have diversified mainly via gene duplications of the more restricted members of ancestral genomes before the ascidian/ vertebrate divergence. Most genes responsible for modulation of neuronal excitability and pain sensation are absent from the ascidian genome, suggesting that these genes arose after the divergence of urochordates. In contrast, the divergent genes encoding connexins, transient receptor potential-related channels and chloride channels, channels involved rather in homeostatic control, indicate gene duplication events unique to the ascidian lineage. Because several invertebrate- unique channel genes exist in Ciona genome, the crown group of extant vertebrates not only acquired novel channel genes via gene/ genome duplications but also discarded some ancient genes that have persisted in invertebrates. Such genome- wide information of ion channel genes in basal chordates enables us to begin correlating the innovation and remodeling of genes with the adaptation of more recent chordates to their physical environment.