Expansion of voltage-dependent Na+ channel gene family in early tetrapods coincided with the emergence of terrestriality and increased brain complexity.
Expansion of voltage-dependent Na+ channel gene family in early tetrapods coincided with the emergence of terrestriality and increased brain complexity.
复制标题
早期四足动物中电压依赖性Na通道基因家族的扩展与陆地性的出现和大脑复杂性的增加同时发生。
DOI：
10.1093/molbev/msq325
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发表时间：
2011
影响因子：
10.7
通讯作者：
Lu,Ying
中科院分区：
文献类型：
--
作者：
Zakon,HaroldH;Jost,MandaC;Lu,Ying
哺乳动物有十种电压依赖性钠 (Nav) 通道基因。导航通道在具有不同亚细胞分布的不同细胞类型中表达，对于神经元处理的许多方面至关重要。硬骨鱼和四足动物的最后共同祖先有四个导航通道基因，可能位于四个不同的染色体上。在哺乳动物的谱系中，其中两条染色体上的一系列串联重复使 Nav 通道基因的数量增加了一倍多。目前尚不清楚这些重复何时发生，以及它们是否是在染色体上侧翼基因重复的背景下发生的，还是作为离子通道基因总体扩张的背景。我们利用硬骨鱼、软骨鱼、肺鱼、两栖动物、鸟类、蜥蜴和哺乳动物的 Nav 通道序列以及四足动物基因的染色体同线性进行系统发育分析，估计了 Nav 通道基因家族扩展的关键日期。我们通过证明周围基因缺乏重复或重复保留，测试并排除了 Nav 通道基因位于易于重复的染色体区域的零假设。我们还发现，在硬骨鱼-四足动物分歧之后，四足动物的其他电压依赖性离子通道基因家族没有类似的扩张。我们假设 Nav 通道基因家族在泥盆纪和石炭纪时期发生了特定的扩展，当时四足动物进化、多样化并入侵陆地栖息地。在此期间，羊膜动物前脑进化出更复杂的解剖结构，并出现了新的触觉感受器。导航通道基因的复制使得导航通道表达具有更大的区域专业化、亚细胞定位的变化以及体感输入的增强处理。
Mammals have ten voltage-dependent sodium (Nav) channel genes. Nav channels are expressed in different cell types with different subcellular distributions and are critical for many aspects of neuronal processing. The last common ancestor of teleosts and tetrapods had four Nav channel genes, presumably on four different chromosomes. In the lineage leading to mammals, a series of tandem duplications on two of these chromosomes more than doubled the number of Nav channel genes. It is unknown when these duplications occurred and whether they occurred against a backdrop of duplication of flanking genes on their chromosomes or as an expansion of ion channel genes in general. We estimated key dates of the Nav channel gene family expansion by phylogenetic analysis using teleost, elasmobranch, lungfish, amphibian, avian, lizard, and mammalian Nav channel sequences, as well as chromosomal synteny for tetrapod genes. We tested, and exclude, the null hypothesis that Nav channel genes reside in regions of chromosomes prone to duplication by demonstrating the lack of duplication or duplicate retention of surrounding genes. We also find no comparable expansion in other voltage-dependent ion channel gene families of tetrapods following the teleost–tetrapod divergence. We posit a specific expansion of the Nav channel gene family in the Devonian and Carboniferous periods when tetrapods evolved, diversified, and invaded the terrestrial habitat. During this time, the amniote forebrain evolved greater anatomical complexity and novel tactile sensory receptors appeared. The duplication of Nav channel genes allowed for greater regional specialization in Nav channel expression, variation in subcellular localization, and enhanced processing of somatosensory input.