Metazoan evolution of glutamate receptors reveals unreported phylogenetic groups and divergent lineage-specific events.
Metazoan evolution of glutamate receptors reveals unreported phylogenetic groups and divergent lineage-specific events.
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谷氨酸受体的后生动物进化揭示了未报道的系统发育群体和不同的谱系特异性事件。
DOI：
10.7554/elife.35774
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发表时间：
2018-11-22
期刊：
影响因子：
7.7
通讯作者：
Bayés À
中科院分区：
文献类型：
--
作者：
Ramos-Vicente D;Ji J;Gratacòs-Batlle E;Gou G;Reig-Viader R;Luís J;Burguera D;Navas-Perez E;García-Fernández J;Fuentes-Prior P;Escriva H;Roher N;Soto D;Bayés À
谷氨酸受体分为两个不相关的家族：驱动突触传递的离子型（iGluR）和调节突触强度的代谢型（mGluR）。目前的 GluR 分类基于脊椎动物蛋白，并且二十多年来一直保持不变。在这里，我们报告了后生动物 GluR 的详尽系统发育研究。重要的是，我们证明 GluR 在不同的动物谱系中遵循不同的进化历史。我们的分析表明，目前将 iGluR 分为六类并不能完全反映其进化的复杂性。相反，我们建议将组织分为四个亚科和十个类，其中四个亚科以前从未被描述过。此外，我们报告了 mGluR I-III 类、IV 类的姐妹类。我们发现许多未报道的蛋白质在神经系统中表达，并且新的 Epsilon 受体形成功能性配体门控离子通道。我们提出了谷氨酸受体的更新分类，其中包括我们的发现。神经细胞或神经元通过在它们之间的间隙（突触）中释放特定分子来相互通信。发送神经元通过称为神经递质的化学物质包传递信息，这些化学物质在其表面受体的帮助下被接收细胞接收。神经元使用不同的神经递质发送不同的信息，但最常见的神经递质之一是谷氨酸。谷氨酸受体有两个家族：离子型受体，它可以响应神经递质打开或关闭离子通道并控制信号的传输；以及代谢型受体，它与特定蛋白质连接并控制信号的强度。我们对这两个受体家族的理解来自于有脊椎的动物，即脊椎动物。但受体本身很古老。我们可以将第一个家族追溯到细菌，将第二个家族追溯到阿米巴原虫等单细胞生物。脊椎动物有六类离子型谷氨酸受体和三类代谢型谷氨酸受体。但其他多细胞动物也有这些受体，因此这张图片可能并不完整。在这里，拉莫斯-维森特等人。绘制了动物的所有主要谱系，以揭示这些受体的进化历史，以确定受体家族是否随着脑力的增加而变得更加复杂。结果表明，脊椎动物中发现的谷氨酸受体仅是所有现有类型的一小部分。事实上，在当今的动物群体出现之前，含有离子型受体基因的基因组部分复制了三倍。这形成了四个受体亚家族，我们的祖先拥有所有这些亚家族。在整个动物界，有十类而不是六类离子型受体，还有一类额外的代谢型受体。但如今，脊椎动物中仅存在两个离子型受体亚家族和四分之三的代谢型受体亚家族。目前谷氨酸受体的分类以脊椎动物为中心，忽略了其他动物。但这个新数据可能会改变这一点。更好地了解这些新受体可以帮助神经科学家更好地了解神经系统。而且，使用这种技术来研究其他蛋白质家族可以揭示进化中更多缺失的环节。
Glutamate receptors are divided in two unrelated families: ionotropic (iGluR), driving synaptic transmission, and metabotropic (mGluR), which modulate synaptic strength. The present classification of GluRs is based on vertebrate proteins and has remained unchanged for over two decades. Here we report an exhaustive phylogenetic study of GluRs in metazoans. Importantly, we demonstrate that GluRs have followed different evolutionary histories in separated animal lineages. Our analysis reveals that the present organization of iGluRs into six classes does not capture the full complexity of their evolution. Instead, we propose an organization into four subfamilies and ten classes, four of which have never been previously described. Furthermore, we report a sister class to mGluR classes I-III, class IV. We show that many unreported proteins are expressed in the nervous system, and that new Epsilon receptors form functional ligand-gated ion channels. We propose an updated classification of glutamate receptors that includes our findings. Nerve cells or neurons communicate with each other by releasing specific molecules in the gap between them, the synapses. The sending neuron passes on messages through packets of chemicals called neurotransmitters, which are picked up by the receiving cell with the help of receptors on its surface. Neurons use different neurotransmitters to send different messages, but one of the most common ones is glutamate. There are two families of glutamate receptors: ionotropic receptors, which can open or close ion channels in response to neurotransmitters and control the transmission of a signal, and metabotropic receptors, which are linked to a specific protein and control the strength of signal. Our understanding of these two receptor families comes from animals with backbones, known as vertebrates. But the receptors themselves are ancient. We can trace the first family back as far as bacteria and the second back to single-celled organisms like amoebas. Vertebrates have six classes of ionotropic and three classes of metabotropic glutamate receptor. But other multi-celled animals also have these receptors, so this picture may not be complete. Here, Ramos-Vicente et al. mapped all major lineages of animals to reveal the evolutionary history of these receptors to find out if the receptor families became more complicated as brain power increased. The results showed that the glutamate receptors found in vertebrates are only a fraction of all the types that exist. In fact, before present-day animal groups emerged, the part of the genome that holds the ionotropic receptor genes duplicated three times. This formed four receptor subfamilies, and our ancestors had all of them. Across the animal kingdom, there are ten, not six, classes of ionotropic receptors and there is an extra class of metabotropic receptors. But only two subfamilies of ionotropic and three out of four metabotropic receptor classes are still present in vertebrates today. The current classification of glutamate receptors centers around vertebrates, ignoring other animals. But this new data could change that. A better knowledge of these new receptors could aid neuroscientists in better understanding the nervous system. And, using this technique to study other families of proteins could reveal more missing links in evolution.