Two types of muscarinic acetylcholine receptors in Drosophila and other arthropods
Two types of muscarinic acetylcholine receptors in Drosophila and other arthropods
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DOI：
10.1007/s00018-013-1334-0
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发表时间：
2013-09-01
影响因子：
8
通讯作者：
Grimmelikhuijzen, Cornelis J. P.
中科院分区：
文献类型：
--
作者：
Collin, Caitlin;Hauser, Frank;Grimmelikhuijzen, Cornelis J. P.
毒蕈碱乙酰胆碱受体 (mAChR) 在哺乳动物神经系统中发挥着核心作用。这些受体是 G 蛋白偶联受体 (GPCR)，可被激动剂乙酰胆碱和毒蕈碱激活，并被多种拮抗剂阻断。哺乳动物有 5 个 mAChR (m1-m5)。在本研究中，我们从果蝇果蝇中克隆了两个结构相关的GPCR，在中国仓鼠卵巢细胞中表达后，被证明是毒蕈碱乙酰胆碱受体。一种 mAChR（A 型；由基因 CG4356 编码）被乙酰胆碱（EC50，5 x 10(-8) M）和毒蕈碱（EC50，6 x 10(-8) M）激活，并被经典 mAChR 拮抗剂阿托品、东莨菪碱和 3-quinuclidinyl-benzilate (QNB) 阻断，而另一种（B 型；由基因编码） CG7918) 也能被乙酰胆碱激活，但对毒蕈碱的敏感性低 1,000 倍，并且不会被拮抗剂阻断。还从赤拟谷盗中克隆了 A 型和 B 型 mAChR，并进行了功能表征。最近，哈加等人。 (Nature 2012, 482: 547-551) 发表了人 m2 mAChR 的晶体结构，揭示了形成 QNB 结合袋的 14 个氨基酸残基。这些残基在人 m2 与黑腹果蝇和赤霉 A 型 mAChR 之间是相同的，而其中许多残基在人 m2 与 B 型受体之间是不同的。利用生物信息学，在具有已测序基因组的所有其他节肢动物中也可以发现 A 型 mAChR 的一种直系同源物和 B 型 mAChR 的一种同源物。原口动物（例如节肢动物）和后口动物（例如哺乳动物和其他脊椎动物）属于两个在进化上截然不同的动物进化谱系，它们在大约 7 亿年前分裂。我们发现起源于这次分裂之前的动物，例如刺胞动物（Hydra），有两个 A 型 mAChR。根据这些数据，我们提出了 mAChR 进化模型。
Muscarinic acetylcholine receptors (mAChRs) play a central role in the mammalian nervous system. These receptors are G protein-coupled receptors (GPCRs), which are activated by the agonists acetylcholine and muscarine, and blocked by a variety of antagonists. Mammals have five mAChRs (m1-m5). In this study, we cloned two structurally related GPCRs from the fruit fly Drosophila melanogaster, which, after expression in Chinese hamster ovary cells, proved to be muscarinic acetylcholine receptors. One mAChR (the A-type; encoded by gene CG4356) is activated by acetylcholine (EC50, 5 x 10(-8) M) and muscarine (EC50, 6 x 10(-8) M) and blocked by the classical mAChR antagonists atropine, scopolamine, and 3-quinuclidinyl-benzilate (QNB), while the other (the B-type; encoded by gene CG7918) is also activated by acetylcholine, but has a 1,000-fold lower sensitivity to muscarine, and is not blocked by the antagonists. A- and B-type mAChRs were also cloned and functionally characterized from the red flour beetle Tribolium castaneum. Recently, Haga et al. (Nature 2012, 482: 547-551) published the crystal structure of the human m2 mAChR, revealing 14 amino acid residues forming the binding pocket for QNB. These residues are identical between the human m2 and the D. melanogaster and T. castaneum A-type mAChRs, while many of them are different between the human m2 and the B-type receptors. Using bioinformatics, one orthologue of the A-type and one of the B-type mAChRs could also be found in all other arthropods with a sequenced genome. Protostomes, such as arthropods, and deuterostomes, such as mammals and other vertebrates, belong to two evolutionarily distinct lineages of animal evolution that split about 700 million years ago. We found that animals that originated before this split, such as cnidarians (Hydra), had two A-type mAChRs. From these data we propose a model for the evolution of mAChRs.