Functional Characterization of a Novel Class of Morantel-Sensitive Acetylcholine Receptors in Nematodes.
Functional Characterization of a Novel Class of Morantel-Sensitive Acetylcholine Receptors in Nematodes.
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DOI：
10.1371/journal.ppat.1005267
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发表时间：
2015-12
期刊：
影响因子：
6.7
通讯作者：
Neveu C
中科院分区：
文献类型：
--
作者：
Courtot E;Charvet CL;Beech RN;Harmache A;Wolstenholme AJ;Holden-Dye L;O'Connor V;Peineau N;Woods DJ;Neveu C
乙酰胆碱受体是一种五聚体配体门控通道，在脊椎动物和无脊椎动物中都参与兴奋性神经传递。在线虫中，它们代表胆碱能激动剂或拮抗剂驱虫药物的主要靶标。尽管存在于线虫中的乙酰胆碱受体亚基基因的多样性很大，但迄今为止只有少数受体亚型被表征。有趣的是，影响人类或动物健康的寄生线虫拥有该基因家族的两个密切相关的成员，acr-26和acr-27，这在自由生活或植物寄生物种中基本上是不存在的。以反刍动物致病性寄生线虫捻转血矛线虫为模型，我们发现Hco-ACR-26和Hco-ACR-27在体肌细胞中共表达。我们证明了在非洲爪蟾卵母细胞中共表达Hco-ACR-26和Hco-ACR-27导致对驱虫剂莫仑太尔和噻嘧啶高度敏感的乙酰胆碱受体的功能性表达。重要的是，我们还报道了ACR-26和ACR-27，来自马的远亲寄生线虫，马副蛔虫，也形成了对这两种药物高度敏感的功能性乙酰胆碱受体。在秀丽隐杆线虫（一种自由生活的模式线虫）中，我们证明了异源表达H。捻转螺和马铃螺受体显著增加了其对莫仑太尔和噻嘧啶的敏感性，反映了在非洲爪蟾卵母细胞中观察到的药理学特性。我们的研究结果是第一个描述一类新的线虫体壁肌肉乙酰胆碱受体的重要分子决定因素。人类、牲畜和伴侣动物中寄生线虫感染的控制主要依赖于驱虫剂治疗。然而，驱虫药的滥用不可避免地导致了抗药性寄生虫的选择。在这方面，目前迫切需要增加我们对现有驱虫药的作用模式的了解，以及确定开发下一代驱虫化合物的新靶点。在本研究中，我们报告的功能和药理学特性的一种新的亚型的线虫乙酰胆碱门控离子通道在两个遥远的相关寄生线虫种：捻转血矛线虫和马副蛔虫。利用非洲爪蟾卵母细胞作为表达系统，我们发现这些受体由两个密切相关的基因acr-26和acr-27编码的亚基组成，它们广泛分布于感染人类和动物的寄生线虫中。我们进一步证明，这些受体代表了驱虫药莫仑太尔和噻嘧啶的分子靶点。螺杆在线虫模型秀丽隐杆线虫中作为转基因表达的捻转线虫和马疫霉受体都赋予了体内对莫仑太尔和噻嘧啶的敏感性。对于兽医和医学上重要的寄生线虫，这类新的胆碱能受体对于靶向药物筛选和相关驱虫剂组合的开发具有主要意义。
Acetylcholine receptors are pentameric ligand–gated channels involved in excitatory neuro-transmission in both vertebrates and invertebrates. In nematodes, they represent major targets for cholinergic agonist or antagonist anthelmintic drugs. Despite the large diversity of acetylcholine-receptor subunit genes present in nematodes, only a few receptor subtypes have been characterized so far. Interestingly, parasitic nematodes affecting human or animal health possess two closely related members of this gene family, acr-26 and acr-27 that are essentially absent in free-living or plant parasitic species. Using the pathogenic parasitic nematode of ruminants, Haemonchus contortus, as a model, we found that Hco-ACR-26 and Hco-ACR-27 are co-expressed in body muscle cells. We demonstrated that co-expression of Hco-ACR-26 and Hco-ACR-27 in Xenopus laevis oocytes led to the functional expression of an acetylcholine-receptor highly sensitive to the anthelmintics morantel and pyrantel. Importantly we also reported that ACR-26 and ACR-27, from the distantly related parasitic nematode of horses, Parascaris equorum, also formed a functional acetylcholine-receptor highly sensitive to these two drugs. In Caenorhabditis elegans, a free-living model nematode, we demonstrated that heterologous expression of the H. contortus and P. equorum receptors drastically increased its sensitivity to morantel and pyrantel, mirroring the pharmacological properties observed in Xenopus oocytes. Our results are the first to describe significant molecular determinants of a novel class of nematode body wall muscle AChR. The control of parasitic nematode infections in humans, livestock and companion animals is critically dependent on anthelmintic treatment. However, the indiscriminate use of anthelmintic drugs has inevitably led to the selection of resistant parasites. In this respect there is currently an urgent need to increase our knowledge of the mode of action of available anthelmintics as well as to identify novel targets for the development of next generation anthelmintic compounds. In the present study we report the functional and pharmacological characterization of a novel subtype of nematode acetylcholine-gated ion channel in two distantly related parasitic nematode species: Haemonchus contortus and Parascaris equorum. Using the Xenopus laevis oocyte as an expression system, we showed that these receptors are composed of subunits encoded by two closely related genes, acr-26 and acr-27 that are widely distributed in parasitic nematodes infecting humans and animals. We further demonstrate that these receptors represent a molecular target for the anthelmintics morantel and pyrantel. The H. contortus and P. equorum receptors expressed as transgenes in the nematode model Caenorhabditis elegans both confer morantel and pyrantel sensitivity in-vivo. For parasitic nematodes of veterinary and medical importance, this novel class of cholinergic receptor is of prime interest for target-based drug screening and the development of relevant anthelmintic combinations.