Cholinergic receptors on the nematode pharynx: an unexploited drug target

描述（由申请人提供）：被忽视的热带病（NTDs）包括由不同肠道线虫群引起的土壤传播蠕虫病（STHs）。寄生虫包括蛔虫、毛线虫和钩虫。这些感染很常见。例如，蛔虫病影响着全世界14亿人，最常见于3至8岁的儿童。控制这些线虫寄生虫依赖于有效的驱虫剂供应。以兽药为例，我们知道继续使用驱虫药化合物进行大规模化疗将导致耐药性。有必要为驱虫虫的发展确定新的靶点。曾经这样的部位是线虫咽上的烟碱乙酰胆碱受体。我们发现这种受体对目前使用的抗寄生虫药物没有反应。方法：此应用程序的具体目标是：1。用电流、电压和膜片钳技术表征猪咽nAChR反应。我们将检验这一假设，即猪咽nachr在药理学上不同于胆碱能驱虫药激活的肌肉nachr。2. 鉴定和克隆咽部特异性烟碱乙酰胆碱受体亚基。我们将确定nAChR亚基基因存在于需要产生功能性受体的咽。3. 使用电压和膜片钳技术表征非洲爪蟾卵母细胞咽胆碱能受体。我们将测试咽部nAChR亚基的表达导致功能受体与体内发现的药理学相似的假设。在这个项目完成后，我们将表征一个重要的新的潜在药物靶点寄生线虫的药理学。我们将鉴定出编码这些受体的基因。最后，我们将在一个适合筛选潜在的新驱虫剂的可访问平台上重组受体。本研究的长期目标是在适合药物发现筛选的平台（爪蟾卵母细胞）中提供来自一系列重要寄生虫物种的离子通道药物靶点。

DESCRIPTION (provided by applicant): The Neglected Tropical Diseases (NTDs) include the soil-transmitted helminthiases (STHs) which are caused by diverse groups of intestinal nematodes. The parasites include Ascaris, Trichuris and hookworms. These infections are common. Ascariasis for example, affects 1.4 billion people worldwide and is most common in children between the ages of 3 and 8. Control of these nematode parasites relies on an effective supply of anthelmintics. Taking veterinary medicine as an example, we know that continued use of anthelmintic compounds for mass chemotherapy will lead to drug resistance. There is a need to identify novel target sites for anthelmintic development. Once such site is the nicotinic acetylcholine receptor on the nematode pharynx. We have discovered this receptor does not respond to currently used anrthelmintic drugs. Approach: The specific aims of this application are: 1. Characterize nAChR responses in A. suum pharynx: using current-, voltage- & patch- clamp techniques. We will test the hypothesis that the A. suum pharynx nAChRs are pharmacologically distinct from the muscle nAChRs activated by cholinergic anthelmintics. 2. Identify & clone pharyngeal specific nicotinic acetylcholine receptor subunits. We will identify the nAChR subunit genes present in the pharynx required to produce functional receptors. 3. Characterize the pharyngeal cholinergic receptors in Xenopus laevis oocytes using voltage- & patch-clamp techniques. We will test the hypothesis that expression of pharyngeal nAChR subunits results in functioning receptors that are pharmacologically similar to those found in vivo. On completion of this project we will have characterized the pharmacology of an important new potential drug target in a parasitic nematode. We will have identified the genes that encode these receptors. Finally, we will have reconstituted the receptors in an accessible platform suitable for screening potential new anthelmintics. The longer term goal of this research is provide ion- channel drug targets from a range of important parasite species in a platform (Xenopus oocytes) suitable for drug discovery screening. PUBLIC HEALTH RELEVANCE: The Neglected Tropical Diseases (NTDs) include soil transmitted nematode parasites like ascariasis, trichuriasis and hookworm. Ascariasis, for example, is one of the most common human parasitic infections. 1.5 billion people worldwide have ascariasis, and the disease is most common in children between the ages of 3 and 8. Treatment of helminthiasis includes use of nicotinic anthelmintics like pyrantel and oxantel which selectively paralyze nematodes by activating cholinergic ion-channels (nAChRs) on their muscle. However, resistance to anthelmintics drugs is a real concern. We have identified a novel potential target site for new anthelmintics, the nAChR on the nematode pharynx, which is not sensitive to currently used drugs. We propose to characterize the pharmacological properties of this receptor, clone the component subunit genes and express the functional receptor in Xenopus oocytes. On completion of the project we will have characterized a potential new drug target (the pharynx nAChR) and reconstituted it in a platform (Xenopus laevis oocytes) suitable for screening compound libraries to identify new anthelmintic compounds.