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Title
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A functional comparison of homopentameric nicotinic acetylcholine receptors (ACR-16) receptors from Necator americanus and Ancylostoma ceylanicum
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Author
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Abstract
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| Effective control of hookworm infections in humans and animals relies on using a small group of anthelmintics. Many of these drugs target cholinergic ligand-gated ion channels, yet the direct activity of anthelmintics has only been studied in a subset of these receptors, primarily in the non-parasitic nematode, Caenorhabditis elegans . Here we report the characterization of a homopentameric ionotropic acetylcholine receptor (AChR), ACR-16, from Necator americanus and Ancylostoma ceylanicum , the first known characterization of human hookworm ion channels. We used two-electrode voltage clamp electrophysiology in Xenopus laevis oocytes to determine the pharmacodynamics of cholinergics and anthelmintics on ACR-16 from both species of hookworm. The A. ceylanicum receptor (Ace-ACR-16) was more sensitive to acetylcholine (EC 50 = 20.64 ± 0.32 μM) and nicotine (EC 50 = 24.37 ± 2.89 μM) than the N. americanus receptor (Nam-ACR-16) (acetylcholine EC 50 = 170.1 ± 19.23 μM; nicotine EC 50 = 597.9 ± 59.12 μM), at which nicotine was a weak partial agonist (% maximal acetylcholine response = 30.4 ± 7.4%). Both receptors were inhibited by 500 μM levamisole (Ace-ACR-16 = 65.1 ± 14.3% inhibition, Nam-ACR-16 = 79.5 ± 7.7% inhibition), and responded to pyrantel, but only Ace-ACR-16 responded to oxantel. We used in silico homology modeling to investigate potential structural differences that account for the differences in agonist binding and identified a loop E isoleucine 130 of Nam-ACR-16 as possibly playing a role in oxantel insensitivity. These data indicate that key functional differences exist among ACR-16 receptors from closely related species and suggest mechanisms for differential drug sensitivity. |
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Language
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English
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Source (journal)
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Frontiers in Molecular Neuroscience
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Publication
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2020
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ISSN
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1662-5099
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DOI
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10.3389/FNMOL.2020.601102
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Volume/pages
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13
(2020)
, p. 1-19
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Article Reference
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601102
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ISI
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000596844700001
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Pubmed ID
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33324163
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Medium
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E-only publicatie
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Full text (Publisher's DOI)
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Full text (open access)
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