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Reconstitution of an N-AChR from Brugia malayi an evolved change in acetylcholine receptor accessory protein requirements in filarial parasites. PLoS Pathog 2022; 18:e1010962. [DOI: 10.1371/journal.ppat.1010962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 12/01/2022] [Accepted: 10/29/2022] [Indexed: 11/15/2022] Open
Abstract
Neurotransmission is an important target for anthelmintic drugs, where receptor characteristics and response can be examined through reconstitution ex vivo in Xenopus laevis oocytes. The homomeric ACR-16 nicotine sensitive acetylcholine receptors (N-AChRs) of several helminth species have been characterized in this way. Our efforts to reconstitute the N-AChR from the clade III filarial parasite, Brugia malayi using similar conditions, initially produced no detectable response. A robust response to acetylcholine is obtained from the closely related clade III parasite Ascaris suum, suggesting that specific changes have occurred between Ascaris and Brugia. N-AChRs from three species intermediate between A. suum and B. malayi were characterized to provide information on the cause. Maximal response to acetylcholine did not change abruptly, consistent with a discrete event, but rather decreased progressively from A. suum through Dracunculus medinensis, Gonglylonema pulchrum and Thelazia callipaeda. Receptor responses to the characteristic nicotine, and other agonists were generally similar. The decrease in maximal current did correlate with a delayed time to reach larger response. Together, this suggested that the failure to reconstitute the B. malayi N-AChR was one extreme of a progressive decrease and that an issue with synthesis of the receptor in oocytes was responsible. Addition of accessory proteins EMC-6, NRA-2 and NRA-4, in addition to RIC-3, produced a small, but measurable B. malayi N-AChR response. Pharmacological properties of a chimeric B. malayi N-AChR were equivalent to the other species, confirming the receptor response remains unchanged while its production is increasingly dependent on accessory proteins. One possibility is that loss of many subunits for acetylcholine receptors from the filarial nematode genome is linked to new subunit combinations that lead to such a dependence. This novel phylogenetic approach allowed the first characterization of a B. malayi AChR ex vivo and in doing so, provides a framework for the successful characterization of other receptors that have yet to be reconstituted.
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McHugh M, Williams P, Verma S, Powell-Coffman JA, Robertson AP, Martin RJ. Cholinergic receptors on intestine cells of Ascaris suum and activation of nAChRs by levamisole. Int J Parasitol Drugs Drug Resist 2020; 13:38-50. [PMID: 32470835 PMCID: PMC7256660 DOI: 10.1016/j.ijpddr.2020.04.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 04/13/2020] [Accepted: 04/14/2020] [Indexed: 11/19/2022]
Abstract
Cholinergic agonists, like levamisole, are a major class of anthelmintic drugs that are known to act selectively on nicotinic acetylcholine receptors (nAChRs) on the somatic muscle and nerves of nematode parasites to produce their contraction and spastic paralysis. Previous studies have suggested that in addition to the nAChRs found on muscle and nerves, there are nAChRs on non-excitable tissues of nematode parasites. We looked for evidence of nAChRs expression in the cells of the intestine of the large pig nematode, Ascaris suum, using RT-PCR and RNAscope in situ hybridization and detected mRNA of nAChR subunits in the cells. These subunits include components of the putative levamisole receptor in A. suum muscle: Asu-unc-38, Asu-unc-29, Asu-unc-63 and Asu-acr-8. Relative expression of these mRNAs in A. suum intestine was quantified by qPCR. We also looked for and found expression of G protein-linked acetylcholine receptors (Asu-gar-1). We used Fluo-3 AM to detect intracellular calcium changes in response to receptor activation by acetylcholine (as a non-selective agonist) and levamisole (as an L-type nAChR agonist) to look for evidence of functioning nAChRs in the intestine. We found that both acetylcholine and levamisole elicited increases in intracellular calcium but their signal profiles in isolated intestinal tissues were different, suggesting activation of different receptor sets. The levamisole responses were blocked by mecamylamine, a nicotinic receptor antagonist in A. suum, indicating the activation of intestinal nAChRs rather than G protein-linked acetylcholine receptors (GARs) by levamisole. The detection of nAChRs in cells of the intestine, in addition to those on muscles and nerves, reveals another site of action of the cholinergic anthelmintics and a site that may contribute to the synergistic interactions of cholinergic anthelmintics with other anthelmintics that affect the intestine (Cry5B).
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Affiliation(s)
- Mark McHugh
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
| | - Paul Williams
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Saurabh Verma
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Jo Anne Powell-Coffman
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA, USA
| | - Alan P Robertson
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA
| | - Richard J Martin
- Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, IA, USA.
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Doyle SR, Bourguinat C, Nana-Djeunga HC, Kengne-Ouafo JA, Pion SDS, Bopda J, Kamgno J, Wanji S, Che H, Kuesel AC, Walker M, Basáñez MG, Boakye DA, Osei-Atweneboana MY, Boussinesq M, Prichard RK, Grant WN. Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity. PLoS Negl Trop Dis 2017; 11:e0005816. [PMID: 28746337 PMCID: PMC5546710 DOI: 10.1371/journal.pntd.0005816] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 08/07/2017] [Accepted: 07/19/2017] [Indexed: 12/30/2022] Open
Abstract
Background Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana—exposed to more than a decade of regular ivermectin treatment—have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread. Methodology/Principal findings Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR. Conclusions/Significance This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations. Onchocerciasis is a human parasitic disease endemic across large areas of Sub-Saharan Africa, where more than 99% of the estimated 100 million people globally at-risk live. The microfilarial stage of Onchocerca volvulus causes pathologies ranging from mild itching to visual impairment and ultimately, irreversible blindness. Mass administration of ivermectin kills microfilariae and has an anti-fecundity effect on adult worms by temporarily inhibiting the development in utero and/or release into the skin of new microfilariae, thereby reducing morbidity and transmission. Phenotypic and genetic changes in some parasite populations that have undergone multiple ivermectin treatments in Cameroon and Ghana have raised concern that sub-optimal response to ivermectin's anti-fecundity effect may increase in frequency, reducing the impact of ivermectin-based control measures. We used next generation sequencing of small pools of parasites to define genome-wide genetic differences between phenotypically characterised good and sub-optimal responder parasites from Cameroon and Ghana, and identified multiple regions of the genome that differentiated the response types. These regions were largely different between parasites from these two countries but revealed common molecular pathways that might be involved in determining the extent of response to ivermectin's anti-fecundity effect. These data reveal a more complex than previously described pattern of genetic diversity among O. volvulus populations that differ in their geography and response to ivermectin treatment.
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Affiliation(s)
- Stephen R. Doyle
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Australia
- Wellcome Trust Sanger Institute, Hinxton, Cambridge, United Kingdom
- * E-mail: (SRD); (RKP); (WNG)
| | - Catherine Bourguinat
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada
| | - Hugues C. Nana-Djeunga
- Parasitology and Ecology Laboratory, Department of Animal Biology and Physiology, Faculty of Science, University of Yaoundé 1, Yaoundé, Cameroon
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
| | - Jonas A. Kengne-Ouafo
- Research Foundation in Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon
| | - Sébastien D. S. Pion
- Institut de Recherche pour le Développement (IRD), IRD UMI 233 TransVIHMI – Université Montpellier – INSERM U1175, Montpellier, France
| | - Jean Bopda
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Yaoundé, Cameroon
| | - Joseph Kamgno
- Centre for Research on Filariasis and other Tropical Diseases (CRFilMT), Yaoundé, Cameroon
- Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Yaoundé, Cameroon
| | - Samuel Wanji
- Research Foundation in Tropical Diseases and the Environment (REFOTDE), Buea, Cameroon
| | - Hua Che
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada
| | - Annette C. Kuesel
- UNICEF/UNDP/World Bank/World Health Organization Special Programme for Research and Training in Tropical Diseases (WHO/TDR), World Health Organization, Geneva, Switzerland
| | - Martin Walker
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, United Kingdom
| | - Maria-Gloria Basáñez
- London Centre for Neglected Tropical Disease Research, Department of Infectious Disease Epidemiology, Faculty of Medicine, School of Public Health, Imperial College London, United Kingdom
| | - Daniel A. Boakye
- Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana
| | - Mike Y. Osei-Atweneboana
- Department of Environmental Biology and Health Water Research Institute, Council for Scientific and Industrial Research (CSIR), Accra, Ghana
| | - Michel Boussinesq
- Institut de Recherche pour le Développement (IRD), IRD UMI 233 TransVIHMI – Université Montpellier – INSERM U1175, Montpellier, France
| | - Roger K. Prichard
- Institute of Parasitology, McGill University, Sainte Anne-de-Bellevue, Québec, Canada
- * E-mail: (SRD); (RKP); (WNG)
| | - Warwick N. Grant
- Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, Australia
- * E-mail: (SRD); (RKP); (WNG)
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Verma S, Kashyap SS, Robertson AP, Martin RJ. Functional genomics in Brugia malayi reveal diverse muscle nAChRs and differences between cholinergic anthelmintics. Proc Natl Acad Sci U S A 2017; 114:5539-5544. [PMID: 28487481 PMCID: PMC5448196 DOI: 10.1073/pnas.1619820114] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many techniques for studying functional genomics of important target sites of anthelmintics have been restricted to Caenorhabditis elegans because they have failed when applied to animal parasites. To overcome these limitations, we have focused our research on the human nematode parasite Brugia malayi, which causes elephantiasis. Here, we combine single-cell PCR, whole muscle cell patch clamp, motility phenotyping (Worminator), and dsRNA for RNAi for functional genomic studies that have revealed, in vivo, four different muscle nAChRs (M-, L-, P-, and N-). The cholinergic anthelmintics had different selectivities for these receptors. We show that motility and patch-clamp responses to levamisole and pyrantel, but not morantel or nicotine, require the unc-38 and/or unc-29 genes. Derquantel behaved as a competitive antagonist and distinguished M-nAChRs activated by morantel (Kb 13.9 nM), P-nAChRs activated by pyrantel (Kb 126 nM), and L-nAChRs activated by levamisole (Kb 0.96 µM) and bephenium. Derquantel was a noncompetitive antagonist of nicotine, revealing N-type nAChRs. The presence of four diverse nAChRs on muscle is perhaps surprising and not predicted from the C. elegans model. The diverse nAChRs represent distinguishable drug targets with different functions: Knockdown of unc-38+unc-29 (L- and/or P-receptors) inhibited motility but knockdown of acr-16+acr-26 (M- and/or N-receptors) did not.
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Affiliation(s)
- Saurabh Verma
- Department of Biomedical Sciences, Iowa State University, Ames, IA 50011
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Mostafa E, Storey B, Farghaly AM, Afify HAEH, Taha AAER, Wolstenholme AJ. Transient effects of levamisole on Brugia malayi microfilariae. INVERTEBRATE NEUROSCIENCE 2015; 15:5. [PMID: 26187649 DOI: 10.1007/s10158-015-0181-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Accepted: 07/09/2015] [Indexed: 11/30/2022]
Abstract
Levamisole is an anthelmintic drug that acts by activating nicotinic acetylcholine receptors at the nematode neuromuscular junction and causing paralysis. We measured the in vitro effects of levamisole on the motility of Brugia malayi microfilariae; after 2 h incubation the apparent IC50 was 2.68 mM. Lower drug concentrations, such as 1 mM, caused an immediate total paralysis that lasted for up to 1 h, but was completely reversed by 2 h of incubation. The 'recovered' parasites were still completely susceptible to application of a second nicotinic agonist, pyrantel.
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Affiliation(s)
- Eman Mostafa
- Department of Infectious Diseases, University of Georgia, 501 D.W. Brooks Drive, Athens, GA, 30602, USA
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