Investigation of acetylcholine receptor diversity in a nematode parasite leads to characterization of tribendimidine- and derquantel-sensitive nAChRs.
Nicotinic acetylcholine receptors (nAChRs) of parasitic nematodes are required for body movement and are targets of important "classical" anthelmintics like levamisole and pyrantel, as well as "novel" anthelmintics like tribendimidine and derquantel. Four biophysical subtypes of nAChR have been observed electrophysiologically in body muscle of the nematode parasite Oesophagostomum dentatum, but their molecular basis was not understood. Additionally, loss of one of these subtypes (G 35 pS) was found to be associated with levamisole resistance. In the present study, we identified and expressed in Xenopus oocytes, four O. dentatum nAChR subunit genes, Ode-unc-38, Ode-unc-63, Ode-unc-29 and Ode-acr-8, to explore the origin of the receptor diversity. When different combinations of subunits were injected in Xenopus oocytes, we reconstituted and characterized four pharmacologically different types of nAChRs with different sensitivities to the cholinergic anthelmintics. Moreover, we demonstrate that the receptor diversity may be affected by the stoichiometric arrangement of the subunits. We show, for the first time, different combinations of subunits from a parasitic nematode that make up receptors sensitive to tribendimidine and derquantel. In addition, we report that the recombinant levamisole-sensitive receptor made up of Ode-UNC-29, Ode-UNC-63, Ode-UNC-38 and Ode-ACR-8 subunits has the same single-channel conductance, 35 pS and 2.4 ms mean open-time properties, as the levamisole-AChR (G35) subtype previously identified in vivo. These data highlight the flexible arrangements of the receptor subunits and their effects on sensitivity and resistance to the cholinergic anthelmintics; pyrantel, tribendimidine and/or derquantel may still be effective on levamisole-resistant worms.
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America ; INRA, UR1282 Infectiologie Animale et Santé Publique, Nouzilly, France.
Samuel K
SK
Buxton
INRA, UR1282 Infectiologie Animale et Santé Publique, Nouzilly, France ; Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, Tours, France.
Claude L
CL
Charvet
INRA, UR1282 Infectiologie Animale et Santé Publique, Nouzilly, France ; Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, Tours, France.
Cedric
C
Neveu
INRA, UR1282 Infectiologie Animale et Santé Publique, Nouzilly, France ; Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, Tours, France.
Jacques
J
Cabaret
INRA, UR1282 Infectiologie Animale et Santé Publique, Nouzilly, France ; Université François Rabelais de Tours, UMR1282 Infectiologie et Santé Publique, Tours, France.
Jacques
J
Cortet
Université François Rabelais de Tours, Département de Physiologie Animale, Tours, France.
Nicolas
N
Peineau
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America.
Melanie
M
Abongwa
INRA, UR1282 Infectiologie Animale et Santé Publique, Nouzilly, France.
Elise
E
Courtot
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America.
Alan P
AP
Robertson
Department of Biomedical Sciences, College of Veterinary Medicine, Iowa State University, Ames, Iowa, United States of America.
Richard J
RJ
Martin
D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology*; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology*; D009348:Nematoda / Q000235:genetics / Q000378:metabolism*; D010082:Oxepins / Q000494:pharmacology*; D010655:Phenylenediamines / Q000494:pharmacology*; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D000871:Anthelmintics; D015801:Helminth Proteins; D007211:Indoles; D010082:Oxepins; D010655:Phenylenediamines; D011978:Receptors, Nicotinic; C575297:derquantel; C056017:tribendimidine