An ivermectin-sensitive glutamate-gated chloride channel subunit from Dirofilaria immitis.
Dirofilaria immitis is a filarial nematode that infects dogs and causes cardiopulmonary disease. The most effective way of controlling the infection is by chemoprophylaxis, using members of the avermectin/milbemycin (A/M) class of anthelmintics, which includes ivermectin; these drugs act at invertebrate glutamate-gated chloride channels (GluCl). We have cloned two cDNAs encoding D. immitis GluCl subunits and demonstrated that at least one may be an important molecular target for the A/Ms in vivo. The subunits are orthologues of the alternatively spliced GluClalpha3A and alpha3B subunits (encoded by the avr-14 gene) previously identified in Caenorhabditis elegans and in Haemonchus contortus. Although the alternative splicing of avr-14 is conserved across the species, the processing of the mature GluClalpha3A mRNA differs in D. immitis compared to C. elegans and H. contortus. Two-electrode voltage clamp recordings were made from Xenopus oocytes injected with subunit-specific cRNAs. The DiGluClalpha3B subunit formed channels that were gated by L-glutamate (1-100 mM) and ivermectin (1 microM). Oocytes injected with DiGluClalpha3A cRNA failed to respond to L-glutamate. The qualitative responses obtained were consistent with the pharmacology observed for the GluClalpha3 subunits from C. elegans and H. contortus.
Yates
Darran M
DM
Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
Wolstenholme
Adrian J
AJ
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D018118:Chloride Channels / Q000187:drug effects* / Q000378:metabolism; D004183:Dirofilaria immitis / Q000187:drug effects* / Q000235:genetics; D005369:Filaricides / Q000494:pharmacology*; D007559:Ivermectin / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D016415:Sequence Alignment; D014981:Xenopus / Q000378:metabolism
D018118:Chloride Channels; D005369:Filaricides; C109777:glutamate-gated chloride channels; D007559:Ivermectin