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.
Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.
Darran M
DM
Yates
Adrian J
AJ
Wolstenholme
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