title: Characterization of the target of ivermectin, the glutamate-gated chloride channel, from Anopheles gambiae.
abstract: The use of insecticide-treated nets and indoor residual insecticides targeting adult mosquito vectors is a key element in malaria control programs. However, mosquito resistance to the insecticides used in these applications threatens malaria control efforts. Recently, the mass drug administration of ivermectin (IVM) has been shown to kill Anopheles gambiae mosquitoes and disrupt Plasmodium falciparum transmission in the field. We cloned the molecular target of IVM from A. gambiae, the glutamate-gated chloride channel (AgGluCl), and characterized its transcriptional patterns, protein expression and functional responses to glutamate and IVM. AgGluCl cloning revealed an unpredicted fourth splice isoform as well as a novel exon and splice site. The predicted gene products contained heterogeneity in the N-terminal extracellular domain and the intracellular loop region. Responses to glutamate and IVM were measured using two-electrode voltage clamp on Xenopus laevis oocytes expressing AgGluCl. IVM induced non-persistent currents in AgGluCl-a1 and did not potentiate glutamate responses. In contrast, AgGluCl-b was insensitive to IVM, suggesting that the AgGluCl gene could produce IVM-sensitive and -insensitive homomultimers from alternative splicing. AgGluCl isoform-specific transcripts were measured across tissues, ages, blood feeding status and sex, and were found to be differentially transcribed across these physiological variables. Lastly, we stained adult, female A. gambiae for GluCl expression. The channel was expressed in the antenna, Johnston's organ, supraesophageal ganglion and thoracic ganglia. In summary, we have characterized the first GluCl from a mosquito, A. gambiae, and described its unique activity and expression with respect to it as the target of the insecticide IVM.
authors.affiliation: Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523-1617, USA Jacob.I.Meyers@gmail.com.
authors.forename: Jacob I
authors.initials: JI
authors.lastname: Meyers
authors.affiliation: Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, 1692 Campus Delivery, Fort Collins, CO 80523-1692, USA.
authors.forename: Meg
authors.initials: M
authors.lastname: Gray
authors.affiliation: Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, 1692 Campus Delivery, Fort Collins, CO 80523-1692, USA.
authors.forename: Wojtek
authors.initials: W
authors.lastname: Kuklinski
authors.affiliation: Department of Chemical and Biological Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, CO 80523-1370, USA.
authors.forename: Lucas B
authors.initials: LB
authors.lastname: Johnson
authors.affiliation: Department of Chemical and Biological Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, CO 80523-1370, USA.
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Snow
authors.affiliation: Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, 1692 Campus Delivery, Fort Collins, CO 80523-1692, USA.
authors.forename: William C
authors.initials: WC
authors.lastname: Black
authors.affiliation: Department of Biomedical Sciences, Colorado State University, 1617 Campus Delivery, Fort Collins, CO 80523-1617, USA.
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Partin
authors.affiliation: Arthropod-borne and Infectious Diseases Laboratory, Department of Microbiology, Immunology and Pathology, Colorado State University, 1692 Campus Delivery, Fort Collins, CO 80523-1692, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Foy
mesh_terms: D000367:Age Factors; D017398:Alternative Splicing; D000818:Animals; D000852:Anopheles / Q000187:drug effects* / Q000378:metabolism; D018118:Chloride Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology; D007303:Insect Vectors; D007306:Insecticides / Q000494:pharmacology*; D007559:Ivermectin / Q000494:pharmacology*; D008297:Male; D009865:Oocytes / Q000502:physiology; D014982:Xenopus laevis
chemical_list: D018118:Chloride Channels; D007306:Insecticides; C109777:glutamate-gated chloride channels; D018698:Glutamic Acid; D007559:Ivermectin
keywords: Anopheles gambiae; Glutamate-gated chloride channel; Ivermectin