title: Evolution, Expression, and Function of Nonneuronal Ligand-Gated Chloride Channels in Drosophila melanogaster.
abstract: Ligand-gated chloride channels have established roles in inhibitory neurotransmission in the nervous systems of vertebrates and invertebrates. Paradoxically, expression databases in Drosophila melanogaster have revealed that three uncharacterized ligand-gated chloride channel subunits, CG7589, CG6927, and CG11340, are highly expressed in nonneuronal tissues. Furthermore, subunit copy number varies between insects, with some orders containing one ortholog, whereas other lineages exhibit copy number increases. Here, we show that the Dipteran lineage has undergone two gene duplications followed by expression-based functional differentiation. We used promoter-GFP expression analysis, RNA-sequencing, and in situ hybridization to examine cell type and tissue-specific localization of the three D. melanogaster subunits. CG6927 is expressed in the nurse cells of the ovaries. CG7589 is expressed in multiple tissues including the salivary gland, ejaculatory duct, malpighian tubules, and early midgut. CG11340 is found in malpighian tubules and the copper cell region of the midgut. Overexpression of CG11340 increased sensitivity to dietary copper, and RNAi and ends-out knockout of CG11340 resulted in copper tolerance, providing evidence for a specific nonneuronal role for this subunit in D. melanogaster Ligand-gated chloride channels are important insecticide targets and here we highlight copy number and functional divergence in insect lineages, raising the potential that order-specific receptors could be isolated within an effective class of insecticide targets.
authors.affiliation: School of BioSciences, University of Melbourne, Victoria 3010, Australia Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia Behaviour and Genetics of Social Insects Laboratory, School of Life and Environmental Sciences, University of Sydney, New South Wales 2006, Australia emily.remnant@sydney.edu.au.
authors.forename: Emily J
authors.initials: EJ
authors.lastname: Remnant
authors.affiliation: School of BioSciences, University of Melbourne, Victoria 3010, Australia Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
authors.forename: Adam
authors.initials: A
authors.lastname: Williams
authors.affiliation: School of BioSciences, University of Melbourne, Victoria 3010, Australia Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Lumb
authors.affiliation: School of BioSciences, University of Melbourne, Victoria 3010, Australia Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
authors.forename: Ying Ting
authors.initials: YT
authors.lastname: Yang
authors.affiliation: School of BioSciences, University of Melbourne, Victoria 3010, Australia Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
authors.forename: Janice
authors.initials: J
authors.lastname: Chan
authors.affiliation: Charles Perkins Centre, School of Life and Environmental Sciences, University of Sydney, New South Wales 2006, Australia.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Duchêne
authors.affiliation: School of BioSciences, University of Melbourne, Victoria 3010, Australia Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
authors.forename: Phillip J
authors.initials: PJ
authors.lastname: Daborn
authors.affiliation: School of BioSciences, University of Melbourne, Victoria 3010, Australia Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
authors.forename: Philip
authors.initials: P
authors.lastname: Batterham
authors.affiliation: School of BioSciences, University of Melbourne, Victoria 3010, Australia Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
authors.forename: Trent
authors.initials: T
authors.lastname: Perry
mesh_terms: D000818:Animals; D018118:Chloride Channels / Q000235:genetics* / Q000378:metabolism; D019327:Copper Sulfate / Q000494:pharmacology; D030541:Databases, Genetic; D004331:Drosophila melanogaster / Q000145:classification / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005260:Female; D041981:Gastrointestinal Tract / Q000166:cytology / Q000378:metabolism; D018628:Gene Dosage; D020440:Gene Duplication; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D017403:In Situ Hybridization; D007814:Larva / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D008317:Malpighian Tubules / Q000166:cytology / Q000378:metabolism; D010053:Ovary / Q000166:cytology / Q000378:metabolism; D010802:Phylogeny; D011401:Promoter Regions, Genetic; D021122:Protein Subunits / Q000235:genetics* / Q000378:metabolism; D012469:Salivary Glands / Q000166:cytology / Q000378:metabolism; D017423:Sequence Analysis, RNA
chemical_list: D018118:Chloride Channels; D021122:Protein Subunits; D049452:Green Fluorescent Proteins; D019327:Copper Sulfate
keywords: copper tolerance; copy number variation; gene duplication; ligand-gated chloride channel; nonneuronal expression