title: Functional co-expression of two insect nicotinic receptor subunits (Nlalpha3 and Nlalpha8) reveals the effects of a resistance-associated mutation (Nlalpha3) on neonicotinoid insecticides.
abstract: Neonicotinoid insecticides, such as imidacloprid, are selective agonists of insect nicotinic acetylcholine receptors (nAChRs) and are used extensively to control a variety of insect pest species. Previously, we have identified a nAChR point mutation (Y151S) associated with insecticide resistance in the brown planthopper Nilaparvata lugens. Although this mutation has been identified in two different N. lugens nAChR subunits (Nlalpha1 and Nlalpha3) because of difficulties in heterologous expression of Nlalpha3; its influence on agonist potency has been examined only in Nlalpha1-containing nAChRs. Here we describe the cloning of a novel nAChR subunit from N. lugens (Nlalpha8), together with evidence for its co-assembly with Nlalpha3 in native and recombinant nAChRs. This has, for the first time, enabled the functional effects of the Nlalpha3(Y151S) mutation to be examined. The Nlalpha3(Y151S) mutation has little effect on agonist potency of acetylcholine but has a dramatic effect on neonicotinoid insecticides (reducing I(max) values and increasing EC(50) values). The apparent affinity of neonicotinoids was higher and the effect of the Y151S mutation on neonicotinoid agonist potency was more profound in Nlalpha3-containing, rather than Nlalpha1-containing nAChR. We conclude that Nlalpha3- and Nlalpha1-containing nAChRs may be representative of two distinct insect nAChR populations.
authors.affiliation: Key Laboratory of Monitoring and Management of Plant Diseases and Insects, Ministry of Agriculture, College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Yixi
authors.forename: Zewen
authors.initials: Z
authors.lastname: Liu
authors.forename: Zhaojun
authors.initials: Z
authors.lastname: Han
authors.forename: Feng
authors.initials: F
authors.lastname: Song
authors.forename: Xiangmei
authors.initials: X
authors.lastname: Yao
authors.forename: Ying
authors.initials: Y
authors.lastname: Shao
authors.forename: Jian
authors.initials: J
authors.lastname: Li
authors.forename: Neil S
authors.initials: NS
authors.lastname: Millar
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000595:Amino Acid Sequence; D000818:Animals; D004305:Dose-Response Relationship, Drug; D029721:Drosophila Proteins; D004558:Electric Stimulation; D015870:Gene Expression / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology; D047468:Immunoprecipitation / Q000379:methods; D007313:Insecta; D007305:Insecticide Resistance / Q000187:drug effects / Q000235:genetics*; D007306:Insecticides / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects / Q000235:genetics; D008845:Microinjections / Q000379:methods; D008969:Molecular Sequence Data; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000494:pharmacology; D009865:Oocytes; D018408:Patch-Clamp Techniques; D017354:Point Mutation / Q000502:physiology*; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D029721:Drosophila Proteins; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D021122:Protein Subunits; D011978:Receptors, Nicotinic; C113681:nicotinic acetylcholine receptor alpha-subunits, Drosophila; C082359:imidacloprid; D000109:Acetylcholine