Nuss Andrew B, Ejendal Karin F K, Doyle Trevor B, Meyer Jason M, Lang Emma G, Watts Val J, Hill Catherine A
Department of Entomology, Purdue University, West Lafayette, Indiana, United States of America.
Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, Indiana, United States of America.
PLoS Negl Trop Dis. 2015 Mar 20;9(3):e0003515. doi: 10.1371/journal.pntd.0003515. eCollection 2015 Mar.
New mode-of-action insecticides are sought to provide continued control of pesticide resistant arthropod vectors of neglected tropical diseases (NTDs). We previously identified antagonists of the AaDOP2 D1-like dopamine receptor (DAR) from the yellow fever mosquito, Aedes aegypti, with toxicity to Ae. aegypti larvae as leads for novel insecticides. To extend DAR-based insecticide discovery, we evaluated the molecular and pharmacological characteristics of an orthologous DAR target, CqDOP2, from Culex quinquefasciatus, the vector of lymphatic filariasis and West Nile virus.
METHODS/RESULTS: CqDOP2 has 94.7% amino acid identity to AaDOP2 and 28.3% identity to the human D1-like DAR, hD1. CqDOP2 and AaDOP2 exhibited similar pharmacological responses to biogenic amines and DAR antagonists in cell-based assays. The antagonists amitriptyline, amperozide, asenapine, chlorpromazine and doxepin were between 35 to 227-fold more selective at inhibiting the response of CqDOP2 and AaDOP2 in comparison to hD1. Antagonists were toxic to both C. quinquefasciatus and Ae. aegypti larvae, with LC50 values ranging from 41 to 208 μM 72 h post-exposure. Orthologous DOP2 receptors identified from the African malaria mosquito, Anopheles gambiae, the sand fly, Phlebotomus papatasi and the tsetse fly, Glossina morsitans, had high sequence similarity to CqDOP2 and AaDOP2.
DAR antagonists represent a putative new insecticide class with activity against C. quinquefasciatus and Ae. aegypti, the two most important mosquito vectors of NTDs. There has been limited change in the sequence and pharmacological properties of the DOP2 DARs of these species since divergence of the tribes Culicini and Aedini. We identified antagonists selective for mosquito versus human DARs and observed a correlation between DAR pharmacology and the in vivo larval toxicity of antagonists. These data demonstrate that sequence similarity can be predictive of target potential. On this basis, we propose expanded insecticide discovery around orthologous DOP2 targets from additional dipteran vectors.
人们一直在寻找新作用模式的杀虫剂，以持续控制对杀虫剂产生抗性的被忽视热带病（NTDs）节肢动物媒介。我们之前从黄热病蚊子埃及伊蚊中鉴定出AaDOP2 D1样多巴胺受体（DAR）的拮抗剂，其对埃及伊蚊幼虫具有毒性，可作为新型杀虫剂的先导化合物。为了扩展基于DAR的杀虫剂发现，我们评估了来自致倦库蚊（淋巴丝虫病和西尼罗河病毒的传播媒介）的直系同源DAR靶点CqDOP2的分子和药理学特性。
方法/结果：CqDOP2与AaDOP2的氨基酸同一性为94.7%，与人类D1样DAR（hD1）的同一性为28.3%。在基于细胞的试验中，CqDOP2和AaDOP2对生物胺和DAR拮抗剂表现出相似的药理学反应。与hD1相比，拮抗剂阿米替林、氨磺必利、阿塞那平、氯丙嗪和多塞平在抑制CqDOP2和AaDOP2反应方面的选择性高35至227倍。拮抗剂对致倦库蚊和埃及伊蚊幼虫均有毒性，暴露72小时后的半数致死浓度（LC50）值在41至208μM之间。从非洲疟蚊冈比亚按蚊、白蛉巴氏白蛉和采采蝇莫氏采采蝇中鉴定出的直系同源DOP2受体与CqDOP2和AaDOP2具有高度序列相似性。
DAR拮抗剂代表了一种对致倦库蚊和埃及伊蚊（NTDs的两种最重要蚊子媒介）具有活性的新型杀虫剂类别。自库蚊族和伊蚊族分化以来，这些物种的DOP2 DARs的序列和药理学特性变化有限。我们鉴定出了对蚊子DARs与人类DARs具有选择性的拮抗剂，并观察到DAR药理学与拮抗剂的体内幼虫毒性之间存在相关性。这些数据表明序列相似性可预测靶点潜力。在此基础上，我们建议围绕来自其他双翅目媒介的直系同源DOP2靶点扩大杀虫剂发现。
