Discovery and characterization of a potent and selective inhibitor of Aedes aegypti inward rectifier potassium channels.
Vector-borne diseases such as dengue fever and malaria, which are transmitted by infected female mosquitoes, affect nearly half of the world's population. The emergence of insecticide-resistant mosquito populations is reducing the effectiveness of conventional insecticides and threatening current vector control strategies, which has created an urgent need to identify new molecular targets against which novel classes of insecticides can be developed. We previously demonstrated that small molecule inhibitors of mammalian Kir channels represent promising chemicals for new mosquitocide development. In this study, high-throughput screening of approximately 30,000 chemically diverse small-molecules was employed to discover potent and selective inhibitors of Aedes aegypti Kir1 (AeKir1) channels heterologously expressed in HEK293 cells. Of 283 confirmed screening 'hits', the small-molecule inhibitor VU625 was selected for lead optimization and in vivo studies based on its potency and selectivity toward AeKir1, and tractability for medicinal chemistry. In patch clamp electrophysiology experiments of HEK293 cells, VU625 inhibits AeKir1 with an IC50 value of 96.8 nM, making VU625 the most potent inhibitor of AeKir1 described to date. Furthermore, electrophysiology experiments in Xenopus oocytes revealed that VU625 is a weak inhibitor of AeKir2B. Surprisingly, injection of VU625 failed to elicit significant effects on mosquito behavior, urine excretion, or survival. However, when co-injected with probenecid, VU625 inhibited the excretory capacity of mosquitoes and was toxic, suggesting that the compound is a substrate of organic anion and/or ATP-binding cassette (ABC) transporters. The dose-toxicity relationship of VU625 (when co-injected with probenecid) is biphasic, which is consistent with the molecule inhibiting both AeKir1 and AeKir2B with different potencies. This study demonstrates proof-of-concept that potent and highly selective inhibitors of mosquito Kir channels can be developed using conventional drug discovery approaches. Furthermore, it reinforces the notion that the physical and chemical properties that determine a compound's bioavailability in vivo will be critical in determining the efficacy of Kir channel inhibitors as insecticides.
Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, United States of America; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America.
Rene
R
Raphemot
Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, United States of America.
Matthew F
MF
Rouhier
Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, United States of America.
Daniel R
DR
Swale
Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America.
Emily
E
Days
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America.
C David
CD
Weaver
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America.
Kimberly M
KM
Lovell
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America.
Leah C
LC
Konkel
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America.
Darren W
DW
Engers
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America.
Sean R
SR
Bollinger
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America.
Sean F
SF
Bollinger
Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Institute for Global Health, Vanderbilt University, Nashville, TN, United States of America; Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America.
Corey
C
Hopkins
Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, United States of America.
Peter M
PM
Piermarini
Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, United States of America; Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America; Institute for Global Health, Vanderbilt University, Nashville, TN, United States of America.
Jerod S
JS
Denton
D000330:Aedes / Q000187:drug effects*; D000818:Animals; D004347:Drug Interactions; D057809:HEK293 Cells; D006801:Humans; D007306:Insecticides / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects; D026902:Potassium Channel Blockers / Q000494:pharmacology*; D024661:Potassium Channels, Inwardly Rectifying / Q000037:antagonists & inhibitors*; D011339:Probenecid / Q000494:pharmacology; D014981:Xenopus
D007306:Insecticides; D026902:Potassium Channel Blockers; D024661:Potassium Channels, Inwardly Rectifying; D011339:Probenecid