Discovery of GPCR-targeted insecticides for malaria mosquito control

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Project Summary/Abstract Numerous species of mosquitoes are vectors of many pathogens that cause devastating infectious diseases, such as malaria, Dengue, yellow fever, and Zika fever. More than 1 million deaths and up to 700 million cases of infections by mosquito-borne vector diseases (nearly 10% of the total world population) are reported each year. The use of chemical insecticides has been a highly efficient method for the disruption of the pathogen transmission cycle by suppressing the vector population, whereas the evolution of insecticide resistance has hampered the efficacy of currently available classes of insecticides. We propose to establish a new approach for the development of a novel class of mosquitocidal compounds. In the era of new biotechnology, the search for small bioactive compounds using high throughput screening (HTS) is now a robust and accessible technology that can offer substantive dividends for users. The target molecule for the HTS assay we propose is a G protein-coupled receptor (GPCR), named ecdysis-triggering hormone receptor (ETH-R), which is a receptor for a crucial hormone in the unique biology of arthropods for shedding of their external cuticle during molting and for regulation of another crucial endocrine factor juvenile hormone in mosquito. The ETH-R is an ideal target that will allow for the identification of an effective product with significantly improved selectivity toward mammals and even different orders of insects, which will permit the suppression of the mosquito population without significant environmental damage. Target-based discovery of insecticidal compounds will provide a novel example of a biorational approach for the development of pesticide. In this proposal, we aim to identify compounds that act on ETH receptor of the most devastating malaria mosquito (Anopheles gambiae, AgETH-R) by using HTS. We will also identify the structure of the peptide ligands ETH to understand the chemical interaction of the ligand on the binding pocket of the ETH-R. Four investigators in two different Universities will collaborate for the Specific Aims that require diverse areas of disciplines. The specific aims are: 1) High throughput screening for identifying agonists and antagonists acting on AgETH-R [Drs. Roy and Park], 2) Nuclear magnetic resonance (NMR) spectroscopy to determine the structures of AgETH and similar peptide ligands [Drs. Prakash and Park], and 3) Cheminformatics to identify the chemical signature of the hits and the chemical clusters for further tests [Drs. Huan and Park].