BHLH transcription factors: Potential target sites for insecticide development

A superfamily of transcription factors containing the bHLH domain plays important roles in the control of cell proliferation, determination and tissue differentiation during the development of animals and plants. Several genes coding for bHLH transcription factors have been identified in various organisms. The bHLH-PAS domain containing transcription factors constitute one of the families of bHLH superfamily. One of the important members of the bHLH-PAS family identified in insects is Methoprene tolerant (Met) from Drosophila melanogaster. Suppression of Met expression by the injection of Met dsRNA in the third or fourth larval instars causes precocious metamorphosis and precocious development of adult structures suggesting that Met plays a key role in juvenile hormone (JH) signal transduction. Several insecticides targeting Met that function as JH agonists are being used to control insects. In this chapter, we will review literature on the structure, function of bHLH transcription factors in insects, and discuss their potential as target sites for discovering new insecticides.