Dopamine/Ecdysteroid Receptor Regulates Insect Development By Binding 20-hydroxyecdysone

BackgroundInsects are the largest and most widely distributed animal community on earth.The growth and development of insects are mainly regulated by the conteractive regulation of juvenile hormone(JH)and 20-hydroxyecdysone(20E).During the growth period of insect feeding,the titer of JH is high and the 20E is low.However,the JH is gradually decresed or until zero and the 20E is gradually increased during the metamorphosis of insects.The two kinds of hormones are antagonistic and unified to regulate the molting and metamorphosis of insects.Researches prove steroid hormones exist classical genomic pathway.20E can across the plasma membrane and enter cells through free diffusion,and bind nuclear receptors to start gene transcription.In recent years,researches discover the nongenomic pathway of 20E,such as rapid phosphorylation and displacement of intracellular proteins,intracellular calcium mobilization.It is also found that G-protein-coupled receptors(GPCRs)involve in the nongenomic pathway of steroid hormone.And different GPCRs have different mechanisms.Therefore,the studies of involvenent of GPCRs in the nongenomic pathway of 20E become a focus of attention.Our laboratory has demonstrated that ErGPCRl and ErGPCR 2 are involved in the nongenomic pathway of 20E.Some dopamine receptor(DopEcR)is also involved in the signaling of 20F.But the mechanism is unclear.This paper carried out related research on Helicoverpa armigera to explore the mechanism of DopEcR in regulating the nongenomic pathway of 20E.Results and ConclusionHere,using a lepidopteran insect H.armigera as a model,DopEcR was expressed in different orgnization,including epidermis,midgut,fat body,and in the highest amount of expression in brain.DopEcR has a tendency to rise in brain and midgut at molting and metamorphic molting.DopEcR was upregulated by 20E.DopEcR was involved in 20E-induced rapid increase of intracellular calcium ion,gene expression and insect metamorphosis.DopEcR was located on the plasma membrane without internalization by 20E exciting.Knockdown of DopEcR by RNA interference reduced the binding of 20E to plasma membrane.Overexpression of DopEcR increased the binding of 20E to plasma membrane.DopEcR could bind 20E after being isolated;however,the binding-site mutant of DopEcR decreased capacity to bind 20E.Our study suggested 20E upregulates DopEcR expression for transmitting 20E signal to regulate insect development.Highlights and significanceThe binding of DopEcR and 20E was demonstrated by a new method of laboratory discussion in addition to the basic research of the existing technical methods in the laboratory.This method provides reference for the identification of other ligands and receptors.And this study improved and enriched the theoretical knowledge of insect growth and development and the signal pathway of 20E.It provides a theoretical basis for the prevention and treatment of natural insects.