Identification of G protein-coupled receptors required for vitellogenesis and egg development in an insect with panoistic ovary

G protein-coupled receptors (GPCRs), a superfamily of integral transmembrane proteins regulate a variety of physiological processes in insects. Juvenile hormone (JH) is known to stimulate Vitellogenin (Vg) synthesis in the fat body, secretion into the hemolymph and uptake by developing oocytes. However, the role of GPCRs in JH-dependent insect vitellogenesis and oocyte maturation remains elusive. In the present study, we performed transcriptomic analysis and RNA interference (RNAi) screening in vitellogenic females of the migratory locustLocusta migratoria. Of 22 GPCRs identified in ovarian transcriptome,LGR4,OR-A1,OR-A2,Mthl1,Mthl5andSmowere most abundant in the ovary. By comparison,mAChR-Cexpressed at higher levels in the fat body, whereasOct/TyrR,OAR beta,AdoRandADGRA3were at higher expression levels in the brain. Our RNAi screening demonstrated that knockdown of sixGPCRs resulted in defective phenotypes of Vg accumulation in developing oocytes, accompanied by blocked ovarian development and impaired oocyte maturation. While LGR4 and Oct/TyrR appeared to control Vg synthesis in the fat body, OR-A1, OR-A2, mAChR-C and CirlL regulated Vg transportation and uptake. The findings provide fundamental evidence for deciphering the regulatory mechanisms of GPCRs in JH-stimulated insect reproduction.

Automated summary

This study identified the key role of specific GPCRs in vitellogenesis and oocyte maturation in the migratory locust through transcriptomic analysis and RNA interference screening. These findings provide fundamental evidence for understanding the regulatory mechanisms of GPCRs in JH-stimulated insect reproduction.