The vitellogenin receptor functionality of the migratory locust depends on its phosphorylation by juvenile hormone

Vitellogenin receptor (VgR) plays a pivotal role in ovarian vitello-genin (Vg) uptake and vertical transmission of pathogenic microbes and Wolbachia symbionts. However, the regulatory mechanisms of VgR action as an endocytic receptor and translocation from oocyte cytoplasm to the membrane remain poorly understood. Here, by using the migratory locust Locusta migratoria as a model system, we report that juvenile hormone (JH) promotes VgR phosphorylation at Ser(1361) in the second EGF-precursor homology domain. A signaling cascade including GPCR, PLC, extracellular calcium, and PKC-iota is involved in JH-stimulated VgR phosphorylation. This post-translational regulation is a prerequisite for VgR binding to Vg on the external surface of the oocyte membrane and subsequent VgR/Vg endocytosis. Acidification, a condition in endosomes, induces VgR dephosphorylation along with the dissociation of Vg from VgR. Phosphorylation modification is also required for VgR recycling from oocyte cytoplasm to the membrane. Additionally, VgR phos-phorylation and its requirement for Vg uptake and VgR recycling are evolutionarily conserved in other representative insects including the cockroach Periplaneta americana and the cotton bollworm Helicoverpa armigera. This study fills an important knowledge gap of low-density lipoprotein receptors in posttranslational regulation, endocytosis, and intracellular recycling.

Automated summary

Using the migratory locust as a model system, the study found that juvenile hormone promotes phosphorylation of Vitellogenin receptor, which is essential for Vitellogenin uptake and recycling. This phosphorylation regulation is evolutionarily conserved in other insects as well.