Membrane-localized MET engages PVR to mediate extranuclear juvenile hormone signaling in <i>Aedes aegypti</i>

Abstract

Although Methoprene-tolerant (MET) is well established as the intracellular receptor mediating the genomic actions of juvenile hormone (JH) in insects, the identity of the receptor responsible for initiating extranuclear JH responses has remained elusive. In the yellow fever mosquito Aedes aegypti, we identify the platelet-derived growth factor- and vascular endothelial growth factor-receptor related (PVR) protein as a key mediator of membrane-initiated JH signaling. JH treatment induces robust PVR phosphorylation in the fat body of adult female mosquitoes. Disruption of PVR function suppresses JH-induced activation of the phospholipase C and phosphatidylinositol 3-kinase signaling pathways and impairs primary follicle growth during the previtellogenic stage. Strikingly, JH-induced PVR phosphorylation and downstream signaling require MET, specifically its ligand-binding activity, but not its DNA-binding domain. A subpopulation of MET localizes to the plasma membrane of fat body cells, where it physically interacts with PVR between 24 h postemergence and 24 h post–blood feeding, suggesting that membrane-localized MET functions as the extranuclear JH receptor. Transcriptomic analyses following RNA interference (RNAi)-mediated knockdown of Met or Pvr demonstrate that PVR broadly contributes to JH-regulated gene expression. Notably, PVR-dependent signaling modulates genes that are also regulated by nuclear MET and enables JH to regulate additional gene sets independently of MET-mediated transcriptional regulation. These findings uncover a previously unrecognized MET–PVR signaling axis and support an integrated model of JH action in which membrane and nuclear pathways cooperate to enhance the specificity and complexity of JH function during the previtellogenic phase in mosquitoes.