E93 and its kinase-mediated S530 phosphorylation regulate ovarian development and oogenesis in Nilaparvata lugens via Egfr and Cpr83

Insect reproduction serves as a primary target for insecticide development and resistance management in insects. Ovarian development, a key determinant of insect reproduction, is tightly regulated through complex signaling pathways. Here we reported that AKT-E93 signaling pathway governing ovarian development and oogenesis in Nilaparvata lugens via two key genes Epidermal Growth Factor Receptor ( Egfr ) and cuticular protein gene Cpr83 . Silencing Akt inhibited ovarian development and oocyte budding at the later nymph stage. Phosphoproteome analyses identified 20 transcription factors (TFs) with a lost site phosphorylation after Akt silencing, among which E93 was found essential for oocyte budding. E93 is abundantly distributed in follicular cells, and silencing E93 produced a comparable phenotype as Akt RNAi. Silencing Akt and E93 down-regulated expression of Egfr and three cuticular protein genes ( Cpr33 , Cpr83 and Cpr95 ), but only silencing Egfr and Cpr83 led to an obvious suppression of ovarian development. Specifically, silencing Egfr mainly inhibited ovarian development, while silencing Cpr83 led to failure of oogenesis. AKT was identified as modulators of E93 through phosphorylation at serine 530 (S530). These kinases phosphorylated E93 to obtain three patterns in regulating Egfr and Cpr83 expression, suppressing, enhancing and maintaining. These findings reveal a novel mechanism in insects that AKT regulates ovarian development via phosphorylation of E93 at S530 site, which subsequently modulates Egfr and Cpr83 expression. As a node of reproduction regulation, the proteins involved in ovarian development would be targets to develop reproduction suppressants in insects.