The non-canonical Notch signaling is essential for the control of fertility in Aedes aegypti

The Notch signaling pathway is a highly evolutionarily-conserved cell-cell signaling pathway that regulates many events during development. It plays a pivotal role in the regulation of fundamental cellular processes, such as cell proliferation, stem cell maintenance, and differentiation during embryonic and adult development. However, functions of Notch signaling in Aedes aegypti, the major mosquito vector for dengue, are largely unknown. In this study, we identified a unique feature of A. aegypti Notch (AaNotch) in the control of the sterile-like phenotype in female mosquitoes. Silencing AaNotch with a reverse genetic approach significantly reduced the fecundity and fertility of the mosquito. Silencing AaNotch also resulted in the prevention of micropyle formation, which led to impaired fertilization. In addition, JNK phosphorylation (a signaling molecule in the non-canonical Notch signaling pathway) was inhibited in the absence of AaNotch. Furthermore, treatment with a JNK inhibitor in the mosquito resulted in impaired fecundity and fertility. Taken together, our results demonstrate that non-canonical Notch signaling is essential for controlling fertility in the A. aegypti mosquito.
Author summary Mosquitoes transmit many devastating diseases, including malaria, dengue, and Zika, which together are responsible for over one million deaths per year. Major reasons for this tragic situation are the unavailability of effective vaccines and drugs for most mosquito-borne diseases, increased resistance of vectors to insecticides, and resistance of pathogens to currently available drugs. A thorough understanding of the molecular machinery involved in mosquito fertility is essential for developing vector control strategies. In this study, we observed a unique feature of the Aedes aegypti Notch (AaNotch) in the control of a sterile-like phenotype in female mosquitoes. Silencing AaNotch using a reverse genetic approach revealed significant reductions in fecundity and fertility. It also resulted in the abolishment of micropyles, which led to impaired fertilization. However, no effect on fecundity and fertility was observed in the absence of AaDelta, a canonical Notch transmembrane ligand. Although JNK is a downstream component of the non-canonical Notch signaling pathway, treatment with a JNK inhibitor resulted in impaired fecundity and fertility. In conclusion, our results demonstrate that Notch-dependent regulation of sterile-like female mosquitoes is controlled by non-canonical Notch signaling.