20E-dependent tyrosine phosphorylation of phospholipase C gamma underpins egg development in the malaria vector Anopheles gambiae

The efficient development of eggs following a blood meal is central to the vector capacity of Anopheles gambiae females. The ecdysteroid hormone 20-hydroxyecdysone (20E) plays a pivotal role in this process, yet the signaling mechanisms by which 20E exerts its effects remain incompletely understood. Here we show blood feeding is associated with increased tyrosine phosphorylation of an array of proteins coincident with the increase in titers of 20E that follows a blood meal. Injection of genistein, a tyrosine kinase inhibitor, reduces both the appearance of phosphotyrosine-containing proteins and fecundity, linking tyrosine phosphorylation to egg development. We identify one of the proteins phosphorylated after a blood meal as phospholipase C gamma (PLC{gamma}) and show that its blood feeding-induced phosphorylation is dependent on endogenously synthesized 20E via the ecdysone receptor (EcR). Interruption of Src-like tyrosine kinase signaling inhibits phosphorylation of PLC{gamma} as well as egg development after blood feeding, implicating Src-like kinases in the phosphorylation of PLC{gamma}. Taken together, these data suggest that the effects of 20E on An. gambiae egg development are at least partially mediated through a tyrosine phosphorylation-dependent signaling cascade involving Src family tyrosine kinases and PLC{gamma}.