Identification and characterization of the catalytic subunit of phosphatidylinositol 3-kinase in the yellow fever mosquito Aedes aegypti.

We characterized the catalytic subunit of phosphatidylinositol 3-kinase in Aedes aegypti (Aaegp110). Aaegp110 is an essential component of the insulin/ insulin growth factor I signaling (IIS) cascade, which regulates aging, reproduction, and other physiological processes in diverse organisms. The Aaegp110 gene encodes five putative domains (adapter binding, ras binding, C2, helical, and PI3-kinase) identified by sequence homology with other p110 proteins. Aaegp110 transcript was expressed during all A. aegypti life stages except late pupae, with particularly high levels in embryos. In female tissues, Aaegp110 transcript and protein were strongly expressed in ovaries, and moderately expressed in midguts, fat bodies and heads. The importance of IIS in mosquito reproduction led us to examine Aaegp110 ovarian expression during reproduction. Aaegp110 was expressed in ovaries prior to and during the first 24h post-bloodmeal, but undetectable 36-48 h post-bloodmeal. Following oviposition Aaegp110 protein levels returned to pre-bloodmeal levels. In reproductively arrested ovaries, Aaegp110 was present predominantly in the cytoplasm of follicle cells surrounding the oocyte. In vitro stimulation of the ovaries with 17 microM bovine insulin resulted in translocation of Aaegp110 from the cytoplasm to cell membrane in 15s. Lower concentrations (0.17 microM) also recruited Aaegp110 to the cell membrane.