Regulation of Antimicrobial Peptides in Aedes aegypti Aag2 Cells

Abstract

Antimicrobial peptides (AMPs) are an important group of immune effectors that play a role in combating microbial infections in invertebrates. Most of the current information on the regulation of insect AMPs in microbial infection have been gained from <i>Drosophila</i>, and their regulation in other insects are still not completely understood. Here, we generated an AMP induction profile in response to infections with some Gram-negative, -positive bacteria, and fungi in <i>Aedes aegypti</i> embryonic Aag2 cells. Most of the AMP inductions caused by the gram-negative bacteria was controlled by the Immune deficiency (Imd) pathway; nonetheless, <i>Gambicin</i>, an <i>AMP</i> gene discovered only in mosquitoes, was combinatorially regulated by the Imd, Toll and JAK-STAT pathways in the Aag2 cells. <i>Gambicin</i> promoter analyses including specific sequence motif deletions implicated these three pathways in <i>Gambicin</i> activity, as shown by a luciferase assay. Moreover, the recognition between Rel1 (refer to Dif/Dorsal in <i>Drosophila</i>) and STAT and their regulatory sites at the <i>Gambicin</i> promoter site was validated by a super-shift electrophoretic mobility shift assay (EMSA). Our study provides information that increases our understanding of the regulation of <i>AMP</i>s in response to microbial infections in mosquitoes. And it is a new finding that the <i>A. aegypti</i> AMPs are mainly regulated Imd pathway only, which is quite different from the previous understanding obtained from Drosophila.