PGRP-LE Plays a Critical Role in Gut Antimicrobial Peptide Production in Response to .

Invading pathogens are recognized by peptidoglycan recognition proteins (PGRPs) that induce translocation of NF-κB transcription proteins and expression of robust antimicrobial peptides (AMPs). PGRP-LE (PGRP-LE) has been previously identified as a key sensor of infection. Here, we present that is highly expressed in the gut of larvae and 5-day-old adults in the absence of microbial infection. In response to and infections, mRNA levels are significantly upregulated in both the fat body and gut. Silencing of by RNAi rendered significantly more susceptible to challenge by infection and, to a lesser extent, and infections. Reduction of levels in the larval gut resulted in downregulation of eight AMP genes following exposure to , , and . However, the transcriptional levels of AMPs more rapidly reached a higher level in the ds-treated larval gut after challenge with , which may suggest that AMPs induction were more sensitive to than and In addition, RNAi following and challenges had notable effects on , isoform (), and expression level in the fat body and gut. Taken together, acts as an important gut microbial sensor that induces AMPs via Imd activation in response to , whereas involvement of in AMPs synthesize is barely perceptible in the hemocytes and fat body.