Downregulation of the Drosophila immune response by peptidoglycan-recognition proteins SC1 and SC2.
Peptidoglycan-recognition proteins (PGRPs) are evolutionarily conserved molecules that are structurally related to bacterial amidases. Several Drosophila PGRPs have lost this enzymatic activity and serve as microbe sensors through peptidoglycan recognition. Other PGRP family members, such as Drosophila PGRP-SC1 or mammalian PGRP-L, have conserved the amidase function and are able to cleave peptidoglycan in vitro. However, the contribution of these amidase PGRPs to host defense in vivo has remained elusive so far. Using an RNA-interference approach, we addressed the function of two PGRPs with amidase activity in the Drosophila immune response. We observed that PGRP-SC1/2-depleted flies present a specific over-activation of the IMD (immune deficiency) signaling pathway after bacterial challenge. Our data suggest that these proteins act in the larval gut to prevent activation of this pathway following bacterial ingestion. We further show that a strict control of IMD-pathway activation is essential to prevent bacteria-induced developmental defects and larval death.
Bischoff
Vincent
V
Institut de Biologie Moléculaire et Cellulaire, UPR 9022 du CNRS, Strasbourg, France.
Vignal
Cécile
C
Duvic
Bernard
B
Boneca
Ivo G
IG
Hoffmann
Jules A
JA
Royet
Julien
J
D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000502:physiology; D001419:Bacteria / Q000472:pathogenicity; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D015536:Down-Regulation; D004330:Drosophila / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000382:microbiology*; D007814:Larva / Q000276:immunology / Q000382:microbiology; D034622:RNA Interference; D015398:Signal Transduction
D023181:Antimicrobial Cationic Peptides; D002352:Carrier Proteins; C118897:peptidoglycan recognition protein