Overexpression of a pattern-recognition receptor, peptidoglycan-recognition protein-LE, activates imd/relish-mediated antibacterial defense and the prophenoloxidase cascade in Drosophila larvae

• DOI: 10.1073/pnas.212301199
• Publication Date: 2002-10-15T16:43:03Z
• Authors: Aya Takehana; Tomonori Katsuyama; Tamaki Yano; Yoshiteru Oshima; Haruhiko Takada; Toshiro Aigaki; Shoichiro Kurata
• Keywords: 0301 basic medicine; Enzyme Precursors; Base Sequence; Gene Expression; Genes, Insect; DNA; Peptidoglycan; 3. Good health; 03 medical and health sciences; Larva; Animals; Drosophila Proteins; Drosophila; Carrier Proteins; Catechol Oxidase; Signal Transduction; Transcription Factors

In Drosophila , microbial infection activates an antimicrobial defense system involving the activation of proteolytic cascades in the hemolymph and intracellular signaling pathways, the immune deficiency (imd) and Toll pathways, in immune-responsive tissues. The mechanisms for microbial recognition are largely unknown. We report that, in larvae, the imd-mediated antibacterial defense is activated by peptidoglycan-recognition protein (PGRP)-LE, a PGRP-family member in Drosophila . Consistent with this, PGRP-LE binds to the diaminopimelic acid-type peptidoglycan, a cell-wall component of the bacteria capable of activating the imd pathway, but not to the lysine-type peptidoglycan. Moreover, PGRP-LE activates the prophenoloxidase cascade, a proteolytic cascade in the hemolymph. Therefore, PGRP-LE acts as a pattern-recognition receptor to the diaminopimelic acid-type peptidoglycan and activates both the proteolytic cascade and intracellular signaling in Drosophila immunity.