title: Overexpression of a pattern-recognition receptor, peptidoglycan-recognition protein-LE, activates imd/relish-mediated antibacterial defense and the prophenoloxidase cascade in Drosophila larvae.
abstract: 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.
mesh_terms: D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D004156:Catechol Oxidase / Q000378:metabolism*; D004247:DNA / Q000235:genetics; D004330:Drosophila / Q000235:genetics / Q000254:growth & development / Q000276:immunology* / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D004792:Enzyme Precursors / Q000378:metabolism*; D015870:Gene Expression; D017344:Genes, Insect; D007814:Larva / Q000276:immunology / Q000378:metabolism; D010457:Peptidoglycan / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000276:immunology*
chemical_list: D002352:Carrier Proteins; D029721:Drosophila Proteins; D004792:Enzyme Precursors; D010457:Peptidoglycan; C101626:Rel protein, Drosophila; D014157:Transcription Factors; C439909:imd protein, Drosophila; C118897:peptidoglycan recognition protein; D004247:DNA; C038451:pro-phenoloxidase; D004156:Catechol Oxidase