Peptidoglycan recognition proteins: on and off switches for innate immunity
- 5 March 2004
- journal article
- review article
- Published by Wiley in Immunological Reviews
- Vol. 198 (1), 83-96
- https://doi.org/10.1111/j.0105-2896.2004.0120.x
Abstract
Summary: Insects rely on innate immune mechanisms to defend themselves against microbes. The inducible anti‐microbial peptides constitute an important arm of this defense. In Drosophila, the Toll and the Imd pathways are the major routes to induce the peptides, and it has become clear that to a certain extent, these pathways can discriminate between different microbes and mount an appropriate response to eliminate the intruder. This review discusses the proteins responsible for this discriminatory recognition, the peptidoglycan recognition proteins (PGRPs). The serum protein PGRP‐SA triggers a humoral cascade of proteases upon infection by certain gram‐positive bacteria to activate the Toll pathway. The membrane‐bound receptor PGRP‐LC activates the Imd pathway in response to certain gram‐ negative bacteria or their peptidoglycans. Other PGRPs have enzymatic activity, cleaving lactylamide bonds in peptidoglycan to eliminate its immunogenicity, thus turning off the immune response. The PGRP family is conserved from insects to man. Short mammalian PGRP variants are synthesized in neutrophils and stored in granules. These PGRPs seem to influence the survival of phagocytosed non‐pathogenic bacteria. Long PGRP variants are expressed in the liver and secreted into the bloodstream where their peptidoglycan‐degrading activity might serve scavenger functions.Keywords
This publication has 82 references indexed in Scilit:
- Binding of the Drosophila cytokine Spätzle to Toll is direct and establishes signalingNature Immunology, 2003
- The Differentially Spliced Mouse tagL Gene, Homolog of tag7/PGRP Gene Family in Mammals and Drosophila, can Recognize Gram-positive and Gram-negative Bacterial Cell Wall Independently of T Phage Lysozyme Homology DomainJournal of Molecular Biology, 2003
- Isolation, Characterization, and Antimicrobial Properties of Bovine Oligosaccharide-binding ProteinPublished by Elsevier BV ,2002
- The Genome Sequence of Drosophila melanogasterScience, 2000
- Relish, a Central Factor in the Control of Humoral but Not Cellular Immunity in DrosophilaMolecular Cell, 1999
- Endotoxin-tolerant Mice Have Mutations in Toll-like Receptor 4 (Tlr4)The Journal of Experimental Medicine, 1999
- Signals from the IL-1 Receptor Homolog, Toll, Can Activate an Immune Response in a Drosophila Hemocyte Cell LineBiochemical and Biophysical Research Communications, 1995
- Insect immunityEuropean Journal of Biochemistry, 1988
- Partial purification and characterization of amidase from human and mouse serumBiochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology, 1982
- Secondary structure of the cecropins: antibacterial peptides from the moth Hyalophora cecropiaFEBS Letters, 1982