关键词: 昆虫, 天生免疫, 肽聚糖, 病原相关分子模式, 肽聚糖识别蛋白

Abstract:  Peptidoglycan recognition proteins (PGRPs), a family of pattern recognition proteins, play key roles in the innate immune system against invading pathogens and parasites in vertebrates and invertebrates. Peptidoglycans (PGNs), which are conserved in most bacteria as an essential component of cell wall, are recognized by PGRPs as pathogen-associated molecular pattern (PAMP). In insects, some PGRPs function as receptors to recognize bacteria and fungi, leading to the activation of antimicrobial peptide (AMP) synthesis through IMD and Toll pathways. And this recognition also results in the activation of prophenoloxidase (PPO) cascade. Some PGRPs with amidase activity are involved in phagocytosis, and some may down-regulate AMP pathways by degradation of bacterial peptidoglycan. And some PGRPs function as effectors to kill bacteria by themselves. This review summarizes the functions of PGRPs as recognition receptor, regulator and effector in insect innate immune system and gives the directions for future study.

Key words:  Insects, innate immunity, peptidoglycan, pathogen-associated molecular pattern (PAMP), peptidoglycan recognition protein (PGRP)