NOD1 is the innate immune receptor for iE-DAP and can activate NF-κB pathway in teleost fish.

The innate immune system is the first line for organisms defense against microbial infection, and NOD-like receptors (NLRs) protein family is an important member of innate immunity effector molecules. It has been proved that NLRs are located in the endochylema and can senses of microbial products. NOD1 is one of the representatives of this family, it has been proved that in mammals, NOD1 can distinguish a specific muropeptide (G-d-glutamyl-meso-diaminopimelic acid, iE-DAP) which was derived from bacterial peptidoglycans. However, the NOD-mediated intracellular recognition of microorganisms remains largely uncharacterized in teleost fishes. In this study, we use miiuy croaker (Miichthys miiuy) as a model to determine NOD1 can response to the infection of Gram-negative bacteria and it is the receptor that can recognize of iE-DAP by LRRs domain, it can activate the NF-κB signaling pathway through recruit RIP2 to induce inflammatory response in teleost fishes. Results showed that NOD1 can recognize the components of Gram-negative bacteria and activate inflammatory response to resistance of bacterial infection. Our study can improve the knowledge on immune system of fishes and provide a theoretical basis for the study of prevention and treatment of fish diseases.