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Evolution of Lipopolysaccharide (LPS) Recognition and Signaling: Fish TLR4 Does Not Recognize LPS and Negatively Regulates NF-κB Activation
- Source :
- The Journal of Immunology. 182:1836-1845
- Publication Year :
- 2009
- Publisher :
- The American Association of Immunologists, 2009.
-
Abstract
- It has long been established that lower vertebrates, most notably fish and amphibians, are resistant to the toxic effect of LPS. Furthermore, the lack of a TLR4 ortholog in some fish species and the lack of the essential costimulatory molecules for LPS activation via TLR4 (i.e., myeloid differentiation protein 2 (MD-2) and CD14) in all the fish genomes and expressed sequence tag databases available led us to hypothesize that the mechanism of LPS recognition in fish may be different from that of mammals. To shed light on the role of fish TLRs in LPS recognition, a dual-luciferase reporter assay to study NF-κB activation in whole zebrafish embryos was developed and three different bony fish models were studied: 1) the gilthead seabream (Sparus aurata, Perciformes), an immunological-tractable teleost model in which the presence of a TLR4 ortholog is unknown; 2) the spotted green pufferfish (Tetraodon nigroviridis, Tetraodontiformes), which lacks a TLR4 ortholog; and 3) the zebrafish (Danio rerio, Cypriniformes), which possesses two TLR4 orthologs. Our results show that LPS signaled via a TLR4- and MyD88-independent manner in fish, and, surprisingly, that the zebrafish TLR4 orthologs negatively regulated the MyD88-dependent signaling pathway. We think that the identification of TLR4 as a negative regulator of TLR signaling in the zebrafish, together with the absence of this receptor in most fish species, explains the resistance of fish to endotoxic shock and supports the idea that the TLR4 receptor complex for LPS recognition arose after the divergence of fish and tetrapods.
- Subjects :
- Lipopolysaccharides
Receptor complex
animal structures
Green pufferfish
Blotting, Western
Molecular Sequence Data
Immunology
Danio
Gene Expression
Transfection
Tetraodontiformes
Perciformes
Leukocytes
Animals
Humans
Immunology and Allergy
Amino Acid Sequence
Zebrafish
Sequence Homology, Amino Acid
biology
Reverse Transcriptase Polymerase Chain Reaction
Ecology
Fishes
NF-kappa B
biology.organism_classification
Biological Evolution
Cell biology
Toll-Like Receptor 4
Myeloid Differentiation Factor 88
TLR4
lipids (amino acids, peptides, and proteins)
Signal transduction
Signal Transduction
Subjects
Details
- ISSN :
- 15506606 and 00221767
- Volume :
- 182
- Database :
- OpenAIRE
- Journal :
- The Journal of Immunology
- Accession number :
- edsair.doi.dedup.....07fb9d467c04fd8a945428770c553283