Molecular immunology
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Molecular immunology · Jan 2004
Toll-like receptor gene family and TIR-domain adapters in Danio rerio.
The toll-like family of receptors (TLR) is an ancient pattern recognition receptor family, conserved from insects to mammals. We have identified in zebrafish (Danio rerio) 19 putative TLR variants, the orthologs of mammalian TLR2-5, 7-9, a fish specific receptor type group and three putative splice variants. One receptor is very close to mammalian TLR1, 6 and 10 and seems to be their common ancestor. ⋯ By RT-PCR we showed that all TLR are widely expressed in adult tissues, but also at different stages of development. All these TLRs contain very conserved toll/interleukin-1 receptor (TIR) domains able to interact with TIR-domain of adapter molecules. We demonstrate here that TIR-domain containing adapters MyD88 and SARM are present in zebrafish, showing that TLR adapter molecules are highly conserved in evolution.
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Molecular immunology · Jan 2004
Expression analysis of the Toll-like receptor and TIR domain adaptor families of zebrafish.
The zebrafish genomic sequence database was analysed for the presence of genes encoding members of the Toll-like receptors (TLR) and interleukin receptors (IL-R) and associated adaptor proteins containing a TIR domain. The resulting predictions show the presence of one or more counterparts for the human TLR1, TLR2, TLR3, TLR4, TLR5, TLR7, TLR8, TLR9, IL-1R and IL-18R genes and one copy of the adaptor genes MyD88, MAL, TRIF and SARM. In contrast to data for the pufferfish Fugu rubripes, zebrafish has two genes that are highly similar to human TLR4. ⋯ Expression analysis using reverse transcriptase-PCR (RT-PCR) shows that 17 of the predicted zebrafish TLR genes and all the genes encoding adaptor proteins are expressed in the adult stage. A subset of the TLR genes are expressed at higher levels in fish infected with the pathogen Mycobacterium marinum. The induced genes include the homologues of the human TLR1 and TLR2 genes, whose functions are associated with mycobacterial infections, underscoring the suitability of zebrafish as a model for analysis of the vertebrate innate immune system.