title: Pathogen recognition receptors in channel catfish: III phylogeny and expression analysis of Toll-like receptors.
abstract: Toll-like receptors (TLRs) were the earliest characterized and the most extensively studied pathogen recognition receptors (PRRs). The majority of tetrapod TLR orthologs have been found in teleost fish. In addition, a group of "fish-specific" TLRs have been identified. In catfish, a number of TLR-related sequences have been reported, but systematic phylogenetic analyses have not been conducted. In this study, we conducted phylogenetic and comparative analysis of 20 catfish TLR genes against their counterparts from various species. TLR25 and TLR26 are TLRs identified only in channel catfish. Phylogenetic analyses suggested that four catfish TLR genes have duplicated copies in the genome, i.e., TLR4, TLR5, TLR8, and TLR20. Six fish-specific TLRs were identified, and the vast majority of these belong to the TLR11 subfamily. In healthy catfish tissues, most of the tested TLR genes were ubiquitously expressed although expression levels varied among the 11 tested tissues. We tested nine TLRs for their expression in response to Edwardsiella ictaluri infection. They were significantly up-regulated in the spleen and liver, but down-regulated in the head kidney, suggesting their involvement in the immune responses against the intracellular bacterial pathogen in a tissue-specific manner in catfish, perhaps through rapid migration of phagocytes to infection sites.
authors: The Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Aquatic Genomics Unit, Auburn University, Auburn, AL 36849, USA.
authors: Jiaren
authors: J
authors: Zhang
authors: Shikai
authors: S
authors: Liu
authors: K V
authors: KV
authors: Rajendran
authors: Luyang
authors: L
authors: Sun
authors: Yu
authors: Y
authors: Zhang
authors: Fanyue
authors: F
authors: Sun
authors: Huseyin
authors: H
authors: Kucuktas
authors: Hong
authors: H
authors: Liu
authors: Zhanjiang
authors: Z
authors: Liu
mesh_terms: D000818:Animals; D020610:Edwardsiella ictaluri / Q000276:immunology; D004756:Enterobacteriaceae Infections / Q000276:immunology / Q000378:metabolism / Q000662:veterinary*; D005393:Fish Diseases / Q000276:immunology* / Q000378:metabolism / Q000382:microbiology; D029941:Fish Proteins / Q000235:genetics* / Q000378:metabolism; D018628:Gene Dosage; D015870:Gene Expression / Q000276:immunology; D005786:Gene Expression Regulation / Q000276:immunology; D060226:Head Kidney / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D054884:Host-Pathogen Interactions; D007059:Ictaluridae / Q000235:genetics* / Q000378:metabolism; D008099:Liver / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D009928:Organ Specificity; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D013154:Spleen / Q000276:immunology / Q000378:metabolism / Q000382:microbiology; D051193:Toll-Like Receptors / Q000235:genetics* / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D051193:Toll-Like Receptors