title: Cloning of a novel interleukin (IL)-20-like gene in rainbow trout Oncorhynchus mykiss gives an insight into the evolution of the IL-10 family.
abstract: A novel IL-20-like (IL-20L) gene has been analyzed in rainbow trout. It has a six exon/five intron gene organisation and is translated into 181 amino acids (aa) with a signal peptide of 25aa and a mature peptide of 156aa. The trout IL-20L translation shares highest identities to other IL-20L molecules from fish and to IL-20 in mammals. Phylogenetic analysis showed that the fish IL-20L molecules form an independent clade but cluster with the group containing the IL-19, IL-20 and IL-24 molecules from higher vertebrates with a high bootstrap value (89%). The fish IL-20L genes are syntenically in the same location as mammalian IL-19/IL-20/IL-24. Gene organisation and multiple alignment also showed a close relationship of fish IL-20L genes to the mammalian IL-19/IL-20/IL-24 subfamily. These data suggest that the fish IL-20L molecules may have arisen from an ancestral gene that gave rise to IL-19, IL-20 and IL-24 in higher vertebrates. A high level of IL-20L expression in immune related tissues and in the brain, suggests an important role of the fish IL-20L molecule in both the fish immune system and nervous system. Although the exact cell types expressing IL-20L have yet to be defined, macrophages express IL-20L. Moreover, the IL-20L expression in the macrophage cell line RTS-11 was modulated by pro-inflammatory cytokines, signalling pathway activators, microbial mimics and the immuno-suppressor dexamethasone. These data suggest that trout IL-20L is an important player in the cytokine network. The increased expression of IL-20L was only detected at late stages (4-24h) of LPS stimulation in RTS-11 cells and in spleen 24-72h after infection with Yersinia ruckeri, and suggests that the increased expression of IL-20L by LPS and infection may be via the rapid increase of pro-inflammatory cytokines (e.g., IL-1beta) and other factors that is known to occur.
authors.affiliation: Scottish Fish Immunology Research Centre, School of Biological Sciences, University of Aberdeen, Aberdeen, UK.
authors.forename: Tiehui
authors.initials: T
authors.lastname: Wang
authors.forename: Patricia
authors.initials: P
authors.lastname: Díaz-Rosales
authors.forename: Sam A M
authors.initials: SA
authors.lastname: Martin
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Secombes
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D019143:Evolution, Molecular; D029941:Fish Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D005786:Gene Expression Regulation; D006801:Humans; D016753:Interleukin-10 / Q000235:genetics / Q000276:immunology*; D007378:Interleukins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000235:genetics / Q000276:immunology*; D010802:Phylogeny; D015009:Yersinia Infections / Q000276:immunology
chemical_list: D029941:Fish Proteins; D007378:Interleukins; D016753:Interleukin-10; C422042:interleukin 20