Genomics of fish IL-17 ligand and receptors: A review

Cloning and Characterization of Rainbow Trout Interleukin-17A/F2 (IL-17A/F2) and IL-17 Receptor A: Expression during Infection and Bioactivity of Recombinant IL-17A/F2

“…According to analysis of the phylogenetic relationship between the various IL-17R protein family members, trout IL-17RA clustered with the other piscine and homeotherm IL-17RA molecules. Multiple alignment of this protein sequence with those of other vertebrate IL-17RA molecules revealed a high degree of conservation within the extracellular and intracellular SEFIR domains, which are characteristic of the IL-17RA family (18,24,25). Several conserved cysteines, eight of which are potentially involved in disulfide bridge formation, as seen in mammalian molecules (64), were also present in trout IL-17RA.…”

“…These mo- tifs are typical of proinflammatory molecules, which show transitory expression to reduce host damage (63), illustrating a potential role of the trout IL-17A/F in inflammatory responses. A multiple amino acid alignment revealed conservation of 4 cysteine residues for almost all the species considered, except for fugu IL-17A/F2 (17), which are signature residues in the IL-17 family (12,(16)(17)(18). The presence of 4 cysteine residues in trout and other IL-17A/F teleost molecules (16,17) suggests that they might be involved in the formation of 2 disulfide bonds, which form the cysteine knot characteristic of the IL-17 family (12,13).…”

“…Initially, in lower vertebrates, three molecules were identified in zebrafish (Danio rerio) that had homology to IL-17A and IL-17F and were thus designated IL-17A/F-1 to -3 (16). This was followed by a similar report in fugu (Takifugu rubripes) (17) and, most recently, in medaka (Oryzias latipes) (18). Teleost IL-17s have also been reviewed recently (19).…”

“…Even though several IL-17A/F molecules have been identified in different fish species (16)(17)(18), no functional data have been ascribed to IL-17A/F activity in lower vertebrates to date. Here, for the first time in a nonmammalian model, we have produced and tested the bioactivity of trout rIL-17A/F2.…”

The cytokine networks of adaptive immunity in fish

“…A further IL-17A or F homologue gene (IL-17A/F3) has been found in zebrafish and fugu on another chromosome [111,112]. IL-17A/F homologue genes have also been found in rainbow trout [113], medaka Oryzias latipes [114] and turbot Scophthalmus maximus [115]. Synteny analysis suggests some conserved features between the fish IL-17A/F1-IL-17A/F2 locus, the IL-17A/F3 locus and the mammalian IL-17A-IL-17F locus.…”