Cloning of a Salmo salar interleukin-1 receptor-like cDNA

The interleukin-I receptor/toll-like receptor (IL-lR/TLR) superfatrtily, defined by a cytosolic Toll/IL-IR (TIR) signalling domain, participates in host responses to injury and infection. We describe in this study the cloning of a cDNA encoding a Salmo salar interleukin-1 receptor-like protein (SalIL-IRLP), SaHL-IRLP comprises a potential signal peptide, three extracellular immunoglobulin domains, a short transmembrane region and an intracellular region that contains the TIR domain. The predicted amino acid sequence of SallL-l RLP displays 43-44% similarities and 31 % identities to chicken and human IL- I RI sequences. Within the intracellular region, SalIL-IRLP displays highest similarity (59%) and identity (46%) to the chicken IL-IRI sequence. Two different 5' distal UTRs were identi tied among six salmon IL-IRLP clones. The six clones, however, displayed identical 5' proximal UTRs, coding regions and 3' UTRs. SallL-lRLP expression is induced in liver, head kidney, spleen and gills upon injection of salmon with bacterial lipopolysaccharide. Sequence comparisons, protein domain structures, expression patterns and phylogenetic analyses indicate that SalIL-IRLP is most closely related to type I interleukin-I receptors and interieukin- I receptor related proteins. (C) 2002 Elsevier Science Ltd. All rights reserved.