Cloning and expression analysis of an IL-6 homolog in rainbow trout ( Oncorhynchus mykiss)

• Published in: Molecular immunology Vol. 44; no. 7; pp. 1803 - 1807
• Main Authors: Iliev, Dimitar B., Castellana, Barbara, MacKenzie, Simon, Planas, Josep V., Goetz, Frederick W.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.03.2007
• Subjects: Amino Acid Sequence; Animals; Cloning; Cloning, Molecular; Conserved Sequence; Cytokine evolution; Expression; Gene Expression; Inflammation; Interleukin-6; Interleukin-6 - classification; Interleukin-6 - genetics; Interleukin-6 - metabolism; Lipopolysaccharide; Molecular Sequence Data; Monocytes/macrophages; Oncorhynchus mykiss - genetics; Oncorhynchus mykiss - immunology; Phylogeny; Rainbow trout; RNA, Messenger - analysis; RNA, Messenger - metabolism; Sequence Homology, Amino Acid; Tissue Distribution; CNTF; Cloning; LIF; SSH; CT-1; Inflammation; Monocytes/macrophages; OncM; C/EBP-β; AP-1; IL-6; LPS; Interleukin-6; NF-κB; UTR; Cytokine evolution; CREB; TNF-α; Expression; RACE; Rainbow trout; Lipopolysaccharide
• ISSN: 0161-5890; 1872-9142
• DOI: 10.1016/j.molimm.2006.07.297

A partial cDNA with significant similarity to IL-6 was identified in rainbow trout. Rapid amplification of cDNA ends was used to obtain the full sequence of the trout IL-6 homolog which contains 1180 nucleotides. The transcript encodes a predicted protein of 219 amino acids and eight instability motifs in the 3′UTR. While the complete sequence of the trout IL-6 is poorly conserved, the protein contains a distinct IL-6/G-CSF/MGF family consensus pattern and predicted characteristic α-helical tertiary structure. However, like in fugu, trout IL-6 lacks a pair of cysteine residues, which in mammals are involved in formation of a disulphide bond. The expression of the IL-6 homolog in trout mononuclear phagocytes was highly up-regulated by LPS but not poly(I:C) as demonstrated by Northern analysis. Using RT-PCR the IL-6 expression was detected in trout spleen, gill, gastrointestinal tract, ovary and brain. The highest transcript levels were detected in the ovary suggesting that IL-6 may perform specific functions within this organ.