title: The first cytokine sequence within cartilaginous fish: IL-1 beta in the small spotted catshark (Scyliorhinus canicula).
abstract: Cartilaginous fish are considered the most primitive living jawed vertebrates with a complex immune system typical of all jawed vertebrates. Cytokine homologs are found within jawless and bony fish, although no cytokine or cytokine receptor genes have been sequenced in cartilaginous fish. In this study the complete coding sequence of the small spotted catshark (Scyliorhinus canicula) IL-1beta gene is presented that contains a short 5' untranslated region (54 bp), a 903-bp open reading frame, a 379-bp 3' untranslated region, a polyadenylation signal, and eight mRNA instability motifs. The predicted translation (301 amino acids) has highest identity to trout IL-1beta (31.7%), with greatest homology within the putative 12 beta-sheets. The IL-1 family signature is also present, but there is no apparent signal peptide. As with other nonmammalian IL-1beta sequences, the IL-1-converting enzyme cut site is absent. Expression of the IL-1beta transcript is detectable by RT-PCR in the spleen and testes, induced in vivo with LPS. Furthermore, a 7-fold increase of transcript levels in splenocytes incubated for 5 h with LPS was seen. The genomic organization comprises six exons and five introns with highest homology seen in exons encoding the largest amount of secondary structure per amino acid. Southern blot analysis suggests at least two copies of the IL-1beta gene or genes related to the 3' end of the IL-1beta sequence are present in the catshark. The cloning of IL-1beta in S. canicula, the first cytokine sequenced within cartilaginous fish, verifies previous bioactivity evidence for the presence of inflammatory cytokines.
authors.affiliation: Department of Zoology, University of Aberdeen, Aberdeen, United Kingdom.
authors.forename: Steve
authors.initials: S
authors.lastname: Bird
authors.forename: Tiehui
authors.initials: T
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Zou
authors.forename: Charlie
authors.initials: C
authors.lastname: Cunningham
authors.forename: Chris J
authors.initials: CJ
authors.lastname: Secombes
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D005091:Exons; D015870:Gene Expression / Q000276:immunology; D006801:Humans; D007375:Interleukin-1 / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification*; D007438:Introns; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009928:Organ Specificity / Q000235:genetics / Q000276:immunology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D012754:Sharks / Q000235:genetics* / Q000276:immunology*
chemical_list: D007375:Interleukin-1