Regulation of interleukin 1 beta RNA expression in the common carp, Cyprinus carpio L.

The intron-exon organisation of the carp IL-1 beta gene consists of 2455 bp and comprises seven exons. Three IL-1 beta RNA transcripts have been found in carp: (1) a fully spliced product; (2) exon 1-7 with introns 5 and 6; a nd (3) exon 1-7 with intron 5 only. The intron-containing products probably represent partially spliced transcripts. IL-1 beta mRNA expression in carp was semi-quantitatively analysed by RT-PCR in multiple organs, including b rain and pituitary. Constitutive expression of the IL-1 beta mRNA was found in these organs with a predominant expression in the immune organs head ki dney and spleen. Furthermore, a scattered distribution of IL-1 beta produci ng cells was shown by in situ hybridisations of head kidney tissue. Adminis tration of phorbol-myristate-acetate (PMA), lipopolysaccharide (LPS) or ret inoic acid (RA), to phagocytes isolated from the head kidney, resulted in e xpression of IL-1 beta intron-containing transcripts. Of these, only PMA an d LPS were stimulators that induced the fully spliced transcript. A role fo r the nuclear factor (NF)-kappaB pathway in carp IL-1 beta expression was s hown with suppression of the LPS-induced IL-1 beta expression by NF-kappaB inhibitor pyrrolidine dithiocarbamate (PDTC). Cortisol was able to inhibit in vitro constitutive expression of IL-1 beta transcripts. Addition of cort isol simultaneously with LPS could not substantially inhibit transcription. (C) 2001 Elsevier Science Ltd. All rights reserved.