title: Differential expression and haplotypic variation of two interleukin-1beta genes in the common carp (Cyprinus carpio L.).
abstract: Interleukin-1beta (IL-1beta) is a central component in innate immunity and the inflammatory response of mammals. Only recently, the first non-mammalian IL-1beta sequences were published. In this study, we describe a second IL-1beta sequence (IL-1beta2) in carp with 74% amino acid identity to the carp IL-1beta1 sequence. The existence of two IL-1beta copies in the carp genome probably originates from the tetraploid nature of the species. In contrast to the first carp IL-1beta sequence, IL-1beta2 is represented by multiple genes with 95-99% identity. Detection of several IL-1beta2 sequences within individual homozygous fish suggests the presence of multiple copies of the IL-1beta2 gene in the carp genome, possibly as a result of subsequent gene duplication of IL-1beta2. In vivo, constitutive mRNA expression of both IL-1beta genes was found in healthy carp. IL-1beta2 mRNA expression could be up-regulated in head kidney cells similar to carp IL-1beta1, in vivo by infection with Trypanoplasma borreli and in vitro by stimulation with lipopolysaccharide (LPS). Cortisol, the major glucocorticoid in fish, is an endocrine-derived fator mediating IL-1beta expression. Although constitutive IL-1beta expression was inhibited by a physiological dose of cortisol, cortisol synergistically enhanced LPS-induced IL-1beta expression in carp. Involvement of the transcription factor nuclear factor (NF)-kappaB in expression of IL-1beta1 and IL-1beta2 was demonstrated. Ratio of IL-1beta expression was determined and this showed IL-1beta1 mRNA expression to be at least tenfold higher compared with IL-1beta2. The possibilities of IL-1beta2 being a functional gene or approaching pseudogene status are discussed.
authors.affiliation: Cell Biology and Immunology Group, Wageningen Institute of Animal Sciences, Wageningen University, P.O. Box 338, 6700 NH Wageningen, The Netherlands.
authors.forename: Marc Y
authors.initials: MY
authors.lastname: Engelsma
authors.forename: René J M
authors.initials: RJ
authors.lastname: Stet
authors.forename: Jeroen P
authors.initials: JP
authors.lastname: Saeij
authors.forename: B M Lidy
authors.initials: BM
authors.lastname: Verburg-van Kemenade
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002347:Carps / Q000235:genetics* / Q000276:immunology*; D003001:Cloning, Molecular; D040461:Gene Components; D015870:Gene Expression; D014644:Genetic Variation; D006239:Haplotypes; D007375:Interleukin-1 / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D007375:Interleukin-1; D020033:Protein Isoforms; D012333:RNA, Messenger