Structure of the rat interleukin 6 gene and its expression in macrophage-derived cells

W. Northemann, T. A. Braciak, Masahira Hattori, F. Lee, G. H. Fey

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Abstract

Rat peritoneal exudate cells produce two interleukin 6 (IL6) messenger RNA species, a major 1200 nucleotide and a 5-fold less abundant, 2400-nucleotide species. A cDNA clone representing the major species was isolated, and sequenced. The 1055-base pair insert covered the 3'-nontranslated region, the 211 triplet coding region and most of the 5'-nontranslated region. The derived rat IL6 amino acid sequence was 93 and 58% identical, respectively, with mature murine and human IL6. Rat IL6 lacks N-glycosylation sites but contains a fifth cysteinyl residue in addition to the 4 residues shared in conserved positions with murine and human IL6. Stable murine L cell and human HeLa-derived cell lines were established by cotransfection with rat IL6 cDNA and a selectable neomycin resistance marker. These lines secrete 9-fold increased amounts of functional IL6 over their respective parental cells. A stable rat macrophage-derived cell line, RM-SV1, was established by transformation with simian virus 40. IL6 and IL1 mRNA levels are inducible 20- and 3.5-fold, respectively, in this line by treatment with lipopolysaccharide with kinetics characteristic of macrophages. A set of three overlapping genomic DNA clones was isolated and a 10-kilobase DNA segment was sequenced containing the rat IL6 gene plus 2.9 kilobases of 5'-flanking and 1.3 kilobases of 3'-flanking sequences. The two transcription start sites used in RM-SV1 cells were mapped within 5 base pairs of each other. The exon/intron boundaries are conserved with the murine and human IL6 genes. The two IL6 mRNA species are generated by alternative polyadenylation at sites separated by a distance of 1.2 kilobases. The intervening region contains a repetitive element 72-80% identical with the rat and murine consensus L1 family sequences.

Original languageEnglish
Pages (from-to)16072-16082
Number of pages11
JournalJournal of Biological Chemistry
Volume264
Issue number27
Publication statusPublished - 1989
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry

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    Northemann, W., Braciak, T. A., Hattori, M., Lee, F., & Fey, G. H. (1989). Structure of the rat interleukin 6 gene and its expression in macrophage-derived cells. Journal of Biological Chemistry, 264(27), 16072-16082.