PMID:9185517

Citation	Gabay, C, Smith, MF, Eidlen, D and Arend, WP (1997) Interleukin 1 receptor antagonist (IL-1Ra) is an acute-phase protein. J. Clin. Invest. 99:2930-40
Abstract	Interleukin 1 receptor antagonist (IL-1Ra) levels are elevated in the blood of patients with a variety of infectious, immune, or traumatic conditions. To examine whether IL1Ra is produced by liver cells with characteristics resembling an acute-phase protein, human primary hepatocytes isolated from liver biopsies and HepG2 hepatoma cells were stimulated with IL-1beta, IL-6, and TNFalpha. IL-1Ra was present in the supernatants of both cells, with production significantly enhanced by IL-1beta, and by the combination of IL-1beta and IL-6. The term IL-1Ra refers to two different proteins encoded by the same gene, but generated by alternative splicing of two different first exons. One isoform is secreted (17-kD sIL-1Ra), and the other isoform remains in the cytoplasm (18-kD icIL-1Ra). By Western blot analysis, the supernatants of human hepatoma (HepG2) cells contained only sIL-1Ra, whereas the lysates contained a novel smaller molecular mass isoform of 16 kD. RT-PCR and ribonuclease protection assay with RNA from HepG2 cells showed that only sIL-1Ra mRNA was expressed, and confirmed the inducing effect of IL-1beta and IL-6. Transfection studies were performed using constructs containing the promoters of either sIL-1Ra or icIL-1Ra coupled to the luciferase reporter gene. The sIL-1Ra promoter was active in HepG2 cells stimulated by IL-1beta and/or IL-6, whereas the icIL-1Ra promoter was inactive. Mutation of binding sites for transcription factors NF-kappaB and/or C/EBP within the proximal sIL-1Ra promoter led to significant decreases in response to IL-1beta and IL-6 in comparison to the wild-type promoter. Electromobility gel shift assays confirmed the presence of NF-kappaB and C/EBP binding sites within the sIL-1Ra promoter, and indicated a significant increase in the binding activities of nuclear proteins from HepG2 cells treated with IL-1beta and IL-6. In summary, sIL-1Ra, but not icIL-1Ra, is produced by hepatocytes, and is regulated by proinflammatory cytokines as an acute-phase protein. In addition, NF-kappaB and C/EBP family members are likely to play important roles in the full expression of IL-1Ra by hepatocytes during inflammatory conditions.
Links	PubMed PMC508145 Online version:10.1172/JCI119488
Keywords	Acute-Phase Proteins; Binding Sites; Carcinoma, Hepatocellular; Cells, Cultured; DNA/chemistry; DNA/metabolism; DNA-Binding Proteins/metabolism; Electrophoresis; Humans; Interleukin 1 Receptor Antagonist Protein; Interleukin-1/pharmacology; Interleukin-6/pharmacology; Liver/metabolism; Liver Neoplasms; NF-kappa B/metabolism; Polymerase Chain Reaction; RNA, Messenger/analysis; Sialoglycoproteins/biosynthesis; Sialoglycoproteins/genetics; Transfection; Tumor Cells, Cultured; Tumor Necrosis Factor-alpha/pharmacology
edit table

Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HUMAN:IL1RA	involved_in	GO:0006953: acute-phase response	ECO:0000314: direct assay evidence used in manual assertion		P		Seeded From UniProt	complete
HUMAN:IL1RA	part_of	GO:0005615: extracellular space	ECO:0000314: direct assay evidence used in manual assertion		C		Seeded From UniProt	complete

References

See Help:References for how to manage references in GONUTS.