A 58-base-pair region of the human C3 gene confers synergistic inducibility by interleukin-1 and interleukin-6

Mol Cell Biol. 1990 Dec;10(12):6181-91. doi: 10.1128/mcb.10.12.6181-6191.1990.


We have cloned the promoter for the human third component of complement (C3) gene and have identified sequences involved in its regulation during the acute-phase response. A construct linking 199 bp of the C3 promoter to the firefly luciferase gene was found to be very responsive to interleukin-1 (IL-1) and modestly responsive to interleukin-6 (IL-6) by transfection analysis in the human hepatoma line Hep3B2. Simultaneous treatment with the two cytokines showed a strong synergy between the actions of the two molecules. A 58-bp fragment (-127 to -70 bp) was shown by 5' and 3' deletional mutagenesis to contain cis-acting elements that mediated both the IL-1 response and the IL-1-plus-IL-6 synergistic response of this promoter. When coupled to a heterologous promoter, this fragment enabled the synergistic induction by IL-1 plus IL-6. Sequences homologous to the palindrome ACATTGCACAATCT, which mediates the induction of the IL-6 gene by IL-1 (S. Akira, H. Isshiki, T. Sugita, O. Tanabe, S. Kinoshita, Y. Nishio, T. Nakajima, T. Hirano, and T. Kishimoto, EMBO J. 9:1897-1906, 1990), and the core sequence of the IL-6-responsive element of the rat alpha 2-macroglobulin gene (CTGGGA; M. Hattori, L. J. Abraham, W. Northemann, and G. H. Fey, Proc. Natl. Acad. Sci. USA 87:2364-2368, 1990) are contained within this fragment in immediate juxtaposition and partially overlapping. Site-directed mutagenesis within this homology region drastically reduced the inducibility of the C3 promoter by either cytokine. DNase I footprinting analysis defined a binding site for the transcription factor CCAAT/enhancer-binding protein (C/EBP), which included the IL-1-responsive element-like sequence. No differences were seen between the footprints generated by using extracts from unstimulated and IL-1-stimulated Hep3B2 cells. However, gel retardation analyses revealed two IL-1-specific bands. The data suggest that the induction by IL-1 is mediated by a factor belonging to the family of C/EBP-related proteins.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Composition
  • Base Sequence
  • Cloning, Molecular
  • Coleoptera / enzymology
  • Coleoptera / genetics
  • Complement C3 / biosynthesis
  • Complement C3 / genetics*
  • Deoxyribonuclease I
  • Drug Synergism
  • Humans
  • Interleukin-1 / pharmacology*
  • Interleukin-6 / pharmacology*
  • Luciferases / genetics
  • Mice
  • Molecular Sequence Data
  • Molecular Weight
  • Mutagenesis, Site-Directed
  • Oligonucleotide Probes
  • Promoter Regions, Genetic / drug effects*
  • Recombinant Proteins / pharmacology
  • Restriction Mapping
  • Sequence Homology, Nucleic Acid
  • Transcription, Genetic / drug effects*


  • Complement C3
  • Interleukin-1
  • Interleukin-6
  • Oligonucleotide Probes
  • Recombinant Proteins
  • Luciferases
  • Deoxyribonuclease I