Regulation of human IP-10 gene expression in astrocytoma cells by inflammatory cytokines

J Neurosci Res. 1998 Oct 15;54(2):169-80. doi: 10.1002/(SICI)1097-4547(19981015)54:2<169::AID-JNR5>3.0.CO;2-C.

Abstract

Because of its prominent expression in central nervous system inflammatory pathology by astrocytes, we examined the mechanism of human IP-10 (hIP-10) gene induction by interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) in astrocytoma cells. When present together, IFN-gamma and TNF-alpha induced robust accumulation of hIP-10 mRNA, but hIP-10 mRNA was minimally induced when astrocytoma cells were treated with individual cytokines. This pattern of expression resembled that previously described for murine IP-10 (mIP-10) gene induction in fibroblasts and in rat astroglia. Nuclear run-on experiments showed that the synergistic effect of the cytokines resulted from an increased rate of IP-10 transcriptional initiation. Functional analysis of the hIP-10 promoter after deletion and substitution mutagenesis indicated that an interferon-stimulated response element (ISRE) governed both simple response to IFN-gamma and synergy with TNF-alpha. Synergistic induction of hIP-10 also required an ISRE-proximal nuclear factor kappa-B (NFkappaB) binding site. TNF-alpha-induced NFkappaB binding activity at this site was composed of RelA (p65) homodimers. Our results document that cis-elements through which cytokines mediate synergistic induction of IP-10 in mouse and human are strictly conserved despite divergence elsewhere within the proximal 5'-flanking region.

Publication types

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

MeSH terms

  • Animals
  • Astrocytoma / metabolism*
  • Binding Sites
  • Drug Synergism
  • Gene Expression Regulation, Neoplastic / drug effects*
  • Genome, Human
  • Humans
  • Interferon-gamma / pharmacology*
  • Mice
  • NF-kappa B / metabolism
  • Rats
  • Transcription, Genetic / drug effects
  • Transcriptional Activation
  • Tumor Cells, Cultured
  • Tumor Necrosis Factor-alpha / pharmacology*

Substances

  • NF-kappa B
  • Tumor Necrosis Factor-alpha
  • Interferon-gamma