Functional consequences of a polymorphism affecting NF-kappaB p50-p50 binding to the TNF promoter region

Mol Cell Biol. 2000 Dec;20(24):9113-9. doi: 10.1128/MCB.20.24.9113-9119.2000.


Stimulation of the NF-kappaB pathway often causes p65-p50 and p50-p50 dimers to be simultaneously present in the cell nucleus. A natural polymorphism at nucleotide -863 in the human TNF promoter (encoding tumor necrosis factor [TNF]) region provides an opportunity to dissect the functional interaction of p65-p50 and p50-p50 at a single NF-kappaB binding site. We found that this site normally binds both p65-p50 and p50-p50, but a single base change specifically inhibits p50-p50 binding. Reporter gene analysis in COS-7 cells expressing both p65-p50 and p50-p50 shows that the ability to bind p50-p50 reduces the enhancer effect of this NF-kappaB site. Using an adenoviral reporter assay, we found that the variant which binds p50-p50 results in a reduction of lipopolysaccharide-inducible gene expression in primary human monocytes. This finding adds to a growing body of experimental evidence that p50-p50 can inhibit the transactivating effects of p65-p50 and illustrates the potential for genetic modulation of inflammatory gene regulation in humans by subtle nucleotide changes that alter the relative binding affinities of different forms of the NF-kappaB complex.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoviridae / genetics
  • Animals
  • Binding Sites
  • COS Cells
  • Cell Fractionation
  • Cell Line
  • Cells, Cultured
  • Cloning, Molecular
  • Dimerization
  • Gene Expression Regulation
  • Genes, Reporter / genetics
  • Humans
  • Lipopolysaccharides / pharmacology
  • Macrophages / cytology
  • Macrophages / metabolism
  • Monocytes / cytology
  • Monocytes / drug effects
  • Monocytes / metabolism
  • NF-kappa B / chemistry
  • NF-kappa B / genetics
  • NF-kappa B / metabolism*
  • NF-kappa B p50 Subunit
  • Polymorphism, Genetic / genetics*
  • Promoter Regions, Genetic / genetics*
  • Transcriptional Activation / physiology
  • Tumor Necrosis Factor-alpha / genetics*


  • Lipopolysaccharides
  • NF-kappa B
  • NF-kappa B p50 Subunit
  • Tumor Necrosis Factor-alpha