Promoter specificity and biological activity of tethered AP-1 dimers

Mol Cell Biol. 2002 Jul;22(13):4952-64. doi: 10.1128/MCB.22.13.4952-4964.2002.

Abstract

Activator protein 1 (AP-1) is a group of dimeric transcription factors composed of Jun, Fos, and ATF family proteins. Both gain- and loss-of-function studies have revealed specific roles for individual AP-1 components in cell proliferation, differentiation, apoptosis, and other biological processes. However, little is known about the functions of specific AP-1 dimers. To test the importance of AP-1 composition in transcriptional activation, AP-1 monomers were joined via a flexible polypeptide tether to force specific pairing. The resultant single-chain AP-1 molecules showed DNA binding specificity and transcriptional activation potentials similar to those of untethered dimers, even in the presence of dominant-negative AP-1 monomers. c-Jun-containing dimers showed distinct promoter specificity in transient-transfection experiments, depending on the Fos, Fra, or ATF partner. When stably expressed in NIH 3T3 cells, c-Jun tethered dimer Fra2, but not c-Jun tethered dimer Fra1 and c-Jun tethered dimer cFos (the tilde indicates a tethered dimer), inhibited G(0) arrest at confluency and under low-serum conditions and specifically activated cyclin A expression. These data suggest that the choice of dimerization partner defines the role of c-Jun in gene activation and cell cycle regulation and that single-chain AP-1 molecules provide a powerful tool for assessing the role of specific AP-1 dimers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Animals
  • Base Sequence
  • Cell Cycle / genetics
  • Cell Division / genetics
  • Cells, Cultured
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Dimerization
  • Fos-Related Antigen-2
  • Humans
  • Mice
  • Molecular Sequence Data
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins c-fos / genetics
  • Proto-Oncogene Proteins c-fos / metabolism*
  • Proto-Oncogene Proteins c-jun / genetics
  • Proto-Oncogene Proteins c-jun / metabolism*
  • Transcription Factor AP-1 / genetics*
  • Transcription Factor AP-1 / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcription, Genetic

Substances

  • DNA-Binding Proteins
  • FOSL2 protein, human
  • Fos-Related Antigen-2
  • Fosl2 protein, mouse
  • Proto-Oncogene Proteins c-fos
  • Proto-Oncogene Proteins c-jun
  • Transcription Factor AP-1
  • Transcription Factors