The c-Fos protein interacts with c-Jun/AP-1 to stimulate transcription of AP-1 responsive genes

Cell. 1988 Aug 12;54(4):541-52. doi: 10.1016/0092-8674(88)90076-1.


Cell lines stably transfected with metal inducible, MT-fos chimeric genes were used to study the ability of the c-fos gene product, Fos, to act as a transcriptional trans-activator. In 3T3MTfos cells, induction of Fos expression led to specific trans-activation of an AP-1 responsive reporter gene. Induction of Fos expression in F9MTfos cells, however, did not lead to trans-activation. Since, unlike NIH3T3 cells, F9 cells do not contain detectable levels of AP-1, we examined whether a c-Jun/AP-1 expression vector can restore the trans-activating effect of Fos in F9MTfos cells. Transfection with a functional c-Jun/AP-1 vector restored the specific trans-activating effect of Fos on AP-1 responsive constructs. When incubated with nondenatured cell extracts, anti-cFos antisera precipitated a protein complex composed of Fos and several Fos associated proteins (FAP). One of these, FAP p39, is structurally identical to c-Jun/AP-1. These results suggest that Fos is a trans-acting factor that is capable of stimulating gene expression not by direct binding to DNA but by interaction with the sequence-specific transcription factor AP-1. Therefore recognition of specific cis-elements by AP-1 is a prerequisite for Fos-mediated stimulation of gene expression.

Publication types

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

MeSH terms

  • Cell Line
  • Enhancer Elements, Genetic
  • Humans
  • Models, Genetic
  • Proto-Oncogene Proteins / physiology*
  • Proto-Oncogene Proteins c-fos
  • Proto-Oncogenes*
  • Transcription Factors*
  • Transcription, Genetic*
  • Transfection


  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-fos
  • Transcription Factors