A direct role for c-fos in AP-1-dependent gene transcription.

R. Herrera, S. Agarwal, K. Walton, B. Satterberg, R. J. Distel, R. Goodman, B. M. Spiegelman, T. M. Roberts

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Transcription factor activator protein 1 (AP-1) is a protein fraction that contains c-fos, c-jun, and several other related proteins. Although this protein fraction can stimulate transcription in vitro, the relative contributions of c-fos and c-jun to the transcriptional effect of AP-1 are not clear. In order to approach this question, we have overexpressed both proteins using a baculovirus-mediated expression system and defined their DNA-binding and transcriptional enhancement activities in vitro. Gel mobility-shift and DNase 1 footprinting assays showed that c-jun protein specifically binds to DNA through an AP-1 binding site. Under the same conditions, no detectable binding of c-fos protein was observed. However, when the DNA binding assays were performed in the presence of both c-jun and c-fos, a marked increase in the affinity of c-jun for the AP-1 site was observed. An AP-1-dependent transcription assay was used to test the capability of both proteins to stimulate correctly initiated RNA synthesis in vitro. Under our conditions, c-jun protein was capable of stimulating specific RNA transcription in an AP-1 site-dependent manner. In contrast, c-fos protein showed no detectable transcriptional activation by itself. However, a transcription assay carried out in the presence of both c-fos and c-jun proteins showed that the c-fos/c-jun complex was more active as a transcriptional regulator than c-jun protein alone. These experimental results indicate that c-fos and c-jun proteins are required to reconstitute full AP-1-dependent transcriptional activation and directly demonstrate that c-fos is a regulator of gene expression.

Original languageEnglish (US)
Pages (from-to)483-490
Number of pages8
JournalCell growth & differentiation : the molecular biology journal of the American Association for Cancer Research
Issue number10
StatePublished - Oct 1990
Externally publishedYes

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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