INDUCTION OF AP-1 DNA-BINDING ACTIVITY AND C-FOS MESSENGER-RNA BY THE ADENOVIRUS 243R-E1A-PROTEIN AND CYCLIC-AMP REQUIRES DOMAINS NECESSARY FOR TRANSFORMATION

The 243R EIA protein can act in synergy with cyclic AMP to induce A.P-1 DNA-binding activity and c-fos mRNA in mouse S49 cells. A series of deletion mutants was used to identify two domains of the 243R protein that were required for these effects. Interestingly, these domains correlated precisely with regions known to be necessary for EIA-mediated transformation. One domain was located at the N terminus of EIA. The other domain spanned residues 36 to 81, corresponding to conserved region 1 of EIA. S49 cellular proteins that associate with EIA were coimmunoprecipitated with anti-EIA antibody. These included the previously identified proteins p300, p130, p107, p105Rb, and cyclin A. In addition, proteins of 90 kDa and a series of proteins in the 120- to 170-kDa range were identified. Binding of p300, p90, and the 120- to 170-kDa proteins was abolished in cells expressing mutants of E1A that were unable to induce AP-1 DNA-binding activity and c-fos mRNA. These data strongly suggest that specific cellular E1A-binding proteins are involved in the induction of AP-1 DNA-binding activity and c-fos mRNA by the synergistic action of the 243R ElA protein and cyclic AMP and that these transcriptional events are related to the transformation process.