Role of activator protein-1 in TCR-mediated regulation of the murine fasl promoter

The present study demonstrates that transcription factor interactions are i mportant in regulating the murine fasl promoter following TCR-mediated acti vation. We used DNase I-footprinting, EMSAs, and transient transfection ass ays to identify the minimal TCR signal-responsive region within the fasl pr omoter. This region contains the previously identified binding sites for NF -kappa B and Egr and the AP-1 site identified in this study. We found that TCR signaling induces AP-1 binding to this site and regulates the fasl prom oter function in a fashion dependent on NF-kappa B binding, However, mutati on in the AP-1 site alone did not show a significant effect on the promoter function. The data suggest that the minimal promoter required at least two transcription factors to function.