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

The present study demonstrates that transcription factor interactions are important in regulating the murine fasl promoter following TCR-mediated activation. We used DNase I-footprinting, EMSAs, and transient transfection assays to identify the minimal TCR signal-responsive region within the fasl promoter. This region contains the previously identified binding sites for NF-kappaB 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 promoter function in a fashion dependent on NF-kappaB binding. However, mutation 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.