Increased levels of E2F-1-dependent DNA binding activity after UV- or gamma-irradiation

In mammalian cells, DNA damage induces robust changes in gene expression an d these changes contribute to the proper execution of cellular responses to DNA damage, including DNA repair, cell cycle arrest and apoptosis, The tra nscription factor E2F-1 has been suggested to play a key role in the regula tion of cell cycle-dependent gene expression and apoptosis. These activitie s depend on the ability of E2F-1 to form functionally active DNA binding co mplexes. Here we describe an assay that allows one to measure E2F-1 DNA bin ding activity in naive cells, We find that DNA damage, generated by UV- or gamma-irradiation, prompts increased production of E2F-1 DNA binding activi ty, which, at least in part, originates from alterations in E2F-1 protein l evels, These findings represent an indication for a role of the transcripti on factor E2F-1 in the DNA damage response pathway.