Temporal Coordination of the Transcription Factor Response to H₂O₂ stress

Oxidative stress from excess H₂O₂ activates transcription factors (TFs) that restore redox balance and repair oxidative damage. Though many TFs are activated by H₂O₂, it is unknown whether they are activated at the same H₂O₂ concentration or time after H₂O₂ stress. We found TF activation is tightly coordinated over time and dose dependent. We first focused on p53 and FOXO1 and found that in response to low H₂O₂, p53 is activated rapidly while FOXO1 remains inactive. In contrast, cells respond to high H₂O₂ in two temporal phases. In the first phase FOXO1 rapidly shuttles to the nucleus while p53 remains inactive. In the second phase FOXO1 shuts off and p53 levels rise. Other TFs are activated in the first phase with FOXO1 (NF-κB, NFAT1), or the second phase with p53 (NRF2, JUN), but not both. The two phases result in large differences in gene expression. Finally, we provide evidence that 2-Cys peroxiredoxins control which TF are activated and the timing of TF activation.