Dose-Dependent Temporal Dynamics of FOXO1 and 53BP1 in Response to H2O2-induced Oxidative Stress

Abstract

Oxidative stress driven by reactive oxygen species (ROS) such as hydrogen peroxide (H2O2), plays a pivotal role in regulating cellular homeostasis and genomic stability through activation of stress response pathways, including DNA repair mechanisms. This study investigates the temporal dynamics of Forkhead box-O1 (FOXO1), a key transcription factor for maintaining cellular homeostasis and p53-binding protein-1 (53BP1), a crucial player in the DNA damage response, in response to varying doses of. H2O2-induced oxidative stress. Cells harboring FOXO1 and 53BP1 fluorescent reporters were exposed to increasing concentrations of H2O2 and FOXO1 activation and 53BP1 foci formation were tracked using live cell microscopy over a 24-hour period. Quantitative image analysis revealed that FOXO1 nuclear localization exhibited a rapid but variable activation pattern across cells, with duration increasing in a dose-dependent manner. In contrast, 53BP1 foci formation showed a surprising slower accumulation at higher H2O2 concentrations, suggesting possible impairment of double-strand break (DSB) DNA repair or a shift towards alternative repair pathways. Our findings indicate that oxidative stress modulates DNA repair dynamics in a dose-dependent manner, with higher levels of H2O2 potentially altering the efficiency or pathway choice of DSB repair mechanisms.