p53-binding Protein Inhibits Intracellular Reactive Oxygen Species by Increasing the Expression of Metallothioneins.

Background/aim: Accumulation of reactive oxygen species (ROS), which is essential for normal cell function and signaling, can induce oxidative stress that leads to cellular damage and various diseases, including cancer, thereby underscoring the crucial role of intracellular antioxidant systems in maintaining ROS balance. The p53-binding protein 1 (53BP1) is a key regulator of DNA double-strand break (DSB) repair, however, its role in ROS regulation remains unclear. This study aimed to investigate the involvement of 53BP1 in ROS homeostasis and its potential impact on oxidative stress regulation.

Materials And Methods: Fluorescence microscopy and flow cytometry using MitoSOX indicators were performed to measure the amount of ROS in 53BP1-deficient cells. To elucidate the ROS regulatory genes mediated by 53BP1, the expression of NOX1, MT1F, and MT2A mRNA was analyzed through quantitative real-time PCR (qRT-PCR).

Results: Silencing 53BP1 led to a significant increase in both ROS and mitochondrial superoxide levels, while transfection of 53BP1-deficient cells with a 53BP1 expression vector reduced ROS accumulation. In addition, 53BP1-depleted cells showed increased expression of NOX1 mRNA and decreased expression of MT1F and MT2A, suggesting a potential antioxidative mechanism.

Conclusion: 53BP1 plays a crucial role in maintaining ROS homeostasis by regulating genes involved in oxidative stress response. These results suggest that targeting ROS regulation through 53BP1-related pathways may provide novel insights into therapeutic strategies for diseases associated with oxidative stress.