Epsin 3 Promotes Cellular Senescence Through Reactive Oxygen Species‐Mediated Induction of <scp>DNA</scp> Damage

Cellular senescence is caused by various stresses, including DNA damage, oxidative stress, oncogene activation, and telomere shortening. However, the detailed molecular mechanisms of cellular senescence have yet to be elucidated. Recently, using comparative transcriptomics and quantitative PCR, we identified several genes that are specifically upregulated in senescent cells in a p53-dependent manner, including Epsin 3 (EPN3). However, the functional relevance of EPN3 to senescence has not yet been defined. Here, we performed functional analyses to investigate the relationship between EPN3 and the senescence program. We found that EPN3 knockdown suppressed senescent phenotypes induced by DNA damage. Furthermore, ectopic expression of EPN3 induced senescence accompanied by increased reactive oxygen species (ROS) and accumulation of DNA damage. Furthermore, EPN3-induced DNA damage was suppressed by genetic and pharmacological inhibition of Rac1. Finally, treatment with ROS scavengers, N-acetyl-l-cysteine (NAC) and l-Ascorbic Acid (LAA), prevented EPN3-induced DNA damage, and a Rac1 inhibitor reduced ROS levels in EPN3-expressing stable clones. These results indicate that EPN3 induces DNA damage and promotes senescence via Rac1 activity and ROS generation.