Oxidation resistance 1 functions in the maintenance of cellular survival and genome stability in response to oxidative stress-independent DNA damage.

DNA damage is generated by various intrinsic and extrinsic sources such as reactive oxygen species (ROS) and environmental mutagens, and causes genomic alterations. DNA damage response (DDR) is activated to induce cell cycle arrest and DNA repair. Oxidation resistance 1 (OXR1) is a protein that defends cells against oxidative stress. We previously reported that OXR1 protein functions in the regulation of G2-phase cell cycle arrest in cells irradiated with gamma-rays, suggesting that OXR1 directly responds to DNA damage. To clarify the functions of OXR1 against ROS-independent DNA damage, HeLa and OXR1-depleted HeLa cells were treated with heavy-ion beams and the ROS-independent DNA-damaging agent methyl methanesulfonate (MMS). First, OXR1-depleted cells exhibited higher sensitivity to MMS and heavy-ion beams than control cells. Next, OXR1 depletion increased micronucleus formation and shortened the duration of G2-phase arrest after treatment with MMS or heavy-ion beams. These results suggest that OXR1 functions in the maintenance of cell survival and genome stability in response to DNA damage. Furthermore, the OXR1 protein level was increased by MMS and heavy-ion beams in HeLa cells. Together with our previous study, the present study suggests that OXR1 plays an important role in the response to DNA damage, not only when DNA damage is generated by ROS.