WIP1 phosphatase suppresses the DNA damage response during G2/prophase arrest in mouse oocytes.

Maternal DNA damage during meiosis causes genetic abnormalities that can lead to infertility, birth defects, and abortion. While DNA damage can rapidly halt cell cycle progression and promote DNA repair in somatic cells, mammalian oocytes are unable to mount a robust G2/prophase arrest in response to DNA damage unless damage levels are severe. Here, we show that inhibition of WIP1 phosphatase enhances the ability of oocytes to respond to DNA damage. We found that WIP1 was expressed constantly during meiotic maturation, and that inhibition of WIP1 activity did not impair meiotic maturation. However, oocytes in G2/prophase were sensitized to DNA damage following WIP1 inhibition, not only increasing γ-H2AX level and ATM phosphorylation, but also decreasing entry into meiosis. Moreover, WIP1 inhibition significantly promoted the repair of damaged DNA during G2/prophase arrest, suggesting that WIP1 suppresses DNA repair in oocytes. Therefore, our results suggest that WIP1 is a key suppressor of the DNA damage response during G2/prophase arrest in mouse oocytes.