DNA repair is a series of processes by which a cell detects and corrects damage to the DNA molecules that encode its genome. Here, we show that H2A.Z exchange and subsequent removal by Anp32e plays a critical role in the early chromatin processing events at DSBs.
Firstly, we found DNA damage created by laser micro-irradiation led to an increase in γH2AX and accumulation of Anp32e. The accumulation of H2A.Z on nucleosomes at DSBs is transient, and that rapid eviction of H2A.Z is required for DSB repair.
Next, loss of Anp32e reduced H4Ac at DSBs, indicating that Anp32e is required for H4Ac after DNA damage. Increased H4 acetylation by NuA4–Tip60 at DSBs also facilitates the formation of open, relaxed chromatin at DSBs.
Finally, phosphorylated H2AX (γH2AX) provides a binding site for mdc1, which promotes spreading of γH2AX for hundreds of kilobases either side of the break. When H2A.Z removal by Anp32e is blocked, nucleosomes at DSBs retain elevated levels of H2A.Z, and assume a more stable, hypoacetylated conformation.
This study show that Anp32e remove H2A.z to provide an essential binding site for key proteins involved in the earliest events of DSB repair.