Kobayashi Junya, Tauchi Hiroshi, Chen Benjamin, Burma Sandeep, Tashiro Satoshi, Matsuura Shinya, Tanimoto Keiji, Chen David J, Komatsu Kenshi
Department of Genome Repair Dynamics, Radiation Biology Center, Kyoto University, Kyoto 606-8501, Japan.
Biochem Biophys Res Commun. 2009 Mar 20;380(4):752-7. doi: 10.1016/j.bbrc.2009.01.109. Epub 2009 Jan 23.
Phosphorylated histone H2AX (gamma-H2AX) functions in the recruitment of DNA damage response proteins to DNA double-strand breaks (DSBs) and facilitates DSB repair. ATM also co-localizes with gamma-H2AX at DSB sites following its auto-phosphorylation. However, it is unclear whether gamma-H2AX has a role in activation of ATM-dependent cell cycle checkpoints. Here, we show that ATM as well as NBS1 is recruited to damaged-chromatin in a gamma-H2AX-dependent manner. Foci formation of phosphorylated ATM and ATM-dependent phosphorylation is repressed in H2AX-knockdown cells. Furthermore, anti-gamma-H2AX antibody co-immunoprecipitates an ATM-like protein kinase activity in vitro and recombinant H2AX increases in vitro kinase activity of ATM from un-irradiated cells. Moreover, H2AX-deficient cells exhibited a defect in ATM-dependent cell cycle checkpoints. Taken together, gamma-H2AX has important role for effective DSB-dependent activation of ATM-related damage responses via NBS1.
磷酸化组蛋白H2AX（γ-H2AX）在将DNA损伤反应蛋白招募至DNA双链断裂（DSB）处发挥作用，并促进DSB修复。ATM在自身磷酸化后也会与γ-H2AX在DSB位点共定位。然而，γ-H2AX是否在ATM依赖的细胞周期检查点激活中发挥作用尚不清楚。在此，我们表明ATM以及NBS1以γ-H2AX依赖的方式被招募至受损染色质。在H2AX敲低细胞中，磷酸化ATM的焦点形成以及ATM依赖的磷酸化受到抑制。此外，抗γ-H2AX抗体在体外共免疫沉淀出一种ATM样蛋白激酶活性，并且重组H2AX增加了未受辐射细胞中ATM的体外激酶活性。此外，H2AX缺陷细胞在ATM依赖的细胞周期检查点方面表现出缺陷。综上所述，γ-H2AX通过NBS1对有效的DSB依赖的ATM相关损伤反应激活具有重要作用。
