Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX, USA.
Department of Life Science, National Taiwan University, Taipei, Taiwan.
EMBO J. 2023 Mar 15;42(6):e112094. doi: 10.15252/embj.2022112094. Epub 2023 Feb 2.
DNA-PKcs is a key regulator of DNA double-strand break repair. Apart from its canonical role in the DNA damage response, DNA-PKcs is involved in the cellular response to oxidative stress (OS), but its exact role remains unclear. Here, we report that DNA-PKcs-deficient human cells display depolarized mitochondria membrane potential (MMP) and reoriented metabolism, supporting a role for DNA-PKcs in oxidative phosphorylation (OXPHOS). DNA-PKcs directly interacts with mitochondria proteins ANT2 and VDAC2, and formation of the DNA-PKcs/ANT2/VDAC2 (DAV) complex supports optimal exchange of ADP and ATP across mitochondrial membranes to energize the cell via OXPHOS and to maintain MMP. Moreover, we demonstrate that the DAV complex temporarily dissociates in response to oxidative stress to attenuate ADP-ATP exchange, a rate-limiting step for OXPHOS. Finally, we found that dissociation of the DAV complex is mediated by phosphorylation of DNA-PKcs at its Thr2609 cluster by ATM kinase. Based on these findings, we propose that the coordination between the DAV complex and ATM serves as a novel oxidative stress checkpoint to decrease ROS production from mitochondrial OXPHOS and to hasten cellular recovery from OS.
DNA-PKcs 是 DNA 双链断裂修复的关键调节因子。除了其在 DNA 损伤反应中的典型作用外，DNA-PKcs 还参与细胞对氧化应激（OS）的反应，但它的确切作用仍不清楚。在这里，我们报告说，缺乏 DNA-PKcs 的人细胞显示出线粒体膜电位（MMP）去极化和代谢重新定向，这支持了 DNA-PKcs 在氧化磷酸化（OXPHOS）中的作用。DNA-PKcs 与线粒体蛋白 ANT2 和 VDAC2 直接相互作用，并且 DNA-PKcs/ANT2/VDAC2（DAV）复合物的形成支持 ADP 和 ATP 跨线粒体膜的最佳交换，通过 OXPHOS 为细胞提供能量并维持 MMP。此外，我们证明 DAV 复合物会响应氧化应激暂时解离，以减弱 OXPHOS 的限速步骤 ADP-ATP 交换。最后，我们发现 DAV 复合物的解离是由 ATM 激酶对 DNA-PKcs 的 Thr2609 簇进行磷酸化介导的。基于这些发现，我们提出 DAV 复合物和 ATM 之间的协调作为一种新的氧化应激检查点，可减少来自线粒体 OXPHOS 的 ROS 产生，并加速细胞从 OS 中恢复。
