DNA‐PKcs and ATM modulate mitochondrial ADP‐ATP exchange as an oxidative stress checkpoint mechanism

Abstract

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 D NA‐PKcs/ A NT2/ V DAC2 (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. image Mitochondrial ADP‐ATP exchange is attenuated quickly in response to oxidative stress. This study identifies DNA‐PKcs as a novel oxidative stress checkpoint protein that forms a complex with mitochondrial factors ANT2‐VDAC2 (DAV complex) to modulate mitochondrial ADP‐ATP exchange and oxidative phosphorylation (OXPHOS). OXPHOS is attenuated in the absence of DNA‐PKcs. DNA‐PKcs interacts with mitochondrial proteins ANT2 and VDAC2 to mediate ADP‐ATP exchange. Oxidative stress dissociates DNA‐PKcs from ANT2 and thereby attenuates ADP‐ATP exchange. ATM kinase, as a sensor of oxidative stress, modulates the stability of the DAV complex via DNA‐PKcs phosphorylation at the Thr2609 cluster.