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 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.

Ataxia Telangiectasia patient-derived neuronal and brain organoid models reveal mitochondrial dysfunction and oxidative stress

“…suggesting that impairments to these ATM-regulated DNA damage response pathways do not cause mitochondrial defects in this cell type. This aligns with the premise that mitochondrial impairments and oxidative stress in ATM deficient cells are not merely a downstream result of accumulating nuclear DNA damage [20,67].…”

“…These findings are of particular interest, as previous studies showed that AT ONS cells possess neuronal-like features and exhibit hypersensitivity to radiation, defective radiation-induced signalling and cell cycle checkpoint defects [26], suggesting that impairments to these ATM-regulated DNA damage response pathways do not cause mitochondrial defects in this cell type. This aligns with the premise that mitochondrial impairments and oxidative stress in ATM deficient cells are not merely a downstream result of accumulating nuclear DNA damage [20, 67].…”

Cancer Metabolism: The Role of ROS in DNA Damage and Induction of Apoptosis in Cancer Cells

“…DNA-PKcs can directly interact with mitochondrial proteins ANT2 and VDAC2. The resulting DNA-PKcs/ANT2/VDAC2 (DAV complex) regulates mitochondrial ADP–ATP exchange and OXPHOS, thereby accelerating cellular oxidative stress repair [ 119 ].…”

High-Efficiency Enrichment by Saturating Nanoliters of Protein Affinity Media

“…The accessory factors APLF and WRN were identified, and several other proteins thought to be involved in regulating NHEJ (e.g., MRE11). We also discovered a rich complement of mitochondrial proteins that have only recently been uncovered . Many of the proteins that we detected are anticipated to be novel binders or substrates of DNA-PKcs, but this will require extensive biological validation.…”

“…We also discovered a rich complement of mitochondrial proteins that have only recently been uncovered. 45 Many of the proteins that we detected are anticipated to be novel binders or substrates of DNA-PKcs, but this will require extensive biological validation.…”