Radiation-dose-dependent functional synergisms between ATM, ATR and DNA-PKcs in checkpoint control and resection in G2-phase

• Published in: Scientific reports 2019-06, Vol.9 (1), p.8255, Article 8255
• Main Authors: Mladenov, Emil, Fan, Xiaoxiang, Dueva, Rositsa, Soni, Aashish, Iliakis, George
• Format: Article
• Language: English
• Subjects: 13/109; 13/31; 13/89; 14/19; 14/63; 631/337/1427/2122; 631/337/1427/2567; 82/29; Cell cycle; CHK1 protein; Deoxyribonucleic acid; DNA; DNA damage; DNA-dependent protein kinase; Double-strand break repair; Genomes; Humanities and Social Sciences; Ionizing radiation; multidisciplinary; Non-homologous end joining; Protein kinase C; Science; Science (multidisciplinary)
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-44771-6

Using data generated with cells exposed to ionizing-radiation (IR) in G 2 -phase of the cell cycle, we describe dose-dependent interactions between ATM, ATR and DNA-PKcs revealing unknown mechanistic underpinnings for two key facets of the DNA damage response: DSB end-resection and G 2 -checkpoint activation. At low IR-doses that induce low DSB-numbers in the genome, ATM and ATR regulate epistatically the G 2 -checkpoint, with ATR at the output-node, interfacing with the cell-cycle predominantly through Chk1. Strikingly, at low IR-doses, ATM and ATR epistatically regulate also resection, and inhibition of either activity fully suppresses resection. At high IR-doses that induce high DSB-numbers in the genome, the tight ATM/ATR coupling relaxes and independent outputs to G 2 -checkpoint and resection occur. Consequently, both kinases must be inhibited to fully suppress checkpoint activation and resection. DNA-PKcs integrates to the ATM/ATR module by regulating resection at all IR-doses, with defects in DNA-PKcs causing hyper-resection and G 2 -checkpoint hyper-activation. Notably, hyper-resection is absent from other c-NHEJ mutants. Thus, DNA-PKcs specifically regulates resection and adjusts the activation of the ATM/ATR module. We propose that selected DSBs are shepherd by DNA-PKcs from c-NHEJ to resection-dependent pathways for processing under the regulatory supervision of the ATM/ATR module.