Regulation of the DNA Damage Response by DNA-PKcs Inhibitory Phosphorylation of ATM

Mol Cell. 2017 Jan 5;65(1):91-104. doi: 10.1016/j.molcel.2016.11.004. Epub 2016 Dec 8.


Ataxia-telangiectasia mutated (ATM) regulates the DNA damage response as well as DNA double-strand break repair through homologous recombination. Here we show that ATM is hyperactive when the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is chemically inhibited or when the DNA-PKcs gene is deleted in human cells. Pre-incubation of ATM protein with active DNA-PKcs also significantly reduces ATM activity in vitro. We characterize several phosphorylation sites in ATM that are targets of DNA-PKcs and show that phospho-mimetic mutations at these residues significantly inhibit ATM activity and impair ATM signaling upon DNA damage. In contrast, phospho-blocking mutations at one cluster of sites increase the frequency of apoptosis during normal cell growth. DNA-PKcs, which is integral to the non-homologous end joining pathway, thus negatively regulates ATM activity through phosphorylation of ATM. These observations illuminate an important regulatory mechanism for ATM that also controls DNA repair pathway choice.

Keywords: ATM; DNA repair; DNA-PKcs; cell-cycle checkpoint; phosphorylation; protein kinase.

MeSH terms

  • Apoptosis
  • Ataxia Telangiectasia Mutated Proteins / genetics
  • Ataxia Telangiectasia Mutated Proteins / metabolism*
  • Cell Cycle
  • Cell Line, Tumor
  • Cell Proliferation
  • DNA Breaks, Double-Stranded*
  • DNA Repair*
  • DNA-Activated Protein Kinase / genetics
  • DNA-Activated Protein Kinase / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Embryonic Stem Cells / enzymology
  • Genotype
  • HEK293 Cells
  • Humans
  • Mutation
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Oxidative Stress
  • Phenotype
  • Phosphorylation
  • RNA Interference
  • Signal Transduction
  • Time Factors
  • Transfection


  • DNA-Binding Proteins
  • Nuclear Proteins
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Atm protein, mouse
  • DNA-Activated Protein Kinase
  • PRKDC protein, human
  • Prkdc protein, mouse