title: Ataxia telangiectasia mutated (ATM) is essential for DNA-PKcs phosphorylations at the Thr-2609 cluster upon DNA double strand break.
abstract: The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is rapidly phosphorylated at the Thr-2609 cluster and Ser-2056 upon ionizing radiation (IR). Furthermore, DNA-PKcs phosphorylation at both regions is critical for its role in DNA double strand break (DSB) repair as well as cellular resistance to radiation. IR-induced DNA-PKcs phosphorylation at Thr-2609 and Ser-2056, however, exhibits distinct kinetics indicating that they are differentially regulated. Although DNA-PKcs autophosphorylates itself at Ser-2056 after IR, we have reported here that ATM mediates DNA-PKcs phosphorylation at Thr-2609 as well as at the adjacent (S/T)Q motifs within the Thr-2609 cluster. In addition, our data suggest that DNA-PKcs- and ATM-mediated DNA-PKcs phosphorylations are cooperative and required for the full activation of DNA-PKcs and the subsequent DSB repair. Elimination of DNA-PKcs phosphorylation at both regions severely compromises radioresistance and DSB repair. Finally, our result provides a possible mechanism for the direct involvement of ATM in non-homologous end joining-mediated DSB repair.
authors.affiliation: Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390, USA.
authors.forename: Benjamin P C
authors.initials: BP
authors.lastname: Chen
authors.forename: Naoya
authors.initials: N
authors.lastname: Uematsu
authors.forename: Junya
authors.initials: J
authors.lastname: Kobayashi
authors.forename: Yaniv
authors.initials: Y
authors.lastname: Lerenthal
authors.forename: Andrea
authors.initials: A
authors.lastname: Krempler
authors.forename: Hirohiko
authors.initials: H
authors.lastname: Yajima
authors.forename: Markus
authors.initials: M
authors.lastname: Löbrich
authors.forename: Yosef
authors.initials: Y
authors.lastname: Shiloh
authors.forename: David J
authors.initials: DJ
authors.lastname: Chen
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000502:physiology*; D002478:Cells, Cultured; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000502:physiology*; D005347:Fibroblasts / Q000166:cytology; D006801:Humans; D007700:Kinetics; D010766:Phosphorylation / Q000528:radiation effects; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D011839:Radiation, Ionizing; D012694:Serine / Q000378:metabolism; D013912:Threonine / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000502:physiology*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; D013912:Threonine; D012694:Serine; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases