Autophosphorylation of the DNA-dependent protein kinase catalytic subunit is required for rejoining of DNA double-strand breaks

  1. Doug W. Chan1,2,5,
  2. Benjamin Ping-Chi Chen1,5,
  3. Sheela Prithivirajsingh3,
  4. Akihiro Kurimasa1,4,
  5. Michael D. Story3,
  6. Jun Qin2, and
  7. David J. Chen1,6
  1. 1Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; 2Verna and Marrs McLean Department of Biochemistry and Molecular Biology, and Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas 77030, USA; 3Department of Experimental Radiotherapy, M. D. Anderson Cancer Center, University of Texas, Houston, Texas 77030, USA

Abstract

Nonhomologous end-joining (NHEJ) is the predominant pathway that repairs DNA double-strand breaks (DSBs) in mammalian cells. The DNA-dependent protein kinase (DNA-PK), consisting of Ku and DNA-PK catalytic subunit (DNA-PKcs), is activated by DNA in vitro and is required for NHEJ. We report that DNA-PKcs is autophosphorylated at Thr2609 in vivo in a Ku-dependent manner in response to ionizing radiation. Phosphorylated DNA-PKcs colocalizes with both γ-H2AX and 53BP1 after DNA damage. Mutation of Thr2609 to Ala leads to radiation sensitivity and impaired DSB rejoining. These findings establish that Ku-dependent phosphorylation of DNA-PKcs at Thr2609 is required for the repair of DSBs by NHEJ.

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Footnotes

  • 4 Present address: Life Science Division, Tottori University, Tottori 683-8503, Japan.

  • 5 These authors contributed equally to this work.

  • 6 Corresponding author.

  • E-MAIL djchen{at}lbl.gov; FAX (510) 486-6816.

  • Article and publication are at http://www.genesdev.org/cgi/doi/10.1101/gad.1015202.

    • Received June 13, 2002.
    • Accepted July 25, 2002.
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