Cleavage and phosphorylation of XRCC4 protein induced by X-irradiation

Yoshihisa Matsumoto, Norio Suzuki, Naoki Namba, Noriko Umeda, Xue Jun Ma, Akinori Morita, Masanori Tomita, Atsushi Enomoto, Shinobu Serizawa, Kazuya Hirano, Kazuo Sakai, Hideyo Yasuda, Yoshio Hosoi

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56 Citations (Scopus)


We report the p35 and p60 forms of XRCC4 protein, appearing in human leukemia MOLT-4 or U937 cells following X-irradiation or hyperthermia. p35 appeared in conjunction with the cleavage of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and the fragmentation of internucleosomal DNA, and was suppressed by Ac-DEVD-CHO. p35 was also produced in vitro by treating MOLT-4 cell lysate with recombinant caspases, suggesting that p35 was a caspase-cleaved fragment of XRCC4 in apoptotic cell death. p60 was sensitive to treatment with phosphatase or wortmannin and was undetectable in M059J cells deficient in DNA-PKcs. However, p60 was found in ataxia-telangiectasia cells after irradiation. These results indicated p60 as a phosphorylated form of XRCC4, requiring DNA-PKcs but not ataxia-telangiectasia mutated (ATM). Copyright (C) 2000 Federation of European Biochemical Societies.

Original languageEnglish
Pages (from-to)67-71
Number of pages5
JournalFEBS Letters
Issue number1-2
Publication statusPublished - 2000 Jul 28


  • Apoptosis
  • Ataxia-telangiectasia mutated
  • Caspase
  • DNA double-strand break repair
  • DNA-dependent protein kinase
  • XRCC4


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