Involvement of DNA-dependent protein kinase in UV-induced replication arrest

Jang Su Park, Su Jung Park, Xiaodong Peng, Mu Wang, Myeong Ae Yu, Suk Hee Lee

Research output: Contribution to journalArticle

55 Scopus citations


Cells exposed to UV irradiation are predominantly arrested at S-phase as well as at the G1/S boundary while repair occurs. It is not known how UV irradiation induces S-phase arrest and yet permits DNA repair; however, UV- induced inhibition of replication is efficiently reversed by the addition of replication protein A (RPA), suggesting a role for RPA in this regulatory event. Here, we show evidence that DNA-dependent protein kinase (DNA-PK), plays a role in UV-induced replication arrest. DNA synthesis of M059K (DNA-PK catalytic subunit-positive (DNA-PKcs+)), as measured by [3H]thymidine incorporation, was significantly arrested by 4 h following UV irradiation, whereas M059J (DNA-PKcs-) cells were much less affected. Similar results were obtained with the in vitro replication reactions where immediate replication arrest occurred in DNA-PKcs+ cells following UV irradiation, and only a gradual decrease in replication activity was observed in DNA-PKcs- cells. Reversal of replication arrest was observed at 8 h following UV irradiation in DNA-PKcs+ cells but not in DNA-PKcs- cells. Reversal of UV- induced replication arrest was also observed in vitro by the addition of a DNA-PK inhibitor, wortmannin, or by immunodepletion of DNA-PKcs, supporting a positive role for DNA-PK in damage-induced replication arrest. The RPA- containing fraction from UV-irradiated DNA-PKcs+ cells poorly supported DNA replication, whereas the replication activity of the RPA-containing fraction from DNA-PKcs- cells was not affected by UV, suggesting that DNA-PKcs may be involved in UV-induced replication arrest through modulation of RPA activity. Together, our results strongly suggest a role for DNA-PK in S-phase (replication) arrest in response to UV irradiation.

Original languageEnglish (US)
Pages (from-to)32520-32527
Number of pages8
JournalJournal of Biological Chemistry
Issue number45
StatePublished - Nov 5 1999

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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