ATR signaling mediates an S-phase checkpoint after inhibition of poly(ADP-ribose) polymerase activity

DNA Repair (Amst). 2007 Jun 1;6(6):742-50. doi: 10.1016/j.dnarep.2006.12.015. Epub 2007 Feb 9.


Human fibroblasts, capable of expressing a kinase-dead form of ATR (ATRkd), can be sensitized to the cytotoxic effects of methyl methanesulfonate (MMS) by the PARP inhibitor 4-amino-1,8-naphthalimide (4-AN). The combination of MMS+4-AN results in accumulation of cells in S-phase of the cell cycle and activation of Chk1. Inhibition of ATR activity by expression of ATRkd suppresses the S-phase accumulation and partially reverses the Chk1 phosphorylation. The results confirm involvement of an ATR-mediated damage response pathway in the MMS+4-AN-induced S-phase cell cycle checkpoint in human fibroblasts. Consistent with this hypothesis, the inhibitors caffeine and UCN-01 also abrogate the ATR- and Chk1-mediated delay in progression through S-phase. In the absence of ATR-mediated signaling, MMS+4-AN exposure results in a G(2)/M arrest, rather than an S-phase checkpoint. Thus, whereas ATR mediates the S-phase response, it is not critical for arrest of cells in G(2)/M.

Publication types

  • Research Support, N.I.H., Intramural

MeSH terms

  • 1-Naphthylamine / analogs & derivatives*
  • 1-Naphthylamine / pharmacology
  • Cell Cycle
  • Cell Division
  • Dose-Response Relationship, Drug
  • Enzyme Inhibitors / pharmacology*
  • Fibroblasts / metabolism
  • Flow Cytometry
  • G2 Phase
  • Humans
  • Methyl Methanesulfonate
  • Naphthalimides / pharmacology*
  • Phosphorylation
  • Poly(ADP-ribose) Polymerase Inhibitors*
  • Poly(ADP-ribose) Polymerases / metabolism*
  • Quinolones / pharmacology*
  • S Phase*
  • Signal Transduction*
  • Time Factors


  • Enzyme Inhibitors
  • Naphthalimides
  • Poly(ADP-ribose) Polymerase Inhibitors
  • Quinolones
  • 4-amino-1,8-naphthalimide
  • 1-Naphthylamine
  • Methyl Methanesulfonate
  • Poly(ADP-ribose) Polymerases