title: ATR signaling mediates an S-phase checkpoint after inhibition of poly(ADP-ribose) polymerase activity.
abstract: 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.
authors.affiliation: Laboratory of Structural Biology, NIEHS, National Institutes of Health, 111 T.W. Alexander Dr., Research Triangle Park, NC 27709, USA.
authors.forename: Julie K
authors.initials: JK
authors.lastname: Horton
authors.forename: Donna F
authors.initials: DF
authors.lastname: Stefanick
authors.forename: Padmini S
authors.initials: PS
authors.lastname: Kedar
authors.forename: Samuel H
authors.initials: SH
authors.lastname: Wilson
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D002453:Cell Cycle; D002455:Cell Division; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D016195:G2 Phase; D006801:Humans; D008741:Methyl Methanesulfonate; D053644:Naphthalimides / Q000494:pharmacology*; D010766:Phosphorylation; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D015363:Quinolones / Q000494:pharmacology*; D016196:S Phase; D015398:Signal Transduction; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D053644:Naphthalimides; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D015363:Quinolones; C086538:4-amino-1,8-naphthalimide; D015057:1-Naphthylamine; D008741:Methyl Methanesulfonate; D011065:Poly(ADP-ribose) Polymerases