Open AccessATR kinase activation in G1 phase facilitates the repair of ionizing radiation-induced DNA damage
Author(s) -
Armin M. Gamper,
Reza Rofougaran,
Simon C. Watkins,
Joel S. Greenberger,
Jan H. Beumer,
Christopher J. Bakkenist
Publication year - 2013
Publication title -
nucleic acids research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.008
H-Index - 537
eISSN - 1362-4954
pISSN - 0305-1048
DOI - 10.1093/nar/gkt833
Subject(s) - biology , dna damage , kinase , phosphorylation , dna repair , microbiology and biotechnology , chek1 , protein kinase a , dna , cell , biochemistry , cell cycle , cell cycle checkpoint
The kinase ATR is activated by RPA-coated single-stranded DNA generated at aberrant replicative structures and resected double strand breaks. While many hundred candidate ATR substrates have been identified, the essential role of ATR in the replicative stress response has impeded the study of ATR kinase-dependent signalling. Using recently developed selective drugs, we show that ATR inhibition has a significantly more potent effect than ATM inhibition on ionizing radiation (IR)-mediated cell killing. Transient ATR inhibition for a short interval after IR has long-term consequences that include an accumulation of RPA foci and a total abrogation of Chk1 S345 phosphorylation. We show that ATR kinase activity in G1 phase cells is important for survival after IR and that ATR colocalizes with RPA in the absence of detectable RPA S4/8 phosphorylation. Our data reveal that, unexpectedly, ATR kinase inhibitors may be more potent cellular radiosensitizers than ATM kinase inhibitors, and that this is associated with a novel role for ATR in G1 phase cells.