DNA synthesis from unbalanced nucleotide pools causes limited DNA damage that triggers ATR-CHK1-dependent p53 activation
- 29 April 2008
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 105 (17), 6314-6319
- https://doi.org/10.1073/pnas.0802080105
Abstract
P53-dependent G(1) and G(2) cell cycle checkpoints are activated in response DNA damage that help to maintain genomic stability. p53 also helps to protect cells from damage that occurs during S phase, for example, when the cells are starved for DNA precursors or irradiated with a low dose of UV. p53 is activated in normal cells starved for pyrimidine nucleotides by treatment with N-(phosphonacetyl)-l-aspartate (PALA). The treated cells progress through a first S phase with kinetics similar to those of untreated cells. However, the DNA of the treated cells begins to become damaged rapidly, within 12 h, as revealed by a comet assay, which detects broken DNA, and by staining for phosphorylated histone H2AX, which accumulates at sites of DNA damage. Because the cells survive, the damage must be reversible, suggesting single-strand breaks or gaps as the most likely possibility. The transiently damaged DNA stimulates activation of ATR and CHK1, which in turn catalyze the phosphorylation and accumulation of p53. Although PALA-induced DNA damage occurs only in dividing cells, the p53 that is activated is only competent to transcribe genes such as p21 and macrophage inhibitory cytokine 1 (whose products regulate G(2) and G(1) or S phase checkpoints, respectively) after the cells have exited the S phase during which damage occurs. We propose that p53 is activated by stimulation of mismatch repair in response to the misincorporation of deoxynucleotides into newly synthesized DNA, long before the lack of pyrimidine nucleoside triphosphates causes the rate of DNA synthesis to slow appreciably.Keywords
This publication has 27 references indexed in Scilit:
- A new biomarker for mitotic cellsCytometry Part A, 2007
- Protein roadblocks and helix discontinuities are barriers to the initiation of mismatch repairProceedings of the National Academy of Sciences of the United States of America, 2007
- ATR-dependent phosphorylation and activation of ATM in response to UV treatment or replication fork stallingThe EMBO Journal, 2006
- Macrophage inhibitory cytokine 1 mediates a p53-dependent protective arrest in S phase in response to starvation for DNA precursorsProceedings of the National Academy of Sciences of the United States of America, 2006
- Inhibition of Human Chk1 Causes Increased Initiation of DNA Replication, Phosphorylation of ATR Targets, and DNA BreakageMolecular and Cellular Biology, 2005
- ATR Is Not Required for p53 Activation but Synergizes with p53 in the Replication CheckpointOnline Journal of Public Health Informatics, 2002
- p53 inhibits entry into mitosis when DNA synthesis is blockedOncogene, 1999
- The role of p53 in regulating genomic stability when DNA and RNA synthesis are inhibitedTrends in Biochemical Sciences, 1995
- Wild-type p53 restores cell cycle control and inhibits gene amplification in cells with mutant p53 allelesCell, 1992
- Altered cell cycle arrest and gene amplification potential accompany loss of wild-type p53Cell, 1992