Cited by 1,085DNA Repair MechanismsCancer-related Molecular PathwaysEffects of Radiation Exposure

The ATM-Chk2-Cdc25A checkpoint pathway guards against radioresistant DNA synthesis

Falck, Jacob, Mailand, Niels, Syljuåsen, Randi G., Bartek, Jiri, Lukas, Jiri·2001·Nature

Abstract

When exposed to ionizing radiation (IR), eukaryotic cells activate checkpoint pathways to delay the progression of the cell cycle. Defects in the IR-induced S-phase checkpoint cause 'radioresistant DNA synthesis', a phenomenon that has been identified in cancer-prone patients suffering from ataxia-telangiectasia, a disease caused by mutations in the ATM gene. The Cdc25A phosphatase activates the cyclin-dependent kinase 2 (Cdk2) needed for DNA synthesis, but becomes degraded in response to DNA damage or stalled replication. Here we report a functional link between ATM, the checkpoint signalling kinase Chk2/Cds1 (Chk2) and Cdc25A, and implicate this mechanism in controlling the S-phase checkpoint. We show that IR-induced destruction of Cdc25A requires both ATM and the Chk2-mediated phosphorylation of Cdc25A on serine 123. An IR-induced loss of Cdc25A protein prevents dephosphorylation of Cdk2 and leads to a transient blockade of DNA replication. We also show that tumour-associated Chk2 alleles cannot bind or phosphorylate Cdc25A, and that cells expressing these Chk2 alleles, elevated Cdc25A or a Cdk2 mutant unable to undergo inhibitory phosphorylation (Cdk2AF) fail to inhibit DNA synthesis when irradiated. These results support Chk2 as a candidate tumour suppressor, and identify the ATM-Chk2-Cdc25A-Cdk2 pathway as a genomic integrity checkpoint that prevents radioresistant DNA synthesis.

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Crossref · 10.1038/35071124

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Authors
Falck, J., Mailand, N., Syljuåsen, R. G., Bartek, J., & Lukas, J.
Affiliations
Danish Cancer Society (DK)
Venue
Nature
Published
2001-04
Volume
410
Issue
6830
Pages
842-847
ISSN
  • 0028-0836 (ISSN-L)
  • 1476-4687
OpenAlex
W1480741751
Cited by
1,085
References
30
Citations by year
2026: 14 · 2025: 11 · 2024: 22 · 2023: 20 · 2022: 24 · 2021: 29 · 2020: 19 · 2019: 31 · 2018: 24 · 2017: 30 · 2016: 40 · 2015: 30 · 2014: 37 · 2013: 43 · 2012: 55
FWCI
29.91
Type
journal article
Language
en
Open access
closed
Locations
  • Nature (publishedVersion)
  • PubMed (publishedVersion)
  • RePEc: Research Papers in Economics (submittedVersion)
Funders
National Institute on Aging
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › DNA Repair Mechanisms
  • Health Sciences › Medicine › Oncology › Cancer-related Molecular Pathways
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Effects of Radiation Exposure
Keywords
radioresistant DNA synthesis, ATM, Chk2, CDC25A, CDK2, S-phase checkpoint, ionizing radiation, DNA damage response, tumour suppressor, ataxia telangiectasia, DNA replication inhibition, protein phosphorylation
MeSH terms
Alleles, Animals, Cell Cycle, Cell Line, DNA Replication, DNA-Binding Proteins, Humans, Phosphorylation, Protein Kinases, Radiation Tolerance, Radiation, Ionizing, Serine, Transfection, Signal Transduction, S Phase, Protein Serine-Threonine Kinases, Cell Cycle Proteins, cdc25 Phosphatases, Tumor Suppressor Proteins, Mice, Ataxia Telangiectasia Mutated Proteins, Checkpoint Kinase 2

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