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Updated: Oct 11, 2026

Study of the DNA Damage Checkpoint using Xenopus Egg Extracts
10:55

Study of the DNA Damage Checkpoint using Xenopus Egg Extracts

Published on: November 5, 2012

Reconstitution of an ATM-dependent checkpoint that inhibits chromosomal DNA replication following DNA damage

V Costanzo1, K Robertson, C Y Ying

  • 1Department of Genetics and Development, Columbia University, New York, NY 10032, USA.

Molecular Cell
|October 13, 2000
PubMed

Insights

This study reveals a DNA damage checkpoint pathway in Xenopus that halts DNA replication initiation. This ATM-dependent pathway prevents S phase entry, independent of p53, by regulating key replication proteins.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • Cell cycle checkpoints prevent cell cycle progression after DNA damage.
  • A Xenopus cell-free system reconstitutes the DNA replication checkpoint pathway.

Purpose of the Study:

  • To describe a DNA damage checkpoint pathway that inhibits DNA replication initiation.
  • To investigate the molecular mechanisms of this checkpoint in a vertebrate system.

Main Methods:

  • Utilized a Xenopus egg-derived cell-free system.
  • Assessed the dose-dependent inhibition of replication initiation by double-strand breaks.
  • Analyzed protein complex assembly and phosphorylation events.

Main Results:

  • DNA double-strand breaks inhibit replication initiation in a dose-dependent manner.
  • Checkpoint activation involves ATM, Cdk2/CyclinE, and affects prereplicative complex formation.
  • Cdc25A overrides the checkpoint, restoring DNA replication.

Conclusions:

  • A novel DNA damage checkpoint pathway prevents S phase entry independently of p53 transcriptional activity.
  • This pathway involves ATM-dependent regulation of Cdk2/CyclinE and prereplicative complex components.

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