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ATR and ATM regulate the timing of DNA replication origin firing

David Shechter1, Vincenzo Costanzo, Jean Gautier

  • 1Integrated Program in Cellular, Molecular, and Biophysical Studies, and Department of Genetics and Development, Hammer Health Sciences Center, Columbia University College of Physicians and Surgeons, 701 West 168th Street, New York, NY 10032, USA.

Nature Cell Biology
|June 29, 2004
PubMed

Insights

ATM and ATR signaling pathways regulate DNA replication initiation during normal cell cycles. Modulating these pathways controls origin firing and DNA synthesis, preparing cells to halt replication upon DNA damage.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Genetics

Background:

  • DNA replication initiation is tightly regulated by S-phase-promoting kinases (SPKs).
  • ATM and ATR signaling pathways normally inhibit SPKs (Cdk2, Cdc7) to prevent DNA replication upon damage.

Purpose of the Study:

  • To investigate the role of ATM and ATR signaling in regulating DNA replication during an unperturbed cell cycle.
  • To understand how these pathways control origin firing and DNA synthesis progression.

Main Methods:

  • Inhibition of ATM and ATR using caffeine or neutralizing antibodies.
  • Upregulation of Cdk2 or Cdc7.
  • Inhibition of Cdc25A.
  • Monitoring replication protein A (RPA)-bound single-stranded DNA (ssDNA) and Chk1 activation.
  • Assessing ATM activation during replication.

Main Results:

  • Inhibition of ATM/ATR or upregulation of Cdk2/Cdc7 accelerated and synchronized origin firing.
  • Cdc25A inhibition slowed DNA replication.
  • RPA-bound ssDNA levels correlated with Chk1 activation and inhibited origin firing.
  • ATM was transiently activated during ongoing replication.

Conclusions:

  • ATM and ATR signaling pathways modulate SPK activity via feedback from active replicons.
  • These pathways actively regulate DNA synthesis initiation and progression in normal cell cycles.
  • The system is poised to halt replication rapidly in response to DNA damage.

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