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Recurrent initiation: a mechanism for triggering p53 pulses in response to DNA damage

Eric Batchelor1, Caroline S Mock, Irun Bhan

  • 1Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.

Molecular Cell
|May 13, 2008
PubMed

Insights

DNA damage triggers p53 pulses. These pulses are driven by upstream kinases ATM and Chk2, not just the p53/Mdm2 loop, revealing new insights into DNA damage signaling.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • DNA Damage Response

Background:

  • The tumor suppressor protein p53 exhibits pulsatile behavior following DNA damage.
  • The p53/Mdm2 negative feedback loop is widely considered the primary driver of p53 dynamics.
  • The specific mechanisms governing the precise shape and timing of p53 pulses remain incompletely understood.

Purpose of the Study:

  • To investigate the underlying mechanisms responsible for the pulsatile dynamics of p53.
  • To determine whether the p53/Mdm2 loop alone can explain observed p53 pulses.
  • To elucidate the roles of upstream signaling kinases and feedback loops in regulating p53 dynamics.

Main Methods:

  • Quantitative analysis of p53 dynamics at high temporal resolution.
  • Investigation of the influence of upstream kinases ATM (Ataxia-Telangiectasia Mutated) and Chk2 (Checkpoint Kinase 2) on p53 pulsing.
  • Examination of the role of the Wip1 (Wild-type p53-induced phosphatase 1) feedback loop in modulating p53 pulse characteristics.

Main Results:

  • Evidence suggests the p53/Mdm2 negative feedback loop is insufficient to explain p53 pulses.
  • p53 pulses are externally driven by upstream signaling kinases ATM and Chk2.
  • Negative feedback involving p53, ATM, and Wip1 is crucial for maintaining uniform p53 pulse shapes.

Conclusions:

  • p53 pulses are initiated by repeated ATM activation, driven by persistent DNA damage.
  • The Wip1-mediated feedback loop is essential for stabilizing p53 pulse uniformity.
  • High-resolution dynamic data are critical for understanding complex signaling pathway regulation and offer avenues for therapeutic manipulation.

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