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A role for ATR in the DNA damage-induced phosphorylation of p53

R S Tibbetts1, K M Brumbaugh, J M Williams

  • 1Department of Pharmacology and Cancer Cell Biology, Duke University, Durham, North Carolina 27710 USA.

Genes & Development
|January 30, 1999
PubMed

Insights

The ATM-Rad3-related protein ATR regulates the phosphorylation of p53 at Ser-15, a key event for p53 activation during DNA damage. This study shows ATR directly phosphorylates p53, highlighting its role in the cellular stress response.

Area of Science:

  • Molecular Biology
  • Cellular Stress Response
  • DNA Damage Signaling

Background:

  • Phosphorylation of p53 at Ser-15 is crucial for its activation during cellular stress.
  • The upstream regulators of p53 Ser-15 phosphorylation in response to DNA damage are not fully understood.

Purpose of the Study:

  • To investigate the role of the ATM-Rad3-related protein (ATR) in regulating p53 Ser-15 phosphorylation.
  • To determine if ATR directly phosphorylates p53.

Main Methods:

  • Overexpression of catalytically inactive ATR (ATRki) in human fibroblasts.
  • Exposure of cells to gamma-irradiation and UV light.
  • In vitro kinase assays using ATR and p53.

Main Results:

  • ATR inhibition (ATRki) blocked Ser-15 phosphorylation in response to both gamma-irradiation and UV light.
  • ATR inhibition selectively affected late-phase Ser-15 phosphorylation after gamma-irradiation but was time-independent for UV-induced phosphorylation.
  • In vitro, ATR directly phosphorylated p53 at Ser-15 and Ser-37.

Conclusions:

  • ATR is a key regulator of p53 Ser-15 phosphorylation in DNA-damaged cells.
  • ATR directly phosphorylates p53, suggesting p53 is a direct target of ATR.
  • ATR's regulation of p53 phosphorylation differs depending on the type of DNA damage.

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