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ATM-dependent phosphorylation of the checkpoint clamp regulates repair pathways and maintains genomic stability

Min Hwa Shin1, Ming Yuan, Hao Zhang

  • 1Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA.

Cell Cycle (Georgetown, Tex.)
|March 29, 2012
PubMed

Insights

ATM phosphorylates Rad9 at Ser272, a process crucial for DNA repair and maintaining genomic integrity. This phosphorylation is vital for controlling repair pathways, preventing chromosome breaks and rearrangements.

Area of Science:

  • Cellular biology
  • Molecular genetics
  • DNA repair mechanisms

Background:

  • ATM (Ataxia-telangiectasia mutated) is a key kinase involved in DNA damage response.
  • Rad9 is a checkpoint clamp protein essential for cell cycle control.
  • ATM-dependent phosphorylation of Rad9 at Ser272 was previously identified but its function remained unclear.

Purpose of the Study:

  • To elucidate the physiological function of ATM-dependent Rad9 phosphorylation at Ser272.
  • To investigate the role of Rad9(Ser272) phosphorylation in DNA repair and genomic stability.

Main Methods:

  • Utilized cell-based assays to study ATM-Rad9 interactions and phosphorylation.
  • Employed genetic mutations to assess the impact of Rad9(Ser272) phosphorylation on DNA repair.
  • Investigated the requirement of the MRN complex in ATM-mediated Rad9 phosphorylation.

Main Results:

  • ATM-dependent Rad9(Ser272) phosphorylation requires the MRN complex.
  • Cells lacking functional Rad9(Ser272) phosphorylation accumulate chromosome breaks.
  • Mutant cells exhibit increased gross chromosomal rearrangements, indicating genomic instability.

Conclusions:

  • ATM-dependent Rad9(Ser272) phosphorylation plays a critical role in controlling DNA repair pathways.
  • This phosphorylation is essential for maintaining genomic integrity during both normal cell cycling and in response to DNA damage.
  • Findings reveal a novel function for ATM in regulating repair pathways through Rad9 phosphorylation.

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