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A polycomb group protein, PHF1, is involved in the response to DNA double-strand breaks in human cell

Zehui Hong1, Jie Jiang, Li Lan

  • 1Department of Molecular Genetics, Institute of Development, Aging and Cancer, Tohoku University, Seiryomachi 4-1, Aobaku, Sendai 980-8575, Japan.

Nucleic Acids Research
|April 4, 2008
PubMed

Insights

Polycomb group protein PHF1 is recruited to DNA double-strand breaks (DSBs) and promotes their repair via nonhomologous end-joining, revealing a new role in genome maintenance.

Area of Science:

  • Epigenetics and Molecular Biology
  • DNA Repair Mechanisms
  • Cellular Stress Response

Background:

  • DNA double-strand breaks (DSBs) are highly toxic DNA lesions repaired by homologous recombination or nonhomologous end-joining (NHEJ).
  • Polycomb group (PcG) proteins are epigenetic regulators crucial for gene silencing and stem cell maintenance.
  • The precise roles of many proteins in DSB repair pathways remain incompletely understood.

Purpose of the Study:

  • To identify proteins involved in DNA damage response pathways.
  • To investigate the function of PHF1, a Polycomb group protein, in the context of DNA double-strand breaks.
  • To elucidate the role of PHF1 in DNA repair mechanisms.

Main Methods:

  • Laser micro-irradiation to induce localized DNA double-strand breaks.
  • Screening of proteins recruited to sites of DNA damage.
  • Ku70/Ku80 dependency assays and knockdown experiments (e.g., in HeLa cells).
  • Analysis of X-ray sensitivity and homologous recombination frequency.
  • Co-immunoprecipitation assays to identify protein-protein interactions.

Main Results:

  • PHF1 is rapidly recruited to laser-induced DSBs in a Ku70/Ku80-dependent manner.
  • Knockdown of PHF1 results in increased sensitivity to X-ray radiation and a higher frequency of homologous recombination.
  • PHF1 physically interacts with Ku70/Ku80, suggesting a role in promoting NHEJ.
  • PHF1 also interacts with other DNA damage response proteins, including RAD50, SMC1, DHX9, and p53.

Conclusions:

  • PHF1 plays a significant role in genome maintenance beyond its established function in Polycomb group complexes.
  • PHF1 is a novel component of the nonhomologous end-joining pathway, facilitating the repair of DNA double-strand breaks.
  • These findings highlight the involvement of epigenetic modifiers in crucial cellular processes like DNA repair.

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