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Quantification of γH2AX Foci in Response to Ionising Radiation
06:53

Quantification of γH2AX Foci in Response to Ionising Radiation

Published on: April 6, 2010

Tissue-specific DNA-PK-dependent H2AX phosphorylation and gamma-H2AX elimination after X-irradiation in vivo

Manabu Koike1, Jun Sugasawa, Mariko Yasuda

  • 1DNA Repair Gene Research, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.

Biochemical and Biophysical Research Communications
|August 30, 2008
PubMed

Insights

The study reveals that DNA-PK-dependent elimination of gamma-H2AX occurs in mouse tissues after X-irradiation, but its phosphorylation is tissue-specific. This highlights a complex, localized regulation of DNA repair markers in vivo.

Area of Science:

  • Molecular Biology
  • Cellular Biology
  • Biochemistry

Background:

  • Histone H2AX phosphorylation at Ser139 (gamma-H2AX) is a rapid response to DNA double-strand breaks.
  • ATM kinase and DNA-PK are known to phosphorylate H2AX in vitro, but in vivo regulation remains unclear.

Purpose of the Study:

  • To investigate the in vivo regulation of gamma-H2AX levels following DNA damage.
  • To determine the roles of ATM and DNA-PK in gamma-H2AX phosphorylation and elimination in different mouse tissues.

Main Methods:

  • X-irradiation of mice (wild-type, ATM knockout, DNA-PK deficient).
  • Detection of H2AX phosphorylation (gamma-H2AX) and its elimination in mouse skin, liver, kidney, and spleen.
  • Comparative analysis of gamma-H2AX dynamics in different genetic backgrounds.

Main Results:

  • Gamma-H2AX phosphorylation and elimination were observed in mouse skin post-X-irradiation.
  • Increased gamma-H2AX levels were found in ATM or DNA-PK deficient mice after irradiation.
  • Slower elimination of gamma-H2AX in DNA-PK deficient mice suggests a DNA-PK-dependent elimination pathway.
  • DNA-PK-dependent elimination was tissue-specific, observed in liver, kidney, and spleen, while DNA-PK-dependent phosphorylation was only detected in the spleen.

Conclusions:

  • The regulatory mechanism controlling gamma-H2AX levels is tissue-specific.
  • DNA-PK plays a role in the elimination of gamma-H2AX in various tissues, but not necessarily in its initial phosphorylation.
  • These findings provide insights into the complex in vivo management of DNA damage response markers.

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