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Updated: Feb 22, 2026
Quantification of γH2AX Foci in Response to Ionising Radiation
Published on: April 6, 2010
Genome Instability and γH2AX
Anastasios Georgoulis1, Constantinos E Vorgias2, George P Chrousos3
1Department of Biochemistry & Molecular Biology, Faculty of Biology, University of Athens, Athens 15784, Greece. tgeorgoulis@med.uoa.gr.
Abstract:
γH2AX has emerged in the last 20 years as a central player in the DDR (DNA damage response), with specificity for DSBs (double-strand breaks). Upon the generation of DSBs, γ-phosphorylation extends along megabase-long domains in chromatin, both sides of the damage. The significance of this mechanism is of great importance; it depicts a biological amplification mechanism where one DSB induces the γ-phosphorylation of thousands of H2AX molecules along megabaselong domains of chromatin, that are adjusted to the sites of DSBs. A sequential recruitment of signal transduction factors that interact to each other and become activated to further amplify the signal that will travel to the cytoplasm take place on the γ-phosphorylated chromatin. γ-phosphorylation is an early event in the DSB damage response, induced in all phases of the cell cycle, and participates in both DSB repair pathways, the HR (homologous recombination) and NHEJ (non-homologous end joining). Today, numerous studies support the notion that γH2AX functions as a guardian of the genome by preventing misrepaired DSB that increase the mutation load of the cells and may further lead to genome instability and carcinogenesis.
Insights
Gamma-H2AX (γH2AX) is crucial for the DNA damage response (DDR), specifically marking DNA double-strand breaks (DSBs). This protein amplifies the damage signal, aiding in repair and preventing genome instability.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Histone H2AX phosphorylation, forming γH2AX, is a key marker for DNA double-strand breaks (DSBs).
- γH2AX forms large domains around DSBs, acting as a platform for DNA damage response (DDR) signaling.
- This phosphorylation is an early, cell-cycle-independent event crucial for DSB repair.
Purpose of the Study:
- To elucidate the role of γH2AX in the DNA damage response (DDR).
- To highlight γH2AX's function in amplifying the DSB signal and recruiting repair factors.
- To emphasize γH2AX's role in maintaining genome stability and preventing carcinogenesis.
Main Methods:
- The abstract does not specify methods but discusses established knowledge and biological mechanisms.
- Focuses on the molecular events following DSB induction and the role of γH2AX.
- References the involvement of signal transduction factors and repair pathways (HR, NHEJ).
Main Results:
- γH2AX formation is a rapid, amplified response to DSBs, covering megabase-long chromatin domains.
- γH2AX recruits multiple signal transduction factors, amplifying the damage signal.
- γH2AX is essential for both homologous recombination (HR) and non-homologous end joining (NHEJ) repair pathways.
Conclusions:
- γH2AX acts as a critical 'guardian of the genome'.
- It prevents misrepaired DSBs, thereby reducing mutation load and preventing genome instability.
- γH2AX plays a vital role in suppressing carcinogenesis by maintaining genomic integrity.
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