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Updated: Jul 4, 2026
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Analysis of Nonhomologous End Joining and Homologous Recombination Efficiency in HEK-293T Cells Using GFP-Based Reporter Systems
Published on: February 2, 2024
Cell sorting analysis of cell cycle-dependent X-ray sensitivity in end joining-deficient human cells
Kuniyoshi Iwabuchi1, Mitsumasa Hashimoto, Tadashi Matsui
1Department of Biochemistry, Kanazawa Medical University, 1-1 Daigaku, Uchinada, Kahoku-gun, Ishikawa 920-0293, Japan. kuni-kmu@kanazawa-med.ac.jp
Biochemical and Biophysical Research Communications
|June 10, 2008
Summary
This study demonstrates a novel, less toxic cell sorting method to isolate G1-phase cells for DNA double-strand break (DSB) repair studies. This technique accurately reflects non-homologous end joining (NHEJ) activity in various cell lines.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Non-homologous end joining (NHEJ) is a critical DNA repair pathway for double-strand breaks (DSBs), particularly in the G1 cell cycle phase.
- Assessing DSB repair activity across different cell cycle phases is essential for understanding cellular responses to DNA damage.
Purpose of the Study:
- To develop and validate a simpler, less toxic method for cell cycle fractionation to study DNA repair.
- To evaluate the DSB repair activity, specifically NHEJ, in G1-phase cells using size-based cell sorting.
Main Methods:
- Utilized flow cytometry for size-based fractionation of G1- and S/G2-phase cells from NHEJ-deficient DT40 and Nalm-6 cell lines.
- Employed colony formation assays to assess X-ray sensitivity and thus DSB repair capacity.
- Quantified DNA damage using gamma-H2AX foci formation in sorted versus chemically synchronized cells.
Main Results:
- Size-based cell sorting successfully enriched G1-phase cells, and their X-ray sensitivity correlated with DSB repair activity.
- NHEJ factor-deficient cell lines showed distinct DSB repair capacities in the sorted G1 populations.
- Sorted cells exhibited reduced DNA damage compared to chemically synchronized cells, indicating a gentler fractionation process.
Conclusions:
- Size-based flow cytometry is a viable, non-toxic method for isolating G1-phase cells for DNA repair studies.
- This technique offers a simpler alternative to chemical synchronization, applicable to diverse cell types, including those resistant to standard synchronization methods.
- The findings provide a valuable tool for investigating cell cycle-dependent DNA repair mechanisms like NHEJ.
