Related Experiment Videos
Double-strand DNA break formation mediated by flap endonuclease-1
Stephane Vispé1, Erick L Y Ho, Tetsu M C Yung
1Laboratory of DNA Repair, Health and Environment Unit, Laval University Medical Center, CHUQ, Faculty of Medicine, Laval University, 2705 Boulevard Laurier, Sainte-Foy, Québec G1V 4G2, Canada.
The Journal of Biological Chemistry
|July 2, 2003
Summary
Flap endonuclease-1 (FEN-1) enzyme causes double-strand DNA breaks (DSBs) during DNA repair. Increasing FEN-1 levels in cells led to more DSBs after radiation exposure, suggesting FEN-1 is a DSB formation factor.
Area of Science:
- Molecular Biology
- DNA Repair Mechanisms
- Enzymology
Background:
- Double-strand DNA breaks (DSBs) are critical DNA lesions induced by ionizing radiation.
- Previous research suggested DNA polymerase delta/epsilon involvement in DSB formation from specific DNA damages.
- A cell-free assay demonstrated enzymatic conversion of opposite DNA strand damages into DSBs.
Purpose of the Study:
- To investigate the enzymatic factors responsible for double-strand DNA break formation.
- To test the proposed model involving DNA polymerase delta/epsilon collision.
- To identify alternative enzymes involved in DSB generation during DNA repair.
Main Methods:
- Utilized a cell-free assay to study double-strand DNA break formation.
- Enzymatic assays to identify specific enzymes involved in DNA damage processing.
- Cell transfection experiments to alter flap endonuclease-1 (FEN-1) levels.
- Gamma-ray irradiation of cells to assess DSB induction.
Main Results:
- Flap endonuclease-1 (FEN-1), not DNA polymerase delta/epsilon, was identified as the enzyme responsible for DSB formation in the assay.
- Increased FEN-1 expression in cells resulted in a higher number of DSBs following gamma-ray irradiation.
- FEN-1 activity appears to directly contribute to the generation of DSBs.
Conclusions:
- FEN-1 functions as a key factor in the formation of double-strand DNA breaks.
- DSBs may arise as unintended by-products of FEN-1's essential roles in DNA repair and replication.
- This finding implicates FEN-1 in the cellular response to DNA damage and radiation exposure.