Related Experiment Video
Updated: Jun 16, 2026

Analysis of Nonhomologous End Joining and Homologous Recombination Efficiency in HEK-293T Cells Using GFP-Based Reporter Systems
Published on: February 2, 2024
Microhomology-mediated end joining induces hypermutagenesis at breakpoint junctions
Supriya Sinha1, Fuyang Li1, Diana Villarreal2
1Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States of America.
Abstract:
Microhomology (MH) flanking a DNA double-strand break (DSB) drives chromosomal rearrangements but its role in mutagenesis has not yet been analyzed. Here we determined the mutation frequency of a URA3 reporter gene placed at multiple locations distal to a DSB, which is flanked by different sizes (15-, 18-, or 203-bp) of direct repeat sequences for efficient repair in budding yeast. Induction of a DSB accumulates mutations in the reporter gene situated up to 14-kb distal to the 15-bp MH, but more modestly to those carrying 18- and 203-bp or no homology. Increased mutagenesis in MH-mediated end joining (MMEJ) appears coupled to its slower repair kinetics and the extensive resection occurring at flanking DNA. Chromosomal translocations via MMEJ also elevate mutagenesis of the flanking DNA sequences 7.1 kb distal to the breakpoint junction as compared to those without MH. The results suggest that MMEJ could destabilize genomes by triggering structural alterations and increasing mutation burden.
Related Concept Videos
Fixing Double-strand Breaks
Fixing Double-strand Breaks
Homologous Recombination
Homologous Recombination
Mismatch Repair
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
Mismatch Repair

