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Updated: Jul 5, 2025
06:59
Using Next Generation Sequencing to Identify Mutations Associated with Repair of a CAS9-induced Double Strand Break Near the CD4 Promoter
Published on: March 31, 2022
2.4K
Microsatellite break-induced replication generates highly mutagenized extrachromosomal circular DNAs.
Biorxiv : the Preprint Server for Biology
|January 23, 2024
Summary
Unstable microsatellites form extrachromosomal circular DNAs (eccDNAs) that are highly mutagenized. These eccDNAs can lead to genomic instability and homologous recombination deficiency (HRD).
Area of Science:
- Genetics
- Molecular Biology
- Genomics
Background:
- Extrachromosomal circular DNAs (eccDNAs) are found in eukaryotes and implicated in cancer.
- Unstable microsatellites can form non-B DNA structures, potentially influencing genome dynamics.
Approach:
- Investigated eccDNA formation from unstable microsatellites integrated at an ectopic site in human cells.
- Analyzed eccDNA mutagenesis, template switching, and the role of DNA repair proteins (Rad51, POLη).
Key Points:
- Microsatellite-prone sequences generate replication-dependent eccDNAs.
- These eccDNAs exhibit high mutation rates, including template switching to chromosomal sites.
- Mutations extend beyond microsatellites, causing genomic instability and potential homologous recombination deficiency (HRD).
Conclusions:
- Microsatellite-induced DNA breaks and asynchronous capture model explain eccDNA generation and mutagenesis.
- EccDNA formation and subsequent mutations contribute to genomic instability and HRD scars.
- Specific DNA repair pathways influence eccDNA mutagenic profiles.
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