Related Experiment Video
Updated: Jun 17, 2025
08:31
Characterizing DNA Repair Processes at Transient and Long-lasting Double-strand DNA Breaks by Immunofluorescence Microscopy
Published on: June 8, 2018
9.1K
Disparate Pathways for Extrachromosomal DNA Biogenesis and Genomic DNA Repair
John C Rose1, Julia A Belk1, Ivy Tsz-Lo Wong2,3
1Center for Personal Dynamic Regulomes, Stanford University, Stanford, California.
Cancer Discovery
|August 7, 2024
Summary
This study reveals how extrachromosomal circular DNA (ecDNA) forms efficiently through double-strand breaks using CRISPR technology. It clarifies distinct pathways for ecDNA and chromosomal scar generation, proposing a new model for excisional ecDNA formation.
Area of Science:
- Molecular Biology
- Genetics
- Cancer Research
Background:
- Extrachromosomal circular DNA (ecDNA) are prevalent in cancer cells.
- The biogenesis of ecDNA and its relationship to chromosomal alterations remain incompletely understood.
Purpose of the Study:
- To investigate the mechanisms underlying ecDNA formation using a novel CRISPR-based approach.
- To differentiate the processes of ecDNA generation and chromosomal scar formation.
Main Methods:
- Utilized a CRISPR-based system to induce and study double-strand breaks.
- Analyzed the formation of ecDNA and associated chromosomal scars.
Main Results:
- Demonstrated efficient ecDNA circularization occurring at double-strand breaks.
- Showcased distinct molecular mechanisms for ecDNA formation versus chromosomal scar repair.
- Identified nonhomologous end joining and microhomology-mediated end joining as key pathways involved.
Conclusions:
- Established a mechanistic model for excisional ecDNA formation.
- Provided new insights into the distinct pathways governing ecDNA and chromosomal scar generation.
- Highlighted the role of CRISPR technology in dissecting complex genomic events.
Related Concept Videos
02:25Overview of DNA Repair
30.9K
In order to be passed through generations, genomic DNA must be undamaged and error-free. However, every day, DNA in a cell undergoes several thousand to a million damaging events by natural causes and external factors. Ionizing radiation such as UV rays, free radicals produced during cellular respiration, and hydrolytic damage from metabolic reactions can alter the structure of DNA. Damages caused include single-base alteration, base dimerization, chain breaks, and cross-linkage.
Chemically...
Chemically...
30.9K
02:04Fixing Double-strand Breaks
12.5K
The double-stranded structure of DNA has two major advantages. First, it serves as a safe repository of genetic information where one strand serves as the back-up in case the other strand is damaged. Second, the double-helical structure can be wrapped around proteins called histones to form nucleosomes, which can then be tightly wound to form chromosomes. This way, DNA chains up to 2 inches long can be contained within microscopic structures in a cell. A double-stranded break not only damages...
12.5K
02:31Homologous Recombination
50.4K
The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
50.4K
01:38Nucleotide Excision Repair
3.5K
DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
3.5K
02:46Genome Copying Errors
4.2K
DNA replication is a well-evolved process that copies millions of base pairs with high fidelity during each cell division. Occasionally a wrong base or a long stretch of wrong bases may get added to the daughter strands. If the errors are left unchecked, cells might accumulate several mutations that might endanger their survival. Therefore, the copying errors are checked and repaired at three levels.
4.2K
01:02Long-patch Base Excision Repair
7.0K
Since the discovery of the two BER pathways, there has been a debate about how a cell chooses one pathway over the other and the factors determining this selection. Numerous in vitro experiments have pointed out multiple determinants for the sub-pathway selection. These are:
7.0K