Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Homologous Recombination

Homologous Recombination

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...

Homologous Recombination

Homologous Recombination

Nucleotide Excision Repair

Nucleotide Excision Repair

Nucleotide Excision Repair

Nucleotide Excision Repair

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...

Nucleotide Excision Repair

Nucleotide Excision Repair

Mismatch Repair

Mismatch Repair

Organisms are capable of detecting and fixing nucleotide mismatches that occur during DNA replication. This sophisticated process requires identifying the new strand and replacing the erroneous bases with correct nucleotides. Mismatch repair is coordinated by many proteins in both prokaryotes and eukaryotes.
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...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Functional genomic screens uncover FERMT2 as a critical regulator of YAP/TAZ-driven tumorigenicity.

Cell death and differentiation·2026

Same author

Corrigendum to "iNKT cell-neutrophil crosstalk promotes colorectal cancer pathogenesis" [Mucosal Immunol. 16(3) (2023) 326-340.

Mucosal immunology·2025

Same author

Machine Learning for Structural Health Monitoring of Aerospace Structures: A Review.

Sensors (Basel, Switzerland)·2025

Same author

Energy Evaluation and Passive Damage Detection for Structural Health Monitoring in Aerospace Structures Using Machine Learning Models.

Sensors (Basel, Switzerland)·2025

Same author

TRF1 relies on fork reversal to prevent fragility at human telomeres.

Nature communications·2025

Same author

Direct RNA nanopore sequencing reveals rapid RNA modification changes following glucose stimulation of human pancreatic beta-cell lines.

bioRxiv : the preprint server for biology·2025

Same journal

Thyroid cancer-associated EZH1 Q571R mutation drives chromatin compaction and H3K27me3 invasion into active chromatin.

Molecular cell·2026

Same journal

Genome-wide rotational and translational phasing of nucleosomes with human transcription factors.

Molecular cell·2026

Same journal

Spliceosomal proofreading factors safeguard 3' splice-site fidelity and prevent proteotoxicity and inflammation.

Molecular cell·2026

Same journal

Cytosolic EZH2-IMPDH2 complexes regulate melanoma progression and metastasis via GTP.

Molecular cell·2026

Same journal

A bacterial reverse transcriptase: Protein-templated DNA synthesis fuels antiviral immunity.

Molecular cell·2026

Same journal

Tweezing apart ribosome heterogeneity.

Molecular cell·2026

See all related articles

Search research articles

Related Experiment Video

Updated: May 3, 2026

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

Published on: September 11, 2022

Damage-induced i-loops generate eccDNA from repetitive elements.

Elia Zanella¹, Michele Giannattasio², Sara Bisi³

¹IFOM ETS - The AIRC Institute of Molecular Oncology, Via Adamello 16, 20139 Milano, Italy.

|May 1, 2026

Summary

This summary is machine-generated.

A novel mechanism for extrachromosomal circular DNA (eccDNA) formation involves internal loops (i-loops) arising from single-stranded DNA breaks, distinct from DNA end joining. This process, triggered by apoptosis, sheds light on eccDNA

Keywords:

DNA damage alpha satellite apoptosis cancer centromeres ecDNA eccDNA non-allelic homologous recombination rDNA repetitive DNA retrotransposons single-stranded breaks telomeres

More Related Videos

Genome-wide Purification of Extrachromosomal Circular DNA from Eukaryotic Cells

Genome-wide Purification of Extrachromosomal Circular DNA from Eukaryotic Cells

Published on: April 4, 2016

Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage

Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage

Published on: August 21, 2021

Related Experiment Videos

Last Updated: May 3, 2026

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

Published on: September 11, 2022

Genome-wide Purification of Extrachromosomal Circular DNA from Eukaryotic Cells

Genome-wide Purification of Extrachromosomal Circular DNA from Eukaryotic Cells

Published on: April 4, 2016

Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage

Visualizing and Quantifying Endonuclease-Based Site-Specific DNA Damage

Published on: August 21, 2021

Area of Science:

Genetics
Molecular Biology
Cancer Biology

Background:

Extrachromosomal circular DNA (eccDNA) is implicated in genome instability and tumorigenesis.
Existing models of eccDNA formation primarily focus on double-stranded breaks (DSBs) and DNA end joining.
A comprehensive understanding of eccDNA biogenesis is crucial for addressing its role in disease and evolution.

Purpose of the Study:

To elucidate a novel mechanism of eccDNA formation in human cells.
To investigate the role of single-stranded DNA (ssDNA) breaks and internal loops (i-loops) in eccDNA biogenesis.
To explore the contribution of this mechanism to eccDNA formation during apoptosis and its implications for cancer biology.

Main Methods:

Utilized electron microscopy (EM) to visualize i-loops as precursors to eccDNA.
Employed rolling-circle amplification to detect eccDNA formation.
Applied Nanopore sequencing to identify repetitive elements involved in eccDNA generation during apoptosis.

Main Results:

Identified a new pathway for eccDNA formation initiated by ssDNA breaks or gaps, leading to the formation of internal loops (i-loops) at repetitive sequences like telomeres and alpha satellites.
Demonstrated that i-loops are direct precursors to eccDNA, which can be visualized by EM and detected by rolling-circle amplification.
Showed that apoptosis significantly triggers i-loop and eccDNA formation at telomeric and alpha satellite repeats, with Nanopore sequencing revealing other repetitive elements like rDNA and retrotransposons as additional sources during this process.

Conclusions:

Proposed a novel i-loop-mediated mechanism for eccDNA formation, distinct from DNA end joining, driven by ssDNA breaks or gaps.
Highlighted apoptosis as a key cellular event that activates this i-loop mechanism, leading to eccDNA generation.
Suggested that the i-loop mechanism significantly contributes to the pool of eccDNA in human cells, with broad implications for genome instability, tumor biology, and genome evolution.