GO:2000780 negative regulation of double-strand break repair: Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:2000780 describes any biological process that stops, prevents or reduces the frequency, rate or extent of double-strand break (DSB) repair.
• Negative regulation of DSB repair is essential for pathway choice between homologous recombination (HR) and non-homologous end joining (NHEJ).
• Key negative regulators include HDAC6, RNF168, 53BP1, TIRR, DTX3L, FIGNL1-FIRRM, and COP1-ADA2b.
• Deregulation of this process drives cancer radioresistance, chemoresistance, and genomic instability.
• CRISPR knockout, point mutation, knock-in, and overexpression models are critical to dissect negative regulation of DSB repair.
• Understanding GO:2000780 informs development of radiosensitizers and PARP inhibitor combination therapies.
Description
Double-strand breaks (DSBs) are the most cytotoxic DNA lesions, and their repair is tightly controlled to preserve genome integrity. The Gene Ontology term GO:2000780, negative regulation of double-strand break repair, captures any process that stops, prevents or reduces the frequency, rate or extent of DSB repair. This regulatory layer is critical because unrestrained or misdirected repair can lead to mutations, chromosomal rearrangements, and cell death. Researchers study GO:2000780 to understand how cells balance repair fidelity, how cancer cells evade therapy, and how to manipulate repair for therapeutic benefit. The term encompasses diverse molecular mechanisms, from chromatin modification and ubiquitination to protein degradation and meiotic recombination control.
negative regulation of double-strand break repair At A Glance
| GO ID | GO:2000780 |
|---|---|
| GO term | negative regulation of double-strand break repair |
| Ontology | biological_process |
| Synonym | none |
| Major function | Stops, prevents or reduces the frequency, rate or extent of double-strand break repair |
| Key regulators | HDAC6, RNF168, 53BP1, TIRR, DTX3L, FIGNL1-FIRRM, COP1-ADA2b |
| Pathway context | DSB repair pathway choice (HR vs NHEJ) |
| Disease relevance | Cancer radioresistance, chemoresistance, genomic instability |
| Research methods | CRISPR KO, point mutation, knock-in, overexpression, library screening |
What Is GO:2000780?
GO:2000780 is a biological process defined as any process that stops, prevents or reduces the frequency, rate or extent of double-strand break repair. In practice, this includes inhibition of repair factor recruitment, active removal or degradation of repair proteins, chromatin remodeling that blocks repair, and cell-cycle-dependent suppression of repair pathways. It does not refer to a single gene or protein but to a regulatory outcome that can be achieved through multiple mechanisms.
Why Is negative regulation of double-strand break repair Important in Cell Biology?
Negative regulation of DSB repair is central to genome stability and cell survival decisions. It determines whether a cell repairs breaks accurately via HR or error-prone NHEJ, influencing mutation load and therapy response. In cancer, upregulation of negative regulators can cause resistance to DNA-damaging agents, while loss of negative regulation can lead to hyper-recombination and genomic instability. In meiosis, precise negative regulation ensures proper recombination and prevents ectopic RAD51/DMC1 loading. Thus, GO:2000780 is a key node for understanding DNA repair, cancer biology, and reproductive genetics.
• Controls DSB repair pathway choice between HR and NHEJ.
• Prevents excessive or inappropriate recombination during meiosis.
• Mediates resistance to radiotherapy and PARP inhibitors in cancer.
• Regulates chromatin ubiquitination and repair factor recruitment.
• Influences cell cycle checkpoints and apoptosis.
• Plays a role in plant light-regulated DNA repair.
• Provides targets for radiosensitizers and chemosensitizers.
• Links RNA metabolism to DSB repair regulation.
• Involved in acetylation-dependent control of 53BP1 function.
• Key for understanding genomic instability in cancer and aging.
What Happens During negative regulation of double-strand break repair?
Initiation of negative regulation by chromatin modification
In simple terms: The cell first marks the broken DNA area with chemical tags that can either recruit or block repair proteins.
Negative regulation of DSB repair often begins with chromatin modifications. For example, the HDAC6-RNF168 axis regulates H2A/H2A.X ubiquitination to enable DSB repair, and its disruption can inhibit repair. Acetylation of 53BP1 dictates the DSB repair pathway, and deacetylation can reduce its repair-promoting function. These modifications act as molecular switches that can suppress repair factor recruitment.
Active removal or degradation of repair proteins
In simple terms: Some proteins that help repair breaks are actively shipped out of the nucleus or destroyed to stop repair.
DTX3L-mediated TIRR nuclear export and degradation regulates DNA repair pathway choice and PARP inhibitor sensitivity. This exemplifies how negative regulation can occur through targeted protein degradation, reducing the availability of repair-promoting factors. Similarly, FIGNL1-FIRRM prevents DNA damage-independent RAD51 and DMC1 loading, acting as a negative regulator of recombination.
RNA and RNA-related proteins in repair regulation
In simple terms: RNA molecules and RNA-binding proteins can also put the brakes on double-strand break repair.
The role of RNA and RNA-related proteins in the regulation of DNA double strand break repair pathway choice highlights that non-coding RNAs and RNA-processing factors can negatively regulate repair. These factors can influence the recruitment of repair proteins or modulate chromatin state.
Environmental and developmental control of negative regulation
In simple terms: External signals like light or developmental cues can turn down double-strand break repair.
The COP1-ADA2b module mediates light regulation of DNA double-strand break repair in Arabidopsis, demonstrating that negative regulation can be controlled by environmental signals. In meiosis, eukaryotic RecA recombinases and their modulators ensure proper recombination and prevent inappropriate repair.
Pharmacological interference with repair
In simple terms: Drugs can mimic negative regulation by blocking repair proteins, making cancer cells more sensitive to DNA damage.
Fisetin induces DNA double-strand breaks and interferes with the repair of radiation-induced damage to radiosensitize triple negative breast cancer cells. This shows that small molecules can act as negative regulators of DSB repair, enhancing the efficacy of radiotherapy.
Key Genes Involved in GO:2000780 negative regulation of double-strand break repair
The following genes and proteins are experimentally validated participants in negative regulation of double-strand break repair, as supported by the cited literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| HDAC6 | Regulates H2A/H2A.X ubiquitination via RNF168 axis to enable DSB repair; its inhibition can negatively regulate repair | Target for modulating DSB repair and chromatin ubiquitination |
| RNF168 | E3 ubiquitin ligase in HDAC6-RNF168 axis; mediates H2A/H2A.X ubiquitination | Key node in DSB repair regulation |
| 53BP1 | Acetylation dictates DSB repair pathway; deacetylation reduces its repair function | Critical for pathway choice and negative regulation |
| TIRR | DTX3L-mediated nuclear export and degradation regulates repair pathway choice | Modulates PARP inhibitor sensitivity |
| DTX3L | E3 ligase that mediates TIRR nuclear export and degradation | Regulates DSB repair and drug response |
| FIGNL1 | Forms complex with FIRRM; prevents DNA damage-independent RAD51 and DMC1 loading | Essential for meiotic recombination control |
| FIRRM | Partners with FIGNL1 to prevent inappropriate RAD51/DMC1 loading | Meiotic recombination regulator |
| COP1 | Part of COP1-ADA2b module mediating light regulation of DSB repair in Arabidopsis | Plant DSB repair regulation |
| ADA2b | Part of COP1-ADA2b module in light-regulated DSB repair | Plant DSB repair regulation |
| RAD51 | RecA recombinase; its loading is negatively regulated by FIGNL1-FIRRM | Central to HR; target of negative regulation |
| DMC1 | Meiotic recombinase; negatively regulated by FIGNL1-FIRRM | Meiosis-specific recombination |
| RNA-related proteins | Modulate DSB repair pathway choice | Emerging regulators |
| Fisetin (chemical) | Induces DSBs and interferes with repair, radiosensitizing TNBC cells | Pharmacological negative regulator |
| PARP inhibitors | Sensitivity modulated by TIRR/DTX3L axis | Therapeutic context |
| Eukaryotic RecA recombinases | Modulated during plant meiosis | Meiotic recombination |
| Modulators of RecA recombinases | Regulate recombination in plant meiosis | Plant reproductive biology |
How Is negative regulation of double-strand break repair Regulated?
Negative regulation of DSB repair is itself regulated at multiple levels. The HDAC6-RNF168 axis controls H2A/H2A.X ubiquitination, and its activity can be modulated by HDAC inhibitors. Acetylation of 53BP1 dictates repair pathway choice, linking acetyltransferase and deacetylase activities to negative regulation. DTX3L-mediated TIRR degradation is a regulated process that influences PARP inhibitor sensitivity. In plants, the COP1-ADA2b module mediates light regulation of DSB repair, showing environmental control. Additionally, RNA-related proteins can modulate pathway choice, indicating post-transcriptional regulation.
negative regulation of double-strand break repair and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| HDAC6 | Cancer radioresistance, chromatin regulation | Knockout or overexpression in cancer cell lines |
| 53BP1 | Genomic instability, cancer | Point mutation of acetylation sites |
| TIRR | PARP inhibitor sensitivity, cancer | Knockout and rescue with degradation-resistant mutant |
| FIGNL1 | Meiotic defects, infertility | Knockout mouse models |
| DTX3L | Cancer therapy response | Knockout in cancer cells |
Cancer radioresistance and chemoresistance
Negative regulation of DSB repair can promote resistance to DNA-damaging therapies. Fisetin interferes with repair of radiation-induced damage to radiosensitize triple negative breast cancer cells, indicating that pharmacological inhibition of repair can overcome resistance. DTX3L-mediated TIRR degradation regulates PARP inhibitor sensitivity, linking negative regulation to targeted therapy response. HDAC6-RNF168 axis and 53BP1 acetylation also influence repair capacity and may affect therapy outcomes.
Genomic instability and tumorigenesis
Loss of proper negative regulation can lead to hyper-recombination or inappropriate repair, causing genomic instability. 53BP1 acetylation status dictates pathway choice, and its dysregulation can shift repair toward error-prone NHEJ, promoting mutations. TIRR and DTX3L dysregulation may also contribute to genomic instability.
Meiotic defects and infertility
FIGNL1-FIRRM is essential for meiotic recombination and prevents DNA damage-independent RAD51 and DMC1 loading. Disruption of this negative regulation can cause meiotic defects and potentially infertility. Eukaryotic RecA recombinases and their modulators are critical for proper meiosis in plants, with implications for reproductive biology.
Plant development and environmental stress
The COP1-ADA2b module mediates light regulation of DSB repair in Arabidopsis, linking negative regulation to plant development and stress responses. This highlights the evolutionary conservation of DSB repair regulation.
From negative regulation of double-strand break repair-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of HDAC6 affect DSB repair efficiency? | HDAC6 knockout cell line |
| How does 53BP1 acetylation regulate pathway choice? | Point mutation of 53BP1 acetylation sites |
| Can TIRR degradation be blocked to enhance PARP inhibitor sensitivity? | Knock-in of degradation-resistant TIRR |
| What is the role of FIGNL1-FIRRM in meiosis? | FIGNL1 knockout mouse |
| Does overexpression of DTX3L reduce repair? | DTX3L overexpression cell line |
| How does light regulate DSB repair in plants? | COP1 or ADA2b mutant Arabidopsis |
How to Study the negative regulation of double-strand break repair Process
| Method | What It Measures | Typical Application |
|---|---|---|
| CRISPR knockout screen | Loss-of-function effects on DSB repair | Identify negative regulators |
| Point mutation knock-in | Effect of specific amino acid changes | Dissect acetylation sites in 53BP1 |
| Overexpression | Gain-of-function effects | Test DTX3L-mediated TIRR degradation |
| Immunofluorescence | Repair foci formation (e.g., 53BP1, RAD51) | Quantify repair kinetics |
| Comet assay | DSB levels and repair capacity | Measure negative regulation of repair |
| PARP inhibitor sensitivity assay | Cell survival with DNA damage | Link TIRR/DTX3L to therapy response |
| Meiotic recombination assays | RAD51/DMC1 loading | Study FIGNL1-FIRRM function |
| Plant genetic analysis | DSB repair in light conditions | COP1-ADA2b module |
CRISPR knockout screens
Genome-wide CRISPR knockout screens can identify negative regulators of DSB repair by selecting for cells that survive DNA-damaging agents. Such screens have revealed roles for HDAC6, RNF168, and DTX3L.
Point mutation and knock-in models
Point mutations in acetylation sites of 53BP1 have been used to dissect how acetylation dictates DSB repair pathway choice. Knock-in of degradation-resistant TIRR can test the importance of DTX3L-mediated degradation.
Overexpression and rescue experiments
Overexpression of negative regulators such as DTX3L can reduce repair efficiency and sensitize cells to PARP inhibitors. Conversely, overexpression of repair factors can overcome negative regulation.
Imaging and reporter assays
Live-cell imaging of GFP-tagged repair proteins (e.g., 53BP1, RAD51) and DSB reporter assays (e.g., I-SceI) quantify repair kinetics and pathway choice. These methods are essential to study negative regulation in real time.
How CRISPR Can Be Used to Study GO:2000780 negative regulation of double-strand break repair
Knockout
CRISPR knockout of negative regulators such as HDAC6, DTX3L, or FIGNL1 can reveal their essential roles in DSB repair and meiosis. For example, HDAC6 knockout impairs H2A/H2A.X ubiquitination and DSB repair.
Point Mutation
Point mutations in acetylation sites of 53BP1 (e.g., K-to-R or K-to-Q) can be introduced to test how acetylation dictates repair pathway choice. Such models are crucial for understanding post-translational control of negative regulation.
Knock-in
Knock-in of degradation-resistant TIRR mutants can block DTX3L-mediated degradation and test its impact on PARP inhibitor sensitivity. Tagged knock-in of repair proteins (e.g., GFP-53BP1) enables live-cell imaging.
Overexpression
Overexpression of DTX3L or other negative regulators can reduce DSB repair and sensitize cancer cells to DNA-damaging agents. Overexpression of FIGNL1-FIRRM can prevent inappropriate RAD51 loading.
How EDITGENE Supports negative regulation of double-strand break repair Research
Researchers studying negative regulation of double-strand break repair-related genes often need to determine whether a candidate gene is causally involved in suppressing repair, and to dissect the precise molecular mechanism. EDITGENE provides end-to-end CRISPR services to generate knockout, point-mutation, knock-in, and overexpression cell models, as well as custom library screening and bioinformatics support.
Contact EDITGENE today to design your custom CRISPR model for negative regulation of double-strand break repair research.
Frequently Asked Questions About negative regulation of double-strand break repair
What is GO:2000780?
GO:2000780 is the Gene Ontology term for negative regulation of double-strand break repair, defined as any process that stops, prevents or reduces the frequency, rate or extent of double-strand break repair.
What genes are involved in negative regulation of double-strand break repair?
Key genes include HDAC6, RNF168, 53BP1, TIRR, DTX3L, FIGNL1, FIRRM, COP1, and ADA2b, as supported by experimental studies.
How does negative regulation of DSB repair affect cancer therapy?
It can promote radioresistance and chemoresistance; inhibiting negative regulators can sensitize cancer cells to DNA-damaging agents and PARP inhibitors.
What is the role of 53BP1 acetylation in DSB repair?
Acetylation of 53BP1 dictates the DSB repair pathway choice, and its deacetylation can reduce repair-promoting function.
How does DTX3L regulate DSB repair?
DTX3L mediates TIRR nuclear export and degradation, which regulates DNA repair pathway choice and PARP inhibitor sensitivity.
What is the function of FIGNL1-FIRRM in meiosis?
FIGNL1-FIRRM is essential for meiotic recombination and prevents DNA damage-independent RAD51 and DMC1 loading.
Can CRISPR be used to study negative regulation of DSB repair?
Yes, CRISPR knockout, point mutation, knock-in, and overexpression models are widely used to dissect this process.
What methods are used to measure negative regulation of DSB repair?
Common methods include CRISPR screens, immunofluorescence for repair foci, comet assays, and PARP inhibitor sensitivity assays.
Is negative regulation of DSB repair conserved in plants?
Yes, the COP1-ADA2b module mediates light regulation of DSB repair in Arabidopsis, showing conservation.
What are the therapeutic implications of targeting negative regulators of DSB repair?
Targeting these regulators can overcome therapy resistance and enhance the efficacy of radiotherapy and PARP inhibitors.
Conclusion
GO:2000780, negative regulation of double-strand break repair, is a critical biological process that ensures genome stability by controlling when and how DSBs are repaired. Its dysregulation contributes to cancer progression, therapy resistance, and meiotic defects. Understanding the molecular players such as HDAC6, 53BP1, TIRR, DTX3L, and FIGNL1-FIRRM provides opportunities for therapeutic intervention. CRISPR-based models and screening approaches are indispensable for dissecting this regulatory network and translating findings into clinical applications.
References
- 1. Qiu L et al.. 2023. The HDAC6-RNF168 axis regulates H2A/H2A.X ubiquitination to enable double-strand break repair.. Nucleic Acids Res 51(17):9166-9182 PMID: 37503842
- 2. Jimeno S et al.. 2019. The role of RNA and RNA-related proteins in the regulation of DNA double strand break repair pathway choice.. DNA Repair (Amst) 81:102662 PMID: 31303544
- 3. Chen L et al.. 2026. The COP1-ADA2b module mediates light regulation of DNA double-strand break repair in Arabidopsis.. Nat Commun 17(1) PMID: 41820379
- 4. Zainu A et al.. 2024. FIGNL1-FIRRM is essential for meiotic recombination and prevents DNA damage-independent RAD51 and DMC1 loading.. Nat Commun 15(1):7015 PMID: 39147779
- 5. Guo X et al.. 2018. Acetylation of 53BP1 dictates the DNA double strand break repair pathway.. Nucleic Acids Res 46(2):689-703 PMID: 29190394
- 6. Khozooei S et al.. 2022. Fisetin induces DNA double-strand break and interferes with the repair of radiation-induced damage to radiosensitize triple negative breast cancer cells.. J Exp Clin Cancer Res 41(1):256 PMID: 35989353
- 7. Ye Q et al.. 2024. DTX3L-mediated TIRR nuclear export and degradation regulates DNA repair pathway choice and PARP inhibitor sensitivity.. Nat Commun 15(1):10596 PMID: 39632881
- 8. Emmenecker C et al.. 2023. Repair of DNA double-strand breaks in plant meiosis: role of eukaryotic RecA recombinases and their modulators.. Plant Reprod 36(1):17-41 PMID: 35641832
