GO:1905168 positive regulation of double-strand break repair via homologous recombination: DNA Repair Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1905168 describes any process that activates or increases the frequency, rate or extent of double-strand break repair via homologous recombination (HR).
• HR is a high-fidelity repair pathway that uses a homologous template to restore DNA at double-strand breaks, and its positive regulation determines repair pathway choice.
• Key positive regulators include RNF126, which stabilizes BRCA1 via E2F1 to promote HR, and RAD54L, a motor protein that drives HR progression.
• Loss of positive regulation causes HR deficiency (BRCAness), sensitizing tumors to PARP inhibitors and platinum agents.
• Signaling kinases such as Akt1/Akt2 and RNA-related proteins modulate HR efficiency, linking metabolism and RNA biology to repair.
• CRISPR knockout, point-mutation, knock-in and overexpression models are essential to dissect causal roles of HR regulators in cancer and other diseases.
Description
GO:1905168, positive regulation of double-strand break repair via homologous recombination, is a Gene Ontology biological process term that captures any activity that increases the frequency, rate or extent of homologous recombination (HR)-mediated repair of DNA double-strand breaks (DSBs). HR is a template-dependent, error-free repair pathway that is critical for maintaining genomic integrity during replication and after genotoxic stress. Because DSBs are among the most lethal DNA lesions, cells have evolved elaborate regulatory layers to promote HR when a sister chromatid is available, and to suppress it when it is not. Understanding the positive regulation of HR is therefore central to cancer biology, genome editing and precision medicine. At the molecular level, positive regulation of HR involves the coordinated action of sensors, transducers, chromatin remodelers and effector proteins that together commit a DSB to HR. For example, the E3 ubiquitin ligase RNF126 promotes HR by regulating E2F1-mediated BRCA1 expression, thereby increasing BRCA1 availability at damage sites. RAD54L, a Snf2-family motor protein, promotes hepatocellular carcinoma progression via the HR repair pathway, illustrating how positive regulators can also drive tumorigenesis. Conversely, depletion of Akt1 and Akt2 impairs HR-mediated repair of radiation-induced DSBs, showing that survival kinases can act as positive regulators of this process. This article synthesizes authoritative QuickGO annotation and verified PubMed literature to provide a research-grade overview of GO:1905168. We cover the definition, core mechanisms, key genes, disease links, experimental models and CRISPR-based methods used to study positive regulation of HR. The content is designed for researchers seeking to design functional experiments, interpret genomic data, or develop therapeutics targeting HR regulation.
positive regulation of double-strand break repair via homologous recombination At A Glance
| GO ID | GO:1905168 |
|---|---|
| GO term | positive regulation of double-strand break repair via homologous recombination |
| Ontology | biological_process |
| Synonym | activation of HDR; positive regulation of homology-directed repair; upregulation of HRR; activation of Rad51-dependent recombinational repair |
| Major function | Increases the frequency, rate or extent of homologous recombination-mediated repair of DNA double-strand breaks |
| Related process | double-strand break repair via homologous recombination (GO:0000724) |
| Regulatory direction | Positive (activation/upregulation) |
| Example regulators | RNF126, RAD54L, BRCA1, Akt1/Akt2, RNA-related proteins |
| Disease relevance | Cancer (breast, ovarian, hepatocellular, pancreatic), Fanconi anemia, miscarriage |
What Is GO:1905168?
GO:1905168 is defined by QuickGO as any process that activates or increases the frequency, rate or extent of double-strand break repair via homologous recombination. In other words, it is not HR itself, but the regulatory inputs that upregulate HR activity. These inputs can include transcriptional induction of HR genes, post-translational modifications of HR proteins, recruitment of repair factors to damage sites, or signaling events that bias repair pathway choice toward HR. The term is a child of positive regulation of double-strand break repair and is synonymous with activation of HDR, activation of HRR, and positive regulation of Rad51-dependent recombinational repair, among others.
Why Is positive regulation of double-strand break repair via homologous recombination Important in Cell Biology?
Positive regulation of homologous recombination is essential for genome stability, yet its dysregulation is a hallmark of cancer and other diseases. HR deficiency, often caused by loss of positive regulators such as BRCA1 or RAD54L, leads to genomic instability and hypersensitivity to PARP inhibitors and platinum drugs. Conversely, enhanced HR activity can drive resistance to these therapies, as seen in triple-negative breast cancer where SOSTDC1 promotes CHD1-mediated HR repair and olaparib resistance. In Fanconi anemia, deficient regulation of DSB repair contributes to chromosomal instability and bone marrow failure. In reproductive biology, defective HR regulation by the lnc-HZ10/Ahr loop in trophoblasts is associated with miscarriage. Thus, understanding GO:1905168 is critical for cancer therapy, genome editing efficiency, and reproductive health.
• Determines repair pathway choice between error-free HR and error-prone non-homologous end joining.
• Loss of positive regulation causes HR deficiency (BRCAness), creating therapeutic vulnerabilities to PARP inhibitors.
• Enhanced positive regulation can mediate resistance to PARP inhibitors and platinum-based chemotherapy.
• RNF126 promotes HR via E2F1-mediated BRCA1 expression, linking ubiquitin signaling to HR.
• RAD54L promotes hepatocellular carcinoma progression through the HR repair pathway.
• Akt1 and Akt2 depletion impairs HR-mediated repair of radiation-induced DSBs.
• Deficient regulation of DSB repair is observed in Fanconi anemia fibroblasts.
• Defective HR regulation by lnc-HZ10/Ahr loop in trophoblasts is associated with miscarriage.
• RNA and RNA-related proteins regulate DSB repair pathway choice, expanding the regulatory landscape.
• CRISPR screens and functional models are needed to identify and validate positive regulators of HR.
What Happens During positive regulation of double-strand break repair via homologous recombination?
DSB sensing and resection
In simple terms: The cell detects a broken DNA end and chews back one strand to create a single-stranded tail.
Positive regulation of HR begins with recognition of the DSB by sensor complexes, followed by 5'-3' end resection to generate single-stranded DNA (ssDNA). This step is a commitment point for HR and is promoted by factors that increase resection activity or recruit resection machinery. RNA-related proteins can influence this early decision, as reviewed by Jimeno et al.. In Fanconi anemia fibroblasts, deficient regulation of DSB repair suggests that sensing or resection steps may be impaired.
Rad51 filament formation and strand invasion
In simple terms: A protein called Rad51 coats the single-stranded tail and searches for a matching DNA template.
The ssDNA is bound by RPA and then replaced by Rad51 to form a nucleoprotein filament that invades the homologous template. Positive regulators enhance this step by promoting Rad51 loading or stabilizing the filament. For example, RAD54L, a motor protein, promotes HR progression after Rad51 filament formation. RNF126 increases BRCA1 expression, which in turn supports Rad51 loading.
DNA synthesis and resolution
In simple terms: The broken DNA is copied using the matching template and then sealed back together.
Following strand invasion, DNA polymerase extends the invading strand, and the resulting joint molecules are resolved to restore the original sequence. Positive regulation at this stage ensures efficient completion of HR. Depletion of Akt1 and Akt2 impairs repair of radiation-induced DSBs via HR, indicating that these kinases positively regulate steps after initial resection. In trophoblast cells, defective HR regulation by the lnc-HZ10/Ahr loop leads to miscarriage, highlighting the importance of resolution in development.
Chromatin remodeling and pathway choice
In simple terms: The cell opens up chromatin and decides whether to use HR or a faster but error-prone repair.
Chromatin remodelers such as CHD1 facilitate HR by making DNA accessible. Positive regulation of HR involves tilting the balance toward HR and away from non-homologous end joining. SOSTDC1 nuclear translocation facilitates BTIC maintenance and CHD1-mediated HR repair, promoting olaparib resistance in triple-negative breast cancer. This illustrates how chromatin-level regulation is a key component of GO:1905168.
Transcriptional and post-translational control
In simple terms: Cells can make more repair proteins or modify them to boost HR activity.
Positive regulation can occur through increased transcription of HR genes or post-translational modifications that activate HR proteins. RNF126 regulates E2F1-mediated BRCA1 expression, directly linking ubiquitin signaling to transcriptional control of HR. RNA-related proteins also modulate DSB repair pathway choice, adding an RNA layer to regulation. These mechanisms ensure that HR is upregulated when needed, such as during replication stress.
Key Genes Involved in GO:1905168 positive regulation of double-strand break repair via homologous recombination
The following genes and proteins are experimentally validated participants in the positive regulation of double-strand break repair via homologous recombination, based on the verified literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RNF126 | E3 ubiquitin ligase; promotes HR via E2F1-mediated BRCA1 expression | Links ubiquitin signaling to HR; potential target in cancers with BRCA1 dysregulation |
| RAD54L | Snf2-family motor protein; promotes HR progression | Promotes hepatocellular carcinoma progression; biomarker and therapeutic target |
| BRCA1 | Central HR factor; promotes Rad51 loading and strand invasion | Loss causes HR deficiency and PARP inhibitor sensitivity |
| CHD1 | Chromatin remodeler; facilitates HR repair | Mediates olaparib resistance in triple-negative breast cancer |
| SOSTDC1 | Nuclear translocation facilitates CHD1-mediated HR repair | Promotes tumor progression and olaparib resistance in TNBC |
| Akt1 | Survival kinase; positively regulates HR-mediated DSB repair | Depletion impairs HR; links metabolism to DNA repair |
| Akt2 | Survival kinase; positively regulates HR-mediated DSB repair | Depletion impairs HR; potential target in radioresistant tumors |
| E2F1 | Transcription factor; regulates BRCA1 expression | Mediates RNF126-dependent HR promotion |
| OFD1 | Centriolar protein; inhibition induces BRCAness | Creates therapeutic vulnerability to PARP inhibition in pancreatic cancer |
| lnc-HZ10 | Long non-coding RNA; forms loop with Ahr | Defective HR regulation in trophoblasts induces miscarriage |
| Ahr | Aryl hydrocarbon receptor; part of lnc-HZ10/Ahr loop | Regulates HR in trophoblasts; linked to miscarriage |
| FANCD2 | Fanconi anemia protein; involved in DSB repair regulation | Deficient regulation in Fanconi anemia fibroblasts |
| RPA | ssDNA-binding protein; protects resected ends | Essential for HR; regulated by RNA-related proteins |
| Rad51 | Recombinase; forms filament on ssDNA | Central effector of HR; target of positive regulation |
| RNA-related proteins | Modulate DSB repair pathway choice | Emerging regulators of HR |
How Is positive regulation of double-strand break repair via homologous recombination Regulated?
Positive regulation of HR is controlled at multiple levels. Transcriptional control includes E2F1-mediated BRCA1 expression downstream of RNF126. Post-translational modifications, such as ubiquitination by RNF126, modulate HR factor stability and activity. Signaling kinases Akt1 and Akt2 positively regulate HR-mediated repair of radiation-induced DSBs, linking growth factor signaling to DNA repair. Chromatin remodeling by CHD1 facilitates HR and is promoted by SOSTDC1 nuclear translocation. RNA and RNA-related proteins also regulate DSB repair pathway choice, adding an RNA layer to HR control. In Fanconi anemia, deficient regulation of DSB repair suggests that the Fanconi anemia pathway intersects with HR regulation. In trophoblasts, the lnc-HZ10/Ahr loop regulates HR, and its dysfunction is associated with miscarriage. Finally, inhibition of OFD1 induces BRCAness, indicating that OFD1 normally supports HR proficiency.
positive regulation of double-strand break repair via homologous recombination and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RNF126 | Cancer (BRCA1-dependent HR) | Knockout and overexpression in breast cancer cell lines |
| RAD54L | Hepatocellular carcinoma | Knockout in HCC cell lines and xenografts |
| OFD1 | Pancreatic cancer (BRCAness) | Knockout or inhibition in pancreatic cancer organoids |
| SOSTDC1 | Triple-negative breast cancer (olaparib resistance) | Knockout and knock-in in TNBC cell lines |
| lnc-HZ10/Ahr | Miscarriage (trophoblast HR defect) | Knockout in trophoblast cell models |
Cancer and HR deficiency
Positive regulation of HR is frequently dysregulated in cancer. RNF126 promotes HR via E2F1-mediated BRCA1 expression, and its overexpression may contribute to HR proficiency and therapy resistance. RAD54L promotes hepatocellular carcinoma progression through the HR repair pathway, suggesting that positive regulators can be oncogenic. In pancreatic cancer, OFD1 inhibition induces BRCAness, creating a therapeutic vulnerability to PARP inhibition. In triple-negative breast cancer, SOSTDC1 nuclear translocation facilitates CHD1-mediated HR repair, promoting tumor progression and olaparib resistance. These findings highlight that both loss and gain of positive HR regulation can drive cancer phenotypes.
Fanconi anemia and genomic instability
Fanconi anemia is a hereditary disorder characterized by chromosomal instability and bone marrow failure. Fibroblasts from Fanconi anemia patients show deficient regulation of DNA double-strand break repair, indicating that the Fanconi anemia pathway is required for proper positive regulation of HR. This link underscores the importance of HR regulation in maintaining genomic stability and preventing disease.
Reproductive disorders and miscarriage
Defective homologous recombination repair by up-regulating the lnc-HZ10/Ahr loop in human trophoblast cells induces miscarriage. This finding connects positive regulation of HR to placental development and reproductive success, suggesting that HR regulators could be biomarkers or therapeutic targets for recurrent pregnancy loss.
Radio- and chemosensitivity
Akt1 and Akt2 depletion impairs the repair of radiation-induced DNA double-strand breaks via homologous recombination, indicating that these kinases positively regulate HR and influence radiosensitivity. Targeting positive regulators of HR may therefore sensitize tumors to radiation and DNA-damaging chemotherapy.
From positive regulation of double-strand break repair via homologous recombination-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a candidate gene impair HR? | CRISPR knockout cell lines followed by HR reporter assay |
| Does a specific mutation in an HR regulator affect its function? | Point-mutation knock-in via CRISPR |
| Does a candidate gene promote HR when overexpressed? | CRISPR overexpression (e.g., CRISPRa) or lentiviral overexpression |
| Where does a protein localize during HR? | Tagged knock-in (e.g., GFP) and live-cell imaging |
| Does a gene regulate HR in vivo? | Xenograft or orthotopic models with knockout/overexpression |
| Can HR regulators be targeted to overcome PARP inhibitor resistance? | Patient-derived organoids and CRISPR screens |
How to Study the positive regulation of double-strand break repair via homologous recombination Process
| Method | What It Measures | Typical Application |
|---|---|---|
| DR-GFP HR reporter | HR efficiency | Testing candidate genes for positive regulation of HR |
| Rad51 foci immunofluorescence | HR engagement at DSBs | Assessing HR proficiency in cells and tissues |
| RNA-seq | Transcriptional changes | Identifying HR gene expression signatures |
| Proteomics | Protein abundance and modifications | Discovering post-translational regulation of HR |
| CRISPR knockout screen | Gene requirement for HR | Identifying novel positive regulators |
| CRISPR activation screen | Gene sufficiency to enhance HR | Discovering drivers of HR upregulation |
| Comet assay | DSB repair kinetics | Measuring overall repair capacity |
| PARP inhibitor sensitivity assay | HR deficiency (BRCAness) | Linking positive regulators to therapy response |
HR reporter assays
Direct repeat GFP (DR-GFP) and other chromosomal HR reporters are the gold standard to measure HR efficiency. These assays use a DSB induced by I-SceI or Cas9 and quantify GFP-positive cells as a readout of HR. They are used to test whether knockout or overexpression of a candidate gene positively regulates HR.
DNA damage and repair foci imaging
Immunofluorescence for gamma-H2AX, Rad51, and BRCA1 foci measures DSB formation and HR engagement. Co-localization of Rad51 with gamma-H2AX indicates active HR. Live-cell imaging with tagged knock-in proteins can track recruitment kinetics.
Transcriptomic and proteomic profiling
RNA-seq and proteomics can identify genes and pathways whose expression changes upon HR activation or inhibition. For example, RNF126 regulates E2F1-mediated BRCA1 expression, which can be detected by RNA-seq. Proteomics can reveal post-translational modifications on HR factors.
CRISPR screens and functional genomics
Genome-wide CRISPR knockout or activation screens coupled with HR reporters or PARP inhibitor sensitivity can identify novel positive regulators of HR. These screens are powerful for discovering genes like OFD1 whose inhibition induces BRCAness.
How CRISPR Can Be Used to Study GO:1905168 positive regulation of double-strand break repair via homologous recombination
Knockout
CRISPR knockout is used to delete candidate positive regulators of HR and assess the consequences on HR efficiency, Rad51 foci formation, and sensitivity to PARP inhibitors or radiation. For example, knockout of RAD54L impairs HR and reduces tumor progression in hepatocellular carcinoma models. Knockout of OFD1 induces BRCAness in pancreatic cancer cells.
Point Mutation
Point mutations can be introduced via CRISPR base editing or homology-directed repair to model missense variants in HR regulators. This is useful to dissect domain-specific functions, such as the ubiquitin ligase activity of RNF126 or the ATPase activity of RAD54L. Point-mutation models help distinguish catalytic from scaffolding functions.
Knock-in
Knock-in of tags (e.g., GFP, HA) or reporter cassettes allows visualization and quantification of HR regulators at endogenous levels. Tagged knock-in of Rad51 or BRCA1 enables live-cell imaging of HR dynamics. Knock-in of patient-derived mutations can model disease-associated variants.
Overexpression
CRISPR activation (CRISPRa) or lentiviral overexpression is used to test whether a candidate gene is sufficient to enhance HR. Overexpression of RNF126 increases BRCA1 expression and promotes HR. Overexpression of SOSTDC1 enhances CHD1-mediated HR and olaparib resistance in TNBC. These models are key to identifying gain-of-function mechanisms.
How EDITGENE Supports positive regulation of double-strand break repair via homologous recombination Research
Researchers studying positive regulation of double-strand break repair via homologous recombination-related genes often need to determine whether a candidate gene is causally involved in HR upregulation, and whether its loss or gain alters therapy response. EDITGENE provides a comprehensive suite of CRISPR-based services to generate precisely engineered cell models for such functional studies.
Contact EDITGENE today to design your custom CRISPR model for positive regulation of double-strand break repair via homologous recombination research.
Frequently Asked Questions About positive regulation of double-strand break repair via homologous recombination
What is GO:1905168?
GO:1905168 is the Gene Ontology term for positive regulation of double-strand break repair via homologous recombination, meaning any process that activates or increases the frequency, rate or extent of HR-mediated DSB repair.
What genes are involved in positive regulation of double-strand break repair via homologous recombination?
Key genes include RNF126, RAD54L, BRCA1, CHD1, SOSTDC1, Akt1, Akt2, E2F1, OFD1, and lnc-HZ10/Ahr, among others.
How does RNF126 regulate homologous recombination?
RNF126 promotes HR by regulating E2F1-mediated BRCA1 expression, thereby increasing BRCA1 levels and supporting HR.
What is the role of RAD54L in homologous recombination?
RAD54L is a motor protein that promotes HR progression and has been shown to drive hepatocellular carcinoma progression via the HR pathway.
How is homologous recombination regulated by Akt signaling?
Depletion of Akt1 and Akt2 impairs the repair of radiation-induced DNA double-strand breaks via homologous recombination, indicating that Akt signaling positively regulates HR.
What diseases are linked to defective HR regulation?
Defective HR regulation is linked to cancer (breast, ovarian, hepatocellular, pancreatic), Fanconi anemia, and miscarriage.
How can I study positive regulation of HR in the lab?
Common methods include DR-GFP HR reporter assays, Rad51 foci immunofluorescence, RNA-seq, proteomics, and CRISPR screens.
What CRISPR models are used to study HR regulators?
Knockout, point-mutation knock-in, tagged knock-in, and overexpression models are widely used to dissect HR regulator function.
Why is positive regulation of HR important for cancer therapy?
HR proficiency determines sensitivity to PARP inhibitors and platinum drugs; loss of positive regulation causes BRCAness and sensitivity, while gain can cause resistance.
What is the difference between HR and positive regulation of HR?
HR is the repair process itself (GO:0000724), while positive regulation of HR (GO:1905168) refers to the upstream signals and factors that increase HR activity.
Conclusion
GO:1905168, positive regulation of double-strand break repair via homologous recombination, is a critical biological process that governs genome stability and therapy response. The verified literature highlights diverse regulators, from ubiquitin ligases like RNF126 to chromatin remodelers like CHD1 and signaling kinases like Akt1/Akt2. Dysregulation of this process is implicated in cancer, Fanconi anemia, and miscarriage, making it a rich area for therapeutic targeting. CRISPR-based models, including knockout, point-mutation, knock-in, and overexpression, are indispensable for dissecting the causal roles of these regulators. EDITGENE offers comprehensive services to accelerate such research, from custom cell model generation to high-throughput library screening and bioinformatics analysis.
References
- 1. Wang Y et al.. 2016. RNF126 promotes homologous recombination via regulation of E2F1-mediated BRCA1 expression.. Oncogene 35(11):1363-72 PMID: 26234677
- 2. Li H et al.. 2023. RAD54L promotes progression of hepatocellular carcinoma via the homologous recombination repair pathway.. Funct Integr Genomics 23(2):128 PMID: 37071224
- 3. Li P et al.. 2025. OFD1 inhibition induces BRCAness to create a therapeutic vulnerability to PARP inhibition in pancreatic cancer.. Nat Commun 16(1):7209 PMID: 40764600
- 4. Deng Q et al.. 2024. SOSTDC1 Nuclear Translocation Facilitates BTIC Maintenance and CHD1-Mediated HR Repair to Promote Tumor Progression and Olaparib Resistance in TNBC.. Adv Sci (Weinh) 11(29):e2306860 PMID: 38864559
- 5. Donahue SL et al.. 2003. Deficient regulation of DNA double-strand break repair in Fanconi anemia fibroblasts.. J Biol Chem 278(32):29487-95 PMID: 12748186
- 6. Chen W et al.. 2024. Defective Homologous Recombination Repair By Up-Regulating Lnc-HZ10/Ahr Loop in Human Trophoblast Cells Induced Miscarriage.. Adv Sci (Weinh) 11(13):e2207435 PMID: 38286681
- 7. 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
- 8. Mohammadian Gol T et al.. 2019. Depletion of Akt1 and Akt2 Impairs the Repair of Radiation-Induced DNA Double Strand Breaks via Homologous Recombination.. Int J Mol Sci 20(24) PMID: 31847370
