GO:0110025 DNA strand resection involved in replication fork processing: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0110025 describes the 5' to 3' exonucleolytic resection of DNA at a stalled replication fork, a key step in replication fork processing.
• Resection generates single-stranded DNA (ssDNA) that triggers ATR-dependent checkpoint signaling and homologous recombination repair.
• The DNA2 nuclease/helicase is a central enzyme for long-range resection, often working with BLM or WRN helicases.
• Resection must be balanced with fork protection; proteins such as BOD1L shield nascent strands from uncontrolled degradation.
• Deregulated resection contributes to genome instability, chemoresistance, and diseases including cancer and centromeric replication defects.
• CRISPR knockout, point-mutation, and knock-in models enable precise dissection of resection factors in replication stress responses.
Description
DNA replication forks frequently encounter obstacles that cause stalling, and cells must process these forks to maintain genome stability. GO:0110025, DNA strand resection involved in replication fork processing, captures the 5' to 3' exonucleolytic degradation of DNA at a stalled fork, a process that generates ssDNA and initiates downstream signaling and repair. This term is distinct from general double-strand break resection because it is specifically tied to replication fork processing, where the fork structure and associated proteins create unique regulatory requirements. Understanding this process is critical for researchers studying replication stress, DNA repair, and cancer therapy resistance. The QuickGO definition states: The 5' to 3' exonucleolytic resection of DNA at the site of a stalled replication fork that contributes to replication fork processing. This article synthesizes published literature to explain the mechanism, key genes, disease links, and experimental approaches for studying GO:0110025.
DNA strand resection involved in replication fork processing At A Glance
| GO ID | GO:0110025 |
|---|---|
| GO term | DNA strand resection involved in replication fork processing |
| Ontology | biological_process |
| Synonym | None |
| Definition | The 5' to 3' exonucleolytic resection of DNA at the site of a stalled replication fork that contributes to replication fork processing. |
| Major function | Generation of ssDNA at stalled forks to promote checkpoint signaling and repair |
| Related processes | Homologous recombination, ATR signaling, fork protection, fork restart |
| Key enzymes | DNA2, BLM, WRN, EXO1, MRE11 |
| Disease relevance | Cancer, genome instability, chemoresistance |
What Is GO:0110025?
GO:0110025 is a biological process term describing the 5' to 3' exonucleolytic resection of DNA at a stalled replication fork. In this process, nucleases degrade one strand of the DNA end in the 5' to 3' direction, creating 3' single-stranded DNA overhangs. This resection is not a generic DNA end-processing event; it occurs specifically at replication forks that have stalled or collapsed, and it contributes to fork processing, which can lead to fork restart, repair, or checkpoint activation. The term is a child of replication fork processing and is mechanistically linked to homologous recombination and ATR signaling.
Why Is DNA strand resection involved in replication fork processing Important in Cell Biology?
Resection at stalled replication forks is a double-edged sword: it is required to generate ssDNA for ATR activation and homologous recombination, but uncontrolled resection leads to fork degradation and genome instability. This process is central to how cells survive replication stress, and its dysregulation is implicated in cancer and chemotherapy resistance. Studying GO:0110025 helps researchers understand the molecular basis of fork processing and identify therapeutic targets.
• Generates ssDNA that activates the ATR checkpoint to pause cell cycle progression.
• Facilitates homologous recombination-mediated fork restart and repair.
• Balances with fork protection factors such as BOD1L to prevent excessive degradation.
• DNA2 nuclease/helicase is essential for long-range resection and centromeric replication.
• Defects in resection factors cause genome instability and sensitivity to replication stress.
• Resection activity influences sensitivity to PARP inhibitors and platinum-based chemotherapy.
• Plays a role in the cellular response to replication arrest, with both beneficial and detrimental genes identified.
• Cytosolic DNA sensing pathways can be activated by resected DNA, linking to innate immunity.
• NBS1 and chromatin modifications regulate resection at damaged forks.
• Understanding resection guides development of CRISPR models for cancer research.
What Happens During DNA strand resection involved in replication fork processing?
Fork stalling and initial processing
In simple terms: When a replication fork hits damage, it stops and the cell must trim the DNA ends to signal for help.
Replication forks stall when they encounter DNA lesions, nucleotide depletion, or secondary structures. The stalled fork is recognized by sensor proteins, and initial nucleolytic processing begins. MRE11, in complex with RAD50 and NBS1 (MRN), can initiate short-range resection at the fork. This early step is regulated by chromatin modifications and NBS1, which coordinate the recruitment of downstream resection machinery. The goal is to create a limited ssDNA region that can recruit ATR and its activator ATRIP.
Long-range resection by DNA2 and EXO1
In simple terms: Specialized enzymes then chew back the DNA further to create long single-stranded tails.
After initial processing, long-range resection is carried out by two main pathways: DNA2 nuclease/helicase with BLM or WRN, and EXO1. DNA2 is a multifunctional enzyme with both nuclease and helicase activities, and it promotes centromeric DNA replication and genome stability. DNA2 works with BLM to resect DNA in the 5' to 3' direction, generating long 3' ssDNA overhangs. EXO1 provides an alternative resection pathway, and the two are partially redundant. This step is critical for generating enough ssDNA to activate the ATR checkpoint and for homologous recombination.
Fork protection and balance
In simple terms: The cell must protect the fork from being over-digested, so it uses shielding proteins.
Uncontrolled resection leads to fork degradation and genome instability, so cells deploy fork protection factors. BOD1L is a key protection factor that shields nascent DNA strands from excessive resection by DNA2 and other nucleases. The balance between resection and protection is regulated by post-translational modifications and protein-protein interactions. Loss of BOD1L leads to hypersensitive forks and increased DNA damage. This balance ensures that enough ssDNA is generated for signaling without compromising fork integrity.
Checkpoint activation and repair
In simple terms: The single-stranded DNA created by resection acts as a flag to call in repair and checkpoint proteins.
The ssDNA generated by resection is coated by RPA, which recruits ATR and its partner ATRIP, leading to CHK1 activation and cell cycle arrest. This checkpoint gives the cell time to repair the fork. Resection also promotes homologous recombination, which can restart the fork or repair a collapsed fork. NBS1 is important for the recruitment of repair factors and for chromatin remodeling at the damage site. If repair fails, the fork can collapse, leading to double-strand breaks and genome instability.
Cytosolic DNA sensing and immune signaling
In simple terms: Resected DNA can leak into the cytosol and trigger an immune response.
Recent studies show that resected DNA at stressed replication forks can be sensed by cGAS/STING in the cytosol, leading to TRPV2-mediated calcium release and protection of stressed forks. This pathway links replication fork resection to innate immune signaling and cell survival. The cGAS/STING pathway is activated by cytosolic DNA, which can arise from resected forks. This emerging area highlights the broader impact of resection beyond DNA repair.
Key Genes Involved in GO:0110025 DNA strand resection involved in replication fork processing
The following genes and proteins are central to DNA strand resection involved in replication fork processing, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| DNA2 | Nuclease/helicase for long-range resection; promotes centromeric replication | Knockout causes replication stress and genome instability |
| BLM | Helicase that partners with DNA2 for resection | Mutations cause Bloom syndrome; model for resection studies |
| WRN | Helicase that can substitute for BLM in resection | Mutations cause Werner syndrome; linked to aging |
| EXO1 | Exonuclease for long-range resection | Redundant with DNA2; knockout affects repair |
| MRE11 | Initiates short-range resection as part of MRN complex | Mutations cause ataxia-telangiectasia-like disorder |
| RAD50 | Component of MRN complex with MRE11 | Structural role in resection initiation |
| NBS1 | MRN component; regulates resection and chromatin | Mutations cause Nijmegen breakage syndrome |
| BOD1L | Fork protection factor; limits resection | Knockout leads to fork degradation |
| RPA | Binds ssDNA generated by resection | Essential for ATR activation |
| ATR | Checkpoint kinase activated by ssDNA-RPA | Target for cancer therapy |
| ATRIP | ATR-interacting protein; recruits ATR to ssDNA | Required for checkpoint signaling |
| CHK1 | Downstream effector of ATR | Phosphorylated upon resection |
| cGAS | Cytosolic DNA sensor activated by resected DNA | Links resection to innate immunity |
| STING | Adaptor for cGAS signaling | Mediates calcium release and fork protection |
| TRPV2 | Calcium channel activated by cGAS/STING | Protects stressed forks |
| FANCD2 | Fork protection factor (implied by replication stress response) | Monoubiquitination upon replication arrest |
| PCNA | Sliding clamp; interacts with resection factors | Modified upon fork stalling |
How Is DNA strand resection involved in replication fork processing Regulated?
Resection at stalled forks is tightly regulated by post-translational modifications and protein-protein interactions. BOD1L protects forks from excessive resection, and its loss leads to hypersensitive forks. NBS1 and chromatin modifications regulate the recruitment of resection factors. The cGAS/STING pathway can also modulate fork protection through calcium signaling. Additionally, the balance between resection and protection is influenced by the type of DNA damage and cell cycle phase.
DNA strand resection involved in replication fork processing and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| DNA2 | Cancer, centromeric instability | Knockout in cancer cell lines; overexpression |
| BOD1L | Fork degradation, chemosensitivity | Knockout in U2OS cells |
| NBS1 | Nijmegen breakage syndrome | Patient-derived cells; knock-in of mutations |
| cGAS | Autoinflammatory diseases | Knockout in macrophages; STING reporter |
| EXO1 | Cancer predisposition | Knockout in HCT116 |
Cancer and chemoresistance
Deregulated resection contributes to genome instability and resistance to chemotherapy. DNA2 is overexpressed in some cancers and promotes cell survival under replication stress. Loss of fork protection factors like BOD1L leads to sensitivity to DNA-damaging agents. Targeting resection pathways is a potential therapeutic strategy.
Centromeric replication defects
DNA2 is essential for centromeric DNA replication, and its depletion causes centromeric instability. This links resection to chromosomal instability and diseases associated with centromere dysfunction.
Innate immune disorders
The cGAS/STING pathway activated by resected DNA can trigger inflammatory responses. Dysregulation of this pathway is implicated in autoimmune diseases. Understanding resection-mediated immune activation may reveal new therapeutic targets.
From DNA strand resection involved in replication fork processing-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does DNA2 nuclease activity promote fork resection? | Point mutation (D277A) knock-in |
| What is the role of BOD1L in fork protection? | Knockout via CRISPR |
| How does NBS1 regulate resection? | Knock-in of patient mutations |
| Can overexpression of DNA2 rescue resection defects? | Overexpression in DNA2-knockout cells |
| Does cGAS/STING activation protect forks? | Knockout of cGAS or STING |
| What genes are essential for replication arrest survival? | CRISPR library screening |
How to Study the DNA strand resection involved in replication fork processing Process
| Method | What It Measures | Typical Application |
|---|---|---|
| DNA fiber assay | Fork progression and degradation | Assess resection after BOD1L knockout |
| RPA foci staining | ssDNA generation | Measure resection in cells |
| pCHK1 western blot | ATR checkpoint activation | Confirm resection signaling |
| CRISPR library screen | Genes required for replication arrest survival | Identify novel resection factors |
| Proteomics | Protein interactions with DNA2 | Map resection complex |
| Electron microscopy | Fork structures | Visualize resected forks |
| Comet assay | DNA breaks | Detect genome instability |
| Live-cell imaging | Fork dynamics | Track fork protection by cGAS/STING |
DNA fiber assay
The DNA fiber assay measures replication fork progression and resection by labeling nascent DNA with nucleotide analogs. It is used to assess fork degradation upon knockdown of protection factors.
RPA and ATR signaling detection
Immunofluorescence for RPA foci and western blot for phosphorylated CHK1 measure checkpoint activation downstream of resection. These methods quantify ssDNA generation.
CRISPR screening
Genome-wide CRISPR knockout screens identify genes that are beneficial or detrimental for survival under replication arrest. This approach has uncovered novel resection regulators.
Proteomics and interactomics
Mass spectrometry-based proteomics identifies proteins associated with resection factors like DNA2 and BLM. This reveals the resection machinery composition.
How CRISPR Can Be Used to Study GO:0110025 DNA strand resection involved in replication fork processing
Knockout
CRISPR knockout of DNA2, BOD1L, or EXO1 is used to study their roles in resection and fork protection. Knockout cells show increased fork degradation and sensitivity to replication stress. Genome-wide knockout screens have identified genes that are beneficial or detrimental for survival under replication arrest.
Point Mutation
Point mutations in the nuclease domain of DNA2 (e.g., D277A) abolish resection activity and are used to separate its nuclease and helicase functions. Knock-in of patient-derived mutations in NBS1 helps dissect its role in resection.
Knock-in
Knock-in of tagged versions of resection proteins (e.g., GFP-DNA2) allows live-cell imaging and proteomics. Knock-in of disease-associated mutations in NBS1 or DNA2 provides models for human disorders.
Overexpression
Overexpression of DNA2 or BLM is used to test if increased resection activity promotes fork restart or chemoresistance. Overexpression of cGAS or STING can enhance fork protection.
How EDITGENE Supports DNA strand resection involved in replication fork processing Research
Researchers studying DNA strand resection involved in replication fork processing-related genes often need to determine whether a candidate gene is causally involved in fork stability, checkpoint activation, or chemoresistance. EDITGENE provides CRISPR-based services to create precise cell models for such functional studies.
Contact EDITGENE today to design your custom CRISPR model for DNA strand resection involved in replication fork processing research.
Frequently Asked Questions About DNA strand resection involved in replication fork processing
What is GO:0110025?
GO:0110025 is a Gene Ontology biological process term for the 5' to 3' exonucleolytic resection of DNA at a stalled replication fork, contributing to fork processing.
What genes are involved in DNA strand resection involved in replication fork processing?
Key genes include DNA2, BLM, WRN, EXO1, MRE11, RAD50, NBS1, BOD1L, RPA, ATR, and cGAS.
Why is resection at stalled forks important?
It generates ssDNA for ATR checkpoint activation and homologous recombination, but must be balanced with fork protection to avoid genome instability.
How is resection at replication forks regulated?
It is regulated by fork protection factors like BOD1L, chromatin modifications, NBS1, and cGAS/STING signaling.
What diseases are linked to defective resection?
Cancer, chemoresistance, centromeric instability, and innate immune disorders.
What methods study DNA strand resection?
DNA fiber assay, RPA foci staining, pCHK1 western blot, CRISPR screens, and proteomics.
What is the role of DNA2 in resection?
DNA2 is a nuclease/helicase that performs long-range resection with BLM or WRN and is essential for centromeric replication.
How does BOD1L protect forks?
BOD1L shields nascent DNA from excessive resection by nucleases like DNA2.
Can CRISPR knockout models study resection?
Yes, knockout of DNA2, BOD1L, or EXO1 reveals their roles in fork degradation and replication stress.
What is the link between resection and innate immunity?
Resected DNA can activate cGAS/STING, leading to TRPV2-mediated calcium release and fork protection.
Conclusion
GO:0110025, DNA strand resection involved in replication fork processing, is a critical biological process that generates ssDNA at stalled forks to trigger checkpoint signaling and repair. Its regulation by DNA2, BOD1L, and other factors ensures a balance between resection and protection. Dysregulation of this process contributes to cancer and genome instability, making it a key area for therapeutic research. CRISPR-based models from EDITGENE enable precise functional studies of resection genes.
References
- 1. Li S et al.. 2023. Cytosolic DNA sensing by cGAS/STING promotes TRPV2-mediated Ca(2+) release to protect stressed replication forks.. Mol Cell 83(4):556-573.e7 PMID: 36696898
- 2. Bonetti D et al.. 2018. Processing of DNA Ends in the Maintenance of Genome Stability.. Front Genet 9:390 PMID: 30258457
- 3. Higgs MR et al.. 2016. Protection or resection: BOD1L as a novel replication fork protection factor.. Nucleus 7(1):34-40 PMID: 26889944
- 4. Saito Y et al.. 2016. Chromatin modification and NBS1: their relationship in DNA double-strand break repair.. Genes Genet Syst 90(4):195-208 PMID: 26616756
- 5. Zheng L et al.. 2020. Multiple roles of DNA2 nuclease/helicase in DNA metabolism, genome stability and human diseases.. Nucleic Acids Res 48(1):16-35 PMID: 31754720
- 6. Patel DR et al.. 2018. A tough row to hoe: when replication forks encounter DNA damage.. Biochem Soc Trans 46(6):1643-1651 PMID: 30514768
- 7. Schons-Fonseca L et al.. 2022. Beneficial and detrimental genes in the cellular response to replication arrest.. PLoS Genet 18(12):e1010564 PMID: 36574412
- 8. Li Z et al.. 2018. hDNA2 nuclease/helicase promotes centromeric DNA replication and genome stability.. EMBO J 37(14) PMID: 29773570
