GO:0070911 global genome nucleotide-excision repair: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0070911 (global genome nucleotide-excision repair, GG-NER) is the nucleotide-excision repair subpathway that removes DNA lesions from nontranscribed strands and transcriptionally silent regions across the entire genome.
• GG-NER is initiated by damage recognition factors such as the XPC-RAD23B-CETN2 complex, which detects helix-distorting lesions including UV-induced cyclobutane pyrimidine dimers and 6-4 photoproducts.
• The core excision machinery (TFIIH, XPA, RPA, XPG, XPF-ERCC1) creates dual incisions and releases a 24-32 nucleotide damage-containing fragment, followed by gap-filling synthesis and ligation.
• Defects in GG-NER cause xeroderma pigmentosum and Cockayne syndrome-like phenotypes, and GG-NER status influences cisplatin and UV sensitivity in cancer cells.
• GG-NER is regulated by ubiquitin and SUMO modifiers, including CUL4-DDB1-DDB2-mediated ubiquitination of XPC and DDB2, which tune damage recognition and repair efficiency.
• CRISPR knockout, point-mutation, knock-in, and overexpression cell models enable causal dissection of GG-NER gene function and drug-response mechanisms.
Description
Global genome nucleotide-excision repair (GG-NER), annotated as GO:0070911, is a biological process that removes DNA lesions from nontranscribed strands and from transcriptionally silent regions over the entire genome. It is one of two major nucleotide-excision repair (NER) subpathways, the other being transcription-coupled NER (TC-NER), which preferentially repairs lesions in actively transcribed genes. GG-NER is essential for protecting cells from bulky DNA adducts induced by ultraviolet (UV) radiation, environmental carcinogens, and chemotherapeutic agents such as cisplatin. Researchers study GG-NER because its dysfunction is directly linked to human disease. Inherited defects in GG-NER genes cause xeroderma pigmentosum, a cancer-prone disorder characterized by extreme UV sensitivity, and can also contribute to Cockayne syndrome and other repair-deficiency syndromes. In cancer biology, GG-NER activity modulates responses to platinum-based chemotherapy and other DNA-damaging treatments, making it a target for therapeutic stratification. The pathway also intersects with ubiquitin and SUMO signaling, providing regulatory nodes that can be experimentally manipulated. Mechanistically, GG-NER is a multi-step process requiring coordinated action of damage recognition, helicase unwinding, incision, excision, DNA synthesis, and ligation factors. The pathway is highly conserved from prokaryotes to humans, and comparative studies continue to inform mechanistic models. This article summarizes the authoritative GO definition, core molecular steps, key genes, disease associations, and research methods for investigating GO:0070911.
global genome nucleotide-excision repair At A Glance
| GO ID | GO:0070911 |
|---|---|
| GO term | global genome nucleotide-excision repair |
| Ontology | biological_process |
| Synonym | GG-NER; GGR; global genome NER; global genomic nucleotide-excision repair; global genomic repair |
| Major function | Removal of DNA lesions from nontranscribed strands and transcriptionally silent regions across the entire genome |
| Subpathway of | nucleotide-excision repair (NER) |
| Key damage types | UV-induced cyclobutane pyrimidine dimers, 6-4 photoproducts, bulky chemical adducts, cisplatin-DNA crosslinks |
| Initiation factor | XPC-RAD23B-CETN2 complex, with DDB2 for some lesions |
| Core excision factors | TFIIH, XPA, RPA, XPG, XPF-ERCC1 |
| Disease relevance | Xeroderma pigmentosum, Cockayne syndrome, cancer chemotherapy response, neurodegeneration |
What Is GO:0070911?
According to the Gene Ontology, GO:0070911 (global genome nucleotide-excision repair) is defined as the nucleotide-excision repair process in which DNA lesions are removed from nontranscribed strands and from transcriptionally silent regions over the entire genome. In other words, GG-NER surveys the whole genome for helix-distorting damage, independent of whether the DNA is being transcribed, and excises the damaged segment so that normal DNA sequence can be restored.
Why Is global genome nucleotide-excision repair Important in Cell Biology?
GG-NER is critically important because it is the primary defense against bulky DNA lesions that would otherwise cause mutations, cell death, or malignant transformation. Unlike TC-NER, which is restricted to transcribed strands, GG-NER operates genome-wide and therefore protects the vast majority of the genome from UV and chemical damage. Its efficiency determines cellular sensitivity to UV radiation and platinum-based drugs, and inherited defects in GG-NER genes underlie severe human disorders including xeroderma pigmentosum. Understanding GG-NER also informs cancer therapy, aging research, and the development of DNA-repair-targeted treatments.
• Protects the entire genome from UV-induced cyclobutane pyrimidine dimers and 6-4 photoproducts.
• Prevents mutations that can lead to skin cancer and other malignancies.
• Determines cellular sensitivity to cisplatin and other platinum-based chemotherapeutics.
• Inherited defects cause xeroderma pigmentosum and related repair-deficiency syndromes.
• Regulated by ubiquitin and SUMO post-translational modifiers that control damage recognition.
• Provides a model system for studying DNA damage recognition and dual-incision mechanisms.
• Conserved from prokaryotes to humans, enabling comparative mechanistic studies.
• Interfaces with transcription-coupled repair to ensure comprehensive genome maintenance.
• Contributes to neuronal survival and may influence cisplatin-induced neurotoxicity.
• Offers therapeutic targets for sensitizing cancer cells to DNA-damaging agents.
What Happens During global genome nucleotide-excision repair?
Damage recognition by XPC-RAD23B-CETN2
In simple terms: The cell first finds the damaged spot in DNA using a sensor protein complex.
GG-NER is initiated by the XPC-RAD23B-CETN2 complex, which recognizes helix-distorting lesions such as UV-induced cyclobutane pyrimidine dimers and 6-4 photoproducts. For certain lesions, the UV-DDB complex (DDB1-DDB2) assists in damage detection and recruits XPC. This recognition step is the primary determinant of GG-NER specificity and is regulated by ubiquitination and SUMOylation.
TFIIH recruitment and DNA unwinding
In simple terms: A molecular machine opens up the DNA around the damage so other repair proteins can access it.
After damage recognition, TFIIH is recruited to the lesion site, and its helicase subunits unwind the DNA duplex to create a repair bubble. This unwinding is ATP-dependent and allows subsequent factors to verify the damage and position the incision machinery.
Damage verification and dual incision
In simple terms: The repair machinery checks the damage and cuts the DNA on both sides of the lesion.
XPA and RPA bind the unwound DNA and help verify the damage, while the endonucleases XPG and XPF-ERCC1 make incisions on the 3' and 5' sides of the lesion, respectively. This dual incision releases a 24-32 nucleotide fragment containing the damage.
Excision, DNA synthesis, and ligation
In simple terms: The damaged piece is removed, and the gap is filled in and sealed.
Following dual incision, the damage-containing oligonucleotide is excised, and the resulting gap is filled by DNA polymerase delta or epsilon using the undamaged strand as a template. The final nick is sealed by DNA ligase I or III, restoring the original DNA sequence.
Regulation by ubiquitin and SUMO modifiers
In simple terms: Small tags are added to repair proteins to control when and how efficiently they work.
GG-NER is controlled by ubiquitin and SUMO post-translational modifications that regulate the stability, localization, and activity of damage recognition factors such as XPC and DDB2. CUL4-DDB1-DDB2-mediated ubiquitination of XPC and DDB2 modulates repair efficiency and is essential for proper GG-NER function.
Key Genes Involved in GO:0070911 global genome nucleotide-excision repair
The following genes encode core proteins that participate in or regulate global genome nucleotide-excision repair (GO:0070911).
| Gene | Major Role | Research Relevance |
|---|---|---|
| XPC | Primary damage recognition factor in GG-NER | Mutations cause xeroderma pigmentosum; key target for KO and point-mutation studies |
| RAD23B | Binds XPC and stabilizes damage recognition complex | Modulates GG-NER efficiency; candidate for overexpression and knockdown |
| CETN2 | Centrin-2, component of XPC complex | Supports XPC function; studied in KO models |
| DDB1 | UV-DDB complex subunit, assists damage detection | Regulates XPC recruitment; target for KO and proteomics |
| DDB2 | UV-DDB complex subunit, binds UV lesions | Mutations cause XP group E; regulated by ubiquitination |
| XPA | Damage verification and incision positioning | Mutations cause XP group A; core factor for KO studies |
| ERCC1 | XPF-ERCC1 endonuclease subunit, 5' incision | Mutations cause XP and Cockayne-like phenotypes; drug sensitivity |
| ERCC4 (XPF) | Catalytic subunit of XPF-ERCC1, 5' incision | Target for point-mutation and knock-in studies |
| ERCC5 (XPG) | 3' incision endonuclease | Mutations cause XP group G; KO models available |
| XPB (ERCC3) | TFIIH helicase subunit | Mutations cause XP group B; essential for unwinding |
| XPD (ERCC2) | TFIIH helicase subunit | Mutations cause XP group D; target for functional studies |
| RPA1 | Binds single-stranded DNA during repair | Supports damage verification; KO is lethal |
| RPA2 | RPA subunit, ssDNA binding | Modulates repair; studied in overexpression models |
| LIG1 | DNA ligase I, seals repair patch | Final step of GG-NER; KO affects repair completion |
| CUL4A | E3 ubiquitin ligase, regulates XPC/DDB2 | Target for KO and regulation studies |
| SUMO1 | SUMO modifier, regulates repair factors | Studied in SUMOylation and GG-NER regulation |
| TP53 | Regulates DNA damage response and NER gene expression | Indirect regulator; KO affects GG-NER capacity |
How Is global genome nucleotide-excision repair Regulated?
GG-NER is regulated at multiple levels, including post-translational modification by ubiquitin and SUMO. CUL4-DDB1-DDB2-mediated ubiquitination of XPC and DDB2 controls damage recognition and repair efficiency. SUMOylation of repair factors also modulates GG-NER activity. Additionally, the DNA damage response kinase ATM/ATR and the transcription factor TP53 can influence NER gene expression and overall repair capacity. These regulatory layers provide experimental entry points for manipulating GG-NER in cell models.
global genome nucleotide-excision repair and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| XPC | Xeroderma pigmentosum group C; UV hypersensitivity | XPC knockout keratinocytes or fibroblasts |
| XPA | Xeroderma pigmentosum group A; neurodegeneration | XPA knockout neuronal cell lines |
| ERCC1 | Xeroderma pigmentosum; Cockayne-like syndrome | ERCC1 knockout or point-mutation models |
| ERCC5 (XPG) | Xeroderma pigmentosum group G | XPG knockout cell lines |
| DDB2 | Xeroderma pigmentosum group E | DDB2 knockout or overexpression models |
Xeroderma pigmentosum and GG-NER deficiency
Inherited mutations in GG-NER genes such as XPC, XPA, ERCC1, ERCC4, and ERCC5 cause xeroderma pigmentosum, a disorder characterized by extreme sensitivity to UV radiation and a markedly increased risk of skin cancer. Cells from these patients show defective removal of UV-induced lesions, confirming the essential role of GG-NER in genome protection.
Cancer chemotherapy response and cisplatin sensitivity
GG-NER activity influences the cellular response to cisplatin, a platinum-based chemotherapeutic that forms bulky DNA adducts. Defects in GG-NER can sensitize cancer cells to cisplatin, while elevated repair capacity may contribute to drug resistance. Recent work has linked DNA repair, including NER, to cisplatin-induced neuronal death, suggesting that GG-NER modulation may affect neurotoxicity.
Neurodegeneration and repair-deficiency syndromes
Some GG-NER defects overlap with Cockayne syndrome and other neurodegenerative phenotypes, particularly when TC-NER or overlapping repair functions are also affected. The interplay between GG-NER and transcription-coupled repair is critical for neuronal survival, and impaired repair can lead to progressive neurodegeneration.
From global genome nucleotide-excision repair-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is XPC required for GG-NER in a specific cell type? | XPC knockout cell line |
| Does a patient variant impair damage recognition? | XPC point-mutation knock-in |
| Can tagged XPC be used to track repair dynamics? | XPC tagged knock-in (e.g., GFP or HA) |
| Does DDB2 overexpression enhance UV repair? | DDB2 overexpression cell line |
| Which genes modulate cisplatin sensitivity via GG-NER? | CRISPR library screening in cancer cells |
| How does SUMOylation regulate XPC function? | SUMO1 knockout or knock-in models |
How to Study the global genome nucleotide-excision repair Process
| Method | What It Measures | Typical Application |
|---|---|---|
| UV survival assay | Cell viability after UV damage | GG-NER functional status |
| CPD/6-4 photoproduct ELISA | Lesion removal kinetics | Quantifying GG-NER activity |
| Comet assay | DNA strand breaks and repair | Genome-wide repair assessment |
| Co-immunoprecipitation | Protein-protein interactions | XPC complex composition |
| Western blot for ubiquitin/SUMO | Post-translational modifications | Regulation of XPC and DDB2 |
| RNA-seq | Transcriptional changes after damage | GG-NER-dependent gene expression |
| CRISPR library screening | Gene requirements for repair | Identifying novel GG-NER modulators |
UV sensitivity and survival assays
Clonogenic survival and apoptosis assays after UV irradiation are standard methods to measure GG-NER capacity in cells. Cells with defective GG-NER show increased UV sensitivity and reduced survival.
DNA damage detection and repair kinetics
Immunoassays for cyclobutane pyrimidine dimers and 6-4 photoproducts, as well as comet assays, quantify lesion removal over time. These methods directly measure GG-NER activity in genomic DNA.
Protein interaction and modification analysis
Co-immunoprecipitation, mass spectrometry, and ubiquitin/SUMO Western blotting can identify GG-NER complex components and their post-translational modifications. These approaches are useful for studying XPC, DDB2, and their regulators.
Transcriptomic and proteomic profiling
RNA-seq and proteomics can reveal global changes in gene expression and protein abundance after DNA damage, helping to identify GG-NER-dependent pathways. Such profiling is often combined with CRISPR knockout models to establish causality.
How CRISPR Can Be Used to Study GO:0070911 global genome nucleotide-excision repair
Knockout
CRISPR knockout of GG-NER genes such as XPC, XPA, or ERCC1 creates isogenic cell models to test repair capacity, UV sensitivity, and drug response. These models are essential for establishing causal roles of specific genes in GO:0070911.
Point Mutation
Point-mutation knock-in of patient-derived variants (e.g., in XPC or ERCC5) allows precise assessment of how specific amino acid changes affect GG-NER function and disease phenotypes. This approach distinguishes loss-of-function from hypomorphic alleles.
Knock-in
Tagged knock-in of GG-NER genes (e.g., GFP-XPC or HA-DDB2) enables live-cell imaging and proteomic analysis of repair complex dynamics. Knock-in of reporter cassettes can also quantify repair activity at specific loci.
Overexpression
Overexpression of GG-NER factors such as XPC or DDB2 can test whether increased repair capacity alters UV or cisplatin sensitivity. Overexpression models are useful for studying regulatory mechanisms and potential resistance phenotypes.
How EDITGENE Supports global genome nucleotide-excision repair Research
Researchers studying global genome nucleotide-excision repair-related genes often need to determine whether a candidate gene is causally involved in damage recognition, excision, or regulation. EDITGENE provides CRISPR-based cell model services that enable precise genetic manipulation of GG-NER pathway components, from knockout to knock-in and overexpression, supported by library screening and bioinformatics.
Contact EDITGENE today to design your custom CRISPR model for global genome nucleotide-excision repair research.
Frequently Asked Questions About global genome nucleotide-excision repair
What is global genome nucleotide-excision repair (GO:0070911)?
It is the nucleotide-excision repair subpathway that removes DNA lesions from nontranscribed strands and transcriptionally silent regions across the entire genome.
What genes are involved in global genome nucleotide-excision repair?
Key genes include XPC, RAD23B, CETN2, DDB1, DDB2, XPA, ERCC1, ERCC4 (XPF), ERCC5 (XPG), XPB (ERCC3), XPD (ERCC2), RPA1, RPA2, and LIG1.
How does GG-NER differ from transcription-coupled NER?
GG-NER repairs lesions genome-wide, including nontranscribed regions, while TC-NER specifically targets lesions in actively transcribed genes.
What types of DNA damage does GG-NER repair?
GG-NER repairs bulky helix-distorting lesions such as UV-induced cyclobutane pyrimidine dimers, 6-4 photoproducts, and cisplatin-DNA adducts.
What diseases are associated with defective GG-NER?
Defects cause xeroderma pigmentosum and can contribute to Cockayne syndrome-like phenotypes, neurodegeneration, and altered cancer chemotherapy responses.
How is GG-NER regulated?
It is regulated by ubiquitin and SUMO post-translational modifications, including CUL4-DDB1-DDB2-mediated ubiquitination of XPC and DDB2.
What is the role of XPC in GG-NER?
XPC, in complex with RAD23B and CETN2, is the primary damage recognition factor that initiates GG-NER.
Can CRISPR be used to study GG-NER?
Yes, CRISPR knockout, point-mutation, knock-in, and overexpression models are widely used to dissect GG-NER gene function and drug responses.
What methods measure GG-NER activity?
UV survival assays, CPD/6-4 photoproduct ELISA, comet assays, and repair kinetics measurements are commonly used.
Why is GG-NER important in cancer therapy?
GG-NER activity affects sensitivity to cisplatin and other DNA-damaging agents, making it a potential biomarker and therapeutic target.
Conclusion
Global genome nucleotide-excision repair (GO:0070911) is a genome-wide DNA repair pathway essential for removing bulky lesions from nontranscribed DNA and transcriptionally silent regions. Its core machinery, from XPC-mediated damage recognition to dual incision and gap filling, is highly conserved and tightly regulated by ubiquitin and SUMO modifiers. Defects in GG-NER cause xeroderma pigmentosum and influence cancer chemotherapy responses, underscoring its clinical importance. CRISPR-based cell models provide powerful tools to dissect GG-NER gene function and identify new therapeutic opportunities.
References
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