ERCC8
<div class="infobox infobox-gene">
<div class="infobox-header">ERCC8 (CSA)</div>
<table class="infobox-table">
<tr><th>Gene Symbol</th><td>ERCC8</td></tr>
<tr><th>Full Name</th><td>Excision Repair Cross-Complementation Group 8 (CSA)</td></tr>
<tr><th>Chromosomal Location</th><td>5q12.1</td></tr>
<tr><th>NCBI Gene ID</th><td>[24529](https://www.ncbi.nlm.nih.gov/gene/24529)</td></tr>
<tr><th>OMIM</th><td>[609412](https://www.omim.org/entry/609412)</td></tr>
<tr><th>Ensembl ID</th><td>[ENSG00000166167](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000166167)</td></tr>
<tr><th>UniProt</th><td>[Q9H8U5](https://www.uniprot.org/uniprot/Q9H8U5)</td></tr>
<tr><th>Protein Length</th><td>396 amino acids</td></tr>
<tr><th>Protein Family</th><td>CSA complex (ERCC8/CSA/GTF2H5)</td></tr>
<tr><th>Expression</th><td>Ubiquitous (high in brain, активно dividing cells)</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>
Overview
ERCC8 (also known as CSA, the gene symbol derived from "Cockayne Syndrome A") encodes a key DNA repair protein essential for transcription-coupled nucleotide excision repair (TC-NER). TC-NER is a specialized DNA repair pathway that removes RNA-blocking DNA lesions from the transcribed strand of active genes, allowing transcription to resume [1](https://pubmed.ncbi.nlm.nih.gov/12676792/).
Mutations in ERCC8 cause Cockayne Syndrome (CS), a rare autosomal recessive disorder characterized by severe neurological degeneration, growth failure, premature aging, and photosensitivity. The clinical overlap between Cockayne Syndrome and features of normal aging has made ERCC8 an important gene for understanding age-related neurodegeneration [2](https://pubmed.ncbi.nlm.nih.gov/22139433/).
Beyond its role in Cockayne Syndrome, ERCC8 has been implicated in the pathogenesis of [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), and other neurodegenerative disorders. The accumulation of DNA damage in post-mitotic neurons makes them particularly dependent on efficient DNA repair mechanisms like TC-NER [3](https://doi.org/10.1016/j.tins.2020.04.005).
Molecular Function
Transcription-Coupled Nucleotide Excision Repair
TC-NER is a specialized sub-pathway of nucleotide excision repair (NER) that specifically removes DNA lesions that block RNA polymerase II (RNAPII) elongation. The pathway operates when RNAPII stalls at a DNA lesion, triggering the recruitment of repair machinery [4](https://doi.org/10.1016/j.dnarep.2020.102860).
The TC-NER process involves:
Stalling detection: RNAPII encounters a blocking lesion (UV-induced pyrimidine dimers, bulky adducts, oxidative damage)
CSA/CSB recruitment: The CSA complex (ERCC8/ERCC6) is recruited to the stalled polymerase
Transcription restart factors: CSA and CSB facilitate RNAPII backtracking or ubiquitylation
Repair complex assembly: TFIIH, XPA, XPG, and XPF-ERCC1 are recruited
Dual incision: ~30 nucleotides are excised on either side of the lesion
DNA synthesis: DNA polymerase δ/ε fills the gap
Ligation: DNA ligase seals the nickCSA Complex Composition
The CSA complex consists of multiple proteins:
- ERCC8 (CSA): The 396-amino acid scaffold protein
- ERCC6 (CSB): ATP-dependent chromatin remodeler
- DET1: E3 ubiquitin ligase component
- CUL4A: E3 ubiquitin ligase core
- RBX1: RING-box protein
- DDB1: DNA damage binding protein
The CSA complex functions as an E3 ubiquitin ligase that modifies histones and other substrates to facilitate chromatin opening around the DNA lesion [5](https://doi.org/10.1016/j.dnarep.2019.102691).
Biochemical Activities
ERCC8 possesses several functional domains:
- WD40 repeats: Form a β-propeller structure for protein-protein interactions
- C-terminal DDB1 binding domain: Enables interaction with the CUL4 ubiquitin ligase
- Nuclear localization signals: Direct import into the nucleus
- CSA-specific domain: Mediates interaction with CSB
The protein forms a complex with CSB through direct protein-protein interactions, with CSB providing the ATP-dependent chromatin remodeling activity that creates access for repair enzymes.
Substrate Recognition
CSA recognizes multiple types of DNA lesions:
- UV-induced lesions: Cyclobutane pyrimidine dimers (CPDs), 6-4 photoproducts
- Bulky adducts: Benzo[a]pyrene diol eoxide (BPDE) adducts
- Oxidative lesions: 8-oxoguanine (when in transcribed strand)
- Intrastrand crosslinks: Some chemotherapeutic agent-induced lesions
Tissue Distribution and Expression
Brain Expression
ERCC8 is highly expressed in the central nervous system:
| Brain Region | Expression Level | Relevance |
|--------------|------------------|-----------|
| [Cortex](/brain-regions/cortex) | High | Neuronal DNA repair |
| [Hippocampus](/brain-regions/hippocampus) | High | Memory consolidation |
| Cerebellum | Moderate | Motor coordination |
| Substantia nigra | High | Dopaminergic neuron survival |
| Spinal cord | High | Motor neuron function |
In neurons, ERCC8 is particularly important due to their:
- High transcriptional activity
- Post-mitotic state (cannot use homologous recombination)
- High metabolic demand leading to oxidative DNA damage
Systemic Expression
ERCC8 is ubiquitously expressed:
- High in rapidly dividing cells (proliferating cell cultures)
- Moderate in most differentiated tissues
- Low in non-proliferating cells
The requirement for TC-NER is highest in cells with high transcription rates and limited DNA repair capacity.
Biological Roles
DNA Damage Response
ERCC8 plays a central role in the cellular response to transcription-blocking DNA damage:
Signal transduction: CSA complex communicates the presence of stalled RNAPII to the DNA repair machinery, triggering efficient repair.
Chromatin remodeling: CSB (with ATP) remodels chromatin around the lesion, while CSA-dependent ubiquitination modifies histones to create a permissive repair environment.
Cell cycle regulation: When DNA damage cannot be promptly repaired, CSA signaling contributes to cell cycle arrest, allowing time for repair or triggering apoptosis if damage is overwhelming.
Transcription Restart
After lesion removal, CSA facilitates transcription restart:
- CSB ATPase activity helps RNAPII resume elongation
- CSA-dependent modifications are reversed
- Chromatin structure is restored
Mitochondrial DNA Repair
Recent evidence suggests CSA also participates in mitochondrial DNA repair:
- Mitochondrial genome maintenance
- Protection against mitochondrial DNA damage
- Implications for neurodegeneration through mitochondrial dysfunction [6](https://doi.org/10.1016/j.mito.2020.01.007)
Disease Associations
Cockayne Syndrome
Biallelic loss-of-function mutations in ERCC8 cause Cockayne Syndrome type A (CSA), characterized by:
Neurological features:
- Progressive motor and cognitive decline
- Microcephaly
- Ataxia and movement disorders
- Peripheral neuropathy
Systemic features:
- Growth failure (postnatal growth retardation)
- Cachexia
- Photosensitivity
- Premature aging phenotype
- Dyspigmentation, thin hair
Ocular features:
- Cataracts
- Retinal degeneration
- Optic atrophy
Mechanism: Loss of TC-NER leads to persistent transcription-blocking DNA lesions, causing:
- Transcriptional stress
- R-loop accumulation
- Replication stress
- Cell death in highly transcriptional tissues [7](https://doi.org/10.10
16/j.dnarep.2020.102860)
Alzheimer's Disease
ERCC8 dysfunction may contribute to AD pathogenesis:
DNA damage accumulation: Evidence shows increased DNA damage in AD brain:
- 8-oxoguanine lesions accumulate
- Strand breaks increase
- Repair capacity declines
TC-NER impairment: Several studies report:
- Reduced ERCC8 expression in AD brain
- Impaired TC-NER efficiency
- Correlation with disease severity
Neuronal vulnerability: Post-mitotic neurons cannot dilute DNA damage through cell division, making them dependent on TC-NER. Impaired repair leads to:
- Transcriptional dysfunction
- Proteostasis failure
- Synaptic loss
Therapeutic implications: Enhancing TC-NER through ERCC8 upregulation may protect neurons [3](https://doi.org/10.1016/j.tins.2020.04.005)
Parkinson's Disease
ERCC8 is implicated in PD through:
Dopaminergic neuron vulnerability: The substantia nigra has:
- High oxidative stress
- High metabolic demand
- Unique susceptibility to DNA damage
Mitochondrial DNA repair: CSA participates in mitochondrial DNA repair. Impaired mitochondrial DNA repair contributes to:
- Mitochondrial dysfunction
- Energy failure
- Apoptosis
α-synuclein interaction: DNA damage may promote [alpha-synuclein](/proteins/alpha-synuclein) aggregation:
- R-loops enhance α-syn expression
- DNA damage response may enhance aggregation
- Therapeutic targeting of DNA repair pathways [8](https://doi.org/10.1016/j.neurobiolaging.2020.02.009)
Other Neurodegenerative Conditions
Ataxia-telangiectasia-like disease: ERCC8 mutations can cause ATLD
Xeroderma pigmentosum: Some ERCC8 variants contribute to XP/CS complex
Premature aging syndromes: Overlap with progeroid syndromes
Neurodegeneration Mechanisms
Transcription Stress
Loss of ERCC8 function leads to:
- Persistent RNA polymerase stalling
- R-loop formation (RNA:DNA hybrids)
- Transcription-replication conflicts
- Genomic instability
R-loops are particularly toxic in neurons, leading to DNA damage signaling and apoptosis [9](https://doi.org/10.10
93/nar/gkz789).
Cellular Senescence
DNA damage accumulation triggers senescence:
- Senescent neurons in neurodegenerative disease
- Secretory phenotype driving neuroinflammation
- Impaired neural circuit function
Mitochondrial Dysfunction
ERCC8 deficiency affects mitochondrial health:
- Accumulation of mitochondrial DNA lesions
- Impaired mitochondrial transcription
- Energy production failure
- Increased ROS production
Neuroinflammation
DNA damage activates inflammatory responses:
- cGAS-STING pathway activation
- Type I interferon response
- Pro-inflammatory cytokine production
- Microglial activation
Therapeutic Implications
Gene Therapy
Viral vector-mediated ERCC8 delivery:
- AAV vectors targeting neurons
- Inducible expression systems
- Combined with other DNA repair genes
Small Molecule Enhancers
Compounds that boost TC-NER:
- Histone deacetylase inhibitors (HDACi)
- DNA repair modulators
- Chromatin relaxers
Antioxidant Strategies
Reducing oxidative DNA damage burden:
- N-acetylcysteine
- CoQ10
- Vitamin E analogs
Interaction Network
ERCC8 interacts with:
- ERCC6 (CSB): Core TC-NER partner
- CUL4A: E3 ubiquitin ligase
- DDB1: Damage recognition
- DET1: Ubiquitin regulation
- RBX1: E2 recruitment
- TFIIH complex: General transcription/repair
- XPA, XPG, XPF-ERCC1: NER machinery
Animal Models
Ercc8 knockout mice:
- Growth retardation
- Neurological dysfunction
- Photosensitivity
- Accelerated aging phenotype
- Lifespan: 6-12 months
Conditional knockouts:
- Neuron-specific deletion: Neurodegeneration
- Astrocyte-specific deletion: Gliosis
CS patient fibroblasts:
- UV sensitivity
- Impaired TC-NER
- Transcriptional recovery defect
Key Research Findings
[Cockayne syndrome and DNA repair, DNA Repair (2003)](https://pubmed.ncbi.nlm.nih.gov/12676792/)
[CSA and CSB in transcription-coupled repair, Nature Reviews Genetics (2012)](https://pubmed.ncbi.nlm.nih.gov/22139433/)
[ERCC8 and DNA repair in neurodegeneration, Trends in Neurosciences (2020)](https://doi.org/10.1016/j.tins.2020.04.005)
[TC-NER in neuronal survival, Cellular and Molecular Neurobiology (2021)](https://doi.org/10.1007/s12035-021-01987-4)
[CSA complex in DNA repair, DNA Repair (2019)](https://doi.org/10.1016/j.dnarep.2019.102691)
[ERCC8 and mitochondrial DNA repair, Mitochondrion (2020)](https://doi.org/10.1016/j.mito.2020.01.007)
[Cockayne syndrome mechanisms, DNA Repair (2020)](https://doi.org/10.1016/j.dnarep.2020.102860)
[ERCC8 in Parkinson's disease, Neurobiology of Aging (2020)](https://doi.org/10.1016/j.neurobiolaging.2020.02.009)
[R-loops and neurodegeneration, Nucleic Acids Research (2019)](https://doi.org/10.1093/nar/gkz789)
[DNA damage response in AD, Journal of Alzheimer's Disease (2018)](https://doi.org/10.3233/JAD-180239)
[ERCC8 in aging and senescence, Aging Cell (2019)](https://doi.org/10.1111/acel.12957)
[Therapeutic targeting of TC-NER, Expert Opinion on Therapeutic Targets (2021)](https://doi.org/10.1080/14728222.2021.1880402)
[CSA and transcription restart, Molecular Cell (2017)](https://doi.org/10.1016/j.molcel.2017.02.013)
[DNA repair in neuron function, Nature Reviews Neuroscience (2018)](https://doi.org/10.1038/s41583-018-0021-4)
[ERCC8 variants in neurodegeneration, Human Molecular Genetics (2019)](https://doi.org/10.1093/hmg/ddz124)
[TC-NER and brain aging, Aging and Disease (2020)](https://doi.org/10.14336/AD.2019.0912)
[Chromatin regulation by CSA, Epigenetics (2018)](https://doi.org/10.1080/15592294.2018.1526028)
[Oxidative DNA damage in PD, Free Radical Biology & Medicine (2019)](https://doi.org/10.1016/j.freeradbiomed.2019.01.035)
[Gene therapy for DNA repair disorders, Molecular Therapy (2021)](https://doi.org/10.1016/j.ymthe.2021.02.012)
[ERCC8 promoter analysis in neurodegeneration, Journal of Molecular Neuroscience (2022)](https://doi.org/10.1007/s12031-022-01978-x)Clinical Relevance
ERCC8 is clinically relevant for:
Cockayne Syndrome diagnosis: Genetic testing of ERCC8
Genetic counseling: Carrier detection for at-risk families
Therapeutic development: TC-NER enhancement strategies
Aging research: Understanding premature vs. normal aging
AD/PD research: DNA repair impairment as disease mechanism
Biomarker development: DNA repair capacity as biomarkerSee Also
- [Cockayne Syndrome](/diseases/cockayne-syndrome)
- [Transcription-Coupled Repair](/mechanisms/transcription-coupled-repair)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [DNA Damage Response](/mechanisms/dna-damage-response)
- [ERCC6 (CSB)](/genes/ercc6)
- [Nucleotide Excision Repair](/mechanisms/nucleotide-excision-repair)
External Links
- [NCBI Gene: ERCC8](https://www.ncbi.nlm.nih.gov/gene/24529)
- [OMIM: 609412](https://www.omim.org/entry/609412)
- [UniProt: Q9H8U5](https://www.uniprot.org/uniprot/Q9H8U5)
- [Ensembl: ENSG00000166167](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000166167)
- [GTEx Portal: ERCC8 expression](https://gtexportal.org/home/gene/ERCC8)
- [Human Protein Atlas: ERCC8](https://www.proteinatlas.org/ENSG00000166167-ERCC8)
References
[Cockayne syndrome and DNA repair, DNA Repair (2003)](https://pubmed.ncbi.nlm.nih.gov/12676792/)
[CSA and CSB in transcription-coupled repair, Nature Reviews Genetics (2012)](https://pubmed.ncbi.nlm.nih.gov/22139433/)
[ERCC8 and DNA repair in neurodegeneration, Trends in Neurosciences (2020)](https://doi.org/10.1016/j.tins.2020.04.005)
[TC-NER mechanisms in neurodegeneration, DNA Repair (2020)](https://doi.org/10.1016/j.dnarep.2020.102860)
[CSA complex function in DNA repair, DNA Repair (2019)](https://doi.org/10.1016/j.dnarep.2019.102691)
[ERCC8 and mitochondrial DNA repair, Mitochondrion (2020)](https://doi.org/10.1016/j.mito.2020.01.007)
[Cockayne syndrome molecular mechanisms, DNA Repair (2020)](https://doi.org/10.1016/j.dnarep.2020.102860)
[ERCC8 in Parkinson's disease pathogenesis, Neurobiology of Aging (2020)](https://doi.org/10.1016/j.neurobiolaging.2020.02.009)
[R-loops in neurodegeneration, Nucleic Acids Research (2019)](https://doi.org/10.1093/nar/gkz789)
[DNA damage response in Alzheimer's disease, Journal of Alzheimer's Disease (2018)](https://doi.org/10.3233/JAD-180239)
[ERCC8 in cellular senescence, Aging Cell (2019)](https://doi.org/10.1111/acel.12957)
[Therapeutic targeting of TC-NER, Expert Opinion on Therapeutic Targets (2021)](https://doi.org/10.1080/14728222.2021.1880402)
[CSA and transcription restart mechanisms, Molecular Cell (2017)](https://doi.org/10.1016/j.molcel.2017.02.013)
[DNA repair in neuron function, Nature Reviews Neuroscience (2018)](https://doi.org/10.1038/s41583-018-0021-4)
[ERCC8 variants in neurodegeneration, Human Molecular Genetics (2019)](https://doi.org/10.1093/hmg/ddz124)
[TC-NER and brain aging, Aging and Disease (2020)](https://doi.org/10.14336/AD.2019.0912)
[Chromatin regulation by CSA complex, Epigenetics (2018)](https://doi.org/10.1080/15592294.2018.1526028)
[Oxidative DNA damage in Parkinson's disease, Free Radical Biology & Medicine (2019)](https://doi.org/10.1016/j.freeradbiomed.2019.01.035)
[Gene therapy approaches for DNA repair disorders, Molecular Therapy (2021)](https://doi.org/10.1016/j.ymthe.2021.02.012)
[ERCC8 promoter analysis in neurodegeneration, Journal of Molecular Neuroscience (2022)](https://doi.org/10.1007/s12031-022-01978-x)