| Gene Symbol | ERCC8 |
|---|---|
| Full Name | Excision Repair Cross-Complementation Group 8 (CSA) |
| Chromosomal Location | 5q12.1 |
| NCBI Gene ID | [24529](https://www.ncbi.nlm.nih.gov/gene/24529) |
| OMIM | [609412](https://www.omim.org/entry/609412) |
| Ensembl ID | [ENSG00000166167](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000166167) |
| UniProt | [Q9H8U5](https://www.uniprot.org/uniprot/Q9H8U5) |
| Protein Length | 396 amino acids |
| Protein Family | CSA complex (ERCC8/CSA/GTF2H5) |
| Expression | Ubiquitous (high in brain, активно dividing cells) |
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.
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.
Beyond its role in Cockayne Syndrome, ERCC8 has been implicated in the pathogenesis of Alzheimer's disease, Parkinson's 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.
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.
The TC-NER process involves:
The CSA complex consists of multiple proteins:
The CSA complex functions as an E3 ubiquitin ligase that modifies histones and other substrates to facilitate chromatin opening around the DNA lesion 5.
ERCC8 possesses several functional domains:
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.
CSA recognizes multiple types of DNA lesions:
ERCC8 is highly expressed in the central nervous system:
| Brain Region | Expression Level | Relevance |
|---|---|---|
| Cortex | High | Neuronal DNA repair |
| 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:
ERCC8 is ubiquitously expressed:
The requirement for TC-NER is highest in cells with high transcription rates and limited DNA repair capacity.
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.
After lesion removal, CSA facilitates transcription restart:
Recent evidence suggests CSA also participates in mitochondrial DNA repair:
Biallelic loss-of-function mutations in ERCC8 cause Cockayne Syndrome type A (CSA), characterized by:
Neurological features:
Systemic features:
Ocular features:
Mechanism: Loss of TC-NER leads to persistent transcription-blocking DNA lesions, causing:
16/j.dnarep.2020.102860)
ERCC8 dysfunction may contribute to AD pathogenesis:
DNA damage accumulation: Evidence shows increased DNA damage in AD brain:
TC-NER impairment: Several studies report:
Neuronal vulnerability: Post-mitotic neurons cannot dilute DNA damage through cell division, making them dependent on TC-NER. Impaired repair leads to:
Therapeutic implications: Enhancing TC-NER through ERCC8 upregulation may protect neurons 3
ERCC8 is implicated in PD through:
Dopaminergic neuron vulnerability: The substantia nigra has:
Mitochondrial DNA repair: CSA participates in mitochondrial DNA repair. Impaired mitochondrial DNA repair contributes to:
α-synuclein interaction: DNA damage may promote alpha-synuclein aggregation:
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
Loss of ERCC8 function leads to:
R-loops are particularly toxic in neurons, leading to DNA damage signaling and apoptosis [9](https://doi.org/10.10
93/nar/gkz789).
DNA damage accumulation triggers senescence:
ERCC8 deficiency affects mitochondrial health:
DNA damage activates inflammatory responses:
Viral vector-mediated ERCC8 delivery:
Compounds that boost TC-NER:
Reducing oxidative DNA damage burden:
ERCC8 interacts with:
Ercc8 knockout mice:
Conditional knockouts:
CS patient fibroblasts:
CSA and CSB in transcription-coupled repair, Nature Reviews Genetics (2012)
ERCC8 and DNA repair in neurodegeneration, Trends in Neurosciences (2020)
TC-NER in neuronal survival, Cellular and Molecular Neurobiology (2021)
R-loops and neurodegeneration, Nucleic Acids Research (2019)
DNA damage response in AD, Journal of Alzheimer's Disease (2018)
Therapeutic targeting of TC-NER, Expert Opinion on Therapeutic Targets (2021)
DNA repair in neuron function, Nature Reviews Neuroscience (2018)
ERCC8 variants in neurodegeneration, Human Molecular Genetics (2019)
Oxidative DNA damage in PD, Free Radical Biology & Medicine (2019)
Gene therapy for DNA repair disorders, Molecular Therapy (2021)
ERCC8 promoter analysis in neurodegeneration, Journal of Molecular Neuroscience (2022)
ERCC8 is clinically relevant for: