ERCC3 Gene

Overview

flowchart TD
    ERCC3["ERCC3"] -->|"risk factor for"| Hepatocellular_Carcinoma["Hepatocellular Carcinoma"]
    ERCC3["ERCC3"] -->|"contributes to"| Hepatocellular_Carcinoma["Hepatocellular Carcinoma"]
    ERCC3["ERCC3"] -->|"activates"| Cirrhosis["Cirrhosis"]
    ERCC3["ERCC3"] -->|"activates"| Carcinoma["Carcinoma"]
    ERCC3["ERCC3"] -->|"activates"| Ms["Ms"]
    ERCC3["ERCC3"] -->|"activates"| Als["Als"]
    ERCC3["ERCC3"] -->|"associated with"| Als["Als"]
    ERCC3["ERCC3"] -->|"associated with"| Carcinoma["Carcinoma"]
    ERCC3["ERCC3"] -->|"associated with"| Cirrhosis["Cirrhosis"]
    ERCC3["ERCC3"] -->|"activates"| CEBPB["CEBPB"]
    ERCC3["ERCC3"] -->|"activates"| PI3K["PI3K"]
    ERCC3["ERCC3"] -->|"activates"| EGFR["EGFR"]
    ERCC3["ERCC3"] -->|"activates"| MTOR["MTOR"]
    ERCC3["ERCC3"] -->|"activates"| CYP3A4["CYP3A4"]
    style ERCC3 fill:#4fc3f7,stroke:#333,color:#000

ERCC3 (Excision Repair Cross-Complementation Group 3), also known as TFIIH core component, is a DNA repair gene located on chromosome 19q13.32. The protein encodes a DNA helicase subunit of the transcription factor IIH (TFIIH) complex, which is essential for both transcription initiation and nucleotide excision repair (NER). ERCC3 plays a critical role in transcription-coupled nucleotide excision repair (TC-NER), a pathway that specifically repairs DNA lesions in actively transcribed genes.

Gene and Protein Structure

The ERCC3 gene spans approximately 15 kb and consists of 17 exons. It encodes a 782-amino acid protein with a molecular weight of approximately 89 kDa. The protein contains seven conserved motifs characteristic of the SF2 helicase family, including the ATP-dependent DNA helicase domain. ERCC3 forms a core component of the TFIIH complex, which contains both repair and transcription activities. ^{1TFIIH and transcription-coupled repair (2019)2019 · PMID 31199387Open reference}

Normal Function in the Nervous System

In the nervous system, ERCC3/TFIIH is essential for: ^{2ERCC3 polymorphisms and Alzheimer's disease risk (2014)2014 · PMID 24526841Open reference}

• Transcription initiation: ERCC3’s helicase activity unwinds DNA at the promoter region, allowing RNA polymerase II to initiate transcription of neuronal genes

• DNA repair: TC-NER removes bulky DNA lesions (UV-induced pyrimidine dimers, chemical adducts) that would otherwise block transcription

• Neuronal survival: Proper DNA repair maintains genomic integrity in post-mitotic neurons, which cannot undergo replication-based repair

Neurons are particularly dependent on TC-NER due to their high metabolic rate, oxidative stress exposure, and inability to replicate. ^{3DNA repair in neurodegenerative diseases (2022)2022 · PMID 35894223Open reference}

Role in Neurodegenerative Diseases

Cockayne Syndrome

Biallelic mutations in ERCC3 cause Cockayne syndrome (CS), a rare autosomal recessive disorder characterized by progressive neurodegeneration, developmental delay, photosensitivity, and premature aging. CS patients exhibit: ^{4TFIIH functions in brain development (2007)2007 · PMID 17535976Open reference}

• Severe neurological impairment with intellectual disability

• Cerebellar ataxia and motor dysfunction

• Peripheral neuropathy

• Cachexia

• Early onset neurodegeneration

CS is considered a segmental progeroid syndrome, sharing features with accelerated aging, including neurodegeneration.

Alzheimer’s Disease

ERCC3 polymorphisms have been associated with Alzheimer’s disease (AD) risk in genome-wide association studies (GWAS). The DNA repair capacity declines with age, and impaired TC-NER may contribute to:

• Accumulation of DNA damage in neurons

• Dysregulation of transcription of synaptic proteins

• Activation of DNA damage response pathways

• Neuroinflammation

Parkinson’s Disease

Evidence suggests ERCC3 variants may modify Parkinson’s disease (PD) risk. DNA repair mechanisms are crucial for maintaining dopaminergic neuron viability, as these cells face high oxidative stress from dopamine metabolism.

Therapeutic Implications

ERCC3 and the TFIIH complex represent potential therapeutic targets:

• Gene therapy: Delivering functional ERCC3 to neurons in CS patients

• Small molecule modulators: Enhancing TFIIH activity to improve DNA repair

• Antioxidant therapies: Reducing oxidative DNA damage burden

• Neuroprotective strategies: Supporting neuronal DNA repair capacity

Expression Patterns

ERCC3 is ubiquitously expressed in all human tissues, including:

• Brain: neurons, astrocytes, microglia, oligodendrocytes

• Highest expression in regions with high metabolic activity

• Expression decreases with age in brain tissue

Interactions and Pathways

ERCC3 interacts with:

• TFIIH complex: Core component (XPB, p62, p52, p44, p34, p8)

• CSA (ERCC8): Cockayne syndrome type A protein

• CSB (ERCC6): Cockayne syndrome type B protein

• RNA polymerase II: Co-transcriptional recruitment

• XPA, XPC: NER pathway proteins

Summary

ERCC3 is a critical DNA repair and transcription gene whose dysfunction leads to severe neurodegenerative phenotypes. Its role in maintaining genomic integrity in post-mitotic neurons makes it relevant to age-related neurodegenerative diseases including AD and PD.

• DNA Repair Pathways Syndrome

• DNA Repair Pathways TFIIH Complex

• Nucleotide Excision Repair

• Transcription-Coupled Repair

• Aging and Neurodegeneration

External Links

• NCBI Gene: ERCC3

• OMIM: ERCC3

• UniProt: ERCC3