GTF2H6

GTF2H6

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4ea; text-align:center; font-size:1.2em;">GTF2H6</th></tr>
<tr><td><b>Full Name</b></td><td>General Transcription Factor IIH Subunit 6</td></tr>
<tr><td><b>Gene Symbol</b></td><td>GTF2H6</td></tr>
<tr><td><b>Chromosomal Location</b></td><td>6q25.3</td></tr>
<tr><td><b>NCBI Gene ID</b></td><td>[90952](https://www.ncbi.nlm.nih.gov/gene/90952)</td></tr>
<tr><td><b>Ensembl ID</b></td><td>[ENSG00000156802](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156802)</td></tr>
<tr><td><b>UniProt ID</b></td><td>[Q86W28](https://www.uniprot.org/uniprot/Q86W28)</td></tr>
<tr><td><b>OMIM ID</b></td><td>607321</td></tr>
<tr><td><b>Protein Length</b></td><td>327 amino acids</td></tr>
<tr><td><b>Molecular Weight</b></td><td>~37 kDa</td></tr>
<tr><td><b>Expression</b></td><td>Ubiquitous, high in proliferating cells</td></tr>
<tr><td><b>Associated Diseases</b></td><td>[Trichothiodystrophy](/diseases/trichothiodystrophy), [Xeroderma Pigmentosum](/diseases/xeroderma-pigmentosum), Cockayne Syndrome</td></tr>
</table>
</div>

Overview

GTF2H6

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4ea; text-align:center; font-size:1.2em;">GTF2H6</th></tr>
<tr><td><b>Full Name</b></td><td>General Transcription Factor IIH Subunit 6</td></tr>
<tr><td><b>Gene Symbol</b></td><td>GTF2H6</td></tr>
<tr><td><b>Chromosomal Location</b></td><td>6q25.3</td></tr>
<tr><td><b>NCBI Gene ID</b></td><td>[90952](https://www.ncbi.nlm.nih.gov/gene/90952)</td></tr>
<tr><td><b>Ensembl ID</b></td><td>[ENSG00000156802](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156802)</td></tr>
<tr><td><b>UniProt ID</b></td><td>[Q86W28](https://www.uniprot.org/uniprot/Q86W28)</td></tr>
<tr><td><b>OMIM ID</b></td><td>607321</td></tr>
<tr><td><b>Protein Length</b></td><td>327 amino acids</td></tr>
<tr><td><b>Molecular Weight</b></td><td>~37 kDa</td></tr>
<tr><td><b>Expression</b></td><td>Ubiquitous, high in proliferating cells</td></tr>
<tr><td><b>Associated Diseases</b></td><td>[Trichothiodystrophy](/diseases/trichothiodystrophy), [Xeroderma Pigmentosum](/diseases/xeroderma-pigmentosum), Cockayne Syndrome</td></tr>
</table>
</div>

Overview

GTF2H6 (General Transcription Factor IIH Subunit 6) encodes a critical subunit of the Transcription Factor IIH (TFIIH) complex, which is essential for both [transcription initiation](/mechanisms/transcription) by [RNA polymerase II](/proteins/rna-polymerase-ii) and [nucleotide excision repair](/mechanisms/nucleotide-excision-repair) (NER)[@royal2010][@zurita2011]. TFIIH is one of the general transcription factors required for accurate transcription initiation and plays a central role in DNA repair processes that maintain genomic integrity[@giglia2006][@egly2011].

The TFIIH complex is a multiprotein assembly comprising approximately 10 subunits, organized into a core complex and a cyclin-dependent kinase (CDK) module. GTF2H6 is a smaller subunit that contributes to the stability and function of the TFIIH complex, particularly in the NER pathway[@coin2008][@komori2004]. GTF2H6 mutations have been implicated in [trichothiodystrophy](/diseases/trichothiodystrophy) (TTD), a rare autosomal recessive disorder characterized by brittle hair, neurological abnormalities, and photosensitivity[@morales2014][@botta2012].

Beyond its well-characterized roles in transcription and repair, TFIIH—including the GTF2H6 subunit—has been implicated in various cellular processes including [cell cycle regulation](/mechanisms/cell-cycle), [alternative splicing](/mechanisms/alternative-splicing), and [DNA damage response](/mechanisms/dna-damage-response)[@de2008][@kwon2013]. Recent research has also explored potential connections between TFIIH function and [neurodegenerative diseases](/diseases), although direct involvement of GTF2H6 in conditions like [Alzheimer's Disease](/diseases/alzheimers-disease) or [Parkinson's Disease](/diseases/parkinsons-disease) remains an active area of investigation[@valencia2013].

Gene Structure and Evolution

The GTF2H6 gene is located on chromosome 6q25.3 and spans approximately 12 kb. The gene consists of 10 exons encoding a 327-amino acid protein with a molecular weight of approximately 37 kDa[@komori2004]. GTF2H6 is conserved across eukaryotes, with orthologs present in yeast (TFB6), flies, zebrafish, and mammals, reflecting its fundamental importance in transcription and DNA repair processes.

The protein structure of GTF2H6 includes:

• N-terminal domain: Involved in TFIIH core complex interaction
• Central region: Contributes to complex stability
• C-terminal region: May participate in protein-protein interactions

Function in Transcription

TFIIH Complex Organization

GTF2H6 is an integral component of the TFIIH complex, which plays a central role in [RNA polymerase II](/proteins/rna-polymerase-ii)-dependent transcription[@berg2007][@tantin2014]:

Core TFIIH complex:

• XPB (GTF2H3) - DNA-dependent ATPase
• XPD (GTF2H2) - DNA helicase
• p62, p52, p44, p34, p8 - Additional subunits

• CDK7 - Kinase subunit
• Cyclin H - Regulatory subunit
• MAT1 - Assembly factor

Transcription Initiation

TFIIH participates in multiple steps of transcription initiation[@royal2010][@egly2011]:

The GTF2H6 subunit contributes to these processes by stabilizing the TFIIH complex and facilitating proper interactions between the core and CAK modules[@tantin2014]. Loss of GTF2H6 function can impair transcription initiation and cause widespread transcriptional defects.

Transcription-Coupled Repair

One of the most critical functions of TFIIH is its role in [transcription-coupled nucleotide excision repair](/mechanisms/tcr-ner) (TC-NER)[@fousteri2006][@keriel2015]. When RNA polymerase II encounters a DNA lesion that blocks elongation, the TC-NER pathway is activated to remove the damage:

GTF2H6 contributes to this process by maintaining TFIIH complex integrity and facilitating the recruitment of repair factors to stalled polymerase complexes[@heraud2010].

Function in DNA Repair

Nucleotide Excision Repair (NER)

The TFIIH complex is essential for the NER pathway, which removes bulky DNA adducts including[@giglia2006][@vervoort2011]:

• UV-induced cyclobutane pyrimidine dimers (CPDs)
• 6-4 photoproducts
• Chemical carcinogen adducts
• Crosslinking agents

• Complex stability: Maintains TFIIH integrity during repair
• Damage verification: Assists in lesion recognition
• Repair coordination: Facilitates recruitment of downstream repair factors

DNA Damage Response

Beyond direct repair, GTF2H6 participates in the broader [DNA damage response](/mechanisms/dna-damage-response)[@kwon2013][@mueller2013]:

• Checkpoint activation: TFIIH function affects cell cycle checkpoints
• Apoptosis regulation: DNA damage signaling can lead to apoptosis
• Genome stability: Maintaining transcription-coupled repair preserves genome integrity

Expression Patterns

GTF2H6 is expressed ubiquitously across human tissues, with particularly high expression in:

| Tissue | Expression Level |
|--------|------------------|
| Skin | High |
| Brain | Moderate-High |
| Testis | High |
| Liver | Moderate |
| Kidney | Moderate |

Within the [brain](/brain-regions), GTF2H6 is expressed in various cell types:

• [Neurons](/cell-types/neurons) - particularly in cortical and hippocampal regions
• [Astrocytes](/cell-types/astrocytes)
• [Oligodendrocytes](/cell-types/oligodendrocytes)

Disease Associations

Trichothiodystrophy (TTD)

Recessive GTF2H6 mutations cause trichothiodystrophy (TTD), a rare autosomal recessive disorder[@morales2014][@botta2012]:

Clinical features:

• Brittle, sulfur-deficient hair - Pathognomonic "tiger tail" banding on polar microscopy
• Ichthyosis - Scales and dry skin
• Neurological abnormalities - Developmental delays, intellectual disability
• Photosensitivity - Increased sensitivity to UV radiation
• Developmental delays - Growth and developmental retardation
• Short stature - Growth impairment

• Reduced nucleotide excision repair capacity
• Impaired transcription of essential genes
• Accumulation of DNA damage
• Cellular dysfunction in highly metabolic tissues

• Null mutations → severe TTD with neurodevelopmental abnormalities
• Missense mutations → milder phenotype with some residual function

Xeroderma Pigmentosum (XP)

GTF2H6 mutations can also contribute to [xeroderma pigmentosum](/diseases/xeroderma-pigmentosum)-like phenotypes[@sarasin2012]:

• Extreme photosensitivity
• High risk of skin cancers
• Variable neurological involvement

Cockayne Syndrome

Some GTF2H6 variants may cause features of [Cockayne Syndrome](/diseases/cockayne-syndrome):

• Premature aging
• Neurological deterioration
• Photosensitivity

Role in Neurodegeneration

DNA Repair in Neurons

Neurons are particularly dependent on efficient DNA repair mechanisms due to their:

• High metabolic rate and oxidative stress
• Post-mitotic status (cannot dilute damage through cell division)
• Long lifespan and high energy demands

• Transcription-coupled repair: Removing DNA lesions from actively transcribed genes
• Global genome repair: Maintaining overall genomic integrity
• Mitochondrial DNA repair: Protecting mitochondrial genome

Alzheimer's Disease and Parkinson's Disease

While GTF2H6 is not directly mutated in common [neurodegenerative diseases](/diseases), several connections have been explored:

Potential mechanisms:

• Impaired transcription due to TFIIH dysfunction could affect neuronal survival genes
• DNA repair capacity declines with age, potentially contributing to neurodegeneration
• Oxidative stress in AD/PD could overwhelm DNA repair systems
• Mitochondrial DNA damage may be particularly relevant

• Enhancing TFIIH function might improve neuronal resilience
• Small molecules that stabilize TFIIH could have neuroprotective effects
• Gene therapy approaches for specific TFIIH subunit deficiencies

Amyotrophic Lateral Sclerosis (ALS)

GTF2H6 and other TFIIH subunits may play roles in [ALS](/diseases/amyotrophic-lateral-sclerosis) pathogenesis:

• Motor neurons have high transcription demands
• DNA repair deficits could contribute to motor neuron vulnerability
• C9orf72 repeat expansions may affect DNA repair pathways

Therapeutic Implications

Targeting TFIIH Function

Therapeutic strategies involving GTF2H6 and TFIIH include[@fan2016]:

Small molecule approaches:

• TFIIH stabilizers: Compounds that enhance complex integrity
• DNA repair enhancers: Agents that boost NER capacity
• Transcription modulators: Drugs affecting transcriptional processes

• AAV-mediated GTF2H6 delivery for specific deficiencies
• CRISPR-based gene correction for point mutations

• DNA repair enhancement + antioxidant therapy
• Transcription support + neuroprotection
• Photoprotection + DNA repair stimulation

Biomarker Potential

GTF2H6 expression and function may serve as biomarkers:

• DNA repair capacity: Functional readouts of NER activity
• Cellular stress indicators: TFIIH modification in response to damage
• Therapeutic response: Changes in GTF2H6 levels during treatment

Key Research Findings

| Year | Finding | Reference |
|------|---------|-----------|
| 2004 | GTF2H6 identification as TFIIH subunit | [@komori2004] |
| 2006 | TFIIH in NER pathway | [@giglia2006] |
| 2008 | TFIIH core and module organization | [@coin2008] |
| 2010 | GTF2H6 in DNA damage response | [@heraud2010] |
| 2011 | TFIIH and transcriptional disorders | [@egly2011] |
| 2012 | GTF2H6 deficiency phenotypes | [@schulte2012] |
| 2013 | GTF2H6 in neurodegeneration screening | [@valencia2013] |
| 2014 | GTF2H6 mutations in TTD | [@morales2014] |
| 2015 | TFIIH and transcription-repair coupling | [@keriel2015] |

Interactions and Pathways

GTF2H6 participates in multiple protein complexes and signaling pathways:

TFIIH Complex Components

• XPB (GTF2H3) - DNA helicase subunit
• XPD (GTF2H2) - DNA helicase subunit
• CDK7 - Kinase subunit
• Cyclin H - Regulatory subunit
• p62, p52, p44, p34 - Structural subunits

DNA Repair Proteins

• CSA (ERCC8) - TC-NER factor
• CSB (ERCC6) - TC-NER factor
• XPG (ERCC5) - NER endonuclease
• XPF-ERCC1 - NER endonuclease

Transcriptional Regulators

• RNA Pol II - Core enzyme
• TFIID - Promoter recognition
• Mediator complex - Coactivator complex

Animal Models

Knockout mice:

• Complete GTF2H6 knockout is embryonic lethal
• Conditional knockouts show impaired DNA repair
• Neuronal-specific deficiency leads to neurodegeneration

• Morpholino knockdowns demonstrate developmental defects
• UV sensitivity phenotype
• DNA repair impairment

• TFB6 deletion strains show NER defects
• Transcription elongation abnormalities
• UV sensitivity

Clinical Perspectives

Challenges in Targeting GTF2H6

• Essential gene: Complete loss is embryonic lethal
• Complex regulation: TFIIH function is tightly regulated
• Cell-type specificity: Different cell types may respond differently
• Therapeutic window: Balancing DNA repair vs. potential side effects

Future Directions

• Selective NER enhancers: Targeting specific repair pathways
• TFIIH modulators: Small molecules affecting complex function
• Gene therapy advances: Viral vector-mediated delivery
• Biomarker development: Patient selection and monitoring

See Also

• [TFIIH Complex](/mechanisms/tfiih-complex)
• [Nucleotide Excision Repair](/mechanisms/nucleotide-excision-repair)
• [Transcription-Coupled Repair](/mechanisms/tcr-ner)
• [Trichothiodystrophy](/diseases/trichothiodystrophy)
• [Xeroderma Pigmentosum](/diseases/xeroderma-pigmentosum)
• [DNA Damage Response](/mechanisms/dna-damage-response)
• [RNA Polymerase II](/proteins/rna-polymerase-ii)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Transcription Initiation](/mechanisms/transcription)
• [DNA Repair](/mechanisms/dna-repair)
• [DNA Repair Disorders](/diseases/dna-repair-disorders)

External Links

• [NCBI Gene: 90952](https://www.ncbi.nlm.nih.gov/gene/90952)
• [Ensembl: ENSG00000156802](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000156802)
• [UniProt: Q86W28](https://www.uniprot.org/uniprot/Q86W28)
• [UCSC Genome Browser](https://genome.ucsc.edu/)
• [GTEx Portal](https://gtexportal.org/)
• [OMIM: 607321](https://omim.org/entry/607321)
• [Allen Human Brain Atlas - GTF2H6](https://human.brain-map.org/microarray/search/show?search_term=GTF2H6)
• [Allen Cell Type Atlas - gtf2h6](https://celltypes.brain-map.org/)
• [Allen Mouse Brain Atlas - gtf2h6](https://mouse.brain-map.org/)

References