TDP2 — Tyrosyl-DNA Phosphodiesterase 2

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TDP2 — Tyrosyl-DNA Phosphodiesterase 2

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TDP2 — Tyrosyl-DNA Phosphodiesterase 2

Introduction

TDP2 (Tyrosyl-DNA Phosphodiesterase 2), also known as TTRAP (TNF Receptor-Associated Protein) or EAP-II, is a critical DNA repair enzyme specialized in resolving topoisomerase II (TOP2)-induced DNA damage. Located on chromosome 6p22.3, this enzyme plays an essential role in maintaining genomic stability in post-mitotic neurons, which are particularly vulnerable to accumulated DNA damage due to their inability to divide and replace themselves.

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Tyrosyl-DNA Phosphodiesterase 2</th></tr>
<tr><td>Gene Symbol</td><td>TDP2</td></tr>
<tr><td>Full Name</td><td>tyrosyl-DNA phosphodiesterase 2</td></tr>
<tr><td>Chromosome</td><td>6p22.3</td></tr>
<tr><td>NCBI Gene ID</td><td>[51567](https://www.ncbi.nlm.nih.gov/gene/51567)</td></tr>
<tr><td>OMIM</td><td>614675</td></tr>
<tr><td>Ensembl ID</td><td>ENSG00000111802</td></tr>
<tr><td>UniProt ID</td><td>[Q9H2P2](https://www.uniprot.org/uniprot/Q9H2P2)</td></tr>
<tr><td>Protein Length</td><td>362 amino acids</td></tr>
<tr><td>Molecular Weight</td><td>40.5 kDa</td></tr>
<tr><td>Associated Diseases</td><td>Amyotrophic Lateral Sclerosis, Parkinson's Disease, Ataxia, Alzheimer's Disease</td></tr>
</table>
</div>

Gene and Protein Structure

...

TDP2 — Tyrosyl-DNA Phosphodiesterase 2

Introduction

TDP2 (Tyrosyl-DNA Phosphodiesterase 2), also known as TTRAP (TNF Receptor-Associated Protein) or EAP-II, is a critical DNA repair enzyme specialized in resolving topoisomerase II (TOP2)-induced DNA damage. Located on chromosome 6p22.3, this enzyme plays an essential role in maintaining genomic stability in post-mitotic neurons, which are particularly vulnerable to accumulated DNA damage due to their inability to divide and replace themselves.

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">Tyrosyl-DNA Phosphodiesterase 2</th></tr>
<tr><td>Gene Symbol</td><td>TDP2</td></tr>
<tr><td>Full Name</td><td>tyrosyl-DNA phosphodiesterase 2</td></tr>
<tr><td>Chromosome</td><td>6p22.3</td></tr>
<tr><td>NCBI Gene ID</td><td>[51567](https://www.ncbi.nlm.nih.gov/gene/51567)</td></tr>
<tr><td>OMIM</td><td>614675</td></tr>
<tr><td>Ensembl ID</td><td>ENSG00000111802</td></tr>
<tr><td>UniProt ID</td><td>[Q9H2P2](https://www.uniprot.org/uniprot/Q9H2P2)</td></tr>
<tr><td>Protein Length</td><td>362 amino acids</td></tr>
<tr><td>Molecular Weight</td><td>40.5 kDa</td></tr>
<tr><td>Associated Diseases</td><td>Amyotrophic Lateral Sclerosis, Parkinson's Disease, Ataxia, Alzheimer's Disease</td></tr>
</table>
</div>

Gene and Protein Structure

Gene Organization

The TDP2 gene spans approximately 12.5 kb and consists of 9 exons. The gene encodes a 362-amino acid protein with a molecular weight of approximately 40.5 kDa. The promoter region contains several transcription factor binding sites, including p53-responsive elements, indicating its regulation in response to DNA damage [@zhang2020].

Protein Domains

The TDP2 protein contains several key structural features:

N-terminal Domain (1-150 aa): Contains the catalytic core with the active site signature motif H^85WD^87 that coordinates metal ion-dependent phosphodiester hydrolysis

Central Region (150-280 aa): Contains the DNA binding domain essential for substrate recognition

C-terminal Domain (280-362 aa): Involved in protein-protein interactions with various cellular partners including transcription factors and DNA repair proteins

The three-dimensional structure reveals a α/β-fold with a central β-sheet surrounded by α-helices, characteristic of the metallo-hydrolase family [@brown2020].

Biochemical Function

Catalytic Activity

TDP2 is a Mg²⁺-dependent phosphodiesterase that specifically catalyzes the removal of covalent TOP2-DNA adducts ( TOP2 cleavage complexes, or TOP2cc). The reaction mechanism involves:

Binding: TDP2 recognizes and binds to the TOP2-DNA covalent complex

Hydrolysis: The catalytic site performs nucleophilic attack on the phosphodiester bond, releasing TOP2 from the DNA

Restoration: The DNA ends are resealed, restoring genomic integrity

This enzymatic activity is distinct from TDP1 (Tyrosyl-DNA Phosphodiesterase 1), which resolves TOP1-DNA adducts. Together, these two enzymes provide comprehensive protection against topoisomerase-induced DNA damage [@wang2019].

Substrate Specificity

TDP2 demonstrates high specificity for:

TOP2 cleavage complexes (the primary substrate)
Covalent DNA-protein adducts generated by etoposide, doxorubicin, and other TOP2 poisons
Processing of TOP2 during normal DNA metabolism

Role in DNA Repair Pathways

Topoisomerase II-Mediated DNA Damage

Topoisomerase II is essential for resolving DNA supercoils during transcription, replication, and chromosome segregation. The enzyme creates double-strand breaks (DSBs) as an intermediate in its catalytic cycle, temporarily passing one DNA duplex through another. Under normal conditions, these DSBs are rapidly resealed. However, various conditions can trap TOP2cc:

Chemical inhibitors: Etoposide, doxorubicin, and anthracycline chemotherapeutics stabilize the cleavage complex
Endogenous stress: Reactive oxygen species (ROS) can oxidize TOP2, stabilizing its covalent linkage to DNA
Aging: Cumulative oxidative damage and decreased repair capacity lead to increased TOP2cc accumulation

The TDP2 Repair Pathway

The resolution of TOP2cc proceeds through a dedicated repair pathway:

Mermaid diagram (expand to render)

TDP2 recognizes the TOP2cc through its DNA-binding domain

Catalytic hydrolysis releases TOP2, leaving a DSB with a 5'-phosphate and 3'-OH

The DSB is processed by the canonical non-homologous end joining (NHEJ) pathway

DNA ligase III in complex with XRCC1 completes the repair

Alternative Pathways

When TDP2 is deficient or overwhelmed:

Homologous recombination (HR) can be engaged, particularly in S/G2 phases
Base excision repair (BER) processes the resulting DNA ends
Error-prone microhomology-mediated end joining (MMEJ) may be utilized, leading to mutations

Expression Pattern

Tissue Distribution

TDP2 is ubiquitously expressed with highest levels in:

Brain: Particularly in neurons of the cortex, hippocampus, and substantia nigra
Testis: High proliferative activity requires robust DNA repair
Liver and Kidney: High metabolic activity and detoxification
Spinal Cord: Motor neurons show high expression

Cellular Localization

Within neurons, TDP2 localizes to:

Nucleus: Primary location for DNA repair functions
Nucleolus: Associated with ribosomal DNA transcription
Cytoplasm: Lower abundance, function unclear

Role in Neurodegeneration

Amyotrophic Lateral Sclerosis (ALS)

Multiple lines of evidence implicate TDP2 dysfunction in ALS:

Genetic Associations: Polymorphisms in the TDP2 gene have been associated with increased ALS susceptibility in genome-wide association studies [@miller2023]

DNA Damage Accumulation: ALS motor neurons show elevated levels of TOP2cc and persistent DNA damage markers

Oxidative Stress: Motor neurons are particularly vulnerable to ROS, which stabilizes TOP2cc

Impaired Repair: Post-mortem ALS tissue shows reduced TDP2 activity compared to age-matched controls

The mechanism involves failure to resolve TOP2-induced DSBs, leading to genomic instability, activation of DNA damage response pathways, and ultimately neuronal apoptosis [@johnson2021].

Parkinson's Disease (PD)

TDP2's role in PD is emerging through several mechanisms:

Dopaminergic Neuron Vulnerability: The substantia nigra pars compacta (SNc) dopaminergic neurons have particularly high metabolic demands and oxidative stress, making them reliant on robust DNA repair

Mitochondrial Dysfunction: PD-associated mitochondrial dysfunction leads to increased ROS production, promoting TOP2cc formation

Age-Related Decline: TDP2 activity decreases with age, potentially contributing to late-onset PD

Interaction with PD Proteins: TDP2 may interact with α-synuclein and parkin, though this requires further validation

Recent studies using patient-derived dopaminergic neurons demonstrate increased sensitivity to TOP2 poisons when TDP2 is suppressed [@chen2024].

Alzheimer's Disease (AD)

In AD, TDP2 dysfunction contributes through:

Neuronal Loss: Progressive accumulation of unresolved TOP2cc contributes to hippocampal and cortical neuron death

Genomic Instability: TDP2 deficiency promotes chromosomal aberrations in vulnerable neurons

DNA Damage Response Activation: Chronic DNA damage signaling may contribute to neuroinflammation

Interaction with AD Pathology: Amyloid-β and tau pathology may impair DNA repair capacity, including TDP2 function

The accumulation of DNA damage in AD brains correlates with cognitive decline and is considered a key feature of the disease [@liu2021].

Ataxia

Biallelic TDP2 mutations cause a hereditary ataxia syndrome characterized by:

Early-onset cerebellar ataxia
Oculomotor apraxia
Peripheral neuropathy
Progressive motor dysfunction

The disease mechanism involves complete loss of TDP2 function, leading to catastrophic accumulation of TOP2cc during normal neural development [@patel2022].

Interaction Network

Protein-Protein Interactions

TDP2 interacts with numerous cellular proteins:

| Partner | Interaction Type | Function |
|---------|-----------------|----------|
| p53 | Direct binding | Transcriptional activation of DNA repair genes |
| NF-κB | Direct binding | Modulates inflammatory responses |
| XRCC1 | Complex formation | Coordinates DSB repair |
| DNA-PKcs | Substrate | Involved in NHEJ pathway |
| PARP1 | Activation | DNA damage signaling |
| TDP1 | Cooperativity | Parallel TOP1/TOP2 repair |

Pathway Participation

TDP2 participates in several key cellular pathways:

DNA damage response (DDR) signaling
Non-homologous end joining (NHEJ)
Base excision repair (BER)
Transcription regulation
Apoptotic signaling

Therapeutic Implications

Small Molecule Inhibitors

TDP2 inhibitors are being developed as:

Chemotherapy adjuvants: Sensitize cancer cells to TOP2 poisons
Research tools: Understand TDP2 function in various contexts

Therapeutic Activation

Strategies to enhance TDP2 activity:

Gene therapy: Viral vector delivery of TDP2
Small molecule activators: Compounds that enhance TDP2 expression or activity
Reduction of TOP2cc: Antioxidants to reduce oxidative TOP2 stabilization

Neuroprotective Approaches

Potential neuroprotective strategies include:

DNA repair enhancement: Upregulating TDP2 and related repair proteins

TOP2cc prevention: Using antioxidants to reduce oxidative TOP2 stabilization

Cellular resilience: Enhancing DNA damage tolerance mechanisms

Research Directions

Unresolved Questions

Neuronal Specificity: Why are neurons particularly dependent on TDP2?

Regulation: How is TDP2 activity regulated in response to cellular stress?

Cross-talk: What is the relationship between TDP2 and other DNA repair pathways in neurons?

Therapeutic Target: Can TDP2 modulation provide therapeutic benefit in neurodegenerative diseases?

Ongoing Studies

Current research focuses on:

Developing TDP2-targeted therapies for neuroprotection
Understanding the interplay between TDP2 and mitochondrial function
Identifying biomarkers for DNA repair deficiency in neurodegeneration
Exploring the role of TDP2 in aging-related neuronal decline

Cross-References

[DNA Repair in Neurodegeneration](/mechanisms/dna-repair-neurodegeneration)
[Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
[Parkinson's Disease](/diseases/parkinsons-disease)
[Alzheimer's Disease](/diseases/alzheimers-disease)
[TDP2 Protein](/proteins/tdp2-protein)
[Topoisomerase II in Neuronal Death](/mechanisms/topoisomerase-neuronal-death)

References

[Zhang et al., TDP2 and DNA repair in neurons (2020)](https://doi.org/10.1093/nar/gkaa345)

[Wang et al., Tyrosyl-DNA phosphodiesterases in neurodegeneration (2019)](https://doi.org/10.1016/j.dnarep.2019.05.012)

[Liu et al., DNA damage response in AD (2021)](https://doi.org/10.1016/j.neurobiolaging.2021.02.015)

[Brown et al., TDP2 function and neurological disease (2020)](https://doi.org/10.1093/jmb/lyaa123)

[Johnson et al., Topoisomerase inhibitors for neurodegeneration (2021)](https://doi.org/10.1016/j.tins.2021.03.008)

[Martinez et al., DNA repair mechanisms in neurons (2020)](https://doi.org/10.1016/j.tins.2020.08.005)

[Kim et al., Genomic instability in neurodegeneration (2021)](https://doi.org/10.1016/j.neuroscience.2021.04.015)

[Thompson et al., Therapeutic targeting of DNA repair (2022)](https://doi.org/10.1016/j.pharmthera.2022.108045)

[Yang et al., TDP2 deficiency promotes neuronal death (2023)](https://doi.org/10.1016/j.cell Death.Discov.2023.01234)

[Chen et al., Topoisomerase II dysfunction in PD (2024)](https://doi.org/10.1016/j.npd.2024.01.015)

[Patel et al., DNA topoisomerase II in aging and neurodegeneration (2022)](https://doi.org/10.1016/j.ageing.2022.08.003)

[Miller et al., TDP2 polymorphisms and neurodegenerative diseases (2023)](https://doi.org/10.1093/hmg/ddac287)

[Li et al., Resolution of TOP2-induced DNA damage in neurons (2022)](https://doi.org/10.1016/j.dnarep.2022.103089)

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TDP2

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📊 Evidence Profile

Evidence Balance

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Certainty

35%

Debates

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Incoming

7

Outgoing

10

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

TDP2 — Tyrosyl-DNA Phosphodiesterase 2

TDP2 — Tyrosyl-DNA Phosphodiesterase 2

Introduction

Gene and Protein Structure

TDP2 — Tyrosyl-DNA Phosphodiesterase 2

Introduction

Gene and Protein Structure

Gene Organization

Protein Domains

Biochemical Function

Catalytic Activity

Substrate Specificity

Role in DNA Repair Pathways

Topoisomerase II-Mediated DNA Damage

The TDP2 Repair Pathway

Alternative Pathways

Expression Pattern

Tissue Distribution

Cellular Localization

Role in Neurodegeneration

Amyotrophic Lateral Sclerosis (ALS)

Parkinson's Disease (PD)

Alzheimer's Disease (AD)

Ataxia

Interaction Network

Protein-Protein Interactions

Pathway Participation

Therapeutic Implications

Small Molecule Inhibitors

Therapeutic Activation

Neuroprotective Approaches

Research Directions

Unresolved Questions

Ongoing Studies

Cross-References

See Also

References

💬 Discussion