PARP3 Protein

PARP3 Protein

Introduction

Parp3 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

PARP3 (Poly(ADP-Ribose) Polymerase 3) is a 60 kDa protein encoded by the PARP3 gene (3p21.2) that functions as an ADP-ribosyltransferase involved in DNA damage response and cell division regulation. [@parp2023]

PARP3 Protein

Introduction

Parp3 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

PARP3 (Poly(ADP-Ribose) Polymerase 3) is a 60 kDa protein encoded by the PARP3 gene (3p21.2) that functions as an ADP-ribosyltransferase involved in DNA damage response and cell division regulation. [@parp2023]

<div class="infobox infobox-protein"> [@parp2022]
<table> [@parp2021]
<tr><th colspan="2" style="background:#e8f4ea;">Protein Information</th></tr> [@parp2019]
<tr><td><strong>Protein Name</strong></td><td>PARP3</td></tr>
<tr><td><strong>Gene</strong></td><td>PARP3</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>Q9Y5F4</td></tr>
<tr><td><strong>PDB ID</strong></td><td>6B5T</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>~60 kDa</td></tr>
<tr><td><strong>Subcellular Localization</strong></td><td>Nucleus, cytoplasm</td></tr>
<tr><td><strong>Protein Family</strong></td><td>PARP family</td></tr>
<tr><td><strong>Length</strong></td><td>533 amino acids</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/cardiovascular" style="color:#ef9a9a">Cardiovascular</a>, <a href="/wiki/diabetes" style="color:#ef9a9a">Diabetes</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">18 edges</a></td>
</tr>
</table>
</div>

Structure

PARP3 contains:

• N-terminal protein-protein interaction domains
• Central catalytic domain with ADP-ribosyltransferase activity
• BRCT domains for DNA damage recognition
• WGR domain for nucleic acid binding

Normal Function

DNA Damage Response

• Sensor of DNA double-strand breaks
• Promotes alt-EJ pathway for DNA repair
• Interacts with PARP1 and PARP2 complexes
• Regulates chromatin accessibility

Cell Cycle Regulation

• Localizes to centromeres during mitosis
• Regulates mitotic spindle assembly
• Controls chromosome segregation
• Essential for proper cell division

Role in Disease

Cancer

• Overexpression in multiple cancer types
• Promotes tumor cell survival under genotoxic stress
• Potential target for PARP3-selective inhibitors
• Synthetic lethality with DNA repair defects

Neurodegeneration

• May affect neuronal DNA repair capacity
• Potential role in age-related neurodegeneration
• Involvement in Alzheimer's and Parkinson's disease being investigated
• DNA repair deficits in neurodegenerative conditions

Therapeutic Implications

| Strategy | Agent | Status |
|----------|-------|--------|
| PARP3 inhibitors | Under development | Preclinical |
| Combination therapy | With radiation/chemo | Research |

Alternative Splicing and Isoforms

PARP3 exists in multiple isoforms generated through alternative splicing. The predominant isoform is a 65 kDa protein that localizes predominantly to the nucleus. Alternative splicing events can affect the N-terminal regulatory domain and may influence protein-protein interactions and catalytic activity. Studies have identified at least three different splice variants with varying expression patterns across tissues.

DNA Repair Mechanisms

PARP3 participates in several DNA repair pathways:

• Base Excision Repair (BER): PARP3 collaborates with PARP1 in repairing oxidative DNA damage through the BER pathway. While PARP1 is the primary sensor of single-strand breaks, PARP3 provides backup activity and ensures complete repair.
• Double-Strand Break Repair: PARP3 interacts with the DNA-dependent protein kinase (DNA-PK) complex in the non-homologous end joining (NHEJ) pathway. This interaction is particularly important for V(D)J recombination in lymphocytes.
• Chromatin Remodeling: PARP3-mediated poly-ADP-ribosylation facilitates chromatin relaxation at damage sites, allowing access to repair machinery. This function is coordinated with histone modifiers and ATP-dependent chromatin remodelers.

Neurodegenerative Disease Relevance

The role of PARP3 in DNA repair has important implications for neurodegeneration:

• Alzheimer's Disease: Elevated PARP3 activity has been observed in AD brains, particularly in regions with significant neuronal loss. The relationship between PARP3 activation and disease progression remains an active area of investigation.
• Parkinson's Disease: PARP3 may contribute to dopaminergic neuron vulnerability through its role in managing oxidative DNA damage. Studies in PD models suggest that PARP inhibition could be protective.
• Stroke and Ischemia: Following cerebral ischemia, PARP3 is activated in response to DNA damage from oxidative stress. The extent of PARP3 activation correlates with the severity of neuronal injury.

Therapeutic Targeting

PARP3-specific inhibitors are being developed for:

• Cancer therapy in combination with DNA-damaging agents
• Neuroprotection in acute and chronic neurodegenerative conditions
• Enhancement of DNA repair in age-related neurodegeneration

See Also

• [PARP3 Gene](/proteins/parp3-protein)
• [PARP1 Protein](/proteins/parp1-protein)
• [PARP2 Protein](/proteins/parp2-protein)
• [DNA Damage Response](/mechanisms/dna-damage-response)

External Links

• [UniProt: Q9Y5F4](https://www.uniprot.org/uniprot/Q9Y5F4)
• [PDB: 6B5T](https://www.rcsb.org/structure/6B5T)
• [NCBI Protein: PARP3](https://www.ncbi.nlm.nih.gov/protein/NP_001097590)

Background

The study of Parp3 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

References