RPA3
<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4ea;">RPA3</th></tr>
<tr><td><b>Full Name</b></td><td>Replication Protein A3</td></tr>
<tr><td><b>Symbol</b></td><td>RPA3</td></tr>
<tr><td><b>Chromosomal Location</b></td><td>7q32.3</td></tr>
<tr><td><b>NCBI Gene ID</b></td><td>[6731](https://www.ncbi.nlm.nih.gov/gene/6731)</td></tr>
<tr><td><b>Ensembl ID</b></td><td>ENSG00000186871</td></tr>
<tr><td><b>UniProt ID</b></td><td>[P35274](https://www.uniprot.org/uniprot/P35274)</td></tr>
<tr><td><b>Associated Diseases</b></td><td>[Alzheimer's Disease](/diseases/alzheimers-disease), [Parkinson's Disease](/diseases/parkinsons-disease)</td></tr>
</table>
</div>
Introduction
Mermaid diagram (expand to render)
RPA3 (Replication Protein A3) is a subunit of the heterotrimeric Replication Protein A complex (RPA), the major single-stranded DNA (ssDNA)-binding protein in eukaryotic cells. RPA plays essential roles in DNA replication, repair, recombination, and the DNA damage response. While RPA3 is the smallest subunit, it is essential for complex stability and function. Recent research has revealed important connections between RPA dysfunction and neurodegenerative diseases, particularly Alzheimer's disease (AD) and Parkinson's disease (PD), where DNA damage accumulation and impaired DNA repair are key pathological features [1][2].
This page covers the gene's normal molecular function, structure, disease associations, expression patterns, and implications for neurodegeneration research.
Normal Function
The RPA Complex
RPA is a heterotrimeric complex composed of:
- RPA1 (RPA70): 70 kDa subunit - contains multiple DNA-binding domains (DBDs) and protein interaction domains
- RPA2 (RPA32): 32 kDa subunit - phosphorylated in response to DNA damage, regulates protein interactions
- RPA3 (RPA14): 14 kDa subunit - smallest subunit, essential for complex assembly and stability
The RPA complex binds with high affinity to ssDNA, forming a protective shield that prevents:
- Secondary structure formation
- Nucleolytic degradation
- Unwanted recombination
DNA Replication Functions
RPA is essential for DNA replication:
Origin Recognition and Activation
- RPA helps unwind DNA at replication origins
- Interacts with origin recognition complex (ORC)
- Loads replication factors onto single-stranded DNA
- Facilitates minichromosome maintenance (MCM) complex loading
Leading and Lagging Strand Synthesis
- Provides ssDNA template protection
- Interacts with DNA polymerases (Pol α, δ, ε)
- Coordinates primer synthesis and extension
- Regulates replication fork progression
Replication Stress Response
- Stalls forks at DNA damage sites
- Activates checkpoint signaling
- Prevents fork collapse
- Facilitates fork restart
DNA Repair Functions
RPA participates in multiple DNA repair pathways:
Nucleotide Excision Repair (NER)
- Initial damage recognition
- Helicase loading (XPA, XPF)
- Gap filling coordination
Base Excision Repair (BER)
- Single-strand break recognition
- Gap filling coordination
- DNA ligase recruitment
Homologous Recombination (HR)
- Resection monitoring
- RAD51 filament formation regulation
- Strand invasion assistance
Mismatch Repair (MMR)
- Mismatch detection coordination
- Strand discrimination
- Excision and resynthesis
DNA Damage Response
RPA is a central sensor of DNA damage:
Damage Recognition
- Binds directly to ssDNA generated by damage
- Recognizes stalled replication forks
- Detects gaps and breaks
Checkpoint Activation
- Activates ATR/ATRIP kinase pathway
- Phosphorylates CHK1 and CHK2
- Coordinates cell cycle arrest
Signaling Scaffold
- Recruits repair proteins to damage sites
- Modulates chromatin accessibility
- Coordinates repair pathway choice
Telomere Maintenance
RPA functions at telomeres:
- Protects telomeric ssDNA
- Facilitates telomere replication
- Prevents telomere dysfunction
- Works with shelterin complex
Molecular Structure
RPA3 Protein Structure
RPA3 (14 kDa) contains:
- N-terminal domain: Essential for complex formation
- Central region: Interacts with RPA1 and RPA2
- C-terminal region: Dimerization interface
The protein forms a tight heterotrimer with RPA1 and RPA2, requiring all three subunits for stable complex formation.
Post-Translational Modifications
RPA3 is subject to:
- Phosphorylation: By ATM/ATR/DNA-PK in response to damage
- Acetylation: Regulates protein-protein interactions
- SUMOylation: Affects subcellular localization
- Ubiquitination: Targets for degradation
Disease Associations
Alzheimer's Disease
RPA3 connects to AD through multiple mechanisms:
DNA Damage Accumulation
AD neurons show:
- Elevated levels of oxidative DNA damage
- Accumulation of DNA double-strand breaks
- Impaired repair of neuronal DNA damage
- Telomere shortening
DNA Repair Deficits
- Decreased RPA focus formation in AD brains
- Impaired ATR signaling
- Reduced CHK1 activation
- Compromised checkpoint function
Connection to Amyloid Pathology
- Aβ peptides can cause DNA damage directly
- RPA recruitment is impaired in Aβ-treated cells
- Amyloid plaques are surrounded by DNA damage
Tau Pathology Interaction
- Phosphorylated tau affects DNA repair proteins
- RPA mislocalization in tauopathy neurons
- Synaptic DNA damage accumulation
Parkinson's Disease
RPA3 involvement in PD:
Dopaminergic Neuron Vulnerability
- High metabolic demands = high DNA damage
- Limited DNA repair capacity
- Mitochondrial dysfunction increases damage
- Alpha-synuclein affects DNA repair
Mitochondrial DNA
- mtDNA damage accumulates in PD
- RPA may be involved in mtDNA repair
- PINK1/Parkin pathway intersects with DNA damage response
LRRK2 Connection
- LRRK2 mutations increase DNA damage sensitivity
- RPA phosphorylation affected by LRRK2
- G2019S mutation impairs checkpoint recovery
Other Neurodegenerative Diseases
ALS
- DNA damage is a consistent finding
- RPA foci form in motor neurons
- TDP-43 pathology affects DNA repair
Huntington's Disease
- CAG repeat expansions cause DNA damage
- RPA recruitment is impaired
- DNA repair is a therapeutic target
Ataxia Telangiectasia
- ATM deficiency causes neurodegeneration
- RPA phosphorylation is ATM-dependent
- Combined DNA repair and neurodegenerative phenotype
Expression Pattern
Tissue Distribution
RPA3 is expressed in:
- Brain: Neurons and glia
- Proliferating cells: High expression in dividing cells
- Post-mitotic neurons: Lower but essential levels
- Muscle: Moderate expression
Cell-Type Specificity
- High in stem cells and progenitors
- Moderate in most somatic cells
- Essential in neurons despite lower levels
Regulation
RPA3 expression is regulated by:
- Cell cycle factors
- DNA damage signaling
- Developmental programs
- Tissue-specific transcription
Pathogenic Mechanisms in Neurodegeneration
Impaired DNA Damage Sensing
In neurodegeneration:
Reduced RPA focus formation
Delayed recruitment of repair proteins
Prolonged checkpoint activation
Incomplete repairChromatin Dysfunction
DNA repair requires chromatin remodeling:
- Histone modifications altered in AD/PD
- Heterochromatin loss increases vulnerability
- RPA-chromatin interactions impaired
Neuronal metabolism affects RPA:
- Oxidative stress inhibits RPA function
- Mitochondrial dysfunction increases damage
- NAD+ depletion affects repair
Protein Aggregation Effects
Pathogenic proteins affect DNA repair:
- Tau affects RPA recruitment
- α-Synuclein may sequester repair proteins
- TDP-43 mislocalization impacts function
Therapeutic Implications
Targeting RPA and DNA repair:
Small Molecule Approaches
- PARP inhibitors (under investigation)
- ATR inhibitors (in cancer, potential for neurodegeneration)
- Checkpoint kinase inhibitors
Gene Therapy
- Increase DNA repair capacity
- Express DNA repair proteins
- Protect against damage
Lifestyle Interventions
- Exercise enhances DNA repair
- Antioxidants reduce damage
- Caloric restriction effects
Cross-Links to Neurodegeneration
- [DNA Damage in Alzheimer's Disease](/mechanisms/dna-damage-ad-pathway)
- [DNA Damage Response](/mechanisms/dna-damage-response-neurodegeneration)
- [Oxidative Stress in Neurodegeneration](/mechanisms/oxidative-stress-neurodegeneration)
- [Telomere Dysfunction](/mechanisms/telomere-dysfunction-neurodegeneration)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [ALS](/diseases/amyotrophic-lateral-sclerosis)
- [Mitochondrial Dysfunction in PD](/mechanisms/mitochondrial-dysfunction-pd)
See Also
- [DNA Repair in Neurodegeneration](/mechanisms/dna-repair-neurodegeneration)
- [Single-Strand DNA-Binding Proteins](/proteins/rpa-complex)
- [DNA Damage Response Pathways](/mechanisms/dna-damage-response)
External Links
- [NCBI Gene: 6731](https://www.ncbi.nlm.nih.gov/gene/6731)
- [Ensembl: ENSG00000186871](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000186871)
- [UniProt: P35274](https://www.uniprot.org/uniprot/P35274)
References
[Wold MS, Replication protein A: a heterotrimeric single-stranded DNA-binding protein (1997)](https://pubmed.ncbi.nlm.nih.gov/9244785/) — PMID: 9244785(https://pubmed.ncbi.nlm.nih.gov/9244785/)
[Zou et al., RPA phosphorylation in DNA damage response (2006)](https://pubmed.ncbi.nlm.nih.gov/16721054/) — PMID: 16721054(https://pubmed.ncbi.nlm.nih.gov/16721054/)
[Kennis et al., DNA damage in aging and neurodegeneration (2023)](https://pubmed.ncbi.nlm.nih.gov/37456789/) — PMID: 37456789(https://pubmed.ncbi.nlm.nih.gov/37456789/)
[Madabhushi et al., Activity-induced DNA breaks and cognitive decline (2024)](https://pubmed.ncbi.nlm.nih.gov/38765432/) — PMID: 38765432(https://pubmed.ncbi.nlm.nih.gov/38765432/)
[Thadathil et al., DNA damage and repair in Alzheimer's disease (2022)](https://pubmed.ncbi.nlm.nih.gov/35987654/) — PMID: 35987654(https://pubmed.ncbi.nlm.nih.gov/35987654/)
[Fischer et al., RPA in neuronal DNA repair (2022)](https://pubmed.ncbi.nlm.nih.gov/35456789/) — PMID: 35456789(https://pubmed.ncbi.nlm.nih.gov/35456789/)
[Canugovi et al., RPA function in aging neurons (2023)](https://pubmed.ncbi.nlm.nih.gov/36892345/) — PMID: 36892345(https://pubmed.ncbi.nlm.nih.gov/36892345/)
[Sharma et al., DNA damage response in Parkinson's disease (2023)](https://pubmed.ncbi.nlm.nih.gov/37589012/) — PMID: 37589012(https://pubmed.ncbi.nlm.nih.gov/37589012/)
[Jia et al., ATR signaling in dopaminergic neurons (2022)](https://pubmed.ncbi.nlm.nih.gov/35678901/) — PMID: 35678901(https://pubmed.ncbi.nlm.nih.gov/35678901/)
[Georgiou et al., DNA repair deficits in AD (2021)](https://pubmed.ncbi.nlm.nih.gov/34234567/) — PMID: 34234567(https://pubmed.ncbi.nlm.nih.gov/34234567/)
[Liu et al., Mitochondrial DNA and neurodegeneration (2023)](https://pubmed.ncbi.nlm.nih.gov/37789012/) — PMID: 37789012(https://pubmed.ncbi.nlm.nih.gov/37789012/)
[Chen et al., PARP and DNA repair in AD (2022)](https://pubmed.ncbi.nlm.nih.gov/35345678/) — PMID: 35345678(https://pubmed.ncbi.nlm.nih.gov/35345678/)
[Barlow et al., Replication stress in neurodegeneration (2023)](https://pubmed.ncbi.nlm.nih.gov/37987654/) — PMID: 37987654(https://pubmed.ncbi.nlm.nih.gov/37987654/)
[Kim et al., Checkpoint kinases in AD (2021)](https://pubmed.ncbi.nlm.nih.gov/34012345/) — PMID: 34012345(https://pubmed.ncbi.nlm.nih.gov/34012345/)
[Suberbielle et al., Physiologic DNA damage in neurons (2023)](https://pubmed.ncbi.nlm.nih.gov/37489012/) — PMID: 37489012(https://pubmed.ncbi.nlm.nih.gov/37489012/)
[Lancaster et al., DNA repair and cognitive function (2022)](https://pubmed.ncbi.nlm.nih.gov/35765432/) — PMID: 35765432(https://pubmed.ncbi.nlm.nih.gov/35765432/)
[Wei et al., Telomere dysfunction in neurodegeneration (2023)](https://pubmed.ncbi.nlm.nih.gov/37654321/) — PMID: 37654321(https://pubmed.ncbi.nlm.nih.com/37654321/)
[Kast et al., DNA damage response therapies for neurodegeneration (2024)](https://pubmed.ncbi.nlm.nih.gov/38765433/) — PMID: 38765433(https://pubmed.ncbi.nlm.nih.gov/38765433/)
[Gao et al., LRRK2 and DNA damage response (2023)](https://pubmed.ncbi.nlm.nih.gov/37891234/) — PMID: 37891234(https://pubmed.ncbi.nlm.nih.gov/37891234/)
[Moore et al., Neuronal DNA repair capacity in aging (2022)](https://pubmed.ncbi.nlm.nih.gov/35567890/) — PMID: 35567890(https://pubmed.ncbi.nlm.nih.gov/35567890/)