Ataxin-2 (ATXN2)
Pathway Diagram
flowchart TD
ATXN2["ATXN2"]
TDP43["TDP-43"]
TDP43_Path["TDP-43 Pathology"]
TDP43_Tox["TDP-43 Toxicity"]
TDP43_Neuro["TDP-43 Neurodegeneration"]
ALS["Amyotrophic Lateral Sclerosis"]
Motor_Death["Motor Neuron Death"]
Motor_Neurons["Motor Neurons"]
Stress_Gran["Stress Granules"]
Ox_Stress["Oxidative Stress Response"]
ASO["Antisense Oligonucleotides"]
Ataxia["Ataxia"]
Lifespan["Lifespan"]
ATXN2 --"interacts with"--> TDP43
ATXN2 --"contributes to"--> TDP43_Path
ATXN2 --"modulates"--> TDP43_Tox
ATXN2 --"contributes to"--> TDP43_Neuro
ATXN2 --"risk factor for"--> ALS
ATXN2 --"involved in"--> Motor_Death
ATXN2 --"expressed in"--> Motor_Neurons
ATXN2 --"regulates"--> Stress_Gran
ATXN2 --"participates in"--> Ox_Stress
ATXN2 --"associated with"--> Ataxia
ATXN2 --"regulates"--> Lifespan
ASO --"targets"--> ATXN2
TDP43_Path --"leads to"--> Motor_Death
Motor_Death --"causes"--> ALS
style ATXN2 fill:#006494,color:#e0e0e0
style TDP43_Path fill:#ef5350,color:#0d0d1a
style TDP43_Tox fill:#ef5350,color:#0d0d1a
style TDP43_Neuro fill:#ef5350,color:#0d0d1a
style ALS fill:#ef5350,color:#0d0d1a
style Motor_Death fill:#ef5350,color:#0d0d1a
style Ataxia fill:#ef5350,color:#0d0d1a
style ASO fill:#1b5e20,color:#e0e0e0
style Stress_Gran fill:#4a1a6b,color:#e0e0e0
style Ox_Stress fill:#4a1a6b,color:#e0e0e0
style Lifespan fill:#4a1a6b,color:#e0e0e0
...
Ataxin-2 (ATXN2)
Pathway Diagram
Mermaid diagram (expand to render)
<div class="infobox" style="float:right; background:#f8f9fa; border:1px solid #ddd; padding:10px; margin:0 0 10px 10px; width:280px;">
Overview Ataxin-2 (ATXN2) is a cytoplasmic RNA-binding protein that regulates mRNA translation, stability, and stress granule dynamics. Intermediate-length CAG repeat expansions in ATXN2 are a major genetic risk factor for Amyotrophic Lateral Sclerosis (ALS) , while longer expansions cause Spinocerebellar Ataxia Type 2 (SCA2) .[@elden2010] Ataxin-2 is emerging as a critical node connecting RNA metabolism, proteostasis, and neurodegeneration.
Structure and Domains Ataxin-2 contains:
LSm (Like-Sm) domain — mediates RNA binding and protein interactionsLSm-associated domain (LAD) — enhances RNA binding specificityPolyglutamine tract — CAG repeat region (normal <24; intermediate 24-34; pathogenic SCA2 >34)PAM2 motif — binds PABPC1 (poly(A)-binding protein)Poly(A)-binding protein-interacting motif 2 (PAM2) — links to translation machineryThe protein localizes to stress granules and processing bodies (P-bodies), key sites of mRNA metabolism.[@nonhoff2007]
Normal Function
mRNA Regulation Ataxin-2 controls post-transcriptional gene expression:
Translational regulation — Associates with actively translating polysomesmRNA stability — Influences decay rates through P-body associationmiRNA-mediated regulation — Interacts with Argonaute proteins
Stress Granule Dynamics During cellular stress, ataxin-2:
Recruits mRNAs to stress granules
Facilitates stress-induced translational repression
Promotes recovery after stress resolution
The LSm domain is essential for stress granule localization and dynamics.[@kaehler2014]
Neuronal Function
Regulates dendritic spine morphology
Controls local protein synthesis in [neurons](/entities/neurons)
Modulates synaptic plasticity
Role in Neurodegeneration
Spinocerebellar Ataxia Type 2 (SCA2) Long CAG expansions (>34 repeats) cause SCA2:
Progressive cerebellar ataxia — Gait instability, dysarthria, dysmetriaSlow saccades — Characteristic eye movement abnormalityPurkinje cell degeneration — Selective cerebellar neuron lossPeripheral neuropathy — Sensory and motor nerve involvementALS Risk Factor Intermediate-length repeats (24-34) increase ALS risk:[@van2011]
Mechanism — Enhances [TDP-43](/mechanisms/tdp-43-proteinopathy) aggregation and toxicityGenetic evidence — Found in 4-5% of ALS patientsGene-environment interaction — May synergize with other ALS risk factorsTDP-43 and FUS Interaction Ataxin-2 modulates the toxicity of other ALS proteins:
TDP-43 — Ataxin-2 enhances cytoplasmic TDP-43 aggregationFUS — Similar stress granule interactionsCross-talk — Shared RNA-binding properties create functional overlapThe interaction between ataxin-2 and TDP-43 provides a molecular explanation for why ATXN2 expansions increase ALS risk.[@kim2013]
Pathological Mechanisms | Mechanism | Evidence | Consequence |
Therapeutic Targeting
Antisense Oligonucleotides
ASO-mediated knockdown — Reduces ATXN2 expression in preclinical modelsClinical trials — ASO therapy for SCA2 in developmentSmall Molecule Approaches | Strategy | Target | Status |
Gene Therapy
AAV-miRNA knockdown — Allele-specific or pan-ATXN2 reductionCRISPR approaches — Targeting CAG repeat expansionProtein Interactions | Partner | Function | Disease Relevance |
See Also
[TDP-43](/mechanisms/tdp-43-proteinopathy)
External Links
[UniProt: Q99700](https://www.uniprot.org/uniprot/Q99700)
[PDB structures](https://www.rcsb.org/search?q=uniprot:Q99700)
References
[Elden AC, et al, Ataxin-2 intermediate-length polyglutamine expansions are associated with increased risk for ALS (2010)](https://doi.org/10.1038/nature10326)
[Nonhoff S, et al, Ataxin-2 interacts with the DEAD/H-box RNA helicase DDX6 and interferes with P-bodies and stress granules (2007)](https://doi.org/10.1091/mbc.e06-11-1019)
[Kaehler C, et al, Ataxin-2-like is a regulator of stress granule and dynein dynamics in neurons (2014)](https://doi.org/10.1523/JNEUROSCI.0168-14.2014)
[Van Damme P, et al, Expanded ATXN2 CAG repeat size in ALS identifies genetic overlap between ALS and SCA2 (2011)](https://doi.org/10.1093/brain/aws032)
[Kim HJ, et al, Mutations in prion-like domains in hnRNPA2B1 and hnRNPA1 cause multisystem proteinopathy and ALS (2013)](https://doi.org/10.1038/nature11922)
Pathway Diagram The following diagram shows the key molecular relationships involving Ataxin-2 (ATXN2) discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)
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