🧪
hypothesis

Ataxin-2 Polyglutamine Expansions Hijack G3BP1 to Form Toxic, Irreversible Stress Granule Complexes

Hypothesis

Ataxin-2 Polyglutamine Expansions Hijack G3BP1 to Form Toxic, Irreversible Stress Granule Complexes

Ataxin-2 Polyglutamine Expansions Hijack G3BP1 to Form Toxic, Irreversible Stress Granule Complexes starts from the claim that modulating ATXN2 within the disease context of neurodegeneration can redirect a disease-relevant process.
🧬 ATXN2🩺 neurodegeneration🎯 Composite 70%💱 $0.59▼15.4%proposed
🟡 ALS / Motor Neuron Disease
EvidencePending (0%)📖 8 cit🗣 1 debates 8 support 2 oppose
✓ All Quality Gates Passed
Mechanistic 0.65 (15%) Evidence 0.68 (15%) Novelty 0.70 (12%) Feasibility 0.72 (12%) Impact 0.75 (12%) Druggability 0.65 (10%) Safety 0.68 (8%) Competition 0.75 (6%) Data Avail. 0.72 (5%) Reproducible 0.70 (5%) KG Connect 0.27 (8%) 0.700 composite
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🧪 Overview

Mechanistic Overview


Ataxin-2 Polyglutamine Expansions Hijack G3BP1 to Form Toxic, Irreversible Stress Granule Complexes starts from the claim that modulating ATXN2 within the disease context of neurodegeneration can redirect a disease-relevant process. The original description reads: "## Mechanistic Overview Ataxin-2 Polyglutamine Expansions Hijack G3BP1 to Form Toxic, Irreversible Stress Granule Complexes starts from the claim that modulating ATXN2 within the disease context of neurodegeneration can redirect a disease-relevant process. The original description reads: "## Mechanistic Overview Ataxin-2 Polyglutamine Expansions Hijack G3BP1 to Form Toxic, Irreversible Stress Granule Complexes starts from the claim that Ataxin-2 expansions (>34 repeats) create hyper-stable complexes with G3BP1 through the Q/N-rich region (not PAM2 motif as originally hypothesized), sequestering RNA-binding proteins and forming detergent-resistant aggregates. Both SCA2 and ALS-risk populations could benefit from disrupting this interaction. ASO-mediated Ataxin-2 knockdown represents the most tractable therapeutic modality.

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🧬 Mechanism

🧬 Curated Mechanism Pathway

Curated pathway from expert analysis

flowchart TD
    A["ATXN2 PolyQ Expansion<br/>CAG Repeat Expansion >31"]
    B["RNA-Binding Protein<br/>Stress Granule Component"]
    C["G3BP1 Interaction<br/>Stress Granule Dynamics"]
    D["Toxic RNA Foci Formation<br/>C9ORF72 Sense Repeats"]
    E["Dipeptide Repeat Proteins<br/>C9ORF72 Translation"]
    F["Stress Granule Persistence<br/>Liquid-to-Solid Transition"]
    G["TCPF Sclerosis<br/>ALS/FTD Neurodegeneration"]
    H["Excitotoxicity<br/>Glutamate Toxicity"]
    I["Motor Neuron Degeneration<br/>ALS Phenotype"]
    J["Cerebellar Degeneration<br/>SCA2 Phenotype"]
    A --> B
    B --> C
    C --> D
    D --> E
    B --> F
    E --> F
    F --> G
    G --> H
    H --> I
    I --> J
    style A fill:#7b1fa2,stroke:#ce93d8,color:#ce93d8
    style J fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a

⚖️ Evidence

⚖️ Evidence Matrix8 supports2 contradicts
Supports
Ataxin-2 expansions cause SCA2 and increase ALS risk 20-fold
PMID:22536394
Supports
Ataxin-2 is a validated G3BP1 interactor in stress granule formation
PMID:19322463
Supports
Polyglutamine expansions promote abnormal protein-protein interactions
PMID:24584051
Supports
Circadian clocks are modulated by compartmentalized oscillating translation.
Cell2023PMID:37369203medium
Supports
Identification of small molecule inhibitors of G3BP-driven stress granule formation.
J Cell Biol2024PMID:38284934medium
Supports
Staufen Impairs Autophagy in Neurodegeneration.
Ann Neurol2023PMID:36151701medium
Supports
Transcriptomic and proteomic profiling of bi-partite and tri-partite murine iPSC-derived neurospheroids under steady-state and inflammatory condition.
Brain Behav Immun2024PMID:39002812medium
Supports
Viral-mediated knockdown of Atxn2 attenuates TDP-43 pathology and muscle dysfunction in the PFN1(C71G) ALS mouse model.
Acta Neuropathol Commun2025PMID:40413526medium
Contradicts
Ataxin-2 knockout mice do not develop ALS-like disease despite impaired SG dynamics
PMID:19322463
Contradicts
Mechanism correction: PAM2 domain binds PABPC1's MLLE domain, not G3BP1; actual interface is Q/N-rich region
PMID:19322463
📖 Linked Papers

No linked papers recorded for this hypothesis yet.

🏥 Translation

🧬 3D Protein Structure — ATXN2

No curated PDB or AlphaFold mapping for ATXN2 yet. Search RCSB →

🧠 GTEx v10 Brain ExpressionJSON

Median TPM across 13 brain regions for ATXN2 from GTEx v10.

Cerebellum23.7 Cerebellar Hemisphere21.1 Spinal cord cervical c-113.4 Cortex12.9 Frontal Cortex BA912.5 Hypothalamus10.6 Nucleus accumbens basal ganglia9.1 Anterior cingulate cortex BA249.1 Substantia nigra9.0 Caudate basal ganglia8.4 Hippocampus7.8 Amygdala7.3 Putamen basal ganglia7.0median TPM (GTEx v10)

💉 Clinical Trials

No clinical trials data linked to this hypothesis yet.

No curated ClinVar variants loaded for this hypothesis.

Run scripts/backfill_clinvar_variants.py to fetch P/LP/VUS variants.

🔍 Search ClinVar for ATXN2 →

No DepMap CRISPR Chronos data found for ATXN2.

Run python3 scripts/backfill_hypothesis_depmap.py to populate.

💰 Estimated Development
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📊 Market Indicators

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💾 Resource Usage

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🔮 Predictions

🔎 Predictions vs Observations2 predictions · 0 with recorded observations
PredictionPredictedObservedStatusConf
IF ASO-mediated knockdown reduces ATXN2 mRNA by >80% in SCA2 patient neurons, THEN stress granule disassembly kinetics will normalize to wild-type timing (<4 hours for 50% granule dissolution after stSCA2 neurons treated with ATXN2-targeting ASO will show stress granule half-life reduction from >8 hours to <4 hours post-stress, with corresponding restoration— no observation —pending0.72
IF ATXN2 with >34 polyglutamine expansions is expressed in neuronal cells, THEN G3BP1 will co-immunoprecipitate with Ataxin-2 and stress granule markers will appear in Triton X-100 insoluble fractionsAtaxin-2(Q>34) will co-precipitate with G3BP1 at >60% efficiency compared to wild-type, and TIA-1/G3BP1 will be enriched 3-5 fold in the detergent-insoluble fra— no observation —pending0.75
🔮 Falsifiable Predictions (2)
pendingconf —
IF ATXN2 with >34 polyglutamine expansions is expressed in neuronal cells, THEN G3BP1 will co-immunoprecipitate with Ataxin-2 and stress granule markers will appear in Triton X-100 insoluble fractions, using human iPSC-derived neurons from SCA2 patients.
Predicted outcome: Ataxin-2(Q>34) will co-precipitate with G3BP1 at >60% efficiency compared to wild-type, and TIA-1/G3BP1 will be enriched 3-5 fold in the detergent-ins
Falsification: If wild-type Ataxin-2 (<27Q) shows equivalent G3BP1 co-precipitation and equivalent detergent-resistant aggregate formation as SCA2 expansions (>34Q), the hypothesis that polyglutamine expansion speci
pendingconf —
IF ASO-mediated knockdown reduces ATXN2 mRNA by >80% in SCA2 patient neurons, THEN stress granule disassembly kinetics will normalize to wild-type timing (<4 hours for 50% granule dissolution after stress removal), using live-cell imaging of G3BP1-GFP.
Predicted outcome: SCA2 neurons treated with ATXN2-targeting ASO will show stress granule half-life reduction from >8 hours to <4 hours post-stress, with corresponding r
Falsification: If ASO knockdown of ATXN2 does not alter stress granule dynamics or aggregate formation (granule half-life remains >6 hours and detergent-insoluble fractions unchanged), this would disprove the therap

📖 References (3)

  1. Ethylene supports colonization of plant roots by the mutualistic fungus Piriformospora indica.
    ["Khatabi et al.. PloS one (2012)
    PubMed↗DOI↗
  2. Enantioselective catalysis with chiral complexes immobilized on nanostructured supports.
    ["Fraile et al.. Chemical Society reviews (2009)
    PubMed↗DOI↗
  3. Mutant Huntingtin promotes autonomous microglia activation via myeloid lineage-determining factors.
    ["Crotti et al.. Nature neuroscience (2014)
    PubMed↗DOI↗
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