Glucosylceramide accumulation nucleates alpha-synuclein aggregation via lipid raft microdomain formation, impairing LIMP-2-mediated GBA trafficking
🧪 Overview
We propose that GBA deficiency-driven accumulation of glucosylceramide (GlcCer) in lysosomal membranes creates ordered lipid raft-like microdomains that serve as high-affinity nucleation sites for alpha-synuclein (αSyn) binding and fibrillization. The resultant αSyn oligomers directly interact with LIMP-2 (SCARB2), the mannose-6-phosphate receptor responsible for trafficking pro-GBA from ER to lysosome, impairing its function and causing further GBA mislocalization. This creates a self-reinforcing bidirectional loop. Testable prediction: pharmacological reduction of GlcCer via GZ/SAR402671 will reduce αSyn seeding susceptibility in patient-derived neurons, measured by ThT fluorescence and seeding assays, prior to detectable changes in total αSyn levels. Blocking this lipid-mediated nucleation interface would break the loop upstream of both aggregation and trafficking impairment.
🧬 Mechanism
Curated pathway from expert analysis
flowchart TD
A["GBA Loss of Function<br/>Glucosylceramide Accumulation"]
B["Lipid Raft<br/>Microdomain Formation"]
C["Alpha-Synuclein<br/>Aggregation Nucleation"]
D["LIMP-2-Mediated<br/>GBA Trafficking Deficit"]
E["Synucleinopathy<br/>Propagation"]
F["GBA as<br/>Lipid-Nucleation Target"]
A --> B
B --> C
C --> D
D --> E
E --> F
style A fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style F fill:#1b5e20,stroke:#a5d6a7,color:#a5d6a7⚖️ Evidence
No linked papers recorded for this hypothesis yet.
🏥 Translation
🧬 3D Protein Structure — GBA
🧠 GTEx v10 Brain ExpressionJSON
Median TPM across 13 brain regions for GBA from 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.
No DepMap CRISPR Chronos data found for GBA.
Run python3 scripts/backfill_hypothesis_depmap.py to populate.
🏆 Tournament
🏆 Arenas / Elo
📊 Market Indicators
💾 Resource Usage
🔮 Predictions
| Prediction | Predicted | Observed | Status | Conf |
|---|---|---|---|---|
| IF a synthetic competitive peptide (50 μM) corresponding to the LIMP-2 binding domain (residues 269-290) is applied to iPSC-derived neurons from GBA-PD patients, THEN lysosomal GBA activity (measured | Blocking αSyn-LIMP-2 interaction with a competitive peptide restores LIMP-2 trafficking function and GBA localization to lysosomes | — no observation — | pending | 0.65 |
| IF human iPSC-derived dopaminergic neurons from GBA-PD patients (homozygous N370S or heterozygous L444P) are treated with a brain-penetrant GlcCer synthase inhibitor (GZ/SAR402671, 1 μM) for 7 days, T | GlcCer reduction (≥50% by LC-MS/MS) precedes and is quantitatively correlated with reduced αSyn seeding susceptibility, with no concurrent change in total αSyn | — no observation — | pending | 0.72 |
▸Metadatasource: v1_phase_c_backfill · origin_type: audit_hypothesis_generator
| source | v1_phase_c_backfill |
| origin_type | audit_hypothesis_generator |
| _schema_version | 1 |