The ESCRT machinery (particularly CHMP2B, TSG101, and ALIX) normally mediates budding of intraluminal vesicles into MVBs and resealing of damaged lysosomal membranes. In PD, phosphorylated SNCA (at Ser129) acts as a pathological ligand that recruits ESCRT-III components to lysosomal membranes via a novel phospho-dependent interaction with CHMP2B. Normally, LAMP2A coordinates this process by recruiting TSG101; however, in PD, hyperphosphorylated SNCA outcompetes LAMP2A for TSG101 binding. This redirects ESCRT machinery toward SNCA aggregates rather than membrane repair, causing accumulation of damaged lysosomal membranes and failed MVB maturation. The trapped MVBs cannot fuse with lysosomes, creating a compartment where SNCA continues to aggregate. VPS35 dysfunction exacerbates this by impairing retrieval of ESCRT components to the cytoplasm for recycling. The prediction is that blocking the SNCA- CHMP2B interaction (with cell-penetrating peptides targeting the CHMP2B-binding domain) will restore lysosomal membrane repair and MVB trafficking.
...Curated pathway from expert analysis
flowchart TD
A["pSer129-SNCA Aggregation<br/>Phosphorylated Alpha-Synuclein"]
B["CHMP2B ESCRT-III Recruitment<br/>Phospho-Dependent Binding"]
C["TSG101 Outcompeted from LAMP2A<br/>ESCRT Redirection to SNCA"]
D["Intraluminal Vesicle Budding Fails<br/>MVB Maturation Arrested"]
E["VPS35 Dysfunction<br/>ESCRT Recycling Impaired"]
F["Damaged Lysosomal Membranes Accumulate<br/>Membrane Repair Failure"]
G["SNCA Continues Aggregating<br/>in Trapped MVB Compartment"]
H["Lysosomal Dysfunction<br/>PD Pathology Amplification"]
A --> B
B --> C
C --> D
E --> D
D --> F
D --> G
F --> H
G --> H
style A fill:#7b1fa2,stroke:#ce93d8,color:#ce93d8
style H fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9aNo linked papers recorded for 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 SNCA.
Run python3 scripts/backfill_hypothesis_depmap.py to populate.
No resource usage or linked notebooks recorded for this hypothesis yet.
| Prediction | Predicted | Observed | Status | Conf |
|---|---|---|---|---|
| IF a cell-penetrating peptide blocking the CHMP2B-binding domain (SNCA residues 61–95) is applied to iPSC-derived dopaminergic neurons from GBA1-PD patients (n≥3 lines), THEN the co-localization of CH | Significant reduction in CHMP2B mislocalization to lysosomes and restoration of lysosomal membrane integrity, quantified by Manders' colocalization coefficient | — no observation — | pending | 0.72 |
| IF the CHMP2B-blocking peptide is applied to iPSC-derived neurons from GBA1-PD patients, THEN the number of VPS27/MVB-lysosome fusion events (measured by CD63-LAMP2 colocalization) will increase by >6 | Restored MVB-lysosome fusion (increased CD63-LAMP2 colocalization) and reduced α-synuclein aggregate load, as measured by high-content imaging and α-synuclein E | — no observation — | pending | 0.68 |