In APOE4 contexts, reduced LRP1 signaling in PDGFRB+ pericytes permits activation of the PPIA/CypA-MMP9 axis, leading to oxidative stress, basement-membrane remodeling, pericyte senescence-like injury, and BBB leak before substantial amyloid/tau-mediated neurodegeneration. The strongest interpretation is that APOE4-linked pericyte injury is plausibly upstream, but direct proof that bona fide senescence is the initiating lesion remains incomplete.
Curated pathway from expert analysis
flowchart TD
A["APOE4 Isoform<br/>Arg112-Cys158 Structure"]
B["LRP1 Receptor Binding<br/>Hepatic and Neuronal Uptake"]
C["TREM2 Engagement<br/>Microglial State Transition"]
D["DAM Identity<br/>Disease-Associated Microglia"]
E["Lipid Metabolism<br/>Cholesterol Efflux Defect"]
F["Amyloid Clearance<br/>Reduced A-beta Uptake"]
G["Tau Hyperphosphorylation<br/>GSK3B/CDK5 Activation"]
H["Neurofibrillary Tangles<br/>Intraneuronal Pathology"]
I["Synaptic Dysfunction<br/>Neuronal Network Disruption"]
J["Cognitive Decline<br/>Progressive Dementia"]
A --> B
B --> C
C --> D
D --> E
E --> F
A --> G
F -.->|"accelerates"| G
G --> H
D --> I
H --> J
I --> J
style A fill:#7b1fa2,stroke:#ce93d8,color:#ce93d8
style J fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9aNo linked papers recorded for this hypothesis yet.
No curated PDB or AlphaFold mapping for APOE4 yet. Search RCSB →
Median TPM across 13 brain regions for APOE4, LRP1, PPIA, MMP9, PDGFRB from GTEx v10.
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 APOE4, LRP1, PPIA, MMP9, PDGFRB.
Run python3 scripts/backfill_hypothesis_depmap.py to populate.
| Prediction | Predicted | Observed | Status | Conf |
|---|---|---|---|---|
| IF we stratify APOE4/4 homozygous carriers aged 25-45 without clinical neurodegeneration against age-matched APOE3/3 carriers, THEN APOE4 carriers will show significantly lower cerebrospinal fluid sol | sPDGFRB will be 30-50% lower and MMP9 activity 2-3 fold higher in APOE4/4 vs APOE3/3 subjects, reflecting pericyte detachment and matrix remodeling independent | — no observation — | pending | 0.78 |
| IF we administer CypA inhibitor (Alisporivir, 20 mg/kg/day via osmotic minipump) to APOE4 knock-in mice from 3-6 months of age, THEN MMP9 activity in cortical perivascular tissue will decrease by ≥60% | Alisporivir will normalize pericyte health markers and BBB integrity in APOE4 mice to APOE3 levels, establishing CypA-MMP9 axis as a necessary driver of APOE4-r | — no observation — | pending | 0.72 |