TREM2 signaling controls the spatial distribution of complement regulators CD55 and CD46 on synaptic membranes, determining which synapses are vulnerable to complement-mediated pruning. Under normal conditions, TREM2 activation promotes the expression and clustering of CD55/CD46 at perisomatic inhibitory synapses through DAM pathway signaling, while maintaining low regulator density at distal excitatory synapses. This creates a protective gradient where inhibitory circuits are preserved while allowing physiological pruning of excitatory connections. In TREM2 haploinsufficiency states, this spatial control breaks down—CD55/CD46 redistribution becomes dysregulated, leading to inappropriate complement activation at previously protected inhibitory synapses. The mechanism involves TREM2-dependent regulation of PSD-95 and gephyrin scaffolding proteins, which control CD55/CD46 membrane anchoring. When TREM2 signaling is compromised, PSD-95-mediated competitive inhibition of complement regulators extends aberrantly to inhibitory synapses, while the normal gephyrin-facilitated clustering of CD55/CD46 is lost.
...Curated pathway from expert analysis
flowchart TD
A["CD55 DAF, CD46 MCP<br/>Hypothesis Target"]
B["Complement<br/>Cited Mechanism"]
C["Cellular Response<br/>Stress or Clearance Change"]
D["Neural Circuit Effect<br/>Synapse/Glia Vulnerability"]
E["Neurodegeneration<br/>Disease-Relevant Outcome"]
A --> B
B --> C
C --> D
D --> E
style A fill:#1a237e,stroke:#4fc3f7,color:#4fc3f7
style B fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9a
style E fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9aNo linked papers recorded for this hypothesis yet.
Median TPM across 13 brain regions for TREM2 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 TREM2.
Run python3 scripts/backfill_hypothesis_depmap.py to populate.