CCR2+ monocyte-derived macrophages, recruited to the neuromuscular junction by motor neuron-secreted CCL2, selectively infiltrate and strip fast-fatigable (IIb/IIx fibre) NMJs via matrix metalloproteinase-9 (MMP-9) cleavage of the laminin alpha-5/beta-2 NMJ scaffold. Fast motor neurons express higher CCL2 and lower TIMP-1 (MMP-9 inhibitor) than slow motor units, creating a chemokine gradient that explains selective NMJ vulnerability. Genetic or pharmacological MMP-9 blockade should preferentially protect fast-fatigable NMJs in ALS mouse models.
Curated pathway from expert analysis
flowchart TD
A["ALS Motor Neuron Stress<br/>Fast-Fatigable Type IIb/IIx Units"]
B["CCL2 Secreted by Fast Motor Neurons<br/>High CCL2 Low TIMP-1 Gradient"]
C["CCR2+ Monocyte Recruitment<br/>Chemokine-Directed Infiltration"]
D["Monocyte-Derived Macrophages<br/>Accumulate at Fast-Fatigable NMJ"]
E["MMP-9 Secretion<br/>Metalloproteinase Activation"]
F["Laminin alpha5 beta2 Scaffold Cleaved<br/>NMJ Structural Disruption"]
G["Fast-Fatigable NMJ Stripped<br/>Selective Denervation"]
H["ALS Motor Neuron Vulnerability<br/>Progressive Weakness"]
A --> B
B --> C
C --> D
D --> E
E --> F
F --> G
G --> H
style B fill:#7b1fa2,stroke:#ce93d8,color:#ce93d8
style H fill:#b71c1c,stroke:#ef9a9a,color:#ef9a9aNo linked papers recorded for this hypothesis yet.
No curated PDB or AlphaFold mapping for CCL2 yet. Search RCSB →
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 CCL2.
Run python3 scripts/backfill_hypothesis_depmap.py to populate.
No resource usage or linked notebooks recorded for this hypothesis yet.