S100A9 Protein Calgranulin B is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| Symbol | S100A9 |
| Full Name | S100 Calcium Binding Protein A9 |
| Aliases | Calgranulin B, MRP14, Myeloid-related protein 14 |
| Molecular Weight | 13.2 kDa |
| Protein Family | S100 EF-hand calcium-binding proteins |
| Associated Diseases | AD, PD, ALS, MS, Rheumatoid Arthritis, Inflammatory Bowel Disease |
S100A9 (S100 Calcium Binding Protein A9), also known as Calgranulin B or Myeloid-Related Protein 14 (MRP14), is a member of the S100 family of EF-hand calcium-binding proteins. Like its partner S100A8, S100A9 forms a heterodimer (calprotectin) that functions as a Damage-Associated Molecular Pattern (DAMP) molecule. This complex is a major player in neuroinflammation and is implicated in the pathogenesis of Alzheimer's disease, Parkinson's disease, ALS, and multiple sclerosis.
S100A9 is a 13.2 kDa protein containing two EF-hand calcium-binding motifs. The C-terminal EF-hand is the high-affinity calcium-binding site. S100A9 can form both homodimers and heterodimers with S100A8. The S100A8/A9 heterodimer (calprotectin) is the biologically active form involved in immune signaling.
S100A9 is co-localized with amyloid plaques in AD brain. The protein is upregulated in microglia surrounding plaques and contributes to chronic neuroinflammation. CSF levels of S100A9 correlate with disease severity and may serve as a biomarker.
Elevated S100A9 in substantia nigra and CSF of PD patients. Promotes microglial activation and dopaminergic neuron toxicity. The S100A8/A9 complex may be a therapeutic target.
Upregulated in ALS spinal cord microglia and motor neurons. Associated with neuroinflammation and disease progression. Correlates with clinical measures of disease severity.
Central to demyelination and lesion formation. Therapeutic targeting reduces disease severity in mouse models of MS.
| Approach | Status | Description |
|---|---|---|
| Anti-S100A9 antibodies | Preclinical | Neutralizing antibodies against calprotectin |
| TLR4 inhibitors | Preclinical | Blocking downstream inflammation |
| RAGE antagonists | Preclinical | Preventing RAGE-mediated signaling |
| S100A9 knockout | Research | Genetic deletion reduces inflammation |
The study of S100A9 Protein Calgranulin B has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.