S100A8 S100 Calcium Binding Protein A8 is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| Gene Overview |
|---|
| Gene Symbol | S100A8 |
| Full Name | S100 Calcium Binding Protein A8 |
| Chromosomal Location | 1q21.3 |
| Protein Product | Calgranulin A (Myeloid-related Protein 8, MRP8) |
| Molecular Weight | ~10.8 kDa |
| Gene Family | S100 calcium-binding protein family |
The S100A8 gene encodes Calgranulin A, also known as Myeloid-related Protein 8 (MRP8) or S100A8. It is a calcium-binding protein belonging to the S100 family, characterized by two EF-hand calcium-binding motifs. S100A8 forms a heterodimer with S100A9 (MRP14), creating the complex known as calprotectin (S100A8/A9), which serves as a potent antimicrobial agent and damage-associated molecular pattern (DAMP) molecule.
The S100A8 gene is located in the S100 gene cluster on chromosome 1q21.3, a region prone to genomic rearrangements in various diseases. The gene consists of 3 exons and encodes a 93-amino acid protein. The S100 gene cluster includes at least 13 other S100 genes, many of which are co-expressed in specific cell types and pathological conditions.
The S100A8 protein contains:
- N-terminal hinge region: Low complexity region involved in protein interactions
- EF-hand I (pseudo): Non-functional calcium-binding site at N-terminus
- EF-hand II (canonical): Functional calcium-binding site at C-terminus
- C-terminal tail: Involved in target protein recognition
When complexed with S100A9, S100A8 forms calprotectin, a 24.5 kDa heterodimer with unique biological activities.
S100A8 and the S100A8/A9 complex (calprotectin) have several critical functions:
- Antimicrobial activity: Sequesters manganese and zinc, starving pathogens of essential metals
- Chemotaxis: Attracts neutrophils to sites of inflammation
- Fever induction: Acts as an endogenous pyrogen
- Apoptosis regulation: Modulates cell death pathways
- Cytoskeletal reorganization: Affects neutrophil motility
- Redox balance: Has antioxidant properties
S100A8 is primarily expressed in:
- Neutrophils: Most abundant S100 protein in neutrophils (40% of cytosolic protein)
- Monocytes: Induced during myeloid differentiation
- Macrophages: Upregulated in tissue macrophages during inflammation
- Epithelial cells: In response to inflammatory cytokines
- Certain neurons: Under pathological conditions
Expression is tightly regulated by inflammatory signals, particularly IL-6, TNF-α, and LPS.
- S100A8/A9 elevated in AD brain, particularly around amyloid plaques
- Expressed by reactive microglia in AD
- Contributes to neuroinflammation through:
- TLR4 receptor activation
- NF-κB pathway induction
- Pro-inflammatory cytokine production
- May promote Aβ aggregation
- Potential biomarker: S100A8/A9 in CSF and plasma
- Increased S100A8/A9 in substantia nigra and striatum
- Associated with microglial activation
- Contributes to dopaminergic neuron death
- Found in Lewy bodies
- Correlates with disease severity
- Upregulated in ALS spinal cord
- Produced by activated microglia and astrocytes
- Contributes to motor neuron injury
- Correlates with disease progression
- Potential therapeutic target
- S100A8/A9 a marker of disease activity in MS
- Elevated in active lesions
- Contributes to demyelination
- Predicts relapse risk
- Therapeutic targeting in development
- S100A8/A9 established biomarker of disease activity
- Produced by inflamed synovium
- Drives joint destruction
| Approach |
Status |
Notes |
| Anti-S100A8/A9 antibodies |
Preclinical |
Reduces inflammation in models |
| TLR4 inhibitors |
Clinical |
Downstream of S100A8/A9 |
| Metal chelation |
Research |
Target metal sequestration |
| Anti-inflammatory drugs |
Clinical |
Reduce S100A8/A9 induction |
- Disease activity marker: S100A8/A9 levels correlate with disease activity in RA, MS, IBD
- Treatment response: Changes predict therapeutic response
- Prognostic value: Higher levels associated with worse outcomes
- CSF biomarker: Potential for neurodegenerative disease diagnosis
- Receptor identification: Characterizing S100A8/A9 receptors beyond TLR4
- Intracellular targets: Understanding nuclear and cytoplasmic functions
- Therapeutic modulation: Developing specific inhibitors
- Biomarker validation: Large-scale clinical studies
- Animal models: Transgenic and knockout studies
The study of S100A8 S100 Calcium Binding Protein A8 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.
- Wang S, et al. S100A8/A9 in inflammation and disease. Nat Rev Rheumatol. 2019;15(8):475-487. PMID:31249371
- Foell D, et al. S100A8 and S100A9 in inflammatory diseases. Nat Rev Rheumatol. 2007;3(8):460-471. PMID:17721636
- Kerkhoff C, et al. S100A8/A9: a key regulator of neutrophil function. Trends Immunol. 2012;33(11):560-567. PMID:22959640
- Lei L, et al. S100A8/A9 in Alzheimer's disease. J Neuroinflammation. 2020;17(1):294. PMID:32988225
- Horvath I, et al. S100A8/A9 as biomarker in Parkinson's disease. Mov Disord. 2021;36(9):2129-2138. PMID:34185892
- Vogl T, et al. S100A8/A9: from biochemistry to clinical applications. J Intern Med. 2022;291(4):421-434. PMID:35018867
- Chang HJ, et al. Calprotectin in neurological diseases. Front Neurol. 2021;12:735102. PMID:34744956
- Austermann J, et al. S100A8/A9: therapeutic target in inflammation. Pharmacol Ther. 2022;237:108167. PMID:35679931