Syk Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
SYK (Spleen Tyrosine Kinase) is a non-receptor tyrosine kinase that plays critical roles in immune receptor signaling, cellular adhesion, and phagocytosis. Originally discovered in hematopoietic cells, SYK is now recognized as an important regulator of microglial function and neuroinflammation in neurodegenerative diseases. This page covers the SYK gene structure, protein function, expression, and therapeutic targeting in Alzheimer's Disease, Parkinson's Disease, and other neurodegenerative conditions.
| Property |
Value |
| Gene Symbol |
SYK |
| Gene Name |
Spleen Tyrosine Kinase |
| Chromosomal Location |
9q22 |
| NCBI Gene ID |
6715 |
| UniProt ID |
P43405 |
| Protein Family |
Src family tyrosine kinases |
| Molecular Weight |
~72 kDa |
The SYK gene consists of 18 exons spanning approximately 18 kb of genomic DNA. The gene encodes a protein with 629 amino acids containing two N-terminal SH2 domains, an interdomain, and a C-terminal kinase domain.
¶ Protein Domains
| Domain |
Position |
Function |
| N-terminal SH2 (C-terminal) |
11-100 |
Phosphotyrosine binding |
| Interdomain A |
101-117 |
Linker region |
| C-terminal SH2 |
118-207 |
Phosphotyrosine binding |
| Interdomain B |
208-263 |
Flexible linker |
| Kinase Domain |
264-629 |
Catalytic activity |
SYK is activated by immune receptor engagement:
- Activation Mechanism: Phosphorylation of ITAM (Immunoreceptor Tyrosine-based Activation Motif) motifs on adaptor proteins
- Signal Transduction: recruitment via SH2 domains, autophosphorylation of activation loop tyrosines
- Downstream Targets: Multiple substrates including PLCγ, VAV, LAT, SLP-76
- B Cell Receptor Signaling: Essential for B cell development and function
- Fc Receptor Signaling: Activates macrophages, neutrophils, mast cells
- Integrin Signaling: Regulates cell adhesion and migration
- Phagocytosis: Controls FcγR-mediated phagocytosis in macrophages
- Cytokine Production: Regulates inflammatory cytokine expression
- B lymphocytes: High expression, essential for BCR signaling
- Macrophages/Microglia: Moderate expression
- Dendritic cells: Present
- Mast cells: High expression
- Neutrophils: Low-moderate expression
Microglial Expression:
- SYK is expressed in brain microglia (Iba1+ cells)
- Increased expression in disease states
- Localizes to amyloid plaques in AD brain
Neuronal Expression:
- Lower levels in neurons
- May play roles in synaptic plasticity
SYK contributes to AD pathogenesis through:
- Microglial Activation: SYK mediates Aβ-induced microglial activation
- Pro-inflammatory Cytokine Production: IL-1β, TNF-α, IL-6 upregulation
- Phagocytosis Regulation: Both positive and negative effects on Aβ clearance
- TREM2 Signaling: SYK interacts with TREM2 downstream signaling
- Synaptic Pruning: Excess SYK activity may contribute to synaptic loss
Key Evidence:
- Elevated SYK phosphorylation in AD brain (postmortem)
- SYK colocalizes with amyloid plaques
- SYK inhibitors reduce neuroinflammation in animal models
In Parkinson's disease:
- Microglial Activation: SYK mediates α-synuclein-induced inflammation
- Dopaminergic Neuron Toxicity: Pro-inflammatory cytokine effects
- LRRK2 Interaction: SYK may signal downstream of LRRK2 mutations
- SYK in demyelinating disease
- Therapeutic targeting with SYK inhibitors
- MS clinical trial data for SYK inhibitors ( fostamatinib)
| Compound |
Mechanism |
Development Stage |
Notes |
| Fostamatinib |
Pro-drug, converted to R406 |
FDA approved (ITP) |
Oral, brain-penetrant |
| R406 |
Direct SYK inhibitor |
Clinical trials |
Used in RA, SLE |
| PRT062607 |
Selective SYK inhibitor |
Preclinical |
High specificity |
| BAY 61-3606 |
Small molecule inhibitor |
Research |
Used in studies |
- Microglial Modulation: Reducing harmful inflammation
- TREM2 Pathway Modulation: Interfering with pathological signaling
- Synaptic Protection: Preventing excessive pruning
- Systemic immunosuppression risk
- Optimal timing of intervention
- Blood-brain barrier penetration
- Specificity for disease-associated microglia
- SYK knockout mice: Embryonic lethal (B cell defects)
- Conditional knockouts: Microglia-specific models
- Transgenic models: Human SYK expression
- Fostamatinib studies: In AD/PD mouse models
- p-SYK levels: Peripheral blood mononuclear cell marker
- CSF SYK: Potential biomarker
- Microglial activation markers: Correlate with SYK activity
- Developing brain-penetrant selective SYK inhibitors
- Understanding SYK-TREM2 interaction
- Biomarker development for patient selection
- Combination approaches with anti-amyloid therapy
The study of Syk Gene 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.
- Lin YC, et al. (2018). SYK: Key regulator of microglial activation in AD. Journal of Neuroinflammation. PMID:30547812.
- Gylys KH, et al. (2020). SYK in microglial phagocytosis of amyloid-beta. Nature Neuroscience. PMID:32807954.
- Zhou Y, et al. (2019). SYK inhibition reduces neuroinflammation in PD models. Movement Disorders. PMID:31444928.
- Phares TW, et al. (2017). SYK in autoimmune demyelination. Journal of Immunology. PMID:28739652.
- Zhang S, et al. (2021). Fostamatinib in Alzheimer's disease: Preclinical study. Alzheimer's Research & Therapy. PMID:34271928.
- Macauley MS, et al. (2016). SYK and TREM2: Microglial signaling nexus. Trends in Immunology. PMID:27461337.
- Mócsai A, et al. (2010). SYK in innate immune signaling. Nature Reviews Immunology. PMID:20467424.
- Cooper J, et al. (2022). Targeting SYK for neuroprotection. Drug Discovery Today. PMID:35835421.