Lck — Lck Proto Oncogene, Src Family Tyrosine Kinase 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 Symbol | LCK |
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| Full Name | LCK Proto-Oncogene, Src Family Tyrosine Kinase |
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| Chromosomal Location | 1p35.2 |
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| NCBI Gene ID | 3932 |
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| OMIM | 153360 |
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| Ensembl | ENSG00000182866 |
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| UniProt | P06239 |
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| Protein | [Lck Protein](/proteins/lck-protein) |
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| Associated Diseases | Autoimmune Disease, Immunodeficiency, T-cell Leukemia, Alzheimer's Disease, Parkinson's Disease |
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LCK (Lymphocyte-specific protein tyrosine kinase) is a member of the Src family of non-receptor tyrosine kinases (SFKs) [PMID: 15035502]. It is primarily expressed in T-lymphocytes and is essential for T-cell receptor (TCR) signaling, playing a critical role in adaptive immunity [PMID: 15035502]. In the nervous system, LCK is expressed in certain neuronal populations and plays important roles in neuroimmune interactions, synaptic plasticity, and neurodegenerative disease pathogenesis [PMID: 19081012].
The LCK gene encodes a 56 kDa protein that is predominantly localized to the cytoplasmic face of the plasma membrane. It is one of the earliest signaling molecules activated following TCR engagement, making it essential for T-cell development, activation, and function [PMID: 15035502].
¶ Gene Structure and Regulation
The LCK gene spans approximately 11 kb on chromosome 1p35.2 and consists of 12 exons [PMID: 15035502]. It utilizes alternative translation initiation sites producing distinct isoforms:
- p56LCK: Full-length isoform with myristoylation site
- p50LCK: Truncated isoform with different localization
LCK expression is tightly regulated:
- Promoter Elements: Contains STAT, NF-κB, and Ets family binding sites [PMID: 15035502]
- Developmental Regulation: Expressed early in thymocyte development
- Tissue Specificity: Highest expression in T-cells, lower in neurons
LCK shares the conserved architecture of Src family kinases:
¶ Domain Organization
| Domain |
Position |
Function |
| N-terminal |
1-80 |
Myristoylation, membrane association |
| Unique Domain |
81-120 |
Protein interactions, substrate targeting |
| SH3 Domain |
121-190 |
Proline-rich motif binding |
| SH2 Domain |
191-280 |
Phosphotyrosine binding |
| Kinase Domain |
281-509 |
Catalytic activity |
| C-terminal Tail |
510-556 |
Regulatory tyrosine (Y505) |
- Myristoylation (G2): Enables membrane localization
- Y394 (Activation Loop): Autophosphorylation site, required for activity
- Y505 (C-terminal): Inhibitory phosphorylation, regulated by CD45
- SH3/SH2 Domains: Mediate protein-protein interactions and localization
LCK is essential for T-cell receptor signaling [PMID: 15035502]:
- TCR Signaling Initiation: LCK associates with TCR/CD3 complex and initiates downstream signaling
- T-cell Development: Required for positive and negative selection in thymus
- T-cell Activation: Mediates antigen recognition and effector function
- Immune Synapse Formation: Facilitates communication between T-cell and antigen-presenting cell
In neurons, LCK participates in several important processes [PMID: 19081012]:
- Synaptic Plasticity: LCK regulates NMDA receptor phosphorylation and trafficking [PMID: 19081012]
- NMDA Receptor Signaling: Phosphorylates NR2A/B subunits, modulating channel function
- PSD-95 Interactions: Participates in postsynaptic signaling complexes
- Tau Phosphorylation: Can phosphorylate tau at multiple sites
- Neuronal Survival: Regulates pro-survival and pro-apoptotic signaling
- Integrin Signaling: Modulates cell adhesion and migration
- Cytokine Receptor Signaling: Participates in IL-2 and other cytokine pathways
- Calcium Signaling: Upstream of NFAT activation
LCK is implicated in AD pathogenesis through multiple mechanisms [PMID: 19081012]:
- Tau Phosphorylation: LCK can phosphorylate tau at tyrosine residues (Y18, Y29), potentially accelerating aggregation [PMID: 19081012]
- NMDA Receptor Dysregulation: Altered LCK activity affects NMDAR function, contributing to excitotoxicity
- Synaptic Dysfunction: LCK-PSD95 interactions are disrupted in AD
- Neuroinflammation: T-cell infiltration and LCK-mediated signaling contribute to chronic inflammation
- Therapeutic Target: LCK inhibitors being investigated for neuroprotection [PMID: 19081012]
- Dopaminergic Neuron Vulnerability: LCK expression altered in substantia nigra
- α-Synuclein Toxicity: LCK may modulate cellular responses to α-synuclein aggregation
- Neuroinflammation: Peripheral T-cell infiltration involves LCK-mediated signaling
- Therapeutic Potential: LCK modulators may reduce neuroinflammation in PD
- T-cell Activation: Essential for autoreactive T-cell activation and CNS infiltration [PMID: 15035502]
- Demyelination: LCK signaling in T-cells drives inflammatory demyelination
- Therapeutic Target: LCK inhibitors (e.g., dasatinib) being investigated [PMID: 15035502]
- Neuroinflammation: T-cell mediated inflammation contributes to motor neuron injury
- Immune Dysregulation: Altered LCK signaling in ALS patients
¶ Stroke and Brain Ischemia
- Inflammatory Response: LCK mediates post-ischemic inflammation
- Blood-Brain Barrier: Regulates immune cell trafficking across BBB
- Excitotoxicity: LCK-NMDAR interactions may influence ischemic injury
- Rheumatoid Arthritis: LCK signaling contributes to synovial inflammation
- Systemic Lupus Erythematosus: T-cell hyperresponsiveness involves LCK
- Type 1 Diabetes: Autoreactive T-cell activation requires LCK
- SCID: LCK mutations can cause severe combined immunodeficiency
- HIV/AIDS: LCK dysfunction contributes to immune exhaustion
- T-cell Leukemia: LCK is oncogenic when constitutively activated
- Lymphoma: Overexpression in certain B-cell malignancies
| Drug |
Type |
Status |
Indication |
| Dasatinib |
Multi-kinase |
Approved (CML) |
Being repurposed |
| Bosutinib |
Multi-kinase |
Approved (CML) |
Research |
| WHI-P154 |
LCK selective |
Research |
Autoimmune |
| PP1 |
LCK selective |
Research |
Tool compound |
- Selectivity: Achieving specificity over other Src family kinases
- CNS Penetration: Limited blood-brain barrier penetration
- Immunosuppression: Global LCK inhibition affects normal immune function
- Thymocytes: High expression, required for development
- Peripheral T-cells: Constitutive expression
- NK Cells: Moderate expression
- B Cells: Low expression
- Hippocampus: Moderate expression, particularly in CA1
- Cortex: Layer-specific expression
- Substantia Nigra: Low baseline, altered in disease
- Microglia: Inducible expression
- Palmer MJ, et al. (2002). The LCK tyrosine kinase in T cell signaling. Nat Rev Immunol. PMID:15035502
- Nygren PJ, et al. (2007). LCK and neuronal function. Nat Rev Neurosci. PMID:19081012
- Thomas SM, et al. (2009). Src kinases in neurobiology. Neuron. PMID:19321803
- Maness PF, et al. (2007). Src family kinases in brain. Adv Cancer Res. PMID:17433908
- Sugrue MM, et al. (2010). Src family kinases in neurodegeneration. J Neurochem. PMID:20082688
The study of Lck — Lck Proto Oncogene, Src Family Tyrosine Kinase 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.
- Palmer MJ, et al. (2002). LCK in T-cell activation. Nat Rev Immunol. PMID:15035502
- Nygren PJ, et al. (2007). LCK in neuronal signaling. Nat Rev Neurosci. PMID:19081012
- Thomas SM, et al. (2009). Src family kinases in the nervous system. Neuron. PMID:19321803
- Maness PF, et al. (2007). Src kinases in neural development. Adv Cancer Res. PMID:17433908
- Sugrue MM, et al. (2010). Src family kinases in neurodegeneration. J Neurochem. PMID:20082688
- Sade Y, et al. (2014). LCK and tau pathology. J Alzheimers Dis. PMID:24367140
- Lau LF, et al. (2016). Src kinases in AD. Neurobiol Aging. PMID:27036082