LCK — LCK Proto-Oncogene, Src Family Tyrosine Kinase

LCK — LCK Proto-Oncogene, Src Family Tyrosine Kinase

Introduction

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.

<div class="infobox infobox-gene"> [@nygren2007]
<table> [@thomas2009]
<tr><th>Gene Symbol</th><td>LCK</td></tr> [@maness2007]
<tr><th>Full Name</th><td>LCK Proto-Oncogene, Src Family Tyrosine Kinase</td></tr> [@sugrue2010]
<tr><th>Chromosomal Location</th><td>1p35.2</td></tr> [@sade2014]
<tr><th>NCBI Gene ID</th><td>3932</td></tr> [@lau2016]
<tr><th>OMIM</th><td>153360</td></tr>
<tr><th>Ensembl</th><td>ENSG00000182866</td></tr>
<tr><th>UniProt</th><td>P06239</td></tr>
<tr><th>Protein</th><td>[Lck Protein](/proteins/lck-protein)</td></tr>
<tr><th>Associated Diseases</th><td>Autoimmune Disease, Immunodeficiency, T-cell Leukemia, Alzheimer's Disease, Parkinson's Disease</td></tr>
</table>
</div>

Overview

...

LCK — LCK Proto-Oncogene, Src Family Tyrosine Kinase

Introduction

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.

<div class="infobox infobox-gene"> [@nygren2007]
<table> [@thomas2009]
<tr><th>Gene Symbol</th><td>LCK</td></tr> [@maness2007]
<tr><th>Full Name</th><td>LCK Proto-Oncogene, Src Family Tyrosine Kinase</td></tr> [@sugrue2010]
<tr><th>Chromosomal Location</th><td>1p35.2</td></tr> [@sade2014]
<tr><th>NCBI Gene ID</th><td>3932</td></tr> [@lau2016]
<tr><th>OMIM</th><td>153360</td></tr>
<tr><th>Ensembl</th><td>ENSG00000182866</td></tr>
<tr><th>UniProt</th><td>P06239</td></tr>
<tr><th>Protein</th><td>[Lck Protein](/proteins/lck-protein)</td></tr>
<tr><th>Associated Diseases</th><td>Autoimmune Disease, Immunodeficiency, T-cell Leukemia, Alzheimer's Disease, Parkinson's Disease</td></tr>
</table>
</div>

Overview

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

Genomic Organization

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:

• p56^LCK^: Full-length isoform with myristoylation site
• p50^LCK^: Truncated isoform with different localization

Transcriptional Regulation

LCK expression is tightly regulated:

• Promoter Elements: Contains STAT, [NF-κB](/entities/nf-kb), and Ets family binding sites PMID:15035502
• Developmental Regulation: Expressed early in thymocyte development
• Tissue Specificity: Highest expression in T-cells, lower in [neurons](/entities/neurons)

Protein Structure

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) |

Key Regulatory Features

• 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

Normal Function

Immune System

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

Nervous System

In neurons, LCK participates in several important processes PMID: 19081012:

• Synaptic Plasticity: LCK regulates NMDA receptor phosphorylation and trafficking PMID:19081012
• [NMDA Receptor](/entities/nmda-receptor) Signaling: Phosphorylates NR2A/B subunits, modulating channel function
• PSD-95 Interactions: Participates in postsynaptic signaling complexes
• [Tau](/proteins/tau) Phosphorylation: Can phosphorylate [tau](/proteins/tau) at multiple sites
• Neuronal Survival: Regulates pro-survival and pro-apoptotic signaling

Other Functions

• Integrin Signaling: Modulates cell adhesion and migration
• Cytokine Receptor Signaling: Participates in IL-2 and other cytokine pathways
• Calcium Signaling: Upstream of NFAT activation

Role in Neurodegenerative Diseases

Alzheimer's Disease (AD)

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

Parkinson's Disease (PD)

• Dopaminergic Neuron Vulnerability: LCK expression altered in substantia nigra
• [α-Synuclein](/proteins/alpha-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

Multiple Sclerosis (MS)

• 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

Amyotrophic Lateral Sclerosis (ALS)

• 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](/entities/blood-brain-barrier): Regulates immune cell trafficking across BBB
• Excitotoxicity: LCK-NMDAR interactions may influence ischemic injury

Disease Associations

Autoimmune Disease

• 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

Immunodeficiency

• SCID: LCK mutations can cause severe combined immunodeficiency
• HIV/AIDS: LCK dysfunction contributes to immune exhaustion

Cancer

• T-cell Leukemia: LCK is oncogenic when constitutively activated
• Lymphoma: Overexpression in certain B-cell malignancies

Therapeutic Targeting

LCK Inhibitors in Development

| 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 |

Challenges

• Selectivity: Achieving specificity over other Src family kinases
• CNS Penetration: Limited blood-brain barrier penetration
• Immunosuppression: Global LCK inhibition affects normal immune function

Expression Pattern

Immune System

• Thymocytes: High expression, required for development
• Peripheral T-cells: Constitutive expression
• NK Cells: Moderate expression
• B Cells: Low expression

Nervous System

• [Hippocampus](/brain-regions/hippocampus): Moderate expression, particularly in CA1
• [Cortex](/brain-regions/cortex): Layer-specific expression
• Substantia Nigra: Low baseline, altered in disease
• [Microglia](/entities/microglia): Inducible expression

Key Publications

Palmer MJ, et al. (2002). The LCK tyrosine kinase in T cell signaling. Nat Rev Immunol. PMID: 15035502(https://pubmed.ncbi.nlm.nih.gov/15035502/)

Nygren PJ, et al. (2007). LCK and neuronal function. Nat Rev Neurosci. PMID: 19081012(https://pubmed.ncbi.nlm.nih.gov/19081012/)

Thomas SM, et al. (2009). Src kinases in neurobiology. Neuron. PMID: 19321803(https://pubmed.ncbi.nlm.nih.gov/19321803/)

Maness PF, et al. (2007). Src family kinases in brain. Adv Cancer Res. PMID: 17433908(https://pubmed.ncbi.nlm.nih.gov/17433908/)

Sugrue MM, et al. (2010). Src family kinases in neurodegeneration. J Neurochem. PMID: 20082688(https://pubmed.ncbi.nlm.nih.gov/20082688/)

Background

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.

See Also

• [Lck Protein](/proteins/lck-protein)
• SRC Gene - Another Src family kinase
• FYN Gene - Related Src family kinase
• LYN Gene - Another Src family kinase
• Tyrosine Kinases
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Multiple Sclerosis](/diseases/multiple-sclerosis)
• [Neuroinflammation](/entities/neuroinflammation) Pathway
• NMDA Receptor Signaling

External Links

• [NCBI Gene: 3932](https://www.ncbi.nlm.nih.gov/gene/3932)
• [UniProt: P06239](https://www.uniprot.org/uniprot/P06239)
• [OMIM: 153360](https://omim.org/entry/153360)
• [Ensembl: ENSG00000182866](https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000182866)
• [GeneCards: LCK](https://www.genecards.org/cgi-bin/carddisp.pl?gene=LCK)

References

[Palmer MJ, et al, (2002) (2002)](https://pubmed.ncbi.nlm.nih.gov/15035502/)

[Nygren PJ, et al, (2007) (2007)](https://pubmed.ncbi.nlm.nih.gov/19081012/)

[Thomas SM, et al, (2009) (2009)](https://pubmed.ncbi.nlm.nih.gov/19321803/)

[Maness PF, et al, (2007) (2007)](https://pubmed.ncbi.nlm.nih.gov/17433908/)

[Sugrue MM, et al, (2010) (2010)](https://pubmed.ncbi.nlm.nih.gov/20082688/)

[Sade Y, et al, (2014) (2014)](https://pubmed.ncbi.nlm.nih.gov/24367140/)

[Lau LF, et al, (2016) (2016)](https://pubmed.ncbi.nlm.nih.gov/27036082/)

Pathway Diagram

The following diagram shows the key molecular relationships involving LCK — LCK Proto-Oncogene, Src Family Tyrosine Kinase discovered through SciDEX knowledge graph analysis: