FLT3 Protein

FLT3 Protein — FMS-like Tyrosine Kinase 3

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">FLT3</th></tr>
<tr><td><strong>Protein Name</strong></td><td>FMS-like Tyrosine Kinase 3</td></tr>
<tr><td><strong>Gene</strong></td><td>[FLT3](/genes/flt3)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[P36888](https://www.uniprot.org/uniprot/P36888)</td></tr>
<tr><td><strong>Protein Family</strong></td><td>Receptor tyrosine kinase, PDGFR family</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>~143 kDa</td></tr>
<tr><td><strong>Expression</strong></td><td>Hematopoietic cells, brain ([neurons](/entities/neurons), microglia)</td></tr>
<tr><td><strong>Ligands</strong></td><td>FLT3 ligand (FL)</td></tr>
</table>
</div>

Overview

FLT3 (FMS-like Tyrosine Kinase 3) is a class III receptor tyrosine kinase expressed primarily in hematopoietic progenitor cells. While best characterized in acute myeloid leukemia (AML), FLT3 is also expressed in the central nervous system, where it plays important roles in neuronal development, survival, and immune function. Emerging research suggests FLT3 signaling may be relevant to neurodegenerative diseases, particularly [Alzheimer's disease](/diseases/alzheimers-disease) and [Parkinson's disease](/diseases/parkinsons-disease), through effects on [microglia](/cell-types/microglia-neuroinflammation) and neuroinflammation [1].

Structure and Signaling

Receptor Architecture

FLT3 Protein — FMS-like Tyrosine Kinase 3

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">FLT3</th></tr>
<tr><td><strong>Protein Name</strong></td><td>FMS-like Tyrosine Kinase 3</td></tr>
<tr><td><strong>Gene</strong></td><td>[FLT3](/genes/flt3)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[P36888](https://www.uniprot.org/uniprot/P36888)</td></tr>
<tr><td><strong>Protein Family</strong></td><td>Receptor tyrosine kinase, PDGFR family</td></tr>
<tr><td><strong>Molecular Weight</strong></td><td>~143 kDa</td></tr>
<tr><td><strong>Expression</strong></td><td>Hematopoietic cells, brain ([neurons](/entities/neurons), microglia)</td></tr>
<tr><td><strong>Ligands</strong></td><td>FLT3 ligand (FL)</td></tr>
</table>
</div>

Overview

FLT3 (FMS-like Tyrosine Kinase 3) is a class III receptor tyrosine kinase expressed primarily in hematopoietic progenitor cells. While best characterized in acute myeloid leukemia (AML), FLT3 is also expressed in the central nervous system, where it plays important roles in neuronal development, survival, and immune function. Emerging research suggests FLT3 signaling may be relevant to neurodegenerative diseases, particularly [Alzheimer's disease](/diseases/alzheimers-disease) and [Parkinson's disease](/diseases/parkinsons-disease), through effects on [microglia](/cell-types/microglia-neuroinflammation) and neuroinflammation [1].

Structure and Signaling

Receptor Architecture

FLT3 is a type I transmembrane receptor consisting of:

• Extracellular domain: 5 immunoglobulin-like domains for ligand binding
• Transmembrane helix: Single pass through the membrane
• Juxtamembrane domain: Contains regulatory motifs
• Kinase domain: Intracellular tyrosine kinase activity
• C-terminal tail: Contains tyrosine residues for signaling

Activation Mechanism

FLT3 signaling involves:

Expression in the Brain

Cellular Distribution

In the nervous system, FLT3 is expressed in:

• Microglia: Primary immune cells of the brain
• Neurons: Developmental expression, lower in adults
• Neural progenitor cells: During neurogenesis
• Endothelial cells: [Blood-brain barrier](/entities/blood-brain-barrier) component

Functions in the CNS

FLT3 signaling in the brain regulates:

• Microglial activation: Modulates inflammatory responses
• Neuronal survival: Neurotrophic effects during development
• Synaptic plasticity: Activity-dependent modifications
• Blood-brain barrier: Endothelial function

FLT3 in Neurodegenerative Diseases

Alzheimer's Disease

FLT3 contributes to [Alzheimer's disease](/diseases/alzheimers-disease) pathogenesis through microglial pathways:

Neuroinflammation

Microglial FLT3 signaling promotes inflammatory responses:

• Increased pro-inflammatory cytokine production
• Enhanced phagocytic activity
• Potential effects on amyloid clearance

Amyloid Interaction

Evidence for FLT3-amyloid interactions:

• FLT3 expression increases in AD microglia
• Amyloid may act as a FLT3 ligand
• Dysregulated inflammation in AD brains

Parkinson's Disease

In [Parkinson's disease](/diseases/parkinsons-disease), FLT3 may play roles in:

Neuroinflammation

FLT3 as a therapeutic target for neuroinflammation:

• FLT3 inhibitors reduce microglial activation
• Potential for disease modification
• Selective targeting in the CNS

FLT3 in Neurodevelopment

Neuronal Development

During brain development, FLT3:

• Promotes neuronal progenitor proliferation
• Supports differentiation
• Regulates migration
• Influences synapse formation

Therapeutic Potential

Understanding FLT3 in development suggests:

• Developmental disorder treatments
• Regenerative medicine approaches
• Stem cell therapy enhancement

Clinical Implications

FLT3 Inhibitors

FDA-approved FLT3 inhibitors (primarily for AML) include:

• Midostaurin
• Gilteritinib
• Quizartinib

• Reduce neuroinflammation
• Modulate microglial function
• Combined with other therapies

Biomarker Potential

FLT3 expression may serve as:

• Marker of microglial activation
• Biomarker for disease progression
• Therapeutic response indicator

Summary

FLT3 is a receptor tyrosine kinase expressed in microglia and neurons in the central nervous system. While extensively studied in hematological malignancies, FLT3 signaling in the brain influences neuroinflammation, microglial function, and neuronal survival. Dysregulated FLT3 activity contributes to the pathogenesis of Alzheimer's disease, Parkinson's disease, and other neurodegenerative disorders through effects on inflammatory processes. FLT3 represents a potential therapeutic target for modulating neuroinflammation in these conditions.

See Also

• [Alzheimer's disease](/diseases/alzheimers-disease)
• [Parkinson's disease](/diseases/parkinsons-disease)

External Links

• [PubMed](https://pubmed.ncbi.nlm.nih.gov/)
• [KEGG Pathways](https://www.genome.jp/kegg/pathway.html)

References