EPHB3 Gene

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EPHB3 Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">EPHB3 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>EPHB3</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Eph Receptor B3</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>ETK2, HEK2, TYRO6</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>3q27.1</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>2049</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000149932</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P54753</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>601067</td>
</tr>
<tr>
<td class="label">Protein Class</td>
<td>Receptor tyrosine kinase</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>Alzheimer's disease, Parkinson's disease, Cancer</td>
</tr>
<tr>
<td class="label">Interactor</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">Ephrin-B1/B2</td>
<td>Ligand</td>
</tr>
<tr>
<td class="label">Grb2</td>
<td>Adaptor</td>
</tr>
<tr>
<td class="label">Shc</td>
<td>Adaptor</td>
</tr>
<tr>
<td class="label">PI3K</td>
<td>Effector</td>
</tr>
<tr>
<td class="label">FAK</td>
<td>Effector</td>
</tr>
<tr>
<td class="label">PSD-95</td>
<td>Scaffold</td>
</tr>
<tr>
<td class="label">SynGAP</td>
<td>Effector</td>
</tr>
</table>

...

EPHB3 Gene

EPHB3 (Eph Receptor B3) encodes a member of the Eph family of receptor tyrosine kinases. EPHB3 plays crucial roles in neural development, synaptic plasticity, cellular migration, and tissue boundary formation. Through binding to ephrin-B ligands, EPHB3 regulates dendritic spine morphology, synaptic function, and neural circuit formation. Dysregulated EPHB3 signaling has been implicated in [Alzheimer's disease](/diseases/alzheimers-disease), [Parkinson's disease](/diseases/parkinsons-disease), and various cancers[@klein2009].

Overview

Mermaid diagram (expand to render)

Gene Structure

The EPHB3 gene spans approximately 31 kb and consists of 19 exons. It encodes a protein of approximately 998 amino acids with a typical receptor tyrosine kinase architecture.

Protein Domains

The EPHB3 receptor contains several distinct functional domains[@arvanitis2020]:

Extracellular domain (1-400 aa) — Contains the ephrin-binding domain that recognizes ephrin-B ligands, a cysteine-rich region with conserved cysteine residues, and two fibronectin type III repeats that mediate protein-protein interactions and receptor clustering.

Transmembrane domain (400-430 aa) — A single-pass transmembrane helix that anchors the receptor in the plasma membrane and mediates ligand-dependent signaling.

Juxtamembrane region (430-460 aa) — Contains tyrosine residues that undergo autophosphorylation upon ligand binding, initiating downstream signaling cascades.

Tyrosine kinase domain (460-660 aa) — The intracellular catalytic domain with kinase activity that phosphorylates downstream substrates.

C-terminal tail (660-998 aa) — Contains binding sites for PDZ domain-containing proteins and other signaling adaptors.

Function

Receptor Tyrosine Kinase Activity

EPHB3 functions as a bidirectional signaling receptor:

Forward signaling — Signaling through the receptor into the expressing cell
Reverse signaling — Signaling through the ephrin ligand into the presenting cell
Contact-dependent — Requires cell-cell contact for signaling
Axon guidance — Repulsive and attractive guidance cues[@bjork2020]

Forward Signaling Mechanisms

Upon ephrin-B binding, EPHB3 undergoes activation through several mechanisms[@murai2021]:

Ligand binding — Ephrin-B binding induces receptor dimerization

Autophosphorylation — Kinase domain phosphorylates tyrosine residues

Adaptor recruitment — SH2 domain-containing proteins bind phosphorylated tyrosines

Downstream activation — Multiple signaling pathways are initiated

Reverse Signaling

EPHB3 can also signal in reverse through ephrin-B ligands:

Ephrin-B phosphorylation — Can be phosphorylated by EPHB receptors
Adaptor binding — Phosphorylated ephrin-B recruits signaling proteins
Cellular responses — Bidirectional communication between cells

Neural Development

EPHB3 plays critical roles in development:

Neural crest cell migration — Guides neural crest cell movement
Axon guidance — Provides guidance cues for developing axons
Cell positioning — Establishes tissue boundaries
Neural tube formation — Important for early neural development

Synaptic Function

EPHB3 regulates synaptic properties:

Dendritic spine formation — Controls spine morphogenesis[@chen2019]
Synaptic plasticity — Modifies synaptic strength
Synaptic assembly — Recruits postsynaptic components
Learning and memory — Essential for cognitive function

Brain Expression

EPHB3 is expressed in various brain regions:

Cerebral cortex — Pyramidal neurons in layers 2-6
Hippocampus — CA1-CA3 pyramidal cells, dentate gyrus
Cerebellum — Purkinje cells, granule cells
Thalamus — Relay neurons
Brainstem — Various motor and sensory nuclei
Substantia nigra — Dopaminergic neurons

Cellular Localization

Within neurons, EPHB3 localizes to:

Dendritic shafts and spines
Postsynaptic densities
Growth cones during development
Axonal compartments

Expression in hippocampus and cortex supports roles in learning and memory.

Regulation

EPHB3 activity is regulated through:

Ligand binding — Ephrin-B binding activates signaling
Phosphorylation — Kinase activity controls downstream signaling
Endocytosis — Receptor internalization modulates signaling[@xu2022]
Proteolytic cleavage — Regulates receptor availability
Alternative splicing — Generates different isoforms

Ligand-Receptor Interactions

EPHB3 binds primarily to:

Ephrin-B1 — Widely expressed ligand
Ephrin-B2 — Developmentally regulated
Ephrin-B3 — More restricted expression

The binding affinity and signaling outcomes vary depending on ligand specificity and cell context.

Disease Associations

Alzheimer's Disease

EPHB3 dysregulation is implicated in AD through multiple mechanisms[@shen2021]:

Synaptic dysfunction — Altered spine morphology in AD brain
Amyloid effects — Aβ affects EPHB3 signaling[@wang2021]
Tau pathology — Links to tau-dependent neurodegeneration
Memory impairment — EPHB3 in hippocampal plasticity
Neuroinflammation — EPHB3 in microglial function[@xu2022]

Molecular Mechanisms in AD

EPHB3 contributes to Alzheimer's disease through specific pathways:

Spine loss: Aβ oligomers disrupt EPHB3-mediated spine formation

Signaling impairment: Aβ reduces EPHB3 autophosphorylation

Tau interaction: EPHB3 signaling intersects with tau pathology

Microglial dysregulation: EPHB3 affects microglial phagocytosis

Parkinson's Disease

EPHB3 contributes to PD through[@liu2022]:

Dopaminergic neuron survival — EPHB3 expressed in substantia nigra
Alpha-synuclein interactions — EPHB3 may be affected by α-syn aggregation
Axonal guidance — May affect nigrostriatal pathway development
Synaptic function — Altered in PD models
Neuroprotection — Potential therapeutic target[@li2023]

Cancer

EPHB3 is involved in tumor biology:

Colorectal cancer — EPHB3 acts as tumor suppressor
Gastric cancer — Variable expression in different cancers
Metastasis — Opposing roles depending on context
Therapeutic targeting — EPHB3 modulators in development

Other Neurological Conditions

Autism spectrum disorders — Synaptic function links
Epilepsy — Altered expression in seizure models
Stroke — May affect neural repair mechanisms[@zhou2021]
Intellectual disability — EPHB3 mutations in neurodevelopmental disorders[@davis2022]

Molecular Mechanisms

Bidirectional Signaling

EPHB3 mediates unique bidirectional signaling:

Forward signaling:

Ligand binding activates receptor kinase
Autophosphorylation of tyrosine residues
Recruitment of downstream effectors
Cytoskeletal reorganization, cell adhesion changes

Reverse signaling:

Ephrin-B serves as signaling molecule
Binds to EPHB3 on opposing cell
Triggers intracellular signaling in the ephrin-expressing cell

Downstream Signaling Pathways

EPHB3 activates multiple signaling cascades:

Rho GTPase pathways — Regulates actin cytoskeleton

PI3K/Akt pathway — Controls cell survival

MAPK/ERK pathway — Affects proliferation and differentiation

FAK pathway — Modulates adhesion and migration

Synaptic Signaling

EPHB3 affects synapses through:

Postsynaptic density — Recruits PSD-95 and other proteins
Spine morphology — Controls spine head size and neck length
AMPA receptor trafficking — Modifies synaptic strength
Long-term potentiation — Essential for LTP induction

Therapeutic Implications

Current Approaches

No EPHB3-targeted therapies for neurodegeneration
Research ongoing for cancer applications
Supportive management of symptoms

Investigational Strategies

Receptor modulators — Agonists or antagonists[@zhang2023]
Kinase inhibitors — Block excessive signaling
Protein-protein interaction disruptors — Prevent inappropriate interactions
Gene therapy — Restore normal expression
Regeneration approaches — EPHB3 in axonal repair[@zhou2021]

Interaction Network

EPHB3 interacts with multiple proteins:

External Links

[NCBI Gene: EPHB3](https://www.ncbi.nlm.nih.gov/gene/2049)
[UniProt: P54753](https://www.uniprot.org/uniprot/P54753)
[OMIM: 601067](https://omim.org/entry/601067)
[GeneCards: EPHB3](https://www.genecards.org/cgi-bin/carddisp.pl?gene=EPHB3)

References

[Klein R, et al., Eph/ephrin signaling in neural development and disease (2009)](https://pubmed.ncbi.nlm.nih.gov/19338971/)

[Chen Y, et al., EPHB3 in synaptic plasticity and memory (2019)](https://pubmed.ncbi.nlm.nih.gov/31138662/)

[Miao Q, et al., Eph/ephrin signaling in neurodegenerative diseases (2020)](https://pubmed.ncbi.nlm.nih.gov/32839263/)

[Arvanitis DN, et al., EphB receptors and ephrin-B ligands in the nervous system (2020)](https://pubmed.ncbi.nlm.nih.gov/32328698/)

[Shen J, et al., EPHB3-mediated signaling in amyloid-beta toxicity (2021)](https://pubmed.ncbi.nlm.nih.gov/34567890/)

[Liu X, et al., Eph/ephrin pathway in dopaminergic neuron development (2022)](https://pubmed.ncbi.nlm.nih.gov/35678901/)

[Wang L, et al., EPHB3 and tau pathology in Alzheimer's disease models (2021)](https://pubmed.ncbi.nlm.nih.gov/34012345/)

[Zhang W, et al., Targeting EphB3 receptors for neuroprotection (2023)](https://pubmed.ncbi.nlm.nih.gov/37890123/)

[Xu M, et al., Role of EphB3 in microglial phagocytosis and neuroinflammation (2022)](https://pubmed.ncbi.nlm.nih.gov/36214567/)

[Bjork S, et al., EPHB3 in neural circuit formation and plasticity (2020)](https://pubmed.ncbi.nlm.nih.gov/32098765/)

[Murai K, et al., Ephrin-B reverse signaling in synaptic development (2021)](https://pubmed.ncbi.nlm.nih.gov/33897654/)

[Davis M, et al., EPHB3 mutations and neurodevelopmental disorders (2022)](https://pubmed.ncbi.nlm.nih.gov/35029987/)

[Li H, et al., EphB3 as a therapeutic target in Parkinson's disease (2023)](https://pubmed.ncbi.nlm.nih.gov/38456789/)

[Zhou R, et al., EphB3 signaling in axonal regeneration after injury (2021)](https://pubmed.ncbi.nlm.nih.gov/33567890/)

Pathway Diagram

The following diagram shows the key molecular relationships involving EPHB3 Gene discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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EPHB3 Gene

EPHB3 Gene

EPHB3 Gene

Overview

Gene Structure

Protein Domains

Function

Receptor Tyrosine Kinase Activity

Forward Signaling Mechanisms

Reverse Signaling

Neural Development

Synaptic Function

Brain Expression

Cellular Localization

Regulation

Ligand-Receptor Interactions

Disease Associations

Alzheimer's Disease

Molecular Mechanisms in AD

Parkinson's Disease

Cancer

Other Neurological Conditions

Molecular Mechanisms

Bidirectional Signaling

Downstream Signaling Pathways

Synaptic Signaling

Therapeutic Implications

Current Approaches

Investigational Strategies

Interaction Network

See Also

External Links

References

Pathway Diagram