EFNA3 Gene — Ephrin A3

EFNA3 Gene — Ephrin A3

Introduction

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">EFNA3 Gene — Ephrin A3</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>EFNA3</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Ephrin A3</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>3q13.33</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>1944</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>602019</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000163407</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P52797</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>203 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~22 kDa</td>
</tr>
<tr>
<td class="label">Receptor</td>
<td>Binding Affinity</td>
</tr>
<tr>
<td class="label">EPHA3</td>
<td>High</td>
</tr>
<tr>
<td class="label">EPHA2</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">EPHA4</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">EPHA5</td>
<td>Low</td>
</tr>
<tr>
<td class="label">EPHA6</td>
<td>Low</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

EFNA3 Gene — Ephrin A3

Introduction

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">EFNA3 Gene — Ephrin A3</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>EFNA3</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Ephrin A3</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>3q13.33</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>1944</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>602019</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000163407</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P52797</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>203 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~22 kDa</td>
</tr>
<tr>
<td class="label">Receptor</td>
<td>Binding Affinity</td>
</tr>
<tr>
<td class="label">EPHA3</td>
<td>High</td>
</tr>
<tr>
<td class="label">EPHA2</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">EPHA4</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">EPHA5</td>
<td>Low</td>
</tr>
<tr>
<td class="label">EPHA6</td>
<td>Low</td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

EFNA3 (Ephrin A3) is a member of the ephrin family of membrane-bound ligands that play critical roles in neural development, synaptic plasticity, and cell-cell communication within the central nervous system. As a GPI-anchored protein, EFNA3 mediates bidirectional signaling with EPHA (Ephrin type-A receptor) tyrosine kinases, particularly EPHA3, influencing neuronal migration, axon guidance, synapse formation, and plasticity. Recent research has implicated EFNA3 in neurodegenerative diseases, including [Alzheimer's disease](/diseases/alzheimers-disease) and [Parkinson's disease](/diseases/parkinsons-disease), where it influences neuroinflammation, synaptic integrity, and neuronal survival. [@chen2023]

Overview

EFNA3 is one of five members of the ephrin-A family (EFNA1-5), each characterized by their GPI anchor and preference for binding EPHA class receptors. The EFNA3 gene encodes a protein expressed extensively in the developing and adult brain, with particularly high expression in the [hippocampus](/brain-regions/hippocampus), [cortex](/brain-regions/cortex), and [olfactory bulb](/brain-regions/olfactory-bulb). The protein serves multiple functions:

• Neural development: Guides neuronal migration and axon pathfinding
• Synaptogenesis: Regulates formation and maturation of synapses
• Plasticity: Modulates activity-dependent synaptic modifications
• Neuroinflammation: Controls microglial activation and neuroimmune signaling

Gene Information

Protein Structure and Function

Structural Features

EFNA3 possesses the characteristic structure of ephrin-A family members:

Forward Signaling (EFNA3 → EPHA)

Upon binding to EPHA receptors on neighboring cells, EFNA3 triggers forward signaling:

• Ras/MAPK pathway → cell growth and differentiation
• PI3K/Akt pathway → cell survival
• Rho GTPases → cytoskeletal reorganization

Reverse Signaling (EPHA → EFNA3)

EFNA3 can also receive signals from EPHA receptors:

Expression Pattern

Brain Regional Distribution

EFNA3 shows distinct regional expression in the central nervous system:

• Hippocampus: High expression in CA1-CA3 pyramidal neurons and dentate gyrus granule cells
• Cortex: Moderate expression in layer II-V pyramidal neurons
• Olfactory bulb: High expression in mitral and tufted cells
• Cerebellum: Expression in Purkinje cells and granule cells
• Thalamus and hypothalamus: Moderate expression in specific nuclei

Cellular Localization

• Neurons: Primary expression in excitatory neurons
• Astrocytes: Some expression in reactive astrocytes
• Microglia: Low baseline expression, upregulated in inflammation
• Vascular cells: Expression in endothelial cells and pericytes

Developmental Regulation

EFNA3 expression is tightly regulated during development:

• Embryonic: Early expression in neural tube and developing brain
• Postnatal: Peak expression during synaptogenesis (P14-P30 in mice)
• Adult: Lower but sustained expression in mature neurons
• Activity-dependent: Regulated by neuronal activity and experience

Role in Neural Development

Neuronal Migration

EFNA3 plays essential roles in neuronal migration during development:

• EPHA3-EFNA3 signaling regulates the proper positioning of neurons in cortical layers
• Migration defects observed in EFNA3 knockdown lead to laminar abnormalities
• The guidance cue function is particularly important for GABAergic interneuron migration

Axon Guidance

During development, EFNA3 acts as a guidance molecule:

• Serves as a repulsive cue for axonal tracts
• Helps establish topographic mappings in sensory systems
• Contributes to optic chiasm formation
• Guides callosal axon projections

Axonal Pruning

EFNA3 is involved in activity-dependent axon elimination:

• Regulates developmental pruning of inappropriate connections
• Modulates experience-dependent refinement of cortical circuits
• Deficiencies in this process may contribute to neurodevelopmental disorders

Synaptic Function

Synapse Formation

EFNA3 contributes to synapse formation and maturation:

Synaptic Plasticity

EFNA3 regulates both excitatory and inhibitory synaptic plasticity:

Excitatory plasticity

• Modulates LTP and LTD in hippocampal neurons
• Regulates AMPA receptor trafficking
• Controls dendritic spine morphology

• Influences GABAergic synapse function
• Modulates inhibitory circuit plasticity
• Affects feedforward and feedback inhibition [@xu2019]

Synaptic Transmission

EFNA3 signaling modulates synaptic transmission:

• Alters presynaptic release probability
• Regulates postsynaptic receptor function
• Controls synaptic vesicle dynamics
• Modulates network oscillation patterns

Neurodegenerative Disease Implications

Alzheimer's Disease

EFNA3 is implicated in Alzheimer's disease pathogenesis:

Amyloid-Beta Effects

• Amyloid-beta exposure modulates EFNA3 expression
• EFNA3 signaling influences amyloid clearance mechanisms
• Dysregulated EFNA3 contributes to amyloid-induced synaptic toxicity

• EFNA3 modifies tau phosphorylation through kinase/phosphatase pathways
• Tau pathology alters EFNA3 membrane trafficking
• Interaction affects dendritic spine integrity

• EFNA3 modulates microglial activation states
• Regulates cytokine production in response to AD pathology
• Therapeutic targeting reduces neuroinflammation [@zhang2020]

Parkinson's Disease

EFNA3 has been linked to Parkinson's disease:

• Genetic variants in EFNA3 associated with PD risk
• Expression changes in PD brain regions
• Role in dopaminergic neuron survival
• Implications for alpha-synuclein pathology [@song2018]

Other Neurodegenerative Conditions

• Amyotrophic lateral sclerosis (ALS): Altered EFNA3 in motor neurons
• Multiple sclerosis: Role in demyelination and remyelination
• Huntington's disease: EFNA3 in medium spiny neuron dysfunction

Genetic Studies

GWAS Associations

Genome-wide association studies have identified EFNA3 variants:

• Specific polymorphisms correlate with disease risk
• eQTL effects influence brain expression levels
• Haplotype analysis reveals protective and risk alleles

Functional Genomics

• CRISPR studies confirm EFNA3 roles in neuronal function
• Patient-derived iPSC neurons show variant-specific phenotypes
• Gene expression studies in disease tissue validate dysregulation

Neuroimmune Functions

Microglial Interactions

EFNA3 modulates microglial biology:

Neuroinflammatory Signaling

EFNA3 participates in neuroimmune crosstalk:

• Expression upregulated in response to inflammatory stimuli
• Controls blood-brain barrier function
• Modulates peripheral immune cell infiltration
• Therapeutic modulation reduces neuroinflammation [@yang2020]

Therapeutic Potential

Drug Development

Targeting EFNA3-EPHA3 signaling offers therapeutic opportunities:

Gene Therapy

• Viral vector delivery of EFNA3
• CRISPR-based correction of risk variants
• RNA interference for overexpression states

Biomarker Potential

• CSF EFNA3 levels as disease biomarkers
• Expression changes as treatment response indicators

Animal Models

Knockout Models

• Efna3 knockout mice: Viable with subtle behavioral phenotypes
• Conditional knockouts: Cell-type specific deletion reveals distinct functions
• Transgenic models: Overexpression models for gain-of-function studies

Disease Models

• Cross with APP/PSEN1 mice for AD studies
• Cross with alpha-synuclein models for PD studies
• Use in neuroinflammatory models

Interaction Network

Receptor Interactions

Signaling Partners

• Adaptors: Grb2, Crk, Nck
• Enzymes: RasGAP, PI3K, PLCγ
• Cytoskeletal proteins: Rho GTPases, cofilin
• Synaptic proteins: PSD-95, Synapsin

Cross-Linking

EFNA3 connects to multiple pathways:

• [EPHA3 Receptor](/proteins/epha3-receptor)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Synaptic Plasticity](/mechanisms/synaptic-plasticity)
• [Neuroinflammation](/mechanisms/neuroinflammation)
• [Microglia](/cell-types/microglia-neuroinflammation)
• [Hippocampus](/brain-regions/hippocampus)
• [Cortex](/brain-regions/cortex)
• [Axon Guidance](/mechanisms/axon-guidance)

Summary

EFNA3 (Ephrin A3) is a GPI-anchored ligand for EPHA receptors that plays essential roles in neural development, synaptic function, and neuroimmune regulation. Through bidirectional signaling with EPHA receptors, EFNA3 influences neuronal migration, axon guidance, synapse formation, and plasticity. In neurodegenerative diseases, EFNA3 dysfunction contributes to amyloid and tau pathology, neuroinflammation, and synaptic loss. The EFNA3-EPHA3 axis represents a promising therapeutic target for conditions including Alzheimer's disease and Parkinson's disease.

References

External Links

• [NCBI Gene: EFNA3](https://www.ncbi.nlm.nih.gov/gene/1944)
• [Ensembl: ENSG00000163407](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000163407)
• [UniProt: P52797](https://www.uniprot.org/uniprotkb/P52797)
• [GeneCards: EFNA3](https://www.genecards.org/cgi-bin/carddisp.pl?gene=EFNA3)