PLXNA1 Gene

PLXNA1 Gene

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">PLXNA1 Gene</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>PLXNA1</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>PLXNA1</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Gene</td>
</tr>
<tr>
<td class="label">NCBI</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/?term=PLXNA1" target="_blank">Search NCBI</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

PLXNA1 (Plexin A1) encodes a transmembrane receptor for semaphorins, playing critical roles in axonal guidance, neural circuit formation, and synaptic plasticity throughout development and in the adult nervous system.[@semaphorin2023][@plexin2022] As a member of the plexin family of guidance receptors, PLXNA1 regulates cytoskeletal dynamics through interactions with small GTPases and downstream signaling cascades. Dysregulation of PLXNA1 has been implicated in neurodegenerative diseases including Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS), as well as in cancer progression and neurodevelopmental disorders.[@plexin2021][@semaaplexina2020]

Gene Structure and Expression

The PLXNA1 gene is located on chromosome 3q21.3 and encodes a 2,018 amino acid transmembrane receptor protein with a molecular weight of approximately 210 kDa. The gene spans approximately 85 kb and consists of 31 exons.

Expression Pattern

PLXNA1 Gene

Overview

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">PLXNA1 Gene</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>PLXNA1</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>PLXNA1</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Gene</td>
</tr>
<tr>
<td class="label">NCBI</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/?term=PLXNA1" target="_blank">Search NCBI</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

PLXNA1 (Plexin A1) encodes a transmembrane receptor for semaphorins, playing critical roles in axonal guidance, neural circuit formation, and synaptic plasticity throughout development and in the adult nervous system.[@semaphorin2023][@plexin2022] As a member of the plexin family of guidance receptors, PLXNA1 regulates cytoskeletal dynamics through interactions with small GTPases and downstream signaling cascades. Dysregulation of PLXNA1 has been implicated in neurodegenerative diseases including Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS), as well as in cancer progression and neurodevelopmental disorders.[@plexin2021][@semaaplexina2020]

Gene Structure and Expression

The PLXNA1 gene is located on chromosome 3q21.3 and encodes a 2,018 amino acid transmembrane receptor protein with a molecular weight of approximately 210 kDa. The gene spans approximately 85 kb and consists of 31 exons.

Expression Pattern

PLXNA1 exhibits high expression in:

• Cerebral [cortex](/brain-regions/cortex) — Pyramidal [neurons](/entities/neurons) throughout all layers
• [Hippocampus](/brain-regions/hippocampus) — CA1-CA3 pyramidal cells and dentate gyrus granule cells
• Cerebellum — Purkinje cells
• Spinal cord — Motor neurons (alpha and gamma motor neurons)
• Dorsal root ganglia — Sensory neurons
• Developing brain — Particularly during embryogenesis and early postnatal periods

Protein Structure and Function

Domain Architecture

Plexin A1 contains several conserved domains:[@semaphorin2023][@plexin2018]

• Sema domain (~500 aa) — High-affinity semaphorin binding
• PSI domains (3x) — Plexin-Semaphorin-Integrin motifs
• IPT/TIG domains (4x) — Immunoglobulin-like folds

• Single-pass membrane anchor
• Dimerization interface

• Plexin homology (PH) domain — Contains GTPase-activating protein (GAP) activity[@plexin2018]
• C-terminal region — Required for downstream signaling

Semaphorin Ligands

PLXNA1 serves as a receptor for multiple Class 3 semaphorins:

• SEMA3A — Primary ligand, potent axonal repulsion[@semaamediated2021]
• SEMA3B — Tumor suppressor functions
• SEMA3C — Both repulsive and attractive effects
• SEMA3F — Anti-angiogenic properties
• SEMA3D — Mixed effects on axon guidance

Signaling Mechanisms

Upon semaphorin binding, PLXNA1 activates multiple downstream pathways:[@semaphorin2023][@plexin2022]

GTPase Regulation:

• GAP activity toward R-Ras, M-Ras, and Rap1[@plexin2018]
• Inactivation of integrins and promotion of growth cone collapse
• Regulation of actin cytoskeleton dynamics

• PI3K/Akt pathway — Cell survival signaling
• MAPK/ERK pathway — Growth and differentiation
• FAK activation — Focal adhesion turnover

• Growth cone collapse and axonal repulsion
• Dendritic branching modulation
• Synaptic structure remodeling[@plxna2022]
• Angiogenesis regulation

Disease Associations

Alzheimer's Disease

PLXNA1 is implicated in AD through multiple mechanisms:[@plexin2021]

Synaptic Dysfunction:

• Regulates dendritic spine morphology and synaptic plasticity[@plxna2022]
• SEMA3A/PLXNA1 signaling modulates AMPA receptor trafficking
• Dysregulated signaling contributes to synaptic loss in AD

• Critical for hippocampal circuit formation and function
• May influence [tau](/proteins/tau) pathology spread through connected networks
• Implicated in memory consolidation deficits[@semaphorinplexin2023]

• Aβ oligomers disrupt normal PLXNA1 signaling
• Altered semaphorin/plexin gradients in AD brain
• Potential for therapeutic targeting

Amyotrophic Lateral Sclerosis

PLXNA1 plays important roles in ALS pathophysiology:[@semaaplexina2020][@semaamediated2021]

Motor Neuron Vulnerability:

• Essential for axonal maintenance in upper and lower motor neurons
• SEMA3A toxicity mediated through PLXNA1
• Dysregulated axonal guidance signaling

• Regulates microtubule dynamics
• Impaired transport in ALS models
• Contributes to distal axonopathy

• SEMA3A antagonists protective in ALS models[@therapeutic2022]
• PLXNA1 modulators under investigation

Cancer

• PLXNA1 acts as a tumor suppressor in certain contexts[@plexin2019]
• Loss of PLXNA1 promotes tumor progression
• Anti-angiogenic therapy target

Neurodevelopmental Disorders

• Mutations associated with brain malformations
• Implicated in schizophrenia through GWAS
• Potential role in autism spectrum disorders

Molecular Mechanisms

Growth Cone Dynamics

PLXNA1-mediated semaphorin signaling controls growth cone behavior through:[@semaphorin2023][@plexin2022]

Synaptic Plasticity

At mature synapses, PLXNA1 regulates:[@plxna2022][@semaphorinplexin2023]

• Dendritic spine morphogenesis
• AMPA receptor trafficking
• [Long-term potentiation](/mechanisms/long-term-potentiation) (LTP) and depression (LTD)
• Homeostatic synaptic scaling

Neuroinflammation

Microglial and astrocyte responses are modulated by PLXNA1:

• Regulates cytokine production
• Affects glial scar formation
• Modulates neuroinflammation in disease states

Interaction Network

Protein-Protein Interactions

PLXNA1 interacts with:

• NRP1/NRP2 — Neuropilin co-receptors
• PLXNA2/PLXNA3/PLXNA4 — Plexin family members
• RND1/RND2/RND3 — Rho GTPase family
• FAK — Focal adhesion kinase
• SRC — Proto-oncogene tyrosine kinase
• PI3K — Phosphoinositide 3-kinase
• IQGAP1 — Scaffold protein

Signaling Pathways

Key downstream cascades:

• RhoA/ROCK — Cytoskeletal remodeling
• R-Ras GAP — Integrin signaling
• PI3K/Akt — Survival pathway
• MAPK/ERK — Proliferation/differentiation

Therapeutic Implications

Small Molecule Approaches

• SEMA3A inhibitors — Reduce semaphorin-mediated toxicity[@therapeutic2022]
• Plexin agonists — Promote neuroprotective signaling
• GAP domain modulators — Target downstream effectors

Gene Therapy

• AAV-mediated PLXNA1 modulation
• CRISPR approaches for mutation correction
• Cell-type specific targeting

Biomarkers

• PLXNA1 expression as a biomarker for neural circuit integrity
• Genetic variants for risk stratification

Research Directions

Current Areas of Investigation

Knowledge Gaps

• Mechanisms in sporadic AD
• Cell-type specific vulnerabilities
• Long-term effects of therapeutic modulation

Cross-references

• [PLXNA1 Protein](/proteins/plxna1-protein)
• [Axonal Guidance Mechanisms](/mechanisms/axonal-guidance)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
• [Semaphorin Signaling](/mechanisms/semaphorin-signaling)
• [PLXNA2 Gene](/genes/plxna2)
• [NRP1 Gene](/genes/nrp1)

See Also

• [ Protein](/proteins/plxna1-protein)
• [Axonal Guidance Mechanisms](/mechanisms/axonal-guidance)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)
• [Semaphorin Signaling](/mechanisms/semaphorin-signaling)

External Links

• [Ensembl: ENSG00000114554](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000114554)

References