RTN4 Gene

RTN4 (Reticulon 4 / Nogo)

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">RTN4 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>RTN4</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Reticulon 4</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>NOGO, KIAA0886, NSP</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>22q11.21</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>57142</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>604569</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000145113</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9NPD4</td>
</tr>
<tr>
<td class="label">Gene Type</td>
<td>Protein Coding</td>
</tr>
<tr>
<td class="label">Isoform</td>
<td>Amino Acids</td>
</tr>
<tr>
<td class="label">Nogo-A</td>
<td>~1,163 aa</td>
</tr>
<tr>
<td class="label">Nogo-B</td>
<td>~373 aa</td>
</tr>
<tr>
<td class="label">Nogo-C</td>
<td>~199 aa</td>
</tr>
<tr>
<td class="label">Cell Type</td>
<td>Isoform</td>
</tr>
<tr>
<td class="label">Cortical neurons</td>
<td>Nogo-A</td>
</tr>
<tr>
<td class="label">Hippocampal neurons</td>
<td>Nogo-A</td>
</tr>
<tr>
<td class="label">Oligodendrocytes</td>
<td>Nogo-A</td>
</tr>
<tr>
<td class="label">Astrocytes</td>
<td>Nogo-A, Nogo-B</td>
</tr>
<tr>
<td class="la

RTN4 (Reticulon 4 / Nogo)

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">RTN4 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>RTN4</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Reticulon 4</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>NOGO, KIAA0886, NSP</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>22q11.21</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>57142</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>604569</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000145113</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9NPD4</td>
</tr>
<tr>
<td class="label">Gene Type</td>
<td>Protein Coding</td>
</tr>
<tr>
<td class="label">Isoform</td>
<td>Amino Acids</td>
</tr>
<tr>
<td class="label">Nogo-A</td>
<td>~1,163 aa</td>
</tr>
<tr>
<td class="label">Nogo-B</td>
<td>~373 aa</td>
</tr>
<tr>
<td class="label">Nogo-C</td>
<td>~199 aa</td>
</tr>
<tr>
<td class="label">Cell Type</td>
<td>Isoform</td>
</tr>
<tr>
<td class="label">Cortical neurons</td>
<td>Nogo-A</td>
</tr>
<tr>
<td class="label">Hippocampal neurons</td>
<td>Nogo-A</td>
</tr>
<tr>
<td class="label">Oligodendrocytes</td>
<td>Nogo-A</td>
</tr>
<tr>
<td class="label">Astrocytes</td>
<td>Nogo-A, Nogo-B</td>
</tr>
<tr>
<td class="label">Microglia</td>
<td>Nogo-B</td>
</tr>
<tr>
<td class="label">Vascular endothelium</td>
<td>Nogo-B</td>
</tr>
<tr>
<td class="label">Peripheral tissues</td>
<td>Nogo-B, Nogo-C</td>
</tr>
<tr>
<td class="label">Protein</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">NgR1 (RTN4R)</td>
<td>Receptor binding</td>
</tr>
<tr>
<td class="label">LINGO-1</td>
<td>Coreceptor complex</td>
</tr>
<tr>
<td class="label">p75^NTR (NGFR)</td>
<td>Coreceptor complex</td>
</tr>
<tr>
<td class="label">RhoA</td>
<td>Downstream effector</td>
</tr>
<tr>
<td class="label">ROCK</td>
<td>Downstream effector</td>
</tr>
<tr>
<td class="label">Oligodendrocyte myelin</td>
<td>Structural</td>
</tr>
<tr>
<td class="label">Agent</td>
<td>Target</td>
</tr>
<tr>
<td class="label">IN-1 (anti-Nogo-A)</td>
<td>Nogo-A</td>
</tr>
<tr>
<td class="label">ATI-355</td>
<td>Nogo-A</td>
</tr>
<tr>
<td class="label">Opiicinumab (LINGO-1)</td>
<td>LINGO-1</td>
</tr>
<tr>
<td class="label">NgR1 decoys</td>
<td>NgR1</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">11 edges</a></td>
</tr>
</table>

Overview

RTN4 (Reticulon 4), also known as Nogo, encodes a family of reticulon proteins with three major isoforms: Nogo-A, Nogo-B, and Nogo-C["@schwab2010"]. RTN4 is most widely recognized for its role as a potent inhibitor of neurite outgrowth and axonal regeneration in the central nervous system (CNS). Nogo-A is expressed primarily in [neurons](/entities/neurons) and [oligodendrocytes](/cell-types/oligodendrocytes), where it acts through the Nogo-66 receptor (NgR) and its coreceptor LINGO-1 to suppress axon growth after injury["@pernet2012"].

Beyond regeneration inhibition, RTN4 plays critical roles in endoplasmic reticulum (ER) morphology and shaping, vascular development, and cellular stress responses. Dysregulated RTN4 has been implicated in multiple neurodegenerative diseases, including [Alzheimer's disease](/diseases/alzheimers-disease) (AD), [Parkinson's disease](/diseases/parkinsons-disease) (PD), [amyotrophic lateral sclerosis](/diseases/amyotrophic-lateral-sclerosis) (ALS), [multiple sclerosis](/diseases/multiple-sclerosis) (MS), and [stroke](/diseases/stroke)-related neurodegeneration["@acevedo2019"].

Gene Information

Protein Structure and Isoforms

RTN4 produces three major isoforms through alternative splicing and promoter usage:

The Nogo-66 loop (residues 1059-1160 in Nogo-A) is the critical region for receptor binding and growth cone collapse activity[@grandpre2000]. The N-terminal region of Nogo-A (amino acids 1-1000) is unique to this isoform and has independent growth-inhibitory properties.

All RTN4 isoforms share a C-terminal reticulon homology domain (RHD) consisting of two hydrophobic segments separated by a long loop. This domain localizes the protein to the ER membrane and plays a role in shaping ER tubules and sheets[@peng2018].

Normal Biological Functions

Axon Growth Inhibition (Nogo-A)

Nogo-A is the most potent axon growth inhibitor in the CNS[@schwab2010]:

This pathway evolved as a mechanism to stabilize established neural circuits and prevent inappropriate axonal sprouting in adults[@pernet2012].

ER Morphology and Function

All RTN4 isoforms contribute to ER network shaping[@peng2018]:

• ER tubule formation: RTN4 oligomerizes to shape curved ER tubules
• ER sheet architecture: Controls the density and distribution of ER sheets
• ER-contact sites: Organizes MAMs (mitochondria-ER contact sites)
• Protein quality control: ER morphology influences misfolded protein handling

Vascular Function (Nogo-B)

Nogo-B has distinct roles in vascular biology[@acevedo2019]:

• Angiogenesis regulation: Nogo-B modulates blood vessel formation and remodeling
• Endothelial cell migration: Controls vascular repair responses
• Blood-brain barrier: Nogo-B may influence BBB integrity and function
• Atheroprotection: Nogo-B deficiency promotes vascular remodeling

Role in Neurodegenerative Diseases

Alzheimer's Disease

In AD, RTN4/Nogo-A has complex, context-dependent roles:

• Synaptic stability: Nogo-A overexpression in hippocampal neurons may affect synaptic plasticity relevant to AD cognitive decline
• Amyloid-beta interaction: Studies suggest Nogo-A may modulate A-beta toxicity through effects on neuronal stress responses
• Cognitive function: Nogo-A is upregulated in AD brain and may contribute to impaired plasticity
• Therapeutic targeting: Anti-Nogo strategies have been explored to enhance neural repair in AD

Parkinson's Disease

RTN4 involvement in PD includes:

• Dopaminergic neuron survival: Nogo-A may limit regenerative capacity of [substantia nigra](/brain-regions/substantia-nigra) neurons
• Alpha-synuclein pathology: Potential intersection between RTN4 pathways and synuclein aggregation
• Mitochondrial function: Nogo-B at ER-mitochondrial contact sites may influence neuronal bioenergetics
• Therapeutic potential: Blocking Nogo-A could enhance dopaminergic axon sprouting

ALS (Amyotrophic Lateral Sclerosis)

In ALS, RTN4 may contribute to failed axon regeneration:

• Motor neuron vulnerability: Motor neurons show impaired regenerative responses, partly attributable to Nogo-A
• Oligodendrocyte dysfunction: ALS oligodendrocytes show altered Nogo-A expression
• Glial-neuronal signaling: Nogo-A from dysfunctional glia may inhibit motor axon maintenance
• Therapeutic approach: Anti-Nogo antibodies have shown benefit in ALS mouse models

Multiple Sclerosis

Nogo-A is most actively targeted in MS research:

• Demyelination context: Nogo-A inhibits remyelination and axon repair after myelin loss
• Blocking strategies: Anti-Nogo-A antibodies (e.g., IN-1) promote axon regeneration and remyelination in MS models
• Clinical trials: Anti-Nogo-A approaches have reached early-phase clinical testing
• Combination therapy: Nogo-A blockade + remyelination-promoting agents may be synergistic

Stroke and Cerebral Ischemia

After ischemic stroke[@diyora2011]:

• Nogo-A upregulation: Inhibits axonal sprouting and functional recovery
• BBB dysfunction: Nogo-B contributes to blood-brain barrier disruption post-stroke
• Rehabilitation enhancement: Nogo-A blockade augments rehabilitation-induced recovery in animal models
• Time window: Nogo-A blocking is most effective during subacute phase (days to weeks post-stroke)

Expression Pattern

RTN4 expression across tissues:

In the healthy adult brain, Nogo-A is expressed at low basal levels in neurons and sharply upregulated after injury. Nogo-B is constitutively expressed in brain vasculature and some glia.

Therapeutic Strategies

Nogo-A Antagonism

Multiple therapeutic approaches target Nogo-A[@oertle2003]:

• Anti-Nogo-A antibodies: IN-1, ATI-355, and humanized variants block Nogo-A receptor binding
• NgR1 antagonists: Small molecule and peptide blockers of the Nogo-66 receptor
• LINGO-1 antagonists: Decoy receptors and antibodies (opicinumab) block the coreceptor complex
• Nogo-A aptamers: RNA aptamers designed to sequester Nogo-A

Gene Therapy Approaches

• RTN4 knockdown: siRNA/shRNA targeting Nogo-A to promote axon regeneration
• Dominant-negative NgR: Viral expression of truncated NgR that acts as a decoy
• CRISPR-based: Targeting RTN4R (NgR1) gene for disruption

Cell-Based Strategies

• Nogo-A deficient glial precursors: Transplanted cells that lack Nogo-A may promote repair
• Exosome-mediated: Nogo-A neutralizing exosomes from engineered cells

Receptor Pathways

Nogo-66 Receptor (NgR1/RTN4R)

NgR1 (encoded by RTN4R) is the primary receptor for the Nogo-66 loop[@grandpre2000]:

• Ligands: Nogo-A, MAG, OMgp all bind NgR1
• Coreceptors: LINGO-1 + p75^NTR (in neurons) or TROY (alternative)
• Downstream: RhoA/ROCK pathway, leading to growth cone collapse[@liu2003]

Alternative Receptors

• S1PR2: Nogo-A can signal through sphingosine-1-phosphate receptor 2
• PirB: Paired immunoglobulin-like receptor B is an alternative NgR1-independent Nogo receptor

Interaction Partners

Animal Models and Research

Key findings from RTN4/Nogo research:

• Nogo-A knockout mice: Show enhanced axon sprouting and partial functional recovery after spinal cord injury
• Nogo-A/B double knockout: Further improved regeneration vs. single knockout
• NgR1 knockout mice: Reduced myelin inhibition and improved CNS repair
• Nogo-A transgenic overexpression: Confirms the inhibitory role in regeneration
• Non-human primate models: Anti-Nogo strategies show promise for primate CNS repair

Clinical Trials and Development

Research Directions

• Combination therapies: Nogo blockade + activity-based rehabilitation for maximal recovery
• Timing optimization: Determining the optimal window for Nogo-A antagonism
• Cell-type specificity: Targeting Nogo-A in specific cell types (neurons vs. glia)
• Biomarker development: Identifying biomarkers for patient selection

See Also

• [Oligodendrocyte Biology](/cell-types/oligodendrocytes) - Myelin-producing cells expressing Nogo-A
• [Axon Regeneration Failure](/mechanisms/axon-regeneration-failure) - Failed repair in neurodegeneration
• [ER Stress and Unfolded Protein Response](/mechanisms/er-stress-unfolded-protein-response) - RTN4 roles in ER
• [Stroke Mechanisms](/mechanisms/stroke-neurodegeneration) - Post-stroke axon regeneration
• [Multiple Sclerosis](/diseases/multiple-sclerosis) - Nogo-A as a therapeutic target
• [RTN4 Protein](/proteins/rtn4-protein) - Protein page
• [RTN1 Gene](/genes/rtn1), [RTN2 Gene](/genes/rtn2), [RTN3 Gene](/genes/rtn3) - Reticulon family members

External Links

• [NCBI Gene - RTN4](https://www.ncbi.nlm.nih.gov/gene/57142)
• [UniProt - Q9NPD4](https://www.uniprot.org/uniprot/Q9NPD4)
• [OMIM - 604569](https://www.omim.org/entry/604569)
• [GeneCards - RTN4](https://www.genecards.org/cgi-bin/carddisp.pl?gene=RTN4)

Pathway Diagram

The following diagram shows the key molecular relationships involving RTN4 Gene discovered through SciDEX knowledge graph analysis: