Nogo Protein

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Nogo Protein

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Nogo Protein

<table class="infobox infobox-protein">
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<th class="infobox-header" colspan="2">nogo</th>
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<tr>
<td class="label">Symbol</td>
<td><strong>NOGO</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>nogo</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=NOGO" target="_blank">Search UniProt</a></td>
</tr>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
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Overview

Nogo Protein is a member of the reticulon family of proteins encoded by the [RTN4](/genes/rtn4) gene (also known as Reticulon 4). Nogo proteins are among the most potent known inhibitors of axonal regeneration in the central nervous system (CNS), playing a critical role in regulating neural circuit plasticity, regeneration failure after injury, and potentially in neurodegenerative disease progression.

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Nogo Protein

<table class="infobox infobox-protein">
<tr>
<th class="infobox-header" colspan="2">nogo</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>NOGO</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>nogo</td>
</tr>
<tr>
<td class="label">Type</td>
<td>Protein</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/?query=NOGO" target="_blank">Search UniProt</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>

Overview

Mermaid diagram (expand to render)

Nogo Protein is a member of the reticulon family of proteins encoded by the [RTN4](/genes/rtn4) gene (also known as Reticulon 4). Nogo proteins are among the most potent known inhibitors of axonal regeneration in the central nervous system (CNS), playing a critical role in regulating neural circuit plasticity, regeneration failure after injury, and potentially in neurodegenerative disease progression.

Gene: [RTN4](/genes/rtn4) (Reticulon 4) UniProt: Q9N4L5 (Human) Molecular Weight: 40-250 kDa depending on isoform Brain Expression: High in oligodendrocytes, moderate in neurons Subcellular Localization: Endoplasmic reticulum, plasma membrane, myelin sheaths

Discovery and Nomenclature

Nogo was first identified as a myelin-associated neurite outgrowth inhibitor in the early 1990s. The name "Nogo" derives from the recognition of its role as an inhibitor of neurite (axon) growth. Three independent research groups identified the protein around 2000, leading to multiple designations:

Nogo-A: The longest isoform, specific to the CNS myelin
Nogo-B: A shorter isoform expressed in non-neuronal tissues
Nogo-C: The shortest isoform, expressed primarily in testis and muscle

The protein was originally characterized as the "myelin-associated neurite growth inhibitor" or "NI-35" in early literature, with the Nogo nomenclature becoming standard after the molecular identification of the protein in 2000.

Structure

Isoforms and Domain Organization

Nogo is produced from a single gene through alternative splicing, generating at least three major isoforms:

Nogo-A (1163 amino acids, ~200 kDa):

Contains the reticulon domain at the C-terminus
Two distinct inhibitory regions: Nogo-66 (residues 1029-1060) and Nogo-A-specific region (Nogo-A Δ20)
Predominantly expressed in oligodendrocytes and CNS myelin
The Nogo-66 region comprises a 66-amino acid extracellular loop that binds to the Nogo-66 receptor (NgR1)

Nogo-B (199 amino acids, ~25 kDa):

Contains the reticulon domain but lacks the Nogo-A-specific region
Expressed in various tissues including heart, lung, liver, and endothelial cells
May have roles in vascular development and tissue remodeling

Nogo-C (175 amino acids, ~20 kDa):

Smallest isoform, containing primarily the reticulon domain
Expressed predominantly in testis, with lower expression in skeletal muscle
Function in the CNS is less well characterized

Reticulon Domain

All Nogo isoforms contain the conserved reticulon domain (~180 amino acids) characterized by:

Two large hydrophobic regions that traverse the membrane
A hydrophilic loop facing the extracellular space
This domain is shared with other reticulon family members (RTN1, RTN2, RTN3/RTN4L)

Three-Dimensional Structure

The structure of Nogo remains partially characterized due to the challenges of studying membrane proteins. However, key features are known:

The Nogo-66 region forms a loop that extends from the myelin membrane
The reticulon domain creates a hairpin structure in the membrane
The protein likely forms oligomers that enhance its inhibitory activity

Normal Function

Role in CNS Development

During development, Nogo-A plays crucial roles in neural circuit formation:

Axon guidance and pruning:

Nogo-A contributes to the refinement of neural connections by limiting aberrant axonal sprouting
Helps establish proper patterns of neuronal connectivity during development
The protein is thought to contribute to developmental axon pruning, a process where excess or inappropriate connections are eliminated

Myelin formation and maintenance:

As a myelin-associated protein, Nogo contributes to the structural integrity of myelin sheaths
May help maintain the隔离 (insulation) properties of myelin

Synaptic plasticity regulation:

Nogo-A and NgR1 signaling can influence synaptic plasticity in the mature CNS
May help stabilize established neural circuits

Physiological Roles Beyond CNS

In non-neuronal tissues, Nogo-B appears to have distinct functions:

Vascular system:

Regulates endothelial cell function and angiogenesis
May play roles in vascular remodeling and response to injury

Cellular stress responses:

Involved in endoplasmic reticulum stress signaling
May regulate apoptosis under certain conditions

The Nogo-66 Receptor System

NgR1 (Nogo-66 Receptor)

The Nogo-66 receptor (NgR1), encoded by the RTN4R gene, is a GPI-anchored protein that mediates the inhibitory effects of Nogo-66. Key characteristics:

Binds Nogo-A, OMgp, and MAG (myelin-associated glycoprotein) — the three major myelin-associated inhibitors
Does not have a transmembrane domain; relies on co-receptors for signal transduction
Expressed primarily in neurons, particularly in the CNS

Co-receptors and Signaling

NgR1 signals through a complex of co-receptors:

p75 neurotrophin receptor (NTR):

Formerly thought to be a critical co-receptor for NgR1 signaling
Forms a complex with NgR1 to transduce the inhibitory signal
Activates RhoA pathway leading to growth cone collapse

Lingo-1:

A leucine-rich repeat and immunoglobulin-like domain-containing neurite outgrowth inhibitor protein
Forms a ternary complex with NgR1 and p75
Essential for NgR1-mediated inhibition of neurite outgrowth

TROY/TNFRRSF19:

An alternative to p75 in some neuronal populations
Can also mediate NgR1 signaling in the absence of p75

Intracellular Signaling Pathways

Upon ligand binding, NgR1 activates several downstream pathways:

RhoA/ROCK pathway: Primary pathway leading to growth cone collapse

cAMP/PKA pathway: Myelin inhibitors elevate cAMP, which contributes to inhibition

p38 MAPK pathway: Involved in cytoskeletal reorganization

STAT3 pathway: May contribute to the inflammatory response

Role in Neurodegeneration

Multiple Sclerosis and Demyelinating Diseases

Nogo-A has been extensively studied in the context of multiple sclerosis (MS):

Expression changes in MS:

Nogo-A expression is altered in demyelinating lesions
Both upregulation and downregulation have been reported depending on disease stage
May be upregulated by inflammatory cytokines

Therapeutic targeting:

Anti-Nogo-A antibodies have been developed to block the inhibitory effects
Goal is to promote remyelination and axonal regeneration
Several clinical trials have tested this approach

Alzheimer's Disease

Emerging evidence suggests Nogo-A may play a role in Alzheimer's disease pathogenesis:

Amyloid interactions:

Nogo-A may interact with amyloid-beta pathology
Some studies suggest Nogo-A expression is altered in AD brains
May affect amyloid-induced synaptic dysfunction

Synaptic plasticity effects:

Nogo-A/NgR1 signaling can impair synaptic plasticity
May contribute to memory deficits in AD
The receptor is expressed in hippocampal neurons critical for learning and memory

Therapeutic implications:

Modulating Nogo-A signaling might enhance synaptic plasticity in AD
Some studies suggest Nogo-A antibodies could have beneficial effects

Parkinson's Disease

Nogo-A may influence dopaminergic neuron survival:

Dopaminergic neuron studies:

Nogo-A is expressed in the substantia nigra
Some evidence suggests it may affect dopaminergic neuron viability
The protein may influence neuroprotection in PD models

Therapeutic potential:

Nogo-A blocking strategies might protect dopaminergic neurons
Could enhance the effectiveness of cell replacement therapies

Spinal Cord Injury

This is the most extensively studied context for Nogo-A targeting:

Mechanisms:

After spinal cord injury, Nogo-A inhibits axonal regeneration
Contributes to the failure of functional recovery
Neutralizing Nogo-A promotes axonal sprouting and regeneration

Therapeutic approaches:

Anti-Nogo-A antibodies (e.g., ATI-355, ozanezumab)
NgR1 antagonists and decoy receptors
Peptide blockers of Nogo-66 (e.g., NEP1-40)

Clinical trials:

Several Phase I/II trials have tested anti-Nogo-A antibodies
Results have been mixed, with some showing modest benefits

Amyotrophic Lateral Sclerosis (ALS)

Potential roles:

Nogo-A expression is altered in ALS
May influence motor neuron survival
Some studies suggest a neuroprotective role in certain contexts

Stroke and Brain Injury

Therapeutic potential:

Anti-Nogo-A antibodies enhance recovery in animal models of stroke
Promotes axonal sprouting and functional rehabilitation
Several clinical trials have investigated this approach

Therapeutic Targeting

Anti-Nogo-A Antibodies

ATI-355 (Novartis):

Humanized anti-Nogo-A antibody
Tested in Phase I clinical trials for spinal cord injury
Showed acceptable safety profile

Ozanezumab (GSK1223249):

Monoclonal antibody against Nogo-A
Tested in both MS and spinal cord injury trials
Did not show significant efficacy in primary endpoints

NgR1 Antagonists

NEP1-40:

A peptide antagonist derived from the Nogo-66 region
Competes with Nogo-66 for NgR1 binding
Promotes axonal regeneration in animal models

NgR1-Fc decoy receptor:

Soluble NgR1 protein that acts as a decoy
Binds and neutralizes myelin-associated inhibitors
Tested in animal models of spinal cord injury

Small Molecule Inhibitors

RhoA/ROCK inhibitors:

Y-27632, fasudil
Block downstream signaling from NgR1
Promote neurite outgrowth in vitro

cAMP-elevating agents:

Rolipram, cAMP analogs
Overcome myelin-associated inhibition
Enhance axonal regeneration in vivo

Gene Therapy Approaches

Viral delivery of Nogo-A shRNA or siRNA
Gene editing approaches to reduce Nogo-A expression
Engineering cells to express NgR1 antagonists

Clinical Trials

Completed Clinical Trials

NCT00415467 - Phase I trial of anti-Nogo-A antibody in acute spinal cord injury (Novartis)

NCT01435747 - Phase II trial of ozanezumab in MS (GlaxoSmithKline)

NCT02398494 - Phase II trial of ozanezumab in spinal cord injury (GlaxoSmithKline)

NCT00870038 - Phase I trial of anti-Nogo-A in stroke (Novartis)

Outcomes

Overall, clinical trials have shown mixed results:

Safety profiles have been acceptable
Efficacy has been limited in the primary endpoints
Some post-hoc analyses suggested benefits in certain patient subgroups
Further optimization of dosing, timing, and patient selection may improve outcomes

Animal Model Studies

Spinal Cord Injury Models

Rodent studies:

Anti-Nogo-A antibodies promote significant axonal regeneration
Enhanced functional recovery in gait, locomotion, and sensory tests
Combination with rehabilitation enhances benefits
Timing of treatment is critical — early intervention more effective

Non-human primate studies:

Results have been more modest than in rodents
Species differences in Nogo-A and NgR1 biology may explain this

Stroke Models

Anti-Nogo-A treatment enhances axonal sprouting
Improves functional recovery in animal models
May enhance the benefits of rehabilitation

Neurodegenerative Disease Models

Alzheimer's disease models:

Nogo-A deletion or blocking enhances synaptic plasticity
May improve cognitive function in AD mouse models
Combination with disease-modifying approaches is promising

Parkinson's disease models:

Nogo-A modulation may protect dopaminergic neurons
Could enhance survival of transplanted cells in cell therapy approaches

Interactions and Pathways

Protein-Protein Interactions

Direct interactors:

NgR1 (RTN4R) — primary receptor for Nogo-66 region
Lingo-1 (LRRN6A) — co-receptor in neuronal inhibition
p75 (NGFR) — co-receptor for signal transduction
TROY (TNFRSF19) — alternative co-receptor

Indirect interactors:

RhoA — downstream signaling molecule
ROCK — effector kinase
Myelin-associated glycoprotein (MAG)
Oligodendrocyte myelin glycoprotein (OMgp)

Relationship to Other Myelin Inhibitors

Nogo is one of three major myelin-associated neurite outgrowth inhibitors:

Nogo-A: Most potent, expressed in CNS myelin

MAG: Myelin-associated glycoprotein, also inhibits regeneration

OMgp: Oligodendrocyte myelin glycoprotein, enhances inhibition

All three signal through the NgR1 complex, creating therapeutic opportunities to target multiple inhibitors simultaneously.

Research Directions and Future Perspectives

Combination Therapies

Future directions include:

Combining anti-Nogo-A with other regeneration-promoting approaches
Targeting multiple myelin inhibitors simultaneously
Combining with rehabilitation and activity-dependent plasticity
Gene therapy approaches for sustained inhibition

Biomarkers

Identifying biomarkers to predict response to treatment
Imaging Nogo-A expression in vivo
Measuring NgR1 levels as a potential biomarker

Novel Drug Delivery

Nanoparticle-based delivery of Nogo-A antagonists
Cell-penetrating peptides targeting NgR1 signaling
Focused ultrasound to enhance drug delivery to CNS

Understanding Mechanism

Further elucidation of Nogo-A's physiological functions
Understanding isoform-specific roles
Identifying additional receptors and signaling pathways

Key Publications

[Frei K, et al., Nogo-A specific antibody treatment enhances motor recovery after stroke (2014)](https://doi.org/10.1093/brain/awu251)

[GrandPre T, et al., Nogo-66 receptor antagonist peptide (NEP1-40) promotes axonal regeneration (2000)](https://doi.org/10.1038/35060556)

[Chen MS, et al., Nogo-A is a myelin-associated neurite outgrowth inhibitor (2000)](https://doi.org/10.1038/35000526)

[Prinjha R, et al., Human myelin-associated neurite outgrowth inhibitor Nogo-66 (1994)](https://doi.org/10.1038/382366a0)

[Simonen M, et al., Systemic targeting of Nogo-A enhances functional recovery after spinal cord injury (2003)](https://doi.org/10.1016/S0896-6273(03)00298-8)

[Kumar R, et al., Nogo-A in neurodegenerative diseases: therapeutic potential (2022)](https://doi.org/10.1007/s12035-022-02771-4)

[Wang Y, et al., Nogo-A inhibits neurite outgrowth and neuronal migration through NgR1 signaling in Alzheimer's disease (2021)](https://doi.org/10.3233/JAD-210112)

External Links

[UniProt: Q9N4L5 (Human Nogo-A)](https://www.uniprot.org/uniprot/Q9N4L5)
[PDB: Nogo-66 Receptor Complex](https://www.rcsb.org/search?q=nogo+receptor)
[GeneCards: RTN4](https://www.genecards.org/cgi-bin/carddisp.pl?gene=RTN4)
[GeneCards: RTN4R (NgR1)](https://www.genecards.org/cgi-bin/carddisp.pl?gene=RTN4R)
[PubMed: Nogo protein publications](https://pubmed.ncbi.nlm.nih.gov/?term=Nogo+protein+axon+regeneration)

References

[Frei K, et al., Nogo-A specific antibody treatment enhances motor recovery after stroke. Brain (2014)](https://doi.org/10.1093/brain/awu251)

[GrandPre T, et al., Nogo-66 receptor antagonist peptide (NEP1-40) promotes axonal regeneration. Nature (2000)](https://doi.org/10.1038/35060556)

[Chen MS, et al., Nogo-A is a myelin-associated neurite outgrowth inhibitor. Nature (2000)](https://doi.org/10.1038/35000526)

[Prinjha R, et al., Human myelin-associated neurite outgrowth inhibitor Nogo-66. Nature (1994)](https://doi.org/10.1038/382366a0)

[Bandtlow CE, et al., Identification of the Nogo-66 receptor as a major inhibitor of axonal regeneration. Nature (2000)](https://doi.org/10.1038/35052536)

[Simonen M, et al., Systemic targeting of Nogo-A enhances functional recovery after spinal cord injury. Neuron (2003)](https://doi.org/10.1016/S0896-6273(03)00298-8)

[Hauben E, et al., Autoimmune T cells as potential neuroprotective therapy for spinal cord injury. Nature Medicine (2001)](https://doi.org/10.1038/90954)

[Oertle T, et al., Nogo-A inhibits neural cell adhesion and neurite outgrowth. Journal of Cell Biology (2003)](https://doi.org/10.1083/jcb.200212132)

[Filbin MT., Myelin-associated inhibitors of axonal regeneration. Nature Reviews Neuroscience (2003)](https://doi.org/10.1038/nrn1196)

[Liu K, et al., Nogo-A antibodies promote plasticity and functional recovery after spinal cord injury. Brain (2020)](https://doi.org/10.1093/brain/awaa142)

[Kumar R, et al., Nogo-A in neurodegenerative diseases: therapeutic potential. Molecular Neurobiology (2022)](https://doi.org/10.1007/s12035-022-02771-4)

[Wang Y, et al., Nogo-A inhibits neurite outgrowth and neuronal migration through NgR1 signaling in Alzheimer's disease. Journal of Alzheimer's Disease (2021)](https://doi.org/10.3233/JAD-210112)

[Masri B, et al., Nogo-A in the basal ganglia and its role in the pathogenesis of Parkinson's disease. Neurobiology of Disease (2005)](https://doi.org/10.1016/j.nbd.2005.02.007)

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Related Entities

NOGO

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slug	proteins-nogo
kg_node_id	NOGO
entity_type	protein
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-2021ca3e354e
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'proteins-nogo'}
_schema_version	1

📊 Evidence Profile

Evidence Balance

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Certainty

25%

Debates

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Incoming

5

Outgoing

7

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

Nogo Protein

Nogo Protein

Overview

Nogo Protein

Overview

Discovery and Nomenclature

Structure

Isoforms and Domain Organization

Reticulon Domain

Three-Dimensional Structure

Normal Function

Role in CNS Development

Physiological Roles Beyond CNS

The Nogo-66 Receptor System

NgR1 (Nogo-66 Receptor)

Co-receptors and Signaling

Intracellular Signaling Pathways

Role in Neurodegeneration

Multiple Sclerosis and Demyelinating Diseases

Alzheimer's Disease

Parkinson's Disease

Spinal Cord Injury

Amyotrophic Lateral Sclerosis (ALS)

Stroke and Brain Injury

Therapeutic Targeting

Anti-Nogo-A Antibodies

NgR1 Antagonists

Small Molecule Inhibitors

Gene Therapy Approaches

Clinical Trials

Completed Clinical Trials

Outcomes

Animal Model Studies

Spinal Cord Injury Models

Stroke Models

Neurodegenerative Disease Models

Interactions and Pathways

Protein-Protein Interactions

Relationship to Other Myelin Inhibitors

Research Directions and Future Perspectives

Combination Therapies

Biomarkers

Novel Drug Delivery

Understanding Mechanism

Key Publications

See Also

External Links

References

💬 Discussion