LRP4 Protein

LRP4 Protein

Introduction

Lrp4 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">LRP4 Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>Low-density lipoprotein receptor-related protein 4</td></tr>
<tr><td><strong>Gene Symbol</strong></td><td>LRP4</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[4037](https://www.ncbi.nlm.nih.gov/gene/4037)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q9NPJ6](https://www.uniprot.org/uniprot/Q9NPJ6)</td></tr>
<tr><td><strong>MW</strong></td><td>195 kDa</td></tr>
<tr><td><strong>Subcellular Location</strong></td><td>Cell membrane (postsynaptic)</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/autoimmune" style="color:#ef9a9a">Autoimmune</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">59 edges</a></td>
</tr>
</table>
</div>

Overview

LRP4 Protein

Introduction

Lrp4 Protein is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

<div class="infobox infobox-protein">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">LRP4 Protein</th></tr>
<tr><td><strong>Protein Name</strong></td><td>Low-density lipoprotein receptor-related protein 4</td></tr>
<tr><td><strong>Gene Symbol</strong></td><td>LRP4</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[4037](https://www.ncbi.nlm.nih.gov/gene/4037)</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q9NPJ6](https://www.uniprot.org/uniprot/Q9NPJ6)</td></tr>
<tr><td><strong>MW</strong></td><td>195 kDa</td></tr>
<tr><td><strong>Subcellular Location</strong></td><td>Cell membrane (postsynaptic)</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/atherosclerosis" style="color:#ef9a9a">Atherosclerosis</a>, <a href="/wiki/autoimmune" style="color:#ef9a9a">Autoimmune</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">59 edges</a></td>
</tr>
</table>
</div>

Overview

LRP4 (Low-density lipoprotein receptor-related protein 4) is a transmembrane receptor that plays essential roles in neuromuscular junction (NMJ) formation and synapse development["@weatherbee2006"]. Unlike LRP5 and LRP6 which primarily function in Wnt signaling, LRP4 is best characterized for its role as the receptor for agrin and its function in anchoring [acetylcholine](/entities/acetylcholine) receptors (AChRs) at the postsynaptic membrane["@zong2012"]. LRP4 mutations cause congenital myasthenic syndrome (CMS) and have been implicated in amyotrophic lateral sclerosis (ALS) and other neuromuscular disorders.

Molecular Function

Agrin Receptor Function

LRP4 serves as the primary agrin receptor:

• Agrin binding: Binds neuronal agrin at the neuromuscular junction
• AChR clustering: Initiates and maintains acetylcholine receptor clusters
• Synaptic differentiation: Controls postsynaptic specialization
• MuSK interaction: Works with muscle-specific kinase (MuSK)

Neuromuscular Junction Formation

LRP4 is essential for NMJ development[@wu2012]:

• Prenatal development: Critical for initial AChR clustering
• Postsynaptic machinery: Organizes the postsynaptic membrane
• Maintenance: Required for ongoing synaptic stability
• Retrograde signaling: Communicates with presynaptic terminal

Synaptic Protein Interactions

• Muscle-specific kinase (MuSK): Forms receptor complex with LRP4
• Dok7: Stabilizes LRP4-MuSK signaling
• Rapsyn: AChR anchoring protein downstream of LRP4

Disease Associations

Congenital Myasthenic Syndrome (CMS)

LRP4 mutations are a significant cause of CMS:

| Mutation Type | Effect | Phenotype |
|---------------|--------|----------|
| Recessive | Loss of function | Severe CMS, respiratory distress |
| Dominant | Dominant-negative | Variable CMS phenotype |
| Compound heterozygous | Variable | Range of severity |

Mechanism: Impaired agrin-LRP4-MuSK signaling leads to reduced AChR clustering and synaptic transmission[@nicodemus2013].

Amyotrophic Lateral Sclerosis (ALS)

• Genetic association: LRP4 variants in ALS patients
• NMJ dysfunction: Early defects in neuromuscular transmission
• Synaptic pathology: May contribute to motor neuron degeneration
• Biomarker potential: LRP4 as indicator of synaptic integrity

Other Disorders

• Myasthenia gravis: Autoantibodies against LRP4 in some patients
• Sarcoglycanopathies: Interaction with sarcoglycan complex
• Neurodegeneration: Potential role in CNS synapse maintenance

Pathway Interactions

Agrin-LRP4-MuSK Signaling

• Agrin: Neuronal factor that activates LRP4[@zhang2008]
• MuSK: Tyrosine kinase activated by LRP4
• Dok7: Essential intracellular partner
• Rapsyn: Effector for AChR clustering

Wnt Signaling Cross-talk

• Non-canonical Wnt pathways: LRP4 in planar cell polarity
• Synaptic Wnt signaling: Regulation of CNS synapses

Synaptic Plasticity

• Postsynaptic density: Part of the postsynaptic machinery
• Synaptic maintenance: Ongoing role at established synapses
• Homeostatic plasticity: Compensation mechanisms

Therapeutic Implications

NMJ-Targeted Therapies

• LRP4 agonists: Agrin mimetics under development
• MuSK activators: Complement LRP4 signaling
• Gene therapy: AAV-LRP4 delivery approaches

Biomarker Applications

• CSF LRP4: Potential synaptic biomarker
• Antibody testing: LRP4 autoantibodies in myasthenia

Background

The study of Lrp4 Protein has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

See Also

• LRP4 Gene
• [LRP5 Protein](/proteins/lrp5-protein)
• [LRP6 Protein](/proteins/lrp6-protein)
• Amyotrophic Lateral Sclerosis Pathway
• Neuromuscular Junction Pathway
• MuSK Gene

External Links

• [NCBI Gene: LRP4](https://www.ncbi.nlm.nih.gov/gene/4037)
• [UniProt: Q9NPJ6](https://www.uniprot.org/uniprot/Q9NPJ6)

References

Pathway Diagram

The following diagram shows the key molecular relationships involving LRP4 Protein discovered through SciDEX knowledge graph analysis: