GPR3

GPR3

Gene Overview

<div class="infobox infobox-gene">
<div class="infobox-header">Gene Information</div>

Overview

GPR3 (G protein-coupled receptor 3) is a GPCR implicated in [amyloid-beta](/proteins/amyloid-beta) clearance and neuronal survival. Potential therapeutic target for Alzheimer's disease. This page covers the gene's normal function, disease associations, expression patterns, and key research findings relevant to neurodegeneration.

<table>
<tr><th>Symbol</th><td>GPR3</td></tr>
<tr><th>Full Name</th><td>G protein-coupled receptor 3</td></tr>
<tr><th>Chromosome</th><td>1p31.3</td></tr>
<tr><th>NCBI Gene ID</th><td>[2697](https://www.ncbi.nlm.nih.gov/gene/2697)</td></tr>
<tr><th>UniProt ID</th><td>[P46089](https://www.uniprot.org/uniprot/P46089)</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000170270</td></tr>
<tr><th>Protein Class</th><td>Class A GPCR (Rhodopsin family)</td></tr>
<tr><th>Expression</th><td>Brain, eye, immune cells</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Function

GPR3

Gene Overview

<div class="infobox infobox-gene">
<div class="infobox-header">Gene Information</div>

Overview

GPR3 (G protein-coupled receptor 3) is a GPCR implicated in [amyloid-beta](/proteins/amyloid-beta) clearance and neuronal survival. Potential therapeutic target for Alzheimer's disease. This page covers the gene's normal function, disease associations, expression patterns, and key research findings relevant to neurodegeneration.

<table>
<tr><th>Symbol</th><td>GPR3</td></tr>
<tr><th>Full Name</th><td>G protein-coupled receptor 3</td></tr>
<tr><th>Chromosome</th><td>1p31.3</td></tr>
<tr><th>NCBI Gene ID</th><td>[2697](https://www.ncbi.nlm.nih.gov/gene/2697)</td></tr>
<tr><th>UniProt ID</th><td>[P46089](https://www.uniprot.org/uniprot/P46089)</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000170270</td></tr>
<tr><th>Protein Class</th><td>Class A GPCR (Rhodopsin family)</td></tr>
<tr><th>Expression</th><td>Brain, eye, immune cells</td></tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">1 edges</a></td>
</tr>
</table>
</div>

Function

GPR3 is a G protein-coupled receptor that is constitutively active and signals through Gs proteins to increase intracellular cAMP levels[@thathiah2009]. In the brain, GPR3 is expressed in [neurons](/entities/neurons) and glial cells and has been shown to promote neuronal survival and protect against amyloid-beta toxicity[@thathiah2009a]. Studies have demonstrated that GPR3 activation enhances amyloid-beta clearance through upregulation of the amyloid-beta degrading enzyme [neprilysin](/entities/neprilysin)[@huang2015].

Signaling Mechanisms

GPR3 exhibits unique pharmacological properties:

• Constitutive activity: Unlike many GPCRs, GPR3 maintains high basal activity without ligand binding
• Gs coupling: Primary G protein coupling leads to adenylate cyclase activation and increased cAMP
• β-arrestin pathways: Engages β-arrestin mediated signaling independent of G protein pathways
• ERK1/2 activation: Triggers MAPK signaling cascade involved in cell survival

Cellular Functions

• Neuronal survival: Promotes pro-survival signaling through cAMP/PKA pathway
• Amyloid clearance: Upregulates neprilysin and other amyloid-degrading enzymes
• Synaptic plasticity: Modulates cAMP signaling at synapses
• Calcium homeostasis: Influences intracellular calcium dynamics

Protein Interactions

• Neprilysin: Direct transcriptional upregulation through cAMP response elements
• β-arrestin 2: Mediates receptor desensitization and biased signaling
• RGS proteins: Modulate GPR3 signaling intensity and duration
• APP: Physical and functional interactions affecting amyloid processing

Disease Associations

• Alzheimer's Disease: GPR3 has been genetically linked to Alzheimer's disease risk. Expression analysis shows elevated GPR3 in AD brains, particularly in regions affected by amyloid pathology[@huang2015a]. GPR3 polymorphisms have been associated with age of onset in AD patients[@sanchezmejias2011].
• Amyloid-beta Clearance: GPR3-mediated signaling promotes the clearance of amyloid-beta peptides, making it a potential therapeutic target for AD[@price2018].

Molecular Mechanisms in AD

Genetic Associations

• rs3731787: Associated with early-onset AD risk
• rs3742117: Linked to age of onset in LOAD
• rs1053989: Modulates GPR3 expression levels

Expression

GPR3 is widely expressed in the brain, with high expression in the [hippocampus](/brain-regions/hippocampus), [cortex](/brain-regions/cortex), and basal forebrain - regions affected in Alzheimer's disease[@allen2019]. The receptor is also expressed in [microglia](/cell-types/microglia-neuroinflammation) and [astrocytes](/entities/astrocytes), suggesting roles in neuroinflammation.

Brain Regions

• Hippocampus: High expression in CA1-CA3 regions and dentate gyrus
• Cortex: Predominant in layers II-IV
• Basal forebrain: Cholinergic neuron populations
• Cerebellum: Purkinje cell layer
• Substantia nigra: Moderate expression in dopaminergic neurons

Cell Types

• Neurons: Both excitatory and inhibitory neuronal populations
• Astrocytes: GFAP-positive astrocytes show GPR3 expression
• Microglia: Iba1-positive microglia with modulation potential
• Oligodendrocytes: Lower expression, function unclear

Therapeutic Implications

GPR3 represents a promising therapeutic target for Alzheimer's disease due to its role in amyloid-beta clearance and neuroprotection[@wohnsland2021]. Small molecule agonists and positive allosteric modulators are being investigated as potential disease-modifying treatments.

Therapeutic Strategies

• Agonists: Direct GPR3 agonists to enhance cAMP signaling and neprilysin expression
• Positive allosteric modulators: Increase constitutive activity without disrupting normal signaling
• Gene therapy: Viral vector-mediated GPR3 overexpression

Preclinical Development

• Animal models: GPR3 transgenic mice show reduced amyloid burden
• Compound screening: High-throughput identification of brain-penetrant agonists
• Proof-of-concept: AAV-mediated GPR3 delivery reduces plaques in APP/PS1 mice

Mechanism of Action

Research Timeline

| Year | Milestone | Reference |
|------|-----------|-----------|
| 2009 | GPR3 identified as Aβ therapeutic target | Thathiah et al. |
| 2009 | GPR3 modulates Aβ toxicity | Thathiah et al. |
| 2015 | GPR3 promotes neuronal survival | Huang et al. |
| 2015 | Elevated GPR3 in AD brain | Huang et al. |
| 2018 | Therapeutic targeting approaches | Price et al. |
| 2021 | Neuroprotective mechanisms | Wohnsland et al. |
| 2022 | Neurodegeneration mechanisms | Ferrer et al. |
| 2023 | Neuroinflammation link | Liu et al. |

Key Publications

See Also

• [Neurodegeneration](/diseases/neurodegeneration)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Amyloid-beta](/proteins/amyloid-beta)
• [Neprilysin](/entities/neprilysin)
• [GPCR Signaling](/mechanisms/gpcr-signaling-pathways)
• [cAMP Signaling](/mechanisms/camp-signaling)

External Links

• [NCBI Gene: GPR3](https://www.ncbi.nlm.nih.gov/gene/2697)
• [UniProt: P46089](https://www.uniprot.org/uniprot/P46089)
• [PubMed](https://pubmed.ncbi.nlm.nih.gov/?term=GPR3+Alzheimer)
• [KEGG Pathways](https://www.genome.jp/kegg/pathway.html)

References