GPR37 Gene

GPR37 Gene

<div class="infobox infobox-gene">
<table>
<tr><th>Gene Symbol</th><td><strong>GPR37</strong></td></tr>
<tr><th>Full Name</th><td>G Protein-Coupled Receptor 37 (Parmethin)</td></tr>
<tr><th>Chromosomal Location</th><td>7q31.3</td></tr>
<tr><th>NCBI Gene ID</th><td>7102</td></tr>
<tr><th>OMIM</th><td>603581</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000170370</td></tr>
<tr><th>UniProt ID</th><td>O00163</td></tr>
<tr><th>Protein Class</th><td>Orphan GPCR, Class A</td></tr>
<tr><th>Expression</th><td>Brain (CNS), Peripheral Nervous System</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/bacterial-infection" style="color:#ef9a9a">Bacterial Infection</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/demyelinating-disorders" style="color:#ef9a9a">Demyelinating Disorders</a></td>
</tr>
<tr>
<td class="label">SciDEX Hypotheses</td>
<td><a href="/hypothesis/h-f71a9791" style="color:#ce93d8" title="Score: 0.42">Oligodendrocyte Protectin D1 Mimetic for...</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">187 edges</a></td>
</tr>
</table>
</div>

Pathway Diagram

GPR37 Gene

<div class="infobox infobox-gene">
<table>
<tr><th>Gene Symbol</th><td><strong>GPR37</strong></td></tr>
<tr><th>Full Name</th><td>G Protein-Coupled Receptor 37 (Parmethin)</td></tr>
<tr><th>Chromosomal Location</th><td>7q31.3</td></tr>
<tr><th>NCBI Gene ID</th><td>7102</td></tr>
<tr><th>OMIM</th><td>603581</td></tr>
<tr><th>Ensembl ID</th><td>ENSG00000170370</td></tr>
<tr><th>UniProt ID</th><td>O00163</td></tr>
<tr><th>Protein Class</th><td>Orphan GPCR, Class A</td></tr>
<tr><th>Expression</th><td>Brain (CNS), Peripheral Nervous System</td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">ALS</a>, <a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/bacterial-infection" style="color:#ef9a9a">Bacterial Infection</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/demyelinating-disorders" style="color:#ef9a9a">Demyelinating Disorders</a></td>
</tr>
<tr>
<td class="label">SciDEX Hypotheses</td>
<td><a href="/hypothesis/h-f71a9791" style="color:#ce93d8" title="Score: 0.42">Oligodendrocyte Protectin D1 Mimetic for...</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">187 edges</a></td>
</tr>
</table>
</div>

Pathway Diagram

Knowledge graph relationships for GPR37 (308 total edges in KG)

Overview

GPR37 (G Protein-Coupled Receptor 37), also known as Parmethin, is an orphan G-protein-coupled receptor primarily expressed in the central nervous system. Originally identified as a substrate of the E3 ubiquitin ligase parkin, GPR37 has emerged as a critical player in Parkinson's disease (PD) pathogenesis through multiple mechanisms[@ma2024][@imai2004].

The receptor is notable for its involvement in several key neurodegeneration pathways:

• Parkin-mediated degradation: Direct substrate of parkin, linking it to familial PD with PRKN mutations
• Prosaposin-GPR37-IL-6 axis: A newly discovered pathway where oligodendrocyte GPR37 drives neuroinflammation[@ma2024]
• ER stress and protein quality control: Predominant ER localization with roles in unfolded protein response
• Alpha-synuclein interplay: Modulates α-synuclein toxicity in PD models[@kitsou2024]

Gene Structure and Protein Architecture

Gene Organization

The GPR37 gene is located on chromosome 7q31.3, a region that has been implicated in PD susceptibility through genome-wide association studies. The gene encodes a 462-amino acid GPCR protein with a molecular weight of approximately 52 kDa.

Protein Structure

GPR37 possesses the canonical seven-transmembrane domain architecture typical of Class A GPCRs:

| Domain | Features |
|--------|----------|
| N-terminus | Extracellular, contains potential glycosylation sites |
| TM1-TM7 | Seven transmembrane helices forming the transmembrane core |
| Extracellular loops | ECL1-ECL3 with conserved cysteine residues for disulfide bonds |
| Intracellular loops | ICL1-ICL3 mediating G protein coupling |
| C-terminal tail | Intracellular, contains PDZ-binding motif and phosphorylation sites |

The receptor lacks obvious orthostatic ligand binding sites, classifying it as an orphan receptor. However, recent studies suggest that prosaposin (PSAP) may function as an endogenous ligand[@ma2024].

Expression Pattern

Tissue Distribution

GPR37 exhibits highly restricted expression primarily in neural tissues:

Central Nervous System:

• Substantia nigra (highest expression) — particularly vulnerable in PD
• Hippocampus — CA1/CA3 regions and dentate gyrus
• Cerebral cortex — layers 2-6 pyramidal neurons
• Cerebellum — Purkinje cells
• Striatum — medium spiny neurons
• Brainstem — various nuclei

• Dorsal root ganglia (sensory neurons)
• Enteric nervous system

• Very low expression in testis
• Minimal expression in other peripheral organs

Cellular Expression

GPR37 is expressed in multiple neural cell types:

• Dopaminergic neurons: High expression in substantia nigra pars compacta
• Oligodendrocytes: Critical for the PSAP-GPR37-IL-6 axis[@ma2024]
• Astrocytes: Moderate expression
• Microglia: Lower expression, involved in inflammatory responses

Subcellular Localization

• Endoplasmic reticulum (primary location) — ~70% of total cellular GPR37
• Golgi apparatus — processing and trafficking
• Plasma membrane (minor) — functional signaling competent pool
• Cytosolic aggregates — in disease states, forms ubiquitinated inclusions

Signaling Mechanisms

G Protein Coupling

GPR37 couples to Gi/o family G proteins, leading to:

• Inhibition of adenylate cyclase — reduces cAMP levels
• Activation of inward rectifier potassium channels — hyperpolarizes neurons
• Modulation of MAPK pathways — affects cell survival signaling

Downstream Pathways

Key signaling cascades activated by GPR37:

Non-G Protein Signaling

β-arrestin recruitment has been documented, suggesting:

• Receptor internalization mechanisms
• G protein-independent signaling through β-arrestin scaffolds

Role in Parkinson's Disease

GPR37 is centrally involved in PD pathogenesis through multiple mechanisms:

1. Parkin Substrate ( Familial PD)

GPR37 was first identified as a parkin substrate in 2004[@imai2004]:

• Direct ubiquitination: Parkin directly ubiquitinates GPR37
• Proteasomal targeting: Polyubiquitination (K63-linked) targets GPR37 for degradation
• Pathogenic accumulation: Loss of parkin function (PRKN mutations) leads to GPR37 accumulation
• Toxic aggregate formation: Accumulated GPR37 can form toxic aggregates in neurons

• GPR37 levels are elevated 2-3-fold in the substantia nigra
• GPR37-positive inclusions are detected in surviving neurons
• The accumulation correlates with disease severity

2. PSAP-GPR37-IL-6 Axis (2024 Nature Paper)

A landmark study published in Nature (2024)[@ma2024] revealed a critical pathogenic mechanism:

Mechanism:

Key Findings:

• GPR37 is significantly upregulated in oligodendrocytes in PD patient substantia nigra
• Genetic deletion of GPR37 in oligodendrocytes protects against neurodegeneration
• The axis has been validated in multiple PD models (MPTP, α-synuclein, LRRK2)
• Human PD brain samples show the same pathway activation

• GPR37 in oligodendrocytes is a promising therapeutic target
• Blocking the PSAP-GPR37 interaction may halt neuroinflammation

3. ER Stress and Protein Quality Control

GPR37 is predominantly ER-localized and plays roles in proteostasis[@dunham2019]:

• ER stress sensor: GPR37 detects misfolded protein accumulation
• Unfolded protein response (UPR): Activates PERK and IRE1 pathways
• ER-associated degradation (ERAD): Links to the protein quality control system
• Impaired degradation: Loss of parkin disrupts ERAD, causing GPR37 accumulation

4. Alpha-Synuclein Interaction

Recent evidence shows GPR37 modulates α-synuclein toxicity[@kitsou2024]:

• GPR37 knockout cells show reduced α-synuclein aggregation
• Overexpression of GPR37 exacerbates α-synuclein pathology
• GPR37 may influence the aggregation-nucleation process
• Potential therapeutic target for synucleinopathies

Other Disease Associations

Atypical Parkinsonism

• Progressive Supranuclear Palsy (PSP): GPR37 pathology observed in tau-positive neurons
• Multiple System Atrophy (MSA): Involvement in oligodendrocyte dysfunction
• Cortico-basal Degeneration (CBD): Possible role in neuronal loss

Other Neurological Conditions

• Huntington's Disease: Altered GPR37 expression in striatum
• Amyotrophic Lateral Sclerosis (ALS): Contributes to motor neuron vulnerability
• Ataxia: GPR37 mutations cause cerebellar degeneration in models

Therapeutic Implications

Targeting Strategies

GPR37 is an attractive therapeutic target for PD:

| Strategy | Approach | Status |
|----------|----------|--------|
| Antagonists | Block PSAP-GPR37 interaction | Preclinical |
| Small molecule modulators | Allosteric modulators | Discovery |
| Gene therapy | AAV-delivered GPR37 modulators | Early research |
| Antisense oligonucleotides | Reduce GPR37 expression | Discovery |

Parkin-Enhancing Approaches

Since GPR37 accumulation results from loss of parkin function:

• Parkin activators: Small molecules enhancing parkin E3 activity
• Proteostasis enhancers: Boost ERAD function
• Autophagy modulators: Promote clearance of accumulated GPR37

Anti-inflammatory Strategies

Targeting the PSAP-GPR37-IL-6 axis:

• IL-6 antagonists: Monoclonal antibodies against IL-6
• GPR37-specific antagonists: Block oligodendrocyte GPR37
• PSAP neutralization: Reduce PSAP secretion or block its effects

Animal Models

Knockout Mice (Gpr37-/-)

• Viable and fertile with subtle neurological phenotypes
• Enhanced sensitivity to MPTP-induced dopaminergic degeneration
• Altered ER stress responses
• Motor coordination deficits with age

Transgenic Models

• GPR37 overexpression: Accelerates neurodegeneration in α-synuclein models
• Oligodendrocyte-specific knockout: Protects against PD-like pathology
• Conditional knockouts: Tissue-specific deletion for mechanistic studies

Interaction Network

Protein-Protein Interactions

GPR37 interacts with:

• Parkin (PRKN) — E3 ubiquitin ligase, direct substrate
• UPS proteins — Ubiquitin-proteasome system components
• G proteins — Gi/o family (GNAI1, GNAI2, GNAI3)
• β-arrestins — ARRB1, ARRB2
• PDZ proteins — Potential PDZ domain interactions

Pathway Membership

GPR37 participates in:

• Protein quality control pathways
• ER stress signaling
• Neuroinflammation cascades
• Dopaminergic neuron survival pathways
• Synaptic function modulation

Research Methods

Genetic Approaches

• CRISPR/Cas9 knockout and knockin
• RNA interference
• Transgenic overexpression
• GWAS for variant identification

Molecular Biology

• qPCR and RNA-seq for expression
• Western blot and immunoprecipitation
• Confocal microscopy for localization
• Co-immunoprecipitation for interactions

Functional Studies

• Cell culture models (neurons, oligodendrocytes)
• Mouse models (MPTP, 6-OHDA, α-synuclein)
• Behavioral testing
• Electrophysiology

Key Publications

See Also

• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Parkin (PRKN) Gene](/genes/prkn)
• [Alpha-Synuclein (SNCA) Protein](/proteins/snca-protein)
• [LRRK2 Gene](/genes/lrrk2)
• [Prosaposin (PSAP) Gene](/genes/psap)
• [Mitochondrial Dysfunction Pathway](/mechanisms/mitochondrial-dysfunction-pathway)
• [ER Stress Pathway](/mechanisms/er-stress-pathway)
• [Neuroinflammation Pathway](/mechanisms/neuroinflammation-pathway)
• [Oligodendrocytes](/cell-types/oligodendrocytes-neurobiology)

External Links

• [NCBI Gene: GPR37](https://www.ncbi.nlm.nih.gov/gene/7102)
• [UniProt: GPR37](https://www.uniprot.org/uniprot/O00163)
• [OMIM: GPR37](https://www.omim.org/entry/603581)
• [Ensembl: GPR37](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000170370)
• [IUPHAR: GPR37](https://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=200)

References

Related Hypotheses

From the [SciDEX Exchange](/exchange) — scored by multi-agent debate

• [Oligodendrocyte Protectin D1 Mimetic for Myelin Resolution](/hypothesis/h-f71a9791) — <span style="color:#ffd54f;font-weight:600">0.42</span> · Target: GPR37

Pathway Diagram

The following diagram shows the key molecular relationships involving GPR37 Gene discovered through SciDEX knowledge graph analysis: