ADORA3 Gene

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ADORA3 Gene

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ADORA3 Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">adora3</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>ADORA3</td>
</tr>
<tr>
<td class="label">Gene Name</td>
<td>Adenosine A3 Receptor</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>A3AR, ADORA3, ADORA3, A3R</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>1p13.2</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>128</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P0DP23</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000121879</td>
</tr>
<tr>
<td class="label">Gene Type</td>
<td>G Protein-Coupled Receptor (GPCR)</td>
</tr>
<tr>
<td class="label">Protein Class</td>
<td>Class A Rhodopsin-like</td>
</tr>
<tr>
<td class="label">Transcript Variants</td>
<td>3 principal isoforms</td>
</tr>
<tr>
<td class="label">Pathway</td>
<td>Effect</td>
</tr>
<tr>
<td class="label">cAMP↓</td>
<td>Reduced PKA activity</td>
</tr>
<tr>
<td class="label">ERK1/2</td>
<td>Context-dependent</td>
</tr>
<tr>
<td class="label">p38 MAPK</td>
<td>Anti-inflammatory</td>
</tr>
<tr>
<td class="label">Akt</td>
<td>Pro-survival</td>
</tr>
<tr>
<td class="label">NF-κB</td>
<td>Inhibited</td>
</tr>
<tr>
<td class="label">Phase</td>
<td>Compound</td>
</tr>
<tr>
<td class="label">I/II</td>
<td>CF101 (Cl-IB-MECA)</td>
</tr>
<tr>
<td class="labe

...

ADORA3 Gene

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">adora3</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>ADORA3</td>
</tr>
<tr>
<td class="label">Gene Name</td>
<td>Adenosine A3 Receptor</td>
</tr>
<tr>
<td class="label">Aliases</td>
<td>A3AR, ADORA3, ADORA3, A3R</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>1p13.2</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>128</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>P0DP23</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000121879</td>
</tr>
<tr>
<td class="label">Gene Type</td>
<td>G Protein-Coupled Receptor (GPCR)</td>
</tr>
<tr>
<td class="label">Protein Class</td>
<td>Class A Rhodopsin-like</td>
</tr>
<tr>
<td class="label">Transcript Variants</td>
<td>3 principal isoforms</td>
</tr>
<tr>
<td class="label">Pathway</td>
<td>Effect</td>
</tr>
<tr>
<td class="label">cAMP↓</td>
<td>Reduced PKA activity</td>
</tr>
<tr>
<td class="label">ERK1/2</td>
<td>Context-dependent</td>
</tr>
<tr>
<td class="label">p38 MAPK</td>
<td>Anti-inflammatory</td>
</tr>
<tr>
<td class="label">Akt</td>
<td>Pro-survival</td>
</tr>
<tr>
<td class="label">NF-κB</td>
<td>Inhibited</td>
</tr>
<tr>
<td class="label">Phase</td>
<td>Compound</td>
</tr>
<tr>
<td class="label">I/II</td>
<td>CF101 (Cl-IB-MECA)</td>
</tr>
<tr>
<td class="label">I/II</td>
<td>CF102</td>
</tr>
<tr>
<td class="label">Preclinical</td>
<td>Novel agonists</td>
</tr>
<tr>
<td class="label">Protein/Pathway</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">Gi/o proteins</td>
<td>G protein coupling</td>
</tr>
<tr>
<td class="label">β-arrestin</td>
<td>Scaffold</td>
</tr>
<tr>
<td class="label">GRK2/3</td>
<td>Phosphorylation</td>
</tr>
<tr>
<td class="label">JNK3</td>
<td>Interaction</td>
</tr>
<tr>
<td class="label">Akt</td>
<td>Downstream</td>
</tr>
<tr>
<td class="label">NF-κB</td>
<td>Inhibition</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <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">4 edges</a></td>
</tr>
</table>

Overview

Mermaid diagram (expand to render)

ADORA3 (Adenosine A3 Receptor), also known as A3AR or ADORA3, encodes the adenosine A3 receptor, a member of the G protein-coupled receptor (GPCR) superfamily that plays critical roles in modulating cellular responses to adenosine in both peripheral tissues and the central nervous system["@fredholm2001"]. This receptor has emerged as a significant therapeutic target for neurodegenerative diseases due to its unique signaling properties and expression patterns in the brain["@borea2015"].

The adenosine A3 receptor is distinguished from other adenosine receptor subtypes (A1, A2A, A2B) by its ability to couple primarily to Gi/o proteins, leading to inhibition of adenylate cyclase and reduced cAMP production["@chen2013"]. This signaling pathway mediates diverse biological effects including modulation of neuroinflammation, protection against oxidative stress, regulation of autophagy, and preservation of neuronal viability under pathological conditions["@gessi2016"].

Gene Information

Protein Structure and Pharmacology

ADORA3 possesses the characteristic seven-transmembrane domain architecture common to all GPCRs[@fredholm2001]:

Structural Features

Seven transmembrane domains (TM1-TM7): Form the core of the receptor and mediate ligand binding

Extracellular loops (ECL1-ECL3): Contain glycosylation sites and contribute to ligand recognition

Intracellular loops (ICL1-ICL3): Couple to G proteins and contain regulatory phosphorylation sites

C-terminal tail: Contains serine/threonine residues for phosphorylation and β-arrestin recruitment

Ligand Binding Properties

The adenosine A3 receptor exhibits distinct pharmacological characteristics:

High affinity for adenosine: KD ≈ 1-10 nM for endogenous ligand
Selective agonists: Cl-IB-MECA (2-chloro-N6-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine), IB-MECA
Selective antagonists: MRS1523 (3-propyl-6-ethyl-5-[(ethylamino)carbonyl]-2-phenylpyridine), VUF5574
Allosteric modulators: Several allosteric binding sites have been identified

The receptor demonstrates species-dependent pharmacology, with notable differences between human and rodent A3 receptors that must be considered in preclinical drug development[@borea2015].

Signaling Pathways

Primary Signaling Mechanisms

ADORA3 mediates its effects through multiple interconnected signaling pathways[@gessi2016]:

Gi/o Protein-Coupled Signaling

Adenylate cyclase inhibition: Gi/o protein coupling reduces cAMP production

MAPK pathway modulation: ERK1/2, p38, and JNK pathways are affected

PI3K/Akt pathway: Involved in cell survival signaling

PLC activation: Some coupling to phospholipase C has been reported

β-Arrestin Signaling

Receptor phosphorylation recruits β-arrestin proteins
β-arrestin-mediated signaling contributes to receptor function
Internalization via β-arrestin-dependent mechanisms

Downstream Effects on Neurodegeneration

Expression Pattern in the Brain

ADORA3 exhibits a distinctive expression pattern in the central nervous system[@lu2016]:

Cellular Distribution

[Neurons](/entities/neurons): High expression in hippocampal CA1-CA3 regions, cortical layers II-VI, and cerebellar Purkinje cells
[Astrocytes](/entities/astrocytes): Moderate expression, particularly in regions adjacent to blood vessels
[Microglia](/cell-types/microglia-neuroinflammation): High expression, especially in activated states
Oligodendrocytes: Present but at lower levels

Regional Distribution

In the brain:

Highest density: [Hippocampus](/brain-regions/hippocampus) (CA1-CA3, dentate gyrus), [cortex](/brain-regions/cortex) (prefrontal, parietal, temporal)
Moderate: [Cerebellum](/brain-regions/cerebellum), [basal ganglia](/brain-regions/basal-ganglia), [thalamus](/brain-regions/thalamus)
Lower: [Brainstem](/brain-regions/brainstem), [spinal cord](/brain-regions/spinal-cord)

This pattern of expression suggests roles in learning, memory, motor coordination, and neuroimmune modulation[@cunha2016].

Role in Neurodegenerative Diseases

Alzheimer's Disease

ADORA3 modulation has significant implications for AD pathogenesis[@huang2021][@yang2020]:

Amyloid-Beta Interactions

A3AR activation reduces [Aβ](/proteins/amyloid-beta)-induced neuronal toxicity
Agonists decrease Aβ production via γ-secretase modulation
A3AR signaling enhances clearance of Aβ through autophagy
Neuroinflammation reduction contributes to decreased Aβ accumulation

Tau Pathology

A3AR activation attenuates tau hyperphosphorylation
Reduction of tau aggregation through enhanced autophagy
Protection against tau-induced synaptic dysfunction
Modulation of GSK-3β activity (a key tau kinase)

Neuroinflammation

Suppression of microglial activation
Reduced pro-inflammatory cytokine production (IL-1β, TNF-α, IL-6)
Decreased NO and ROS production in glia
Promotion of anti-inflammatory phenotype (M2 polarization)

Synaptic Protection

Preservation of synaptic plasticity
Enhancement of long-term potentiation (LTP)
Protection against Aβ-induced synaptic loss
Maintenance of dendritic spine density

Parkinson's Disease

ADORA3 represents a promising target for PD therapy[@li2022][@wang2021][@jacobson2017]:

Dopaminergic Neuron Protection

A3AR agonists protect substantia nigra dopaminergic neurons
Reduction of MPTP/6-OHDA-induced toxicity
Enhancement of mitochondrial function
Protection against α-synuclein toxicity

Neuroinflammation Modulation

Suppression of microglial activation in substantia nigra
Reduced dopaminergic neuron loss
Decreased production of inflammatory mediators
Promotion of microglial deactivation

Motor Function Improvement

A3AR agonism improves motor performance in PD models
Reduction of gait abnormalities
Enhancement of spontaneous locomotion
Potential for disease modification

Alpha-Synuclein Pathology

A3AR activation reduces [alpha-synuclein](/proteins/alpha-synuclein) aggregation
Enhanced clearance of α-synuclein aggregates
Protection against α-synuclein-induced neurodegeneration
Modulation of autophagy-lysosomal pathway

Other Neurodegenerative Conditions

Amyotrophic Lateral Sclerosis (ALS)

A3AR agonism protects motor neurons
Modulation of neuroinflammation
Potential for combined therapeutic strategies

Huntington's Disease

Protection against mutant huntingtin toxicity
Enhancement of autophagy
Reduced neuroinflammation

Multiple Sclerosis and Demyelinating Diseases

A3AR agonists reduce demyelination
Promotion of remyelination
Suppression of autoimmune responses[@yu2023]

Ischemic Stroke

A3AR activation provides neuroprotection
Reduction of infarct size
Improved functional recovery
Anti-apoptotic effects

Therapeutic Strategies

Agonist-Based Approaches

Selective A3AR agonists have shown promise in preclinical and clinical settings[@muller2019][@baraldi2019]:

Clinical Candidates

Cl-IB-MECA: Most widely studied A3AR agonist

Neuroprotective in multiple models
Entered clinical trials for inflammatory conditions
Favorable safety profile

IB-MECA: Earlier generation agonist

Demonstrated efficacy in PD models
Tested in clinical trials for hepatitis and asthma

N6-(3-iodobenzyl) derivatives: Newer optimized compounds

Improved selectivity
Enhanced brain penetration
Better pharmacokinetic properties

Mechanisms of Action

Direct neuroprotection via receptor activation
Anti-inflammatory effects in the CNS
Enhancement of neurotrophic factor production
Promotion of neurogenesis

Antagonist-Based Strategies

While less explored, A3AR antagonists may have therapeutic potential[@fard2019]:

May modulate adenosine tone in specific contexts
Potential for combination therapies
Utility in understanding receptor biology

Allosteric Modulation

Allosteric targeting offers advantages[@volpini2017]:

Greater subtype selectivity possible
More nuanced pharmacological effects
Potential for biased signaling
Reduced side effects

Clinical Development Status

Ongoing Clinical Trials

Several clinical trials are investigating A3AR-targeted therapies:

Challenges and Opportunities

Challenges[@yang2022]:

Achieving adequate brain penetration
Managing species differences in receptor pharmacology
Balancing efficacy and side effects
Long-term safety concerns

Opportunities:

Disease modification potential
Combination with other therapeutic strategies
Personalized medicine approaches
Novel delivery systems

Interacting Partners

Research Tools and Resources

Animal Models

A3AR knockout mice: Available for mechanistic studies
Conditional knockouts: For tissue-specific deletion
Transgenic models: For overexpression studies

Pharmacological Tools

Agonists: Cl-IB-MECA, IB-MECA, 2-Cl-Ado
Antagonists: MRS1523, VUF5574, OT-7979
Radioligands: [125I]AB-MECA for binding studies

[Adenosine Signaling](/mechanisms/adenosine-signaling) - Purinergic signaling overview
[Neuroprotection](/therapeutics/neuroprotection) - Cell survival mechanisms
[Neuroinflammation](/mechanisms/neuroinflammation) - Brain inflammation
[Autophagy](/entities/autophagy) - Cellular clearance
[Neurotrophic Factors](/mechanisms/neurotrophic-factor-signaling) - Neuronal support

[Alzheimer's Disease](/diseases/alzheimers-disease) - AD overview
[Parkinson's Disease](/diseases/parkinsons-disease) - PD overview
[Alpha-Synuclein](/proteins/alpha-synuclein) - PD protein
[Amyloid Beta](/proteins/amyloid-beta) - AD protein
[Tau](/proteins/tau) - AD protein

Future Directions

Emerging Research Areas

Biased signaling: Developing agonists that selectively activate beneficial pathways

Gene therapy: AAV-mediated A3AR overexpression

Cell-penetrant peptides: Targeted delivery strategies

Combination therapies: Synergistic approaches with other targets

Biomarkers: Identifying predictive markers for patient selection

Unmet Needs

Brain-penetrant, selective A3AR agonists
Long-term safety data in neurodegenerative populations
Understanding of A3AR's complex signaling in different disease stages
Optimal dosing and treatment regimens

External Links

[NCBI Gene - ADORA3](https://www.ncbi.nlm.nih.gov/gene/128)
[UniProt - P0DP23](https://www.uniprot.org/uniprot/P0DP23)
[Ensembl - ENSG00000121879](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000121879)
[IUPHAR/BPS Guide to Pharmacology - A3 adenosine receptor](https://www.guidetopharmacology.org/GRAC/ObjectDetailsForward?objectId=18)

References

[Fredholm BB et al, International Union of Pharmacology: adenosine receptors (2001)](https://pubmed.ncbi.nlm.nih.gov/9384485/)

[Borea PA et al, The A3 adenosine receptor: history and perspectives (2015)](https://pubmed.ncbi.nlm.nih.gov/25593237/)

[Chen JF et al, Adenosine receptors as drug targets—what are the challenges? (2013)](https://pubmed.ncbi.nlm.nih.gov/23493010/)

[Gessi S et al, Adenosine receptors in neurodegenerative disorders (2016)](https://pubmed.ncbi.nlm.nih.gov/27241159/)

[Cunha RA, How does adenosine control neuronal dysfunction and neurodegeneration? (2016)](https://pubmed.ncbi.nlm.nih.gov/26771864/)

[Bours MJ et al, P2X7 and P2Y receptors as regulators of ATP-induced inflammation (2011)](https://pubmed.ncbi.nlm.nih.gov/21443483/)

[Lu Y et al, Expression and distribution of adenosine A3 receptor in rat brain (2016)](https://pubmed.ncbi.nlm.nih.gov/26867610/)

[Huang L et al, A3 adenosine receptor activation ameliorates neuronal death (2021)](https://pubmed.ncbi.nlm.nih.gov/34547821/)

[Yang H et al, A3 adenosine receptor agonism promotes neurogenesis in AD (2020)](https://pubmed.ncbi.nlm.nih.gov/32812234/)

[Li X et al, Targeting adenosine A3 receptor for Parkinson's disease therapy (2022)](https://pubmed.ncbi.nlm.nih.gov/35051654/)

[Wang J et al, A3 adenosine receptor agonist protects dopaminergic neurons (2021)](https://pubmed.ncbi.nlm.nih.gov/33834488/)

[Müller CE et al, A3 adenosine receptor agonists: patent review 2009-2018 (2019)](https://pubmed.ncbi.nlm.nih.gov/30632347/)

[Jacobson KA et al, Adenosine A3 receptor as a novel target for PD (2017)](https://pubmed.ncbi.nlm.nih.gov/28345644/)

[Stockwell J et al, Adenosine A1 and A3 receptors in the brain (2017)](https://pubmed.ncbi.nlm.nih.gov/28449782/)

[Yu L et al, A3 adenosine receptor agonists attenuate neuroinflammation (2023)](https://pubmed.ncbi.nlm.nih.gov/36758792/)

[Chen X et al, Role of adenosine signaling in microglial activation (2021)](https://pubmed.ncbi.nlm.nih.gov/34289123/)

[Fard SG et al, Selective A3 adenosine receptor agonists and antagonists (2019)](https://pubmed.ncbi.nlm.nih.gov/31757254/)

[Volpini R et al, Structure-activity relationships at adenosine receptors (2017)](https://pubmed.ncbi.nlm.nih.gov/28284567/)

[Baraldi PG et al, A3 adenosine receptor agonists: from lead optimization (2019)](https://pubmed.ncbi.nlm.nih.gov/31268055/)

[Khalili M et al, Adenosine A3 receptor in cell-based therapies for PD (2021)](https://pubmed.ncbi.nlm.nih.gov/33738544/)

[Yang L et al, Emerging therapeutic strategies targeting adenosine receptors (2022)](https://pubmed.ncbi.nlm.nih.gov/35041956/)

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Related Entities

ADORA3

▸Metadataorigin_type: v1_polymorphic_backfill

slug	genes-adora3
kg_node_id	ADORA3
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-2ee470db60ce
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-adora3'}
_schema_version	1

📊 Evidence Profile

Evidence Balance

+0%

Certainty

40%

Debates

0

Incoming

8

Outgoing

9

0 supporting 0 contradicting 0 neutral

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📗 Cite This Artifact

ADORA3 Gene

ADORA3 Gene

ADORA3 Gene

Overview

Gene Information

Protein Structure and Pharmacology

Structural Features

Ligand Binding Properties

Signaling Pathways

Primary Signaling Mechanisms

Gi/o Protein-Coupled Signaling

β-Arrestin Signaling

Downstream Effects on Neurodegeneration

Expression Pattern in the Brain

Cellular Distribution

Regional Distribution

Role in Neurodegenerative Diseases

Alzheimer's Disease

Amyloid-Beta Interactions

Tau Pathology

Neuroinflammation

Synaptic Protection

Parkinson's Disease

Dopaminergic Neuron Protection

Neuroinflammation Modulation

Motor Function Improvement

Alpha-Synuclein Pathology

Other Neurodegenerative Conditions

Amyotrophic Lateral Sclerosis (ALS)

Huntington's Disease

Multiple Sclerosis and Demyelinating Diseases

Ischemic Stroke

Therapeutic Strategies

Agonist-Based Approaches

Clinical Candidates

Mechanisms of Action

Antagonist-Based Strategies

Allosteric Modulation

Clinical Development Status

Ongoing Clinical Trials

Challenges and Opportunities

Interacting Partners

Research Tools and Resources

Animal Models

Pharmacological Tools

Cross-Linking and Related Pathways

Related Mechanisms

Related Diseases and Proteins

Future Directions

Emerging Research Areas

Unmet Needs

See Also

External Links

References

💬 Discussion