ADORA2A (A2aR): The "Secret Messenger" in Immune and Nervous Systems

ADORA2A (A2aR)

As a key member of the G protein-coupled receptor (GPCR) superfamily, ADORA2A (adenosine A2a receptor) has become a focal point in neuroscience, tumor immunology, and metabolic diseases due to its unique seven-transmembrane structure and extensive biological functions.

I. Molecular Structure and Expression Characteristics

The protein encoded by the ADORA2A gene consists of 412 amino acids, with a typical seven-transmembrane helix (7TM) structure as its core. By binding to Gs/Golf subfamilies of G proteins, it activates the adenylate cyclase (AC) signaling pathway, significantly elevating intracellular cAMP levels. This protein is highly expressed in brain tissues (such as the striatum and hippocampus), immune cells (T cells, NK cells), and the cardiovascular system. Selective splicing generates multiple transcript variants, forming functional isoforms.

II. Physiological Functional Network

Neurological Regulation Hub

ADORA2A regulates dopaminergic neurotransmission in the basal ganglia, participating in motor coordination and reward mechanisms. Studies have shown that its overexpression is associated with neuropsychiatric disorders such as depression and Parkinson's disease. For instance, a research team from the University of Hong Kong discovered that the RagA protein induces depression-like behavior in mice by activating the p70S6K/ADORA2A signaling pathway, while the ADORA2A inhibitor istradefylline can significantly alleviate symptoms, providing a novel target for antidepressant drug development.

Immunoregulatory Pivot

In the tumor microenvironment (TME), tumor cells degrade ATP to adenosine via the CD39/CD73 pathway. Adenosine binding to ADORA2A inhibits T cell activation. Ampio Pharmaceuticals' monoclonal antibody AT-004 can specifically block A2aR, reversing adenosine-mediated immunosuppression, restoring CD8+ T cell surface marker expression, and enhancing IFN-γ secretion levels, demonstrating 100-fold greater potency than small molecule inhibitors.

Metabolic Regulation Node

At the energy metabolism level, ADORA2A influences adipose tissue browning by regulating mitochondrial function. A team from Shanghai Jiao Tong University found that it triggers proline synthesis through the ERK/MYC/PYCR cascade, reshaping the epigenetic landscape of neuroendocrine prostate cancer and lung cancer, offering new strategies for tumor metabolic intervention.

III. ADORA2A and Diseases

ADORA2A mutations are associated with risks of over 40 diseases, including:

Neuropsychiatric disorders: sleep disorders, panic disorder, schizophrenia

Cardiovascular diseases: ventricular dysfunction, hypotension

Immune-related diseases: rheumatoid arthritis, drug allergies

Cancers: neuroendocrine prostate cancer, lung cancer

Its mutants lead to pathological phenotypes by affecting receptor binding affinity to adenosine or downstream signal transduction efficiency. For example, specific mutations can enhance receptor sensitivity to adenosine, exacerbating immunosuppression in the tumor microenvironment.

IV. Clinical Translation and Drug Development

Tumor Immunotherapy

Ampio Pharmaceuticals' monoclonal antibody AT-004, by specifically blocking A2aR, reverses adenosine-mediated T cell suppression. In preclinical studies, it exhibits 100-fold greater potency than small molecule inhibitors. Combined with PD-1/CTLA-4 inhibitors, it significantly enhances anti-tumor immune responses in solid tumors.

Neuropsychiatric Disorder Interventions

Targeting the RagA-p70S6K-ADORA2A signaling pathway, researchers found that the ADORA2A inhibitor istradefylline improves depression-like behavior in mice, providing a new therapeutic target for depression. Additionally, the natural product puerarin shows improvement in LPS-induced depression-like behavior by downregulating RagA expression.

Recombinant Protein Tool Development

In basic research, full-length ADORA2A recombinant proteins (such as the P02 protein expressed via CFS cell-free wheat germ system) have become standard tools for drug screening, antibody development, and signaling pathway studies. Their high solubility, post-translational modifications, and functional activity provide important platforms for GPCR structural biology research.

V. Future Prospects

With the integration of single-cell sequencing, cryo-electron microscopy, and artificial intelligence technologies, the structure-function relationship of ADORA2A will be more precisely elucidated. In clinical applications, bispecific antibodies, PROTAC degraders, and gene editing therapies based on this receptor are under development. For example, CRISPR-Cas9 knockout of ADORA2A in tumor cells can reverse adenosine-mediated immune escape, offering new ideas for combination therapies.

Research on ADORA2A protein not only deepens our understanding of GPCR signal transduction but also drives interdisciplinary therapeutic innovations. In the future, with technological breakthroughs and accumulation of clinical data, this molecule is expected to become an important target in the era of precision medicine.

Related Product Recommendations:

Data Sharing:

ADORA2A (with nine mutations) Flag-His-EGFP-strep tag Protein, Human (Detergent)

Catalog No.: UA060006

Immobilized ADORA2A (with nine mutations) Flag-His-EGFP-strep tag Protein, Human (Detergent) (Cat. No. UA060006) at 5 μg/mL (100 μL/well) on a Nickel Coated plate can bind Mouse Anti-ADORA2A with EC50 of 1.89-4.07 ng/mL.

Anti-His antibody Immobilized on CM5 Chip captured ADORA2A (with nine mutations) Flag-His-EGFP-strep tag Protein, Human (Detergent) (Cat. No. UA060006), can bind Mouse Anti-ADORA2A with an affinity constant of 2.62 nM as determined in SPR assay.

References:

1. Yuta Myojin; Justin McCallen; Chi Ma; Kylynda C. Bauer; Benjamin Ruf; et al. Adenosine A2a receptor inhibition increases the antitumor efficacy of anti-PD1 treatment in murinehepatobiliary cancers.JHEP Reports.2023.
2. Changfa Sun; Bochu Wang; Shilei Hao. Adenosine-A2A Receptor Pathwayin Cancer Immunotherapy.  Frontiers in Immunology.2022.
3. Jia Zhao; Yilu Sun; Yibin Feng; Jianhui Rong. Brain Specific RagA Overexpression Triggers Depressive-Like Behaviors in Mice via Activating ADORA2A Signaling Pathway. Advanced Science.2024.
4. Aditya Shreenivas; Daisuke Nishizaki; Suzanna Lee; Sarabjot Pabla; Mary Nesline; et al. Clinical and Biologic Correlates of ADORA2A TranscriptomicExpression in Cancer. International Journal of Molecular Sciences.2024.
5. Xiaomei Fan; Yuna Chen; Wenzhou Li; Hanbin Xia; Bin Liu; et al. Genetic Polymorphism of ADORA2A Is Associated With the Risk of Epilepsy and Predisposition to Neurologic Comorbidity in Chinese Southern Children.Frontiers in Neuroscience.2020.