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Gao ZG, Haddad M, Jacobson KA. A 2B adenosine receptor signaling and regulation. Purinergic Signal 2024:10.1007/s11302-024-10025-y. [PMID: 38833181 DOI: 10.1007/s11302-024-10025-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 05/20/2024] [Indexed: 06/06/2024] Open
Abstract
The A2B adenosine receptor (A2BR) is one of the four adenosine-activated G protein-coupled receptors. In addition to adenosine, protein kinase C (PKC) was recently found to activate the A2BR. The A2BR is coupled to both Gs and Gi, as well as Gq proteins in some cell types. Many primary cells and cell lines, such as bladder and breast cancer, bronchial smooth muscle, skeletal muscle, and fat cells, express the A2BR endogenously at high levels, suggesting its potentially important role in asthma, cancer, diabetes, and other conditions. The A2BR has been characterized as both pro- and anti-inflammatory, inducing cell type-dependent secretion of IL-6, IL-8, and IL-10. Theophylline and enprofylline have long been used for asthma treatment, although it is still not entirely clear if their A2BR antagonism contributes to their therapeutic effects or side effects. The A2BR is required in ischemic cardiac preconditioning by adenosine. Both A2BR and protein kinase C (PKC) contribute to cardioprotection, and both modes of A2BR signaling can be blocked by A2BR antagonists. Inhibitors of PKC and A2BR are in clinical cancer trials. Sulforaphane and other isothiocyanates from cruciferous vegetables such as broccoli and cauliflower have been reported to inhibit A2BR signaling via reaction with an intracellular A2BR cysteine residue (C210). A full, A2BR-selective agonist, critical to elucidate many controversial roles of the A2BR, is still not available, although agonist-bound A2BR structures have recently been reported.
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Affiliation(s)
- Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA.
| | - Mansour Haddad
- Faculty of Pharmacy, Yarmouk University, Irbid, 21163, Jordan
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA.
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Gao ZG, Levitan IM, Inoue A, Wei Q, Jacobson KA. A 2B adenosine receptor activation and modulation by protein kinase C. iScience 2023; 26:107178. [PMID: 37404375 PMCID: PMC10316653 DOI: 10.1016/j.isci.2023.107178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 05/25/2023] [Accepted: 06/15/2023] [Indexed: 07/06/2023] Open
Abstract
Protein kinase C (PKC) isoforms regulate many important signaling pathways. Here, we report that PKC activation by phorbol 12-myristate 13-acetate (PMA) enhanced A2B adenosine receptor (AR)-mediated, but not β2-adrenergic receptor-mediated, cAMP accumulation, in H9C2 cardiomyocyte-like and HEK293 cells. In addition to enhancement, PKC (PMA-treatment) also activated A2BAR with low Emax (H9C2 and NIH3T3 cells endogenously expressing A2BAR), or with high Emax (A2BAR-overexpressing HEK293 cells) to induce cAMP accumulation. A2BAR activation induced by PKC was inhibited by A2BAR and PKC inhibitors but enhanced by A2BAR overexpression. Gαi isoforms and PKCγ isoform were found to be involved in both enhancement of A2BAR function and A2BAR activation. Thus, we establish PKC as an endogenous modulator and activator of A2BAR, involving Giα and PKCγ. Depending on signaling pathway, PKC could activate and enhance, or alternatively inhibit A2BAR activity. These findings are relevant to common functions of A2BAR and PKC, e.g. cardioprotection and cancer progression/treatment.
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Affiliation(s)
- Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Ian M. Levitan
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Asuka Inoue
- Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan
| | - Qiang Wei
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
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Da W, Tao L, Zhu Y. The Role of Osteoclast Energy Metabolism in the Occurrence and Development of Osteoporosis. Front Endocrinol (Lausanne) 2021; 12:675385. [PMID: 34054735 PMCID: PMC8150001 DOI: 10.3389/fendo.2021.675385] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Accepted: 04/29/2021] [Indexed: 12/14/2022] Open
Abstract
In recent decades, the mechanism underlying bone metabolic disorders based on energy metabolism has been heavily researched. Bone resorption by osteoclasts plays an important role in the occurrence and development of osteoporosis. However, the mechanism underlying the osteoclast energy metabolism disorder that interferes with bone homeostasis has not been determined. Bone resorption by osteoclasts is a process that consumes large amounts of adenosine triphosphate (ATP) produced by glycolysis and oxidative phosphorylation. In addition to glucose, fatty acids and amino acids can also be used as substrates to produce energy through oxidative phosphorylation. In this review, we summarize and analyze the energy-based phenotypic changes, epigenetic regulation, and coupling with systemic energy metabolism of osteoclasts during the development and progression of osteoporosis. At the same time, we propose a hypothesis, the compensatory recovery mechanism (involving the balance between osteoclast survival and functional activation), which may provide a new approach for the treatment of osteoporosis.
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Affiliation(s)
| | - Lin Tao
- Department of Orthopedics, The First Hospital of China Medical University, Shenyang, China
| | - Yue Zhu
- Department of Orthopedics, The First Hospital of China Medical University, Shenyang, China
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McNeill SM, Baltos JA, White PJ, May LT. Biased agonism at adenosine receptors. Cell Signal 2021; 82:109954. [PMID: 33610717 DOI: 10.1016/j.cellsig.2021.109954] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/11/2021] [Accepted: 02/13/2021] [Indexed: 01/14/2023]
Abstract
Adenosine modulates many aspects of human physiology and pathophysiology through binding to the adenosine family of G protein-coupled receptors, which are comprised of four subtypes, the A1R, A2AR, A2BR and A3R. Modulation of adenosine receptor function by exogenous agonists, antagonists and allosteric modulators can be beneficial for a number of conditions including cardiovascular disease, Parkinson's disease, and cancer. Unfortunately, many preclinical drug candidates targeting adenosine receptors have failed in clinical trials due to limited efficacy and/or severe on-target undesired effects. To overcome the key barriers typically encountered when transitioning adenosine receptor ligands into the clinic, research efforts have focussed on exploiting the phenomenon of biased agonism. Biased agonism provides the opportunity to develop ligands that favour therapeutic signalling pathways, whilst avoiding signalling associated with on-target undesired effects. Recent studies have begun to define the structure-function relationships that underpin adenosine receptor biased agonism and establish how this phenomenon can be harnessed therapeutically. In this review we describe the recent advancements made towards achieving therapeutically relevant biased agonism at adenosine receptors.
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Affiliation(s)
- Samantha M McNeill
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Jo-Anne Baltos
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia; Department of Pharmacology, Monash University, Melbourne, VIC, Australia.
| | - Paul J White
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia
| | - Lauren T May
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, VIC, Australia; Department of Pharmacology, Monash University, Melbourne, VIC, Australia.
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A 2B Adenosine Receptor and Cancer. Int J Mol Sci 2019; 20:ijms20205139. [PMID: 31627281 PMCID: PMC6829478 DOI: 10.3390/ijms20205139] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/11/2019] [Accepted: 10/12/2019] [Indexed: 12/28/2022] Open
Abstract
There are four subtypes of adenosine receptors (ARs), named A1, A2A, A2B and A3, all of which are G protein-coupled receptors (GPCRs). Locally produced adenosine is a suppressant in anti-tumor immune surveillance. The A2BAR, coupled to both Gαs and Gαi G proteins, is one of the several GPCRs that are expressed in a significantly higher level in certain cancer tissues, in comparison to adjacent normal tissues. There is growing evidence that the A2BAR plays an important role in tumor cell proliferation, angiogenesis, metastasis, and immune suppression. Thus, A2BAR antagonists are novel, potentially attractive anticancer agents. Several antagonists targeting A2BAR are currently in clinical trials for various types of cancers. In this review, we first describe the signaling, agonists, and antagonists of the A2BAR. We further discuss the role of the A2BAR in the progression of various cancers, and the rationale of using A2BAR antagonists in cancer therapy.
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Pal Y, Bandyopadhyay N, Pal RS, Ahmed S, Bandopadhyay S. Perspective and Potential of A2A and A3 Adenosine Receptors as Therapeutic Targets for the Treatment of Rheumatoid Arthritis. Curr Pharm Des 2019; 25:2859-2874. [DOI: 10.2174/1381612825666190710111658] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 07/01/2019] [Indexed: 01/10/2023]
Abstract
Adenosine is a purine nucleoside which is an effective controller of inflammation. The inflammatory effect of adenosine is expressed via its four receptor subtypes viz. A1, A2A, A2B and A3. The various inflammatory conditions including rheumatoid arthritis (RA) are initiated by adenosine receptors of which A2A and A3 play a vital role. RA primarily is an auto-immune disorder which is manifested as chronic inflammation in the synovial lining of joints. In order to develop an effective treatment, the role of cytokines, IL–1, TNF-α and IL–6 is crucial. Besides, the knowledge of PI3K-PKB/Akt and NF-kB signaling pathway is also important to understand the antiinflammatory targets. Methotrexate along with various other molecules like, NSAIDs and DMARDs are presently used as treatment lines for controlling RA. The enhanced knowledge of the preclinical stages and pathogenesis along with recent potent therapeutics raises the hopes that RA can be prevented in the near future.
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Affiliation(s)
- Yogendra Pal
- Department of Pharmacy, Pranveer Singh Institute of Technology, Bhauti, Kanpur, Uttar Pradesh 209305, India
| | - Nabamita Bandyopadhyay
- Molecular Biology Division, National Institute of Malarial Research (NIMR), Dwarka, New Delhi, Delhi 110077, India
| | - Rashmi S. Pal
- Department of Pharmacy, Pranveer Singh Institute of Technology, Bhauti, Kanpur, Uttar Pradesh 209305, India
| | - Sarfaraz Ahmed
- Global Institute of Pharmaceutical Education and Research, Kashipur, Udham Singh Nagar, Uttarakhand 244713, India
| | - Shantanu Bandopadhyay
- Faculty of Pharmacy, Naraina Vidya Peeth Group of Institutions, Panki, Kanpur, Uttar Pradesh 208020, India
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The Adenosine A 2B Receptor Drives Osteoclast-Mediated Bone Resorption in Hypoxic Microenvironments. Cells 2019; 8:cells8060624. [PMID: 31234425 PMCID: PMC6628620 DOI: 10.3390/cells8060624] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/12/2019] [Accepted: 06/20/2019] [Indexed: 02/07/2023] Open
Abstract
Osteoclast-mediated bone destruction is amplified in the hypoxic synovial microenvironment of rheumatoid arthritis (RA). This increased bone resorption is driven by the hypoxia-inducible transcription factor HIF. We identified hypoxic induction of the HIF-regulated adenosine A2B receptor in primary human osteoclasts (mRNA, 3.8-fold increase, p < 0.01) and sought to identify the role(s) of purinergic signaling via this receptor in the bone resorption process. Primary human osteoclasts were differentiated from CD14+ monocytes and exposed to hypoxia (2% O2) and A2B receptor inhibitors (MRS1754, PSB603). The hypoxic increase in bone resorption was prevented by the inhibition of the A2B receptor, at least partly by the attenuation of glycolytic and mitochondrial metabolism via inhibition of HIF. A2B receptor inhibition also reduced osteoclastogenesis in hypoxia by inhibiting early cell fusion (day 3–4, p < 0.05). The A2B receptor is only functional in hypoxic or inflammatory environments when the extracellular concentrations of adenosine (1.6-fold increase, p < 0.05) are sufficient to activate the receptor. Inhibition of the A2B receptor under normoxic conditions therefore did not affect any parameter tested. Reciprocal positive regulation of HIF and the A2B receptor in a hypoxic microenvironment thus enhances glycolytic and mitochondrial metabolism in osteoclasts to drive increased bone resorption. A2B receptor inhibition could potentially prevent the pathological osteolysis associated with hypoxic diseases such as rheumatoid arthritis.
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Vecchio EA, White PJ, May LT. The adenosine A 2B G protein-coupled receptor: Recent advances and therapeutic implications. Pharmacol Ther 2019; 198:20-33. [PMID: 30677476 DOI: 10.1016/j.pharmthera.2019.01.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The adenosine A2B receptor (A2BAR) is one of four adenosine receptor subtypes belonging to the Class A family of G protein-coupled receptors (GPCRs). Until recently, the A2BAR remained poorly characterised, in part due to its relatively low affinity for the endogenous agonist adenosine and therefore presumed minor physiological significance. However, the substantial increase in extracellular adenosine concentration, the sensitisation of the receptor and the upregulation of A2BAR expression under conditions of hypoxia and inflammation, suggest the A2BAR as an exciting therapeutic target in a variety of pathological disease states. Here we discuss the pharmacology of the A2BAR and outline its role in pathophysiology including ischaemia-reperfusion injury, fibrosis, inflammation and cancer.
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Affiliation(s)
- Elizabeth A Vecchio
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia; Heart Failure Pharmacology, Baker Heart & Diabetes Institute, Melbourne, VIC 3004, Australia
| | - Paul J White
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Lauren T May
- Drug Discovery Biology, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia.
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Ortiz Zacarías NV, Lenselink EB, IJzerman AP, Handel TM, Heitman LH. Intracellular Receptor Modulation: Novel Approach to Target GPCRs. Trends Pharmacol Sci 2018; 39:547-559. [PMID: 29653834 DOI: 10.1016/j.tips.2018.03.002] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 03/07/2018] [Accepted: 03/08/2018] [Indexed: 12/23/2022]
Abstract
Recent crystal structures of multiple G protein-coupled receptors (GPCRs) have revealed a highly conserved intracellular pocket that can be used to modulate these receptors from the inside. This novel intracellular site partially overlaps with the G protein and β-arrestin binding site, providing a new manner of pharmacological intervention. Here we provide an update of the architecture and function of the intracellular region of GPCRs, until now portrayed as the signaling domain. We review the available evidence on the presence of intracellular binding sites among chemokine receptors and other class A GPCRs, as well as different strategies to target it, including small molecules, pepducins, and nanobodies. Finally, the potential advantages of intracellular (allosteric) ligands over orthosteric ligands are also discussed.
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Affiliation(s)
- Natalia V Ortiz Zacarías
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Eelke B Lenselink
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Adriaan P IJzerman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands
| | - Tracy M Handel
- University of California, San Diego, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA 92093, USA
| | - Laura H Heitman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC, Leiden, The Netherlands.
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Sun Y, Huang P. Adenosine A2B Receptor: From Cell Biology to Human Diseases. Front Chem 2016; 4:37. [PMID: 27606311 PMCID: PMC4995213 DOI: 10.3389/fchem.2016.00037] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 08/11/2016] [Indexed: 12/26/2022] Open
Abstract
Extracellular adenosine is a ubiquitous signaling molecule that modulates a wide array of biological processes. Recently, significant advances have been made in our understanding of A2B adenosine receptor (A2BAR). In this review, we first summarize some of the general characteristics of A2BAR, and then we describe the multiple binding partners of the receptor, such as newly identified α-actinin-1 and p105, and discuss how these associated proteins could modulate A2BAR's functions, including certain seemingly paradoxical functions of the receptor. Growing evidence indicates a critical role of A2BAR in cancer, renal disease, and diabetes, in addition to its importance in the regulation of vascular diseases, and lung disease. Here, we also discuss the role of A2BAR in cancer, renal disease, and diabetes and the potential of the receptor as a target for treating these three diseases.
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Affiliation(s)
- Ying Sun
- Department of Biology, South University of Science and Technology of ChinaShenzhen, China; Shenzhen Key Laboratory of Cell Microenvironment, South University of Science and Technology of ChinaShenzhen, China
| | - Pingbo Huang
- Division of Life Science, Hong Kong University of Science and TechnologyHong Kong, China; Division of Biomedical Engineering, Hong Kong University of Science and TechnologyHong Kong, China; State Key Laboratory of Molecular Neuroscience, Hong Kong University of Science and TechnologyHong Kong, China
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