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Cherchi F, Venturini M, Magni G, Scortichini M, Jacobson KA, Pugliese AM, Coppi E. Covalently Binding Adenosine A 3 Receptor Agonist ICBM Irreversibly Reduces Voltage-Gated Ca 2+ Currents in Dorsal Root Ganglion Neurons. Purinergic Signal 2024; 20:35-45. [PMID: 36918461 PMCID: PMC10828244 DOI: 10.1007/s11302-023-09929-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 03/02/2023] [Indexed: 03/16/2023] Open
Abstract
Interest has been focused in recent years on the analgesic effects exerted by adenosine and its receptors, A1, A2A, A2B, and A3 adenosine receptor (AR) subtypes, in different in vivo models of chronic pain. In particular, it was demonstrated that selective A3AR agonists reduced pro-nociceptive N-type Ca2+ channels in dorsal root ganglion (DRG) neurons isolated from rats and, by this mechanism, inhibit post inflammatory visceral hypersensitivity. In the present study, we investigate the effect of a previously reported irreversibly binding A3AR agonist, ICBM, on Ca2+ currents (ICa) in rat DRG neurons. Present data demonstrate that ICBM, an isothiocyanate derivative designed for covalent binding to the receptor, concentration-dependently inhibits ICa. This effect is irreversible, since it persists after drug removal, differently from the prototypical A3AR agonist, Cl-IB-MECA. ICBM pre-exposure inhibits the effect of a subsequent Cl-IB-MECA application. Thus, covalent A3AR agonists such as ICBM may represent an innovative, beneficial, and longer-lasting strategy to achieve efficacious chronic pain control versus commonly used, reversible, A3AR agonists. However, the possible limitations of this drug and other covalent drugs may be, for example, a characteristic adverse effect profile, suggesting that more pre-clinical studies are needed.
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Affiliation(s)
- Federica Cherchi
- Department of Neuroscience, Drug Research and Child Health, University of Florence, Viale Gaetano Pieraccini 6, 50139, PsychologyFlorence, Italy.
| | - Martina Venturini
- Department of Neuroscience, Drug Research and Child Health, University of Florence, Viale Gaetano Pieraccini 6, 50139, PsychologyFlorence, Italy
| | - Giada Magni
- Istituto Di Fisica Applicata "Nello Carrara," Consiglio Nazionale Delle Ricerche, Via Madonna del Piano 10, 50019, Sesto Fiorentino, Florence, Italy
| | - Mirko Scortichini
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Kenneth A Jacobson
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Anna Maria Pugliese
- Department of Neuroscience, Drug Research and Child Health, University of Florence, Viale Gaetano Pieraccini 6, 50139, PsychologyFlorence, Italy
| | - Elisabetta Coppi
- Department of Neuroscience, Drug Research and Child Health, University of Florence, Viale Gaetano Pieraccini 6, 50139, PsychologyFlorence, Italy
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Gao ZG, Auchampach JA, Jacobson KA. Species dependence of A 3 adenosine receptor pharmacology and function. Purinergic Signal 2023; 19:523-550. [PMID: 36538251 PMCID: PMC9763816 DOI: 10.1007/s11302-022-09910-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 11/26/2022] [Indexed: 12/24/2022] Open
Abstract
Efforts to fully understand pharmacological differences between G protein-coupled receptor (GPCR) species homologues are generally not pursued in detail during the drug development process. To date, many GPCRs that have been successfully targeted are relatively well-conserved across species in amino acid sequence and display minimal variability of biological effects. However, the A3 adenosine receptor (AR), an exciting drug target for a multitude of diseases associated with tissue injury, ischemia, and inflammation, displays as little as 70% sequence identity among mammalian species (e.g., rodent vs. primate) commonly used in drug development. Consequently, the pharmacological properties of synthetic A3AR ligands vary widely, not only in binding affinity, selectivity, and signaling efficacy, but to the extent that some function as agonists in some species and antagonists in others. Numerous heterocyclic antagonists that have nM affinity at the human A3AR are inactive or weakly active at the rat and mouse A3ARs. Positive allosteric modulators, including the imidazo [4,5-c]quinolin-4-amine derivative LUF6000, are only active at human and some larger animal species that have been evaluated (rabbit and dog), but not rodents. A3AR agonists evoke systemic degranulation of rodent, but not human mast cells. The rat A3AR undergoes desensitization faster than the human A3AR, but the human homologue can be completely re-sensitized and recycled back to the cell surface. Thus, comprehensive pharmacological evaluation and awareness of potential A3AR species differences are critical in studies to further understand the basic biological functions of this unique AR subtype. Recombinant A3ARs from eight different species have been pharmacologically characterized thus far. In this review, we describe in detail current knowledge of species differences in genetic identity, G protein-coupling, receptor regulation, and both orthosteric and allosteric A3AR pharmacology.
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Affiliation(s)
- Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0810, USA.
| | - John A Auchampach
- Department of Pharmacology and Toxicology, and the Cardiovascular Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI, 53226, USA
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, 20892-0810, USA.
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A3 adenosine receptor agonist IB-MECA reverses chronic cerebral ischemia-induced inhibitory avoidance memory deficit. Eur J Pharmacol 2022; 921:174874. [DOI: 10.1016/j.ejphar.2022.174874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 02/08/2022] [Accepted: 03/07/2022] [Indexed: 12/24/2022]
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Valdés F, Arévalo B, Gutiérrez M, García-Castillo V, Salgado-García R, Pérez-Plasencia C, Valenzuela C, Cayo Á, Olate-Briones A, Brown N. Two New Adenosine Derivatives and their Antiproliferative Properties, an In Vitro Evaluation. Anticancer Agents Med Chem 2021; 22:1414-1425. [PMID: 34053425 DOI: 10.2174/1871520621666210528151818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 03/24/2021] [Accepted: 04/05/2021] [Indexed: 11/22/2022]
Abstract
BACKGROUND Adenosine is a natural nucleoside present in various organs and tissues, where it acts as a modulator of diverse physiological and pathophysiological processes. These actions are mediated by at least four G protein-coupled receptors, which are widely and differentially expressed in tissues. Interestingly, high concentrations of adenosine have been reported in a variety of tumors. In this context, the final output of adenosine in tumorigenesis will likely depend on the constellation of adenosine receptors expressed by tumor and stromal cells. Notably, activation of the A3 receptor can reduce the proliferative capacity of various cancer cells. OBJECTIVE The objective of this study is to describe the anti-proliferative effects of two previously synthesized adenosine derivatives with A3 agonist action (compounds 2b and 2f) through in vitro assays. METHOD We used gastric and breast cancer cell lines expressing the A3 receptor as in vitro models and theoretical experiments such as molecular dynamics and determination of ADME properties. RESULTS The antiproliferative effects of adenosine derivatives (after determining IC50 values) were comparable or even higher than those described for IB-MECA, a commercially available A3 agonist. Among possible mechanisms involved, apoptosis was found to be induced in MCF-7 cells but not in AGS or MDA-MB-231 cells. Surprisingly, we were unable to observe cellular senescence induction upon treatment with compounds 2b and 2f in any of the cell lines studied, although we cannot rule out other forms of cell cycle exit at this point. CONCLUSION Both adenosine derivatives showed antiproliferative effects on gastric and breast cancer cell lines, and were able to induce apoptosis, at least in the MCF-7 cell line. Further studies will be necessary to unveil receptor specificity and mechanisms accounting for the antiproliferative properties of these novel semi-synthetic compounds.
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Affiliation(s)
- Francisco Valdés
- Organic Synthesis Laboratory and Biological Activity (LSO-Act-Bio), PhD Sciences Mention Investigation and Development of Bioactive Products, Institute of Chemistry of Natural Resources, University of Talca, Chile
| | - Bárbara Arévalo
- Centro de Estudios en Alimentos Procesados- CEAP, Conicyt, Programa Regional R19A10001, Gore Maule, Talca, Chile; 3Institute of Chemistry of Natural Resources, University of Talca, Chile
| | | | | | | | - Carlos Pérez-Plasencia
- FES-Iztacala, UBIMED, National Autonomous University of Mexico, UNAM, Tlalnepantla, Mexico
| | | | - Ángel Cayo
- Medical School, University of Talca, Chile
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Ferreira-Silva J, Aires ID, Boia R, Ambrósio AF, Santiago AR. Activation of Adenosine A 3 Receptor Inhibits Microglia Reactivity Elicited by Elevated Pressure. Int J Mol Sci 2020; 21:ijms21197218. [PMID: 33007835 PMCID: PMC7582754 DOI: 10.3390/ijms21197218] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 09/25/2020] [Accepted: 09/29/2020] [Indexed: 01/22/2023] Open
Abstract
Glaucoma is a progressive chronic retinal degenerative disease and a leading cause of global irreversible blindness, characterized by optic nerve damage and retinal ganglion cell (RGC) death. Elevated intraocular pressure (IOP) is a main risk factor of glaucoma. Neuroinflammation plays an important role in glaucoma. We have been demonstrating that elevated pressure triggers microglia reactivity that contribute to the loss of RGCs. Adenosine, acting on adenosine receptors, is a crucial modulator of microglia phenotype. Microglia express all adenosine receptors. Previously, we demonstrated that the activation of adenosine A3 receptor (A3R) affords protection to the retina, including RGCs, unveiling the possibility for a new strategy for glaucoma treatment. Since microglial cells express A3R, we now studied the ability of a selective A3R agonist (2-Cl-IB-MECA) in controlling microglia reactivity induced by elevated hydrostatic pressure (EHP), used to mimic elevated IOP. The activation of A3R reduced EHP-induced inducible nitric oxide synthase (iNOS) expression, microglia migration and phagocytosis in BV-2 cells. In retinal microglia, proliferation and phagocytosis elicited by EHP were also decreased by A3R activation. This work demonstrates that 2-Cl-IB-MECA, the selective agonist of A3R, is able to hinder microglia reactivity, suggesting that A3R agonists could afford protection against glaucomatous degeneration through the control of neuroinflammation.
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Affiliation(s)
- Joana Ferreira-Silva
- Coimbra Institute for Clinical and Biomedical Research (ICBR), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.F.-S.); (I.D.A.); (R.B.); (A.F.A.)
- Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-548 Coimbra, Portugal
| | - Inês D. Aires
- Coimbra Institute for Clinical and Biomedical Research (ICBR), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.F.-S.); (I.D.A.); (R.B.); (A.F.A.)
- Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-548 Coimbra, Portugal
| | - Raquel Boia
- Coimbra Institute for Clinical and Biomedical Research (ICBR), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.F.-S.); (I.D.A.); (R.B.); (A.F.A.)
- Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-548 Coimbra, Portugal
| | - António Francisco Ambrósio
- Coimbra Institute for Clinical and Biomedical Research (ICBR), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.F.-S.); (I.D.A.); (R.B.); (A.F.A.)
- Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-548 Coimbra, Portugal
- Association for Innovation and Biomedical Research on Light and Image, 3000-548 Coimbra, Portugal
| | - Ana Raquel Santiago
- Coimbra Institute for Clinical and Biomedical Research (ICBR), Faculty of Medicine, University of Coimbra, 3000-548 Coimbra, Portugal; (J.F.-S.); (I.D.A.); (R.B.); (A.F.A.)
- Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
- Clinical Academic Center of Coimbra (CACC), 3000-548 Coimbra, Portugal
- Association for Innovation and Biomedical Research on Light and Image, 3000-548 Coimbra, Portugal
- Correspondence: ; Tel.: +351-239480226
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Ceruti S, Abbracchio MP. Adenosine Signaling in Glioma Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1202:13-33. [PMID: 32034707 DOI: 10.1007/978-3-030-30651-9_2] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Purines and pyrimidines are fundamental signaling molecules in controlling the survival and proliferation of astrocytes, as well as in mediating cell-to-cell communication between glial cells and neurons in the healthy brain. The malignant transformation of astrocytes towards progressively more aggressive brain tumours (from astrocytoma to anaplastic glioblastoma) leads to modifications in both the survival and cell death pathways which overall confer a growth advantage to malignant cells and resistance to many cytotoxic stimuli. It has been demonstrated, however, that, in astrocytomas, several purinergic (in particular adenosinergic) pathways controlling cell survival and death are still effective and, in some cases, even enhanced, providing invaluable targets for purine-based chemotherapy, that still represents an appropriate pharmacological approach to brain tumours. In this chapter, the current knowledge on both receptor-mediated and receptor-independent adenosine pathways in astrocytomas will be reviewed, with a particular emphasis on the most promising targets which could be translated from in vitro studies to in vivo pharmacology. Additionally, we have included new original data from our laboratory demonstrating a key involvement of MAP kinases in the cytostastic and cytotoxic effects exerted by an adenosine analogue, 2-CdA, which with the name of Cladribine is already clinically utilized in haematological malignancies. Here we show that 2-CdA can activate multiple intracellular pathways leading to cell cycle block and cell death by apoptosis of a human astrocytoma cell line that bears several pro-survival genetic mutations. Although in vivo data are still lacking, our results suggest that adenosine analogues could therefore be exploited to overcome resistance to chemotherapy of brain tumours.
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Affiliation(s)
- Stefania Ceruti
- Laboratory of Molecular and Cellular Pharmacology of Purinergic Transmission, Department of Pharmacological Sciences, University of Milan - Università degli Studi di Milano, Milan, Italy.
| | - Maria P Abbracchio
- Laboratory of Molecular and Cellular Pharmacology of Purinergic Transmission, Department of Pharmacological Sciences, University of Milan - Università degli Studi di Milano, Milan, Italy
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Tan A, Babak MV, Venkatesan G, Lim C, Klotz KN, Herr DR, Cheong SL, Federico S, Spalluto G, Ong WY, Chen YZ, Loo JSE, Pastorin G. Design, Synthesis and Evaluation of New Indolylpyrimidylpiperazines for Gastrointestinal Cancer Therapy. Molecules 2019; 24:E3661. [PMID: 31614517 PMCID: PMC6832257 DOI: 10.3390/molecules24203661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 10/04/2019] [Accepted: 10/08/2019] [Indexed: 11/29/2022] Open
Abstract
Human A3 adenosine receptor hA3AR has been implicated in gastrointestinal cancer, where its cellular expression has been found increased, thus suggesting its potential as a molecular target for novel anticancer compounds. Observation made in our previous work indicated the importance of the carbonyl group of amide in the indolylpyrimidylpiperazine (IPP) for its human A2A adenosine receptor (hA2AAR) subtype binding selectivity over the other AR subtypes. Taking this observation into account, we structurally modified an indolylpyrimidylpiperazine (IPP) scaffold, 1 (a non-selective adenosine receptors' ligand) into a modified IPP (mIPP) scaffold by switching the position of the carbonyl group, resulting in the formation of both ketone and tertiary amine groups in the new scaffold. Results showed that such modification diminished the A2A activity and instead conferred hA3AR agonistic activity. Among the new mIPP derivatives (3-6), compound 4 showed potential as a hA3AR partial agonist, with an Emax of 30% and EC50 of 2.89 ± 0.55 μM. In the cytotoxicity assays, compound 4 also exhibited higher cytotoxicity against both colorectal and liver cancer cells as compared to normal cells. Overall, this new series of compounds provide a promising starting point for further development of potent and selective hA3AR partial agonists for the treatment of gastrointestinal cancers.
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Affiliation(s)
- Aaron Tan
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Centre for Life Sciences, #05-01, 28 Medical Drive, Singapore 117456, Singapore.
| | - Maria V Babak
- Department of Pharmacy, National University of Singapore, Singapore 119260, Singapore.
| | | | - Clarissa Lim
- Department of Pharmacy, National University of Singapore, Singapore 119260, Singapore.
| | - Karl-Norbert Klotz
- Institut für Pharmakologie und Toxikologie, Universität Würzburg, 97078 Würzburg, Germany.
| | - Deron Raymond Herr
- Department of Pharmacology, National University of Singapore, Singapore 117600, Singapore.
| | - Siew Lee Cheong
- Department of Pharmaceutical Chemistry, School of Pharmacy, International Medical University, 126 Jalan Jalil Perkasa 19, Bukit Jalil, Kuala Lumpur 57000, Malaysia.
| | - Stephanie Federico
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, 34127 Trieste, Italy.
| | - Giampiero Spalluto
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, 34127 Trieste, Italy.
| | - Wei-Yi Ong
- Department of Anatomy, National University of Singapore, Singapore 119260, Singapore.
| | - Yu Zong Chen
- Department of Pharmacy, National University of Singapore, Singapore 119260, Singapore.
| | - Jason Siau Ee Loo
- School of Pharmacy, Faculty of Health and Medical Sciences, Taylor's University, 1, Jalan Taylors, Subang Jaya, Selangor 47500, Malaysia.
| | - Giorgia Pastorin
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Centre for Life Sciences, #05-01, 28 Medical Drive, Singapore 117456, Singapore.
- Department of Pharmacy, National University of Singapore, Singapore 119260, Singapore.
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Stamatis D, Lagarias P, Barkan K, Vrontaki E, Ladds G, Kolocouris A. Structural Characterization of Agonist Binding to an A 3 Adenosine Receptor through Biomolecular Simulations and Mutagenesis Experiments. J Med Chem 2019; 62:8831-8846. [PMID: 31502843 DOI: 10.1021/acs.jmedchem.9b01164] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The adenosine A3 receptor (A3R) binds adenosine and is a drug target against cancer cell proliferation. Currently, there is no experimental structure of A3R. Here, we have generated a molecular model of A3R in complex with two agonists, the nonselective 1-(6-amino-9H-purin-9-yl)-1-deoxy-N-ethyl-β-d-ribofuranuronamide (NECA) and the selective 1-deoxy-1-[6-[[(3-iodophenyl)methyl]amino]-9H-purin-9-yl]-N-methyl-β-d-ribofuranuronamide (IB-MECA). Molecular dynamics simulations of the wild-type A3R in complex with both agonists, combined with in vitro mutagenic studies revealed important residues for binding. Further, molecular mechanics-generalized Born surface area calculations were able to distinguish mutations that reduce or negate agonistic activity from those that maintained or increased the activity. Our studies reveal that selectivity of IB-MECA toward A3R requires not only direct interactions with residues within the orthosteric binding area but also with remote residues. Although V1695.30 is considered to be a selectivity filter for A3R binders, when it was mutated to glutamic acid or alanine, the activity of IB-MECA increased by making new van der Waals contacts with TM5. This result may have implications in the design of new A3R agonists.
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Affiliation(s)
- Dimitrios Stamatis
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
| | - Panagiotis Lagarias
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
| | - Kerry Barkan
- Department of Pharmacology , University of Cambridge , Tennis Court Road , CB2 1PD Cambridge U.K
| | - Eleni Vrontaki
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
| | - Graham Ladds
- Department of Pharmacology , University of Cambridge , Tennis Court Road , CB2 1PD Cambridge U.K
| | - Antonios Kolocouris
- Division of Pharmaceutical Chemistry, Department of Pharmacy, School of Health Sciences , National and Kapodistrian University of Athens , Panepistimiopolis-Zografou , 15771 Athens , Greece
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Wan TC, Tampo A, Kwok WM, Auchampach JA. Ability of CP-532,903 to protect mouse hearts from ischemia/reperfusion injury is dependent on expression of A 3 adenosine receptors in cardiomyoyctes. Biochem Pharmacol 2019; 163:21-31. [PMID: 30710517 DOI: 10.1016/j.bcp.2019.01.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Accepted: 01/28/2019] [Indexed: 10/27/2022]
Abstract
A3 adenosine receptor (A3AR) agonists are effective at limiting injury caused by ischemia/reperfusion injury of the heart in experimental animal models. However, understanding of their mechanism of action, which is likely multifactorial, remains incomplete. In prior studies, it has been demonstrated that A3AR-mediated ischemic protection is blocked by glibenclamide and is absent in Kir6.2 gene ablated mice that lack the pore-forming subunit of the ATP-sensitive potassium (KATP) channel, suggesting one contributing mechanism may involve accelerated activation of KATP channels. However, presence of A3ARs in the myocardium has yet to be established. Utilizing a whole-cell recording technique, in this study we confirm functional expression of the A3AR in adult mouse ventricular cardiomyocytes, coupled to activation of ATP-dependent potassium (KATP) channels via Gi inhibitory proteins. We further show that ischemic protection provided by the selective A3AR agonist CP-532,903 in an isolated, buffer-perfused heart model is lost completely in Adora3LoxP/LoxP;Myh6-Cre mice, which is a newly developed model developed and comprehensively described herein whereby the A3AR gene (Adora3) is deleted exclusively in cardiomyocytes. Our findings, taken together with previously published work, are consistent with the hypothesis that A3AR agonists provide ischemic tolerance, at least in part, by facilitating opening of myocardial KATP channels.
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Affiliation(s)
- Tina C Wan
- Department of Pharmacology & Toxicology, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Akihito Tampo
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - Wai-Meng Kwok
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, United States
| | - John A Auchampach
- Department of Pharmacology & Toxicology, Medical College of Wisconsin, Milwaukee, WI 53226, United States; Cardiovascular Center, Medical College of Wisconsin, Milwaukee, WI 53226, United States.
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10
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Probing structure-activity relationship in β-arrestin2 recruitment of diversely substituted adenosine derivatives. Biochem Pharmacol 2018; 158:103-113. [PMID: 30292756 DOI: 10.1016/j.bcp.2018.10.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2018] [Accepted: 10/02/2018] [Indexed: 12/18/2022]
Abstract
In the adenosine receptor (AR) subfamily of G protein-coupled receptors (GPCRs), biased agonism has been described for the human A1AR, A2BAR and A3AR. While diverse A3AR agonists have been evaluated for receptor binding and Gi-mediated cAMP signalling, the β-arrestin2 (βarr2) pathway has been left largely unexplored. We screened nineteen diverse adenosine derivatives for βarr2 recruitment using a stable hA3AR-NanoBit®-βarr2 HEK293T cell line. Their activity profiles were compared with a cAMP accumulation assay in stable hA3AR CHO cells. Structural features linked to βarr2 activation were further investigated by the evaluation of an additional ten A3AR ligands. The A3AR-selective reference agonist 2-Cl-IB-MECA, which is a full agonist in terms of cAMP inhibition, only showed partial agonist behaviour in βarr2 recruitment. Highly A3AR-selective (N)-methanocarba 5'-uronamide adenosine derivatives displayed higher potency in both cAMP signalling and βarr2 recruitment than reference agonists NECA and 2-Cl-IB-MECA. Their A3AR-preferred conformation tolerates C2-position substitutions, for increased βarr2 efficacy, better than the flexible scaffolds of ribose derivatives. The different amino functionalities in the adenosine scaffold of these derivatives each seem to be important for signalling as well. In conclusion, we have provided insights into ligand features that can help to guide the future therapeutic development of biased A3AR ligands with respect to G-protein and βarr2 signalling.
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Jacobson KA, Merighi S, Varani K, Borea PA, Baraldi S, Tabrizi MA, Romagnoli R, Baraldi PG, Ciancetta A, Tosh DK, Gao ZG, Gessi S. A 3 Adenosine Receptors as Modulators of Inflammation: From Medicinal Chemistry to Therapy. Med Res Rev 2018; 38:1031-1072. [PMID: 28682469 PMCID: PMC5756520 DOI: 10.1002/med.21456] [Citation(s) in RCA: 111] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 05/02/2017] [Accepted: 06/13/2017] [Indexed: 01/09/2023]
Abstract
The A3 adenosine receptor (A3 AR) subtype is a novel, promising therapeutic target for inflammatory diseases, such as rheumatoid arthritis (RA) and psoriasis, as well as liver cancer. A3 AR is coupled to inhibition of adenylyl cyclase and regulation of mitogen-activated protein kinase (MAPK) pathways, leading to modulation of transcription. Furthermore, A3 AR affects functions of almost all immune cells and the proliferation of cancer cells. Numerous A3 AR agonists, partial agonists, antagonists, and allosteric modulators have been reported, and their structure-activity relationships (SARs) have been studied culminating in the development of potent and selective molecules with drug-like characteristics. The efficacy of nucleoside agonists may be suppressed to produce antagonists, by structural modification of the ribose moiety. Diverse classes of heterocycles have been discovered as selective A3 AR blockers, although with large species differences. Thus, as a result of intense basic research efforts, the outlook for development of A3 AR modulators for human therapeutics is encouraging. Two prototypical selective agonists, N6-(3-Iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA; CF101) and 2-chloro-N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Cl-IB-MECA; CF102), have progressed to advanced clinical trials. They were found safe and well tolerated in all preclinical and human clinical studies and showed promising results, particularly in psoriasis and RA, where the A3 AR is both a promising therapeutic target and a biologically predictive marker, suggesting a personalized medicine approach. Targeting the A3 AR may pave the way for safe and efficacious treatments for patient populations affected by inflammatory diseases, cancer, and other conditions.
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Affiliation(s)
- Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Stefania Merighi
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Katia Varani
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Pier Andrea Borea
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy
| | - Stefania Baraldi
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Mojgan Aghazadeh Tabrizi
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Romeo Romagnoli
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Pier Giovanni Baraldi
- Department of Pharmaceutical Sciences, University of Ferrara, Via Fossato di Mortara 17, 44121 Ferrara, Italy
| | - Antonella Ciancetta
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Dilip K. Tosh
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD20892
| | - Stefania Gessi
- Department of Medical Sciences, Pharmacology Section, University of Ferrara, Via Fossato di Mortara 17/19, 44121 Ferrara, Italy
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12
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Inhibition of IL-17 and IL-23 in Human Keratinocytes by the A 3 Adenosine Receptor Agonist Piclidenoson. J Immunol Res 2018; 2018:2310970. [PMID: 29862305 PMCID: PMC5976987 DOI: 10.1155/2018/2310970] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/28/2018] [Accepted: 04/17/2018] [Indexed: 02/08/2023] Open
Abstract
Interleukin-17 and interleukin-23 play major roles in the inflammatory process in psoriasis. The Gi protein-associated A3 adenosine receptor (A3AR) is known to be overexpressed in inflammatory cells and in peripheral blood mononuclear cells (PBMCs) of patients with autoimmune inflammatory conditions. Piclidenoson, a selective agonist at the A3AR, induces robust anti-inflammatory effect in psoriasis patients. In this study, we aimed to explore A3AR expression levels in psoriasis patients and its role in mediating the anti-inflammatory effect of piclidenoson in human keratinocyte cells. A3AR expression levels were evaluated in skin tissue and PBMCs derived from psoriasis patients and healthy subjects. Proliferation assay and the expression of signaling proteins were used to evaluate piclidenoson effect on human keratinocytes (HaCat). High A3AR expression levels were found in a skin biopsy and in PBMCs from psoriasis patients in comparison to healthy subjects. Piclidenoson inhibited the proliferation of HaCat cells through deregulation of the NF-κB signaling pathway, leading to a decrease in interleukin-17 and interleukin-23 expression levels. This effect was counteracted by the specific antagonist MRS 1523. A3AR overexpression in skin and PBMCs of psoriasis patients may be used as a target to inhibit pathological cell proliferation and the production of interleukin-17 and interleukin-23.
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Preclinical In Vitro and In Vivo Evaluation of [ 18F]FE@SUPPY for Cancer PET Imaging: Limitations of a Xenograft Model for Colorectal Cancer. CONTRAST MEDIA & MOLECULAR IMAGING 2018; 2018:1269830. [PMID: 29666562 PMCID: PMC5830979 DOI: 10.1155/2018/1269830] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Accepted: 12/27/2017] [Indexed: 01/20/2023]
Abstract
Molecular imaging probes such as PET-tracers have the potential to improve the accuracy of tumor characterization by directly visualizing the biochemical situation. Thus, molecular changes can be detected early before morphological manifestation. The A3 adenosine receptor (A3AR) is described to be highly expressed in colon cancer cell lines and human colorectal cancer (CRC), suggesting this receptor as a tumor marker. The aim of this preclinical study was the evaluation of [18F]FE@SUPPY as a PET-tracer for CRC using in vitro imaging and in vivo PET imaging. First, affinity and selectivity of FE@SUPPY and its metabolites were determined, proving the favorable binding profile of FE@SUPPY. The human adenocarcinoma cell line HT-29 was characterized regarding its hA3AR expression and was subsequently chosen as tumor graft. Promising results regarding the potential of [18F]FE@SUPPY as a PET-tracer for CRC imaging were obtained by autoradiography as ≥2.3-fold higher accumulation of [18F]FE@SUPPY was found in CRC tissue compared to adjacent healthy colon tissue from the same patient. Nevertheless, first in vivo studies using HT-29 xenografts showed insufficient tumor uptake due to (1) poor conservation of target expression in xenografts and (2) unfavorable pharmacokinetics of [18F]FE@SUPPY in mice. We therefore conclude that HT-29 xenografts are not adequate to visualize hA3ARs using [18F]FE@SUPPY.
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14
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Sarkar B, Maiti S, Jadhav GR, Paira P. Discovery of benzothiazolylquinoline conjugates as novel human A 3 receptor antagonists: biological evaluations and molecular docking studies. ROYAL SOCIETY OPEN SCIENCE 2018; 5:171622. [PMID: 29515874 PMCID: PMC5830763 DOI: 10.1098/rsos.171622] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 01/08/2018] [Indexed: 03/16/2024]
Abstract
Adenosine is known as an endogenous purine nucleoside and it modulates a wide variety of physiological responses by interacting with adenosine receptors. Among the four adenosine receptor subtypes, the A3 receptor is of major interest in this study as it is overexpressed in some cancer cell lines. Herein, we have highlighted the strategy of designing the hA3 receptor targeted novel benzothiazolylquinoline scaffolds. The radioligand binding data of the reported compounds are rationalized with the molecular docking results. Compound 6a showed best potency and selectivity at hA3 among other adenosine receptors.
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Affiliation(s)
| | | | | | - Priyankar Paira
- Department of Chemistry, School of Advanced Sciences, VIT University, Vellore, Tamil Nadu 632014, India
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15
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Storme J, Cannaert A, Van Craenenbroeck K, Stove CP. Molecular dissection of the human A 3 adenosine receptor coupling with β-arrestin2. Biochem Pharmacol 2018; 148:298-307. [PMID: 29309765 DOI: 10.1016/j.bcp.2018.01.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 01/03/2018] [Indexed: 02/07/2023]
Abstract
Besides classical G protein coupling, G protein-coupled receptors (GPCRs) are nowadays well known to show significant signalling via other adaptor proteins, such as β-arrestin2 (βarr2). The elucidation of the molecular mechanism of the GPCR-βarr2 interaction is a prerequisite for the structure-activity based design of biased ligands, which introduces a new chapter in drug discovery. The general mechanism of the interaction is believed to rely on phosphorylation sites, exposed upon agonist binding. However, it is not known whether this mechanism is universal throughout the GPCR family or if GPCR-specific patterns are involved. In recent years, promising orally active agonists for the human A3 adenosine receptor (A3AR), a GPCR highly expressed in inflammatory and cancer cells, have been evaluated in clinical trials for the treatment of rheumatoid arthritis, psoriasis, and hepatocellular carcinoma. In this study, the effect of cytoplasmic modifications of the A3AR on βarr2 recruitment was evaluated in transiently transfected HEK293T cells, using a live-cell split-reporter system (NanoBit®, Promega), based on the structural complementation of NanoLuc luciferase, allowing real-time βarr2 monitoring. The A3AR-selective reference agonist 2-Cl-IB-MECA yielded a robust, concentration dependent (5 nM-1 µM) recruitment of βarr2 (logEC50: -7.798 ± 0.076). The role of putative phosphorylation sites, located in the C-terminal part and cytoplasmic loops, and the role of the 'DRY' motif was evaluated. It was shown that the A3AR C-terminus was dispensable for βarr2 recruitment. This contrasts with studies in the past for the rat A3AR, which pointed at crucial C-terminal phosphorylation sites. When combining truncation of the A3AR with modification of the 'DRY' motif to 'AAY', the βarr2 recruitment was drastically reduced. Recruitment could be partly rescued by back-mutation to 'NQY', or by extending the C-terminus again. In conclusion, other parts of the human A3AR, either cytosolic or exposed upon receptor activation, rather than the C-terminus alone, are responsible for βarr2 recruitment in a complementary or synergistic way.
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Affiliation(s)
- Jolien Storme
- Laboratory of Toxicology, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Annelies Cannaert
- Laboratory of Toxicology, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Kathleen Van Craenenbroeck
- Laboratory of Toxicology, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium
| | - Christophe P Stove
- Laboratory of Toxicology, Department of Bioanalysis, Faculty of Pharmaceutical Sciences, Ghent University, Ottergemsesteenweg 460, 9000 Ghent, Belgium.
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16
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Kazemi MH, Raoofi Mohseni S, Hojjat-Farsangi M, Anvari E, Ghalamfarsa G, Mohammadi H, Jadidi-Niaragh F. Adenosine and adenosine receptors in the immunopathogenesis and treatment of cancer. J Cell Physiol 2017; 233:2032-2057. [DOI: 10.1002/jcp.25873] [Citation(s) in RCA: 97] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Accepted: 02/21/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Mohammad H. Kazemi
- Student Research Committee, Department of Immunology, School of Medicine; Iran University of Medical Sciences (IUMS); Tehran Iran
- Immunology Research Center; Tabriz University of Medical Sciences; Tabriz Iran
| | - Sahar Raoofi Mohseni
- Department of Immunology, School of Public Health; Tehran University of Medical Sciences; Tehran Iran
| | - Mohammad Hojjat-Farsangi
- Department of Oncology-Pathology, Immune and Gene Therapy Lab, Cancer Center Karolinska (CCK); Karolinska University Hospital Solna and Karolinska Institute; Stockholm Sweden
- Department of Immunology, School of Medicine; Bushehr University of Medical Sciences; Bushehr Iran
| | - Enayat Anvari
- Faculty of Medicine, Department of Physiology; Ilam University of Medical Sciences; Ilam Iran
| | - Ghasem Ghalamfarsa
- Medicinal Plants Research Center; Yasuj University of Medical Sciences; Yasuj Iran
| | - Hamed Mohammadi
- Immunology Research Center; Tabriz University of Medical Sciences; Tabriz Iran
- Faculty of Medicine, Department of Immunology; Tabriz University of Medical Sciences; Tabriz Iran
| | - Farhad Jadidi-Niaragh
- Immunology Research Center; Tabriz University of Medical Sciences; Tabriz Iran
- Department of Immunology, School of Public Health; Tehran University of Medical Sciences; Tehran Iran
- Faculty of Medicine, Department of Immunology; Tabriz University of Medical Sciences; Tabriz Iran
- Drug Applied Research Center; Tabriz University of Medical Sciences; Tabriz Iran
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17
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Jacobson KA, Civan MM. Ocular Purine Receptors as Drug Targets in the Eye. J Ocul Pharmacol Ther 2016; 32:534-547. [PMID: 27574786 PMCID: PMC5069731 DOI: 10.1089/jop.2016.0090] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 07/13/2016] [Indexed: 02/06/2023] Open
Abstract
Agonists and antagonists of various subtypes of G protein coupled adenosine receptors (ARs), P2Y receptors (P2YRs), and ATP-gated P2X receptor ion channels (P2XRs) are under consideration as agents for the treatment of ocular diseases, including glaucoma and dry eye. Numerous nucleoside and nonnucleoside modulators of the receptors are available as research tools and potential therapeutic molecules. Three of the 4 subtypes of ARs have been exploited with clinical candidate molecules for treatment of the eye: A1, A2A, and A3. An A1AR agonist is in clinical trials for glaucoma, A2AAR reduces neuroinflammation, A3AR protects retinal ganglion cells from apoptosis, and both A3AR agonists and antagonists had been reported to lower intraocular pressure (IOP). Extracellular concentrations of endogenous nucleotides, including dinucleoside polyphosphates, are increased in pathological states, activating P2Y and P2XRs throughout the eye. P2YR agonists, including P2Y2 and P2Y6, lower IOP. Antagonists of the P2X7R prevent the ATP-induced neuronal apoptosis in the retina. Thus, modulators of the purinome in the eye might be a source of new therapies for ocular diseases.
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Affiliation(s)
- Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Mortimer M. Civan
- Departments of Physiology and Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania
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18
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Nishat S, Khan LA, Ansari ZM, Basir SF. Adenosine A3 Receptor: A promising therapeutic target in cardiovascular disease. Curr Cardiol Rev 2016; 12:18-26. [PMID: 26750723 PMCID: PMC4807713 DOI: 10.2174/1573403x12666160111125116] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Accepted: 11/28/2015] [Indexed: 11/22/2022] Open
Abstract
Cardiovascular complications are one of the major factors for early mortality in the present
worldwide scenario and have become a major challenge in both developing and developed nations. It
has thus become of immense importance to look for different therapeutic possibilities and treatments
for the growing burden of cardiovascular diseases. Recent advancements in research have opened
various means for better understanding of the complication and treatment of the disease. Adenosine
receptors have become tool of choice in understanding the signaling mechanism which might lead to
the cardiovascular complications. Adenosine A3 receptor is one of the important receptor which is extensively studied as a
therapeutic target in cardiovascular disorder. Recent studies have shown that A3AR is involved in the amelioration of cardiovascular
complications by altering the expression of A3AR. This review focuses towards the therapeutic potential of
A3AR involved in cardiovascular disease and it might help in better understanding of mechanism by which this receptor
may prove useful in improving the complications arising due to various cardiovascular diseases. Understanding of A3AR
signaling may also help to develop newer agonists and antagonists which might be prove helpful in the treatment of cardiovascular
disorder.
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Affiliation(s)
| | | | | | - Seemi F Basir
- Department of Biosciences, Faculty of Natural Sciences, Jamia Millia Islamia, New Delhi-110025, India.
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Pedata F, Dettori I, Coppi E, Melani A, Fusco I, Corradetti R, Pugliese AM. Purinergic signalling in brain ischemia. Neuropharmacology 2015; 104:105-30. [PMID: 26581499 DOI: 10.1016/j.neuropharm.2015.11.007] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Revised: 11/04/2015] [Accepted: 11/06/2015] [Indexed: 12/18/2022]
Abstract
Ischemia is a multifactorial pathology characterized by different events evolving in the time. After ischemia a primary damage due to the early massive increase of extracellular glutamate is followed by activation of resident immune cells, i.e microglia, and production or activation of inflammation mediators. Protracted neuroinflammation is now recognized as the predominant mechanism of secondary brain injury progression. Extracellular concentrations of ATP and adenosine in the brain increase dramatically during ischemia in concentrations able to stimulate their respective specific P2 and P1 receptors. Both ATP P2 and adenosine P1 receptor subtypes exert important roles in ischemia. Although adenosine exerts a clear neuroprotective effect through A1 receptors during ischemia, the use of selective A1 agonists is hampered by undesirable peripheral effects. Evidence up to now in literature indicate that A2A receptor antagonists provide protection centrally by reducing excitotoxicity, while agonists at A2A (and possibly also A2B) and A3 receptors provide protection by controlling massive infiltration and neuroinflammation in the hours and days after brain ischemia. Among P2X receptors most evidence indicate that P2X7 receptor contribute to the damage induced by the ischemic insult due to intracellular Ca(2+) loading in central cells and facilitation of glutamate release. Antagonism of P2X7 receptors might represent a new treatment to attenuate brain damage and to promote proliferation and maturation of brain immature resident cells that can promote tissue repair following cerebral ischemia. Among P2Y receptors, antagonists of P2Y12 receptors are of value because of their antiplatelet activity and possibly because of additional anti-inflammatory effects. Moreover strategies that modify adenosine or ATP concentrations at injury sites might be of value to limit damage after ischemia. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.
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Affiliation(s)
- Felicita Pedata
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Viale Pieraccini, 6, 50139 Florence, Italy.
| | - Ilaria Dettori
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Viale Pieraccini, 6, 50139 Florence, Italy
| | - Elisabetta Coppi
- Department of Health Sciences, University of Florence, Viale Pieraccini, 6, 50139 Florence, Italy
| | - Alessia Melani
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Viale Pieraccini, 6, 50139 Florence, Italy
| | - Irene Fusco
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Viale Pieraccini, 6, 50139 Florence, Italy
| | - Renato Corradetti
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Viale Pieraccini, 6, 50139 Florence, Italy
| | - Anna Maria Pugliese
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), University of Florence, Viale Pieraccini, 6, 50139 Florence, Italy
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20
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Borea PA, Varani K, Vincenzi F, Baraldi PG, Tabrizi MA, Merighi S, Gessi S. The A3 adenosine receptor: history and perspectives. Pharmacol Rev 2015; 67:74-102. [PMID: 25387804 DOI: 10.1124/pr.113.008540] [Citation(s) in RCA: 177] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
By general consensus, the omnipresent purine nucleoside adenosine is considered a major regulator of local tissue function, especially when energy supply fails to meet cellular energy demand. Adenosine mediation involves activation of a family of four G protein-coupled adenosine receptors (ARs): A(1), A(2)A, A(2)B, and A(3). The A(3) adenosine receptor (A(3)AR) is the only adenosine subtype to be overexpressed in inflammatory and cancer cells, thus making it a potential target for therapy. Originally isolated as an orphan receptor, A(3)AR presented a twofold nature under different pathophysiologic conditions: it appeared to be protective/harmful under ischemic conditions, pro/anti-inflammatory, and pro/antitumoral depending on the systems investigated. Until recently, the greatest and most intriguing challenge has been to understand whether, and in which cases, selective A(3) agonists or antagonists would be the best choice. Today, the choice has been made and A(3)AR agonists are now under clinical development for some disorders including rheumatoid arthritis, psoriasis, glaucoma, and hepatocellular carcinoma. More specifically, the interest and relevance of these new agents derives from clinical data demonstrating that A(3)AR agonists are both effective and safe. Thus, it will become apparent in the present review that purine scientists do seem to be getting closer to their goal: the incorporation of adenosine ligands into drugs with the ability to save lives and improve human health.
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Affiliation(s)
- Pier Andrea Borea
- Department of Medical Sciences, Pharmacology Section (P.A.B., K.V., F.V., S.M., S.G.), and Department of Pharmaceutical Sciences, University of Ferrara, Italy (P.G.B., M.A.T.)
| | - Katia Varani
- Department of Medical Sciences, Pharmacology Section (P.A.B., K.V., F.V., S.M., S.G.), and Department of Pharmaceutical Sciences, University of Ferrara, Italy (P.G.B., M.A.T.)
| | - Fabrizio Vincenzi
- Department of Medical Sciences, Pharmacology Section (P.A.B., K.V., F.V., S.M., S.G.), and Department of Pharmaceutical Sciences, University of Ferrara, Italy (P.G.B., M.A.T.)
| | - Pier Giovanni Baraldi
- Department of Medical Sciences, Pharmacology Section (P.A.B., K.V., F.V., S.M., S.G.), and Department of Pharmaceutical Sciences, University of Ferrara, Italy (P.G.B., M.A.T.)
| | - Mojgan Aghazadeh Tabrizi
- Department of Medical Sciences, Pharmacology Section (P.A.B., K.V., F.V., S.M., S.G.), and Department of Pharmaceutical Sciences, University of Ferrara, Italy (P.G.B., M.A.T.)
| | - Stefania Merighi
- Department of Medical Sciences, Pharmacology Section (P.A.B., K.V., F.V., S.M., S.G.), and Department of Pharmaceutical Sciences, University of Ferrara, Italy (P.G.B., M.A.T.)
| | - Stefania Gessi
- Department of Medical Sciences, Pharmacology Section (P.A.B., K.V., F.V., S.M., S.G.), and Department of Pharmaceutical Sciences, University of Ferrara, Italy (P.G.B., M.A.T.)
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21
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Chen JF, Lee CF, Chern Y. Adenosine receptor neurobiology: overview. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 119:1-49. [PMID: 25175959 DOI: 10.1016/b978-0-12-801022-8.00001-5] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Adenosine is a naturally occurring nucleoside that is distributed ubiquitously throughout the body as a metabolic intermediary. In the brain, adenosine functions as an important upstream neuromodulator of a broad spectrum of neurotransmitters, receptors, and signaling pathways. By acting through four G-protein-coupled receptors, adenosine contributes critically to homeostasis and neuromodulatory control of a variety of normal and abnormal brain functions, ranging from synaptic plasticity, to cognition, to sleep, to motor activity to neuroinflammation, and cell death. This review begun with an overview of the gene and genome structure and the expression pattern of adenosine receptors (ARs). We feature several new developments over the past decade in our understanding of AR functions in the brain, with special focus on the identification and characterization of canonical and noncanonical signaling pathways of ARs. We provide an update on functional insights from complementary genetic-knockout and pharmacological studies on the AR control of various brain functions. We also highlight several novel and recent developments of AR neurobiology, including (i) recent breakthrough in high resolution of three-dimension structure of adenosine A2A receptors (A2ARs) in several functional status, (ii) receptor-receptor heterodimerization, (iii) AR function in glial cells, and (iv) the druggability of AR. We concluded the review with the contention that these new developments extend and strengthen the support for A1 and A2ARs in brain as therapeutic targets for neurologic and psychiatric diseases.
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Affiliation(s)
- Jiang-Fan Chen
- Department of Neurology, Boston University School of Medicine, Boston, Massachusetts, USA.
| | - Chien-fei Lee
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yijuang Chern
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
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22
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Stoddart LA, Kellam B, Briddon SJ, Hill SJ. Effect of a toggle switch mutation in TM6 of the human adenosine A₃ receptor on Gi protein-dependent signalling and Gi-independent receptor internalization. Br J Pharmacol 2015; 171:3827-44. [PMID: 24750014 PMCID: PMC4128046 DOI: 10.1111/bph.12739] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 04/07/2014] [Accepted: 04/14/2014] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND AND PURPOSE The highly conserved tryptophan (W6.48) in transmembrane domain 6 of GPCRs has been shown to play a central role in forming an active conformation in response to agonist binding. We set out to characterize the effect of this mutation on the efficacy of two agonists at multiple signalling pathways downstream of the adenosine A3 receptor. EXPERIMENTAL APPROACH Residue W6.48 in the human adenosine A3 receptor fused to yellow fluorescent protein was mutated to phenylalanine and expressed in CHO-K1 cells containing a cAMP response element reporter gene. The effects on agonist-mediated receptor internalization were monitored by automated confocal microscopy and image analysis. Further experiments were carried out to investigate agonist-mediated ERK1/2 phosphorylation, inhibition of [3H]-cAMP accumulation and β-arrestin2 binding. KEY RESULTS NECA was able to stimulate agonist-mediated internalization of the W6.48F mutant receptor, while the agonist HEMADO was inactive. Investigation of other downstream signalling pathways indicated that G-protein coupling was impaired for both agonists tested. Mutation of W6.48F therefore resulted in differential effects on agonist efficacy, and introduced signalling pathway bias for HEMADO at the adenosine A3 receptor. CONCLUSIONS AND IMPLICATIONS Investigation of the pharmacology of the W6.48F mutant of the adenosine A3 receptor confirms that this region is important in forming the active conformation of the receptor for stimulating a number of different signalling pathways and that mutations in this residue can lead to changes in agonist efficacy and signalling bias.
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Affiliation(s)
- Leigh A Stoddart
- Institute of Cell Signalling, School of Life Sciences, The University of Nottingham, Nottingham, UK
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23
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Burnstock G, Di Virgilio F. Purinergic signalling and cancer. Purinergic Signal 2014; 9:491-540. [PMID: 23797685 DOI: 10.1007/s11302-013-9372-5] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 06/06/2013] [Indexed: 01/24/2023] Open
Abstract
Receptors for extracellular nucleotides are widely expressed by mammalian cells. They mediate a large array of responses ranging from growth stimulation to apoptosis, from chemotaxis to cell differentiation and from nociception to cytokine release, as well as neurotransmission. Pharma industry is involved in the development and clinical testing of drugs selectively targeting the different P1 nucleoside and P2 nucleotide receptor subtypes. As described in detail in the present review, P2 receptors are expressed by all tumours, in some cases to a very high level. Activation or inhibition of selected P2 receptor subtypes brings about cancer cell death or growth inhibition. The field has been largely neglected by current research in oncology, yet the evidence presented in this review, most of which is based on in vitro studies, although with a limited amount from in vivo experiments and human studies, warrants further efforts to explore the therapeutic potential of purinoceptor targeting in cancer.
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24
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Sheth S, Brito R, Mukherjea D, Rybak LP, Ramkumar V. Adenosine receptors: expression, function and regulation. Int J Mol Sci 2014; 15:2024-52. [PMID: 24477263 PMCID: PMC3958836 DOI: 10.3390/ijms15022024] [Citation(s) in RCA: 255] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 01/15/2014] [Accepted: 01/15/2014] [Indexed: 02/06/2023] Open
Abstract
Adenosine receptors (ARs) comprise a group of G protein-coupled receptors (GPCR) which mediate the physiological actions of adenosine. To date, four AR subtypes have been cloned and identified in different tissues. These receptors have distinct localization, signal transduction pathways and different means of regulation upon exposure to agonists. This review will describe the biochemical characteristics and signaling cascade associated with each receptor and provide insight into how these receptors are regulated in response to agonists. A key property of some of these receptors is their ability to serve as sensors of cellular oxidative stress, which is transmitted by transcription factors, such as nuclear factor (NF)-κB, to regulate the expression of ARs. Recent observations of oligomerization of these receptors into homo- and heterodimers will be discussed. In addition, the importance of these receptors in the regulation of normal and pathological processes such as sleep, the development of cancers and in protection against hearing loss will be examined.
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Affiliation(s)
- Sandeep Sheth
- Department of Pharmacology and Neuroscience, Southern Illinois University School of Medicine, Springfield, IL 62702, USA.
| | - Rafael Brito
- Department of Pharmacology and Neuroscience, Southern Illinois University School of Medicine, Springfield, IL 62702, USA.
| | - Debashree Mukherjea
- Department of Surgery (Otolaryngology), Southern Illinois University School of Medicine, Springfield, IL 62702, USA.
| | - Leonard P Rybak
- Department of Pharmacology and Neuroscience, Southern Illinois University School of Medicine, Springfield, IL 62702, USA.
| | - Vickram Ramkumar
- Department of Pharmacology and Neuroscience, Southern Illinois University School of Medicine, Springfield, IL 62702, USA.
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Nikas JB. Inflammation and immune system activation in aging: a mathematical approach. Sci Rep 2013; 3:3254. [PMID: 24247109 PMCID: PMC3832874 DOI: 10.1038/srep03254] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Accepted: 11/04/2013] [Indexed: 01/07/2023] Open
Abstract
Memory and learning declines are consequences of normal aging. Since those functions are associated with the hippocampus, I analyzed the global gene expression data from post-mortem hippocampal tissue of 25 old (age ≥ 60 yrs) and 15 young (age ≤ 45 yrs) cognitively intact human subjects. By employing a rigorous, multi-method bioinformatic approach, I identified 36 genes that were the most significant in terms of differential expression; and by employing mathematical modeling, I demonstrated that 7 of the 36 genes were able to discriminate between the old and young subjects with high accuracy. Remarkably, 90% of the known genes from those 36 most significant genes are associated with either inflammation or immune system activation. This suggests that chronic inflammation and immune system over-activity may underlie the aging process of the human brain, and that potential anti-inflammatory treatments targeting those genes may slow down this process and alleviate its symptoms.
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Affiliation(s)
- Jason B Nikas
- 1] Department of Neurosurgery, University of Minnesota Medical School, Minneapolis, Minnesota, USA [2] Masonic Cancer Center, University of Minnesota Medical School, Minneapolis, Minnesota, USA
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Cardiovascular adenosine receptors: Expression, actions and interactions. Pharmacol Ther 2013; 140:92-111. [DOI: 10.1016/j.pharmthera.2013.06.002] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 05/28/2013] [Indexed: 12/26/2022]
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Adenosine receptors as potential targets in melanoma. Pharmacol Res 2013; 76:34-40. [DOI: 10.1016/j.phrs.2013.07.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Revised: 07/04/2013] [Accepted: 07/04/2013] [Indexed: 01/24/2023]
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Kozma E, Gizewski ET, Tosh DK, Squarcialupi L, Auchampach JA, Jacobson KA. Characterization by flow cytometry of fluorescent, selective agonist probes of the A(3) adenosine receptor. Biochem Pharmacol 2013; 85:1171-81. [PMID: 23376019 DOI: 10.1016/j.bcp.2013.01.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 01/16/2013] [Accepted: 01/24/2013] [Indexed: 01/02/2023]
Abstract
Various fluorescent nucleoside agonists of the A3 adenosine receptor (AR) were compared as high affinity probes using radioligands and flow cytometry (FCM). They contained a fluorophore linked through the C2 or N(6) position and rigid A3AR-enhancing (N)-methanocarba modification. A hydrophobic C2-(1-pyrenyl) derivative MRS5704 bound nonselectively. C2-Tethered cyanine5-dye labeled MRS5218 bound selectively to hA3AR expressed in whole CHO cells and membranes. By FCM, binding was A3AR-mediated (blocked by A3AR antagonist, at least half through internalization), with t1/2 for association 38min in mA3AR-HEK293 cells; 26.4min in sucrose-treated hA3AR-CHO cells (Kd 31nM). Membrane binding indicated moderate mA3AR affinity, but not selectivity. Specific accumulation of fluorescence (50nM MRS5218) occurred in cells expressing mA3AR, but not other mouse ARs. Evidence was provided suggesting that MRS5218 detects endogenous expression of the A3AR in the human promyelocytic leukemic HL-60 cell line. Therefore, MRS5218 promises to be a useful tool for characterizing the A3AR.
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Affiliation(s)
- Eszter Kozma
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892-0810, USA
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Adenosine Signaling in Glioma Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 986:13-30. [DOI: 10.1007/978-94-007-4719-7_2] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Baraldi PG, Preti D, Borea PA, Varani K. Medicinal Chemistry of A3 Adenosine Receptor Modulators: Pharmacological Activities and Therapeutic Implications. J Med Chem 2012; 55:5676-703. [DOI: 10.1021/jm300087j] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Pier Giovanni Baraldi
- Dipartimento
di Scienze Farmaceutiche and ‡Dipartimento di Medicina Clinica e Sperimentale-Sezione
di Farmacologia, Università di Ferrara, 44121 Ferrara, Italy
| | - Delia Preti
- Dipartimento
di Scienze Farmaceutiche and ‡Dipartimento di Medicina Clinica e Sperimentale-Sezione
di Farmacologia, Università di Ferrara, 44121 Ferrara, Italy
| | - Pier Andrea Borea
- Dipartimento
di Scienze Farmaceutiche and ‡Dipartimento di Medicina Clinica e Sperimentale-Sezione
di Farmacologia, Università di Ferrara, 44121 Ferrara, Italy
| | - Katia Varani
- Dipartimento
di Scienze Farmaceutiche and ‡Dipartimento di Medicina Clinica e Sperimentale-Sezione
di Farmacologia, Università di Ferrara, 44121 Ferrara, Italy
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32
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Cheong SL, Federico S, Venkatesan G, Mandel AL, Shao YM, Moro S, Spalluto G, Pastorin G. The A3 adenosine receptor as multifaceted therapeutic target: pharmacology, medicinal chemistry, and in silico approaches. Med Res Rev 2011; 33:235-335. [PMID: 22095687 DOI: 10.1002/med.20254] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Adenosine is an ubiquitous local modulator that regulates various physiological and pathological functions by stimulating four membrane receptors, namely A(1), A(2A), A(2B), and A(3). Among these G protein-coupled receptors, the A(3) subtype is found mainly in the lung, liver, heart, eyes, and brain in our body. It has been associated with cerebroprotection and cardioprotection, as well as modulation of cellular growth upon its selective activation. On the other hand, its inhibition by selective antagonists has been reported to be potentially useful in the treatment of pathological conditions including glaucoma, inflammatory diseases, and cancer. In this review, we focused on the pharmacology and the therapeutic implications of the human (h)A(3) adenosine receptor (AR), together with an overview on the progress of hA(3) AR agonists, antagonists, allosteric modulators, and radioligands, as well as on the recent advances pertaining to the computational approaches (e.g., quantitative structure-activity relationships, homology modeling, molecular docking, and molecular dynamics simulations) applied to the modeling of hA(3) AR and drug design.
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Affiliation(s)
- Siew Lee Cheong
- Department of Pharmacy, National University of Singapore, 3 Science Drive 2, Singapore 117543, Singapore
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Fishman P, Bar-Yehuda S, Liang BT, Jacobson KA. Pharmacological and therapeutic effects of A3 adenosine receptor agonists. Drug Discov Today 2011; 17:359-66. [PMID: 22033198 DOI: 10.1016/j.drudis.2011.10.007] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/27/2011] [Accepted: 10/12/2011] [Indexed: 10/16/2022]
Abstract
The A(3) adenosine receptor (A(3)AR) coupled to G(i) (inhibitory regulative guanine nucleotide-binding protein) mediates anti-inflammatory, anticancer and anti-ischemic protective effects. The receptor is overexpressed in inflammatory and cancer cells, while low expression is found in normal cells, rendering the A(3)AR as a potential therapeutic target. Highly selective A(3)AR agonists have been synthesized and molecular recognition in the binding site has been characterized. In this article, we summarize preclinical and clinical human studies that demonstrate that A(3)AR agonists induce specific anti-inflammatory and anticancer effects through a molecular mechanism that entails modulation of the Wnt and the NF-κB signal transduction pathways. At present, A(3)AR agonists are being developed for the treatment of inflammatory diseases, including rheumatoid arthritis (RA) and psoriasis; ophthalmic diseases such as dry eye syndrome and glaucoma; liver diseases such as hepatocellular carcinoma and hepatitis.
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Affiliation(s)
- Pnina Fishman
- Can-Fite BioPharma Ltd, Kiryat-Matalon, 10 Bareket St, PO Box 7537, Petah-Tikva 49170, Israel
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Vieira C, Ferreirinha F, Silva I, Duarte-Araújo M, Correia-de-Sá P. Localization and function of adenosine receptor subtypes at the longitudinal muscle--myenteric plexus of the rat ileum. Neurochem Int 2011; 59:1043-55. [PMID: 21924311 DOI: 10.1016/j.neuint.2011.08.016] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2011] [Revised: 08/11/2011] [Accepted: 08/22/2011] [Indexed: 10/17/2022]
Abstract
Adenosine plays a dual role on acetylcholine (ACh) release from myenteric motoneurons via the activation of high-affinity inhibitory A₁ and facilitatory A(2A) receptors. The therapeutic potential of adenosine-related compounds for controlling intestinal motility and inflammation, prompted us to investigate further the role of low-affinity adenosine receptors, A(2B) and A₃, on electrically-evoked (5 Hz, 200 pulses) [³H]ACh release from myenteric neurons. Immunolocalization studies showed that A(2B) receptors exhibit a pattern of distribution similar to the glial cell marker, GFAP. Regarding A₁ and A₃ receptors, they are mainly distributed to cell bodies of ganglionic myenteric neurons, whereas A(2A) receptors are localized predominantly on cholinergic nerve terminals. Using selective antagonists (DPCPX, ZM241385 and MRS1191), data indicate that modulation of evoked [³H]ACh release is balanced through tonic activation of inhibitory (A₁) and facilitatory (A(2A) and A₃) receptors by endogenous adenosine. The selective A(2B) receptor antagonist, PSB603, alone was devoid of effect and failed to modify the inhibitory effect of NECA. The A₃ receptor agonist, 2-Cl-IB MECA (1-10 nM), concentration-dependently increased the release of [³H]ACh. The effect of 2-Cl-IB MECA was attenuated by MRS1191 and by ZM241385, which selectively block respectively A₃ and A(2A) receptors. In contrast to 2-Cl-IB MECA, activation of A(2A) receptors with CGS21680C attenuated nicotinic facilitation of ACh release induced by focal depolarization of myenteric nerve terminals in the presence of tetrodotoxin. Tandem localization of excitatory A₃ and A(2A) receptors along myenteric neurons explains why stimulation of A₃ receptors (with 2-Cl-IB MECA) on nerve cell bodies acts cooperatively with prejunctional facilitatory A(2A) receptors to up-regulate acetylcholine release. The results presented herein consolidate and expand the current understanding of adenosine receptor distribution and function in the myenteric plexus of the rat ileum, and should be taken into consideration for data interpretation regarding the pathophysiological implications of adenosine on intestinal motility disorders.
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Affiliation(s)
- Cátia Vieira
- Laboratório de Farmacologia e Neurobiologia/UMIB, Instituto de Ciências Biomédicas Abel Salazar-Universidade do Porto-ICBAS-UP, Portugal
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Gessi S, Merighi S, Sacchetto V, Simioni C, Borea PA. Adenosine receptors and cancer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1400-12. [DOI: 10.1016/j.bbamem.2010.09.020] [Citation(s) in RCA: 144] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 09/14/2010] [Accepted: 09/20/2010] [Indexed: 01/25/2023]
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Williams-Karnesky RL, Stenzel-Poore MP. Adenosine and stroke: maximizing the therapeutic potential of adenosine as a prophylactic and acute neuroprotectant. Curr Neuropharmacol 2010; 7:217-27. [PMID: 20190963 PMCID: PMC2769005 DOI: 10.2174/157015909789152209] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2009] [Revised: 05/15/2009] [Accepted: 05/18/2009] [Indexed: 12/12/2022] Open
Abstract
Stroke is a leading cause of morbidity and mortality in the United States. Despite intensive research into the development of treatments that lessen the severity of cerebrovascular injury, no major therapies exist. Though the potential use of adenosine as a neuroprotective agent in the context of stroke has long been realized, there are currently no adenosine-based therapies for the treatment of cerebral ischemia and reperfusion. One of the major obstacles to developing adenosine-based therapies for the treatment of stroke is the prevalence of functional adenosine receptors outside the central nervous system. The activities of peripheral immune and vascular endothelial cells are particularly vulnerable to modulation via adenosine receptors. Many of the pathophysiological processes in stroke are a direct result of peripheral immune infiltration into the brain. Ischemic preconditioning, which can be induced by a number of stimuli, has emerged as a promising area of focus in the development of stroke therapeutics. Reprogramming of the brain and immune responses to adenosine signaling may be an underlying principle of tolerance to cerebral ischemia. Insight into the role of adenosine in various preconditioning paradigms may lead to new uses for adenosine as both an acute and prophylactic neuroprotectant.
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Affiliation(s)
- Rebecca L Williams-Karnesky
- Department of Molecular Microbiology and Immunology, Oregon Health and Science University, 3181 Sam Jackson Park Road, Portland, OR 97239, USA.
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37
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Mundell S, Kelly E. Adenosine receptor desensitization and trafficking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:1319-28. [PMID: 20550943 DOI: 10.1016/j.bbamem.2010.06.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 05/28/2010] [Accepted: 06/06/2010] [Indexed: 11/26/2022]
Abstract
As with the majority of G-protein-coupled receptors, all four of the adenosine receptor subtypes are known to undergo agonist-induced regulation in the form of desensitization and trafficking. These processes can limit the ability of adenosine receptors to couple to intracellular signalling pathways and thus reduce the ability of adenosine receptor agonists as well as endogenous adenosine to produce cellular responses. In addition, since adenosine receptors couple to multiple signalling pathways, these pathways may desensitize differentially, while the desensitization of one pathway could even trigger signalling via another. Thus, the overall picture of adenosine receptor regulation can be complex. For all adenosine receptor subtypes, there is evidence to implicate arrestins in agonist-induced desensitization and trafficking, but there is also evidence for other possible forms of regulation, including second messenger-dependent kinase regulation, heterologous effects involving G proteins, and the involvement of non-clathrin trafficking pathways such as caveolae. In this review, the evidence implicating these mechanisms is summarized for each adenosine receptor subtype, and we also discuss those issues of adenosine receptor regulation that remain to be resolved as well as likely directions for future research in this field.
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Affiliation(s)
- Stuart Mundell
- Department of Physiology and Pharmacology, University of Bristol, Bristol, UK
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38
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Yang A, Mucsi AD, Desrosiers MD, Chen JF, Schnermann JB, Blackburn MR, Shi Y. Adenosine mediated desensitization of cAMP signaling enhances T-cell responses. Eur J Immunol 2010; 40:449-59. [PMID: 19950175 PMCID: PMC3468332 DOI: 10.1002/eji.200939586] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adenosine has long been regarded as a crucial anti-inflammatory agent that protects the host from excessive damage. It has been reported to play an important role in suppressing immune activation, particularly that of T cells. However, it is a general observation that induction of T-cell activation is an efficient event despite the high adenosine levels that are often present in the affected host due to injury or stress. We report here that prior to antigenic stimulation via TCR/CD3, exposure of T cells to adenosine desensitizes adenosine receptors, so as to create a window of time where the T cells are insensitive to this ubiquitous suppressor. T cells from mice that were pre-exposed to this manipulation showed stronger responses to antigenic stimulation; therefore, the P1 adenosine receptor desensitization demonstrated an adjuvant-like effect. Our results suggest that adenosine receptor desensitization may be a mechanism for T cells to escape the general suppression during early points of T-cell activation and may emerge as a potential alternative for vaccine adjuvants.
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Affiliation(s)
- Ailian Yang
- Immunology Research Group and Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alta., Canada
| | - Ashley D. Mucsi
- Immunology Research Group and Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alta., Canada
| | - Melanie D. Desrosiers
- Immunology Research Group and Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alta., Canada
| | - Jiang-Fan Chen
- Molecular Neuropharmacology Laboratory, Department of Neurology, Boston University School of Medicine, Boston, MA, USA
| | - Jürgen B. Schnermann
- National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, MA, USA
| | - Michael R. Blackburn
- Department of Biochemistry and Molecular Biology, University of Texas Health Science Center at Houston, Medical School, Houston, TX, USA
| | - Yan Shi
- Immunology Research Group and Department of Microbiology and Infectious Diseases, University of Calgary, Calgary, Alta., Canada
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Abstract
The study of the A(3) adenosine receptor (A(3)AR) represents a rapidly growing and intense area of research in the adenosine field. The present chapter will provide an overview of the expression patterns, molecular pharmacology and functional role of this A(3)AR subtype under pathophysiological conditions. Through studies utilizing selective A(3)AR agonists and antagonists, or A(3)AR knockout mice, it is now clear that this receptor plays a critical role in the modulation of ischemic diseases as well as in inflammatory and autoimmune pathologies. Therefore, the potential therapeutic use of agonists and antagonists will also be described. The discussion will principally address the use of such compounds in the treatment of brain and heart ischemia, asthma, sepsis and glaucoma. The final part concentrates on the molecular basis of A(3)ARs in autoimmune diseases such as rheumatoid arthritis, and includes a description of clinical trials with the selective agonist CF101. Based on this chapter, it is evident that continued research to discover agonists and antagonists for the A(3)AR subtype is warranted.
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40
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Aguiari G, Varani K, Bogo M, Mangolini A, Vincenzi F, Durante C, Gessi S, Sacchetto V, Catizone L, Harris P, Rizzuto R, Borea PA, Del Senno L. Deficiency of polycystic kidney disease-1 gene (PKD1) expression increases A(3) adenosine receptors in human renal cells: implications for cAMP-dependent signalling and proliferation of PKD1-mutated cystic cells. Biochim Biophys Acta Mol Basis Dis 2009; 1792:531-40. [PMID: 19285554 DOI: 10.1016/j.bbadis.2009.03.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 02/27/2009] [Accepted: 03/03/2009] [Indexed: 11/28/2022]
Abstract
Cyst growth and expansion in autosomal dominant polycystic kidney disease (ADPKD) has been attributed to numerous factors, including ATP, cAMP and adenosine signalling. Although the role of ATP and cAMP has been widely investigated in PKD1-deficient cells, no information is currently available on adenosine-mediated signalling. Here we investigate for the first time the impact of abnormalities of polycystin-1 (PC1) on the expression and functional activity of adenosine receptors, members of the G-protein-coupled receptor superfamily. Pharmacological, molecular and biochemical findings show that a siRNA-dependent PC1-depletion in HEK293 cells and a PKD1-nonsense mutation in cyst-derived cell lines result in increased expression of the A(3) adenosine receptor via an NFkB-dependent mechanism. Interestingly, A(3) adenosine receptor levels result higher in ADPKD than in normal renal tissues. Furthermore, the stimulation of this receptor subtype with the selective agonist Cl-IB-MECA causes a reduction in both cytosolic cAMP and cell proliferation in both PC1-deficient HEK293 cells and cystic cells. This reduction is associated with increased expression of p21(waf) and reduced activation not only of ERK1/2, but also of S6 kinase, the main target of mTOR signalling. In the light of these findings, the ability of Cl-IB-MECA to reduce disease progression in ADPKD should be further investigated. Moreover, our results suggest that NFkB, which is markedly activated in PC1-deficient and cystic cells, plays an important role in modulating A(3)AR expression in cystic cells.
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Affiliation(s)
- Gianluca Aguiari
- Department of Biochemistry and Molecular Biology, Section of Molecular Biology, University of Ferrara, Italy
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41
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Flach TL, Pang W, Chau EMT, Desrosiers MD, Shi Y. Adenosine primes resting stage dendritic cells before their activation. Biochem Biophys Res Commun 2009; 380:748-51. [PMID: 19338746 DOI: 10.1016/j.bbrc.2009.01.114] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2009] [Accepted: 01/19/2009] [Indexed: 02/03/2023]
Abstract
The effect of adenosine mediated suppression of immune cell activation has long been an important topic of study. While the protective benefits of such a signaling mechanism are well recognized, there remains a question as to how dendritic cells (DCs) bypass the high levels of adenosine during tissue stress and infection, and become fully activated. We report here that adenosine receptors on resting stage DCs, both in vivo and in vitro, are functionally desensitized after ligand binding. This desensitization lasts several hours during which DCs are "blind" to adenosine and are stimulated without this negative feedback. This effect is mediated by cAMP signaling. Our report suggests that there is a specific regulatory mechanism used by DCs to overcome adenosine mediated inhibition to become fully activated despite a general suppressive state.
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Affiliation(s)
- Tracy L Flach
- Immunology Research Group & Department of Microbiology and Infectious Diseases, 4A18 HRIC, 3330 Hospital Dr. NW, University of Calgary, Calgary, Alberta, Canada T2N 4N1
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42
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Fishman P, Bar-Yehuda S, Synowitz M, Powell JD, Klotz KN, Gessi S, Borea PA. Adenosine receptors and cancer. Handb Exp Pharmacol 2009:399-441. [PMID: 19639290 PMCID: PMC3598010 DOI: 10.1007/978-3-540-89615-9_14] [Citation(s) in RCA: 105] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
The A(1), A(2A), A(2B) and A(3) G-protein-coupled cell surface adenosine receptors (ARs) are found to be upregulated in various tumor cells. Activation of the receptors by specific ligands, agonists or antagonists, modulates tumor growth via a range of signaling pathways. The A(1)AR was found to play a role in preventing the development of glioblastomas. This antitumor effect of the A(1)AR is mediated via tumor-associated microglial cells. Activation of the A(2A)AR results in inhibition of the immune response to tumors via suppression of T regulatory cell function and inhibition of natural killer cell cytotoxicity and tumor-specific CD4+/CD8+ activity. Therefore, it is suggested that pharmacological inhibition of A(2A)AR activation by specific antagonists may enhance immunotherapeutics in cancer therapy. Activation of the A(2B)AR plays a role in the development of tumors via upregulation of the expression levels of angiogenic factors in microvascular endothelial cells. In contrast, it was evident that activation of A(2B)AR results in inhibition of ERK1/2 phosphorylation and MAP kinase activity, which are involved in tumor cell growth signals. Finally, A(3)AR was found to be highly expressed in tumor cells and tissues while low expression levels were noted in normal cells or adjacent tissue. Receptor expression in the tumor tissues was directly correlated to disease severity. The high receptor expression in the tumors was attributed to overexpression of NF-kappaB, known to act as an A(3)AR transcription factor. Interestingly, high A(3)AR expression levels were found in peripheral blood mononuclear cells (PBMCs) derived from tumor-bearing animals and cancer patients, reflecting receptor status in the tumors. A(3)AR agonists were found to induce tumor growth inhibition, both in vitro and in vivo, via modulation of the Wnt and the NF-kappaB signaling pathways. Taken together, A(3)ARs that are abundantly expressed in tumor cells may be targeted by specific A(3)AR agonists, leading to tumor growth inhibition. The unique characteristics of these A(3)AR agonists make them attractive as drug candidates.
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Affiliation(s)
- P Fishman
- Can-Fite BioPharma, Kiryat Matalon, Petach Tikva, 49170, Israel.
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43
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Tonazzini I, Trincavelli ML, Montali M, Martini C. Regulation of A1 adenosine receptor functioning induced by P2Y1 purinergic receptor activation in human astroglial cells. J Neurosci Res 2008; 86:2857-66. [PMID: 18500760 DOI: 10.1002/jnr.21727] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In the rat brain, a heteromeric association between adenosine A(1) and purinergic P2Y(1) receptors has been demonstrated. It is suggested that this association plays an important role in the control of purine-mediated responses during pathophysiological conditions. Recently, we have demonstrated that these receptors colocalize on glutamatergic synaptic and astroglial membranes in rat hippocampus and reciprocally interact, thus modulating their functional responses at the G protein coupling level. In the present work, by means of immunoprecipitation studies, we demonstrated that A(1) and P2Y(1) receptors are present in human astroglial cells (ADF) and aggregate to form a multimeric complex. P2Y(1) receptor activation by its agonist, 2-methylthio-adenosine 5'-diphosphate (MeSADP), induced a time-dependent reduction in agonist-mediated A(1) receptor functional responses, causing a drop in A(1) receptor agonist potency to promote receptor-G protein coupling and to inhibit the adenylate cyclase pathway. These effects appeared to be selectively mediated by P2Y(1) receptor activation and probably occurred as a consequence of a direct receptor-receptor interaction at the plasma membrane level. These results indicated that P2Y(1) receptor activation induces A(1) receptor heterologous desensitization. The interaction between A(1) and P2Y(1) receptors may play an important role in the purinergic signaling cascade in astrocytes, which are involved in cell-to-cell communication and in control of synaptic transmission, particularly during pathological conditions, when large amounts of purines are released.
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Affiliation(s)
- I Tonazzini
- Department of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, Pisa, Italy
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44
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Trincavelli ML, Tonazzini I, Montali M, Abbracchio MP, Martini C. Short-term TNF-Alpha treatment induced A2B adenosine receptor desensitization in human astroglial cells. J Cell Biochem 2008; 104:150-61. [PMID: 18004767 DOI: 10.1002/jcb.21611] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Long-term glial cell treatment with the proinflammatory cytokine TNF-alpha has been demonstrated to increase the functional responsiveness of A(2B) adenosine receptors (A(2B) ARs), which in turn synergize with the cytokine inducing chronic astrogliosis. In the present study, we investigated the short-term effects of TNF-alpha on A(2B) AR functional responses in human astroglial cells (ADF), thus simulating the acute phase of cerebral damage which is characterized by both cytokine and adenosine high level release. Short-term TNF-alpha cell treatment caused A(2B) AR phosphorylation inducing, in turn, impairment in A(2B) AR-G protein coupling and cAMP production. These effects occurred in a time-dependent manner with a maximum following 3-h cell exposure. Moreover, we showed PKC intracellular kinase is mainly involved in the TNF-alpha-mediated regulation of A(2B) AR functional responses. The results may indicate the A(2B) AR functional impairment as a cell defense mechanism to counteract the A(2B) receptor-mediated effects during the acute phase of brain damage, underlying A(2B) AR as a target to modulate early inflammatory responses.
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Affiliation(s)
- Maria Letizia Trincavelli
- Department of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, Pisa, Italy
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Di Sole F, Cerull R, Babich V, Casavola V, Helmle-Roth C, Burckhardt G. Short- and long-term A3 adenosine receptor activation inhibits the Na+/H+ exchanger NHE3 activity and expression in opossum kidney cells. J Cell Physiol 2008; 216:221-33. [PMID: 18286509 DOI: 10.1002/jcp.21399] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The renal function of the A(3) adenosine receptor (A3AR) is poorly characterized. In this study, we report that the A3AR-selective agonist, 1-[2-chloro-6-[[(3-iodophenyl)methyl]amino]-9H-purine-9-yl]-1-deoxy-N-methyl-b-D-ribofuranuronamide (2-Cl-IBMECA) regulates the Na+/H+ exchanger-3 (NHE3) in a dose- and time-dependent fashion. In opossum kidney (OK) cells, 2-Cl-IBMECA at high (10(-6) M) and low (10(-8) M) dose inhibits NHE3 by a multiphasic time course with an acute phase of NHE3 inhibition from 15 min to 1 h, followed by a chronic phase of NHE3 inhibition from 24 to 48 h. Pre-incubation with either the selective A3AR-antagonist MRS1523 (10(-7) M) or the protein kinase C inhibitor, Calphostin C (10(-8) M) completely blocked 10(-6) M 2-Cl-IBMECA-induced acute (15 min) and chronic (24 h) phases of NHE3 inhibition. In contrast, the acute inhibitory phase (15 min) of 10(-8) M 2-Cl-IBMECA was completely prevented only when Calphostin C (10(-8) M) was added in conjunction with the protein kinase A inhibitor, H89 (10(-7) M). Acute (15 or 30 min depending on the A3AR-agonist concentration) A3AR-dependent inhibition of NHE3 activity was accompanied by decrease in cell surface NHE3 protein with no change in total NHE3 antigen. Chronic (24 h) A3AR-mediated down-regulation of NHE3 was associated with reduction of surface NHE3, decreased total NHE3 protein (70%) and a paradoxical rise of NHE3 RNA (40%). In summary, these results indicate that A3AR directly regulates NHE3 at multiple levels in a complex pattern. A3AR-dependent short- and long-term inhibition of NHE3 may be a fundamental mechanism of net sodium and fluid balance.
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Affiliation(s)
- Francesca Di Sole
- Department of Physiology and Pathophysiology, University of Göttingen, Göttingen, Germany.
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Translocation of arrestin induced by human A(3) adenosine receptor ligands in an engineered cell line: comparison with G protein-dependent pathways. Pharmacol Res 2008; 57:303-11. [PMID: 18424164 DOI: 10.1016/j.phrs.2008.02.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 02/29/2008] [Accepted: 02/29/2008] [Indexed: 11/23/2022]
Abstract
Structurally diverse ligands were studied in A(3) adenosine receptor (AR)-mediated beta-arrestin translocation in engineered CHO cells. The agonist potency and efficacy were similar, although not identical, to their G protein signaling. However, differences have also been found. MRS542, MRS1760, and other adenosine derivatives, A(3)AR antagonists in cyclic AMP assays, were partial agonists in beta-arrestin translocation, indicating possible biased agonism. The xanthine 7-riboside DBXRM, a full agonist, was only partially efficacious in beta-arrestin translocation. DBXRM was shown to induce a lesser extent of desensitization compared with IB-MECA. In kinetic studies, MRS3558, a potent and selective A(3)AR agonist, induced beta-arrestin translocation significantly faster than IB-MECA and Cl-IB-MECA. Non-nucleoside antagonists showed similar inhibitory potencies as previously reported. PTX pretreatment completely abolished ERK1/2 activation, but not arrestin translocation. Thus, lead candidates for biased agonists at the A(3)AR have been identified with this arrestin-translocation assay, which promises to be an effective tool for ligand screening.
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Internalization and desensitization of adenosine receptors. Purinergic Signal 2007; 4:21-37. [PMID: 18368531 PMCID: PMC2245999 DOI: 10.1007/s11302-007-9086-7] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Accepted: 10/02/2007] [Indexed: 01/28/2023] Open
Abstract
Until now, more than 800 distinct G protein-coupled receptors (GPCRs) have been identified in the human genome. The four subtypes of the adenosine receptor (A1, A2A, A2B and A3 receptor) belong to this large family of GPCRs that represent the most widely targeted pharmacological protein class. Since adenosine receptors are widespread throughout the body and involved in a variety of physiological processes and diseases, there is great interest in understanding how the different subtypes are regulated, as a basis for designing therapeutic drugs that either avoid or make use of this regulation. The major GPCR regulatory pathway involves phosphorylation of activated receptors by G protein-coupled receptor kinases (GRKs), a process that is followed by binding of arrestin proteins. This prevents receptors from activating downstream heterotrimeric G protein pathways, but at the same time allows activation of arrestin-dependent signalling pathways. Upon agonist treatment, adenosine receptor subtypes are differently regulated. For instance, the A1Rs are not (readily) phosphorylated and internalize slowly, showing a typical half-life of several hours, whereas the A2AR and A2BR undergo much faster downregulation, usually shorter than 1 h. The A3R is subject to even faster downregulation, often a matter of minutes. The fast desensitization of the A3R after agonist exposure may be therapeutically equivalent to antagonist occupancy of the receptor. This review describes the process of desensitization and internalization of the different adenosine subtypes in cell systems, tissues and in vivo studies. In addition, molecular mechanisms involved in adenosine receptor desensitization are discussed.
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The role of ATP and adenosine in the brain under normoxic and ischemic conditions. Purinergic Signal 2007; 3:299-310. [PMID: 18404443 PMCID: PMC2072927 DOI: 10.1007/s11302-007-9085-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 09/25/2007] [Indexed: 01/01/2023] Open
Abstract
By taking advantage of some recently synthesized compounds that are able to block ecto-ATPase activity, we demonstrated that adenosine triphosphate (ATP) in the hippocampus exerts an inhibitory action independent of its degradation to adenosine. In addition, tonic activation of P2 receptors contributes to the normally recorded excitatory neurotransmission. The role of P2 receptors becomes critical during ischemia when extracellular ATP concentrations increase. Under such conditions, P2 antagonism is protective. Although ATP exerts a detrimental role under ischemia, it also exerts a trophic role in terms of cell division and differentiation. We recently reported that ATP is spontaneously released from human mesenchymal stem cells (hMSCs) in culture. Moreover, it decreases hMSC proliferation rate at early stages of culture. Increased hMSC differentiation could account for an ATP-induced decrease in cell proliferation. ATP as a homeostatic regulator might exert a different effect on cell trophism according to the rate of its efflux and receptor expression during the cell life cycle. During ischemia, adenosine formed by intracellular ATP escapes from cells through the equilibrative transporter. The protective role of adenosine A(1) receptors during ischemia is well accepted. However, the use of selective A(1) agonists is hampered by unwanted peripheral effects, thus attention has been focused on A(2A) and A(3) receptors. The protective effects of A(2A) antagonists in brain ischemia may be largely due to reduced glutamate outflow from neurones and glial cells. Reduced activation of p38 mitogen-activated protein kinases that are involved in neuronal death through transcriptional mechanisms may also contribute to protection by A(2A) antagonism. Evidence that A(3) receptor antagonism may be protective after ischemia is also reported.
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Gessi S, Merighi S, Varani K, Leung E, Mac Lennan S, Borea PA. The A3 adenosine receptor: an enigmatic player in cell biology. Pharmacol Ther 2007; 117:123-40. [PMID: 18029023 DOI: 10.1016/j.pharmthera.2007.09.002] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2007] [Accepted: 09/05/2007] [Indexed: 02/01/2023]
Abstract
Adenosine is a primordial signaling molecule present in every cell of the human body that mediates its physiological functions by interacting with 4 subtypes of G-protein-coupled receptors, termed A1, A2A, A2B and A3. The A3 subtype is perhaps the most enigmatic among adenosine receptors since, although several studies have been performed in the years to elucidate its physiological function, it still presents in several cases a double nature in different pathophysiological conditions. The 2 personalities of A3 often come into direct conflict, e.g., in ischemia, inflammation and cancer, rendering this receptor as a single entity behaving in 2 different ways. This review focuses on the most relevant aspects of A3 adenosine subtype activation and summarizes the pharmacological evidence as the basis of the dichotomy of this receptor in different therapeutic fields. Although much is still to be learned about the function of the A3 receptor and in spite of its duality, at the present time it can be speculated that A3 receptor selective ligands might show utility in the treatment of ischemic conditions, glaucoma, asthma, arthritis, cancer and other disorders in which inflammation is a feature. The biggest and most intriguing challenge for the future is therefore to understand whether and where selective A3 agonists or antagonists are the best choice.
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Affiliation(s)
- Stefania Gessi
- Department of Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, Ferrara, Italy
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Fishman P, Jacobson K, Ochaion A, Cohen S, Bar-Yehuda S. The Anti-Cancer Effect of A 3 Adenosine Receptor Agonists: A Novel, Targeted Therapy. IMMUNOLOGY, ENDOCRINE & METABOLIC AGENTS IN MEDICINAL CHEMISTRY 2007; 7:298-303. [PMID: 34824647 PMCID: PMC8611655 DOI: 10.2174/187152207781369878] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The A3 adenosine receptor (A3AR) is highly expressed in various human solid tumor cells whereas low expression is found in the adjacent normal tissues. Activation of the A3AR with synthetic highly selective agonists, such as IB-MECA, Cl-IB-MECA or LJ529, induces tumor growth inhibition of melanoma, lymphoma, breast, hepatoma, prostate and colon carcinoma cells both in vitro and in vivo. Two molecular events take place upon receptor activation and include: a. receptor internalization and subsequent degradation, followed by decreased receptor mRNA and protein expression level. b. modulation of down-stream signal transduction pathways, including those related to Wnt and NF-κB. Subsequently, the levels of cyclin D1 and c-Myc are decreased leading to tumor growth inhibition. IB-MECA synergizes with chemotherapeutic agents to yield an additive anti-tumor effect and protects against myelotoxicity induced by chemotherapy. Taken together, A3AR agonists may be suggested as a new family of orally bioavailable compounds to be developed as potent inhibitors of malignant diseases.
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Affiliation(s)
- P. Fishman
- Can-Fite BioPharma Ltd., Kiryat-Matalon, Petah -Tikva, 49170, Israel
| | - K.A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - A. Ochaion
- Can-Fite BioPharma Ltd., Kiryat-Matalon, Petah -Tikva, 49170, Israel
| | - S. Cohen
- Can-Fite BioPharma Ltd., Kiryat-Matalon, Petah -Tikva, 49170, Israel
| | - S. Bar-Yehuda
- Can-Fite BioPharma Ltd., Kiryat-Matalon, Petah -Tikva, 49170, Israel
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