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Boncler M, Bartczak K, Rozalski M. Potential for modulation of platelet function via adenosine receptors during inflammation. Br J Pharmacol 2024; 181:547-563. [PMID: 37218380 DOI: 10.1111/bph.16146] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 03/15/2023] [Accepted: 05/15/2023] [Indexed: 05/24/2023] Open
Abstract
Traditionally, platelets are known to play an important role in haemostasis and thrombosis; however, they serve also as important modulators of inflammation and immunity. Platelets secrete adhesion molecules and cytokines, interact with leukocytes and endothelium, and express toll-like receptors involved in a direct interaction with pathogens. Platelets express A2A and A2B subtypes of receptors for adenosine. The activation of these receptors leads to an increase in cAMP concentration in the cytoplasm, thereby resulting in inhibited secretion of pro-inflammatory mediators and reduced cell activation. Therefore, platelet adenosine receptors could be a potential target for inhibiting platelet activation and thus down-regulating inflammation or immunity. The biological effects of adenosine are short-lasting, because the compound is rapidly metabolized; hence, its lability has triggered efforts to synthesize new, longer-lasting adenosine analogues. In this article, we have reviewed the literature regarding the pharmacological potential of adenosine and other agonists of A2A and A2B receptors to affect platelet function during inflammation. LINKED ARTICLES: This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.
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Affiliation(s)
- Magdalena Boncler
- Department of Haemostasis and Haemostatic Disorders, Chair of Biomedical Sciences, Medical University of Lodz, Lodz, Poland
| | - Kinga Bartczak
- Department of Haemostasis and Haemostatic Disorders, Chair of Biomedical Sciences, Medical University of Lodz, Lodz, Poland
| | - Marcin Rozalski
- Department of Haemostasis and Haemostatic Disorders, Chair of Biomedical Sciences, Medical University of Lodz, Lodz, Poland
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2
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Nucleoside transporters and immunosuppressive adenosine signaling in the tumor microenvironment: Potential therapeutic opportunities. Pharmacol Ther 2022; 240:108300. [PMID: 36283452 DOI: 10.1016/j.pharmthera.2022.108300] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/30/2022]
Abstract
Adenosine compartmentalization has a profound impact on immune cell function by regulating adenosine localization and, therefore, extracellular signaling capabilities, which suppresses immune cell function in the tumor microenvironment. Nucleoside transporters, responsible for the translocation and cellular compartmentalization of hydrophilic adenosine, represent an understudied yet crucial component of adenosine disposition in the tumor microenvironment. In this review article, we will summarize what is known regarding nucleoside transporter's function within the purinome in relation to currently devised points of intervention (i.e., ectonucleotidases, adenosine receptors) for cancer immunotherapy, alterations in nucleoside transporter expression reported in cancer, and potential avenues for targeting of nucleoside transporters for the desired modulation of adenosine compartmentalization and action. Further, we put forward that nucleoside transporters are an unexplored therapeutic opportunity, and modulation of nucleoside transport processes could attenuate the pathogenic buildup of immunosuppressive adenosine in solid tumors, particularly those enriched with nucleoside transport proteins.
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Shepherd C, Robinson S, Berizzi A, Thompson LEJ, Bird L, Culurgioni S, Varzandeh S, Rawlins PB, Olsen RHJ, Navratilova IH. Surface Plasmon Resonance Screening to Identify Active and Selective Adenosine Receptor Binding Fragments. ACS Med Chem Lett 2022; 13:1172-1181. [DOI: 10.1021/acsmedchemlett.2c00099] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Claire Shepherd
- University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
- Kinetic Discovery Ltd., The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
| | - Sean Robinson
- Exscientia plc, The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
| | - Alice Berizzi
- Exscientia plc, The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
| | - Laura E. J. Thompson
- Exscientia plc, The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
| | - Louise Bird
- Kinetic Discovery Ltd., The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
- Exscientia plc, The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
| | - Simone Culurgioni
- Kinetic Discovery Ltd., The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
- Exscientia plc, The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
| | - Simon Varzandeh
- Exscientia plc, The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
| | - Philip B. Rawlins
- Discovery Sciences, R&D, AstraZeneca, Cambridge CB4 0WG, United Kingdom
| | - Reid H. J. Olsen
- Exscientia plc, The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
| | - Iva Hopkins Navratilova
- University of Dundee, Dow Street, Dundee DD1 5EH, United Kingdom
- Kinetic Discovery Ltd., The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
- Exscientia plc, The Schrödinger
Building, Heatley Road, The Oxford Science Park, Oxford OX4 4GE, United Kingdom
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4
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Gündel D, Toussaint M, Lai TH, Deuther-Conrad W, Cumming P, Schröder S, Teodoro R, Moldovan RP, Pan-Montojo F, Sattler B, Kopka K, Sabri O, Brust P. Quantitation of the A2A Adenosine Receptor Density in the Striatum of Mice and Pigs with [18F]FLUDA by Positron Emission Tomography. Pharmaceuticals (Basel) 2022; 15:ph15050516. [PMID: 35631343 PMCID: PMC9146919 DOI: 10.3390/ph15050516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 04/14/2022] [Accepted: 04/19/2022] [Indexed: 12/10/2022] Open
Abstract
The cerebral expression of the A2A adenosine receptor (A2AAR) is altered in neurodegenerative diseases such as Parkinson’s (PD) and Huntington’s (HD) diseases, making these receptors an attractive diagnostic and therapeutic target. We aimed to further investigate the pharmacokinetic properties in the brain of our recently developed A2AAR–specific antagonist radiotracer [18F]FLUDA. For this purpose, we retrospectively analysed dynamic PET studies of healthy mice and rotenone–treated mice, and conducted dynamic PET studies with healthy pigs. We performed analysis of mouse brain time–activity curves to calculate the mean residence time (MRT) by non–compartmental analysis, and the binding potential (BPND) of [18F]FLUDA using the simplified reference tissue model (SRTM). For the pig studies, we performed a Logan graphical analysis to calculate the radiotracer distribution volume (VT) at baseline and under blocking conditions with tozadenant. The MRT of [18F]FLUDA in the striatum of mice was decreased by 30% after treatment with the A2AAR antagonist istradefylline. Mouse results showed the highest BPND (3.9 to 5.9) in the striatum. SRTM analysis showed a 20% lower A2AAR availability in the rotenone–treated mice compared to the control–aged group. Tozadenant treatment significantly decreased the VT (14.6 vs. 8.5 mL · g−1) and BPND values (1.3 vs. 0.3) in pig striatum. This study confirms the target specificity and a high BPND of [18F]FLUDA in the striatum. We conclude that [18F]FLUDA is a suitable tool for the non–invasive quantitation of altered A2AAR expression in neurodegenerative diseases such as PD and HD, by PET.
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Affiliation(s)
- Daniel Gündel
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- Correspondence: ; Tel.: +49-341-234179-4615
| | - Magali Toussaint
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
| | - Thu Hang Lai
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- Department of Research and Development, ROTOP Pharmaka Ltd., 01328 Dresden, Germany;
| | - Winnie Deuther-Conrad
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
| | - Paul Cumming
- Department of Nuclear Medicine, Bern University Hospital, 3010 Bern, Switzerland;
- School of Psychology and Counselling, Queensland University of Technology, Brisbane 4000, Australia
| | - Susann Schröder
- Department of Research and Development, ROTOP Pharmaka Ltd., 01328 Dresden, Germany;
| | - Rodrigo Teodoro
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- Department of Research and Development, Life Molecular Imaging GmbH, 13353 Berlin, Germany
| | - Rareş-Petru Moldovan
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
| | - Francisco Pan-Montojo
- Department of Psychiatry, University Hospital Munich, Ludwig–Maximilians–Universität (LMU) Munich, 80336 Munich, Germany;
- Department of Neurology, University Hospital Munich, Ludwig–Maximilians–Universität (LMU) Munich, 81377 Munich, Germany
| | - Bernhard Sattler
- Department for Nuclear Medicine, University Hospital Leipzig, 04103 Leipzig, Germany; (B.S.); (O.S.)
| | - Klaus Kopka
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- Faculty of Chemistry and Food Chemistry, School of Science, TU Dresden, 01069 Dresden, Germany
| | - Osama Sabri
- Department for Nuclear Medicine, University Hospital Leipzig, 04103 Leipzig, Germany; (B.S.); (O.S.)
| | - Peter Brust
- Department of Neuroradiopharmaceuticals, Institute of Radiopharmaceutical Cancer Research, Helmholtz–Zentrum Dresden–Rossendorf, 04308 Leipzig, Germany; (M.T.); (T.H.L.); (W.D.-C.); (R.T.); (R.-P.M.); (K.K.); (P.B.)
- The Lübeck Institute of Experimental Dermatology, University Medical Center Schleswig–Holstein, 23562 Lübeck, Germany
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5
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Cooper SL, Wragg ES, Pannucci P, Soave M, Hill SJ, Woolard J. Regionally selective cardiovascular responses to adenosine A 2A and A 2B receptor activation. FASEB J 2022; 36:e22214. [PMID: 35230706 PMCID: PMC9415116 DOI: 10.1096/fj.202101945r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/31/2022] [Accepted: 02/07/2022] [Indexed: 11/25/2022]
Abstract
Adenosine is a local mediator that regulates changes in the cardiovascular system via activation of four G protein-coupled receptors (A1 , A2A , A2B , A3 ). Here, we have investigated the effect of A2A and A2B -selective agonists on vasodilatation in three distinct vascular beds of the rat cardiovascular system. NanoBRET ligand binding studies were used to confirm receptor selectivity. The regional hemodynamic effects of adenosine A2A and A2B selective agonists were investigated in conscious rats. Male Sprague-Dawley rats (350-450 g) were chronically implanted with pulsed Doppler flow probes on the renal artery, mesenteric artery, and the descending abdominal aorta. Cardiovascular responses were measured following intravenous infusion (3 min for each dose) of the A2A -selective agonist CGS 21680 (0.1, 0.3, 1 µg kg-1 min-1 ) or the A2B -selective agonist BAY 60-6583 (4,13.3, 40 µg kg-1 min-1 ) following predosing with the A2A -selective antagonist SCH 58261 (0.1 or 1 mg kg-1 min-1 ), the A2B /A2A antagonist PSB 1115 (10 mg kg-1 min-1 ) or vehicle. The A2A -selective agonist CGS 21680 produced a striking increase in heart rate (HR) and hindquarters vascular conductance (VC) that was accompanied by a significant decrease in mean arterial pressure (MAP) in conscious rats. In marked contrast, the A2B -selective agonist BAY 60-6583 significantly increased HR and VC in the renal and mesenteric vascular beds, but not in the hindquarters. Taken together, these data indicate that A2A and A2B receptors are regionally selective in their regulation of vascular tone. These results suggest that the development of A2B receptor agonists to induce vasodilatation in the kidney may provide a good therapeutic approach for the treatment of acute kidney injury.
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Affiliation(s)
- Samantha L. Cooper
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamNottinghamUK,Centre of Membrane Proteins and ReceptorsUniversity of Birmingham and University of NottinghamMidlandsUK
| | - Edward S. Wragg
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamNottinghamUK,Centre of Membrane Proteins and ReceptorsUniversity of Birmingham and University of NottinghamMidlandsUK
| | - Patrizia Pannucci
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamNottinghamUK,Centre of Membrane Proteins and ReceptorsUniversity of Birmingham and University of NottinghamMidlandsUK
| | - Mark Soave
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamNottinghamUK,Centre of Membrane Proteins and ReceptorsUniversity of Birmingham and University of NottinghamMidlandsUK
| | - Stephen J. Hill
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamNottinghamUK,Centre of Membrane Proteins and ReceptorsUniversity of Birmingham and University of NottinghamMidlandsUK
| | - Jeanette Woolard
- Division of Physiology, Pharmacology and NeuroscienceSchool of Life SciencesUniversity of NottinghamNottinghamUK,Centre of Membrane Proteins and ReceptorsUniversity of Birmingham and University of NottinghamMidlandsUK
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6
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IJzerman AP, Jacobson KA, Müller CE, Cronstein BN, Cunha RA. International Union of Basic and Clinical Pharmacology. CXII: Adenosine Receptors: A Further Update. Pharmacol Rev 2022; 74:340-372. [PMID: 35302044 PMCID: PMC8973513 DOI: 10.1124/pharmrev.121.000445] [Citation(s) in RCA: 70] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Our previous International Union of Basic and Clinical Pharmacology report on the nomenclature and classification of adenosine receptors (2011) contained a number of emerging developments with respect to this G protein-coupled receptor subfamily, including protein structure, protein oligomerization, protein diversity, and allosteric modulation by small molecules. Since then, a wealth of new data and results has been added, allowing us to explore novel concepts such as target binding kinetics and biased signaling of adenosine receptors, to examine a multitude of receptor structures and novel ligands, to gauge new pharmacology, and to evaluate clinical trials with adenosine receptor ligands. This review should therefore be considered a further update of our previous reports from 2001 and 2011. SIGNIFICANCE STATEMENT: Adenosine receptors (ARs) are of continuing interest for future treatment of chronic and acute disease conditions, including inflammatory diseases, neurodegenerative afflictions, and cancer. The design of AR agonists ("biased" or not) and antagonists is largely structure based now, thanks to the tremendous progress in AR structural biology. The A2A- and A2BAR appear to modulate the immune response in tumor biology. Many clinical trials for this indication are ongoing, whereas an A2AAR antagonist (istradefylline) has been approved as an anti-Parkinson agent.
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Affiliation(s)
- Adriaan P IJzerman
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands (A.P.IJ.); National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Molecular Recognition Section, Bethesda, Maryland (K.A.J.); Universität Bonn, Bonn, Germany (C.E.M.); New York University School of Medicine, New York, New York (B.N.C.); and Center for Neurosciences and Cell Biology and Faculty of Medicine, University of Coimbra, Coimbra, Portugal (R.A.C.)
| | - Kenneth A Jacobson
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands (A.P.IJ.); National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Molecular Recognition Section, Bethesda, Maryland (K.A.J.); Universität Bonn, Bonn, Germany (C.E.M.); New York University School of Medicine, New York, New York (B.N.C.); and Center for Neurosciences and Cell Biology and Faculty of Medicine, University of Coimbra, Coimbra, Portugal (R.A.C.)
| | - Christa E Müller
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands (A.P.IJ.); National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Molecular Recognition Section, Bethesda, Maryland (K.A.J.); Universität Bonn, Bonn, Germany (C.E.M.); New York University School of Medicine, New York, New York (B.N.C.); and Center for Neurosciences and Cell Biology and Faculty of Medicine, University of Coimbra, Coimbra, Portugal (R.A.C.)
| | - Bruce N Cronstein
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands (A.P.IJ.); National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Molecular Recognition Section, Bethesda, Maryland (K.A.J.); Universität Bonn, Bonn, Germany (C.E.M.); New York University School of Medicine, New York, New York (B.N.C.); and Center for Neurosciences and Cell Biology and Faculty of Medicine, University of Coimbra, Coimbra, Portugal (R.A.C.)
| | - Rodrigo A Cunha
- Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands (A.P.IJ.); National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases, Molecular Recognition Section, Bethesda, Maryland (K.A.J.); Universität Bonn, Bonn, Germany (C.E.M.); New York University School of Medicine, New York, New York (B.N.C.); and Center for Neurosciences and Cell Biology and Faculty of Medicine, University of Coimbra, Coimbra, Portugal (R.A.C.)
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7
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Merighi S, Borea PA, Varani K, Vincenzi F, Jacobson KA, Gessi S. A 2A Adenosine Receptor Antagonists in Neurodegenerative Diseases. Curr Med Chem 2022; 29:4138-4151. [PMID: 34844537 PMCID: PMC9148371 DOI: 10.2174/0929867328666211129122550] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/01/2021] [Accepted: 10/07/2021] [Indexed: 01/03/2023]
Abstract
BACKGROUND Alzheimer's disease (AD) is the most common form of dementia worldwide, with approximately 6 million cases reported in America in 2020. The clinical signs of AD include cognitive dysfunction, apathy, anxiety and neuropsychiatric signs, and pathogenetic mechanisms that involve amyloid peptide-β extracellular accumulation and tau hyperphosphorylation. Unfortunately, current drugs to treat AD can provide only symptomatic relief but are not disease-modifying molecules able to revert AD progression. The endogenous modulator adenosine, through A2A receptor activation, plays a role in synaptic loss and neuroinflammation, which are crucial for cognitive impairment and memory damage. OBJECTIVE In this review, recent advances covering A2A adenosine receptor antagonists will be extensively reviewed, providing a basis for the rational design of future A2A inhibitors. METHODS Herein, the literature on A2A adenosine receptors and their role in synaptic plasticity and neuroinflammation, as well as the effects of A2A antagonism in animal models of AD and in humans, are reviewed. Furthermore, current chemical and structure-based strategies are presented. RESULTS Caffeine, the most widely consumed natural product stimulant and an A2A antagonist, improves human memory. Similarly, synthetic A2A receptor antagonists, as described in this review, may provide a means to fight AD. CONCLUSION This review highlights the clinical potential of A2A adenosine receptor antagonists as a novel approach to treat patients with AD.
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Affiliation(s)
- Stefania Merighi
- Department of Translational Medicine and for Romagna, University of Ferrara, 44121, Ferrara, Italy;,Address correspondence to these authors at the Department Translational Medicine and for Romagna, University of Ferrara, 44121, Ferrara, Italy; ; ; Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, United States;
| | | | - Katia Varani
- Department of Translational Medicine and for Romagna, University of Ferrara, 44121, Ferrara, Italy
| | - Fabrizio Vincenzi
- Department of Translational Medicine and for Romagna, University of Ferrara, 44121, Ferrara, Italy
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, United States,Address correspondence to these authors at the Department Translational Medicine and for Romagna, University of Ferrara, 44121, Ferrara, Italy; ; ; Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, United States;
| | - Stefania Gessi
- Department of Translational Medicine and for Romagna, University of Ferrara, 44121, Ferrara, Italy;,Address correspondence to these authors at the Department Translational Medicine and for Romagna, University of Ferrara, 44121, Ferrara, Italy; ; ; Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, MD, United States;
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8
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Yang X, Heitman LH, IJzerman AP, van der Es D. Molecular probes for the human adenosine receptors. Purinergic Signal 2021; 17:85-108. [PMID: 33313997 PMCID: PMC7954947 DOI: 10.1007/s11302-020-09753-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 11/01/2020] [Indexed: 11/29/2022] Open
Abstract
Adenosine receptors, G protein-coupled receptors (GPCRs) that are activated by the endogenous ligand adenosine, have been considered potential therapeutic targets in several disorders. To date however, only very few adenosine receptor modulators have made it to the market. Increased understanding of these receptors is required to improve the success rate of adenosine receptor drug discovery. To improve our understanding of receptor structure and function, over the past decades, a diverse array of molecular probes has been developed and applied. These probes, including radioactive or fluorescent moieties, have proven invaluable in GPCR research in general. Specifically for adenosine receptors, the development and application of covalent or reversible probes, whether radiolabeled or fluorescent, have been instrumental in the discovery of new chemical entities, the characterization and interrogation of adenosine receptor subtypes, and the study of adenosine receptor behavior in physiological and pathophysiological conditions. This review summarizes these applications, and also serves as an invitation to walk another mile to further improve probe characteristics and develop additional tags that allow the investigation of adenosine receptors and other GPCRs in even finer detail.
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Affiliation(s)
- Xue Yang
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Laura H. Heitman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Adriaan P. IJzerman
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
| | - Daan van der Es
- Division of Drug Discovery and Safety, Leiden Academic Centre for Drug Research, Leiden University, Einsteinweg 55, 2333 CC Leiden, The Netherlands
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9
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Park Y, Park MH, Byeon JJ, Shin SH, Lee BI, Choi JM, Kim N, Park SJ, Park MJ, Lim JH, Shin YG. Assessment of Pharmacokinetics and Metabolism Profiles of SCH 58261 in Rats Using Liquid Chromatography-Mass Spectrometric Method. Molecules 2020; 25:molecules25092209. [PMID: 32397307 PMCID: PMC7248953 DOI: 10.3390/molecules25092209] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/01/2020] [Accepted: 05/05/2020] [Indexed: 11/16/2022] Open
Abstract
5-Amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo(4,3-e)-1,2,4-triazolo(1,5-c) pyrimidine (SCH 58261) is one of the new chemical entities that has been developed as an adenosine A2A receptor antagonist. Although SCH 58261 has been reported to be beneficial, there is little information about SCH 58261 from a drug metabolism or pharmacokinetics perspective. This study describes the metabolism and pharmacokinetic properties of SCH 58261 in order to understand its behaviors in vivo. Rats were used as the in vivo model species. First, an LC-MS/MS method was developed for the determination of SCH 58261 in rat plasma. A GastroPlus™ simulation, in vitro microsomal metabolic stability, and bile duct-cannulated studies were also performed to understand its pharmacokinetic profile. The parameter sensitivity analysis of GastroPlus™ was used to examine the factors that influence exposure when the drug is orally administered. The factors are as follows: permeability, systemic clearance, renal clearance, and liver first-pass effect. In vitro microsomal metabolic stability indicates how much the drug is metabolized. The extrapolated hepatic clearance value of SCH 58261 was 39.97 mL/min/kg, indicating that the drug is greatly affected by hepatic metabolism. In vitro microsomal metabolite identification studies revealed that metabolites produce oxidized and ketone-formed metabolites via metabolic enzymes in the liver. The bile duct-cannulated rat study, after oral administration of SCH 58261, showed that a significant amount of the drug was excreted in feces. These results imply that the drug is not absorbed well in the body after oral administration. Taken together, SCH 58261 showed quite a low bioavailability when administered orally and this was likely due to significantly limited absorption, as well as high metabolism in vivo.
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10
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Yano H, Cai NS, Javitch JA, Ferré S. Luciferase complementation based-detection of G-protein-coupled receptor activity. Biotechniques 2019; 65:9-14. [PMID: 30014734 DOI: 10.2144/btn-2018-0039] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Protein complementation assays (PCA) are used as pharmacological tools, enabling a wide array of applications, ranging from studies of protein-protein interactions to second messenger effects. Methods to detect activities of G protein-coupled receptors (GPCRs) have particular relevance for drug screening. Recent development of an engineered luciferase NanoLuc created the possibility of generating a novel PCA, which in turn could open a new avenue for developing drug screening assays. Here we identified a novel split position for NanoLuc and demonstrated its use in a series of fusion constructs to detect the activity of GPCRs. The split construct can be applied to a variety of pharmacological screening systems.
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Affiliation(s)
- Hideaki Yano
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Ning Sheng Cai
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Jonathan A Javitch
- Departments of Psychiatry & Pharmacology, College of Physicians & Surgeons, Columbia University, New York, NY, USA.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, NY, USA
| | - Sergi Ferré
- National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
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11
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Tritium-labeled agonists as tools for studying adenosine A 2B receptors. Purinergic Signal 2018; 14:223-233. [PMID: 29752618 DOI: 10.1007/s11302-018-9608-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 04/27/2018] [Indexed: 12/11/2022] Open
Abstract
A selective agonist radioligand for A2B adenosine receptors (A2BARs) is currently not available. Such a tool would be useful for labeling the active conformation of the receptors. Therefore, we prepared BAY 60-6583, a potent and functionally selective A2BAR (partial) agonist, in a tritium-labeled form. Despite extensive efforts, however, we have not been able to establish a radioligand binding assay using [3H]BAY 60-6583. This is probably due to its high non-specific binding and its moderate affinity, which had previously been overestimated based on functional data. As an alternative, we evaluated the non-selective A2BAR agonist [3H]NECA for its potential to label A2BARs. [3H]NECA showed specific, saturable, and reversible binding to membrane preparations of Chinese hamster ovary (CHO) or human embryonic kidney (HEK) cells stably expressing human, rat, or mouse A2BARs. In competition binding experiments, the AR agonists 2-chloroadenosine (CADO) and NECA displayed significantly higher affinity when tested versus [3H]NECA than versus the A2B-antagonist radioligand [3H]PSB-603 while structurally diverse AR antagonists showed the opposite effects. Although BAY 60-6583 is an A2BAR agonist, it displayed higher affinity versus [3H]PSB-603 than versus [3H]NECA. These results indicate that nucleoside and non-nucleoside agonists are binding to very different conformations of the A2BAR. In conclusion, [3H]NECA is currently the only useful radioligand for determining the affinity of ligands for an active A2BAR conformation.
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Arruda MA, Stoddart LA, Gherbi K, Briddon SJ, Kellam B, Hill SJ. A Non-imaging High Throughput Approach to Chemical Library Screening at the Unmodified Adenosine-A 3 Receptor in Living Cells. Front Pharmacol 2017; 8:908. [PMID: 29321740 PMCID: PMC5733478 DOI: 10.3389/fphar.2017.00908] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 11/28/2017] [Indexed: 12/29/2022] Open
Abstract
Recent advances in fluorescent ligand technology have enabled the study of G protein-coupled receptors in their native environment without the need for genetic modification such as addition of N-terminal fluorescent or bioluminescent tags. Here, we have used a non-imaging plate reader (PHERAstar FS) to monitor the binding of fluorescent ligands to the human adenosine-A3 receptor (A3AR; CA200645 and AV039), stably expressed in CHO-K1 cells. To verify that this method was suitable for the study of other GPCRs, assays at the human adenosine-A1 receptor, and β1 and β2 adrenoceptors (β1AR and β2AR; BODIPY-TMR-CGP-12177) were also carried out. Affinity values determined for the binding of the fluorescent ligands CA200645 and AV039 to A3AR for a range of classical adenosine receptor antagonists were consistent with A3AR pharmacology and correlated well (R2 = 0.94) with equivalent data obtained using a confocal imaging plate reader (ImageXpress Ultra). The binding of BODIPY-TMR-CGP-12177 to the β1AR was potently inhibited by low concentrations of the β1-selective antagonist CGP 20712A (pKi 9.68) but not by the β2-selective antagonist ICI 118551(pKi 7.40). Furthermore, in experiments conducted in CHO K1 cells expressing the β2AR this affinity order was reversed with ICI 118551 showing the highest affinity (pKi 8.73) and CGP20712A (pKi 5.68) the lowest affinity. To determine whether the faster data acquisition of the non-imaging plate reader (~3 min per 96-well plate) was suitable for high throughput screening (HTS), we screened the LOPAC library for inhibitors of the binding of CA200645 to the A3AR. From the initial 1,263 compounds evaluated, 67 hits (defined as those that inhibited the total binding of 25 nM CA200645 by ≥40%) were identified. All compounds within the library that had medium to high affinity for the A3AR (pKi ≥6) were successfully identified. We found three novel compounds in the library that displayed unexpected sub-micromolar affinity for the A3AR. These were K114 (pKi 6.43), retinoic acid p-hydroxyanilide (pKi 6.13) and SU 6556 (pKi 6.17). Molecular docking of these latter three LOPAC library members provided a plausible set of binding poses within the vicinity of the established orthosteric A3AR binding pocket. A plate reader based library screening using an untagged receptor is therefore possible using fluorescent ligand opening the possibility of its use in compound screening at natively expressed receptors.
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Affiliation(s)
- Maria Augusta Arruda
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, The Midlands, United Kingdom
- Vice-Diretoria de Ensino, Pesquisa e Inovacao, Farmanguinhos, Fiocruz, Rio de Janeiro, Brazil
| | - Leigh A. Stoddart
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, The Midlands, United Kingdom
| | - Karolina Gherbi
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, The Midlands, United Kingdom
| | - Stephen J. Briddon
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, The Midlands, United Kingdom
| | - Barrie Kellam
- Centre for Biomolecular Sciences, School of Pharmacy, University of Nottingham, Nottingham, United Kingdom
| | - Stephen J. Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Medical School, Queen's Medical Centre, University of Nottingham, Nottingham, United Kingdom
- Centre of Membrane Proteins and Receptors, University of Birmingham and University of Nottingham, The Midlands, United Kingdom
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Acurio J, Herlitz K, Troncoso F, Aguayo C, Bertoglia P, Escudero C. Adenosine A 2A receptor regulates expression of vascular endothelial growth factor in feto-placental endothelium from normal and late-onset pre-eclamptic pregnancies. Purinergic Signal 2016; 13:51-60. [PMID: 27696086 DOI: 10.1007/s11302-016-9538-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 09/16/2016] [Indexed: 11/26/2022] Open
Abstract
We aim to investigate whether A2A/nitric oxide-mediated regulation of vascular endothelial growth factor (VEGF) expression is impaired in feto-placental endothelial cells from late-onset pre-eclampsia. Cultures of human umbilical vein endothelial cells (HUVECs) and human placental microvascular endothelial cells (hPMECs) from normal and pre-eclamptic pregnancies were used. Assays by using small interference RNA (siRNA) for A2A were performed, and transfected cells were used for estimation of messenger RNA (mRNA) levels of VEGF, as well as for cell proliferation and angiogenesis in vitro. CGS-21680 (A2A agonist, 24 h) increases HUVEC and hPMEC proliferation in a dose response manner. Furthermore, similar to CGS-21680, the nitric oxide donor, S-nitroso-N-acetyl-penicillamine oxide (SNAP), increased cell proliferation in a dose response manner (logEC50 10-9.2 M). In hPMEC, CGS-21680 increased VEGF protein levels in both normal (∼1.5-fold) and pre-eclamptic pregnancies (∼1.2-fold), an effect blocked by the A2A antagonist, ZM-241385 (10-5 M) and the inhibitor of NO synthase, N ω-nitro-L-arginine methyl ester hydrochloride (L-NAME). Subsequently, SNAP partially recovered cell proliferation and in vitro angiogenesis capacity of cells from normal pregnancies exposed to siRNA for A2A. CGS-21680 also increased (∼1.5-fold) the level of VEGF mRNA in HUVEC from normal pregnancies, but not in pre-eclampsia. Additionally, transfection with siRNA for A2A decrease (∼30 %) the level of mRNA for VEGF in normal pregnancy compared to untransfected cells, an effect partially reversed by co-incubation with SNAP. The A2A-NO-VEGF pathway is present in endothelium from microcirculation and macrocirculation in both normal and pre-eclamptic pregnancies. However, NO signaling pathway seems to be impaired in HUVEC from pre-eclampsia.
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Affiliation(s)
- Jesenia Acurio
- Vascular Physiology Laboratory, Group of Investigation in Tumor Angiogenesis (GIANT), Department of Basic Sciences, Universidad del Bío-Bío, Chillán, Chile
| | - Kurt Herlitz
- Vascular Physiology Laboratory, Group of Investigation in Tumor Angiogenesis (GIANT), Department of Basic Sciences, Universidad del Bío-Bío, Chillán, Chile
| | - Felipe Troncoso
- Vascular Physiology Laboratory, Group of Investigation in Tumor Angiogenesis (GIANT), Department of Basic Sciences, Universidad del Bío-Bío, Chillán, Chile
| | - Claudio Aguayo
- Department of Clinical Biochemistry and Immunology, Faculty of Pharmacy, University of Concepción, Concepción, Chile
- Group of Research and Innovation in Vascular Health (GRIVAS Health), Chillan, Chile
| | - Patricio Bertoglia
- Obstetric and Gynecology Department, Hospital Clinico Herminda Martin, Chillán, Chile, Universidad Católica de la Santísima Concepción, Concepción, Chile
| | - Carlos Escudero
- Vascular Physiology Laboratory, Group of Investigation in Tumor Angiogenesis (GIANT), Department of Basic Sciences, Universidad del Bío-Bío, Chillán, Chile.
- Group of Research and Innovation in Vascular Health (GRIVAS Health), Chillan, Chile.
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14
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Guo D, Heitman LH, IJzerman AP. Kinetic Aspects of the Interaction between Ligand and G Protein-Coupled Receptor: The Case of the Adenosine Receptors. Chem Rev 2016; 117:38-66. [DOI: 10.1021/acs.chemrev.6b00025] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Dong Guo
- Division of Medicinal Chemistry,
Leiden Academic Centre for Drug Research (LACDR), Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Laura H. Heitman
- Division of Medicinal Chemistry,
Leiden Academic Centre for Drug Research (LACDR), Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
| | - Adriaan P. IJzerman
- Division of Medicinal Chemistry,
Leiden Academic Centre for Drug Research (LACDR), Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands
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15
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors. Br J Pharmacol 2013; 170:1459-581. [PMID: 24517644 PMCID: PMC3892287 DOI: 10.1111/bph.12445] [Citation(s) in RCA: 505] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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16
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Guo D, Mulder-Krieger T, IJzerman AP, Heitman LH. Functional efficacy of adenosine A₂A receptor agonists is positively correlated to their receptor residence time. Br J Pharmacol 2012; 166:1846-59. [PMID: 22324512 DOI: 10.1111/j.1476-5381.2012.01897.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE The adenosine A(2A) receptor belongs to the superfamily of GPCRs and is a promising therapeutic target. Traditionally, the discovery of novel agents for the A(2A) receptor has been guided by their affinity for the receptor. This parameter is determined under equilibrium conditions, largely ignoring the kinetic aspects of the ligand-receptor interaction. The aim of this study was to assess the binding kinetics of A(2A) receptor agonists and explore a possible relationship with their functional efficacy. EXPERIMENTAL APPROACH We set up, validated and optimized a kinetic radioligand binding assay (a so-called competition association assay) at the A(2A) receptor from which the binding kinetics of unlabelled ligands were determined. Subsequently, functional efficacies of A(2A) receptor agonists were determined in two different assays: a novel label-free impedance-based assay and a more traditional cAMP determination. KEY RESULTS A simplified competition association assay yielded an accurate determination of the association and dissociation rates of unlabelled A(2A) receptor ligands at their receptor. A correlation was observed between the receptor residence time of A(2A) receptor agonists and their intrinsic efficacies in both functional assays. The affinity of A(2A) receptor agonists was not correlated to their functional efficacy. CONCLUSIONS AND IMPLICATIONS This study indicates that the molecular basis of different agonist efficacies at the A(2A) receptor lies within their different residence times at this receptor.
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Affiliation(s)
- Dong Guo
- Division of Medicinal Chemistry, Leiden/Amsterdam Centre for Drug Research, Leiden University, Leiden, the Netherlands
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17
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Yip KH, Lau HYA, Wise H. Reciprocal modulation of anti-IgE induced histamine release from human mast cells by A₁ and A(2B) adenosine receptors. Br J Pharmacol 2012; 164:807-19. [PMID: 21506953 DOI: 10.1111/j.1476-5381.2011.01446.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND AND PURPOSE Adenosine is believed to participate in the pathological development of asthma through a mast cell-dependent mechanism. Our study aimed to pharmacologically characterize the functions of adenosine receptor (AR) subtypes (A₁, A(2A) , A(2B) and A₃) in primary human cultured mast cells (HCMC). EXPERIMENTAL APPROACH HCMC were derived from progenitor stem cells in buffy coat and the effects of adenosine receptor ligands on basal and IgE-dependent histamine release were evaluated. KEY RESULTS Adenosine and analogues alone did not induce HCMC degranulation. When HCMC were activated by anti-IgE after 10 min pre-incubation with adenosine, a biphasic effect on histamine release was observed with enhancement of HCMC activation at low concentrations of adenosine (10⁻⁹-10⁻⁷ mol·L⁻¹) and inhibition at higher concentrations (10⁻⁶-10⁻⁴ mol·L⁻¹). The potentiating action was mimicked by A₁ AR agonists CCPA and 2'MeCCPA, and inhibited by the A₁ AR antagonist PSB36. In contrast, the inhibitory action of adenosine was mimicked by the non-specific A₂ AR agonist CV1808 and attenuated by A(2B) AR antagonists PSB1115 and MRS1760. The non-selective AR antagonist CGS15943 attenuated both the potentiating and inhibitory actions. CONCLUSIONS AND IMPLICATIONS We have defined for the first time the contribution of A₁ and A(2B) ARs, respectively, to the potentiating and inhibitory action of adenosine on human mast cell activation. With reference to the current trend of developing novel anti-asthmatic agents from AR ligands, our results suggest that inhibition of human mast cell activation would be a mechanism for A₁ AR antagonists, but not A(2B) AR antagonists.
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Affiliation(s)
- K H Yip
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong SAR, China
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18
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Dai SS, Zhou YG. Adenosine 2A receptor: a crucial neuromodulator with bidirectional effect in neuroinflammation and brain injury. Rev Neurosci 2011; 22:231-9. [PMID: 21476942 DOI: 10.1515/rns.2011.020] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This review summarizes recent developments that have contributed to our understanding of how adenosine 2A receptors (A2ARs) modulate brain damage in various animal models of acute neurological injuries, including brain ischemia, traumatic brain injury, spinal cord injury and hemorrhage stroke. The main conclusions are: (1) pharmacological, neurochemical and molecular/genetic approaches to the complex actions of A2AR in different cellular elements suggest that A2AR activation exerts bidirectional effect (detrimental or protective) after brain insults; (2) modulation of glutamate excitotoxicity and neuroinflammation are involved in the protection of A2AR agonists or antagonists, but the bidirectional effect of A2AR is largely due to the bidirectional regulation of neuroinflammation (anti-inflammation or proinflammation) by A2AR on immune cells such as microglia cells and peripheral bone marrow cells; and (3) the bidirectional effect of A2AR on neuroinflammation and brain injury depends on the distinct and sometimes opposite actions of A2AR in various cellular elements and on different injury models and associated pathological conditions. The local glutamate level in the brain injury is one of the crucial factors that contribute to the direction of A2AR effect on neuroinflammation and brain injury outcome. These developments presented here clearly highlight the complexity of using A2AR agents therapeutically in acute neuronal injuries and confirm that A2AR ligands have many promising characteristics that encourage the pursuit of their full therapeutic potential.
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Affiliation(s)
- Shuang-Shuang Dai
- Department of Biochemistry and Molecular Biology, Third Military Medical University, 400038 Chongqing, China
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19
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The alternative TrkAIII splice variant targets the centrosome and promotes genetic instability. Mol Cell Biol 2009; 29:4812-30. [PMID: 19564412 DOI: 10.1128/mcb.00352-09] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The hypoxia-regulated alternative TrkAIII splice variant expressed by human neuroblastomas exhibits oncogenic potential, driven by in-frame exon 6 and 7 alternative splicing, leading to omission of the receptor extracellular immunoglobulin C(1) domain and several N-glycosylation sites. Here, we show that the TrkAIII oncogene promotes genetic instability by interacting with and exhibiting catalytic activity at the centrosome. This function depends upon intracellular TrkAIII accumulation and spontaneous interphase-restricted activation, in cytoplasmic tyrosine kinase (tk) domain orientation, predominantly within structures that closely associate with the fully assembled endoplasmic reticulum intermediate compartment and Golgi network. This facilitates TrkAIII tk-mediated binding of gamma-tubulin, which is regulated by endogenous protein tyrosine phosphatases and geldanamycin-sensitive interaction with Hsp90, paving the way for TrkAIII recruitment to the centrosome. At the centrosome, TrkAIII differentially phosphorylates several centrosome-associated components, increases centrosome interaction with polo kinase 4, and decreases centrosome interaction with separase, the net results of which are centrosome amplification and increased genetic instability. The data characterize TrkAIII as a novel internal membrane-associated centrosome kinase, unveiling an important alternative mechanism to "classical" cell surface oncogenic receptor tk signaling through which stress-regulated alternative TrkAIII splicing influences the oncogenic process.
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Abstract
The development of potent and selective agonists and antagonists of adenosine receptors (ARs) has been a target of medicinal chemistry research for several decades, and recently the US Food and Drug Administration has approved Lexiscan, an adenosine derivative substituted at the 2 position, for use as a pharmacologic stress agent in radionuclide myocardial perfusion imaging. Currently, some other adenosine A(2A) receptor (A(2A)AR) agonists and antagonists are undergoing preclinical testing and clinical trials. While agonists are potent antiinflammatory agents also showing hypotensive effects, antagonists are being developed for the treatment of Parkinson's disease.However, since there are still major problems in this field, including side effects, low brain penetration (for the targeting of CNS diseases), short half-life, or lack of in vivo effects, the design and development of new AR ligands is a hot research topic.This review presents an update on the medicinal chemistry of A(2A)AR agonists and antagonists, and stresses the strong need for more selective ligands at the human A(2A)AR subtype, in particular in the case of agonists.
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Affiliation(s)
- Gloria Cristalli
- Dipartimento di Scienze Chimiche, Università di Camerino, 62032 Camerino (MC), Italy.
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21
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Silverman LS, Caldwell JP, Greenlee WJ, Kiselgof E, Matasi JJ, Tulshian DB, Arik L, Foster C, Bertorelli R, Monopoli A, Ongini E. 3H-[1,2,4]-Triazolo[5,1-i]purin-5-amine derivatives as adenosine A2A antagonists. Bioorg Med Chem Lett 2007; 17:1659-62. [PMID: 17234414 DOI: 10.1016/j.bmcl.2006.12.104] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Accepted: 12/22/2006] [Indexed: 11/19/2022]
Abstract
A novel series of 3-substituted-8-aryl-[1,2,4]-triazolo[5,1-i]purin-5-amine analogs related to Sch 58261 was synthesized in order to identify potent adenosine A(2A) receptor antagonists with improved selectivity over the A(1) receptor, physiochemical properties, and pharmacokinetic profiles as compared to those of Sch 58261. As a result of structural modifications, numerous analogs with excellent in vitro binding affinities and selectivities were identified. Moreover, compound 27 displayed both superior in vitro and highly promising in vivo profiles.
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Affiliation(s)
- Lisa S Silverman
- CV & CNS Departments of Chemical Research, Schering Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
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22
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Yang M, Soohoo D, Soelaiman S, Kalla R, Zablocki J, Chu N, Leung K, Yao L, Diamond I, Belardinelli L, Shryock JC. Characterization of the potency, selectivity, and pharmacokinetic profile for six adenosine A2A receptor antagonists. Naunyn Schmiedebergs Arch Pharmacol 2007; 375:133-44. [PMID: 17310264 DOI: 10.1007/s00210-007-0135-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Accepted: 01/09/2007] [Indexed: 10/23/2022]
Abstract
Antagonists of adenosine A2A receptors (A2A -antagonists) with different chemical structures have been developed by several pharmaceutical companies for the potential treatment of Parkinson's disease. Pharmacological characterization of these antagonists was incomplete, and different assay conditions were used in different labs. Therefore, we characterized the potencies, selectivities, and pharmacokinetic profiles of six prototypical A2A -antagonists. Displacements of [3H]MSX-2 and of [3H]CGS21680 binding to the human cloned and rat A2A receptors were performed. The rank order of potency of antagonists to displace [(3)H]MSX-2 binding to the human A2A was SCH58261 > or = Biogen-34 > or = Ver-6623 > or = MSX-2 > KW-6002 > > DMPX. For the rat striatal A2A, the order of potency was Biogen-34 > or = SCH58261 > or = Ver-6623 > or = MSX-2 > or = KW-6002 > > DMPX. SCH58261 was the most potent antagonist of the human A2A with a K(i) value of 4 nM, whereas Biogen-34 was the most potent antagonist of the rat A2A with a K(i) value of 1.2 nM. Similar results were obtained from cAMP assays. Selectivities of A2A-antagonists were determined using radioligands [3H]DPCPX, [3H]ZM241385, and [125I]-AB-MECA for A1, A2B, and A3 receptors, respectively. KW-6002 and Biogen-34 exhibited the highest selectivity for A2A vs A1 (human and rat), respectively. The pharmacokinetic profiles of antagonists were evaluated in vivo in rats. DMPX and KW-6002 had the greatest oral bioavailability. In contrast, SCH58261, MSX-2, and Ver-6623 had low or poor oral bioavailability. In summary, SCH58261, Biogen-34, MSX-2, and Ver-6623 had high affinities for both human and rat A2A receptors, with reasonable selectivity for A2A over A1 and A2B receptors. They are suitable as A2A -antagonists for in vitro pharmacological studies. Among the six A2A-antagonists, KW-6002 is the best for use in in vivo animal studies, particularly for a CNS target, based on its bioavailability, half life, and brain penetration.
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Affiliation(s)
- Ming Yang
- Department of Pharmacology, CV Therapeutics, Inc., Palo Alto, CA 94304, USA.
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23
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Ravyn V, Bostwick JR. Functional coupling of the Galpha(olf) variant XLGalpha(olf) with the human adenosine A2A receptor. J Recept Signal Transduct Res 2006; 26:241-58. [PMID: 16818375 DOI: 10.1080/10799890600710592] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
A recently identified novel Galphaolf variant, XLGalphaolf, is shown to functionally couple to the human adenosine A2A receptor (A2AR). In Sf9 cells expressing A2AR, beta1, and gamma2, co-expression of XLGalphaolf increased NECA-induced [35S]GTPgammaS binding from approximately 130% to 300% of basal levels. Pharmacological characteristics of A2AR ligands on these cells were evaluated by using [3H]ZM241385- and [35S]GTPgammaS- binding assays. The rank order of the equilibrium binding constants (Kd or Ki) of adenosine receptor ligands were [3H]ZM241385 approximately CGS15943 < MRS1220 < < CV1808 approximately NECA < CGS21680 approximately adenosine < IBMECA < HEMADO approximately CPA approximately CCPA. The rank order of EC50 values for agonists were CV1808 approximately NECA < adenosine approximately CGS26180 < IBMECA < HEMADO approximately CPA approximately CCPA. This pharmacology is consistent with the literature for A2AR and suggests that Sf9 cells co-expressing A2AR, beta1, gamma2, and XLGalphaolf could serve as a heterologous expression system for A2AR drug screening.
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Affiliation(s)
- Vipa Ravyn
- Lead Discovery, AstraZeneca Pharmaceuticals, Wilmington, Delaware 19850, USA
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24
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Morissette M, Dridi M, Calon F, Hadj Tahar A, Meltzer LT, Bédard PJ, Di Paolo T. Prevention of dyskinesia by an NMDA receptor antagonist in MPTP monkeys: Effect on adenosine A2A receptors. Synapse 2006; 60:239-50. [PMID: 16739115 DOI: 10.1002/syn.20295] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Adenosine A(2A) receptors (A(2A)R) have received increasing attention for the treatment of L-DOPA-induced dyskinesias in Parkinson disease. In the present study, A(2A)R messenger RNA (mRNA) and receptor-specific binding in the brain of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) monkeys were studied after treatment with L-DOPA and a selective NR1A/2B NMDA receptor antagonist, CI-1041. Four MPTP monkeys received L-DOPA/benserazide and all developed dyskinesias, whereas among the four MPTP monkeys who additionally received CI-1041, only one developed mild dyskinesias. Four normal monkeys and four MPTP-treated monkeys were also studied. All MPTP monkeys had similar striatal dopamine (DA) denervation. A(2A)R mRNA levels, measured by in situ hybridization, were increased in the rostral lateral caudate and putamen of saline-treated MPTP monkeys as well as in the caudal lateral and medial putamen when compared with those of controls. A(2A)R mRNA levels remained elevated in the rostral caudate and putamen of L-DOPA-treated MPTP monkeys when compared with those of controls. A(2A)R mRNA levels of L-DOPA + CI-1041-treated monkeys were at control levels and decreased in the lateral rostral caudate and caudal putamen when compared with those of L-DOPA-treated and saline-treated MPTP monkeys respectively. No change was measured in the caudal medial putamen and caudate nucleus. A(2A)Rs labeled by autoradiography with [(3)H]SCH-58261 had lower level in the L-DOPA + CI-1041-treated MPTP monkeys compared with saline- or L-DOPA-treated MPTP and control monkeys in the rostral lateral and medial caudate and the putamen. No effect of lesion or L-DOPA treatment was measured on [(3)H]SCH-58261-specific binding. These findings suggest that blockade of NMDA receptors could prevent the development of dyskinesias by altering A(2A)Rs.
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Affiliation(s)
- Marc Morissette
- Molecular Endocrinology and Oncology Research Centre, Laval University Medical Centre (CHUL), Quebec, Canada
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25
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Matasi JJ, Caldwell JP, Zhang H, Fawzi A, Cohen-Williams ME, Varty GB, Tulshian DB. 2-(2-Furanyl)-7-phenyl[1,2,4]triazolo[1,5-c]pyrimidin-5-amine analogs: Highly potent, orally active, adenosine A2A antagonists. Part 1. Bioorg Med Chem Lett 2005; 15:3670-4. [PMID: 15978806 DOI: 10.1016/j.bmcl.2005.05.086] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2005] [Revised: 05/05/2005] [Accepted: 05/11/2005] [Indexed: 11/24/2022]
Abstract
The structure-activity relationship of this novel class of compounds based on 2-(2-furanyl)-7-phenyl[1,2,4]-triazolo[1,5-c]pyrimidin-5-amine, 1, and its analogs was evaluated for their in vitro and in vivo adenosine A(2A) receptor antagonism. Several compounds displayed oral activity at 3 mg/kg in a rat catalepsy model. Specifically, compound 8g displayed an excellent in vitro profile, as well as a highly promising in vivo profile.
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Affiliation(s)
- Julius J Matasi
- Department of Medicinal Chemistry-CV & CNS, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
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26
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Matasi JJ, Caldwell JP, Zhang H, Fawzi A, Higgins GA, Cohen-Williams ME, Varty GB, Tulshian DB. 2-(2-Furanyl)-7-phenyl[1,2,4]triazolo[1,5-c]pyrimidin-5-amine analogs as adenosine A2A antagonists: The successful reduction of hERG activity. Part 2. Bioorg Med Chem Lett 2005; 15:3675-8. [PMID: 15982882 DOI: 10.1016/j.bmcl.2005.05.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2005] [Revised: 05/05/2005] [Accepted: 05/11/2005] [Indexed: 10/25/2022]
Abstract
The structure-activity relationship (SAR) exploration using 2-(2-furanyl)-7-phenyl[1,2,4]triazolo-[1,5-c]pyrimidin-5-amine (1) as a template led to the identification of a novel class of potent and selective adenosine A2A receptor (AR) antagonists. However, these compounds were found to be associated with significant hERG activity. This report discusses the strategy and outcome of an expanded SAR focused on addressing the hERG liability. As a result, compounds 21 and 24 possess excellent in vitro profiles, highly promising in vivo profiles, and acceptable levels of hERG channel inhibition.
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Affiliation(s)
- Julius J Matasi
- Department of Medicinal Chemistry-CV&CNS, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
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27
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Matasi JJ, Caldwell JP, Hao J, Neustadt B, Arik L, Foster CJ, Lachowicz J, Tulshian DB. The discovery and synthesis of novel adenosine receptor (A(2A)) antagonists. Bioorg Med Chem Lett 2005; 15:1333-6. [PMID: 15713381 DOI: 10.1016/j.bmcl.2005.01.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2004] [Revised: 01/10/2005] [Accepted: 01/11/2005] [Indexed: 10/25/2022]
Abstract
In high throughput screening of our file compounds, a novel structure 1 was identified as a potent A(2A) receptor antagonist with no selectivity over the A1 adenosine receptor. The structure-activity relationship investigation using 1 as a template lead to identification of a novel class of compounds as potent and selective antagonists of A(2A) adenosine receptor. Compound 26 was identified to be the most potent A(2A) receptor antagonist (Ki = 0.8 nM) with 100-fold selectivity over the A1 adenosine receptor.
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Affiliation(s)
- Julius J Matasi
- Department of Medicinal Chemistry-CV & CNS, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
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28
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Hsiao G, Lin KH, Chang Y, Chen TL, Tzu NH, Chou DS, Sheu JR. Protective mechanisms of inosine in platelet activation and cerebral ischemic damage. Arterioscler Thromb Vasc Biol 2005; 25:1998-2004. [PMID: 15976325 DOI: 10.1161/01.atv.0000174798.25085.d6] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Inosine is a naturally occurring nucleoside degraded from adenosine. Recent studies have demonstrated that inosine has potent immunomodulatory and neuroprotective effects. In the present study, we further investigated the inhibitory effects of inosine on platelet activation in vitro and in vivo, as well as in attenuating middle cerebral artery occlusion (MCAO)-induced focal cerebral ischemia in rats. METHODS AND RESULTS Inosine concentration-dependently (0.5 to 6.0 mmol/L) inhibited platelet aggregation stimulated by agonists. Inosine (1.5 and 3.0 mmol/L) inhibited phosphoinositide breakdown, [Ca+2]i, and TxA2 formation in human platelets stimulated by collagen (1 microg/mL). In addition, inosine (1.5 and 3.0 mmol/L) markedly increased levels of cyclic guanylate monophosphate (GMP) and cyclic GMP-induced vasodilator-stimulated phosphoprotein Ser157 phosphorylation. Rapid phosphorylation of a platelet protein of molecular weight 47,000 (P47), a marker of protein kinase C activation, was triggered by collagen (1 microg/mL). This phosphorylation was markedly inhibited by inosine (3.0 mmol/L). Inosine (1.5 and 3.0 mmol/L) markedly reduced hydroxyl radical in collagen (1 microg/mL)-activated platelets. In in vivo studies, inosine (400 mg/kg) significantly prolonged the latency period of inducing platelet plug formation in mesenteric venules of mice, and administration of 2 doses (100 mg/kg) or a single dose (150 mg/kg) of inosine significantly attenuated MCAO-induced focal cerebral ischemia in rats. CONCLUSIONS Platelet aggregation contributes significantly to MCAO-induced focal cerebral ischemia. The most important findings of this study suggest that inosine markedly inhibited platelet activation in vitro and in vivo, as well as cerebral ischemia. Thus, inosine treatment may represent a novel approach to lowering the risk of or improving function in thromboembolic-related disorders and ischemia-reperfusion brain injury.
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Affiliation(s)
- George Hsiao
- Graduate Institute of Medical Sciences, Taipei Medical University, No. 250, Wu-Hsing Street, Taipei 110, Taiwan
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29
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Kiselgof E, Tulshian DB, Arik L, Zhang H, Fawzi A. 6-(2-Furanyl)-9H-purin-2-amine derivatives as A2A adenosine antagonists. Bioorg Med Chem Lett 2005; 15:2119-22. [PMID: 15808481 DOI: 10.1016/j.bmcl.2005.02.031] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Revised: 02/08/2005] [Accepted: 02/09/2005] [Indexed: 11/28/2022]
Abstract
Structure-activity relationships have been investigated through substitutions at the 9-position of the 2-amino-6-(2-furanyl) purine (5) to identify novel and selective A(2A) adenosine receptor antagonists. Several potent and selective antagonists were identified. In particular, compounds 20, 25, and 26 show very high affinity with excellent selectivity.
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Affiliation(s)
- Eugenia Kiselgof
- Schering-Plough Research Institute, Chemical Research, 2015 Galloping Hill Road, MS 2545, Kenilworth, NJ 07033, USA
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30
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Impagnatiello F, Bastia E, Ongini E, Monopoli A. Adenosine receptors in neurological disorders. ACTA ACUST UNITED AC 2005. [DOI: 10.1517/14728222.4.5.635] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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31
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Wengert M, Berto C, Kaufman J, Leão-Ferreira LR, Paes-de-Carvalho R, Lopes AG, Caruso-Neves C. Stimulation of the proximal tubule Na+-ATPase activity by adenosine A(2A) receptor. Int J Biochem Cell Biol 2005; 37:155-65. [PMID: 15381158 DOI: 10.1016/j.biocel.2004.06.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 06/03/2004] [Accepted: 06/04/2004] [Indexed: 01/01/2023]
Abstract
The aim of this work was to determine the molecular mechanism involved in the stimulation of the pig kidney proximal tubule Na+-ATPase by adenosine (Ado). To study the role of A2 Ado receptors, we added in all experiments 10(-6)M DPCPX, an A1 receptor-selective antagonist, since we have previously shown that Ado inhibits the enzyme activity through this receptor. Ado increased the Na+-ATPase activity with maximal effect observed at 10(-6)M. The presence of both A(2A) and A(2B) receptors were demonstrated by immunoblotting using specific polyclonal antibodies. The stimulatory effect of Ado was completely abolished by 5 x 10(-9)M DMPX, an antagonist of A2 receptor, and 10(-7)M SCH 58261, an A(2A) receptor-selective antagonist. DMPA (10(-7)M), a specific agonist of A(2A) receptor mimicked the stimulatory effect of Ado. Involvement of a Gs protein/adenylate cyclase/PKA pathway was evidenced by: (a) the reversion of Ado-induced effect by GDPbetaS; (b) stimulation of the Na+-ATPase activity in a similar and non-additive manner to Ado by 10(-8)M cholera toxin, 10(-7)M GTPgammaS, 10(-6)M forskolin, 10(-7)M cAMP or 1.25 U catalytic subunit of PKA; (c) the reversion of the stimulatory effect of Ado by 10(-8)M PKA inhibitor peptide; (d) Ado-produced two-fold increase of the PKA activity, which was completely reversed by 10(-6)M DMPX. These are the first evidences showing the modulation of a renal primary active sodium transporter by Ado through A(2A) receptor.
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Affiliation(s)
- M Wengert
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro 21949-900, RJ, Brazil
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32
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Bryant R, McGuinness D, Turek-Etienne T, Guyer D, Yu L, Howells L, Caravano J, Zhai Y, Lachowicz J. WGA-coated yttrium oxide beads enable an imaging-based adenosine 2a receptor binding scintillation proximity assay suitable for high throughput screening. Assay Drug Dev Technol 2005; 2:290-9. [PMID: 15285910 DOI: 10.1089/1540658041410713] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Adenosine receptors belong to the superfamily of G protein-coupled receptors and are involved in a variety of physiologic functions. Traditionally, binding assays to detect adenosine 2a (A2a) antagonists and agonists have used filtration methods that are cumbersome to run and not amenable to HTS. We developed scintillation proximity assays (SPA trade mark ) utilizing HEK293 RBHA2AM cell membranes, either wheat germ agglutinin (WGA)-coated yttrium silicate (YSi) or red-shifted yttrium oxide (YO) beads and the A2a-selective radioligand [(3)H]SCH 58261. Both beads gave windows (total binding/nonspecific binding) of >5 and K(d) values of 2-3 nM for the radioligand, in agreement with results obtained by filtration. In contrast, WGA-polyvinyltoluene as well as other bead types had windows of <3 and significant radioligand binding to the uncoated beads. A 384-well WGA-YO bead SPA was optimized utilizing a LEADseeker imaging system and an automated trituration process for dispensing the dense yttrium-based beads. Signals were stable after 4 h, and Z' values were 0.7-0.8. The LEADseeker imaging assay tolerated 2% dimethyl sulfoxide and generated IC(50) values of 3-5 nM for the A2a antagonist CGS 15943, comparable to that obtained by the filtration method. A number of adenosine and xanthine analogues were identified as hits in the Library of Pharmacologically Active Compounds (LOPAC). This imaging-based A2a SPA enables HTS and is a major improvement over the filtration method.
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Affiliation(s)
- Robert Bryant
- Schering-Plough Research Institute, 20156 Galloping Hill Road, Kenilworth, NJ 07033, USA
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33
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Uustare A, Vonk A, Terasmaa A, Fuxe K, Rinken A. Kinetic and functional properties of [3H]ZM241385, a high affinity antagonist for adenosine A2A receptors. Life Sci 2004; 76:1513-26. [PMID: 15680315 DOI: 10.1016/j.lfs.2004.10.027] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2004] [Accepted: 10/02/2004] [Indexed: 12/01/2022]
Abstract
We have characterized the binding of [2-(3)H]-4-(2-[7-Amino-2-(2-furyl)-[1,2,4]-triazolo-[2,3-a]-[1,3,5]-triazin-5-ylamino]ethyl)phenol ([(3)H]ZM241385) to adenosine A(2A) receptors in membranes of rat striatum and transfected CHO cells. Saturation experiments showed that [(3)H]ZM241385 binds to a single class of binding sites with high affinity (K(d) = 0.23 nM and 0.14 nM in CHO cell and striatal membranes, respectively). The membranes of CHO cells required pretreatment with adenosine deaminase (ADA) to achieve high-affinity binding, while ADA had no influence on the ligand binding properties in striatal membranes. The binding of [(3)H]ZM241385 was fast and reversible, achieving equilibrium within 20 minutes at all radioligand concentrations. The kinetic analysis of the [(3)H]ZM241385 interaction with A(2A) receptors indicated that the reaction had at least two subsequent steps. The first step corresponds to a fast equilibrium, which also determines the antagonist potency to competitively inhibit CGS21680-induced accumulation of cAMP (first equilibrium constant K(A) = 6.6 nM). The second step corresponds to a slow process of conformational isomerization (equilibrium constant K(i) = 0.03). The combination of the two steps gives the dissociation constant K(d) = 0.20 nM based on the kinetic data, which is in good agreement with the directly measured value. The data obtained shed light on the mechanism of the [(3)H]ZM241385 interaction with adenosine A(2A) receptors from different sources in vitro. The isomerization step of the A(2A) antagonist radioligand binding has to be taken into account for the interpretation of the binding parameters obtained from the various competition assays and explain the discrepancy between antagonist affinity in saturation experiments versus its potency in functional assays.
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Affiliation(s)
- Ain Uustare
- Institute of Organic and Bioorganic Chemistry, University of Tartu, Jakobi Str. 2, EE-51014 Tartu, Estonia
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Lynge J, Schulte G, Nordsborg N, Fredholm BB, Hellsten Y. Adenosine A 2B receptors modulate cAMP levels and induce CREB but not ERK1/2 and p38 phosphorylation in rat skeletal muscle cells. Biochem Biophys Res Commun 2003; 307:180-7. [PMID: 12849998 DOI: 10.1016/s0006-291x(03)01125-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The present study examined the existence of the adenosine A(1),A(2A), and A(2B) receptors and the effect of receptor activation on cAMP accumulation and protein phosphorylation in primary rat skeletal muscle cells. Presence of mRNA and protein for all three receptors was demonstrated in both cultured and adult rat skeletal muscle. NECA (10(-9)-10(-4)M) increased the cAMP concentration in cultured muscle cells with an EC(50) of (95% confidence interval)=15 (5.9-25.1) micro M, whereas CGS 21680 (10(-9)-10(-4)M) had no effect on cAMP accumulation. Concentrations of [R]-PIA below 10(-6)M had no effect on cAMP accumulation induced by either isoproterenol or forskolin. NECA resulted in phosphorylation of CREB with an EC(50) of (95% confidence interval)=1.7 (0.40-7.02) micro M, whereas ERK1/2 and p38 phosphorylation was unchanged. The results show that, although the A(1),A(2A), and A(2B) receptors are all present in skeletal muscle cells, the effect of adenosine on adenylyl cyclase activation and phosphorylation of CREB is mainly mediated via the adenosine A(2B) receptor.
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Affiliation(s)
- Jan Lynge
- Copenhagen Muscle Research Centre, Department of Human Physiology, Institute of Exercise and Sports Sciences, August Krogh Institute, Copenhagen University, Universitetsparken 13, Copenhagen Ø, DK-2100, Denmark
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35
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Varani K, Gessi S, Merighi S, Iannotta V, Cattabriga E, Spisani S, Cadossi R, Borea PA. Effect of low frequency electromagnetic fields on A2A adenosine receptors in human neutrophils. Br J Pharmacol 2002; 136:57-66. [PMID: 11976268 PMCID: PMC1762120 DOI: 10.1038/sj.bjp.0704695] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The present study describes the effect of low frequency, low energy, pulsing electromagnetic fields (PEMFs) on A2A adenosine receptors in human neutrophils. Saturation experiments performed using a high affinity adenosine antagonist [3H]-ZM 241385 revealed a single class of binding sites in control and in PEMF-treated human neutrophils with similar affinity (KD=1.05+/-0.10 and 1.08+/-0.12 nM, respectively). Furthermore, after 1 h of exposure to PEMFs the receptor density was statistically increased (P<0.01) (Bmax =126+/-10 and 215+/-15 fmol mg-1 protein, respectively). The effect of PEMFs was specific to the A2A adenosine receptors. This effect was also intensity, time and temperature dependent. In the adenylyl cyclase assays the A2A receptor agonists, HE-NECA and NECA, increased cyclic AMP accumulation in untreated human neutrophils with an EC50 value of 43 (40 - 47) and 255 (228 - 284) nM, respectively. The capability of HE-NECA and NECA to stimulate cyclic AMP levels in human neutrophils was increased (P<0.01) after exposure to PEMFs with an EC50 value of 10(8 - 13) and 61(52 - 71) nM, respectively. In the superoxide anion (O2-) production assays HE-NECA and NECA inhibited the generation of O2- in untreated human neutrophils, with an EC50 value of 3.6(3.1 - 4.2) and of 23(20 - 27) nM, respectively. Moreover, in PEMF-treated human neutrophils, the same compounds show an EC50 value of 1.6(1.2 - 2.1) and of 6.0(4.7 - 7.5) nM respectively. These results indicate the presence of significant alterations in the expression and in the functionality of adenosine A2A receptors in human neutrophils treated with PEMFs.
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MESH Headings
- Binding, Competitive
- Cyclic AMP/biosynthesis
- Electromagnetic Fields
- Humans
- In Vitro Techniques
- Kinetics
- Neutrophils/metabolism
- Neutrophils/radiation effects
- Purinergic P1 Receptor Agonists
- Radioligand Assay
- Receptor, Adenosine A2A
- Receptors, Adrenergic, alpha-2/metabolism
- Receptors, Adrenergic, beta-2/metabolism
- Receptors, Opioid, kappa/metabolism
- Receptors, Opioid, mu/metabolism
- Receptors, Purinergic P1/metabolism
- Superoxides/metabolism
- Temperature
- Time Factors
- Up-Regulation
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Affiliation(s)
- Katia Varani
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Ferrara, Italy
| | - Stefania Gessi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Ferrara, Italy
| | - Stefania Merighi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Ferrara, Italy
| | - Valeria Iannotta
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Ferrara, Italy
| | - Elena Cattabriga
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Ferrara, Italy
| | - Susanna Spisani
- Department of Biochemistry and Molecular Biology, University of Ferrara, Ferrara, Italy
| | | | - Pier Andrea Borea
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Ferrara, Italy
- Author for correspondence:
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36
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Weiss HM, Grisshammer R. Purification and characterization of the human adenosine A(2a) receptor functionally expressed in Escherichia coli. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:82-92. [PMID: 11784301 DOI: 10.1046/j.0014-2956.2002.02618.x] [Citation(s) in RCA: 169] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The adenosine A(2a) receptor belongs to the seven transmembrane helix G-protein-coupled receptor family, is abundant in striatum, vasculature and platelets and is involved in several physiological processes such as blood pressure regulation and protection of cells during anoxia. For structural and biophysical studies we have expressed the human adenosine A(2a) receptor (hA2aR) at high levels inserted into the Escherichia coli inner membrane, and established a purification scheme. Expression was in fusion with the periplasmic maltose-binding protein to levels of 10-20 nmol of receptor per L of culture, as detected with the specific antagonist ligand [(3)H]ZM241385. As the receptor C-terminus was proteolyzed upon solubilization, a protease-resistant but still functional receptor was created by truncation to Ala316. Addition of the sterol, cholesteryl hemisuccinate, allowed a stable preparation of functional hA2aR solubilized in dodecylmaltoside to be obtained, and, increased the stability of the receptor solubilized in other alkylmaltosides. Purification to homogeneity was achieved in three steps, including ligand affinity chromatography based on the antagonist xanthine amine congener. The purified hA2aR fusion protein bound [(3)H]ZM241385 with a K(d) of 0.19 nm and an average B(max) of 13.7 nmol x mg(-1) that suggests 100% functionality. Agonist affinities for the purified solubilized receptor were higher than those for the membrane-bound form. Sufficient pure, functional hA2aR can now be prepared regularly for structural studies.
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Affiliation(s)
- H Markus Weiss
- MRC Laboratory of Molecular Biology, Hills Road, Cambridge, UK.
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37
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Fredholm BB, Arslan G, Halldner L, Kull B, Schulte G, Ådén U, Svenningsson P. Adenosine receptor signaling in vitro and in vivo. Drug Dev Res 2001. [DOI: 10.1002/ddr.1124] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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38
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Gao ZG, Jiang Q, Jacobson KA, Ijzerman AP. Site-directed mutagenesis studies of human A(2A) adenosine receptors: involvement of glu(13) and his(278) in ligand binding and sodium modulation. Biochem Pharmacol 2000; 60:661-8. [PMID: 10927024 PMCID: PMC5567773 DOI: 10.1016/s0006-2952(00)00357-9] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
To provide insights into interactions between ligands and A(2A) adenosine receptors, site-directed mutagenesis was used to test the roles of a glutamic acid residue in the first transmembrane domain (Glu13) and a histidine residue in the seventh transmembrane domain (His278). The two residues, which have been suggested to be closely linked in molecular modeling studies, were mutated to glutamine (E13Q) and tyrosine (H278Y), respectively. Saturation experiments revealed that [(3)H]ZM241385 (4-2-[7-amino-2-(2-furyl)-1,2, 4-triazolo[1,5-a][1,3,5]triazin-5-yl-amino]ethylphenol) bound wild-type and mutant receptors in membranes from COS-7 cells expressing human A(2A) adenosine receptors with high affinity and low non-specific binding. It was found from the competition experiments that the affinity of the A(2A) adenosine receptor agonists for the mutant receptors was 3- to 200-fold lower than for the wild-type receptor. Among antagonist competitors of binding at E13Q and H278Y mutant receptors, there was variation in the affinity depending on their different structures, although changes were relatively minor (<3-fold) except in the case of theophylline, whose affinity was decreased approximately 20 times on the H278Y mutant. The possible involvement of the two residues in sodium ion regulation was also tested. The agonist competition curves for [(3)H]ZM241385 were shifted to the right in both wild-type and mutant receptors in the presence of 1 M sodium ions, but the extent of shift (2- to 27-fold) in wild-type receptor was generally larger than for the mutant receptors. Sodium ions also decreased [(3)H]ZM241385 dissociation from both wild-type and mutant receptors, being more influential on the former than the latter. The results suggest that the two closely linked residues Glu13 and His278 in A(2A) adenosine receptor are most important for agonist recognition and are partly responsible for the allosteric regulation by sodium ions.
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Affiliation(s)
- Z G Gao
- Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, P.O. Box 9502, 2300 RA, Leiden, The Netherlands
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Ohkubo S, Kimura J, Nakanishi H, Matsuoka I. Effects of P(1) and P2 receptor antagonists on beta, gamma-methyleneATP- and CGS21680-induced cyclic AMP formation in NG108-15 cells. Br J Pharmacol 2000; 129:291-8. [PMID: 10694235 PMCID: PMC1571837 DOI: 10.1038/sj.bjp.0703053] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. We have previously shown that ATP increased cyclic AMP in NG108-15 cells, which was inhibited by P(1) receptor antagonist methylxanthines. In the present study, we examined the effects of P(1) and P2 receptor antagonists on cyclic AMP formation induced by beta,gamma-methyleneATP (beta,gamma-MeATP) and CGS21680, an A(2A) adenosine receptor agonist, in NG108-15 cells. 2. beta,gamma-MeATP and CGS21680 increased intracellular cyclic AMP with EC(50) values of 8. 0+/-0.98 microM (n=4) and 42+/-7.5 nM (n=4), respectively. 3. Several P(1) receptor antagonists inhibited both beta,gamma-MeATP- and CGS21680-induced cyclic AMP increase with a similar rank order of potency; ZM241385>CGS15943>XAC>DPCPX. However, the pK(i) values of these antagonists for beta,gamma-MeATP were larger than those for CGS21680. 4. Alloxazine, a P(1) receptor antagonist, and several P2 receptor antagonists (PPADS, iPPADS, reactive blue-2) inhibited beta, gamma-MeATP-induced response, while these antagonists little affected CGS21680-induced one. Suramin was effective only for beta, gamma-MeATP-induced response at 1 mM. 5. 2-chloroadenosine (2CADO) and 2-chloroATP (2ClATP) increased cyclic AMP with similar potencies. The effects of these agonists were both inhibited by ZM241385, but only 2ClATP-induced response was inhibited by PPADS. 6. ATP- and beta, gamma-MeATP-induced responses were little affected by alpha, beta-methyleneADP, a 5'-nucleotidase inhibitor. 7. These results clearly demonstrate that ATP-stimulated cyclic AMP formation can be distinguished from the A(2A) receptor agonist-induced one by using the several P(1) and P2 receptor antagonists.
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Affiliation(s)
- S Ohkubo
- Department of Pharmacology, School of Medicine, Fukushima Medical University, Hikarigaoka 1, Fukushima 960-1295, Japan.
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Gessi S, Varani K, Merighi S, Ongini E, Borea PA. A(2A) adenosine receptors in human peripheral blood cells. Br J Pharmacol 2000; 129:2-11. [PMID: 10694196 PMCID: PMC1621134 DOI: 10.1038/sj.bjp.0703045] [Citation(s) in RCA: 125] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/1999] [Revised: 09/10/1999] [Accepted: 10/20/1999] [Indexed: 11/08/2022] Open
Affiliation(s)
- S Gessi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy
| | - K Varani
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy
| | - S Merighi
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy
| | - E Ongini
- Schering-Plough Research Institute, San Raffaele Science Park, 20132 Milan, Italy
| | - P A Borea
- Department of Clinical and Experimental Medicine, Pharmacology Unit, University of Ferrara, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy
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Varani K, Cacciari B, Baraldi PG, Dionisotti S, Ongini E, Borea PA. Binding affinity of adenosine receptor agonists and antagonists at human cloned A3 adenosine receptors. Life Sci 1998; 63:PL 81-7. [PMID: 9714428 DOI: 10.1016/s0024-3205(98)00289-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The A3 adenosine receptor is one of the four adenosine receptors which have thus far been identified. Cloning of the A3 receptor from animal species such as rat, sheep and human has shown that there are interspecies differences in its peripheral distribution, and binding affinity for various adenosine receptor ligands. The adenosine derivative, 4-aminobenzyl-5'-N-methylcarboxamidoadenosine (AB-MECA), is a potent A3 receptor agonist which is used as a reference drug. In this report we have characterized the binding of selected adenosine receptor agonists and antagonists to HEK 293 cells transfected with the human A3 adenosine receptor using [125I]AB-MECA as radioligand. HE-NECA and NECA were the most potent compounds showing Ki values in the low nanomolar range, while the recently discovered non-xanthine A2A receptor antagonists ZM 241385, SCH 58261 and SCH 63390 showed affinity values in the micromolar range. These data further indicate the need to examine the affinity of new adenosine receptor ligands directly in human A3 receptors.
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Affiliation(s)
- K Varani
- Dipartimento di Medicina Clinica e Sperimentale-Sezione di Farmacologia, Università degli Studi di Ferrara, Italy
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Varani K, Gessi S, Dionisotti S, Ongini E, Borea PA. [3H]-SCH 58261 labelling of functional A2A adenosine receptors in human neutrophil membranes. Br J Pharmacol 1998; 123:1723-31. [PMID: 9605581 PMCID: PMC1565317 DOI: 10.1038/sj.bjp.0701758] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
1. The present study describes the direct labelling of A2A adenosine receptors in human neutrophil membranes with the potent and selective antagonist radioligand, [3H]-5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4 triazolo[l,5-c]pyrimidine, ([3H]-SCH 58261). In addition, both receptor affinity and potency of a number of adenosine receptor agonists and antagonists were determined in binding, adenylyl cyclase and superoxide anion production assays. 2. Saturation experiments revealed a single class of binding sites with Kd and Bmax values of 1.34 nM and 75 fmol mg(-1) protein, respectively. Adenosine receptor ligands competed for the binding of 1 nM [3H]-SCH 58261 to human neutrophil membranes, with a rank order of potency consistent with that typically found for interactions with the A2A adenosine receptors. In the adenylyl cyclase and in the superoxide anion production assays the same compounds exhibited a rank order of potency identical to that observed in binding experiments. 3. Thermodynamic data indicated that [3H]-SCH 58261 binding to human neutrophils is entropy and enthalpy-driven. This finding is in agreement with the thermodynamic behaviour of antagonists binding to rat striatal A2A adenosine receptors. 4. It was concluded that in human neutrophil membranes, [3H]-SCH 58261 directly labels binding sites with pharmacological properties similar to those of A2A adenosine receptors of other tissues. The receptors labelled by [3H]-SCH 58261 mediated the effects of adenosine and adenosine receptor agonists to stimulate cyclic AMP accumulation and inhibition of superoxide anion production in human neutrophils.
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Affiliation(s)
- K Varani
- Department of Clinical and Experimental Medicine, University of Ferrara, Italy
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Varani K, Gessi S, Dalpiaz A, Ongini E, Borea PA. Characterization of A2A adenosine receptors in human lymphocyte membranes by [3H]-SCH 58261 binding. Br J Pharmacol 1997; 122:386-92. [PMID: 9313951 PMCID: PMC1564935 DOI: 10.1038/sj.bjp.0701378] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
1. The present study describes for the first time the characterization of the adenosine A2A receptor in human lymphocyte membranes with the new potent and selective antagonist radioligand, [3H]-5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo [4,3-e]-1,2,4 triazolo [1,5-c] pyrimidine, ([3H]-SCH 58261). In addition, both receptor affinity and potency of reference adenosine receptor agonists and antagonists were determined in binding and adenylyl cyclase studies. 2. Saturation experiments revealed a single class of binding sites with Kd and Bmax values of 0.85 nM and 35 fmol mg-1 protein, respectively. A series of adenosine receptor ligands were found to compete for the binding of 0.8 nM [3H]-SCH 58261 to human lymphocyte membranes with a rank order of potency consistent with that typically found for interactions with the A2A-adenosine receptor. In the adenylyl cyclase assay the same compounds exhibited a rank order of potency similar to that observed in binding experiments. 3. Thermodynamic data indicate that [3H]-SCH 58261 binding to human lymphocytes is entropy and enthalpy-driven, a finding in agreement with the thermodynamic behaviour of antagonists for rat striatal A2A-adenosine receptors. 4. It is concluded that in human lymphocyte membranes [3H]-SCH 58261 directly labels binding sites showing the characteristic properties of the adenosine A2A-receptor. The presence of A2A-receptors in peripheral tissue such as human lymphocytes strongly suggests an important role for adenosine in modulating immune and inflammatory responses.
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Affiliation(s)
- K Varani
- Department of Clinical and Experimental Medicine, University of Ferrara, Italy
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