1
|
Humpert S, Schneider D, Lang M, Schulze A, Neumaier F, Holschbach M, Bier D, Neumaier B. Radiosynthesis and In Vitro Evaluation of [ 11C]tozadenant as Adenosine A 2A Receptor Radioligand. Molecules 2024; 29:1089. [PMID: 38474602 DOI: 10.3390/molecules29051089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 02/23/2024] [Accepted: 02/27/2024] [Indexed: 03/14/2024] Open
Abstract
Tozadenant (4-hydroxy-N-(4-methoxy-7-morpholinobenzo[d]thiazol-2-yl)-4-methylpiperidine-1-carboxamide) is a highly selective adenosine A2A receptor (A2AR) antagonist and a promising lead structure for the development of A2AR-selective positron emission tomography (PET) probes. Although several 18F-labelled tozadenant derivatives showed favorable in vitro properties, recent in vivo PET studies observed poor brain penetration and lower specific binding than anticipated from the in vitro data. While these findings might be attributable to the structural modification associated with 18F-labelling, they could also reflect inherent properties of the parent compound. However, PET studies with radioisotopologues of tozadenant to evaluate its cerebral pharmacokinetics and brain distribution are still lacking. In the present work, we applied N-Boc-O-desmethyltozadenant as a suitable precursor for the preparation of [O-methyl-11C]tozadenant ([11C]tozadenant) by O-methylation with [11C]methyl iodide followed by acidic deprotection. This approach afforded [11C]tozadenant in radiochemical yields of 18 ± 2%, with molar activities of 50-60 GBq/µmol (1300-1600 mCi/µmol) and radiochemical purities of 95 ± 3%. In addition, in vitro autoradiography in pig and rat brain slices demonstrated the expected striatal accumulation pattern and confirmed the A2AR specificity of the radioligand, making it a promising tool for in vivo PET studies on the cerebral pharmacokinetics and brain distribution of tozadenant.
Collapse
Affiliation(s)
- Swen Humpert
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Daniela Schneider
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Markus Lang
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Annette Schulze
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Felix Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Marcus Holschbach
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Dirk Bier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
| | - Bernd Neumaier
- Forschungszentrum Jülich GmbH, Institute of Neuroscience and Medicine, Nuclear Chemistry (INM-5), Wilhelm-Johnen-Str., 52428 Jülich, Germany
- Institute of Radiochemistry and Experimental Molecular Imaging, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| |
Collapse
|
2
|
Pathophysiological Role and Medicinal Chemistry of A 2A Adenosine Receptor Antagonists in Alzheimer's Disease. Molecules 2022; 27:molecules27092680. [PMID: 35566035 PMCID: PMC9102440 DOI: 10.3390/molecules27092680] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/14/2022] [Accepted: 04/18/2022] [Indexed: 12/20/2022] Open
Abstract
The A2A adenosine receptor is a protein belonging to a family of four GPCR adenosine receptors. It is involved in the regulation of several pathophysiological conditions in both the central nervous system and periphery. In the brain, its localization at pre- and postsynaptic level in striatum, cortex, hippocampus and its effects on glutamate release, microglia and astrocyte activation account for a crucial role in neurodegenerative diseases, including Alzheimer’s disease (AD). This ailment is considered the main form of dementia and is expected to exponentially increase in coming years. The pathological tracts of AD include amyloid peptide-β extracellular accumulation and tau hyperphosphorylation, causing neuronal cell death, cognitive deficit, and memory loss. Interestingly, in vitro and in vivo studies have demonstrated that A2A adenosine receptor antagonists may counteract each of these clinical signs, representing an important new strategy to fight a disease for which unfortunately only symptomatic drugs are available. This review offers a brief overview of the biological effects mediated by A2A adenosine receptors in AD animal and human studies and reports the state of the art of A2A adenosine receptor antagonists currently in clinical trials. As an original approach, it focuses on the crucial role of pharmacokinetics and ability to pass the blood–brain barrier in the discovery of new agents for treating CNS disorders. Considering that A2A receptor antagonist istradefylline is already commercially available for Parkinson’s disease treatment, if the proof of concept of these ligands in AD is confirmed and reinforced, it will be easier to offer a new hope for AD patients.
Collapse
|
3
|
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.
Collapse
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;
| |
Collapse
|
4
|
Guidolin D, Marcoli M, Tortorella C, Maura G, Agnati LF. Adenosine A 2A-dopamine D 2 receptor-receptor interaction in neurons and astrocytes: Evidence and perspectives. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2019; 169:247-277. [PMID: 31952688 DOI: 10.1016/bs.pmbts.2019.11.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The discovery of receptor-receptor interactions in the early 1980s, together with a more accurate focusing of allosteric mechanisms in proteins, expanded the knowledge on the G protein-coupled receptor (GPCR)-mediated signaling processes. GPCRs were seen to operate not only as monomers, but also as quaternary structures shaped by allosteric interactions. These integrative mechanisms can change the function of the GPCRs involved, leading to a sophisticated dynamic of the receptor assembly in terms of modulation of recognition and signaling. In this context, the heterodimeric complex formed by the adenosine A2A and the dopamine D2 receptors likely represents a prototypical example. The pharmacological evidence obtained, together with the tissue distribution of the A2A-D2 heteromeric complexes, suggested they could represent a target for new therapeutic strategies addressing significant disorders of the central nervous system. The research findings and the perspectives they offer from the therapeutic standpoint are the focus of the here presented discussion.
Collapse
Affiliation(s)
- Diego Guidolin
- Department of Neuroscience, Section of Anatomy, University of Padova, Padova, Italy.
| | - Manuela Marcoli
- Department of Pharmacy and Center of Excellence for Biomedical Research, University of Genova, Genova, Italy
| | - Cinzia Tortorella
- Department of Neuroscience, Section of Anatomy, University of Padova, Padova, Italy
| | - Guido Maura
- Department of Pharmacy and Center of Excellence for Biomedical Research, University of Genova, Genova, Italy
| | - Luigi F Agnati
- Department of Biomedical Sciences, University of Modena and Reggio Emilia, Modena, Italy; Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| |
Collapse
|
5
|
Gonçalves FQ, Lopes JP, Silva HB, Lemos C, Silva AC, Gonçalves N, Tomé ÂR, Ferreira SG, Canas PM, Rial D, Agostinho P, Cunha RA. Synaptic and memory dysfunction in a β-amyloid model of early Alzheimer's disease depends on increased formation of ATP-derived extracellular adenosine. Neurobiol Dis 2019; 132:104570. [PMID: 31394204 DOI: 10.1016/j.nbd.2019.104570] [Citation(s) in RCA: 73] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 07/09/2019] [Accepted: 08/02/2019] [Indexed: 01/01/2023] Open
Abstract
Adenosine A2A receptors (A2AR) overfunction causes synaptic and memory dysfunction in early Alzheimer's disease (AD). In a β-amyloid (Aβ1-42)-based model of early AD, we now unraveled that this involves an increased synaptic release of ATP coupled to an increased density and activity of ecto-5'-nucleotidase (CD73)-mediated formation of adenosine selectively activating A2AR. Thus, CD73 inhibition with α,β-methylene-ADP impaired long-term potentiation (LTP) in mouse hippocampal slices, which is occluded upon previous superfusion with the A2AR antagonist SCH58261. Furthermore, α,β-methylene-ADP did not alter LTP amplitude in global A2AR knockout (KO) and in forebrain neuron-selective A2AR-KO mice, but inhibited LTP amplitude in astrocyte-selective A2AR-KO mice; this shows that CD73-derived adenosine solely acts on neuronal A2AR. In agreement with the concept that ATP is a danger signal in the brain, ATP release from nerve terminals is increased after intracerebroventricular Aβ1-42 administration, together with CD73 and A2AR upregulation in hippocampal synapses. Importantly, this increased CD73 activity is critically required for Aβ1-42 to impair synaptic plasticity and memory since Aβ1-42-induced synaptic and memory deficits were eliminated in CD73-KO mice. These observations establish a key regulatory role of CD73 activity over neuronal A2AR and imply CD73 as a novel target for modulation of early AD.
Collapse
Affiliation(s)
- Francisco Q Gonçalves
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - João P Lopes
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Henrique B Silva
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Cristina Lemos
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - António C Silva
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Nélio Gonçalves
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Ângelo R Tomé
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Samira G Ferreira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Paula M Canas
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Daniel Rial
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal
| | - Paula Agostinho
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; FMUC-Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal; FMUC-Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal.
| |
Collapse
|
6
|
Khanapur S, van Waarde A, Dierckx RAJO, Elsinga PH, Koole MJB. Preclinical Evaluation and Quantification of 18F-Fluoroethyl and 18F-Fluoropropyl Analogs of SCH442416 as Radioligands for PET Imaging of the Adenosine A 2A Receptor in Rat Brain. J Nucl Med 2016; 58:466-472. [PMID: 27789720 DOI: 10.2967/jnumed.116.178103] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 10/02/2016] [Indexed: 11/16/2022] Open
Abstract
The cerebral adenosine A2A receptor is an attractive therapeutic target for neuropsychiatric disorders. 18F-fluoroethyl and 18F-fluoropropyl analogs of 18F-labeled pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (SCH442416) (18F-FESCH and 18F-FPSCH, respectively) were developed as A2A receptor-specific PET ligands. Our aim was to determine an appropriate compartmental model for tracer kinetics, evaluate a reference tissue approach, and select the most suitable PET ligand. Methods: A 90-min dynamic PET scan with arterial blood sampling and metabolite analysis was acquired for 22 healthy male Wistar rats starting at the time of 18F-FESCH (n = 12) and 18F-FPSCH (n = 10) injection. For each tracer, half the animals were vehicle-treated whereas the other half were pretreated with the A2A receptor-selective antagonist KW-6002, inducing full blocking. Regional tissue total volume of distribution (VT) was estimated by 1- and 2-tissue-compartment modeling (1TCM and 2TCM, respectively) and Logan graphical analysis. Midbrain, cerebellum, and hippocampus were evaluated as the reference region by comparing baseline VT with VT under full blocking conditions and comparing striatal nondisplaceable binding potential (BPND) using a simplified reference tissue model (SRTM) with distribution volume ratio minus 1 (DVR - 1) for 60- and 90-min scans. Results: On the basis of the Akaike information criterion, 1TCM and 2TCM were the most appropriate models for 18F-FPSCH (baseline striatal VT, 3.7 ± 1.1) and 18F-FESCH (baseline striatal VT, 5.0 ± 2.0), respectively. Baseline striatal VT did not significantly differ between tracers. After pretreatment, striatal VT was reduced significantly, with no significant decrease in hippocampus, midbrain, or cerebellum VT Baseline striatal SRTM BPND did not differ significantly from DVR - 1 except for 18F-FPSCH when using a 60-min scan and midbrain as the reference region, whereas Bland-Altman analysis found a smaller bias for 18F-FESCH and a 60-min scan. After pretreatment, striatal SRTM BPND did not significantly differ from zero except for 18F-FPSCH when using hippocampus as the reference region. Striatal SRTM BPND using midbrain or cerebellum as the reference region was significantly lower for 18F-FPSCH (range, 1.41-2.62) than for 18F-FESCH (range, 1.64-3.36). Conclusion: Dynamic PET imaging under baseline and blocking conditions determined 18F-FESCH to be the most suitable PET ligand for quantifying A2A receptor expression in the rat brain. Accurate quantification is achieved by a 60-min dynamic PET scan and the use of either cerebellum or midbrain as the reference region.
Collapse
Affiliation(s)
- Shivashankar Khanapur
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and
| | - Aren van Waarde
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and
| | - Rudi A J O Dierckx
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and
| | - Philip H Elsinga
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and
| | - Michel J B Koole
- Department of Nuclear Medicine and Molecular Imaging, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands; and .,Department of Nuclear Medicine and Molecular Imaging, KU Leuven, Leuven, Belgium
| |
Collapse
|
7
|
Khanapur S, Paul S, Shah A, Vatakuti S, Koole MJB, Zijlma R, Dierckx RAJO, Luurtsema G, Garg P, van Waarde A, Elsinga PH. Development of [18F]-labeled pyrazolo[4,3-e]-1,2,4- triazolo[1,5-c]pyrimidine (SCH442416) analogs for the imaging of cerebral adenosine A2A receptors with positron emission tomography. J Med Chem 2014; 57:6765-80. [PMID: 25061687 DOI: 10.1021/jm500700y] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cerebral adenosine A2A receptors (A2ARs) are attractive therapeutic targets for the treatment of neurodegenerative and psychiatric disorders. We developed high affinity and selective compound 8 (SCH442416) analogs as in vivo probes for A2ARs using PET. We observed the A2AR-mediated accumulation of [18F]fluoropropyl ([18F]-10b) and [18F]fluoroethyl ([18F]-10a) derivatives of 8 in the brain. The striatum was clearly visualized in PET and in vitro autoradiography images of control animals and was no longer visible after pretreatment with the A2AR subtype-selective antagonist KW6002. In vitro and in vivo metabolite analyses indicated the presence of hydrophilic (radio)metabolite(s), which are not expected to cross the blood-brain-barrier. [18F]-10b and [18F]-10a showed comparable striatum-to- cerebellum ratios (4.6 at 25 and 37 min post injection, respectively) and reversible binding in rat brains. We concluded that these compounds performed equally well, but their kinetics were slightly different. These molecules are potential tools for mapping cerebral A2ARs with PET.
Collapse
Affiliation(s)
- Shivashankar Khanapur
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen , Groningen, The Netherlands
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Agnati LF, Guidolin D, Leo G, Carone C, Genedani S, Fuxe K. Receptor-receptor interactions: A novel concept in brain integration. Prog Neurobiol 2009; 90:157-75. [PMID: 19850102 DOI: 10.1016/j.pneurobio.2009.10.004] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Revised: 01/29/2009] [Accepted: 10/08/2009] [Indexed: 02/07/2023]
Abstract
A brief historical presentation of the hypothesis on receptor-receptor interactions as an important integrative mechanism taking place at plasma membrane level is given. Some concepts derived from this integrative mechanism especially the possible assemblage of receptors in receptor mosaics (high-order receptor oligomers) and their relevance for the molecular networks associated with the plasma membrane are discussed. In particular, the Rodbell's disaggregation theory for G-proteins is revisited in the frame of receptor mosaic model. The paper also presents some new indirect evidence on A2A;D2 receptor interactions obtained by means of Atomic Force Microscopy on immunogold preparations of A2A and D2 receptors in CHO cells. These findings support previous data obtained by means of computer-assisted confocal laser microscopy. The allosteric control of G-protein coupled receptors is examined in the light of the new views on allosterism and recent data on a homocysteine analogue capable of modulating D2 receptors are shown. Finally, the hypothesis is introduced on the existence of check-points along the amino acid pathways connecting allosteric and orthosteric binding sites of a receptor and their potential importance for drug development.
Collapse
Affiliation(s)
- Luigi F Agnati
- Department of BioMedical Sciences, University of Modena and IRCCS San Camillo, Lido Venezia, Italy.
| | | | | | | | | | | |
Collapse
|
9
|
Albasanz JL, Rodríguez A, Ferrer I, Martín M. Adenosine A2A receptors are up-regulated in Pick's disease frontal cortex. Brain Pathol 2007; 16:249-55. [PMID: 17107593 PMCID: PMC8095809 DOI: 10.1111/j.1750-3639.2006.00026.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Adenosine A2A receptors (A2AR) are highly expressed in striatum. However, they are also present in extrastriatal structures. A2AR were studied in post-mortem human frontal cortex from Pick's disease (PiD) and age-matched non-demented controls by radioligand binding assays, Western-blotting, real-time PCR and adenylyl cyclase activity determination. Saturation binding assay using [3H]ZM 241385, a selective A2A antagonist, as radioligand revealed a significant increase in total adenosine A2AR numbers (Bmax) in frontal cortex from PiD samples (191% of control Bmax), suggesting up-regulation of this receptor. A significant increase in the level of A2AR was also detected by Western-blotting. Furthermore, expression of mRNA coding A2AR determined by quantitative real-time PCR was enhanced. In agreement, stimulation of adenylyl cyclase by CGS 21680, a selective A2A receptor agonist, was significantly strengthened. Up-regulation of A2B receptors and their corresponding mRNA was also observed. These results show that A2A adenosine receptor/adenylyl cyclase transduction pathway is up-regulated and sensitized in frontal cortex brain from PiD.
Collapse
Affiliation(s)
- José Luís Albasanz
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla‐La Mancha, Ciudad Real, Spain
| | - Agustín Rodríguez
- Departamento de Biología Celular y Anatomía Patológica, Facultad de Medicina, Universidad de Barcelona, campus de Bellvitge, and
| | - Isidro Ferrer
- Departamento de Biología Celular y Anatomía Patológica, Facultad de Medicina, Universidad de Barcelona, campus de Bellvitge, and
- Instituto de Neuropatología, Servicio de Anatomía Patológica, IDIBELL‐Hospital Universitario de Bellvitge, Hospitalet de Llobregat, Spain
| | - Mairena Martín
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla‐La Mancha, Ciudad Real, Spain
| |
Collapse
|
10
|
Manera C, Betti L, Cavallini T, Giannaccini G, Martinelli A, Ortore G, Saccomanni G, Trincavelli L, Tuccinardi T, Ferrarini PL. 1,8-Naphthyridin-4-one derivatives as new ligands of A2A adenosine receptors. Bioorg Med Chem Lett 2005; 15:4604-10. [PMID: 16099648 DOI: 10.1016/j.bmcl.2005.06.064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Revised: 06/23/2005] [Accepted: 06/23/2005] [Indexed: 11/26/2022]
Abstract
A series of 1,8-naphthyridine derivatives bearing various substituents in position 3, 4, and 7 of the heterocyclic nucleus have been synthesized and evaluated for their affinity at the bovine and human adenosine receptors. The new compounds were found to lack the affinity toward A(1)AR, whereas many of them are able to acquire an interesting affinity and selectivity for the A(2A)AR.
Collapse
Affiliation(s)
- Clementina Manera
- Dipartimento di Scienze Farmaceutiche, via Bonanno 6, 56126 Pisa, Italy.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Marcoli M, Bonfanti A, Roccatagliata P, Chiaramonte G, Ongini E, Raiteri M, Maura G. Glutamate efflux from human cerebrocortical slices during ischemia: vesicular-like mode of glutamate release and sensitivity to A2A adenosine receptor blockade. Neuropharmacology 2004; 47:884-91. [PMID: 15527822 DOI: 10.1016/j.neuropharm.2004.06.022] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2003] [Revised: 05/07/2004] [Accepted: 06/30/2004] [Indexed: 11/23/2022]
Abstract
Glutamate extracellular accumulation is an early event in brain ischemia triggering excitotoxic neuron damage. We have investigated how to control the glutamate efflux from human cerebrocortical slices superfused in conditions simulating an acute ischemic insult (oxygen and glucose deprivation). The efflux of previously accumulated [3H]D-aspartate or endogenous glutamate increased starting 18 min after exposure to ischemia and returned almost to basal values in 6 min reperfusion with standard medium. Superfusion with Ca2+-free, EGTA (0.5 mM)-containing medium or with medium containing tetrodotoxin (TTX; 0.5 microM) inhibited the ischemia (24 min)-evoked [3H]D-aspartate efflux by about 50% and 65%, respectively. The ischemia (24 or 36 min)-evoked efflux of [3H]D-aspartate or endogenous glutamate was reduced at least 40% by the adenosine A(2A) receptor antagonist SCH 58261 (1 microM); the compound was effective when added up to 15 min after exposure to ischemia. No effect of SCH 58261 on the ischemia-evoked [3H]D-aspartate was found in Ca2+-free, EGTA-containing medium. To conclude, a significant component of the ischemia-evoked glutamate efflux in human cerebrocortical slices seems to occur by a vesicular-like mechanism. Endogenously released adenosine is likely to activate A(2A) receptors that enhance vesicular-like glutamate release during ischemia; A(2A) receptor antagonists would deserve consideration for their neuroprotective potential.
Collapse
Affiliation(s)
- Manuela Marcoli
- Dipartimento di Medicina Sperimentale, Sezione di Farmacologia e Tossicologia, Università di Genova, Viale Cembrano 4, 16148 Genoa, Italy
| | | | | | | | | | | | | |
Collapse
|
12
|
Liang BT, Stewart D, Jacobson KA. Adenosine A1 and A3 receptors: Distinct cardioprotection. Drug Dev Res 2001. [DOI: 10.1002/ddr.1136] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
13
|
Liang BT, Jacobson KA. Adenosine and ischemic preconditioning. Curr Pharm Des 1999; 5:1029-41. [PMID: 10607860 PMCID: PMC3561763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
Adenosine is released in large amounts during myocardial ischemia and is capable of exerting potent cardioprotective effects in the heart. Although these observations on adenosine have been known for a long time, how adenosine acts to achieve its anti-ischemic effect remains incompletely understood. However, recent advances on the chemistry and pharmacology of adenosine receptor ligands have provided important and novel information on the function of adenosine receptor subtypes in the cardiovascular system. The development of model systems for the cardiac actions of adenosine has yielded important insights into its mechanism of action and have begun to elucidate the sequence of signalling events from receptor activation to the actual exertion of its cardioprotective effect. The present review will focus on the adenosine receptors that mediate the potent anti-ischemic effect of adenosine, new ligands at the receptors, potential molecular signalling mechanisms downstream of the receptor, mediators for cardioprotection, and possible clinical applications in cardiovascular disorders.
Collapse
Affiliation(s)
- B T Liang
- Department of Medicine, Cardiovascular Division, University of Pennsylvania Medical Center, Philadelphia, PA 19104, USA.
| | | |
Collapse
|
14
|
Baraldi PG, Cacciari B, Dionisotti S, Egan J, Spalluto G, Zocchi C. Synthesis of the tritium labeled SCH 58261, a new non-xanthine A2A adenosine receptor antagonist. J Labelled Comp Radiopharm 1998. [DOI: 10.1002/(sici)1099-1344(199608)38:8<725::aid-jlcr885>3.0.co;2-g] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
15
|
Kanda T, Tashiro T, Kuwana Y, Jenner P. Adenosine A2A receptors modify motor function in MPTP-treated common marmosets. Neuroreport 1998; 9:2857-60. [PMID: 9760134 DOI: 10.1097/00001756-199808240-00032] [Citation(s) in RCA: 89] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Both adenosine A1 and A2 receptor populations are located in the striatum and can modify locomotor activity, and they may form a therapeutic target for Parkinson's disease (PD). Administration of the selective adenosine A2A antagonist (E)-1,3-diethyl-8-(3,4-dimethoxystyryl)-7-methyl-3,7-dihydro-1H-pu rine-2,6-dione (KW-6002) to MPTP-treated common marmosets increased locomotor activity. In contrast, administration of the selective A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxantine (DPCPX) had no effect on locomotion. Administration of the adenosine A2A receptor agonist 2-[p-[2-(2-aminoethylamino) carbonylethyl] phenethyl amino]-5'-N-ethylcarboxamidoadenosine (APEC) dose dependently suppressed basal locomotor activity. A minimally effective dose of APEC (0.62 mg/kg, i.p) completely reversed the increase in locomotor activity produced by administration of KW-6002. The adenosine A2A receptor appears to be an important target for the treatment of basal ganglia disorders, particularly PD.
Collapse
Affiliation(s)
- T Kanda
- Pharmaceutical Research Institute, Kyowa Hakko Kogyo Co Ltd, Shizuoka, Japan
| | | | | | | |
Collapse
|
16
|
Svenningsson P, Hall H, Sedvall G, Fredholm BB. Distribution of adenosine receptors in the postmortem human brain: an extended autoradiographic study. Synapse 1997; 27:322-35. [PMID: 9372555 DOI: 10.1002/(sici)1098-2396(199712)27:4<322::aid-syn6>3.0.co;2-e] [Citation(s) in RCA: 165] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Whole-hemisphere sections from six subjects were used in a quantitative autoradiographic study to characterize and to investigate the distribution of adenosine receptors, using [3H]DPCPX, [3H]CGS 21680, and [3H]SCH 58261 as radioligands. [3H]DPCPX-binding showed the pharmacology expected for adenosine A1 receptors and is therefore taken to mirror adenosine A1 receptors. Adenosine A1 receptors were widely distributed, with the highest densities in the stratum radiatum/pyramidale of the hippocampal region CA1. Adenosine A1 receptors were nonhomogeneously distributed in nucleus caudatus, globus pallidus, and cortical areas: In the cingulate and frontal cortex the deep layers showed the highest labeling, while in the occipital, parietal, temporal, and insular cortex it was highest in the superficial layers. In addition, we found very high levels of adenosine A1 receptors in structures known to be important for cholinergic transmission, especially the septal nuclei. The Bmax values and KD values for [3H]DPCPX-binding in stratum radiatum/pyramidale of CA1 and the superficial layer of insular cortex were 598 and 430 fmol/mg gray matter and 9.9 and 14.2 nM, respectively. [3H]CGS 21680-binding was multiphasic, but showed the pharmacology expected for adenosine A2A receptors and was taken to represent them. Adenosine A2A receptors were abundant in putamen, nucleus caudatus, nucleus accumbens, and globus pallidus pars lateralis. Specific [3H]CGS 21680-binding was also found in certain thalamic nuclei and throughout the cerebral cortex. The adenosine A2A receptor antagonist radioligand [3H]SCH 58261 was also found to label these extrastriatal structures. Thus, adenosine A2A receptors seem to be more widely distributed in the human brain than previously recognized.
Collapse
Affiliation(s)
- P Svenningsson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden.
| | | | | | | |
Collapse
|
17
|
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.
Collapse
Affiliation(s)
- K Varani
- Department of Clinical and Experimental Medicine, University of Ferrara, Italy
| | | | | | | | | |
Collapse
|
18
|
Jiang Q, Lee BX, Glashofer M, van Rhee AM, Jacobson KA. Mutagenesis reveals structure-activity parallels between human A2A adenosine receptors and biogenic amine G protein-coupled receptors. J Med Chem 1997; 40:2588-95. [PMID: 9258366 PMCID: PMC3449164 DOI: 10.1021/jm970084v] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Structure-affinity relationships for ligand binding at the human A2A adenosine receptor have been probed using site-directed mutagenesis in the transmembrane helical domains (TMs). The mutant receptors were expressed in COS-7 cells and characterized by binding of the radioligands [3H]CGS21680, [3H]NECA, and [3H]XAC. Three residues, at positions essential for ligand binding in other G protein-coupled receptors, were individually mutated. The residue V(3.32) in the A2A receptor that is homologous to the essential aspartate residue of TM3 in the biogenic amine receptors, i.e., V84(3.32), may be substituted with L (present in the A3 receptor) but not with D (in biogenic amine receptors) or A. H250(6.52), homologous to the critical N507 of rat m3 muscarinic acetylcholine receptors, may be substituted with other aromatic residues or with N but not with A (Kim et al. J. Biol. Chem. 1995, 270, 13987-13997). H278(7.43), homologous to the covalent ligand anchor site in rhodopsin, may not be substituted with either A, K, or N. Both V84L(3.32) and H250N(6.52) mutant receptors were highly variable in their effect on ligand competition depending on the structural class of the ligand. Adenosine-5'-uronamide derivatives were more potent at the H250N(6.52) mutant receptor than at wild type receptors. Xanthines tended to be close in potency (H250N(6.52)) or less potent (V84L(3.32)) than at wild type receptors. The affinity of CGS21680 increased as the pH was lowered to 5.5 in both the wild type and H250N(6.52) mutant receptors. Thus, protonation of H250(6.52) is not involved in this pH dependence. These data are consistent with a molecular model predicting the proximity of bound agonist ligands to TM3, TM5, TM6, and TM7.
Collapse
Affiliation(s)
- Qiaoling Jiang
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Brian X. Lee
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Marc Glashofer
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - A. Michiel van Rhee
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| |
Collapse
|
19
|
Belardinelli L, Shryock JC, Ruble J, Monopoli A, Dionisotti S, Ongini E, Dennis DM, Baker SP. Binding of the novel nonxanthine A2A adenosine receptor antagonist [3H]SCH58261 to coronary artery membranes. Circ Res 1996; 79:1153-60. [PMID: 8943953 DOI: 10.1161/01.res.79.6.1153] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
This study demonstrates quantification of A2A adenosine receptors (A2AAdoRs) in membranes prepared from porcine coronary arteries, porcine striatum, and PC12 cells. Radioligand binding assays were performed using the new selective A2AAdoR antagonist radioligand [3H]-5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo [4,3-epsilon]-1,2,4-triazolo[1,5-c)pyrimidine ([3H]SCH58261). Binding of the radioligand to membranes was rapid, reversible, and saturable. The densities of A2AAdoRs in membranes prepared from porcine coronary arteries, porcine striatum, and PC12 cells were 900 +/- 61, 892 +/- 35, and 959 +/- 76 fmol/mg protein, respectively. Equilibrium dissociation constants (Kd values) calculated from results of saturation binding assays were 2.19, 1.20, and 0.81 nmol/L, and Kd values calculated from results of association and dissociation assays were 2.42, 1.01, and 0.40 nmol/L for [3H]SCH58261 binding to membranes prepared from porcine coronary arteries, porcine striatum, and PC12 cells, respectively. The specific binding of [3H]SCH58261 as a percentage of total binding at a radioligand concentration equal to the Kd value was 65% to 90% in the three membrane preparations. The order of ligand potencies determined by assay of competition binding to sites in porcine coronary membranes using [3H]SCH58261, unlabeled antagonists (SCH58261, 8-(3-chlorostyryl)caffeine [CSC], and xanthine amine congener [XAC]), and unlabeled agonists ([3H]2-p-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoaden osine [CGS 21680], 2-hexynyl-5'-N-ethylcarboxamidoadenosine [HE-NECA], [3H]5'-N-ethylcarboxamidoadenosine [NECA], and R(-)N6-(2-phenylisopropyl)adenosine [R-PIA]) was SCH58261 > HE-NECA = CSC = CGS 21680 = XAC > NECA = R-PIA. The Hill coefficients of displacement by A2AAdoR ligands of [3H]SCH58261 binding were not significantly different from unity, indicating that [3H]SCH58261 bound to a group of homogeneous noninteracting sites in all membrane preparations. The order of ligand potencies to compete for [3H]SCH58261 binding sites in porcine striatal and PC12 cell membranes was, in part, different from that for porcine coronary arterial membranes. The different rank orders of potencies for agonists and antagonists at A2A receptors of porcine coronary arteries, striatum, and PC12 cells and significant differences in absolute values of potency of ligands in the three preparations may indicate the existence of different subtypes of A2AAdoRs. The antagonist radio-ligand [3H]SCH58261 should be of value for pharmacological characterization of A2A adenosine receptors in other preparations.
Collapse
Affiliation(s)
- L Belardinelli
- Department of Medicine, College of Medicine, University of Florida, Gainesville 32610-0277, USA
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Zocchi C, Ongini E, Ferrara S, Baraldi PG, Dionisotti S. Binding of the radioligand [3H]-SCH 58261, a new non-xanthine A2A adenosine receptor antagonist, to rat striatal membranes. Br J Pharmacol 1996; 117:1381-6. [PMID: 8730729 PMCID: PMC1909468 DOI: 10.1111/j.1476-5381.1996.tb15296.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
1. The present study describes the binding to rat striatal A2A adenosine receptors of the new potent and selective antagonist radioligand, [3H]-5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazol o [1,5-c] pyrimidine, [3H]-SCH 58261. 2. [3H]-SCH 58261 specific binding to rat striatal membranes ( > 90%) was saturable, reversible and dependent upon protein concentration. Saturation experiments revealed that [3H]-SCH 58261 labelled a single class of recognition sites with high affinity (Kd = 0.70 nM) and limited capacity (apparent Bmax = 971 fmol mg-1 of protein). The presence of 100 microM GTP in the incubation mixture did not modify [3H]-SCH 58261 binding parameters. 3. Competition experiments showed that [3H]-SCH 58261 binding is consistent with the labelling of A2A striatal receptors. Adenosine receptor agonists competed with the binding of 0.2 nM [3H]-SCH 58261 with the following order of potency: 2-hexynyl-5'-N-ethyl carboxamidoadenosine (2HE-NECA) > 5'-N-ethylcarboxamidoadenosine (NECA) > 2-[4-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamidoadenosi ne (CGS 21680) > 2-phenylaminoadenosine (CV 1808) > R-N6-phenylisopropyladenosine (R-PIA) > N6-cyclohexyladenosine (CHA) = 2-chloro-N6-cyclopentyladenosine (CCPA) > S-N6-phenylisopropyladenosine (S-PIA). 4. Adenosine antagonists inhibited [3H]-SCH 58261 binding with the following order: 5-amino-9-chloro-2-(2-furyl)-[1,2,4]-triazolo[1,5-c] quinazoline (CGS 15943) > 5-amino-8-(4-fluorobenzyl)-2-(2-furyl)-pyrazolo [4,3-e]-1,2,4-triazolo [1,5-c] pyrimidine (8FB-PTP) = SCH 58261 > xanthine amine congener (XAC) = (E,18%-Z,82%)7-methyl-8-(3,4-dimethoxystyryl)-1,3-dipropylxanthine (KF 17837S) > 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) > or = 8-phenyltheophylline (8-PT). 5. The Ki values for adenosine antagonists were similar to those labelled with the A2A agonist [3H]-CGS 21680. Affinities of agonists were generally lower. The A1-selective agonist, R-PIA, was found to be about 9 fold more potent than its stereoisomer, S-PIA, thus showing the stereoselectivity of [3H]-SCH 58261 binding. Except for 8-PT, the adenosine agonists and antagonists examined inhibited [3H]-SCH 58261 binding with Hill coefficients not significantly different from unity. 6. The present results indicate that [3H]-SCH 58261 is the first non-xanthine adenosine antagonist radioligand which directly labels A2A striatal receptors. High receptor affinity, good selectivity and very low non-specific binding make [3H]-SCH 58261 an excellent probe for studying the A2A adenosine receptor subtype in mammalian brain.
Collapse
Affiliation(s)
- C Zocchi
- Schering-Plough Research Institute, San Raffaele Science Park, Milan, Italy
| | | | | | | | | |
Collapse
|
21
|
Robeva AS, Woodard R, Luthin DR, Taylor HE, Linden J. Double tagging recombinant A1- and A2A-adenosine receptors with hexahistidine and the FLAG epitope. Development of an efficient generic protein purification procedure. Biochem Pharmacol 1996; 51:545-55. [PMID: 8619901 DOI: 10.1016/0006-2952(95)02235-x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
An expression plasmid for mammalian cells (CLDN10B) has been modified to add nucleotides encoding hexahistidine and the FLAG peptide (H/F) to cDNAs. The new mammalian expression plasmid has been named pDoubleTrouble (pDT). The plasmid and a recombinant baculovirus were used to produce native-and H/F-human A1 and A2A adenosine receptors, optimally expressed in CHO-K1 and Sf9 cells, respectively. Binding to recombinant H/F-A1 receptors (Bmax = 30 pmol/mg protein) was characterized using [3H]8-cyclopentyl-1,3-dipropylxanthine ([3H]CPX) and 125I-N6-aminobenzyladenosine (125I-ABA). Binding to H/F-A2A receptors (Bmax = 48 pmol/mg protein) was characterized using [3H]5'-N-ethylcarboxamidoadenosine ([3H]NECA) and [3H]2-[4-(2-carboxyethyl)phenethylamino]-NECA ([3H]CGS21680). By comparison to native receptors, the addition of H/F to the amino termini of these receptors had no effect on the binding affinities cyclic AMP accumulation in intact cells was not affected by the H/F extension. Anti-FLAG and Ni-nitrilotriacetic acid affinity chromatography resulted in high yield ( >50% overall recovery) of nearly homogeneous deglycosylation with N-glycosidase F. We anticipate that pDT will be generally useful for facilitating the purification in high yield of recombinant receptors and other proteins by single or sequential affinity chromatography steps.
Collapse
Affiliation(s)
- A S Robeva
- Department of Internal Medicine, University of Virginia Health Sciences Center, Charlottesville 22908, USA
| | | | | | | | | |
Collapse
|
22
|
Abstract
Adenosine participates in the physiology of central and peripheral tissues through several subtypes of G-protein-coupled receptors. Positively linked to adenylate cyclase, A2 receptors have been subdivided into A2a and A2b sites on the basis of their molecular, biochemical and pharmacological properties. They exhibit selective distribution, and are implicated in the modulation of psychomotor activity, circulation, respiration, and metabolism. Recent data support the evidence that adenosine A2 receptor properties may prove useful in future drug development, and selective manipulation of receptor-associated biologic effects might be relevant in the treatment of various disorders, including psychiatric diseases, hypoxia/ischemia, inflammation or erythrocytosis.
Collapse
Affiliation(s)
- J L Daval
- INSERM U.272, Université de Nancy I, France
| | | | | |
Collapse
|
23
|
Kim J, Wess J, van Rhee AM, Schöneberg T, Jacobson KA. Site-directed mutagenesis identifies residues involved in ligand recognition in the human A2a adenosine receptor. J Biol Chem 1995; 270:13987-97. [PMID: 7775460 PMCID: PMC3427751 DOI: 10.1074/jbc.270.23.13987] [Citation(s) in RCA: 166] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The A2a adenosine receptor is a member of the G-protein coupled receptor family, and its activation stimulates cyclic AMP production. To determine the residues which are involved in ligand binding, several residues in transmembrane domains 5-7 were individually replaced with alanine and other amino acids. The binding properties of the resultant mutant receptors were determined in transfected COS-7 cells. To study the expression levels in COS-7 cells, mutant receptors were tagged at their amino terminus with a hemagglutinin epitope, which allowed their immunological detection in the plasma membrane by the monoclonal antibody 12CA5. The functional properties of mutant receptors were determined by measuring stimulation of adenylate cyclase. Specific binding of [3H]CGS 21680 (15 nM) and [3H]XAC (4 nM), an A2a agonist and antagonist, respectively, was absent in the following Ala mutants: F182A, H250A, N253A, I274A, H278A, and S281A, although they were well expressed in the plasma membrane. The hydroxy group of Ser-277 is required for high affinity binding of agonists, but not antagonists. An N181S mutant lost affinity for adenosine agonists substituted at N6 or C-2, but not at C-5'. The mutant receptors I274A, S277A, and H278A showed full stimulation of adenylate cyclase at high concentrations of CGS 21680. The functional agonist potencies at mutant receptors that lacked radioligand binding were > 30-fold less than those at the wild type receptor. His-250 appears to be a required component of a hydrophobic pocket, and H-bonding to this residue is not essential. On the other hand, replacement of His-278 with other aromatic residues was not tolerated in ligand binding. Thus, some of the residues targeted in this study may be involved in the direct interaction with ligands in the human A2a adenosine receptor. A molecular model based on the structure of rhodopsin, in which the 5'-NH in NECA is hydrogen bonded to Ser-277 and His-278, was developed in order to visualize the environment of the ligand binding site.
Collapse
Affiliation(s)
- Jeongho Kim
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Jürgen Wess
- Drug Receptor Interaction Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - A. Michiel van Rhee
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Torsten Schöneberg
- Drug Receptor Interaction Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Kenneth A. Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| |
Collapse
|
24
|
Johansson B, Fredholm BB. Further characterization of the binding of the adenosine receptor agonist [3H]CGS 21680 to rat brain using autoradiography. Neuropharmacology 1995; 34:393-403. [PMID: 7566470 DOI: 10.1016/0028-3908(95)00009-u] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
2-[p-(2-carboxyethyl)-phenylethylamino]-5'-N-ethylcarboxamidoadeno sine (CGS 21680) is considered a selective ligand for adenosine A2A receptors, which are known to be enriched in striatum and olfactory tubercle. We have investigated the characteristics of [3H]CGS 21680 binding in several brain regions using quantitative autoradiography. In agreement with previous data the radioligand was found to label the caudate-putamen, accumbens nucleus, olfactory tubercle and globus pallidus, but also many other structures, e.g. cerebral and cerebellar cortex, hippocampus, thalamus and some brainstem nuclei, were labelled. Cortical and striatal binding of [3H]CGS 21680 was unaltered by high concentrations of the adenosine transport inhibitor dipyridamole or the phosphodiesterase inhibitor rolipram but was displaced by 1,3-diethyl-8-phenylxanthine, the A2 selective adenosine antagonist CP 66,713, and the A2A selective agonist SHA 118. These three agents were approximately equipotent in striatum, cortex and hippocampus. The A2 selective agonist CV 1808 was a 4-5 times more potent displacer in cortex and hippocampus than in the striatum. [3H]CGS 21680 binding was strongly magnesium-dependent in all the studied brain regions, in contrast to the binding of adenosine A1 agonists. The binding of [3H]CGS 21680 to cerebral cortex and hippocampus, but not the binding to striatum, was displaced by the adenosine receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine in nanomolar concentrations. The present study provides evidence that in cerebral cortex and hippocampus, most of the [3H]CGS 21680 binds to a receptor site that is distinct from the striatal A2A receptor and the classical adenosine A1 receptor and may represent a hitherto unrecognized binding site.
Collapse
Affiliation(s)
- B Johansson
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | | |
Collapse
|
25
|
Pirotton S, Boeynaems JM. Evidence that ATP, ADP and AMP are not ligands of the striatal adenosine A2A receptors. Eur J Pharmacol 1993; 241:55-61. [PMID: 8223925 DOI: 10.1016/0014-2999(93)90932-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
It has been claimed recently that, in several cell types, ATP can induce a stimulation of cAMP production which is sensitive to methylxanthine inhibition and is not mediated by the ATP degradation product, adenosine. One explanation for these results would be direct activation of adenosine A2 receptors by ATP itself. We have therefore investigated whether adenine nucleotides are ligands of adenosine A2A receptors from bovine striatum. We show here that ATP, ADP, AMP and their phosphorothioates analogues (ATP gamma S, ADP beta S and AMP alpha S), at a 100 microM concentration, produced a 83-91% inhibition of the binding of [3H]CGS21680, an adenosine A2A receptor agonist, to striatum membranes. However, this action was inhibited by adenosine deaminase or by adenosine 5'-O-(alpha, beta-methylene)diphosphate (APCP), an inhibitor of 5'-nucleotidase-mediated AMP degradation. The effects of adenosine deaminase and APCP were dependent on their concentration. These results indicate that ATP, ADP and even AMP can exert an effect on the adenosine A2A receptors only through their breakdown into adenosine by ectonucleotidases.
Collapse
Affiliation(s)
- S Pirotton
- Institute of Interdisciplinary Research, Free University of Brussels, Belgium
| | | |
Collapse
|
26
|
Ji XD, Jacobson KA. Solubilized rabbit striatal A2a-adenosine receptors: stability and antagonist binding. Arch Biochem Biophys 1993; 305:611-7. [PMID: 8373201 PMCID: PMC4827164 DOI: 10.1006/abbi.1993.1469] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The A2a-adenosine binding subunit from rabbit striatal membranes was solubilized using 1% 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate and was characterized using the antagonist radioligand [3H]8-[4-[[[[2-aminoethyl)amino]carbonyl]methyl]oxy] phenyl]-1,3-dipropylxanthine (XAC). The solubilized receptor was very stable, with 55% of the specific [3H]XAC binding remaining after storage for 15 days at 4 degrees C. The dissociation constant (Kd) for binding of [3H]XAC to solubilized A2 receptors was determined in saturation studies to be 4.0 nM, with a Bmax of 600 fmol/mg protein. Xanthine inhibitors displaced the specific binding of the adenosine antagonist [3H]XAC (in the presence of 50 nM 8-cyclopentyl-1,3-dipropylxanthine) at 25 degrees C, with Ki values consonant with the expected affinities at A2a receptors. Binding of [3H]XAC (1 nM) or the adenosine agonist [3H]2-(carboxyethylphenylethylamino)adenosine-5'-N-ethyl carboxamide (5 nM) to A2a receptors was diminished in the presence of 0.1 M Na+ in both membranes and solubilized preparations. Agonist binding was increased (by 280% for membranes and 180% for solubilized receptors), and antagonist binding was decreased in the presence of 10 mM Mg2+. Displacement of [3H]XAC by the agonist (R)-N6-phenylisopropyladenosine was biphasic, corresponding to high (IC50 = 188 nM, RH = 30%) and low (IC50 = 9730 nM, RL = 70%) affinity sites. Preincubation with 100 microM GTP (10 mM Mg2+) converted the high affinity binding to low affinity, suggesting that receptor and G-protein are dissociated by the guanine nucleotide. The solubilized receptor was more easily inactivated by exposure to the reducing agent dithiothreitol (IC50 = 3 mM) than in membranes (IC50 = 220 mM), suggesting increased accessibility of structurally essential disulfide bridges.
Collapse
Affiliation(s)
- X D Ji
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | | |
Collapse
|
27
|
Jacobson KA, Gallo-Rodriguez C, Melman N, Fischer B, Maillard M, van Bergen A, van Galen PJ, Karton Y. Structure-activity relationships of 8-styrylxanthines as A2-selective adenosine antagonists. J Med Chem 1993; 36:1333-42. [PMID: 8496902 PMCID: PMC5975975 DOI: 10.1021/jm00062a005] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A series of substituted 8-styryl derivatives of 1,3,7-alkylxanthines was synthesized as potential A2-selective adenosine receptor antagonists, and the potency at rat brain A1- and A2-receptors was studied in radioligand binding experiments. At the xanthine 7-position, only small hydrophobic substituents were tolerated in receptor binding. 7-Methyl analogues were roughly 1 order of magnitude more selective for A2 versus A1 receptors than the corresponding 7-H analogues. 1,3-Dimethylxanthine derivatives tended to be more selective for A2-receptors than the corresponding 1,3-diallyl, diethyl, or dipropyl derivatives. Substitutions of the phenyl ring at the 3-(monosubstituted) and 3,5-(disubstituted) positions were favored. 1,3, 7-Trimethyl-8-(3-chlorostyryl)xanthine was a moderately potent (Ki vs [3H]CGS 21680 was 54 nM) and highly A2-selective (520-fold) adenosine antagonist. 1,3,7-Trimethyl-8-[(3-carboxy-1-oxopropyl)amino] styryl]xanthine was highly A2-selective (250-fold) and of enhanced water solubility (max 19 mM). 1,3-Dipropyl-7-methyl-8-(3,5-dimethoxystyryl) xanthine was a potent (Ki = 24 nM) and very A2-selective (110-fold) adenosine antagonist.
Collapse
Affiliation(s)
- K A Jacobson
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes, and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Jacobson KA, van Galen PJM, Ji XD, Ramkumar V, Olah ME, Stiles GL. Molecular Characterization of A(1) and A(2a) Adenosine Receptors. Drug Dev Res 1993; 28:226-231. [PMID: 23002320 PMCID: PMC3446818 DOI: 10.1002/ddr.430280307] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Detailed amino acid sequence analyses of A(1) and A(2a) adenosine receptors were assembled by analogy to other G-protein-coupled receptors and correlated with pharmacological observations. Sites for phosphorylation, palmitoylation, and sodium binding have been proposed. Striatal A(2a) receptors from human and other species were photoaffinity-labeled using the selective, radioiodinated agonist PAPA-APEC. Selective chemical affinity labels for A(1) and A(2a) receptors have been introduced. For example, an isothiocyanate, p-DITC-APEC (100 nM), irreversibly diminished the B(max) for [(3)H]CGS 21680 (2-[4-[(2-carboxyethyl) phenyl] ethylamino]-5'-N-ethylcarboxamidoadenosine) binding in rabbit striatal membranes by 71% (K(d) unaffected), suggesting a direct modification of the ligand binding site. Novel trifunctional affinity labels have been designed. Rabbit and human A(2a) receptors were characterized using [(3)H]XAC binding in the presence of 50 or 25 nM CPX (8-cyclopentyl-l,3-dipropylxanthine), respectively. The inhibition of A(2) radioligand binding by the histidyl-modifying reagent diethylpyrocarbonate suggested the involvement of His residues in interactions with adenosine agonists and antagonists. Properties of transiently expressed mutants of bovine A(1) receptors in which either His(251) or His(278) residues have been substituted with Leu suggest that both histidines are important in binding.
Collapse
Affiliation(s)
- Kenneth A Jacobson
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive Diseases and Kidney Diseases, National Institutes of Health, Bethesda, Maryland (K.A.J., P.J. M.v.C., X.-D.J.); Department of Medicine, Duke University Medical Center, Durham, North Carolina (V. R., M.E.O., G.L.S.)
| | | | | | | | | | | |
Collapse
|
29
|
van Galen PJ, Stiles GL, Michaels G, Jacobson KA. Adenosine A1 and A2 receptors: structure--function relationships. Med Res Rev 1992; 12:423-71. [PMID: 1513184 PMCID: PMC3448285 DOI: 10.1002/med.2610120502] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- P J van Galen
- Laboratory of Bioorganic Chemistry, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892
| | | | | | | |
Collapse
|
30
|
Eidelman O, Guay-Broder C, van Galen PJ, Jacobson KA, Fox C, Turner RJ, Cabantchik ZI, Pollard HB. A1 adenosine-receptor antagonists activate chloride efflux from cystic fibrosis cells. Proc Natl Acad Sci U S A 1992; 89:5562-6. [PMID: 1376923 PMCID: PMC49332 DOI: 10.1073/pnas.89.12.5562] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A1 adenosine-receptor-antagonist drugs such as 8-cyclopentyl-1,3-dipropylxanthine (CPX) and xanthine amine congener (XAC) are found to activate the efflux of 36Cl- from CFPAC cells. These cells are a pancreatic adenocarcinoma cell line derived from a cystic fibrosis (CF) patient homozygous for the common mutation, deletion of Phe-508. The active concentrations for these compounds are in the low nanomolar range, consistent with action on A1 adenosine receptors. In addition, drug action can be blocked by exogenous agonists such as 2-chloroadenosine and also can be antagonized by removal of endogenous agonists by treatment with adenosine deaminase. Cells lacking the CF genotype and phenotype, such as HT-29 and T84 colon carcinoma cell lines, appear to be resistant to activation of chloride efflux by either drug. CFPAC cells transfected with the CF transmembrane regulator gene, CFTR, are also resistant to activation by CPX. We conclude that, since these antagonists are of relatively low toxicity and appear to act somewhat selectively, they might be considered as promising therapeutic candidates for CF.
Collapse
Affiliation(s)
- O Eidelman
- Clinical Investigations and Patient Care Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, MD 20892
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Jacobson KA, van Galen PJ, Williams M. Adenosine receptors: pharmacology, structure-activity relationships, and therapeutic potential. J Med Chem 1992; 35:407-22. [PMID: 1738138 PMCID: PMC3476067 DOI: 10.1021/jm00081a001] [Citation(s) in RCA: 351] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- K A Jacobson
- Laboratory of Bioorganic Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | | | | |
Collapse
|