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Atif M, Alsrhani A, Naz F, Ullah MI, Alameen AAM, Imran M, Ejaz H. Adenosine A 2A receptor as a potential target for improving cancer immunotherapy. Mol Biol Rep 2022; 49:10677-10687. [PMID: 35752699 DOI: 10.1007/s11033-022-07685-7] [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: 04/26/2022] [Accepted: 06/07/2022] [Indexed: 11/29/2022]
Abstract
The adenosine nucleoside performs a wide range of actions on various human tissues by activating four cell surface receptors. Adenosine A2A receptors (A2ARs) are widely expressed in the striatum, olfactory bulb, platelets, leukocytes, spleen, and thymus. They promote vasodilatation, platelet antiaggregatory effect, protection from ischemic damage, and regulation of sensorimotor neurons in basal ganglia. Adenosine signaling plays a vital part in modulating in vivo pathophysiological responses. A2ARs are potent negative regulators of the antitumor and proinflammatory actions of activated T cells. This axis offers several therapeutic targets, the most important of which are A2ARs, HIF-1α, and CD39/CD73. Downregulation of this axis increases the effectiveness of modern immunotherapeutic approaches against cancer, such as αCTLA-4/αPD-1. These discoveries have led to a promising novel role of antagonists of A2AR in blocking angiogenesis in immunotherapy of cancer. A small molecule, AZD4635, strongly inhibits A2AR, lowering cancer volume and increasing anticancer immunity. Deletion of A2AR with CRISPR/Cas9 in both human and murine CAR T cells produces a substantial increase in the efficiency of these cells. This review asserts that inhibition of the adenosinergic pathway can boost antitumor immunity, and this axis should be a target for future immunotherapeutic strategies.
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Affiliation(s)
- Muhammad Atif
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Al Jouf, 72388, Saudi Arabia
| | - Abdullah Alsrhani
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Al Jouf, 72388, Saudi Arabia
| | - Farrah Naz
- Department of Pathology, Institute of Public Health, Lahore, Pakistan
| | - Muhammad Ikram Ullah
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Al Jouf, 72388, Saudi Arabia
| | - Ayman Ali Mohammed Alameen
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Al Jouf, 72388, Saudi Arabia
| | - Muhammad Imran
- Department of Food Science and Technology, University of Narowal, Narowal, Pakistan
| | - Hasan Ejaz
- Department of Clinical Laboratory Sciences, College of Applied Medical Sciences, Jouf University, Al Jouf, 72388, Saudi Arabia.
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Korkutata M, Agrawal L, Lazarus M. Allosteric Modulation of Adenosine A 2A Receptors as a New Therapeutic Avenue. Int J Mol Sci 2022; 23:ijms23042101. [PMID: 35216213 PMCID: PMC8880556 DOI: 10.3390/ijms23042101] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 02/11/2022] [Accepted: 02/11/2022] [Indexed: 12/26/2022] Open
Abstract
The therapeutic potential of targeting adenosine A2A receptors (A2ARs) is immense due to their broad expression in the body and central nervous system. The role of A2ARs in cardiovascular function, inflammation, sleep/wake behaviors, cognition, and other primary nervous system functions has been extensively studied. Numerous A2AR agonist and antagonist molecules are reported, many of which are currently in clinical trials or have already been approved for treatment. Allosteric modulators can selectively elicit a physiologic response only where and when the orthosteric ligand is released, which reduces the risk of an adverse effect resulting from A2AR activation. Thus, these allosteric modulators have a potential therapeutic advantage over classical agonist and antagonist molecules. This review focuses on the recent developments regarding allosteric A2AR modulation, which is a promising area for future pharmaceutical research because the list of existing allosteric A2AR modulators and their physiologic effects is still short.
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Affiliation(s)
- Mustafa Korkutata
- Department of Neurology, Division of Sleep Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA;
| | - Lokesh Agrawal
- Molecular Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Kunigami-gun, Onna 904-0412, Japan;
| | - Michael Lazarus
- International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba 305-8575, Japan
- Correspondence: ; Tel.: +81-29-853-3681
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Coppi E, Dettori I, Cherchi F, Bulli I, Venturini M, Lana D, Giovannini MG, Pedata F, Pugliese AM. A 2B Adenosine Receptors: When Outsiders May Become an Attractive Target to Treat Brain Ischemia or Demyelination. Int J Mol Sci 2020; 21:E9697. [PMID: 33353217 PMCID: PMC7766015 DOI: 10.3390/ijms21249697] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 12/16/2020] [Accepted: 12/16/2020] [Indexed: 12/14/2022] Open
Abstract
Adenosine is a signaling molecule, which, by activating its receptors, acts as an important player after cerebral ischemia. Here, we review data in the literature describing A2BR-mediated effects in models of cerebral ischemia obtained in vivo by the occlusion of the middle cerebral artery (MCAo) or in vitro by oxygen-glucose deprivation (OGD) in hippocampal slices. Adenosine plays an apparently contradictory role in this receptor subtype depending on whether it is activated on neuro-glial cells or peripheral blood vessels and/or inflammatory cells after ischemia. Indeed, A2BRs participate in the early glutamate-mediated excitotoxicity responsible for neuronal and synaptic loss in the CA1 hippocampus. On the contrary, later after ischemia, the same receptors have a protective role in tissue damage and functional impairments, reducing inflammatory cell infiltration and neuroinflammation by central and/or peripheral mechanisms. Of note, demyelination following brain ischemia, or autoimmune neuroinflammatory reactions, are also profoundly affected by A2BRs since they are expressed by oligodendroglia where their activation inhibits cell maturation and expression of myelin-related proteins. In conclusion, data in the literature indicate the A2BRs as putative therapeutic targets for the still unmet treatment of stroke or demyelinating diseases.
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Affiliation(s)
- Elisabetta Coppi
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy; (I.D.); (F.C.); (I.B.); (M.V.); (F.P.); (A.M.P.)
| | - Ilaria Dettori
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy; (I.D.); (F.C.); (I.B.); (M.V.); (F.P.); (A.M.P.)
| | - Federica Cherchi
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy; (I.D.); (F.C.); (I.B.); (M.V.); (F.P.); (A.M.P.)
| | - Irene Bulli
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy; (I.D.); (F.C.); (I.B.); (M.V.); (F.P.); (A.M.P.)
| | - Martina Venturini
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy; (I.D.); (F.C.); (I.B.); (M.V.); (F.P.); (A.M.P.)
| | - Daniele Lana
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, 50139 Florence, Italy; (D.L.); (M.G.G.)
| | - Maria Grazia Giovannini
- Department of Health Sciences, Section of Clinical Pharmacology and Oncology, University of Florence, 50139 Florence, Italy; (D.L.); (M.G.G.)
| | - Felicita Pedata
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy; (I.D.); (F.C.); (I.B.); (M.V.); (F.P.); (A.M.P.)
| | - Anna Maria Pugliese
- Department of Neuroscience, Psychology, Drug Research and Child Health (NEUROFARBA), Section of Pharmacology and Toxicology, University of Florence, 50139 Florence, Italy; (I.D.); (F.C.); (I.B.); (M.V.); (F.P.); (A.M.P.)
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Yu F, Zhu C, Xie Q, Wang Y. Adenosine A 2A Receptor Antagonists for Cancer Immunotherapy. J Med Chem 2020; 63:12196-12212. [PMID: 32667814 DOI: 10.1021/acs.jmedchem.0c00237] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Currently, the most promising therapeutic modality for cancer treatment is the blockade of immune checkpoint pathways, which has revolutionized cancer therapy in the past 15 years. Strategies targeting and modulating adenosine A2A receptor (A2AR), an emerging alternative immune checkpoint, have shown the potential to produce significant therapeutic effects. In this review, we describe the immunosuppressive activities of A2AR and A2BR in the tumor microenvironment (TME), followed by a summary and discussion of the structure-activity relationship (SAR) of the A2AR (and dual A2AR/A2BR) antagonists that have been experimentally confirmed to exert oncoimmunological effects. This review also provides an update on the compounds under clinical evaluation and insights into the ligand binding modes of the receptor.
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Affiliation(s)
- Fazhi Yu
- Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China
| | - Chenyu Zhu
- Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China
| | - Qiong Xie
- Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China
| | - Yonghui Wang
- Department of Medicinal Chemistry, School of Pharmacy, Fudan University, 826 Zhangheng Road, Shanghai 201203, China
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Santiago AR, Madeira MH, Boia R, Aires ID, Rodrigues-Neves AC, Santos PF, Ambrósio AF. Keep an eye on adenosine: Its role in retinal inflammation. Pharmacol Ther 2020; 210:107513. [PMID: 32109489 DOI: 10.1016/j.pharmthera.2020.107513] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Adenosine is an endogenous purine nucleoside ubiquitously distributed throughout the body that interacts with G protein-coupled receptors, classified in four subtypes: A1R, A2AR, A2BR and A3R. Among the plethora of functions of adenosine, it has been increasingly recognized as a key mediator of the immune response. Neuroinflammation is a feature of chronic neurodegenerative diseases and contributes to the pathophysiology of several retinal degenerative diseases. Animal models of retinal diseases are helping to elucidate the regulatory roles of adenosine receptors in the development and progression of those diseases. Mounting evidence demonstrates that the adenosinergic system is altered in the retina during pathological conditions, compromising retinal physiology. This review focuses on the roles played by adenosine and the elements of the adenosinergic system (receptors, enzymes, transporters) in the neuroinflammatory processes occurring in the retina. An improved understanding of the molecular and cellular mechanisms of the signalling pathways mediated by adenosine underlying the onset and progression of retinal diseases will pave the way towards the identification of new therapeutic approaches.
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Affiliation(s)
- Ana Raquel Santiago
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal; Association for Innovation and Biomedical Research on Light and Image (AIBILI), Coimbra, 3000-548 Coimbra, Portugal.
| | - Maria H Madeira
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal; Association for Innovation and Biomedical Research on Light and Image (AIBILI), Coimbra, 3000-548 Coimbra, Portugal
| | - Raquel Boia
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Inês Dinis Aires
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Ana Catarina Rodrigues-Neves
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal
| | - Paulo Fernando Santos
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal; Department of Life Sciences, University of Coimbra, 3000-456 Coimbra, Portugal
| | - António Francisco Ambrósio
- Faculty of Medicine, Coimbra Institute for Clinical and Biomedical Research (iCBR), University of Coimbra, 3000-548 Coimbra, Portugal; Center for Innovative Biomedicine and Biotechnology (CIBB), University of Coimbra, 3000-548 Coimbra, Portugal; Association for Innovation and Biomedical Research on Light and Image (AIBILI), Coimbra, 3000-548 Coimbra, Portugal.
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Huin V, Dhaenens CM, Homa M, Carvalho K, Buée L, Sablonnière B. Neurogenetics of the Human Adenosine Receptor Genes: Genetic Structures and Involvement in Brain Diseases. J Caffeine Adenosine Res 2019. [DOI: 10.1089/caff.2019.0011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Vincent Huin
- University of Lille, INSERM, CHU Lille, UMR-S 1172-JPArc–Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille, France
- CHU Lille, Institut de Biochimie et Biologie moléculaire, Centre de Biologie Pathologie et Génétique, Lille, France
| | - Claire-Marie Dhaenens
- University of Lille, INSERM, CHU Lille, UMR-S 1172-JPArc–Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille, France
- CHU Lille, Institut de Biochimie et Biologie moléculaire, Centre de Biologie Pathologie et Génétique, Lille, France
| | - Mégane Homa
- University of Lille, INSERM, CHU Lille, UMR-S 1172-JPArc–Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille, France
| | - Kévin Carvalho
- University of Lille, INSERM, CHU Lille, UMR-S 1172-JPArc–Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille, France
| | - Luc Buée
- University of Lille, INSERM, CHU Lille, UMR-S 1172-JPArc–Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille, France
| | - Bernard Sablonnière
- University of Lille, INSERM, CHU Lille, UMR-S 1172-JPArc–Centre de Recherche Jean-Pierre AUBERT Neurosciences et Cancer, Lille, France
- CHU Lille, Institut de Biochimie et Biologie moléculaire, Centre de Biologie Pathologie et Génétique, Lille, France
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Vijayamahantesh, Vijayalaxmi. Tinkering with targeting nucleotide signaling for control of intracellular Leishmania parasites. Cytokine 2019; 119:129-143. [PMID: 30909149 DOI: 10.1016/j.cyto.2019.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Revised: 03/12/2019] [Accepted: 03/13/2019] [Indexed: 12/23/2022]
Abstract
Nucleotides are one of the most primitive extracellular signalling molecules across all phyla and regulate a multitude of responses. The biological effects of extracellular nucleotides/sides are mediated via the specific purinergic receptors present on the cell surface. In mammalian system, adenine nucleotides are the predominant nucleotides found in the extracellular milieu and mediate a constellation of physiological functions. In the context of host-pathogen interaction, extracellular ATP is recognized as a danger signal and potentiates the release of pro-inflammatory mediators from activated immune cells, on the other hand, its breakdown product adenosine exerts potential anti-inflammatory and immunosuppressive actions. Therefore, it is increasingly apparent that the interplay between extracellular ATP/adenosine ratios has a significant role in coordinating the regulation of the immune system in health and diseases. Several pathogens express ectonucleotidases on their surface and exploit the purinergic signalling as one of the mechanisms to modulate the host immune response. Leishmania pathogens are one of the most successful intracellular pathogens which survive within host macrophages and manipulate protective Th1 response into disease promoting Th2 response. In this review, we discuss the regulation of extracellular ATP and adenosine levels, the role of ATP/adenosine counter signalling in regulating the inflammation and immune responses during infection and how Leishmania parasites exploit the purinergic signalling to manipulate host response. We also discuss the challenges and opportunities in targeting purinergic signalling and the future prospects.
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Affiliation(s)
- Vijayamahantesh
- Department of Biochemistry, Indian Institute of Science (IISc), Bengaluru, Karnataka, India.
| | - Vijayalaxmi
- Department of Zoology, Karnatak University, Dharwad, Karnataka, India
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Stefanello N, Spanevello RM, Passamonti S, Porciúncula L, Bonan CD, Olabiyi AA, Teixeira da Rocha JB, Assmann CE, Morsch VM, Schetinger MRC. Coffee, caffeine, chlorogenic acid, and the purinergic system. Food Chem Toxicol 2018; 123:298-313. [PMID: 30291944 DOI: 10.1016/j.fct.2018.10.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 09/29/2018] [Accepted: 10/02/2018] [Indexed: 12/14/2022]
Abstract
Coffee is a drink prepared from roasted coffee beans and is lauded for its aroma and flavour. It is the third most popular beverage in the world. This beverage is known by its stimulant effect associated with the presence of methylxanthines. Caffeine, a purine-like molecule (1,3,7 trymetylxantine), is the most important bioactive compound in coffee, among others such as chlorogenic acid (CGA), diterpenes, and trigonelline. CGA is a phenolic acid with biological properties as antioxidant, anti-inflammatory, neuroprotector, hypolipidemic, and hypoglicemic. Purinergic system plays a key role inneuromodulation and homeostasis. Extracellular ATP, other nucleotides and adenosine are signalling molecules that act through their specific receptors, namely purinoceptors, P1 for nucleosides and P2 for nucleotides. They regulate many pathological processes, since adenosine, for instance, can limit the damage caused by ATP in the excitotoxicity from the neuronal cells. The primary purpose of this review is to discuss the effects of coffee, caffeine, and CGA on the purinergic system. This review focuses on the relationship/interplay between coffee, caffeine, CGA, and adenosine, and their effects on ectonucleotidases activities as well as on the modulation of P1 and P2 receptors from central nervous system and also in peripheral tissue.
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Affiliation(s)
- Naiara Stefanello
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil.
| | - Roselia Maria Spanevello
- Programa de Pós Graduação em Bioquímica e Bioprospecção: Centro de Ciências Farmacêuticas, Químicas e de Alimentos, UFPel, Campus Capão do Leão 96010-900, Pelotas, RS, Brazil
| | - Sabina Passamonti
- Dipartimento di Scienze della Vita, Università degli Studi di Trieste, via L. Giorgieri 1, 34127, Trieste, Italy
| | - Lisiane Porciúncula
- Departamento de Bioquímica, UFRGS, 90040-060, Porto Alegre, Rio Grande do Sul, Brazil
| | - Carla Denise Bonan
- Programa de Pós-graduação em Biologia Celular e Molecular Faculdade de Biociências da Pontifícia Universidade Católica do Rio Grande do Sul, PUCRS, Porto Alegre, RS, Brazil
| | | | - João Batista Teixeira da Rocha
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil
| | - Charles Elias Assmann
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil
| | - Vera Maria Morsch
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil
| | - Maria Rosa Chitolina Schetinger
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, UFSM, Camobi, 97105-900, Santa Maria, RS, Brazil.
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Grisshammer R. New approaches towards the understanding of integral membrane proteins: A structural perspective on G protein-coupled receptors. Protein Sci 2017; 26:1493-1504. [PMID: 28547763 DOI: 10.1002/pro.3200] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 05/12/2017] [Accepted: 05/15/2017] [Indexed: 01/12/2023]
Abstract
Three-dimensional structure determination of integral membrane proteins has advanced in unprecedented detail our understanding of mechanistic events of how ion channels, transporters, receptors, and enzymes function. This exciting progress required a tremendous amount of methods development, as exemplified here with G protein-coupled receptors (GPCRs): Optimizing the production of GPCRs in recombinant hosts; increasing the probability of crystal formation using high-affinity ligands, nanobodies, and minimal G proteins for co-crystallization, thus stabilizing receptors into one conformation; using the T4 lysozyme technology and other fusion partners to promote crystal contacts; advancing crystallization methods including the development of novel detergents, and miniaturization and automation of the lipidic cubic phase crystallization method; the concept of conformational thermostabilization of GPCRs; and developing microfocus X-ray synchrotron technologies to analyze small GPCR crystals. However, despite immense progress to explain how GPCRs function, many receptors pose intractable hurdles to structure determination at this time. Three emerging methods, serial femtosecond crystallography, micro electron diffraction, and single particle electron cryo-microscopy, hold promise to overcome current limitations in structural membrane biology.
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Affiliation(s)
- Reinhard Grisshammer
- Department of Health and Human Services, Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Rockville, Maryland, 20852
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Morin N, Morissette M, Grégoire L, Di Paolo T. mGlu5, Dopamine D2 and Adenosine A2A Receptors in L-DOPA-induced Dyskinesias. Curr Neuropharmacol 2017; 14:481-93. [PMID: 26639458 PMCID: PMC4983750 DOI: 10.2174/1570159x14666151201185652] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 11/04/2015] [Accepted: 11/11/2015] [Indexed: 02/07/2023] Open
Abstract
Patients with Parkinson's disease (PD) receiving L-3,4-dihydroxyphenylalanine (L-DOPA, the gold-standard treatment for this disease) frequently develop abnormal involuntary movements, termed L-DOPA-induced dyskinesias (LID). Glutamate overactivity is well documented in PD and LID. An approach to manage LID is to add to L-DOPA specific agents to reduce dyskinesias such as metabotropic glutamate receptor (mGlu receptor) drugs. This article reviews the contribution of mGlu type 5 (mGlu5) receptors in animal models of PD. Several mGlu5 negative allosteric modulators acutely attenuate LID in 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine (MPTP) monkeys and 6-hydroxydopamine(6-OHDA)-lesioned rats. Chronic administration of mGlu5 negative allosteric modulators to MPTP monkeys and 6-OHDA rats also attenuates LID while maintaining the antiparkinsonian effect of L-DOPA. Radioligand autoradiography shows an elevation of striatal mGlu5 receptors of dyskinetic L-DOPA-treated MPTP monkeys but not in those without LID. The brain molecular correlates of the long-term effect of mGlu5 negative allosteric modulators treatments with L-DOPA attenuating development of LID was shown to extend beyond mGlu5 receptors with normalization of glutamate activity in the basal ganglia of L-DOPA-induced changes of NMDA, AMPA, mGlu2/3 receptors and VGlut2 transporter. In the basal ganglia, mGlu5 receptor negative allosteric modulators also normalize the L-DOPA-induced changes of dopamine D2receptors, their associated signaling proteins (ERK1/2 and Akt/GSK3β) and neuropeptides (preproenkephalin, preprodynorphin) as well as the adenosine A2A receptors expression. These results show in animal models of PD reduction of LID with mGlu5 negative allosteric modulation associated with normalization of glutamate, dopamine and adenosine receptors suggesting a functional link of these receptors in chronic treatment with L-DOPA.
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Affiliation(s)
| | | | | | - Thérèse Di Paolo
- Neuroscience Research Unit, Centre de recherche du CHU de Québec, 2705 Laurier Boulevard, Quebec, Qc, Canada, G1V 4G2.
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Waickman AT, Alme A, Senaldi L, Zarek PE, Horton M, Powell JD. Enhancement of tumor immunotherapy by deletion of the A2A adenosine receptor. Cancer Immunol Immunother 2011; 61:917-26. [PMID: 22116345 DOI: 10.1007/s00262-011-1155-7] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Accepted: 11/03/2011] [Indexed: 01/12/2023]
Abstract
The A(2A) adenosine receptor plays a critical and non-redundant role in suppressing inflammation at sites of hypoxia and tissue damage. The tumor microenvironment has high levels of adenosine as a result of hypoxia and ectopic expression of enzymes responsible for the generation of extracellular adenosine. Thus, we sought to determine the ability of A(2A) receptor null mice to immunologically reject tumors. We observed that mice lacking the A(2A) adenosine receptor showed significantly delayed growth of lymphoma cells when compared to WT mice. Furthermore, when immunized with a low dose of tumor or with an irradiated GM-CSF-secreting tumor vaccine, A(2A) receptor null mice showed significantly enhanced protection from a subsequent high-dose challenge from both immunogenic and poorly immunogenic tumor lines. This increase in protection was accompanied by an increase in the number of tumor-antigen-specific CD8 T cells at the vaccine-site draining lymph node. Finally, we found that A(2A) receptor null mice displayed more robust anti-tumor responses than WT mice when they were treated with a soluble B7-DC/Fc fusion protein designed to antagonize B7-H1-mediated co-inhibition. This combinatorial immunotherapy strategy could also be recapitulated with pharmacological A(2A) receptor blockade paired with B7-DC/Fc administration. In light of these data, we believe that blockade of the A(2A) adenosine receptor is an attractive target for tumor immunotherapy that synergizes with other immunomodulatory approaches currently in clinical trials.
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Affiliation(s)
- Adam T Waickman
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Butler TR, Prendergast MA. Neuroadaptations in adenosine receptor signaling following long-term ethanol exposure and withdrawal. Alcohol Clin Exp Res 2011; 36:4-13. [PMID: 21762181 DOI: 10.1111/j.1530-0277.2011.01586.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ethanol affects the function of neurotransmitter systems, resulting in neuroadaptations that alter neural excitability. Adenosine is one such receptor system that is changed by ethanol exposure. The current review is focused on the A(1) and the A(2A) receptor subtypes in the context of ethanol-related neuroadaptations and ethanol withdrawal because these subtypes (i) are activated by basal levels of adenosine, (ii) have been most well-studied for their role in neuroprotection and ethanol-related phenomena, and (iii) are the primary site of action for caffeine in the brain, a substance commonly ingested with ethanol. It is clear that alterations in adenosinergic signaling mediate many of the effects of acute ethanol administration, particularly with regard to motor function and sedation. Further, prolonged ethanol exposure has been shown to produce adaptations in the cell surface expression or function of both A(1) and the A(2A) receptor subtypes, effects that likely promote neuronal excitability during ethanol withdrawal. As a whole, these findings demonstrate a significant role for ethanol-induced adaptations in adenosine receptor signaling that likely influence neuronal function, viability, and relapse to ethanol intake following abstinence.
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Affiliation(s)
- Tracy R Butler
- Department of Psychology, Spinal Cord and Brain Injury Research Center, University of Kentucky, Lexington, USA.
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13
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Dias RB, Ribeiro JA, Sebastião AM. Enhancement of AMPA currents and GluR1 membrane expression through PKA-coupled adenosine A2A receptors. Hippocampus 2010; 22:276-91. [DOI: 10.1002/hipo.20894] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2010] [Indexed: 11/06/2022]
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14
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Nell PG, Albrecht-Küpper B. The adenosine A1 receptor and its ligands. PROGRESS IN MEDICINAL CHEMISTRY 2009; 47:163-201. [PMID: 19328291 DOI: 10.1016/s0079-6468(08)00204-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Peter G Nell
- Global Drug Discovery - Operations, Bayer HealthCare AG, Bayer Schering Pharma, Müllerstrasse 178, 13353 Berlin, Germany
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15
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Cristalli G, Cacciari B, Dal Ben D, Lambertucci C, Moro S, Spalluto G, Volpini R. Highlights on the development of A(2A) adenosine receptor agonists and antagonists. ChemMedChem 2008; 2:260-81. [PMID: 17177231 DOI: 10.1002/cmdc.200600193] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Although significant progress has been made in the past few decades demonstrating that adenosine modulates a variety of physiological and pathophysiological processes through the interaction with four subtypes of a family of cell-surface G-protein-coupled receptors, clinical evaluation of some adenosine receptor ligands has been discontinued. Major problems include side effects due to the wide distribution of adenosine receptors, low brain penetration (which is important for the targeting of CNS diseases), short half-life of compounds, or a lack of effects, in some cases perhaps due to receptor desensitization or to low receptor density in the targeted tissue. Currently, three A(2A) adenosine receptor agonists have begun phase III studies. Two of them are therapeutically evaluated as pharmacologic stress agents and the third proved to be effective in the treatment of acute spinal cord injury (SCI), while avoiding the adverse effects of steroid agents. On the other hand, the great interest in the field of A(2A) adenosine receptor antagonists is related to their application in neurodegenerative disorders, in particular, Parkinson's disease, and some of them are currently in various stages of evaluation. This review presents an update of medicinal chemistry and molecular recognition of A(2A) adenosine receptor agonists and antagonists, and stresses the strong need for more selective ligands at the A(2A) human subtype.
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Affiliation(s)
- Gloria Cristalli
- Dipartimento di Scienze Chimiche, Università di Camerino, Via S. Agostino 1, 62032 Camerino, Italy.
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16
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Brand F, Klutz AM, Jacobson KA, Fredholm BB, Schulte G. Adenosine A(2A) receptor dynamics studied with the novel fluorescent agonist Alexa488-APEC. Eur J Pharmacol 2008; 590:36-42. [PMID: 18603240 DOI: 10.1016/j.ejphar.2008.05.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2008] [Revised: 05/07/2008] [Accepted: 05/22/2008] [Indexed: 11/18/2022]
Abstract
G protein-coupled receptors, such as the adenosine A(2A) receptor, are dynamic proteins, which undergo agonist-dependent redistribution from the cell surface to intracellular membranous compartments, such as endosomes. In order to study the kinetics of adenosine A(2A) receptor redistribution in living cells, we synthesized a novel fluorescent agonist, Alexa488-APEC. Alexa488-APEC binds to adenosine A(2A) (K(i)=149+/-27 nM) as well as A(3) receptors (K(i)=240+/-160 nM) but not to adenosine A(1) receptors. Further, we characterized the dose-dependent increase in Alexa488-APEC-induced cAMP production as well as cAMP response element binding (CREB) protein phosphorylation, verifying the ligand's functionality at adenosine A(2A) but not A(2B) receptors. In live-cell imaging studies, Alexa488-APEC-induced adenosine A(2A) receptor internalization, which was blocked by the competitive reversible antagonist ZM 241385 and hyperosmolaric sucrose. Further, internalized adenosine A(2A) receptors co-localized with clathrin and Rab5, indicating that agonist stimulation promotes adenosine A(2A) receptor uptake through a clathrin-dependent mechanism to Rab5-positive endosomes. The basic characterization of Alexa488-APEC described here showed that it provides a useful tool for tracing adenosine A(2A) receptors in vitro.
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Affiliation(s)
- Frank Brand
- Karolinska Institutet, Department of Physiology & Pharmacology, Sect. Receptor Biology & Signaling, S-171 77 Stockholm, Sweden
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17
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Abstract
The guinea pig has been the most commonly used small animal species in preclinical studies related to asthma and COPD. The primary advantages of the guinea pig are the similar potencies and efficacies of agonists and antagonists in human and guinea pig airways and the many similarities in physiological processes, especially airway autonomic control and the response to allergen. The primary disadvantages to using guinea pigs are the lack of transgenic methods, limited numbers of guinea pig strains for comparative studies and a prominent axon reflex that is unlikely to be present in human airways. These attributes and various models developed in guinea pigs are discussed.
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Affiliation(s)
- Brendan J Canning
- Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
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18
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Baraldi PG, Tabrizi MA, Gessi S, Borea PA. Adenosine Receptor Antagonists: Translating Medicinal Chemistry and Pharmacology into Clinical Utility. Chem Rev 2008; 108:238-63. [DOI: 10.1021/cr0682195] [Citation(s) in RCA: 194] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Pier Giovanni Baraldi
- Departments of Pharmaceutical Sciences and Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Italy
| | - Mojgan Aghazadeh Tabrizi
- Departments of Pharmaceutical Sciences and Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Italy
| | - Stefania Gessi
- Departments of Pharmaceutical Sciences and Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Italy
| | - Pier Andrea Borea
- Departments of Pharmaceutical Sciences and Clinical and Experimental Medicine, Pharmacology Unit and Interdisciplinary Center for the Study of Inflammation, University of Ferrara, Italy
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19
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Russell JM, Stephenson GS, Yellowley CE, Benton HP. Adenosine inhibition of lipopolysaccharide-induced interleukin-6 secretion by the osteoblastic cell line MG-63. Calcif Tissue Int 2007; 81:316-26. [PMID: 17705048 DOI: 10.1007/s00223-007-9060-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 07/06/2007] [Indexed: 12/21/2022]
Abstract
Adenosine is known to inhibit inflammatory responses in many cell systems via a family of purine receptors termed "P1." The P1 family consists of the adenosine receptors (ADORA) of subtypes A(1), A(2a), A(2b), and A(3). In order to assess whether adenosine has anti-inflammatory actions in osteoblastic cells, we investigated its effects on lipopolysaccharide (LPS)-induced interleukin 6 (IL-6) release in an in vitro inflammatory functional response model. We showed that the osteoblastic cell line MG-63 expresses ADORA(1), A(2a), and A(2b) but not A(3). Treatment of MG-63 cells with adenosine and pharmacological ADORA agonist 5'-N-ethylcarboxamidoadenosine or 2-[4-(2-p-carboxyethyl)phenylamino]-5'-N-ethylcarboxamidoadenosine (CGS21680) inhibits LPS-induced IL-6 release. This inhibition was protein kinase A (PKA)-dependent and mimicked by treatment with the adenylate cyclase activator forskolin. Treatment of MG-63 with the ADORA(2a)-specific antagonist ZM241385 partially reversed the inhibitory effects of ADORA stimulation on LPS-induced IL-6 release. Overall, these data suggest that ADORA(2a) is involved in the regulation of LPS-induced IL-6 release, thus illustrating a regulatory role for adenosine receptors in the control of inflammation and potentially osteoclastogenesis and bone resorption.
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Affiliation(s)
- Joseph M Russell
- Department of Veterinary Medicine, Anatomy, Physiology, and Cell Biology, University of California, Davis, CA 95616, USA.
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20
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Sahin M, Saxena A, Joost P, Lewerenz J, Methner A. Induction of Bcl-2 by functional regulation of G-protein coupled receptors protects from oxidative glutamate toxicity by increasing glutathione. Free Radic Res 2007; 40:1113-23. [PMID: 17050165 DOI: 10.1080/10715760600838191] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Glutamate treatment depletes hippocampal HT22 cells of glutathione, which renders the cells incapable to reduce reactive oxygen species and ultimately cumulates in cell death by oxidative stress. HT22 cells resistant to glutamate displayed increased phosphorylation of cAMP-response-element binding (CREB) and decreased ERK1/2 suggestive of differences in signal transmission. We investigated the amount of candidate G-protein-coupled receptors involved in this resistance and found an increase in mRNA for receptors activated by the vasoactive intestinal peptide VIP (VPAC2, 12.6-fold) and glutamate like the metabotropic glutamate receptor mGlu1 (5.3-fold). Treating cells with VIP and glutamate led to the same changes in protein phosphorylation observed in resistant cells and induced the proto-oncogene Bcl-2. Bcl-2 overexpression protected by increasing the amount of intracellular glutathione and Bcl-2 knockdown by small interfering RNAs (siRNA) increased glutamate susceptibility of resistant cells. Other receptors upregulated in this paradigm might represent useful targets in the treatment of neurological diseases associated with oxidative stress.
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Affiliation(s)
- Mert Sahin
- Department of Neurology, Heinrich Heine Universität Düsseldorf, Moorenstreet 5, 40225, Düsseldorf, Germany
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21
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Yan X, Koos BJ, Kruger L, Linden J, Murray TF. Characterization of [125I]ZM 241385 binding to adenosine A2A receptors in the pineal of sheep brain. Brain Res 2006; 1096:30-9. [PMID: 16764836 DOI: 10.1016/j.brainres.2006.04.072] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Revised: 04/04/2006] [Accepted: 04/10/2006] [Indexed: 11/29/2022]
Abstract
Adenosine is a ubiquitous neuromodulator and homeostatic regulator that exerts its physiologic actions through activation of A(1), A(2A), A(2B) and A(3) adenosine receptor subtypes. In the central nervous system, adenosine's action in neurons is manifested in its modulation of tonic inhibitory control. Adenosine released in the brain during hypoxia has critical depressant effects on breathing in fetal and newborn mammals, an action suggested to be mediated by A(2A) receptors in the posteromedial thalamus. In an effort to more accurately define the spatial distribution of adenosine A(2A) receptors in fetal sheep diencephalon, we have used a receptor autoradiographic technique utilizing an iodinated radioligand [(125)I]ZM 241385, which has greater sensitivity and resolution than the tritiated compound. The distribution of ligand binding sites in the fetal sheep diencephalon indicated that the highest levels of binding were in select thalamic nuclei, including those implicated in hypoxic depression of fetal breathing, and the pineal. Given the high density of labeled A(2A) receptors in the pineal, these sites were characterized more fully in homogenate radioligand binding assays. These data indicate that [(125)I]ZM 241385 binding sites display a pharmacological signature consistent with that of adenosine A(2A) receptors and are expressed at similar levels in fetal, lamb and adult ovine brain. The adenosine A(2A) receptor pharmacologic signature of the [(125)I]ZM 241385 binding site in pineal cell membranes generalized to the site characterized in membranes derived from other portions of the lamb thalamus, including the sector involved in hypoxic inhibition of fetal breathing. These results have important implications for the functional roles of adenosine A(2A) receptors in the thalamus and pineal of sheep brain.
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Affiliation(s)
- X Yan
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE 68178, USA
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22
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Moro S, Gao ZG, Jacobson KA, Spalluto G. Progress in the pursuit of therapeutic adenosine receptor antagonists. Med Res Rev 2006; 26:131-59. [PMID: 16380972 PMCID: PMC9194718 DOI: 10.1002/med.20048] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Ever since the discovery of the hypotensive and bradycardiac effects of adenosine, adenosine receptors continue to represent promising drug targets. First, this is due to the fact that the receptors are expressed in a large variety of tissues. In particular, the actions of adenosine (or methylxanthine antagonists) in the central nervous system, in the circulation, on immune cells, and on other tissues can be beneficial in certain disorders. Second, there exists a large number of ligands, which have been generated by introducing several modifications in the structure of the lead compounds (adenosine and methylxanthine), some of them highly specific. Four adenosine receptor subtypes (A1, A2A, A2B, and A3) have been cloned and pharmacologically characterized, all of which are G protein-coupled receptors. Adenosine receptors can be distinguished according to their preferred mechanism of signal transduction: A1 and A3 receptors interact with pertussis toxin-sensitive G proteins of the Gi and Go family; the canonical signaling mechanism of the A2A and of the A2B receptors is stimulation of adenylyl cyclase via Gs proteins. In addition to the coupling to adenylyl cyclase, all four subtypes may positively couple to phospholipase C via different G protein subunits. The development of new ligands, in particular, potent and selective antagonists, for all subtypes of adenosine receptors has so far been directed by traditional medicinal chemistry. The availability of genetic information promises to facilitate understanding of the drug-receptor interaction leading to the rational design of a potentially therapeutically important class of drugs. Moreover, molecular modeling may further rationalize observed interactions between the receptors and their ligands. In this review, we will summarize the most relevant progress in developing new therapeutic adenosine receptor antagonists.
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Affiliation(s)
- Stefano Moro
- Molecular Modeling Section, Dipartimento di Scienze Farmaceutiche, Università di Padova, Via Marzolo 5, I-35131 Padova, Italy.
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23
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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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24
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Press NJ, Taylor RJ, Fullerton JD, Tranter P, McCarthy C, Keller TH, Brown L, Cheung R, Christie J, Haberthuer S, Hatto JDI, Keenan M, Mercer MK, Press NE, Sahri H, Tuffnell AR, Tweed M, Fozard JR. A new orally bioavailable dual adenosine A2B/A3 receptor antagonist with therapeutic potential. Bioorg Med Chem Lett 2005; 15:3081-5. [PMID: 15876531 DOI: 10.1016/j.bmcl.2005.04.021] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Revised: 03/30/2005] [Accepted: 04/14/2005] [Indexed: 11/17/2022]
Abstract
The synthesis and SAR of 5-heterocycle-substituted aminothiazole adenosine receptor antagonists is described. Several compounds show high affinity and selectivity for the A2B and A3 receptors. One compound (5f) shows good ADME properties in the rat and as such may be an important new compound in testing the current hypotheses proposing a therapeutic role for a dual A2B/A3 antagonist in allergic diseases.
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Affiliation(s)
- Neil J Press
- Novartis Institutes for Biomedical Research, Respiratory Diseases Area, Wimblehurst Road, Horsham, West Sussex RH12 5AB, UK.
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25
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Xu K, Bastia E, Schwarzschild M. Therapeutic potential of adenosine A2A receptor antagonists in Parkinson's disease. Pharmacol Ther 2005; 105:267-310. [PMID: 15737407 DOI: 10.1016/j.pharmthera.2004.10.007] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Accepted: 10/14/2004] [Indexed: 10/26/2022]
Abstract
In the pursuit of improved treatments for Parkinson's disease (PD), the adenosine A(2A) receptor has emerged as an attractive nondopaminergic target. Based on the compelling behavioral pharmacology and selective basal ganglia expression of this G-protein-coupled receptor, its antagonists are now crossing the threshold of clinical development as adjunctive symptomatic treatment for relatively advanced PD. The antiparkinsonian potential of A(2A) antagonism has been boosted further by recent preclinical evidence that A(2A) antagonists might favorably alter the course as well as the symptoms of the disease. Convergent epidemiological and laboratory data have suggested that A(2A) blockade may confer neuroprotection against the underlying dopaminergic neuron degeneration. In addition, rodent and nonhuman primate studies have raised the possibility that A(2A) receptor activation contributes to the pathophysiology of dyskinesias-problematic motor complications of standard PD therapy--and that A(2A) antagonism might help prevent them. Realistically, despite being targeted to basal ganglia pathophysiology, A(2A) antagonists may be expected to have other beneficial and adverse effects elsewhere in the central nervous system (e.g., on mood and sleep) and in the periphery (e.g., on immune and inflammatory processes). The thoughtful design of new clinical trials of A(2A) antagonists should take into consideration these counterbalancing hopes and concerns and may do well to shift toward a broader set of disease-modifying as well as symptomatic indications in early PD.
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Affiliation(s)
- Kui Xu
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, 114 16th Street, Charlestown, MA 02129, USA
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26
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Fredholm BB, Chen JF, Cunha RA, Svenningsson P, Vaugeois JM. Adenosine and Brain Function. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 63:191-270. [PMID: 15797469 DOI: 10.1016/s0074-7742(05)63007-3] [Citation(s) in RCA: 500] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Bertil B Fredholm
- Department of Physiology and Pharmacology, Karolinska Institutet Stockholm, Sweden
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27
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Yu L, Frith MC, Suzuki Y, Peterfreund RA, Gearan T, Sugano S, Schwarzschild MA, Weng Z, Fink JS, Chen JF. Characterization of genomic organization of the adenosine A2A receptor gene by molecular and bioinformatics analyses. Brain Res 2004; 1000:156-73. [PMID: 15053963 DOI: 10.1016/j.brainres.2003.11.072] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2003] [Indexed: 11/21/2022]
Abstract
The adenosine A(2A) receptor (A(2A)R) is abundantly expressed in brain and emerging as an important therapeutic target for Parkinson's disease and potentially other neuropsychiatric disorders. To understand the molecular mechanisms of A(2A)R gene expression, we have characterized the genomic organization of the mouse and human A(2A)R genes by molecular and bioinformatic analyses. Three new exons (m1A, m1B and m1C) encoding the 5' untranslated regions (5'-UTRs) of mouse A(2A)R mRNA were identified by rapid amplification of 5' cDNA end (5' RACE), RT-PCR analysis and genome sequence analyses. Similar bioinformatics analysis also suggested six variants of the non-coding "exon 1" (h1A, h1B, h1C, h1D, h1E and h1F) in the human A(2A)R gene, which were confirmed by RT-PCR analysis, while three of the human exon 1 variants (h1D, h1E and h1F) were likewise verified by 5' oligonucleotide capping analysis suggesting multiple transcription start sites. Importantly, RT-PCR and quantitative PCR analysis demonstrated that the A(2A)R transcripts with different exon 1 variants displayed tissue-specific expression patterns. For instance, the mouse exon m1A mRNA was detected only in brain (specifically striatum) and the human exon h1D mRNA in lymphoreticular system. Furthermore, the determination of the three new transcription start sites of human A(2A)R gene by 5' oligonucleotide capping and bioinformatics analyses led to the identification of three corresponding promoter regions which contain several important cis elements, providing additional target for further molecular dissection of A(2A)R gene expression. Finally, our analysis indicates that A(2A)R mRNA and a novel transcript partially overlapping with the 3' exon h3, but in opposite orientation to the A(2A)R gene, could conceivably form duplexes to mutually regulate transcript expression. Thus, combined molecular and bioinformatics analyses revealed a new A(2A)R genomic structure, with conserved coding exons 2 and 3 and divergent, tissue-specific exon 1 variants encoding for 5'-UTR. This raises the possibility of generating multiple tissue-specific A(2A)R mRNA species by alternative promoters with varying regulatory susceptibility.
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Affiliation(s)
- Liqun Yu
- Department of Neurology, Boston University School of Medicine, 715 Albany Street, Boston, MA 02118, USA
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28
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Tel BC, Zeng BY, Cannizzaro C, Pearce RKB, Rose S, Jenner P. Alterations in striatal neuropeptide mRNA produced by repeated administration of L-DOPA, ropinirole or bromocriptine correlate with dyskinesia induction in MPTP-treated common marmosets. Neuroscience 2003; 115:1047-58. [PMID: 12453478 DOI: 10.1016/s0306-4522(02)00535-3] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Chronic administration of L-DOPA to MPTP-treated common marmosets induces marked dyskinesia while repeated administration of equivalent antiparkisonian doses of ropinirole and bromocriptine produces only mild involuntary movements. The occurrence of dyskinesia has been associated with an altered balance between the direct and indirect striatal output pathways. Using in situ hybridisation histochemistry, we now compare the effects of these drug treatments on striatal preproenkephalin-A (PPE-A) and adenosine A(2a) receptor mRNA expression as markers of the indirect pathway and striatal preprotachykinin (PPT) mRNA and preproenkephalin-B (PPE-B, prodynorphin) mRNA expression as markers of the direct pathway.The equivalent marked losses of specific [3H]mazindol binding in the striatum of all drug treatment groups confirmed the identical nature of the nigral cell loss produced by MPTP treatment. MPTP-induced destruction of the nigro-striatal pathway markedly increased the level of PPE-A mRNA in the caudate nucleus and putamen and decreased the levels of PPT and PPE-B mRNA relative to normal animals. Repeated treatment with L-DOPA for 30 days produced marked dyskinesia but had no effect on the MPTP-induced increase in PPE-A mRNA in the caudate nucleus and putamen. In contrast, L-DOPA treatment normalised the MPTP-induced decrease in the level of PPT and PPE-B mRNA. Repeated treatment with ropinirole produced little or no dyskinesia but markedly reversed the MPTP-induced elevation in PPE-A mRNA in the caudate nucleus and putamen. However, it had no effect on the decrease in PPT or PPE-B mRNA. Similarly, bromocriptine treatment which induced only mild dyskinesia attenuated the MPTP-induced elevation in PPE-A mRNA in the caudate nucleus and putamen with no effect on reduced striatal PPT or PPE-B mRNA. Neither MPTP treatment nor treatment with L-DOPA, bromocriptine or ropinirole had any effect on adenosine A(2a) receptor mRNA in the striatum. These patterns of alteration in striatal PPE-A and PPT and PPE-B mRNA produced by L-DOPA, bromocriptine and ropinirole show differential involvement of markers of the direct and indirect striatal output pathways related to improvement of locomotor activity and mirror the relative abilities of the drugs to induce dyskinesia.
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Affiliation(s)
- B C Tel
- Neurodegenerative Disease Research Centre, Guy's, King's and St. Thomas' School of Biomedical Sciences, King's College, SE1 1UL, London, UK
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Daniels DA, Sohal AK, Rees S, Grisshammer R. Generation of RNA aptamers to the G-protein-coupled receptor for neurotensin, NTS-1. Anal Biochem 2002; 305:214-26. [PMID: 12054450 DOI: 10.1006/abio.2002.5663] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
G-protein-coupled receptors (GPCRs) are integral membrane proteins involved in signal transduction and constitute major drug targets for disease therapy. Aptamers, which are globular RNA or DNA molecules evolved to specifically bind a target, could represent a valuable tool with which to probe the role of such receptors in normal tissue and disease pathology and for cocrystallization with receptors for structure determination by X-ray crystallography. Using the bacterially expressed rat neurotensin receptor NTS-1 as an example, we describe a strategy for the generation of GPCR-specific RNA aptamers. Seven rounds of a "subtractive," paramagnetic bead-based selection protocol were used to enrich for neurotensin receptor-specific aptamers, while circumventing the evolution of aptamers reactive to minor protein contaminants. Representatives of each aptamer family were analyzed in Escherichia coli membrane nitrocellulose filter binding assays. Eight aptamers demonstrated specificity for the neurotensin receptor. One aptamer, P19, was characterized in detail and shown to bind to both the rat receptor and the human receptor with nanomolar affinity. P19 was also shown to interact with rat neurotensin receptor expressed in CHO cells, in both membrane preparations and intact cells. P19 represents the first example of a GPCR-specific RNA aptamer.
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Affiliation(s)
- Dion A Daniels
- Gene Expression and Protein Biochemistry, Medicines Research Centre, Stevenage, SG1 2NY, United Kingdom
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van Muijlwijk-Koezen JE, Timmerman H, Ijzerman AP. The adenosine A3 receptor and its ligands. PROGRESS IN MEDICINAL CHEMISTRY 2002; 38:61-113. [PMID: 11774799 DOI: 10.1016/s0079-6468(08)70092-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- J E van Muijlwijk-Koezen
- Leiden/Amsterdam Center for Drug Research, Division of Medicinal Chemistry, Department of Pharmacochemistry, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands
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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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Stella SL, Bryson EJ, Thoreson WB. A2 adenosine receptors inhibit calcium influx through L-type calcium channels in rod photoreceptors of the salamander retina. J Neurophysiol 2002; 87:351-60. [PMID: 11784755 DOI: 10.1152/jn.00010.2001] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Presynaptic inhibition is a major mechanism for regulating synaptic transmission in the CNS and adenosine inhibits Ca(2+) currents (I(Ca)) to reduce transmitter release at several synapses. Rod photoreceptors possess L-type Ca(2+) channels that regulate the release of L-glutamate. In the retina, adenosine is released in the dark when L-glutamate release is maximal. We tested whether adenosine inhibits I(Ca) and intracellular Ca(2+) increases in rod photoreceptors in retinal slice and isolated cell preparations. Adenosine inhibited both I(Ca) and the [Ca(2+)]i increase evoked by depolarization in a dose-dependent manner with approximately 25% inhibition at 50 microM. An A2-selective agonist, (N(6)-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)-ethyl]adenosine) (DPMA), but not the A1- or A3-selective agonists, (R)-N(6)-(1-methyl-2-phenylethyl)adenosine and N(6)-2-(4-aminophenyl)ethyladenosine, also inhibited I(Ca) and depolarization-induced [Ca(2+)]i increases. An inhibitor of protein kinase A (PKA), Rp-cAMPS, blocked the effects of DPMA on both I(Ca) and the depolarization-evoked [Ca(2+)]i increase in rods. The results suggest that activation of A2 receptors stimulates PKA to inhibit L-type Ca(2+) channels in rods resulting in a decreased Ca(2+) influx that should suppress glutamate release.
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Affiliation(s)
- Salvatore L Stella
- Department of Pharmacology and Department of Ophthalmology, University of Nebraska Medical Center, Omaha, Nebraska 68198-5540, USA
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Linden J. Molecular approach to adenosine receptors: receptor-mediated mechanisms of tissue protection. Annu Rev Pharmacol Toxicol 2001; 41:775-87. [PMID: 11264476 DOI: 10.1146/annurev.pharmtox.41.1.775] [Citation(s) in RCA: 544] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Adenosine accumulation during ischemia and inflammation protects tissues from injury. In ischemic tissues adenosine accumulates due to inhibition of adenosine kinase, and in inflamed tissues adenosine is formed from adenine nucleotides that are released from many cells including platelets, mast cells, nerves, and endothelium. Nucleotides are rapidly converted to adenosine by a family of ecto-nucleotidases including CD39 and CD73. Activation of A(1) and possibly A(3) adenosine receptors (ARs) protects heart and other tissues by preconditioning through a pathway including protein kinase C and mitochondrial K(ATP) channels. Activation of A(2A) receptors limits reperfusion injury by inhibiting inflammatory processes in neutrophils, platelets, macrophages and T cells. Adenosine produces proinflammatory responses mediated by receptors that vary among species; A(3) and A(2B) receptors mediate degranulation of rodent and human or canine mast cells, respectively. Novel adenosine receptor subtype-selective ligands have recently been developed. These include MRS1754 (A(2B) blocker), MRS1220 (A(3) blocker), MRE 3008F20 (human A(3) blocker), MRS1523 (rat A(3) blocker), and ATL146e (A(2A) agonist). These new pharmacologic tools will help investigators to sort out how adenosine protects tissues from injury and to identify new therapeutic agents that hold promise for the treatment of inflammatory and ischemic diseases.
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Affiliation(s)
- J Linden
- Department of Cardiovascular Medicine, University of Virginia, Charlottesville, Virginia 22908, USA.
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Hein TW, Wang W, Zoghi B, Muthuchamy M, Kuo L. Functional and molecular characterization of receptor subtypes mediating coronary microvascular dilation to adenosine. J Mol Cell Cardiol 2001; 33:271-82. [PMID: 11162132 DOI: 10.1006/jmcc.2000.1298] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adenosine is a potent vasodilator of the coronary microvessels and is implicated in the regulation of coronary blood flow during metabolic stress. However, the receptor subtypes and the vasodilatory mechanism responsible for the dilation of coronary microvessels to adenosine remain unclear. In the present study, using an isolated-vessel preparation we demonstrated that porcine coronary arterioles (50-100 microm) dilated concentration-dependently to adenosine, CPA (adenosine A1 receptor agonist) and CGS21680 (adenosine A2A receptor agonist). These vasodilations were not altered by the A1 receptor antagonist CPX, but were abolished by the selective A2A receptor antagonist ZM241385, indicating that activation of A2A receptors mediates these vasodilatory responses. The protein kinase A inhibitor Rp-8-Br-cAMPS abolished coronary arteriolar dilations to adenylyl cyclase activator forskolin and cAMP analog 8-Br-cAMP, but failed to inhibit adenosine- and CGS21680-induced dilations. The calcium-activated potassium channel inhibitor iberiotoxin also did not affect vasodilations to adenosine and CGS21680. In contrast, the ATP-sensitive potassium (K(ATP)) channel inhibitor glibenclamide abolished vasodilations to adenosine and CGS21680 but did not affect vasodilations to forskolin and 8-Br-cAMP. In addition, the cAMP level in coronary microvessels was not increased by adenosine or CGS21680. The results from RT/PCR and in situ hybridization indicated that adenosine A2A receptor mRNA was encoded in coronary arterioles and the left anterior descending (LAD) artery but not in cardiomyocytes, whereas the A1 receptor transcript was detected in the LAD artery and cardiomyocytes but not in arterioles. Similarly, adenosine A1 and A2A proteins were expressed in the LAD artery, but only A2A receptors were expressed in coronary arterioles. Collectively, these functional data suggest that coronary arteriolar dilation to adenosine is primarily mediated by the opening of K(ATP) channels through activation of A2A receptors. This conclusion is corroborated by the molecular data showing that coronary arterioles only express adenosine A2A receptors. Furthermore, the dilation of coronary microvessels to adenosine A2A receptor activation appears to be independent of cAMP signaling.
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Affiliation(s)
- T W Hein
- Department of Medical Physiology, Cardiovascular Reseach Institute, The Texas A&M University System Health Science Center, College Station, TX 77843-1114, USA
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Harada H, Asano O, Hoshino Y, Yoshikawa S, Matsukura M, Kabasawa Y, Niijima J, Kotake Y, Watanabe N, Kawata T, Inoue T, Horizoe T, Yasuda N, Minami H, Nagata K, Murakami M, Nagaoka J, Kobayashi S, Tanaka I, Abe S. 2-Alkynyl-8-aryl-9-methyladenines as novel adenosine receptor antagonists: their synthesis and structure-activity relationships toward hepatic glucose production induced via agonism of the A(2B) receptor. J Med Chem 2001; 44:170-9. [PMID: 11170626 DOI: 10.1021/jm990499b] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Novel adenosine antagonists, 2-alkynyl-8-aryl-9-methyladenine derivatives, were synthesized as candidate hypoglycemic agents. These analogues were evaluated for inhibitory activity on N-ethylcarboxamidoadenosine (NECA)-induced glucose production in primary cultured rat hepatocytes. In general, aromatic moieties at the 8-position and alkynyl groups at the 2-position had significantly increased activity compared to unsubstituted compounds. The preferred substituents at the 8-position of adenine were the 2-furyl and 3-fluorophenyl groups. In modifying the alkynyl side chain, change of the ring size, cleavage of the ring, and removal of the hydroxyl group were well tolerated. The order of the stimulatory effects of adenosine agonists on rat hepatocytes was NECA > CPA > CGS21680, which is consistent with involvement of the A(2B) receptor. In Chinese hamster ovary cells stably transfected with human A(2B) receptor cDNA, one of the compounds potent in hepatocytes, 15o (IC(50) = 0.42 microM), antagonized NECA-induced stimulation of cyclic AMP production (IC(50) = 0.063 microM). This inhibitory effect was much more potent than those of FK453, KF17837, and L249313 which have been reported to be respectively A(1), A(2A), and A(3) selective antagonists. These findings agree very well with the result that, compared to 15o, these selective antagonists for each receptor subtype showed only marginal effects in rat hepatocytes. These results suggest that adenosine agonist-induced glucose production in rat hepatocytes is mediated through the A(2B) receptor. Furthermore, 15o showed hypoglycemic activity in an animal model of noninsulin-dependent diabetes mellitus, the KK-A(y) mice. It is possible that inhibition of hepatic glucose production via the A(2B) receptor could be at least one of the mechanisms by which 15o exerts its in vivo effects. Further elaboration of this group of compounds may afford novel antidiabetic agents.
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Affiliation(s)
- H Harada
- Tsukuba Research Laboratories, Eisai Company, Ltd., 5-1-3 Tokodai, Tsukuba, Ibaraki 300-2635, Japan.
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36
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Kuo L, Hein TW. Functional and molecular evidence of adenosine A2A receptor in coronary arteriolar dilation to adenosine. Drug Dev Res 2001. [DOI: 10.1002/ddr.1134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Crosson CE, Niazi Z. Ocular effects associated with the chronic administration of the adenosine A(1) agonist cyclohexyladenosine. Curr Eye Res 2000; 21:808-13. [PMID: 11120571 DOI: 10.1076/ceyr.21.4.808.5547] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
PURPOSE To investigate changes in ocular responses associated with the chronic administration of the adenosine A(1) agonist cyclohexyladenosine (CHA). METHODS New Zealand White rabbits were treated unilaterally twice-a-day for 30 days with CHA (165 or 500 microg) or vehicle. Intraocular pressures (IOPs) and pupil diameters (PDs) were evaluated over the course of the study. At the end of the study period, outflow facility was determined in selected animals and compared to naïve vehicle- and CHA-treated animals. RESULTS In rabbits receiving 165 microg of CHA, ipsilateral IOPs at 2 and 6 hours post-drug exhibited progressively greater reduction over the course of the study. Regression analysis demonstrated a significant correlation between study duration and lower IOP at 2 and 6 hours post-drug. In rabbits receiving 500 microg of CHA, ipsilateral IOP reductions at 2 hours post-drug were similar throughout the 30-day study. However, analysis of ipsilateral IOPs 6 hours following CHA administration, demonstrated a significant correlation between study duration and lower IOPs. Enhanced contralateral responses at 2 hours post- drug, were also measured in rabbits receiving 165 or 500 microg of CHA. In animals receiving chronic CHA treatment for 30 days, outflow facility 3 hours post-CHA was significantly elevated over that measured in naïve vehicle-treated rabbits. Although mean outflow facility in chronic treatment animals was slightly elevated over CHA-induced increases in naïve rabbits, this difference was not significant. No evidence of tolerance was observed for either dose during the course of these studies. No change in PD during the course of these studies was measured. CONCLUSIONS The chronic administration of the adenosine A(1) agonist CHA twice daily produced no evidence of tolerance. Unexpectedly, the IOP response to CHA was enhanced with chronic administration. These data provide evidence that the use of adenosine A(1) agonists may be useful in the chronic treatment of ocular hypertension at doses lower than those identified in acute IOP studies.
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Affiliation(s)
- C E Crosson
- Department of Ophthalmology and Visual Sciences, Texas Tech University Health Sciences Center, Lubbock, Texas, USA.
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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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Zeng BY, Pearce RK, MacKenzie GM, Jenner P. Alterations in preproenkephalin and adenosine-2a receptor mRNA, but not preprotachykinin mRNA correlate with occurrence of dyskinesia in normal monkeys chronically treated with L-DOPA. Eur J Neurosci 2000; 12:1096-104. [PMID: 10762340 DOI: 10.1046/j.1460-9568.2000.00988.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chronic treatment with L-DOPA induces dyskinesia in patients with Parkinson's disease (PD) and 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP)-treated monkeys, but is not thought to do so in normal humans or primates. However, we have shown that chronic oral high dose L-DOPA administration, with the peripheral decarboxylase inhibitor, carbidopa and with or without the peripherally acting catechol-O-methyl transferase (COMT) inhibitor, entacapone, to normal macaque monkeys for 13 weeks induced dyskinesia in a proportion of animals. In the present study, in situ hybridization histochemistry was used to investigate the effect of chronic L-DOPA administration on the activity of the direct and indirect striatal output pathways by measuring striatal preprotachykinin (PPT), preproenkephalin-A (PPE-A) and adenosine-2a (A2a) receptor gene expression in these monkeys. Overall there was no significant difference in striatal PPT, PPE-A and A2a receptor mRNA levels between normal animals and all L-DOPA (plus carbidopa and/or entacapone)-treated animals irrespective of whether or not dyskinesia occurred. However, when the level of PPE-A and A2a receptor mRNA was analysed in eight monkeys displaying marked dyskinesias as a result of L-DOPA (plus carbidopa with or without entacapone) treatment, there was a significant increase in PPE-A and A2a receptor mRNA message levels in the striatum compared with animals receiving identical treatment, but displaying few or no involuntary movements, and compared with normal controls. There was no difference in striatal PPT mRNA levels in monkeys exhibiting severe dyskinesia compared with those showing little or no dyskinesia after L-DOPA treatment or to normal controls. These results suggest that prolonged L-DOPA treatment alone has no consistent effect on either the direct or indirect pathways, as judged by striatal PPT, PPE-A or A2a receptor mRNA levels in normal monkeys. However, in monkeys exhibiting marked dyskinesia resulting from chronic L-DOPA treatment, abnormal activity is detected in the indirect striato-pallidal output pathway, as judged by striatal PPE-A and A2a receptor mRNA levels, indicating an imbalance between the direct and indirect striatal pathway which may explain the emergence of dyskinesia in these animals.
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Affiliation(s)
- B Y Zeng
- Neurodegenerative Disease Research Centre, Division of Pharmacology & Therapeutics, Hodgkin Building, GKT School of Biomedical Sciences, King's College London, Guy's Campus, London Bridge, London, SE1 1UL, UK
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Abstract
Adenosine produces a wide variety of physiological effects through the activation of cell surface adenosine receptors (ARs). ARs are members of the G-protein-coupled receptor family, and currently, four subtypes, the A1AR, A2AAR, A2BAR, and A3AR, are recognized. This review focuses on the role of receptor structure in governing various facets of AR activity. Ligand-binding properties of ARs are primarily dictated by amino acids in the transmembrane domains of the receptors, although a role for extracellular domains of certain ARs has been suggested. Studies have identified certain amino acids conserved amongst AR subtypes that are critical for ligand recognition, as well as additional residues that may differentiate between agonist and antagonist ligands. Receptor regions responsible for activation of Gs have been identified for the A2AAR. The location of these intracellular sites is consistent with findings described for other G-protein-coupled receptors. Site-directed mutagenesis has been employed to analyze the structural basis for the differences in the kinetics of the desensitization response displayed by various AR subtypes. For the A2AAR and A3AR, agonist-stimulated phosphorylation of the AR, presumably via a G-protein receptor kinase, has been shown to occur. For these AR subtypes, intracellular regions or individual amino acids that may be targets for this phosphorylation have been identified. Finally, the role of A1AR gene structure in regulating the expression of this AR subtype is reviewed.
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Affiliation(s)
- M E Olah
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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Moreau JL, Huber G. Central adenosine A(2A) receptors: an overview. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1999; 31:65-82. [PMID: 10611496 DOI: 10.1016/s0165-0173(99)00059-4] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent advances in molecular biology, biochemistry, cell biology and behavioral pharmacology together with the development of more selective ligands to the various adenosine receptors have increased our understanding of the functioning of central adenosine A(2A) receptors. The A(2A) receptor is one of four adenosine receptors found in the brain. Its expression is highest in striatum, nucleus accumbens and olfactory tubercles, although it also occurs in neurons and microglia in most other brain regions. The receptor has seven transmembrane domains and couples via Gs to adenyl cyclase stimulation. Antagonistic interactions between A(2A) receptors and dopamine D(2) receptors have been described, as stimulation of the A(2A) receptor leads to a reduction in the affinity of D(2) receptors for D(2) receptor agonists. The A(2A) receptor is thought to play a role in a number of physiological responses and pathological conditions. Indeed, A(2A) receptor antagonists may be useful for the treatment of acute and chronic neurodegenerative disorders such as cerebral ischemia or Parkinson's disease. A(2A) receptor agonists may treat certain types of seizures or sleep disorders. This review discusses the characteristics, distribution, pharmacochemical properties and regulation of central A(2A) receptors, as well as A(2A) receptor-mediated behavioural responses and their potential role in various neuropsychiatric disorders.
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Affiliation(s)
- J L Moreau
- Pharma Division, Preclinical CNS Research, F. Hoffmann-La Roche, PRPN, 72/141, CH-4070, Basel, Switzerland.
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Abstract
The role of adenosine receptor engagement in murine T-cell development was evaluated by culturing day 15-16 fetal thymic lobes in the presence of various concentrations of the adenosine receptor agonist 5'-(N-ethyl)-carboxamidoadenosine (NECA) or the adenosine receptor antagonist 8-phenyl-theophylline (8-PT) using the fetal thymic organ culture (FTOC) system. Before and 8 days after culture, thymocytes were isolated, counted, and analyzed for the expression of CD4 and CD8 T-cell differentiation molecules. Analysis of fresh thymocytes prior to culture showed that the majority of cells were of the CD4 single-positive or CD4+ CD8+ immature phenotype. Eight days after culture with media alone, 44% of cells were CD4+ and 23% were CD8+, and the number of viable thymocytes had increased from 1.7 x 10(5) to 2.2 x 10(5) cells per thymic lobe. A dose-dependent inhibition of maturation was observed in cultures with 8-PT, with greater than 85% inhibition at 50 microM. The double-positive thymocyte subset was most severely depleted. The number of cells obtained from cultures with NECA was also reduced, with about 65% inhibition at 50 microM, especially the CD8+ subset that was most severely affected. These results suggest that adenosine receptor engagement is required for normal T-cell differentiation and that adenosine receptor agonists and antagonists have distinct effects on thymocyte differentiation. An understanding of the cell-type-specific and developmental expression of adenosine receptors will help elucidate the mechanisms by which adenosine receptor engagement influences T-cell development.
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Affiliation(s)
- M Hamad
- Department of Medical Technology, Zarka Private University, Jordan
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Ribeiro JA. Adenosine A2A receptor interactions with receptors for other neurotransmitters and neuromodulators. Eur J Pharmacol 1999; 375:101-13. [PMID: 10443568 DOI: 10.1016/s0014-2999(99)00230-7] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Adenosine, by activating adenosine A2A receptors, seems to have a crucial function in regulating the activation of multiple receptors that affect neurotransmitter release and/or synaptic transmission, in particular receptors for neuropeptides (calcitonin gene related peptide (CGRP) and vasoactive intestinal peptide (VIP)), and NMDA receptors, metabotropic glutamate receptors, nicotinic autofacilitatory receptors, dopamine receptors and adenosine A1 receptors. The manner in which these A2A receptors are involved in interactions with the receptors for other neurotransmitters and or neuromodulators opens novel avenues for the action of this 'omnipresent' nucleoside. Either by direct receptor-receptor modulation or by post-receptor mechanisms, adenosine, in its 'obsession' to protect cells from insults, uses as many receptor systems as possible to synchronize synaptic transmission, in order to exert what seems to be the 'destiny' of this nucleoside--protection of the nervous system.
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Affiliation(s)
- J A Ribeiro
- Laboratory of Neurosciences, Faculty of Medicine, University of Lisbon, Portugal.
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Ezeamuzie CI, Philips E. Adenosine A3 receptors on human eosinophils mediate inhibition of degranulation and superoxide anion release. Br J Pharmacol 1999; 127:188-94. [PMID: 10369472 PMCID: PMC1565974 DOI: 10.1038/sj.bjp.0702476] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The role of adenosine A3 receptors on human eosinophil degranulation and superoxide anion (O2-) release was studied in vitro using the complement fragment C5a as the main stimulus and employing a number of selective agonists and antagonists. In the presence of cytochalasin B (CB), C5a induced a dose-dependent release of the granular eosinophil peroxidase (EPO), but not O2-, whereas in the absence of CB O2- , but not EPO, was released. C5a-induced EPO release was inhibited dose-dependently by the selective A3 agonist N6-(3-iodobenzyl)-5'-N-methylcarbamoyladenosine (IB-MECA) and to a lesser extent by the less-selective N6-2-(4-amino-3-iodophenyl) ethyladenosine (APNEA). The IC50 (95% CI) for IB-MECA was 6.8 microM (3.1-12.0 microM). At concentrations up to 100 microM, neither adenosine nor the selective A1 agonist N-cyclopentyladenosine (CPA) and the selective A2 agonist 2-[[2-[4-(2-carboxyethyl)phenyl]ethyl]amino]-N-ethylcarboxamidoadenosine (CGS 21680) had any significant effect. The inhibitory effect of IB-MECA was almost completely abolished by pre-treatment with 1 microM of the selective A3 antagonist 9-chloro-2-(2-furyl)-5-phenylactylamino[1,2,4]triazolo[1,5-c]quina zoline (MRS 1220), but not the selective A1 antagonist 1,3-dipropyly-8-cyclopentylxanthine (DPCPX) or the selective A2 antagonist 3,7-dimethyl-1-propargylxanthine (DMPX). IB-MECA also significantly inhibited C5a-induced O2- release with IC50 (95% CI) of 9.5 microM (4.6-13.1 microM) whereas adenosine and the A1 agonist CPA potentiated this effect at low concentrations. The potentiation appeared to be a result of their direct O2- release from these cells, probably mediated via A1 receptors. The inhibition by IB-MECA was selectively reversed by MRS 1220. These results show that the A3 receptors on human eosinophils mediate inhibition of both degranulation and O2- release and suggest a therapeutic potential for A3 agonists in diseases such as asthma in which activated eosinophils are involved.
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Affiliation(s)
- C I Ezeamuzie
- Department of Pharmacology and Toxicology, Faculty of Medicine, Kuwait University, Safat.
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Kull B, Arslan G, Nilsson C, Owman C, Lorenzen A, Schwabe U, Fredholm BB. Differences in the order of potency for agonists but not antagonists at human and rat adenosine A2A receptors. Biochem Pharmacol 1999; 57:65-75. [PMID: 9920286 DOI: 10.1016/s0006-2952(98)00298-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
To examine possible species differences in pharmacology, rat adenosine A2A receptors were studied in PC12 (pheochromocytoma) cells, and human receptors in Chinese hamster ovary (CHO) cells transfected with the cloned human A2A receptor cDNA. Using [3H]-5-amino-7(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo [1,5-c]pyrimidine ([3H]-SCH 58261) as radioligand, the estimated Bmax (maximal binding) was 538 and 2085 fmol/mg in CHO and PC12 cells, respectively. The Kd (dissociation constant) values for [3H]-SCH 58261 were 1.05 and 5.6 nM in the two cell types, respectively. The order of potency of antagonists and most agonists was the same in both cell types, but 2-phenylaminoadenosine and 2-chloroadenosine were relatively less potent in PC12 cells than in CHO cells. In the functional assay, using cyclic AMP accumulation, all agonists tested were more potent in CHO than in PC12 cells, but this could not be readily explained by differences in adenylyl cyclase or in the expression of G proteins. As in the case of binding, the relative agonist potencies were similar for most compounds, but 2-phenylaminoadenosine and 2-chloroadenosine were more potent at human A2A receptors in CHO cells than predicted from the data obtained on rat A2A receptors in PC12 cells. Antagonists were approximately equipotent in the two cells. These results show that, despite only small differences in amino acid sequences and no difference in antagonist pharmacology, the relative order of potency of receptor agonists can differ between species homologues of the adenosine A2A receptor.
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Affiliation(s)
- B Kull
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
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Kurumaji A, Toru M. An increase in [3H] CGS21680 binding in the striatum of postmortem brains of chronic schizophrenics. Brain Res 1998; 808:320-3. [PMID: 9767181 DOI: 10.1016/s0006-8993(98)00840-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
We measured adenosine 2a receptors in basal ganglia of 13 schizophrenics and 10 controls, using [3H] CGS21680 as a ligand for the receptor binding assay. There was a significant increase in the specific [3H] CGS21680 binding in the putamen and caudate, but not in the globus pallidus of externa, of the schizophrenic patients, compared to those of controls. These results provide evidence suggesting that adenosine 2a receptors play a role in the pathophysiology of schizophrenia.
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Affiliation(s)
- A Kurumaji
- Department of Neuropsychiatry, Tokyo Medical and Dental University School of Medicine, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan.
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Guieu R, Dussol B, Halimi G, Bechis G, Sampieri F, Berland Y, Sampol J, Couraud F, Rochat H. Adenosine and the nervous system: pharmacological data and therapeutic perspectives. GENERAL PHARMACOLOGY 1998; 31:553-61. [PMID: 9792214 DOI: 10.1016/s0306-3623(98)00071-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
1. Adenosine acts on a family of G-protein-coupled receptors called purinoreceptors. 2. Four subtypes have been cloned and pharmacologically characterized. 3. The principal pharmacological data and structure-function relations for agonist interactions with P1 receptors are presented. 4. We conclude that the potent role of adenosine in the nervous system may be interesting for the development of drugs targeted at purines and their receptors.
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Affiliation(s)
- R Guieu
- Laboratoire de Biochimie et d'Ingéniérie des Protéines, URA CNRS 1455 Faculté de Médecine Secteur Nord, Marseille, France
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48
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Costa B, Lucacchini A, Martini C. A2a adenosine receptors: guanine nucleotide derivative regulation in porcine striatal membranes and digitonin soluble fraction. Neurochem Int 1998; 33:121-9. [PMID: 9761456 DOI: 10.1016/s0197-0186(98)00019-9] [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: 02/09/2023]
Abstract
We report the characterization of A2a adenosine receptors (A2aARs) in porcine striatal membranes and their solubilization (25%) by the detergent digitonin. After solubilization, the drug specificity and equilibrium [3H]CGS-21680 ([3H]2-(4-(2-carboxyethyl)phenylethylamino)-5'-N-ethyl-carboxamido -adenosine) binding parameters were virtually identical to those obtained in intact membranes, indicating a conservation of the binding site after the removal of receptors from their lipid environment. Gel filtration on a calibrated Superdex 200 HR column revealed a main [3H]CGS-21680 binding peak with an apparent molecular weight of 171,000+/-9000 Da. In membranes, Scatchard analysis of saturation data carried out in a wide range of radioligand concentration (1-100 nM) resulted in a biphasic curve and, in accordance with the two binding sites model, yielded a Kd1 = 7.4+/-0.5 and Kd2 = 53.1+/-3.6 nM, a Bmax1 = 186+/-15 fmol/mg protein and a Bmax2 = 285+/-20 fmol/mg protein, respectively. In the presence of guanosine-5'-O-(3-thiotriphosphate) (GTPgamma[S]) a shift from two affinity states to a single one was evidenced (Kd = 28.5+/-5.9 nM) and a Bmax value of 504+/-10 fmol/mg protein found. In the soluble extract, only one high-affinity state was detected (Kd = 19.3+/-1.1 nM and Bmax = 285+/-20 fmol/mg protein) and, in the presence of GTPgamma[S]), a two site model likewise provided a significantly (P < 0.01) better fit (Kd1 = 13.9+/-1.2 nM and Kd2 = 72.1+/-6.9 nM, Bmax1 = 125+/-10 fmol/mg protein and Bmax2 = 375+/-19 fmol/mg protein, respectively). These results suggest a close relation between the receptor and G protein solubilized as a functional unit and open the way to its purification.
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Affiliation(s)
- B Costa
- Dipartimento di Psichiatria, Farmacologia e Biotecnologie dell 'Università degli Studi di Pisa, Italy
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Kaul PN. Drug discovery: past, present and future. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1998; 50:9-105. [PMID: 9670776 DOI: 10.1007/978-3-0348-8833-2_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
New drug discovery from early on involved a trial-and-error approach on naturally derived materials and substances until the end of the nineteenth century. The first half of the twentieth century witnessed systematic pharmacological evaluations of both natural and synthetic compounds. However, most new drugs until the 1970s were discovered by serendipity. With the exponential development of molecular biology on one hand and computer technology on the other, it became possible from 1980 onwards to place drug discovery on a rational basis. Cloning of genes has led to the development of methodologies for specific receptor-directed and enzyme-directed drug discoveries. Advances in recombinant DNA and transgenic technologies have enabled the production of human hormonal and other endogenous biomolecules as new drugs. As we understand more about the co-ordinating and regulating powers of the cerebral cortex during the next century, especially of the frontal lobe, man may be able to use bio-feedback training to voluntarily regulate the release of neurotransmitters, hormones, and other molecules involved in the regulation of various physiological processes in health as well as in disease.
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Affiliation(s)
- P N Kaul
- Clark Atlanta University, GA 30314, USA
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50
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Abstract
This review summarises current knowledge on adenosine receptors, an important G protein-coupled receptor. The four known adenosine receptor subtypes A1, A2A, A2B, and A3 are discussed with special reference to the opportunities for drug development.
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Affiliation(s)
- S A Poulsen
- Queensland Pharmaceutical Research Institute, Griffith University, Brisbane, Australia
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