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Nucleoside transporters and immunosuppressive adenosine signaling in the tumor microenvironment: Potential therapeutic opportunities. Pharmacol Ther 2022; 240:108300. [PMID: 36283452 DOI: 10.1016/j.pharmthera.2022.108300] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/30/2022]
Abstract
Adenosine compartmentalization has a profound impact on immune cell function by regulating adenosine localization and, therefore, extracellular signaling capabilities, which suppresses immune cell function in the tumor microenvironment. Nucleoside transporters, responsible for the translocation and cellular compartmentalization of hydrophilic adenosine, represent an understudied yet crucial component of adenosine disposition in the tumor microenvironment. In this review article, we will summarize what is known regarding nucleoside transporter's function within the purinome in relation to currently devised points of intervention (i.e., ectonucleotidases, adenosine receptors) for cancer immunotherapy, alterations in nucleoside transporter expression reported in cancer, and potential avenues for targeting of nucleoside transporters for the desired modulation of adenosine compartmentalization and action. Further, we put forward that nucleoside transporters are an unexplored therapeutic opportunity, and modulation of nucleoside transport processes could attenuate the pathogenic buildup of immunosuppressive adenosine in solid tumors, particularly those enriched with nucleoside transport proteins.
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Wang M, Li Z, Song Y, Sun Q, Deng L, Lin Z, Zeng Y, Qiu C, Lin J, Guo H, Chen J, Guo W. Genetic tagging of the adenosine A2A receptor reveals its heterogeneous expression in brain regions. Front Neuroanat 2022; 16:978641. [PMID: 36059431 PMCID: PMC9434489 DOI: 10.3389/fnana.2022.978641] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 07/29/2022] [Indexed: 11/22/2022] Open
Abstract
The adenosine A2A receptor (A2AR), a G protein-coupled receptor, is involved in numerous and varied physiological and pathological processes, including inflammation, immune responses, blood flow, and neurotransmission. Accordingly, it has become an important drug target for the treatment of neuropsychiatric disorders. However, the exact brain distribution of A2AR in regions outside the striatum that display relatively low levels of endogenous A2AR expression has hampered the exploration of A2AR functions under both physiological and pathological conditions. To further study the detailed distribution of the A2AR in low-expression regions, we have generated A2AR knock-in mice in which the 3xHA-2xMyc epitope tag sequence was fused to the C-terminus of A2AR (A2AR-tag mice) via CRISPR/Cas9 technology. Here, using CRISPR/Cas9 technology, we have generated A2AR knock-in mice in which the 3xHA-2xMyc epitope tag sequence was fused to the C-terminus of A2AR (A2AR-tag mice). The A2AR-tag mice exhibited normal locomotor activity and emotional state. Consistent with previous studies, A2AR fluorescence was widely detected in the striatum, nucleus accumbens, and olfactory tubercles, with numerous labeled cells being evident in these regions in the A2AR-tag mouse. Importantly, we also identified the presence of a few but clearly labeled cells in heterogeneous brain regions where A2AR expression has not previously been unambiguously detected, including the lateral septum, hippocampus, amygdala, cerebral cortex, and gigantocellular reticular nucleus. The A2AR-tag mouse represents a novel useful genetic tool for monitoring the expression of A2AR and dissecting its functions in brain regions other than the striatum.
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Affiliation(s)
- Muran Wang
- The Molecular Neuropharmacology Laboratory and the Eye-Brain Research Center, The State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Zewen Li
- The Molecular Neuropharmacology Laboratory and the Eye-Brain Research Center, The State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Yue Song
- The Molecular Neuropharmacology Laboratory and the Eye-Brain Research Center, The State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Qiuqin Sun
- The Molecular Neuropharmacology Laboratory and the Eye-Brain Research Center, The State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Lu Deng
- Department of Neurology, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Structural Malformations in Children of Zhejiang Province, Wenzhou, China
| | - Zhiqing Lin
- The Molecular Neuropharmacology Laboratory and the Eye-Brain Research Center, The State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Yang Zeng
- Shanghai Pregen Biotechnology Co., Ltd., Shanghai, China
| | - Chunhong Qiu
- Shanghai Pregen Biotechnology Co., Ltd., Shanghai, China
| | - Jingjing Lin
- Department of Neurology, The Second Affiliated Hospital and Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou, China
- Key Laboratory of Structural Malformations in Children of Zhejiang Province, Wenzhou, China
| | - Hui Guo
- The Molecular Neuropharmacology Laboratory and the Eye-Brain Research Center, The State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
| | - Jiangfan Chen
- The Molecular Neuropharmacology Laboratory and the Eye-Brain Research Center, The State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
- Jiangfan Chen,
| | - Wei Guo
- The Molecular Neuropharmacology Laboratory and the Eye-Brain Research Center, The State Key Laboratory of Ophthalmology, Optometry and Vision Science, Wenzhou Medical University, Wenzhou, China
- *Correspondence: Wei Guo,
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Jung SM, Peyton L, Essa H, Choi DS. Adenosine receptors: Emerging non-opioids targets for pain medications. NEUROBIOLOGY OF PAIN (CAMBRIDGE, MASS.) 2022; 11:100087. [PMID: 35372716 PMCID: PMC8971635 DOI: 10.1016/j.ynpai.2022.100087] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/22/2022] [Accepted: 03/23/2022] [Indexed: 11/16/2022]
Abstract
Physical and emotional pain deteriorates the quality of well-being. Also, numerous non-invasive and invasive treatments for diagnosed diseases such as cancer medications and surgical procedures cause various types of pain. Despite the multidisciplinary approaches available to manage pain, the unmet needs for medication with minimal side effects are substantial. Especially with the surge of opioid crisis during the last decades, non-opioid analgesics may reduce life-threatening overdosing and addictive liability. Although many clinical trials supported the potential potency of cannabis and cannabidiol (CBD) in pain management or treatment, the long-term benefits of cannabis or CBD are still not evident. At the same time, growing evidence shows the risk of overusing cannabis and CBD. Therefore, it is urgent to develop novel analgesic medications that minimize side effects. All four well-identified adenosine receptors, A1, A2A, A2B, and A3, are implicated in pain. Recently, a report demonstrated that an adenosine A1R-specific positive allosteric modulator (PAM) is a potent analgesic without noticeable side effects. Also, several A3R agonists are being considered as promising analgesic agent. However, the importance of adenosine in pain is relatively underestimated. To help readers understand, first, we will summarize the historical perspective of the adenosine system in preclinical and clinical studies. Then, we will discuss possible interactions of adenosine and opioids or the cannabis system focusing on pain. Overall, this review will provide the potential role of adenosine and adenosine receptors in pain treatment.
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Affiliation(s)
- Soo-Min Jung
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
| | - Lee Peyton
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
| | - Hesham Essa
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
| | - Doo-Sup Choi
- Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine and Science, Rochester, MN, United States.,Neuroscience Program, Mayo Clinic College of Medicine and Science, Rochester, MN, United States.,Department of Psychiatry and Psychology, Mayo Clinic College of Medicine and Science, Rochester, MN, United States
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4
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Moreira-de-Sá A, Lourenço VS, Canas PM, Cunha RA. Adenosine A 2A Receptors as Biomarkers of Brain Diseases. Front Neurosci 2021; 15:702581. [PMID: 34335174 PMCID: PMC8322233 DOI: 10.3389/fnins.2021.702581] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 06/22/2021] [Indexed: 12/12/2022] Open
Abstract
Extracellular adenosine is produced with increased metabolic activity or stress, acting as a paracrine signal of cellular effort. Adenosine receptors are most abundant in the brain, where adenosine acts through inhibitory A1 receptors to decrease activity/noise and through facilitatory A2A receptors (A2AR) to promote plastic changes in physiological conditions. By bolstering glutamate excitotoxicity and neuroinflammation, A2AR also contribute to synaptic and neuronal damage, as heralded by the neuroprotection afforded by the genetic or pharmacological blockade of A2AR in animal models of ischemia, traumatic brain injury, convulsions/epilepsy, repeated stress or Alzheimer's or Parkinson's diseases. A2AR overfunction is not only necessary for the expression of brain damage but is actually sufficient to trigger brain dysfunction in the absence of brain insults or other disease triggers. Furthermore, A2AR overfunction seems to be an early event in the demise of brain diseases, which involves an increased formation of ATP-derived adenosine and an up-regulation of A2AR. This prompts the novel hypothesis that the evaluation of A2AR density in afflicted brain circuits may become an important biomarker of susceptibility and evolution of brain diseases once faithful PET ligands are optimized. Additional relevant biomarkers would be measuring the extracellular ATP and/or adenosine levels with selective dyes, to identify stressed regions in the brain. A2AR display several polymorphisms in humans and preliminary studies have associated different A2AR polymorphisms with altered morphofunctional brain endpoints associated with neuropsychiatric diseases. This further prompts the interest in exploiting A2AR polymorphic analysis as an ancillary biomarker of susceptibility/evolution of brain diseases.
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Affiliation(s)
- Ana Moreira-de-Sá
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Vanessa S Lourenço
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Paula M Canas
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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5
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Mori A. How do adenosine A 2A receptors regulate motor function? Parkinsonism Relat Disord 2020; 80 Suppl 1:S13-S20. [PMID: 33349575 DOI: 10.1016/j.parkreldis.2020.09.025] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 09/14/2020] [Accepted: 09/15/2020] [Indexed: 01/17/2023]
Abstract
Adenosine A2A receptor antagonism is a new therapeutic strategy in the symptomatic treatment of Parkinson's disease (PD). This review addresses how adenosine A2A receptors are involved with the control of motor function via the basal ganglia-thalamocortical circuit, and considers the anatomical localization and physiological function of the receptor, along with its ultrastructural localization in critical areas/neurons of the circuit. Based on this understanding of the functional significance of the adenosine A2A receptor in the basal ganglia, the mode of action of A2A receptor antagonists is explored in terms of the dynamic functioning of the basal ganglia and the activity of the internal circuits of the striatum in PD. Finally, the pathophysiological differences between the normal and PD states are examined to emphasize the importance of the adenosine A2A receptor.
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Glaser T, Andrejew R, Oliveira-Giacomelli Á, Ribeiro DE, Bonfim Marques L, Ye Q, Ren WJ, Semyanov A, Illes P, Tang Y, Ulrich H. Purinergic Receptors in Basal Ganglia Diseases: Shared Molecular Mechanisms between Huntington's and Parkinson's Disease. Neurosci Bull 2020; 36:1299-1314. [PMID: 33026587 PMCID: PMC7674528 DOI: 10.1007/s12264-020-00582-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 05/30/2020] [Indexed: 12/22/2022] Open
Abstract
Huntington's (HD) and Parkinson's diseases (PD) are neurodegenerative disorders caused by the death of GABAergic and dopaminergic neurons in the basal ganglia leading to hyperkinetic and hypokinetic symptoms, respectively. We review here the participation of purinergic receptors through intracellular Ca2+ signaling in these neurodegenerative diseases. The adenosine A2A receptor stimulates striatopallidal GABAergic neurons, resulting in inhibitory actions on GABAergic neurons of the globus pallidus. A2A and dopamine D2 receptors form functional heteromeric complexes inducing allosteric inhibition, and A2A receptor activation results in motor inhibition. Furthermore, the A2A receptor physically and functionally interacts with glutamate receptors, mainly with the mGlu5 receptor subtype. This interaction facilitates glutamate release, resulting in NMDA glutamate receptor activation and an increase of Ca2+ influx. P2X7 receptor activation also promotes glutamate release and neuronal damage. Thus, modulation of purinergic receptor activity, such as A2A and P2X7 receptors, and subsequent aberrant Ca2+ signaling, might present interesting therapeutic potential for HD and PD.
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Affiliation(s)
- Talita Glaser
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, SP, 05508-000, Brazil
| | - Roberta Andrejew
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, SP, 05508-000, Brazil
| | - Ágatha Oliveira-Giacomelli
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, SP, 05508-000, Brazil
| | - Deidiane Elisa Ribeiro
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, SP, 05508-000, Brazil
| | - Lucas Bonfim Marques
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, SP, 05508-000, Brazil
| | - Qing Ye
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, SP, 05508-000, Brazil
- Key Laboratory of Sichuan Province for Acupuncture and Chronobiology, Chengdu, 610075, China
| | - Wen-Jing Ren
- Key Laboratory of Sichuan Province for Acupuncture and Chronobiology, Chengdu, 610075, China
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, 04107, Germany
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia
- Sechenov First Moscow State Medical University, Moscow, 119992, Russia
| | - Peter Illes
- Rudolf-Boehm-Institut für Pharmakologie und Toxikologie, Universität Leipzig, Leipzig, 04107, Germany
- International Collaborative Centre on Big Science Plan for Purine Signaling, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Yong Tang
- Key Laboratory of Sichuan Province for Acupuncture and Chronobiology, Chengdu, 610075, China
- International Collaborative Centre on Big Science Plan for Purine Signaling, Chengdu University of Traditional Chinese Medicine, Chengdu, 610075, China
| | - Henning Ulrich
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, Av. Prof. Lineu Prestes 748, São Paulo, SP, 05508-000, Brazil.
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Diaz-Castro B, Gangwani MR, Yu X, Coppola G, Khakh BS. Astrocyte molecular signatures in Huntington's disease. Sci Transl Med 2020; 11:11/514/eaaw8546. [PMID: 31619545 DOI: 10.1126/scitranslmed.aaw8546] [Citation(s) in RCA: 139] [Impact Index Per Article: 34.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Accepted: 08/02/2019] [Indexed: 12/14/2022]
Abstract
Astrocytes are implicated in neurodegenerative disorders and may contribute to striatal neuron loss or dysfunction in Huntington's disease (HD). Here, we assessed striatal astrocyte gene and protein signatures in two HD mouse models at three stages and compared our results to human HD data at four clinical grades and to mice exhibiting polyglutamine length-dependent pathology. We found disease-model and stage-specific alterations and discovered a core disease-associated astrocyte molecular signature comprising 62 genes that were conserved between mice and humans. Our results show little evidence of neurotoxic A1 astrocytes that have been proposed to be causal for neuronal death in neurodegenerative disorders such as HD. Furthermore, 61 of the 62-core gene expression changes within astrocytes were reversed in a HD mouse model by lowering astrocyte mutant huntingtin protein (mHTT) expression using zinc finger protein (ZFP) transcriptional repressors. Our findings indicate that HD astrocytes progressively lose essential normal functions, some of which can be remedied by lowering mHTT. The data have implications for neurodegenerative disease rescue and repair strategies as well as specific therapeutic relevance for mHTT reduction and contribute to a better understanding of fundamental astrocyte biology and its contributions to disease.
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Affiliation(s)
- Blanca Diaz-Castro
- Department of Physiology, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Mohitkumar R Gangwani
- Department of Physiology, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Xinzhu Yu
- Department of Physiology, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Giovanni Coppola
- Department of Neurology, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA.,Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA.,Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Baljit S Khakh
- Department of Physiology, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA. .,Department of Neurobiology, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
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Adenosine A 2AReceptors in Substance Use Disorders: A Focus on Cocaine. Cells 2020; 9:cells9061372. [PMID: 32492952 PMCID: PMC7348840 DOI: 10.3390/cells9061372] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 05/28/2020] [Accepted: 05/28/2020] [Indexed: 12/31/2022] Open
Abstract
Several psychoactive drugs can evoke substance use disorders (SUD) in humans and animals, and these include psychostimulants, opioids, cannabinoids (CB), nicotine, and alcohol. The etiology, mechanistic processes, and the therapeutic options to deal with SUD are not well understood. The common feature of all abused drugs is that they increase dopamine (DA) neurotransmission within the mesocorticolimbic circuitry of the brain followed by the activation of DA receptors. D2 receptors were proposed as important molecular targets for SUD. The findings showed that D2 receptors formed heteromeric complexes with other GPCRs, which forced the addiction research area in new directions. In this review, we updated the view on the brain D2 receptor complexes with adenosine (A)2A receptors (A2AR) and discussed the role of A2AR in different aspects of addiction phenotypes in laboratory animal procedures that permit the highly complex syndrome of human drug addiction. We presented the current knowledge on the neurochemical in vivo and ex vivo mechanisms related to cocaine use disorder (CUD) and discussed future research directions for A2AR heteromeric complexes in SUD.
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Micioni Di Bonaventura MV, Pucci M, Giusepponi ME, Romano A, Lambertucci C, Volpini R, Micioni Di Bonaventura E, Gaetani S, Maccarrone M, D'Addario C, Cifani C. Regulation of adenosine A 2A receptor gene expression in a model of binge eating in the amygdaloid complex of female rats. J Psychopharmacol 2019; 33:1550-1561. [PMID: 31161847 DOI: 10.1177/0269881119845798] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Pharmacological treatment approaches for eating disorders, such as binge eating disorder and bulimia nervosa, are currently limited. METHODS AND AIMS Using a well-characterized animal model of binge eating, we investigated the epigenetic regulation of the A2A Adenosine Receptor (A2AAR) and dopaminergic D2 receptor (D2R) genes. RESULTS Gene expression analysis revealed a selective increase of both receptor mRNAs in the amygdaloid complex of stressed and restricted rats, which exhibited binge-like eating, when compared to non-stressed and non-restricted rats. Consistently, pyrosequencing analysis revealed a significant reduction of the percentage of DNA methylation but only at the A2AAR promoter region in rats showing binge-like behaviour compared to the control animals. Focusing thus on A2AAR agonist (VT 7) administration (which inhibited the episode of binge systemically at 0.1 mg/kg or intra-central amygdala (CeA) injection at 900 ng/side) induced a significant increase of A2AAR mRNA levels in restricted and stressed rats when compared to the control group. In addition, we observed a significant decrease in A2AAR mRNA levels in rats treated with the A2AAR antagonist (ANR 94) at 1 mg/kg. Consistent changes in the DNA methylation status of the A2AAR promoter were found in restricted and stressed rats after administration of VT 7 or ANR 94. CONCLUSION We confirm the role of A2AAR in binge eating behaviours, and we underline the importance of epigenetic regulation of the A2AAR gene, possibly due to a compensatory mechanism to counteract the effect of binge eating. We suggest that A2AAR activation, inducing receptor gene up-regulation, could be relevant to reduction of food consumption.
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Affiliation(s)
| | - Mariangela Pucci
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | | | - Adele Romano
- Department of Physiology and Pharmacology V. Erspamer, Sapienza University of Rome, Rome, Italy
| | - Catia Lambertucci
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Camerino, Italy
| | - Rosaria Volpini
- School of Pharmacy, Medicinal Chemistry Unit, University of Camerino, Camerino, Italy
| | | | - Silvana Gaetani
- Department of Physiology and Pharmacology V. Erspamer, Sapienza University of Rome, Rome, Italy
| | - Mauro Maccarrone
- Campus Bio-Medico, University of Rome, Rome, Italy
- European Center for Brain Research (CERC)/Santa Lucia Foundation, Rome, Italy
| | - Claudio D'Addario
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
- Department of Clinical Neuroscience, Center for Molecular Medicine, Karolinska Institute, Stockholm, Sweden
| | - Carlo Cifani
- School of Pharmacy, Pharmacology Unit, University of Camerino, Camerino, Italy
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Temido-Ferreira M, Coelho JE, Pousinha PA, Lopes LV. Novel Players in the Aging Synapse: Impact on Cognition. J Caffeine Adenosine Res 2019; 9:104-127. [PMID: 31559391 PMCID: PMC6761599 DOI: 10.1089/caff.2019.0013] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
While neuronal loss has long been considered as the main contributor to age-related cognitive decline, these alterations are currently attributed to gradual synaptic dysfunction driven by calcium dyshomeostasis and alterations in ionotropic/metabotropic receptors. Given the key role of the hippocampus in encoding, storage, and retrieval of memory, the morpho- and electrophysiological alterations that occur in the major synapse of this network-the glutamatergic-deserve special attention. We guide you through the hippocampal anatomy, circuitry, and function in physiological context and focus on alterations in neuronal morphology, calcium dynamics, and plasticity induced by aging and Alzheimer's disease (AD). We provide state-of-the art knowledge on glutamatergic transmission and discuss implications of these novel players for intervention. A link between regular consumption of caffeine-an adenosine receptor blocker-to decreased risk of AD in humans is well established, while the mechanisms responsible have only now been uncovered. We review compelling evidence from humans and animal models that implicate adenosine A2A receptors (A2AR) upsurge as a crucial mediator of age-related synaptic dysfunction. The relevance of this mechanism in patients was very recently demonstrated in the form of a significant association of the A2AR-encoding gene with hippocampal volume (synaptic loss) in mild cognitive impairment and AD. Novel pathways implicate A2AR in the control of mGluR5-dependent NMDAR activation and subsequent Ca2+ dysfunction upon aging. The nature of this receptor makes it particularly suited for long-term therapies, as an alternative for regulating aberrant mGluR5/NMDAR signaling in aging and disease, without disrupting their crucial constitutive activity.
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Affiliation(s)
- Mariana Temido-Ferreira
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Joana E. Coelho
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
| | - Paula A. Pousinha
- Institut de Pharmacologie Moléculaire et Cellulaire (IPMC), CNRS UMR7275, Université Côte d'Azur, Valbonne, France
| | - Luísa V. Lopes
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Lisboa, Portugal
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11
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Carmo M, Gonçalves FQ, Canas PM, Oses JP, Fernandes FD, Duarte FV, Palmeira CM, Tomé AR, Agostinho P, Andrade GM, Cunha RA. Enhanced ATP release and CD73-mediated adenosine formation sustain adenosine A 2A receptor over-activation in a rat model of Parkinson's disease. Br J Pharmacol 2019; 176:3666-3680. [PMID: 31220343 DOI: 10.1111/bph.14771] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Revised: 05/01/2019] [Accepted: 06/01/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Parkinson's disease (PD) involves an initial loss of striatal dopamine terminals evolving into degeneration of dopamine neurons in substantia nigra (SN), which can be modelled by 6-hydroxydopamine (6-OHDA) administration. Adenosine A2A receptor blockade attenuates PD features in animal models, but the source of the adenosine causing A2A receptor over-activation is unknown. As ATP is a stress signal, we have tested if extracellular catabolism of adenine nucleotides into adenosine (through ecto-5'-nucleotidase or CD73) leads to A2A receptor over-activation in PD. EXPERIMENTAL APPROACH Effects of blocking CD73 with α,β-methylene ADP (AOPCP) were assayed in 6-OHDA-treated rats and dopamine-differentiated neuroblastoma SH-SY5Y cells. KEY RESULTS 6-OHDA increased ATP release and extracellular conversion into adenosine through CD73 up-regulation in SH-SY5Y cells. Removing extracellular adenosine with adenosine deaminase, blocking CD73 with AOPCP, or blocking A2A receptors with SCH58261 were equi-effective in preventing 6-OHDA-induced damage in SH-SY5Y cells. In vivo striatal exposure to 6-OHDA increased ATP release and extracellular formation of adenosine from adenosine nucleotides and up-regulated CD73 and A2A receptors in striatal synaptosomes. Intracerebroventricular administration of AOPCP phenocopied effects of SCH58261, attenuating 6-OHDA-induced (a) increase of contralateral rotations after apomorphine, (b) reduction of dopamine content in striatum and SN, (c) loss of TH staining in striatum and SN, (d) motor dysfunction in the cylinder test, and (e) short-term memory impairment in the object recognition test. CONCLUSION AND IMPLICATIONS Our data indicate that increased ATP-derived adenosine formation is responsible for A2A receptor over-activation in PD, suggesting CD73 as a new target to manage PD.
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Affiliation(s)
- Marta Carmo
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza, Brazil
| | - Francisco Q Gonçalves
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Paula M Canas
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Jean-Pierre Oses
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Francisco D Fernandes
- Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza, Brazil
| | - Filipe V Duarte
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | - Carlos M Palmeira
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Department of Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal
| | - Angelo R Tomé
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Department of Life Sciences, Faculty of Science and Technology, University of Coimbra, Coimbra, Portugal
| | - Paula Agostinho
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,FMUC-Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Geanne M Andrade
- Department of Physiology and Pharmacology, Federal University of Ceará, Fortaleza, Brazil
| | - Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,FMUC-Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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12
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Nedeljkovic N. Complex regulation of ecto-5'-nucleotidase/CD73 and A 2AR-mediated adenosine signaling at neurovascular unit: A link between acute and chronic neuroinflammation. Pharmacol Res 2019; 144:99-115. [PMID: 30954629 DOI: 10.1016/j.phrs.2019.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 04/01/2019] [Accepted: 04/03/2019] [Indexed: 12/20/2022]
Abstract
The review summarizes available data regarding the complex regulation of CD73 at the neurovascular unit (NVU) during neuroinflammation. Based on available data we propose the biphasic pattern of CD73 regulation at NVU, with an early attenuation and a postponed up-regulation of CD73 activity. Transient attenuation of CD73 activity on leukocyte/vascular endothelium and leukocyte/astrocyte surface, required for the initiation of a neuroinflammatory response, may be effectuated either by catalytic inhibition of CD73 and/or by shedding of the CD73 molecule from the cell surface, while postponed induction of CD73 is effectuated by transcriptional up-regulation of Nt5e and posttranslational modifications. Neuroinflammatory conditions are also associated with significant enhancement and gain-of-function of A2AR-mediated adenosine signaling. However, in contrast to the temporary prevalence of A2AR over A1R signaling during an acute inflammatory response, prolonged induction of A2AR and resulting perpetual CD73/A2AR coupling may be a contributing factors in the transition between acute and chronic neuroinflammation. Thus, pharmacological targeting of the CD73/A2AR axis may attenuate inflammatory response and ameliorate neurological deficits in chronic neuroinflammatory conditions.
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Affiliation(s)
- Nadezda Nedeljkovic
- Department of General Physiology and Biophysics, Faculty of Biology University of Belgrade, Studentski trg 3, Belgrade 11001, Serbia.
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13
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Neuronal Adenosine A2A Receptors Are Critical Mediators of Neurodegeneration Triggered by Convulsions. eNeuro 2018; 5:eN-NWR-0385-18. [PMID: 30627646 PMCID: PMC6325550 DOI: 10.1523/eneuro.0385-18.2018] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 10/07/2018] [Indexed: 12/20/2022] Open
Abstract
Neurodegeneration is a process transversal to neuropsychiatric diseases and the understanding of its mechanisms should allow devising strategies to prevent this irreversible step in brain diseases. Neurodegeneration caused by seizures is a critical step in the aggravation of temporal lobe epilepsy, but its mechanisms remain undetermined. Convulsions trigger an elevation of extracellular adenosine and upregulate adenosine A2A receptors (A2AR), which have been associated with the control of neurodegenerative diseases. Using the rat and mouse kainate model of temporal lobe epilepsy, we now tested whether A2AR control convulsions-induced hippocampal neurodegeneration. The pharmacological or genetic blockade of A2AR did not affect kainate-induced convulsions but dampened the subsequent neurotoxicity. This neurotoxicity began with a rapid A2AR upregulation within glutamatergic synapses (within 2 h), through local translation of synaptic A2AR mRNA. This bolstered A2AR-mediated facilitation of glutamate release and of long-term potentiation (LTP) in CA1 synapses (4 h), triggered a subsequent synaptotoxicity, heralded by decreased synaptic plasticity and loss of synaptic markers coupled to calpain activation (12 h), that predated overt neuronal loss (24 h). All modifications were prevented by the deletion of A2AR selectively in forebrain neurons. This shows that synaptic A2AR critically control synaptic excitotoxicity, which underlies the development of convulsions-induced neurodegeneration.
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Rajasundaram S. Adenosine A2A Receptor Signaling in the Immunopathogenesis of Experimental Autoimmune Encephalomyelitis. Front Immunol 2018; 9:402. [PMID: 29559972 PMCID: PMC5845642 DOI: 10.3389/fimmu.2018.00402] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Accepted: 02/13/2018] [Indexed: 12/19/2022] Open
Abstract
Our increasing appreciation of adenosine as an endogenous signaling molecule that terminates inflammation has generated excitement regarding the potential to target adenosine receptors (ARs) in the treatment of multiple sclerosis (MS), a disease of chronic neuroinflammation. Of the four G protein-coupled ARs, A2ARs are the principal mediator of adenosine’s anti-inflammatory effects and accordingly, there is a growing body of evidence surrounding the role of A2ARs in experimental autoimmune encephalomyelitis (EAE), the dominant animal model of MS. Such evidence points to a complex, often paradoxical role for A2ARs in the immunopathogenesis of EAE, where they have the ability to both exacerbate and alleviate disease severity. This review seeks to interpret these paradoxical findings and evaluate the therapeutic promise of A2ARs. In essence, the complexities of A2AR signaling arise from two properties. Firstly, A2AR signaling downregulates the inflammatory potential of TH lymphocytes whilst simultaneously facilitating the recruitment of these cells into the CNS. Secondly, A2AR expression by myeloid cells – infiltrating macrophages and CNS-resident microglia – has the capacity to promote both tissue injury and repair in chronic neuroinflammation. Consequently, the therapeutic potential of targeting A2ARs is greatly undermined by the risk of collateral tissue damage in the periphery and/or CNS.
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Huerta-Aguilar CA, Valdivieso SN, Thangarasu P, Camacho-Olguín CA, Reyes-Dominguez IA. Surface-decorated CdS nanoparticles for the recognition of K+ in aqueous medium: DFT and antibacterial studies. RESEARCH ON CHEMICAL INTERMEDIATES 2017. [DOI: 10.1007/s11164-017-3095-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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16
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Cunha RA. How does adenosine control neuronal dysfunction and neurodegeneration? J Neurochem 2016; 139:1019-1055. [PMID: 27365148 DOI: 10.1111/jnc.13724] [Citation(s) in RCA: 320] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Revised: 05/23/2016] [Accepted: 06/23/2016] [Indexed: 12/11/2022]
Abstract
The adenosine modulation system mostly operates through inhibitory A1 (A1 R) and facilitatory A2A receptors (A2A R) in the brain. The activity-dependent release of adenosine acts as a brake of excitatory transmission through A1 R, which are enriched in glutamatergic terminals. Adenosine sharpens salience of information encoding in neuronal circuits: high-frequency stimulation triggers ATP release in the 'activated' synapse, which is locally converted by ecto-nucleotidases into adenosine to selectively activate A2A R; A2A R switch off A1 R and CB1 receptors, bolster glutamate release and NMDA receptors to assist increasing synaptic plasticity in the 'activated' synapse; the parallel engagement of the astrocytic syncytium releases adenosine further inhibiting neighboring synapses, thus sharpening the encoded plastic change. Brain insults trigger a large outflow of adenosine and ATP, as a danger signal. A1 R are a hurdle for damage initiation, but they desensitize upon prolonged activation. However, if the insult is near-threshold and/or of short-duration, A1 R trigger preconditioning, which may limit the spread of damage. Brain insults also up-regulate A2A R, probably to bolster adaptive changes, but this heightens brain damage since A2A R blockade affords neuroprotection in models of epilepsy, depression, Alzheimer's, or Parkinson's disease. This initially involves a control of synaptotoxicity by neuronal A2A R, whereas astrocytic and microglia A2A R might control the spread of damage. The A2A R signaling mechanisms are largely unknown since A2A R are pleiotropic, coupling to different G proteins and non-canonical pathways to control the viability of glutamatergic synapses, neuroinflammation, mitochondria function, and cytoskeleton dynamics. Thus, simultaneously bolstering A1 R preconditioning and preventing excessive A2A R function might afford maximal neuroprotection. The main physiological role of the adenosine modulation system is to sharp the salience of information encoding through a combined action of adenosine A2A receptors (A2A R) in the synapse undergoing an alteration of synaptic efficiency with an increased inhibitory action of A1 R in all surrounding synapses. Brain insults trigger an up-regulation of A2A R in an attempt to bolster adaptive plasticity together with adenosine release and A1 R desensitization; this favors synaptotocity (increased A2A R) and decreases the hurdle to undergo degeneration (decreased A1 R). Maximal neuroprotection is expected to result from a combined A2A R blockade and increased A1 R activation. This article is part of a mini review series: "Synaptic Function and Dysfunction in Brain Diseases".
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Affiliation(s)
- Rodrigo A Cunha
- CNC-Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,FMUC-Faculty of Medicine, University of Coimbra, Coimbra, Portugal
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17
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Time-course of protection by the selective A2A receptor antagonist SCH58261 after transient focal cerebral ischemia. Neurol Sci 2015; 36:1441-8. [DOI: 10.1007/s10072-015-2160-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 03/07/2015] [Indexed: 10/23/2022]
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18
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Huang PC, Hsiao YT, Kao SY, Chen CF, Chen YC, Chiang CW, Lee CF, Lu JC, Chern Y, Wang CT. Adenosine A(2A) receptor up-regulates retinal wave frequency via starburst amacrine cells in the developing rat retina. PLoS One 2014; 9:e95090. [PMID: 24777042 PMCID: PMC4002430 DOI: 10.1371/journal.pone.0095090] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Accepted: 03/23/2014] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Developing retinas display retinal waves, the patterned spontaneous activity essential for circuit refinement. During the first postnatal week in rodents, retinal waves are mediated by synaptic transmission between starburst amacrine cells (SACs) and retinal ganglion cells (RGCs). The neuromodulator adenosine is essential for the generation of retinal waves. However, the cellular basis underlying adenosine's regulation of retinal waves remains elusive. Here, we investigated whether and how the adenosine A(2A) receptor (A(2A)R) regulates retinal waves and whether A(2A)R regulation of retinal waves acts via presynaptic SACs. METHODOLOGY/PRINCIPAL FINDINGS We showed that A(2A)R was expressed in the inner plexiform layer and ganglion cell layer of the developing rat retina. Knockdown of A(2A)R decreased the frequency of spontaneous Ca²⁺ transients, suggesting that endogenous A(2A)R may up-regulate wave frequency. To investigate whether A(2A)R acts via presynaptic SACs, we targeted gene expression to SACs by the metabotropic glutamate receptor type II promoter. Ca²⁺ transient frequency was increased by expressing wild-type A(2A)R (A2AR-WT) in SACs, suggesting that A(2A)R may up-regulate retinal waves via presynaptic SACs. Subsequent patch-clamp recordings on RGCs revealed that presynaptic A(2A)R-WT increased the frequency of wave-associated postsynaptic currents (PSCs) or depolarizations compared to the control, without changing the RGC's excitability, membrane potentials, or PSC charge. These findings suggest that presynaptic A(2A)R may not affect the membrane properties of postsynaptic RGCs. In contrast, by expressing the C-terminal truncated A(2A)R mutant (A(2A)R-ΔC) in SACs, the wave frequency was reduced compared to the A(2A)R-WT, but was similar to the control, suggesting that the full-length A(2A)R in SACs is required for A(2A)R up-regulation of retinal waves. CONCLUSIONS/SIGNIFICANCE A(2A)R up-regulates the frequency of retinal waves via presynaptic SACs, requiring its full-length protein structure. Thus, by coupling with the downstream intracellular signaling, A(2A)R may have a great capacity to modulate patterned spontaneous activity during neural circuit refinement.
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Affiliation(s)
- Pin-Chien Huang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Yu-Tien Hsiao
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Shao-Yen Kao
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Ching-Feng Chen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Yu-Chieh Chen
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chung-Wei Chiang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chien-fei Lee
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Juu-Chin Lu
- Department of Physiology and Pharmacology, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Yijuang Chern
- Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Chih-Tien Wang
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
- Department of Life Science, National Taiwan University, Taipei, Taiwan
- Neurobiology and Cognitive Science Center, National Taiwan University, Taipei, Taiwan
- Genome and Systems Biology Degree Program, National Taiwan University, Taipei, Taiwan
- * E-mail:
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19
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Mode of Action of Adenosine A2A Receptor Antagonists as Symptomatic Treatment for Parkinson's Disease. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2014; 119:87-116. [DOI: 10.1016/b978-0-12-801022-8.00004-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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20
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Induction of murine adenosine A(2A) receptor expression by LPS: analysis of the 5' upstream promoter. Genes Immun 2013; 14:147-53. [PMID: 23328845 DOI: 10.1038/gene.2012.60] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Non-activated macrophages express low levels of A(2A)Rs and lipopolysaccharides (LPS) upregulates A(2A)R expression in an NF-κB-dependent manner. The murine A(2A)R gene is encoded by three exons, m1, m2 and m3. Exons m2 and m3 are conserved, while m1 encodes the 5' untranslated UTR. Three m1 variants have been defined, m1A, m1B and m1C, with m1C being farthest from the transcriptional start site. LPS upregulates A(2A)Rs in primary murine peritoneal and bone-marrow-derived macrophages and RAW264.7 cells by selectively splicing m1C to m2, through a promoter located upstream of m1C. We have cloned ∼1.6 kb upstream of m1C into pGL4.16(luc2CP/Hygro) promoterless vector. This construct in RAW 264.7 cells responds to LPS, and adenosine receptor agonists augmented LPS responsiveness. The NF-κB inhibitors BAY-11 and triptolide inhibited LPS-dependent induction. Deletion of a key proximal NF-κB site (402-417) abrogated LPS responsiveness, while deletion of distal NF-κB and C/EBPβ sites did not. Site-directed mutagenesis of CREB (309-320), STAT1 (526-531) and AP2 (566-569) sites had little effect on LPS and adenosine receptor agonist responsiveness; however, mutation of a second STAT1 site (582-588) abrogated this responsiveness. Further analysis of this promoter should provide valuable insights into regulation of A(2A)R expression in macrophages in response to inflammatory stimuli.
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Varani K, Vincenzi F, Targa M, Corciulo C, Fini M, Setti S, Cadossi R, Borea PA. Effect of pulsed electromagnetic field exposure on adenosine receptors in rat brain. Bioelectromagnetics 2011; 33:279-87. [PMID: 22012856 DOI: 10.1002/bem.20704] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Accepted: 08/24/2011] [Indexed: 01/14/2023]
Abstract
Different effects of pulsed electromagnetic field (PEMF) exposure on brain tissue have been described in pre-clinical models and in clinical settings. Nevertheless, the mechanism of action and the possible interaction with membrane receptors such as adenosine receptors (ARs) has not been investigated. The present study focused on the effect of PEMFs on A1 and A2A ARs in the rat cerebral cortex and cortical neurons. Affinity and density of ARs were evaluated by means of saturation binding experiments while mRNA expression was investigated through retro-transcription polymerase chain reaction (RT-PCR). PEMF treatment of the intact rat cerebral cortex or cortical neurons at 1.5 mT mediated a transient and significant increase in A2A ARs after 4 h (2.0-fold increase) and 6 h (1.4- and 1.8-fold increase, respectively) of exposure. In addition, PEMF treatment of the rat cerebral cortex and rat cortical neurons at 3 mT upregulated A2A ARs after 2 h (2.0- and 2.2-fold increase, respectively) and 4 h (1.6- and 1.9-fold increase, respectively). The treatment of rat cortex membranes with PEMFs at 1.5 and 3 mT induced an increase in A2A AR density after 2 h (1.9- and 2.2-fold increase, respectively) and was constant at all incubation times investigated. In rat cortical neurons, mRNA levels of A1 and A2A ARs were not affected by PEMF exposure for the times and intensities used. These results suggest that PEMF treatment has different biological effects in whole organs or cells in comparison with isolated membranes.
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Affiliation(s)
- Katia Varani
- Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy.
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Dai SS, Zhou YG. Adenosine 2A receptor: a crucial neuromodulator with bidirectional effect in neuroinflammation and brain injury. Rev Neurosci 2011; 22:231-9. [PMID: 21476942 DOI: 10.1515/rns.2011.020] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
This review summarizes recent developments that have contributed to our understanding of how adenosine 2A receptors (A2ARs) modulate brain damage in various animal models of acute neurological injuries, including brain ischemia, traumatic brain injury, spinal cord injury and hemorrhage stroke. The main conclusions are: (1) pharmacological, neurochemical and molecular/genetic approaches to the complex actions of A2AR in different cellular elements suggest that A2AR activation exerts bidirectional effect (detrimental or protective) after brain insults; (2) modulation of glutamate excitotoxicity and neuroinflammation are involved in the protection of A2AR agonists or antagonists, but the bidirectional effect of A2AR is largely due to the bidirectional regulation of neuroinflammation (anti-inflammation or proinflammation) by A2AR on immune cells such as microglia cells and peripheral bone marrow cells; and (3) the bidirectional effect of A2AR on neuroinflammation and brain injury depends on the distinct and sometimes opposite actions of A2AR in various cellular elements and on different injury models and associated pathological conditions. The local glutamate level in the brain injury is one of the crucial factors that contribute to the direction of A2AR effect on neuroinflammation and brain injury outcome. These developments presented here clearly highlight the complexity of using A2AR agents therapeutically in acute neuronal injuries and confirm that A2AR ligands have many promising characteristics that encourage the pursuit of their full therapeutic potential.
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Affiliation(s)
- Shuang-Shuang Dai
- Department of Biochemistry and Molecular Biology, Third Military Medical University, 400038 Chongqing, China
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Armentero MT, Pinna A, Ferré S, Lanciego JL, Müller CE, Franco R. Past, present and future of A(2A) adenosine receptor antagonists in the therapy of Parkinson's disease. Pharmacol Ther 2011; 132:280-99. [PMID: 21810444 DOI: 10.1016/j.pharmthera.2011.07.004] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 07/07/2011] [Indexed: 12/20/2022]
Abstract
Several selective antagonists for adenosine A(2A) receptors (A(2A)R) are currently under evaluation in clinical trials (phases I to III) to treat Parkinson's disease, and they will probably soon reach the market. The usefulness of these antagonists has been deduced from studies demonstrating functional interactions between dopamine D₂ and adenosine A(2A) receptors in the basal ganglia. At present it is believed that A(2A)R antagonists can be used in combination with the dopamine precursor L-DOPA to minimize the motor symptoms of Parkinson's patients. However, a considerable body of data indicates that in addition to ameliorating motor symptoms, adenosine A(2A)R antagonists may also prevent neurodegeneration. Despite these promising indications, one further issue must be considered in order to develop fully optimized antiparkinsonian drug therapy, namely the existence of (hetero)dimers/oligomers of G protein-coupled receptors, a topic that is currently the focus of intense debate within the scientific community. Dopamine D₂ receptors (D₂Rs) expressed in the striatum are known to form heteromers with A(2A) adenosine receptors. Thus, the development of heteromer-specific A(2A) receptor antagonists represents a promising strategy for the identification of more selective and safer drugs.
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Affiliation(s)
- Marie Therese Armentero
- Laboratory of Functional Neurochemistry, Interdepartmental Research Centre for Parkinson's Disease, IRCCS National Institute of Neurology "C. Mondino", Pavia, Italy
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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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25
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Chien CL, Wu YS, Lai HL, Chen YH, Jiang ST, Shih CM, Lin SS, Chang C, Chern Y. Impaired water reabsorption in mice deficient in the type VI adenylyl cyclase (AC6). FEBS Lett 2010; 584:2883-90. [PMID: 20466003 DOI: 10.1016/j.febslet.2010.05.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 04/21/2010] [Accepted: 05/01/2010] [Indexed: 01/27/2023]
Abstract
Adenylyl cyclase (AC) type VI (AC6) is a calcium-inhibitable enzyme which produces cAMP upon stimulation. Herein, we characterized the specific role of AC6 in the kidneys using two AC6-knockout mouse lines. Immunohistochemical staining revealed that AC6 exists in the tubular parts of the nephron and collecting duct. Activities of AC evoked by forskolin or a selective agonist of the V2 vasopressin receptor were lower in the kidneys of AC6-null mice compared to those of wildtype mice. Results of a metabolic cage assay and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) showed for the first time that AC6 plays a critical role in regulating water homeostasis.
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Affiliation(s)
- Chen-Li Chien
- Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
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Morelli M, Carta AR, Kachroo A, Schwarzschild MA. Pathophysiological roles for purines: adenosine, caffeine and urate. PROGRESS IN BRAIN RESEARCH 2010; 183:183-208. [PMID: 20696321 PMCID: PMC3102301 DOI: 10.1016/s0079-6123(10)83010-9] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The motor symptoms of Parkinson's disease (PD) are primarily due to the degeneration of the dopaminergic neurons in the nigrostriatal pathway. However, several other brain areas and neurotransmitters other than dopamine such as noradrenaline, 5-hydroxytryptamine and acetylcholine are affected in the disease. Moreover, adenosine because of the extensive interaction of its receptors with the dopaminergic system has been implicated in the pathophysiology of the disease. Based on the involvement of these non-dopaminergic neurotransmitters in PD and the sometimes severe adverse effects that limit the mainstay use of dopamine-based anti-parkinsonian treatments, recent assessments have called for a broadening of therapeutic options beyond the traditional dopaminergic drug arsenal. In this review we describe the interactions between dopamine and adenosine receptors that underpin the pre-clinical and clinical rationale for pursuing adenosine A(2A) receptor antagonists as symptomatic and potentially neuroprotective treatment of PD. The review will pay particular attention to recent results regarding specific A(2A) receptor-receptor interactions and recent findings identifying urate, the end product of purine metabolism, as a novel prognostic biomarker and candidate neuroprotectant in PD.
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Affiliation(s)
- Micaela Morelli
- Department of Toxicology, University of Cagliari, Cagliari, Italy.
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Pugliese AM, Traini C, Cipriani S, Gianfriddo M, Mello T, Giovannini MG, Galli A, Pedata F. The adenosine A2A receptor antagonist ZM241385 enhances neuronal survival after oxygen-glucose deprivation in rat CA1 hippocampal slices. Br J Pharmacol 2009; 157:818-30. [PMID: 19422385 PMCID: PMC2721266 DOI: 10.1111/j.1476-5381.2009.00218.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2008] [Revised: 12/12/2008] [Accepted: 01/19/2009] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND AND PURPOSE Activation of adenosine A(2A) receptors in the CA1 region of rat hippocampal slices during oxygen-glucose deprivation (OGD), a model of cerebral ischaemia, was investigated. EXPERIMENTAL APPROACH We made extracellular recordings of CA1 field excitatory postsynaptic potentials (fepsps) followed by histochemical and immunohistochemical techniques coupled to Western blots. KEY RESULTS OGD (7 or 30 min duration) elicited an irreversible loss of fepsps invariably followed by the appearance of anoxic depolarization (AD), an unambiguous sign of neuronal damage. The application of the selective adenosine A(2A) receptor antagonist, ZM241385 (4-(2-[7-amino-2-{2-furyl}{1,2,4}triazolo{2,3-a}{1,3,5}triazin-5-ylamino]ethyl)phenol; 100-500 nmolxL(-1)) prevented or delayed AD appearance induced by 7 or 30 min OGD and protected from the irreversible fepsp depression elicited by 7 min OGD. Two different selective adenosine A(2A) receptor antagonists, SCH58261 and SCH442416, were less effective than ZM241385 during 7 min OGD. The extent of CA1 cell injury was assessed 3 h after the end of 7 min OGD by propidium iodide. Substantial CA1 pyramidal neuronal damage occurred in untreated slices, exposed to OGD, whereas injury was significantly prevented by 100 nmolxL(-1) ZM241385. Glial fibrillary acid protein (GFAP) immunostaining showed that 3 h after 7 min OGD, astrogliosis was appreciable. Western blot analysis indicated an increase in GFAP 30 kDa fragment which was significantly reduced by treatment with 100 nmolxL(-1) ZM241385. CONCLUSIONS AND IMPLICATIONS In the CA1 hippocampus, antagonism of A(2A) adenosine receptors by ZM241385 was protective during OGD (a model of cerebral ischaemia) by delaying AD appearance, decreasing astrocyte activation and improving neuronal survival.
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Affiliation(s)
- A M Pugliese
- Department of Preclinical and Clinical Pharmacology, University of Florence, Florence, Italy
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Chiang MC, Chen HM, Lai HL, Chen HW, Chou SY, Chen CM, Tsai FJ, Chern Y. The A2A adenosine receptor rescues the urea cycle deficiency of Huntington's disease by enhancing the activity of the ubiquitin-proteasome system. Hum Mol Genet 2009; 18:2929-42. [PMID: 19443488 DOI: 10.1093/hmg/ddp230] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. The resultant mutant Htt protein (mHtt) forms aggregates in the brain and several peripheral tissues (e.g. the liver) and causes devastating neuronal degeneration. Metabolic defects resulting from Htt aggregates in peripheral tissues also contribute to HD pathogenesis. Simultaneous improvement of defects in both the CNS and peripheral tissues is thus the most effective therapeutic strategy and is highly desirable. We earlier showed that an agonist of the A(2A) adenosine receptor (A(2A) receptor), CGS21680 (CGS), attenuates neuronal symptoms of HD. We found herein that the A(2A) receptor also exists in the liver, and that CGS ameliorated the urea cycle deficiency by reducing mHtt aggregates in the liver. By suppressing aggregate formation, CGS slowed the hijacking of a crucial transcription factor (HSF1) and two protein chaperons (Hsp27 and Hsp70) into hepatic Htt aggregates. Moreover, the abnormally high levels of high-molecular-mass ubiquitin conjugates in the liver of an HD mouse model (R6/2) were also ameliorated by CGS. The protective effect of CGS against mHtt-induced aggregate formation was reproduced in two cells lines and was prevented by an antagonist of the A(2A) receptor and a protein kinase A (PKA) inhibitor. Most importantly, the mHtt-induced suppression of proteasome activity was also normalized by CGS through PKA. Our findings reveal a novel therapeutic pathway of A(2A) receptors in HD and further strengthen the concept that the A(2A) receptor can be a drug target in treating HD.
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Affiliation(s)
- Ming-Chang Chiang
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei 115, Taiwan, Republic of China
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Melani A, Cipriani S, Vannucchi MG, Nosi D, Donati C, Bruni P, Giovannini MG, Pedata F. Selective adenosine A2a receptor antagonism reduces JNK activation in oligodendrocytes after cerebral ischaemia. Brain 2009; 132:1480-95. [PMID: 19359287 DOI: 10.1093/brain/awp076] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Adenosine is a potent biological mediator, the concentration of which increases dramatically following brain ischaemia. During ischaemia, adenosine is in a concentration range (muM) that stimulates all four adenosine receptor subtypes (A(1), A(2A), A(2B) and A(3)). In recent years, evidence has indicated that the A(2A) receptor subtype is of critical importance in stroke. We have previously shown that 24 h after medial cerebral artery occlusion (MCAo), A(2A) receptors up-regulate on neurons and microglia of ischaemic striatum and cortex and that subchronically administered adenosine A(2A) receptor antagonists protect against brain damage and neurological deficit and reduce activation of p38 mitogen-activated protein kinase (MAPK) in microglial cells. The mechanisms by which A(2A) receptors are noxious during ischaemia still remain elusive. The objective of the present study was to investigate whether the adenosine A(2A) antagonist SCH58261 affects JNK and MEK1/ERK MAPK activation. A further aim was to investigate cell types expressing activated JNK and MEK1/ERK MAPK after ischaemia. We hereby report that the selective adenosine A(2A) receptor antagonist, SCH58261, administered subchronically (0.01 mg/kg i.p) 5 min, 6 and 20 h after MCAo in male Wistar rats, reduced JNK MAPK activation (immunoblot analysis: phospho-JNK54 isoform by 81% and phospho-JNK46 isoform by 60%) in the ischaemic striatum. Twenty-four hours after MCAo, the Olig2 transcription factor of oligodendroglial progenitor cells and mature oligodendrocytes was highly expressed in cell bodies in the ischaemic striatum. Immunofluorescence staining showed that JNK MAPK is maximally expressed in Olig2-stained oligodendrocytes and in a few NeuN stained neurons. Striatal cell fractioning into nuclear and extra-nuclear fractions demonstrated the presence of Olig2 transcription factor and JNK MAPK in both fractions. The A(2A) antagonist reduced striatal Olig 2 transcription factor (immunoblot analysis: by 55%) and prevented myelin disorganization, assessed by myelin-associated glycoprotein staining. Twenty-four hours after MCAo, ERK1/2 MAPK was highly activated in the ischaemic striatum, mostly in microglia, while it was reduced in the ischaemic cortex. The A(2A) antagonist did not affect activation of the ERK1/2 pathway. The efficacy of A(2A) receptor antagonism in reducing activation of JNK MAPK in oligodendrocytes suggests a mechanism of protection consisting of scarring oligodendrocyte inhibitory molecules that can hinder myelin reconstitution and neuron functionality.
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Affiliation(s)
- Alessia Melani
- Department of Preclinical and Clinical Pharmacology, University of Florence, Viale Pieraccini, 6, Florence, Italy
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González A, Salido GM. Ethanol alters the physiology of neuron-glia communication. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 88:167-98. [PMID: 19897078 DOI: 10.1016/s0074-7742(09)88007-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In the central nervous system (CNS), both neurones and astrocytes play crucial roles. On a cellular level, brain activity involves continuous interactions within complex cellular circuits established between neural cells and glia. Although it was initially considered that neurones were the major cell type in cerebral function, nowadays astrocytes are considered to contribute to cerebral function too. Astrocytes support normal neuronal activity, including synaptic function, by regulating the extracellular environment with respect to ions and neurotransmitters. There is a plethora of noxious agents which can lead to the development of alterations in organs and functional systems, and that will end in a chronic prognosis. Among the potentially harmful external agents we can find ethanol consumption, whose consequences have been recognized as a major public health concern. Deregulation of cell cycle has devastating effects on the integrity of cells, and has been closely associated with the development of pathologies which can lead to dysfunction and cell death. An alteration of normal neuronal-glial physiology could represent the basis of neurodegenerative processes. In this review we will pay attention on to the recent findings in astrocyte function and their role toward neurons under ethanol consumption.
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Affiliation(s)
- Antonio González
- Department of Physiology (Cell Physiology Research Group), University of Extremadura, 10071, Cáceres, Spain
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31
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St Hilaire C, Carroll SH, Chen H, Ravid K. Mechanisms of induction of adenosine receptor genes and its functional significance. J Cell Physiol 2008; 218:35-44. [PMID: 18767039 DOI: 10.1002/jcp.21579] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Adenosine is a metabolite generated and released from cells, particularly under injury or stress. It elicits protective or damaging responses via signaling through the adenosine receptors, including the adenylyl cyclase inhibitory A(1) and A(3), and the adenylyl cyclase stimulatory A(2A) and A(2B). Multiple adenosine receptor types, including stimulatory and inhibitory, can be found in the same cell, suggesting that a careful balance of adenosine receptor expression in a particular cell is necessary for a specific adenosine-induced response. This balance could be controlled by differential expression of the adenosine receptor genes under different stimuli. Here, we have reviewed an array of studies that have characterized basal or induced expression of the adenosine receptors and common as well as distinct mechanisms of effect, in hopes that ongoing studies on this topic will further elucidate detailed mechanisms of adenosine receptor regulation, leading to potential therapeutic applications.
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Affiliation(s)
- Cynthia St Hilaire
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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32
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Brooks DJ, Doder M, Osman S, Luthra SK, Hirani E, Hume S, Kase H, Kilborn J, Martindill S, Mori A. Positron emission tomography analysis of [11C]KW-6002 binding to human and rat adenosine A2A receptors in the brain. Synapse 2008; 62:671-81. [PMID: 18566974 DOI: 10.1002/syn.20539] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Adenosine A(2A) receptors are found on striatal neurones projecting to the external pallidum. KW-6002 (istradefylline) is a potent and selective antagonist for the adenosine A(2A) receptors in the CNS and acts to inhibit the excessive activity of this pathway in the MPTP marmoset model of PD, thus relieving parkinsonism. The objectives of this study were to investigate the regional binding of the novel positron emission tomography tracer [(11)C]KW-6002 in the healthy human brain and the rat brain, along with receptor occupancy by cold KW-6002 at varying doses in human. The highest [(11)C]KW-6002 uptake in the rat brain was seen in striatum and lower levels in cortex and cerebellum. Brain [(11)C]KW-6002 uptake was well characterized in humans by a two-tissue compartmental model with a blood volume term, and the ED(50) of cold KW-6002 was 0.5 mg in the striatum. Over 90% receptor occupancy was achieved with daily oral doses of greater than 5 mg. In humans, blockable binding was present in all gray matter structures including the cerebellum, which has not been reported to express A(2A) receptors. MRS 1745, an A(2B) receptor selective antagonist, had no effect on the cerebellar binding of [(11)C]KW-6002 in rats, suggesting that this blockable signal is unlikely to result from an affinity for adenosine A(2B) receptors.
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Affiliation(s)
- D J Brooks
- MRC Clinical Sciences Centre and Division of Neuroscience, Faculty of Medicine, Imperial College, London, United Kingdom
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33
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Chen JF, Sonsalla PK, Pedata F, Melani A, Domenici MR, Popoli P, Geiger J, Lopes LV, de Mendonça A. Adenosine A2A receptors and brain injury: Broad spectrum of neuroprotection, multifaceted actions and “fine tuning” modulation. Prog Neurobiol 2007; 83:310-31. [DOI: 10.1016/j.pneurobio.2007.09.002] [Citation(s) in RCA: 180] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2007] [Revised: 08/10/2007] [Accepted: 09/21/2007] [Indexed: 10/22/2022]
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Trincavelli ML, Melani A, Guidi S, Cuboni S, Cipriani S, Pedata F, Martini C. Regulation of A(2A) adenosine receptor expression and functioning following permanent focal ischemia in rat brain. J Neurochem 2007; 104:479-90. [PMID: 17953669 DOI: 10.1111/j.1471-4159.2007.04990.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Ischemia, through modulation of adenosine receptors (ARs), may influence adenosine-mediated-cellular responses. In the present study, we investigated the modulation of rat A(2A) receptor expression and functioning, in rat cerebral cortex and striatum, following in vivo focal ischemia (24 h). In cortex, middle cerebral artery occlusion did not induce any alterations in A(2A) receptor binding and functioning. On the contrary, in striatum, a significant decrease in A(2A) ligand affinity, associated with an increase in receptor density, were detected. In striatum, ischemia also induced a significant reduction both in G protein pool and in A(2A) receptor-G protein coupling. On the contrary, A(2A) receptor functional responsiveness, measured as stimulation of adenylyl cyclise, was not affected by ischemia, suggesting receptor up-regulation may represent a compensatory mechanism to maintain receptor functioning during cerebral damage. Immunohistochemical study showed that following 24 h middle cerebral artery occlusion, A(2A) ARs were definitely expressed both on neurons and activated microglia in ischemic striatum and cortex, but were not detected on astrocytes. In the non-ischemic hemisphere and in sham-operated rats A(2A) ARs were barely detected. Modifications of ARs may play a significant role in determining adenosine effects during ischemia and therefore should be taken into account when evaluating time-dependent protective effects of specific A(2A) active compounds.
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Affiliation(s)
- Maria L Trincavelli
- Department of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, Pisa, Italy
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35
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The role of ATP and adenosine in the brain under normoxic and ischemic conditions. Purinergic Signal 2007; 3:299-310. [PMID: 18404443 PMCID: PMC2072927 DOI: 10.1007/s11302-007-9085-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Accepted: 09/25/2007] [Indexed: 01/01/2023] Open
Abstract
By taking advantage of some recently synthesized compounds that are able to block ecto-ATPase activity, we demonstrated that adenosine triphosphate (ATP) in the hippocampus exerts an inhibitory action independent of its degradation to adenosine. In addition, tonic activation of P2 receptors contributes to the normally recorded excitatory neurotransmission. The role of P2 receptors becomes critical during ischemia when extracellular ATP concentrations increase. Under such conditions, P2 antagonism is protective. Although ATP exerts a detrimental role under ischemia, it also exerts a trophic role in terms of cell division and differentiation. We recently reported that ATP is spontaneously released from human mesenchymal stem cells (hMSCs) in culture. Moreover, it decreases hMSC proliferation rate at early stages of culture. Increased hMSC differentiation could account for an ATP-induced decrease in cell proliferation. ATP as a homeostatic regulator might exert a different effect on cell trophism according to the rate of its efflux and receptor expression during the cell life cycle. During ischemia, adenosine formed by intracellular ATP escapes from cells through the equilibrative transporter. The protective role of adenosine A(1) receptors during ischemia is well accepted. However, the use of selective A(1) agonists is hampered by unwanted peripheral effects, thus attention has been focused on A(2A) and A(3) receptors. The protective effects of A(2A) antagonists in brain ischemia may be largely due to reduced glutamate outflow from neurones and glial cells. Reduced activation of p38 mitogen-activated protein kinases that are involved in neuronal death through transcriptional mechanisms may also contribute to protection by A(2A) antagonism. Evidence that A(3) receptor antagonism may be protective after ischemia is also reported.
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Fredholm BB, Chern Y, Franco R, Sitkovsky M. Aspects of the general biology of adenosine A2A signaling. Prog Neurobiol 2007; 83:263-76. [PMID: 17804147 DOI: 10.1016/j.pneurobio.2007.07.005] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2007] [Revised: 04/05/2007] [Accepted: 07/19/2007] [Indexed: 01/10/2023]
Abstract
Many of our current hopes of finding better ways to treat Parkinson's disease or to stop its progression rely on studies of adenosine A2A receptors in the brain. Yet any drug targeting central receptors will also potentially affect receptors in other sites. Furthermore, several fundamental aspects of adenosine receptor biology must be taken into account. For these reasons the "Targeting adenosine A2A receptors in Parkinson's disease and other CNS disorders" meeting in Boston included selected aspects of the general biology of adenosine A2A receptor signaling. Some of the presentations from this part of the meeting are summarized in this first chapter. As will be apparent to the reader, these different parts do not form an integrated whole, but they do indicate areas the organizers felt might illuminate remaining questions regarding the roles of adenosine A2A receptors. The contributors to this part of the meeting have summarized some of the key questions below.
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MESH Headings
- Adenosine/metabolism
- Animals
- Dimerization
- Encephalitis/genetics
- Encephalitis/immunology
- Encephalitis/metabolism
- Humans
- Hypoxia, Brain/genetics
- Hypoxia, Brain/immunology
- Hypoxia, Brain/metabolism
- Hypoxia-Inducible Factor 1, alpha Subunit/genetics
- Hypoxia-Inducible Factor 1, alpha Subunit/immunology
- Hypoxia-Inducible Factor 1, alpha Subunit/metabolism
- Parkinson Disease/genetics
- Parkinson Disease/immunology
- Parkinson Disease/metabolism
- Receptor, Adenosine A2A/genetics
- Receptor, Adenosine A2A/metabolism
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Signal Transduction/genetics
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Affiliation(s)
- Bertil B Fredholm
- Department of Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden.
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Minghetti L, Greco A, Potenza RL, Pezzola A, Blum D, Bantubungi K, Popoli P. Effects of the adenosine A2A receptor antagonist SCH 58621 on cyclooxygenase-2 expression, glial activation, and brain-derived neurotrophic factor availability in a rat model of striatal neurodegeneration. J Neuropathol Exp Neurol 2007; 66:363-71. [PMID: 17483693 DOI: 10.1097/nen.0b013e3180517477] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Inhibition of adenosine A2A receptors (A2ARs) is neuroprotective in several experimental models of striatal diseases. However, the mechanisms elicited by A2AR blockade are only partially known, and critical aspects about the potential beneficial effects of A2AR antagonism in models of neurodegeneration still await elucidation. In the present study, we analyzed the influence of the selective A2AR antagonist SCH 58261 in a rat model of striatal excitotoxicity obtained by unilateral intrastriatal injection of quinolinic acid (QA). We found that SCH 58261 differently affected the expression of cyclooxygenase-2 (COX-2) induced by QA in cortex and striatum. The antagonist enhanced COX-2 expression in cortical neurons and prevented it in striatal microglia-like cells. Similarly, SCH 58261 differently regulated astrogliosis and microglial activation in the 2 brain regions. In addition, the A2AR antagonist prevented the QA-induced increase in striatal brain-derived neurotrophic factor levels. Because COX-2 activity has been linked to excitotoxic processes and because brain-derived neurotrophic factor depletion has been observed in mouse models as well as in patients with Huntington disease, we suggest that the final outcome of A2AR blockade (namely neuroprotection vs neurodegeneration) is likely to depend on the balance among its various and region-specific effects.
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Affiliation(s)
- Luisa Minghetti
- From the Departments of Cell Biology and Neuroscience, Istituto Superiore di Sanità, Rome, Italy.
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Castillo CA, Albasanz JL, Fernández M, Martín M. Endogenous Expression of Adenosine A1, A2 and A3 Receptors in Rat C6 Glioma Cells. Neurochem Res 2007; 32:1056-70. [PMID: 17401671 DOI: 10.1007/s11064-006-9273-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2006] [Accepted: 12/22/2006] [Indexed: 10/23/2022]
Abstract
Inhibitory and stimulatory adenosine receptors have been identified and characterized in both membranes and intact rat C6 glioma cells. In membranes, saturation experiment performed with [(3)H]DPCPX, selective A(1)R antagonist, revealed a single binding site with a K (D) = 9.4 +/- 1.4 nM and B (max) = 62.7 +/- 8.6 fmol/mg protein. Binding of [(3)H]DPCPX in intact cell revealed a K (D) = 17.7 +/- 1.3 nM and B (max )= 567.1 +/- 26.5 fmol/mg protein. On the other hand, [(3)H]ZM241385 binding experiments revealed a single binding site population of receptors with K (D) = 16.5 +/- 1.3 nM and B (max) = 358.9 +/- 52.4 fmol/mg protein in intact cells, and K (D) = 4.7 +/- 0.6 nM and B (max) = 74.3 +/- 7.9 fmol/mg protein in plasma membranes, suggesting the presence of A(2A) receptor in C6 cells. A(1), A(2A), A(2B) and A(3 )adenosine receptors were detected by Western-blotting and immunocytochemistry, and their mRNAs quantified by real time PCR assays. Gialpha and Gsalpha proteins were also detected by Western-blotting and RT-PCR assays. Furthermore, selective A(1)R agonists inhibited forskolin- and GTP-stimulated adenylyl cyclase activity and CGS 21680 and NECA stimulated this enzymatic activity in C6 cells. These results suggest that C6 glioma cells endogenously express A(1) and A(2) receptors functionally coupled to adenylyl cyclase inhibition and stimulation, respectively, and suggest these cells as a model to study the role of adenosine receptors in tumoral cells.
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Affiliation(s)
- Carlos Alberto Castillo
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Ciudad Real, Spain
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39
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Chiang MC, Chen HM, Lee YH, Chang HH, Wu YC, Soong BW, Chen CM, Wu YR, Liu CS, Niu DM, Wu JY, Chen YT, Chern Y. Dysregulation of C/EBPalpha by mutant Huntingtin causes the urea cycle deficiency in Huntington's disease. Hum Mol Genet 2007; 16:483-98. [PMID: 17213233 DOI: 10.1093/hmg/ddl481] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion in the Huntingtin (Htt) gene. Using two mouse models of HD, we demonstrate that the urea cycle deficiency characterized by hyperammonemia, high blood citrulline and suppression of urea cycle enzymes is a prominent feature of HD. The resultant ammonia toxicity might exacerbate the neurological deficits of HD. Suppression of C/EBPalpha, a crucial transcription factor for the transcription of urea cycle enzymes, appears to mediate the urea cycle deficiency in HD. We found that in the presence of mutant Htt, C/EBPalpha loses its ability to interact with an important cofactor (CREB-binding protein). Moreover, mutant Htt recruited C/EBPalpha into aggregates, as well as suppressed expression of the C/EBPalpha gene. Consumption of protein-restricted diets not only led to the restoration of C/EBPalpha's activity, and repair of the urea cycle deficiency and hyperammonemia, but also ameliorated the formation of Htt aggregates, the motor deterioration, the suppression of striatal brain-derived neurotrophic factor and the normalization of three protein chaperones (Hsp27, Hsp70 and Hsp90). Treatments aimed at repairing the urea cycle deficiency may provide a new strategy for dealing with HD.
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Affiliation(s)
- Ming-Chang Chiang
- Institute of Biomedical Sciences, Academia Sinica, Nankang, Taipei, Taiwan
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Gonzalez B, Paz F, Florán L, Aceves J, Erlij D, Florán B. Adenosine A2A receptor stimulation decreases GAT-1-mediated GABA uptake in the globus pallidus of the rat. Neuropharmacology 2006; 51:154-9. [PMID: 16730753 DOI: 10.1016/j.neuropharm.2006.03.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2005] [Revised: 02/17/2006] [Accepted: 03/13/2006] [Indexed: 11/20/2022]
Abstract
We examined modulation of [(3)H]GABA uptake in slices of the rat globus pallidus because stimulation of adenosine A(2A) receptors increases extracellular GABA in this structure. Pharmacological analysis showed that GAT-1 is the main transporter present in these slices. Both adenosine and the A(2A) agonist CGS 21680 reduced GABA uptake. Antagonist ZM 241385 prevented these effects. Agents that increase protein kinase A activity like forskolin and 8-bromo-cAMP also inhibited GABA uptake. The inhibition of uptake produced by these substances and by CGS 21680 was prevented by the protein kinase A blocker H-89. The protein phosphatase blocker okadaic acid reduced uptake; this effect and the response to CGS 21680 were not additive. The effective concentrations of adenosine (EC(50)=15.2microM) are within the range measured in the interstitial fluid under some physiological conditions. Thus, inhibition of uptake may be important in increasing interstitial GABA during endogenous adenosine release.
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Affiliation(s)
- Brenda Gonzalez
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados, Apartado Postal 14-740, 07000 México DF, México
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Sun CN, Cheng HC, Chou JL, Lee SY, Lin YW, Lai HL, Chen HM, Chern Y. Rescue of p53 Blockage by the A2AAdenosine Receptor via a Novel Interacting Protein, Translin-Associated Protein X. Mol Pharmacol 2006; 70:454-66. [PMID: 16617164 DOI: 10.1124/mol.105.021261] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Blockage of the p53 tumor suppressor has been found to impair nerve growth factor (NGF)-induced neurite outgrowth in PC-12 cells. We report herein that such impairment could be rescued by stimulation of the A(2A) adenosine receptor (A(2A)-R), a G protein-coupled receptor implicated in neuronal plasticity. The A(2A)-R-mediated rescue occurred in the presence of protein kinase C (PKC) inhibitors or protein kinase A (PKA) inhibitors and in a PKA-deficient PC-12 variant. Thus, neither PKA nor PKC was involved. In contrast, expression of a truncated A(2A)-R mutant harboring the seventh transmembrane domain and its C terminus reduced the rescue effect of A(2A)-R. Using the cytoplasmic tail of the A(2A)-R as bait, a novel-A(2A)-R-interacting protein [translin-associated protein X (TRAX)] was identified in a yeast two-hybrid screen. The authenticity of this interaction was verified by pull-down experiments, coimmunoprecipitation, and colocalization of these two molecules in the brain. It is noteworthy that reduction of TRAX using an antisense construct suppressed the rescue effect of A(2A)-R, whereas overexpression of TRAX alone caused the same rescue effect as did A(2A)-R activation. Results of [(3)H]thymidine and bromodeoxyuridine incorporation suggested that A(2A)-R stimulation inhibited cell proliferation in a TRAX-dependent manner. Because the antimitotic activity is crucial for NGF function, the A(2A)-R might exert its rescue effect through a TRAX-mediated antiproliferative signal. This antimitotic activity of the A(2A)-R also enables a mitogenic factor (epidermal growth factor) to induce neurite outgrowth. We demonstrate that the A(2A)-R modulates the differentiation ability of trophic factors through a novel interacting protein, TRAX.
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Affiliation(s)
- Chung-Nan Sun
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan
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42
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Melani A, Gianfriddo M, Vannucchi MG, Cipriani S, Baraldi PG, Giovannini MG, Pedata F. The selective A2A receptor antagonist SCH 58261 protects from neurological deficit, brain damage and activation of p38 MAPK in rat focal cerebral ischemia. Brain Res 2006; 1073-1074:470-80. [PMID: 16443200 DOI: 10.1016/j.brainres.2005.12.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 11/22/2005] [Accepted: 12/05/2005] [Indexed: 12/01/2022]
Abstract
We investigated the protective effect of subchronic treatment of the A2A receptor antagonist, SCH 58261 (0.01 mg/kg, i.p.), administered 5 min, 6 h and 15 h after permanent right middle cerebral artery occlusion (MCAo). Twenty-four hours after ischemia, an extensive pallid area, evaluated by cresyl violet staining, is evident in the vascular territories supplied by the MCA, the striatum and the sensory motor cortex. The pallid area reflects the extent of necrotic neurons. Soon after waking, rats showed a definite contralateral turning behavior which was significantly reduced by SCH 58261 treatment. Twenty-four hours after MCAo, SCH 58261 significantly improved the neurological deficit and reduced ischemic damage in the striatum and cortex. Phospho-p38 mitogen-activated protein kinase (MAPK), evaluated by Western Blot, increased by 500% in the ischemic striatum 24 h after MCAo. SCH 58261 treatment significantly reduced phospho-p38 MAPK by 70%. Microglia was immunostained using the OX-42 antibody. Phospho-p38 MAPK and OX-42-immunoreactive cells are localized in the ventral striatum and frontoparietal cortex. Furthermore, both OX-42 and phospho-p38 MAPK-immunoreactive cells have overlapping morphological features, typical of reactive microglia. SCH 58261 reduced phospho-p38 MAPK immunoreactivity in the striatum and in the cortex without changing the microglial cell morphology. These results indicate that the protective effect of the adenosine antagonist SCH 58261 during ischemia is not due to reduced microglial activation but involves inhibition of phospho-p38 MAPK and suggest that treatment with the A2A antagonist from the first hour to several hours after ischemia may be a useful therapeutic approach in cerebral ischemia.
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Affiliation(s)
- Alessia Melani
- Department of Pharmacology, University of Florence, Viale Pieraccini 6, 50139 Florence, Italy
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Chiang MC, Lee YC, Huang CL, Chern Y. cAMP-response Element-binding Protein Contributes to Suppression of the A2A Adenosine Receptor Promoter by Mutant Huntingtin with Expanded Polyglutamine Residues. J Biol Chem 2005; 280:14331-40. [PMID: 15689617 DOI: 10.1074/jbc.m413279200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Huntington's disease is a neurodegenerative disease resulting from a CAG (glutamine) trinucleotide expansion in exon 1 of the Huntingtin (Htt) gene. The role of the striatum-enriched A2A adenosine receptor (A2A-R) in Huntington's disease has attracted much attention lately. In the present study, we found that expression of mutant Htt with expanded poly(Q) significantly reduced the transcript levels of the endogenous A2A-R in PC12 cells and primary striatal neurons. Cotransfection of various promoter constructs of the A2A-R gene and an expression construct of poly(Q)-expanded Htt revealed that the Htt mutant suppressed the core promoter activity of the A2A-R gene. Stimulation of the A2A-R using CGS21680, forskolin, and a constitutively active cAMP-response element-binding protein (CREB) mutant elevated the reduced promoter activity of the A2A-R gene by mutant Htt. Moreover, the effect of CGS was blocked by an A2A-R-selective antagonist (CSC), two inhibitors of protein kinase A, and two dominant negative mutants of (CREB). The protein kinase A/CREB pathway therefore is involved in regulating A2A-R promoter activity. Consistently, an atypical CRE site (TCCAGG) is located in the core promoter region of the A2A-R gene. Electrophoretic gel mobility shift assay and mutational inactivation further demonstrated the functional binding of CREB to the core promoter region and showed that expression of poly(Q)-expanded Htt abolished the binding of CREB to this site. Stimulation of the A2A-R restored the reduced CREB binding caused by the mutant and concurrently reduced mutant Htt aggregation. Collectively, the poly(Q)-expanded mutant Htt suppressed expression of the A2A-R by inhibiting its core promoter at least partially by preventing CREB binding.
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Affiliation(s)
- Ming-Chang Chiang
- Division of Neuroscience, Institute of Biomedical Sciences, Academia Sinica and Institute of Neuroscience, National Yang Ming University, Taipei 11529, Taiwan
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Chou SY, Lee YC, Chen HM, Chiang MC, Lai HL, Chang HH, Wu YC, Sun CN, Chien CL, Lin YS, Wang SC, Tung YY, Chang C, Chern Y. CGS21680 attenuates symptoms of Huntington's disease in a transgenic mouse model. J Neurochem 2005; 93:310-20. [PMID: 15816854 DOI: 10.1111/j.1471-4159.2005.03029.x] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by a CAG trinucleotide expansion in exon 1 of the Huntingtin (Htt) gene. We show herein that in an HD transgenic mouse model (R6/2), daily administration of CGS21680 (CGS), an A(2A) adenosine receptor (A(2A)-R)-selective agonist, delayed the progressive deterioration of motor performance and prevented a reduction in brain weight. 3D-microMRI analysis revealed that CGS reversed the enlarged ventricle-to-brain ratio of R6/2 mice, with particular improvements in the left and right ventricles. (1)H-MRS showed that CGS significantly reduced the increased choline levels in the striatum. Immunohistochemical analyses further demonstrated that CGS reduced the size of ubiquitin-positive neuronal intranuclear inclusions (NIIs) in the striatum of R6/2 mice and ameliorated mutant Htt aggregation in a striatal progenitor cell line overexpressing mutant Htt with expanded polyQ. Moreover, chronic CGS treatment normalized the elevated blood glucose levels and reduced the overactivation of a major metabolic sensor [5'AMP-activated protein kinase (AMPK)] in the striatum of R6/2 mice. Since AMPK is a master switch for energy metabolism, modulation of energy dysfunction caused by the mutant Htt might contribute to the beneficial effects of CGS. Collectively, CGS is a potential drug candidate for the treatment of HD.
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Affiliation(s)
- Szu-Yi Chou
- Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
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45
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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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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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Rebola N, Canas PM, Oliveira CR, Cunha RA. Different synaptic and subsynaptic localization of adenosine A2A receptors in the hippocampus and striatum of the rat. Neuroscience 2005; 132:893-903. [PMID: 15857695 DOI: 10.1016/j.neuroscience.2005.01.014] [Citation(s) in RCA: 154] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2004] [Revised: 01/03/2005] [Accepted: 01/06/2005] [Indexed: 11/30/2022]
Abstract
Adenosine A(2A) receptors are most abundant in the striatum where they control the striatopallidal pathway thus controlling locomotion. Extra-striatal A(2A) receptors are considerably less abundant but their blockade confers robust neuroprotection. We now have investigated if striatal and extra-striatal A(2A) receptors have a different neuronal location to understand their different functions. The binding density of the A(2A) antagonist, [(3)H]-7-(2-phenylethyl)-5-amino-2-(2-furyl)pyrazolo[4,3e][1,2,4]triazolo[1,5-c]pyrimidine ([(3)H]SCH 58261), was enriched in nerve terminals membranes (B(max)=103+/-12 fmol/mg protein) compared with total membranes (B(max)=29+/-4 fmol/mg protein) from the hippocampus, the same occurring with A(2A) receptor immunoreactivity. In contrast, there was no enrichment of [(3)H]SCH 58261 binding or A(2A) receptor immunoreactivity in synaptosomal compared with total membranes from the striatum. Further subcellular fractionation of hippocampal nerve terminals revealed that A(2A) receptor immunoreactivity was enriched in the active zone of presynaptic nerve terminals, whereas it was predominantly located in the postsynaptic density in the striatum, although a minority of striatal A(2A) receptors were located in the presynaptic active zone. These results indicate that A(2A) receptors in the striatum are not enriched in synapses in agreement with the preponderant role of A(2A) receptors in signal processing in striatopallidal neurons. In contrast, hippocampal A(2A) receptors are enriched in synapses, mainly in the active zone, in accordance with their role in controlling neurotransmitter release. This regional variation in the neuronal distribution of A(2A) receptors reinforces the care required to extrapolate our knowledge from striatal A(2A) receptors to other brain preparations.
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Affiliation(s)
- N Rebola
- Center for Neurosciences of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, Portugal
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Chou JL, Huang CL, Lai HL, Hung AC, Chien CL, Kao YY, Chern Y. Regulation of type VI adenylyl cyclase by Snapin, a SNAP25-binding protein. J Biol Chem 2004; 279:46271-9. [PMID: 15319443 DOI: 10.1074/jbc.m407206200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In the present study, we used the N terminus (amino acids 1 approximately 160) of type VI adenylyl cyclase (ACVI) as bait to screen a mouse brain cDNA library and identified Snapin as a novel ACVI-interacting molecule. Snapin is a binding protein of SNAP25, a component of the SNARE complex. Co-immunoprecipitation analyses confirmed the interaction between Snapin and full-length ACVI. Mutational analysis revealed that the interaction domains of ACVI and Snapin were located within amino acids 1 approximately 86 of ACVI and 33-51 of Snapin, respectively. Co-localization of ACVI and Snapin was observed in primary hippocampal neurons. Moreover, expression of Snapin specifically eliminated protein kinase C (PKC)-mediated suppression of ACVI, but not that of cAMP-dependent protein kinase (PKA) or calcium. Mutation of the potential PKC and PKA phosphorylation sites of Snapin did not affect the ability of Snapin to reverse the PKC inhibitory effect on ACVI. Phosphorylation of Snapin by PKC or PKA therefore might not be crucial for Snapin action on ACVI. In contrast, Snapin(Delta33-51), which harbors an internal deletion of amino acids 33-51 did not affect PKC-mediated inhibition of ACVI, supporting that amino acids 33-51 of Snapin comprises the ACVI-interacting region. Consistently, Snapin exerted no effect on PKC-mediated inhibition of an ACVI mutant (ACVI-DeltaA87), which lacked the Snapin-interacting region (amino acids 1-86). Snapin thus reverses its action via direct interaction with the N terminus of ACVI. Collectively, we demonstrate herein that in addition to its association with the SNARE complex, Snapin also functions as a regulator of an important cAMP synthesis enzyme in the brain.
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Affiliation(s)
- Jui-Ling Chou
- Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan
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