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G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Molecular Pharmacology".

Deadline for manuscript submissions: closed (1 March 2020) | Viewed by 58535

Special Issue Editor

Departament de Patologia i Terapèutica Experimental, Facultat de Medicina i Ciències de la Salut, Campus Bellvitge, IDIBELL, Universitat de Barcelona. Av. Feixa Llarga, s/n, 08907 L’Hospitalet de Llobregat, Spain
Interests: G protein-coupled receptors; adenosine receptors; neuropharmacology; neurological diseases; allosteric modulation; receptor-receptor interactions; psychiatric diseases
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Adenosine is a well-known neuromodulator in the brain, and has effects on other tissues like immune or circulatory systems. Its physiological actions are exerted mainly through four different subtypes of G protein-coupled adenosine receptors (i.e., A1R, A2AR, A2BR, and A3R), which are expressed in a large variety of cells throughout the body. Thus, ARs are potential therapeutic targets in a variety of pathophysiological conditions, including cancer, cardiovascular diseases, neurological disorders, and inflammatory and autoimmune diseases.

Consequently, interest in the molecular structure and pharmacology of ARs has increased in recent years. Interestingly, more than 30 crystal structures for human ARs have been reported in the last decade, thus making it the most structurally characterized GPCR. In addition, selective agonists and antagonists for all four AR subtypes have been developed, and its diagnostic and therapeutic utility is being pursued.

Using ARs as a paradigm of purinergic GPCRs, the following Special Issue intends to provide the reader with a flavor of the structural and pharmacological recent developments of ARs. Thus, the submissions of papers describing new molecular, physiological, and pharmacological aspects of ARs are welcome. In addition, manuscripts describing new AR-based chemical tools or approaches for the study of the adenosine function, prospective analysis for the therapeutic future of ARs ligands, and reviews will be also taken into consideration. Finally, authors are encouraged to propose topics that will be evaluated accordingly. Overall, we hope that this timely focused Issue summarizing our current knowledge on adenosine receptors will be of interest to a wide range of readers of the journal.

Prof. Dr. Francisco Ciruela
Guest Editor

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Keywords

  • molecular mechanism
  • adenosine receptor ligands
  • therapeutics
  • G protein-coupled receptors
  • agonist
  • signal transduction
  • antagonist
  • receptor–receptor interactions
  • medicinal chemistry
  • purinergic pharmacology.

Published Papers (15 papers)

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Editorial

Jump to: Research, Review

4 pages, 185 KiB  
Editorial
Special Issue: G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond
by Francisco Ciruela
Int. J. Mol. Sci. 2020, 21(6), 1997; https://doi.org/10.3390/ijms21061997 - 15 Mar 2020
Cited by 1 | Viewed by 1621
Abstract
Adenosine is a purine nucleoside present in all human cells where it plays many different physiological roles: From being a building block for nucleic acids to a key constituent of the biological energy currency ATP [...] Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)

Research

Jump to: Editorial, Review

14 pages, 1539 KiB  
Communication
Development of a Radiofluorinated Adenosine A2B Receptor Antagonist as Potential Ligand for PET Imaging
by Marcel Lindemann, Rareş-Petru Moldovan, Sonja Hinz, Winnie Deuther-Conrad, Daniel Gündel, Sladjana Dukic-Stefanovic, Magali Toussaint, Rodrigo Teodoro, Cathleen Juhl, Jörg Steinbach, Peter Brust, Christa E. Müller and Barbara Wenzel
Int. J. Mol. Sci. 2020, 21(9), 3197; https://doi.org/10.3390/ijms21093197 - 30 Apr 2020
Cited by 3 | Viewed by 2529
Abstract
The adenosine A2B receptor has been proposed as a novel therapeutic target in cancer, as its expression is drastically elevated in several tumors and cancer cells. Noninvasive molecular imaging via positron emission tomography (PET) would allow the in vivo quantification of this [...] Read more.
The adenosine A2B receptor has been proposed as a novel therapeutic target in cancer, as its expression is drastically elevated in several tumors and cancer cells. Noninvasive molecular imaging via positron emission tomography (PET) would allow the in vivo quantification of this receptor in pathological processes and most likely enable the identification and clinical monitoring of respective cancer therapies. On the basis of a bicyclic pyridopyrimidine-2,4-dione core structure, the new adenosine A2B receptor ligand 9 was synthesized, containing a 2-fluoropyridine moiety suitable for labeling with the short-lived PET radionuclide fluorine-18. Compound 9 showed a high binding affinity for the human A2B receptor (Ki(A2B) = 2.51 nM), along with high selectivities versus the A1, A2A, and A3 receptor subtypes. Therefore, it was radiofluorinated via nucleophilic aromatic substitution of the corresponding nitro precursor using [18F]F-/K2.2.2./K2CO3 in DMSO at 120 °C. Metabolic studies of [18F]9 in mice revealed about 60% of radiotracer intact in plasma at 30 minutes p.i. A preliminary PET study in healthy mice showed an overall biodistribution of [18F]9, corresponding to the known ubiquitous but low expression of the A2B receptor. Consequently, [18F]9 represents a novel PET radiotracer with high affinity and selectivity toward the adenosine A2B receptor and a suitable in vivo profile. Subsequent studies are envisaged to investigate the applicability of [18F]9 to detect alterations in the receptor density in certain cancer-related disease models. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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14 pages, 2671 KiB  
Article
PDRN, a Bioactive Natural Compound, Ameliorates Imiquimod-Induced Psoriasis through NF-κB Pathway Inhibition and Wnt/β-Catenin Signaling Modulation
by Natasha Irrera, Alessandra Bitto, Mario Vaccaro, Federica Mannino, Violetta Squadrito, Giovanni Pallio, Vincenzo Arcoraci, Letteria Minutoli, Antonio Ieni, Maria Lentini, Domenica Altavilla and Francesco Squadrito
Int. J. Mol. Sci. 2020, 21(4), 1215; https://doi.org/10.3390/ijms21041215 - 12 Feb 2020
Cited by 19 | Viewed by 4333
Abstract
Nuclear factor-κB (NF-κB) plays a central role in psoriasis and canonical Wnt/β-catenin pathway blunts the immune-mediated inflammatory cascade in psoriasis. Adenosine A2A receptor activation blocks NF-κB and boosts the Wnt/β-catenin signaling. PDRN (Polydeoxyribonucleotide) is a biologic agonist of the A2A receptor and its [...] Read more.
Nuclear factor-κB (NF-κB) plays a central role in psoriasis and canonical Wnt/β-catenin pathway blunts the immune-mediated inflammatory cascade in psoriasis. Adenosine A2A receptor activation blocks NF-κB and boosts the Wnt/β-catenin signaling. PDRN (Polydeoxyribonucleotide) is a biologic agonist of the A2A receptor and its effects were studied in an experimental model of psoriasis. Psoriasis-like lesions were induced by a daily application of imiquimod (IMQ) on the shaved back skin of mice for 7 days. Animals were randomly assigned to the following groups: Sham psoriasis challenged with Vaseline; IMQ animals challenged with imiquimod; and IMQ animals treated with PDRN (8 mg/kg/ip). An additional arm of IMQ animals was treated with PDRN plus istradefylline (KW6002; 25 mg/kg/ip) as an A2A antagonist. PDRN restored a normal skin architecture, whereas istradefylline abrogated PDRN positive effects, thus pointing out the mechanistic role of the A2A receptor. PDRN decreased pro-inflammatory cytokines, prompted Wnt signaling, reduced IL-2 and increased IL-10. PDRN also reverted the LPS repressed Wnt-1/β-catenin in human keratinocytes and these effects were abolished by ZM241385, an A2A receptor antagonist. Finally, PDRN reduced CD3+ cells in superficial psoriatic dermis. PDRN anti-psoriasis potential may be linked to a “dual mode” of action: NF-κB inhibition and Wnt/β-catenin stimulation. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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16 pages, 1734 KiB  
Article
Adenosine Suppresses Cholangiocarcinoma Cell Growth and Invasion in Equilibrative Nucleoside Transporters-Dependent Pathway
by Kornkamon Lertsuwan, Supathra Phoaubon, Nathapol Tasnawijitwong and Jomnarong Lertsuwan
Int. J. Mol. Sci. 2020, 21(3), 814; https://doi.org/10.3390/ijms21030814 - 27 Jan 2020
Cited by 6 | Viewed by 3527
Abstract
Cholangiocarcinoma (CCA) is a lethal disease with increasing incidence worldwide. Previous study showed that CCA was sensitive to adenosine. Thereby, molecular mechanisms of CCA inhibition by adenosine were examined in this study. Our results showed that adenosine inhibited CCA cells via an uptake [...] Read more.
Cholangiocarcinoma (CCA) is a lethal disease with increasing incidence worldwide. Previous study showed that CCA was sensitive to adenosine. Thereby, molecular mechanisms of CCA inhibition by adenosine were examined in this study. Our results showed that adenosine inhibited CCA cells via an uptake of adenosine through equilibrative nucleoside transporters (ENTs), instead of activation of adenosine receptors. The inhibition of ENTs by NBTI caused the inhibitory effect of adenosine to subside, while adenosine receptor antagonists, caffeine and CGS-15943, failed to do so. Intracellular adenosine level was increased after adenosine treatment. Also, a conversion of adenosine to AMP by adenosine kinase is required in this inhibition. On the other hand, inosine, which is a metabolic product of adenosine has very little inhibitory effect on CCA cells. This indicates that a conversion of adenosine to inosine may reduce adenosine inhibitory effect. Furthermore, there was no specific correlation between level of proinflammatory proteins and CCA responses to adenosine. A metabolic stable analog of adenosine, 2Cl-adenosine, exerted higher inhibition on CCA cell growth. The disturbance in intracellular AMP level also led to an activation of 5′ AMP-activated protein kinase (AMPK). Accordingly, we proposed a novel adenosine-mediated cancer cell growth and invasion suppression via a receptor-independent mechanism in CCA. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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14 pages, 719 KiB  
Article
Accuracy and Precision of the Receptorial Responsiveness Method (RRM) in the Quantification of A1 Adenosine Receptor Agonists
by Adrienn Monika Szabo, Gabor Viczjan, Tamas Erdei, Ildiko Simon, Rita Kiss, Andras Jozsef Szentmiklosi, Bela Juhasz, Csaba Papp, Judit Zsuga, Akos Pinter, Zoltan Szilvassy and Rudolf Gesztelyi
Int. J. Mol. Sci. 2019, 20(24), 6264; https://doi.org/10.3390/ijms20246264 - 12 Dec 2019
Cited by 2 | Viewed by 2136
Abstract
The receptorial responsiveness method (RRM) is a procedure that is based on a simple nonlinear regression while using a model with two variables (X, Y) and (at least) one parameter to be determined (cx). The model of RRM describes the co-action [...] Read more.
The receptorial responsiveness method (RRM) is a procedure that is based on a simple nonlinear regression while using a model with two variables (X, Y) and (at least) one parameter to be determined (cx). The model of RRM describes the co-action of two agonists that consume the same response capacity (due to the use of the same postreceptorial signaling in a biological system). While using RRM, uniquely, an acute increase in the concentration of an agonist (near the receptors) can be quantified (as cx), via evaluating E/c curves that were constructed with the same or another agonist in the same system. As this measurement is sensitive to the implementation of the curve fitting, the goal of the present study was to test RRM by combining different ways and setting options, namely: individual vs. global fitting, ordinary vs. robust fitting, and three weighting options (no weighting vs. weighting by 1/Y2 vs. weighting by 1/SD2). During the testing, RRM was used to estimate the known concentrations of stable synthetic A1 adenosine receptor agonists in isolated, paced guinea pig left atria. The estimates were then compared to the known agonist concentrations (to assess the accuracy of RRM); furthermore, the 95% confidence limits of the best-fit values were also considered (to evaluate the precision of RRM). It was found that, although the global fitting offered the most convenient way to perform RRM, the best estimates were provided by the individual fitting without any weighting, almost irrespective of the fact whether ordinary or robust fitting was chosen. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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14 pages, 1695 KiB  
Article
A2AR Transmembrane 2 Peptide Administration Disrupts the A2AR-A2AR Homoreceptor but Not the A2AR-D2R Heteroreceptor Complex: Lack of Actions on Rodent Cocaine Self-Administration
by Dasiel O. Borroto-Escuela, Karolina Wydra, Wilber Romero-Fernandez, Zilong Zhou, Malgorzata Frankowska, Malgorzata Filip and Kjell Fuxe
Int. J. Mol. Sci. 2019, 20(23), 6100; https://doi.org/10.3390/ijms20236100 - 03 Dec 2019
Cited by 6 | Viewed by 2794
Abstract
It was previously demonstrated that rat adenosine A2AR transmembrane V peptide administration into the nucleus accumbens enhances cocaine self-administration through disruption of the A2AR-dopamine (D2R) heteroreceptor complex of this region. Unlike human A2AR transmembrane 4 (TM4) and 5 (TM5), A2AR TM2 did not [...] Read more.
It was previously demonstrated that rat adenosine A2AR transmembrane V peptide administration into the nucleus accumbens enhances cocaine self-administration through disruption of the A2AR-dopamine (D2R) heteroreceptor complex of this region. Unlike human A2AR transmembrane 4 (TM4) and 5 (TM5), A2AR TM2 did not interfere with the formation of the A2AR-D2R heteroreceptor complex in cellular models using BRET1 assay. A2AR TM2 was proposed to be part of the of the receptor interface of the A2AR homomer instead and was therefore tested in the current article for effects on rat cocaine self-administration using rat A2AR synthetic TM2 peptide bilaterally injected into the nucleus accumbens. The injected A2AR TM2 peptide failed to significantly counteract the inhibitory action of the A2AR agonist CGS 21680 (0.1 mg/Kg) on cocaine self-administration. In line with these results, the microinjected A2AR TM2 peptide did not reduce the number of proximity ligation assay blobs identifying A2AR-D2R heteroreceptor complexes in the nucleus accumbens. In contrast, the A2AR TM2 peptide significantly reduced the number of A2AR-A2AR homoreceptor complexes in the nucleus accumbens. As to effects on the receptor–receptor interactions in the A2AR-D2R heteroreceptor complexes, the A2AR TM2 peptide did not alter the significant increase in the D2R Ki, high values produced by the A2AR agonist CGS 21680 ex vivo in the ventral striatum. The results indicate that the accumbal A2AR-A2AR homomeric complexes are not involved in mediating the A2AR agonist-induced inhibition of cocaine self-administration. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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16 pages, 5591 KiB  
Article
Expression of Adenosine Receptors in Rodent Pancreas
by Mikio Hayashi
Int. J. Mol. Sci. 2019, 20(21), 5329; https://doi.org/10.3390/ijms20215329 - 25 Oct 2019
Cited by 10 | Viewed by 2988
Abstract
Adenosine regulates exocrine and endocrine secretions in the pancreas. Adenosine is considered to play a role in acini-to-duct signaling in the exocrine pancreas. To identify the molecular basis of functional adenosine receptors in the exocrine pancreas, immunohistochemical analysis was performed in the rat, [...] Read more.
Adenosine regulates exocrine and endocrine secretions in the pancreas. Adenosine is considered to play a role in acini-to-duct signaling in the exocrine pancreas. To identify the molecular basis of functional adenosine receptors in the exocrine pancreas, immunohistochemical analysis was performed in the rat, mouse, and guinea pig pancreas, and the secretory rate and concentration of HCO3 in pancreatic juice from the rat pancreas were measured. The A2A adenosine receptor colocalized with ezrin, an A-kinase anchoring protein, in the luminal membrane of duct cells in the mouse and guinea pig pancreas. However, a strong signal ascribed to A2B adenosine receptors was detected in insulin-positive β cells in islets of Langerhans. The A2A adenosine receptor agonist 4-[2-[[6-Amino-9-(N-ethyl-β-D-ribofuranuronamidosyl)-9H-purin-2-yl]amino]ethyl]benzenepropanoic acid (CGS 21680) stimulated HCO3-rich fluid secretion from the rat pancreas. These results indicate that A2A adenosine receptors may be, at least in part, involved in the exocrine secretion of pancreatic duct cells via acini-to-duct signaling. The adenosine receptors may be a potential therapeutic target for cancer as well as exocrine dysfunctions of the pancreas. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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22 pages, 2850 KiB  
Article
Carbamazepine Attenuates Astroglial L-Glutamate Release Induced by Pro-Inflammatory Cytokines via Chronically Activation of Adenosine A2A Receptor
by Motohiro Okada, Kouji Fukuyama, Takashi Shiroyama and Yuto Ueda
Int. J. Mol. Sci. 2019, 20(15), 3727; https://doi.org/10.3390/ijms20153727 - 30 Jul 2019
Cited by 21 | Viewed by 3754
Abstract
Carbamazepine (CBZ) binds adenosine receptors, but detailed effects of CBZ on astroglial transmission associated with adenosine receptor still need to be clarified. To clarify adenosinergic action of CBZ on astroglial transmission, primary cultured astrocytes were acutely or chronically treated with CBZ, proinflammatory cytokines [...] Read more.
Carbamazepine (CBZ) binds adenosine receptors, but detailed effects of CBZ on astroglial transmission associated with adenosine receptor still need to be clarified. To clarify adenosinergic action of CBZ on astroglial transmission, primary cultured astrocytes were acutely or chronically treated with CBZ, proinflammatory cytokines (interferon γ (IFNγ) and tumor necrosis factor α (TNFα)), and adenosine A2A receptor (A2AR) agonist (CGS21680). IFNγ and TNFα increased basal, adenophostin-A (AdA)-evoked, and 2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid (AMPA)-evoked astroglial L-glutamate releases. In physiological condition, CGS21680 increased basal astroglial L-glutamate release but glutamate transporter inhibition prevented this CGS21680 action. CBZ did not affect basal release, whereas glutamate transporter inhibition generated CBZ-induced glutamate release. Furthermore, AdA-evoked and AMPA-evoked releases were inhibited by CBZ but were unaffected by CGS21680. Contrary to physiological condition, chronic administrations of IFNγ and TNFα enhanced basal, AdA-, and AMPA-evoked releases, whereas IFNγ and TNFα decreased and increased CGS21680-evoked releases via modulation A2AR expression. Both chronic administration of CGS21680 and CBZ suppressed astroglial L-glutamate release responses induced by chronic cytokine exposer. Especifically, chronic administration of CBZ and CGS21680 prevented the reduction and elevation of A2AR expression by respective IFNγ and TNFα. These findings suggest that A2AR agonistic effects of CBZ contribute to chronic prevention of pathomechanisms developments of several neuropsychiatric disorders associated with proinflammatory cytokines. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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12 pages, 1480 KiB  
Article
Bioluminescence Resonance Energy Transfer Based G Protein-Activation Assay to Probe Duration of Antagonism at the Histamine H3 Receptor
by Tamara A. M. Mocking, Maurice C. M. L. Buzink, Rob Leurs and Henry F. Vischer
Int. J. Mol. Sci. 2019, 20(15), 3724; https://doi.org/10.3390/ijms20153724 - 30 Jul 2019
Cited by 6 | Viewed by 3895
Abstract
Duration of receptor antagonism, measured as the recovery of agonist responsiveness, is gaining attention as a method to evaluate the ‘effective’ target-residence for antagonists. These functional assays might be a good alternative for kinetic binding assays in competition with radiolabeled or fluorescent ligands, [...] Read more.
Duration of receptor antagonism, measured as the recovery of agonist responsiveness, is gaining attention as a method to evaluate the ‘effective’ target-residence for antagonists. These functional assays might be a good alternative for kinetic binding assays in competition with radiolabeled or fluorescent ligands, as they are performed on intact cells and better reflect consequences of dynamic cellular processes on duration of receptor antagonism. Here, we used a bioluminescence resonance energy transfer (BRET)-based assay that monitors heterotrimeric G protein activation via scavenging of released Venus-Gβ1γ2 by NanoLuc (Nluc)-tagged membrane-associated-C-terminal fragment of G protein-coupled receptor kinase 3 (masGRK3ct-Nluc) as a tool to probe duration of G protein-coupled receptor (GPCR) antagonism. The Gαi-coupled histamine H3 receptor (H3R) was used in this study as prolonged antagonism is associated with adverse events (e.g., insomnia) and consequently, short-residence time ligands might be preferred. Due to its fast and prolonged response, this assay can be used to determine the duration of functional antagonism by measuring the recovery of agonist responsiveness upon washout of pre-bound antagonist, and to assess antagonist re-equilibration time via Schild-plot analysis. Re-equilibration of pre-incubated antagonist with agonist and receptor could be followed in time to monitor the transition from insurmountable to surmountable antagonism. The BRET-based G protein activation assay can detect differences in the recovery of H3R responsiveness and re-equilibration of pre-bound antagonists between the tested H3R antagonists. Fast dissociation kinetics were observed for marketed drug pitolisant (Wakix®) in this assay, which suggests that short residence time might be beneficial for therapeutic targeting of the H3R. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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11 pages, 1903 KiB  
Article
Revealing Adenosine A2A-Dopamine D2 Receptor Heteromers in Parkinson’s Disease Post-Mortem Brain through a New AlphaScreen-Based Assay
by Víctor Fernández-Dueñas, Maricel Gómez-Soler, Marta Valle-León, Masahiko Watanabe, Isidre Ferrer and Francisco Ciruela
Int. J. Mol. Sci. 2019, 20(14), 3600; https://doi.org/10.3390/ijms20143600 - 23 Jul 2019
Cited by 32 | Viewed by 5358
Abstract
Background: Several biophysical techniques have been successfully implemented to detect G protein-coupled receptors (GPCRs) heteromerization. Although these approaches have made it possible to ascertain the presence of GPCR heteromers in animal models of disease, no success has been accomplished in pathological human [...] Read more.
Background: Several biophysical techniques have been successfully implemented to detect G protein-coupled receptors (GPCRs) heteromerization. Although these approaches have made it possible to ascertain the presence of GPCR heteromers in animal models of disease, no success has been accomplished in pathological human post-mortem brains. The AlphaScreen technology has been consistently used to quantify small analyte accumulation or depletion, bimolecular interactions, and post-translational modifications. The high signal-to-background, dynamic range and sensitivity exhibited by this technology support that it may be suitable to detect GPCR heteromers even under non-optimal conditions. Methods: Here, we describe the development of a new AlphaScreen assay to detect GPCR oligomers in human post-mortem brain. Results: Adenosine A2A-dopamine D2 receptor (A2AR/D2R) heteromer formation was monitored in caudate from healthy and Parkinson’s disease (PD) subjects. The approach was first validated using striatal membranes from wild type and A2AR deficient mice. Secondly, we took advantage of the 6-hydroxydopamine hemiparkinsonian rat model to validate previous results. In addition, finally, A2AR/D2R heteromer formation was assessed in caudate membranes from human post-mortem brains. Importantly, our preliminary results revealed an increase in A2AR/D2R heteromer formation in PD brains. Conclusions: The new AlphaScreen assay allowed assessing GPCR heteromers in human post-mortem brains with high sensitivity. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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12 pages, 1318 KiB  
Communication
A2A-D2 Heteromers on Striatal Astrocytes: Biochemical and Biophysical Evidence
by Simone Pelassa, Diego Guidolin, Arianna Venturini, Monica Averna, Giulia Frumento, Letizia Campanini, Rosa Bernardi, Pietro Cortelli, Giovanna Calandra Buonaura, Guido Maura, Luigi F. Agnati, Chiara Cervetto and Manuela Marcoli
Int. J. Mol. Sci. 2019, 20(10), 2457; https://doi.org/10.3390/ijms20102457 - 17 May 2019
Cited by 25 | Viewed by 3142
Abstract
Our previous findings indicate that A2A and D2 receptors are co-expressed on adult rat striatal astrocytes and on the astrocyte processes, and that A2A-D2 receptor–receptor interaction can control the release of glutamate from the processes. Functional evidence suggests that the receptor–receptor interaction was [...] Read more.
Our previous findings indicate that A2A and D2 receptors are co-expressed on adult rat striatal astrocytes and on the astrocyte processes, and that A2A-D2 receptor–receptor interaction can control the release of glutamate from the processes. Functional evidence suggests that the receptor–receptor interaction was based on heteromerization of native A2A and D2 receptors at the plasma membrane of striatal astrocyte processes. We here provide biochemical and biophysical evidence confirming that receptor–receptor interaction between A2A and D2 receptors at the astrocyte plasma membrane is based on A2A-D2 heteromerization. To our knowledge, this is the first direct demonstration of the ability of native A2A and D2 receptors to heteromerize on glial cells. As striatal astrocytes are recognized to be involved in Parkinson’s pathophysiology, the findings that adenosine A2A and dopamine D2 receptors can form A2A-D2 heteromers on the astrocytes in the striatum (and that these heteromers can play roles in the control of the striatal glutamatergic transmission) may shed light on the molecular mechanisms involved in the pathogenesis of the disease. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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Review

Jump to: Editorial, Research

13 pages, 2026 KiB  
Review
Adenosine Receptor Profiling Reveals an Association between the Presence of Spare Receptors and Cardiovascular Disorders
by Emmanuel Fenouillet, Giovanna Mottola, Nathalie Kipson, Franck Paganelli, Régis Guieu and Jean Ruf
Int. J. Mol. Sci. 2019, 20(23), 5964; https://doi.org/10.3390/ijms20235964 - 27 Nov 2019
Cited by 20 | Viewed by 5933
Abstract
Adenosine and its receptors exert a potent control on the cardiovascular system. This review aims to present emerging experimental evidence supporting the existence and implication in cardiovascular disorders of specific adenosinergic pharmacological profiles, conforming to the concept of “receptor reserve”, also known as [...] Read more.
Adenosine and its receptors exert a potent control on the cardiovascular system. This review aims to present emerging experimental evidence supporting the existence and implication in cardiovascular disorders of specific adenosinergic pharmacological profiles, conforming to the concept of “receptor reserve”, also known as “spare receptors”. This kind of receptors allow agonists to achieve their maximal effect without occupying all of the relevant cell receptors. In the cardiovascular system, spare adenosine receptors appear to compensate for a low extracellular adenosine level and/or a low adenosine receptor number, such as in coronary artery disease or some kinds of neurocardiogenic syncopes. In both cases, the presence of spare receptors appears to be an attempt to overcome a weak interaction between adenosine and its receptors. The identification of adenosine spare receptors in cardiovascular disorders may be helpful for diagnostic purposes. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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18 pages, 4135 KiB  
Review
Blood Platelet Adenosine Receptors as Potential Targets for Anti-Platelet Therapy
by Nina Wolska and Marcin Rozalski
Int. J. Mol. Sci. 2019, 20(21), 5475; https://doi.org/10.3390/ijms20215475 - 03 Nov 2019
Cited by 27 | Viewed by 5697
Abstract
Adenosine receptors are a subfamily of highly-conserved G-protein coupled receptors. They are found in the membranes of various human cells and play many physiological functions. Blood platelets express two (A2A and A2B) of the four known adenosine receptor subtypes (A [...] Read more.
Adenosine receptors are a subfamily of highly-conserved G-protein coupled receptors. They are found in the membranes of various human cells and play many physiological functions. Blood platelets express two (A2A and A2B) of the four known adenosine receptor subtypes (A1, A2A, A2B, and A3). Agonization of these receptors results in an enhanced intracellular cAMP and the inhibition of platelet activation and aggregation. Therefore, adenosine receptors A2A and A2B could be targets for anti-platelet therapy, especially under circumstances when classic therapy based on antagonizing the purinergic receptor P2Y12 is insufficient or problematic. Apart from adenosine, there is a group of synthetic, selective, longer-lasting agonists of A2A and A2B receptors reported in the literature. This group includes agonists with good selectivity for A2A or A2B receptors, as well as non-selective compounds that activate more than one type of adenosine receptor. Chemically, most A2A and A2B adenosine receptor agonists are adenosine analogues, with either adenine or ribose substituted by single or multiple foreign substituents. However, a group of non-adenosine derivative agonists has also been described. This review aims to systematically describe known agonists of A2A and A2B receptors and review the available literature data on their effects on platelet function. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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18 pages, 694 KiB  
Review
A2B Adenosine Receptor and Cancer
by Zhan-Guo Gao and Kenneth A. Jacobson
Int. J. Mol. Sci. 2019, 20(20), 5139; https://doi.org/10.3390/ijms20205139 - 17 Oct 2019
Cited by 57 | Viewed by 6349
Abstract
There are four subtypes of adenosine receptors (ARs), named A1, A2A, A2B and A3, all of which are G protein-coupled receptors (GPCRs). Locally produced adenosine is a suppressant in anti-tumor immune surveillance. The A2BAR, [...] Read more.
There are four subtypes of adenosine receptors (ARs), named A1, A2A, A2B and A3, all of which are G protein-coupled receptors (GPCRs). Locally produced adenosine is a suppressant in anti-tumor immune surveillance. The A2BAR, coupled to both Gαs and Gαi G proteins, is one of the several GPCRs that are expressed in a significantly higher level in certain cancer tissues, in comparison to adjacent normal tissues. There is growing evidence that the A2BAR plays an important role in tumor cell proliferation, angiogenesis, metastasis, and immune suppression. Thus, A2BAR antagonists are novel, potentially attractive anticancer agents. Several antagonists targeting A2BAR are currently in clinical trials for various types of cancers. In this review, we first describe the signaling, agonists, and antagonists of the A2BAR. We further discuss the role of the A2BAR in the progression of various cancers, and the rationale of using A2BAR antagonists in cancer therapy. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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35 pages, 758 KiB  
Review
The Biological and Clinical Relevance of G Protein-Coupled Receptors to the Outcomes of Hematopoietic Stem Cell Transplantation: A Systematized Review
by Hadrien Golay, Simona Jurkovic Mlakar, Vid Mlakar, Tiago Nava and Marc Ansari
Int. J. Mol. Sci. 2019, 20(16), 3889; https://doi.org/10.3390/ijms20163889 - 09 Aug 2019
Cited by 3 | Viewed by 3829
Abstract
Hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for several malignant and non-malignant diseases at the cost of serious treatment-related toxicities (TRTs). Recent research on extending the benefits of HSCT to more patients and indications has focused on limiting TRTs and [...] Read more.
Hematopoietic stem cell transplantation (HSCT) remains the only curative treatment for several malignant and non-malignant diseases at the cost of serious treatment-related toxicities (TRTs). Recent research on extending the benefits of HSCT to more patients and indications has focused on limiting TRTs and improving immunological effects following proper mobilization and engraftment. Increasing numbers of studies report associations between HSCT outcomes and the expression or the manipulation of G protein-coupled receptors (GPCRs). This large family of cell surface receptors is involved in various human diseases. With ever-better knowledge of their crystal structures and signaling dynamics, GPCRs are already the targets for one third of the current therapeutic arsenal. The present paper assesses the current status of animal and human research on GPCRs in the context of selected HSCT outcomes via a systematized survey and analysis of the literature. Full article
(This article belongs to the Special Issue G Protein-Coupled Adenosine Receptors: Molecular Aspects and Beyond)
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