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Saecker L, Häberlein H, Franken S. Investigation of adenosine A1 receptor-mediated β-arrestin 2 recruitment using a split-luciferase assay. Front Pharmacol 2023; 14:1172551. [PMID: 37324481 PMCID: PMC10268005 DOI: 10.3389/fphar.2023.1172551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 05/15/2023] [Indexed: 06/17/2023] Open
Abstract
Background: Adenosine A1 receptor (A1AR) plays a prominent role in neurological and cardiac diseases and inflammatory processes. Its endogenous ligand adenosine is known to be one of the key players in the sleep-wake cycle. Like other G protein-coupled receptors (GPCRs), stimulation of A1AR leads to the recruitment of arrestins in addition to the activation of G proteins. So far, little is known about the role of these proteins in signal transduction and regulation of A1AR compared to the activation of G proteins. In this work, we characterized a live cell assay for A1AR-mediated β-arrestin 2 recruitment. We have applied this assay to a set of different compounds that interact with this receptor. Methods: Based on NanoBit® technology, a protein complementation assay was developed in which the A1AR is coupled to the large part of the nanoluciferase (LgBiT), whereas its small part (SmBiT) is fused to the N-terminus of β-arrestin 2. Stimulation of A1AR results in the recruitment of β-arrestin 2 and subsequent complementation of a functional nanoluciferase. For comparison, corresponding data on the effect of receptor stimulation on intracellular cAMP levels were collected for some data sets using the GloSensor™ assay. Results: The assay gives highly reproducible results with a very good signal-to-noise ratio. Capadenoson, in contrast to adenosine, CPA, or NECA, shows only partial agonism in this assay with respect to the recruitment of β-arrestin 2, whereas it shows full agonism in the case of the inhibitory effect of A1AR on cAMP production. By using a GRK2 inhibitor, it becomes clear that the recruitment is at least partially dependent on the phosphorylation of the receptor by this kinase. Interestingly, this was also the first time that we demonstrate the A1AR-mediated recruitment of β-arrestin 2 by stimulation with a valerian extract. Conclusion: The presented assay is a useful tool for the quantitative study of A1AR-mediated β-arrestin 2 recruitment. It allows data collection for stimulatory, inhibitory, and modulatory substances and is also suitable for more complex substance mixtures such as valerian extract.
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Affiliation(s)
| | | | - Sebastian Franken
- Institute of Biochemistry and Molecular Biology, Medical Faculty, University of Bonn, Bonn, Germany
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2
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Calcium signaling cascades differentially regulate PGF 2α-induced myometrial contractions in water buffaloes (Bubalus bubalis). Naunyn Schmiedebergs Arch Pharmacol 2021; 394:1651-1664. [PMID: 33884445 DOI: 10.1007/s00210-021-02084-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 03/30/2021] [Indexed: 10/21/2022]
Abstract
This study unravels the differential involvement of calcium signaling pathway(s) in PGF2α-induced contractions in myometrium of nonpregnant (NP) and pregnant buffaloes. Compared to the myometrium of pregnant animals, myometrium of NP buffaloes was more sensitive to PGF2α as manifested by changes in mean integral tension (MIT) and tonicity. In the presence of nifedipine, myometrial contraction to PGF2α was significantly attenuated in both NP and pregnant uteri; however, mibefradil and NNC 55-0396 produced inhibitory effects only in uterus of pregnant animals, thus suggesting the role of extracellular Ca2+ influx through nifedipine-sensitive L-type Ca2+-channels both in NP and pregnant, but T-type Ca2+ channels seem to play a role only during pregnancy. Entry of extracellular Ca2+ is triggered by enhanced functional involvement of Pyr3-sensitive TRPC3 channels and Rho-kinase pathways as evidenced by a significant rightward shift of the concentration-response curve of PGF2α in the presence of Pyr3 and Y-27632 in NP myometrium. But significant down-expressions of TRPC3 and Rho-A proteins during pregnancy apparently facilitate uterine quiescence. In the presence of Ca2+-free solution and cyclopiazonic acid (SERCA blocker), feeble contraction to PGF2α was observed in both NP and pregnant myometrium which suggests minor role of intracellular source of Ca2+ in mediating PGF2α-induced contractions in these tissues.
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3
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Spanoghe J, Larsen LE, Craey E, Manzella S, Van Dycke A, Boon P, Raedt R. The Signaling Pathways Involved in the Anticonvulsive Effects of the Adenosine A 1 Receptor. Int J Mol Sci 2020; 22:ijms22010320. [PMID: 33396826 PMCID: PMC7794785 DOI: 10.3390/ijms22010320] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/22/2020] [Accepted: 12/27/2020] [Indexed: 12/20/2022] Open
Abstract
Adenosine acts as an endogenous anticonvulsant and seizure terminator in the brain. Many of its anticonvulsive effects are mediated through the activation of the adenosine A1 receptor, a G protein-coupled receptor with a wide array of targets. Activating A1 receptors is an effective approach to suppress seizures. This review gives an overview of the neuronal targets of the adenosine A1 receptor focusing in particular on signaling pathways resulting in neuronal inhibition. These include direct interactions of G protein subunits, the adenyl cyclase pathway and the phospholipase C pathway, which all mediate neuronal hyperpolarization and suppression of synaptic transmission. Additionally, the contribution of the guanyl cyclase and mitogen-activated protein kinase cascades to the seizure-suppressing effects of A1 receptor activation are discussed. This review ends with the cautionary note that chronic activation of the A1 receptor might have detrimental effects, which will need to be avoided when pursuing A1 receptor-based epilepsy therapies.
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Affiliation(s)
- Jeroen Spanoghe
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Lars E. Larsen
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Erine Craey
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Simona Manzella
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Annelies Van Dycke
- Department of Neurology, General Hospital Sint-Jan Bruges, 8000 Bruges, Belgium;
| | - Paul Boon
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
| | - Robrecht Raedt
- 4Brain, Department of Head and Skin, Ghent University, 9000 Ghent, Belgium; (J.S.); (L.E.L.); (E.C.); (S.M.); (P.B.)
- Correspondence:
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4
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Shahrestanaki MK, Arasi FP, Aghaei M. Adenosine protects pancreatic beta cells against apoptosis induced by endoplasmic reticulum stress. J Cell Biochem 2019; 120:7759-7770. [PMID: 30417434 DOI: 10.1002/jcb.28050] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2018] [Accepted: 10/22/2018] [Indexed: 01/24/2023]
Abstract
Chronic exposure to high glucose induces endoplasmic reticulum (ER) stress in pancreatic beta cells (PBCs). The previous evidence showed that adenosine modulate PBCs viability and insulin secretion. The aim of this study was to evaluate possible involvement of adenosine in protection of MIN6 β-cells from Tunicamycin (Tu)-induced ER stress. MIN6 cells were cotreated with Tu and different concentrations of adenosine. Cell viability, proliferation, and apoptosis were evaluated using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT), 5-bromo-2'-deoxyuridine (Brdu), and colony formation assays. Caspase-12 activity was assayed using the fluorometric method. Thioflavin T (ThT) staining was used for the evaluation of protein aggregation. Insulin secretion was evaluated using specific an ELISA kit. Ca2+ mobilization assayed using Fura2/AM probe. BIP, CHOP, XBP-1, and XBP-1s expression in both messenger RNA (mRNA) and protein levels were evaluated using the reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis, respectively. Bcl-2, p-eIF2α/eIF2α, and GADD34 levels also determined with Western blot analysis. Adenosine protected MIN6 cells against Tu-induced ER stress in a dose-dependent manner and increased their proliferation. Decreased caspase-12 activity and upregulated Bcl-2 protein may explain antiapoptotic effects of adenosine. ThT staining indicated an attenuated aggregation of misfolded proteins. Adenosine effectively increased insulin secretion in Tu-treated cells. BIP, CHOP, XBP1, and sXBP1 expression were decreased significantly in cotreated cells, indicating alleviation of ER stress. However, adenosine potentiated the expression of GADD34 and decreased p-eIF2α/eIF2α ratio. Adenosine increased cytosolic Ca 2+ levels, which may promote adenosine triphosphate (ATP) synthesis in mitochondria, helping ER to preserve protein hemostasis. Taken together, adenosine upregulated Bcl-2 and GADD34 to protect PBCs against Tu-induced apoptosis and increase Insulin secretion.
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Affiliation(s)
- Mohammad Keyvanloo Shahrestanaki
- Department of Clinical Biochemistry, School of Pharmacy & Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Fatemeh Panahi Arasi
- Department of Clinical Biochemistry, School of Pharmacy & Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
| | - Mahmoud Aghaei
- Department of Clinical Biochemistry, School of Pharmacy & Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran
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5
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Pacini ESA, Sanders-Silveira S, O Godinho R. The Extracellular cAMP-Adenosine Pathway in Airway Smooth Muscle. J Pharmacol Exp Ther 2018; 366:75-83. [PMID: 29685885 DOI: 10.1124/jpet.118.247734] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/16/2018] [Indexed: 11/22/2022] Open
Abstract
In the respiratory tract, intracellular cAMP has a key role in the smooth muscle relaxation induced by the β2-adrenoceptor/Gs protein/adenylyl cyclase axis. In other tissues, cAMP also works as an extracellular messenger, after its efflux and interstitial conversion to adenosine by ectoenzymes. The aim of this study was to identify cAMP efflux and the "extracellular cAMP-adenosine pathway" in the airway smooth muscle. First, we tested the ability of β2-adrenoceptor agonists formoterol or fenoterol to increase the extracellular cAMP in isolated tracheal rings from adult male Wistar rats. The effects of adenosine, cAMP, 8-Br-cAMP, fenoterol, or formoterol were also evaluated in the isometric contraction of control or carbachol (CCh) precontracted tracheas, normalized as the percentage of CCh-induced response. Fenoterol and formoterol induced 70%-80% relaxation and increased extracellular cAMP levels by up to 280%-450%. Although exogenous cAMP or adenosine evoked phasic contractions, the membrane-permeable cAMP analog 8-Br-cAMP induced relaxation of CCh-precontracted tracheas. The simultaneous inhibition of adenosine degradation/uptake with EHNA [erythro-9-(2-hydroxy-3-nonyl) adenine hydrochloride] plus uridine increased by 3-fold the maximum cAMP-induced contraction, whereas it was significantly reduced by AMPCP [adenosine 5'-(α,β-methylene)diphosphate; an ecto-5'-nucleotidase inhibitor], and by adenosine receptor antagonists CGS-15943 (nonselective) or DPCPX (8-cyclopentyl-1,3-dipropylxanthine) (A1 selective). Finally, CGS-15943 shifted to the left the concentration-relaxation curve for fenoterol. In conclusion, our results show that airway smooth muscle expresses the extracellular cAMP-adenosine pathway associated with contracting effects mediated by A1 receptors. The cAMP efflux triggered by fenoterol/formoterol indicates that the extracellular cAMP-adenosine pathway may play a role in balancing the relaxant effects of β2-adrenoceptor agonists in airways, which may impact their bronchodilation effects.
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Affiliation(s)
- Enio S A Pacini
- Division of Cellular Pharmacology, Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, Brazil
| | - Sarah Sanders-Silveira
- Division of Cellular Pharmacology, Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, Brazil
| | - Rosely O Godinho
- Division of Cellular Pharmacology, Department of Pharmacology, Escola Paulista de Medicina, Universidade Federal de São Paulo (EPM/UNIFESP), São Paulo, Brazil
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6
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Sharma A, Nakade UP, Jaitley P, Sharma V, Choudhury S, Garg SK. WITHDRAWN: Differential involvement of L- and T-type Ca 2+ channels, store-operated calcium channel (TRPC) and Rho-kinase signaling pathway(s) in PGF 2α-induced contractions in myometrium of non-pregnant and pregnant buffaloes (Bubalus bubalis). Prostaglandins Other Lipid Mediat 2017:S1098-8823(17)30021-7. [PMID: 28916261 DOI: 10.1016/j.prostaglandins.2017.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 09/05/2017] [Accepted: 09/06/2017] [Indexed: 11/30/2022]
Abstract
This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.
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Affiliation(s)
- Abhishek Sharma
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Udayraj P Nakade
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Pooja Jaitley
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Vipin Sharma
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Soumen Choudhury
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India
| | - Satish Kumar Garg
- Experimental Pharmacology Laboratory, Department of Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura 281001, India.
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7
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A1 Adenosine Receptor Activation Modulates Central Nervous System Development and Repair. Mol Neurobiol 2016; 54:8128-8139. [DOI: 10.1007/s12035-016-0292-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/08/2016] [Indexed: 01/22/2023]
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8
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Bicket A, Mehrabi P, Naydenova Z, Wong V, Donaldson L, Stagljar I, Coe IR. Novel regulation of equlibrative nucleoside transporter 1 (ENT1) by receptor-stimulated Ca2+-dependent calmodulin binding. Am J Physiol Cell Physiol 2016; 310:C808-20. [PMID: 27009875 DOI: 10.1152/ajpcell.00243.2015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 03/09/2016] [Indexed: 01/25/2023]
Abstract
Equilibrative nucleoside transporters (ENTs) facilitate the flux of nucleosides, such as adenosine, and nucleoside analog (NA) drugs across cell membranes. A correlation between adenosine flux and calcium-dependent signaling has been previously reported; however, the mechanistic basis of these observations is not known. Here we report the identification of the calcium signaling transducer calmodulin (CaM) as an ENT1-interacting protein, via a conserved classic 1-5-10 motif in ENT1. Calcium-dependent human ENT1-CaM protein interactions were confirmed in human cell lines (HEK293, RT4, U-87 MG) using biochemical assays (HEK293) and the functional assays (HEK293, RT4), which confirmed modified nucleoside uptake that occurred in the presence of pharmacological manipulations of calcium levels and CaM function. Nucleoside and NA drug uptake was significantly decreased (∼12% and ∼39%, respectively) by chelating calcium (EGTA, 50 μM; BAPTA-AM, 25 μM), whereas increasing intracellular calcium (thapsigargin, 1.5 μM) led to increased nucleoside uptake (∼26%). Activation of N-methyl-d-aspartate (NMDA) receptors (in U-87 MG) by glutamate (1 mM) and glycine (100 μM) significantly increased nucleoside uptake (∼38%) except in the presence of the NMDA receptor antagonist, MK-801 (50 μM), or CaM antagonist, W7 (50 μM). These data support the existence of a previously unidentified novel receptor-dependent regulatory mechanism, whereby intracellular calcium modulates nucleoside and NA drug uptake via CaM-dependent interaction of ENT1. These findings suggest that ENT1 is regulated via receptor-dependent calcium-linked pathways resulting in an alteration of purine flux, which may modulate purinergic signaling and influence NA drug efficacy.
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Affiliation(s)
- Alex Bicket
- Department of Biology, York University, Toronto, Canada
| | - Pedram Mehrabi
- Department of Biology, York University, Toronto, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Canada
| | - Zlatina Naydenova
- Department of Chemistry and Biology, Ryerson University, Toronto, Canada
| | - Victoria Wong
- Donnelly Centre, Department of Biochemistry and Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | | | - Igor Stagljar
- Donnelly Centre, Department of Biochemistry and Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Imogen R Coe
- Department of Biology, York University, Toronto, Canada; Department of Chemistry and Biology, Ryerson University, Toronto, Canada;
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9
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Erb L, Weisman GA. Coupling of P2Y receptors to G proteins and other signaling pathways. ACTA ACUST UNITED AC 2012; 1:789-803. [PMID: 25774333 DOI: 10.1002/wmts.62] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
P2Y receptors are G protein-coupled receptors (GPCRs) that are activated by adenine and uridine nucleotides and nucleotide sugars. There are eight subtypes of P2Y receptors (P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, P2Y12, P2Y13, and P2Y14), which activate intracellular signaling cascades to regulate a variety of cellular processes, including proliferation, differentiation, phagocytosis, secretion, nociception, cell adhesion, and cell migration. These signaling cascades operate mainly by the sequential activation or deactivation of heterotrimeric and monomeric G proteins, phospholipases, adenylyl and guanylyl cyclases, protein kinases, and phosphodiesterases. In addition, there are numerous ion channels, cell adhesion molecules, and receptor tyrosine kinases that are modulated by P2Y receptors and operate to transmit an extracellular signal to an intracellular response.
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Affiliation(s)
- Laurie Erb
- Department of Biochemistry, Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Gary A Weisman
- Department of Biochemistry, Life Sciences Center, University of Missouri-Columbia, Columbia, MO 65211, USA
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10
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Abstract
This review summarizes the brain mechanisms controlling sleep and wakefulness. Wakefulness promoting systems cause low-voltage, fast activity in the electroencephalogram (EEG). Multiple interacting neurotransmitter systems in the brain stem, hypothalamus, and basal forebrain converge onto common effector systems in the thalamus and cortex. Sleep results from the inhibition of wake-promoting systems by homeostatic sleep factors such as adenosine and nitric oxide and GABAergic neurons in the preoptic area of the hypothalamus, resulting in large-amplitude, slow EEG oscillations. Local, activity-dependent factors modulate the amplitude and frequency of cortical slow oscillations. Non-rapid-eye-movement (NREM) sleep results in conservation of brain energy and facilitates memory consolidation through the modulation of synaptic weights. Rapid-eye-movement (REM) sleep results from the interaction of brain stem cholinergic, aminergic, and GABAergic neurons which control the activity of glutamatergic reticular formation neurons leading to REM sleep phenomena such as muscle atonia, REMs, dreaming, and cortical activation. Strong activation of limbic regions during REM sleep suggests a role in regulation of emotion. Genetic studies suggest that brain mechanisms controlling waking and NREM sleep are strongly conserved throughout evolution, underscoring their enormous importance for brain function. Sleep disruption interferes with the normal restorative functions of NREM and REM sleep, resulting in disruptions of breathing and cardiovascular function, changes in emotional reactivity, and cognitive impairments in attention, memory, and decision making.
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Affiliation(s)
- Ritchie E Brown
- Laboratory of Neuroscience, VA Boston Healthcare System and Harvard Medical School, Brockton, Massachusetts 02301, USA
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11
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Gao X, Patzak A, Sendeski M, Scheffer PG, Teerlink T, Sällström J, Fredholm BB, Persson AEG, Carlström M. Adenosine A1-receptor deficiency diminishes afferent arteriolar and blood pressure responses during nitric oxide inhibition and angiotensin II treatment. Am J Physiol Regul Integr Comp Physiol 2011; 301:R1669-81. [DOI: 10.1152/ajpregu.00268.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Adenosine mediates tubuloglomerular feedback responses via activation of A1-receptors on the renal afferent arteriole. Increased preglomerular reactivity, due to reduced nitric oxide (NO) production or increased levels of ANG II and reactive oxygen species (ROS), has been linked to hypertension. Using A1-receptor knockout (A1−/−) and wild-type (A1+/+) mice we investigated the hypothesis that A1-receptors modulate arteriolar and blood pressure responses during NO synthase (NOS) inhibition or ANG II treatment. Blood pressure and renal afferent arteriolar responses were measured in nontreated mice and in mice with prolonged Nω-nitro-l-arginine methyl ester hydrochloride (l-NAME) or ANG II treatment. The hypertensive responses to l-NAME and ANG II were clearly attenuated in A1−/− mice. Arteriolar contractions to l-NAME (10−4 mol/l; 15 min) and cumulative ANG II application (10−12 to 10−6 mol/l) were lower in A1−/− mice. Simultaneous treatment with tempol (10−4 mol/l; 15 min) attenuated arteriolar responses in A1+/+ but not in A1−/− mice, suggesting differences in ROS formation. Chronic treatment with l-NAME or ANG II did not alter arteriolar responses in A1−/− mice, but enhanced maximal contractions in A1+/+ mice. In addition, chronic treatments were associated with higher plasma levels of dimethylarginines (asymmetrical and symmetrical) and oxidative stress marker malondialdehyde in A1+/+ mice, and gene expression analysis showed reduced upregulation of NOS-isoforms and greater upregulation of NADPH oxidases. In conclusion, adenosine A1-receptors enhance preglomerular responses during NO inhibition and ANG II treatment. Interruption of A1-receptor signaling blunts l-NAME and ANG II-induced hypertension and oxidative stress and is linked to reduced responsiveness of afferent arterioles.
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Affiliation(s)
- Xiang Gao
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Andreas Patzak
- Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Germany
| | - Mauricio Sendeski
- Institute of Vegetative Physiology, Charité-Universitätsmedizin Berlin, Germany
| | - Peter G. Scheffer
- Department of Clinical Chemistry, VU University Medical Centre, Amsterdam, Netherlands; and
| | - Tom Teerlink
- Department of Clinical Chemistry, VU University Medical Centre, Amsterdam, Netherlands; and
| | - Johan Sällström
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Bertil B. Fredholm
- Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden
| | | | - Mattias Carlström
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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12
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Lauro C, Cipriani R, Catalano M, Trettel F, Chece G, Brusadin V, Antonilli L, van Rooijen N, Eusebi F, Fredholm BB, Limatola C. Adenosine A1 receptors and microglial cells mediate CX3CL1-induced protection of hippocampal neurons against Glu-induced death. Neuropsychopharmacology 2010; 35:1550-9. [PMID: 20200508 PMCID: PMC3055460 DOI: 10.1038/npp.2010.26] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Fractalkine/CX3CL1 is a neuron-associated chemokine, which modulates microglia-induced neurotoxicity activating the specific and unique receptor CX3CR1. CX3CL1/CX3CR1 interaction modulates the release of cytokines from microglia, reducing the level of tumor necrosis factor-alpha, interleukin-1-beta, and nitric oxide and induces the production of neurotrophic substances, both in vivo and in vitro. We have recently shown that blocking adenosine A(1) receptors (A(1)R) with the specific antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) abolishes CX3CL1-mediated rescue of neuronal excitotoxic death and that CX3CL1 induces the release of adenosine from microglia. In this study, we show that the presence of extracellular adenosine is mandatory for the neurotrophic effect of CX3CL1 as reducing adenosine levels in hippocampal cultures, by adenosine deaminase treatment, strongly impairs CX3CL1-mediated neuroprotection. Furthermore, we confirm the predominant role of microglia in mediating the neuronal effects of CX3CL1, because the selective depletion of microglia from hippocampal cultures treated with clodronate-filled liposomes causes the complete loss of effect of CX3CL1. We also show that hippocampal neurons obtained from A(1)R(-/-) mice are not protected by CX3CL1 whereas A(2A)R(-/-) neurons are. The requirement of functional A(1)R for neuroprotection is not unique for CX3CL1 as A(1)R(-/-) hippocampal neurons are not rescued from Glu-induced cell death by other neurotrophins such as brain-derived neurotrophic factor and erythropoietin, which are fully active on wt neurons.
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Affiliation(s)
- Clotilde Lauro
- Istituto Pasteur, Fondazione Cenci Bolognetti, Rome, Italy,Centro di Eccellenza BEMM, Rome, Italy,Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy
| | - Raffaela Cipriani
- Istituto Pasteur, Fondazione Cenci Bolognetti, Rome, Italy,Centro di Eccellenza BEMM, Rome, Italy,Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy
| | - Myriam Catalano
- Istituto Pasteur, Fondazione Cenci Bolognetti, Rome, Italy,Centro di Eccellenza BEMM, Rome, Italy,Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy
| | - Flavia Trettel
- Istituto Pasteur, Fondazione Cenci Bolognetti, Rome, Italy,Centro di Eccellenza BEMM, Rome, Italy,Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy
| | - Giuseppina Chece
- Istituto Pasteur, Fondazione Cenci Bolognetti, Rome, Italy,Centro di Eccellenza BEMM, Rome, Italy,Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy
| | - Valentina Brusadin
- Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy
| | - Letizia Antonilli
- Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy
| | - Nico van Rooijen
- Department of Molecular Cell Biology, Free University Medical Center, Amsterdam, The Netherlands
| | - Fabrizio Eusebi
- Istituto Pasteur, Fondazione Cenci Bolognetti, Rome, Italy,Centro di Eccellenza BEMM, Rome, Italy,Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy,IRCSS NeuroMed, Pozzilli, Italy
| | - Bertil B Fredholm
- Department of Physiology and Pharmacology, Karolinska Institutet, Stockholm, Sweden
| | - Cristina Limatola
- Istituto Pasteur, Fondazione Cenci Bolognetti, Rome, Italy,Centro di Eccellenza BEMM, Rome, Italy,Dipartimento di Fisiologia e Farmacologia, Università Sapienza, Rome, Italy,IRCSS NeuroMed, Pozzilli, Italy,Dipartimento di Fisiologia e Farmacologia, Università di Roma Sapienza, Piazzale Aldo Moro, 5, Rome 00185, Italy. Tel: +39 06 49690243; Fax: +39 06 49910851; E-mail:
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Carlsson SK, Edman MC, Delbro D, Gierow JP. Adenosine A2 receptor presence and synergy with cholinergic stimulation in rabbit lacrimal gland. Curr Eye Res 2010; 35:466-74. [PMID: 20465439 DOI: 10.3109/02713681003602667] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Secretion from the lacrimal gland is an important part of the well-being of the eye, and a central part in the search for treatment of dry eye syndrome. Adenosine has stimulatory effects on the lacrimal gland, and can potentiate the effect of the cholinergic agonist carbachol (Cch). The aim of the present study is to investigate the presence of the adenosine A(2) receptor subtypes A(2A) and A(2B) in the rabbit lacrimal gland, and to characterize their role in regulated acinar cell secretion. METHODS Expression of the receptors was investigated using reverse transcriptase-PCR (RT-PCR) and immunofluorescence, and secretion effects were studied using a secretion assay in isolated lacrimal gland acinar cells. RESULTS Presence of both receptors was detected by RT-PCR and immunofluorescence. The secretion assay revealed a minor effect of stimulation of the A(2) receptors, and a strong synergistic effect with the cholinergic agonist Cch. The synergistic effect was significantly reduced by the A(2B) antagonist PSB 1115, but not by the A(2A) antagonist SCH 58261, indicating that A(2B) is the receptor responsible for this potentiation. CONCLUSIONS The study reveals the presence of the adenosine A(2) receptor subtypes as well as a role for them in lacrimal gland secretion, and especially in the synergy with purinergic and cholinergic stimulation.
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Association analysis of adenosine A1 receptor gene (ADORA1) polymorphisms with schizophrenia in a Japanese population. Psychiatr Genet 2010; 19:328-35. [PMID: 19820430 DOI: 10.1097/ypg.0b013e3283328e26] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The human adenosine A1 receptor gene (ADORA1) localizes to chromosome 1q32 is 76.8 kbp in length and contains six exons. ADORA1 is ubiquitously expressed in the central nervous system and clinical and pharmacological evidence suggest the involvement of adenosine neurotransmission in the pathogenesis of schizophrenia. Therefore, we investigated the contribution of genetic variations of ADORA1 to the pathophysiological mechanisms of Japanese schizophrenia patients. METHODS We performed genetic analysis of 29 polymorphic markers in 200 schizophrenic patients and 210 healthy controls from the Kyushu region of Japan. In statistical analysis, we performed the univariate analysis with genotypes and allele frequencies, linkage disequilibrium (LD) analyses, multivariate analysis, haplotype analysis, and sliding window haplotype analysis. RESULTS In univariate analysis, no statistical difference was shown, after Bonferroni correction. By LD analysis, however, we could not find any LD blocks. In haplotype analysis, a total of 359 haplotypes were estimated. In multivariate analysis, we found three statistically different markers. In sliding window haplotype analysis, there were four statistically different haplotypes. CONCLUSION This is the first study describing the involvement of ADORA1 polymorphisms in the pathophysiological mechanisms of schizophrenia in a Japanese population. These results corroborate our previous pharmacological and neurochemical studies in the rat that have suggested an association between ADORA1 neurotransmission and the schizophrenic effects of the N-methyl-D-aspartate receptor antagonist phencyclidine. Thus, ADORA1 polymorphisms may represent good candidate markers for schizophrenia research and ADORA1 may be involved in the pathophysiological mechanisms of schizophrenia in Japanese populations.
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15
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Kempson SA, Edwards JM, Osborn A, Sturek M. Acute inhibition of the betaine transporter by ATP and adenosine in renal MDCK cells. Am J Physiol Renal Physiol 2008; 295:F108-17. [PMID: 18448594 DOI: 10.1152/ajprenal.00108.2008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Extracellular ATP interacts with purinergic P2 receptors to regulate a range of physiological responses, including downregulation of transport activity in the nephron. ATP is released from cells by mechanical stimuli such as cell volume changes, and autocrine signaling by extracellular ATP could occur in renal medullary cells during diuresis. This was tested in Madin-Darby canine kidney (MDCK) cells, a model used frequently to study P1 and P2 receptor activity. ATP was released within 1 min after transfer from 500 to 300 mosmol/kgH2O medium. A 30-min incubation with ATP produced dose-dependent inhibition (0.01-0.10 mM) of the renal betaine/GABA transporter (BGT1) with little effect on other osmolyte transporters. Inhibition was reproduced by specific agonists for P2X (alpha,beta-methylene-ATP) and P2Y (UTP) receptors. Adenosine, the final product of ATP hydrolysis, also inhibited BGT1 but not taurine transport. Inhibition by ATP and adenosine was blocked by pertussis toxin and A73122, suggesting involvement of inhibitory G protein and PLC in postreceptor signaling. Both ATP and adenosine (0.1 mM) produced rapid increases in intracellular Ca2+, due to the mobilization of intracellular Ca2+ stores and Ca2+ influx. Blocking these Ca2+ increases with BAPTA-AM also blocked the action of ATP and adenosine on BGT1 transport. Finally, immunohistochemical studies indicated that inhibition of BGT1 transport may be due to endocytic accumulation of BGT1 proteins from the plasma membrane. We conclude that ATP and adenosine, through stimulation of PLC and intracellular Ca2+, may be rapidly acting regulators of BGT1 transport especially in response to a fall in extracellular osmolarity.
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Affiliation(s)
- Stephen A Kempson
- Department of Cellular and Intergrative Physiology, Indiana University School of Medicine, Indianapolis, IN, USA.
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Abbracchio MP, Burnstock G, Boeynaems JM, Barnard EA, Boyer JL, Kennedy C, Knight GE, Fumagalli M, Gachet C, Jacobson KA, Weisman GA. International Union of Pharmacology LVIII: update on the P2Y G protein-coupled nucleotide receptors: from molecular mechanisms and pathophysiology to therapy. Pharmacol Rev 2006; 58:281-341. [PMID: 16968944 PMCID: PMC3471216 DOI: 10.1124/pr.58.3.3] [Citation(s) in RCA: 987] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
There have been many advances in our knowledge about different aspects of P2Y receptor signaling since the last review published by our International Union of Pharmacology subcommittee. More receptor subtypes have been cloned and characterized and most orphan receptors de-orphanized, so that it is now possible to provide a basis for a future subdivision of P2Y receptor subtypes. More is known about the functional elements of the P2Y receptor molecules and the signaling pathways involved, including interactions with ion channels. There have been substantial developments in the design of selective agonists and antagonists to some of the P2Y receptor subtypes. There are new findings about the mechanisms underlying nucleotide release and ectoenzymatic nucleotide breakdown. Interactions between P2Y receptors and receptors to other signaling molecules have been explored as well as P2Y-mediated control of gene transcription. The distribution and roles of P2Y receptor subtypes in many different cell types are better understood and P2Y receptor-related compounds are being explored for therapeutic purposes. These and other advances are discussed in the present review.
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Affiliation(s)
- Maria P Abbracchio
- Department of Pharmacological Sciences, University of Milan, Milan, Italy
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Erb L, Liao Z, Seye CI, Weisman GA. P2 receptors: intracellular signaling. Pflugers Arch 2006; 452:552-62. [PMID: 16586093 DOI: 10.1007/s00424-006-0069-2] [Citation(s) in RCA: 193] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2006] [Accepted: 03/06/2006] [Indexed: 10/24/2022]
Abstract
P2 receptors for extracellular nucleotides are divided into two categories: the ion channel receptors (P2X) and the G-protein-coupled receptors (P2Y). For the P2X receptors, signal transduction appears to be relatively simple. Upon activation by extracellular ATP, a channel comprised of P2X receptor subunits opens and allows cations to move across the plasma membrane, resulting in changes in the electrical potential of the cell that, in turn, propagates a signal. This regulated flux of ions across the plasma membrane has important signaling functions, especially in impulse propagation in the nervous system and in muscle contractility. In addition, P2X receptor activation causes the accumulation of calcium ions in the cytoplasm, which is responsible for activating numerous signaling molecules. For the P2Y receptors, signal transduction is more complex. Intracellular signaling cascades are the main routes of communication between G-protein-coupled receptors and regulatory targets within the cell. These signaling cascades operate mainly by the sequential activation or deactivation of heterotrimeric and monomeric G proteins, phospholipases, protein kinases, adenylyl and guanylyl cyclases, and phosphodiesterases that regulate many cellular processes, including proliferation, differentiation, apoptosis, metabolism, secretion, and cell migration. In addition, there are numerous ion channels, cell adhesion molecules and receptor tyrosine kinases that are modulated by P2Y receptors and operate to transmit an extracellular signal to an intracellular response. These intracellular signaling pathways and their regulation by P2 receptors are discussed in this review.
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Affiliation(s)
- Laurie Erb
- Department of Biochemistry, University of Missouri-Columbia, Life Sciences Center, 1201 Rollins Rd., Columbia, MO 65211, USA.
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Finkelberg A, Busch L, Reina S, Sterin-Borda L, Borda E. Endogenous signalling system involved in parotid gland adenosine A(1) receptor-amylase release. Acta Physiol (Oxf) 2006; 186:29-36. [PMID: 16497177 DOI: 10.1111/j.1748-1716.2005.01508.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM In this study, we have determined signalling pathways involved in adenosine A(1) receptor (A(1) receptor)-dependent stimulation of amylase release in rat parotid gland. METHODS Amylase release, binding and cyclic adenosine monophosphate (cAMP) assays, inositol phosphates (IPs) production and nitric oxide synthase (NOS) activity in the presence of cyclopentyl-1,3-dipropylxanthine (CPA) alone or in the presence of different inhibitory drugs were performed. RESULTS The binding parameters of specific A(1) antagonist [(3)H]-cyclopentyl 1,3-dipropilxanthine ([(3)H]-DPCPX) in parotid gland membranes show a population of high affinity sites with K(d) (nm) 0.53 +/- 0.06 and B(max) (fmol mg(-1) protein) 122.6 +/- 10.2. CPA stimulation of A(1) receptor exerts an increase in amylase release, IPs accumulation, cAMP production and NOS activity. All these A(1) agonist effects were blocked by the A(1) receptor antagonist DPCPX. Inhibitors of phospholipase C (PLC), calcium/calmodulin (CaM), protein kinase C (PKC), and adenylate cyclase, but not NOS, activities attenuated the CPA stimulatory effect on amylase release. The effect of CPA on amylase release significantly correlated with its action either on cAMP or on IPs accumulation. CONCLUSION These results suggest that CPA activation of parotid gland A(1) receptor induces a stimulatory effect on amylase release associated with increased production of cAMP and IPs accumulation. The mechanism appears to occur secondarily to stimulation of phosphoinositide turnover via PLC activation. This, in turn, triggers cascade reactions involving CaM and PKC. The CPA stimulation of NOS does not appear to participate in amylase release.
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Affiliation(s)
- A Finkelberg
- Physiology Unit, School of Dentistry, Córdoba National University, Buenos Aires, Argentina
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León D, Albasanz JL, Ruíz MA, Iglesias I, Martín M. Effect of chronic gestational treatment with caffeine or theophylline on Group I metabotropic glutamate receptors in maternal and fetal brain. J Neurochem 2005; 94:440-51. [PMID: 15998294 DOI: 10.1111/j.1471-4159.2005.03211.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Pregnant rats were treated throughout the gestational period with either caffeine or theophylline, and its effect on the metabotropic glutamate receptor (mGluRs) signal transduction pathway was studied in both maternal and fetal brain. In maternal brain, radioligand binding assays showed that chronic treatment with methylxanthines caused a significant decrease in the total number of mGluRs. This decrease was accompanied by an increase in receptor affinity. Immunodetection showed that mGluR1a and phospholipase C beta1 (PLCbeta1) were significantly decreased in response to chronic methylxanthine treatment, whereas alphaG(q/11) was not affected. A loss was also detected of PLC stimulation mediated by (S)-3,5-dihydroxyphenylglycine (DHPG), a selective Group I mGluR agonist, suggesting desensitization of the mGluR/PLC pathway. In fetal brain, a loss in total mGluRs was observed in fetuses from mothers treated with caffeine or theophylline, without variation in receptor affinity. A decrease in mGluR1a, alphaG(q/11) and PLCbeta1 levels was also observed in response to treatment. However, changes detected in this immature tissue were not associated with variations in PLC activity. These results suggest that chronic caffeine or theophylline treatment down-regulates several mGluR/PLC transduction pathway components in both maternal and fetal brain, causing a loss of receptor responsiveness only in maternal brain.
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Affiliation(s)
- D León
- 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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Yoshioka K, Nakata H. ATP- and adenosine-mediated signaling in the central nervous system: purinergic receptor complex: generating adenine nucleotide-sensitive adenosine receptors. J Pharmacol Sci 2004; 94:88-94. [PMID: 14978342 DOI: 10.1254/jphs.94.88] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Adenosine A(1) receptors (A(1)R) are able to form a heteromeric complex with P2Y(1) receptors (P2Y(1)R) that generates A(1)R with P2Y(1)R-like agonistic pharmacology. A potent P2Y(1)R agonist, adenosine 5'-O-(2-thiotriphosphate), binds the A(1)R binding pocket of the A(1)R/P2Y(1)R complex and inhibits adenylyl cyclase activity via G(i/o) protein. These mechanisms might be used to fine-tune purinergic inhibition locally at sites where there is a particular oligomerization structure between purinergic receptors and explain the undefined purinergic functions by adenosine and adenine nucleotides.
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Affiliation(s)
- Kazuaki Yoshioka
- Department of Molecular Cell Signaling, Tokyo Metropolitan Institute for Neuroscience, Tokyo, Japan
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Cordeaux Y, IJzerman AP, Hill SJ. Coupling of the human A1 adenosine receptor to different heterotrimeric G proteins: evidence for agonist-specific G protein activation. Br J Pharmacol 2004; 143:705-14. [PMID: 15302686 PMCID: PMC1575922 DOI: 10.1038/sj.bjp.0705925] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
The present study investigates the effect of varying ligand structure on the ability of agonists to activate guanine nucleotide-binding proteins of the Gi, Gs and Gq families via the A(1) adenosine receptor. In CHO cells expressing this receptor, inhibition or potentiation of forskolin-stimulated cAMP accumulation was used as an end point to measure the activation of Gi and, in Pertussis toxin (PTX)-treated cells, Gs, respectively. Stimulation of inositol phosphate accumulation in PTX-treated cells was used as an index of Gq activation. CPA (N(6)-cyclopentyladenosine), NECA (5'-N-ethyl-carboxyamidoadenosine) and eight analogues of these ligands presented a range of guanine nucleotide-binding protein (G-protein)-activating profiles. Some ligands could only activate Gi (e.g. 2'deoxyCPA), some primarily Gi and Gs (and only weakly Gq) (e.g. 3'deoxyCPA), highlighting the importance of the ribose hydroxyls in agonist activation of multiple G proteins. CHA (N(6)-cyclohexyladenosine) activated Gi, Gs and Gq, but was more efficacious than CPA in activating Gs. The NECA analogues 5'-N-cyclopropyl-carboxamidoadenosine, 5'-N-cyclobutyl-carboxamidoadenosine and 5'-N-cyclopentyl-carboxamidoadenosine (CPeCA) also activated all three G proteins, although their ability to activate Gs and Gq (relative to CPA) was reduced with increasing substituent size, such that CPeCA produced only a small stimulation (at 100 microM) at Gq, but was a full agonist, relative to CPA, at Gi and Gs. This study suggests that the A(1) adenosine receptor can adopt agonist-specific conformations, arising from small changes in ligand structure, which lead to the differential activation of Gi, Gs and Gq.
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Affiliation(s)
- Yolande Cordeaux
- Institute of Cell Signalling, Medical School, University of Nottingham, Nottingham NG7 2UH
| | - Adriaan P IJzerman
- Leiden/Amsterdam Centre for Drug research, Division of Medicinal Chemistry, Leiden, Netherlands
| | - Stephen J Hill
- Institute of Cell Signalling, Medical School, University of Nottingham, Nottingham NG7 2UH
- Author for correspondence:
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Basheer R, Strecker RE, Thakkar MM, McCarley RW. Adenosine and sleep–wake regulation. Prog Neurobiol 2004; 73:379-96. [PMID: 15313333 DOI: 10.1016/j.pneurobio.2004.06.004] [Citation(s) in RCA: 358] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Accepted: 06/28/2004] [Indexed: 10/26/2022]
Abstract
This review addresses three principal questions about adenosine and sleep-wake regulation: (1) Is adenosine an endogenous sleep factor? (2) Are there specific brain regions/neuroanatomical targets and receptor subtypes through which adenosine mediates sleepiness? (3) What are the molecular mechanisms by which adenosine may mediate the long-term effects of sleep loss? Data suggest that adenosine is indeed an important endogenous, homeostatic sleep factor, likely mediating the sleepiness that follows prolonged wakefulness. The cholinergic basal forebrain is reviewed in detail as an essential area for mediating the sleep-inducing effects of adenosine by inhibition of wake-promoting neurons via the A1 receptor. The A2A receptor in the subarachnoid space below the rostral forebrain may play a role in the prostaglandin D2-mediated somnogenic effects of adenosine. Recent evidence indicates that a cascade of signal transduction induced by basal forebrain adenosine A1 receptor activation in cholinergic neurons leads to increased transcription of the A1 receptor; this may play a role in mediating the longer-term effects of sleep deprivation, often called sleep debt.
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Affiliation(s)
- Radhika Basheer
- Neuroscience Laboratory, Department of Psychiatry, Harvard Medical School and Boston VA Healthcare System, Brockton, MA 02301, USA
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Alloisio S, Cugnoli C, Ferroni S, Nobile M. Differential modulation of ATP-induced calcium signalling by A1 and A2 adenosine receptors in cultured cortical astrocytes. Br J Pharmacol 2004; 141:935-42. [PMID: 14993103 PMCID: PMC1574277 DOI: 10.1038/sj.bjp.0705707] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2003] [Revised: 01/14/2004] [Accepted: 01/20/2004] [Indexed: 11/09/2022] Open
Abstract
1. Despite the accumulating evidence that under various pathological conditions the extracellular elevation of adenine-based nucleotides and nucleosides plays a key role in the control of astroglial reactivity, how these signalling molecules interact in the regulation of astrocyte function is still largely elusive. 2. The action of the nucleoside adenosine in the modulation of the intracellular calcium signalling ([Ca(2+)](i)) elicited by adenosine 5'-triphosphate (ATP)-induced activation of P2 purinoceptors was investigated on neocortical type-1 astrocytes in primary culture by using single-cell microfluorimetry. 3. Astrocyte challenge with ATP (1-10 microm) elicited biphasic [Ca(2+)](i) responses consisting of an initial peak followed by a sustained elevation. The stable adenosine analogue 2-chloroadenosine (2-ClA) potentiated the transient [Ca(2+)](i) rise induced by activation of metabotropic P2Y receptors. Among the various P1 receptor agonists tested, the nonselective agonist 5'-N-ethylcarboxamidoadenosine (NECA) mimicked the 2-ClA action, whereas the selective A1 R(-) N6-(2-phenylisopropyl)-adenosine (R-PIA), the A2A 2-[4-(2-carboxyethyl)phenethylamino]-5'-N-ethylcarboxamidoadenosine (CGS-21680) and A3 1-deoxy-1-(6-[([3-lodophenyl]methyl)-amino]-9H-purin-9-yl)-N-methyl-beta-d-ribofuranuronamide (IB-MECA) agonists were ineffective. 4. Application of R-PIA>NECA>or=2-ClA depressed the [Ca(2+)](i) plateau reversibly. Moreover, in the presence of R-PIA or 2-ClA, the prolonged [Ca(2+)](i) signal was maintained by application of the A1 antagonist 1,3-diethyl-8-phenylxanthine (DPX). Finally, preincubation of the astrocytes with pertussis toxin abrogated the 2-ClA inhibition of the ATP-elicited sustained [Ca(2+)](i) rise without affecting the transient [Ca(2+)](i) potentiation. 5. Taken together, these findings indicate that stimulation of A1 and A2 adenosine receptors mediates a differential modulation of [Ca(2+)](i) signalling elicited by P2 purinoceptors. Since variations in [Ca(2+)](i) dynamics also affect cell proliferation and differentiation, our data suggest that tuning of the extracellular levels of adenosine may be relevant for the control of astrogliosis mediated by adenine nucleotides.
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Affiliation(s)
- Susanna Alloisio
- Institute of Biophysics, CNR, Via De Marini 6, 16149 Genoa, Italy
| | - Carlo Cugnoli
- Institute of Biophysics, CNR, Via De Marini 6, 16149 Genoa, Italy
| | - Stefano Ferroni
- Department of Human and General Physiology, University of Bologna, Via San Donato, 19-2–40127 Bologna, Italy
| | - Mario Nobile
- Institute of Biophysics, CNR, Via De Marini 6, 16149 Genoa, Italy
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Kenakin T. Predicting therapeutic value in the lead optimization phase of drug discovery. Nat Rev Drug Discov 2003; 2:429-38. [PMID: 12776218 DOI: 10.1038/nrd1110] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Recombinant and natural cellular assays for human G-protein-coupled receptors are used to optimize initial lead molecules obtained from screening. Although the activity of these molecules can be assessed on human genotype receptors, there is increasing evidence that cells impose a phenotypic selectivity to molecules in various cellular backgrounds. This opens the possibility of dissimulations between activity seen in lead optimization assays and the intended therapeutic value in humans. This review discusses the mechanisms by which cells can impose phenotypic selectivity on molecules and approaches to reduce this practical problem for drug discovery.
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Affiliation(s)
- Terry Kenakin
- Systems Research, GlaxoSmithKline Research and Development, 5 Moore Drive, Research Triangle Park, North Carolina 27709, USA.
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Nakata H, Yoshioka K, Saitoh O. Hetero-oligomerization between adenosine A1 and P2Y1 receptors in living cells: Formation of ATP-sensitive adenosine receptors. Drug Dev Res 2003. [DOI: 10.1002/ddr.10169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Bergner A, Sanderson MJ. ATP stimulates Ca2+ oscillations and contraction in airway smooth muscle cells of mouse lung slices. Am J Physiol Lung Cell Mol Physiol 2002; 283:L1271-9. [PMID: 12388370 DOI: 10.1152/ajplung.00139.2002] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In airway smooth muscle cells (SMCs) from mouse lung slices, > or =10 microM ATP induced Ca2+ oscillations that were accompanied by airway contraction. After approximately 1 min, the Ca2+ oscillations subsided and the airway relaxed. By contrast, > or =0.5 microM adenosine 5'-O-(3-thiotriphosphate) (nonhydrolyzable) induced Ca2+ oscillations in the SMCs and an associated airway contraction that persisted for >2 min. Adenosine 5'-O-(3-thiotriphosphate)-induced Ca2+ oscillations occurred in the absence of external Ca2+ but were abolished by the phospholipase C inhibitor U-73122 and the inositol 1,4,5-trisphosphate receptor inhibitor xestospongin. Adenosine, AMP, and alpha,beta-methylene ATP had no effect on airway caliber, and the magnitude of the contractile response induced by a variety of nucleotides could be ranked in the following order: ATP = UTP > ADP. These results suggest that the SMC response to ATP is impaired by ATP hydrolysis and mediated via P2Y(2) or P2Y(4) receptors, activating phospholipase C to release Ca2+ via the inositol 1,4,5-trisphosphate receptor. We conclude that ATP can serve as a spasmogen of airway SMCs and that Ca2+ oscillations in SMCs are required to sustain airway contraction.
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Affiliation(s)
- Albrecht Bergner
- Department of Physiology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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Ferroni S, Marchini C, Ogata T, Schubert P. Recovery of deficient cholinergic calcium signaling by adenosine in cultured rat cortical astrocytes. J Neurosci Res 2002; 68:615-21. [PMID: 12111851 DOI: 10.1002/jnr.10248] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The regulation of the cholinergic calcium signaling in astroglial cells is thought to play a crucial role in the pathogenesis of Alzheimer's disease. We investigated the action of the cell modulator adenosine on acetylcholine (Ach)-mediated intracellular calcium ([Ca(2+)](i)) transients in cultured rat cortical astrocytes using the Ca(2+) imaging technique. The stable adenosine analog 2-chloroadenosine (2ClA) potentiated the [Ca(2+)](i) rise induced by activation of muscarinic Ach receptors by shifting approximately 30-fold the half-effective Ach concentration. This 2ClA effect was maintained upon removal of extracellular Ca(2+), indicating that Ach-induced [Ca(2+)](i) elevation was due mainly to Ca(2+) mobilization from intracellular stores. Pharmacological studies demonstrated that the 2ClA action was mediated by A1 receptors. Incubation with pertussis toxin abrogated the 2ClA effect but left unchanged the [Ca(2+)](i) rise produced by Ach alone. The [Ca(2+)](i) response elicited by Ach alone was abolished upon blockade of muscarinic receptor subtypes that stimulate phospholipase C, whereas the [Ca(2+)](i) elevation generated by the combined action of subthreshold Ach and 2ClA was not affected. Collectively, these results suggest that the impaired cholinergic signaling, the cardinal symptom of Alzheimer's disease, can be reinforced at the second messenger level by an alternative intracellular Ca(2+) mobilizing path, which can be brought into play by the concomitant activation of A1 purinoceptors and muscarinic receptors negatively coupled to adenylyl cyclase.
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Affiliation(s)
- Stefano Ferroni
- Department of Human and General Physiology, University of Bologna, Bologna, Italy.
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Senses V, Ozyazgan S, Ince E, Tuncdemir M, Kaya F, Ozturk M, Sultuybek G, Akkan AG. Effect of 5-aminoimidazole-4-carboxamide riboside (AICA-r) on isolated thoracic aorta responses in streptozotocin-diabetic rats. J Basic Clin Physiol Pharmacol 2002; 12:227-48. [PMID: 11762693 DOI: 10.1515/jbcpp.2001.12.3.227] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Diabetes mellitus alters the vascular responsiveness to several vasoconstrictors and vasodilators. 5-amino-4-imidazole-carboxamide riboside (AICA-r), a nucleoside corresponding to AICA-ribotide and an intermediate of the de novo pathway of purine biosynthesis, was recently proposed as a new insulinotropic tool in non-insulin-dependent diabetes mellitus. The aim of the present study was to define whether AICA-r affects altered vascular responsiveness to vasoconstrictors and vasodilators in the thoracic aorta of neonatal streptozotocin (STZ)-diabetic rats. The results of this study indicate that a 1-month treatment with AICA-r significantly increases the body weight in diabetic rats; significantly decreases the blood glucose level of diabetic rats (from 302+/-47 to 135+/-11 mg/dL, p<0.001); does not significantly affect the fast, slow, and total components of responses to noradrenaline in all the experimental groups; reverses the increased Emax values of noradrenaline in diabetic rats to near-control values; reverses the completely abolished responses of acetylcholine (pD2 and percent relaxation) in diabetic rats to control values; and reverses the decreased pD2 values of sodium nitroprussiate in diabetic rats to control values. In conclusion, AICA-r treatment in neonatal STZ-diabetic rats improved increased blood glucose levels, accelerated weight gain, reversed endothelial dysfunction, and normalized vascular responses.
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Affiliation(s)
- V Senses
- Department of Pharmacology, Cerrahpasa Faculty of Medicine, University of Istanbul, Turkey
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29
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Yoshioka K, Saitoh O, Nakata H. Heteromeric association creates a P2Y-like adenosine receptor. Proc Natl Acad Sci U S A 2001; 98:7617-22. [PMID: 11390975 PMCID: PMC34717 DOI: 10.1073/pnas.121587098] [Citation(s) in RCA: 196] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adenosine and its endogenous precursor ATP are main components of the purinergic system that modulates cellular and tissue functions via specific adenosine and ATP receptors (P1 and P2 receptors), respectively. Although adenosine inhibits excitability and ATP functions as an excitatory transmitter in the central nervous system, little is known about the ability of P1 and P2 receptors to form new functional structures such as a heteromer to control the complex purinergic cascade. Here we have shown that G(i/o) protein-coupled A1 adenosine receptor (A1R) and Gq protein-coupled P2Y1 receptor (P2Y1R) coimmunoprecipitate in cotransfected HEK293T cells, suggesting the oligomeric association between distinct G protein-coupled P1 and P2 receptors. A1R and P2Y2 receptor, but not A1R and dopamine D2 receptor, also were found to coimmunoprecipitate in cotransfected cells. A1R agonist and antagonist binding to cell membranes were reduced by coexpression of A1R and P2Y1R, whereas a potent P2Y1R agonist adenosine 5'-O-(2-thiotriphosphate) (ADPbetaS) revealed a significant potency to A1R binding only in the cotransfected cell membranes. Moreover, the A1R/P2Y1R coexpressed cells showed an ADPbetaS-dependent reduction of forskolin-evoked cAMP accumulation that was sensitive to pertussis toxin and A1R antagonist, indicating that ADPbetaS binds A1R and inhibits adenylyl cyclase activity via G(i/o) proteins. Also, a high degree of A1R and P2Y1R colocalization was demonstrated in cotransfected cells by double immunofluorescence experiments with confocal laser microscopy. These results suggest that oligomeric association of A1R with P2Y1R generates A1R with P2Y1R-like agonistic pharmacology and provides a molecular mechanism for an increased diversity of purine signaling.
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MESH Headings
- Adenosine/analogs & derivatives
- Adenosine/pharmacology
- Adenylyl Cyclases/metabolism
- Animals
- Cell Line
- Cell Membrane/physiology
- Cyclic AMP/metabolism
- GTP-Binding Protein alpha Subunits, Gi-Go/chemistry
- GTP-Binding Protein alpha Subunits, Gi-Go/isolation & purification
- GTP-Binding Protein alpha Subunits, Gi-Go/physiology
- Heterotrimeric GTP-Binding Proteins/chemistry
- Heterotrimeric GTP-Binding Proteins/isolation & purification
- Heterotrimeric GTP-Binding Proteins/physiology
- Humans
- Inositol 1,4,5-Trisphosphate/metabolism
- Kinetics
- Macromolecular Substances
- Purinergic P1 Receptor Agonists
- Radioligand Assay
- Rats
- Receptors, Dopamine D2/chemistry
- Receptors, Dopamine D2/isolation & purification
- Receptors, Dopamine D2/physiology
- Receptors, Purinergic P1/isolation & purification
- Receptors, Purinergic P1/physiology
- Receptors, Purinergic P2/chemistry
- Receptors, Purinergic P2/isolation & purification
- Receptors, Purinergic P2/physiology
- Recombinant Proteins/chemistry
- Recombinant Proteins/isolation & purification
- Recombinant Proteins/metabolism
- Transfection
- Tritium
- Xanthines/pharmacokinetics
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Affiliation(s)
- K Yoshioka
- Department of Molecular and Cellular Neurobiology, Tokyo Metropolitan Institute for Neuroscience, Fuchu, Tokyo 183-8526, Japan
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30
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Abstract
Neuronal activity elicits increases in intracellular Ca2+ in astrocytes, which in turn can elevate neuronal Ca2+ and potentiate the efficacy of excitatory synaptic transmission. Therefore, understanding the modulation of astrocyte Ca2+ elevations by neurotransmitters should aid in understanding astrocyte-neuronal interactions. On cultured hippocampal microislands containing only astrocytes, activation of metabotropic glutamate receptors (mGluRs) with the specific agonist 1S,3R-ACPD triggers Ca2+ elevations that are potentiated by adenosine A1 receptor activation. A1 receptor modulation of mGluR-induced Ca2+ elevations is blocked by pertussis toxin and is mimicked by the wasp venom peptide mastoparan, suggesting that potentiation occurs by means of a G(i/o) mechanism. Surprisingly, on microislands containing only astrocytes, A1 receptor antagonism or adenosine degradation suppresses mGluR-triggered Ca2+ elevations, strongly suggesting that astrocytes are a source of physiologically relevant concentrations of adenosine.
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Affiliation(s)
- R J Cormier
- Department of Psychiatry, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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31
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Cordeaux Y, Briddon SJ, Megson AE, McDonnell J, Dickenson JM, Hill SJ. Influence of receptor number on functional responses elicited by agonists acting at the human adenosine A(1) receptor: evidence for signaling pathway-dependent changes in agonist potency and relative intrinsic activity. Mol Pharmacol 2000; 58:1075-84. [PMID: 11040056 DOI: 10.1124/mol.58.5.1075] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of A(1) adenosine receptors leads to the inhibition of cAMP accumulation and the stimulation of inositol phosphate accumulation via pertussis toxin-sensitive G-proteins. In this study we have investigated the signaling of the A(1) adenosine receptor in Chinese hamster ovary (CHO) cells, when expressed at approximately 203 fmol/mg (CHOA1L) and at approximately 3350 fmol/mg (CHOA1H). In CHOA1L cells, the agonists N(6)-cyclopentyladenosine (CPA), (R)-N(6)-(2-phenylisopropyl)adenosine, and 5'-(N-ethylcarboxamido)adenosine (NECA) inhibited cAMP production in a concentration-dependent manner. After pertussis toxin treatment, the agonist NECA produced a stimulation of cAMP production, whereas CPA and (R)-N(6)-(2-phenylisopropyl)adenosine were ineffective. In CHOAIH cells, however, all three agonists produced both an inhibition of adenylyl cyclase and a pertussis toxin-insensitive stimulation of adenylyl cyclase. All three agonists were more potent at inhibiting adenylyl cyclase in CHOA1H cells than in CHOA1L cells. In contrast, A(1) agonists (and particularly NECA) were less potent at stimulating inositol phosphate accumulation in CHOA1H cells than in CHOA1L cells. After pertussis toxin treatment, agonist-stimulated inositol phosphate accumulation was reduced in CHOA1H cells and abolished in CHOA1L cells. The relative intrinsic activity of NECA in stimulating inositol phosphate accumulation, compared to CPA (100%), was much greater in the presence of pertussis toxin (289.6%) than in the absence of pertussis toxin (155.2%). These data suggest that A(1) adenosine receptors can couple to both pertussis toxin-sensitive and -insensitive G-proteins in an expression level-dependent manner. These data also suggest that the ability of this receptor to activate different G-proteins is dependent on the agonist present.
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Affiliation(s)
- Y Cordeaux
- Institute of Cell Signalling and School of Biomedical Sciences, Medical School, Queen's Medical Centre, Nottingham, United Kingdom
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32
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She QB, Mukherjee JJ, Chung T, Kiss Z. Placental alkaline phosphatase, insulin, and adenine nucleotides or adenosine synergistically promote long-term survival of serum-starved mouse embryo and human fetus fibroblasts. Cell Signal 2000; 12:659-65. [PMID: 11080618 DOI: 10.1016/s0898-6568(00)00117-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Earlier we showed that in serum-starved fibroblasts placental alkaline phosphatase (PALP) can exert growth factor-like effects. Here we report that in mouse embryo (NIH 3T3) and human fetus (HTB-157) fibroblasts, PALP (200 nM) alone provided full protection against serum starvation-induced cell death for 5 days. After 12 days, substantial effects of PALP on cell survival required the copresence of insulin (500 nM) and ATP or adenosine (100 microM). In serum-starved NIH 3T3 cells, PALP induced activating phosphorylation of p42/p44 mitogen-activated protein (MAP) kinases; insulin, but not ATP, had small additional effects. PALP also stimulated the expression of various cyclins; ATP both prolonged and enhanced PALP-induced expression of cyclins A and E. Finally, ATP/adenosine enhanced activation of Akt kinase by insulin. The results suggest that PALP may be a regulator of growth and remodeling of fetal tissues during the second and third trimester of pregnancy when it is expressed.
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Affiliation(s)
- Q B She
- The Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55912, USA
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33
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Morales B, Barrera N, Uribe P, Mora C, Villalón M. Functional cross talk after activation of P2 and P1 receptors in oviductal ciliated cells. Am J Physiol Cell Physiol 2000; 279:C658-69. [PMID: 10942716 DOI: 10.1152/ajpcell.2000.279.3.c658] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The presence of ATP and adenosine receptors and their role in controlling ciliary activity in oviductal ciliated cells was studied by measuring the ciliary beat frequency (CBF) in oviductal tissue cultures. ATP, adenosine, and related compounds increased the CBF in a dose-dependent manner. We established that P2 receptors of subtype 2Y(2) and P1 receptors of subtype A(2a) mediated the responses to ATP and adenosine, respectively. We found evidence to suggest that stimulation of ciliary activity by ATP requires D-myo-inositol 1,4, 5-trisphosphate [Ins(1,4,5)P(3)] metabolism, intracellular Ca(2+) mobilization, and protein kinase C activation. On the other hand, the adenosine effect is mediated by activation of a G(s) protein-dependent pathway that enhances cAMP intracellular levels. To study the interaction between P2 and P1 receptors, cells were stimulated simultaneously with both agonists. We observed a synergistic increase of the CBF even at agonist concentrations (100 nM) that did not produce a significant response when added separately to the culture. Furthermore, a blocker of the cAMP pathway produced a reduction of the ATP response, whereas a blocker of the Ins(1,4,5)P(3) pathway also produced an inhibition of the adenosine response. Our evidence demonstrates that both ATP and adenosine receptors are present in a single ciliated cell and that a mechanism of cross talk could operate in the transduction pathways to control ciliary activity.
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Affiliation(s)
- B Morales
- Departamento de Ciencias Fisiológicas, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
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34
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Yang CM, Wu WB, Pan SL, Tsai YJ, Chiu CT, Wang CC. P2Y(2) receptor-stimulated phosphoinositide hydrolysis and Ca(2+) mobilization in tracheal epithelial cells. Am J Physiol Lung Cell Mol Physiol 2000; 279:L235-41. [PMID: 10926546 DOI: 10.1152/ajplung.2000.279.2.l235] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Extracellular nucleotides have been implicated in the regulation of secretory function through the activation of P2 receptors in the epithelial tissues, including tracheal epithelial cells (TECs). In this study, experiments were conducted to characterize the P2 receptor subtype on canine TECs responsible for stimulating inositol phosphate (InsP(x)) accumulation and Ca(2+) mobilization using a range of nucleotides. The nucleotides ATP and UTP caused a concentration-dependent increase in [(3)H]InsP(x) accumulation and Ca(2+) mobilization with comparable kinetics and similar potency. The selective agonists for P1, P2X, and P2Y(1) receptors, N(6)-cyclopentyladenosine and AMP, alpha,beta-methylene-ATP and beta, gamma-methylene-ATP, and 2-methylthio-ATP, respectively, had little effect on these responses. Stimulation of TECs with maximally effective concentrations of ATP and UTP showed no additive effect on [(3)H]InsP(x) accumulation. The response of a maximally effective concentration of either ATP or UTP was additive to the response evoked by bradykinin. Furthermore, ATP and UTP induced a cross-desensitization in [(3)H]InsP(x) accumulation and Ca(2+) mobilization. These results suggest that ATP and UTP directly stimulate phospholipase C-mediated [(3)H]InsP(x) accumulation and Ca(2+) mobilization in canine TECs. P2Y(2) receptors may be predominantly mediating [(3)H]InsP(x) accumulation, and, subsequently, inositol 1,4,5-trisphosphate-induced Ca(2+) mobilization may function as the transducing mechanism for ATP-modulated secretory function of tracheal epithelium.
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Affiliation(s)
- C M Yang
- Cellular and Molecular Pharmacology Laboratory, Department of Pharmacology, College of Medicine, Chang Gung University, Kwei-San, Tao-Yuan, Taiwan.
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35
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Fujita N, Kakimi M, Ikeda Y, Hiramoto T, Suzuki K. Extracellular ATP inhibits starvation-induced apoptosis via P2X2 receptors in differentiated rat pheochromocytoma PC12 cells. Life Sci 2000; 66:1849-59. [PMID: 10809182 DOI: 10.1016/s0024-3205(00)00508-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Apoptosis in neuronal tissue is an efficient mechanism which contributes to both normal cell development and pathological cell death. The present study explored the effects of extracellular ATP on starvation-induced apoptosis in rat pheochromocytoma PC12 cells. Incubation of differentiated PC12 cells with ATP for 6h suppressed apoptosis. 2-Methylthio-ATP, a P2 purinoceptor agonist, was as potent as ATP in suppressing apoptosis, whereas adenosine, ADP, alpha,betamethylene-ATP or UTP was totally ineffective. The suppressive action of ATP was dependent upon the presence of extracellular Ca2+ and blocked by co-incubation with the P2 antagonist, suramin. DNA ladder formation, a typical symptom of apoptosis in starved cells, was inhibited by ATP, 2-methylthio-ATP but not by UTP. These results suggest that the inhibitory action of extracellular ATP on apoptotic cell death is mediated via the activation of P2X2 receptors in differentiated PC12 cells.
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Affiliation(s)
- N Fujita
- Department of Bioscience and Biotechnology, Ritsumeikan University, Noji-higashi, Japan
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36
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Zhao Z, Makaritsis K, Francis CE, Gavras H, Ravid K. A role for the A3 adenosine receptor in determining tissue levels of cAMP and blood pressure: studies in knock-out mice. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1500:280-90. [PMID: 10699369 DOI: 10.1016/s0925-4439(99)00111-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Adenosine administration has been reported to lower blood pressure by activating specific membrane receptors. The rat and human heart and aorta have been previously found to express both A2-type adenosine receptors, which activate adenylyl cyclase, and A3 adenosine receptors (A3AR), which inhibit adenylyl cyclase. In the current study, we used A3 adenosine receptor (A3AR) knock-out mice to examine the hypothesis that the relative levels of the A2-type adenosine receptors and A3AR determine the steady-state levels of cAMP in the cells and may affect blood pressure. We found that the A3AR knock-out mice express normal levels of the A1- and A2-type adenosine receptors. In situ hybridization demonstrated that the level of A3AR is high in the vascular smooth muscle layer of aortas derived from wild-type mice, but is not detectable in the knock-out mice. The steady-state level of cAMP is elevated in the aorta and heart of knock-out mice, as compared to wild-type mice, but is not altered in platelets, where A3AR is not expressed naturally. A3AR knock-out mice possess a blood pressure comparable to this in wild-type mice. However, when challenged with adenosine, the knock-out mice display a further increase in cAMP levels in the heart and vascular smooth muscle and a significant decrease in blood pressure, as compared to wild-type mice. In contrast, the effect of adenosine on ADP-induced platelet aggregation is similar in both types of mice. These studies indicate that the A3AR affects the steady-state level of cAMP in the tissues where it is naturally expressed, and that it influences the blood pressure in response to adenosine.
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Affiliation(s)
- Z Zhao
- Department of Biochemistry and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA
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37
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Vainio M, Törnquist K. The role of adenosine A(1) receptors in the ATP-evoked Ca(2+) response in rat thyroid FRTL-5 cells. Eur J Pharmacol 2000; 390:43-50. [PMID: 10708705 DOI: 10.1016/s0014-2999(00)00031-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of adenosine A(1) receptor activation on the ATP-induced increase in intracellular free Ca(2+) was studied in control and protein kinase C down-regulated Fisher rat thyroid (FRTL-5) cells. Long-term phorbol ester treatment, which leads to protein kinase C down-regulation, enhanced the ATP-evoked extracellular Ca(2+) influx. The increased Ca(2+) influx was antagonized by the adenosine A(1) receptor antagonist 8-cyclopentyl-1, 3-dipropylxanthine (DPCPX). [3H]DPCPX binding studies revealed that phorbol ester-treatment increased the number of adenosine A(1) receptors. The adenosine A(1) receptor-mediated inhibition of the cyclic AMP formation was not affected by the increased receptor number. We conclude that the enhanced ATP-evoked Ca(2+) influx in protein kinase C down-regulated cells is mediated by adenosine formed by hydrolysis of ATP, and that this adenosine interacts with the increased number of A(1) receptors. The mechanism by which adenosine enhances Ca(2+) entry is not known. Thus, the larger number of adenosine A(1) receptors broadens the spectrum of adenosine A(1) receptor affected signaling systems in FRTL-5 cells.
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Affiliation(s)
- M Vainio
- Department of Biology, Abo Akademi University, BioCity, Tykistökatu 6 A, 20520, Turku, Finland
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38
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Rathbone MP, Middlemiss PJ, Gysbers JW, Andrew C, Herman MA, Reed JK, Ciccarelli R, Di Iorio P, Caciagli F. Trophic effects of purines in neurons and glial cells. Prog Neurobiol 1999; 59:663-90. [PMID: 10845757 DOI: 10.1016/s0301-0082(99)00017-9] [Citation(s) in RCA: 306] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In addition to their well known roles within cells, purine nucleotides such as adenosine 5' triphosphate (ATP) and guanosine 5' triphosphate (GTP), nucleosides such as adenosine and guanosine and bases, such as adenine and guanine and their metabolic products xanthine and hypoxanthine are released into the extracellular space where they act as intercellular signaling molecules. In the nervous system they mediate both immediate effects, such as neurotransmission, and trophic effects which induce changes in cell metabolism, structure and function and therefore have a longer time course. Some trophic effects of purines are mediated via purinergic cell surface receptors, whereas others require uptake of purines by the target cells. Purine nucleosides and nucleotides, especially guanosine, ATP and GTP stimulate incorporation of [3H]thymidine into DNA of astrocytes and microglia and concomitant mitosis in vitro. High concentrations of adenosine also induce apoptosis, through both activation of cell-surface A3 receptors and through a mechanism requiring uptake into the cells. Extracellular purines also stimulate the synthesis and release of protein trophic factors by astrocytes, including bFGF (basic fibroblast growth factor), nerve growth factor (NGF), neurotrophin-3, ciliary neurotrophic factor and S-100beta protein. In vivo infusion into brain of adenosine analogs stimulates reactive gliosis. Purine nucleosides and nucleotides also stimulate the differentiation and process outgrowth from various neurons including primary cultures of hippocampal neurons and pheochromocytoma cells. A tonic release of ATP from neurons, its hydrolysis by ecto-nucleotidases and subsequent re-uptake by axons appears crucial for normal axonal growth. Guanosine and GTP, through apparently different mechanisms, are also potent stimulators of axonal growth in vitro. In vivo the extracellular concentration of purines depends on a balance between the release of purines from cells and their re-uptake and extracellular metabolism. Purine nucleosides and nucleotides are released from neurons by exocytosis and from both neurons and glia by non-exocytotic mechanisms. Nucleosides are principally released through the equilibratory nucleoside transmembrane transporters whereas nucleotides may be transported through the ATP binding cassette family of proteins, including the multidrug resistance protein. The extracellular purine nucleotides are rapidly metabolized by ectonucleotidases. Adenosine is deaminated by adenosine deaminase (ADA) and guanosine is converted to guanine and deaminated by guanase. Nucleosides are also removed from the extracellular space into neurons and glia by transporter systems. Large quantities of purines, particularly guanosine and, to a lesser extent adenosine, are released extracellularly following ischemia or trauma. Thus purines are likely to exert trophic effects in vivo following trauma. The extracellular purine nucleotide GTP enhances the tonic release of adenine nucleotides, whereas the nucleoside guanosine stimulates tonic release of adenosine and its metabolic products. The trophic effects of guanosine and GTP may depend on this process. Guanosine is likely to be an important trophic effector in vivo because high concentrations remain extracellularly for up to a week after focal brain injury. Purine derivatives are now in clinical trials in humans as memory-enhancing agents in Alzheimer's disease. Two of these, propentofylline and AIT-082, are trophic effectors in animals, increasing production of neurotrophic factors in brain and spinal cord. Likely more clinical uses for purine derivatives will be found; purines interact at the level of signal-transduction pathways with other transmitters, for example, glutamate. They can beneficially modify the actions of these other transmitters.
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Affiliation(s)
- M P Rathbone
- Department of Medicine, McMaster University, Hamilton, Ontario, Canada
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39
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Bevan N, Palmer T, Drmota T, Wise A, Coote J, Milligan G, Rees S. Functional analysis of a human A(1) adenosine receptor/green fluorescent protein/G(i1)alpha fusion protein following stable expression in CHO cells. FEBS Lett 1999; 462:61-5. [PMID: 10580092 DOI: 10.1016/s0014-5793(99)01467-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Fusion proteins between the human A(1) adenosine receptor and the pertussis toxin resistant (Cys351Gly) mutant of the G-protein alpha subunit G(i1)alpha (A1/Gi), and between the human A(1) adenosine receptor, the Aequorea victoria green fluorescent protein (GFP) and Cys351Gly G(i1)alpha (A1/GFP/Gi), were expressed in CHO cells. The agonist NECA caused a stimulation of [(35)S]GTPgammaS binding at both fusion proteins with similar concentration dependence as at the native receptor. However in the presence of pertussis toxin NECA stimulation of [(35)S]GTPgammaS binding was only seen at the A1/GFP/Gi fusion protein. The regulation of the adenylyl cyclase and MAP kinase effector systems by both fusion proteins was attenuated following pertussis toxin treatment. These studies demonstrate for the first time the characterisation of a fusion protein between a G-protein coupled receptor, GFP and a G-protein alpha subunit.
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Affiliation(s)
- N Bevan
- Biological Chemistry, Glaxo Wellcome Research and Development, Gunnels Wood Road, Stevenage, UK.
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40
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Michoud MC, Tao FC, Pradhan AA, Martin JG. Mechanisms of the potentiation by adenosine of adenosine triphosphate-induced calcium release in tracheal smooth-muscle cells. Am J Respir Cell Mol Biol 1999; 21:30-6. [PMID: 10385590 DOI: 10.1165/ajrcmb.21.1.3425] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The effects of concomitant P1-receptor stimulation on peak intracellular Ca2+ release by extracellular adenosine 5'-triphosphate (ATP) and 5-hydroxytryptamine (5-HT) were investigated in cultured airway smooth-muscle (ASM) cells. The results show that peak Ca2+ release to ATP is enhanced by preincubation with adenosine (ADO) and with the specific A3 receptor agonist 1-Deoxy-1-(6-([(3-iodophenyl)methyl] amino)-9H-purin-9-yl)-N-methyl-beta-D-ribofuranuronamide (1B-MECA). The response to 5-HT, a smooth-muscle contractile agonist, was also enhanced after preincubation with ADO. Further measurements showed that this enhancement of the response to ATP was dependent on extracellular calcium because it was abolished by the removal of Ca2+ from the extracellular fluid and by incubation with the calcium channel blocker nifedipine. In addition, there was no difference between the levels of total inositol phosphates measured in the presence of ATP alone or of ADO + ATP. AACOCF3, a specific blocker of phospholipase A2, decreased the peak Ca2+ response to ATP and abolished the enhanced response to ATP and 5-HT produced by ADO. We conclude that stimulation of P1 and P2 receptors in ASM cells activates not only phospholipase C but also phospholipase A2. The enhancement of ATP-induced and 5-HT-induced Ca2+ release is due to Ca2+ influx from the extracellular fluid through a Ca2+ channel presumably modulated by arachidonic acid. These data show that endogenous ADO may modulate airway hyperresponsiveness by enhancing the ASM response to contractile agonists.
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Affiliation(s)
- M C Michoud
- Meakins-Christie Laboratories and the Heisler Laboratory of the Montreal Chest Institute Research Centre, McGill University, Montreal, Quebec, Canada
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41
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Gutiérrez AM, Kornfeld M, Persson AE. Calcium response to adenosine and ATP in rabbit afferent arterioles. ACTA PHYSIOLOGICA SCANDINAVICA 1999; 166:175-81. [PMID: 10468653 DOI: 10.1046/j.1365-201x.1999.00557.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The effects of purine compounds in the renal vasculature are almost exclusively restricted to pre-glomerular vessels. Although their physiological role as extracellular messengers is not clear, there are extensive data indicating the importance of adenosine and ATP in the regulation of renal haemodynamics. This study was undertaken to characterize the calcium response of rabbit afferent arteriole to adenosine, ATP and other nucleotides. Experiments were performed in isolated afferent arterioles, microdissected from rabbit kidneys and loaded with fura-2. Intracellular calcium concentration ([Ca2+]i) was measured by video in proximal and distal parts of the afferent arteriole. Application of 100 microM adenosine or ATP increased [Ca2+]i in both arteriolar regions. In all cases the response had two well distinguishable phases: a quick peak increase and a plateau phase that equilibrated at a [Ca2+]i significantly higher than the basal level. UTP (100 microM) had no effect on the arteriole. Removal of extracellular calcium (2.5 mM EGTA) abolished only the plateau phase in response to adenosine, without significantly changing the peak increase. In contrast, the response to ATP was completely abolished in both arteriolar regions, where [Ca2+]i decreased upon application of the agonist and rapidly increased after restoration of calcium concentration to plasma level. We conclude that P1 and P2X receptors are present along the rabbit afferent arteriole and mediate calcium mobilization, with the same distribution in the proximal and distal segments.
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Affiliation(s)
- A M Gutiérrez
- Department of Physiology, University of Uppsala, Uppsala, Sweden
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Smith AD, Moloney S, Khoyi MA, Westfall DP. Species-dependent effects of adenosine receptor agonists on contractile responses of vas deferens to ATP. JOURNAL OF AUTONOMIC PHARMACOLOGY 1999; 19:181-4. [PMID: 10511475 DOI: 10.1046/j.1365-2680.1999.00132.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. Experiments were carried out to examine the postjunctional actions of adenosine receptor agonists on the smooth muscle of the vas deferens of the guinea-pig and rabbit. 2. Although they produced neither contraction nor relaxation by themselves, adenosine analogues enhanced contractions of the guinea-pig vas deferens induced by 10 microm ATP. The rank order of potency was N6-cyclopentyladenosine (CPA) > 5'-N-ethylcarboxamidoadenosine (NECA) > adenosine > CGS 21680. Dose-response curves for NECA were shifted to the right by the nonselective adenosine receptor antagonist 8(p-sulphophenyl)theophylline (8-SPT; 100 microM) and by the selective A1-receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 1 mM). 3. In the rabbit vas deferens, contractions induced by ATP (1 mM) were inhibited rather than facilitated by NECA. Neither CPA, R(-)-N6-(2-phenyl isopropyl)-adenosine (R-PIA) nor CGS 21680 had any effect. 4. The results indicate that the smooth muscle of the guinea-pig vas deferens expresses facilitatory adenosine A1 receptors but not adenosine A2 receptors. In contrast, in rabbit there are postjunctional inhibitory adenosine A2A receptors but not adenosine A1 receptors.
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Affiliation(s)
- A D Smith
- Department of Pharmacology, School of Medicine, University of Nevada, Reno 89557, USA
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Jim�nez AI, Castro E, Mirabet M, Franco R, Delicado EG, Miras-Portugal MT. Potentiation of ATP calcium responses by A2B receptor stimulation and other signals coupled to Gs proteins in type-1 cerebellar astrocytes. Glia 1999. [DOI: 10.1002/(sici)1098-1136(199904)26:2<119::aid-glia3>3.0.co;2-d] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Dickenson JM, Hill SJ. Potentiation of adenosine A1 receptor-mediated inositol phospholipid hydrolysis by tyrosine kinase inhibitors in CHO cells. Br J Pharmacol 1998; 125:1049-57. [PMID: 9846644 PMCID: PMC1565676 DOI: 10.1038/sj.bjp.0702170] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
1. The effect of protein tyrosine kinase inhibitors on human adenosine A1 receptor-mediated [3H]-inositol phosphate ([3H]-IP) accumulation has been studied in transfected Chinese hamster ovary cells (CHO-A1) cells. 2. In agreement with our previous studies the selective adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) stimulated the accumulation of [3H]-IPs in CHO-A1 cells. Pre-treatment with the broad spectrum tyrosine kinase inhibitor genistein (100 microM; 30 min) potentiated the responses elicited by 1 microM (199+/-17% of control CPA response) and 10 microM CPA (234+/-15%). Similarly, tyrphostin A47 (100 microM) potentiated the accumulation of [3H]-IPs elicited by 1 microM CPA (280+/-32%). 3. Genistein (EC50 = 13.7+/-1.2 microM) and tyrphostin A47 (EC50 = 10.4+/-3.9 microM) potentiated the [3H]-IP response to 1 microM CPA in a concentration-dependent manner. 4. Pre-incubation with the inactive analogues of genistein and tyrphostin A47, daidzein (100 microM; 30 min) and tyrphostin A1 (100 microM; 30 min), respectively, had no significant effect on the accumulation of [3H]-IPs elicited by 1 microM CPA. 5. Genistein (100 microM) had no significant effect on the accumulation of [3H]-IPs produced by the endogenous thrombin receptor (1 u ml(-1); 100+/-10% of control response). In contrast, tyrphostin A47 produced a small augmentation of the thrombin [3H]-IP response (148+/-13%). 6. Genistein (100 microM) had no effect on the [3H]-IP response produced by activation of the endogenous Gq-protein coupled CCK(A) receptor with the sulphated C-terminal octapeptide of cholecystokinin (1 microM CCK-8; 96+/-6% of control). In contrast, tyrphostin A47 (100 microM) caused a small but significant increase in the response to 1 microM CCK-8 (113+/-3% of control). 7. The phosphatidylinositol 3-kinase inhibitor LY 294002 (30 microM) and the MAP kinase kinase inhibitor PD 98059 (50 microM) had no significant effect on the [3H]-IP responses produced by 1 microM CPA and 1 microM CCK-8. 8. These observations suggest that a tyrosine kinase-dependent pathway may be involved in the regulation of human adenosine A1 receptor mediated [3H]-IP responses in CHO-A1 cells.
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Affiliation(s)
- J M Dickenson
- Institute of Cell Signalling and School of Biomedical Sciences, Queen's Medical Centre, Nottingham
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Guieu R, Dussol B, Halimi G, Bechis G, Sampieri F, Berland Y, Sampol J, Couraud F, Rochat H. Adenosine and the nervous system: pharmacological data and therapeutic perspectives. GENERAL PHARMACOLOGY 1998; 31:553-61. [PMID: 9792214 DOI: 10.1016/s0306-3623(98)00071-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
1. Adenosine acts on a family of G-protein-coupled receptors called purinoreceptors. 2. Four subtypes have been cloned and pharmacologically characterized. 3. The principal pharmacological data and structure-function relations for agonist interactions with P1 receptors are presented. 4. We conclude that the potent role of adenosine in the nervous system may be interesting for the development of drugs targeted at purines and their receptors.
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Affiliation(s)
- R Guieu
- Laboratoire de Biochimie et d'Ingéniérie des Protéines, URA CNRS 1455 Faculté de Médecine Secteur Nord, Marseille, France
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Dickenson JM, Hill SJ. Involvement of G-protein betagamma subunits in coupling the adenosine A1 receptor to phospholipase C in transfected CHO cells. Eur J Pharmacol 1998; 355:85-93. [PMID: 9754942 DOI: 10.1016/s0014-2999(98)00468-3] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In transfected Chinese hamster ovary (CHO-A1) cells the human adenosine A1 receptor directly stimulates pertussis toxin-sensitive increases in inositol phosphate production and potentiates (synergistically) the inositol phosphate responses mediated by Gq-coupled P2Y2 purinoceptor and CCK(A) receptors. In the present study we have investigated the role of Gbetagamma subunits in mediating adenosine A1 receptor effects on phospholipase C activation (both direct and synergistic) by transiently transfecting CHO-A1 cells with a scavenger of Gbetagamma subunits: the C-terminus of beta-adrenoceptor kinase 1 (beta ark1 residues 495-689). [3H]inositol phosphate responses to the selective adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA; 1 microM) were inhibited (41 +/- 1%) in CHO-A1 cells transiently transfected with the Gbetagamma scavenger, beta ark1 (495-689). Expression of beta ark1 (495-689) protein was confirmed by Western blotting. In contrast, adenosine A1 receptor-mediated inhibition of forskolin stimulated [3H]cyclic AMP accumulation was unaffected by transient expression of beta ark1 (495-689). Beta ark1 (495-689) expression had no significant effect on the [3H]inositol phosphate responses produced by activation of the endogenous P2Y2 purinoceptor (100 microM UTP; 92 +/- 0.8% of control). [3H]inositol phosphate accumulation in response to adenosine A receptor activation was also attenuated in CHO-K1 cells co-transfected with the beta ark1 (495-689) minigene (59 +/- 4% inhibition of control response to 1 microM CPA). Finally, transient expression of beta ark1 (495-689) in CHO-A1 cells inhibited the augmentation of [3H]inositol phosphate responses resulting from co-activation of adenosine A1 receptors and P2Y2 purinoceptors. These experiments indicate that Gbetagamma subunits are involved in the direct coupling the adenosine A1 receptor to phospholipase C and that they also participate in the augmentation of P2Y2 purinoceptor-mediated [3H]inositol phosphate responses by the adenosine A1 receptor.
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Affiliation(s)
- J M Dickenson
- Institute of Cell Signalling, School of Biomedical Sciences, University of Nottingham, Queen's Medical Centre, UK
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Saura CA, Mallol J, Canela EI, Lluis C, Franco R. Adenosine deaminase and A1 adenosine receptors internalize together following agonist-induced receptor desensitization. J Biol Chem 1998; 273:17610-7. [PMID: 9651356 DOI: 10.1074/jbc.273.28.17610] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A1 adenosine receptors (A1Rs) and adenosine deaminase (ADA; EC 3.5.4. 4) interact on the cell surface of DDT1MF-2 smooth muscle cells. The interaction facilitates ligand binding and signaling via A1R, but it is not known whether it has a role in homologous desensitization of A1Rs. Here we show that chronic exposure of DDT1MF-2 cells to the A1R agonist, N6-(R)-(phenylisopropyl)adenosine (R-PIA), caused a rapid aggregation or clustering of A1 receptor molecules on the cell membrane, which was enhanced by pretreatment with ADA. Colocalization between A1R and ADA occurred in the R-PIA-induced clusters. Interestingly, colocalization between A1R and ADA also occurred in intracellular vesicles after internalization of both protein molecules in response to R-PIA. Agonist-induced aggregation of A1Rs was mediated by phosphorylation of A1Rs, which was enhanced and accelerated in the presence of ADA. Ligand-induced second-messenger desensitization of A1Rs was also accelerated in the presence of exogenous ADA, and it correlated well with receptor phosphorylation. However, although phosphorylation of A1R returned to its basal state within minutes, desensitization continued for hours. The loss of cell-surface binding sites (sequestration) induced by the agonist was time-dependent (t1/2= 10 +/- 1 h) and was accelerated by ADA. All of these results strongly suggest that ADA plays a key role in the regulation of A1Rs by accelerating ligand-induced desensitization and internalization and provide evidence that the two cell surface proteins internalize via the same endocytic pathway.
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Affiliation(s)
- C A Saura
- Departament de Bioquímica i Biologia Molecular, Facultat de Química, Universitat de Barcelona, 08028 Barcelona, Catalunya, Spain
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Akerman KE, Näsman J, Lund PE, Shariatmadari R, Kukkonen JP. Endogenous extracellular purine nucleotides redirect alpha2-adrenoceptor signaling. FEBS Lett 1998; 430:209-12. [PMID: 9688540 DOI: 10.1016/s0014-5793(98)00664-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Many receptors coupled to inhibitory Go/Gi-type G proteins often also produce stimulatory signals like Ca2+ mobilisation. When expressed in CHO cells the alpha2-adrenoceptor subtypes alpha2A, alpha2B and alpkha2C mobilised Ca2+. These responses were strongly reduced by the P2Y-purinoceptor antagonist suramin. A large proportion of the total pool of purine nucleotides was found extracellularly. Removal of extracellular nucleotides with apyrase or by constant perfusion had a similar effect as suramin. These treatments did not affect the alpha2-adrenoceptor-mediated inhibition of cAMP production. This indicates that cells may be primed or their signaling pathways redirected towards Ca2+ mobilisation by 'autocrine' release of nucleotides.
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Affiliation(s)
- K E Akerman
- Department of Physiology, Uppsala University, BMC, Sweden.
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Abstract
1. Extracellular adenosine triphosphate (ATP) is mitogenic for vascular smooth muscle cells (VSMC) and stimulates several events that are important for cell proliferation: DNA synthesis, protein synthesis, increase of cell number, immediate early genes, cell-cycle progression, and tyrosine phosphorylation. 2. Receptor characterization indicates mitogenic effects of both P2U and P2Y receptors. The P2X receptor is lost in cultured VSMC and is not involved. Several related biological substances such as UTP, ITP, GTP, AP4A, ADP, and UDP are also mitogenic. 3. Signal transduction is mediated via Gq-proteins, phospholipase C beta, phospholipase D, diacyl glycerol, protein kinase C alpha, delta, Raf-1, MEK, and MAPK. 4. ATP acts synergistically with polypeptide growth factors (PDGF, bFGF, IGF-1, EGF, insulin) and growth factors acting via G-protein-coupled receptors (noradrenaline, neuropeptide Y, 5-hydroxytryptamine, angiotensin II, endothelin-1). 5. The mitogenic effects have been demonstrated in rat, porcine, and bovine VSMC and cells from human coronary arteries, aorta, and subcutaneous arteries and veins. 6. The trophic effects on VSMC and the abundant sources for extracellular ATP in the vessel wall make a pathophysiological role probable in the development of atherosclerosis, neointima-formation after angioplasty, and possibly hypertension.
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Affiliation(s)
- D Erlinge
- Department of Internal Medicine, Lund University Hospital, Sweden.
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Murthy KS, Makhlouf GM. Coexpression of ligand-gated P2X and G protein-coupled P2Y receptors in smooth muscle. Preferential activation of P2Y receptors coupled to phospholipase C (PLC)-beta1 via Galphaq/11 and to PLC-beta3 via Gbetagammai3. J Biol Chem 1998; 273:4695-704. [PMID: 9468531 DOI: 10.1074/jbc.273.8.4695] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
P2 receptor subtypes and their signaling mechanisms were characterized in dispersed smooth muscle cells. UTP and ATP stimulated inositol 1,4,5-triphosphate formation, Ca2+ release, and contraction that were abolished by U-73122 and guanosine 5'-O-(3-thio)diphosphate, and partly inhibited (50-60%) by pertussis toxin (PTX). ATP analogs (adenosine 5'-(alpha, beta-methylene)triphosphate, adenosine 5'-(beta, gamma-methylene)triphosphate, and 2-methylthio-ATP) stimulated Ca2+ influx and contraction that were abolished by nifedipine and in Ca2+-free medium. Micromolar concentrations of ATP stimulated both Ca2+ influx and Ca2+ release. ATP and UTP activated Gq/11 and Gi3 in gastric and aortic smooth muscle and heart membranes, Gq/11 and Gi1 and/or Gi2 in liver membranes, and Go and Gi1-3 in brain membranes. Phosphoinositide hydrolysis stimulated by ATP and UTP was mediated concurrently by Galphaq/11-dependent activation of phospholipase (PL) C-beta1 and Gbetagammai3-dependent activation of PLC-beta3. Phosphoinositide hydrolysis was partially inhibited by PTX or by antibodies to Galphaq/11, Gbeta, PLC-beta1, or PLC-beta3, and completely inhibited by the following combinations (PLC-beta1 and PLC-beta3 antibodies; Galphaq/11 and Gbeta antibodies; PLC-beta1 and Gbeta antibodies; PTX with either PLC-beta1 or Galphaq/11 antibody). The pattern of responses implied that P2Y2 receptors in visceral, and probably vascular, smooth muscle are coupled to PLC-beta1 via Galphaq/11 and to PLC-beta3 via Gbetagammai3. These receptors co-exist with ligand-gated P2X1 receptors activated by ATP analogs and high levels of ATP.
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Affiliation(s)
- K S Murthy
- Departments of Medicine and Physiology, Medical College of Virginia, Richmond, Virginia 23298-0711, USA
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