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Brailoiu E, Chakraborty S, Brailoiu GC, Zhao P, Barr JL, Ilies MA, Unterwald EM, Abood ME, Taylor CW. Choline Is an Intracellular Messenger Linking Extracellular Stimuli to IP 3-Evoked Ca 2+ Signals through Sigma-1 Receptors. Cell Rep 2019; 26:330-337.e4. [PMID: 30625315 PMCID: PMC6326163 DOI: 10.1016/j.celrep.2018.12.051] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/11/2018] [Accepted: 12/11/2018] [Indexed: 11/18/2022] Open
Abstract
Sigma-1 receptors (Sig-1Rs) are integral ER membrane proteins. They bind diverse ligands, including psychoactive drugs, and regulate many signaling proteins, including the inositol 1,4,5-trisphosphate receptors (IP3Rs) that release Ca2+ from the ER. The endogenous ligands of Sig-1Rs are unknown. Phospholipase D (PLD) cleaves phosphatidylcholine to choline and phosphatidic acid (PA), with PA assumed to mediate all downstream signaling. We show that choline is also an intracellular messenger. Choline binds to Sig-1Rs, it mimics other Sig-1R agonists by potentiating Ca2+ signals evoked by IP3Rs, and it is deactivated by metabolism. Receptors, by stimulating PLC and PLD, deliver two signals to IP3Rs: IP3 activates IP3Rs, and choline potentiates their activity through Sig-1Rs. Choline is also produced at synapses by degradation of acetylcholine. Choline uptake by transporters activates Sig-1Rs and potentiates Ca2+ signals. We conclude that choline is an endogenous agonist of Sig-1Rs linking extracellular stimuli, and perhaps synaptic activity, to Ca2+ signals.
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Affiliation(s)
- Eugen Brailoiu
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA.
| | | | - G Cristina Brailoiu
- Department of Pharmaceutical Sciences, Jefferson College of Pharmacy, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Pingwei Zhao
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Jeffrey L Barr
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Marc A Ilies
- Department of Pharmaceutical Sciences, Temple University School of Pharmacy, Philadelphia, PA 19140, USA
| | - Ellen M Unterwald
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Mary E Abood
- Center for Substance Abuse Research, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Colin W Taylor
- Department of Pharmacology, Tennis Court Road, Cambridge CB2 1PD, UK.
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P2X and P2Y receptors—role in the pathophysiology of the nervous system. Int J Mol Sci 2014; 15:23672-704. [PMID: 25530618 PMCID: PMC4284787 DOI: 10.3390/ijms151223672] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 12/03/2014] [Accepted: 12/06/2014] [Indexed: 12/16/2022] Open
Abstract
Purinergic signalling plays a crucial role in proper functioning of the nervous system. Mechanisms depending on extracellular nucleotides and their P2 receptors also underlie a number of nervous system dysfunctions. This review aims to present the role of purinergic signalling, with particular focus devoted to role of P2 family receptors, in epilepsy, depression, neuropathic pain, nervous system neoplasms, such as glioma and neuroblastoma, neurodegenerative diseases like Parkinson’s disease, Alzheimer’s disease and multiple sclerosis. The above-mentioned conditions are associated with changes in expression of extracellular ectonucleotidases, P2X and P2Y receptors in neurons and glial cells, as well as releasing considerable amounts of nucleotides from activated or damaged nervous tissue cells into the extracellular space, which contributes to disturbance in purinergic signalling. The numerous studies indicate a potential possibility of using synthetic agonists/antagonists of P2 receptors in treatment of selected nervous system diseases. This is of particular significance, since numerous available agents reveal a low effectiveness and often produce side effects.
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Burnstock G, Di Virgilio F. Purinergic signalling and cancer. Purinergic Signal 2014; 9:491-540. [PMID: 23797685 DOI: 10.1007/s11302-013-9372-5] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 06/06/2013] [Indexed: 01/24/2023] Open
Abstract
Receptors for extracellular nucleotides are widely expressed by mammalian cells. They mediate a large array of responses ranging from growth stimulation to apoptosis, from chemotaxis to cell differentiation and from nociception to cytokine release, as well as neurotransmission. Pharma industry is involved in the development and clinical testing of drugs selectively targeting the different P1 nucleoside and P2 nucleotide receptor subtypes. As described in detail in the present review, P2 receptors are expressed by all tumours, in some cases to a very high level. Activation or inhibition of selected P2 receptor subtypes brings about cancer cell death or growth inhibition. The field has been largely neglected by current research in oncology, yet the evidence presented in this review, most of which is based on in vitro studies, although with a limited amount from in vivo experiments and human studies, warrants further efforts to explore the therapeutic potential of purinoceptor targeting in cancer.
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The actions of Pasteurella multocida toxin on neuronal cells. Neuropharmacology 2013; 77:9-18. [PMID: 24055502 PMCID: PMC3878393 DOI: 10.1016/j.neuropharm.2013.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/03/2013] [Accepted: 09/05/2013] [Indexed: 02/06/2023]
Abstract
Pasteurella multocida toxin (PMT) activates the G-proteins Gαi(1-3), Gαq, Gα11, Gα12 and Gα13 by deamidation of specific glutamine residues. A number of these alpha subunits have signalling roles in neurones. Hence we studied the action of this toxin on rat superior cervical ganglion (SCG) neurones and NG108-15 neuronal cells. Both Gαq and Gα11 could be identified in SCGs with immunocytochemistry. PMT had no direct action on Kv7 or Cav2 channels in SCGs. However PMT treatment enhanced muscarinic receptor mediated inhibition of M-current (Kv7.2 + 7. 3) as measured by a 19-fold leftward shift in the oxotremorine-M concentration–inhibition curve. Agonists of other receptors, such as bradykinin or angiotensin, that inhibit M-current did not produce this effect. However the amount of PIP2 hydrolysis could be enhanced by PMT for all three agonists. In a transduction system in SCGs that is unlikely to be affected by PMT, Go mediated inhibition of calcium current, PMT was ineffective whereas the response was blocked by pertussis toxin as expected. M1 muscarinic receptor evoked calcium mobilisation in transformed NG108-15 cells was enhanced by PMT. The calcium rises evoked by uridine triphosphate acting on endogenous P2Y2 receptors in NG108-15 cells were enhanced by PMT. The time and concentration dependence of the PMT effect was different for the resting calcium compared to the calcium rise produced by activation of P2Y2 receptors. PMT's action on these neuronal cells would suggest that if it got into the brain, symptoms of a hyperexcitable nature would be seen, such as seizures. Pasteurella multocida toxin (PMT) activates a range of G-protein alpha subunits. PMT increased muscarinic receptor mediated suppression of Kv7 potassium current in sympathetic neurones. PMT enhances both muscarinic and purinergic receptor mediated calcium mobilisation in NG108-15 cells. Both these events are mediated by the G-proteins Gq or G11. We would predict that the symptoms of central nervous system PMT toxicity would be hyperexcitable events such as seizures.
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Sauer R, El-Tayeb A, Kaulich M, Müller CE. Synthesis of uracil nucleotide analogs with a modified, acyclic ribose moiety as P2Y(2) receptor antagonists. Bioorg Med Chem 2009; 17:5071-9. [PMID: 19523835 DOI: 10.1016/j.bmc.2009.05.062] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Revised: 05/16/2009] [Accepted: 05/23/2009] [Indexed: 11/17/2022]
Abstract
A series of new uracil nucleotide analogs (monophosphates, triphosphates, and phosphonates) was synthesized, in which the ribose moiety was replaced by acyclic chains, including branched or linear alkyl or dialkylether linkers. 1-omega-Bromoalkyluracil derivatives (2) were converted to the corresponding alcohols by treatment with sodium hydroxide and subsequently phosphorylated using phosphorus oxychloride followed by hydrolysis to yield the monophosphates, or by coupling with diphosphate to form the triphosphates. Reaction of 2 with triethyl phosphite followed by deprotection with trimethylsilyl bromide led to the omega-phosphonylalkyluracil derivatives. These products could be further phosphorylated by converting them into their imidazolides and subsequent treatment with diphosphate yielding the corresponding UTP analogs. Nucleoside analogs with an oxygen atom in the 2'-position, which are more similar to the natural ribosides, were synthesized from silylated uracil and trimethylsilyl iodide-treated 1,3-dioxolane, or 1,3-dioxane, respectively, and subsequently phosphorylated by standard procedures. The nucleotide analogs were investigated in a functional assay at NG108-15 cells, a neuroblastomaxglioma hybrid cell line which expresses the UTP- and ATP-activated nucleotide receptor subtype P2Y(2). The acyclic nucleotide analogs were generally weaker ligands than UTP, and-in contrast to UTP-they were antagonistic. The most potent compound was diphosphoric 5-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)pentylphosphonic anhydride (5c) with an IC(50) value of 92microM showing that the replacement of the alpha-phosphate by phosphonate, which leads to enhanced stability, was well tolerated.
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Affiliation(s)
- Roland Sauer
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, An der Immenburg 4, D-53121 Bonn, Germany
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Nishii N, Nejime N, Yamauchi C, Yanai N, Shinozuka K, Nakabayashi T. Effects of ATP on the intracellular calcium level in the osteoblastic TBR31-2 cell line. Biol Pharm Bull 2009; 32:18-23. [PMID: 19122274 DOI: 10.1248/bpb.32.18] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the effects of extracellular ATP on TBR31-2 cells established from the bone marrow of transgenic mice harboring the temperature-sensitive simian virus (SV) 40 T-antigen gene. These cells showed the capacity to differentiate toward osteoblasts and could be enhanced by bone morphogenetic protein (BMP)-2, an inducer of osteoblasts. The intracellular calcium ion level ([Ca(2+)](i)) in differentiating TBR31-2 cells was measured by fluorescence confocal microscopic imaging using the Ca(2+)-sensitive probe, Calcium Green 1/AM. P2 receptor agonists, such as ATP (1 microM), uridine 5'-triphosphate (1 microM), and ADP (1 microM), significantly increased the [Ca(2+)](i) of TBR31-2 cells in 2-d and 5-d cultures, but a potent P2X receptor agonist, alpha,beta-methylene ATP (10 microM), did not increase [Ca(2+)](i). The increase in [Ca(2+)](i) induced by ATP in the 2-d culture tended to be higher than in the 5-d culture. The increase in [Ca(2+)](i) of both cultures was inhibited by pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid, a P2 receptor antagonist. However, in an external Ca(2+)-free condition ATP-induced increase in [Ca(2+)](i) was unchanged at either stage. U73122, phospholipase C inhibitor and Thapsigargin, a calcium-pump inhibitor, significantly inhibited the increase in [Ca(2+)](i) at both stages. Reverse transcription-polymerase chain reaction analysis showed that the expression of P2Y receptor mRNA was higher in the 2-d culture than in the 5-d culture. These results indicate that ATP induces the increase in [Ca(2+)](i) from the calcium store through activating P2Y receptors in TBR31-2 cells and that the 2-d culture can respond to ATP more than the 5-d culture due to the higher expression of P2Y receptors. This suggests that the physiological role of ATP in osteoblasts is altered during differentiation.
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Affiliation(s)
- Naomi Nishii
- First Department of Biochemistry, School of Pharmacy and Pharmaceutical Sciences, Mukogawa Women's University, Nishinomiya, Hyogo, Japan
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Sak K, Illes P. Neuronal and glial cell lines as model systems for studying P2Y receptor pharmacology. Neurochem Int 2005; 47:401-12. [PMID: 16081187 DOI: 10.1016/j.neuint.2005.05.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Accepted: 05/31/2005] [Indexed: 11/18/2022]
Abstract
Investigation of the role of extracellular nucleotides in nervous system has been one of the main topics of the P2Y receptor research throughout the years. In parallel to numerous studies on primary culture systems, various neuronal and non-neuronal cell lines have been used to model in vitro the processes mediated by extracellular nucleotides. In this review article, a survey of expression profiles of G protein-coupled P2Y receptor subtypes in nervous-system-derived cell lines is presented, by analysing the receptor expression at the mRNA, protein, and functional level. The variability of receptor expression profiles in established cell lines is further discussed, bringing forward some general properties for neuronal and glial malignant cell lines.
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Affiliation(s)
- Katrin Sak
- Rudolf-Boehm Institute of Pharmacology and Toxicology, and Interdisciplinary Center for Clinical Research, Medical Faculty, University of Leipzig, D-04107 Leipzig, Germany.
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Cavaliere F, Nestola V, Amadio S, D'Ambrosi N, Angelini DF, Sancesario G, Bernardi G, Volonté C. The metabotropic P2Y4 receptor participates in the commitment to differentiation and cell death of human neuroblastoma SH-SY5Y cells. Neurobiol Dis 2005; 18:100-9. [PMID: 15649700 DOI: 10.1016/j.nbd.2004.09.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2004] [Revised: 08/31/2004] [Accepted: 09/07/2004] [Indexed: 01/19/2023] Open
Abstract
Extracellular nucleotides exert a variety of biological actions through different subtypes of P2 receptors. Here we characterized in the human neuroblastoma SH-SY5Y cells the simultaneous presence of various P2 receptors, belonging to the P2X ionotropic and P2Y metabotropic families. Western blot analysis detected the P2X1,2,4,5,6,7 and P2Y1,2,4,6, but not the P2X3 and P2Y12 receptors. We then investigated which biological effects were mediated by the P2Y4 subtype and its physiological pyrimidine agonist UTP. We found that neuronal differentiation of the SH-SY5Y cells with dibutiryl-cAMP increased the expression of the P2Y4 protein and that UTP itself was able to positively interfere with neuritogenesis. Moreover, transient transfection and activation of P2Y4 also facilitated neuritogenesis in SH-SY5Y cells, as detected by morphological phase contrast analysis and confocal examination of neurofilament proteins NFL. This was concurrent with increased transcription of immediate-early genes linked to differentiation such as cdk-5 and NeuroD6, and activity of AP-1 transcription family members such as c-fos, fos-B, and jun-D. Nevertheless, a prolonged activation of the P2Y4 receptor by UTP also induced cell death, both in naive, differentiated, and P2Y4-transfected SH-SY5Y cells, as measured by direct count of intact nuclei and cytofluorimetric analysis of damaged DNA. Taken together, our data indicate that the high expression and activation of the P2Y4 receptor participates in the neuronal differentiation and commitment to death of SH-SY5Y cells.
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Tulapurkar ME, Laubinger W, Nahum V, Fischer B, Reiser G. Subtype specific internalization of P2Y1 and P2Y2 receptors induced by novel adenosine 5'-O-(1-boranotriphosphate) derivatives. Br J Pharmacol 2004; 142:869-78. [PMID: 15197109 PMCID: PMC1575069 DOI: 10.1038/sj.bjp.0705859] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
P2Y-nucleotide receptors represent important targets for drug development. The lack of stable and receptor specific agonists, however, has prevented successful therapeutic applications. A novel series of P-boronated ATP derivatives (ATP-alpha-B) were synthesized by substitution of a nonbridging O at P(alpha) with a BH(3) group. This introduces a chiral center, thus resulting in diastereoisomers. In addition, at C2 of the adenine ring a further substitution was made (Cl- or methylthio-). The pairs of diastereoisomers were denoted here as A and B isomers. Here, we tested the receptor subtype specificity of these analogs on HEK 293 cells stably expressing rat P2Y(1) and rat P2Y(2) receptors, respectively, both attached to the fluorescent marker protein GFP (rP2Y(1)-GFP, rP2Y(2)-GFP). We investigated agonist-induced receptor endocytosis, [Ca(2+)](i) rise and arachidonic acid (AA) release. Agonist-induced endocytosis of rP2Y(1)-GFP was more pronounced for the A isomers than the corresponding B counterparts for all ATP-alpha-B analogs. Both 2-MeS-substituted diastereoisomers induced a greater degree of agonist-induced receptor endocytosis as compared to the 2-Cl-substituted derivatives. Endocytosis results are in accordance with the potency to induce Ca(2+) release by these compounds in HEK 293 cells stably transfected with rP2Y(1). In case of rP2Y(2)-GFP, the borano-nucleotides were very weak agonists in comparison to UTP and ATP in terms of Ca(2+) release, AA release and in inducing receptor endocytosis. The different ATP-alpha-B derivatives and also the diastereoisomers were equally ineffective. Thus, the new agonists may be considered as potent and highly specific agonist drug candidates for P2Y(1) receptors. The difference in activity of the ATP analogs at P2Y receptors could be used as a tool to investigate structural differences between P2Y receptor subtypes.
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Affiliation(s)
- M E Tulapurkar
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany
| | - W Laubinger
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany
| | - V Nahum
- Department of Chemistry, Gonda-Goldschmied Medical Research Center, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - B Fischer
- Department of Chemistry, Gonda-Goldschmied Medical Research Center, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - G Reiser
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Leipziger Strasse 44, 39120 Magdeburg, Germany
- Author for correspondence:
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Abstract
Propagation of interastrocyte Ca2+ waves is mediated by diffusion of extracellular adenosine triphosphate (ATP), and may require regenerative release of ATP. The ability of ATP to initiate release of intracellular ATP was assessed by labeling adenine nucleotide pools in astrocyte cultures with 14C-adenine. The 14C-purines released during exposure to ATP were then identified by thin-layer chromatography. ATP treatment caused a five-fold increase in release of 14C-ATP but not 14C-ADP or 14C-AMP, indicating selectivity for release of ATP. Other P2 receptor agonists also caused significant 14C-ATP release, and the P2 receptor antagonists suramin, reactive blue-2 and pyridoxalphosphate-6-azo(benzene-2,4-disulfonic acid) (PPADS) inhibited ATP-induced 14C-ATP release to varying degrees, suggesting the involvement of a P2 receptor. ATP-induced 14C-ATP release was not affected by chelation of intracellular Ca2+ with BAPTA-AM, or by blockers of Ca2+ release from intracellular stores or of extracellular Ca2+ influx, suggesting a Ca2+-independent response. ATP-induced 14C-ATP release was significantly inhibited by non-selective anion channel blockers but not by blockers of ATP-binding cassette proteins, gap junction hemichannels, or vesicular exocytosis. Release of adenine nucleotides induced by 0 Ca2+ was, in contrast, not selective for ATP, and was susceptible to inhibition by gap junction blockers. These findings indicate that astrocytes are capable of ATP-induced ATP release and support a role for regenerative ATP release in glial Ca2+ wave propagation.
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Affiliation(s)
- Christopher M Anderson
- Department of Neurology, University of California, San Francisco and Department of Veterans Affairs Medical Center, San Francisco, California 94121, USA.
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Burnstock G, Knight GE. Cellular Distribution and Functions of P2 Receptor Subtypes in Different Systems. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 240:31-304. [PMID: 15548415 DOI: 10.1016/s0074-7696(04)40002-3] [Citation(s) in RCA: 573] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review is aimed at providing readers with a comprehensive reference article about the distribution and function of P2 receptors in all the organs, tissues, and cells in the body. Each section provides an account of the early history of purinergic signaling in the organ?cell up to 1994, then summarizes subsequent evidence for the presence of P2X and P2Y receptor subtype mRNA and proteins as well as functional data, all fully referenced. A section is included describing the plasticity of expression of P2 receptors during development and aging as well as in various pathophysiological conditions. Finally, there is some discussion of possible future developments in the purinergic signaling field.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Institute, Royal Free and University College Medical School, London NW3 2PF, United Kingdom
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Kaulich M, Qurishi R, Müller CE. Extracellular metabolism of nucleotides in neuroblastoma x glioma NG108-15 cells determined by capillary electrophoresis. Cell Mol Neurobiol 2003; 23:349-64. [PMID: 12825832 DOI: 10.1023/a:1023640721630] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
1. The metabolism of extracellular nucleotides in NG108-15 cells, a neuroblastoma x glioma hybrid cell line, was studied by means of capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC). 2. In NG108-15 cells ATP, ADP, AMP, UTP, UDP, and UMP were hydrolyzed to the nucleosides adenosine and uridine indicating the presence of ecto-nucleotidases and ectophosphatases. The hydrolysis of the purine nucleotides ATP and ADP was significantly faster than the hydrolysis of the pyrimidine nucleotides UTP and UDP. 3. ATP and UTP breakdown appeared to be mainly due to an ecto-nucleotide-diphosphohydrolase. ADP, but not UDP, was initially also phosphorylated to some extent to the corresponding triphosphate, indicating the presence of an adenylate kinase on NG108-15 cells. The alkaline phosphatase (ALP) inhibitor levamisole did not only inhibit the hydrolysis of AMP to adenosine and of UMP to uridine, but also the degradation of ADP and to a larger extent that of UDP. ATP and UTP degradation was only slightly inhibited by levamisole. 4. These results underscore the important role of ecto-alkaline phosphatase in the metabolism of adenine as well as uracil nucleotides in NG108-15 cells Dipyridamole, a potent inhibitor of nucleotide breakdown in superior cervical ganglion cells, had no effect on nucleotide degradation in NG108-15 cells. 5. Dipyridamole, which is a therapeutically used nucleoside reuptake inhibitor in humans, reduced the extracellular adenosine accumulation possibly by allosteric enhancement of adenosine reuptake into the cells.
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Affiliation(s)
- Marko Kaulich
- Department of Pharmaceutical Chemistry Poppelsdorf, Pharmaceutical Institute, University of Bonn, Bonn, Germany
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Sak K, Webb TE. A retrospective of recombinant P2Y receptor subtypes and their pharmacology. Arch Biochem Biophys 2002; 397:131-6. [PMID: 11747319 DOI: 10.1006/abbi.2001.2616] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Since the first cloning of P2Y receptor sequences in 1993 it has become apparent that this family of G-protein-coupled receptors is omnipresent. At least 25 individual sequences entered in the GenBank sequence database encode P2Y receptors from a variety of species ranging from the little skate Raja erinacea to man. In man, six receptor subtypes have been cloned and found to be functionally active (P2Y(1), P2Y(2), P2Y(4), P2Y(6), P2Y(11), and P2Y(12)). In this article a review of the P2Y receptor subtypes is presented considering both their sequences and the pharmacological profiles of the encoded receptors expressed in heterologous expression systems.
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Affiliation(s)
- Katrin Sak
- Hematology-Oncology Clinic, Tartu University, Ulikooli 18, Tartu 50090, Estonia
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