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P2X. Br J Pharmacol 2009. [DOI: 10.1111/j.1476-5381.2009.00502_7.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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52
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LGIC. Br J Pharmacol 2009. [DOI: 10.1111/j.1476-5381.2009.00502.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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53
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Lee JY, Yu J, Cho WJ, Ko H, Kim YC. Synthesis and structure-activity relationships of pyrazolodiazepine derivatives as human P2X7 receptor antagonists. Bioorg Med Chem Lett 2009; 19:6053-8. [PMID: 19800793 DOI: 10.1016/j.bmcl.2009.09.053] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2009] [Revised: 09/09/2009] [Accepted: 09/12/2009] [Indexed: 10/20/2022]
Abstract
Screening of library compounds has yielded pyrazolodiazepine derivatives with P2X7 receptor antagonist activity. To explore the structure-activity relationships (SAR) of these pyrazolodiazepines as human P2X7 receptor antagonists, derivatives were synthesized by substitutions at positions R2 and R3 of the pyrazolodiazepine skeleton. Using a 2'(3')-O-(4-benzoylbenzoyl)ATP (BzATP)-induced fluorescent ethidium uptake assay, the activities of these derivatives were tested in HEK-293 cells stably expressing human P2X7 receptors. Moreover, the effect of these derivatives was assessed by measuring their effect on IL-1beta release induced by BzATP-induced activation of differentiated THP-1 cells. A 2-phenethyl pyrazolodiazepine derivative with a 1-methyl-1H-3-indolyl group at position R2 had fivefold greater activity than the derivative with a 5-isoquinolinyl at R2. Moreover, a benzyl moiety at R3 had fivefold greater activity than a bicyclic moiety. The stereochemical effect at C-6 showed a preference for the (R)-isomer. Among the series of active derivatives, compound 23b, with a phenethyl group at R1, a 3-methyl indole at R2, and a benzyl at R3, exhibited activity similar to that of the positive control, KN-62, as shown by the inhibitory effects of IL-1beta release.
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Affiliation(s)
- Ju-Yeon Lee
- Research Center for Biomolecular Nanotechnology, Department of Life Science, Gwangju Institute of Science & Technology, Gwangju, Republic of Korea
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Wareham K, Vial C, Wykes RCE, Bradding P, Seward EP. Functional evidence for the expression of P2X1, P2X4 and P2X7 receptors in human lung mast cells. Br J Pharmacol 2009; 157:1215-24. [PMID: 19552691 DOI: 10.1111/j.1476-5381.2009.00287.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE P2X receptors are widely expressed in cells of the immune system with varying functions. This study sought to characterize P2X receptor expression in the LAD2 human mast cell line and human lung mast cells (HLMCs). EXPERIMENTAL APPROACH Reverse transcriptase polymerase chain reaction (RT-PCR) and patch clamp studies were used to characterize P2X expression in mast cells using a range of pharmacological tools. KEY RESULTS RT-PCR revealed P2X1, P2X4 and P2X7 transcripts in both cell types; mRNA for P2X6 was also detected in LAD2 cells. Under whole-cell patch clamp conditions, rapid application of ATP (1-1000 microM) to cells clamped at -60 mV consistently evoked inward currents in both types of cells. Brief application of ATP (1 s) evoked a rapidly desensitizing P2X1-like current in both cell types. This current was also elicited by alphabetamethylene ATP (10 microM, 94% cells, n= 31) and was antagonized in LAD2 cells by NF 449 (1 microM) and pyridoxal phosphate-6-azo(benzene-2,4-disulphonic acid) (1-10 microM). A P2X7-like non-desensitizing current in response to high concentrations of ATP (1-5 mM) was also seen in both cell types (96% LAD2, n= 24; 54% HLMCs, n= 24) which was antagonized by AZ11645373 (1 microM). P2X7-like responses were also evoked in LAD2 cells by 2'(3')-0-(4-benzoylbenzoyl)ATP (300 microM). A P2X4-like current was evoked by 100 microM ATP (80% LAD2, n= 10; 21% HLMCs, n= 29), the amplitude and duration of which was potentiated by ivermectin (3 microM). CONCLUSION AND IMPLICATIONS Our data confirmed the presence of functional P2X1, P2X4 and P2X7 receptors in LAD2 cells and HLMCs.
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Affiliation(s)
- K Wareham
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield, UK
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55
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Donnelly-Roberts DL, Namovic MT, Han P, Jarvis MF. Mammalian P2X7 receptor pharmacology: comparison of recombinant mouse, rat and human P2X7 receptors. Br J Pharmacol 2009; 157:1203-14. [PMID: 19558545 DOI: 10.1111/j.1476-5381.2009.00233.x] [Citation(s) in RCA: 199] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND AND PURPOSE Acute activation of P2X7 receptors rapidly opens a non-selective cation channel. Sustained P2X7 receptor activation leads to the formation of cytolytic pores, mediated by downstream recruitment of hemichannels to the cell surface. Species- and single-nucleotide polymorphism-mediated differences in P2X7 receptor activation have been reported that complicate understanding of the physiological role of P2X7 receptors. Studies were conducted to determine pharmacological differences between human, rat and mouse P2X7 receptors. EXPERIMENTAL APPROACH Receptor-mediated changes in calcium influx and Yo-Pro uptake were compared between recombinant mouse, rat and human P2X7 receptors. For mouse P2X7 receptors, wild-type (BALB/c) and a reported loss of function (C57BL/6) P2X7 receptor were also compared. KEY RESULTS BzATP [2,3-O-(4-benzoylbenzoyl)-ATP] was more potent than ATP in stimulating calcium influx and Yo-Pro uptake at rat, human, BALB/c and C57BL/6 mouse P2X7 receptors. Two selective P2X7 receptor antagonists, A-740003 and A-438079, potently blocked P2X7 receptor activation across mammalian species. Several reported P2X1 receptor antagonists [e.g. MRS 2159 (4-[(4-formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl}-2-pyridinyl)azo]-benzoic acid), PPNDS and NF279] blocked P2X7 receptors. NF279 fully blocked human P2X7 receptors, but only partially blocked BALB/c P2X7 receptors and was inactive at C57BL/6 P2X7 receptors. CONCLUSIONS AND IMPLICATIONS These data provide new insights into P2X7 receptor antagonist pharmacology across mammalian species. P2X7 receptor pharmacology in a widely used knockout background mouse strain (C57BL/6) was similar to wild-type mouse P2X7 receptors. Several structurally novel, selective and competitive P2X7 receptor antagonists show less species differences compared with earlier non-selective antagonists.
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Affiliation(s)
- Diana L Donnelly-Roberts
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60024, USA
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56
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The P2X(7) receptor mediates the uptake of organic cations in canine erythrocytes and mononuclear leukocytes: comparison to equivalent human cell types. Purinergic Signal 2009; 5:385-94. [PMID: 19533417 DOI: 10.1007/s11302-009-9163-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 05/26/2009] [Indexed: 01/12/2023] Open
Abstract
We previously demonstrated that canine erythrocytes express the P2X(7) receptor, and that the function and expression of this receptor is greatly increased compared with human erythrocytes. Using (86)Rb(+) (K(+)) and organic cation flux measurements, we further compared P2X(7) in erythrocytes and mononuclear leukocytes from these species. Concentration response curves of BzATP- and ATP-induced (86)Rb(+) efflux demonstrated that canine P2X(7) was less sensitive to inhibition by extracellular Na(+) ions compared to human P2X(7). In contrast, canine and human P2X(7) showed a similar sensitivity to the P2X(7) antagonists KN-62 and Mg(2+). KN-62 and Mg(2+) also inhibited ATP-induced choline(+) uptake into canine and human erythrocytes. BzATP and ATP but not ADP or NAD induced ethidium(+) uptake into canine monocytes, T- and B-cells. ATP-induced ethidium(+) uptake was twofold greater in canine T-cells compared to canine B-cells and monocytes. KN-62 inhibited the ATP-induced ethidium(+) uptake in each cell type. P2X(7)-mediated uptake of organic cations was 40- and fivefold greater in canine erythrocytes and lymphocytes (T- and B-cells), respectively, compared to equivalent human cell types. In contrast, P2X(7) function was threefold lower in canine monocytes compared to human monocytes. Thus, P2X(7) activation can induce the uptake of organic cations into canine erythrocytes and mononuclear leukocytes, but the relative levels of P2X(7) function differ to that of equivalent human cell types.
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57
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Gu BJ, Rathsam C, Stokes L, McGeachie AB, Wiley JS. Extracellular ATP dissociates nonmuscle myosin from P2X(7) complex: this dissociation regulates P2X(7) pore formation. Am J Physiol Cell Physiol 2009; 297:C430-9. [PMID: 19494237 DOI: 10.1152/ajpcell.00079.2009] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The P2X(7) receptor is a ligand-gated cation channel that is highly expressed on monocyte-macrophages and that mediates the pro-inflammatory effects of extracellular ATP. Dilation of the P2X(7) channel and massive K(+) efflux follows initial channel opening, but the mechanism of secondary pore formation is unclear. The proteins associated with P2X(7) were isolated by using anti-P2X(7) monoclonal antibody-coated Dynabeads from both interferon-gamma plus LPS-stimulated monocytic THP-1 cells and P2X(7)-transfected HEK-293 cells. Two nonmuscle myosins, NMMHC-IIA and myosin Va, were found to associate with P2X(7) in THP-1 cells and HEK-293 cells, respectively. Activation of the P2X(7) receptor by ATP caused dissociation of P2X(7) from nonmuscle myosin in both cell types. The interaction of P2X(7) and NMMHC-IIA molecules was confirmed by fluorescent life time measurements and fluorescent resonance of energy transfer-based time-resolved flow cytometry assay. Reducing the expression of NMMHC-IIA or myosin Va by small interfering RNA or short hairpin RNA led to a significant increase of P2X(7) pore function without any increase in surface expression or ion channel function of P2X(7) receptors. S-l-blebbistatin, a specific inhibitor of NMMHC-IIA ATPase, inhibited both ATP-induced ethidium uptake and ATP-induced dissociation of P2X(7)-NMMHC-IIA complex. In both cell types nonmuscle myosin closely interacts with P2X(7) and is dissociated from the complex by extracellular ATP. Dissociation of this anchoring protein may be required for the transition of P2X(7) channel to a pore.
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Affiliation(s)
- Ben J Gu
- Department of Medicine, Nepean Clinical School, Penrith, NSW, Australia
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58
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Grahnert A, Klein C, Hauschildt S. Involvement of P2X receptors in the NAD(+)-induced rise in [Ca (2+)] (i) in human monocytes. Purinergic Signal 2009; 5:309-19. [PMID: 19221895 DOI: 10.1007/s11302-009-9144-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 01/27/2009] [Indexed: 01/06/2023] Open
Abstract
In the present study, we show that the extracellular addition of nicotinamide adenine dinucleotide (NAD(+)) induces a transient rise in [Ca(2+)](i) in human monocytes caused by an influx of extracellular calcium. The NAD(+)-induced Ca(2+) response was prevented by adenosine triphosphate (ATP), suggesting the involvement of ATP receptors. Of the two subtypes of ATP receptors (P2X and P2Y), the P2X receptors were considered the most likely candidates. By the use of subtype preferential agonists and antagonists, we identified P2X(1), P2X(4), and P2X(7) receptors being engaged in the NAD(+)-induced rise in [Ca(2+)](i). Among the P2X receptor subtypes, the P2X(7) receptor is unique in facilitating the induction of nonselective pores that allow entry of ethidium upon stimulation with ATP. In monocytes, opening of P2X(7) receptor-dependent pores strongly depends on specific ionic conditions. Measuring pore formation in response to NAD(+), we found that NAD(+) unlike ATP lacks the ability to induce this pore-forming response. Whereas as little as 100 muM ATP was sufficient to activate the nonselective pore, NAD(+) at concentrations up to 2 mM had no effect. Taken together, these data indicate that despite similarities in the action of extracellular NAD(+) and ATP there are nucleotide-specific variations. So far, common and distinct features of the two nucleotides are only beginning to be understood.
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Affiliation(s)
- Anja Grahnert
- Department of Immunobiology, Institute of Biology II, University of Leipzig, Talstrasse 33, 04103, Leipzig, Germany
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59
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Lee GE, Lee HS, Lee SD, Kim JH, Kim WK, Kim YC. Synthesis and structure-activity relationships of novel, substituted 5,6-dihydrodibenzo[a,g]quinolizinium P2X7 antagonists. Bioorg Med Chem Lett 2008; 19:954-8. [PMID: 19110420 DOI: 10.1016/j.bmcl.2008.11.088] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Revised: 11/18/2008] [Accepted: 11/24/2008] [Indexed: 01/16/2023]
Abstract
Iminium quaternary protoberberine alkaloids (QPA) have been found to be novel P2X(7) antagonists. To assess their structure-activity relationships, these compounds were modified at their R(1) and R(2) groups and assayed for their ability to inhibit the 2'(3')-O-(4-benzoylbenzoyl)-ATP (BzATP)-induced uptake of fluorescent ethidium by HEK-293 cells stably expressing the human P2X(7) receptor, and their ability to inhibit BzATP-induced IL-1beta release by differentiated THP-1 cells. Compounds 15a and 15d, with alkyl groups at the R(1) position, and especially compound 19h, with the 2-NO(2)-4,5-dimethoxy-benzyl group at the R(2) position, had potent inhibitory efficacy as P2X(7) antagonists.
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Affiliation(s)
- Ga Eun Lee
- Research Center for Biomolecular Nanotechnology, Department of Life Science, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712, South Korea
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60
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Michel AD, Clay WC, Ng SW, Roman S, Thompson K, Condreay JP, Hall M, Holbrook J, Livermore D, Senger S. Identification of regions of the P2X(7) receptor that contribute to human and rat species differences in antagonist effects. Br J Pharmacol 2008; 155:738-51. [PMID: 18660826 DOI: 10.1038/bjp.2008.306] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND AND PURPOSE Several P2X(7) receptor antagonists are allosteric inhibitors and exhibit species difference in potency. Furthermore, N(2)-(3,4-difluorophenyl)-N(1)-(2-methyl-5-(1-piperazinylmethyl)phenyl)glycinamide dihydrochloride (GW791343) exhibits negative allosteric effects at the human P2X(7) receptor but is a positive allosteric modulator of the rat P2X(7) receptor. In this study we have identified several regions of the P2X(7) receptor that contribute to the species differences in antagonist effects. EXPERIMENTAL APPROACH Chimeric human-rat P2X(7) receptors were constructed with regions of the rat receptor being inserted into the human receptor. Antagonist effects at these receptors were measured in ethidium accumulation and radioligand binding studies. KEY RESULTS Exchanging regions of the P2X(7) receptor close to transmembrane domain 1 modified the effects of KN62, 4-(4-fluorophenyl)-2-(4-methylsulphinylphenyl)-5-(4-pyridyl)1H-imidazole (SB203580) and GW791343. Further studies, in which single amino acids were exchanged, identified amino acid 95 as being primarily responsible for the differential allosteric effects of GW791343 and, to varying degrees, the species differences in potency of SB203580 and KN62. The species selectivity of pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid was affected by multiple regions of the receptor, with potency being particularly affected by the amino acid 126 but not by amino acid 95. A further region of the rat receptor (amino acids 154-183) was identified that, when inserted into the corresponding position in the human receptor, increased ATP potency 10-fold. CONCLUSIONS This study has identified several key residues responsible for the species differences in antagonist effects at the P2X(7) receptor and also identified a further region of the P2X(7) receptor that can significantly affect agonist potency at the P2X(7) receptor.
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Affiliation(s)
- A D Michel
- Neurology Centre of Excellence for Drug Discovery, GlaxoSmithKline Research & Development Limited, New Frontiers Science Park, Harlow, Essex, UK.
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Romagnoli R, Baraldi PG, Cruz-Lopez O, Lopez-Cara C, Preti D, Borea PA, Gessi S. The P2X7 receptor as a therapeutic target. Expert Opin Ther Targets 2008; 12:647-61. [PMID: 18410246 DOI: 10.1517/14728222.12.5.647] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND The P2X7 receptor is present in a variety of cell types involved in pain, inflammatory processes and neurodegenerative conditions, thus it may be an appealing target for pharmacological intervention. The extensive use of high-throughput screening (HTS) followed by a hit-to-lead (HtL) program, has prompted a number of firms to identify highly selective and metabolically stable small-molecules possessing activity for both the rat and human P2X(7) receptor, which provide a novel therapeutic approach to the treatment of pain as well as neurodegenerative and inflammatory disorders. OBJECTIVE To describe the current status of and potential for development of P2X(7) receptor-antagonists. METHODS A literature review. RESULTS/CONCLUSIONS We describe the recent discoveries of novel P2X(7) receptor-selective antagonists, along with their biological activity and therapeutic potential.
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Affiliation(s)
- Romeo Romagnoli
- Università di Ferrara, Dipartimento di Scienze Farmaceutiche, Via Fossato di Mortara 17-19, 44100 Ferrara, Italy.
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Lajdova I, Chorvat D, Chorvatova A. Rapid effects of 1alpha,25(OH)2D3 in resting human peripheral blood mononuclear cells. Eur J Pharmacol 2008; 586:14-23. [PMID: 18353308 DOI: 10.1016/j.ejphar.2008.02.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 01/25/2008] [Accepted: 02/06/2008] [Indexed: 11/18/2022]
Abstract
The steroid hormone 1alpha,25(OH)2D3 produces biological responses via both genomic and nongenomic mechanisms. Stimulation of rapid, nongenomic responses by 1alpha,25(OH)2D3 has been postulated to result from interaction of the ligand with cell membrane 1alpha,25(OH)2D3 receptors and to involve membrane receptors. We examined the rapid effects of 1alpha,25(OH)2D3 on calcium mobilization and calcium entry into resting human peripheral blood mononuclear cells isolated from healthy volunteers. We also investigated the possible involvement of purinergic receptors in this action. 1alpha,25(OH)2D3 induced a time-dependent increase in intracellular calcium concentration ([Ca2+]i). The initial 1alpha,25(OH)2D3-stimulated calcium increment was sensitive to thapsigargin (Tg), indicating its origins in calcium release from intracellular stores. 2-Aminoethyldiphenyl borate (2APB), an inhibitor of capacitative calcium entry, caused a significant [Ca2+]i decrease in human cells treated with 1alpha,25(OH)2D3. Furthermore, in contrast to observations in osteoblasts and skeletal muscle cells, nifedipine had no effect on 1alpha,25(OH)2D3-induced calcium entry, suggesting that L-type calcium channels were not implicated in this action. Besides, 1alpha,25(OH)(2)D3 prevented the calcium entry induced by 3'-O-(4-benzoyl)benzoyl-adenosine 5'-triphosphate (BzATP), a specific agonist of purinergic P2X7 receptors. This finding was further confirmed by 1alpha,25(OH)2D3-induced reduction of BzATP- and 4-aminopyridine (4AP)-stimulated ethidium bromide fluorescence. The presented results demonstrate, for the first time in healthy, resting human peripheral blood mononuclear cells that 1alpha,25(OH)2D3 is capable of exerting a rapid, nongenomic effect on [Ca2+]i, while inhibiting of the P2X7 channel permeability.
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León D, Sánchez-Nogueiro J, Marín-García P, Miras-Portugal MAT. Glutamate release and synapsin-I phosphorylation induced by P2X7 receptors activation in cerebellar granule neurons. Neurochem Int 2007; 52:1148-59. [PMID: 18242779 DOI: 10.1016/j.neuint.2007.12.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2007] [Revised: 11/30/2007] [Accepted: 12/07/2007] [Indexed: 10/22/2022]
Abstract
The present work reports that activation of P2X7 receptor induces synaptic vesicle release in granule neurons and phosphorylation of synapsin-I by calcium-calmodulin-dependent protein kinase II (CaMKII), which in turn modulates secretory event. ATP, in absence of magnesium, induced a concentration-dependent glutamate release with an EC50 value of 1.95 microM. The involvement of P2X7 receptor was suggested when maximal secretory response was significantly reduced by the selective P2X7 antagonist Brilliant Blue G (BBG; 100 nM) and abolished by removing extracellular Ca2+. The involvement of P2X7 receptor on synaptic vesicle release was confirmed by measuring the release of FM 1-43 dye. In this case, pharmacological activation of P2X7 was achieved with the more selective agonist 2'-3'-o-(4-benzoylbenzoyl)-adenosine 5'-triphosphate (BzATP; 100 microM) showing a significant FM 1-43 release that was blocked by BBG (100 nM), by Zn2+ ions (100 microM), both P2X7 blockers, but not by suramin (100 microM), antagonist of P2X1, P2X2, P2X3 and P2X5. In addition, BzATP, through P2X7 receptor activation, significantly increased the phosphorylation of synapsin-I, the main presynaptic target of CaMKII. Both effects mediated by BzATP were inhibited by the CaMKII inhibitors KN-62 (10 microM) and KN-93 (10 microM). These results suggest, therefore, that Ca2+ entrance mediated by P2X7 receptor induces glutamate release and in parallel synapsin-I phosphorylation.
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Affiliation(s)
- David León
- Department of Biochemistry, Veterinary Faculty, Universidad Complutense de Madrid, Avda. Puerta de Hierro s/n, 28040 Madrid, Spain
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64
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Michel AD, Chambers LJ, Walter DS. Negative and positive allosteric modulators of the P2X(7) receptor. Br J Pharmacol 2007; 153:737-50. [PMID: 18071294 DOI: 10.1038/sj.bjp.0707625] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND AND PURPOSE Antagonist effects at the P2X(7) receptor are complex with many behaving in a non-competitive manner. In this study, the effects of N-[2-({2-[(2-hydroxyethyl)amino]ethyl}amino)-5-quinolinyl]-2-tricyclo[3.3.1.1(3,7)]dec-1-ylacetamide (compound-17) and N (2)-(3,4-difluorophenyl)-N (1)-[2-methyl-5-(1-piperazinylmethyl)phenyl]glycinamide dihydrochloride (GW791343) on P2X(7) receptors were examined and their mechanism of action explored. EXPERIMENTAL APPROACH Antagonist effects were studied by measuring agonist-stimulated ethidium accumulation in cells expressing human or rat recombinant P2X(7) receptors and in radioligand binding studies. KEY RESULTS Compound-17 and GW791343 were non-competitive inhibitors of human P2X(7) receptors. Receptor protection studies using decavanadate and pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) showed that neither compound-17 nor GW791343 competitively interacted at the ATP binding site and so were probably negative allosteric modulators of the P2X(7) receptor. GW791343 prevented the slowly reversible blockade of the human P2X(7) receptor produced by compound-17 and inhibited [(3)H]-compound-17 binding to the P2X(7) receptor suggesting they may bind to similar or interacting sites. At rat P2X(7) receptors, compound-17 was a negative allosteric modulator but the predominant effect of GW791343 was to increase agonist responses. Antagonist interaction and radioligand binding studies revealed that GW791343 did not interact at the ATP binding site but did interact with the compound-17 binding site suggesting that GW791343 is a positive allosteric modulator of the rat P2X(7) receptor. CONCLUSIONS Compound-17 was a negative allosteric modulator of human and rat P2X(7) receptors. GW791343 was a negative allosteric modulator of the human P2X(7) receptor but at the rat P2X(7) receptor its predominant effect was positive allosteric modulation. These compounds should provide valuable tools for mechanistic studies on P2X(7) receptors.
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Affiliation(s)
- A D Michel
- Neurology Centre of Excellence for Drug Discovery, GlaxoSmithKline Research & Development Limited, Harlow, Essex, UK.
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Shemon AN, Sluyter R, Stokes L, Manley PW, Wiley JS. Inhibition of the human P2X7 receptor by a novel protein tyrosine kinase antagonist. Biochem Biophys Res Commun 2007; 365:515-20. [PMID: 17999916 DOI: 10.1016/j.bbrc.2007.11.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Accepted: 11/02/2007] [Indexed: 10/22/2022]
Abstract
A panel of 18 protein tyrosine kinase antagonists were tested for their inhibitory effect on human P2X(7) receptor-mediated (86)Rb(+) (K(+)) efflux. The most potent compound (compound P), a phthalazinamine derivative and an inhibitor of vascular endothelial growth factor receptor kinase, blocked ATP-induced (86)Rb(+)-efflux in human B-lymphocytes and erythrocytes by 76% and 66%, respectively. This inhibition was dose-dependent in both cell types with an IC(50) of approximately 5muM. Kinetic analysis showed compound P was a non-competitive inhibitor of P2X(7). This compound also inhibited ATP-induced ethidium(+) influx into B-lymphocytes and P2X(7)-transfected-HEK-293 cells, as well as ATP-induced (86)Rb(+)-efflux from canine erythrocytes. Externally, but not internally, applied compound P impaired ATP-induced inward currents in P2X(7)-transfected-HEK-293 cells. This study demonstrates that a novel protein tyrosine kinase antagonist directly impairs native and recombinant human P2X(7) receptors. The data suggests that antagonists which target ATP-binding sites of kinases may potentially block the P2X(7) receptor.
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Affiliation(s)
- Anne N Shemon
- Department of Medicine, Nepean Clinical School, University of Sydney, Penrith, NSW, Australia
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Furber M, Alcaraz L, Bent JE, Beyerbach A, Bowers K, Braddock M, Caffrey MV, Cladingboel D, Collington J, Donald DK, Fagura M, Ince F, Kinchin EC, Laurent C, Lawson M, Luker TJ, Mortimore MMP, Pimm AD, Riley RJ, Roberts N, Robertson M, Theaker J, Thorne PV, Weaver R, Webborn P, Willis P. Discovery of Potent and Selective Adamantane-Based Small-Molecule P2X7Receptor Antagonists/Interleukin-1β Inhibitors. J Med Chem 2007; 50:5882-5. [DOI: 10.1021/jm700949w] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sluyter R, Shemon AN, Hughes WE, Stevenson RO, Georgiou JG, Eslick GD, Taylor RM, Wiley JS. Canine erythrocytes express the P2X7 receptor: greatly increased function compared with human erythrocytes. Am J Physiol Regul Integr Comp Physiol 2007; 293:R2090-8. [PMID: 17761513 DOI: 10.1152/ajpregu.00166.2007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Over three decades ago, Parker and Snow (Am J Physiol 223: 888-893, 1972) demonstrated that canine erythrocytes undergo an increase in cation permeability when incubated with extracellular ATP. In this study we examined the expression and function of the channel/pore-forming P2X(7) receptor on canine erythrocytes. P2X(7) receptors were detected on canine erythrocytes by immunocytochemistry and immunoblotting. Extracellular ATP induced (86)Rb(+) (K(+)) efflux from canine erythrocytes that was 20 times greater than that from human erythrocytes. The P2X(7) agonist 2'(3')-O-(4-benzoylbenzoyl)adenosine 5'-trisphosphate (BzATP) was more potent than ATP, and both stimulated (86)Rb(+) efflux from erythrocytes in a dose-dependent fashion with EC(50) values of approximately 7 and approximately 309 microM, respectively. 2-Methylthioadenosine 5'-triphosphate and adenosine 5'-O-(3-thiotriphosphate) induced a smaller (86)Rb(+) efflux from erythrocytes, whereas ADP, AMP, UTP, or adenosine had no effect. ATP-induced (86)Rb(+) efflux from erythrocytes was inhibited by oxidized ATP, KN-62, and Brilliant blue G, known P2X(7) antagonists. ATP also induced uptake of choline(+) into canine erythrocytes that was 60 times greater than that into human erythrocytes. Overnight incubation of canine erythrocytes with ATP and BzATP induced phosphatidylserine exposure in >80% of cells and caused up to 20% hemolysis. In contrast, <30% of human erythrocytes showed phosphatidylserine exposure after overnight incubation with ATP and BzATP, and hemolysis was negligible. Flow cytometric measurements of ATP-induced ethidium(+) uptake showed that P2X(7) function was three times lower in canine monocytes than in human monocytes. These data show that the massive cation permeability increase induced by extracellular ATP in canine erythrocytes results from activation and opening of the P2X(7) receptor channel/pore.
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Affiliation(s)
- Ronald Sluyter
- Dept. of Medicine, University of Sydney, Nepean Clinical School, Penrith, New South Wales, Australia.
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68
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Jursik C, Sluyter R, Georgiou JG, Fuller SJ, Wiley JS, Gu BJ. A quantitative method for routine measurement of cell surface P2X7 receptor function in leucocyte subsets by two-colour time-resolved flow cytometry. J Immunol Methods 2007; 325:67-77. [PMID: 17618646 DOI: 10.1016/j.jim.2007.06.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2007] [Revised: 05/30/2007] [Accepted: 06/01/2007] [Indexed: 12/18/2022]
Abstract
The P2X(7) receptor is a ligand-gated cation channel activated by extracellular ATP and highly expressed on monocytes, macrophages and lymphocytes. Activation of this receptor by exposure to extracellular ATP opens a selective cation channel that allows Ca(2+) and Ba(2+) influx, and K(+) efflux. Over the first minute the channel adopts a second and larger permeability state allowing the uptake of ethidium(+), followed by a cascade of intracellular downstream effects. Current methods used to study the P2X(7) receptor function, do not give quantitative measurement in sub-populations of a mixed cell suspension. We describe a quantitative method to determine the P2X(7) receptor function using time-resolved two-colour flow cytometry by assessing ATP-induced ethidium(+) uptake. Practical factors such as ethidium bromide concentration, agonists, temperature and buffers are also studied. Moreover, the ATP-induced ethidium(+) uptake method is compared to ATP induced barium (Ba(2+)) influx with Fura-Red. These two compatible methods can be used to screen the channel/pore function of the cell surface P2X(7) receptor among individuals and the results may be useful to estimate susceptibility of subjects to certain infectious diseases.
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Affiliation(s)
- Claudia Jursik
- Department of Medicine, the University of Sydney, Nepean Hospital, Penrith, New South Wales 2750, Australia
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69
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Romagnoli R, Baraldi PG, Carrion MD, Cara CL, Preti D, Cruz-Lopez O, Tabrizi MA, Moorman AR, Gessi S, Fogli E, Sacchetto V, Borea PA. From tyrosine to glycine: synthesis and biological activity of potent antagonists of the purinergic P2X7 receptor. J Med Chem 2007; 50:3706-15. [PMID: 17585854 DOI: 10.1021/jm070443e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The characterization of the native and recombinant P2X7 receptor continues to be hindered by the lack of specific and subtype-selective antagonists with a "druglike" profile. However, a tyrosine derivative named KN-62 exhibits selective P2X7 receptor-blocking properties. As a molecular simplification of KN-62, the present study was designed to evaluate the functional antagonistic properties of a novel series of glycine derivatives characterized by the presence of different phenyl-substituted piperazine moieties. Antagonistic activity of these glycine derivatives was tested on HEK293 cells transfected with the human P2X7 receptor. The most potent P2X7 receptor antagonist identified in this study (compound 4g) contains an o-fluorine substituent on the phenylpiperazine moiety and had an IC50 of 12.1 nM. The biological responses investigated were ATP-dependent Ca2+ influx across the plasma membrane and ethidium bromide uptake.
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Affiliation(s)
- Romeo Romagnoli
- Dipartimento di Scienze Farmaceutiche, Università di Ferrara, Ferrara, Italy.
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70
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Donnelly-Roberts DL, Jarvis MF. Discovery of P2X7 receptor-selective antagonists offers new insights into P2X7 receptor function and indicates a role in chronic pain states. Br J Pharmacol 2007; 151:571-9. [PMID: 17471177 PMCID: PMC2013998 DOI: 10.1038/sj.bjp.0707265] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
ATP-sensitive P2X(7) receptors are localized on cells of immunological origin including peripheral macrophages and glial cells in the CNS. Activation of P2X(7) receptors leads to rapid changes in intracellular calcium concentrations, release of the proinflammatory cytokine interleukin-1beta and following prolonged agonist exposure, the formation of cytolytic pores in plasma membranes. Both the localization and functional consequences of P2X(7) receptor activation indicate a role in inflammatory processes. The phenotype of P2X(7) receptor gene-disrupted mice also indicates that P2X(7) receptor activation contributes to ongoing inflammation. More recently, P2X(7) receptor knockout data has also suggested a specific role in inflammatory and neuropathic pain states. The recent discovery of potent and highly selective antagonists for P2X(7) receptors has helped to further clarify P2X receptor pharmacology, expanded understanding of P2X(7) receptor signaling, and offers new evidence that P2X(7) receptors play a specific role in nociceptive signaling in chronic pain states. In this review, we incorporate the recent discoveries of novel P2X(7) receptor-selective antagonists with a brief update on P2X(7) receptor pharmacology and its therapeutic potential.
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Affiliation(s)
- D L Donnelly-Roberts
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories Abbott Park, IL, USA
| | - M F Jarvis
- Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories Abbott Park, IL, USA
- Author for correspondence:
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71
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Carroll WA, Kalvin DM, Perez Medrano A, Florjancic AS, Wang Y, Donnelly-Roberts DL, Namovic MT, Grayson G, Honoré P, Jarvis MF. Novel and potent 3-(2,3-dichlorophenyl)-4-(benzyl)-4H-1,2,4-triazole P2X7 antagonists. Bioorg Med Chem Lett 2007; 17:4044-8. [PMID: 17482819 DOI: 10.1016/j.bmcl.2007.04.075] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Revised: 04/23/2007] [Accepted: 04/23/2007] [Indexed: 10/23/2022]
Abstract
Structure-activity relationship (SAR) studies were conducted around early tetrazole-based leads 3 and 4. Replacements for the tetrazole core were investigated and the pendant benzyl substitution was reoptimized with a triazole isostere. Triazole-based P2X(7) antagonists were identified with similar potency to the lead compound 4 but with improved physiochemical properties. Compound 12 was active in a rat model of neuropathic pain.
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Affiliation(s)
- William A Carroll
- Abbott Laboratories, Neuroscience Research, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
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72
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Michel AD, Chambers LJ, Clay WC, Condreay JP, Walter DS, Chessell IP. Direct labelling of the human P2X7 receptor and identification of positive and negative cooperativity of binding. Br J Pharmacol 2007; 151:103-14. [PMID: 17339830 PMCID: PMC2012979 DOI: 10.1038/sj.bjp.0707196] [Citation(s) in RCA: 53] [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
BACKGROUND AND PURPOSE The P2X(7) receptor exhibits complex pharmacological properties. In this study, binding of a [(3)H]-labelled P2X(7) receptor antagonist to human P2X(7) receptors has been examined to further understand ligand interactions with this receptor. EXPERIMENTAL APPROACH The P2X(7) receptor antagonist, N-[2-({2-[(2-hydroxyethyl)amino]ethyl}amino)-5-quinolinyl]-2-tricyclo[3.3.1.1(3,7)]dec-1-ylacetamide (compound-17), was radiolabelled with tritium and binding studies were performed using membranes prepared from U-2 OS or HEK293 cells expressing human recombinant P2X(7) receptors. KEY RESULTS Binding of [(3)H]-compound-17 was higher in membranes prepared from cells expressing P2X(7) receptors than from control cells and was inhibited by ATP suggesting labelled sites represented human P2X(7) receptors. Binding was reversible, saturable and modulated by P2X(7) receptor ligands (Brilliant Blue G, KN62, ATP, decavanadate). Furthermore, ATP potency was reduced in the presence of divalent cations or NaCl. Radioligand binding exhibited both positive and negative cooperativity. Positive cooperativity was evident from bell shaped Scatchard plots, reduction in radioligand dissociation rate by unlabelled compound-17 and enhancement of radioligand binding by KN62 and unlabelled compound-17. ATP and decavanadate inhibited binding in a negative cooperative manner as they enhanced radioligand dissociation. CONCLUSIONS These data demonstrate that human P2X(7) receptors can be directly labelled and provide novel insights into receptor function. The positive cooperativity observed suggests that binding of compound-17 to one subunit in the P2X(7) receptor complex enhances subsequent binding to other P2X(7) subunits in the same complex. The negative cooperative effects of ATP suggest that ATP and compound-17 bind at separate, interacting, sites on the P2X(7) receptor.
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Affiliation(s)
- A D Michel
- Neurology & GI Centre of Excellence for Drug Discovery, GlaxoSmithKline Research and Development Limited, Harlow, Essex, UK.
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73
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Armstrong S, Korcok J, Sims SM, Dixon SJ. Activation of transcription factors by extracellular nucleotides in immune and related cell types. Purinergic Signal 2007; 3:59-69. [PMID: 18404419 PMCID: PMC2096760 DOI: 10.1007/s11302-006-9037-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2006] [Accepted: 03/13/2006] [Indexed: 01/18/2023] Open
Abstract
Extracellular nucleotides, acting through P2 receptors, can regulate gene expression via intracellular signaling pathways that control the activity of transcription factors. Relatively little is known about the activation of transcription factors by nucleotides in immune cells. The NF-kappaB family of transcription factors is critical for many immune and inflammatory responses. Nucleotides released from damaged or stressed cells can act alone through certain P2 receptors to alter NF-kappaB activity or they can enhance responses induced by pathogen-associated molecules such as LPS. Nucleotides have also been shown to regulate the activity of other transcription factors (AP-1, NFAT, CREB and STAT) in immune and related cell types. Here, we provide an overview of transcription factors shown to be activated by nucleotides in immune cells, and describe what is known about their mechanisms of activation and potential functions. Furthermore, we propose areas for future work in this new and expanding field.
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Affiliation(s)
- Souzan Armstrong
- CIHR Group in Skeletal Development and Remodeling, Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON Canada N6A 5C1
| | - Jasminka Korcok
- CIHR Group in Skeletal Development and Remodeling, Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON Canada N6A 5C1
| | - Stephen M. Sims
- CIHR Group in Skeletal Development and Remodeling, Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON Canada N6A 5C1
| | - S. Jeffrey Dixon
- CIHR Group in Skeletal Development and Remodeling, Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, The University of Western Ontario, London, ON Canada N6A 5C1
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74
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Shemon AN, Sluyter R, Wiley JS. Rottlerin inhibits P2X(7) receptor-stimulated phospholipase D activity in chronic lymphocytic leukaemia B-lymphocytes. Immunol Cell Biol 2006; 85:68-72. [PMID: 17130901 DOI: 10.1038/sj.icb.7100005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Phospholipase D (PLD) is a ubiquitous enzyme that can be activated by extracellular adenosine 5'-triphosphate (ATP) or phorbol 12-myristate 13-acetate (PMA) in B-lymphocytes from subjects with chronic lymphocytic leukaemia (CLL). In this study, ATP- but not PMA-induced PLD stimulation in CLL B-lymphocytes was abolished in the presence of an anti-P2X(7) receptor monoclonal antibody, as well as in B-lymphocytes from CLL subjects homozygous for the Glu(496) to Ala loss-of-function P2X(7) polymorphism. Rottlerin, an inhibitor of novel protein kinase C (PKC) isoforms, but not GF 109203X, an inhibitor of conventional PKC isoforms, impaired the ATP-stimulated PLD activity in CLL B-lymphocytes. In contrast, both inhibitors impaired PLD activity stimulated by PMA, a known mediator of PKC activation. The inhibition of P2X(7)-stimulated PLD activity by rottlerin was attributed to a target downstream of P2X(7) activation, as the ATP-mediated (86)Rb(+) efflux from CLL B-lymphocytes was not altered in the presence of rottlerin. Our results indicate a possible role for novel PKC isoforms in the regulation of P2X(7)-mediated PLD activity.
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MESH Headings
- Acetophenones/pharmacology
- Adenosine Triphosphate/pharmacology
- B-Lymphocytes/drug effects
- B-Lymphocytes/enzymology
- Benzopyrans/pharmacology
- Cell Line, Tumor
- Dose-Response Relationship, Drug
- Gene Expression Regulation, Enzymologic
- Gene Expression Regulation, Leukemic
- Humans
- Leukemia, Lymphocytic, Chronic, B-Cell/enzymology
- Phospholipase D/metabolism
- Polymorphism, Genetic
- Protein Isoforms/antagonists & inhibitors
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/genetics
- Protein Kinase C/metabolism
- Receptors, Purinergic P2/metabolism
- Receptors, Purinergic P2X7
- Rubidium/metabolism
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Affiliation(s)
- Anne N Shemon
- Department of Medicine, University of Sydney at Nepean Hospital, Penrith, New South Wales, Australia
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75
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Abstract
Among seven members of P2X ionotropic receptors activated by extracellular ATP, the P2X(7) subtype is unique in that it can function as a cation channel, a nonselective pore, or even a signaling complex coupled with multiple downstream components. Several roles of P2X(7) receptors have been described in CNS cells in the past decade, including release of cytokines and transmitters, modulation of presynaptic transmitter release, and activation of multiple signaling pathways. The finding that P2X(7) pores may directly mediate efflux of cytosolic glutamate, GABA, and ATP in glial cells is particularly interesting, as it provides a novel mechanism of glial transmitter release that may play important roles not only in physiological intercellular communication but also in pathological neural injury.
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Affiliation(s)
- Shumin Duan
- Institute of Neuroscience and Key Laboratory of Neurobiology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Joseph T Neary
- Research Service, Miami VA Medical Center, Departments of Pathology, Biochemistry and Molecular Biology, and Neuroscience Program, University of Miami School of Medicine, Miami, Florida
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76
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Pastore S, Mascia F, Gulinelli S, Forchap S, Dattilo C, Adinolfi E, Girolomoni G, Di Virgilio F, Ferrari D. Stimulation of purinergic receptors modulates chemokine expression in human keratinocytes. J Invest Dermatol 2006; 127:660-7. [PMID: 17039239 DOI: 10.1038/sj.jid.5700591] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
ATP is abundantly released from stressed or damaged cells in response to mechanical stimulation, bacteria, or noxious agents. In this study, we have investigated the possible involvement of P2 receptors (receptor for extracellular nucleotides) in the expression and release of inflammatory mediators by human keratinocytes. Notably, extracellular ATP displayed a complex regulation of IFN-gamma-stimulated chemokine expression, with upregulation of CC chemokine ligand 2 (CCL2), CCL5 and CXC chemokine ligand 8 (CXCL8), and suppression of the receptor CXC chemokine receptor 3 (CXCR3), CXCL9, CXCL10, and CXCL11. The effect of ATP was mimicked by ADP and adenosine-5'-O-3-thiotriphosphate, whereas 2',3'-O-(4-benzoylbenzoyl) ATP (BzATP) downmodulated all chemokines investigated. UTP had no effect on IFN-gamma-stimulated chemokine secretion. The broad-spectrum P2 receptor antagonist suramin and the selective P2Y1 inhibitor adenosine 3'-phosphate 5'-phosphosulfate counteracted the effect of ATP on secretion of all the chemokines examined, whereas pyridoxal phosphate 6-azophenyl 2',4'-disulfonic acid and KN62 (1-[N,O-bis(5-isoquinoline sulfonyl)-N-methyl-L-tyrosyl] 4 phenylpiperazine) partially prevented the inhibitory effect of ATP on CXCL10 secretion, but on the other hand potentiated the ATP-stimulatory effect on CCL5, CCL2, and CXCL8 release. In lesional skin of psoriasis and atopic dermatitis patients, intense P2X7 reactivity was confined to the cell membrane of the basal layer, whereas diffuse P2Y1 immunostaining was found throughout the epidermis. Collectively, our data suggest that the orchestrated activation of distinct P2Y and P2X receptors modulates skin inflammation.
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Affiliation(s)
- Saveria Pastore
- Laboratory of Tissue Engineering and Cutaneous Physiopathology, Istituto Dermopatico dell'Immacolata, IRCCS, Roma, Italy
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77
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Inoue K, Hosoi J, Denda M. Extracellular ATP has stimulatory effects on the expression and release of IL-6 via purinergic receptors in normal human epidermal keratinocytes. J Invest Dermatol 2006; 127:362-71. [PMID: 16946718 DOI: 10.1038/sj.jid.5700526] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Extracellular ATP regulates proliferation and differentiation, functioning as an important messenger via purinergic (P2) receptors in keratinocytes. In this study, we investigated the effects of ATP on cytokine production in cultured normal human epidermal keratinocytes (NHEKs). Adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS), adenosine 5'-O-2-(thio)diphosphate (ADPbetaS), ADP, ATP, and 2', 3'-O-(4-benzoyl-benzoyl) ATP (BzATP) significantly increased the release of IL-6. The P2 antagonists, suramin-, reactive blue 2-, and periodate-oxidized ATP, inhibited ATP-induced IL-6 release, whereas pyridoxal-phosphate-6-azophenyl-2',4'-disulfonic acid, adenosine 3'-phosphate 5'-phosphate, 1-[N,O-bis(1,5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine, and pertussis toxin did not. SQ22563, an adenylate cyclase inhibitor, inhibited ATP-induced IL-6 release. ATPgammaS, ADPbetaS, ATP, and BzATP significantly increased the intracellular cAMP content. Reverse transcription-PCR showed expression of P2Y1, P2Y2, P2Y4, P2Y11, P2Y12, P2Y13, P2X1, P2X4, P2X5, P2X6, and P2X7 receptor subtypes. Additionally, UVB radiation evoked the release of ATP from NHEKs. The release of IL-6 and the expression of IL-6 mRNA were increased after UVB radiation, and these increases were also inhibited by P2 receptor antagonists. These results suggest that cAMP-generating P2Y receptors are likely functional in ATP-induced IL-6 production in NHEKs. Furthermore, in UVB-radiated cells, we note the possibility that P2 receptor antagonists may reduce skin inflammation.
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Affiliation(s)
- Kaori Inoue
- Shiseido Research Center, Kanazawa-ku, Yokohama, Japan.
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78
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Nelson DW, Gregg RJ, Kort ME, Perez-Medrano A, Voight EA, Wang Y, Grayson G, Namovic MT, Donnelly-Roberts DL, Niforatos W, Honore P, Jarvis MF, Faltynek CR, Carroll WA. Structure-activity relationship studies on a series of novel, substituted 1-benzyl-5-phenyltetrazole P2X7 antagonists. J Med Chem 2006; 49:3659-66. [PMID: 16759108 DOI: 10.1021/jm051202e] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1-Benzyl-5-aryltetrazoles were discovered to be novel antagonists for the P2X(7) receptor. Structure-activity relationship (SAR) studies were conducted around both the benzyl and phenyl moieties. In addition, the importance of the regiochemical substitution on the tetrazole was examined. Compounds were evaluated for activity to inhibit calcium flux in both human and rat recombinant P2X(7) cell lines using fluorometric imaging plate reader technology. Analogues were also assayed for their ability to inhibit IL-1beta release and to inhibit P2X(7)-mediated pore formation in human THP-1 cells. Compound 15d was advanced to efficacy studies in a model of neuropathic pain where significant reversal of mechanical allodynia was observed at doses that did not affect motor coordination.
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Affiliation(s)
- Derek W Nelson
- Abbott Laboratories, Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Park, Illinois 60064-6101, USA.
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79
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Bours MJL, Swennen ELR, Di Virgilio F, Cronstein BN, Dagnelie PC. Adenosine 5'-triphosphate and adenosine as endogenous signaling molecules in immunity and inflammation. Pharmacol Ther 2006; 112:358-404. [PMID: 16784779 DOI: 10.1016/j.pharmthera.2005.04.013] [Citation(s) in RCA: 775] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Accepted: 04/20/2005] [Indexed: 02/07/2023]
Abstract
Human health is under constant threat of a wide variety of dangers, both self and nonself. The immune system is occupied with protecting the host against such dangers in order to preserve human health. For that purpose, the immune system is equipped with a diverse array of both cellular and non-cellular effectors that are in continuous communication with each other. The naturally occurring nucleotide adenosine 5'-triphosphate (ATP) and its metabolite adenosine (Ado) probably constitute an intrinsic part of this extensive immunological network through purinergic signaling by their cognate receptors, which are widely expressed throughout the body. This review provides a thorough overview of the effects of ATP and Ado on major immune cell types. The overwhelming evidence indicates that ATP and Ado are important endogenous signaling molecules in immunity and inflammation. Although the role of ATP and Ado during the course of inflammatory and immune responses in vivo appears to be extremely complex, we propose that their immunological role is both interdependent and multifaceted, meaning that the nature of their effects may shift from immunostimulatory to immunoregulatory or vice versa depending on extracellular concentrations as well as on expression patterns of purinergic receptors and ecto-enzymes. Purinergic signaling thus contributes to the fine-tuning of inflammatory and immune responses in such a way that the danger to the host is eliminated efficiently with minimal damage to healthy tissues.
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Affiliation(s)
- M J L Bours
- Maastricht University, Department of Epidemiology, Nutrition and Toxicology Research Institute Maastricht, P.O. Box 616, 6200 MD Maastricht, The Netherlands.
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80
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Gever JR, Cockayne DA, Dillon MP, Burnstock G, Ford APDW. Pharmacology of P2X channels. Pflugers Arch 2006; 452:513-37. [PMID: 16649055 DOI: 10.1007/s00424-006-0070-9] [Citation(s) in RCA: 237] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2006] [Accepted: 03/08/2006] [Indexed: 02/07/2023]
Abstract
Significant progress in understanding the pharmacological characteristics and physiological importance of homomeric and heteromeric P2X channels has been achieved in recent years. P2X channels, gated by ATP and most likely trimerically assembled from seven known P2X subunits, are present in a broad distribution of tissues and are thought to play an important role in a variety of physiological functions, including peripheral and central neuronal transmission, smooth muscle contraction, and inflammation. The known homomeric and heteromeric P2X channels can be distinguished from each other on the basis of pharmacological differences when expressed recombinantly in cell lines, but whether this pharmacological classification holds true in native cells and in vivo is less well-established. Nevertheless, several potent and selective P2X antagonists have been discovered in recent years and shown to be efficacious in various animal models including those for visceral organ function, chronic inflammatory and neuropathic pain, and inflammation. The recent advancement of drug candidates targeting P2X channels into human trials, confirms the medicinal exploitability of this novel target family and provides hope that safe and effective medicines for the treatment of disorders involving P2X channels may be identified in the near future.
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Affiliation(s)
- Joel R Gever
- Department of Biochemical Pharmacology, Roche Palo Alto, 3431 Hillview Avenue, Palo Alto, CA 94304, USA.
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81
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Gu BJ, Wiley JS. Rapid ATP-induced release of matrix metalloproteinase 9 is mediated by the P2X7 receptor. Blood 2006; 107:4946-53. [PMID: 16514055 DOI: 10.1182/blood-2005-07-2994] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Matrix metalloproteinase-9 (MMP-9) activity is required for inflammatory response, leukocyte recruitment, and tumor invasion. There is increasing evidence suggesting that the P2X(7) receptor of mononuclear cells, which is activated by extracellular adenosine triphosphate (ATP), is involved in inflammatory responses. In this study, ATP caused a rapid release of MMP-9 and a moderate decrease in tissue inhibitor of metalloproteinase 1 (TIMP-1) release from human peripheral-blood mononuclear cells (PBMCs) over a 30-minute time course. The release was time- and dose-dependent and dissociated from ATP-induced cell death. BzATP, which is the most potent agonist for the P2X(7) receptor, also caused a similar effect at a lower dosage. ATP-induced MMP-9 release was inhibited by the P2X(7) receptor antagonists periodate oxidized ATP and KN-62, or by calcium chelators, as well as by a loss-of-function polymorphism in the P2X(7) receptor, but not by brefeldin A, monensin, or cycloheximide, or by anti-tumor necrosis factor-alpha (TNF-alpha) or anti-interleukin-1beta (IL-1beta) monoclonal antibodies. Results from purified subsets of PBMCs showed monocytes were the major source for MMP-9 and TIMP-1 release, and ATP remained effective in purified monocyte and T-cell populations. These observations suggest a novel role for P2X(7) as a pro-inflammatory receptor involved in rapid MMP-9 release and leukocyte recruitment.
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Affiliation(s)
- Ben J Gu
- Department of Medicine, University of Sydney, Nepean Hospital, Penrith, NSW 2750, Australia
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82
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Michel AD, Xing M, Thompson KM, Jones CA, Humphrey PPA. Decavanadate, a P2X receptor antagonist, and its use to study ligand interactions with P2X7 receptors. Eur J Pharmacol 2006; 534:19-29. [PMID: 16487507 DOI: 10.1016/j.ejphar.2006.01.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 12/22/2005] [Accepted: 01/10/2006] [Indexed: 10/25/2022]
Abstract
In this study we have studied decavanadate effects at P2X receptors. Decavanadate competitively blocked 2'- and 3'-O-(4benzoylbenzoyl) ATP (BzATP) stimulated ethidium accumulation in HEK293 cells expressing human recombinant P2X7 receptors (pK(B) 7.5). The effects of decavanadate were rapid (minutes) in both onset and offset and contrasted with the much slower kinetics of pyridoxal 5-phosphate (P5P), Coomassie brilliant blue (CBB) and 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine (KN62). Decavanadate competitively blocked the slowly reversible, or irreversible, blockade of the P2X7 receptor produced by P5P and oxidised ATP suggesting competition for a common binding site. However, the interaction between decavanadate and KN62 was non-competitive. Decavanadate also blocked P2X2 and P2X4 receptors but with slightly lower potency. These data demonstrate that decavanadate is the first reversible and competitive antagonist of the P2X7 receptor and is a useful tool for studying the mechanism of interaction of ligands with the P2X7 receptor.
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Affiliation(s)
- Anton D Michel
- Neurology and GI Centre of Excellence for Drug Discovery, GlaxoSmithKline Research and Development Limited, New Frontiers Science Park, Third Avenue, Harlow, Essex, CM19 5AW, UK.
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83
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Raffaghello L, Chiozzi P, Falzoni S, Di Virgilio F, Pistoia V. The P2X7 receptor sustains the growth of human neuroblastoma cells through a substance P-dependent mechanism. Cancer Res 2006; 66:907-14. [PMID: 16424024 DOI: 10.1158/0008-5472.can-05-3185] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
P2X(7) is a receptor for extracellular nucleotides expressed by different normal cell types. P2X(7) triggering may result in stimulation of cell proliferation or induction of apoptosis depending on the level of activation. P2X(7) expression and function in B-cell chronic lymphocytic leukemia has been shown to correlate with disease severity. Here, we have asked the question of whether P2X(7) is expressed and functional in neuroblastoma, a pediatric tumor of neuroectodermal origin. P2X(7) was detected both in primary neuroblastoma tumors and in neuroblastoma cell lines. In the latter cells, P2X(7) stimulation by ATP was found to trigger (a) increased intracellular calcium fluxes, (b) plasma membrane depolarization, and (c) formation of a nonselective plasma membrane permeable pore. In contrast to the usual response typically observed in the majority of cell types, P2X(7) in vitro stimulation did not induce caspase-3 activation or apoptosis of neuroblastoma cells but rather supported their proliferation. Growth stimulation was partially due to substance P release from nucleotide-activated neuroblastoma cells. Therefore, neuroblastoma cells seem to have molded P2X(7) function to their advantage in two ways (i.e., by silencing P2X(7) proapoptotic activity and by coupling P2X(7) stimulation to release of locally acting trophic factors).
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Affiliation(s)
- Lizzia Raffaghello
- Laboratory of Oncology, Giannina Gaslini Institute, Largo Gerolamo Gaslini 5, Genoa, Italy 16147.
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84
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González FA, Weisman GA, Erb L, Seye CI, Sun GY, Velázquez B, Hernández-Pérez M, Chorna NE. Mechanisms for inhibition of P2 receptors signaling in neural cells. Mol Neurobiol 2006; 31:65-79. [PMID: 15953812 DOI: 10.1385/mn:31:1-3:065] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2004] [Accepted: 11/15/2004] [Indexed: 12/24/2022]
Abstract
Trophic factors are required to ensure neuronal viability and regeneration after neural injury. Although abundant information is available on the factors that cause the activation of astrocytes, little is known about the molecular mechanisms underlying the regulation of this process. Nucleotides released into the extracellular space from injured or dying neural cells can activate astrocytes via P2 nucleotide receptors. After a brief historical review and update of novel P2 receptor antagonists, this article focuses on recent advancements toward understanding molecular mechanisms that regulate G protein-coupled P2Y receptor signaling. Among P2Y receptor subtypes, the heptahelical P2Y2 nucleotide receptor interacts with vitronectin receptors via an RGD sequence in the first extracellular loop, and this interaction is required for effective signal transduction to activate mitogen-activated protein kinases ERK1/2, to mobilize intracellular calcium stores via activation of phospholipase C, protein kinase C isoforms, and to activate focal adhesion kinase and other signaling events. Ligation of vitronectin receptors with specific antibodies caused an inhibition of P2Y2 receptor-induced ERK1/2 and p38 phosphorylation and P2Y2 receptor-induced cytoskeleton rearrangement and DNA synthesis. Structure-function studies have identified agonist-induced phosphorylation of the C-terminus of the P2Y2 receptor, an important mechanism for receptor desensitization. Understanding selective mechanisms for regulating P2Y2 receptor signaling could provide novel targets for therapeutic strategies in the management of brain injury, synaptogenesis, and neurological disorders.
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Affiliation(s)
- Fernando A González
- Department of Chemistry, University of Puerto Rico, Río Piedras Campus, Puerto Rico.
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85
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Ivanov I, Nikolova S, Statkova-Abeghe S. One-Pot Synthesis of 1-(2-, 3- or 4-Aminophenyl)- and 1-(4-Aminobenzyl)-3,4-dihydroisoquinolines. HETEROCYCLES 2006. [DOI: 10.3987/com-05-10625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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86
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Georgiou JG, Skarratt KK, Fuller SJ, Martin CJ, Christopherson RI, Wiley JS, Sluyter R. Human epidermal and monocyte-derived langerhans cells express functional P2X receptors. J Invest Dermatol 2005; 125:482-90. [PMID: 16117789 DOI: 10.1111/j.0022-202x.2005.23835.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Monocyte-derived dendritic cells (Mo-DC) express functional P2X7 receptors; however, the expression of these receptors on tissue-derived dendritic cells including epidermal Langerhans cells (LC) is unknown. Using immunolabeling and flow cytometry, we demonstrated that P2X7 was present on both human epidermal LC and monocyte-derived LC (Mo-LC), as well as on human keratinocytes. The ecto-ATPDase (CD39) was also present on LC, but not keratinocytes. The P2X7 agonists, 2'- and 3'-0(4-benzoylbenzoyl) adenosine 5'-triphosphate (BzATP) or ATP, but neither adenosine 5'-diphosphate (ADP) nor uridine 5'-triphosphate (UTP), induced ethidium+ uptake into these cells. Furthermore, ATP-induced ethidium+ uptake into epidermal LC, Mo-LC and keratinocytes was inhibited by the specific P2X7 antagonist, KN-62 (1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine). ATP-induced ethidium+ uptake into Mo-LC and Mo-DC was 2- and 3-fold greater, respectively, than that for fresh monocytes. P2X7 activation on LC induced downstream signaling events, as BzATP or ATP, but neither ADP nor UTP, induced shedding of the low-affinity receptor for IgE (CD23) from Mo-LC. This process was inhibited by KN-62. Finally, ATP-induced ethidium+ uptake and CD23 shedding were impaired in Mo-LC obtained from subjects homozygous for the loss-of-function Glu-496 to Ala polymorphism in the P2X7 receptor. These results demonstrate that human LC express functional P2X7 receptors, and suggest a role for this receptor in the skin immune system.
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Affiliation(s)
- Jennifer G Georgiou
- Department of Medicine, University of Sydney at Nepean Hospital, Penrith, NSW, Australia
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87
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New heterocyclic ligands for the adenosine receptors P1 and for the ATP receptors P2. ACTA ACUST UNITED AC 2005; 60:185-202. [PMID: 15784237 DOI: 10.1016/j.farmac.2004.09.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2004] [Revised: 07/08/2004] [Accepted: 09/15/2004] [Indexed: 11/26/2022]
Abstract
Extracellular adenosine and adenine nucleotides induce various cellular responses through activation of P1 and P2 receptors. P1 receptors preferentially recognize adenosine and four different G protein-coupled receptors (A(1), A(2A), A(2B), and A(3) subtypes) have been identified. On the other hand, P2 receptors are activated by adenine and/or uridine nucleotides and classified into two families: ionotropic P2X and G protein-coupled P2Y receptors. In this article, we summarize our studies which led to development of new potent and selective heterocyclic ligands for the adenosine receptors P1 and for the ATP receptors P2X(7).
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88
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Adinolfi E, Pizzirani C, Idzko M, Panther E, Norgauer J, Di Virgilio F, Ferrari D. P2X(7) receptor: Death or life? Purinergic Signal 2005; 1:219-27. [PMID: 18404507 PMCID: PMC2096546 DOI: 10.1007/s11302-005-6322-x] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Revised: 01/28/2005] [Accepted: 01/31/2005] [Indexed: 01/08/2023] Open
Abstract
The P2X7 plasma membrane receptor is an intriguing molecule that is endowed with the ability to kill cells, as well as to activate many responses and even stimulate proliferation. Here, the authors give an overview on the multiplicity and complexity of P2X7-mediated responses, discussing recent information on this receptor. Particular attention has been paid to early and late signs of apoptosis and necrosis linked to activation of the receptor and to the emerging field of P2X7 function in carcinogenesis.
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Affiliation(s)
- Elena Adinolfi
- Department of Experimental and Diagnostic Medicine, Section of General Pathology and Interdisciplinary Center for the Study of Inflammation (ICSI), University of Ferrara, Ferrara, Italy
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89
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Cheewatrakoolpong B, Gilchrest H, Anthes JC, Greenfeder S. Identification and characterization of splice variants of the human P2X7 ATP channel. Biochem Biophys Res Commun 2005; 332:17-27. [PMID: 15896293 DOI: 10.1016/j.bbrc.2005.04.087] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Accepted: 04/20/2005] [Indexed: 01/12/2023]
Abstract
The P2X7 channel is a member of the P2X family of ligand-gated ion channels which respond to ATP as the endogenous agonist. Studies suggest that P2X7 has a potentially pivotal role in inflammatory responses largely stemming from its role in mediating the release of IL-1beta in response to ATP. We report the identification of seven variants of human P2X7 which result from alternative splicing. Two of these variants (one lacking the first transmembrane domain, the second lacking the entire cytoplasmic tail) were compared to the full-length channel. Real-time PCR analysis demonstrated that both variants were expressed in various tissues and that the cytoplasmic tail deleted variant is highly expressed. Deletion of the first transmembrane domain resulted in a non-functional channel. Deletion of the cytoplasmic tail did not affect ion movement but severely affected the ability to form a large pore and to induce activation of caspases.
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Affiliation(s)
- Boonlert Cheewatrakoolpong
- Department of Cardiovascular/Metabolism, Schering-Plough Research Institute, 2015 Galloping Hill Road, Kenilworth, NJ 07033, USA
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90
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White N, Butler PEM, Burnstock G. Human melanomas express functional P2X7 receptors. Cell Tissue Res 2005; 321:411-8. [PMID: 15991050 DOI: 10.1007/s00441-005-1149-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2004] [Accepted: 04/13/2005] [Indexed: 12/22/2022]
Abstract
Adenosine 5'-triphosphate is known to function as a potent extracellular messenger, producing its effects via a distinct family of cell surface receptors. Different receptor subtypes have been shown to modulate different cellular functions such as proliferation, differentiation and apoptosis. We have investigated the functional expression and apoptotic action of the P2 X (7) receptor in human malignant melanoma tissue and cells. Incubation of cells with the potent P2 X (7) receptor agonist 2'-3'-O-(4-benzoyl-benzoyl) adenosine 5'-triphosphate leads to a decrease in cell number, which is dose-dependent and reversible by the antagonist 1-N,O-bis-[5-isoquinoline-sulfonyl]-N-methyl-L-tyrosyl)-4-phenyl-piperazine. Synthesis of the P2 X(7) receptor by these cells has been established by reverse transcriptase-polymerase chain reaction, immunohistochemistry, immunocytochemistry and cellular accumulation of the fluorescent DNA-binding dye YO-PRO-1. The P2 X(7) receptors have been shown to mediate apoptotic actions of extracellular nucleotides and represent a novel target for melanoma therapy.
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Affiliation(s)
- Nicholas White
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK
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91
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Coutinho-Silva R, Stahl L, Cheung KK, de Campos NE, de Oliveira Souza C, Ojcius DM, Burnstock G. P2X and P2Y purinergic receptors on human intestinal epithelial carcinoma cells: effects of extracellular nucleotides on apoptosis and cell proliferation. Am J Physiol Gastrointest Liver Physiol 2005; 288:G1024-35. [PMID: 15662049 DOI: 10.1152/ajpgi.00211.2004] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Extracellular nucleotides interact with purinergic receptors, which regulate ion transport in a variety of epithelia. With the use of two different human epithelial carcinoma cell lines (HCT8 and Caco-2), we have shown by RT-PCR that the cells express mRNA for P2X1, P2X3, P2X4, P2X5, P2X6, P2X7, P2Y1, P2Y2, P2Y4, P2Y6, P2Y11, and P2Y12 receptors. Protein expression for P2Y1 and P2Y2 receptors was also demonstrated immunohistochemically, and P2X receptor subtype protein was present in the following decreasing order: P2X4 > P2X7 > P2X1 > P2X3 > P2X6 > P2X5 >> P2X2. The functional presence of P2X7, P2Y1, P2Y2, and P2Y4 receptors was shown based on the effect of extracellular nucleotides on apoptosis or cell proliferation, and measurement of nucleotide-dependent calcium fluxes using a fluorometric imaging plate reader in the presence of different selective agonists and antagonists. ATP, at high concentrations, induced apoptosis through ligation of P2X7 and P2Y1 receptors; conversely, ATP, at lower concentrations, and UTP stimulated proliferation, probably acting via P2Y2 receptors. We therefore propose that stimulation or dysfunction of purinergic receptors may contribute at least partially to modulation of epithelial carcinoma cell proliferation and apoptosis.
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Affiliation(s)
- Robson Coutinho-Silva
- Autonomic Neuroscience Institute, Royal Free and University College Medical School, London, United Kingdom.
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92
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Romagnoli R, Baraldi PG, Di Virgilio F. Recent progress in the discovery of antagonists acting at P2X7receptor. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.15.3.271] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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93
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Narcisse L, Scemes E, Zhao Y, Lee SC, Brosnan CF. The cytokine IL-1beta transiently enhances P2X7 receptor expression and function in human astrocytes. Glia 2005; 49:245-58. [PMID: 15472991 PMCID: PMC2586293 DOI: 10.1002/glia.20110] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Extracellular nucleotide di- and triphosphates such as ATP and ADP mediate their effects through purinergic P2 receptors belonging to either the metabotropic P2Y or the ionotropic P2X receptor family. The P2X7R is a unique member of the P2X family, which forms a pore in response to ligand stimulation, regulating cell permeability, cytokine release, and/or apoptosis. This receptor is also unique in that its affinity for the ligand benzoyl-benzoyl ATP (BzATP) is at least 10-fold greater than that of ATP. Primary human fetal astrocytes in culture express low-levels of P2X7R mRNA and protein, and BzATP induces only a slight influx in intracellular calcium [Ca2+]i, with little demonstrable effect on gene expression or pore formation in these cells. We now show that, following treatment with the proinflammatory cytokine IL-1beta, BzATP induces a robust rise in [Ca2+]i with agonist and antagonist profiles indicative of the P2X7R. IL-1beta also induced the formation of membrane pores as evidenced by the uptake of YO-PRO-1 (375 Da). Quantitative real-time PCR demonstrated transient upregulation of P2X7R mRNA in IL-1beta-treated cells, while FACS analysis indicated a similar upregulation of P2X7R protein at the cell membrane. In multiple sclerosis lesions, immunoreactivity for the P2X7R was demonstrated on reactive astrocytes in autopsy brain tissues. In turn, P2X7R stimulation increased the production of IL-1-induced nitric oxide synthase activity by astrocytes in culture. These studies suggest that signaling via the P2X7R may modulate the astrocytic response to inflammation in the human central nervous system.
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Affiliation(s)
- Leontine Narcisse
- Department of Pathology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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94
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Sluyter R, Shemon AN, Barden JA, Wiley JS. Extracellular ATP increases cation fluxes in human erythrocytes by activation of the P2X7 receptor. J Biol Chem 2004; 279:44749-55. [PMID: 15304508 DOI: 10.1074/jbc.m405631200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Canine erythrocytes are known to undergo a reversible increase in cation permeability when incubated with extracellular ATP. We have examined the expression and function of P2X receptors on human erythrocytes using confocal microscopy and a panel of anti-P2X(1-7) antibodies and have measured monovalent cation fluxes in the presence of various nucleotide agonists. Human erythrocytes expressed P2X7 receptors on all cells examined from eight of eight subjects, as well as P2X2 at a far lower staining intensity in six of eight subjects. ATP stimulated the efflux of 86Rb+ (K+) from human erythrocytes in a dose-dependent fashion with an EC50 of approximately 95 microM. Other nucleotides also induced an efflux of 86Rb+ from erythrocytes with an order of agonist potency of 2'- and 3'-O(4-benzoylbenzoyl) ATP (BzATP) > ATP > 2-methylthio-ATP (2MeSATP) > adenosine 5'-O-(3-thiotriphosphate) (ATPgammaS), whereas ADP or UTP had no effect. ATP-induced efflux of 86Rb+ from erythrocytes was inhibited by extracellular Na+ and oxidized ATP, as well as by KN-62, an antagonist specific for the human P2X7 receptor. When erythrocytes were incubated in isotonic KCl medium, the addition of ATP stimulated an 86Rb+ influx approximately equal in magnitude to ATP-stimulated 86Rb+ efflux from the same cells. BzATP also stimulated the influx of 22Na+ into erythrocytes incubated in isotonic NaCl medium. Both ATP-induced efflux and influx of 86Rb+ and 22Na+ were impaired in erythrocytes from subjects who had inherited loss-of-function polymorphisms in the P2X7 receptor. These results suggest that the reversible permeabilization of erythrocytes by extracellular ATP is mediated by the P2X7 receptor.
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Affiliation(s)
- Ronald Sluyter
- Department of Medicine, University of Sydney at Nepean Hospital, Penrith, New South Wales 2750, Australia
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95
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Wang L, Jacobsen SEW, Bengtsson A, Erlinge D. P2 receptor mRNA expression profiles in human lymphocytes, monocytes and CD34+ stem and progenitor cells. BMC Immunol 2004; 5:16. [PMID: 15291969 PMCID: PMC509419 DOI: 10.1186/1471-2172-5-16] [Citation(s) in RCA: 146] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2004] [Accepted: 08/03/2004] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Extracellular nucleotides (ATP, ADP, UTP and UDP) exert a wide range of biological effects in blood cells mediated by multiple ionotropic P2X receptors and G protein-coupled P2Y receptors. Although pharmacological experiments have suggested the presence of several P2 receptor subtypes on monocytes and lymphocytes, some results are contradictory. Few physiological functions have been firmly established to a specific receptor subtype, partly because of a lack of truly selective agonists and antagonists. This stimulated us to investigate the expression of P2X and P2Y receptors in human lymphocytes and monocytes with a newly established quantitative mRNA assay for P2 receptors. In addition, we describe for the first time the expression of P2 receptors in CD34+ stem and progenitor cells implicating a potential role of P2 receptors in hematopoietic lineage and progenitor/stem cell function. RESULTS Using a quantitative mRNA assay, we assessed the hypothesis that there are specific P2 receptor profiles in inflammatory cells. The P2X4 receptor had the highest expression in lymphocytes and monocytes. Among the P2Y receptors, P2Y12 and P2Y2 had highest expression in lymphocytes, while the P2Y2 and P2Y13 had highest expression in monocytes. Several P2 receptors were expressed (P2Y2, P2Y1, P2Y12, P2Y13, P2Y11, P2X1, P2X4) in CD34+ stem and progenitor cells. CONCLUSIONS The most interesting findings were the high mRNA expression of P2Y12 receptors in lymphocytes potentially explaining the anti-inflammatory effects of clopidogrel, P2Y13 receptors in monocytes and a previously unrecognised expression of P2X4 in lymphocytes and monocytes. In addition, for the first time P2 receptor mRNA expression patterns was studied in CD34+ stem and progenitor cells. Several P2 receptors were expressed (P2Y2, P2Y1, P2Y12, P2Y13, P2Y11, P2X1, P2X4), indicating a role in differentiation and proliferation. Thus, it is possible that specific antibodies to P2 receptors could be used to identify progenitors for monocytes, lymphocytes and megakaryocytes.
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Affiliation(s)
- Lingwei Wang
- Department of Cardiology, Lund University Hospital, S-221 85 Lund, Sweden
| | - Sten Eirik W Jacobsen
- Department of Hematopoietic Stem Cell Laboratory, Lund Center for Stem Cell Biology and Cell Therapy, Lund University Hospital, S-221 85 Lund, Sweden
| | - Anders Bengtsson
- Department of Rheumatology, Lund University Hospital, S-221 85 Lund, Sweden
| | - David Erlinge
- Department of Cardiology, Lund University Hospital, S-221 85 Lund, Sweden
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96
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Baxter A, Bent J, Bowers K, Braddock M, Brough S, Fagura M, Lawson M, McInally T, Mortimore M, Robertson M, Weaver R, Webborn P. Hit-to-Lead studies: the discovery of potent adamantane amide P2X7 receptor antagonists. Bioorg Med Chem Lett 2004; 13:4047-50. [PMID: 14592505 DOI: 10.1016/j.bmcl.2003.08.034] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A Hit-to-Lead optimisation programme was carried out on the adamantane high throughput screening hit 1 resulting in the discovery of a number of potent P2X(7) antagonists.
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Affiliation(s)
- Andrew Baxter
- AstraZeneca R&D Charnwood, Bakewell Road, Loughborough LE11 5RH, UK.
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97
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Shemon AN, Sluyter R, Conigrave AD, Wiley JS. Chelerythrine and other benzophenanthridine alkaloids block the human P2X7 receptor. Br J Pharmacol 2004; 142:1015-9. [PMID: 15210579 PMCID: PMC1575114 DOI: 10.1038/sj.bjp.0705868] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
1 Extracellular ATP can activate a cation-selective channel/pore on human B-lymphocytes, known as the P2X7 receptor. Activation of this receptor is linked to PLD stimulation. We have used ATP-induced 86Rb+ (K+) efflux to examine the effect of benzophenanthridine alkaloids on P2X7 channel/pore function in human B-lymphocytes. 2 Both ATP and the nucleotide analogue 2'-3'-O-(4-benzoylbenzoyl)-ATP (BzATP) induced an 86Rb+ efflux, which was completely inhibited by the isoquinoline derivative 1-(N,O-bis[5-isoquinolinesulphonyl]-N-methyl-l-tyrosyl)-4-phenylpiperazine (KN-62), a potent P2X7 receptor antagonist. 3 The benzophenanthridine alkaloid chelerythrine, a potent PKC inhibitor, inhibited the ATP-induced 86Rb+ efflux by 73.4+/-3.5% and with an IC50 of 5.6+/-2.3 microm. Similarly, other members of this family of compounds, sanguinarine and berberine, blocked the ATP-induced 86Rb+ efflux by 58.8+/-4.8 and 61.1+/-8.0%, respectively. 4 Concentration-effect curves to ATP estimated an EC50 value of 78 microm and in the presence of 5 and 10 microm chelerythrine this increased slightly to 110 and 150 microm, respectively, which fits a noncompetitive inhibitor profile for chelerythrine. 5 Chelerythrine at 10 microm was effective at inhibiting the ATP-induced PLD stimulation in B-lymphocytes by 94.2+/-21.9% and the phorbol 12-myristate 13-acetate-induced PLD stimulation by 68.2+/-7.4%. 6 This study demonstrates that chelerythrine in addition to PKC inhibition has a noncompetitive inhibitory action on the P2X7 receptor itself.
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Affiliation(s)
- Anne N Shemon
- Department of Medicine, The University of Sydney at Nepean Hospital, Penrith, NSW, 2751, Australia
| | - Ronald Sluyter
- Department of Medicine, The University of Sydney at Nepean Hospital, Penrith, NSW, 2751, Australia
| | - Arthur D Conigrave
- School of Molecular and Microbial Biosciences, The University of Sydney, Sydney, NSW, 2006, Australia
| | - James S Wiley
- Department of Medicine, The University of Sydney at Nepean Hospital, Penrith, NSW, 2751, Australia
- Author for correspondence:
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98
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Lajdova I, Chorvat D, Spustova V, Chorvatova A. 4-Aminopyridine activates calcium influx through modulation of the pore-forming purinergic receptor in human peripheral blood mononuclear cells. Can J Physiol Pharmacol 2004; 82:50-6. [PMID: 15052305 DOI: 10.1139/y03-128] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated whether 4-aminopyridine (4AP), a drug recently linked to calcium influx and apoptosis, also affected purinergic receptor channels that are known to play an important role in the activation of T lymphocytes. The application of 4AP induced a rise in [Ca2+]i that was sensitive to nickel. This action was also observed in cells in which calcium reserves were emptied using thapsigargin (Tg). However, it was not present in the absence of extracellular Ca2+, despite full internal reserves. Adenosine trisphosphate (ATP), a partial agonist and a physiological activator of purinergic receptors, also stimulated Ca2+ entry independently of the calcium release from internal compartments. The effects of 4AP and ATP were not additive when studied on the same population of cells. KN-62 inhibited an increase in calcium entry induced by 4AP, while brilliant blue G (BBG) prevented it, supporting the hypothesis that purinergic P2X7 receptors are involved in this action. Furthermore, 4AP allowed entry of ethidium bromide (314 Da) but not propidium iodide (415 Da) into the cell, also corroborating the involvement of P2X7 pores. The presented results demonstrate, for the first time in human mononuclear cells isolated from healthy volunteers, that the P2X7 channel pore is involved in the action of 4AP and intervenes in the sustained calcium entry induced in response to 4AP.Key words: calcium, human lymphocytes, 4-aminopyridine, purinergic receptors.
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Affiliation(s)
- Ingrid Lajdova
- Institute of Preventive and Clinical Medicine, Limbova 14, Bratislava, Slovak Republic
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Seman M, Adriouch S, Scheuplein F, Krebs C, Freese D, Glowacki G, Deterre P, Haag F, Koch-Nolte F. NAD-Induced T Cell Death. Immunity 2003; 19:571-82. [PMID: 14563321 DOI: 10.1016/s1074-7613(03)00266-8] [Citation(s) in RCA: 262] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
T cells express a toxin-related ADP-ribosylating ectoenzyme, ART2. Exposure of mature T cells to NAD, the substrate for ADP-ribosylation, induces cell death. ART2-catalyzed ADP-ribosylation activates the cytolytic P2X7 purinoceptor, causing calcium flux, pore formation, phosphatidylserine exposure, shedding of CD62L, cell shrinkage, and propidium iodide uptake. Interestingly, much lower NAD than ATP concentrations are required to activate P2X7. NAD-induced cell death (NICD) operates with endogenous sources of NAD released upon cell lysis. These findings identify P2X7 as a key effector of NICD and demonstrate that P2X7 can be activated by an endogenous ligand other than ATP. Our results delineate an alternative mechanism for inducing T cell death and set an interesting precedent for immunoregulation via crosstalk between NAD-dependent ADP-ribosyltransferases and purinoceptors.
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100
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Baraldi PG, del Carmen Nuñez M, Morelli A, Falzoni S, Di Virgilio F, Romagnoli R. Synthesis and biological activity of N-arylpiperazine-modified analogues of KN-62, a potent antagonist of the purinergic P2X7 receptor. J Med Chem 2003; 46:1318-29. [PMID: 12672232 DOI: 10.1021/jm021049d] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The P2X(7) receptor is involved in several processes relevant to inflammation (cytokine release, NO generation, killing of intracellular pathogens, cytotoxicity); thus, it may be an appealing target for pharmacological intervention. The characterization of native and recombinant P2X(7) receptor continues to be hindered by the lack of specific and subtype-selective antagonists. However, a tyrosine derivative named KN-62 exhibits selective P2X(7) receptor-blocking properties. The present study was designed to evaluate the functional antagonistic properties of a novel series of KN-62-related compounds characterized by the presence of different phenyl-substituted piperazine moieties. Antagonistic activity of KN-62 derivatives was tested on HEK293 cells transduced with the human P2X(7) receptor and monocyte-derived human macrophages, a cell type well-known for the high level of expression of this receptor. The biological responses investigated were ATP-dependent Ca(2+) influx across the plasma membrane, ethidium bromide uptake, and secretion of the cytokine interleukin-1beta. KN-62 was characterized by the presence of a phenylpiperazine moiety, and the presence of a one-carbon linker between the piperazine nitrogen and the phenyl ring (compound 61) increases the activity, while a two-carbon linker (compound 62) decreases biological activity 10-fold. Also, the nature and the position of substituents on the phenyl ring tethered to the piperazine seemed to exert a fundamental influence on the biological activity. In the series of synthesized compounds, the presence of a fluorine in the para position gives the most potent compound (63), while the same atom in the ortho position reduces potency by 3-fold. When the p-fluorine was replaced in the same position with other halogens, such as chlorine (compound 64) or iodine (compound 65), the activity decreased dramatically. We then tested the activity of the four most potent KN-62 derivatives on ATP-stimulated secretion of IL-1beta from monocyte-derived human macrophages, a key cell type in inflammation and innate immunity. Interestingly, compound 68 and 71 caused a complete inhibition of IL-1beta release, while with KN-62, 63, and 85, there was a small residual cytokine secretion even at concentrations exceeding 100 nM. None of the compounds tested on IL-1beta release had any effect on isolated CaMII kinase activity up to 20 microM (not shown).
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Affiliation(s)
- Pier Giovanni Baraldi
- Dipartimento di Scienze Farmaceutiche, Sezione di Patologia Generale, Università di Ferrara, Italy.
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