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Amos C Hung - One of the best experts on this subject based on the ideXlab platform.
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atp stimulated ca2 influx and phospholipase d activities of a rat brain derived type 2 astrocyte cell line rba 2 are mediated through P2x7 Receptors
Journal of Neurochemistry, 2002Co-Authors: Amos C HungAbstract:This study characterizes and examines the P2 Receptor-mediated signal transduction pathway of a rat brain-derived type 2 astrocyte cell line, RBA-2. ATP induced Ca 2+ influx and activated phospholipase D (PLD). The ATP-stimulated Ca 2+ influx was inhibited by pretreating cells with P2 Receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), in a concentration-dependent manner. The agonist 2'-and 3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP) stimulated the largest increases in intracellular Ca 2+ concentrations ([Ca 2+ ] i ); ATP, 2-methylthioadenosine triphosphate tetrasodium, and ATPγS were much less effective, whereas UTP, ADP, α,β-methylene-ATP, and β,γ-methylene-ATP were ineffective. Furthermore, removal of extracellular Mg 2+ enhanced the ATP- and BzATP-stimulated increases in [Ca 2+ ] i . BzATP stimulated PLD in a concentration- and time-dependent manner that could be abolished by removal of extracellular Ca 2+ and was inhibited by suramin, PPADS, and oxidized ATP. In addition, PLD activities were activated by the Ca 2+ mobilization agent, ionomycin, in an extracellular Ca 2+ concentration-dependent manner. Both staurosporine and prolonged phorbol ester treatment inhibited BzATP-stimulated PLD activity. Taken together, these data indicate that activation of the P2X 7 Receptors induces Ca 2+ influx and stimulates a Ca 2+ -dependent PLD in RBA-2 astrocytes. Furthermore, protein kinase C regulates this PLD.
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atp stimulated ca2 influx and phospholipase d activities of a rat brain derived type 2 astrocyte cell line rba 2 are mediated through P2x7 Receptors
Journal of Neurochemistry, 2002Co-Authors: Synthia H Sun, Amos C Hung, Lianbin Lin, Jonson KuoAbstract:This study characterizes and examines the P2 Receptor-mediated signal transduction pathway of a rat brain-derived type 2 astrocyte cell line, RBA-2. ATP induced Ca2+ influx and activated phospholipase D (PLD). The ATP-stimulated Ca2+ influx was inhibited by pretreating cells with P2 Receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), in a concentration-dependent manner. The agonist 2'- and 3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP) stimulated the largest increases in intracellular Ca2+ concentrations ([Ca2+]i); ATP, 2-methylthioadenosine triphosphate tetrasodium, and ATPgammaS were much less effective, whereas UTP, ADP, alpha,beta-methylene-ATP, and beta,gamma-methylene-ATP were ineffective. Furthermore, removal of extracellular Mg2+ enhanced the ATP- and BzATP-stimulated increases in [Ca2+]i. BzATP stimulated PLD in a concentration- and time-dependent manner that could be abolished by removal of extracellular Ca2+ and was inhibited by suramin, PPADS, and oxidized ATP. In addition, PLD activities were activated by the Ca2+ mobilization agent, ionomycin, in an extracellular Ca2+ concentration-dependent manner. Both staurosporine and prolonged phorbol ester treatment inhibited BzATP-stimulated PLD activity. Taken together, these data indicate that activation of the P2X7 Receptors induces Ca2+ influx and stimulates a Ca2+-dependent PLD in RBA-2 astrocytes. Furthermore, protein kinase C regulates this PLD.
Jean Sevigny - One of the best experts on this subject based on the ideXlab platform.
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inhibition of human and mouse plasma membrane bound ntpdases by P2 Receptor antagonists
Biochemical Pharmacology, 2007Co-Authors: Mercedes N Munkonda, Joanna Lecka, Sebastien A Levesque, Filip Kukulski, Elise G Lavoie, Gilles Kauffenstein, Charlene Legendre, Julie Pelletier, Jean SevignyAbstract:The plasma membrane bound nucleoside triphosphate diphosphohydrolase (NTPDase)-1, 2, 3 and 8 are major ectonucleotidases that modulate P2 Receptor signaling by controlling nucleotides' concentrations at the cell surface. In this report, we systematically evaluated the effect of the commonly used P2 Receptor antagonists reactive blue 2, suramin, NF279, NF449 and MRS2179, on recombinant human and mouse NTPDase1, 2, 3 and 8. Enzymatic reactions were performed in a Tris/calcium buffer, commonly used to evaluate NTPDase activity, and in a more physiological Ringer modified buffer. Although there were some minor variations, there were no major changes either in the enzymatic activity or in the profile of NTPDase inhibition between the two buffers. Except for MRS2179, all other antagonists significantly inhibited these ecto-ATPases; NTPDase3 being the most sensitive to inhibition and NTPDase8 the most resistant. Estimated IC(50) showed that human NTPDases were generally more sensitive to the P2 Receptor antagonists tested than the corresponding mouse isoforms. NF279 and reactive blue 2 were the most potent inhibitors of NTPDases which almost completely abrogated their activity at the concentration of 100 microM. In conclusion, reactive blue 2, suramin, NF279 and NF449, at the concentrations commonly used to antagonize P2 Receptors, inhibit the four major ecto-ATPases. This information may reveal useful for the interpretation of some pharmacological studies of P2 Receptors. In addition, NF279 is a most potent non-selective NTPDase inhibitor. Although P2 Receptor antagonists do not display a strict selectivity toward NTPDases, their IC(50) values may help to discriminate some of these enzymes.
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erratum to comparative hydrolysis of P2 Receptor agonists by ntpdases 1 2 3 and 8 purinergic signalling
Purinergic Signalling, 2005Co-Authors: Filip Kukulski, Joanna Lecka, Simon C Robson, Sebastien A Levesque, Elise G Lavoie, Francois Bigonnesse, Aileen F Knowles, Terence L Kirley, Jean SevignyAbstract:F. Kukulski, S.A. Levesque, E.G. Lavoie, J. Lecka, F. Bigonnesse, A.F. Knowles, S.C. Robson, T.L. Kirley & J. Sevigny (2005) Comparative hydrolysis of P2 Receptor agonists by NTPDases 1, 2, 3 and 8. Purinergic Signalling 1(2): 193–204. On page 194 of the above-mentioned article, in ‘Materials and methods’ under ‘Plasmids,’ second paragraph, the mouse NTPDase2 accession number AY37674 is incorrect and should read {"type":"entrez-nucleotide","attrs":{"text":"AY376711","term_id":"36312788","term_text":"AY376711"}}AY376711.
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expression of ntpdase1 and ntpdase2 in murine kidney relevance to regulation of P2 Receptor signaling
American Journal of Physiology-renal Physiology, 2005Co-Authors: Bellamkonda K Kishore, Jean Sevigny, Norbert Braun, Herbert Zimmermann, Jorge Isaac, Michel Fausther, Sheryl R Tripp, Huihui Shi, Pritmohinder S Gill, Simon C RobsonAbstract:The regulation of renal function by extracellular nucleotides encompasses alterations in glomerular hemodynamics, microvascular function, tubuloglomerular feedback, tubular transport, cell growth or apoptosis, and transport of water and solutes in the medullary collecting duct. Nearly all cells can release ATP or other nucleotides that are then rapidly hydrolyzed in the extracellular milieu. However, little information is available on the cellular expression of ectoenzymes that hydrolyze extracellular nucleotides within the kidney. Nucleoside triphosphate diphosphohydrolases (NTPDases) are plasma membrane-bound ectonucleotidases. NTPDase1 has identity with CD39, a B lymphocyte activation marker, and hydrolyzes extracellular ATP and ADP to AMP within the vasculature, whereas NTPDase2/CD39L(ike)1 preferentially converts ATP to ADP outside of blood vessels. Using immunohistochemical and in situ hybridization approaches, we localized the protein and mRNA of NTPDase1 and 2 in murine renal tissues. In the renal cortex, NTPDase1 is expressed by vascular smooth muscle cells and endothelium in interlobular arteries, afferent glomerular arterioles, and peritubular capillaries. In the inner medulla, NTPDase1 is expressed in ascending thin limbs of Henle's loop, ducts of Bellini, and in the pelvic wall. In contrast, NTPDase2 is expressed in Bowman's capsule, glomerular arterioles, adventitia of blood vessels, and pelvic wall. Thus the distribution patterns of NTPDases have parallels to the known distribution of P2 Receptors within the kidney. NTPDases may modulate regulatory effects of ATP and degradation products within the vasculature and other sites and thereby potentially influence physiological as well as multiple pathological events in the kidney.
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comparative hydrolysis of P2 Receptor agonists by ntpdases 1 2 3 and 8
Purinergic Signalling, 2005Co-Authors: Filip Kukulski, Joanna Lecka, Simon C Robson, Sebastien A Levesque, Elise G Lavoie, Francois Bigonnesse, Aileen F Knowles, Terence L Kirley, Jean SevignyAbstract:Nucleoside triphosphate diphosphohydrolases 1, 2, 3 and 8 (NTPDases 1, 2, 3 and 8) are the dominant ectonucleotidases and thereby expected to play important roles in nucleotide signaling. Distinct biochemical characteristics of individual NTPDases should allow them to regulate P2 Receptor activation differentially. Therefore, the biochemical and kinetic properties of these enzymes were compared. NTPDases 1, 2, 3 and 8 efficiently hydrolyzed ATP and UTP with Km values in the micromolar range, indicating that they should terminate the effects exerted by these nucleotide agonists at P2X1- and P2Y2,4,11 Receptors. Since NTPDase1 does not allow accumulation of ADP, it should terminate the activation of P2Y1,12,13 Receptors far more efficiently than the other NTPDases. In contrast, NTPDases 2, 3 and 8 are expected to promote the activation of ADP specific Receptors, because in the presence of ATP they produce a sustained (NTPDase2) or transient (NTPDases 3 and 8) accumulation of ADP. Interestingly, all plasma membrane NTPDases dephosphorylate UTP with a significant accumulation of UDP, favoring P2Y6 Receptor activation. NTPDases differ in divalent cation and pH dependence, although all are active in the pH range of 7.0-.5. Various NTPDases may also distinctly affect formation of extracellular adenosine and therefore adenosine Receptor-mediated responses, since they generate different amounts of the substrate (AMP) and inhibitor (ADP) of ecto-5-nucleotidase, the rate limiting enzyme in the production of adenosine. Taken together, these data indicate that plasma membrane NTPDases hydrolyze nucleotides in a distinctive manner and may therefore differentially regulate P2 and adenosine Receptor signaling.
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cloning and characterization of mouse nucleoside triphosphate diphosphohydrolase 3
Biochemical Pharmacology, 2004Co-Authors: Elise G Lavoie, Joanna Lecka, Sebastien A Levesque, Filip Kukulski, Jean SevignyAbstract:Abstract We have cloned and characterized the nucleoside triphosphate diphosphohydrolase-3 (NTPDase3) from mouse spleen. Analysis of cDNA shows an open reading frame of 1587 base pairs encoding a protein of 529 amino acids with a predicted molecular mass of 58 953 Da and an estimated isoelectric point of 5.78. The translated amino acid sequence shows the presence of two transmembrane domains, eight potential N-glycosylation sites and the five apyrase conserved regions. The genomic sequence is located on chromosome 9F4 and is comprised of 11 exons. Intact COS-7 cells transfected with an expression vector containing the coding sequence for mouse NTPDase3 hydrolyzed P2 Receptor agonists (ATP, UTP, ADP and UDP) but not AMP. NTPDase3 required divalent cations (Ca2+>Mg2+) for enzymatic activity. Interestingly, the enzyme had two optimum pHs for ATPase activity (pH 5.0 and 7.4) and one for ADPase activity (pH 8.0). Consequently, the ATP/ADP and UTP/UDP hydrolysis ratios were two to four folds higher at pH 5.0 than at pH 7.4, for both, intact cells and protein extracts. At pH 7.4 mouse NTPDase3 hydrolyzed ATP, UTP, ADP and UDP according to Michaelis–Menten kinetics with apparent Kms of 11, 10, 19 and 27 μM, respectively. In agreement with the Km values, the pattern of triphosphonucleoside hydrolysis showed a transient accumulation of the corresponding diphosphonucleoside and similar affinity for uracil and adenine nucleotides. NTPDase3 hydrolyzes nucleotides in a distinct manner than other plasma membrane bound NTPDases that may be relevant for the fine tuning of the concentration of P2 Receptor agonists.
Jonson Kuo - One of the best experts on this subject based on the ideXlab platform.
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P2 purinergic Receptor activation of neuronal nitric oxide synthase and guanylyl cyclase in the dorsal facial area of the medulla increases blood flow in the common carotid arteries of cats
Neuroscience, 2015Co-Authors: Y W Hung, Jonson Kuo, Yukman Leung, Nainu Lin, Tony Jerfu Lee, Kwongchung Tung, Chili GongAbstract:Abstract In the dorsal facial area (DFA) of the medulla, an activation of either P2 purinergic Receptor or nitric oxide synthase (NOS) results in the release of glutamate, leading to an increase in blood flow of the common carotid artery (CCA). It is not known whether activation of the P2 Receptor by ATP may mediate activation of NOS/guanylyl cyclase to cause glutamate release and/or whether l -Arg (nitric oxide (NO) precursor) may also cause ATP release from any other neuron, to cause an increase in CCA flow. We demonstrated that microinjections of P2 Receptor agonists (ATP, α,β-methylene ATP) or NO precursor ( l -arginine) into the DFA increased CCA blood flow. The P2-induced CCA blood flow increase was dose-dependently reduced by pretreatment with NG-nitro-arginine methyl ester ( l -NAME, a non-specific NOS inhibitor), 7-nitroindazole (7-NI, a relatively selective neuronal NOS inhibitor) or methylene blue (MB, a guanylyl cyclase inhibitor) but not by that with d -NAME (an isomer of l -NAME) or N5-(1-iminoethyl)- l -ornithine ( l -NIO, a potent endothelial NOS inhibitor). Involvement of glutamate release in these responses were substantiated by microdialysis studies, in which perfusions of ATP into the DFA increased the glutamate concentration in dialysates, but co-perfusion of ATP with l -NAME or 7-NI did not. Nevertheless, the arginine-induced CCA blood flow increase was abolished by combined pretreatment of l -NAME and MB, but not affected by pretreatment with a selective P2 Receptor antagonist, pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS). In conclusion, ATP activation of the P2 Receptor in the DFA induced activation of neuronal NOS/guanylyl cyclase, which causes glutamate release leading to an increase in CCA blood flow. However, arginine activation of neuronal NOS/guanylyl cyclase, which also caused glutamate release and CCA blood flow increase, did not induce activation of P2 Receptors. These findings provide important information for drug design and/or developing therapeutic strategies for the diseases associated with CCA blood flow that supplies intra- and extra-cranial tissues.
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atp stimulated ca2 influx and phospholipase d activities of a rat brain derived type 2 astrocyte cell line rba 2 are mediated through P2x7 Receptors
Journal of Neurochemistry, 2002Co-Authors: Synthia H Sun, Amos C Hung, Lianbin Lin, Jonson KuoAbstract:This study characterizes and examines the P2 Receptor-mediated signal transduction pathway of a rat brain-derived type 2 astrocyte cell line, RBA-2. ATP induced Ca2+ influx and activated phospholipase D (PLD). The ATP-stimulated Ca2+ influx was inhibited by pretreating cells with P2 Receptor antagonist, pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (PPADS), in a concentration-dependent manner. The agonist 2'- and 3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (BzATP) stimulated the largest increases in intracellular Ca2+ concentrations ([Ca2+]i); ATP, 2-methylthioadenosine triphosphate tetrasodium, and ATPgammaS were much less effective, whereas UTP, ADP, alpha,beta-methylene-ATP, and beta,gamma-methylene-ATP were ineffective. Furthermore, removal of extracellular Mg2+ enhanced the ATP- and BzATP-stimulated increases in [Ca2+]i. BzATP stimulated PLD in a concentration- and time-dependent manner that could be abolished by removal of extracellular Ca2+ and was inhibited by suramin, PPADS, and oxidized ATP. In addition, PLD activities were activated by the Ca2+ mobilization agent, ionomycin, in an extracellular Ca2+ concentration-dependent manner. Both staurosporine and prolonged phorbol ester treatment inhibited BzATP-stimulated PLD activity. Taken together, these data indicate that activation of the P2X7 Receptors induces Ca2+ influx and stimulates a Ca2+-dependent PLD in RBA-2 astrocytes. Furthermore, protein kinase C regulates this PLD.
Peter Illes - One of the best experts on this subject based on the ideXlab platform.
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The P2 Receptor antagonist PPADS supports recovery from experimental stroke in vivo.
PloS one, 2011Co-Authors: Alexandra Lämmer, Alexander Beck, Benjamin Grummich, Annette Förschler, Thomas Krügel, Thomas Kahn, Dietmar Schneider, Peter Illes, Heike Franke, Ute KrügelAbstract:Background After ischemia of the CNS, extracellular adenosine 5′-triphosphate (ATP) can reach high concentrations due to cell damage and subsequent increase of membrane permeability. ATP may cause cellular degeneration and death, mediated by P2X and P2Y Receptors. Methodology/Principal Findings The effects of inhibition of P2 Receptors by pyridoxalphosphate-6-azophenyl-2′,4′-disulphonic acid (PPADS) on electrophysiological, functional and morphological alterations in an ischemia model with permanent middle cerebral artery occlusion (MCAO) were investigated up to day 28. Spontaneously hypertensive rats received PPADS or vehicle intracerebroventricularly 15 minutes prior MCAO for up to 7 days. The functional recovery monitored by qEEG was improved by PPADS indicated by an accelerated recovery of ischemia-induced qEEG changes in the delta and alpha frequency bands along with a faster and sustained recovery of motor impairments. Whereas the functional improvements by PPADS were persistent at day 28, the infarct volume measured by magnetic resonance imaging and the amount of TUNEL-positive cells were significantly reduced by PPADS only until day 7. Further, by immunohistochemistry and confocal laser scanning microscopy, we identified both neurons and astrocytes as TUNEL-positive after MCAO. Conclusion The persistent beneficial effect of PPADS on the functional parameters without differences in the late (day 28) infarct size and apoptosis suggests that the early inhibition of P2 Receptors might be favourable for the maintenance or early reconstruction of neuronal connectivity in the periinfarct area after ischemic incidents.
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P2 Receptor signaling in neurons and glial cells of the central nervous system
Advances in pharmacology (San Diego), 2011Co-Authors: Laszlo Koles, Anna Leichsenring, Patrizia Rubini, Peter IllesAbstract:Purine and pyrimidine nucleotides are extracellular signaling molecules in the central nervous system (CNS) leaving the intracellular space of various CNS cell types via nonexocytotic mechanisms. In addition, ATP is a neuro-and gliotransmitter released by exocytosis from neurons and neuroglia. These nucleotides activate P2 Receptors of the P2X (ligand-gated cationic channels) and P2Y (G protein-coupled Receptors) types. In mammalians, seven P2X and eight P2Y Receptor subunits occur; three P2X subtypes form homomeric or heteromeric P2X Receptors. P2Y subtypes may also hetero-oligomerize with each other as well as with other G protein-coupled Receptors. P2X Receptors are able to physically associate with various types of ligand-gated ion channels and thereby to interact with them. The P2 Receptor homomers or heteromers exhibit specific sensitivities against pharmacological ligands and have preferential functional roles. They may be situated at both presynaptic (nerve terminals) and postsynaptic (somatodendritic) sites of neurons, where they modulate either transmitter release or the postsynaptic sensitivity to neurotransmitters. P2 Receptors exist at neuroglia (e.g., astrocytes, oligodendrocytes) and microglia in the CNS. The neuroglial P2 Receptors subserve the neuron-glia cross talk especially via their end-feets projecting to neighboring synapses. In addition, glial networks are able to communicate through coordinated oscillations of their intracellular Ca(2+) over considerable distances. P2 Receptors are involved in the physiological regulation of CNS functions as well as in its pathophysiological dysregulation. Normal (motivation, reward, embryonic and postnatal development, neuroregeneration) and abnormal regulatory mechanisms (pain, neuroinflammation, neurodegeneration, epilepsy) are important examples for the significance of P2 Receptor-mediated/modulated processes.
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P2 Receptor mediated stimulation of the pi3 k akt pathway in vivo
Glia, 2009Co-Authors: Heike Franke, Ute Krügel, C Sauer, Claudia Rudolph, Jan G Hengstler, Peter IllesAbstract:ATP acts as a growth factor as well as a toxic agent by stimulating P2 Receptors. The P2 Receptor-activated signaling cascades mediating cellular growth and cell survival after injury are only incompletely understood. Therefore, the aim of the present study was to identify the role of the phosphoinositide 3 kinase (PI3-K/Akt) and the mitogen-activated protein kinase/extracellular signal regulated protein kinase (MAPK/ERK) pathways in P2Y Receptor-mediated astrogliosis after traumatic injury and after microinfusion of ADP beta S (P2Y(1,12,13) Receptor agonist) into the rat nucleus accumbens (NAc). Mechanical damage and even more the concomitant treatment with ADP beta S, enhanced P2Y(1) Receptor-expression in the NAc, which could be reduced by pretreatment with the P2X/Y Receptor antagonist PPADS. Quantitative Western blot analysis indicated a significant increase in phosphorylated (p)Akt and pERK1/2 2 h after ADP beta S-microinjection. Pretreatment with PPADS or wortmannin abolished the up-regulation of pAkt by injury alone or ADP beta S-treatment. The ADP beta S-enhanced expression of the early apoptosis marker active caspase 3 was reduced by PPADS and PD98059, but not by wortmannin. Multiple immunofluorescence labeling indicated a time-dependent expression of pAkt and pMAPK on astrocytes and neurons and additionally the colocalization of pAkt, pMAPK, and active caspase 3 with the P2Y(1) Receptor especially at astrocytes. In conclusion, the data show for the first time the involvement of PI3-K/Akt-pathway in processes of injury-induced astroglial proliferation and anti-apoptosis via activation of P2Y(1) Receptors in vivo, suggesting specific roles of P2 Receptors in glial cell pathophysiology in neurodegenerative diseases.
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P2 Receptor expression in the dopaminergic system of the rat brain during development
Neuroscience, 2007Co-Authors: Peter Illes, Jens Grosche, Claudia Heine, A Wegner, Clemens Allgaier, Heike FrankeAbstract:Extracellular ATP facilitates the release of dopamine via P2 Receptor activation in parts of the mesolimbic system. To characterize P2X/Y Receptor subtypes in the developing dopaminergic system, their expression in organotypic slice co-cultures including the ventral tegmental area/substantia nigra (VTA/SN) complex and the prefrontal cortex (PFC) was studied in comparison to the Receptor expression in 3-5 day-old and adult rats. Reverse transcriptase-polymerase chain reaction (RT-PCR) with specific primers for the P2X(1,2,3,4,6,7) and P2Y(1) Receptors in the tissue extracts of organotypic co-cultures revealed the presence of the P2X and P2Y Receptor mRNAs investigated. Multiple immunofluorescence labeling of the P2X/Y Receptor protein indicated differences in the regional expression in the organotypic co-cultures after 10 days of cultivation (VTA/SN, P2X(1,2,3,4,6,7), P2Y(1,6,12); PFC, P2X(1,3,4,6,7), P2Y(1,2,4,6,12)). At postnatal days 3-5, an immunofluorescence mostly comparable to that of adult rats was observed (VTA/SN and PFC: P2X(1,2,3,4,6,7), P2Y(1,2,4,6,12)). There was one important exception: the P2X(7) Receptor immunocytochemistry was not found in adult tissue, suggesting a potential role of this Receptor in the development. Only few P2 Receptors (e.g. P2X(1), P2Y(1)) were expressed at fibers interconnecting the dopaminergic VTA/SN with the PFC in the organotypic co-cultures. The treatment of the cultures with the ATP analogues 2-methylthio-ATP and alpha,beta-methylene-ATP induced an increase in axonal outgrowth and fiber density, which could be inhibited by pre-treatment with the P2X/Y Receptor antagonist pyridoxal-phosphate-6-azophenyl-2',4'-disulphonic acid. The co-localization of the dopamine-(D1) Receptor with the P2X(1) Receptor in organotypic slice cultures was evident. In the PFC of the co-cultures, and that of young but not adult rats, a number of tyrosine hydroxylase (TH)-positive cells also possessed P2Y(1)-immunoreactivity (IR). Additionally, a strong P2Y(1)-IR was observed on astrocytes. The present results show a time-, region- and cell type-dependent in vitro and in vivo expression pattern of different P2 Receptor subtypes in the dopaminergic system indicating the involvement of ATP and its Receptors in neuronal development and growth.
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Neuroprotective effects of the P2 Receptor antagonist PPADS on focal cerebral ischaemia-induced injury in rats
The European journal of neuroscience, 2006Co-Authors: Alexandra Lämmer, Alexander Beck, Dietmar Schneider, Peter Illes, Ute Krügel, Albrecht Günther, Holger Kittner, Heike FrankeAbstract:After acute injury of the central nervous system extracellular adenosine 5'-triphosphate (ATP) can reach high concentrations as a result of cell damage and subsequent increase in membrane permeability. Released ATP may act as a toxic agent, which causes cellular degeneration and death, mediated through P2X and P2Y Receptors. Mechanisms underlying the various effects of purinoceptor modulators in models of cerebral damage are still uncertain. In the present study the effect of P2 Receptor inhibition after permanent middle cerebral artery occlusion (MCAO) in spontaneously hypertensive rats was investigated. Rats received either the non-selective P2 Receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulphonic acid (PPADS) or artificial cerebrospinal fluid (ACSF) as control by the intracerebroventricular route. First, these treatments were administered 10 min before MCAO and subsequently twice daily for 1 or 7 days after MCAO. The functional recovery of motor and cognitive deficits was tested at an elevated T-labyrinth. The PPADS-treated group showed a significant reduction of paresis-induced sideslips compared with ACSF-treated animals. Infarct volume was reduced in the PPADS group in comparison with the ACSF group. A significant decrease in intermediately and profoundly injured cells in favour of intact cells in the PPADS group was revealed by quantification of celestine blue/acid fuchsin-stained cells in the peri-infarct area. The data provide further evidence for the involvement of P2 Receptors in the pathophysiology of cerebral ischaemia in vivo. The inhibition of P2 Receptors at least partially reduces functional and morphological deficits after an acute cerebral ischaemic event.
Linhua Jiang - One of the best experts on this subject based on the ideXlab platform.
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chemical activation of the piezo1 channel drives mesenchymal stem cell migration via inducing atp release and activation of P2 Receptor purinergic signaling
Stem Cells, 2020Co-Authors: Fatema Mousawi, Hongsen Peng, Sreenivasan Ponnambalam, Sebastien Roger, Hucheng Zhao, Xuebin Yang, Linhua JiangAbstract:In this study, we examined the Ca2+ -permeable Piezo1 channel, a newly identified mechanosensing ion channel, in human dental pulp-derived mesenchymal stem cells (MSCs) and hypothesized that activation of the Piezo1 channel regulates MSC migration via inducing ATP release and activation of the P2 Receptor purinergic signaling. The Piezo1 mRNA and protein were readily detected in hDP-MSCs from multiple donors and, consistently, brief exposure to Yoda1, the Piezo1 channel-specific activator, elevated intracellular Ca2+ concentration. Yoda1-induced Ca2+ response was inhibited by ruthenium red or GsMTx4, two Piezo1 channel inhibitors, and also by Piezo1-specific siRNA. Brief exposure to Yoda1 also induced ATP release. Persistent exposure to Yoda1 stimulated MSC migration, which was suppressed by Piezo1-specific siRNA, and also prevented by apyrase, an ATP scavenger, or PPADS, a P2 generic antagonist. Furthermore, stimulation of MSC migration induced by Yoda1 as well as ATP was suppressed by PF431396, a PYK2 kinase inhibitor, or U0126, an inhibitor of the mitogen-activated protein kinase MEK/ERK signaling pathway. Collectively, these results suggest that activation of the Piezo1 channel stimulates MSC migration via inducing ATP release and subsequent activation of the P2 Receptor purinergic signaling and downstream PYK2 and MEK/ERK signaling pathways, thus revealing novel insights into the molecular and signaling mechanisms regulating MSC migration. Such findings provide useful information for evolving a full understanding of MSC migration and homing and developing strategies to improve MSC-based translational applications.
