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Authi KS, Khan S, Gibbins JM, Brain SD. Evidence that inositol 1,4,5-trisphosphate 3-kinase and inositol 1,3,4,5-tetrakisphosphate are negative regulators of platelet function. Res Pract Thromb Haemost 2024; 8:102326. [PMID: 38404940 PMCID: PMC10885593 DOI: 10.1016/j.rpth.2024.102326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 12/21/2023] [Accepted: 01/03/2024] [Indexed: 02/27/2024] Open
Abstract
Background Inositol 1,3,4,5-tetrakisphosphate (IP4) is formed from inositol 1,4,5-trisphosphate (IP3) by IP3 3-kinase (ITPK) in most cells. Its function is unknown but has been suggested to be involved in Ca2+ entry, IP3 regulation, and phosphoinositide 3-kinase antagonism. Objectives To better elucidate a function for IP4, we tested a specific inhibitor of ITPK (GNF362) on platelets, the effects of IP4 directly in permeabilized platelets and its effect on phosphatidylinositol 3,4,5-trisphosphate (PIP3) binding to pleckstrin-homology (PH) domain-containing proteins in platelets. Methods Human platelets were utilized in whole blood for thrombus formation, in platelet-rich plasma and washed suspensions for aggregation, and for Ca2+ studies, or resuspended in high K+ and low Na+ buffers for permeabilization experiments. Phosphorylation of AKT-Ser473 and Rap1-GTP formation were measured by Western blotting and PIP3 binding using PIP3 beads. Results GNF362-enhanced platelet aggregation stimulated by low concentrations of ADP, collagen, thrombin, U46619, and thrombus formation in collagen-coated capillaries. GNF362 induced a transient elevation of Ca2+ concentration, elevated basal levels of IP3, and enhanced the peak height of Ca2+ elevated by agonists. In permeabilized platelets, IP4 inhibited GTPγS induced formation of AKT-Ser473 phosphorylation and platelet aggregation. IP4 reduced GTPγS-stimulated Rap1-GTP levels and potently reduced extraction of RASA3 and BTK by PIP3 beads. Conclusion ITPK and IP4 are negative regulators of platelet function. IP4 regulation of PH domain-containing proteins may represent a pathway by which platelet activation may be controlled during thrombosis.
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Affiliation(s)
- Kalwant S. Authi
- School of Cardiovascular and Metabolic Medicine and Sciences, BHF Centre for Research Excellence, London, UK
| | - Sabeeya Khan
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Jonathan M. Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Susan D. Brain
- School of Cardiovascular and Metabolic Medicine and Sciences, BHF Centre for Research Excellence, London, UK
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Savitha B, Kumar P, Pretty MA, Naijil G, Paulose CS. Muscarinic M₁, M₃ receptor modulation in the corpus striatum of streptozotocin induced diabetic rats as a function of age. J Pharm Pharmacol 2010; 62:1768-75. [PMID: 21054404 DOI: 10.1111/j.2042-7158.2010.01194.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES In this study we have investigated muscarinic M₁, M₃ receptor kinetics and the functional role of IP3 and cGMP in the corpus striatum of both young and old diabetic and insulin-treated diabetic rats. METHODS Radioreceptor binding assays was done in the corpus striatum using specific antagonists QNB and DAMP. IP3 and cGMP assay using [3H]IP3 and [3H]cGMP Biotrak assay system kits. KEY FINDINGS M₁ receptor increased and M₃ receptor decreased in control old rats when compared with young control rats. In young diabetic groups M₁ receptor increased and M₃ receptor decreased. Old diabetic groups showed reversed M₁ and M₃ receptors compared with their controls. IP3 and cGMP content increased in old control rats compared with young control rats. IP3 content increased in young diabetic rats and decreased in old diabetic rats. cGMP content was increased significantly in both young and old diabetic groups. Insulin treatment reversed these altered parameters near to control. CONCLUSIONS Our studies showed that M₁ and M₃ receptors, IP3 and cGMP were functionally regulated during diabetes as function of age, which will have immense clinical significance.
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Affiliation(s)
- Balakrishnan Savitha
- Molecular Neurobiology and Cell Biology Unit, Centre for Neuroscience, Department of Biotechnology, Cochin University of Science and Technology, Cochin, Kerala, India
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The effects of hypoxia/reoxygenation on the physiological behaviour of U373-MG astrocytes. Neurochem Res 2009; 35:42-9. [PMID: 19582572 DOI: 10.1007/s11064-009-0028-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Accepted: 06/17/2009] [Indexed: 02/03/2023]
Abstract
Nerve cells are very susceptible to hypoxia responsive for mitochondrial dysfunctions involved in the subsequent oxidative stress, apoptosis and necrosis. In this paper, we examined the effect of 12 h incubation of U-373 MG astrocytes in hypoxic environment (73% N(2): 2% O(2): 5% CO(2), v:v) by evaluating cell proliferation, modifications of NO and ATP production, intracellular Ca(2+) concentration [Ca(2+)](i), membrane potential, desferoxamine-chelatable free iron, esterified F2-isoprostanes levels and the production of phosphorylated ERK. The same parameters were evaluated also after a following re-oxygenation period of 24 h. Immediately after hypoxia the NO concentration increased significantly and returned to values similar to those of controls after the re-oxygenation period. At the same time, ATP levels remained similar to controls and the cell proliferation significantly decreased. This involved a significant increase of [Ca(2+)](i) immediately after hypoxia and the value remained significantly elevated after the following re-oxygenation period. Moreover, after hypoxia, astrocytes were slightly although not significantly depolarized. Indeed iron and F2-isoprostanes levels increased significantly after hypoxia. Finally ERK proteins increased slowly and not significantly after hypoxia and the same trend was observed after the re-oxygenation period. On the whole, our results indicate that 2% O(2) hypoxia induces a moderate oxidative stress, well tolerated by U-373 MG cells, remaining the ATP production, mitochondrial membrane potential and activated ERK proteins, similar to the values of controls.
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Mazars C, Bourque S, Mithöfer A, Pugin A, Ranjeva R. Calcium homeostasis in plant cell nuclei. THE NEW PHYTOLOGIST 2009; 181:261-274. [PMID: 19130634 DOI: 10.1111/j.1469-8137.2008.02680.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
In plant cells, calcium-based signaling pathways are involved in a large array of biological processes, including cell division, polarity, growth, development and adaptation to changing biotic and abiotic environmental conditions. Free calcium changes are known to proceed in a nonstereotypical manner and produce a specific signature, which mirrors the nature, strength and frequency of a stimulus. The temporal aspects of calcium signatures are well documented, but their vectorial aspects also have a profound influence on biological output. Here, we will focus on the regulation of calcium homeostasis in the nucleus. We will discuss data and present hypotheses suggesting that, while interacting with other organelles, the nucleus has the potential to generate and regulate calcium signals on its own.
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Affiliation(s)
- Christian Mazars
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
| | - Stéphane Bourque
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
| | - Axel Mithöfer
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
| | - Alain Pugin
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
| | - Raoul Ranjeva
- UMR CNRS 5546/Université de Toulouse, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, BP 42617 Auzeville, 31326 Castanet-Tolosan cédex, France;UMR INRA 1088/CNRS 5184/Université de Bourgogne Plante-Microbe-Environnement, 17 Rue Sully, BP 86510, 21065 Dijon cédex, France;Max Planck Institute for Chemical Ecology, Department Bioorganic Chemistry, Hans-Knöll-Str. 8, 07745 Jena, Germany;GDR CNRS Calcium et Régulation des Gènes, 118 route de Narbonne, 31062 Toulouse cédex, France
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Vibert YM, Ashraf QM, Mishra OP, Delivoria-Papadopoulos M. Mechanism of Ca2+-influx and Ca2+/calmodulin-dependent protein kinase IV activity during in utero hypoxia in cerebral cortical neuronal nuclei of the guinea pig fetus at term. Neurosci Lett 2008; 440:227-31. [PMID: 18571321 DOI: 10.1016/j.neulet.2008.05.095] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Revised: 05/22/2008] [Accepted: 05/24/2008] [Indexed: 10/22/2022]
Abstract
Previously we showed that following hypoxia there is an increase in nuclear Ca(2+)-influx and Ca(2+)/calmodulin-dependent protein kinase IV activity (CaMK IV) in the cerebral cortex of term guinea pig fetus. The present study tests the hypothesis that clonidine administration will prevent hypoxia-induced increased neuronal nuclear Ca(2+)-influx and increased CaMK IV activity, by blocking high-affinity Ca(2+)-ATPase. Studies were conducted in 18 pregnant guinea pigs at term, normoxia (Nx, n=6), hypoxia (Hx, n=6) and clonidine with Hx (Hx+Clo, n=6). The pregnant guinea pig was exposed to a decreased FiO(2) of 0.07 for 60 min. Clonidine, an imidazoline inhibitor of high-affinity Ca(2+)-ATPase, was administered 12.5 microg/kg IP 30 min prior to hypoxia. Hypoxia was determined biochemically by ATP and phosphocreatine (PCr) levels. Nuclei were isolated and ATP-dependent (45)Ca(2+)-influx was determined. CaMK IV activity was determined by (33)P-incorporation into syntide 2 for 2 min at 37 degrees C in a medium containing 50mM HEPES (pH 7.5), 2mM DTT, 40muM syntide 2, 0.2mM (33)P-ATP, 10mM magnesium acetate, 5 microM PKI 5-24, 2 microM PKC 19-36 inhibitor peptides, 1 microM microcystine LR, 200 microM sodium orthovanadate and either 1mM EGTA (for CaMK IV-independent activity) or 0.8mM CaCl(2) and 1mM calmodulin (for total activity). ATP (mumoles/gbrain) values were significantly different in the Nx (4.62+/-0.2), Hx (1.65+/-0.2, p<0.05 vs. Nx), and Hx+Clo (1.92+/-0.6, p<0.05 vs. Nx). PCr (mumoles/g brain) values in the Nx (3.9+/-0.1), Hx (1.10+/-0.3, p<0.05 vs. Nx), and Hx+Clo (1.14+/-0.3, p<0.05 vs. Nx). There was a significant difference between nuclear Ca(2+)-influx (pmoles/mg protein/min) in Nx (3.98+/-0.4), Hx (10.38+/-0.7, p<0.05 vs. Nx), and Hx+Clo (7.35+/-0.9, p<0.05 vs. Nx, p<0.05 vs. Hx), and CaM KIV (pmoles/mg protein/min) in Nx (1314.00+/-195.4), Hx (2315.14+/-148.5, p<0.05 vs. Nx), and Hx+Clo (1686.75+/-154.3, p<0.05 vs. Nx, p<0.05 vs. Hx). We conclude that the mechanism of hypoxia-induced increased nuclear Ca(2+)-influx is mediated by high-affinity Ca(2+)-ATPase and that CaMK IV activity is nuclear Ca(2+)-influx-dependent. We speculate that hypoxia-induced alteration of high-affinity Ca(2+)-ATPase is a key step that triggers nuclear Ca(2+)-influx, leading to CREB protein-mediated increased expression of apoptotic proteins and hypoxic neuronal death.
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Affiliation(s)
- Yanick M Vibert
- Department of Pediatrics, Drexel University College of Medicine and St. Christopher's Hospital for Children, Philadelphia, PA 19102, United States.
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Chiang MC, Ashraf QM, Ara J, Mishra OP, Delivoria-Papadopoulos M. Mechanism of caspase-3 activation during hypoxia in the cerebral cortex of newborn piglets. Neurosci Lett 2007; 421:67-71. [PMID: 17553617 DOI: 10.1016/j.neulet.2007.05.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2007] [Revised: 05/16/2007] [Accepted: 05/16/2007] [Indexed: 11/18/2022]
Abstract
We have previously shown that the activity and the expression of caspase-9 and caspase-3 were increased during hypoxia in the cerebral cortex of newborn piglets. The present study was conducted to test the hypothesis that the hypoxia-induced activation of caspase-3 in the cerebral cortex of newborn piglets is mediated by caspase-9. Twenty-two newborn piglets were randomly assigned to four groups: normoxic (Nx), normoxic pretreated with a selective caspase-9 inhibitor, Z-Leu-Glu(OMe)-His-Asp(OMe)-Fluoromethyl ketone (Z-LEHD-FMK) (Nx+LEHD), hypoxic (Hx), and hypoxic pretreated with Z-LEHD-FMK (Hx+LEHD). Cerebral tissue hypoxia was confirmed biochemically by measuring ATP and phosphocreatine. Caspase-9 and -3 activities were determined spectrofluorometrically. The expression of caspase-9 and -3 proteins was measured by Western blot analysis using active enzyme specific antibodies. Cytosolic caspase-9 activity (nmol/mg protein/h) was 3.70+/-0.40 in Nx, 3.56+/-0.31 in Nx+LEHD (p=NS versus Nx), 4.99+/-0.64 in Hx (p<0.05 versus Nx), and 3.73+/-0.80 in Hx+LEHD (p<0.05 versus Hx, p=NS versus Nx). Cytosolic caspase-3 activity (nmol/mg protein/h) was 7.80+/-1.17 in Nx, 8.15+/-0.87 in Nx+LEHD (p=NS versus Nx), 13.07+/-0.78 in Hx (p<0.05 versus Nx), and 10.05+/-2.09 in Hx+LEHD (p<0.05 versus Hx) The density (ODxmm(2)) of active caspase-9 protein was 18.52+/-1.89 in Nx, 20.53+/-1.12 in Nx+LEHD (p=NS versus Nx), 32.36+/-5.03 in Hx (p<0.05 versus Nx), and 19.94+/-3.59 in Hx+LEHD (p<0.05 versus Hx, p=NS versus Nx). The density (ODxmm(2)) of active caspase-3 protein was 55.87+/-8.73 in Nx, 55.69+/-8.18 in Nx+LEHD (p=NS versus Nx), 94.10+/-12.05 in Hx (p<0.05 versus Nx), and 56.12+/-14.56 in Hx+LEHD (p<0.05 versus Hx, p=NS versus Nx). These data show that administration of a selective caspase-9 inhibitor, Z-LEHD-FMK, prior to hypoxia prevents the hypoxia-induced increase in caspase-3 activity and the expression of active caspase-3 protein. We conclude that the hypoxia-induced activation of caspase-3 during hypoxia in the cerebral cortex of newborn piglets is mediated by caspase-9.
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Affiliation(s)
- Ming-Chou Chiang
- Department of Pediatrics, Chang Gung University College of Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan.
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7
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Hornick K, Chang E, Zubrow AB, Mishra OP, Delivoria-Papadopoulos M. Mechanism of Ca(2+)/calmodulin-dependent protein kinase IV activation and of cyclic AMP response element binding protein phosphorylation during hypoxia in the cerebral cortex of newborn piglets. Brain Res 2007; 1150:40-5. [PMID: 17428448 DOI: 10.1016/j.brainres.2007.02.079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 02/15/2007] [Accepted: 02/28/2007] [Indexed: 11/30/2022]
Abstract
Previously we showed that hypoxia results in increased neuronal nuclear Ca(2+) influx, Ca(2+)/calmodulin-dependent protein kinase IV activity (CaM KIV) and phosphorylation of c-AMP response element binding (CREB) protein. The aim of the present study was to understand the importance of neuronal nuclear Ca(2+) in the role of CaM KIV activation and CREB protein phosphorylation associated with hypoxia. To accomplish this the present study tests the hypothesis that clonidine administration will block increased nuclear Ca(2+) influx by inhibiting high affinity Ca(2+)/ATPase and prevent increased CaM KIV activity and CREB phosphorylation in the neuronal nuclei of the cerebral cortex of hypoxic newborn piglets. To accomplish this piglets were divided in three groups: normoxic, hypoxic, and hypoxic-treated with clonidine. The piglets that were in the Hx+Cl group received clonidine 5 min prior to hypoxia. Cerebral tissue hypoxia was confirmed biochemically by tissue levels of ATP and phosphocreatine (PCr). The data show that clonidine prevents hypoxia-induced increase in CaM KIV activity and CREB protein phosphorylation. We conclude that the mechanism of hypoxia-induced activation of CaM KIV and CREB phosphorylation is nuclear Ca(2+) influx mediated. We speculate that nuclear Ca(2+) influx is a key step that triggers CREB mediated transcription of apoptotic proteins and hypoxic mediated neuronal death.
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Affiliation(s)
- Kristie Hornick
- Drexel University College of Medicine Division of Neonatology Department of Pediatrics Mail Stop 1029 245 N, 15th Street Philadelphia, PA 19102, USA.
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8
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Zhu T, Gobeil F, Vazquez-Tello A, Leduc M, Rihakova L, Bossolasco M, Bkaily G, Peri K, Varma DR, Orvoine R, Chemtob S. Intracrine signaling through lipid mediators and their cognate nuclear G-protein-coupled receptors: a paradigm based on PGE2, PAF, and LPA1 receptors. Can J Physiol Pharmacol 2006; 84:377-91. [PMID: 16902584 DOI: 10.1139/y05-147] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Prostaglandins (PGs), platelet-activating factor (PAF), and lysophosphatidic acid (LPA) are ubiquitous lipid mediators that play important roles in inflammation, cardiovascular homeostasis, and immunity and are also known to modulate gene expression of specific pro-inflammatory genes. The mechanism of action of these lipids is thought to be primarily dependent on their specific plasma membrane receptors belonging to the superfamily of G-protein-coupled receptors (GPCR). Increasing evidence suggests the existence of a functional intracellular GPCR population. It has been proposed that immediate effects are mediated via cell surface receptors whereas long-term responses are dependent upon intracellular receptor effects. Indeed, receptors for PAF, LPA, and PGE(2) (specifically EP(1), EP(3), and EP(4)) localize at the cell nucleus of cerebral microvascular endothelial cells of newborn pigs, rat hepatocytes, and cells overexpressing each receptor. Stimulation of isolated nuclei with these lipids reveals biological functions including transcriptional regulation of major genes, namely c-fos, cylooxygenase-2, and endothelial as well as inducible nitric oxide synthase. In the present review, we shall focus on the nuclear localization and signaling of GPCRs recognizing PGE(2), PAF, and LPA phospholipids as ligands. Mechanisms on how nuclear PGE2, PAF, and LPA receptors activate gene transcription and nuclear localization pathways are presented. Intracrine signaling for lipid mediators uncover novel pathways to elicit their effects; accordingly, intracellular GPCRs constitute a distinctive mode of action for gene regulation.
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Affiliation(s)
- Tang Zhu
- Department of Pediatrics, Research Center of Hôpital Sainte-Justine, Université de Montréal, QC, Canada
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Valencia I, Mishra OP, Fritz K, Zubrow A, Katsetos CD, Delivoria-Papadopoulos M, Legido A. Increased neuronal nuclear calcium influx in neonatal seizures. Neurochem Res 2006; 31:1231-7. [PMID: 17004131 DOI: 10.1007/s11064-006-9150-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 08/24/2006] [Indexed: 12/13/2022]
Abstract
We hypothesized that neonatal seizures lead to increased Ca(2+) influx (nCa(2+)I) in neuronal nuclei of newborn rats and that such increase is nitric-oxide mediated. Neuronal nuclear (45)Ca(2+) influx (nCa(2+)I) was measured in neuronal nuclei of 25 10-day-old male rat-pups newborn brains. They were divided into five groups (n = 5/group). (I) control; (II) hypoxia without seizures; (III) hypoxia with seizures; (IV) kainate, 2 mg/kg intraperitoneal (i.p.)-induced seizures and (V) 7-nitroindazole (7-NINA), 1 mg/kg i.p. pretreated, kainate-induced seizures. nCa(2+)I was significantly (P < 0.05) increased following hypoxia or seizures (hypoxic- or kainate-induced). Post-hypoxic seizures further enhanced nCa(2+)I increase induced by hypoxia (P < 0.05). 7-NINA abated the nCa(2+)I increase induced by kainate. We conclude that (1) kainate or hypoxia-induced seizures in newborn rats modify the neuronal nuclear membrane function, resulting in increased nCa(2+)I, (2) seizures exacerbate the hypoxia-induced increased nCa(2+)I incurred after hypoxia and (3) intranuclear calcium surges during kainate-induced neonatal seizures are nitric oxide-mediated.
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Affiliation(s)
- Ignacio Valencia
- Section of Neurology, Department of Pediatrics, St. Christopher's Hospital for Children, Drexel University College of Medicine, Erie Avenue at Front Street, Philadelphia, PA 19134, USA.
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Mami AG, Ballesteros J, Mishra OP, Delivoria-Papadopoulos M. Effects of magnesium sulfate administration during hypoxia on Ca(2+) influx and IP(3) receptor modification in cerebral cortical neuronal nuclei of newborn piglets. Neurochem Res 2006; 31:63-70. [PMID: 16474998 DOI: 10.1007/s11064-005-9076-5] [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] [Accepted: 10/12/2005] [Indexed: 11/28/2022]
Abstract
Magnesium is a non-competitive antagonist of the NMDA receptor. Hypoxic insults to the brain are associated with a significant increase in the intranuclear Ca(2+) due to altered nuclear membrane Ca(2+) influx mechanisms including hypoxia-induced modifications of nuclear membrane IP(3) receptors. In this study we have examined the effects of magnesium sulfate administration to newborn piglets subjected to normoxia and severe hypoxia. The animals were randomly divided into normoxic (n=4), hypoxic (n=4) and magnesium sulfate treated hypoxic (n=4) groups. Hypoxia was confirmed biochemically by measuring ATP and phosphocreatine (PCr) levels in the brain tissue. Intranuclear Ca(2+) influx was assessed by measuring (45)Ca(2+) uptake. Results show a significant (P<0.05) decrease in ATP and PCr levels in hypoxic group in comparison with normoxia. On the other hand magnesium-treated hypoxic group showed a significantly (P<0.05) higher ATP and PCr in comparison with the hypoxic group. Intranuclear Ca(2+) was significantly (P<0.05) higher in the hypoxic group in comparison with both normoxic and magnesium-treated hypoxic groups. In addition results show that magnesium prevented hypoxia-induced modification of the IP(3) receptor. Magnesium treatment significantly reduced the hypoxia-induced increase in the number of receptors (reduced B(max) --P<0.05-treated hypoxia vs. hypoxia and normoxia), and reversed the receptor affinity (reduced dissociation coefficient-K(d)--P<0.05-treated hypoxia vs. normoxia). The results demonstrate that the administration of magnesium sulfate prior to hypoxia prevents the hypoxia-induced increase in intranuclear Ca(2+) and IP(3) receptor modifications. We conclude that Mg(2+ )administration prevents hypoxia-induced modification of neuronal nuclear membrane function that leads to intranuclear Ca(2+)-dependent transcription of apoptotic proteins leading to hypoxic neuronal programmed cell death.
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Affiliation(s)
- Ahmed G Mami
- Department of Pediatric Surgery, Drexel University College of Medicine, Philadelphia, PA 19129, USA.
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Aldinucci C, Carretta A, Pessina GP. The effect of mild and severe hypoxia on rat cortical synaptosomes. Neurochem Res 2006; 30:981-7. [PMID: 16258847 DOI: 10.1007/s11064-005-6529-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2005] [Indexed: 11/30/2022]
Abstract
Brain ischemia results in neuronal injury and neurological disability. The present study examined the effect of mild (6% O2) and severe (2% O2) hypoxia on mitochondria of rat cortical synaptosomes. During mild and severe hypoxia, JO2 and ATP production significantly decreased and mitochondrial membranes depolarized. Synaptosomal calcium concentration increased slightly, albeit not significantly. After a 1 h re-oxygenation period, JO2, ATP production and mitochondrial membrane potential returned to control levels in synaptosomes incubated in 6% O2. In synaptosomes incubated in 2% O2, however, the ATP production was not restored after re-oxygenation and intrasynaptosomal Ca2+ significantly increased. The results indicate that both mild and severe hypoxia influence the physiology of synaptosomal mitochondria; the modifications are reversible after mild hypoxia and but partly irreversible after severe hypoxia.
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Affiliation(s)
- C Aldinucci
- Department of Physiology, University of Siena, 53100, Siena, Italy
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Lin WH, Wang Y, Mueller-Roeber B, Brearley CA, Xu ZH, Xue HW. At5PTase13 modulates cotyledon vein development through regulating auxin homeostasis. PLANT PHYSIOLOGY 2005; 139:1677-91. [PMID: 16299182 PMCID: PMC1310551 DOI: 10.1104/pp.105.067140] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Phosphatidylinositol signaling pathway and the relevant metabolites are known to be critical to the modulation of different aspects of plant growth, development, and stress responses. Inositol polyphosphate 5-phosphatase is a key enzyme involved in phosphatidylinositol metabolism and is encoded by an At5PTase gene family in Arabidopsis thaliana. A previous study shows that At5PTase11 mediates cotyledon vascular development probably through the regulation of intracellular calcium levels. In this study, we provide evidence that At5PTase13 modulates the development of cotyledon veins through its regulation of auxin homeostasis. A T-DNA insertional knockout mutant, At5pt13-1, showed a defect in development of the cotyledon vein, which was rescued completely by exogenous auxin and in part by brassinolide, a steroid hormone. Furthermore, the mutant had reduced auxin content and altered auxin accumulation in seedlings revealed by the DR5:beta-glucuronidase fusion construct in seedlings. In addition, microarray analysis shows that the transcription of key genes responsible for auxin biosynthesis and transport was altered in At5pt13-1. The At5pt13-1 mutant was also less sensitive to auxin inhibition of root elongation. These results suggest that At5PTase13 regulates the homeostasis of auxin, a key hormone controlling vascular development in plants.
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Affiliation(s)
- Wen-Hui Lin
- National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 200032 Shanghai, People's Republic of China
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Marrache AM, Gobeil F, Zhu T, Chemtob S. Intracellular signaling of lipid mediators via cognate nuclear G protein-coupled receptors. ACTA ACUST UNITED AC 2005; 12:63-72. [PMID: 16036317 DOI: 10.1080/10623320590933815] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Platelet-activating factor (PAF) and lysophosphatidic acid (LPA) are ubiquitous lipid mediators that play important roles in inflammation, cardiovascular homeostasis, and immunity and are also known to modulate gene expression of specific proinflammatory genes. The mechanism of action of these phospholipids is thought to be primarily dependent on their specific plasma membrane receptors belonging to the superfamily of G protein-coupled receptors (GPCRs). However, increasing evidence suggests the existence of a functional intracellular GPCR population. It has been suggested that immediate effects are mediated by cell surface receptors, whereas long-term responses are mediated by intracellular receptors. PAF and LPA(1) receptors localize at the cell nucleus of cerebral microvascular endothelial cells of newborn pig, rat hepatocytes, and cells overexpressing each receptor, and stimulation of isolated nuclei reveal biological functions, including transcriptional regulation of major genes, namely cylooxygenase-2 and inducible nitric oxide synthase. This mini review focuses on the nuclear localization and signaling of GPCRs, recognizing PAF and LPA phospholipids as ligands. Theories on how nuclear PAF and LPA1 receptors activate gene transcription and nuclear localization pathways are discussed. Intracrine signaling for lipid mediators uncover novel pathways to elicit their effects; moreover, intracellular GPCRs constitute a distinctive mode of action for gene regulation.
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Abedin N, Ashraf Q, Mishra OP, Delivoria-Papadopoulos M. Effect of hypoxia on the expression of pro- and anti-apoptotic proteins in neuronal nuclei of the guinea pig fetus during gestation. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2005; 156:32-7. [PMID: 15862625 DOI: 10.1016/j.devbrainres.2005.01.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Revised: 01/24/2005] [Accepted: 01/26/2005] [Indexed: 01/03/2023]
Abstract
The present study investigates the expression of apoptotic proteins Bax, Bad, Bcl-2, and Bcl-xl following hypoxia in the cerebral cortex of the guinea pig fetus as a function of gestational age. Normoxic (Nx, n = 6) and hypoxic (Hx, n = 6) guinea pig fetuses at 35 and 60 days gestation were studied. Bax expression (OD X mm(2)) was 96.9 +/- 9.5 (Nx 35 days), 116.5 +/- 8.3 (Hx 35 days), P < 0.05 and 116.2 +/- 3.4 (Nx 60 days, 144.6 +/- 11.7 (Hx 60 days), P < 0.05. Bad expression (OD X mm(2)) was 78.6 +/- 2.6 (Nx 35 days), 102.9 +/- 5.8 (Hx 35 days), P < 0.05 and 101.5 +/- 4.3 (Nx 60 days), 139.8 +/- 7.9 (Hx 60 days), P < 0.05 vs. Nx 60 days, also significantly higher from preterm hypoxia P < 0.007. Expression of Bcl-2 (OD X mm(2)) was 27.4 +/- 2.0 (Nx 35 days), 28.0 +/- 2.4 (Hx 35 days), and 27.4 +/- 2.7 (Nx 60 days), 29.7 +/- 2.3 (Hx 60 days). Expression of Bcl-xl (OD X mm(2)) was 51.0 +/- 4.4 (Nx 35 days), 46.1 +/- 8.0 (Hx 35 days) and 50.0 +/- 1.4 (Nx 60 days), 54.9 +/- 7.4 (Hx 60 days). Hypoxia resulted in increased expression of the proapoptotic proteins Bax and Bad by 20% and 30% in the preterm as compared to 24% and 38% at term, without altering the expression of anti-apoptotic proteins Bcl-2 and Bcl-xl. We conclude that the hypoxia-induced increased expression of Bax and Bad is greater at term compared to preterm. Furthermore, the hypoxia-induced increase in proapoptotic as compared to antiapoptotic proteins at term will accelerate the ongoing active process of programmed cell death at term compared to preterm gestation.
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Affiliation(s)
- Naheed Abedin
- Drexel University College of Medicine, MCP Hospital, Neonatal Research, 3300 Henry Avenue Philadelphia, PA 19133, USA.
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