1
|
NTPDase and 5'-nucleotidase activities in synaptosomes of rabbits experimentally infected with BoHV-5. J Neurovirol 2015; 21:518-24. [PMID: 26025330 DOI: 10.1007/s13365-015-0349-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 04/21/2015] [Accepted: 04/28/2015] [Indexed: 10/23/2022]
Abstract
Bovine herpesvirus type 5 (BoHV-5) is the causative agent of herpetic meningoencephalitis in cattle. The purinergic system is described as a modulator of the immune response and neuroinflammation. These functions are related to the extracellular nucleotides concentration. NTPDase and 5'-nucleotidase are enzymes responsible for controlling the extracellular concentration of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), and adenosine (ADO). The aim of this study is to determinate the ectonucleotidase activity in cortical synaptosomes and synaptosomes from the hippocampus of rabbits experimentally infected with BoHV-5. Rabbits were divided into four groups, two control groups (non-inoculated animals), and two infected groups (inoculated with BoHV-5). The infected groups received 0.5 ml of BoHV-5 suspension with 10(7.5)TCID50 of viral strain SV-507/99, per paranasal sinuses, and the control groups received 0.5 ml of minimum essential media per paranasal sinuses. Animals were submitted to euthanasia on days 7 and 12 post-inoculation (p.i.); cerebral cortex and hippocampus were collected for the synaptosomes isolation and posterior determination of the ectonucleotidase activities. The results showed a decrease (P < 0.05) in ectonucleotidase activity in synaptosomes from the cerebral cortex of infected rabbits, whereas an increased (P < 0.05) ectonucleotidase activity was observed in synaptosomes from the hippocampus. These differences may be related with the heterogeneous distribution of ectonucleotidases in the different brain regions and also with the viral infectivity. Therefore, it is possible to speculate that BoHV-5 replication results in changes in ectonucleotidase activity in the brain, which may contribute to the neurological signs commonly observed in this disease.
Collapse
|
2
|
Rico EP, Rosemberg DB, Seibt KJ, Capiotti KM, Da Silva RS, Bonan CD. Zebrafish neurotransmitter systems as potential pharmacological and toxicological targets. Neurotoxicol Teratol 2011; 33:608-17. [PMID: 21907791 DOI: 10.1016/j.ntt.2011.07.007] [Citation(s) in RCA: 147] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 05/20/2011] [Accepted: 07/20/2011] [Indexed: 01/23/2023]
Abstract
Recent advances in neurobiology have emphasized the study of brain structure and function and its association with numerous pathological and toxicological events. Neurotransmitters are substances that relay, amplify, and modulate electrical signals between neurons and other cells. Neurotransmitter signaling mediates rapid intercellular communication by interacting with cell surface receptors, activating second messenger systems and regulating the activity of ion channels. Changes in the functional balance of neurotransmitters have been implicated in the failure of central nervous system function. In addition, abnormalities in neurotransmitter production or functioning can be induced by several toxicological compounds, many of which are found in the environment. The zebrafish has been increasingly used as an animal model for biomedical research, primarily due to its genetic tractability and ease of maintenance. These features make this species a versatile tool for pre-clinical drug discovery and toxicological investigations. Here, we present a review regarding the role of different excitatory and inhibitory neurotransmitter systems in zebrafish, such as dopaminergic, serotoninergic, cholinergic, purinergic, histaminergic, nitrergic, glutamatergic, glycinergic, and GABAergic systems, and emphasizing their features as pharmacological and toxicological targets. The increase in the global knowledge of neurotransmitter systems in zebrafish and the elucidation of their pharmacological and toxicological aspects may lead to new strategies and appropriate research priorities to offer insights for biomedical and environmental research.
Collapse
Affiliation(s)
- E P Rico
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica, Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos 2600-Anexo, Porto Alegre, RS, Brazil
| | | | | | | | | | | |
Collapse
|
3
|
Eliahu S, Martín-Gil A, de Lara MJP, Pintor J, Camden J, Weisman GA, Lecka J, Sévigny J, Fischer B. 2-MeS-beta,gamma-CCl2-ATP is a potent agent for reducing intraocular pressure. J Med Chem 2010; 53:3305-19. [PMID: 20337495 PMCID: PMC4358770 DOI: 10.1021/jm100030u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Extracellular nucleotides can modify the production or drainage of the aqueous humor via activation of P2 receptors and therefore affect the intraocular pressure (IOP). We have synthesized slowly hydrolyzable nucleoside di- and triphosphate analogues, 1, and 8-14. Analogues 8-14 were completely resistant to hydrolysis by alkaline phosphatase over 30 min at 37 degrees C. In human blood serum, analogues 8-14 exhibited high stability, e.g., analogues 9 and 10-14 were only 15% and 0% degraded after 24 h, respectively. Moreover, analogues 8-14 were highly stable at pH 1.4 (t(1/2) 1 h-30 days). Analogues 8-14 were agonists of the P2Y(1) receptor (EC(50) 0.57-9.54 muM). Ocular administration of most analogues into rabbits reduced IOP, e.g., analogue 9 reduced IOP by 32% (EC(50) 95.5 nM). Analogue 9 was more effective at reducing IOP than several common glaucoma drugs and represents a promising alternative to timolol maleate, which cannot be used for the treatment of patients suffering from asthma or cardiac problems.
Collapse
Affiliation(s)
- Shay Eliahu
- Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel
| | - Alba Martín-Gil
- Dept. Bioquímica, E.U. Optica, Universidad Complutense de Madrid, c/Arcos de Jalon s/n, E-28037 Madrid, Spain
| | - María Jesús Perez de Lara
- Dept. Bioquímica, E.U. Optica, Universidad Complutense de Madrid, c/Arcos de Jalon s/n, E-28037 Madrid, Spain
| | - Jesús Pintor
- Dept. Bioquímica, E.U. Optica, Universidad Complutense de Madrid, c/Arcos de Jalon s/n, E-28037 Madrid, Spain
| | - Jean Camden
- Biochemistry Department, 540E Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Gary A. Weisman
- Biochemistry Department, 540E Bond Life Sciences Center, University of Missouri, Columbia, Missouri 65211
| | - Joanna Lecka
- Centre de Recherche en Rhumatologie et Immunologie, Centre Hospitalier Universitaire de Québec, Université Laval, Québec, QC, Canada
| | - Jean Sévigny
- Centre de Recherche en Rhumatologie et Immunologie, Centre Hospitalier Universitaire de Québec, Université Laval, Québec, QC, Canada
| | - Bilha Fischer
- Department of Chemistry, Bar-Ilan University, Ramat-Gan 52900, Israel
| |
Collapse
|
4
|
Exercise effects on activities of Na(+),K(+)-ATPase, acetylcholinesterase and adenine nucleotides hydrolysis in ovariectomized rats. Brain Res 2009; 1302:248-55. [PMID: 19748491 DOI: 10.1016/j.brainres.2009.09.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Revised: 08/31/2009] [Accepted: 09/04/2009] [Indexed: 11/22/2022]
Abstract
Hormone deficiency following ovariectomy causes activation of Na(+),K(+)-ATPase and acetylcholinesterase (AChE) that has been related to cognitive deficits in experimental animals. Considering that physical exercise presents neuroprotector effects, we decide to investigate whether exercise training would affect enzyme activation in hippocampus and cerebral cortex, as well as adenosine nucleotide hydrolysis in synaptosomes from cerebral cortex of ovariectomized rats. Female adult Wistar rats were assigned to one of the following groups: sham (submitted to surgery without removal of the ovaries), exercise, ovariectomized (Ovx) and Ovx plus exercise. Thirty days after surgery, animals were submitted to one month of exercise training, three times per week. After, rats were euthanized, blood serum was collected and hippocampus and cerebral cortex were dissected. Data demonstrated that exercise reversed the activation of Na(+),K(+)-ATPase and AChE activities both in hippocampus and cerebral cortex of ovariectomized rats. Ovariectomy decreased AMP hydrolysis in cerebral cortex and did not alter adenine nucleotides hydrolysis in blood serum. Exercise per se decreased ADP and AMP hydrolysis in cerebral cortex. On the other hand, AMP hydrolysis in blood serum was increased by exercise in ovariectomized adult rats. Present data support that physical exercise might have beneficial effects and constitute a therapeutic alternative to hormone replacement therapy for estrogen deprivation.
Collapse
|
5
|
Burnstock G. Purinergic signalling and disorders of the central nervous system. Nat Rev Drug Discov 2008; 7:575-90. [PMID: 18591979 DOI: 10.1038/nrd2605] [Citation(s) in RCA: 446] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Purines have key roles in neurotransmission and neuromodulation, with their effects being mediated by the purine and pyrimidine receptor subfamilies, P1, P2X and P2Y. Recently, purinergic mechanisms and specific receptor subtypes have been shown to be involved in various pathological conditions including brain trauma and ischaemia, neurodegenerative diseases involving neuroimmune and neuroinflammatory reactions, as well as in neuropsychiatric diseases, including depression and schizophrenia. This article reviews the role of purinergic signalling in CNS disorders, highlighting specific purinergic receptor subtypes, most notably A(2A), P2X(4) and P2X(7), that might be therapeutically targeted for the treatment of these conditions.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
| |
Collapse
|
6
|
Effects in vitro of guanidinoacetate on adenine nucleotide hydrolysis and acetylcholinesterase activity in tissues from adult rats. Neurochem Res 2008; 33:1129-37. [PMID: 18256932 DOI: 10.1007/s11064-007-9561-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Accepted: 12/04/2007] [Indexed: 10/22/2022]
Abstract
Guanidinoacetate methyltransferase (GAMT) deficiency is a disorder of creatine metabolism characterized by low plasma creatine concentrations in combination with elevated guanidinoacetate (GAA) concentrations. The aim of this work was to investigate the in vitro effect of guanidinoacetate in NTPDase, 5'-nucleotidase and acetylcholinesterase activities in the synaptosomes, platelets and blood of rats. The results showed that in synaptosomes the NTPDase and 5'-nucleotidase activities were inhibited significantly in the presence of GAA at concentrations of 50, 100, 150 and 200 microM (P < 0.05). However, in platelets GAA at the same concentrations caused a significant increase in the activities of these two enzymes (P < 0.05). In relation to the acetylcholinesterase activity, GAA caused a significant inhibition in the activity of this enzyme in blood at concentrations of 150 and 200 microM (P < 0.05), but did not alter the acetylcholinesterase activity in synaptosomes from the cerebral cortex. Our results suggest that alterations caused by GAA in the activities of these enzymes may contribute to the understanding of the neurological dysfunction of GAMT-deficient patients.
Collapse
|
7
|
Abstract
This review is focused on purinergic neurotransmission, i.e., ATP released from nerves as a transmitter or cotransmitter to act as an extracellular signaling molecule on both pre- and postjunctional membranes at neuroeffector junctions and synapses, as well as acting as a trophic factor during development and regeneration. Emphasis is placed on the physiology and pathophysiology of ATP, but extracellular roles of its breakdown product, adenosine, are also considered because of their intimate interactions. The early history of the involvement of ATP in autonomic and skeletal neuromuscular transmission and in activities in the central nervous system and ganglia is reviewed. Brief background information is given about the identification of receptor subtypes for purines and pyrimidines and about ATP storage, release, and ectoenzymatic breakdown. Evidence that ATP is a cotransmitter in most, if not all, peripheral and central neurons is presented, as well as full accounts of neurotransmission and neuromodulation in autonomic and sensory ganglia and in the brain and spinal cord. There is coverage of neuron-glia interactions and of purinergic neuroeffector transmission to nonmuscular cells. To establish the primitive and widespread nature of purinergic neurotransmission, both the ontogeny and phylogeny of purinergic signaling are considered. Finally, the pathophysiology of purinergic neurotransmission in both peripheral and central nervous systems is reviewed, and speculations are made about future developments.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neurscience Centre, Royal Free and University College Medical School, London, UK.
| |
Collapse
|
8
|
Vlajkovic SM, Wang CJH, Soeller C, Zimmermann H, Thorne PR, Housley GD. Activation-dependent trafficking of NTPDase2 in Chinese hamster ovary cells. Int J Biochem Cell Biol 2007; 39:810-7. [PMID: 17307380 DOI: 10.1016/j.biocel.2007.01.003] [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: 11/03/2006] [Revised: 12/18/2006] [Accepted: 01/02/2007] [Indexed: 11/28/2022]
Abstract
Membrane-bound NTPDase2 is a member of the ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase) enzyme family involved in the regulation of P2 receptor signaling. NTPDase2 has broad substrate specificity for extracellular nucleotides, but hydrolyses nucleoside 5'-triphosphates with high preference over nucleoside 5'-diphosphates. In this study, we have sought to determine how enzyme substrates acting on P2 receptors affect intracellular NTPDase2 trafficking. To achieve this, Chinese hamster ovary (CHO) cells were transiently transfected with rat-specific NTPDase2 cDNA tagged with green fluorescent protein (GFP), to allow direct visualisation of subcellular localisation and trafficking of NTPDase2. Cells were superfused with NTPDase2 substrates (ATP and UTP) and synthetic nucleotide analogues (ATPgammaS and ADPbetaS), and confocal image stacks were acquired at regular time intervals. NTPDase2 incorporation into the plasma membrane was determined by comparative analysis of fluorescence intensity in the cytosolic and membrane compartments. GFP-tagged NTPDase2 was fully functional and ATP and ATPgammaS induced membrane incorporation of GFP-NTPDase2 from putative intracellular stores, whilst UTP and ADPbetaS were ineffective. The increased ATP hydrolysis rate correlated with increased NTPDase2 trafficking to the plasma membrane. ATP-induced NTPDase2 trafficking was mediated by activation of endogenous P2X receptors involving Ca2+ entry rather than by P2Y receptor-induced release of Ca2+ from intracellular stores. Our results suggest that P2X receptor activation stimulates insertion of latent NTPDase2 into the plasma membrane. The increase in surface-located NTPDase2 may reflect a regulatory mechanism counteracting excessive stimulation and desensitisation of P2 receptors.
Collapse
Affiliation(s)
- Srdjan M Vlajkovic
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
| | | | | | | | | | | |
Collapse
|
9
|
Spanevello RMM, Mazzanti CM, Kaizer R, Zanin R, Cargnelutti D, Hannel L, Côrrea M, Mazzanti A, Festugatto R, Graça D, Schetinger MRC, Morsch VM. Apyrase and 5'-nucleotidase activities in synaptosomes from the cerebral cortex of rats experimentally demyelinated with ethidium bromide and treated with interferon-beta. Neurochem Res 2006; 31:455-62. [PMID: 16758353 DOI: 10.1007/s11064-006-9039-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/27/2005] [Indexed: 10/24/2022]
Abstract
Apyrase and 5'-nucleotidase activities were analyzed in an ethidium bromide (EB) demyelinating model associated with interferon-beta (IFN-beta). The animals were divided in groups: I, control (saline); II, saline and IFN-beta; III, EB and IV, EB and IFN-beta. After 7, 15 and 30 days the animals (n = 5) were sacrificed and the cerebral cortex was removed for synaptosome preparation and enzymatic assays. Apyrase activity using ATP as substrate increased in groups II, III and IV (P < 0.001) after 7 days and in groups III and IV (P < 0.001) after 15 days. Using ADP as substrate, an activation of this enzyme was observed in group III (P < 0.05) after seven and 15 days. The 5'-nucleotidase activity increased in group III (P < 0.05) after 7 days and in groups II, III and IV (P < 0.001) after 15 days. After 30 days treatment, no significant alteration was observed in enzyme activities. Results showed that apyrase and 5'-nucleotidase activities are altered in demyelination events and that IFN-beta was able to regulate the adenine nucleotide hydrolysis.
Collapse
Affiliation(s)
- R M M Spanevello
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Campus Universitário, Camobi, RS, Brasil
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Leal DBR, Streher CA, Bertoncheli CDM, Carli LFD, Leal CAM, da Silva JEP, Morsch VM, Schetinger MRC. HIV infection is associated with increased NTPDase activity that correlates with CD39-positive lymphocytes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2005; 1746:129-34. [PMID: 16344116 DOI: 10.1016/j.bbamcr.2005.10.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2005] [Revised: 10/15/2005] [Accepted: 10/26/2005] [Indexed: 11/24/2022]
Abstract
Infection with the human immunodeficiency virus (HIV) results in alterations in immune cells such as an increase or decrease of cytokine secretion and immunodeficiency. HIV causes a state of chronic cellular activation that can induce apoptosis in lymphocyte T-helpers, making the patient susceptive to opportunistic infections. The biochemical mechanisms involved in this immune response to HIV have been researched. Here, we have shown for the first time that ATP and ADP hydrolysis are essential for the immune response to HIV. Our results clearly indicate an increase of NTPDase-1 (EC 3.6.1.5) activity in lymphocytes of HIV-positive patients, confirmed by an enhanced CD39 expression on its surface. These results suggest that NTPDase-1 may be important to keep an adequate balance between the generation and consumption of ATP and to preserve cellular integrity and immune response to the HIV infection.
Collapse
Affiliation(s)
- Daniela B R Leal
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcellos, 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Wang C, Vlajkovic S, Housley G, Braun N, Zimmermann H, Robson S, Sévigny J, Soeller C, Thorne P. C-terminal splicing of NTPDase2 provides distinctive catalytic properties, cellular distribution and enzyme regulation. Biochem J 2005; 385:729-36. [PMID: 15362980 PMCID: PMC1134748 DOI: 10.1042/bj20040852] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The present study provides functional characterization of alternative splicing of the NTPDase2 (ecto-nucleoside triphosphate diphosphohydrolase-2) involved in the regulation of extracellular nucleotide concentrations in a range of organ systems. A novel NTPDase2beta isoform produced by alternative splicing of the rat NTPDase2 gene provides an extended intracellular C-terminus and distinguishes itself from NTPDase2alpha isoform in gaining several intracellular protein kinase CK2 (casein kinase 2) phosphorylation sites and losing the intracellular protein kinase C motif. The plasmids containing NTPDase2alpha or NTPDase2beta cDNA were used to stably transfect Chinese-hamster ovary-S cells. Imaging studies showed that NTPDase2alpha was predominantly membrane-bound, whereas NTPDase2beta had combined cell surface and intracellular localization. alpha and beta isoforms showed variations in divalent cation dependence and substrate specificity for nucleoside-5'-triphosphates and nucleoside-5'-diphosphates. NTPDase2beta exhibited reduced ATPase activity and no apparent ADPase activity. NTPDase2 isoforms demonstrated similar sensitivity to inhibitors such as suramin and pyridoxal phosphate-6-azophenyl-2',4'-disulphonic acid, and differential regulation by protein kinases. NTPDase2beta was up-regulated by intracellular protein kinase CK2 phosphorylation, whereas NTPDase2alpha activity was down-regulated by protein kinase C phosphorylation. The results demonstrate that alternative coding of the intracellular C-terminal domain contributes distinctive phenotypic variation with respect to extracellular nucleotide specificity, hydrolysis kinetics, protein kinase-dependent intracellular regulation and protein trafficking. These findings advance the molecular physiology of this enzyme system by characterizing the contribution of the C-terminal domain to many of the enzyme's signature properties.
Collapse
Affiliation(s)
- Carol J. H. Wang
- *Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Park Road, Grafton, Private Bag 92019, Auckland, New Zealand
| | - Srdjan M. Vlajkovic
- *Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Park Road, Grafton, Private Bag 92019, Auckland, New Zealand
- To whom correspondence should be addressed (email )
| | - Gary D. Housley
- *Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Park Road, Grafton, Private Bag 92019, Auckland, New Zealand
| | - Norbert Braun
- †Biozentrum der J. W. Goethe-Universität, AK Neurochemie, Frankfurt am Main, Germany
| | - Herbert Zimmermann
- †Biozentrum der J. W. Goethe-Universität, AK Neurochemie, Frankfurt am Main, Germany
| | - Simon C. Robson
- ‡Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, U.S.A
| | - Jean Sévigny
- §Centre de Recherche en Rhumatologie et Immunologie, CHUQ, Université Laval, Sainte-Foy, Québec, Canada
| | - Christian Soeller
- *Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Park Road, Grafton, Private Bag 92019, Auckland, New Zealand
| | - Peter R. Thorne
- ∥Discipline of Audiology, Faculty of Medical and Health Sciences, The University of Auckland, Park Road, Grafton, Private Bag 92019, Auckland, New Zealand
| |
Collapse
|
12
|
Senger MR, Rico EP, Dias RD, Bogo MR, Bonan CD. Ecto-5'-nucleotidase activity in brain membranes of zebrafish (Danio rerio). Comp Biochem Physiol B Biochem Mol Biol 2005; 139:203-7. [PMID: 15465666 DOI: 10.1016/j.cbpc.2004.07.011] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Revised: 07/10/2004] [Accepted: 07/14/2004] [Indexed: 01/23/2023]
Abstract
Adenosine, a well-known neuromodulator, may be formed intracellularly in the CNS from degradation of AMP and then exit via bi-directional nucleoside transporters, or extracellularly by the metabolism of released nucleotides. This study reports the enzymatic properties of an ecto-5'-nucleotidase activity in brain membranes of zebrafish (Danio rerio). This enzyme was cation-dependent, with a maximal rate for AMP hydrolysis in a pH range of 7.0-7.5 in the presence of Mg(2+). The enzyme presented a maximal activity for AMP hydrolysis at 37 degrees C. The apparent K(m) and V(max) values for Mg(2+)-AMP were 135.3+/-16 microM and 29+/-4.2 nmol Pi.min(-1).mg(-1) protein, respectively. The enzyme was able to hydrolyze both purine and pyrimidine monophosphate nucleotides, such as UMP, GMP and CMP. Levamisole and tetramisole (1 mM), specific inhibitors of alkaline phosphatases, did not alter the enzymatic activity. However, a significant inhibition of AMP hydrolysis (42%) was observed in the presence of 100 microM alpha,beta-methylene-ADP, a known inhibitor of ecto-5'-nucleotidase. Since 5'-nucleotidase represents the major enzyme responsible for the formation of extracellular adenosine, the enzymatic characterization is important to understand its role in purinergic systems and the involvement of adenosine in the regulation of neurotransmitter release.
Collapse
Affiliation(s)
- Mario Roberto Senger
- Departamento de Ciências Fisiológicas, Laboratório de Pesquisa Bioquímica, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul, Avenida Ipiranga 6681, 90619-900, Porto Alegre, RS, Brazil
| | | | | | | | | |
Collapse
|
13
|
Rücker B, Pereira GS, Fürstenau CR, Izquierdo I, Bonan CD, Sarkis JJF. Inhibitory avoidance task reveals differences in ectonucleotidase activities between male and female rats. Neurochem Res 2005; 29:2231-7. [PMID: 15672544 DOI: 10.1007/s11064-004-7030-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Studies demonstrated that endogenous levels of estrogen affect the long-term potentiation (LTP) and long-term depression (LTD). ATP and adenosine may play a role in the modulation of LTP. Our laboratory observed in previous studies that inhibitory avoidance task is associated with a decrease in hippocampal ectonucleotidase activities in adult male rats. To explore if ectonucleotidases are modulated in memory formation in female rats, as observed in males, we evaluated the effect of inhibitory avoidance training on synaptosomal NTP Dase and 5'-nucleotidase activities in rat hippocampus from both sexes. The results demonstrated a decrease in ATP, ADP and AMP hydrolysis (37%, 38% and 32%, respectively) immediately after training and a significant inhibition only in ATP hydrolysis (36%) 30 min post-training in male rats. There were no changes in ectonucleotidase activities from female rats. These findings provide support for the view that could exist biochemical differences in ectonucleotidase activities between males and females.
Collapse
Affiliation(s)
- Bárbara Rücker
- Departamento de Bioquimica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil
| | | | | | | | | | | |
Collapse
|
14
|
Rücker B, Pochmann D, Fürstenau CR, Carneiro-Ramos MS, Battastini AMO, Barreto-Chaves MLM, Sarkis JJF. Effects of steroid hormones on synaptosomal ectonucleotidase activities from hippocampus and cortex of adult female rats. Gen Comp Endocrinol 2005; 140:94-100. [PMID: 15613271 DOI: 10.1016/j.ygcen.2004.10.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Revised: 10/01/2004] [Accepted: 10/12/2004] [Indexed: 11/24/2022]
Abstract
Over the last few years, the effects of steroid hormones on the brain have been intensively discussed. It has been demonstrated that ATP (acting as a neurotransmitter) is hydrolyzed to adenosine in the synaptic cleft by the conjugated action of ectonucleotidases, which include an enzyme of the E-NTPDase family (NTPDase3, apyrase, EC 3.6.1.5) and a 5'-nucleotidase (EC 3.1.3.5). The 5'-nucleotidase enzyme is able to hydrolyze AMP as well as other monophosphate nucleotides. The importance of this enzyme in the central nervous system is to participate in the adenosine formation, a nucleoside with neuroprotective properties and modulatory effects. However, several questions have been raised about the mechanisms of steroid hormones and the possible neuroprotective effects of estrogen. Thus, we examined the effects of gonadal steroid hormone deprivation, induced by ovary removal (OVX) and estradiol replacement therapy, on the ectonucleotidase activities in synaptosomes from hippocampus and cerebral cortex of adult rats. ATP and ADP hydrolysis in synaptosomes from cerebral cortex and hippocampus did not change as a function of OVX and results demonstrated an increase in AMP hydrolysis (82%) in the animals submitted to OVX in cerebral cortex, but not in hippocampus, when compared to control and sham-operated groups. Estradiol replacement therapy reversed this effect. RT-PCR analysis showed that the enhancement of enzyme activity in cerebral cortex could be explained by the higher expression of 5'-nucleotidase, following OVX. The hormones 17beta-estradiol (cyclodextrin-encapsulated 17beta-estradiol), DHEAS, and pregnenolone (1.0, 2.5, and 5.0 microM) did not alter the nucleotide hydrolysis, in vitro, in synaptosomes from cortex and hippocampus of female adult rats. Results presented, herein, should be considered relevant for hormone replacement therapy, since much controversy exists surrounding this area and the relationship between adenosine and sex steroids is still poorly understood.
Collapse
Affiliation(s)
- Bárbara Rücker
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
| | | | | | | | | | | | | |
Collapse
|
15
|
Alvarado-Castillo C, Harden TK, Boyer JL. Regulation of P2Y1 receptor-mediated signaling by the ectonucleoside triphosphate diphosphohydrolase isozymes NTPDase1 and NTPDase2. Mol Pharmacol 2004; 67:114-22. [PMID: 15496502 DOI: 10.1124/mol.104.006908] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ectonucleoside triphosphate diphosphohydrolases (NTPDases) control the concentration of released extracellular nucleotides, but the precise physiological roles played by these isozymes in modulation of P2 receptor signaling remain unclear. Activation of the human P2Y(1) receptor was studied in the presence of NTPDase1 or NTPDase2 expressed either in the same cell as the receptor or in P2Y(1) receptor-expressing cells cocultured with NTPDaseexpressing cells. Coexpression of NTPDase1 with the P2Y(1) receptor resulted in increases in the EC(50) for 2'-methylthioadenosine 5'-diphosphate (2MeSADP; 12-fold), ADP (50-fold), and ATP (10-fold) for activation of phospholipase C. Similar effects were observed when the P2Y(1) receptor and NTPDase1 were expressed on different cells. These results are explained by the capacity of NTPDase1 to hydrolyze both nucleoside triphosphates and diphosphates. NTPDase2 preferentially hydrolyzes nucleoside triphosphates, and the presence of NTPDase2 under either coexpression or coculture conditions did not change the EC(50) of 2MeSADP, ADP, or adenosine 5'-O-(2-thiodiphosphate) for activation of the P2Y(1) receptor. However, the EC(50) for ATP was 15-fold lower in the presence of NTPDase2 than in cells expressing the P2Y(1) receptor alone. Whereas expression of NTPDase1 decreased basal activity of the P2Y(1) receptor, the presence of the NTPDase2 resulted in P2Y(1) receptor-dependent increases in basal activity. These results suggest that basal activity of the P2Y(1) receptor is maintained by paracrine or autocrine release of receptor agonists and that the biological and/or pharmacological response mediated by P2Y receptors in target tissues is highly dependent on the types of ectonucleotidases expressed in the vicinity of the receptor.
Collapse
Affiliation(s)
- Claudia Alvarado-Castillo
- Department of Pharmacology, University of North Carolina School of Medicine, CB#7365, Chapel Hill, NC 27599-7365, USA
| | | | | |
Collapse
|
16
|
Vlajkovic SM, Housley GD, Muñoz DJB, Robson SC, Sévigny J, Wang CJH, Thorne PR. Noise exposure induces up-regulation of ecto-nucleoside triphosphate diphosphohydrolases 1 and 2 in rat cochlea. Neuroscience 2004; 126:763-73. [PMID: 15183524 DOI: 10.1016/j.neuroscience.2004.04.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/07/2004] [Indexed: 12/01/2022]
Abstract
Extracellular ATP acting via P2 receptors in the inner ear initiates a variety of signaling pathways that may be involved in noise-induced cochlear injury. Nucleoside triphosphate diphosphohydrolase (NTPDase)1/CD39 and NTPDase2/CD39L1 are key elements for regulation of extracellular nucleotide concentrations and P2 receptor signaling in the cochlea. This study characterized the effect of noise exposure on regulation of NTPDase1 and NTPDase2 expression in the cochlea using a combination of real-time RT-PCR, immunohistochemistry and functional studies. Adult Wistar rats were exposed to broad band noise at 90 dB and 110 dB sound pressure level (SPL) for 72 h. Exposure to 90 dB SPL induced a small and temporary change of auditory thresholds (temporary threshold shift), while exposure to 110 dB SPL induced a robust and permanent change of auditory thresholds (permanent threshold shift). NTPDase1 and NTPDase2 mRNA transcripts were upregulated in the cochlea exposed to 110 dB SPL, while mild noise (90 dB SPL) altered only NTPDase1 mRNA expression levels. Changes in NTPDases expression did not correlate with levels of circulating corticosterone, implying that the up-regulation of NTPDases expression was not stress-related. Semi-quantitative immunohistochemistry in the cochlea exposed to 110 dB SPL localized the increased NTPDase1 and NTPDase2 immunostaining in the stria vascularis and up-regulation of NTPDase2 in the intraganglionic spiral bundle. In contrast, NTPDase1 was down-regulated in the cell bodies of the spiral ganglion neurones. Distribution of NTPDases was not altered in the cochlea exposed to 90 dB SPL. Functional studies revealed increased ectonucleotidase activities in the cochlea after exposure to 110 dB SPL, consistent with up-regulation of NTPDases. The changes in NTPDases expression may reflect adaptive response of cochlear tissues to limit ATP signaling during noise exposure.
Collapse
Affiliation(s)
- S M Vlajkovic
- Department of Physiology, Faculty of Medical and Health Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand
| | | | | | | | | | | | | |
Collapse
|
17
|
Rico EP, Senger MR, Fauth MDG, Dias RD, Bogo MR, Bonan CD. ATP and ADP hydrolysis in brain membranes of zebrafish (Danio rerio). Life Sci 2003; 73:2071-82. [PMID: 12899930 DOI: 10.1016/s0024-3205(03)00596-4] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Nucleotides, e.g. ATP and ADP, are important signaling molecules, which elicit several biological responses. The degradation of nucleotides is catalyzed by a family of enzymes called NTPDases (nucleoside triphosphate diphosphohydrolases). The present study reports the enzymatic properties of a NTPDase (CD39, apyrase, ATP diphosphohydrolase) in brain membranes of zebrafish (Danio rerio). This enzyme was cation-dependent, with a maximal rate for ATP and ADP hydrolysis in a pH range of 7.5-8.0 in the presence of Ca(2+) (5 mM). The enzyme displayed a maximal activity for ATP and ADP hydrolysis at 37 degrees C. It was able to hydrolyze purine and pyrimidine nucleosides 5'-di and triphosphates, being insensitive to classical ATPase inhibitors, such as ouabain (1 mM), N-ethylmaleimide (0.1 mM), orthovanadate (0.1 mM) and sodium azide (0.1 mM). A significant inhibition of ATP and ADP hydrolysis (68% and 34%, respectively) was observed in the presence of 20 mM sodium azide, used as a possible inhibitor of ATP diphosphohydrolase. Levamisole (1 mM) and tetramisole (1 mM), specific inhibitors of alkaline phosphatase and P1, P(5)-di (adenosine 5'-) pentaphosphate, an inhibitor of adenylate kinase did not alter the enzyme activity. The presence of a NTPDase in brain membranes of zebrafish may be important for the modulation of nucleotide and nucleoside levels, controlling their actions on specific purinoceptors in central nervous system of this specie.
Collapse
Affiliation(s)
- Eduardo Pacheco Rico
- Departamento de Ciências Fisiológicas, Faculdade de Biociências, Pontifícia Universidade Católica do Rio Grande do Sul. Avenida Ipiranga 6681, 90619-900 RS, Porto Alegre, Brazil
| | | | | | | | | | | |
Collapse
|
18
|
Lunkes GI, Lunkes D, Stefanello F, Morsch A, Morsch VM, Mazzanti CM, Schetinger MRC. Enzymes that hydrolyze adenine nucleotides in diabetes and associated pathologies. Thromb Res 2003; 109:189-94. [PMID: 12757773 DOI: 10.1016/s0049-3848(03)00178-6] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The activities of the enzymes NTPDase (E.C. 3.6.1.5, apyrase, ATP diphosphohydrolase, ecto-CD39) and 5'-nucleotidase (E.C. 3.1.3.5, CD73) were analyzed in platelets of type 2 diabetic, hypertensive and type 2 diabetic/hypertensive patients. The results showed an increase in platelet NTPDase activity in type 2 diabetic (34% and 72%), hypertensive (32% and 70%) and type 2 diabetic/hypertensive patients (30% and 55%) when compared to control (P<.01) with ATP and ADP as substrate, respectively. 5'-Nucleotidase activity was elevated in the hypertensive (60%) and type 2 diabetic/hypertensive (53%) groups when compared to the control and type 2 diabetic group (P<.01). No differences in sensitivity to inhibitors was detected between the platelets of controls and type 2 diabetic/hypertensive patients. No effects on the enzyme activities were observed when pharmacological doses of propranolol, captopril, furosemide, chlorpropamide, acetylsalicylic acid and glibenclamide were administered. Furthermore, changes in platelet adhesiveness and reactivity were found in all groups tested. In conclusion, we may postulate that NTPDase and 5'-nucleotidase from platelets are altered in patients with type 2 diabetes and hypertension. Probably, such alterations are involved in compensatory physiological responses in these diseases and are related to other important mechanisms of thromboregulation.
Collapse
Affiliation(s)
- Gilberto Inácio Lunkes
- Departamento de Química, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil
| | | | | | | | | | | | | |
Collapse
|