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Nazario LR, de Sousa JS, de Moraes Silveira FS, Costa KM, de Oliveira GMT, Bogo MR, da Silva RS. Participation of ecto-5'-nucleotidase in the inflammatory response in an adult zebrafish (Danio rerio) model. Comp Biochem Physiol C Toxicol Pharmacol 2022; 260:109402. [PMID: 35779837 DOI: 10.1016/j.cbpc.2022.109402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 06/20/2022] [Accepted: 06/26/2022] [Indexed: 11/17/2022]
Abstract
The ecto-5'-nucleotidase is an important source of adenosine in the extracellular medium. Adenosine modulation appears early in evolution and performs several biological functions, including a role as an anti-inflammatory molecule. Here, we evaluate the activity and mRNA expression of ecto-5'-nucleotidase in response to lipopolysaccharide (LPS) using zebrafish as a model. Adult zebrafish were injected with LPS (10 μg/g). White blood cell differential counts, inflammatory markers, and ecto-5'-nucleotidase activity and expression in the encephalon, kidney, heart, and intestine were evaluated at 2, 12, and 24 h post-injection (hpi). At 2 hpi of LPS, an increase in neutrophils and monocytes in peripheral blood was observed, which was accompanied by increased tnf-α expression in the heart, kidney, and encephalon, and increased cox-2 expression in the intestine and kidney. At 12 hpi, monocytes remained elevated in the peripheral blood, while tnf-α expression was also increased in the intestine. At 24 hpi, the white blood cell differential count no longer differed from that of the control, whereas tnf-α expression remained elevated in the encephalon but reduced in the kidney compared with the controls. AMP hydrolysis in LPS-treated animals was increased in the heart at 24 hpi [72 %; p = 0.029] without affecting ecto-5'-nucleotidase gene expression. These data indicate that, in most tissues studied, inflammation does not affect ecto-5'-nucleotidase activity, whereas in the heart, a delayed increase in ecto-5'-nucleotidase activity could be related to tissue repair.
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Affiliation(s)
- Luiza Reali Nazario
- Laboratório de Neuroquímica e Psicofarmacologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Avenida Ipiranga, 6681, Caixa Postal 1429, 90619-900 Porto Alegre, RS, Brazil
| | - Jéssica Streb de Sousa
- Laboratório de Neuroquímica e Psicofarmacologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Avenida Ipiranga, 6681, Caixa Postal 1429, 90619-900 Porto Alegre, RS, Brazil
| | - Francielle Schroeder de Moraes Silveira
- Laboratório de Neuroquímica e Psicofarmacologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Avenida Ipiranga, 6681, Caixa Postal 1429, 90619-900 Porto Alegre, RS, Brazil
| | - Kesiane Mayra Costa
- Laboratório de Biologia Genômica e Molecular, Escola de Ciências da Saúde e Vida, PUCRS, Caixa Postal 1429, 90619-900 Porto Alegre, RS, Brazil
| | | | - Maurício Reis Bogo
- Laboratório de Biologia Genômica e Molecular, Escola de Ciências da Saúde e Vida, PUCRS, Caixa Postal 1429, 90619-900 Porto Alegre, RS, Brazil
| | - Rosane Souza da Silva
- Laboratório de Neuroquímica e Psicofarmacologia, Escola de Ciências da Saúde e da Vida, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Avenida Ipiranga, 6681, Caixa Postal 1429, 90619-900 Porto Alegre, RS, Brazil.
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Dragic M, Stekic A, Zeljkovic M, Zaric Kontic M, Mihajlovic K, Adzic M, Grkovic I, Nedeljkovic N. Altered Topographic Distribution and Enhanced Neuronal Expression of Adenosine-Metabolizing Enzymes in Rat Hippocampus and Cortex from Early to late Adulthood. Neurochem Res 2022; 47:1637-1650. [PMID: 35320461 DOI: 10.1007/s11064-022-03557-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Revised: 01/27/2022] [Accepted: 02/09/2022] [Indexed: 11/30/2022]
Abstract
The present study demonstrates altered topographic distribution and enhanced neuronal expression of major adenosine-metabolizing enzymes, i.e. ecto-5'-nucleotidase (eN) and tissue non-specific alkaline phosphatase (TNAP), as well as adenosine receptor subtype A2A in the hippocampus and cortex of male rats from early to late adulthood (3, 6, 12 and 15 months old males). The significant effect of age was demonstrated for the increase in the activity and the protein expression of eN and TNAP. At 15-m, enzyme histochemistry demonstrated enhanced expression of eN in synapse-rich hippocampal and cortical layers, whereas the upsurge of TNAP was observed in the hippocampal and cortical neuropil, rather than in cells and layers where two enzymes mostly reside in 3-m old brain. Furthermore, a dichotomy in A1R and A2AR expression was demonstrated in the cortex and hippocampus from early to late adulthood. Specifically, a decrease in A1R and enhancement of A2AR expression were demonstrated by immunohistochemistry, the latter being almost exclusively localized in hippocampal pyramidal and cortical superficial cell layers. We did not observe any glial upregulation of A2AR, which was common for both advanced age and chronic neurodegeneration. Taken together, the results imply that the adaptative changes in adenosine signaling occurring in neuronal elements early in life may be responsible for the later prominent glial enhancement in A2AR-mediated adenosine signaling, and neuroinflammation and neurodegeneration, which are the hallmarks of both advanced age and age-associated neurodegenerative diseases.
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Affiliation(s)
- Milorad Dragic
- Department of General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, 11001, Belgrade, Serbia
| | - Andjela Stekic
- Department of General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, 11001, Belgrade, Serbia
| | - Milica Zeljkovic
- Department of General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, 11001, Belgrade, Serbia
| | - Marina Zaric Kontic
- Department for Molecular biology and Endocrinology, Vinča Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Katarina Mihajlovic
- Department of General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, 11001, Belgrade, Serbia
| | - Marija Adzic
- Department of General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, 11001, Belgrade, Serbia
| | - Ivana Grkovic
- Department for Molecular biology and Endocrinology, Vinča Institute of Nuclear Sciences-National Institute of the Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Nadezda Nedeljkovic
- Department of General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, 11001, Belgrade, Serbia.
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Grković I, Mitrović N, Dragić M. Ectonucleotidases in the hippocampus: Spatial distribution and expression after ovariectomy and estradiol replacement. VITAMINS AND HORMONES 2021; 118:199-221. [PMID: 35180927 DOI: 10.1016/bs.vh.2021.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Extracellular purine nucleotides, such as adenosine 5'-triphosphate (ATP), are important modulators of hippocampal function and plasticity. In the extracellular space, ATP is inherently short-lived molecule, which undergoes rapid enzymatic degradation to adenosine by ectonucleotidases. Given that ectonucleotidases have distinct and overlapping distribution in the hippocampus, and as ovarian hormones participate in a formation, maturation, and a refinement of synaptic contacts, both during development and in adulthood, the present chapter summarizes known data about spatial distribution of selected ecto-enzymes and estradiol-induced effects on ectonucleotidases in the rat hippocampus.
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Affiliation(s)
- Ivana Grković
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences-National Institute of thе Republic of Serbia, University of Belgrade, Belgrade, Serbia.
| | - Nataša Mitrović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences-National Institute of thе Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Milorad Dragić
- Department for General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Belgrade, Serbia
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Abstract
17β-Estradiol (E2) is a potent steroid hormone of both gonadal and neuronal origin that exerts profound effects on neuroplasticity in several brain regions. Dendritic spine and synapse formation and rearrangements are modulated and mediated by estrogens. In this chapter, we highlighted the essential background concerning the effects of E2 on synaptic rearrangements accompanied by synaptic plasticity in E2-sensitive brain regions that mediate learning and memory, i.e., cortex and hippocampus. We also address details of the molecular mechanisms underlying E2 regulation of spine dynamics. The proposed models of action of E2 overlaps with that for well-established synaptic modulators, such as adenosine. Thus, the possible synergistic effects of those two molecules in respect to synaptic rearrangement and plasticity were presented.
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Braganhol E, Wink MR, Lenz G, Battastini AMO. Purinergic Signaling in Glioma Progression. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1202:87-108. [PMID: 32034710 DOI: 10.1007/978-3-030-30651-9_5] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Among the pathological alterations that give tumor cells invasive potential, purinergic signaling is emerging as an important component. Studies performed in in vitro, in vivo and ex vivo glioma models indicate that alterations in the purinergic signaling are involved in the progression of these tumors. Gliomas have low expression of all E-NTPDases, when compared to astrocytes in culture. Nucleotides induce glioma proliferation and ATP, although potentially neurotoxic, does not evoke cytotoxic action on the majority of glioma cells in culture. The importance of extracellular ATP for glioma pathobiology was confirmed by the reduction in glioma tumor size by apyrase, which degrades extracellular ATP to AMP, and the striking increase in tumor size by over-expression of an ecto-enzyme that degrades ATP to ADP, suggesting the effect of extracellular ATP on the tumor growth depends on the nucleotide produced by its degradation. The participation of purinergic receptors on glioma progression, particularly P2X7, is involved in the resistance to ATP-induced cell death. Although more studies are necessary, the purinergic signaling, including ectonucleotidases and receptors, may be considered as future target for glioma pharmacological or gene therapy.
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Affiliation(s)
- Elizandra Braganhol
- Centro de Ciências Químicas, Farmacêuticas e de Alimentos (CCQFA), Universidade Federal de Pelotas (UFPel), Campus Capão do Leão S/N Caixa Postal 354, Pelotas, CEP 96010900, RS, Brazil.
| | - Márcia Rosângela Wink
- Departamento de Ciências Básicas da Saúde, Universidade Federal de Ciências da Saúde de Porto Alegre, 245 Rua Sarmento Leite, Porto Alegre, CEP 90050-170, RS, Brazil
| | - Guido Lenz
- Departamento de Biofísica, IB e Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, 9500 Av. Bento Goncalves, Porto Alegre, 61501970, RS, Brazil
| | - Ana Maria Oliveira Battastini
- Departamento de Bioquímica, ICBS, Universidade Federal do Rio Grande do Sul, 2600-anexo Rua Ramiro Barcelos, Porto Alegre, CEP 90035-003, RS, Brazil
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Rodrigues RJ, Marques JM, Cunha RA. Purinergic signalling and brain development. Semin Cell Dev Biol 2019; 95:34-41. [DOI: 10.1016/j.semcdb.2018.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 12/01/2018] [Accepted: 12/01/2018] [Indexed: 11/27/2022]
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Dragić M, Zarić M, Mitrović N, Nedeljković N, Grković I. Application of Gray Level Co-Occurrence Matrix Analysis as a New Method for Enzyme Histochemistry Quantification. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2019; 25:690-698. [PMID: 30714562 DOI: 10.1017/s1431927618016306] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Enzyme histochemistry is a valuable histological method which provides a connection between morphology, activity, and spatial localization of investigated enzymes. Even though the method relies purely on arbitrary evaluations performed by the human eye, it is still wildly accepted and used in histo(patho)logy. Texture analysis emerged as an excellent tool for image quantification of subtle differences reflected in both spatial discrepancies and gray level values of pixels. The current study of texture analysis utilizes the gray-level co-occurrence matrix as a method for quantification of differences between ecto-5'-nucleotidase activities in healthy hippocampal tissue and tissue with marked neurodegeneration. We used the angular second moment, contrast (CON), correlation, inverse difference moment (INV), and entropy for texture analysis and receiver operating characteristic analysis with immunoblot and qualitative assessment of enzyme histochemistry as a validation. Our results strongly argue that co-occurrence matrix analysis could be used for the determination of fine differences in the enzyme activities with the possibility to ascribe those differences to regions or specific cell types. In addition, it emerged that INV and CON are especially useful parameters for this type of enzyme histochemistry analysis. We concluded that texture analysis is a reliable method for quantification of this descriptive technique, thus removing biases and adding it a quantitative dimension.
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Affiliation(s)
- Milorad Dragić
- Department for General Physiology and Biophysics,Faculty of Biology,University of Belgrade,Belgrade,Studentski trg 3,11001 Belgrade,Serbia
| | - Marina Zarić
- Department of Molecular Biology and Endocrinology,Vinča Institute of Nuclear Sciences, University of Belgrade,Mike Petrovića Alasa 12-14,11001 Belgrade,Serbia
| | - Nataša Mitrović
- Department of Molecular Biology and Endocrinology,Vinča Institute of Nuclear Sciences, University of Belgrade,Mike Petrovića Alasa 12-14,11001 Belgrade,Serbia
| | - Nadežda Nedeljković
- Department for General Physiology and Biophysics,Faculty of Biology,University of Belgrade,Belgrade,Studentski trg 3,11001 Belgrade,Serbia
| | - Ivana Grković
- Department of Molecular Biology and Endocrinology,Vinča Institute of Nuclear Sciences, University of Belgrade,Mike Petrovića Alasa 12-14,11001 Belgrade,Serbia
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Nedeljkovic N. Complex regulation of ecto-5'-nucleotidase/CD73 and A 2AR-mediated adenosine signaling at neurovascular unit: A link between acute and chronic neuroinflammation. Pharmacol Res 2019; 144:99-115. [PMID: 30954629 DOI: 10.1016/j.phrs.2019.04.007] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 04/01/2019] [Accepted: 04/03/2019] [Indexed: 12/20/2022]
Abstract
The review summarizes available data regarding the complex regulation of CD73 at the neurovascular unit (NVU) during neuroinflammation. Based on available data we propose the biphasic pattern of CD73 regulation at NVU, with an early attenuation and a postponed up-regulation of CD73 activity. Transient attenuation of CD73 activity on leukocyte/vascular endothelium and leukocyte/astrocyte surface, required for the initiation of a neuroinflammatory response, may be effectuated either by catalytic inhibition of CD73 and/or by shedding of the CD73 molecule from the cell surface, while postponed induction of CD73 is effectuated by transcriptional up-regulation of Nt5e and posttranslational modifications. Neuroinflammatory conditions are also associated with significant enhancement and gain-of-function of A2AR-mediated adenosine signaling. However, in contrast to the temporary prevalence of A2AR over A1R signaling during an acute inflammatory response, prolonged induction of A2AR and resulting perpetual CD73/A2AR coupling may be a contributing factors in the transition between acute and chronic neuroinflammation. Thus, pharmacological targeting of the CD73/A2AR axis may attenuate inflammatory response and ameliorate neurological deficits in chronic neuroinflammatory conditions.
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Affiliation(s)
- Nadezda Nedeljkovic
- Department of General Physiology and Biophysics, Faculty of Biology University of Belgrade, Studentski trg 3, Belgrade 11001, Serbia.
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Grković I, Drakulić D, Martinović J, Mitrović N. Role of Ectonucleotidases in Synapse Formation During Brain Development: Physiological and Pathological Implications. Curr Neuropharmacol 2019; 17:84-98. [PMID: 28521702 PMCID: PMC6341498 DOI: 10.2174/1570159x15666170518151541] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 04/19/2017] [Accepted: 05/16/2017] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Extracellular adenine nucleotides and nucleosides, such as ATP and adenosine, are among the most recently identified and least investigated diffusible signaling factors that contribute to the structural and functional remodeling of the brain, both during embryonic and postnatal development. Their levels in the extracellular milieu are tightly controlled by various ectonucleotidases: ecto-nucleotide pyrophosphatase/phosphodiesterases (E-NPP), alkaline phosphatases (AP), ecto-nucleoside triphosphate diphosphohydrolases (E-NTPDases) and ecto-5'- nucleotidase (eN). METHODS Studies related to the expression patterns of ectonucleotidases and their known features during brain development are reviewed, highlighting involvement of these enzymes in synapse formation and maturation in physiological as well as in pathological states. RESULTS During brain development and in adulthood all ectonucleotidases have diverse expression pattern, cell specific localization and function. NPPs are expressed at early embryonic days, but the expression of NPP3 is reduced and restricted to ependymal area in adult brain. NTPDase2 is dominant ectonucleotidase existing in the progenitor cells as well as main astrocytic NTPDase in the adult brain, while NTPDase3 is fully expressed after third postnatal week, almost exclusively on varicose fibers. Specific brain AP is functionally associated with synapse formation and this enzyme is sufficient for adenosine production during neurite growth and peak of synaptogenesis. eN is transiently associated with synapses during synaptogenesis, however in adult brain it is more glial than neuronal enzyme. CONCLUSION Control of extracellular adenine nucleotide levels by ectonucleotidases are important for understanding the role of purinergic signaling in developing tissues and potential targets in developmental disorders such as autism.
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Affiliation(s)
- Ivana Grković
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Dunja Drakulić
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Jelena Martinović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Nataša Mitrović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
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Grković I, Mitrović N, Dragić M, Adžić M, Drakulić D, Nedeljković N. Spatial Distribution and Expression of Ectonucleotidases in Rat Hippocampus After Removal of Ovaries and Estradiol Replacement. Mol Neurobiol 2018; 56:1933-1945. [PMID: 29978426 DOI: 10.1007/s12035-018-1217-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/29/2018] [Indexed: 01/14/2023]
Abstract
Purinergic signaling is the main synaptic and non-synaptic signaling system in brain. ATP acts as a fast excitatory transmitter, while adenosine sets a global inhibitory tone within hippocampal neuronal networks. ATP and adenosine are interconnected by ectonucleotidase enzymes, which convert ATP to adenosine. Existing data point to the converging roles of ovarian steroids and purinergic signaling in synapse formation and refinement and synapse activity in the hippocampus. Therefore, in the present study, we have used enzyme histochemistry and expression analysis to obtain data on spatial distribution and expression of ecto-enzymes NTPDase1, NTPDase2, and ecto-5'-nucleotidase (eN) after removal of ovaries (OVX) and estradiol replacement (E2) in female rat hippocampus. The results show that target ectonucleotidases are predominantly localized in synapse-rich hippocampal layers. The most represented NTPDase in the hippocampal tissue is NTPDase2, being at the same time the mostly affected ectonucleotidase by OVX and E2. Specifically, OVX decreases the expression of NTPDase2 and eN, whereas E2 restores their expression to control level. Impact of OVX and E2 on ectonucleotidase expression was also examined in purified synaptosome (SYN) and gliosome (GLIO) fractions. Data reveal that SYN expresses NTPDase1 and NTPDase2, both of which are reduced following OVX and restored with E2. GLIO exhibits NTPDase2-mediated ATP hydrolysis, which falls in OVX, and recovers by E2. These changes in the activity occur without parallel changes in NTPDase2-protein abundance. The same holds for eN. The lack of correlation between NTPDase2 and eN activities and their respective protein abundances suggest a non-genomic mode of E2 action, which is studied further in primary astrocyte culture. Since ovarian steroids shape hippocampal synaptic networks and regulate ectonucleotidase activities, it is possible that cognitive deficits seen after ovary removal may arise from the loss of E2 modulatory actions on ectonucleotidase expression in the hippocampus.
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Affiliation(s)
- Ivana Grković
- Department of Molecular Biology and Endocrinology, Vinča Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia.
| | - Nataša Mitrović
- Department of Molecular Biology and Endocrinology, Vinča Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia
| | - Milorad Dragić
- Department of Molecular Biology and Endocrinology, Vinča Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia
- Department for General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, Belgrade, 11001, Serbia
| | - Marija Adžić
- Department for General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, Belgrade, 11001, Serbia
| | - Dunja Drakulić
- Department of Molecular Biology and Endocrinology, Vinča Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia
| | - Nadežda Nedeljković
- Department for General Physiology and Biophysics, Faculty of Biology, University of Belgrade, Studentski trg 3, Belgrade, 11001, Serbia
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Adzic M, Nedeljkovic N. Unveiling the Role of Ecto-5'-Nucleotidase/CD73 in Astrocyte Migration by Using Pharmacological Tools. Front Pharmacol 2018; 9:153. [PMID: 29545748 PMCID: PMC5837971 DOI: 10.3389/fphar.2018.00153] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 02/13/2018] [Indexed: 01/25/2023] Open
Abstract
CD73 is a bifunctional glycosylphosphatidylinositol (GPI)-anchored membrane protein which functions as ecto-5′-nucleotidase and a membrane receptor for extracellular matrix protein (ECM). A large body of evidence demonstrates a critical involvement of altered purine metabolism and particularly, increased expression of CD73 in a number of human disorders, including cancer and immunodeficiency. Massive up-regulation of CD73 was also found in reactive astrocytes in several experimental models of human neuropathologies. In all the pathological contexts studied so far, the increased expression of CD73 has been associated with the altered ability of cells to adhere and/or migrate. Thus, we hypothesized that increased expression of CD73 in reactive astrocytes has a role in the process of astrocyte adhesion and migration. In the present study, the involvement of CD73 in astrocyte migration was investigated in the scratch wound assay (SW), using primary astrocyte culture prepared from neonatal rat cortex. The cultures were treated with one of the following pharmacological inhibitors which preferentially target individual functions of CD73: (a) α,β-methylene ADP (APCP), which inhibits the catalytic activity of CD73 (b) polyclonal anti-CD73 antibodies, which bind to the internal epitope of CD73 molecule and mask their surface exposure and (c) small interfering CD73-RNA (siCD73), which silences the expression of CD73 gene. It was concluded that approaches that reduce surface expression of CD73 increase migration velocity and promote wound closure in the scratch wound assay, while inhibition of the enzyme activity by APCP induces redistribution of CD73 molecules at the cell surface, thus indirectly affecting cell adhesion and migration. Application of anti-CD73 antibodies induces a decrease in CD73 activity and membrane expression, through CD73 molecules shedding and their release to the culture media. In addition, all applied pharmacological inhibitors differentially affect other aspects of astrocyte function in vitro, including reduced cell proliferation, altered expression of adenosine receptors and increased expression of ERK1/2. Altogether these data imply that CD73 participates in cell adhesion/migration and transmits extracellular signals through interactions with ECM.
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Affiliation(s)
- Marija Adzic
- Department of General Physiology and Biophysics, Institute for Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia.,Centre for Laser Microscopy, Institute for Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
| | - Nadezda Nedeljkovic
- Department of General Physiology and Biophysics, Institute for Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Belgrade, Serbia
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Mitrović N, Zarić M, Drakulić D, Martinović J, Sévigny J, Stanojlović M, Nedeljković N, Grković I. 17β-Estradiol-Induced Synaptic Rearrangements Are Accompanied by Altered Ectonucleotidase Activities in Male Rat Hippocampal Synaptosomes. J Mol Neurosci 2016; 61:412-422. [PMID: 27981418 DOI: 10.1007/s12031-016-0877-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 12/05/2016] [Indexed: 12/20/2022]
Abstract
17β-Estradiol (E2) rapidly, by binding to membrane estrogen receptors, activates cell signaling cascades which induce formation of new dendritic spines in the hippocampus of males as in females, but the interaction with other metabolic processes, such as extracellular adenine nucleotides metabolism, are currently unknown. Extracellular adenine nucleotides play significant roles, controlling excitatory glutamatergic synapses and development of neural circuits and synaptic plasticity. Their precise regulation in the synaptic cleft is tightly controlled by ecto-nucleoside triphosphate diphosphohydrolase (NTPDase)/ecto-5'-nucleotidase (eN) enzyme chain. Therefore, we sought to clarify whether a single systemic injection of E2 in male rats is accompanied by changes in the expression of the pre- and postsynaptic proteins and downstream kinases linked to E2-induced synaptic rearrangement as well as alterations in NTPDase/eN pathway in the hippocampal synaptosomes. Obtained data showed activation of mammalian target of rapamycin and upregulation of key synaptic proteins necessary for spine formation, 24 h after systemic E2 administration. In E2-mediated conditions, we found downregulation of NTPDase1 and NTPDase2 and attenuation of adenine nucleotide hydrolysis by NTPDase/eN enzyme chain, without changes in NTPDase3 properties and augmentation of synaptic tissue-nonspecific alkaline phosphatase (TNAP) activity. Despite reduced NTPDase activities, increased TNAP activity probably prevents toxic accumulation of ATP in the extracellular milieu and also hydrolyzes accumulated ADP due to unchanged NTPDase3 activity. Thus, our initial evaluation supports idea of specific roles of different ectonucleotidases and their coordinated actions in E2-mediated spine remodeling and maintenance.
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Affiliation(s)
- Nataša Mitrović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia
| | - Marina Zarić
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia
| | - Dunja Drakulić
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia
| | - Jelena Martinović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia
| | - Jean Sévigny
- Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec, QC, G1V 0A6, Canada.,Centre de recherche du CHU de Québec, Université Laval, Québec, QC, G1V 4G2, Canada
| | - Miloš Stanojlović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia
| | - Nadežda Nedeljković
- Institute for Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Studentski trg 3, Belgrade, 11000, Serbia
| | - Ivana Grković
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, Belgrade, 11001, Serbia.
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13
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Mitrović N, Guševac I, Drakulić D, Stanojlović M, Zlatković J, Sévigny J, Horvat A, Nedeljković N, Grković I. Regional and sex-related differences in modulating effects of female sex steroids on ecto-5'-nucleotidase expression in the rat cerebral cortex and hippocampus. Gen Comp Endocrinol 2016; 235:100-107. [PMID: 27296672 DOI: 10.1016/j.ygcen.2016.06.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 11/03/2015] [Accepted: 06/09/2016] [Indexed: 12/20/2022]
Abstract
Ecto-5'-nucleotidase (eN), a membrane rate-limiting enzyme of the purine catabolic pathway, catalyzes the conversion of AMP to adenosine involved in the regulation of many brain physiological and pathological processes. Since gender fundamentally determines hormonal milieu in the body and brain, it is reasonable to assume that sex differences in the activity of various signaling systems, including adenosine, may be generated by gonadal steroids. Thus, we examined expression of eN as a component of adenosine signaling system in the basal state in cerebral cortex and hippocampus of male and female rats at gene, protein and functional level, as well as in the state of gonadal hormone deprivation, induced by ovariectomy (OVX), whereas impact of steroid hormones was explored after repeated administration of 17α-estradiol, 17β-estradiol and progesterone for seven consecutive days. Results showed regional and sex-related differences in basal eN activity level, with the highest AMP hydrolysis observed in the hippocampus of male rats. Furthermore, ovarian steroids do not contribute to basal gene eN expression or the activity in cortical and hippocampal region of female rats. However, protein eN expression was increased in OVX rats in both investigated region. Investigated exogenous steroids had no influence on eN expression in male brain, while in OVX females alterations in eN activity were induced. The observed effects in female rats were different between examined regions e.g. in cortex, applied treatments predominantly decreased whereas in hippocampus increased eN activity. Based on the presented results, eN exerts regional and sex-related response in basal state as well as after treatment with female gonadal hormones, however the exact mechanisms of sex steroids actions on eN remain unclear and should be fully explored.
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Affiliation(s)
- Nataša Mitrović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Ivana Guševac
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Dunja Drakulić
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Miloš Stanojlović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Jelena Zlatković
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Jean Sévigny
- Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec G1V 0A6, QC, Canada; Centre de recherche du CHU de Québec, G1V 4G2 QC, Canada
| | - Anica Horvat
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - Nadežda Nedeljković
- Institute for Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Studentski trg 3, 11000 Belgrade, Serbia
| | - Ivana Grković
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia.
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14
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Mitrović N, Zarić M, Drakulić D, Martinović J, Stanojlović M, Sévigny J, Horvat A, Nedeljković N, Grković I. 17β-Estradiol upregulates ecto-5'-nucleotidase (CD73) in hippocampal synaptosomes of female rats through action mediated by estrogen receptor-α and -β. Neuroscience 2016; 324:286-96. [PMID: 26987957 DOI: 10.1016/j.neuroscience.2016.03.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 02/23/2016] [Accepted: 03/08/2016] [Indexed: 02/06/2023]
Abstract
17β-Estradiol (E2) crucially affects several processes in the hippocampus of both sexes. E2 acts upon estradiol receptors ERα and ERβ, influencing target gene expression and/or modulates intracellular signaling cascades. Another potent modulator of hippocampal function is nucleoside adenosine, the final product of ectonucleotidase cascade, enzymes which hydrolyze extracellular ATP to adenosine. The last and rate-limiting step of the hydrolysis is catalyzed by membrane-bound ecto-5'-nucleotidase (eN). Previous findings obtained on adenosine metabolism in brain suggest that eN may be modulated by ovarian steroids. Therefore, the present study reports that the activity and protein abundance of membrane-bound eN fluctuates across the estrus cycle in the hippocampal synaptosomes of female rats. Further, we analyzed the role of E2 and its intracellular receptors on the expression of eN in ovariectomized females. We found that E2 upregulated eN activity and protein abundance in the hippocampal synaptosomes. Application of nonspecific ER antagonist, ICI 182,780 and selective ERα and ERβ agonists, PPT and DPN, respectively, demonstrated the involvement of both receptor subtypes in observed actions. Selective ERα receptor agonist, PPT, induced upregulation of both the protein level and activity of eN, while application of selective ERβ receptor agonist, DPN, increased only the activity of eN. In both cases, E2 entered into the intracellular compartment and activated ER(s), which was demonstrated by membrane impermeable E2-BSA conjugate. Together these results imply that E2-induced effects on connectivity and functional properties of the hippocampal synapses may be in part mediated through observed effect on eN.
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Affiliation(s)
- N Mitrović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - M Zarić
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - D Drakulić
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - J Martinović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - M Stanojlović
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - J Sévigny
- Département de microbiologie-infectiologie et d'immunologie, Faculté de Médecine, Université Laval, Québec G1V 0A6, QC, Canada; Centre de recherche du CHU de Québec - Université Laval, G1V 4G2 QC, Canada
| | - A Horvat
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia
| | - N Nedeljković
- Institute for Physiology and Biochemistry, Faculty of Biology, University of Belgrade, Studentski trg 3, 11000 Belgrade, Serbia
| | - I Grković
- Department of Molecular Biology and Endocrinology, VINČA Institute of Nuclear Sciences, University of Belgrade, Mike Petrovića Alasa 12-14, 11001 Belgrade, Serbia.
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15
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Developmental increase in ecto-5'-nucleotidase activity overlaps with appearance of two immunologically distinct enzyme isoforms in rat hippocampal synaptic plasma membranes. J Mol Neurosci 2014; 54:109-18. [PMID: 24563227 DOI: 10.1007/s12031-014-0256-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 02/04/2014] [Indexed: 12/24/2022]
Abstract
Ecto-5'-nucleotidase (e-5NT), a glycosylphosphatidylinositol-linked membrane protein, catalyzes a conversion of AMP to adenosine, which influences nearly every aspect of brain physiology, including embryonic and postnatal brain development. The present study aimed to investigate a pattern of expression, activity and kinetic properties of e-5NT in the hippocampal formation and synaptic plasma membrane (SPM) preparations in rats at postnatal days (PDs) 7, 15, 20, 30 and 90. By combining gene expression analysis and enzyme histochemistry, we observed that e-5NT mRNA reached the adult level at PD20, while the enzyme activity continued to increase beyond this age. Further analysis revealed that hippocampal layers rich in synapses expressed the highest levels of e-5NT activity, while in layers populated with neuronal cell bodies, the enzyme activity was weak or absent. Therefore, activity and expression of e-5NT were analyzed in SPM preparations isolated from rats at different ages. The presence of two protein bands of about 65 and 68 kDa was determined by immunoblot analysis. The 65-kDa band was present at all ages, and its abundance increased from PD7 to PD20. The 68-kDa band appeared at PD15 and increased until PD30, coinciding with the increase of e-5NT activity, substrate affinity and enzymatic efficiency. Since distinct e-5NT isoforms may derive from different patterns of the enzyme protein N-glycosylation, we speculate that long-term regulation of e-5NT activity in adulthood may be effectuated at posttranslational level and without overall change in the gene and protein expression.
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16
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Porciúncula LO, Sallaberry C, Mioranzza S, Botton PHS, Rosemberg DB. The Janus face of caffeine. Neurochem Int 2013; 63:594-609. [PMID: 24055856 DOI: 10.1016/j.neuint.2013.09.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2013] [Revised: 09/04/2013] [Accepted: 09/06/2013] [Indexed: 12/20/2022]
Abstract
Caffeine is certainly the psychostimulant substance most consumed worldwide. Over the past years, chronic consumption of caffeine has been associated with prevention of cognitive decline associated to aging and mnemonic deficits of brain disorders. While its preventive effects have been reported extensively, the cognitive enhancer properties of caffeine are relatively under debate. Surprisingly, there are scarce detailed ontogenetic studies focusing on neurochemical parameters related to the effects of caffeine during prenatal and earlier postnatal periods. Furthermore, despite the large number of epidemiological studies, it remains unclear how safe is caffeine consumption during pregnancy and brain development. Thus, the purpose of this article is to review what is currently known about the actions of caffeine intake on neurobehavioral and adenosinergic system during brain development. We also reviewed other neurochemical systems affected by caffeine, but not only during brain development. Besides, some recent epidemiological studies were also outlined with the control of "pregnancy signal" as confounding variable. The idea is to tease out how studies on the impact of caffeine consumption during brain development deserve more attention and further investigation.
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Affiliation(s)
- Lisiane O Porciúncula
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil.
| | - Cássia Sallaberry
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil
| | - Sabrina Mioranzza
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil
| | - Paulo Henrique S Botton
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil
| | - Denis B Rosemberg
- Laboratório de Estudos sobre o Sistema Purinérgico, Departamento de Bioquímica/ICBS, Universidade Federal do Rio Grande do Sul, Rua Ramiro Barcelos, 2600-anexo, Porto Alegre/RS, Brazil; Laboratório de Genética e Ecotoxicologia Molecular, Programa de Pós-graduação em Ciências Ambientais, Área de Ciências Exatas e Ambientais, Universidade Comunitária da Região de Chapecó. Avenida Senador Attílio Fontana, 591E, 89809-000 Chapecó/SC, Brazil
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17
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Purinergic signaling in glioma progression. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 986:81-102. [PMID: 22879065 DOI: 10.1007/978-94-007-4719-7_5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Among the pathological alterations that give tumor cells invasive potential, purinergic signaling is emerging as an important component. Studies performed in in vitro, in vivo and ex vivo glioma models indicate that alterations in the purinergic signaling are involved in the progression of these tumors. Gliomas have low expression of all E-NTPDases, when compared to astrocytes in culture. Nucleotides induce glioma proliferation and ATP, although potentially neurotoxic, does not evoke cytotoxic action on the majority of glioma cells in culture. The importance of extracellular ATP for glioma pathobiology was confirmed by the reduction in glioma tumor size by apyrase, which degrades extracellular ATP to AMP, and the striking increase in tumor size by over-expression of an ecto-enzyme that degrades ATP to ADP, suggesting the effect of extracellular ATP on the tumor growth depends on the nucleotide produced by its degradation. The participation of purinergic receptors on glioma progression, particularly P2X(7), is involved in the resistance to ATP-induced cell death. Although more studies are necessary, the purinergic signaling, including ectonucleotidases and receptors, may be considered as future target for glioma pharmacological or gene therapy.
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18
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Superior working memory and behavioural habituation but diminished psychomotor coordination in mice lacking the ecto-5'-nucleotidase (CD73) gene. Purinergic Signal 2012; 9:175-82. [PMID: 23274765 DOI: 10.1007/s11302-012-9344-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 11/19/2012] [Indexed: 12/22/2022] Open
Abstract
Adenosine is an important neuromodulator in the central nervous system involved in the regulation of wakefulness, sleep, learning and memory, fear and anxiety as well as motor functions. Extracellular adenosine is synthesized by the cell-surface ectoenzyme ecto-5'-nucleotidase (CD73) from 5'-adenosine monophosphate. While CD73 is widely expressed throughout the mammalian brain, its specific role for behaviour is poorly understood. We examined spatial working memory, emotional responses, motor coordination and motor learning as well as behavioural habituation in mice with a targeted deletion of CD73. CD73 knockout (CD73-/-) mice exhibit enhanced spatial working memory in the Y-maze and enhanced long-term behavioural habituation in the open field. Furthermore, impaired psychomotor coordination on the accelerating rotarod was found in CD73-/- mice. No changes in motor learning and/or anxiety-like behaviour were evident in CD73-/- mice. Our data provide evidence for a role of CD73 in the regulation of learning and memory and psychomotor coordination. Our results might be important for the evaluation of adenosine neuromodulators as possible treatments to ameliorate cognitive and motor deficits associated with neurodegenerative diseases.
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Profile of nucleotide catabolism and ectonucleotidase expression from the hippocampi of neonatal rats after caffeine exposure. Neurochem Res 2011; 37:23-30. [PMID: 21842269 DOI: 10.1007/s11064-011-0577-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Revised: 07/18/2011] [Accepted: 08/04/2011] [Indexed: 10/17/2022]
Abstract
Nucleotides and nucleosides play an important role in neurodevelopment acting through specific receptors. Ectonucleotidases are the major enzymes involved in controlling the availability of purinergic receptors ligands. ATP is co-released with several neurotransmitters and is the most important source of extracellular adenosine by catabolism exerted by ectonucleotidases. The main ectonucleotidases are named NTPDases (1-8) and 5'-nucleotidase. Adenosine is a powerful modulator of neurotransmitter release. Caffeine blocks adenosine receptor activity as well as adenosine-mediated neuromodulation. Considering the susceptibility of the immature brain to caffeine and the need for correct purinergic signaling during fetal development, we have analyzed the effects of caffeine exposure during gestational and lactational periods on nucleotide degradation and ectonucleotidase expression from the hippocampi of 7-, 14- and 21-days-old rats. Nucleotides hydrolysis was assessed by colorimetric determination of inorganic phosphate released. Ectonucleotidases expression was performed by RT-PCR. ATP and ADP hydrolysis displayed parallel age-dependent decreases in both control and caffeine-treated groups. AMP hydrolysis increased with caffeine treatment in 7-days-old rats (75%); although there was no significant difference in AMP hydrolysis between control (non caffeine-treated) rats and 14- or 21-days caffeine-treated rats. ADP hydrolysis was not affected by caffeine treatment. Caffeine treatment in 7- and 14-days-old rats decreased ATP hydrolysis when compared to the control group (19% and 60% decrease, respectively), but 21-days-treated rats showed an increase in ATP hydrolysis (39%). Expression levels of NTPDase 1 and 5 decreased in hippocampi of caffeine-treated rats. The expression of 5'-nucleotidase was not affected after caffeine exposure. The changes observed in nucleotide hydrolysis and ectonucleotidases expression could promote subtle effects on normal neural development considering the neuromodulatory role of adenosine.
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