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Salcedo C, Pozo Garcia V, García-Adán B, Ameen AO, Gegelashvili G, Waagepetersen HS, Freude KK, Aldana BI. Increased glucose metabolism and impaired glutamate transport in human astrocytes are potential early triggers of abnormal extracellular glutamate accumulation in hiPSC-derived models of Alzheimer's disease. J Neurochem 2024; 168:822-840. [PMID: 38063257 DOI: 10.1111/jnc.16014] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 10/27/2023] [Accepted: 11/01/2023] [Indexed: 05/19/2024]
Abstract
Glutamate recycling between neurons and astrocytes is essential to maintain neurotransmitter homeostasis. Disturbances in glutamate homeostasis, resulting in excitotoxicity and neuronal death, have been described as a potential mechanism in Alzheimer's disease (AD) pathophysiology. However, glutamate neurotransmitter metabolism in different human brain cells, particularly astrocytes, has been poorly investigated at the early stages of AD. We sought to investigate glucose and glutamate metabolism in AD by employing human induced pluripotent stem cell (hiPSC)-derived astrocytes and neurons carrying mutations in the amyloid precursor protein (APP) or presenilin-1 (PSEN-1) gene as found in familial types of AD (fAD). Methods such as live-cell bioenergetics and metabolic mapping using [13C]-enriched substrates were used to examine metabolism in the early stages of AD. Our results revealed greater glycolysis and glucose oxidative metabolism in astrocytes and neurons with APP or PSEN-1 mutations, accompanied by an elevated glutamate synthesis compared to control WT cells. Astrocytes with APP or PSEN-1 mutations exhibited reduced expression of the excitatory amino acid transporter 2 (EAAT2), and glutamine uptake increased in mutated neurons, with enhanced glutamate release specifically in neurons with a PSEN-1 mutation. These results demonstrate a hypermetabolic phenotype in astrocytes with fAD mutations possibly linked to toxic glutamate accumulation. Our findings further identify metabolic imbalances that may occur in the early phases of AD pathophysiology.
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Affiliation(s)
- Claudia Salcedo
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Victoria Pozo Garcia
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Bernat García-Adán
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Aishat O Ameen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Georgi Gegelashvili
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Institute of Chemical Biology, Ilia State University, Tbilisi, Georgia
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Kristine K Freude
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg, Denmark
| | - Blanca I Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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2
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Campolo N, Mastrogiovanni M, Mariotti M, Issoglio FM, Estrin D, Hägglund P, Grune T, Davies MJ, Bartesaghi S, Radi R. Multiple oxidative post-translational modifications of human glutamine synthetase mediate peroxynitrite-dependent enzyme inactivation and aggregation. J Biol Chem 2023; 299:102941. [PMID: 36702251 PMCID: PMC10011836 DOI: 10.1016/j.jbc.2023.102941] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 01/25/2023] Open
Abstract
Glutamine synthetase (GS), which catalyzes the ATP-dependent synthesis of L-glutamine from L-glutamate and ammonia, is a ubiquitous and conserved enzyme that plays a pivotal role in nitrogen metabolism across all life domains. In vertebrates, GS is highly expressed in astrocytes, where its activity sustains the glutamate-glutamine cycle at glutamatergic synapses and is thus essential for maintaining brain homeostasis. In fact, decreased GS levels or activity have been associated with neurodegenerative diseases, with these alterations attributed to oxidative post-translational modifications of the protein, in particular tyrosine nitration. In this study, we expressed and purified human GS (HsGS) and performed an in-depth analysis of its oxidative inactivation by peroxynitrite (ONOO-) in vitro. We found that ONOO- exposure led to a dose-dependent loss of HsGS activity, the oxidation of cysteine, methionine, and tyrosine residues and also the nitration of tryptophan and tyrosine residues. Peptide mapping by LC-MS/MS through combined H216O/H218O trypsin digestion identified up to 10 tyrosine nitration sites and five types of dityrosine cross-links; these modifications were further scrutinized by structural analysis. Tyrosine residues 171, 185, 269, 283, and 336 were the main nitration targets; however, tyrosine-to-phenylalanine HsGS mutants revealed that their sole nitration was not responsible for enzyme inactivation. In addition, we observed that ONOO- induced HsGS aggregation and activity loss. Thiol oxidation was a key modification to elicit aggregation, as it was also induced by hydrogen peroxide treatment. Taken together, our results indicate that multiple oxidative events at various sites are responsible for the inactivation and aggregation of human GS.
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Affiliation(s)
- Nicolás Campolo
- Departamento de Bioquímica and Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Mauricio Mastrogiovanni
- Departamento de Bioquímica and Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Michele Mariotti
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Federico M Issoglio
- CONICET-Universidad de Buenos Aires, Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Buenos Aires, Argentina; Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal
| | - Darío Estrin
- CONICET-Universidad de Buenos Aires, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Buenos Aires, Argentina; Departamento de Química Inorgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Analítica y Química Física, Buenos Aires, Argentina
| | - Per Hägglund
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Tilman Grune
- Department of Molecular Toxicology, German Institute of Human Nutrition, Potsdam-Rehbrücke, Nuthetal, Germany; German Center for Cardiovascular Research (DZHK), Berlin, Germany; Department of Physiological Chemistry, Faculty of Chemistry, University of Vienna, Vienna, Austria
| | - Michael J Davies
- Department of Biomedical Sciences, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Silvina Bartesaghi
- Departamento de Bioquímica and Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Rafael Radi
- Departamento de Bioquímica and Centro de Investigaciones Biomédicas (CEINBIO), Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
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3
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Kornecki JF, Carballares D, Tardioli PW, Rodrigues RC, Berenguer-Murcia Á, Alcántara AR, Fernandez-Lafuente R. Enzyme production ofd-gluconic acid and glucose oxidase: successful tales of cascade reactions. Catal Sci Technol 2020. [DOI: 10.1039/d0cy00819b] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This review mainly focuses on the use of glucose oxidase in the production ofd-gluconic acid, which is a reactant of undoubtable interest in different industrial areas. As example of diverse enzymatic cascade reactions.
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Affiliation(s)
- Jakub F. Kornecki
- Departamento de Biocatálisis
- ICP-CSIC
- Campus UAM-CSIC
- 28049 Madrid
- Spain
| | - Diego Carballares
- Departamento de Biocatálisis
- ICP-CSIC
- Campus UAM-CSIC
- 28049 Madrid
- Spain
| | - Paulo W. Tardioli
- Postgraduate Program in Chemical Engineering (PPGEQ)
- Department of Chemical Engineering
- Federal University of São Carlos
- 13565-905 São Carlos
- Brazil
| | - Rafael C. Rodrigues
- Biocatalysis and Enzyme Technology Lab
- Institute of Food Science and Technology
- Federal University of Rio Grande do Sul
- Porto Alegre
- Brazil
| | - Ángel Berenguer-Murcia
- Departamento de Química Inorgánica e Instituto Universitario de Materiales
- Universidad de Alicante
- Alicante 03080
- Spain
| | - Andrés R. Alcántara
- Departamento de Química en Ciencias Farmacéuticas
- Facultad de Farmacia
- Universidad Complutense de Madrid
- 28040-Madrid
- Spain
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4
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Neves J, Vizuete A, Nicola F, Da Ré C, Rodrigues A, Schmitz F, Mestriner R, Aristimunha D, Wyse A, Netto C. Glial glutamate transporters expression, glutamate uptake, and oxidative stress in an experimental rat model of intracerebral hemorrhage. Neurochem Int 2018. [DOI: 10.1016/j.neuint.2018.03.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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5
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Mezni A, Aoua H, Limam F, Aouani E. Neuroprotective effect of grape seed and skin extract on lithium-induced oxidative stress in healthy rat brain. NEUROCHEM J+ 2017. [DOI: 10.1134/s1819712417010093] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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6
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Robinson SR, Lee A, Bishop GM, Czerwinska H, Dringen R. Inhibition of Astrocytic Glutamine Synthetase by Lead is Associated with a Slowed Clearance of Hydrogen Peroxide by the Glutathione System. Front Integr Neurosci 2015; 9:61. [PMID: 26696846 PMCID: PMC4677102 DOI: 10.3389/fnint.2015.00061] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 11/23/2015] [Indexed: 01/28/2023] Open
Abstract
Lead intoxication in humans is characterized by cognitive impairments, particularly in the domain of memory, where evidence indicates that glutamatergic neurotransmission may be impacted. Animal and cell culture studies have shown that lead decreases the expression and activity of glutamine synthetase (GS) in astrocytes, yet the basis of this effect is uncertain. To investigate the mechanism responsible, the present study exposed primary astrocyte cultures to a range of concentrations of lead acetate (0–330 μM) for up to 24 h. GS activity was significantly reduced in cells following 24 h incubation with 100 or 330 μM lead acetate. However, no reduction in GS activity was detected when astrocytic lysates were co-incubated with lead acetate, suggesting that the mechanism is not due to a direct interaction and involves intact cells. Since GS is highly sensitive to oxidative stress, the capacity of lead to inhibit the clearance of hydrogen peroxide (H2O2) was investigated. It was found that exposure to lead significantly diminished the capacity of astrocytes to degrade H2O2, and that this was due to a reduction in the effectiveness of the glutathione system, rather than to catalase. These results suggest that the inhibition of GS activity in lead poisoning is a consequence of slowed H2O2 clearance, and supports the glutathione pathway as a primary therapeutic target.
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Affiliation(s)
| | - Alan Lee
- Department of Psychology, Monash University Clayton, VIC, Australia
| | - Glenda M Bishop
- School of Health Sciences, RMIT University Melbourne, VIC, Australia
| | - Hania Czerwinska
- School of Health Sciences, RMIT University Melbourne, VIC, Australia
| | - Ralf Dringen
- Centre for Biomolecular Interactions Bremen and Centre for Environmental Research and Sustainable Technology, Faculty 2 (Biology/Chemistry), University of Bremen Bremen, Germany
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7
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Jeitner TM, Battaile K, Cooper AJL. Critical Evaluation of the Changes in Glutamine Synthetase Activity in Models of Cerebral Stroke. Neurochem Res 2015; 40:2544-56. [DOI: 10.1007/s11064-015-1667-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 05/14/2015] [Accepted: 05/20/2015] [Indexed: 01/04/2023]
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8
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Gamma-irradiation induced changes in microbiological status, phenolic profile and antioxidant activity of peanut skin. J Funct Foods 2015. [DOI: 10.1016/j.jff.2014.10.034] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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9
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Palmieri EM, Spera I, Menga A, Infantino V, Iacobazzi V, Castegna A. Glutamine synthetase desensitizes differentiated adipocytes to proinflammatory stimuli by raising intracellular glutamine levels. FEBS Lett 2014; 588:4807-14. [PMID: 25451225 DOI: 10.1016/j.febslet.2014.11.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 10/09/2014] [Accepted: 11/11/2014] [Indexed: 01/16/2023]
Abstract
The role of glutamine synthetase (GS) during adipocyte differentiation is unclear. Here, we assess the impact of GS on the adipocytic response to a proinflammatory challenge at different differentiation stages. GS expression at the late stages of differentiation desensitized mature adipocytes to bacterial lipopolysaccharide (LPS) by increasing intracellular glutamine levels. Furthermore, LPS-activated mature adipocytes were unable to produce inflammatory mediators; LPS sensitivity was rescued following GS inhibition and the associated drop in intracellular glutamine levels. The ability of adipocytes to differentially respond to LPS during differentiation negatively correlates to GS expression and intracellular glutamine levels. Hence, modulation of intracellular glutamine levels by GS expression represents an endogenous mechanism through which mature adipocytes control the inflammatory response.
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Affiliation(s)
- Erika Mariana Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Iolanda Spera
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | - Alessio Menga
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy
| | | | - Vito Iacobazzi
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy; CNR Institute of Biomembranes and Bioenergetics, Bari, Italy
| | - Alessandra Castegna
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, Bari, Italy.
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10
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de Camargo AC, Vidal CMM, Canniatti-Brazaca SG, Shahidi F. Fortification of cookies with peanut skins: effects on the composition, polyphenols, antioxidant properties, and sensory quality. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:11228-11235. [PMID: 25350915 DOI: 10.1021/jf503625p] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Food fortification may be carried out to improve the health status of consumers. In this study, peanut skins were added at 1.3, 1.8, and 2.5% to cookies to increase their polyphenol content. Insoluble fiber was increased by up to 52%. In addition, total phenolic content and the corresponding antioxidant capacities also increased as evidenced by increases of epicatechin and procyanidin dimers A and B. In addition, trimers and tetramers of procyanidins were identified only in peanut skin-fortified cookies. Addition of 2.5% peanut skins rendered an increase of up to 30% in the total polyphenols as evaluated by high-performance liquid chromatography-diode array detection-electrospray ionization multistage mass spectrometry (HPLC-DAD-ESI-MS(n)). Sensory evaluation results demonstrated that peanut skin-fortified cookies were well accepted, which suggests that the present formulation may lend itself for commercial exploitation.
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Affiliation(s)
- Adriano Costa de Camargo
- Department of Biochemistry, Memorial University of Newfoundland , St. John's, NL, Canada A1B 3X9
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11
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Safwen K, Selima S, Mohamed E, Ferid L, Pascal C, Mohamed A, Ezzedine A, Meherzia M. Protective effect of grape seed and skin extract on cerebral ischemia in rat: implication of transition metals. Int J Stroke 2014; 10:415-24. [PMID: 25365917 DOI: 10.1111/ijs.12391] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 08/19/2014] [Indexed: 11/29/2022]
Abstract
Ischemic stroke is a leading cause of long lasting disability in humans and oxidative stress an important underlying cause. The present study aims to determine the effect of short term (seven-days) administration of high dosage grape seed and skin extract (GSSE 2.5 g/kg) on ischemia/reperfusion (I/R) injury in a rat model of global ischemia. Ischemia was induced by occlusion of the common carotid arteries for 30 min followed by one-hour reperfusion on control or GSSE treated animals. I/R induced a drastic oxidative stress characterized by high lipid and protein oxidation, a drop in antioxidant enzyme defenses, disturbed transition metals as free iron overload and depletion of copper, zinc and manganese as well as of associated brain enzyme activities as glutamine synthetase and lactate dehydrogenase. I/R also induced NO and calcium disruption and an increase in calpain activity, a calcium-sensitive cysteine protease. Interestingly, almost all I/R-induced disturbances were prevented by GSSE pretreatment as oxidative stress, transition metals associated enzyme activities, brain damage size and histology. Owing to its antioxidant potential, high dosage GSSE protected efficiently the brain against ischemic stroke and should be translated to humans.
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Affiliation(s)
- Kadri Safwen
- Bioactive Substance Laboratory, Biotechnology Centre, Hammam-Lif, Tunis
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12
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Abstract
Histochemical and MRI studies have demonstrated that MS (multiple sclerosis) patients have abnormal deposition of iron in both gray and white matter structures. Data is emerging indicating that this iron could partake in pathogenesis by various mechanisms, e.g., promoting the production of reactive oxygen species and enhancing the production of proinflammatory cytokines. Iron chelation therapy could be a viable strategy to block iron-related pathological events or it can confer cellular protection by stabilizing hypoxia inducible factor 1α, a transcription factor that normally responds to hypoxic conditions. Iron chelation has been shown to protect against disease progression and/or limit iron accumulation in some neurological disorders or their experimental models. Data from studies that administered a chelator to animals with experimental autoimmune encephalomyelitis, a model of MS, support the rationale for examining this treatment approach in MS. Preliminary clinical studies have been performed in MS patients using deferoxamine. Although some side effects were observed, the large majority of patients were able to tolerate the arduous administration regimen, i.e., 6-8 h of subcutaneous infusion, and all side effects resolved upon discontinuation of treatment. Importantly, these preliminary studies did not identify a disqualifying event for this experimental approach. More recently developed chelators, deferasirox and deferiprone, are more desirable for possible use in MS given their oral administration, and importantly, deferiprone can cross the blood-brain barrier. However, experiences from other conditions indicate that the potential for adverse events during chelation therapy necessitates close patient monitoring and a carefully considered administration regimen.
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Eid T, Tu N, Lee TSW, Lai JCK. Regulation of astrocyte glutamine synthetase in epilepsy. Neurochem Int 2013; 63:670-81. [PMID: 23791709 DOI: 10.1016/j.neuint.2013.06.008] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Revised: 05/28/2013] [Accepted: 06/08/2013] [Indexed: 11/20/2022]
Abstract
Astrocytes play a crucial role in regulating and maintaining the extracellular chemical milieu of the central nervous system under physiological conditions. Moreover, proliferation of phenotypically altered astrocytes (a.k.a. reactive astrogliosis) has been associated with many neurologic and psychiatric disorders, including mesial temporal lobe epilepsy (MTLE). Glutamine synthetase (GS), which is found in astrocytes, is the only enzyme known to date that is capable of converting glutamate and ammonia to glutamine in the mammalian brain. This reaction is important, because a continuous supply of glutamine is necessary for the synthesis of glutamate and GABA in neurons. The known stoichiometry of glutamate transport across the astrocyte plasma membrane also suggests that rapid metabolism of intracellular glutamate via GS is a prerequisite for efficient glutamate clearance from the extracellular space. Several studies have indicated that the activity of GS in astrocytes is diminished in several brain disorders, including MTLE. It has been hypothesized that the loss of GS activity in MTLE leads to increased extracellular glutamate concentrations and epileptic seizures. Understanding the mechanisms by which GS is regulated may lead to novel therapeutic approaches to MTLE, which is frequently refractory to antiepileptic drugs. This review discusses several known mechanisms by which GS expression and function are influenced, from transcriptional control to enzyme modification.
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Affiliation(s)
- Tore Eid
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, CT 06520, United States.
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14
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Effect of oxidative stress on UDP-glucuronosyltransferases in rat astrocytes. Toxicol Lett 2012; 213:316-24. [DOI: 10.1016/j.toxlet.2012.07.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 07/13/2012] [Accepted: 07/16/2012] [Indexed: 01/03/2023]
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Glutamine acts as a neuroprotectant against DNA damage, beta-amyloid and H2O2-induced stress. PLoS One 2012; 7:e33177. [PMID: 22413000 PMCID: PMC3297635 DOI: 10.1371/journal.pone.0033177] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 02/05/2012] [Indexed: 12/04/2022] Open
Abstract
Glutamine is the most abundant free amino acid in the human blood stream and is ‘conditionally essential’ to cells. Its intracellular levels are regulated both by the uptake of extracellular glutamine via specific transport systems and by its intracellular synthesis by glutamine synthetase (GS). Adding to the regulatory complexity, when extracellular glutamine is reduced GS protein levels rise. Unfortunately, this excess GS can be maladaptive. GS overexpression is neurotoxic especially if the cells are in a low-glutamine medium. Similarly, in low glutamine, the levels of multiple stress response proteins are reduced rendering cells hypersensitive to H2O2, zinc salts and DNA damage. These altered responses may have particular relevance to neurodegenerative diseases of aging. GS activity and glutamine levels are lower in the Alzheimer's disease (AD) brain, and a fraction of AD hippocampal neurons have dramatically increased GS levels compared with control subjects. We validated the importance of these observations by showing that raising glutamine levels in the medium protects cultured neuronal cells against the amyloid peptide, Aβ. Further, a 10-day course of dietary glutamine supplementation reduced inflammation-induced neuronal cell cycle activation, tau phosphorylation and ATM-activation in two different mouse models of familial AD while raising the levels of two synaptic proteins, VAMP2 and synaptophysin. Together, our observations suggest that healthy neuronal cells require both intracellular and extracellular glutamine, and that the neuroprotective effects of glutamine supplementation may prove beneficial in the treatment of AD.
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Oxidative stress in neurodegenerative diseases: mechanisms and therapeutic perspectives. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2011; 2011:467180. [PMID: 22191013 PMCID: PMC3236428 DOI: 10.1155/2011/467180] [Citation(s) in RCA: 154] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2011] [Revised: 08/31/2011] [Accepted: 09/07/2011] [Indexed: 02/07/2023]
Abstract
The incidence and prevalence of neurodegenerative diseases (ND) increase with life expectancy. This paper reviews the role of oxidative stress (OS) in ND and pharmacological attempts to fight against reactive oxygen species (ROS)-induced neurodegeneration. Several mechanisms involved in ROS generation in neurodegeneration have been proposed. Recent articles about molecular pathways involved in ROS generation were reviewed. The progress in the development of neuroprotective therapies has been hampered because it is difficult to define targets for treatment and determine what should be considered as neuroprotective. Therefore, the attention was focused on researches about pharmacological targets that could protect neurons against OS. Since it is necessary to look for genes as the ultimate controllers of all biological processes, this paper also tried to identify gerontogenes involved in OS and neurodegeneration. Since neurons depend on glial cells to survive, recent articles about the functioning of these cells in aging and ND were also reviewed. Finally, clinical trials testing potential neuroprotective agents were critically reviewed. Although several potential drugs have been screened in in vitro and in vivo models of ND, these results were not translated in benefit of patients, and disappointing results were obtained in the majority of clinical trials.
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