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Cuellar-Santoyo AO, Ruiz-Rodríguez VM, Mares-Barbosa TB, Patrón-Soberano A, Howe AG, Portales-Pérez DP, Miquelajáuregui Graf A, Estrada-Sánchez AM. Revealing the contribution of astrocytes to glutamatergic neuronal transmission. Front Cell Neurosci 2023; 16:1037641. [PMID: 36744061 PMCID: PMC9893894 DOI: 10.3389/fncel.2022.1037641] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 12/20/2022] [Indexed: 01/20/2023] Open
Abstract
Research on glutamatergic neurotransmission has focused mainly on the function of presynaptic and postsynaptic neurons, leaving astrocytes with a secondary role only to ensure successful neurotransmission. However, recent evidence indicates that astrocytes contribute actively and even regulate neuronal transmission at different levels. This review establishes a framework by comparing glutamatergic components between neurons and astrocytes to examine how astrocytes modulate or otherwise influence neuronal transmission. We have included the most recent findings about the role of astrocytes in neurotransmission, allowing us to understand the complex network of neuron-astrocyte interactions. However, despite the knowledge of synaptic modulation by astrocytes, their contribution to specific physiological and pathological conditions remains to be elucidated. A full understanding of the astrocyte's role in neuronal processing could open fruitful new frontiers in the development of therapeutic applications.
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Affiliation(s)
- Ares Orlando Cuellar-Santoyo
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Victor Manuel Ruiz-Rodríguez
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Teresa Belem Mares-Barbosa
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico,Translational and Molecular Medicine Laboratory, Research Center for Health Sciences and Biomedicine, Autonomous University of San Luis Potosí, San Luis Potosí, Mexico
| | - Araceli Patrón-Soberano
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico
| | - Andrew G. Howe
- Intelligent Systems Laboratory, HRL Laboratories, LLC, Malibu, CA, United States
| | - Diana Patricia Portales-Pérez
- Translational and Molecular Medicine Laboratory, Research Center for Health Sciences and Biomedicine, Autonomous University of San Luis Potosí, San Luis Potosí, Mexico
| | | | - Ana María Estrada-Sánchez
- División de Biología Molecular, Laboratorio de Neurobiología, Instituto Potosino de Investigación Científica y Tecnológica (IPICYT), San Luis Potosí, Mexico,*Correspondence: Ana María Estrada-Sánchez
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Goubert E, Mircheva Y, Lasorsa FM, Melon C, Profilo E, Sutera J, Becq H, Palmieri F, Palmieri L, Aniksztejn L, Molinari F. Inhibition of the Mitochondrial Glutamate Carrier SLC25A22 in Astrocytes Leads to Intracellular Glutamate Accumulation. Front Cell Neurosci 2017; 11:149. [PMID: 28620281 PMCID: PMC5449474 DOI: 10.3389/fncel.2017.00149] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 05/09/2017] [Indexed: 12/16/2022] Open
Abstract
The solute carrier family 25 (SLC25) drives the import of a large diversity of metabolites into mitochondria, a key cellular structure involved in many metabolic functions. Mutations of the mitochondrial glutamate carrier SLC25A22 (also named GC1) have been identified in early epileptic encephalopathy (EEE) and migrating partial seizures in infancy (MPSI) but the pathophysiological mechanism of GC1 deficiency is still unknown, hampered by the absence of an in vivo model. This carrier is mainly expressed in astrocytes and is the principal gate for glutamate entry into mitochondria. A sufficient supply of energy is essential for the proper function of the brain and mitochondria have a pivotal role in maintaining energy homeostasis. In this work, we wanted to study the consequences of GC1 absence in an in vitro model in order to understand if glutamate catabolism and/or mitochondrial function could be affected. First, short hairpin RNA (shRNA) designed to specifically silence GC1 were validated in rat C6 glioma cells. Silencing GC1 in C6 resulted in a reduction of the GC1 mRNA combined with a decrease of the mitochondrial glutamate carrier activity. Then, primary astrocyte cultures were prepared and transfected with shRNA-GC1 or mismatch-RNA (mmRNA) constructs using the Neon® Transfection System in order to target a high number of primary astrocytes, more than 64%. Silencing GC1 in primary astrocytes resulted in a reduced nicotinamide adenine dinucleotide (Phosphate) (NAD(P)H) formation upon glutamate stimulation. We also observed that the mitochondrial respiratory chain (MRC) was functional after glucose stimulation but not activated by glutamate, resulting in a lower level of cellular adenosine triphosphate (ATP) in silenced astrocytes compared to control cells. Moreover, GC1 inactivation resulted in an intracellular glutamate accumulation. Our results show that mitochondrial glutamate transport via GC1 is important in sustaining glutamate homeostasis in astrocytes. Main Points:The mitochondrial respiratory chain is functional in absence of GC1 Lack of glutamate oxidation results in a lower global ATP level Lack of mitochondrial glutamate transport results in intracellular glutamate accumulation
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Affiliation(s)
| | - Yanina Mircheva
- INMED, INSERM, Aix-Marseille UniversitéMarseille, France.,Centre De Recherche De L'Institut Universitaire En Santé Mentale de QuébecQuebec City, QC, Canada
| | - Francesco M Lasorsa
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, and CNR Institute of Biomembranes, Bioenergetics and Molecular BiotechnologiesBari, Italy
| | | | - Emanuela Profilo
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, and CNR Institute of Biomembranes, Bioenergetics and Molecular BiotechnologiesBari, Italy
| | - Julie Sutera
- INMED, INSERM, Aix-Marseille UniversitéMarseille, France
| | - Hélène Becq
- INMED, INSERM, Aix-Marseille UniversitéMarseille, France
| | - Ferdinando Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, and CNR Institute of Biomembranes, Bioenergetics and Molecular BiotechnologiesBari, Italy
| | - Luigi Palmieri
- Department of Biosciences, Biotechnologies and Biopharmaceutics, University of Bari, and CNR Institute of Biomembranes, Bioenergetics and Molecular BiotechnologiesBari, Italy
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Dezonne RS, Lima FRS, Trentin AG, Gomes FC. Thyroid hormone and astroglia: endocrine control of the neural environment. J Neuroendocrinol 2015; 27:435-45. [PMID: 25855519 DOI: 10.1111/jne.12283] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Revised: 04/01/2015] [Accepted: 04/02/2015] [Indexed: 02/03/2023]
Abstract
Thyroid hormones (THs) play key roles in brain development and function. The lack of THs during childhood is associated with the impairment of several neuronal connections, cognitive deficits and mental disorders. Several lines of evidence point to astrocytes as TH targets and as mediators of TH action in the central nervous system; however, the mechanisms underlying these events are still not completely known. In this review, we focus on advances in our understanding of the effects of THs on astroglial cells and the impact of these effects on neurone-astrocyte interactions. First, we discuss the signalling pathways involved in TH metabolism and the molecular mechanisms underlying TH receptor function. Then, we discuss data related to the effects of THs on astroglial cells, as well as studies regarding the generation of mutant TH receptor transgenic mice that have contributed to our understanding of TH function in brain development. We argue that astrocytes are key mediators of hormone actions on development of the cerebral cortex and cerebellum and that the identification of the molecules and pathways involved in these events might be important for determining the molecular-level basis of the neural deficits associated with endocrine diseases.
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Affiliation(s)
- R S Dezonne
- Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - F R S Lima
- Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - A G Trentin
- Departamento de Biologia Celular, Centro de Ciências Biológicas, Embriologia e Genética, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil
| | - F C Gomes
- Instituto de Ciências Biomédicas, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil
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Gouix E, Buisson A, Nieoullon A, Kerkerian-Le Goff L, Tauskela JS, Blondeau N, Had-Aissouni L. Oxygen glucose deprivation-induced astrocyte dysfunction provokes neuronal death through oxidative stress. Pharmacol Res 2014; 87:8-17. [DOI: 10.1016/j.phrs.2014.06.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Revised: 06/03/2014] [Accepted: 06/04/2014] [Indexed: 11/28/2022]
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Santello M, Calì C, Bezzi P. Gliotransmission and the tripartite synapse. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 970:307-31. [PMID: 22351062 DOI: 10.1007/978-3-7091-0932-8_14] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In the last years, the classical view of glial cells (in particular of astrocytes) as a simple supportive cell for neurons has been replaced by a new vision in which glial cells are active elements of the brain. Such a new vision is based on the existence of a bidirectional communication between astrocytes and neurons at synaptic level. Indeed, perisynaptic processes of astrocytes express active G-protein-coupled receptors that are able (1) to sense neurotransmitters released from the synapse during synaptic activity, (2) to increase cytosolic levels of calcium, and (3) to stimulate the release of gliotransmitters that in turn can interact with the synaptic elements. The mechanism(s) by which astrocytes can release gliotransmitter has been extensively studied during the last years. Many evidences have suggested that a fraction of astrocytes in situ release neuroactive substances both with calcium-dependent and calcium-independent mechanism(s); whether these mechanisms coexist and under what physiological or pathological conditions they occur, it remains unclear. However, the calcium-dependent exocytotic vesicular release has received considerable attention due to its potential to occur under physiological conditions via a finely regulated way. By releasing gliotransmitters in millisecond time scale with a specific vesicular apparatus, astrocytes can integrate and process synaptic information and control or modulate synaptic transmission and plasticity.
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Affiliation(s)
- Mirko Santello
- DBCM, Department of Physiology, University of Bern, Bühlplatz 5, 3012 Bern, Switzerland
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Ferrucci A, Nonnemacher MR, Wigdahl B. Human immunodeficiency virus viral protein R as an extracellular protein in neuropathogenesis. Adv Virus Res 2012; 81:165-99. [PMID: 22094081 DOI: 10.1016/b978-0-12-385885-6.00010-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Numerous studies published in the past two decades have identified the viral protein R (Vpr) as one of the most versatile proteins in the life cycle of human immunodeficiency virus type 1 (HIV-1). In this regard, more than a thousand Vpr molecules are present in extracellular viral particles. Subsequent to viral entry, Vpr participates in early replicative events by assisting in viral genome nuclear import and, during the viral life cycle, by shuttling between the nucleus and the cytoplasm to accomplish its functions within the context of other replicative functions. Additionally, several studies have implicated Vpr as a proapoptotic protein because it promotes formation of permeability transition pores in mitochondria, which in turn affects transmembrane potential and adenosine triphosphate synthesis. Recent studies have identified Vpr as a virion-free protein in the serum and cerebrospinal fluid of patients infected with HIV-1 whose plasma viremia directly correlates with the extracellular concentration of Vpr. These observations pointed to a new role for Vpr as an additional weapon in the HIV-1 arsenal, involving the use of an extracellular protein to target and possibly inhibit HIV-1-uninfected bystander cells to enable them to escape immune surveillance. In addition, extracellular Vpr decreases adenosine triphosphate levels and affects the intracellular redox balance in neurons, ultimately causing their apoptosis. Herein, we review the role of Vpr as an extracellular protein and its downstream effects on cellular metabolism, functionality, and survival, with particular emphasis on how extracellular Vpr-induced oxidative stress might aggravate HIV-1-induced symptoms, thus affecting pathogenesis and disease progression.
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Affiliation(s)
- Adriano Ferrucci
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania, USA
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7
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Had-Aissouni L. Toward a new role for plasma membrane sodium-dependent glutamate transporters of astrocytes: maintenance of antioxidant defenses beyond extracellular glutamate clearance. Amino Acids 2011; 42:181-97. [DOI: 10.1007/s00726-011-0863-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 02/17/2011] [Indexed: 01/17/2023]
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Levine MS, Cepeda C, André VM. Location, location, location: contrasting roles of synaptic and extrasynaptic NMDA receptors in Huntington's disease. Neuron 2010; 65:145-7. [PMID: 20152121 DOI: 10.1016/j.neuron.2010.01.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Abnormally enhanced N-methyl-D-aspartate (NMDA) receptor function is implicated in Huntington's disease (HD). In this issue of Neuron and a recent issue of Nature Medicine, an abnormal balance between the activity of NMDA receptors at synaptic (prosurvival) and extrasynaptic (proapoptotic) sites has been uncovered in a cellular and a mouse model of HD.
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Affiliation(s)
- Michael S Levine
- Intellectual and Developmental Disabilities Research Center, Semel Institute for Neuroscience and Human Behavior, University of California at Los Angeles, Los Angeles, CA 90095, USA.
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Yamashita S, Mori A, Kimura E, Mita S, Maeda Y, Hirano T, Uchino M. DJ-1 forms complexes with mutant SOD1 and ameliorates its toxicity. J Neurochem 2010; 113:860-70. [PMID: 20202083 DOI: 10.1111/j.1471-4159.2010.06658.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Mutations in Cu/Zn superoxide dismutase (SOD1) gene cause familial amyotrophic lateral sclerosis (ALS), which could be attributed to the toxic properties of the misfolded protein, oxidative stress, and mitochondrial dysfunction. DJ-1 - a causative agent of familial Parkinson's disease PARK7 - is responsible for inducing antioxidative reaction. In this study, we showed the up-regulation of DJ-1 protein levels in mutant SOD1 transgenic mice through the lifespan were observed in the motor neurons. We demonstrated biochemically DJ-1 formed complexes with mutant SOD1 in the cell lysates. Furthermore, DJ-1 over-expression resulted in increased cell viability and reduced cell toxicity in mutant SOD1-transfected neuronal cells, because of improvement in apoptotic pathway and reduction in oxidative stress levels. We also evaluated DJ-1 levels in CSF collected from sporadic ALS patients and controls subjects. The CSF DJ-1 levels were significantly higher in patients with sporadic ALS than in control subjects. These results show that DJ-1 may be associated with sporadic and familial ALS pathogenesis. Therefore, insight into the effects of DJ-1 on mutant SOD1-mediated toxicity may provide a therapeutic advance for the treatment of motor neuron degeneration in ALS.
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Affiliation(s)
- Satoshi Yamashita
- Department of Neurology, Graduate School of Medical Sciences, Kumamoto University, Honjo, Kumamoto, Japan.
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Szydlowska K, Gozdz A, Dabrowski M, Zawadzka M, Kaminska B. Prolonged activation of ERK triggers glutamate-induced apoptosis of astrocytes: neuroprotective effect of FK506. J Neurochem 2010; 113:904-18. [PMID: 20202085 DOI: 10.1111/j.1471-4159.2010.06656.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Although, astrocytes are more resistant than neurons to ischemic injury, astrocyte death has been demonstrated in animal models of brain ischemia. Astrocytes death after ischemia/reperfusion may strongly affect neuronal survival because of the absence of their trophic and metabolic support to neurons, and astrocytic glutamate uptake. Early signals involved in astrocytes death are poorly understood. We demonstrated enhanced and mostly cytoplasmic activation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) during glutamate-induced apoptosis of cultured astrocytes. Treatment with UO126, inhibitor of MEK1, threo-beta-benzyloxyaspartic acid, glutamate transporter inhibitor, and FK506, a cytoprotective drug prevented ERK activation and glutamate-induced apoptosis. Over-expression of ERK dual specificity phosphatases 5 and 6 reduced apoptosis in transfected astrocytes. Prolonged ERK1/2 activation was observed in ischemic brain: in the nucleus and cytoplasm of astrocytes in the cerebral cortex, and exclusively in the cytoplasm of astrocytes in the striatum. Global gene expression profiling in the cortex revealed that FK506 blocks middle cerebral artery occlusion-induced expression of numerous genes associated with ERK signaling pathway and apoptosis. The results demonstrate a pro-apoptotic role of sustained activation of ERK1/2 signaling in glutamate-induced death of astrocytes and the ability of FK506 to block both ERK activation and astrocytic cell death in vitro and in ischemic brains.
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Affiliation(s)
- Kinga Szydlowska
- Laboratory of Transcription Regulation, The Nencki Institute of Experimental Biology, Warsaw, Poland
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Oono S, Kurimoto T, Nakazawa T, Miyoshi T, Okamoto N, Kashimoto R, Tagami Y, Ito Y, Mimura O. Pyroglutamic Acid Promotes Survival of Retinal Ganglion Cells after Optic Nerve Injury. Curr Eye Res 2009; 34:598-605. [DOI: 10.1080/02713680902981292] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Calì C, Marchaland J, Spagnuolo P, Gremion J, Bezzi P. Regulated exocytosis from astrocytes physiological and pathological related aspects. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2009; 85:261-93. [PMID: 19607976 DOI: 10.1016/s0074-7742(09)85020-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Astrocytes have traditionally been considered ancillary, satellite cells of the nervous system. However, it is a very recent acquisition that glial cells generate signaling loops which are integral to the brain circuitry and participate, interactively with neuronal networks, in the processing of information. Such a conceptual breakthrough makes this field of investigation one of the hottest in neuroscience, as it calls for a revision of past theories of brain function as well as for new strategies of experimental exploration of brain function. Glial cells are electrically not excitable, and it was only the use of optical recording techniques together with calcium sensitive dyes, that allowed the chemical excitability of glial cells to become apparent. Studies using these new techniques have shown for the first time that glial cells are activated by surrounding synaptic activity and translate neuronal signals into their own calcium code. Intracellular calcium concentration([Ca2+]i) elevations in glial cells have then shown to underlie spatial transfer of information in the glial network, accompanied by release of chemical transmitters (gliotransmitters) such as glutamate and back-signaling to neurons. As a consequence, optical imaging techniques applied to cell cultures or intact tissue have become a state-of-the-art technology for studying glial cell signaling. The molecular mechanisms leading to release of "gliotransmitters," especially glutamate, from glia are under debate. Accumulating evidence clearly indicates that astrocytes secrete numerous transmitters by Ca(2+)-dependent exocytosis. This review will discuss the mechanisms underlying the release of chemical transmitters from astrocytes with a particular emphasis to the regulated exocytosis processes.
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Affiliation(s)
- Corrado Calì
- Department of Cellular Biology and Morphology (DBCM), Faculty of Medicine, University of Lausanne, rue du Bugnon 9, 1005 Lausanne, Switzerland
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Mendes-de-Aguiar CBN, Alchini R, Decker H, Alvarez-Silva M, Tasca CI, Trentin AG. Thyroid hormone increases astrocytic glutamate uptake and protects astrocytes and neurons against glutamate toxicity. J Neurosci Res 2008; 86:3117-25. [DOI: 10.1002/jnr.21755] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Molz S, Tharine DC, Decker H, Tasca CI. GMP prevents excitotoxicity mediated by NMDA receptor activation but not by reversal activity of glutamate transporters in rat hippocampal slices. Brain Res 2008; 1231:113-20. [PMID: 18655777 DOI: 10.1016/j.brainres.2008.07.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2008] [Revised: 07/02/2008] [Accepted: 07/02/2008] [Indexed: 01/11/2023]
Abstract
Glutamate is the main excitatory neurotransmitter in the mammalian nervous system and is essential for its normal functions. However, overstimulation of glutamatergic system due to hyperactivation of NMDA receptors and/or impairment of glutamate reuptake system has been implicated in many acute and chronic neurological diseases. Regulation of extracellular glutamate concentrations relies on the function of glutamate transporters which can be reversed in situations related to excitotoxicity. Guanosine-5'-monophosphate (GMP), a guanine nucleotide which displays important extracellular roles, such as trophic effects to neurons and astrocytes, behaves as antagonist of glutamate receptors and is neuroprotective in hippocampal slices against excitotoxicity or ischemic conditions. Hippocampal slices exposed to 1 or 10 mM glutamate, or 100 microM NMDA with 10 microM glycine for 1 h and evaluated after 6 or 18 h, showed reduced cell viability and DNA fragmentation, respectively. Glutamate- or NMDA-induced cell death was prevented by 50 microM MK-801, but only NMDA-induced cell damage was prevented by GMP (1 mM). Glutamate-induced cell viability impairment and glutamate-induced l-[(3)H]glutamate release were both prevented by adding DL-TBOA (10 microM). Otherwise, NMDA-induced cell viability loss was not prevented by 10 microM of DL-TBOA and NMDA did not induce l-[(3)H]glutamate release. Our results demonstrate that GMP is neuroprotective when acting selectively at NMDA receptors. Glutamate-induced hippocampal slice damage and glutamate release were blocked by glutamate transporter inhibitor, indicating that glutamate-induced toxicity also involves the reversal of glutamate uptake, which cannot be prevented by GMP.
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Affiliation(s)
- Simone Molz
- Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Trindade, Florianópolis, SC, Brazil
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Bidmon HJ, Görg B, Palomero-Gallagher N, Schleicher A, Häussinger D, Speckmann EJ, Zilles K. Glutamine synthetase becomes nitrated and its activity is reduced during repetitive seizure activity in the pentylentetrazole model of epilepsy. Epilepsia 2008; 49:1733-48. [PMID: 18479397 DOI: 10.1111/j.1528-1167.2008.01642.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
PURPOSE The astrocyte-specific glutamine synthetase (GS) plays a key role in glutamate recycling and Gamma-aminobutyric acid (GABA) metabolism. Changes in the expression or activity of GS have been proposed to contribute to epileptogenesis. The mechanisms or how and where GS may contribute to epilepsy is still a matter of discussion. Here we asked the question whether brain regions, which show an astrocytic stress response respond with alterations of GS. METHODS Biochemical and histological alterations of GS, HSP-27, and GFAP were studied after pentylenetetrazole-induced repetitive epileptic seizures (PIRS) in rats using a topographical quantification of the GS-immunoreactivity (GSIR) in relation to the focal heat shock response (HSR). Saline-treated rats served as controls and rats treated by the GS-inhibitor, L-methionine-sulfoximine (MSO) served as a positive control. RESULTS No changes in the amount of GSIR and GS-protein occurred during PIRS. A significant reduction of GSIR was observed by histochemistry (in situ) and in native (nonheated) protein extracts of MSO-treated rats. In rats affected by PIRS, GS-activity showed a significant, region-specific reduction in association with a nitration of the enzyme. DISCUSSION These results show that neither PIRS nor GS-inhibition reduced the amount of GS protein, but that MSO interferes with antibody binding to native GS. PIRS resulted in a focal increase of astrocytic stress response, whereas MSO caused a widespread, homogeneous astrocytic HSR independent from quantitative changes of GS content. In rats with PIRS the regions showing a strong glial HSR, respond with reduced GS-activity and GS-nitration, which all together are clear indicators of a nitrosative stress response.
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Affiliation(s)
- Hans-J Bidmon
- C & O Vogt Institute for Brain Research, Heinrich-Heine-University, Düsseldorf, Germany.
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Huang XJ, Zhang WP, Li CT, Shi WZ, Fang SH, Lu YB, Chen Z, Wei EQ. Activation of CysLT receptors induces astrocyte proliferation and death after oxygen-glucose deprivation. Glia 2008; 56:27-37. [PMID: 17910051 DOI: 10.1002/glia.20588] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We recently found that 5-lipoxygenase (5-LOX) is activated to produce cysteinyl leukotrienes (CysLTs), and CysLTs may cause neuronal injury and astrocytosis through activation of CysLT(1) and CysLT(2) receptors in the brain after focal cerebral ischemia. However, the property of astrocyte responses to in vitro ischemic injury is not clear; whether 5-LOX, CysLTs, and their receptors are also involved in the responses of ischemic astrocytes remains unknown. In the present study, we performed oxygen-glucose deprivation (OGD) followed by recovery to induce ischemic-like injury in the cultured rat astrocytes. We found that 1-h OGD did not injure astrocytes (sub-lethal OGD) but induced astrocyte proliferation 48 and 72 h after recovery; whereas 4-h OGD moderately injured the cells (moderate OGD) and led to death 24-72 h after recovery. Inhibition of phospholipase A(2) and 5-LOX attenuated both the proliferation and death. Sub-lethal and moderate OGD enhanced the production of CysLTs that was inhibited by 5-LOX inhibitors. Sub-lethal OGD increased the expressions of CysLT(1) receptor mRNA and protein, while moderate OGD induced the expression of CysLT(2) receptor mRNA. Exogenously applied leukotriene D(4) (LTD(4)) induced astrocyte proliferation at 1-10 nM and astrocyte death at 100-1,000 nM. The CysLT(1) receptor antagonist montelukast attenuated astrocyte proliferation, the CysLT(2) receptor antagonist BAY cysLT2 reversed astrocyte death, and the dual CysLT receptor antagonist BAY u9773 exhibited both effects. In addition, LTD(4) (100 nM) increased the expression of CysLT(2) receptor mRNA. Thus, in vitro ischemia activates astrocyte 5-LOX to produce CysLTs, and CysLTs result in CysLT(1) receptor-mediated proliferation and CysLT(2) receptor-mediated death.
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Affiliation(s)
- Xiao-Jia Huang
- Department of Pharmacology, School of Medicine, Zhejiang University, Hangzhou 310058, People's Republic of China
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Li Z, Srivastava S, Findlan R, Chan C. Using dynamic gene module map analysis to identify targets that modulate free fatty acid induced cytotoxicity. Biotechnol Prog 2007; 24:29-37. [PMID: 18052188 DOI: 10.1021/bp070120b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The objective of this study was to identify pathways that regulate the cytotoxicity induced by free fatty acids (FFAs) in human hepatoblastoma cells (HepG2/C3A). Gene expression profiles of HepG2/C3A cells were obtained at three time points, after 24, 48, and 72 h of exposure to different types of FFA. Saturated fatty acid (palmitate) was found to be cytotoxic. The pathways activated by the different FFAs at the different time points were identified using global gene module map analysis. Unsaturated FFAs exerted transcriptional regulation mainly within the first 24 h, whereas saturated FFA, palmitate, regulated energy production pathways, such as the electron transport chain (ETC) and tricarboxylic acid cycle, within the first 24 h. In the next 24 h, palmitate up-regulated 36 cell death relevant pathways and down-regulated several protective pathways, such as the pentose phosphate pathway and glutathione-related pathways. In the final 24 h, the FFAs did not induce significant transcriptional regulation. We hypothesized that palmitate induced cytotoxicity by first perturbing metabolic pathways in the initial 24 h, resulting in changes to factors, such as metabolites or signaling molecules, which subsequently triggered cell death relevant pathways in the next 24 h. The uptake and release of 27 metabolites were measured to further elucidate the metabolic changes in the first 24 h. It was determined that ketone bodies such as beta-hydroxybutyrate and acetoacetate were important in separating the toxic from the nontoxic phenotypes. A regression model was used to identify the genes relevant to these metabolites. Some of the genes identified to be important were experimentally validated. It was found that ETC genes such as NADH dehydrogenase and succinate dehydrogenase were involved in palmitate induced cytotoxicity.
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Affiliation(s)
- Zheng Li
- Cellular and Molecular Biology Lab, Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, Michigan 48824, USA
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Nafia I, Re DB, Masmejean F, Melon C, Kachidian P, Kerkerian-Le Goff L, Nieoullon A, Had-Aissouni L. Preferential vulnerability of mesencephalic dopamine neurons to glutamate transporter dysfunction. J Neurochem 2007; 105:484-96. [PMID: 18042178 DOI: 10.1111/j.1471-4159.2007.05146.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Nigral depletion of the main brain antioxidant GSH is the earliest biochemical event involved in Parkinson's disease pathogenesis. Its causes are completely unknown but increasing number of evidence suggests that glutamate transporters [excitatory amino acid transporters (EAATs)] are the main route by which GSH precursors may enter the cell. In this study, we report that dopamine (DA) neurons, which express the excitatory amino acid carrier 1, are preferentially affected by EAAT dysfunction when compared with non-DA neurons. In rat embryonic mesencephalic cultures, l-trans-pyrrolidine-2,4-dicarboxylate, a substrate inhibitor of EAATs, is directly and preferentially toxic for DA neurons by decreasing the availability of GSH precursors and lowering their resistance threshold to glutamate excitotoxicity through NMDA-receptors. In adult rat, acute intranigral injection of l-trans-pyrrolidine-2,4-dicarboxylate induces a large regionally selective and dose-dependent loss of DA neurons and alpha-synuclein aggregate formation. These data highlight for the first time the importance of excitatory amino acid carrier 1 function for the maintenance of antioxidant defense in DA neurons and suggest its dysfunction as a candidate mechanism for the selective death of DA neurons such as occurring in Parkinson's disease.
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Affiliation(s)
- Imane Nafia
- Equipe Interactions Cellulaires, Neurodégénérescence et Neuroplasticité, Institut de Biologie du Développement de Marseille-Luminy, UMR6216 CNRS-Université de la Méditerranée, Marseille, France
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19
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Malarkey EB, Parpura V. Mechanisms of glutamate release from astrocytes. Neurochem Int 2007; 52:142-54. [PMID: 17669556 PMCID: PMC2267911 DOI: 10.1016/j.neuint.2007.06.005] [Citation(s) in RCA: 255] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2007] [Indexed: 11/22/2022]
Abstract
Astrocytes can release the excitatory transmitter glutamate which is capable of modulating activity in nearby neurons. This astrocytic glutamate release can occur through six known mechanisms: (i) reversal of uptake by glutamate transporters (ii) anion channel opening induced by cell swelling, (iii) Ca2+-dependent exocytosis, (iv) glutamate exchange via the cystine-glutamate antiporter, (v) release through ionotropic purinergic receptors and (vi) functional unpaired connexons, "hemichannels", on the cell surface. Although these various pathways have been defined, it is not clear how often and to what extent astrocytes employ different mechanisms. It will be necessary to determine whether the same glutamate release mechanisms that operate under physiological conditions operate during pathological conditions or whether there are specific release mechanisms that operate under particular conditions.
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Affiliation(s)
| | - Vladimir Parpura
- Departments of Physics & Astronomy, Centers for Glial-Neuronal Interactions and Nanoscale Science & Engineering, University of California, Riverside, CA 92521
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