scholarly journals The Efficiency of Glutamate Uptake Differs between Neonatal and Adult Cortical Microvascular Endothelial Cells

2014 ◽  
Vol 34 (5) ◽  
pp. 764-767 ◽  
Author(s):  
Maryline Lecointre ◽  
Michelle Hauchecorne ◽  
Armelle Chaussivert ◽  
Stéphane Marret ◽  
Philippe Leroux ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Excitatory Amino Acid ◽  
Glutamate Uptake ◽  
Adult Brain ◽  
Amino Acid Transporters ◽  
Brain Endothelial Cells ◽  
Immature Brain ◽  
Differential Expression Pattern ◽  
Glutamate Efflux ◽  
Brain Homeostasis

Glutamate transporters (excitatory amino-acid transporters (EAATs)) are essential for brain homeostasis. While previous studies indicate that the vascular endothelium contributes to glutamate efflux in the adult brain, little information is available regarding glutamate uptake in the immature brain. The present study shows a differential expression pattern of EAATs between cortical microvessels in adults and newborns. In addition, adult cortical endothelial cells take up glutamate more efficiently than neonatal cells. Our findings indicate age-specific changes in extracellular glutamate regulation by brain endothelial cells, suggesting differences in the efficiency of glutamate efflux during an excitotoxic process that, in turn, may contribute to age-specific brain vulnerability.

scholarly journals Mechanisms of Glutamate Efflux at the Blood—Brain Barrier: Involvement of Glial Cells

2011 ◽  
Vol 32 (1) ◽  
pp. 177-189 ◽  
Author(s):  
Katayun Cohen-Kashi-Malina ◽  
Itzik Cooper ◽  
Vivian I Teichberg
Keyword(s):  
Endothelial Cells ◽  
Blood Brain Barrier ◽  
Glial Cells ◽  
Excitatory Amino Acid ◽  
Active Role ◽  
In Vitro Models ◽  
Brain Barrier ◽  
Amino Acid Transporters ◽  
Blood Brain

At high concentrations, glutamate (Glu) exerts potent neurotoxic properties, leading to irreversible brain damages found in numerous neurological disorders. The accepted notion that Glu homeostasis in brain interstitial fluid is maintained primarily through the activity of Glu transporters present on glial cells does not take into account the possible contribution of endothelial cells constituting the blood-brain barrier (BBB) to this process. Here, we present evidence for the presence of the Glu transporters, excitatory amino-acid transporters (EAATs) 1 to 3, in porcine brain endothelial cells (PBECs) and show their participation in Glu uptake into PBECs. Moreover, transport of Glu across three in vitro models of the BBB is investigated for the first time, and evidence for Glu transport across the BBB in both directions is presented. Our results provide evidence that the BBB can function in the efflux mode to selectively remove Glu, via specific transporters, from the abluminal side (brain) into the luminal compartment (blood). Furthermore, we found that glial cells lining the BBB have an active role in the efflux process by taking up Glu and releasing it, through hemichannels, anion channels, and possibly the reversal of its EAATs, in close proximity to ECs, which in turn take up Glu and release it to the blood.

scholarly journals Na+-dependent gate dynamics and electrostatic attraction ensure substrate coupling in glutamate transporters

2020 ◽  
Vol 6 (47) ◽  
pp. eaba9854
Author(s):  
C. Alleva ◽  
K. Kovalev ◽  
R. Astashkin ◽  
M. I. Berndt ◽  
C. Baeken ◽  
...  
Keyword(s):  
Excitatory Amino Acid ◽  
Glutamate Uptake ◽  
Substrate Binding ◽  
Synaptic Cleft ◽  
Electrostatic Attraction ◽  
Cubic Phase ◽  
Amino Acid Transporters ◽  
X Ray ◽  
Gate Opening ◽  
Substrate Coupling

Excitatory amino acid transporters (EAATs) harness [Na+], [K+], and [H+] gradients for fast and efficient glutamate removal from the synaptic cleft. Since each glutamate is cotransported with three Na+ ions, [Na+] gradients are the predominant driving force for glutamate uptake. We combined all-atom molecular dynamics simulations, fluorescence spectroscopy, and x-ray crystallography to study Na+:substrate coupling in the EAAT homolog GltPh. A lipidic cubic phase x-ray crystal structure of wild-type, Na+-only bound GltPh at 2.5-Å resolution revealed the fully open, outward-facing state primed for subsequent substrate binding. Simulations and kinetic experiments established that only the binding of two Na+ ions to the Na1 and Na3 sites ensures complete HP2 gate opening via a conformational selection-like mechanism and enables high-affinity substrate binding via electrostatic attraction. The combination of Na+-stabilized gate opening and electrostatic coupling of aspartate to Na+ binding provides a constant Na+:substrate transport stoichiometry over a broad range of neurotransmitter concentrations.

scholarly journals Acute Liver Toxicity Modifies Protein Expression of Glutamate Transporters in Liver and Cerebellar Tissue

2021 ◽  
Vol 14 ◽  
Author(s):  
Catya Jiménez-Torres ◽  
Hoda El-Kehdy ◽  
Luisa C. Hernández-Kelly ◽  
Etienne Sokal ◽  
Arturo Ortega ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Liver Toxicity ◽  
Excitatory Amino Acid ◽  
Glutamate Uptake ◽  
Wide Spectrum ◽  
Glutamate Transporters ◽  
Dependent Manner ◽  
Present Contribution ◽  
Differential Expression Pattern ◽  
The Brain

Glutamate is the main excitatory amino acid acting at the level of pre and postsynaptic neurons, as well as in glial cells. It is involved in the coordinated modulation of energy metabolism, glutamine synthesis, and ammonia detoxification. The relationship between the functional status of liver and brain has been known for many years. The most widely recognized aspect of this relation is the brain dysfunction caused by acute liver injury that manifests a wide spectrum of neurologic and psychiatric abnormalities. Inflammation, circulating neurotoxins, and impaired neurotransmission have been reported in this pathophysiology. In the present contribution, we report the effect of a hepatotoxic compound like CCl4 on the expression of key proteins involved in glutamate uptake and metabolism as glutamate transporters and glutamine synthetase in mice liver, brain, and cerebellum. Our findings highlight a differential expression pattern of glutamate transporters in cerebellum. A significant Purkinje cells loss, in parallel to an up-regulation of glutamine synthetase, and astrogliosis in the brain have also been noticed. In the intoxicated liver, glutamate transporter 1 expression is up-regulated, in contrast to glutamine synthetase which is reduced in a time-dependent manner. Taken together our results demonstrate that the exposure to an acute CCl4 insult, leads to the disruption of glutamate transporters expression in the liver-brain axis and therefore a severe alteration in glutamate-mediated neurotransmission might be present in the central nervous system.

scholarly journals Regulation of Th1 and Th2 Lymphocyte Migration by Human Adult Brain Endothelial Cells

2001 ◽  
Vol 60 (12) ◽  
pp. 1127-1136 ◽  
Author(s):  
Katarzyna Biernacki ◽  
Alexandre Prat ◽  
Manon Blain ◽  
Jack P. Antel
Keyword(s):  
Endothelial Cells ◽  
Adult Brain ◽  
Brain Endothelial Cells ◽  
Lymphocyte Migration ◽  
Human Adult ◽  
Th1 And Th2

In vitro evidence for the brain glutamate efflux hypothesis: Brain endothelial cells cocultured with astrocytes display a polarized brain-to-blood transport of glutamate

Glia ◽  
2012 ◽  
Vol 60 (6) ◽  
pp. 882-893 ◽  
Author(s):  
Hans Christian Helms ◽  
Rasmus Madelung ◽  
Helle Sønderby Waagepetersen ◽  
Carsten Uhd Nielsen ◽  
Birger Brodin
Keyword(s):  
Endothelial Cells ◽  
Brain Endothelial Cells ◽  
Blood Transport ◽  
The Brain ◽  
Glutamate Efflux

scholarly journals Substrate transport and anion permeation proceed through distinct pathways in glutamate transporters

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Mary Hongying Cheng ◽  
Delany Torres-Salazar ◽  
Aneysis D Gonzalez-Suarez ◽  
Susan G Amara ◽  
Ivet Bahar
Keyword(s):  
Excitatory Amino Acid ◽  
Glutamate Uptake ◽  
Amino Acid Transporters ◽  
Structural Coupling ◽  
Substrate Transport ◽  
Hydrophobic Residues ◽  
Substituted Cysteine Accessibility ◽  
Anion Permeation ◽  
Binding Core ◽  
Flexible Wall

Advances in structure-function analyses and computational biology have enabled a deeper understanding of how excitatory amino acid transporters (EAATs) mediate chloride permeation and substrate transport. However, the mechanism of structural coupling between these functions remains to be established. Using a combination of molecular modeling, substituted cysteine accessibility, electrophysiology and glutamate uptake assays, we identified a chloride-channeling conformer, iChS, transiently accessible as EAAT1 reconfigures from substrate/ion-loaded into a substrate-releasing conformer. Opening of the anion permeation path in this iChS is controlled by the elevator-like movement of the substrate-binding core, along with its wall that simultaneously lines the anion permeation path (global); and repacking of a cluster of hydrophobic residues near the extracellular vestibule (local). Moreover, our results demonstrate that stabilization of iChS by chemical modifications favors anion channeling at the expense of substrate transport, suggesting a mutually exclusive regulation mediated by the movement of the flexible wall lining the two regions.

scholarly journals Gateways for Glutamate Neuroprotection in Parkinson’s Disease (PD): Essential Role of EAAT3 and NCX1 Revealed in an In Vitro Model of PD

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2037
Author(s):  
Silvia Piccirillo ◽  
Simona Magi ◽  
Alessandra Preziuso ◽  
Pasqualina Castaldo ◽  
Salvatore Amoroso ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Ischemia Reperfusion Injury ◽  
Excitatory Amino Acid ◽  
Cell Damage ◽  
Glutamate Uptake ◽  
Ischemia Reperfusion ◽  
Amino Acid Transporters ◽  
Mitochondrial Functions

Increasing evidence suggests that metabolic alterations may be etiologically linked to neurodegenerative disorders such as Parkinson’s disease (PD) and in particular empathizes the possibility of targeting mitochondrial dysfunctions to improve PD progression. Under different pathological conditions (i.e., cardiac and neuronal ischemia/reperfusion injury), we showed that supplementation of energetic substrates like glutamate exerts a protective role by preserving mitochondrial functions and enhancing ATP synthesis through a mechanism involving the Na+-dependent excitatory amino acid transporters (EAATs) and the Na+/Ca2+ exchanger (NCX). In this study, we investigated whether a similar approach aimed at promoting glutamate metabolism would be also beneficial against cell damage in an in vitro PD-like model. In retinoic acid (RA)-differentiated SH-SY5Y cells challenged with α-synuclein (α-syn) plus rotenone (Rot), glutamate significantly improved cell viability by increasing ATP levels, reducing oxidative damage and cytosolic and mitochondrial Ca2+ overload. Glutamate benefits were strikingly lost when either EAAT3 or NCX1 expression was knocked down by RNA silencing. Overall, our results open the possibility of targeting EAAT3/NCX1 functions to limit PD pathology by simultaneously favoring glutamate uptake and metabolic use in dopaminergic neurons.

scholarly journals A computational approach yields selective inhibitors of human excitatory amino acid transporter 2 (EAAT2)

2020 ◽  
Vol 295 (13) ◽  
pp. 4359-4366
Author(s):  
Kelly L. Damm-Ganamet ◽  
Marie-Laure Rives ◽  
Alan D. Wickenden ◽  
Heather M. McAllister ◽  
Taraneh Mirzadegan
Keyword(s):  
Amino Acid ◽  
Drug Target ◽  
Therapeutic Potential ◽  
Excitatory Amino Acid ◽  
Glutamate Uptake ◽  
Homology Model ◽  
Binding Pocket ◽  
Amino Acid Transporters ◽  
Excitatory Amino Acid Transporter ◽  
Significant Interest

Excitatory amino acid transporters (EAATs) represent a protein family that is an emerging drug target with great therapeutic potential for managing central nervous system disorders characterized by dysregulation of glutamatergic neurotransmission. As such, it is of significant interest to discover selective modulators of EAAT2 function. Here, we applied computational methods to identify specific EAAT2 inhibitors. Utilizing a homology model of human EAAT2, we identified a binding pocket at the interface of the transport and trimerization domain. We next conducted a high-throughput virtual screen against this site and identified a selective class of EAAT2 inhibitors that were tested in glutamate uptake and whole-cell electrophysiology assays. These compounds represent potentially useful pharmacological tools suitable for further exploration of the therapeutic potential of EAAT2 and may provide molecular insights into mechanisms of allosteric modulation for glutamate transporters.

scholarly journals Role of EphrinA3 in HIV-1 Neuropathogenesis

ASN NEURO ◽  
2021 ◽  
Vol 13 ◽  
pp. 175909142110443
Author(s):  
Chitra Mohinder Singh Singal ◽  
Paritosh Jaiswal ◽  
Anuradha Mehta ◽  
Kanza Saleem ◽  
Pankaj Seth
Keyword(s):  
Excitatory Amino Acid ◽  
Neuronal Damage ◽  
Glutamate Uptake ◽  
Synaptic Activity ◽  
Glutamate Excitotoxicity ◽  
Amino Acid Transporters ◽  
Extracellular Glutamate ◽  
Hiv 1

Glial cells perform important supporting functions for neurons through a dynamic crosstalk. Neuron–glia communication is the major phenomenon to sustain homeostatic functioning of the brain. Several interactive pathways between neurons and astrocytes are critical for the optimal functioning of neurons, and one such pathway is the ephrinA3–ephA4 signaling. The role of this pathway is essential in maintaining the levels of extracellular glutamate by regulating the excitatory amino acid transporters, EAAT1 and EAAT2 on astrocytes. Human immunodeficiency virus-1 (HIV-1) and its proteins cause glutamate excitotoxicity due to excess glutamate levels at sites of high synaptic activity. This study unravels the effects of HIV-1 transactivator of transcription (Tat) from clade B on ephrinA3 and its role in regulating glutamate levels in astrocyte–neuron co-cultures of human origin. It was observed that the expression of ephrinA3 increases in the presence of HIV-1 Tat B, while the expression of EAAT1 and EAAT2 was attenuated. This led to reduced glutamate uptake and therefore high neuronal death due to glutamate excitotoxicity. Knockdown of ephrinA3 using small interfering RNA, in the presence of HIV-1 Tat B reversed the neurotoxic effects of HIV-1 Tat B via increased expression of glutamate transporters that reduced the levels of extracellular glutamate. The in vitro findings were validated in autopsy brain sections from acquired immunodeficiency syndrome patients and we found ephrinA3 to be upregulated in the case of HIV-1-infected patients. This study offers valuable insights into astrocyte-mediated neuronal damage in HIV-1 neuropathogenesis.

Sign in / Sign up

Export Citation Format

Share Document