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Banerjee P, Chau K, Kotla S, Davis EL, Turcios EB, Li S, Pengzhi Z, Wang G, Kolluru GK, Jain A, Cooke JP, Abe J, Le NT. A Potential Role for MAGI-1 in the Bi-Directional Relationship Between Major Depressive Disorder and Cardiovascular Disease. Curr Atheroscler Rep 2024; 26:463-483. [PMID: 38958925 DOI: 10.1007/s11883-024-01223-5] [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] [Accepted: 06/10/2024] [Indexed: 07/04/2024]
Abstract
PURPOSE OF REVIEW Major Depressive Disorder (MDD) is characterized by persistent symptoms such as fatigue, loss of interest in activities, feelings of sadness and worthlessness. MDD often coexist with cardiovascular disease (CVD), yet the precise link between these conditions remains unclear. This review explores factors underlying the development of MDD and CVD, including genetic, epigenetic, platelet activation, inflammation, hypothalamic-pituitary-adrenal (HPA) axis activation, endothelial cell (EC) dysfunction, and blood-brain barrier (BBB) disruption. RECENT FINDINGS Single nucleotide polymorphisms (SNPs) in the membrane-associated guanylate kinase WW and PDZ domain-containing protein 1 (MAGI-1) are associated with neuroticism and psychiatric disorders including MDD. SNPs in MAGI-1 are also linked to chronic inflammatory disorders such as spontaneous glomerulosclerosis, celiac disease, ulcerative colitis, and Crohn's disease. Increased MAGI-1 expression has been observed in colonic epithelial samples from Crohn's disease and ulcerative colitis patients. MAGI-1 also plays a role in regulating EC activation and atherogenesis in mice and is essential for Influenza A virus (IAV) infection, endoplasmic reticulum stress-induced EC apoptosis, and thrombin-induced EC permeability. Despite being understudied in human disease; evidence suggests that MAGI-1 may play a role in linking CVD and MDD. Therefore, further investigation of MAG-1 could be warranted to elucidate its potential involvement in these conditions.
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Affiliation(s)
- Priyanka Banerjee
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
- Medical Physiology, College of Medicine, Texas A&M Health Science Center, Bryan, TX, USA
| | - Khanh Chau
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
| | - Sivareddy Kotla
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Eleanor L Davis
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
| | - Estefani Berrios Turcios
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
| | - Shengyu Li
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
| | - Zhang Pengzhi
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
| | - Guangyu Wang
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
| | | | - Abhishek Jain
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
- Department of Biomedical Engineering, College of Engineering, Texas A&M University, College Station, TX, USA
- Department of Medical Physiology, School of Medicine, Texas A&M Health Science Center, Bryan, USA
| | - John P Cooke
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA
| | - Junichi Abe
- Department of Cardiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Nhat-Tu Le
- Center for Cardiovascular Regeneration, Department of Cardiovascular Sciences, Houston Methodist Research Institute, Houston, TX, USA.
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Leek AN, Quinn JA, Krapf D, Tamkun MM. GLT-1a glutamate transporter nanocluster localization is associated with astrocytic actin and neuronal Kv2 clusters at sites of neuron-astrocyte contact. Front Cell Dev Biol 2024; 12:1334861. [PMID: 38362041 PMCID: PMC10867268 DOI: 10.3389/fcell.2024.1334861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 01/16/2024] [Indexed: 02/17/2024] Open
Abstract
Introduction: Astrocytic GLT-1 glutamate transporters ensure the fidelity of glutamic neurotransmission by spatially and temporally limiting glutamate signals. The ability to limit neuronal hyperactivity relies on the localization and diffusion of GLT-1 on the astrocytic surface, however, little is known about the underlying mechanisms. We show that two isoforms of GLT-1, GLT-1a and GLT-1b, form nanoclusters on the surface of transfected astrocytes and HEK-293 cells. Methods: We used both fixed and live cell super-resolution imaging of fluorescent protein and epitope tagged proteins in co-cultures of rat astrocytes and neurons. Immunofluorescence techniques were also used. GLT1 diffusion was assessed via single particle tracking and fluorescence recovery after photobleach (FRAP). Results: We found GLT-1a, but not GLT-1b, nanoclusters concentrated adjacent to actin filaments which was maintained after addition of glutamate. GLT-1a nanocluster concentration near actin filaments was prevented by expression of a cytosolic GLT-1a C-terminus, suggesting the C-terminus is involved in the localization adjacent to cortical actin. Using super-resolution imaging, we show that astrocytic GLT-1a and actin co-localize in net-like structures around neuronal Kv2.1 clusters at points of neuron/astrocyte contact. Conclusion: Overall, these data describe a novel relationship between GLT-1a and cortical actin filaments, which localizes GLT-1a near neuronal structures responsive to ischemic insult.
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Affiliation(s)
- Ashley N. Leek
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
- Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, United States
| | - Josiah A. Quinn
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
| | - Diego Krapf
- Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, CO, United States
| | - Michael M. Tamkun
- Department of Biomedical Sciences, Colorado State University, Fort Collins, CO, United States
- Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, CO, United States
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO, United States
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3
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Gupta S, Bazargani N, Drew J, Howden JH, Modi S, Al Awabdh S, Marie H, Attwell D, Kittler JT. The non-adrenergic imidazoline-1 receptor protein nischarin is a key regulator of astrocyte glutamate uptake. iScience 2022; 25:104127. [PMID: 35434559 PMCID: PMC9010640 DOI: 10.1016/j.isci.2022.104127] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 12/24/2021] [Accepted: 03/17/2022] [Indexed: 12/02/2022] Open
Abstract
Astrocytic GLT-1 is the main glutamate transporter involved in glutamate buffering in the brain, pivotal for glutamate removal at excitatory synapses to terminate neurotransmission and for preventing excitotoxicity. We show here that the surface expression and function of GLT-1 can be rapidly modulated through the interaction of its N-terminus with the nonadrenergic imidazoline-1 receptor protein, Nischarin. The phox domain of Nischarin is critical for interaction and internalization of surface GLT-1. Using live super-resolution imaging, we found that glutamate accelerated Nischarin-GLT-1 internalization into endosomal structures. The surface GLT-1 level increased in Nischarin knockout astrocytes, and this correlated with a significant increase in transporter uptake current. In addition, Nischarin knockout in astrocytes is neuroprotective against glutamate excitotoxicity. These data provide new molecular insights into regulation of GLT-1 surface level and function and suggest new drug targets for the treatment of neurological disorders. Nischarin phox domain interacts with the N-terminus of the glutamate transporter, GLT-1 Nischarin promotes internalization of GLT-1 to endosomes Glutamate modulates GLT-1 surface levels by regulating the Nischarin-GLT-1 interaction Nischarin loss enhances GLT-1 surface levels, transport currents, and neuroprotection
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Affiliation(s)
- Swati Gupta
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
| | - Narges Bazargani
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
| | - James Drew
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
| | - Jack H. Howden
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
| | - Souvik Modi
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
| | - Sana Al Awabdh
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
| | - Hélène Marie
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
| | - David Attwell
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
| | - Josef T. Kittler
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, WC1E 6BT London, UK
- Corresponding author
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MAGI1, a Scaffold Protein with Tumor Suppressive and Vascular Functions. Cells 2021; 10:cells10061494. [PMID: 34198584 PMCID: PMC8231924 DOI: 10.3390/cells10061494] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/04/2021] [Accepted: 06/08/2021] [Indexed: 12/13/2022] Open
Abstract
MAGI1 is a cytoplasmic scaffolding protein initially identified as a component of cell-to-cell contacts stabilizing cadherin-mediated cell–cell adhesion in epithelial and endothelial cells. Clinical-pathological and experimental evidence indicates that MAGI1 expression is decreased in some inflammatory diseases, and also in several cancers, including hepatocellular carcinoma, colorectal, cervical, breast, brain, and gastric cancers and appears to act as a tumor suppressor, modulating the activity of oncogenic pathways such as the PI3K/AKT and the Wnt/β-catenin pathways. Genomic mutations and other mechanisms such as mechanical stress or inflammation have been described to regulate MAGI1 expression. Intriguingly, in breast and colorectal cancers, MAGI1 expression is induced by non-steroidal anti-inflammatory drugs (NSAIDs), suggesting a role in mediating the tumor suppressive activity of NSAIDs. More recently, MAGI1 was found to localize at mature focal adhesion and to regulate integrin-mediated adhesion and signaling in endothelial cells. Here, we review MAGI1′s role as scaffolding protein, recent developments in the understanding of MAGI1 function as tumor suppressor gene, its role in endothelial cells and its implication in cancer and vascular biology. We also discuss outstanding questions about its regulation and potential translational implications in oncology.
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Pryce KD, Powell R, Agwa D, Evely KM, Sheehan GD, Nip A, Tomasello DL, Gururaj S, Bhattacharjee A. Magi-1 scaffolds Na V1.8 and Slack K Na channels in dorsal root ganglion neurons regulating excitability and pain. FASEB J 2019; 33:7315-7330. [PMID: 30860870 DOI: 10.1096/fj.201802454rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Voltage-dependent sodium (NaV) 1.8 channels regulate action potential generation in nociceptive neurons, identifying them as putative analgesic targets. Here, we show that NaV1.8 channel plasma membrane localization, retention, and stability occur through a direct interaction with the postsynaptic density-95/discs large/zonula occludens-1-and WW domain-containing scaffold protein called membrane-associated guanylate kinase with inverted orientation (Magi)-1. The neurophysiological roles of Magi-1 are largely unknown, but we found that dorsal root ganglion (DRG)-specific knockdown of Magi-1 attenuated thermal nociception and acute inflammatory pain and produced deficits in NaV1.8 protein expression. A competing cell-penetrating peptide mimetic derived from the NaV1.8 WW binding motif decreased sodium currents, reduced NaV1.8 protein expression, and produced hypoexcitability. Remarkably, a phosphorylated variant of the very same peptide caused an opposing increase in NaV1.8 surface expression and repetitive firing. Likewise, in vivo, the peptides produced diverging effects on nocifensive behavior. Additionally, we found that Magi-1 bound to sequence like a calcium-activated potassium channel sodium-activated (Slack) potassium channels, demonstrating macrocomplexing with NaV1.8 channels. Taken together, these findings emphasize Magi-1 as an essential scaffold for ion transport in DRG neurons and a central player in pain.-Pryce, K. D., Powell, R., Agwa, D., Evely, K. M., Sheehan, G. D., Nip, A., Tomasello, D. L., Gururaj, S., Bhattacharjee, A. Magi-1 scaffolds NaV1.8 and Slack KNa channels in dorsal root ganglion neurons regulating excitability and pain.
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Affiliation(s)
- Kerri D Pryce
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Rasheen Powell
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Dalia Agwa
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Katherine M Evely
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Garrett D Sheehan
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Allan Nip
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Danielle L Tomasello
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Sushmitha Gururaj
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
| | - Arin Bhattacharjee
- Department of Pharmacology and Toxicology, University at Buffalo-The State University of New York, Buffalo, New York, USA
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Hayashi MK. Structure-Function Relationship of Transporters in the Glutamate-Glutamine Cycle of the Central Nervous System. Int J Mol Sci 2018; 19:ijms19041177. [PMID: 29649168 PMCID: PMC5979278 DOI: 10.3390/ijms19041177] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/09/2018] [Accepted: 04/10/2018] [Indexed: 12/12/2022] Open
Abstract
Many kinds of transporters contribute to glutamatergic excitatory synaptic transmission. Glutamate is loaded into synaptic vesicles by vesicular glutamate transporters to be released from presynaptic terminals. After synaptic vesicle release, glutamate is taken up by neurons or astrocytes to terminate the signal and to prepare for the next signal. Glutamate transporters on the plasma membrane are responsible for transporting glutamate from extracellular fluid to cytoplasm. Glutamate taken up by astrocyte is converted to glutamine by glutamine synthetase and transported back to neurons through glutamine transporters on the plasma membranes of the astrocytes and then on neurons. Glutamine is converted back to glutamate by glutaminase in the neuronal cytoplasm and then loaded into synaptic vesicles again. Here, the structures of glutamate transporters and glutamine transporters, their conformational changes, and how they use electrochemical gradients of various ions for substrate transport are summarized. Pharmacological regulations of these transporters are also discussed.
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Affiliation(s)
- Mariko Kato Hayashi
- School of Medicine, International University of Health and Welfare, 4-3 Kozunomori, Narita, Chiba 286-8686, Japan.
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7
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Dynamics of surface neurotransmitter receptors and transporters in glial cells: Single molecule insights. Cell Calcium 2017; 67:46-52. [PMID: 29029790 DOI: 10.1016/j.ceca.2017.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 08/21/2017] [Accepted: 08/21/2017] [Indexed: 11/22/2022]
Abstract
The surface dynamics of neurotransmitter receptors and transporters, as well as ion channels, has been well-documented in neurons, revealing complex molecular behaviour and key physiological functions. However, our understanding of the membrane trafficking and dynamics of the signalling molecules located at the plasma membrane of glial cells is still in its infancy. Yet, recent breakthroughs in the field of glial cells have been obtained using combination of superresolution microscopy, single molecule imaging, and electrophysiological recordings. Here, we review our current knowledge on the surface dynamics of neurotransmitter receptors, transporters and ion channels, in glial cells. It has emerged that the brain cell network activity, synaptic activity, and calcium signalling, regulate the surface distribution and dynamics of these molecules. Remarkably, the dynamics of a given neurotransmitter receptor/transporter at the plasma membrane of a glial cell or neuron is unique, revealing the existence of cell-type specific regulatory pathways. Thus, investigating the dynamics of signalling proteins at the surface of glial cells will likely shed new light on our understanding of glial cell physiology and pathology.
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8
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Rives ML, Javitch JA, Wickenden AD. Potentiating SLC transporter activity: Emerging drug discovery opportunities. Biochem Pharmacol 2017; 135:1-11. [DOI: 10.1016/j.bcp.2017.02.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 02/13/2017] [Indexed: 12/12/2022]
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9
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Krycer JR, Fazakerley DJ, Cater RJ, C Thomas K, Naghiloo S, Burchfield JG, Humphrey SJ, Vandenberg RJ, Ryan RM, James DE. The amino acid transporter, SLC1A3, is plasma membrane-localised in adipocytes and its activity is insensitive to insulin. FEBS Lett 2017; 591:322-330. [PMID: 28032905 DOI: 10.1002/1873-3468.12549] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 11/25/2016] [Accepted: 12/23/2016] [Indexed: 12/21/2022]
Abstract
The hormone insulin coordinates the catabolism of nutrients by protein phosphorylation. Phosphoproteomic analysis identified insulin-responsive phosphorylation of the Glu/Asp transporter SLC1A3/EAAT1 in adipocytes. The role of SLC1A3 in adipocytes is not well-understood. We show that SLC1A3 is localised to the plasma membrane and the major regulator of acidic amino acid uptake in adipocytes. However, its localisation and activity were unaffected by insulin or mutation of the insulin-regulated phosphosite. The latter was also observed using a heterologous expression system in Xenopus laevis oocytes. Thus, SLC1A3 maintains a constant import of acidic amino acids independently of nutritional status in adipocytes.
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Affiliation(s)
- James R Krycer
- School of Life and Environmental Sciences and Charles Perkins Centre, The University of Sydney, NSW, Australia
| | - Daniel J Fazakerley
- School of Life and Environmental Sciences and Charles Perkins Centre, The University of Sydney, NSW, Australia
| | - Rosemary J Cater
- Discipline of Pharmacology, Sydney Medical School, The University of Sydney, NSW, Australia
| | - Kristen C Thomas
- School of Life and Environmental Sciences and Charles Perkins Centre, The University of Sydney, NSW, Australia
| | - Sheyda Naghiloo
- School of Life and Environmental Sciences and Charles Perkins Centre, The University of Sydney, NSW, Australia
| | - James G Burchfield
- School of Life and Environmental Sciences and Charles Perkins Centre, The University of Sydney, NSW, Australia
| | - Sean J Humphrey
- School of Life and Environmental Sciences and Charles Perkins Centre, The University of Sydney, NSW, Australia
| | - Robert J Vandenberg
- Discipline of Pharmacology, Sydney Medical School, The University of Sydney, NSW, Australia
| | - Renae M Ryan
- Discipline of Pharmacology, Sydney Medical School, The University of Sydney, NSW, Australia
| | - David E James
- School of Life and Environmental Sciences and Charles Perkins Centre, The University of Sydney, NSW, Australia.,Sydney Medical School, The University of Sydney, NSW, Australia
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11
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Astroglial glutamate transporters coordinate excitatory signaling and brain energetics. Neurochem Int 2016; 98:56-71. [PMID: 27013346 DOI: 10.1016/j.neuint.2016.03.014] [Citation(s) in RCA: 112] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 03/15/2016] [Accepted: 03/17/2016] [Indexed: 12/22/2022]
Abstract
In the mammalian brain, a family of sodium-dependent transporters maintains low extracellular glutamate and shapes excitatory signaling. The bulk of this activity is mediated by the astroglial glutamate transporters GLT-1 and GLAST (also called EAAT2 and EAAT1). In this review, we will discuss evidence that these transporters co-localize with, form physical (co-immunoprecipitable) interactions with, and functionally couple to various 'energy-generating' systems, including the Na(+)/K(+)-ATPase, the Na(+)/Ca(2+) exchanger, glycogen metabolizing enzymes, glycolytic enzymes, and mitochondria/mitochondrial proteins. This functional coupling is bi-directional with many of these systems both being regulated by glutamate transport and providing the 'fuel' to support glutamate uptake. Given the importance of glutamate uptake to maintaining synaptic signaling and preventing excitotoxicity, it should not be surprising that some of these systems appear to 'redundantly' support the energetic costs of glutamate uptake. Although the glutamate-glutamine cycle contributes to recycling of neurotransmitter pools of glutamate, this is an over-simplification. The ramifications of co-compartmentalization of glutamate transporters with mitochondria for glutamate metabolism are discussed. Energy consumption in the brain accounts for ∼20% of the basal metabolic rate and relies almost exclusively on glucose for the production of ATP. However, the brain does not possess substantial reserves of glucose or other fuels. To ensure adequate energetic supply, increases in neuronal activity are matched by increases in cerebral blood flow via a process known as 'neurovascular coupling'. While the mechanisms for this coupling are not completely resolved, it is generally agreed that astrocytes, with processes that extend to synapses and endfeet that surround blood vessels, mediate at least some of the signal that causes vasodilation. Several studies have shown that either genetic deletion or pharmacologic inhibition of glutamate transport impairs neurovascular coupling. Together these studies strongly suggest that glutamate transport not only coordinates excitatory signaling, but also plays a pivotal role in regulating brain energetics.
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12
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The transmembrane transporter domain of glutamate transporters is a process tip localizer. Sci Rep 2015; 5:9032. [PMID: 25761899 PMCID: PMC4357008 DOI: 10.1038/srep09032] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 02/10/2015] [Indexed: 01/09/2023] Open
Abstract
Glutamate transporters in the central nervous system remove glutamate released from neurons to terminate the signal. These transporters localize to astrocyte process tips approaching neuronal synapses. The mechanisms underlying the localization of glutamate transporters to these processes, however, are not known. In this study, we demonstrate that the trimeric transmembrane transporter domain fragment of glutamate transporters, lacking both N- and C-terminal cytoplasmic regions, localized to filopodia tips. This is a common property of trimeric transporters including a neutral amino acid transporter ASCT1. Astrocyte specific proteins are not required for the filopodia tip localization. An extracellular loop at the centre of the 4th transmembrane helices, unique for metazoans, is required for the localization. Moreover, a C186S mutation at the 4th transmembrane region of EAAT1, found in episodic ataxia patients, significantly decreased its process tip localization. The transmembrane transporter domain fragments of glutamate transporters also localized to astrocyte process tips in cultured hippocampal slice. These results indicate that the transmembrane transporter domain of glutamate transporters have an additional function as a sorting signal to process tips.
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14
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: transporters. Br J Pharmacol 2013; 170:1706-96. [PMID: 24528242 PMCID: PMC3892292 DOI: 10.1111/bph.12450] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. Transporters are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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Pita-Almenar JD, Zou S, Colbert CM, Eskin A. Relationship between increase in astrocytic GLT-1 glutamate transport and late-LTP. Learn Mem 2012; 19:615-26. [PMID: 23166293 DOI: 10.1101/lm.023259.111] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Na⁺-dependent high-affinity glutamate transporters have important roles in the maintenance of basal levels of glutamate and clearance of glutamate during synaptic transmission. Interestingly, several studies have shown that basal glutamate transport displays plasticity. Glutamate uptake increases in hippocampal slices during early long-term potentiation (E-LTP) and late long-term potentiation (L-LTP). Four issues were addressed in this research: Which glutamate transporter is responsible for the increase in glutamate uptake during L-LTP? In what cell type in the hippocampus does the increase in glutamate uptake occur? Does a single type of cell contain all the mechanisms to respond to an induction stimulus with a change in glutamate uptake? What role does the increase in glutamate uptake play during L-LTP? We have confirmed that GLT-1 is responsible for the increase in glutamate uptake during L-LTP. Also, we found that astrocytes were responsible for much, if not all, of the increase in glutamate uptake in hippocampal slices during L-LTP. Additionally, we found that cultured astrocytes alone were able to respond to an induction stimulus with an increase in glutamate uptake. Inhibition of basal glutamate uptake did not affect the induction of L-LTP, but inhibition of the increase in glutamate uptake did inhibit both the expression of L-LTP and induction of additional LTP. It seems likely that heightened glutamate transport plays an ongoing role in the ability of hippocampal circuitry to code and store information.
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Affiliation(s)
- Juan D Pita-Almenar
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204-5001, USA
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Coxsackievirus and adenovirus receptor (CAR) mediates trafficking of acid sensing ion channel 3 (ASIC3) via PSD-95. Biochem Biophys Res Commun 2012; 425:13-8. [PMID: 22809504 DOI: 10.1016/j.bbrc.2012.07.033] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 07/07/2012] [Indexed: 01/14/2023]
Abstract
We have previously shown that the Coxsackievirus and adenovirus receptor (CAR) can interact with post-synaptic density 95 (PSD-95) and localize PSD-95 to cell-cell junctions. We have also shown that activity of the acid sensing ion channel (ASIC3), a H(+)-gated cation channel that plays a role in mechanosensation and pain signaling, is negatively modulated by PSD-95 through a PDZ-based interaction. We asked whether CAR and ASIC3 simultaneously interact with PSD-95, and if so, whether co-expression of these proteins alters their cellular distribution and localization. Results indicate that CAR and ASIC3 co-immunoprecipitate only when co-expressed with PSD-95. CAR also brings both PSD-95 and ASIC3 to the junctions of heterologous cells. Moreover, CAR rescues PSD-95-mediated inhibition of ASIC3 currents. These data suggest that, in addition to activity as a viral receptor and adhesion molecule, CAR can play a role in trafficking proteins, including ion channels, in a PDZ-based scaffolding complex.
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Genda EN, Jackson JG, Sheldon AL, Locke SF, Greco TM, O'Donnell JC, Spruce LA, Xiao R, Guo W, Putt M, Seeholzer S, Ischiropoulos H, Robinson MB. Co-compartmentalization of the astroglial glutamate transporter, GLT-1, with glycolytic enzymes and mitochondria. J Neurosci 2011; 31:18275-88. [PMID: 22171032 PMCID: PMC3259858 DOI: 10.1523/jneurosci.3305-11.2011] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Efficient excitatory transmission depends on a family of transporters that use the Na(+)-electrochemical gradient to maintain low synaptic concentrations of glutamate. These transporters consume substantial energy in the spatially restricted space of fine astrocytic processes. GLT-1 (EAAT2) mediates the bulk of this activity in forebrain. To date, relatively few proteins have been identified that associate with GLT-1. In the present study, GLT-1 immunoaffinity isolates were prepared from rat cortex using three strategies and analyzed by liquid chromatography-coupled tandem mass spectrometry. In addition to known interacting proteins, the analysis identified glycolytic enzymes and outer mitochondrial proteins. Using double-label immunofluorescence, GLT-1 was shown to colocalize with the mitochondrial matrix protein, ubiquinol-cytochrome c reductase core protein 2 or the inner mitochondrial membrane protein, ADP/ATP translocase, in rat cortex. In biolistically transduced hippocampal slices, fluorescently tagged GLT-1 puncta overlapped with fluorescently tagged mitochondria along fine astrocytic processes. In a Monte Carlo-type computer simulation, this overlap was significantly more frequent than would occur by chance. Furthermore, fluorescently tagged hexokinase-1 overlapped with mitochondria or GLT-1, strongly suggesting that GLT-1, mitochondria, and the first step in glycolysis are cocompartmentalized in astrocytic processes. Acute inhibition of glycolysis or oxidative phosphorylation had no effect on glutamate uptake in hippocampal slices, but simultaneous inhibition of both processes significantly reduced transport. Together with previous results, these studies show that GLT-1 cocompartmentalizes with Na(+)/K(+) ATPase, glycolytic enzymes, and mitochondria, providing a mechanism to spatially match energy and buffering capacity to the demands imposed by transport.
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Affiliation(s)
| | - Joshua G. Jackson
- 1Children's Hospital of Philadelphia Research Institute and
- 2Departments of Pediatrics,
| | - Amanda L. Sheldon
- 1Children's Hospital of Philadelphia Research Institute and
- 2Departments of Pediatrics,
- 3Neuroscience,
| | | | - Todd M. Greco
- 1Children's Hospital of Philadelphia Research Institute and
- 2Departments of Pediatrics,
- 3Neuroscience,
| | - John C. O'Donnell
- 1Children's Hospital of Philadelphia Research Institute and
- 4Pharmacology, and
| | - Lynn A. Spruce
- 1Children's Hospital of Philadelphia Research Institute and
| | - Rui Xiao
- 5Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Wensheng Guo
- 5Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Mary Putt
- 5Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | | | - Harry Ischiropoulos
- 1Children's Hospital of Philadelphia Research Institute and
- 2Departments of Pediatrics,
- 4Pharmacology, and
| | - Michael B. Robinson
- 1Children's Hospital of Philadelphia Research Institute and
- 2Departments of Pediatrics,
- 4Pharmacology, and
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