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Tian J, Jia K, Wang T, Guo L, Xuan Z, Michaelis EK, Swerdlow RH, Du H. Hippocampal transcriptome-wide association study and pathway analysis of mitochondrial solute carriers in Alzheimer's disease. Transl Psychiatry 2024; 14:250. [PMID: 38858380 PMCID: PMC11164935 DOI: 10.1038/s41398-024-02958-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 05/14/2024] [Accepted: 05/21/2024] [Indexed: 06/12/2024] Open
Abstract
The etiopathogenesis of late-onset Alzheimer's disease (AD) is increasingly recognized as the result of the combination of the aging process, toxic proteins, brain dysmetabolism, and genetic risks. Although the role of mitochondrial dysfunction in the pathogenesis of AD has been well-appreciated, the interaction between mitochondrial function and genetic variability in promoting dementia is still poorly understood. In this study, by tissue-specific transcriptome-wide association study (TWAS) and further meta-analysis, we examined the genetic association between mitochondrial solute carrier family (SLC25) genes and AD in three independent cohorts and identified three AD-susceptibility genes, including SLC25A10, SLC25A17, and SLC25A22. Integrative analysis using neuroimaging data and hippocampal TWAS-predicted gene expression of the three susceptibility genes showed an inverse correlation of SLC25A22 with hippocampal atrophy rate in AD patients, which outweighed the impacts of sex, age, and apolipoprotein E4 (ApoE4). Furthermore, SLC25A22 downregulation demonstrated an association with AD onset, as compared with the other two transcriptome-wide significant genes. Pathway and network analysis related hippocampal SLC25A22 downregulation to defects in neuronal function and development, echoing the enrichment of SLC25A22 expression in human glutamatergic neurons. The most parsimonious interpretation of the results is that we have identified AD-susceptibility genes in the SLC25 family through the prediction of hippocampal gene expression. Moreover, our findings mechanistically yield insight into the mitochondrial cascade hypothesis of AD and pave the way for the future development of diagnostic tools for the early prevention of AD from a perspective of precision medicine by targeting the mitochondria-related genes.
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Affiliation(s)
- Jing Tian
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA
| | - Kun Jia
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA
| | - Tienju Wang
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA
| | - Lan Guo
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA
| | - Zhenyu Xuan
- Department of Biological Sciences, The University of Texas at Dallas, Richardson, TX, USA
| | - Elias K Michaelis
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS, USA
| | - Russell H Swerdlow
- Alzheimer's Disease Research Center, University of Kansas Medical Center, Kansas City, KS, USA
| | - Heng Du
- Department of Pharmacology and Toxicology, University of Kansas, Lawrence, KS, USA.
- Alzheimer's Disease Research Center, University of Kansas Medical Center, Kansas City, KS, USA.
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2
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O'Donovan SM, Shan D, Wu X, Choi JH, McCullumsmith RE. Dysregulated Transcript Expression but Not Function of the Glutamate Transporter EAAT2 in the Dorsolateral Prefrontal Cortex in Schizophrenia. Schizophr Bull 2024:sbae092. [PMID: 38825587 DOI: 10.1093/schbul/sbae092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 06/04/2024]
Abstract
BACKGROUND Schizophrenia (SCZ) is a serious mental illness with complex pathology, including abnormalities in the glutamate system. Glutamate is rapidly removed from the synapse by excitatory amino acid transporters (EAATs). Changes in the expression and localization of the primary glutamate transporter EAAT2 are found in the brain in central nervous system (CNS) disorders including SCZ. We hypothesize that neuronal expression and function of EAAT2 are increased in the frontal cortex in subjects diagnosed with SCZ. STUDY DESIGN EAAT2 protein expression and glutamate transporter function were assayed in synaptosome preparations from the dorsolateral prefrontal cortex (DLPFC) of SCZ subjects and age- and sex-matched nonpsychiatrically ill controls. EAAT2 splice variant transcript expression was assayed in enriched populations of neurons and astrocytes from the DLPFC. Pathway analysis of publicly available transcriptomic datasets was carried out to identify biological changes associated with EAAT2 perturbation in different cell types. RESULTS We found no significant changes in EAAT2 protein expression or glutamate uptake in the DLPFC in SCZ subjects compared with controls (n = 10/group). Transcript expression of EAAT2 and signaling molecules associated with EAAT2b trafficking (CaMKIIa and DLG1) were significantly altered in enriched populations of astrocytes and pyramidal neurons (P < .05) in SCZ (n = 16/group). These changes were not associated with antipsychotic medications. Pathway analysis also identified cell-type-specific enrichment of biological pathways associated with perturbation of astrocyte (immune pathways) and neuronal (metabolic pathways) EAAT2 expression. CONCLUSIONS Overall, these data support the growing body of evidence for the role of dysregulation of the glutamate system in the pathophysiology of SCZ.
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Affiliation(s)
| | - Dan Shan
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Xiaojun Wu
- Department of Neuroscience, University of Toledo, Toledo, OH, USA
| | - Jae Hyuk Choi
- Department of Neuroscience, University of Toledo, Toledo, OH, USA
| | - Robert E McCullumsmith
- Department of Neuroscience, University of Toledo, Toledo, OH, USA
- Promedica Neuroscience Institute, Toledo, OH, USA
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3
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Neves D, Salazar IL, Almeida RD, Silva RM. Molecular mechanisms of ischemia and glutamate excitotoxicity. Life Sci 2023; 328:121814. [PMID: 37236602 DOI: 10.1016/j.lfs.2023.121814] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Revised: 05/05/2023] [Accepted: 05/23/2023] [Indexed: 05/28/2023]
Abstract
Excitotoxicity is classically defined as the neuronal damage caused by the excessive release of glutamate, and subsequent activation of excitatory plasma membrane receptors. In the mammalian brain, this phenomenon is mainly driven by excessive activation of glutamate receptors (GRs). Excitotoxicity is common to several chronic disorders of the Central Nervous System (CNS) and is considered the primary mechanism of neuronal loss of function and cell death in acute CNS diseases (e.g. ischemic stroke). Multiple mechanisms and pathways lead to excitotoxic cell damage including pro-death signaling cascade events downstream of glutamate receptors, calcium (Ca2+) overload, oxidative stress, mitochondrial impairment, excessive glutamate in the synaptic cleft as well as altered energy metabolism. Here, we review the current knowledge on the molecular mechanisms that underlie excitotoxicity, emphasizing the role of Nicotinamide Adenine Dinucleotide (NAD) metabolism. We also discuss novel and promising therapeutic strategies to treat excitotoxicity, highlighting recent clinical trials. Finally, we will shed light on the ongoing search for stroke biomarkers, an exciting and promising field of research, which may improve stroke diagnosis, prognosis and allow better treatment options.
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Affiliation(s)
- Diogo Neves
- iBiMED - Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, Portugal
| | - Ivan L Salazar
- Multidisciplinary Institute of Ageing, MIA - Portugal, University of Coimbra, Coimbra, Portugal
| | - Ramiro D Almeida
- iBiMED - Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, Portugal; CNC - Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.
| | - Raquel M Silva
- iBiMED - Institute of Biomedicine, Department of Medical Sciences, University of Aveiro, Aveiro, Portugal; Universidade Católica Portuguesa, Faculdade de Medicina Dentária, Centro de Investigação Interdisciplinar em Saúde, Viseu, Portugal.
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4
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Ji N, Lei M, Chen Y, Tian S, Li C, Zhang B. How Oxidative Stress Induces Depression? ASN Neuro 2023; 15:17590914231181037. [PMID: 37331994 DOI: 10.1177/17590914231181037] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/20/2023] Open
Abstract
Depression increasingly affects a wide range and a large number of people worldwide, both physically and psychologically, which makes it a social problem requiring prompt attention and management. Accumulating clinical and animal studies have provided us with substantial insights of disease pathogenesis, especially central monoamine deficiency, which considerably promotes antidepressant research and clinical treatment. The first-line antidepressants mainly target the monoamine system, whose drawbacks mainly include slow action and treatment resistant. The novel antidepressant esketamine, targeting on central glutamatergic system, rapidly and robustly alleviates depression (including treatment-resistant depression), whose efficiency is shadowed by potential addictive and psychotomimetic side effects. Thus, exploring novel depression pathogenesis is necessary, for seeking more safe and effective therapeutic methods. Emerging evidence has revealed vital involvement of oxidative stress (OS) in depression, which inspires us to pursue antioxidant pathway for depression prevention and treatment. Fully uncovering the underlying mechanisms of OS-induced depression is the first step towards the avenue, thus we summarize and expound possible downstream pathways of OS, including mitochondrial impairment and related ATP deficiency, neuroinflammation, central glutamate excitotoxicity, brain-derived neurotrophic factor/tyrosine receptor kinase B dysfunction and serotonin deficiency, the microbiota-gut-brain axis disturbance and hypothalamic-pituitary-adrenocortical axis dysregulation. We also elaborate on the intricate interactions between the multiple aspects, and molecular mechanisms mediating the interplay. Through reviewing the related research progress in the field, we hope to depict an integral overview of how OS induces depression, in order to provide fresh ideas and novel targets for the final goal of efficient treatment of the disease.
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Affiliation(s)
- Na Ji
- The School of Public Health, Faculty of Basic Medical Sciences, Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin Guangxi, China
| | - Mengzhu Lei
- The School of Public Health, Faculty of Basic Medical Sciences, Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin Guangxi, China
| | - Yating Chen
- The School of Public Health, Faculty of Basic Medical Sciences, Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin Guangxi, China
| | - Shaowen Tian
- The School of Public Health, Faculty of Basic Medical Sciences, Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin Guangxi, China
| | - Chuanyu Li
- The School of Public Health, Faculty of Basic Medical Sciences, Guilin Medical University, Guilin Guangxi, China
| | - Bo Zhang
- The School of Public Health, Faculty of Basic Medical Sciences, Guangxi Key Laboratory of Brain and Cognitive Neuroscience, Guilin Medical University, Guilin Guangxi, China
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5
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Martinez-Lozada Z, Hewett SJ, Zafra F, Ortega A. Editorial: The known, the unknown, and the future of glutamate transporters. Front Cell Neurosci 2022; 16:1005834. [PMID: 36060278 PMCID: PMC9433117 DOI: 10.3389/fncel.2022.1005834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/04/2022] [Indexed: 11/29/2022] Open
Affiliation(s)
- Zila Martinez-Lozada
- Department of Pediatrics, The Children's Hospital of Philadelphia, Philadelphia, PA, United States
- *Correspondence: Zila Martinez-Lozada
| | - Sandra J. Hewett
- Program in Neuroscience, Department of Biology, Syracuse University, Syracuse, NY, United States
| | - Francisco Zafra
- Center of Molecular Biology Severo Ochoa, School of Science, Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain
- Instituto de Investigación Sanitaria del Hospital Universitario La Paz — IdiPAZ, Madrid, Spain
| | - Arturo Ortega
- Department of Toxicology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Ciudad de México, Mexico
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6
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Olguin SL, Patel P, Buchanan CN, Dell'Orco M, Gardiner AS, Cole R, Vaughn LS, Sundararajan A, Mudge J, Allan AM, Ortinski P, Brigman JL, Twiss JL, Perrone-Bizzozero NI. KHSRP loss increases neuronal growth and synaptic transmission and alters memory consolidation through RNA stabilization. Commun Biol 2022; 5:672. [PMID: 35798971 PMCID: PMC9262970 DOI: 10.1038/s42003-022-03594-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 06/16/2022] [Indexed: 02/04/2023] Open
Abstract
The KH-type splicing regulatory protein (KHSRP) is an RNA-binding protein linked to decay of mRNAs with AU-rich elements. KHSRP was previously shown to destabilize Gap43 mRNA and decrease neurite growth in cultured embryonic neurons. Here, we have tested functions of KHSRP in vivo. We find upregulation of 1460 mRNAs in neocortex of adult Khsrp-/- mice, of which 527 bind to KHSRP with high specificity. These KHSRP targets are involved in pathways for neuronal morphology, axon guidance, neurotransmission and long-term memory. Khsrp-/- mice show increased axon growth and dendritic spine density in vivo. Neuronal cultures from Khsrp-/- mice show increased axon and dendrite growth and elevated KHSRP-target mRNAs, including subcellularly localized mRNAs. Furthermore, neuron-specific knockout of Khsrp confirms these are from neuron-intrinsic roles of KHSRP. Consistent with this, neurons in the hippocampus and infralimbic cortex of Khsrp-/- mice show elevations in frequency of miniature excitatory postsynaptic currents. The Khsrp-/- mice have deficits in trace conditioning and attention set-shifting tasks compared Khsrp+/+ mice, indicating impaired prefrontal- and hippocampal-dependent memory consolidation with loss of KHSRP. Overall, these results indicate that deletion of KHSRP impairs neuronal development resulting in alterations in neuronal morphology and function by changing post-transcriptional control of neuronal gene expression.
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Affiliation(s)
- Sarah L Olguin
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Priyanka Patel
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | - Courtney N Buchanan
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | - Michela Dell'Orco
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Amy S Gardiner
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Robert Cole
- Department of Neuroscience, University of Kentucky, Lexington, KY, 40536, USA
| | - Lauren S Vaughn
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | | | - Joann Mudge
- National Center for Genome Resources, Santa Fe, NM, 87505, USA
| | - Andrea M Allan
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Pavel Ortinski
- Department of Neuroscience, University of Kentucky, Lexington, KY, 40536, USA
| | - Jonathan L Brigman
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA.
- Carolina Autism and Neurodevelopment Center, University of South Carolina, Columbia, SC, 29208, USA.
| | - Nora I Perrone-Bizzozero
- Department of Neurosciences, University of New Mexico School of Medicine, Albuquerque, NM, 87131, USA
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7
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Zhang Y, Chu JMT, Wong GTC. Cerebral Glutamate Regulation and Receptor Changes in Perioperative Neuroinflammation and Cognitive Dysfunction. Biomolecules 2022; 12:biom12040597. [PMID: 35454185 PMCID: PMC9029551 DOI: 10.3390/biom12040597] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 04/11/2022] [Accepted: 04/15/2022] [Indexed: 12/23/2022] Open
Abstract
Glutamate is the major excitatory neurotransmitter in the central nervous system and is intricately linked to learning and memory. Its activity depends on the expression of AMPA and NMDA receptors and excitatory amino transporters on neurons and glial cells. Glutamate transporters prevent the excess accumulation of glutamate in synapses, which can lead to aberrant synaptic signaling, excitotoxicity, or cell death. Neuroinflammation can occur acutely after surgical trauma and contributes to the development of perioperative neurocognitive disorders, which are characterized by impairment in multiple cognitive domains. In this review, we aim to examine how glutamate handling and glutamatergic function are affected by neuroinflammation and their contribution to cognitive impairment. We will first summarize the current data regarding glutamate in neurotransmission, its receptors, and their regulation and trafficking. We will then examine the impact of inflammation on glutamate handling and neurotransmission, focusing on changes in glial cells and the effect of cytokines. Finally, we will discuss these changes in the context of perioperative neuroinflammation and the implications they have for perioperative neurocognitive disorders.
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8
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Estimating the glutamate transporter surface density in distinct sub-cellular compartments of mouse hippocampal astrocytes. PLoS Comput Biol 2022; 18:e1009845. [PMID: 35120128 PMCID: PMC8849624 DOI: 10.1371/journal.pcbi.1009845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 02/16/2022] [Accepted: 01/18/2022] [Indexed: 11/19/2022] Open
Abstract
Glutamate transporters preserve the spatial specificity of synaptic transmission by limiting glutamate diffusion away from the synaptic cleft, and prevent excitotoxicity by keeping the extracellular concentration of glutamate at low nanomolar levels. Glutamate transporters are abundantly expressed in astrocytes, and previous estimates have been obtained about their surface expression in astrocytes of the rat hippocampus and cerebellum. Analogous estimates for the mouse hippocampus are currently not available. In this work, we derive the surface density of astrocytic glutamate transporters in mice of different ages via quantitative dot blot. We find that the surface density of glial glutamate transporters is similar in 7-8 week old mice and rats. In mice, the levels of glutamate transporters increase until about 6 months of age and then begin to decline slowly. Our data, obtained from a combination of experimental and modeling approaches, point to the existence of stark differences in the density of expression of glutamate transporters across different sub-cellular compartments, indicating that the extent to which astrocytes limit extrasynaptic glutamate diffusion depends not only on their level of synaptic coverage, but also on the identity of the astrocyte compartment in contact with the synapse. Together, these findings provide information on how heterogeneity in the spatial distribution of glutamate transporters in the plasma membrane of hippocampal astrocytes my alter glutamate receptor activation out of the synaptic cleft.
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9
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Rimmele TS, Li S, Andersen JV, Westi EW, Rotenberg A, Wang J, Aldana BI, Selkoe DJ, Aoki CJ, Dulla CG, Rosenberg PA. Neuronal Loss of the Glutamate Transporter GLT-1 Promotes Excitotoxic Injury in the Hippocampus. Front Cell Neurosci 2022; 15:788262. [PMID: 35035352 PMCID: PMC8752461 DOI: 10.3389/fncel.2021.788262] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 12/08/2021] [Indexed: 12/26/2022] Open
Abstract
GLT-1, the major glutamate transporter in the mammalian central nervous system, is expressed in presynaptic terminals that use glutamate as a neurotransmitter, in addition to astrocytes. It is widely assumed that glutamate homeostasis is regulated primarily by glutamate transporters expressed in astrocytes, leaving the function of GLT-1 in neurons relatively unexplored. We generated conditional GLT-1 knockout (KO) mouse lines to understand the cell-specific functions of GLT-1. We found that stimulus-evoked field extracellular postsynaptic potentials (fEPSPs) recorded in the CA1 region of the hippocampus were normal in the astrocytic GLT-1 KO but were reduced and often absent in the neuronal GLT-1 KO at 40 weeks. The failure of fEPSP generation in the neuronal GLT-1 KO was also observed in slices from 20 weeks old mice but not consistently from 10 weeks old mice. Using an extracellular FRET-based glutamate sensor, we found no difference in stimulus-evoked glutamate accumulation in the neuronal GLT-1 KO, suggesting a postsynaptic cause of the transmission failure. We hypothesized that excitotoxicity underlies the failure of functional recovery of slices from the neuronal GLT-1 KO. Consistent with this hypothesis, the non-competitive NMDA receptor antagonist MK801, when present in the ACSF during the recovery period following cutting of slices, promoted full restoration of fEPSP generation. The inclusion of an enzymatic glutamate scavenging system in the ACSF conferred partial protection. Excitotoxicity might be due to excess release or accumulation of excitatory amino acids, or to metabolic perturbation resulting in increased vulnerability to NMDA receptor activation. Previous studies have demonstrated a defect in the utilization of glutamate by synaptic mitochondria and aspartate production in the synGLT-1 KO in vivo, and we found evidence for similar metabolic perturbations in the slice preparation. In addition, mitochondrial cristae density was higher in synaptic mitochondria in the CA1 region in 20–25 weeks old synGLT-1 KO mice in the CA1 region, suggesting compensation for loss of axon terminal GLT-1 by increased mitochondrial efficiency. These data suggest that GLT-1 expressed in presynaptic terminals serves an important role in the regulation of vulnerability to excitotoxicity, and this regulation may be related to the metabolic role of GLT-1 expressed in glutamatergic axon terminals.
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Affiliation(s)
- Theresa S Rimmele
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States
| | - Shaomin Li
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States
| | - Jens Velde Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Emil W Westi
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Alexander Rotenberg
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Program in Neuroscience, Harvard Medical School, Boston, MA, United States
| | - Jianlin Wang
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States
| | - Blanca Irene Aldana
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Dennis J Selkoe
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States
| | - Chiye J Aoki
- Center for Neural Science, New York University, NY, United States.,Neuroscience Institute NYU Langone Medical Center, NY, United States
| | - Chris G Dulla
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, United States
| | - Paul Allen Rosenberg
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States.,Program in Neuroscience, Harvard Medical School, Boston, MA, United States
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10
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Rapid Regulation of Glutamate Transport: Where Do We Go from Here? Neurochem Res 2022; 47:61-84. [PMID: 33893911 PMCID: PMC8542062 DOI: 10.1007/s11064-021-03329-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/08/2021] [Accepted: 04/13/2021] [Indexed: 01/03/2023]
Abstract
Glutamate is the predominant excitatory neurotransmitter in the mammalian central nervous system (CNS). A family of five Na+-dependent transporters maintain low levels of extracellular glutamate and shape excitatory signaling. Shortly after the research group of the person being honored in this special issue (Dr. Baruch Kanner) cloned one of these transporters, his group and several others showed that their activity can be acutely (within minutes to hours) regulated. Since this time, several different signals and post-translational modifications have been implicated in the regulation of these transporters. In this review, we will provide a brief introduction to the distribution and function of this family of glutamate transporters. This will be followed by a discussion of the signals that rapidly control the activity and/or localization of these transporters, including protein kinase C, ubiquitination, glutamate transporter substrates, nitrosylation, and palmitoylation. We also include the results of our attempts to define the role of palmitoylation in the regulation of GLT-1 in crude synaptosomes. In some cases, the mechanisms have been fairly well-defined, but in others, the mechanisms are not understood. In several cases, contradictory phenomena have been observed by more than one group; we describe these studies with the goal of identifying the opportunities for advancing the field. Abnormal glutamatergic signaling has been implicated in a wide variety of psychiatric and neurologic disorders. Although recent studies have begun to link regulation of glutamate transporters to the pathogenesis of these disorders, it will be difficult to determine how regulation influences signaling or pathophysiology of glutamate without a better understanding of the mechanisms involved.
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11
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Thomason EJ, Suárez-Pozos E, Afshari FS, Rosenberg PA, Dupree JL, Fuss B. Deletion of the Sodium-Dependent Glutamate Transporter GLT-1 in Maturing Oligodendrocytes Attenuates Myelination of Callosal Axons During a Postnatal Phase of Central Nervous System Development. Front Cell Neurosci 2022; 16:905299. [PMID: 35722615 PMCID: PMC9203689 DOI: 10.3389/fncel.2022.905299] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 05/16/2022] [Indexed: 11/13/2022] Open
Abstract
The sodium-dependent glutamate transporter GLT-1 (EAAT2, SLC1A2) has been well-described as an important regulator of extracellular glutamate homeostasis in the central nervous system (CNS), a function that is performed mainly through its presence on astrocytes. There is, however, increasing evidence for the expression of GLT-1 in CNS cells other than astrocytes and in functional roles that are mediated by mechanisms downstream of glutamate uptake. In this context, GLT-1 expression has been reported for both neurons and oligodendrocytes (OLGs), and neuronal presynaptic presence of GLT-1 has been implicated in the regulation of glutamate uptake, gene expression, and mitochondrial function. Much less is currently known about the functional roles of GLT-1 expressed by OLGs. The data presented here provide first evidence that GLT-1 expressed by maturing OLGs contributes to the modulation of developmental myelination in the CNS. More specifically, using inducible and conditional knockout mice in which GLT-1 was deleted in maturing OLGs during a peak period of myelination (between 2 and 4 weeks of age) revealed hypomyelinated characteristics in the corpus callosum of preferentially male mice. These characteristics included reduced percentages of smaller diameter myelinated axons and reduced myelin thickness. Interestingly, this myelination phenotype was not found to be associated with major changes in myelin gene expression. Taken together, the data presented here demonstrate that GLT-1 expressed by maturing OLGs is involved in the modulation of the morphological aspects associated with CNS myelination in at least the corpus callosum and during a developmental window that appears of particular vulnerability in males compared to females.
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Affiliation(s)
- Elizabeth J Thomason
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, United States
| | - Edna Suárez-Pozos
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, United States
| | - Fatemah S Afshari
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, United States
| | - Paul A Rosenberg
- Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, United States
| | - Jeffrey L Dupree
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, United States
| | - Babette Fuss
- Department of Anatomy and Neurobiology, Virginia Commonwealth University School of Medicine, Richmond, VA, United States
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12
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Stachowicz K, Bobula B, Kusek M, Lenda T, Tokarski K. Evidence for the interaction of COX-2 with mGluR5 in the regulation of EAAT1 and EAAT3 protein levels in the mouse hippocampus. The influence of oxidative stress mechanisms. Brain Res 2021; 1771:147660. [PMID: 34529964 DOI: 10.1016/j.brainres.2021.147660] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/17/2021] [Accepted: 09/07/2021] [Indexed: 12/29/2022]
Abstract
Since we found that inhibition of cyclooxygenase-2 (COX-2) with concomitant application of a metabotropic glutamate receptor subtype 5 (mGluR5) antagonist (MTEP) down-regulates mGluR7 in the hippocampus (HC) and changes behavior of mice, our team decided to investigate the mechanism responsible for the observed changes. The amino acid glutamate (Glu) is a major excitatory neurotransmitter in the brain. Glu uptake is regulated by excitatory amino acid transporters (EAAT). There are five transporters with documented expression in neurons and glia in the central nervous system (CNS). EAATs, maintain the correct transmission of the Glu signal and prevent its toxic accumulation by removing Glu from the synapse. It has been documented that the toxic level of Glu is one of the main causes of mental and cognitive abnormalities. Given the above mechanisms involved in the functioning of the Glu synapse, we hypothesized modification of Glu uptake, involving EAATs as the cause of the observed changes. This study investigated the level of selected EAATs in the HC after chronic treatment with mGluR5 antagonist MTEP, NS398, and their combination using Western blot. Concomitant MTEP treatment with NS398 or a single administration of the above causes changes in LTP and modulation of EAAT levels in mouse HC. As EAATs are cellular markers of oxidative stress mechanisms, the E. coli lipopolysaccharide (LPS) challenge was performed. The modified Barnes maze test (MBM) revealed alterations in the mouse spatial learning abilities. This study reports an interaction between the mGluR5 and COX-2 in the HC, with EAAT1 and EAAT3 involvement.
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Affiliation(s)
- Katarzyna Stachowicz
- Department of Neurobiology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland.
| | - Bartosz Bobula
- Department of Physiology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland
| | - Magdalena Kusek
- Department of Physiology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland
| | - Tomasz Lenda
- Department of Neuro- and Psychopharmacology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland
| | - Krzysztof Tokarski
- Department of Physiology, Maj Institute of Pharmacology, Polish Academy of Sciences, Smętna 12, 31-343 Kraków, Poland
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Andersen JV, Markussen KH, Jakobsen E, Schousboe A, Waagepetersen HS, Rosenberg PA, Aldana BI. Glutamate metabolism and recycling at the excitatory synapse in health and neurodegeneration. Neuropharmacology 2021; 196:108719. [PMID: 34273389 DOI: 10.1016/j.neuropharm.2021.108719] [Citation(s) in RCA: 140] [Impact Index Per Article: 46.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 07/01/2021] [Accepted: 07/13/2021] [Indexed: 02/08/2023]
Abstract
Glutamate is the primary excitatory neurotransmitter of the brain. Cellular homeostasis of glutamate is of paramount importance for normal brain function and relies on an intricate metabolic collaboration between neurons and astrocytes. Glutamate is extensively recycled between neurons and astrocytes in a process known as the glutamate-glutamine cycle. The recycling of glutamate is closely linked to brain energy metabolism and is essential to sustain glutamatergic neurotransmission. However, a considerable amount of glutamate is also metabolized and serves as a metabolic hub connecting glucose and amino acid metabolism in both neurons and astrocytes. Disruptions in glutamate clearance, leading to neuronal overstimulation and excitotoxicity, have been implicated in several neurodegenerative diseases. Furthermore, the link between brain energy homeostasis and glutamate metabolism is gaining attention in several neurological conditions. In this review, we provide an overview of the dynamics of synaptic glutamate homeostasis and the underlying metabolic processes with a cellular focus on neurons and astrocytes. In particular, we review the recently discovered role of neuronal glutamate uptake in synaptic glutamate homeostasis and discuss current advances in cellular glutamate metabolism in the context of Alzheimer's disease and Huntington's disease. Understanding the intricate regulation of glutamate-dependent metabolic processes at the synapse will not only increase our insight into the metabolic mechanisms of glutamate homeostasis, but may reveal new metabolic targets to ameliorate neurodegeneration.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
| | - Kia H Markussen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark; Department of Molecular and Cellular Biochemistry, College of Medicine, University of Kentucky, Lexington, KY, USA
| | - Emil Jakobsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Paul A Rosenberg
- Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, USA; Program in Neuroscience, Harvard Medical School, Boston, MA, USA
| | - Blanca I Aldana
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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14
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Rusakov DA, Stewart MG. Synaptic environment and extrasynaptic glutamate signals: The quest continues. Neuropharmacology 2021; 195:108688. [PMID: 34174263 DOI: 10.1016/j.neuropharm.2021.108688] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 12/11/2022]
Abstract
Behaviour of a mammal relies on the brain's excitatory circuits equipped with glutamatergic synapses. In most cases, glutamate escaping from the synaptic cleft is rapidly buffered and taken up by high-affinity transporters expressed by nearby perisynaptic astroglial processes (PAPs). The spatial relationship between glutamatergic synapses and PAPs thus plays a crucial role in understanding glutamate signalling actions, yet its intricate features can only be fully appreciated using methods that operate beyond the diffraction limit of light. Here, we examine principal aspects pertaining to the receptor actions of glutamate, inside and outside the synaptic cleft in the brain, where the organisation of synaptic micro-physiology and micro-environment play a critical part. In what conditions and how far glutamate can escape the synaptic cleft activating its target receptors outside the immediate synapse has long been the subject of debate. Evidence is also emerging that neuronal activity- and astroglia-dependent glutamate spillover actions could be important across the spectrum of cognitive functions This article is part of the special issue on 'Glutamate Receptors - The Glutamatergic Synapse'.
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Affiliation(s)
- Dmitri A Rusakov
- UCL Queen Square Institute of Neurology, University College London, Queen Square, London, WC1N 3BG, UK.
| | - Michael G Stewart
- Dept of Life Sciences, The Open University, Milton Keynes, MK7 6AA, UK.
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15
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Danbolt NC, López-Corcuera B, Zhou Y. Reconstitution of GABA, Glycine and Glutamate Transporters. Neurochem Res 2021; 47:85-110. [PMID: 33905037 PMCID: PMC8763731 DOI: 10.1007/s11064-021-03331-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 04/13/2021] [Accepted: 04/15/2021] [Indexed: 10/25/2022]
Abstract
In contrast to water soluble enzymes which can be purified and studied while in solution, studies of solute carrier (transporter) proteins require both that the protein of interest is situated in a phospholipid membrane and that this membrane forms a closed compartment. An additional challenge to the study of transporter proteins has been that the transport depends on the transmembrane electrochemical gradients. Baruch I. Kanner understood this early on and first developed techniques for studying plasma membrane vesicles. This advanced the field in that the experimenter could control the electrochemical gradients. Kanner, however, did not stop there, but started to solubilize the membranes so that the transporter proteins were taken out of their natural environment. In order to study them, Kanner then had to find a way to reconstitute them (reinsert them into phospholipid membranes). The scope of the present review is both to describe the reconstitution method in full detail as that has never been done, and also to reveal the scientific impact that this method has had. Kanner's later work is not reviewed here although that also deserves a review because it too has had a huge impact.
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Affiliation(s)
- Niels Christian Danbolt
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway.
| | - Beatriz López-Corcuera
- Departamento de Biología Molecular, Universidad Autónoma de Madrid, Madrid, Spain.,Centro de Biología Molecular "Severo Ochoa" Consejo Superior de Investigaciones Científicas, Universidad Autónoma de Madrid, Madrid, Spain.,IdiPAZ, Hospital Universitario La Paz, Madrid, Spain
| | - Yun Zhou
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
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16
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Dhaher R, Gruenbaum SE, Sandhu MRS, Ottestad-Hansen S, Tu N, Wang Y, Lee TSW, Deshpande K, Spencer DD, Danbolt NC, Zaveri HP, Eid T. Network-Related Changes in Neurotransmitters and Seizure Propagation During Rodent Epileptogenesis. Neurology 2021; 96:e2261-e2271. [PMID: 33722994 PMCID: PMC8166437 DOI: 10.1212/wnl.0000000000011846] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 01/29/2021] [Indexed: 12/24/2022] Open
Abstract
OBJECTIVE To test the hypothesis that glutamate and GABA are linked to the formation of epilepsy networks and the triggering of spontaneous seizures, we examined seizure initiation/propagation characteristics and neurotransmitter levels during epileptogenesis in a translationally relevant rodent model of mesial temporal lobe epilepsy. METHODS The glutamine synthetase (GS) inhibitor methionine sulfoximine was infused into one of the hippocampi in laboratory rats to create a seizure focus. Long-term video-intracranial EEG recordings and brain microdialysis combined with mass spectrometry were used to examine seizure initiation, seizure propagation, and extracellular brain levels of glutamate and GABA. RESULTS All seizures (n = 78 seizures, n = 3 rats) appeared first in the GS-inhibited hippocampus of all animals, followed by propagation to the contralateral hippocampus. Propagation time decreased significantly from 11.65 seconds early in epileptogenesis (weeks 1-2) to 6.82 seconds late in epileptogenesis (weeks 3-4, paired t test, p = 0.025). Baseline extracellular glutamate levels were 11.6-fold higher in the hippocampus of seizure propagation (7.3 µM) vs the hippocampus of seizure onset (0.63 µM, analysis of variance/Fisher least significant difference, p = 0.01), even though the concentrations of the major glutamate transporter proteins excitatory amino acid transporter subtypes 1 and 2 and xCT were unchanged between the brain regions. Finally, extracellular GABA in the seizure focus decreased significantly from baseline several hours before a spontaneous seizure (paired t test/false discovery rate). CONCLUSION The changes in glutamate and GABA suggest novel and potentially important roles of the amino acids in epilepsy network formation and in the initiation and propagation of spontaneous seizures.
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Affiliation(s)
- Roni Dhaher
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Shaun E Gruenbaum
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Mani Ratnesh S Sandhu
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Sigrid Ottestad-Hansen
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Nathan Tu
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Yue Wang
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Tih-Shih W Lee
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Ketaki Deshpande
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Dennis D Spencer
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Niels Christian Danbolt
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Hitten P Zaveri
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway
| | - Tore Eid
- From the Departments of Laboratory Medicine (R.D., M.R.S.S., N.T., Y.W., K.D., T.E.), Anesthesiology (S.E.G.), Neurosurgery (D.D.S.), Psychiatry (T.-S.W.L.), and Neurology (H.P.Z.), Yale School of Medicine, New Haven, CT; and Department of Molecular Medicine (S.O.-H., N.C.D.), Division of Anatomy, Institute for Basic Medical Sciences, University of Oslo, Norway.
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17
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Fischer KD, Knackstedt LA, Rosenberg PA. Glutamate homeostasis and dopamine signaling: Implications for psychostimulant addiction behavior. Neurochem Int 2021; 144:104896. [PMID: 33159978 PMCID: PMC8489281 DOI: 10.1016/j.neuint.2020.104896] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 10/30/2020] [Accepted: 10/31/2020] [Indexed: 02/06/2023]
Abstract
Cocaine, amphetamine, and methamphetamine abuse disorders are serious worldwide health problems. To date, there are no FDA-approved medications for the treatment of these disorders. Elucidation of the biochemical underpinnings contributing to psychostimulant addiction is critical for the development of effective therapies. Excitatory signaling and glutamate homeostasis are well known pathophysiological substrates underlying addiction-related behaviors spanning multiple types of psychostimulants. To alleviate relapse behavior to psychostimulants, considerable interest has focused on GLT-1, the major glutamate transporter in the brain. While many brain regions are implicated in addiction behavior, this review focuses on two regions well known for their role in mediating the effects of cocaine and amphetamines, namely the nucleus accumbens (NAc) and the ventral tegmental area (VTA). In addition, because many investigators have utilized Cre-driver lines to selectively control gene expression in defined cell populations relevant for psychostimulant addiction, we discuss potential off-target effects of Cre-recombinase that should be considered in the design and interpretation of such experiments.
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Affiliation(s)
- Kathryn D Fischer
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
| | - Lori A Knackstedt
- Psychology Department, University of Florida, Gainesville, FL, 32611, USA
| | - Paul A Rosenberg
- Department of Neurology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA, 02115, USA; Program in Neuroscience, Harvard Medical School, Boston, MA, 02115, USA.
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18
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Brymer KJ, Barnes JR, Parsons MP. Entering a new era of quantifying glutamate clearance in health and disease. J Neurosci Res 2021; 99:1598-1617. [PMID: 33618436 DOI: 10.1002/jnr.24810] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 01/22/2021] [Accepted: 02/01/2021] [Indexed: 12/21/2022]
Abstract
Glutamate transporter proteins, expressed on both neurons and glia, serve as the main gatekeepers that dictate the spatial and temporal actions of extracellular glutamate. Glutamate is essential to the function of the healthy brain yet paradoxically contributes to the toxicity associated with many neurodegenerative diseases. Rapid transporter-mediated glutamate uptake, primarily occurring at astrocytic processes, tightens the efficiency of excitatory network activity and prevents toxic glutamate build-up in the extracellular space. Glutamate transporter dysfunction is thought to underlie myriad central nervous system (CNS) diseases including Alzheimer and Huntington disease. Over the past few decades, techniques such as biochemical uptake assays and electrophysiological recordings of transporter currents from individual astrocytes have revealed the remarkable ability of the CNS to efficiently clear extracellular glutamate. In more recent years, the rapidly evolving glutamate-sensing "sniffers" now allow researchers to visualize real-time glutamate transients on a millisecond time scale with single synapse spatial resolution in defined cell populations. As we transition to an increased reliance on optical-based methods of glutamate visualization and quantification, it is of utmost importance to understand not only the advantages that glutamate biosensors bring to the table but also the associated caveats and their implications for data interpretation. In this review, we summarize the strengths and limitations of the commonly used methods to quantify glutamate uptake. We then discuss what these techniques, when viewed as a complementary whole, have told us about the brain's ability to regulate glutamate levels, in both health and in the context of neurodegenerative disease.
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Affiliation(s)
- Kyle J Brymer
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Jocelyn R Barnes
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Matthew P Parsons
- Faculty of Medicine, Division of Biomedical Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
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19
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Sears SM, Hewett SJ. Influence of glutamate and GABA transport on brain excitatory/inhibitory balance. Exp Biol Med (Maywood) 2021; 246:1069-1083. [PMID: 33554649 DOI: 10.1177/1535370221989263] [Citation(s) in RCA: 64] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
An optimally functional brain requires both excitatory and inhibitory inputs that are regulated and balanced. A perturbation in the excitatory/inhibitory balance-as is the case in some neurological disorders/diseases (e.g. traumatic brain injury Alzheimer's disease, stroke, epilepsy and substance abuse) and disorders of development (e.g. schizophrenia, Rhett syndrome and autism spectrum disorder)-leads to dysfunctional signaling, which can result in impaired cognitive and motor function, if not frank neuronal injury. At the cellular level, transmission of glutamate and GABA, the principle excitatory and inhibitory neurotransmitters in the central nervous system control excitatory/inhibitory balance. Herein, we review the synthesis, release, and signaling of GABA and glutamate followed by a focused discussion on the importance of their transport systems to the maintenance of excitatory/inhibitory balance.
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Affiliation(s)
- Sheila Ms Sears
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
| | - Sandra J Hewett
- Department of Biology, Program in Neuroscience, 2029Syracuse University, Syracuse, NY 13244, USA
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20
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Wang J, Qu S. Conformationally Sensitive Proximity Between the TM3-4 Loop and Hairpin Loop 2 of the Glutamate Transporter EAAT2 Revealed by Paired-Cysteine Mutagenesis. ACS Chem Neurosci 2021; 12:163-175. [PMID: 33315395 DOI: 10.1021/acschemneuro.0c00645] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Excitatory amino acid transporters (EAATs) serve to maintain extracellular neurotransmitter concentrations below neurotoxic levels by transporting glutamate from the synaptic cleft into apposed glia and neurons. Although the crystal structures of the archaeal EAAT homologue from Pyrococcus horikoshii, GltPh, and the human glutamate transporter, EAAT1cryst, have been resolved, the transport mechanism of the transmembrane 3-4 (TM3-4) loop and its structural rearrangement during transport have remained poorly understood. In order to explore the spatial position and function of the TM3-4 loop in the transport cycle, we engineered a pair of cysteine residues between the TM3-4 loop and hairpin loop 2 (HP2) in cysteine-less EAAT2 (CL-EAAT2). We observed that the oxidative cross-linking reagent Cu(II)(1,10-phenanthroline)3 (CuPh) had a significant inhibitory effect on transport in the disubstituted A167C/G437C mutant, whereas dl-dithiothreitol (DTT) reversed the effect of cross-linking A167C/G437C on transport activity, as assayed by d-[3H]-aspartate uptake. Furthermore, we found that the effect of CuPh in this mutant was due to the formation of disulfide bonds in the transporter molecule. Moreover, dl-threo-β-benzyloxyaspartic acid (TBOA) attenuated, while l-glutamate or KCl enhanced, the CuPh-mediated inhibitory effect in the A167C/G437C mutant, suggesting that the A167C and G437C cysteines were farther apart in the outward-facing configuration and closer in the inward-facing configuration. Taken together, our findings provide evidence that the TM3-4 loop and HP2 change spatial proximity during the transport cycle.
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Affiliation(s)
- Ji Wang
- Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, China
- Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangzhou, Guangdong 510515, China
- Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, Guangdong 510515, China
| | - Shaogang Qu
- Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong 510515, China
- Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangzhou, Guangdong 510515, China
- Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, Guangdong 510515, China
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21
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Bentea E, Villers A, Moore C, Funk AJ, O’Donovan SM, Verbruggen L, Lara O, Janssen P, De Pauw L, Declerck NB, DePasquale EAK, Churchill MJ, Sato H, Hermans E, Arckens L, Meshul CK, Ris L, McCullumsmith RE, Massie A. Corticostriatal dysfunction and social interaction deficits in mice lacking the cystine/glutamate antiporter. Mol Psychiatry 2021; 26:4754-4769. [PMID: 32366950 PMCID: PMC7609546 DOI: 10.1038/s41380-020-0751-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 04/07/2020] [Accepted: 04/21/2020] [Indexed: 12/11/2022]
Abstract
The astrocytic cystine/glutamate antiporter system xc- represents an important source of extracellular glutamate in the central nervous system, with potential impact on excitatory neurotransmission. Yet, its function and importance in brain physiology remain incompletely understood. Employing slice electrophysiology and mice with a genetic deletion of the specific subunit of system xc-, xCT (xCT-/- mice), we uncovered decreased neurotransmission at corticostriatal synapses. This effect was partly mitigated by replenishing extracellular glutamate levels, indicating a defect linked with decreased extracellular glutamate availability. We observed no changes in the morphology of striatal medium spiny neurons, the density of dendritic spines, or the density or ultrastructure of corticostriatal synapses, indicating that the observed functional defects are not due to morphological or structural abnormalities. By combining electron microscopy with glutamate immunogold labeling, we identified decreased intracellular glutamate density in presynaptic terminals, presynaptic mitochondria, and in dendritic spines of xCT-/- mice. A proteomic and kinomic screen of the striatum of xCT-/- mice revealed decreased expression of presynaptic proteins and abnormal kinase network signaling, that may contribute to the observed changes in postsynaptic responses. Finally, these corticostriatal deregulations resulted in a behavioral phenotype suggestive of autism spectrum disorder in the xCT-/- mice; in tests sensitive to corticostriatal functioning we recorded increased repetitive digging behavior and decreased sociability. To conclude, our findings show that system xc- plays a previously unrecognized role in regulating corticostriatal neurotransmission and influences social preference and repetitive behavior.
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Affiliation(s)
- Eduard Bentea
- grid.8767.e0000 0001 2290 8069Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Agnès Villers
- grid.8364.90000 0001 2184 581XDepartment of Neurosciences, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Cynthia Moore
- grid.410404.50000 0001 0165 2383Research Services, Neurocytology Laboratory, Veterans Affairs Medical Center, Portland, OR USA
| | - Adam J. Funk
- grid.267337.40000 0001 2184 944XDepartment of Neurosciences, University of Toledo College of Medicine, Toledo, OH USA
| | - Sinead M. O’Donovan
- grid.267337.40000 0001 2184 944XDepartment of Neurosciences, University of Toledo College of Medicine, Toledo, OH USA
| | - Lise Verbruggen
- grid.8767.e0000 0001 2290 8069Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Olaya Lara
- grid.8767.e0000 0001 2290 8069Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Pauline Janssen
- grid.8767.e0000 0001 2290 8069Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Laura De Pauw
- grid.8767.e0000 0001 2290 8069Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Noemi B. Declerck
- grid.8767.e0000 0001 2290 8069Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - Erica A. K. DePasquale
- grid.239573.90000 0000 9025 8099Division of Biomedical Informatics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH USA ,grid.24827.3b0000 0001 2179 9593Department of Biomedical Informatics, University of Cincinnati, Cincinnati, OH USA
| | - Madeline J. Churchill
- grid.410404.50000 0001 0165 2383Research Services, Neurocytology Laboratory, Veterans Affairs Medical Center, Portland, OR USA
| | - Hideyo Sato
- grid.260975.f0000 0001 0671 5144Department of Medical Technology, Faculty of Medicine, Laboratory of Biochemistry and Molecular Biology, Niigata University, Niigata, Japan
| | - Emmanuel Hermans
- grid.7942.80000 0001 2294 713XInstitute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium
| | - Lutgarde Arckens
- grid.5596.f0000 0001 0668 7884Laboratory of Neuroplasticity and Neuroproteomics, and Leuven Brain Institute (LBI), KU Leuven—University of Leuven, Leuven, Belgium
| | - Charles K. Meshul
- grid.410404.50000 0001 0165 2383Research Services, Neurocytology Laboratory, Veterans Affairs Medical Center, Portland, OR USA ,grid.5288.70000 0000 9758 5690Department of Behavioral Neuroscience, Oregon Health and Science University, Portland, OR USA
| | - Laurence Ris
- grid.8364.90000 0001 2184 581XDepartment of Neurosciences, Research Institute for Biosciences, University of Mons, Mons, Belgium
| | - Robert E. McCullumsmith
- grid.267337.40000 0001 2184 944XDepartment of Neurosciences, University of Toledo College of Medicine, Toledo, OH USA
| | - Ann Massie
- Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences, Vrije Universiteit Brussel (VUB), Brussels, Belgium.
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22
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Zhou Y, Eid T, Hassel B, Danbolt NC. Novel aspects of glutamine synthetase in ammonia homeostasis. Neurochem Int 2020; 140:104809. [DOI: 10.1016/j.neuint.2020.104809] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2020] [Revised: 07/08/2020] [Accepted: 07/09/2020] [Indexed: 02/07/2023]
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23
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Hu QX, Klatt GM, Gudmundsrud R, Ottestad-Hansen S, Verbruggen L, Massie A, Danbolt NC, Zhou Y. Semi-quantitative distribution of excitatory amino acid (glutamate) transporters 1–3 (EAAT1-3) and the cystine-glutamate exchanger (xCT) in the adult murine spinal cord. Neurochem Int 2020; 140:104811. [DOI: 10.1016/j.neuint.2020.104811] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 06/21/2020] [Accepted: 07/09/2020] [Indexed: 01/01/2023]
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24
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Castañeda-Cabral JL, López-Ortega JG, Fajardo-Fregoso BF, Beas-Zárate C, Ureña-Guerrero ME. Glutamate induced neonatal excitotoxicity modifies the expression level of EAAT1 (GLAST) and EAAT2 (GLT-1) proteins in various brain regions of the adult rat. Neurosci Lett 2020; 735:135237. [PMID: 32645399 DOI: 10.1016/j.neulet.2020.135237] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Revised: 07/03/2020] [Accepted: 07/04/2020] [Indexed: 02/08/2023]
Abstract
Glutamate-mediated excitatory synaptic signalling is primarily controlled by excitatory amino acid transporters (EAATs), such as EAAT1 and EAAT2, which are located mostly on astrocytes and, together, uptake more than 95 % of extracellular glutamate. Alterations in the functional expression levels of EAATs can lead to excessive extracellular glutamate accumulation, potentially triggering excitotoxicity and seizures, among other neurological disorders. Excitotoxicity induced in early developmental stages can lead to lasting changes in several neurotransmission systems, including the glutamatergic system, which could make the brain more susceptible to a second insult. In this study, the expression levels of EAAT1 (GLAST) and EAAT2 (GLT-1) proteins were assessed in the cerebral motor cortex (CMC), striatum, hippocampus and entorhinal cortex (EC) of male adult rats following the neonatal excitotoxic process triggered by monosodium glutamate (MSG)-treatment (4 g/kg of body weight at postnatal days 1,3,5 and 7, subcutaneously). Western blot analysis showed that neonatal MSG-treatment decreased EAAT1 expression levels in the CMC, striatum and hippocampus, while EAAT2 levels were increased in the striatum and EC and decreased in the CMC. Immunofluorescence staining confirmed the changes in EAAT1 and EAAT2 expression induced by neonatal MSG-treatment, which were accompanied by an increase in the glial fibrillary acidic protein (GFAP) immunofluorescence signalthat was particularly significant in the hippocampus. Our results show that a neonatal excitotoxic processes can induce lasting changes in the expression levels of EAAT1 and EAAT2 proteins and suggest that although astrogliosis occurs, glutamate uptake could be deficient, particularly in the CMC and hippocampus.
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Affiliation(s)
- José Luis Castañeda-Cabral
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias (CUCBA), Universidad de Guadalajara, Zapopan, Jalisco, Mexico
| | - José Guadalupe López-Ortega
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias (CUCBA), Universidad de Guadalajara, Zapopan, Jalisco, Mexico
| | - Blanca Fabiola Fajardo-Fregoso
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias (CUCBA), Universidad de Guadalajara, Zapopan, Jalisco, Mexico
| | - Carlos Beas-Zárate
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias (CUCBA), Universidad de Guadalajara, Zapopan, Jalisco, Mexico
| | - Mónica E Ureña-Guerrero
- Departamento de Biología Celular y Molecular, Centro Universitario de Ciencias Biológicas y Agropecuarias (CUCBA), Universidad de Guadalajara, Zapopan, Jalisco, Mexico.
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25
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Arenas YM, Cabrera-Pastor A, Juciute N, Mora-Navarro E, Felipo V. Blocking glycine receptors reduces neuroinflammation and restores neurotransmission in cerebellum through ADAM17-TNFR1-NF-κβ pathway. J Neuroinflammation 2020; 17:269. [PMID: 32917219 PMCID: PMC7488331 DOI: 10.1186/s12974-020-01941-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 08/24/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Chronic hyperammonemia induces neuroinflammation in cerebellum, with glial activation and enhanced activation of the TNFR1-NF-kB-glutaminase-glutamate-GABA pathway. Hyperammonemia also increases glycinergic neurotransmission. These alterations contribute to cognitive and motor impairment. Activation of glycine receptors is reduced by extracellular cGMP, which levels are reduced in cerebellum of hyperammonemic rats in vivo. We hypothesized that enhanced glycinergic neurotransmission in hyperammonemic rats (1) contributes to induce neuroinflammation and glutamatergic and GABAergic neurotransmission alterations; (2) is a consequence of the reduced extracellular cGMP levels. The aims were to assess, in cerebellum of hyperammonemic rats, (a) whether blocking glycine receptors with the antagonist strychnine reduces neuroinflammation; (b) the cellular localization of glycine receptor; (c) the effects of blocking glycine receptors on the TNFR1-NF-kB-glutaminase-glutamate-GABA pathway and microglia activation; (d) whether adding extracellular cGMP reproduces the effects of strychnine. METHODS We analyzed in freshly isolated cerebellar slices from control or hyperammonemic rats the effects of strychnine on activation of microglia and astrocytes, the content of TNFa and IL1b, the surface expression of ADAM17, TNFR1 and transporters, the phosphorylation levels of ERK, p38 and ADAM17. The cellular localization of glycine receptor was assessed by immunofluorescence. We analyzed the content of TNFa, IL1b, HMGB1, glutaminase, and the level of TNF-a mRNA and NF-κB in Purkinje neurons. Extracellular concentrations of glutamate and GABA were performed by in vivo microdialysis in cerebellum. We tested whether extracellular cGMP reproduces the effects of strychnine in ex vivo cerebellar slices. RESULTS Glycine receptors are expressed mainly in Purkinje cells. In hyperammonemic rats, enhanced glycinergic neurotransmission leads to reduced membrane expression of ADAM17, resulting in increased surface expression and activation of TNFR1 and of the associated NF-kB pathway. This increases the expression in Purkinje neurons of TNFa, IL-1b, HMGB1, and glutaminase. Increased glutaminase activity leads to increased extracellular glutamate, which increases extracellular GABA. Increased extracellular glutamate and HMGB1 potentiate microglial activation. Blocking glycine receptors with strychnine or extracellular cGMP completely prevents the above pathway in hyperammonemic rats. CONCLUSIONS Glycinergic neurotransmission modulates neuroinflammation. Enhanced glycinergic neurotransmission in hyperammonemia would be due to reduced extracellular cGMP. These results shed some light on possible new therapeutic target pathways for pathologies associated to neuroinflammation.
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Affiliation(s)
- Yaiza M Arenas
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain
| | - Andrea Cabrera-Pastor
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain.
- Laboratory of Neurological Impairment, Health Research Institute INCLIVA, 46010, Valencia, Spain.
| | - Nora Juciute
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain
| | - Eloy Mora-Navarro
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain
| | - Vicente Felipo
- Laboratory of Neurobiology, Príncipe Felipe Research Center Valencia, C/Eduardo Primo Yúfera 3, 46012, Valencia, Spain
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Transport rate of EAAT2 is regulated by amino acid located at the interface between the scaffolding and substrate transport domains. Neurochem Int 2020; 139:104792. [PMID: 32668264 DOI: 10.1016/j.neuint.2020.104792] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 05/19/2020] [Accepted: 06/21/2020] [Indexed: 01/24/2023]
Abstract
Excitatory Amino Acid Transporters (EAATs) are plasma membrane proteins responsible for maintenance of low extracellular concentrations of glutamate in the CNS. Dysfunction in their activity is implicated in various neurological disorders. Glutamate transport by EAATs occurs through the movement of the central transport domain relative to the scaffold domain in the EAAT membrane protein. Previous studies suggested that residues located within the interface of these two domains in EAAT2, the main subtype of glutamate transporter in the brain, are involved in regulating transport rates. We used mutagenesis, structure-function relationship, surface protein expression and electrophysiology studies, in transfected COS-7 cells and oocytes, to examine residue glycine at position 298, which is located within this interface. Mutation G298A results in increased transport rate without changes in surface expression, suggesting a more hydrophobic and larger alanine results in facilitated transport movement. The increased transport rate does not involve changes in sodium affinity. Electrophysiological currents show that G298A increase both transport and anion currents, suggesting faster transitions through the transport cycle. This work identifies a region critically involved in setting the glutamate transport rate.
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27
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Sandhu MRS, Dhaher R, Gruenbaum SE, Raaisa R, Spencer DD, Pavlova MK, Zaveri HP, Eid T. Circadian-Like Rhythmicity of Extracellular Brain Glutamate in Epilepsy. Front Neurol 2020; 11:398. [PMID: 32499751 PMCID: PMC7242976 DOI: 10.3389/fneur.2020.00398] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 04/17/2020] [Indexed: 12/12/2022] Open
Abstract
Seizures often exhibit striking circadian-like (~24-h) rhythms. While chronotherapy has shown promise in treating epilepsy, it is not widely used, in part because the patterns of seizure rhythmicity vary considerably among patients and types of epilepsy. A better understanding of the mechanisms underlying rhythmicity in epilepsy could be expected to result in more effective approaches which can be tailored to each individual patient. The excitatory neurotransmitter glutamate is an essential modulator of circadian rhythms, and changes in the extracellular levels of glutamate likely affect the threshold to seizures. We used a reverse translational rodent model of mesial temporal lobe epilepsy (MTLE) combined with long-term intracerebral microdialysis to monitor the hourly concentrations of glutamate in the seizure onset area (epileptogenic hippocampus) over several days. We observed significant 24-h oscillations of extracellular glutamate in the epileptogenic hippocampus (n = 4, JTK_CYCLE test, p < 0.05), but not in the hippocampus of control animals (n = 4). To our knowledge, circadian glutamate oscillations have not been observed in a seizure onset region, and we speculate that the oscillations contribute to the rhythmicity of seizures in MTLE.
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Affiliation(s)
- Mani Ratnesh S Sandhu
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, United States
| | - Roni Dhaher
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, United States
| | - Shaun E Gruenbaum
- Department of Anesthesia and Perioperative Medicine, Mayo Clinic, FL, United States
| | - Raaisa Raaisa
- Department of Internal Medicine, Yale School of Medicine, New Haven, CT, United States
| | - Dennis D Spencer
- Department of Neurosurgery, Yale School of Medicine, New Haven, CT, United States
| | - Milena K Pavlova
- Department of Neurology, Brigham and Women's Hospital, Harvard Medical School, Cambridge, MA, United States
| | - Hitten P Zaveri
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
| | - Tore Eid
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, United States
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28
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Conditional Knockout of GLT-1 in Neurons Leads to Alterations in Aspartate Homeostasis and Synaptic Mitochondrial Metabolism in Striatum and Hippocampus. Neurochem Res 2020; 45:1420-1437. [PMID: 32144526 DOI: 10.1007/s11064-020-03000-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Revised: 02/06/2020] [Accepted: 02/25/2020] [Indexed: 02/07/2023]
Abstract
Expression of the glutamate transporter GLT-1 in neurons has been shown to be important for synaptic mitochondrial function in the cerebral cortex. Here we determined whether neuronal GLT-1 plays a similar role in the hippocampus and striatum, using conditional GLT-1 knockout mice in which GLT-1 was inactivated in neurons by expression of synapsin-Cre (synGLT-1 KO). Ex vivo 13C-labelling using [1,2-13C]acetate, representing astrocytic metabolism, yielded increased [4,5-13C]glutamate levels, suggesting increased astrocyte-neuron glutamine transfer, in the striatum but not in the hippocampus of the synGLT-1 KO. Moreover, aspartate concentrations were reduced - 38% compared to controls in the hippocampus and the striatum of the synGLT-1 KO. Mitochondria isolated from the hippocampus of synGLT-1 KO mice exhibited a lower oxygen consumption rate in the presence of oligomycin A, indicative of a decreased proton leak across the mitochondrial membrane, whereas the ATP production rate was unchanged. Electron microscopy revealed reduced mitochondrial inter-cristae distance within excitatory synaptic terminals in the hippocampus and striatum of the synGLT-1 KO. Finally, dilution of 13C-labelling originating from [U-13C]glucose, caused by metabolism of unlabelled glutamate, was reduced in hippocampal synGLT-1 KO synaptosomes, suggesting that neuronal GLT-1 provides glutamate for synaptic tricarboxylic acid cycle metabolism. Collectively, these data demonstrate an important role of neuronal expression of GLT-1 in synaptic mitochondrial metabolism in the forebrain.
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29
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Chauhan MZ, Arcuri J, Park KK, Zafar MK, Fatmi R, Hackam AS, Yin Y, Benowitz L, Goldberg JL, Samarah M, Bhattacharya SK. Multi-Omic Analyses of Growth Cones at Different Developmental Stages Provides Insight into Pathways in Adult Neuroregeneration. iScience 2020; 23:100836. [PMID: 32058951 PMCID: PMC6997871 DOI: 10.1016/j.isci.2020.100836] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 01/05/2020] [Accepted: 01/09/2020] [Indexed: 12/11/2022] Open
Abstract
Growth cones (GCs) are structures associated with growing neurons. GC membrane expansion, which necessitates protein-lipid interactions, is critical to axonal elongation in development and in adult neuritogenesis. We present a multi-omic analysis that integrates proteomics and lipidomics data for the identification of GC pathways, cell phenotypes, and lipid-protein interactions, with an analytic platform to facilitate the visualization of these data. We combine lipidomic data from GC and adult axonal regeneration following optic nerve crush. Our results reveal significant molecular variability in GCs across developmental ages that aligns with the upregulation and downregulation of lipid metabolic processes and correlates with distinct changes in the lipid composition of GC plasmalemma. We find that these processes also define the transition into a growth-permissive state in the adult central nervous system. The insight derived from these analyses will aid in promoting adult regeneration and functional innervation in devastating neurodegenerative diseases. Simultaneous proteomics and lipidomics analyses of developmental growth cones Combined multi-omics analyses of regenerating optic nerves and growth cones Integrating protein-protein with protein-lipid interactions in growth cones
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Affiliation(s)
- Muhammad Zain Chauhan
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Integrative Metabolomics Research Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Jennifer Arcuri
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Integrative Metabolomics Research Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Biomedical Sciences & Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Kevin K Park
- Miami Integrative Metabolomics Research Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Biomedical Sciences & Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Maroof Khan Zafar
- Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Rabeet Fatmi
- Department of Computer Science, Florida Polytechnic University, Lakeland, FL 33805, USA
| | - Abigail S Hackam
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Integrative Metabolomics Research Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Biomedical Sciences & Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA
| | - Yuqin Yin
- Department of Neurosurgery, Harvard Medical School, Boston, MA 02115, USA; Department of Neurosurgery and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Larry Benowitz
- Department of Ophthalmology, Harvard Medical School, Boston, MA 02115, USA; Department of Neurosurgery and F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Jeffrey L Goldberg
- Department of Ophthalmology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mohammad Samarah
- Department of Computer Science, Florida Polytechnic University, Lakeland, FL 33805, USA
| | - Sanjoy K Bhattacharya
- Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Miami Integrative Metabolomics Research Center, University of Miami Miller School of Medicine, Miami, FL 33136, USA; Program in Biomedical Sciences & Neuroscience Graduate Program, University of Miami Miller School of Medicine, Miami, FL 33136, USA.
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30
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Sharma A, Kazim SF, Larson CS, Ramakrishnan A, Gray JD, McEwen BS, Rosenberg PA, Shen L, Pereira AC. Divergent roles of astrocytic versus neuronal EAAT2 deficiency on cognition and overlap with aging and Alzheimer's molecular signatures. Proc Natl Acad Sci U S A 2019; 116:21800-21811. [PMID: 31591195 PMCID: PMC6815169 DOI: 10.1073/pnas.1903566116] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The excitatory amino acid transporter 2 (EAAT2) is the major glutamate transporter in the brain expressed predominantly in astrocytes and at low levels in neurons and axonal terminals. EAAT2 expression is reduced in aging and sporadic Alzheimer's disease (AD) patients' brains. The role EAAT2 plays in cognitive aging and its associated mechanisms remains largely unknown. Here, we show that conditional deletion of astrocytic and neuronal EAAT2 results in age-related cognitive deficits. Astrocytic, but not neuronal EAAT2, deletion leads to early deficits in short-term memory and in spatial reference learning and long-term memory. Neuronal EAAT2 loss results in late-onset spatial reference long-term memory deficit. Neuronal EAAT2 deletion leads to dysregulation of the kynurenine pathway, and astrocytic EAAT2 deficiency results in dysfunction of innate and adaptive immune pathways, which correlate with cognitive decline. Astrocytic EAAT2 deficiency also shows transcriptomic overlaps with human aging and AD. Overall, the present study shows that in addition to the widely recognized astrocytic EAAT2, neuronal EAAT2 plays a role in hippocampus-dependent memory. Furthermore, the gene expression profiles associated with astrocytic and neuronal EAAT2 deletion are substantially different, with the former associated with inflammation and synaptic function similar to changes observed in human AD and gene expression changes associated with inflammation similar to the aging human brain.
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Affiliation(s)
- Abhijeet Sharma
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Syed Faraz Kazim
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Chloe S Larson
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY 10065
| | - Aarthi Ramakrishnan
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Jason D Gray
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY 10065
| | - Bruce S McEwen
- Laboratory of Neuroendocrinology, The Rockefeller University, New York, NY 10065;
| | - Paul A Rosenberg
- Department of Neurology and the F. M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115
- Program in Neuroscience, Harvard Medical School, Boston, MA 02115
| | - Li Shen
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Ana C Pereira
- Department of Neurology, Icahn School of Medicine at Mount Sinai, New York, NY 10029;
- Fishberg Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY 10029
- Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029
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31
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Eid T. An Ancient Enzyme Takes a Hit in Epilepsy. Epilepsy Curr 2019; 19:400-401. [PMID: 31530017 PMCID: PMC6891189 DOI: 10.1177/1535759719875468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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32
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She Q, Fu F, Guo X, Tan W, Liao C. Genetic testing in fetuses with isolated agenesis of the corpus callosum. J Matern Fetal Neonatal Med 2019; 34:2227-2234. [PMID: 31450992 DOI: 10.1080/14767058.2019.1660769] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE The objectives of this study were to explore genetics pathogenesis of isolated agenesis of corpus callosum (ACC) and assess the utility of chromosomal microarray analysis (CMA) for genetic diagnosis of isolated ACC. METHODS We analyzed the genomes of 16 fetuses with isolated ACC using Afymetrix CytoScan HD arrays and conducted further bioinformatic analysis for one proband fetus with an abnormal copy number variation (CNV). RESULTS Of the 16 fetal samples examined, two (12.5%) had pathogenic CNVs and three (18.75%) had variants of unknown significance. Two cases, case 2 and case 9, were found to have pathogenic CNVs. Bioinformatic analyses indicated that the CNV of one fetus (case 9) contained 115 annotated coding genes, five of which (SLC6A5, BDNF, ELP4, PAX6, and SLC1A2) have been associated with neurodevelopment. Three of these genes (SLC1A2, BDNF, and PAX6) may play a key role in ACC development. GO cluster analysis of the implicated genes revealed strong representations of protein binding and metal ion binding functions. KEGG pathway analysis pointed to four pathways: longevity regulating pathway, amyotrophic lateral sclerosis, cocaine addiction, and autophagy-animal. CONCLUSIONS BDNF, SLC1A2, and PAX6 may be involved in the development of isolated ACC. CMA is a feasible technology for prenatal diagnosis of isolated ACC.
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Affiliation(s)
- Qin She
- Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Prenatal Diagnostic Center, Guangzhou Women and Children's Medical Center, Guangzhou, China.,Prenatal Diagnostic Center, The Six Affiliated Hospital, Guangzhou Medical University, Qingyuan, China
| | - Fang Fu
- Prenatal Diagnostic Center, Guangzhou Women and Children's Medical Center, Guangzhou, China
| | - Xiaoyan Guo
- Prenatal Diagnostic Center, The Six Affiliated Hospital, Guangzhou Medical University, Qingyuan, China
| | - Weihe Tan
- Prenatal Diagnostic Center, The Six Affiliated Hospital, Guangzhou Medical University, Qingyuan, China
| | - Can Liao
- Zhujiang Hospital, Southern Medical University, Guangzhou, China.,Prenatal Diagnostic Center, Guangzhou Women and Children's Medical Center, Guangzhou, China
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33
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Peterson AR, Binder DK. Post-translational Regulation of GLT-1 in Neurological Diseases and Its Potential as an Effective Therapeutic Target. Front Mol Neurosci 2019; 12:164. [PMID: 31338020 PMCID: PMC6629900 DOI: 10.3389/fnmol.2019.00164] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 06/14/2019] [Indexed: 12/12/2022] Open
Abstract
Glutamate transporter-1 (GLT-1) is a Na+-dependent transporter that plays a key role in glutamate homeostasis by removing excess glutamate in the central nervous system (CNS). GLT-1 dysregulation occurs in various neurological diseases including Huntington's disease (HD), Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and epilepsy. Downregulation or dysfunction of GLT-1 has been a common finding across these diseases but how this occurs is still under investigation. This review aims to highlight post-translational regulation of GLT-1 which leads to its downregulation including sumoylation, palmitoylation, nitrosylation, ubiquitination, and subcellular localization. Various therapeutic interventions to restore GLT-1, their proposed mechanism of action and functional effects will be examined as potential treatments to attenuate the neurological symptoms associated with loss or downregulation of GLT-1.
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Affiliation(s)
- Allison R Peterson
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
| | - Devin K Binder
- Center for Glial-Neuronal Interactions, Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, CA, United States
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Héja L, Simon Á, Szabó Z, Kardos J. Feedback adaptation of synaptic excitability via Glu:Na + symport driven astrocytic GABA and Gln release. Neuropharmacology 2019; 161:107629. [PMID: 31103619 DOI: 10.1016/j.neuropharm.2019.05.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 03/30/2019] [Accepted: 05/07/2019] [Indexed: 02/08/2023]
Abstract
Glutamatergic transmission composed of the arriving of action potential at the axon terminal, fast vesicular Glu release, postsynaptic Glu receptor activation, astrocytic Glu clearance and Glu→Gln shuttle is an abundantly investigated phenomenon. Despite its essential role, however, much less is known about the consequences of the mechanistic connotations of Glu:Na+ symport. Due to the coupled Na+ transport, Glu uptake results in significantly elevated intracellular astrocytic [Na+] that markedly alters the driving force of other Na+-coupled astrocytic transporters. The resulting GABA and Gln release by reverse transport through the respective GAT-3 and SNAT3 transporters help to re-establish the physiological Na+ homeostasis without ATP dissipation and consequently leads to enhanced tonic inhibition and replenishment of axonal glutamate pool. Here, we place this emerging astrocytic adjustment of synaptic excitability into the centre of future perspectives. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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Affiliation(s)
- László Héja
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Ágnes Simon
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Zsolt Szabó
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary
| | - Julianna Kardos
- Functional Pharmacology Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Magyar tudósok körútja 2, 1117, Budapest, Hungary.
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Deletion of Neuronal GLT-1 in Mice Reveals Its Role in Synaptic Glutamate Homeostasis and Mitochondrial Function. J Neurosci 2019; 39:4847-4863. [PMID: 30926746 DOI: 10.1523/jneurosci.0894-18.2019] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 02/07/2019] [Accepted: 03/10/2019] [Indexed: 01/19/2023] Open
Abstract
The glutamate transporter GLT-1 is highly expressed in astrocytes but also in neurons, primarily in axon terminals. We generated a conditional neuronal GLT-1 KO using synapsin 1-Cre (synGLT-1 KO) to elucidate the metabolic functions of GLT-1 expressed in neurons, here focusing on the cerebral cortex. Both synaptosomal uptake studies and electron microscopic immunocytochemistry demonstrated knockdown of GLT-1 in the cerebral cortex in the synGLT-1 KO mice. Aspartate content was significantly reduced in cerebral cortical extracts as well as synaptosomes from cerebral cortex of synGLT-1 KO compared with control littermates. 13C-Labeling of tricarboxylic acid cycle intermediates originating from metabolism of [U-13C]-glutamate was significantly reduced in synGLT-1 KO synaptosomes. The decreased aspartate content was due to diminished entry of glutamate into the tricarboxylic acid cycle. Pyruvate recycling, a pathway necessary for full glutamate oxidation, was also decreased. ATP production was significantly increased, despite unaltered oxygen consumption, in isolated mitochondria from the synGLT-1 KO. The density of mitochondria in axon terminals and perisynaptic astrocytes was increased in the synGLT-1 KO. Intramitochondrial cristae density of synGLT-1 KO mice was increased, suggesting increased mitochondrial efficiency, perhaps in compensation for reduced access to glutamate. SynGLT-1 KO synaptosomes exhibited an elevated oxygen consumption rate when stimulated with veratridine, despite a lower baseline oxygen consumption rate in the presence of glucose. GLT-1 expressed in neurons appears to be required to provide glutamate to synaptic mitochondria and is linked to neuronal energy metabolism and mitochondrial function.SIGNIFICANCE STATEMENT All synaptic transmitters need to be cleared from the extracellular space after release, and transporters are used to clear glutamate released from excitatory synapses. GLT-1 is the major glutamate transporter, and most GLT-1 is expressed in astrocytes. Only 5%-10% is expressed in neurons, primarily in axon terminals. The function of GLT-1 in axon terminals remains unknown. Here, we used a conditional KO approach to investigate the significance of the expression of GLT-1 in neurons. We found multiple abnormalities of mitochondrial function, suggesting impairment of glutamate utilization by synaptic mitochondria in the neuronal GLT-1 KO. These data suggest that GLT-1 expressed in axon terminals may be important in maintaining energy metabolism and biosynthetic activities mediated by presynaptic mitochondria.
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Wang XH, Yao DX, Luan XS, Wang Y, Liu HX, Liu B, Liu Y, Zhao L, Ji XM, Wang TL. MicroRNA expression in the hippocampal CA1 region under deep hypothermic circulatory arrest. Neural Regen Res 2019; 14:2003-2010. [PMID: 31290459 PMCID: PMC6676878 DOI: 10.4103/1673-5374.253174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Using deep hypothermic circulatory arrest, thoracic aorta diseases and complex heart diseases can be subjected to corrective procedures. However, mechanisms underlying brain protection during deep hypothermic circulatory arrest are unclear. After piglet models underwent 60 minutes of deep hypothermic circulatory arrest at 14°C, expression of microRNAs (miRNAs) was analyzed in the hippocampus by microarray. Subsequently, TargetScan 6.2, RNA22 v2.0, miRWalk 2.0, and miRanda were used to predict potential targets, and gene ontology enrichment analysis was carried out to identify functional pathways involved. Quantitative reverse transcription-polymerase chain reaction was conducted to verify miRNA changes. Deep hypothermic circulatory arrest altered the expression of 35 miRNAs. Twenty-two miRNAs were significantly downregulated and thirteen miRNAs were significantly upregulated in the hippocampus after deep hypothermic circulatory arrest. Six out of eight targets among the differentially expressed miRNAs were enriched for neuronal projection (cyclin dependent kinase, CDK16 and SLC1A2), central nervous system development (FOXO3, TYRO3, and SLC1A2), ion transmembrane transporter activity (ATP2B2 and SLC1A2), and interleukin-6 receptor binding (IL6R) – these are the key functional pathways involved in cerebral protection during deep hypothermic circulatory arrest. Quantitative reverse transcription-polymerase chain reaction confirmed the results of microarray analysis. Our experimental results illustrate a new role for transcriptional regulation in deep hypothermic circulatory arrest, and provide significant insight for the development of miRNAs to treat brain injuries. All procedures were approved by the Animal Care Committee of Xuanwu Hospital, Capital Medical University, China on March 1, 2017 (approval No. XW-INI-AD2017-0112).
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Affiliation(s)
- Xiao-Hua Wang
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Dong-Xu Yao
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Xiu-Shu Luan
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Yu Wang
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Hai-Xia Liu
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Bei Liu
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Yang Liu
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Lei Zhao
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
| | - Xun-Ming Ji
- Department of Neurosurgery; Cerebrovascular Research Center, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Tian-Long Wang
- Department of Anesthesiology, Xuanwu Hospital, Capital Medical University; Institute of Geriatrics; National Clinical Research Center for Geriatric Disorders, Beijing, China
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Zhang Y, Dong H, Duan L, Yuan G, Liang W, Li Q, Zhang X, Pan Y. SLC1A2 mediates refractory temporal lobe epilepsy with an initial precipitating injury by targeting the glutamatergic synapse pathway. IUBMB Life 2018; 71:213-222. [PMID: 30360015 DOI: 10.1002/iub.1956] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/30/2018] [Accepted: 09/08/2018] [Indexed: 12/15/2022]
Affiliation(s)
- Yinian Zhang
- Department of Neurosurgery and Laboratory of Neurosurgery; Lanzhou University Second Hospital; Lanzhou, 730030 Gansu China
- Institute of Neurology, Lanzhou University; Lanzhou, 730030 Gansu China
| | - Huateng Dong
- Department of Pediatric Neurology; Gansu Provincial Maternity and Child-care Hospital; Lanzhou, 730050 Gansu China
| | - Lei Duan
- Department of Neurosurgery and Laboratory of Neurosurgery; Lanzhou University Second Hospital; Lanzhou, 730030 Gansu China
- Institute of Neurology, Lanzhou University; Lanzhou, 730030 Gansu China
| | - Guoqiang Yuan
- Department of Neurosurgery and Laboratory of Neurosurgery; Lanzhou University Second Hospital; Lanzhou, 730030 Gansu China
- Institute of Neurology, Lanzhou University; Lanzhou, 730030 Gansu China
| | - Wentao Liang
- Department of Neurosurgery and Laboratory of Neurosurgery; Lanzhou University Second Hospital; Lanzhou, 730030 Gansu China
- Institute of Neurology, Lanzhou University; Lanzhou, 730030 Gansu China
| | - Qiao Li
- Department of Neurosurgery and Laboratory of Neurosurgery; Lanzhou University Second Hospital; Lanzhou, 730030 Gansu China
- Institute of Neurology, Lanzhou University; Lanzhou, 730030 Gansu China
| | - Xinding Zhang
- Department of Neurosurgery and Laboratory of Neurosurgery; Lanzhou University Second Hospital; Lanzhou, 730030 Gansu China
- Institute of Neurology, Lanzhou University; Lanzhou, 730030 Gansu China
| | - Yawen Pan
- Department of Neurosurgery and Laboratory of Neurosurgery; Lanzhou University Second Hospital; Lanzhou, 730030 Gansu China
- Institute of Neurology, Lanzhou University; Lanzhou, 730030 Gansu China
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Zhou Y, Dhaher R, Parent M, Hu QX, Hassel B, Yee SP, Hyder F, Gruenbaum SE, Eid T, Danbolt NC. Selective deletion of glutamine synthetase in the mouse cerebral cortex induces glial dysfunction and vascular impairment that precede epilepsy and neurodegeneration. Neurochem Int 2018; 123:22-33. [PMID: 30053506 DOI: 10.1016/j.neuint.2018.07.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Revised: 07/22/2018] [Accepted: 07/23/2018] [Indexed: 12/31/2022]
Abstract
Glutamate-ammonia ligase (glutamine synthetase; Glul) is enriched in astrocytes and serves as the primary enzyme for ammonia detoxification and glutamate inactivation in the brain. Loss of astroglial Glul is reported in hippocampi of epileptic patients, but the mechanism by which Glul deficiency might cause disease remains elusive. Here we created a novel mouse model by selectively deleting Glul in the hippocampus and neocortex. The Glul deficient mice were born without any apparent malformations and behaved unremarkably until postnatal week three. There were reductions in tissue levels of aspartate, glutamate, glutamine and GABA and in mRNA encoding glutamate receptor subunits GRIA1 and GRIN2A as well as in the glutamate transporter proteins EAAT1 and EAAT2. Adult Glul-deficient mice developed progressive neurodegeneration and spontaneous seizures which increased in frequency with age. Importantly, progressive astrogliosis occurred before neurodegeneration and was first noted in astrocytes along cerebral blood vessels. The responses to CO2-provocation were attenuated at four weeks of age and dilated microvessels were observed histologically in sclerotic areas of cKO. Thus, the abnormal glutamate metabolism observed in this model appeared to cause epilepsy by first inducing gliopathy and disrupting the neurovascular coupling.
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Affiliation(s)
- Yun Zhou
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, N-0317, Oslo, Norway.
| | - Roni Dhaher
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Maxime Parent
- Magnetic Resonance Research Center, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Qiu-Xiang Hu
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, N-0317, Oslo, Norway
| | - Bjørnar Hassel
- Department of Complex Neurology and Neurohabilitation, Oslo University Hospital, University of Oslo, N-0450, Oslo, Norway
| | - Siu-Pok Yee
- Department of Cell Biology, University of Connecticut Health, Farmington, CT, 06030, USA
| | - Fahmeed Hyder
- Magnetic Resonance Research Center, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Shaun E Gruenbaum
- Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Tore Eid
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, N-0317, Oslo, Norway; Department of Laboratory Medicine, Yale School of Medicine, New Haven, CT, 06520, USA.
| | - Niels Christian Danbolt
- Neurotransporter Group, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, N-0317, Oslo, Norway.
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Laprairie RB, Petr GT, Sun Y, Fischer KD, Denovan-Wright EM, Rosenberg PA. Huntington's disease pattern of transcriptional dysregulation in the absence of mutant huntingtin is produced by knockout of neuronal GLT-1. Neurochem Int 2018; 123:85-94. [PMID: 29709465 DOI: 10.1016/j.neuint.2018.04.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/02/2018] [Accepted: 04/24/2018] [Indexed: 12/11/2022]
Abstract
GLT-1 is the major glutamate transporter in the brain, and is expressed in astrocytes and in axon terminals in the hippocampus, cortex, and striatum. Neuronal GLT-1 accounts for only 5-10% of total brain GLT-1 protein, and its function is uncertain. In HD, synaptic dysfunction of the corticostriate synapse is well-established. Transcriptional dysregulation is a key feature of HD. We hypothesized that deletion of neuronal GLT-1, because it is expressed in axon terminals in the striatum, might produce a synaptopathy similar to that present in HD. If true, then some of the gene expression changes observed in HD might also be observed in the neuronal GLT-1 knockout. In situ hybridization using 33P labeled oligonucleotide probes was carried out to assess localization and expression of a panel of genes known to be altered in expression in HD. We found changes in the expression of cannabinoid receptors 1 and 2, preproenkaphalin, and PDE10A in the striatum of mice in which the GLT-1 gene was inactivated in neurons by expression of synapsin-Cre, compared to wild-type littermates. These changes in expression were observed at 12 weeks of age but not at 6 weeks of age. No changes in DARPP-32, PDE1B, NGFIA, or β-actin expression were observed. In addition, we found widespread alteration in expression of the dynamin 1 gene. The changes in expression in the neuronal GLT-1 knockout of genes thought to exemplify HD transcriptional dysregulation suggest an overlap in the synaptopathy caused by neuronal GLT-1 deletion and HD. These data further suggest that specific changes in expression of cannabinoid receptors, preproenkephalin, and PDE10A, considered to be the hallmark of HD transcriptional dysregulation, may be produced by an abnormality of glutamate homeostasis under the regulation of neuronal GLT-1, or a synaptic disturbance caused by that abnormality, independently of mutation in huntingtin.
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Affiliation(s)
- Robert B Laprairie
- Department of Pharmacology, Dalhousie University, Halifax, NS B3M 4R2, Canada
| | - Geraldine T Petr
- Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Yan Sun
- Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Kathryn D Fischer
- Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | | | - Paul A Rosenberg
- Department of Neurology and the F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; Program in Neuroscience, Harvard Medical School, Boston, MA 02115, USA.
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