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Heit BS, Chu A, McRay A, Richmond JE, Heckman CJ, Larson J. Interference with glutamate antiporter system x c - enables post-hypoxic long-term potentiation in hippocampus. Exp Physiol 2024; 109:1572-1592. [PMID: 39153228 PMCID: PMC11363115 DOI: 10.1113/ep092045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Accepted: 06/28/2024] [Indexed: 08/19/2024]
Abstract
Our group previously showed that genetic or pharmacological inhibition of the cystine/glutamate antiporter, system xc -, mitigates excitotoxicity after anoxia by increasing latency to anoxic depolarization, thus attenuating the ischaemic core. Hypoxia, however, which prevails in the ischaemic penumbra, is a condition where neurotransmission is altered, but excitotoxicity is not triggered. The present study employed mild hypoxia to further probe ischaemia-induced changes in neuronal responsiveness from wild-type and xCT KO (xCT-/-) mice. Synaptic transmission was monitored in hippocampal slices from both genotypes before, during and after a hypoxic episode. Although wild-type and xCT-/- slices showed equal suppression of synaptic transmission during hypoxia, mutant slices exhibited a persistent potentiation upon re-oxygenation, an effect we termed 'post-hypoxic long-term potentiation (LTP)'. Blocking synaptic suppression during hypoxia by antagonizing adenosine A1 receptors did not preclude post-hypoxic LTP. Further examination of the induction and expression mechanisms of this plasticity revealed that post-hypoxic LTP was driven by NMDA receptor activation, as well as increased calcium influx, with no change in paired-pulse facilitation. Hence, the observed phenomenon engaged similar mechanisms as classical LTP. This was a remarkable finding as theta-burst stimulation-induced LTP was equivalent between genotypes. Importantly, post-hypoxic LTP was generated in wild-type slices pretreated with system xc - inhibitor, S-4-carboxyphenylglycine, thereby confirming the antiporter's role in this phenomenon. Collectively, these data indicate that system xc - interference enables neuroplasticity in response to mild hypoxia, and, together with its regulation of cellular damage in the ischaemic core, suggest a role for the antiporter in post-ischaemic recovery of the penumbra.
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Affiliation(s)
- Bradley S. Heit
- Department of Neuroscience and Department of Biomedical EngineeringNorthwestern UniversityChicagoIllinoisUSA
- Department of PsychiatryUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | - Alex Chu
- Department of PsychiatryUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | - Alyssa McRay
- Department of Biological SciencesUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | - Janet E. Richmond
- Department of Biological SciencesUniversity of Illinois at ChicagoChicagoIllinoisUSA
| | - Charles J. Heckman
- Department of Neuroscience and Department of Biomedical EngineeringNorthwestern UniversityChicagoIllinoisUSA
| | - John Larson
- Department of PsychiatryUniversity of Illinois at ChicagoChicagoIllinoisUSA
- Department of Biological SciencesUniversity of Illinois at ChicagoChicagoIllinoisUSA
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2
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Kanaan MN, Pileggi CA, Karam CY, Kennedy LS, Fong-McMaster C, Cuperlovic-Culf M, Harper ME. Cystine/glutamate antiporter xCT controls skeletal muscle glutathione redox, bioenergetics and differentiation. Redox Biol 2024; 73:103213. [PMID: 38815331 PMCID: PMC11167394 DOI: 10.1016/j.redox.2024.103213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2024] [Revised: 05/22/2024] [Accepted: 05/24/2024] [Indexed: 06/01/2024] Open
Abstract
Cysteine, the rate-controlling amino acid in cellular glutathione synthesis is imported as cystine, by the cystine/glutamate antiporter, xCT, and subsequently reduced to cysteine. As glutathione redox is important in muscle regeneration in aging, we hypothesized that xCT exerts upstream control over skeletal muscle glutathione redox, metabolism and regeneration. Bioinformatic analyses of publicly available datasets revealed that expression levels of xCT and GSH-related genes are inversely correlated with myogenic differentiation genes. Muscle satellite cells (MuSCs) isolated from Slc7a11sut/sut mice, which harbour a mutation in the Slc7a11 gene encoding xCT, required media supplementation with 2-mercaptoethanol to support cell proliferation but not myotube differentiation, despite persistently lower GSH. Slc7a11sut/sut primary myotubes were larger compared to WT myotubes, and also exhibited higher glucose uptake and cellular oxidative capacities. Immunostaining of myogenic markers (Pax7, MyoD, and myogenin) in cardiotoxin-damaged tibialis anterior muscle fibres revealed greater MuSC activation and commitment to differentiation in Slc7a11sut/sut muscle compared to WT mice, culminating in larger myofiber cross-sectional areas at 21 days post-injury. Slc7a11sut/sut mice subjected to a 5-week exercise training protocol demonstrated enhanced insulin tolerance compared to WT mice, but blunted muscle mitochondrial biogenesis and respiration in response to exercise training. Our results demonstrate that the absence of xCT inhibits cell proliferation but promotes myotube differentiation by regulating cellular metabolism and glutathione redox. Altogether, these results support the notion that myogenesis is a redox-regulated process and may help inform novel therapeutic approaches for muscle wasting and dysfunction in aging and disease.
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Affiliation(s)
- Michel N Kanaan
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, ON, K1H 8M5, Canada; Dr. Eric Poulin Centre for Neuromuscular Disease (CNMD), University of Ottawa, ON, K1H 8M5, Canada
| | - Chantal A Pileggi
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, ON, K1H 8M5, Canada
| | - Charbel Y Karam
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, ON, K1H 8M5, Canada
| | - Luke S Kennedy
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, ON, K1H 8M5, Canada
| | - Claire Fong-McMaster
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, ON, K1H 8M5, Canada
| | - Miroslava Cuperlovic-Culf
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, ON, K1H 8M5, Canada; National Research Council of Canada, Digital Technologies Research Centre, 1200 Montreal Road, Ottawa, ON, K1A 0R6, Canada
| | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, 451 Smyth Road, Ottawa, ON, K1H 8M5, Canada; Ottawa Institute of Systems Biology, University of Ottawa, ON, K1H 8M5, Canada.
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3
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Lara O, Janssen P, Mambretti M, De Pauw L, Ates G, Mackens L, De Munck J, Walckiers J, Pan Z, Beckers P, Espinet E, Sato H, De Ridder M, Marks DL, Barbé K, Aerts JL, Hermans E, Rooman I, Massie A. Compartmentalized role of xCT in supporting pancreatic tumor growth, inflammation and mood disturbance in mice. Brain Behav Immun 2024; 118:275-286. [PMID: 38447884 DOI: 10.1016/j.bbi.2024.03.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Revised: 02/05/2024] [Accepted: 03/02/2024] [Indexed: 03/08/2024] Open
Abstract
xCT (Slc7a11), the specific subunit of the cystine/glutamate antiporter system xc-, is present in the brain and on immune cells, where it is known to modulate behavior and inflammatory responses. In a variety of cancers -including pancreatic ductal adenocarcinoma (PDAC)-, xCT is upregulated by tumor cells to support their growth and spread. Therefore, we studied the impact of xCT deletion in pancreatic tumor cells (Panc02) and/or the host (xCT-/- mice) on tumor burden, inflammation, cachexia and mood disturbances. Deletion of xCT in the tumor strongly reduced tumor growth. Targeting xCT in the host and not the tumor resulted only in a partial reduction of tumor burden, while it did attenuate tumor-related systemic inflammation and prevented an increase in immunosuppressive regulatory T cells. The latter effect could be replicated by specific xCT deletion in immune cells. xCT deletion in the host or the tumor differentially modulated neuroinflammation. When mice were grafted with xCT-deleted tumor cells, hypothalamic inflammation was reduced and, accordingly, food intake improved. Tumor bearing xCT-/- mice showed a trend of reduced hippocampal neuroinflammation with less anxiety- and depressive-like behavior. Taken together, targeting xCT may have beneficial effects on pancreatic cancer-related comorbidities, beyond reducing tumor burden. The search for novel and specific xCT inhibitors is warranted as they may represent a holistic therapy in pancreatic cancer.
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Affiliation(s)
- Olaya Lara
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium; Laboratory for Medical and Molecular Oncology, Translational Oncology Research Center (TORC), VUB, Brussels 1090, Belgium
| | - Pauline Janssen
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium; Laboratory for Medical and Molecular Oncology, Translational Oncology Research Center (TORC), VUB, Brussels 1090, Belgium
| | - Marco Mambretti
- Laboratory for Medical and Molecular Oncology, Translational Oncology Research Center (TORC), VUB, Brussels 1090, Belgium
| | - Laura De Pauw
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium
| | - Gamze Ates
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium
| | - Liselotte Mackens
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium
| | - Jolien De Munck
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium
| | - Jarne Walckiers
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium
| | - Zhaolong Pan
- Laboratory for Medical and Molecular Oncology, Translational Oncology Research Center (TORC), VUB, Brussels 1090, Belgium
| | - Pauline Beckers
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Elisa Espinet
- Pancreatic Cancer Lab, Department of Pathology and Experimental Therapy, School of Medicine, University of Barcelona, L'Hospitalet de Llobregat, Barcelona 08907, Spain; Molecular Mechanisms and Experimental Therapy in Oncology Program, Institut d'Investigació Biomèdica de Bellvitge, L'Hospitalet de Llobregat, Barcelona 08907, Spain
| | - Hideyo Sato
- Department of Medical Technology, Niigata University, Niigata 950-3198, Japan
| | - Mark De Ridder
- Department of Radiotherapy, UZ Brussels, VUB, Brussels 1090, Belgium
| | - Daniel L Marks
- Papé Family Pediatric Research Institute, Oregon Health and Science University, Portland, OR 97239, USA
| | - Kurt Barbé
- The Biostatistics and Medical Informatics Department, VUB, Brussels 1090, Belgium
| | - Joeri L Aerts
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium
| | - Emmanuel Hermans
- Institute of Neuroscience, Université catholique de Louvain, Brussels 1200, Belgium
| | - Ilse Rooman
- Laboratory for Medical and Molecular Oncology, Translational Oncology Research Center (TORC), VUB, Brussels 1090, Belgium.
| | - Ann Massie
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels 1090, Belgium.
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Achiro JM, Tao Y, Gao F, Lin CH, Watanabe M, Neumann S, Coppola G, Black DL, Martin KC. Aging differentially alters the transcriptome and landscape of chromatin accessibility in the male and female mouse hippocampus. Front Mol Neurosci 2024; 17:1334862. [PMID: 38318533 PMCID: PMC10839115 DOI: 10.3389/fnmol.2024.1334862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 01/02/2024] [Indexed: 02/07/2024] Open
Abstract
Aging-related memory impairment and pathological memory disorders such as Alzheimer's disease differ between males and females, and yet little is known about how aging-related changes in the transcriptome and chromatin environment differ between sexes in the hippocampus. To investigate this question, we compared the chromatin accessibility landscape and gene expression/alternative splicing pattern of young adult and aged mouse hippocampus in both males and females using ATAC-seq and RNA-seq. We detected significant aging-dependent changes in the expression of genes involved in immune response and synaptic function and aging-dependent changes in the alternative splicing of myelin sheath genes. We found significant sex-bias in the expression and alternative splicing of hundreds of genes, including aging-dependent female-biased expression of myelin sheath genes and aging-dependent male-biased expression of genes involved in synaptic function. Aging was associated with increased chromatin accessibility in both male and female hippocampus, especially in repetitive elements, and with an increase in LINE-1 transcription. We detected significant sex-bias in chromatin accessibility in both autosomes and the X chromosome, with male-biased accessibility enriched at promoters and CpG-rich regions. Sex differences in gene expression and chromatin accessibility were amplified with aging, findings that may shed light on sex differences in aging-related and pathological memory loss.
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Affiliation(s)
- Jennifer M. Achiro
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Yang Tao
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Fuying Gao
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Chia-Ho Lin
- Department of Microbiology, Immunology and Molecular Genetics, UCLA, Los Angeles, CA, United States
| | - Marika Watanabe
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Sylvia Neumann
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Giovanni Coppola
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
| | - Douglas L. Black
- Department of Microbiology, Immunology and Molecular Genetics, UCLA, Los Angeles, CA, United States
| | - Kelsey C. Martin
- Department of Biological Chemistry, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
- Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, UCLA, Los Angeles, CA, United States
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5
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Janssen P, De Pauw L, Mambretti M, Lara O, Walckiers J, Mackens L, Rooman I, Guillaume B, De Ridder M, Ates G, Massie A. Characterization of the long-term effects of lethal total body irradiation followed by bone marrow transplantation on the brain of C57BL/6 mice. Int J Radiat Biol 2023; 100:385-398. [PMID: 37976378 DOI: 10.1080/09553002.2023.2283092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 11/01/2023] [Indexed: 11/19/2023]
Abstract
PURPOSE Total body irradiation (TBI) followed by bone marrow transplantation (BMT) is used in pre-clinical research to generate mouse chimeras that allow to study the function of a protein specifically on immune cells. Adverse consequences of irradiation on the juvenile body and brain are well described and include general fatigue, neuroinflammation, neurodegeneration and cognitive impairment. Yet, the long-term consequences of TBI/BMT performed on healthy adult mice have been poorly investigated. MATERIAL AND METHODS We developed a robust protocol to achieve near complete bone marrow replacement in mice using 2x550cGy TBI and evaluated the impact of the procedure on their general health, mood disturbances, memory, brain atrophy, neurogenesis, neuroinflammation and blood-brain barrier (BBB) permeability 2 and/or 16 months post-BMT. RESULTS We found a persistent decrease in weight along with long-term impact on locomotion after TBI and BMT. Although the TBI/BMT procedure did not lead to anxiety- or depressive-like behavior 2- or 16-months post-BMT, long-term spatial memory of the irradiated mice was impaired. We also observed radiation-induced impaired neurogenesis and cortical microglia activation 2 months post-BMT. Moreover, higher levels of hippocampal IgG in aged BMT mice suggest an enhanced age-related increase in BBB permeability that could potentially contribute to the observed memory deficit. CONCLUSIONS Overall health of the mice did not seem to be majorly impacted by TBI followed by BMT during adulthood. Yet, TBI-induced alterations in the brain and behavior could lead to erroneous conclusions on the function of a protein on immune cells when comparing mouse chimeras with different genetic backgrounds that might display altered susceptibility to radiation-induced damage. Ultimately, the BMT model we here present could also be used to study the related long-term consequences of TBI and BMT seen in patients.
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Affiliation(s)
- P Janssen
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
- Laboratory of Medical and Molecular Oncology, Oncology Research Centre (ORC), VUB, Brussels, Belgium
| | - L De Pauw
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - M Mambretti
- Laboratory of Medical and Molecular Oncology, Oncology Research Centre (ORC), VUB, Brussels, Belgium
| | - O Lara
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
- Laboratory of Medical and Molecular Oncology, Oncology Research Centre (ORC), VUB, Brussels, Belgium
| | - J Walckiers
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - L Mackens
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - I Rooman
- Laboratory of Medical and Molecular Oncology, Oncology Research Centre (ORC), VUB, Brussels, Belgium
| | - B Guillaume
- Ludwig Institute for Cancer Research, Brussels, Belgium
- de Duve Institute, UCLouvain, Brussels, Belgium
- Centre hospitalier de Jolimont, Service de Biochimie Médicale, La Louvière, Belgium
| | - M De Ridder
- Department of Radiotherapy, UZ Brussel, VUB, Brussels, Belgium
| | - G Ates
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
| | - A Massie
- Laboratory of Neuro-Aging & Viro-Immunotherapy, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Brussels, Belgium
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Frare C, Pitt SK, Hewett SJ. Sex- and age-dependent contribution of System x c- to cognitive, sensory, and social behaviors revealed by comprehensive behavioral analyses of System x c- null mice. Front Behav Neurosci 2023; 17:1238349. [PMID: 37649973 PMCID: PMC10462982 DOI: 10.3389/fnbeh.2023.1238349] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Accepted: 07/31/2023] [Indexed: 09/01/2023] Open
Abstract
Background System xc- (Sxc-) is an important heteromeric amino acid cystine/glutamate exchanger that plays a pivotal role in the CNS by importing cystine into cells while exporting glutamate. Although certain behaviors have been identified as altered in Sxc- null mutant mice, our understanding of the comprehensive impact of Sxc- on behavior remains incomplete. Methods To address this gap, we compared motor, sensory and social behaviors of male and female mice in mice null for Sxc- (SLC7A11sut/sut) with wildtype littermates (SLC7A11+/+) in a comprehensive and systematic manner to determine effects of genotype, sex, age, and their potential interactions. Results Motor performance was not affected by loss of Sxc- in both males and females, although it was impacted negatively by age. Motor learning was specifically disrupted in female mice lacking Sxc- at both 2 and 6 months of age. Further, female SLC7A11sut/sut mice at both ages exhibited impaired sociability, but normal spatial and recognition memory, as well as sensorimotor gating. Finally, pronounced open-space anxiety was displayed by female SLC7A11sut/sut when they were young. In contrast, young SLC7A11sut/sut male mice demonstrated normal sociability, delayed spatial learning, increased open-space anxiety and heightened sensitivity to noise. As they aged, anxiety and noise sensitivity abated but hyperactivity emerged. Discussion We find that the behavioral phenotypes of female SLC7A11sut/sut are similar to those observed in mouse models of autism spectrum disorder, while behaviors of male SLC7A11sut/sut resemble those seen in mouse models of attention deficit hyperactivity disorder. These results underscore the need for further investigation of SLC7A11 in neurodevelopment. By expanding our understanding of the potential involvement of Sxc-, we may gain additional insights into the mechanisms underlying complex neurodevelopmental conditions.
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Affiliation(s)
| | | | - Sandra J. Hewett
- Department of Biology, Program in Neuroscience, Syracuse University, Syracuse, NY, United States
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Heit BS, Chu A, Sane A, Featherstone DE, Park TJ, Larson J. Tonic extracellular glutamate and ischaemia: glutamate antiporter system x c - regulates anoxic depolarization in hippocampus. J Physiol 2023; 601:607-629. [PMID: 36321247 PMCID: PMC10107724 DOI: 10.1113/jp283880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 10/18/2022] [Indexed: 12/05/2022] Open
Abstract
In stroke, the sudden deprivation of oxygen to neurons triggers a profuse release of glutamate that induces anoxic depolarization (AD) and leads to rapid cell death. Importantly, the latency of the glutamate-driven AD event largely dictates subsequent tissue damage. Although the contribution of synaptic glutamate during ischaemia is well-studied, the role of tonic (ambient) glutamate has received far less scrutiny. The majority of tonic, non-synaptic glutamate in the brain is governed by the cystine/glutamate antiporter, system xc - . Employing hippocampal slice electrophysiology, we showed that transgenic mice lacking a functional system xc - display longer latencies to AD and altered depolarizing waves compared to wild-type mice after total oxygen deprivation. Experiments which pharmacologically inhibited system xc - , as well as those manipulating tonic glutamate levels and those antagonizing glutamate receptors, revealed that the antiporter's putative effect on ambient glutamate precipitates the ischaemic cascade. As such, the current study yields novel insight into the pathogenesis of acute stroke and may direct future therapeutic interventions. KEY POINTS: Ischaemic stroke remains the leading cause of adult disability in the world, but efforts to reduce stroke severity have been plagued by failed translational attempts to mitigate glutamate excitotoxicity. Elucidating the ischaemic cascade, which within minutes leads to irreversible tissue damage induced by anoxic depolarization, must be a principal focus. Data presented here show that tonic, extrasynaptic glutamate supplied by system xc - synergizes with ischaemia-induced synaptic glutamate release to propagate AD and exacerbate depolarizing waves. Exploiting the role of system xc - and its obligate release of ambient glutamate could, therefore, be a novel therapeutic direction to attenuate the deleterious effects of acute stroke.
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Affiliation(s)
- Bradley S Heit
- Graduate Program in Neuroscience, University of Illinois at Chicago, Chicago, IL, USA.,Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA
| | - Alex Chu
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA
| | - Abhay Sane
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA
| | - David E Featherstone
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - Thomas J Park
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
| | - John Larson
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, USA.,Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, USA
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