1
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Shigetomi E, Suzuki H, Hirayama YJ, Sano F, Nagai Y, Yoshihara K, Koga K, Tateoka T, Yoshioka H, Shinozaki Y, Kinouchi H, Tanaka KF, Bito H, Tsuda M, Koizumi S. Disease-relevant upregulation of P2Y 1 receptor in astrocytes enhances neuronal excitability via IGFBP2. Nat Commun 2024; 15:6525. [PMID: 39117630 PMCID: PMC11310333 DOI: 10.1038/s41467-024-50190-7] [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: 08/18/2023] [Accepted: 06/26/2024] [Indexed: 08/10/2024] Open
Abstract
Reactive astrocytes play a pivotal role in the pathogenesis of neurological diseases; however, their functional phenotype and the downstream molecules by which they modify disease pathogenesis remain unclear. Here, we genetically increase P2Y1 receptor (P2Y1R) expression, which is upregulated in reactive astrocytes in several neurological diseases, in astrocytes of male mice to explore its function and the downstream molecule. This astrocyte-specific P2Y1R overexpression causes neuronal hyperexcitability by increasing both astrocytic and neuronal Ca2+ signals. We identify insulin-like growth factor-binding protein 2 (IGFBP2) as a downstream molecule of P2Y1R in astrocytes; IGFBP2 acts as an excitatory signal to cause neuronal excitation. In neurological disease models of epilepsy and stroke, reactive astrocytes upregulate P2Y1R and increase IGFBP2. The present findings identify a mechanism underlying astrocyte-driven neuronal hyperexcitability, which is likely to be shared by several neurological disorders, providing insights that might be relevant for intervention in diverse neurological disorders.
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Affiliation(s)
- Eiji Shigetomi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan.
- Yamanashi GLIA center, University of Yamanashi, Yamanashi, 409-3898, Japan.
| | - Hideaki Suzuki
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
- Yamanashi GLIA center, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Yukiho J Hirayama
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Fumikazu Sano
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
- Yamanashi GLIA center, University of Yamanashi, Yamanashi, 409-3898, Japan
- Department of Pediatrics, Faculty of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Yuki Nagai
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
- Yamanashi GLIA center, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Kohei Yoshihara
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Keisuke Koga
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Neurophysiology, Hyogo College of Medicine, Hyogo, 663-8501, Japan
| | - Toru Tateoka
- Department of Neurosurgery, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Hideyuki Yoshioka
- Department of Neurosurgery, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Youichi Shinozaki
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
- Yamanashi GLIA center, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Hiroyuki Kinouchi
- Department of Neurosurgery, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan
| | - Kenji F Tanaka
- Division of Brain Sciences, Institute for Advanced Medical Research, Keio University School of Medicine, Tokyo, 160-8582, Japan
| | - Haruhiko Bito
- Department of Neurochemistry, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-0033, Japan
| | - Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
- Department of Life Innovation, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, 812-8582, Japan
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Yamanashi, 409-3898, Japan.
- Yamanashi GLIA center, University of Yamanashi, Yamanashi, 409-3898, Japan.
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2
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Umpierre AD, Li B, Ayasoufi K, Simon WL, Zhao S, Xie M, Thyen G, Hur B, Zheng J, Liang Y, Bosco DB, Maynes MA, Wu Z, Yu X, Sung J, Johnson AJ, Li Y, Wu LJ. Microglial P2Y 6 calcium signaling promotes phagocytosis and shapes neuroimmune responses in epileptogenesis. Neuron 2024; 112:1959-1977.e10. [PMID: 38614103 PMCID: PMC11189754 DOI: 10.1016/j.neuron.2024.03.017] [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: 06/29/2023] [Revised: 01/09/2024] [Accepted: 03/13/2024] [Indexed: 04/15/2024]
Abstract
Microglial calcium signaling is rare in a baseline state but strongly engaged during early epilepsy development. The mechanism(s) governing microglial calcium signaling are not known. By developing an in vivo uridine diphosphate (UDP) fluorescent sensor, GRABUDP1.0, we discovered that UDP release is a conserved response to seizures and excitotoxicity across brain regions. UDP can signal through the microglial-enriched P2Y6 receptor to increase calcium activity during epileptogenesis. P2Y6 calcium activity is associated with lysosome biogenesis and enhanced production of NF-κB-related cytokines. In the hippocampus, knockout of the P2Y6 receptor prevents microglia from fully engulfing neurons. Attenuating microglial calcium signaling through calcium extruder ("CalEx") expression recapitulates multiple features of P2Y6 knockout, including reduced lysosome biogenesis and phagocytic interactions. Ultimately, P2Y6 knockout mice retain more CA3 neurons and better cognitive task performance during epileptogenesis. Our results demonstrate that P2Y6 signaling impacts multiple aspects of myeloid cell immune function during epileptogenesis.
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Affiliation(s)
| | - Bohan Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
| | | | - Whitney L Simon
- Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN 55905, USA
| | - Shunyi Zhao
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA; Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN 55905, USA
| | - Manling Xie
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Grace Thyen
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Benjamin Hur
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA; Department of Surgery, Mayo Clinic, Rochester, MN 55905, USA
| | - Jiaying Zheng
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Yue Liang
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Dale B Bosco
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA
| | - Mark A Maynes
- Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN 55905, USA
| | - Zhaofa Wu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China
| | - Xinzhu Yu
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jaeyun Sung
- Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905, USA; Department of Surgery, Mayo Clinic, Rochester, MN 55905, USA
| | - Aaron J Johnson
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA; Department of Immunology, Mayo Clinic, Rochester, MN 55905, USA
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China.
| | - Long-Jun Wu
- Department of Neurology, Mayo Clinic, Rochester, MN 55905, USA; Department of Immunology, Mayo Clinic, Rochester, MN 55905, USA; Center for Neuroimmunology and Glial Biology, Institute of Molecular Medicine, University of Texas Health Science Center, Houston, TX 77030, USA.
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3
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Cahill MK, Collard M, Tse V, Reitman ME, Etchenique R, Kirst C, Poskanzer KE. Network-level encoding of local neurotransmitters in cortical astrocytes. Nature 2024; 629:146-153. [PMID: 38632406 PMCID: PMC11062919 DOI: 10.1038/s41586-024-07311-5] [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: 04/03/2023] [Accepted: 03/13/2024] [Indexed: 04/19/2024]
Abstract
Astrocytes, the most abundant non-neuronal cell type in the mammalian brain, are crucial circuit components that respond to and modulate neuronal activity through calcium (Ca2+) signalling1-7. Astrocyte Ca2+ activity is highly heterogeneous and occurs across multiple spatiotemporal scales-from fast, subcellular activity3,4 to slow, synchronized activity across connected astrocyte networks8-10-to influence many processes5,7,11. However, the inputs that drive astrocyte network dynamics remain unclear. Here we used ex vivo and in vivo two-photon astrocyte imaging while mimicking neuronal neurotransmitter inputs at multiple spatiotemporal scales. We find that brief, subcellular inputs of GABA and glutamate lead to widespread, long-lasting astrocyte Ca2+ responses beyond an individual stimulated cell. Further, we find that a key subset of Ca2+ activity-propagative activity-differentiates astrocyte network responses to these two main neurotransmitters, and may influence responses to future inputs. Together, our results demonstrate that local, transient neurotransmitter inputs are encoded by broad cortical astrocyte networks over a minutes-long time course, contributing to accumulating evidence that substantial astrocyte-neuron communication occurs across slow, network-level spatiotemporal scales12-14. These findings will enable future studies to investigate the link between specific astrocyte Ca2+ activity and specific functional outputs, which could build a consistent framework for astrocytic modulation of neuronal activity.
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Affiliation(s)
- Michelle K Cahill
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA
| | - Max Collard
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA
| | - Vincent Tse
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
| | - Michael E Reitman
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA
| | - Roberto Etchenique
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - Christoph Kirst
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA
- Department of Anatomy, University of California, San Francisco, CA, USA
- Kavli Institute for Fundamental Neuroscience, San Francisco, CA, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Kira E Poskanzer
- Department of Biochemistry & Biophysics, University of California, San Francisco, CA, USA.
- Neuroscience Graduate Program, University of California, San Francisco, CA, USA.
- Kavli Institute for Fundamental Neuroscience, San Francisco, CA, USA.
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4
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Shigetomi E, Sakai K, Koizumi S. Extracellular ATP/adenosine dynamics in the brain and its role in health and disease. Front Cell Dev Biol 2024; 11:1343653. [PMID: 38304611 PMCID: PMC10830686 DOI: 10.3389/fcell.2023.1343653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 12/31/2023] [Indexed: 02/03/2024] Open
Abstract
Extracellular ATP and adenosine are neuromodulators that regulate numerous neuronal functions in the brain. Neuronal activity and brain insults such as ischemic and traumatic injury upregulate these neuromodulators, which exert their effects by activating purinergic receptors. In addition, extracellular ATP/adenosine signaling plays a pivotal role in the pathogenesis of neurological diseases. Virtually every cell type in the brain contributes to the elevation of ATP/adenosine, and various mechanisms underlying this increase have been proposed. Extracellular adenosine is thought to be mainly produced via the degradation of extracellular ATP. However, adenosine is also released from neurons and glia in the brain. Therefore, the regulation of extracellular ATP/adenosine in physiological and pathophysiological conditions is likely far more complex than previously thought. To elucidate the complex mechanisms that regulate extracellular ATP/adenosine levels, accurate methods of assessing their spatiotemporal dynamics are needed. Several novel techniques for acquiring spatiotemporal information on extracellular ATP/adenosine, including fluorescent sensors, have been developed and have started to reveal the mechanisms underlying the release, uptake and degradation of ATP/adenosine. Here, we review methods for analyzing extracellular ATP/adenosine dynamics as well as the current state of knowledge on the spatiotemporal dynamics of ATP/adenosine in the brain. We focus on the mechanisms used by neurons and glia to cooperatively produce the activity-dependent increase in ATP/adenosine and its physiological and pathophysiological significance in the brain.
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Affiliation(s)
- Eiji Shigetomi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Japan
- Yamanashi GLIA Center, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Japan
| | - Kent Sakai
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Japan
- Yamanashi GLIA Center, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Japan
| | - Schuichi Koizumi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Japan
- Yamanashi GLIA Center, Interdisciplinary Graduate School of Medicine, University of Yamanashi, Chuo, Japan
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5
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Kirchhoff F, Tang W. Analysis of Functional NMDA Receptors in Astrocytes. Methods Mol Biol 2024; 2799:201-223. [PMID: 38727909 DOI: 10.1007/978-1-0716-3830-9_11] [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] [Indexed: 07/03/2024]
Abstract
Neuronal N-methyl-D-aspartate (NMDA) receptors are well known for their pivotal role in memory formation. Originally, they were thought to be exclusive to neurons. However, numerous studies revealed their functional expression also on various types of glial cells in the nervous system. Here, the methodology on how to study the physiology of NMDA receptors selectively on astrocytes will be described in detail. Astrocytes are the main class of neuroglia that control transmitter and ion homeostasis, which link cerebral blood flow and neuronal energy demands, but also affect synaptic transmission directly.
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Affiliation(s)
- Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), Saarland University, Homburg, Germany
| | - Wannan Tang
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.
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6
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Cahill MK, Collard M, Tse V, Reitman ME, Etchenique R, Kirst C, Poskanzer KE. Network-level encoding of local neurotransmitters in cortical astrocytes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.01.568932. [PMID: 38106119 PMCID: PMC10723263 DOI: 10.1101/2023.12.01.568932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Astrocytes-the most abundant non-neuronal cell type in the mammalian brain-are crucial circuit components that respond to and modulate neuronal activity via calcium (Ca 2+ ) signaling 1-8 . Astrocyte Ca 2+ activity is highly heterogeneous and occurs across multiple spatiotemporal scales: from fast, subcellular activity 3,4 to slow, synchronized activity that travels across connected astrocyte networks 9-11 . Furthermore, astrocyte network activity has been shown to influence a wide range of processes 5,8,12 . While astrocyte network activity has important implications for neuronal circuit function, the inputs that drive astrocyte network dynamics remain unclear. Here we used ex vivo and in vivo two-photon Ca 2+ imaging of astrocytes while mimicking neuronal neurotransmitter inputs at multiple spatiotemporal scales. We find that brief, subcellular inputs of GABA and glutamate lead to widespread, long-lasting astrocyte Ca 2+ responses beyond an individual stimulated cell. Further, we find that a key subset of Ca 2+ activity-propagative events-differentiates astrocyte network responses to these two major neurotransmitters, and gates responses to future inputs. Together, our results demonstrate that local, transient neurotransmitter inputs are encoded by broad cortical astrocyte networks over the course of minutes, contributing to accumulating evidence across multiple model organisms that significant astrocyte-neuron communication occurs across slow, network-level spatiotemporal scales 13-15 . We anticipate that this study will be a starting point for future studies investigating the link between specific astrocyte Ca 2+ activity and specific astrocyte functional outputs, which could build a consistent framework for astrocytic modulation of neuronal activity.
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7
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Hjukse JB, Puebla MFDL, Vindedal GF, Sprengel R, Jensen V, Nagelhus EA, Tang W. Increased membrane Ca 2+ permeability drives astrocytic Ca 2+ dynamics during neuronal stimulation at excitatory synapses. Glia 2023; 71:2770-2781. [PMID: 37564028 DOI: 10.1002/glia.24450] [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: 03/16/2023] [Revised: 07/13/2023] [Accepted: 07/21/2023] [Indexed: 08/12/2023]
Abstract
Astrocytes are intricately involved in the activity of neural circuits; however, their basic physiology of interacting with nearby neurons is not well established. Using two-photon imaging of neurons and astrocytes during higher frequency stimulation of hippocampal CA3-CA1 Schaffer collateral (Scc) excitatory synapses, we could show that increasing levels of released glutamate accelerated local astrocytic Ca2+ elevation. However, blockage of glutamate transporters did not abolish this astrocytic Ca2+ response, suggesting that astrocytic Ca2+ elevation is indirectly associated with an uptake of extracellular glutamate. However, during the astrocytic glutamate uptake, the Na+ /Ca2+ exchanger (NCX) reverse mode was activated, and mediated extracellular Ca2+ entry, thereby triggering the internal release of Ca2+ . In addition, extracellular Ca2+ entry via membrane P2X receptors further facilitated astrocytic Ca2+ elevation via ATP binding. These findings suggest a novel mechanism of activity induced Ca2+ permeability increases of astrocytic membranes, which drives astrocytic responses during neuronal stimulation of CA3-CA1 Scc excitatory synapses.
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Affiliation(s)
- Jarand B Hjukse
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Mario F D L Puebla
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
- Department of Neurology, Neuroclinic, St. Olavs Hospital, Trondheim, Norway
| | - Gry Fluge Vindedal
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Rolf Sprengel
- Department of Neurology, Oslo University Hospital, Oslo, Norway
| | - Vidar Jensen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Erlend A Nagelhus
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Research Group of Molecular Neurobiology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Wannan Tang
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
- Department of Neurology, Neuroclinic, St. Olavs Hospital, Trondheim, Norway
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8
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Naik A, Jensen V, Bakketun CB, Enger R, Hrabetova S, Hrabe J. BubbleDrive, a low-volume incubation chamber for acute brain slices. Sci Rep 2023; 13:20005. [PMID: 37973847 PMCID: PMC10654715 DOI: 10.1038/s41598-023-45949-9] [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: 05/14/2023] [Accepted: 10/26/2023] [Indexed: 11/19/2023] Open
Abstract
Acute brain slices are a common and useful preparation in experimental neuroscience. A wide range of incubation chambers for brain slices exists but only a few are designed with very low volumes of the bath solution in mind. Such chambers are necessary when high-cost chemicals are to be added to the solution or when small amounts of substances released by the slice are to be collected for analysis. The principal challenge in designing a very low-volume incubation chamber is maintaining good oxygenation and flow without mechanically disturbing or damaging the slices. We designed and validated BubbleDrive, a 3D-printed incubation chamber with a minimum volume of 1.5 mL which can hold up to three coronal mouse slices from one hemisphere. It employs the carbogen gas bubbles to drive the flow circulation in a consistent and reproducible manner, and without disturbing the brain slices. The BubbleDrive design and construction were successfully validated by comparison to a conventional large-volume incubation chamber in several experimental designs involving measurements of extracellular diffusion parameters, the electrophysiology of neuronal and astrocytic networks, and the effectiveness of slice incubation with hyaluronidase enzyme.
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Affiliation(s)
- Aditi Naik
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA
- Neural and Behavioral Science Graduate Program, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA
| | - Vidar Jensen
- Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Cecilie Bugge Bakketun
- Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
- Department of Neurology, Oslo University Hospital, Oslo, Norway
| | - Rune Enger
- Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.
| | - Sabina Hrabetova
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA.
- The Robert F. Furchgott Center for Neural and Behavioral Science, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA.
| | - Jan Hrabe
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA.
- Translational Neuroscience Laboratories, Center for Biomedical Imaging and Neuromodulation, Nathan S. Kline Institute for Psychiatric Research, Orangeburg, NY, USA.
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9
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Bordoni L, Thoren AE, Gutiérrez‐Jiménez E, Åbjørsbråten KS, Bjørnstad DM, Tang W, Stern M, Østergaard L, Nagelhus EA, Frische S, Ottersen OP, Enger R. Deletion of aquaporin-4 improves capillary blood flow distribution in brain edema. Glia 2023; 71:2559-2572. [PMID: 37439315 PMCID: PMC10952478 DOI: 10.1002/glia.24439] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/14/2023]
Abstract
Brain edema is a feared complication to disorders and insults affecting the brain. It can be fatal if the increase in intracranial pressure is sufficiently large to cause brain herniation. Moreover, accruing evidence suggests that even slight elevations of intracranial pressure have adverse effects, for instance on brain perfusion. The water channel aquaporin-4 (AQP4), densely expressed in perivascular astrocytic endfeet, plays a key role in brain edema formation. Using two-photon microscopy, we have studied AQP4-mediated swelling of astrocytes affects capillary blood flow and intracranial pressure (ICP) in unanesthetized mice using a mild brain edema model. We found improved regulation of capillary blood flow in mice devoid of AQP4, independently of the severity of ICP increase. Furthermore, we found brisk AQP4-dependent astrocytic Ca2+ signals in perivascular endfeet during edema that may play a role in the perturbed capillary blood flow dynamics. The study suggests that astrocytic endfoot swelling and pathological signaling disrupts microvascular flow regulation during brain edema formation.
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Affiliation(s)
- Luca Bordoni
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | - Anna E. Thoren
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | - Eugenio Gutiérrez‐Jiménez
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical MedicineAarhus UniversityAarhusDenmark
| | - Knut S. Åbjørsbråten
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | - Daniel M. Bjørnstad
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | - Wannan Tang
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
- Department of Clinical and Molecular MedicineNorwegian University of Science and TechnologyTrondheimNorway
- Department of Neurology, NeuroclinicSt. Olavs HospitalTrondheimNorway
| | - Mette Stern
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical MedicineAarhus UniversityAarhusDenmark
- Department of NeuroradiologyAarhus University HospitalAarhusDenmark
| | - Erlend A. Nagelhus
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | | | - Ole P. Ottersen
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | - Rune Enger
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
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10
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Umpierre AD, Li B, Ayasoufi K, Zhao S, Xie M, Thyen G, Hur B, Zheng J, Liang Y, Wu Z, Yu X, Sung J, Johnson AJ, Li Y, Wu LJ. Microglial P2Y 6 calcium signaling promotes phagocytosis and shapes neuroimmune responses in epileptogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.12.544691. [PMID: 37398001 PMCID: PMC10312639 DOI: 10.1101/2023.06.12.544691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Microglial calcium signaling is rare in a baseline state but shows strong engagement during early epilepsy development. The mechanism and purpose behind microglial calcium signaling is not known. By developing an in vivo UDP fluorescent sensor, GRABUDP1.0, we discovered that UDP release is a conserved response to seizures and excitotoxicity across brain regions. UDP signals to the microglial P2Y6 receptor for broad increases in calcium signaling during epileptogenesis. UDP-P2Y6 signaling is necessary for lysosome upregulation across limbic brain regions and enhances production of pro-inflammatory cytokines-TNFα and IL-1β. Failures in lysosome upregulation, observed in P2Y6 KO mice, can also be phenocopied by attenuating microglial calcium signaling in Calcium Extruder ("CalEx") mice. In the hippocampus, only microglia with P2Y6 expression can perform full neuronal engulfment, which substantially reduces CA3 neuron survival and impairs cognition. Our results demonstrate that calcium activity, driven by UDP-P2Y6 signaling, is a signature of phagocytic and pro-inflammatory function in microglia during epileptogenesis.
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Affiliation(s)
- Anthony D. Umpierre
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- These authors contributed equally
| | - Bohan Li
- State Key Laboratory of Membrane Biology, New Cornerstone Science Laboratory, Peking University School of Life Sciences, Beijing, CN 100871
- These authors contributed equally
| | | | - Shunyi Zhao
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- Neuroscience Track, Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN 55905
| | - Manling Xie
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- Neuroscience Track, Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN 55905
| | - Grace Thyen
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
| | - Benjamin Hur
- Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905
- Division of Surgery Research, Department of Surgery, Mayo Clinic, Rochester, MN 55905
| | - Jiaying Zheng
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- Neuroscience Track, Graduate School of Biomedical Sciences, Mayo Clinic, Rochester, MN 55905
| | - Yue Liang
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
| | - Zhaofa Wu
- State Key Laboratory of Membrane Biology, New Cornerstone Science Laboratory, Peking University School of Life Sciences, Beijing, CN 100871
| | - Xinzhu Yu
- Department of Molecular and Integrative Physiology, Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Jaeyun Sung
- Microbiome Program, Center for Individualized Medicine, Mayo Clinic, Rochester, MN 55905
- Division of Surgery Research, Department of Surgery, Mayo Clinic, Rochester, MN 55905
| | - Aaron J. Johnson
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- Department of Immunology, Mayo Clinic, Rochester, MN 55905
- Department of Molecular Medicine, Mayo Clinic, Rochester MN 55905
| | - Yulong Li
- State Key Laboratory of Membrane Biology, New Cornerstone Science Laboratory, Peking University School of Life Sciences, Beijing, CN 100871
| | - Long-Jun Wu
- Department of Neurology, Mayo Clinic, Rochester, MN 55905
- Department of Immunology, Mayo Clinic, Rochester, MN 55905
- Lead contact
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11
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Lee SH, Mak A, Verheijen MHG. Comparative assessment of the effects of DREADDs and endogenously expressed GPCRs in hippocampal astrocytes on synaptic activity and memory. Front Cell Neurosci 2023; 17:1159756. [PMID: 37051110 PMCID: PMC10083367 DOI: 10.3389/fncel.2023.1159756] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 03/13/2023] [Indexed: 03/29/2023] Open
Abstract
Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) have proven themselves as one of the key in vivo techniques of modern neuroscience, allowing for unprecedented access to cellular manipulations in living animals. With respect to astrocyte research, DREADDs have become a popular method to examine the functional aspects of astrocyte activity, particularly G-protein coupled receptor (GPCR)-mediated intracellular calcium (Ca2+) and cyclic adenosine monophosphate (cAMP) dynamics. With this method it has become possible to directly link the physiological aspects of astrocytic function to cognitive processes such as memory. As a result, a multitude of studies have explored the impact of DREADD activation in astrocytes on synaptic activity and memory. However, the emergence of varying results prompts us to reconsider the degree to which DREADDs expressed in astrocytes accurately mimic endogenous GPCR activity. Here we compare the major downstream signaling mechanisms, synaptic, and behavioral effects of stimulating Gq-, Gs-, and Gi-DREADDs in hippocampal astrocytes of adult mice to those of endogenously expressed GPCRs.
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Affiliation(s)
- Sophie H. Lee
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- Research Master’s Programme Brain and Cognitive Sciences, University of Amsterdam, Amsterdam, Netherlands
| | - Aline Mak
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
| | - Mark H. G. Verheijen
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam, Netherlands
- *Correspondence: Mark Verheijen,
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12
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Zanoletti L, Valdata A, Nehlsen K, Faris P, Casali C, Cacciatore R, Sbarsi I, Carriero F, Arfini D, van Baarle L, De Simone V, Barbieri G, Raimondi E, May T, Moccia F, Bozzola M, Matteoli G, Comincini S, Manai F. Cytological, molecular, cytogenetic, and physiological characterization of a novel immortalized human enteric glial cell line. Front Cell Neurosci 2023; 17:1170309. [PMID: 37153631 PMCID: PMC10158601 DOI: 10.3389/fncel.2023.1170309] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 03/22/2023] [Indexed: 05/10/2023] Open
Abstract
Enteric glial cells (EGCs), the major components of the enteric nervous system (ENS), are implicated in the maintenance of gut homeostasis, thereby leading to severe pathological conditions when impaired. However, due to technical difficulties associated with EGCs isolation and cell culture maintenance that results in a lack of valuable in vitro models, their roles in physiological and pathological contexts have been poorly investigated so far. To this aim, we developed for the first time, a human immortalized EGC line (referred as ClK clone) through a validated lentiviral transgene protocol. As a result, ClK phenotypic glial features were confirmed by morphological and molecular evaluations, also providing the consensus karyotype and finely mapping the chromosomal rearrangements as well as HLA-related genotypes. Lastly, we investigated the ATP- and acetylcholine, serotonin and glutamate neurotransmitters mediated intracellular Ca2+ signaling activation and the response of EGCs markers (GFAP, SOX10, S100β, PLP1, and CCL2) upon inflammatory stimuli, further confirming the glial nature of the analyzed cells. Overall, this contribution provided a novel potential in vitro tool to finely characterize the EGCs behavior under physiological and pathological conditions in humans.
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Affiliation(s)
- Lisa Zanoletti
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
- Department of Chronic Diseases and Metabolism (CHROMETA), KU Leuven, Leuven, Belgium
| | - Aurora Valdata
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | | | - Pawan Faris
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
- Department of Biology, College of Science, Salahaddin University-Erbil, Erbil, Iraq
| | - Claudio Casali
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | - Rosalia Cacciatore
- Immunohematology and Transfusion Service, I.R.C.C.S. Policlinico San Matteo, Pavia, Italy
| | - Ilaria Sbarsi
- Immunohematology and Transfusion Service, I.R.C.C.S. Policlinico San Matteo, Pavia, Italy
| | - Francesca Carriero
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | - Davide Arfini
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | - Lies van Baarle
- Department of Chronic Diseases and Metabolism (CHROMETA), KU Leuven, Leuven, Belgium
| | - Veronica De Simone
- Department of Chronic Diseases and Metabolism (CHROMETA), KU Leuven, Leuven, Belgium
| | - Giulia Barbieri
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | - Elena Raimondi
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | | | - Francesco Moccia
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | | | - Gianluca Matteoli
- Department of Chronic Diseases and Metabolism (CHROMETA), KU Leuven, Leuven, Belgium
| | - Sergio Comincini
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
| | - Federico Manai
- Department of Biology and Biotechnology “L. Spallanzani”, University of Pavia, Pavia, Italy
- *Correspondence: Federico Manai,
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13
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Role for Astrocytes in mGluR-Dependent LTD in the Neocortex and Hippocampus. Brain Sci 2022; 12:brainsci12121718. [PMID: 36552177 PMCID: PMC9776455 DOI: 10.3390/brainsci12121718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2022] [Revised: 12/11/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Astroglia are an active element of brain plasticity, capable to release small molecule gliotransmitters by various mechanisms and regulate synaptic strength. While importance of glia-neuron communications for long-term potentiation has been rather widely reported, research into role for astrocytes in long-depression (LTD) is just gaining momentum. Here, we explored the role for astrocytes in the prominent form of synaptic plasticity-mGluR-dependent LTD. We found out the substantial contribution of the Group I receptors, especially mGluR1 subtype, into Ca2+-signaling in hippocampal and neocortical astrocytes, which can be activated during synaptic stimulation used for LTD induction. Our data demonstrate that mGluR receptors can activate SNARE-dependent release of ATP from astrocytes which in turn can directly activate postsynaptic P2X receptors in the hippocampal and neocortical neurons. The latter mechanism has recently been shown to cause the synaptic depression via triggering the internalisation of AMPA receptors. Using mouse model of impaired glial exocytosis (dnSNARE mice), we demonstrated that mGluR-activated release of ATP from astrocytes is essential for regulation of mGluR-dependent LTD in CA3-CA1 and layer 2/3 synapses. Our data also suggest that astrocyte-related pathway relies mainly on mGluR1 receptors and act synergistically with neuronal mechanisms dependent mainly on mGluR5.
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14
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Baur K, Abdullah Y, Mandl C, Hölzl‐Wenig G, Shi Y, Edelkraut U, Khatri P, Hagenston AM, Irmler M, Beckers J, Ciccolini F. A novel stem cell type at the basal side of the subventricular zone maintains adult neurogenesis. EMBO Rep 2022; 23:e54078. [PMID: 35861333 PMCID: PMC9442324 DOI: 10.15252/embr.202154078] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 06/20/2022] [Accepted: 07/04/2022] [Indexed: 11/09/2022] Open
Affiliation(s)
- Katja Baur
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
| | - Yomn Abdullah
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
| | - Claudia Mandl
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
| | - Gabriele Hölzl‐Wenig
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
| | - Yan Shi
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
| | - Udo Edelkraut
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
| | - Priti Khatri
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
| | - Anna M Hagenston
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
| | - Martin Irmler
- Helmholtz Zentrum München GmbH Institute of Experimental Genetics Neuherberg Germany
| | - Johannes Beckers
- Helmholtz Zentrum München GmbH Institute of Experimental Genetics Neuherberg Germany
- Technische Universität München Chair of Experimental Genetics Weihenstephan Germany
- Deutsches Zentrum für Diabetesforschung e.V. (DZD) Neuherberg Germany
| | - Francesca Ciccolini
- Department of Neurobiology, Interdisciplinary Center for Neurosciences Heidelberg University Heidelberg Germany
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15
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Pillai AG, Nadkarni S. Amyloid pathology disrupts gliotransmitter release in astrocytes. PLoS Comput Biol 2022; 18:e1010334. [PMID: 35913987 PMCID: PMC9371304 DOI: 10.1371/journal.pcbi.1010334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/11/2022] [Accepted: 06/28/2022] [Indexed: 01/11/2023] Open
Abstract
Accumulation of amyloid-beta (Aβ) is associated with synaptic dysfunction and destabilization of astrocytic calcium homeostasis. A growing body of evidence support astrocytes as active modulators of synaptic transmission via calcium-mediated gliotransmission. However, the details of mechanisms linking Aβ signaling, astrocytic calcium dynamics, and gliotransmission are not known. We developed a biophysical model that describes calcium signaling and the ensuing gliotransmitter release from a single astrocytic process when stimulated by glutamate release from hippocampal neurons. The model accurately captures the temporal dynamics of microdomain calcium signaling and glutamate release via both kiss-and-run and full-fusion exocytosis. We investigate the roles of two crucial calcium regulating machineries affected by Aβ: plasma-membrane calcium pumps (PMCA) and metabotropic glutamate receptors (mGluRs). When we implemented these Aβ-affected molecular changes in our astrocyte model, it led to an increase in the rate and synchrony of calcium events. Our model also reproduces several previous findings of Aβ associated aberrant calcium activity, such as increased intracellular calcium level and increased spontaneous calcium activity, and synchronous calcium events. The study establishes a causal link between previous observations of hyperactive astrocytes in Alzheimer’s disease (AD) and Aβ-induced modifications in mGluR and PMCA functions. Analogous to neurotransmitter release, gliotransmitter exocytosis closely tracks calcium changes in astrocyte processes, thereby guaranteeing tight control of synaptic signaling by astrocytes. However, the downstream effects of AD-related calcium changes in astrocytes on gliotransmitter release are not known. Our results show that enhanced rate of exocytosis resulting from modified calcium signaling in astrocytes leads to a rapid depletion of docked vesicles that disrupts the crucial temporal correspondence between a calcium event and vesicular release. We propose that the loss of temporal correspondence between calcium events and gliotransmission in astrocytes pathologically alters astrocytic modulation of synaptic transmission in the presence of Aβ accumulation. Signaling by astrocytes is critical to information processing at synapses, and its aberration plays a central role in neurological diseases, especially Alzheimer’s disease (AD). A complete characterization of calcium signaling and the resulting pattern of gliotransmitter release from fine astrocytic processes are not accessible to current experimental tools. We developed a biophysical model that can quantitatively describe signaling by astrocytes in response to a wide range of synaptic activity. We show that AD-related molecular alterations disrupt the concurrence of calcium and gliotransmitter release events, a characterizing feature that enables astrocytes to influence synaptic signaling.
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Affiliation(s)
| | - Suhita Nadkarni
- Indian Institute of Science Education and Research Pune, Pune, India
- * E-mail:
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16
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Men Y, Higashimori H, Reynolds K, Tu L, Jarvis R, Yang Y. Functionally Clustered mRNAs Are Distinctly Enriched at Cortical Astroglial Processes and Are Preferentially Affected by FMRP Deficiency. J Neurosci 2022; 42:5803-5814. [PMID: 35701158 PMCID: PMC9302465 DOI: 10.1523/jneurosci.0274-22.2022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 05/06/2022] [Accepted: 06/08/2022] [Indexed: 01/22/2023] Open
Abstract
Mature protoplasmic astroglia in the mammalian CNS uniquely possess a large number of fine processes that have been considered primary sites to mediate astroglia to neuron synaptic signaling. However, localized mechanisms for regulating interactions between astroglial processes and synapses, especially for regulating the expression of functional surface proteins at these fine processes, are largely unknown. Previously, we showed that the loss of the RNA binding protein FMRP in astroglia disrupts astroglial mGluR5 signaling and reduces expression of the major astroglial glutamate transporter GLT1 and glutamate uptake in the cortex of Fmr1 conditional deletion mice. In the current study, by examining ribosome localization using electron microscopy and identifying mRNAs enriched at cortical astroglial processes using synaptoneurosome/translating ribosome affinity purification and RNA-Seq in WT and FMRP-deficient male mice, our results reveal interesting localization-dependent functional clusters of mRNAs at astroglial processes. We further showed that the lack of FMRP preferentially alters the subcellular localization and expression of process-localized mRNAs. Together, we defined the role of FMRP in altering mRNA localization and expression at astroglial processes at the postnatal development (P30-P40) and provided new candidate mRNAs that are potentially regulated by FMRP in cortical astroglia.SIGNIFICANCE STATEMENT Localized mechanisms for regulating interactions between astroglial processes and synapses, especially for regulating the expression of functional surface proteins at these fine processes, are largely unknown. Previously, we showed that the loss of the RNA binding protein FMRP in astroglia disrupts expression of several astroglial surface proteins, such as mGluR5 and major astroglial glutamate transporter GLT1 in the cortex of FMRP-deficient mice. Our current study examined ribosome localization using electron microscopy and identified mRNAs enriched at cortical astroglial processes in WT and FMRP-deficient mice. These results reveal interesting localization-dependent functional clusters of mRNAs at astroglial processes and demonstrate that the lack of FMRP preferentially alters the subcellular localization and expression of process-localized mRNAs.
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Affiliation(s)
- Yuqin Men
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Haruki Higashimori
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Kathryn Reynolds
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Leona Tu
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Rachel Jarvis
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Yongjie Yang
- Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts 02111
- Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts 02111
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17
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Åbjørsbråten KS, Skaaraas GHE, Cunen C, Bjørnstad DM, Binder KM, Bojarskaite L, Jensen V, Nilsson LNG, Rao SB, Tang W, Hermansen GH, Nagelhus EA, Ottersen OP, Torp R, Enger R. Impaired astrocytic Ca 2+ signaling in awake-behaving Alzheimer's disease transgenic mice. eLife 2022; 11:75055. [PMID: 35833623 PMCID: PMC9352348 DOI: 10.7554/elife.75055] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 06/29/2022] [Indexed: 11/22/2022] Open
Abstract
Increased astrocytic Ca2+ signaling has been shown in Alzheimer’s disease mouse models, but to date no reports have characterized behaviorally induced astrocytic Ca2+ signaling in such mice. Here, we employ an event-based algorithm to assess astrocytic Ca2+ signals in the neocortex of awake-behaving tg-ArcSwe mice and non-transgenic wildtype littermates while monitoring pupil responses and behavior. We demonstrate an attenuated astrocytic Ca2+ response to locomotion and an uncoupling of pupil responses and astrocytic Ca2+ signaling in 15-month-old plaque-bearing mice. Using the genetically encoded fluorescent norepinephrine sensor GRABNE, we demonstrate a reduced norepinephrine signaling during spontaneous running and startle responses in the transgenic mice, providing a possible mechanistic underpinning of the observed reduced astrocytic Ca2+ responses. Our data points to a dysfunction in the norepinephrine–astrocyte Ca2+ activity axis, which may account for some of the cognitive deficits observed in Alzheimer’s disease. Neurodegenerative conditions such as Parkinson’s or Alzheimer’s disease are characterized by neurons dying and being damaged. Yet neurons are only one type of brain actors; astrocytes, for example, are star-shaped ‘companion’ cells that have recently emerged as being able to fine-tune neuronal communication. In particular, they can respond to norepinephrine, a signaling molecule that acts to prepare the brain and body for action. This activation results, for instance, in astrocytes releasing chemicals that can act on neurons. Certain cognitive symptoms associated with Alzheimer’s disease could be due to a lack of norepinephrine. In parallel, studies in anaesthetized mice have shown perturbed astrocyte signaling in a model of the condition. Disrupted norepinephrine-triggered astrocyte signaling could therefore be implicated in the symptoms of the disease. Experiments in awake mice are needed to investigate this link, especially as anesthesia is known to disrupt the activity of astrocytes. To explore this question, Åbjørsbråten, Skaaraas et al. conducted experiments in naturally behaving mice expressing mutations found in patients with early-onset Alzheimer’s disease. These mice develop hallmarks of the disorder. Compared to their healthy counterparts, these animals had reduced astrocyte signaling when running or being startled. Similarly, a fluorescent molecular marker for norepinephrine demonstrated less signaling in the modified mice compared to healthy ones. Over 55 million individuals currently live with Alzheimer’s disease. The results by Åbjørsbråten, Skaaraas et al. suggest that astrocyte–norepinephrine communication may be implicated in the condition, an avenue of research that could potentially lead to developing new treatments.
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Affiliation(s)
| | - Gry H E Skaaraas
- Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Céline Cunen
- Department of Mathematics, University of Oslo, Oslo, Norway
| | | | - Kristin M Binder
- Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | | | - Vidar Jensen
- Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | | | - Shreyas B Rao
- Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Wannan Tang
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | | | | | | | - Reidun Torp
- Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Rune Enger
- Department of Molecular Medicine, University of Oslo, Oslo, Norway
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18
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Disrupted expression of mitochondrial NCLX sensitizes neuroglial networks to excitotoxic stimuli and renders synaptic activity toxic. J Biol Chem 2021; 298:101508. [PMID: 34942149 PMCID: PMC8808183 DOI: 10.1016/j.jbc.2021.101508] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 02/06/2023] Open
Abstract
The mitochondrial sodium/calcium/lithium exchanger (NCLX) is an important mediator of calcium extrusion from mitochondria. In this study, we tested the hypothesis that physiological expression levels of NCLX are essential for maintaining neuronal resilience in the face of excitotoxic challenge. Using a short hairpin RNA (shRNA)-mediated approach, we showed that reduced NCLX expression exacerbates neuronal mitochondrial calcium dysregulation, mitochondrial membrane potential (ΔΨm) breakdown, and reactive oxygen species (ROS) generation during excitotoxic stimulation of primary hippocampal cultures. Moreover, NCLX knockdown-which affected both neurons and glia-resulted not only in enhanced neurodegeneration following an excitotoxic insult, but also in neuronal and astrocytic cell death under basal conditions. Our data also revealed that synaptic activity, which promotes neuroprotective signaling, can become lethal upon NCLX depletion; expression of NCLX-targeted shRNA impaired the clearance of mitochondrial calcium following action potential bursts and was associated both with ΔΨmbreakdown and substantial neurodegeneration in hippocampal cultures undergoing synaptic activity. Finally, we showed that NCLX knockdown within the hippocampal cornu ammonis 1 (CA1) region in vivo causes substantial neuro- and astrodegeneration. In summary, we demonstrated that dysregulated NCLX expression not only sensitizes neuroglial networks to excitotoxic stimuli but notably also renders otherwise neuroprotective synaptic activity toxic. These findings may explain the emergence of neuro- and astrodegeneration in patients with disorders characterized by disrupted NCLX expression or function, and suggest that treatments aimed at enhancing or restoring NCLX function may prevent central nervous system damage in these disease states.
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19
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Lalo U, Koh W, Lee CJ, Pankratov Y. The tripartite glutamatergic synapse. Neuropharmacology 2021; 199:108758. [PMID: 34433089 DOI: 10.1016/j.neuropharm.2021.108758] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/25/2021] [Accepted: 08/20/2021] [Indexed: 12/31/2022]
Abstract
Astroglial cells were long considered as structural and metabolic supporting cells are which do not directly participate in information processing in the brain. Discoveries of responsiveness of astrocytes to synaptically-released glutamate and their capability to release agonists of glutamate receptors awakened extensive studies of glia-neuron communications and led to the revolutionary changes in our understanding of brain cellular networks. Nowadays, astrocytes are widely acknowledged as inseparable element of glutamatergic synapses and role for glutamatergic astrocyte-neuron interactions in the brain computation is emerging. Astroglial glutamate receptors, in particular of NMDA, mGluR3 and mGluR5 types, can activate a variety of molecular cascades leading astroglial-driven modulation of extracellular levels of glutamate and activity of neuronal glutamate receptors. Their preferential location to the astroglial perisynaptic processes facilitates interaction of astrocytes with individual excitatory synapses. Bi-directional glutamatergic communication between astrocytes and neurons underpins a complex, spatially-distributed modulation of synaptic signalling thus contributing to the enrichment of information processing by the neuronal networks. Still, further research is needed to bridge the substantial gaps in our understanding of mechanisms and physiological relevance of astrocyte-neuron glutamatergic interactions, in particular ability of astrocytes directly activate neuronal glutamate receptors by releasing glutamate and, arguably, d-Serine. An emerging roles for aberrant changes in glutamatergic astroglial signalling, both neuroprotective and pathogenic, in neurological and neurodegenerative diseases also require further investigation. This article is part of the special Issue on 'Glutamate Receptors - The Glutamatergic Synapse'.
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Affiliation(s)
- Ulyana Lalo
- School of Life Sciences, Immanuel Kant Baltic Federal University, Kaliningrad, Russia
| | - Wuhyun Koh
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, 34126, South Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, 34126, South Korea
| | - Yuriy Pankratov
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom.
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20
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Benfey NJ, Li VJ, Schohl A, Ruthazer ES. Sodium-calcium exchanger mediates sensory-evoked glial calcium transients in the developing retinotectal system. Cell Rep 2021; 37:109791. [PMID: 34610307 DOI: 10.1016/j.celrep.2021.109791] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 06/24/2021] [Accepted: 09/13/2021] [Indexed: 12/14/2022] Open
Abstract
Various types of sensory stimuli have been shown to induce Ca2+ elevations in glia. However, a mechanistic understanding of the signaling pathways mediating sensory-evoked activity in glia in intact animals is still emerging. During early development of the Xenopus laevis visual system, radial astrocytes in the optic tectum are highly responsive to sensory stimulation. Ca2+ transients occur spontaneously in radial astrocytes at rest and are abolished by silencing neuronal activity with tetrodotoxin. Visual stimulation drives temporally correlated increases in the activity patterns of neighboring radial astrocytes. Following blockade of all glutamate receptors (gluRs), visually evoked Ca2+ activity in radial astrocytes persists, while neuronal activity is suppressed. The additional blockade of either glu transporters or sodium-calcium exchangers (NCX) abolishes visually evoked responses in glia. Finally, we demonstrate that blockade of NCX alone is sufficient to prevent visually evoked responses in radial astrocytes, highlighting a pivotal role for NCX in glia during development.
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Affiliation(s)
- Nicholas J Benfey
- Montreal Neurological Institute-Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, H3A 2B4 Canada
| | - Vanessa J Li
- Montreal Neurological Institute-Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, H3A 2B4 Canada
| | - Anne Schohl
- Montreal Neurological Institute-Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, H3A 2B4 Canada
| | - Edward S Ruthazer
- Montreal Neurological Institute-Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, H3A 2B4 Canada.
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21
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Sherwood MW, Arizono M, Panatier A, Mikoshiba K, Oliet SHR. Astrocytic IP 3Rs: Beyond IP 3R2. Front Cell Neurosci 2021; 15:695817. [PMID: 34393726 PMCID: PMC8363081 DOI: 10.3389/fncel.2021.695817] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/30/2021] [Indexed: 12/31/2022] Open
Abstract
Astrocytes are sensitive to ongoing neuronal/network activities and, accordingly, regulate neuronal functions (synaptic transmission, synaptic plasticity, behavior, etc.) by the context-dependent release of several gliotransmitters (e.g., glutamate, glycine, D-serine, ATP). To sense diverse input, astrocytes express a plethora of G-protein coupled receptors, which couple, via Gi/o and Gq, to the intracellular Ca2+ release channel IP3-receptor (IP3R). Indeed, manipulating astrocytic IP3R-Ca2+ signaling is highly consequential at the network and behavioral level: Depleting IP3R subtype 2 (IP3R2) results in reduced GPCR-Ca2+ signaling and impaired synaptic plasticity; enhancing IP3R-Ca2+ signaling affects cognitive functions such as learning and memory, sleep, and mood. However, as a result of discrepancies in the literature, the role of GPCR-IP3R-Ca2+ signaling, especially under physiological conditions, remains inconclusive. One primary reason for this could be that IP3R2 has been used to represent all astrocytic IP3Rs, including IP3R1 and IP3R3. Indeed, IP3R1 and IP3R3 are unique Ca2+ channels in their own right; they have unique biophysical properties, often display distinct distribution, and are differentially regulated. As a result, they mediate different physiological roles to IP3R2. Thus, these additional channels promise to enrich the diversity of spatiotemporal Ca2+ dynamics and provide unique opportunities for integrating neuronal input and modulating astrocyte–neuron communication. The current review weighs evidence supporting the existence of multiple astrocytic-IP3R isoforms, summarizes distinct sub-type specific properties that shape spatiotemporal Ca2+ dynamics. We also discuss existing experimental tools and future refinements to better recapitulate the endogenous activities of each IP3R isoform.
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Affiliation(s)
- Mark W Sherwood
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Misa Arizono
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France
| | - Aude Panatier
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Katsuhiko Mikoshiba
- ShanghaiTech University, Shanghai, China.,Faculty of Science, Toho University, Funabashi, Japan.,RIKEN CLST, Kobe, Japan
| | - Stéphane H R Oliet
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
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22
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Dzyubenko E, Prazuch W, Pillath-Eilers M, Polanska J, Hermann DM. Analysing Intercellular Communication in Astrocytic Networks Using "Astral". Front Cell Neurosci 2021; 15:689268. [PMID: 34211372 PMCID: PMC8239356 DOI: 10.3389/fncel.2021.689268] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/19/2021] [Indexed: 12/15/2022] Open
Abstract
Astrocytic networks are critically involved in regulating the activity of neuronal networks. However, a comprehensive and ready-to-use data analysis tool for investigating functional interactions between the astrocytes is missing. We developed the novel software package named "Astral" to analyse intercellular communication in astrocytic networks based on live-cell calcium imaging. Our method for analysing calcium imaging data does not require the assignment of regions of interest. The package contains two applications: the core processing pipeline for detecting and quantifying Ca++ events, and the auxiliary visualization tool for controlling data quality. Our method allows for the network-wide quantification of Ca++ events and the analysis of their intercellular propagation. In a set of proof-of-concept experiments, we examined Ca++ events in flat monolayers of primary astrocytes and confirmed that inter-astrocytic interactions depend on the permeability of gap junctions and connexin hemichannels. The Astral tool is particularly useful for studying astrocyte-neuronal interactions on the network level. We demonstrate that compared with purely astrocytic cultures, spontaneous generation of Ca++ events in astrocytes that were co-cultivated with neurons was significantly increased. Interestingly, the increased astrocytic Ca++ activity after long-term co-cultivation with neurons was driven by the enhanced formation of gap junctions and connexin hemichannels but was not affected by silencing neuronal activity. Our data indicate the necessity for systematic investigation of astrocyte-neuronal interactions at the network level. For this purpose, the Astral software offers a powerful tool for processing and quantifying calcium imaging data.
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Affiliation(s)
- Egor Dzyubenko
- Department of Neurology and Center for Translational Neuro- and Behavioral Sciences (C-TNBS), University Hospital Essen, Essen, Germany
| | - Wojciech Prazuch
- Department of Data Science and Engineering, Silesian University of Technology Faculty of Automatic Control, Electronics and Computer Science, Gliwice, Poland
| | - Matthias Pillath-Eilers
- Department of Neurology and Center for Translational Neuro- and Behavioral Sciences (C-TNBS), University Hospital Essen, Essen, Germany
| | - Joanna Polanska
- Department of Data Science and Engineering, Silesian University of Technology Faculty of Automatic Control, Electronics and Computer Science, Gliwice, Poland
| | - Dirk M Hermann
- Department of Neurology and Center for Translational Neuro- and Behavioral Sciences (C-TNBS), University Hospital Essen, Essen, Germany
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23
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Bojarskaite L, Bjørnstad DM, Pettersen KH, Cunen C, Hermansen GH, Åbjørsbråten KS, Chambers AR, Sprengel R, Vervaeke K, Tang W, Enger R, Nagelhus EA. Astrocytic Ca 2+ signaling is reduced during sleep and is involved in the regulation of slow wave sleep. Nat Commun 2020; 11:3240. [PMID: 32632168 PMCID: PMC7338360 DOI: 10.1038/s41467-020-17062-2] [Citation(s) in RCA: 103] [Impact Index Per Article: 25.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 06/09/2020] [Indexed: 12/31/2022] Open
Abstract
Astrocytic Ca2+ signaling has been intensively studied in health and disease but has not been quantified during natural sleep. Here, we employ an activity-based algorithm to assess astrocytic Ca2+ signals in the neocortex of awake and naturally sleeping mice while monitoring neuronal Ca2+ activity, brain rhythms and behavior. We show that astrocytic Ca2+ signals exhibit distinct features across the sleep-wake cycle and are reduced during sleep compared to wakefulness. Moreover, an increase in astrocytic Ca2+ signaling precedes transitions from slow wave sleep to wakefulness, with a peak upon awakening exceeding the levels during whisking and locomotion. Finally, genetic ablation of an important astrocytic Ca2+ signaling pathway impairs slow wave sleep and results in an increased number of microarousals, abnormal brain rhythms, and an increased frequency of slow wave sleep state transitions and sleep spindles. Our findings demonstrate an essential role for astrocytic Ca2+ signaling in regulating slow wave sleep.
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Affiliation(s)
- Laura Bojarskaite
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
| | - Daniel M Bjørnstad
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
| | - Klas H Pettersen
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
| | - Céline Cunen
- Statistics and Data Science group, Department of Mathematics, Faculty of Mathematics and Natural Sciences, University of Oslo, 0316, Oslo, Norway
| | - Gudmund Horn Hermansen
- Statistics and Data Science group, Department of Mathematics, Faculty of Mathematics and Natural Sciences, University of Oslo, 0316, Oslo, Norway
| | - Knut Sindre Åbjørsbråten
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
| | - Anna R Chambers
- Lab for Neural Computation, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
| | - Rolf Sprengel
- Research Group of the Max Planck Institute for Medical Research, Institute for Anatomy and Cell Biology, Heidelberg University, 69120, Heidelberg, Germany
| | - Koen Vervaeke
- Lab for Neural Computation, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
| | - Wannan Tang
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
- Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology, Trondheim, Norway
| | - Rune Enger
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway.
- Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway.
- Department of Neurology, Oslo University Hospital, Rikshospitalet, 0027, Oslo, Norway.
| | - Erlend A Nagelhus
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, 0317, Oslo, Norway
- Department of Neurology, Oslo University Hospital, Rikshospitalet, 0027, Oslo, Norway
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24
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Sugimoto H, Sato M, Nakai J, Kawakami K. Astrocytes in Atp1a2-deficient heterozygous mice exhibit hyperactivity after induction of cortical spreading depression. FEBS Open Bio 2020; 10:1031-1043. [PMID: 32237043 PMCID: PMC7262908 DOI: 10.1002/2211-5463.12848] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 03/01/2020] [Accepted: 03/25/2020] [Indexed: 01/17/2023] Open
Abstract
The ATP1A2 coding α2 subunit of Na,K‐ATPase, which is predominantly located in astrocytes, is a causative gene of familial hemiplegic migraine type 2 (FHM2). FHM2 model mice (Atp1a2tmCKwk/+) are susceptible to cortical spreading depression (CSD), which is profoundly related to migraine aura and headache. However, astrocytic properties during CSD have not been examined in FHM2 model mice. Using Atp1a2tmCKwk/+ crossed with transgenic mice expressing G‐CaMP7 in cortical neurons and astrocytes (Atp1a2+/−), we analyzed the changes in Ca2+ concentrations during CSD. The propagation speed of Ca2+ waves and the percentages of astrocytes with elevated Ca2+ concentrations in Atp1a2+/− were higher than those in wild‐type mice. Increased percentages of astrocytes with elevated Ca2+ concentrations in Atp1a2+/− may contribute to FHM2 pathophysiology.
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Affiliation(s)
- Hiroki Sugimoto
- Division of Biology, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
| | - Masaaki Sato
- Graduate School of Science and Engineering, Saitama University, Japan.,Brain and Body System Science Institute, Saitama University, Japan.,Laboratory for Mental Biology, RIKEN Center for Brain Science, Saitama, Japan
| | - Junichi Nakai
- Graduate School of Science and Engineering, Saitama University, Japan.,Brain and Body System Science Institute, Saitama University, Japan
| | - Kiyoshi Kawakami
- Division of Biology, Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan
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25
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King CM, Bohmbach K, Minge D, Delekate A, Zheng K, Reynolds J, Rakers C, Zeug A, Petzold GC, Rusakov DA, Henneberger C. Local Resting Ca 2+ Controls the Scale of Astroglial Ca 2+ Signals. Cell Rep 2020; 30:3466-3477.e4. [PMID: 32160550 PMCID: PMC7068654 DOI: 10.1016/j.celrep.2020.02.043] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/21/2019] [Accepted: 02/06/2020] [Indexed: 02/07/2023] Open
Abstract
Astroglia regulate neurovascular coupling while engaging in signal exchange with neurons. The underlying cellular machinery is thought to rely on astrocytic Ca2+ signals, but what controls their amplitude and waveform is poorly understood. Here, we employ time-resolved two-photon excitation fluorescence imaging in acute hippocampal slices and in cortex in vivo to find that resting [Ca2+] predicts the scale (amplitude) and the maximum (peak) of astroglial Ca2+ elevations. We bidirectionally manipulate resting [Ca2+] by uncaging intracellular Ca2+ or Ca2+ buffers and use ratiometric imaging of a genetically encoded Ca2+ indicator to establish that alterations in resting [Ca2+] change co-directionally the peak level and anti-directionally the amplitude of local Ca2+ transients. This relationship holds for spontaneous and for induced (for instance by locomotion) Ca2+ signals. Our findings uncover a basic generic rule of Ca2+ signal formation in astrocytes, thus also associating the resting Ca2+ level with the physiological "excitability" state of astroglia.
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Affiliation(s)
- Claire M King
- Institute of Neurology, University College London, London, UK
| | - Kirsten Bohmbach
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Daniel Minge
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Andrea Delekate
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Kaiyu Zheng
- Institute of Neurology, University College London, London, UK
| | - James Reynolds
- Institute of Neurology, University College London, London, UK
| | - Cordula Rakers
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany
| | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Gabor C Petzold
- German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany; Department of Neurology, University Hospital Bonn, Bonn, Germany
| | | | - Christian Henneberger
- Institute of Neurology, University College London, London, UK; Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany; German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.
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26
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Illes P, Burnstock G, Tang Y. Astroglia-Derived ATP Modulates CNS Neuronal Circuits. Trends Neurosci 2019; 42:885-898. [PMID: 31704181 DOI: 10.1016/j.tins.2019.09.006] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Revised: 09/10/2019] [Accepted: 09/23/2019] [Indexed: 02/08/2023]
Abstract
It is broadly recognized that ATP not only supports energy storage within cells but is also a transmitter/signaling molecule that serves intercellular communication. Whereas the fast (co)transmitter function of ATP in the peripheral nervous system has been convincingly documented, in the central nervous system (CNS) ATP appears to be primarily a slow transmitter/modulator. Data discussed in the present review suggest that the slow modulatory effects of ATP arise as a result of its vesicular/nonvesicular release from astrocytes. ATP acts together with other glial signaling molecules such as cytokines, chemokines, and free radicals to modulate neuronal circuits. Hence, astrocytes are positioned at the crossroads of the neuron-glia-neuron communication pathway.
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Affiliation(s)
- Peter Illes
- Rudolf Boehm Institute for Pharmacology and Toxicology, University of Leipzig, 04107 Leipzig, Germany; Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine (TCM), 610075 Chengdu, China.
| | - Geoffrey Burnstock
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, VIC 3010, Australia
| | - Yong Tang
- Acupuncture and Tuina School, Chengdu University of Traditional Chinese Medicine (TCM), 610075 Chengdu, China
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27
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Eilert-Olsen M, Hjukse JB, Thoren AE, Tang W, Enger R, Jensen V, Pettersen KH, Nagelhus EA. Astroglial endfeet exhibit distinct Ca 2+ signals during hypoosmotic conditions. Glia 2019; 67:2399-2409. [PMID: 31350866 DOI: 10.1002/glia.23692] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2019] [Revised: 07/12/2019] [Accepted: 07/16/2019] [Indexed: 11/09/2022]
Abstract
Astrocytic endfeet cover the brain surface and form a sheath around the cerebral vasculature. An emerging concept is that endfeet control blood-brain water transport and drainage of interstitial fluid and waste along paravascular pathways. Little is known about the signaling mechanisms that regulate endfoot volume and hence the width of these drainage pathways. Here, we used the genetically encoded fluorescent Ca2+ indicator GCaMP6f to study Ca2+ signaling within astrocytic somata, processes, and endfeet in response to an osmotic challenge known to induce cell swelling. Acute cortical slices were subjected to artificial cerebrospinal fluid with 20% reduction in osmolarity while GCaMP6f fluorescence was imaged with two-photon microscopy. Ca2+ signals induced by hypoosmotic conditions were observed in all astrocytic compartments except the soma. The Ca2+ response was most prominent in subpial and perivascular endfeet and included spikes with single peaks, plateau-type elevations, and rapid oscillations, the latter restricted to subpial endfeet. Genetic removal of the type 2 inositol 1,4,5-triphosphate receptor (IP3R2) severely suppressed the Ca2+ responses in endfeet but failed to affect brain water accumulation in vivo after water intoxication. Furthermore, the increase in endfoot Ca2+ spike rate during hypoosmotic conditions was attenuated in mutant mice lacking the aquaporin-4 anchoring molecule dystrophin and after blockage of transient receptor potential vanilloid 4 channels. We conclude that the characteristics and underpinning of Ca2+ responses to hypoosmotic stress differ within the astrocytic territory and that IP3R2 is essential for the Ca2+ signals only in subpial and perivascular endfeet.
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Affiliation(s)
- Martine Eilert-Olsen
- Division of Physiology, Department of Molecular Medicine, GliaLab and Letten Centre, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Jarand B Hjukse
- Division of Physiology, Department of Molecular Medicine, GliaLab and Letten Centre, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Anna E Thoren
- Division of Physiology, Department of Molecular Medicine, GliaLab and Letten Centre, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Wannan Tang
- Division of Physiology, Department of Molecular Medicine, GliaLab and Letten Centre, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Rune Enger
- Division of Physiology, Department of Molecular Medicine, GliaLab and Letten Centre, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Department of Neurology, Oslo University Hospital, Oslo, Norway
| | - Vidar Jensen
- Division of Physiology, Department of Molecular Medicine, GliaLab and Letten Centre, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Klas H Pettersen
- Division of Physiology, Department of Molecular Medicine, GliaLab and Letten Centre, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Erlend A Nagelhus
- Division of Physiology, Department of Molecular Medicine, GliaLab and Letten Centre, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Department of Neurology, Oslo University Hospital, Oslo, Norway
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28
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Smith NA, Bekar LK, Nedergaard M. Astrocytic Endocannabinoids Mediate Hippocampal Transient Heterosynaptic Depression. Neurochem Res 2019; 45:100-108. [PMID: 31254249 DOI: 10.1007/s11064-019-02834-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/14/2019] [Accepted: 06/20/2019] [Indexed: 12/29/2022]
Abstract
Astrocytes are highly dynamic cells that modulate synaptic transmission within a temporal domain of seconds to minutes in physiological contexts such as Long-Term Potentiation (LTP) and Heterosynaptic Depression (HSD). Recent studies have revealed that astrocytes also modulate a faster form of synaptic activity (milliseconds to seconds) known as Transient Heterosynaptic Depression (tHSD). However, the mechanism underlying astrocytic modulation of tHSD is not fully understood. Are the traditional gliotransmitters ATP or glutamate released via hemichannels/vesicles or are other, yet, unexplored pathways involved? Using various approaches to manipulate astrocytes, including the Krebs cycle inhibitor fluoroacetate, connexin 43/30 double knockout mice (hemichannels), and inositol triphosphate type-2 receptor knockout mice, we confirmed early reports demonstrating that astrocytes are critical for tHSD. We also confirmed the importance of group II metabotropic glutamate receptors (mGluRs) in astrocytic modulation of tHSD using a group II agonist. Using dominant negative SNARE mice, which have disrupted glial vesicle function, we also found that vesicular release of gliotransmitters and activation of adenosine A1 receptors are not required for tHSD. As astrocytes can release lipids upon receptor stimulation, we asked if astrocyte-derived endocannabinoids are involved in tHSD. Interestingly, a cannabinoid receptor 1 (CB1R) antagonist blocked and an inhibitor of the endogenous endocannabinoid 2-arachidonyl glycerol (2-AG) degradation potentiates tHSD in hippocampal slices. Taken together, this study provides the first evidence for group II mGluR-mediated astrocytic endocannabinoids in transiently suppressing presynaptic neurotransmitter release associated with the phenomenon of tHSD.
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Affiliation(s)
- Nathan A Smith
- Division of Glia Disease and Therapeutics, Dept. of Neurosurgery, Center for Translational Neuromedicine, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA.
- Center for Neuroscience, Children's Research Institute, Children's National Medical Center, 111 Michigan Ave, Washington, NW, 20010, USA.
- George Washington University School of Medicine and Health Sciences, Washington, DC, 20052, USA.
| | - Lane K Bekar
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Maiken Nedergaard
- Division of Glia Disease and Therapeutics, Dept. of Neurosurgery, Center for Translational Neuromedicine, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA
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29
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Okubo Y, Iino M. Visualization of astrocytic intracellular Ca 2+ mobilization. J Physiol 2019; 598:1671-1681. [PMID: 30825213 DOI: 10.1113/jp277609] [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: 12/25/2018] [Accepted: 02/06/2019] [Indexed: 11/08/2022] Open
Abstract
Astrocytes generate robust intracellular Ca2+ concentration changes (Ca2+ signals), which are assumed to regulate astrocytic functions that play crucial roles in the regulation of brain functions. One frequently used strategy for exploring the role of astrocytic Ca2+ signalling is the use of mice deficient in the type 2 inositol 1,4,5-trisphosphate receptor (IP3 R2). These IP3 R2-knockout (KO) mice are reportedly devoid of Ca2+ mobilization from the endoplasmic reticulum (ER) in astrocytes. However, they have shown no functional deficits in several studies, causing a heated debate as to the functional relevance of ER-mediated Ca2+ signalling in astrocytes. Recently, the assumption that Ca2+ mobilization from the ER is absent in IP3 R2-KO astrocytes has been re-evaluated using intraorganellar Ca2+ imaging techniques. The new results indicated that IP3 R2-independent Ca2+ release may generate Ca2+ nanodomains around the ER, which may help explain the absence of functional deficits in IP3 R2-KO mice.
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Affiliation(s)
- Yohei Okubo
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, 133-0033, Japan
| | - Masamitsu Iino
- Division of Cellular and Molecular Pharmacology, Nihon University School of Medicine, Tokyo, 173-8610, Japan
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30
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Reynolds JP, Zheng K, Rusakov DA. Multiplexed calcium imaging of single-synapse activity and astroglial responses in the intact brain. Neurosci Lett 2019; 689:26-32. [PMID: 29908948 PMCID: PMC6335263 DOI: 10.1016/j.neulet.2018.06.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Revised: 06/11/2018] [Accepted: 06/13/2018] [Indexed: 10/28/2022]
Abstract
All-optical registration of neuronal and astrocytic activities within the intact mammalian brain has improved significantly with recent advances in optical sensors and biophotonics. However, relating single-synapse release events and local astroglial responses to sensory stimuli in an intact animal has not hitherto been feasible. Here, we present a multiplexed multiphoton excitation imaging approach for assessing the relationship between presynaptic Ca2+ entry at thalamocortical axonal boutons and perisynaptic astrocytic Ca2+ elevations, induced by whisker stimulation in the barrel cortex of C57BL/6 mice. We find that, unexpectedly, Ca2+ elevations in the perisynaptic astrocytic regions consistently precede local presynaptic Ca2+ signals during spontaneous brain activity associated with anaesthesia. The methods described here can be adapted to a variety of optical sensors and are compatible with experimental designs that might necessitate repeated sampling of single synapses over a longitudinal behavioural paradigm.
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Affiliation(s)
- James P Reynolds
- UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
| | - Kaiyu Zheng
- UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK
| | - Dmitri A Rusakov
- UCL Institute of Neurology, University College London, Queen Square, London WC1N 3BG, UK.
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31
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Scofield MD. Exploring the Role of Astroglial Glutamate Release and Association With Synapses in Neuronal Function and Behavior. Biol Psychiatry 2018; 84:778-786. [PMID: 29258653 PMCID: PMC5948108 DOI: 10.1016/j.biopsych.2017.10.029] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Revised: 10/18/2017] [Accepted: 10/31/2017] [Indexed: 12/25/2022]
Abstract
Astrocytes are stellate cells whose appearance can resemble a pointed star, especially when visualizing glial fibrillary acidic protein, a canonical marker for astrocytes. Accordingly, there is a commonly made connection between the points of light that shine in the night sky and the diffuse and abundant cells that buffer ions and provide support for neurons. An exceptional amount of function has been attributed to, negated for, and potentially reaffirmed for these cells, especially regarding their ability to release neuroactive molecules and influence synaptic plasticity. This makes the precise role of astrocytes in tuning neural communication seem difficult to grasp. However, data from animal models of addiction demonstrate that a variety of drug-induced molecular adaptations responsible for relapse vulnerability take place in astrocyte systems that regulate glutamate uptake and release. These findings highlight astrocytes as a critical component of the neural systems responsible for addiction, serving as a key component of the plasticity responsible for relapse and drug seeking. Here I assemble recent findings that utilize genetic tools to selectively manipulate or measure flux of internal calcium in astrocytes, focusing on G protein-coupled receptor-mediated mobilization of calcium and the induction of glutamate release. Further, I compile evidence regarding astrocyte glutamate release as well as astrocyte association with synapses with respect to the impact of these cellular phenomena in shaping synaptic transmission. I also place these findings in the context of the previous studies of Scofield et al., who explored the role of astrocytes in the nucleus accumbens in the neural mechanisms underlying cocaine seeking.
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Affiliation(s)
- Michael D. Scofield
- Department of Anesthesiology and Perioperative Medicine, Medical University of South Carolina, Charleston, SC, 29425 USA,Department of Neuroscience, Medical University of South Carolina, Charleston, SC, 29425 USA
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32
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Conditional Knock-out of mGluR5 from Astrocytes during Epilepsy Development Impairs High-Frequency Glutamate Uptake. J Neurosci 2018; 39:727-742. [PMID: 30504280 DOI: 10.1523/jneurosci.1148-18.2018] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 11/11/2018] [Accepted: 11/18/2018] [Indexed: 11/21/2022] Open
Abstract
Astrocyte expression of metabotropic glutamate receptor 5 (mGluR5) is consistently observed in resected tissue from patients with epilepsy and is equally prevalent in animal models of epilepsy. However, little is known about the functional signaling properties or downstream consequences of astrocyte mGluR5 activation during epilepsy development. In the rodent brain, astrocyte mGluR5 expression is developmentally regulated and confined in expression/function to the first weeks of life, with similar observations made in human control tissue. Herein, we demonstrate that mGluR5 expression and function dramatically increase in a mouse model of temporal lobe epilepsy. Interestingly, in both male and female mice, mGluR5 function persists in the astrocyte throughout the process of epileptogenesis following status epilepticus. However, mGluR5 expression and function are transient in animals that do not develop epilepsy over an equivalent time period, suggesting that patterns of mGluR5 expression may signify continuing epilepsy development or its resolution. We demonstrate that, during epileptogenesis, astrocytes reacquire mGluR5-dependent calcium transients following agonist application or synaptic glutamate release, a feature of astrocyte-neuron communication absent since early development. Finally, we find that the selective and conditional knock-out of mGluR5 signaling from astrocytes during epilepsy development slows the rate of glutamate clearance through astrocyte glutamate transporters under high-frequency stimulation conditions, a feature that suggests astrocyte mGluR5 expression during epileptogenesis may recapitulate earlier developmental roles in regulating glutamate transporter function.SIGNIFICANCE STATEMENT In development, astrocyte mGluR5 signaling plays a critical role in regulating structural and functional interactions between astrocytes and neurons at the tripartite synapse. Notably, mGluR5 signaling is a positive regulator of astrocyte glutamate transporter expression and function, an essential component of excitatory signaling regulation in hippocampus. After early development, astrocyte mGluR5 expression is downregulated, but reemerges in animal models of temporal lobe epilepsy (TLE) development and patient epilepsy samples. We explored the hypothesis that astrocyte mGluR5 reemergence recapitulates earlier developmental roles during TLE acquisition. Our work demonstrates that astrocytes with mGluR5 signaling during TLE development perform faster glutamate uptake in hippocampus, revealing a previously unexplored role for astrocyte mGluR5 signaling in hypersynchronous pathology.
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Balakrishnan S, Mironov SL. Regenerative glutamate release in the hippocampus of Rett syndrome model mice. PLoS One 2018; 13:e0202802. [PMID: 30256804 PMCID: PMC6157837 DOI: 10.1371/journal.pone.0202802] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 08/09/2018] [Indexed: 11/18/2022] Open
Abstract
Excess glutamate during intense neuronal activity is not instantly cleared and may accumulate in the extracellular space. This has various long-term consequences such as ectopic signaling, modulation of synaptic efficacy and excitotoxicity; the latter implicated in various neurodevelopmental and neurodegenerative diseases. In this study, the quantitative imaging of glutamate homeostasis of hippocampal slices from methyl-CpG binding protein 2 knock-out (Mecp2-/y) mice, a model of Rett syndrome (RTT), revealed unusual repetitive glutamate transients. They appeared in phase with bursts of action potentials in the CA1 neurons. Both glutamate transients and bursting activity were suppressed by the blockade of sodium, AMPA and voltage-gated calcium channels (T- and R-type), and enhanced after the inhibition of HCN channels. HCN and calcium channels in RTT and wild-type (WT) CA1 neurons displayed different voltage-dependencies and kinetics. Both channels modulated postsynaptic integration and modified the pattern of glutamate spikes in the RTT hippocampus. Spontaneous glutamate transients were much less abundant in the WT preparations, and, when observed, had smaller amplitude and frequency. The basal ambient glutamate levels in RTT were higher and transient glutamate increases (spontaneous and evoked by stimulation of Schaffer collaterals) decayed slower. Both features indicate less efficient glutamate uptake in RTT. To explain the generation of repetitive glutamate spikes, we designed a novel model of glutamate-induced glutamate release. The simulations correctly predicted the patterns of spontaneous glutamate spikes observed under different experimental conditions. We propose that pervasive spontaneous glutamate release is a hallmark of Mecp2-/y hippocampus, stemming from and modulating the hyperexcitability of neurons.
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Affiliation(s)
- Saju Balakrishnan
- CNMPB (Centre for Nanoscale Microscopy and Molecular Physiology of the Brain, DFG Research Center 103), Institute of Neuro and Sensory Physiology, Georg-August-University, Göttingen, Germany
| | - Sergej L. Mironov
- CNMPB (Centre for Nanoscale Microscopy and Molecular Physiology of the Brain, DFG Research Center 103), Institute of Neuro and Sensory Physiology, Georg-August-University, Göttingen, Germany
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34
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Hudry E, Andres-Mateos E, Lerner EP, Volak A, Cohen O, Hyman BT, Maguire CA, Vandenberghe LH. Efficient Gene Transfer to the Central Nervous System by Single-Stranded Anc80L65. Mol Ther Methods Clin Dev 2018; 10:197-209. [PMID: 30109242 PMCID: PMC6083902 DOI: 10.1016/j.omtm.2018.07.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 07/10/2018] [Indexed: 12/27/2022]
Abstract
Adeno-associated viral vectors (AAVs) have demonstrated potential in applications for neurologic disorders, and the discovery that some AAVs can cross the blood-brain barrier (BBB) after intravenous injection has further expanded these opportunities for non-invasive brain delivery. Anc80L65, a novel AAV capsid designed from in silico reconstruction of the viral evolutionary lineage, has previously demonstrated robust transduction capabilities after local delivery in various tissues such as liver, retina, or cochlea, compared with conventional AAVs. Here, we compared the transduction efficacy of Anc80L65 with conventional AAV9 in the CNS after intravenous, intracerebroventricular (i.c.v.), or intraparenchymal injections. Anc80L65 was more potent at targeting the brain and spinal cord after intravenous injection than AAV9, and mostly transduced astrocytes and a wide range of neuronal subpopulations. Although the efficacy of Anc80L65 and AAV9 is similar after direct intraparenchymal injection in the striatum, Anc80L65's diffusion throughout the CNS was more extensive than AAV9 after i.c.v. infusion, leading to widespread EGFP expression in the cerebellum. These findings demonstrate that Anc80L65 is a highly efficient gene transfer vector for the murine CNS. Systemic injection of Anc80L65 leads to notable expression in the CNS that does not rely on a self-complementary genome. These data warrant further testing in larger animal models.
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Affiliation(s)
- Eloise Hudry
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Eva Andres-Mateos
- Grousbeck Gene Therapy Center, Schepens Eye Research Institute and Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA
- Ocular Genomics Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
| | - Eli P. Lerner
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Adrienn Volak
- Department of Neurology, The Massachusetts General Hospital and NeuroDiscovery Center, Harvard Medical School, Boston, MA 02114, USA
| | - Olivia Cohen
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Bradley T. Hyman
- MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA 02129, USA
| | - Casey A. Maguire
- Department of Neurology, The Massachusetts General Hospital and NeuroDiscovery Center, Harvard Medical School, Boston, MA 02114, USA
| | - Luk H. Vandenberghe
- Grousbeck Gene Therapy Center, Schepens Eye Research Institute and Massachusetts Eye and Ear Infirmary, Boston, MA 02114, USA
- Ocular Genomics Institute, Department of Ophthalmology, Harvard Medical School, Boston, MA 02114, USA
- Harvard Stem Cell Institute, Harvard University, Cambridge, MA 02138, USA
- The Broad Institute of Harvard and MIT, Cambridge, MA 02142, USA
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35
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Stobart JL, Ferrari KD, Barrett MJP, Stobart MJ, Looser ZJ, Saab AS, Weber B. Long-term In Vivo Calcium Imaging of Astrocytes Reveals Distinct Cellular Compartment Responses to Sensory Stimulation. Cereb Cortex 2018; 28:184-198. [PMID: 28968832 DOI: 10.1093/cercor/bhw366] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/02/2016] [Indexed: 01/28/2023] Open
Abstract
Localized, heterogeneous calcium transients occur throughout astrocytes, but the characteristics and long-term stability of these signals, particularly in response to sensory stimulation, remain unknown. Here, we used a genetically encoded calcium indicator and an activity-based image analysis scheme to monitor astrocyte calcium activity in vivo. We found that different subcellular compartments (processes, somata, and endfeet) displayed distinct signaling characteristics. Closer examination of individual signals showed that sensory stimulation elevated the number of specific types of calcium peaks within astrocyte processes and somata, in a cortical layer-dependent manner, and that the signals became more synchronous upon sensory stimulation. Although mice genetically lacking astrocytic IP3R-dependent calcium signaling (Ip3r2-/-) had fewer signal peaks, the response to sensory stimulation was sustained, suggesting other calcium pathways are also involved. Long-term imaging of astrocyte populations revealed that all compartments reliably responded to stimulation over several months, but that the location of the response within processes may vary. These previously unknown characteristics of subcellular astrocyte calcium signals provide new insights into how astrocytes may encode local neuronal circuit activity.
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Affiliation(s)
- Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Matthew J P Barrett
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Michael J Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Zoe J Looser
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
| | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, CH-8057 Zurich, Switzerland.,Neuroscience Center, University and ETH Zurich, CH-8057 Zurich, Switzerland
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36
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Role of Purinergic Receptor P2Y1 in Spatiotemporal Ca 2+ Dynamics in Astrocytes. J Neurosci 2018; 38:1383-1395. [PMID: 29305530 DOI: 10.1523/jneurosci.2625-17.2017] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/06/2017] [Accepted: 12/18/2017] [Indexed: 01/08/2023] Open
Abstract
Fine processes of astrocytes enwrap synapses and are well positioned to sense neuronal information via synaptic transmission. In rodents, astrocyte processes sense synaptic transmission via Gq-protein coupled receptors (GqPCR), including the P2Y1 receptor (P2Y1R), to generate Ca2+ signals. Astrocytes display numerous spontaneous microdomain Ca2+ signals; however, it is not clear whether such signals are due to local synaptic transmission and/or in what timeframe astrocytes sense local synaptic transmission. To ask whether GqPCRs mediate microdomain Ca2+ signals, we engineered mice (both sexes) to specifically overexpress P2Y1Rs in astrocytes, and we visualized Ca2+ signals via a genetically encoded Ca2+ indicator, GCaMP6f, in astrocytes from adult mice. Astrocytes overexpressing P2Y1Rs showed significantly larger Ca2+ signals in response to exogenously applied ligand and to repetitive electrical stimulation of axons compared with controls. However, we found no evidence of increased microdomain Ca2+ signals. Instead, Ca2+ waves appeared and propagated to occupy areas that were up to 80-fold larger than microdomain Ca2+ signals. These Ca2+ waves accounted for only 2% of total Ca2+ events, but they were 1.9-fold larger and 2.9-fold longer in duration than microdomain Ca2+ signals at processes. Ca2+ waves did not require action potentials for their generation and occurred in a probenecid-sensitive manner, indicating that the endogenous ligand for P2Y1R is elevated independently of synaptic transmission. Our data suggest that spontaneous microdomain Ca2+ signals occur independently of P2Y1R activation and that astrocytes may not encode neuronal information in response to synaptic transmission at a point source of neurotransmitter release.SIGNIFICANCE STATEMENT Astrocytes are thought to enwrap synapses with their processes to receive neuronal information via Gq-protein coupled receptors (GqPCRs). Astrocyte processes display numerous microdomain Ca2+ signals that occur spontaneously. To determine whether GqPCRs play a role in microdomain Ca2+ signals and the timeframe in which astrocytes sense neuronal information, we engineered mice whose astrocytes specifically overexpress the P2Y1 receptor, a major GqPCR in astrocytes. We found that overexpression of P2Y1 receptors in astrocytes did not increase microdomain Ca2+ signals in astrocyte processes but caused Ca2+ wavelike signals. Our data indicate that spontaneous microdomain Ca2+ signals do not require activation of P2Y1 receptors.
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37
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Taheri M, Handy G, Borisyuk A, White JA. Diversity of Evoked Astrocyte Ca 2+ Dynamics Quantified through Experimental Measurements and Mathematical Modeling. Front Syst Neurosci 2017; 11:79. [PMID: 29109680 PMCID: PMC5660282 DOI: 10.3389/fnsys.2017.00079] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/04/2017] [Indexed: 01/06/2023] Open
Abstract
Astrocytes are a major cell type in the mammalian brain. They are not electrically excitable, but generate prominent Ca2+ signals related to a wide variety of critical functions. The mechanisms driving these Ca2+ events remain incompletely understood. In this study, we integrate Ca2+ imaging, quantitative data analysis, and mechanistic computational modeling to study the spatial and temporal heterogeneity of cortical astrocyte Ca2+ transients evoked by focal application of ATP in mouse brain slices. Based on experimental results, we tune a single-compartment mathematical model of IP3-dependent Ca2+ responses in astrocytes and use that model to study response heterogeneity. Using information from the experimental data and the underlying bifurcation structure of our mathematical model, we categorize all astrocyte Ca2+ responses into four general types based on their temporal characteristics: Single-Peak, Multi-Peak, Plateau, and Long-Lasting responses. We find that the distribution of experimentally-recorded response types depends on the location within an astrocyte, with somatic responses dominated by Single-Peak (SP) responses and large and small processes generating more Multi-Peak responses. On the other hand, response kinetics differ more between cells and trials than with location within a given astrocyte. We use the computational model to elucidate possible sources of Ca2+ response variability: (1) temporal dynamics of IP3, and (2) relative flux rates through Ca2+ channels and pumps. Our model also predicts the effects of blocking Ca2+ channels/pumps; for example, blocking store-operated Ca2+ (SOC) channels in the model eliminates Plateau and Long-Lasting responses (consistent with previous experimental observations). Finally, we propose that observed differences in response type distributions between astrocyte somas and processes can be attributed to systematic differences in IP3 rise durations and Ca2+ flux rates.
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Affiliation(s)
- Marsa Taheri
- Department of Bioengineering, University of Utah, Salt Lake City, UT, United States
| | - Gregory Handy
- Department of Mathematics, University of Utah, Salt Lake City, UT, United States
| | - Alla Borisyuk
- Department of Mathematics, University of Utah, Salt Lake City, UT, United States
| | - John A White
- Department of Biomedical Engineering, Boston University, Boston, MA, United States
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38
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Oheim M, Schmidt E, Hirrlinger J. Local energy on demand: Are 'spontaneous' astrocytic Ca 2+-microdomains the regulatory unit for astrocyte-neuron metabolic cooperation? Brain Res Bull 2017; 136:54-64. [PMID: 28450076 DOI: 10.1016/j.brainresbull.2017.04.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/18/2017] [Accepted: 04/21/2017] [Indexed: 12/21/2022]
Abstract
Astrocytes are a neural cell type critically involved in maintaining brain energy homeostasis as well as signaling. Like neurons, astrocytes are a heterogeneous cell population. Cortical astrocytes show a complex morphology with a highly branched aborization and numerous fine processes ensheathing the synapses of neighboring neurons, and typically extend one process connecting to blood vessels. Recent studies employing genetically encoded fluorescent calcium (Ca2+) indicators have described 'spontaneous' localized Ca2+-transients in the astrocyte periphery that occur asynchronously, independently of signals in other parts of the cells, and that do not involve somatic Ca2+ transients; however, neither it is known whether these Ca2+-microdomains occur at or near neuronal synapses nor have their molecular basis nor downstream effector(s) been identified. In addition to Ca2+ microdomains, sodium (Na+) transients occur in astrocyte subdomains, too, most likely as a consequence of Na+ co-transport with the neurotransmitter glutamate, which also regulates mitochondrial movements locally - as do cytoplasmic Ca2+ levels. In this review, we cover various aspects of these local signaling events and discuss how structural and biophysical properties of astrocytes might foster such compartmentation. Astrocytes metabolically interact with neurons by providing energy substrates to active neurons. As a single astrocyte branch covers hundreds to thousands of synapses, it is tempting to speculate that these metabolic interactions could occur localized to specific subdomains of astrocytes, perhaps even at the level of small groups of synapses. We discuss how astrocytic metabolism might be regulated at this scale and which signals might contribute to its regulation. We speculate that the astrocytic structures that light up transiently as Ca2+-microdomains might be the functional units of astrocytes linking signaling and metabolic processes to adapt astrocytic function to local energy demands. The understanding of these local regulatory and metabolic interactions will be fundamental to fully appreciate the complexity of brain energy homeostasis as well as its failure in disease and may shed new light on the controversy about neuron-glia bi-directional signaling at the tripartite synapse.
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Affiliation(s)
- Martin Oheim
- CNRS UMR 8118, Brain Physiology Laboratory, F-75006 Paris, France; Fédération de Recherche en Neurosciences FR3636, Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Université Sorbonne Paris Cité (USPC), F-75006 Paris, France.
| | - Elke Schmidt
- CNRS UMR 8118, Brain Physiology Laboratory, F-75006 Paris, France; Fédération de Recherche en Neurosciences FR3636, Faculté de Sciences Fondamentales et Biomédicales, Université Paris Descartes, PRES Université Sorbonne Paris Cité (USPC), F-75006 Paris, France
| | - Johannes Hirrlinger
- Carl-Ludwig-Institute for Physiology, Faculty of Medicine, University of Leipzig, D-04103 Leipzig, Germany; Dept. of Neurogenetics, Max-Planck-Institute for Experimental Medicine, D-37075 Göttingen, Germany.
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39
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Translation in astrocyte distal processes sets molecular heterogeneity at the gliovascular interface. Cell Discov 2017; 3:17005. [PMID: 28377822 PMCID: PMC5368712 DOI: 10.1038/celldisc.2017.5] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 01/10/2017] [Indexed: 12/26/2022] Open
Abstract
Astrocytes send out long processes that are terminated by endfeet at the vascular surface and regulate vascular functions as well as homeostasis at the vascular interface. To date, the astroglial mechanisms underlying these functions have been poorly addressed. Here we demonstrate that a subset of messenger RNAs is distributed in astrocyte endfeet. We identified, among this transcriptome, a pool of messenger RNAs bound to ribosomes, the endfeetome, that primarily encodes for secreted and membrane proteins. We detected nascent protein synthesis in astrocyte endfeet. Finally, we determined the presence of smooth and rough endoplasmic reticulum and the Golgi apparatus in astrocyte perivascular processes and endfeet, suggesting for local maturation of membrane and secreted proteins. These results demonstrate for the first time that protein synthesis occurs in astrocyte perivascular distal processes that may sustain their structural and functional polarization at the vascular interface.
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40
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Gómez-Gonzalo M, Martin-Fernandez M, Martínez-Murillo R, Mederos S, Hernández-Vivanco A, Jamison S, Fernandez AP, Serrano J, Calero P, Futch HS, Corpas R, Sanfeliu C, Perea G, Araque A. Neuron-astrocyte signaling is preserved in the aging brain. Glia 2017; 65:569-580. [PMID: 28130845 DOI: 10.1002/glia.23112] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Revised: 11/23/2016] [Accepted: 12/21/2016] [Indexed: 12/18/2022]
Abstract
Astrocytes play crucial roles in brain homeostasis and are emerging as regulatory elements of neuronal and synaptic physiology by responding to neurotransmitters with Ca2+ elevations and releasing gliotransmitters that activate neuronal receptors. Aging involves neuronal and astrocytic alterations, being considered risk factor for neurodegenerative diseases. Most evidence of the astrocyte-neuron signaling is derived from studies with young animals; however, the features of astrocyte-neuron signaling in adult and aging brain remain largely unknown. We have investigated the existence and properties of astrocyte-neuron signaling in physiologically and pathologically aging mouse hippocampal and cortical slices at different lifetime points (0.5 to 20 month-old animals). We found that astrocytes preserved their ability to express spontaneous and neurotransmitter-dependent intracellular Ca2+ signals from juvenile to aging brains. Likewise, resting levels of gliotransmission, assessed by neuronal NMDAR activation by glutamate released from astrocytes, were largely preserved with similar properties in all tested age groups, but DHPG-induced gliotransmission was reduced in aged mice. In contrast, gliotransmission was enhanced in the APP/PS1 mouse model of Alzheimer's disease, indicating a dysregulation of astrocyte-neuron signaling in pathological conditions. Disruption of the astrocytic IP3 R2 mediated-signaling, which is required for neurotransmitter-induced astrocyte Ca2+ signals and gliotransmission, boosted the progression of amyloid plaque deposits and synaptic plasticity impairments in APP/PS1 mice at early stages of the disease. Therefore, astrocyte-neuron interaction is a fundamental signaling, largely conserved in the adult and aging brain of healthy animals, but it is altered in Alzheimer's disease, suggesting that dysfunctions of astrocyte Ca2+ physiology may contribute to this neurodegenerative disease. GLIA 2017 GLIA 2017;65:569-580.
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Affiliation(s)
| | | | | | | | | | - Stephanie Jamison
- Department of Neuroscience, University of Minnesota, Minneapolis, 55455
| | | | | | | | - Hunter S Futch
- College of Medicine, University of Florida, Gainesville, Florida, 32610-0261
| | - Rubén Corpas
- Aging and Neurodegeneration Unit, Biomedical Research Institute of Barcelona (IIBB), CSIC and IDIBAPS, Barcelona, 08036, Spain
| | - Coral Sanfeliu
- Aging and Neurodegeneration Unit, Biomedical Research Institute of Barcelona (IIBB), CSIC and IDIBAPS, Barcelona, 08036, Spain
| | | | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, 55455
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Xu H, Zhang H, Zhang J, Huang Q, Shen Z, Wu R. Evaluation of neuron-glia integrity by in vivo proton magnetic resonance spectroscopy: Implications for psychiatric disorders. Neurosci Biobehav Rev 2016; 71:563-577. [PMID: 27702600 DOI: 10.1016/j.neubiorev.2016.09.027] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Revised: 09/18/2016] [Accepted: 09/26/2016] [Indexed: 02/05/2023]
Abstract
Proton magnetic resonance spectroscopy (1H-MRS) has been widely applied in human studies. There is now a large literature describing findings of brain MRS studies with mental disorder patients including schizophrenia, bipolar disorder, major depressive disorder, and anxiety disorders. However, the findings are mixed and cannot be reconciled by any of the existing interpretations. Here we proposed the new theory of neuron-glia integrity to explain the findings of brain 1H-MRS stuies. It proposed the neurochemical correlates of neuron-astrocyte integrity and axon-myelin integrity on the basis of update of neurobiological knowledge about neuron-glia communication and of experimental MRS evidence for impairments in neuron-glia integrity from the authors and the other investigators. Following the neuron-glia integrity theories, this review collected evidence showing that glutamate/glutamine change is a good marker for impaired neuron-astrocyte integrity and that changes in N-acetylaspartate and lipid precursors reflect impaired myelination. Moreover, this new theory enables us to explain the differences between MRS findings in neuropsychiatric and neurodegenerative disorders.
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Affiliation(s)
- Haiyun Xu
- The Mental Health Center, Shantou University Medical College, China.
| | - Handi Zhang
- The Mental Health Center, Shantou University Medical College, China
| | - Jie Zhang
- The Mental Health Center, Shantou University Medical College, China
| | - Qingjun Huang
- The Mental Health Center, Shantou University Medical College, China
| | - Zhiwei Shen
- The Department of Radiology, the second affiliated hospital, Shantou University Medical College, China
| | - Renhua Wu
- The Department of Radiology, the second affiliated hospital, Shantou University Medical College, China
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42
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Bazargani N, Attwell D. Astrocyte calcium signaling: the third wave. Nat Neurosci 2016; 19:182-9. [PMID: 26814587 DOI: 10.1038/nn.4201] [Citation(s) in RCA: 567] [Impact Index Per Article: 70.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 11/10/2015] [Indexed: 02/06/2023]
Abstract
The discovery that transient elevations of calcium concentration occur in astrocytes, and release 'gliotransmitters' which act on neurons and vascular smooth muscle, led to the idea that astrocytes are powerful regulators of neuronal spiking, synaptic plasticity and brain blood flow. These findings were challenged by a second wave of reports that astrocyte calcium transients did not mediate functions attributed to gliotransmitters and were too slow to generate blood flow increases. Remarkably, the tide has now turned again: the most important calcium transients occur in fine astrocyte processes not resolved in earlier studies, and new mechanisms have been discovered by which astrocyte [Ca(2+)]i is raised and exerts its effects. Here we review how this third wave of discoveries has changed our understanding of astrocyte calcium signaling and its consequences for neuronal function.
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Affiliation(s)
- Narges Bazargani
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
| | - David Attwell
- Department of Neuroscience, Physiology &Pharmacology, University College London, London, UK
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43
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Hudry E, Martin C, Gandhi S, György B, Scheffer DI, Mu D, Merkel SF, Mingozzi F, Fitzpatrick Z, Dimant H, Masek M, Ragan T, Tan S, Brisson AR, Ramirez SH, Hyman BT, Maguire CA. Exosome-associated AAV vector as a robust and convenient neuroscience tool. Gene Ther 2016; 23:380-92. [PMID: 26836117 PMCID: PMC4824662 DOI: 10.1038/gt.2016.11] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 01/17/2016] [Accepted: 01/19/2016] [Indexed: 12/18/2022]
Abstract
Adeno-associated virus (AAV) vectors are showing promise in gene therapy trials and have proven to be extremely efficient biological tools in basic neuroscience research. One major limitation to their widespread use in the neuroscience laboratory is the cost, labor, skill and time-intense purification process of AAV. We have recently shown that AAV can associate with exosomes (exo-AAV) when the vector is isolated from conditioned media of producer cells, and the exo-AAV is more resistant to neutralizing anti-AAV antibodies compared with standard AAV. Here, we demonstrate that simple pelleting of exo-AAV from media via ultracentrifugation results in high-titer vector preparations capable of efficient transduction of central nervous system (CNS) cells after systemic injection in mice. We observed that exo-AAV is more efficient at gene delivery to the brain at low vector doses relative to conventional AAV, even when derived from a serotype that does not normally efficiently cross the blood-brain barrier. Similar cell types were transduced by exo-AAV and conventionally purified vector. Importantly, no cellular toxicity was noted in exo-AAV-transduced cells. We demonstrated the utility and robustness of exo-AAV-mediated gene delivery by detecting direct GFP fluorescence after systemic injection, allowing three-dimensional reconstruction of transduced Purkinje cells in the cerebellum using ex vivo serial two-photon tomography. The ease of isolation combined with the high efficiency of transgene expression in the CNS, may enable the widespread use of exo-AAV as a neuroscience research tool. Furthermore, the ability of exo-AAV to evade neutralizing antibodies while still transducing CNS after peripheral delivery is clinically relevant.
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Affiliation(s)
- Eloise Hudry
- Alzheimer Research Unit, The Massachusetts General Hospital Institute for Neurodegenerative Disease, Charlestown, MA
- Department of Neurology, The Massachusetts General Hospital, and NeuroDiscovery Center, Harvard Medical School, Boston, USA
| | - Courtney Martin
- Alzheimer Research Unit, The Massachusetts General Hospital Institute for Neurodegenerative Disease, Charlestown, MA
- Department of Neurology, The Massachusetts General Hospital, and NeuroDiscovery Center, Harvard Medical School, Boston, USA
| | - Sheetal Gandhi
- Alzheimer Research Unit, The Massachusetts General Hospital Institute for Neurodegenerative Disease, Charlestown, MA
- Department of Neurology, The Massachusetts General Hospital, and NeuroDiscovery Center, Harvard Medical School, Boston, USA
| | - Bence György
- Department of Neurology, The Massachusetts General Hospital, and NeuroDiscovery Center, Harvard Medical School, Boston, USA
- Department of Neurobiology, Harvard Medical School, Boston, USA
| | | | - Dakai Mu
- Department of Neurology, The Massachusetts General Hospital, and NeuroDiscovery Center, Harvard Medical School, Boston, USA
| | - Steven F. Merkel
- Department of Pathology and Laboratory Medicine, Temple University School of Medicine, Philadelphia, PA
| | | | - Zachary Fitzpatrick
- Department of Neurology, The Massachusetts General Hospital, and NeuroDiscovery Center, Harvard Medical School, Boston, USA
| | | | | | | | - Sisareuth Tan
- UMR-CBMN CNRS-University of Bordeaux, Pessac, France
| | | | - Servio H. Ramirez
- Department of Pathology and Laboratory Medicine, Temple University School of Medicine, Philadelphia, PA
| | - Bradley T. Hyman
- Alzheimer Research Unit, The Massachusetts General Hospital Institute for Neurodegenerative Disease, Charlestown, MA
- Department of Neurology, The Massachusetts General Hospital, and NeuroDiscovery Center, Harvard Medical School, Boston, USA
| | - Casey A. Maguire
- Department of Neurology, The Massachusetts General Hospital, and NeuroDiscovery Center, Harvard Medical School, Boston, USA
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Shigetomi E, Patel S, Khakh BS. Probing the Complexities of Astrocyte Calcium Signaling. Trends Cell Biol 2016; 26:300-312. [PMID: 26896246 PMCID: PMC4946798 DOI: 10.1016/j.tcb.2016.01.003] [Citation(s) in RCA: 168] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2015] [Revised: 01/12/2016] [Accepted: 01/14/2016] [Indexed: 01/08/2023]
Abstract
Astrocytes are abundant glial cells that tile the entire central nervous system and mediate well-established functions for neurons, blood vessels, and other glia. These ubiquitous cells display intracellular Ca(2+) signals, which have been intensely studied for 25 years. Recently, the use of improved methods has unearthed the panoply of astrocyte Ca(2+) signals and a variable landscape of basal Ca(2+) levels. In vivo studies have started to reveal the settings under which astrocytes display behaviorally relevant Ca(2+) signaling. Studies in mice have emphasized how astrocyte Ca(2+) signaling is altered in distinct neurodegenerative diseases. Progress in the past few years, fueled by methodological advances, has thus reignited interest in astrocyte Ca(2+) signaling for brain function and dysfunction.
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Affiliation(s)
- Eiji Shigetomi
- Department of Neuropharmacology, Interdisciplinary Graduate School of Medicine, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi 409-3898, Japan
| | - Sandip Patel
- Department of Cell and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK
| | - Baljit S Khakh
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA; Department of Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA.
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Nakayama R, Sasaki T, Tanaka KF, Ikegaya Y. Subcellular calcium dynamics during juvenile development in mouse hippocampal astrocytes. Eur J Neurosci 2016; 43:923-32. [PMID: 27041234 DOI: 10.1111/ejn.13188] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 12/26/2015] [Accepted: 01/26/2016] [Indexed: 12/15/2022]
Abstract
Astrocytes generate calcium signals throughout their fine processes, which are assumed to locally regulate neighbouring neurotransmission and blood flow. The intercellular morphological relationships mature during juvenile periods when astrocytes elongate highly ramified processes. In this study, we examined developmental changes in calcium activity patterns of single hippocampal astrocytes using a transgenic mouse line in which astrocytes selectively express a genetically encoded calcium indicator, Yellow Cameleon-Nano50. Compared with postnatal day 7, astrocytes at postnatal day 30 showed larger subcellular calcium events and a greater proportion of somatic events. At both ages, the calcium activity was abolished by removal of extracellular calcium ions. Calcium events in late juvenile astrocytes were not affected by spontaneously occurring sharp waves that trigger synchronized neuronal spikes, implying the independence of astrocyte calcium signals from neuronal synchronization. These results demonstrate that astrocytes undergo dynamic changes in their activity patterns during juvenile development.
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Affiliation(s)
- Ryota Nakayama
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
| | - Takuya Sasaki
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan
| | - Kenji F Tanaka
- Department of Neuropsychiatry, School of Medicine, Keio University, Tokyo, Japan
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo, Japan.,Center for Information and Neural Networks, Osaka, Japan
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46
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Kimbrough IF, Robel S, Roberson ED, Sontheimer H. Vascular amyloidosis impairs the gliovascular unit in a mouse model of Alzheimer's disease. Brain 2015; 138:3716-33. [PMID: 26598495 PMCID: PMC5006220 DOI: 10.1093/brain/awv327] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 08/21/2015] [Accepted: 08/24/2015] [Indexed: 01/08/2023] Open
Abstract
Reduced cerebral blood flow impairs cognitive function and ultimately causes irreparable damage to brain tissue. The gliovascular unit, composed of neural and vascular cells, assures sufficient blood supply to active brain regions. Astrocytes, vascular smooth muscle cells, and pericytes are important players within the gliovascular unit modulating vessel diameters. While the importance of the gliovascular unit and the signals involved in regulating local blood flow to match neuronal activity is now well recognized, surprisingly little is known about this interface in disease. Alzheimer's disease is associated with reduced cerebral blood flow. Here, we studied how the gliovascular unit is affected in a mouse model of Alzheimer's disease, using a combination of ex vivo and in vivo imaging approaches. We specifically labelled vascular amyloid in living mice using the dye methoxy-XO4. We elicited vessel responses ex vivo using either pharmacological stimuli or cell-specific calcium uncaging in vascular smooth muscle cells or astrocytes. Multi-photon in vivo imaging through a cranial window allowed us to complement our ex vivo data in the presence of blood flow after label-free optical activation of vascular smooth muscle cells in the intact brain. We found that vascular amyloid deposits separated astrocyte end-feet from the endothelial vessel wall. High-resolution 3D images demonstrated that vascular amyloid developed in ring-like structures around the vessel circumference, essentially forming a rigid cast. Where vascular amyloid was present, stimulation of astrocytes or vascular smooth muscle cells via ex vivo Ca(2+) uncaging or in vivo optical activation produced only poor vascular responses. Strikingly, vessel segments that were unaffected by vascular amyloid responded to the same extent as vessels from age-matched control animals. We conclude that while astrocytes can still release vasoactive substances, vascular amyloid deposits render blood vessels rigid and reduce the dynamic range of affected vessel segments. These results demonstrate a mechanism that could account in part for the reduction in cerebral blood flow in patients with Alzheimer's disease.media-1vid110.1093/brain/awv327_video_abstractawv327_video_abstract.
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Affiliation(s)
- Ian F Kimbrough
- 1 Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA 2 Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Stefanie Robel
- 1 Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA 2 Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Erik D Roberson
- 1 Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA 3 Department of Neurology, University of Alabama at Birmingham, Birmingham, AL, USA 4 Center for Neurodegeneration and Experimental Therapeutics, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Harald Sontheimer
- 1 Department of Neurobiology, University of Alabama at Birmingham, Birmingham, AL, USA 2 Center for Glial Biology in Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
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Szokol K, Heuser K, Tang W, Jensen V, Enger R, Bedner P, Steinhäuser C, Taubøll E, Ottersen OP, Nagelhus EA. Augmentation of Ca(2+) signaling in astrocytic endfeet in the latent phase of temporal lobe epilepsy. Front Cell Neurosci 2015; 9:49. [PMID: 25762896 PMCID: PMC4340203 DOI: 10.3389/fncel.2015.00049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/01/2015] [Indexed: 11/13/2022] Open
Abstract
Astrocytic endfeet are specialized cell compartments whose important homeostatic roles depend on their enrichment of water and ion channels anchored by the dystrophin associated protein complex (DAPC). This protein complex is known to disassemble in patients with mesial temporal lobe epilepsy and in the latent phase of experimental epilepsies. The mechanistic underpinning of this disassembly is an obvious target of future therapies, but remains unresolved. Here we show in a kainate model of temporal lobe epilepsy that astrocytic endfeet display an enhanced stimulation-evoked Ca(2+) signal that outlast the Ca(2+) signal in the cell bodies. While the amplitude of this Ca(2+) signal is reduced following group I/II metabotropic receptor (mGluR) blockade, the duration is sustained. Based on previous studies it has been hypothesized that the molecular disassembly in astrocytic endfeet is caused by dystrophin cleavage mediated by Ca(2+) dependent proteases. Using a newly developed genetically encoded Ca(2+) sensor, the present study bolsters this hypothesis by demonstrating long-lasting, enhanced stimulation-evoked Ca(2+) signals in astrocytic endfeet.
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Affiliation(s)
- Karolina Szokol
- Department of Neurology, Oslo University Hospital Oslo, Norway ; Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Kjell Heuser
- Department of Neurology, Oslo University Hospital Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Wannan Tang
- Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Vidar Jensen
- Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Rune Enger
- Department of Neurology, Oslo University Hospital Oslo, Norway ; Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Peter Bedner
- Institute of Cellular Neurosciences, University of Bonn Bonn, Germany
| | | | - Erik Taubøll
- Department of Neurology, Oslo University Hospital Oslo, Norway
| | | | - Erlend A Nagelhus
- Department of Neurology, Oslo University Hospital Oslo, Norway ; Centre for Molecular Medicine Norway, The Nordic EMBL Partnership, University of Oslo Oslo, Norway ; Letten Centre and GliaLab, Department of Physiology, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
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48
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Mitterauer BJ. Self-Structuring of Motile Astrocytic Processes within the Network of a Single Astrocyte. ACTA ACUST UNITED AC 2015. [DOI: 10.4236/abb.2015.612074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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