151
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Caudal LC, Gobbo D, Scheller A, Kirchhoff F. The Paradox of Astroglial Ca 2 + Signals at the Interface of Excitation and Inhibition. Front Cell Neurosci 2020; 14:609947. [PMID: 33324169 PMCID: PMC7726216 DOI: 10.3389/fncel.2020.609947] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Accepted: 11/03/2020] [Indexed: 12/15/2022] Open
Abstract
Astroglial networks constitute a non-neuronal communication system in the brain and are acknowledged modulators of synaptic plasticity. A sophisticated set of transmitter receptors in combination with distinct secretion mechanisms enables astrocytes to sense and modulate synaptic transmission. This integrative function evolved around intracellular Ca2+ signals, by and large considered as the main indicator of astrocyte activity. Regular brain physiology meticulously relies on the constant reciprocity of excitation and inhibition (E/I). Astrocytes are metabolically, physically, and functionally associated to the E/I convergence. Metabolically, astrocytes provide glutamine, the precursor of both major neurotransmitters governing E/I in the central nervous system (CNS): glutamate and γ-aminobutyric acid (GABA). Perisynaptic astroglial processes are structurally and functionally associated with the respective circuits throughout the CNS. Astonishingly, in astrocytes, glutamatergic as well as GABAergic inputs elicit similar rises in intracellular Ca2+ that in turn can trigger the release of glutamate and GABA as well. Paradoxically, as gliotransmitters, these two molecules can thus strengthen, weaken or even reverse the input signal. Therefore, the net impact on neuronal network function is often convoluted and cannot be simply predicted by the nature of the stimulus itself. In this review, we highlight the ambiguity of astrocytes on discriminating and affecting synaptic activity in physiological and pathological state. Indeed, aberrant astroglial Ca2+ signaling is a key aspect of pathological conditions exhibiting compromised network excitability, such as epilepsy. Here, we gather recent evidence on the complexity of astroglial Ca2+ signals in health and disease, challenging the traditional, neuro-centric concept of segregating E/I, in favor of a non-binary, mutually dependent perspective on glutamatergic and GABAergic transmission.
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Affiliation(s)
- Laura C Caudal
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Davide Gobbo
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Anja Scheller
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, Homburg, Germany
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152
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Ingiosi AM, Hayworth CR, Harvey DO, Singletary KG, Rempe MJ, Wisor JP, Frank MG. A Role for Astroglial Calcium in Mammalian Sleep and Sleep Regulation. Curr Biol 2020; 30:4373-4383.e7. [PMID: 32976809 PMCID: PMC7919541 DOI: 10.1016/j.cub.2020.08.052] [Citation(s) in RCA: 77] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 07/07/2020] [Accepted: 08/13/2020] [Indexed: 10/23/2022]
Abstract
Mammalian sleep expression and regulation have historically been thought to reflect the activity of neurons. Changes in other brain cells (glia) across the sleep-wake cycle and their role in sleep regulation are comparatively unexplored. We show that sleep and wakefulness are accompanied by state-dependent changes in astroglial activity. Using a miniature microscope in freely behaving mice and a two-photon microscope in head-fixed, unanesthetized mice, we show that astroglial calcium signals are highest in wake and lowest in sleep and are most pronounced in astroglial processes. We also find that astroglial calcium signals during non-rapid eye movement sleep change in proportion to sleep need. In contrast to neurons, astrocytes become less synchronized during non-rapid eye movement sleep after sleep deprivation at the network and single-cell level. Finally, we show that conditionally reducing intracellular calcium in astrocytes impairs the homeostatic response to sleep deprivation. Thus, astroglial calcium activity changes dynamically across vigilance states, is proportional to sleep need, and is a component of the sleep homeostat.
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Affiliation(s)
- Ashley M Ingiosi
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, East Spokane Falls Boulevard, Spokane, WA 99202, USA
| | - Christopher R Hayworth
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, East Spokane Falls Boulevard, Spokane, WA 99202, USA
| | - Daniel O Harvey
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, East Spokane Falls Boulevard, Spokane, WA 99202, USA
| | - Kristan G Singletary
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, East Spokane Falls Boulevard, Spokane, WA 99202, USA
| | - Michael J Rempe
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, East Spokane Falls Boulevard, Spokane, WA 99202, USA; Department of Mathematics and Computer Science, Whitworth University, West Hawthorne Road, Spokane, WA 99251, USA
| | - Jonathan P Wisor
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, East Spokane Falls Boulevard, Spokane, WA 99202, USA
| | - Marcos G Frank
- Department of Biomedical Sciences, Elson S. Floyd College of Medicine, Washington State University, East Spokane Falls Boulevard, Spokane, WA 99202, USA.
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153
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Manninen T, Saudargiene A, Linne ML. Astrocyte-mediated spike-timing-dependent long-term depression modulates synaptic properties in the developing cortex. PLoS Comput Biol 2020; 16:e1008360. [PMID: 33170856 PMCID: PMC7654831 DOI: 10.1371/journal.pcbi.1008360] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 09/22/2020] [Indexed: 12/26/2022] Open
Abstract
Astrocytes have been shown to modulate synaptic transmission and plasticity in specific cortical synapses, but our understanding of the underlying molecular and cellular mechanisms remains limited. Here we present a new biophysicochemical model of a somatosensory cortical layer 4 to layer 2/3 synapse to study the role of astrocytes in spike-timing-dependent long-term depression (t-LTD) in vivo. By applying the synapse model and electrophysiological data recorded from rodent somatosensory cortex, we show that a signal from a postsynaptic neuron, orchestrated by endocannabinoids, astrocytic calcium signaling, and presynaptic N-methyl-D-aspartate receptors coupled with calcineurin signaling, induces t-LTD which is sensitive to the temporal difference between post- and presynaptic firing. We predict for the first time the dynamics of astrocyte-mediated molecular mechanisms underlying t-LTD and link complex biochemical networks at presynaptic, postsynaptic, and astrocytic sites to the time window of t-LTD induction. During t-LTD a single astrocyte acts as a delay factor for fast neuronal activity and integrates fast neuronal sensory processing with slow non-neuronal processing to modulate synaptic properties in the brain. Our results suggest that astrocytes play a critical role in synaptic computation during postnatal development and are of paramount importance in guiding the development of brain circuit functions, learning and memory.
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Affiliation(s)
- Tiina Manninen
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
- Department of Neurobiology, Stanford University, Stanford, CA, USA
| | - Ausra Saudargiene
- Neuroscience Institute, Lithuanian University of Health Sciences, Kaunas, Lithuania
- Department of Informatics, Vytautas Magnus University, Kaunas, Lithuania
| | - Marja-Leena Linne
- Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
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154
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Schmidt E, Oheim M. Infrared Excitation Induces Heating and Calcium Microdomain Hyperactivity in Cortical Astrocytes. Biophys J 2020; 119:2153-2165. [PMID: 33130118 DOI: 10.1016/j.bpj.2020.10.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 10/01/2020] [Accepted: 10/07/2020] [Indexed: 11/16/2022] Open
Abstract
Unraveling how neural networks process and represent sensory information and how these cellular signals instruct behavioral output is a main goal in neuroscience. Two-photon activation of optogenetic actuators and calcium (Ca2+) imaging with genetically encoded indicators allow, respectively, the all-optical stimulation and readout of activity from genetically identified cell populations. However, these techniques locally expose the brain to high near-infrared light doses, raising the concern of light-induced adverse effects on the biology under study. Combining 2P imaging of Ca2+ transients in GCaMP6f-expressing cortical astrocytes and unbiased machine-based event detection, we demonstrate the subtle build-up of aberrant microdomain Ca2+ transients in the fine astroglial processes that depended on the average rather than peak laser power. Illumination conditions routinely being used in biological 2P microscopy (920-nm excitation, ∼100-fs, and ∼10 mW average power) increased the frequency of microdomain Ca2+ events but left their amplitude, area, and duration largely unchanged. Ca2+ transients in the otherwise silent soma were secondary to this peripheral hyperactivity that occurred without overt morphological damage. Continuous-wave (nonpulsed) 920-nm illumination at the same average power was as damaging as femtosecond pulses, unraveling the dominance of a heating-mediated damage mechanism. In an astrocyte-specific inositol 3-phosphate receptor type-2 knockout mouse, near-infrared light-induced Ca2+ microdomains persisted in the small processes, underpinning their resemblance to physiological inositol 3-phosphate receptor type-2-independent Ca2+ signals, whereas somatic hyperactivity was abolished. We conclude that, contrary to what has generally been believed in the field, shorter pulses and lower average power can help to alleviate damage and allow for longer recording windows at 920 nm.
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Affiliation(s)
- Elke Schmidt
- Université de Paris, SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Paris, France
| | - Martin Oheim
- Université de Paris, SPPIN - Saints-Pères Paris Institute for the Neurosciences, CNRS, Paris, France.
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155
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Yu X, Nagai J, Marti-Solano M, Soto JS, Coppola G, Babu MM, Khakh BS. Context-Specific Striatal Astrocyte Molecular Responses Are Phenotypically Exploitable. Neuron 2020; 108:1146-1162.e10. [PMID: 33086039 DOI: 10.1016/j.neuron.2020.09.021] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 08/13/2020] [Accepted: 09/16/2020] [Indexed: 12/14/2022]
Abstract
Astrocytes tile the central nervous system and are widely implicated in brain diseases, but the molecular mechanisms by which astrocytes contribute to brain disorders remain incompletely explored. By performing astrocyte gene expression analyses following 14 experimental perturbations of relevance to the striatum, we discovered that striatal astrocytes mount context-specific molecular responses at the level of genes, pathways, and upstream regulators. Through data mining, we also identified astrocyte pathways in Huntington's disease (HD) that were reciprocally altered with respect to the activation of striatal astrocyte G protein-coupled receptor (GPCR) signaling. Furthermore, selective striatal astrocyte stimulation of the Gi-GPCR pathway in vivo corrected several HD-associated astrocytic, synaptic, and behavioral phenotypes, with accompanying improvement of HD-associated astrocyte signaling pathways, including those related to synaptogenesis and neuroimmune functions. Overall, our data show that astrocytes are malleable, using context-specific responses that can be dissected molecularly and used for phenotypic benefit in brain disorders.
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Affiliation(s)
- Xinzhu Yu
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Jun Nagai
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Maria Marti-Solano
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK
| | - Joselyn S Soto
- Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - Giovanni Coppola
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA; Department of Psychiatry and Biobehavioral Sciences, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA; Center for Neurobehavioral Genetics, Semel Institute for Neuroscience and Human Behavior, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095-1751, USA
| | - M Madan Babu
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Francis Crick Avenue, Cambridge CB2 0QH, UK; Department of Structural Biology and Center for Data Driven Discovery, St. Jude Children's Research Hospital, Memphis, TN 38105-3678, USA
| | - 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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156
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Cho J, Huh Y. Astrocytic Calcium Dynamics Along the Pain Pathway. Front Cell Neurosci 2020; 14:594216. [PMID: 33192331 PMCID: PMC7596274 DOI: 10.3389/fncel.2020.594216] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Accepted: 09/14/2020] [Indexed: 12/30/2022] Open
Abstract
Astrocytes, once thought to be passive cells merely filling the space between neurons in the nervous system, are receiving attention as active modulators of the brain and spinal cord physiology by providing nutrients, maintaining homeostasis, and modulating synaptic transmission. Accumulating evidence indicates that astrocytes are critically involved in chronic pain regulation. Injury induces astrocytes to become reactive, and recent studies suggest that reactive astrocytes can have either neuroprotective or neurodegenerative effects. While the exact mechanisms underlying the transition from resting astrocytes to reactive astrocytes remain unknown, astrocytic calcium increase, coordinated by inflammatory molecules, has been suggested to trigger this transition. In this mini review article, we will discuss the roles of astrocytic calcium, channels contributing to calcium dynamics in astrocytes, astrocyte activations along the pain pathway, and possible relationships between astrocytic calcium dynamics and chronic pain.
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Affiliation(s)
- Jeiwon Cho
- Brain and Cognitive Science, Scranton College, Ewha Womans University, Seoul, South Korea
| | - Yeowool Huh
- Department of Medical Science, College of Medicine, Catholic Kwandong University, Incheon, South Korea.,Translational Brain Research Center, Catholic Kwandong University, International St. Mary's Hospital, Incheon, South Korea
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157
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Trujillo-Estrada L, Gomez-Arboledas A, Forner S, Martini AC, Gutierrez A, Baglietto-Vargas D, LaFerla FM. Astrocytes: From the Physiology to the Disease. Curr Alzheimer Res 2020; 16:675-698. [PMID: 31470787 DOI: 10.2174/1567205016666190830110152] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 04/12/2019] [Accepted: 05/17/2019] [Indexed: 12/14/2022]
Abstract
Astrocytes are key cells for adequate brain formation and regulation of cerebral blood flow as well as for the maintenance of neuronal metabolism, neurotransmitter synthesis and exocytosis, and synaptic transmission. Many of these functions are intrinsically related to neurodegeneration, allowing refocusing on the role of astrocytes in physiological and neurodegenerative states. Indeed, emerging evidence in the field indicates that abnormalities in the astrocytic function are involved in the pathogenesis of multiple neurodegenerative diseases, including Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD) and Amyotrophic Lateral Sclerosis (ALS). In the present review, we highlight the physiological role of astrocytes in the CNS, including their communication with other cells in the brain. Furthermore, we discuss exciting findings and novel experimental approaches that elucidate the role of astrocytes in multiple neurological disorders.
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Affiliation(s)
- Laura Trujillo-Estrada
- Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine, CA 92697-4545, United States
| | - Angela Gomez-Arboledas
- Department of Cell Biology, Genetic and Physiology, Faculty of Sciences, University of Malaga, Malaga, Spain.,Instituto de Investigación Biomédica de Malaga-IBIMA, Malaga, Spain.,Networking Research Center on Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Stefânia Forner
- Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine, CA 92697-4545, United States
| | - Alessandra Cadete Martini
- Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine, CA 92697-4545, United States
| | - Antonia Gutierrez
- Department of Cell Biology, Genetic and Physiology, Faculty of Sciences, University of Malaga, Malaga, Spain.,Instituto de Investigación Biomédica de Malaga-IBIMA, Malaga, Spain.,Networking Research Center on Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - David Baglietto-Vargas
- Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine, CA 92697-4545, United States.,Department of Neurobiology and Behavior, University of California, Irvine, CA 92697, United States
| | - Frank M LaFerla
- Institute for Memory Impairments and Neurological Disorders (UCI MIND), University of California, Irvine, CA 92697-4545, United States.,Department of Neurobiology and Behavior, University of California, Irvine, CA 92697, United States
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158
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Rutten L, Miyata K, Roswanjaya YP, Huisman R, Bu F, Hartog M, Linders S, van Velzen R, van Zeijl A, Bisseling T, Kohlen W, Geurts R. Duplication of Symbiotic Lysin Motif Receptors Predates the Evolution of Nitrogen-Fixing Nodule Symbiosis. PLANT PHYSIOLOGY 2020; 184:1004-1023. [PMID: 32669419 PMCID: PMC7536700 DOI: 10.1104/pp.19.01420] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 07/07/2020] [Indexed: 05/02/2023]
Abstract
Rhizobium nitrogen-fixing nodule symbiosis occurs in two taxonomic lineages: legumes (Fabaceae) and the genus Parasponia (Cannabaceae). Both symbioses are initiated upon the perception of rhizobium-secreted lipochitooligosaccharides (LCOs), called Nod factors. Studies in the model legumes Lotus japonicus and Medicago truncatula showed that rhizobium LCOs are perceived by a heteromeric receptor complex of distinct Lys motif (LysM)-type transmembrane receptors named NOD FACTOR RECEPTOR1 (LjNFR1) and LjNFR5 (L. japonicus) and LYSM DOMAIN CONTAINING RECEPTOR KINASE3 (MtLYK3)-NOD FACTOR PERCEPTION (MtNFP; M. truncatula). Recent phylogenomic comparative analyses indicated that the nodulation traits of legumes, Parasponia spp., as well as so-called actinorhizal plants that establish a symbiosis with diazotrophic Frankia spp. bacteria share an evolutionary origin about 110 million years ago. However, the evolutionary trajectory of LysM-type LCO receptors remains elusive. By conducting phylogenetic analysis, transcomplementation studies, and CRISPR-Cas9 mutagenesis in Parasponia andersonii, we obtained insight into the origin of LCO receptors essential for nodulation. We identified four LysM-type receptors controlling nodulation in P. andersonii: PanLYK1, PanLYK3, PanNFP1, and PanNFP2 These genes evolved from ancient duplication events predating and coinciding with the origin of nodulation. Phylogenetic and functional analyses associated the occurrence of a functional NFP2-orthologous receptor to LCO-driven nodulation. Legumes and Parasponia spp. use orthologous LysM-type receptors to perceive rhizobium LCOs, suggesting a shared evolutionary origin of LCO-driven nodulation. Furthermore, we found that both PanLYK1 and PanLYK3 are essential for intracellular arbuscule formation of mutualistic endomycorrhizal fungi. PanLYK3 also acts as a chitin oligomer receptor essential for innate immune signaling, demonstrating functional analogy to CHITIN ELECITOR RECEPTOR KINASE-type receptors.
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Affiliation(s)
- Luuk Rutten
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Kana Miyata
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Yuda Purwana Roswanjaya
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
- Centre of Technology for Agricultural Production, Agency for the Assessment and Application of Technology, 10340 Jakarta, Indonesia
| | - Rik Huisman
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Fengjiao Bu
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Marijke Hartog
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Sidney Linders
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Robin van Velzen
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
- Biosystematics Group, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Arjan van Zeijl
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Ton Bisseling
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Wouter Kohlen
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Rene Geurts
- Laboratory of Molecular Biology, Department of Plant Sciences, Wageningen University, 6708 PB Wageningen, The Netherlands
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159
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Rasmussen R, O'Donnell J, Ding F, Nedergaard M. Interstitial ions: A key regulator of state-dependent neural activity? Prog Neurobiol 2020; 193:101802. [PMID: 32413398 PMCID: PMC7331944 DOI: 10.1016/j.pneurobio.2020.101802] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/24/2020] [Accepted: 03/26/2020] [Indexed: 02/08/2023]
Abstract
Throughout the nervous system, ion gradients drive fundamental processes. Yet, the roles of interstitial ions in brain functioning is largely forgotten. Emerging literature is now revitalizing this area of neuroscience by showing that interstitial cations (K+, Ca2+ and Mg2+) are not static quantities but change dynamically across states such as sleep and locomotion. In turn, these state-dependent changes are capable of sculpting neuronal activity; for example, changing the local interstitial ion composition in the cortex is sufficient for modulating the prevalence of slow-frequency neuronal oscillations, or potentiating the gain of visually evoked responses. Disturbances in interstitial ionic homeostasis may also play a central role in the pathogenesis of central nervous system diseases. For example, impairments in K+ buffering occur in a number of neurodegenerative diseases, and abnormalities in neuronal activity in disease models disappear when interstitial K+ is normalized. Here we provide an overview of the roles of interstitial ions in physiology and pathology. We propose the brain uses interstitial ion signaling as a global mechanism to coordinate its complex activity patterns, and ion homeostasis failure contributes to central nervous system diseases affecting cognitive functions and behavior.
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Affiliation(s)
- Rune Rasmussen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark.
| | - John O'Donnell
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, 14642, United States
| | - Fengfei Ding
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, 14642, United States
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark; Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, 14642, United States.
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160
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Okubo Y. Astrocytic Ca2+ signaling mediated by the endoplasmic reticulum in health and disease. J Pharmacol Sci 2020; 144:83-88. [DOI: 10.1016/j.jphs.2020.07.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Revised: 07/07/2020] [Accepted: 07/08/2020] [Indexed: 12/19/2022] Open
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161
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Presa JL, Saravia F, Bagi Z, Filosa JA. Vasculo-Neuronal Coupling and Neurovascular Coupling at the Neurovascular Unit: Impact of Hypertension. Front Physiol 2020; 11:584135. [PMID: 33101063 PMCID: PMC7546852 DOI: 10.3389/fphys.2020.584135] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/04/2020] [Indexed: 12/18/2022] Open
Abstract
Components of the neurovascular unit (NVU) establish dynamic crosstalk that regulates cerebral blood flow and maintain brain homeostasis. Here, we describe accumulating evidence for cellular elements of the NVU contributing to critical physiological processes such as cerebral autoregulation, neurovascular coupling, and vasculo-neuronal coupling. We discuss how alterations in the cellular mechanisms governing NVU homeostasis can lead to pathological changes in which vascular endothelial and smooth muscle cell, pericyte and astrocyte function may play a key role. Because hypertension is a modifiable risk factor for stroke and accelerated cognitive decline in aging, we focus on hypertension-associated changes on cerebral arteriole function and structure, and the molecular mechanisms through which these may contribute to cognitive decline. We gather recent emerging evidence concerning cognitive loss in hypertension and the link with vascular dementia and Alzheimer’s disease. Collectively, we summarize how vascular dysfunction, chronic hypoperfusion, oxidative stress, and inflammatory processes can uncouple communication at the NVU impairing cerebral perfusion and contributing to neurodegeneration.
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Affiliation(s)
- Jessica L Presa
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina
| | - Flavia Saravia
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires and Instituto de Biología y Medicina Experimental, CONICET, Buenos Aires, Argentina
| | - Zsolt Bagi
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Jessica A Filosa
- Department of Physiology, Medical College of Georgia, Augusta University, Augusta, GA, United States
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162
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Jin SX, Higashimori H, Schin C, Tamashiro A, Men Y, Chiang MSR, Jarvis R, Cox D, Feig L, Yang Y. Astroglial FMRP modulates synaptic signaling and behavior phenotypes in FXS mouse model. Glia 2020; 69:594-608. [PMID: 32970902 DOI: 10.1002/glia.23915] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 09/09/2020] [Accepted: 09/11/2020] [Indexed: 12/16/2022]
Abstract
Fragile X syndrome (FXS) is one of the most common inherited intellectual disability (ID) disorders, in which the loss of FMRP protein induces a range of cellular signaling changes primarily through excess protein synthesis. Although neuron-centered molecular and cellular events underlying FXS have been characterized, how different CNS cell types are involved in typical FXS synaptic signaling changes and behavioral phenotypes is largely unknown. Recent evidence suggests that selective loss of astroglial FMRP is able to dysregulate glutamate uptake, increase spine density, and impair motor-skill learning. Here we investigated the effect of astroglial FMRP on synaptic signaling and FXS-related behavioral and learning phenotypes in astroglial Fmr1 cKO and cON mice in which FMRP expression is selectively diminished or restored in astroglia. We found that selective loss of astroglial FMRP contributes to cortical hyperexcitability by enhancing NMDAR-mediated evoked but not spontaneous miniEPSCs and elongating cortical UP state duration. Selective loss of astroglial FMRP is also sufficient to increase locomotor hyperactivity, significantly diminish social novelty preference, and induce memory acquisition and extinction deficits in astroglial Fmr1 cKO mice. Importantly, re-expression of astroglial FMRP is able to significantly rescue the hyperactivity (evoked NMDAR response, UP state duration, and open field test) and social novelty preference in astroglial Fmr1 cON mice. These results demonstrate a profound role of astroglial FMRP in the evoked synaptic signaling, spontaneously occurring cortical UP states, and FXS-related behavioral and learning phenotypes and provide important new insights in the cell type consideration for the FMRP reactivation strategy.
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Affiliation(s)
- Shan-Xue Jin
- Department of Developmental, Molecular, and Cellular Biology, Tufts University, Boston, Massachusetts, USA
| | - Haruki Higashimori
- Department of Neuroscience, School of Medicine, Tufts University, Boston, Massachusetts, USA
| | - Christina Schin
- Department of Neuroscience, School of Medicine, Tufts University, Boston, Massachusetts, USA
| | - Alessandra Tamashiro
- Department of Neuroscience, School of Medicine, Tufts University, Boston, Massachusetts, USA
| | - Yuqin Men
- Department of Neuroscience, School of Medicine, Tufts University, Boston, Massachusetts, USA
| | - Ming Sum R Chiang
- Department of Neuroscience, School of Medicine, Tufts University, Boston, Massachusetts, USA
| | - Rachel Jarvis
- Department of Neuroscience, School of Medicine, Tufts University, Boston, Massachusetts, USA
| | - Dan Cox
- Department of Neuroscience, School of Medicine, Tufts University, Boston, Massachusetts, USA
| | - Larry Feig
- Department of Developmental, Molecular, and Cellular Biology, Tufts University, Boston, Massachusetts, USA.,Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA
| | - Yongjie Yang
- Department of Neuroscience, School of Medicine, Tufts University, Boston, Massachusetts, USA.,Graduate School of Biomedical Sciences, Tufts University, Boston, Massachusetts, USA
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163
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Verkhratsky A, Semyanov A, Zorec R. Physiology of Astroglial Excitability. FUNCTION (OXFORD, ENGLAND) 2020; 1:zqaa016. [PMID: 35330636 PMCID: PMC8788756 DOI: 10.1093/function/zqaa016] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 08/29/2020] [Accepted: 09/03/2020] [Indexed: 01/06/2023]
Abstract
Classic physiology divides all neural cells into excitable neurons and nonexcitable neuroglia. Neuroglial cells, chiefly responsible for homeostasis and defense of the nervous tissue, coordinate their complex homeostatic responses with neuronal activity. This coordination reflects a specific form of glial excitability mediated by complex changes in intracellular concentration of ions and second messengers organized in both space and time. Astrocytes are equipped with multiple molecular cascades, which are central for regulating homeostasis of neurotransmitters, ionostasis, synaptic connectivity, and metabolic support of the central nervous system. Astrocytes are further provisioned with multiple receptors for neurotransmitters and neurohormones, which upon activation trigger intracellular signals mediated by Ca2+, Na+, and cyclic AMP. Calcium signals have distinct organization and underlying mechanisms in different astrocytic compartments thus allowing complex spatiotemporal signaling. Signals mediated by fluctuations in cytosolic Na+ are instrumental for coordination of Na+ dependent astrocytic transporters with tissue state and homeostatic demands. Astroglial ionic excitability may also involve K+, H+, and Cl-. The cyclic AMP signalling system is, in comparison to ions, much slower in targeting astroglial effector mechanisms. This evidence review summarizes the concept of astroglial intracellular excitability.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK,Achucarro Center for Neuroscience, Ikerbasque, 48011 Bilbao, Spain,Address correspondence to A.V. (e-mail: )
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow 117997, Russia,Faculty of Biology, Moscow State University, Moscow, Russia,Sechenov First Moscow State Medical University, Moscow, Russia
| | - Robert Zorec
- Celica Biomedical, Ljubljana 1000, Slovenia,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana 1000, Slovenia
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164
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Semyanov A, Henneberger C, Agarwal A. Making sense of astrocytic calcium signals — from acquisition to interpretation. Nat Rev Neurosci 2020; 21:551-564. [DOI: 10.1038/s41583-020-0361-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/29/2020] [Indexed: 12/31/2022]
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165
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Woo J, Jang MW, Lee J, Koh W, Mikoshiba K, Lee CJ. The molecular mechanism of synaptic activity-induced astrocytic volume transient. J Physiol 2020; 598:4555-4572. [PMID: 32706443 DOI: 10.1113/jp279741] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 07/20/2020] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Neuronal activity causes astrocytic volume change via K+ uptake through TREK-1 containing two-pore domain potassium channels. The volume transient is terminated by Cl- efflux through the Ca2+ -activated anion channel BEST1. The source of the Ca2+ required to open BEST1 appears to be the stretch-activated TRPA1 channel. Intense neuronal activity is synaptically coupled with a physical change in astrocytes via volume transients. ABSTRACT The brain volume changes dynamically and transiently upon intense neuronal activity through a tight regulation of ion concentrations and water movement across the plasma membrane of astrocytes. We have recently demonstrated that an intense neuronal activity and subsequent astrocytic AQP4-dependent volume transient are critical for synaptic plasticity and memory. We have also pharmacologically demonstrated a functional coupling between synaptic activity and the astrocytic volume transient. However, the precise molecular mechanisms of how intense neuronal activity and the astrocytic volume transient are coupled remain unclear. Here we utilized an intrinsic optical signal imaging technique combined with fluorescence imaging using ion sensitive dyes and molecular probes and electrophysiology to investigate the detailed molecular mechanisms in genetically modified mice. We report that a brief synaptic activity induced by a train stimulation (20 Hz, 1 s) causes a prolonged astrocytic volume transient (80 s) via K+ uptake through TREK-1 containing two-pore domain potassium (K2P) channels, but not Kir4.1 or NKCC1. This volume change is terminated by Cl- efflux through the Ca2+ -activated anion channel BEST1, but not the volume-regulated anion channel TTYH. The source of the Ca2+ required to open BEST1 appears to be the stretch-activated TRPA1 channel in astrocytes, but not IP3 R2. In summary, our study identifies several important astrocytic ion channels (AQP4, TREK-1, BEST1, TRPA1) as the key molecules leading to the neuronal activity-dependent volume transient in astrocytes. Our findings reveal new molecular and cellular mechanisms for the synaptic coupling of intense neuronal activity with a physical change in astrocytes via volume transients.
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Affiliation(s)
- Junsung Woo
- Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Minwoo Wendy Jang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, 34126, Republic of Korea
| | - Jaekwang Lee
- Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea
| | - Wuhyun Koh
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, 34126, Republic of Korea.,Department of Neuroscience, Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Seoul, 02792, Republic of Korea
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Biology, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
| | - C Justin Lee
- Center for Glia-Neuron Interaction, Korea Institute of Science and Technology (KIST), Seoul, 02792, Republic of Korea.,KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, 34126, Republic of Korea.,Department of Neuroscience, Division of Bio-Medical Science & Technology, KIST School, Korea University of Science and Technology (UST), Seoul, 02792, Republic of Korea
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166
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Latifi S, Mitchell S, Habibey R, Hosseini F, Donzis E, Estrada-Sánchez AM, Nejad HR, Levine M, Golshani P, Carmichael ST. Neuronal Network Topology Indicates Distinct Recovery Processes after Stroke. Cereb Cortex 2020; 30:6363-6375. [PMID: 32728724 DOI: 10.1093/cercor/bhaa191] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 06/04/2020] [Accepted: 06/04/2020] [Indexed: 02/06/2023] Open
Abstract
Despite substantial recent progress in network neuroscience, the impact of stroke on the distinct features of reorganizing neuronal networks during recovery has not been defined. Using a functional connections-based approach through 2-photon in vivo calcium imaging at the level of single neurons, we demonstrate for the first time the functional connectivity maps during motion and nonmotion states, connection length distribution in functional connectome maps and a pattern of high clustering in motor and premotor cortical networks that is disturbed in stroke and reconstitutes partially in recovery. Stroke disrupts the network topology of connected inhibitory and excitatory neurons with distinct patterns in these 2 cell types and in different cortical areas. These data indicate that premotor cortex displays a distinguished neuron-specific recovery profile after stroke.
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Affiliation(s)
- Shahrzad Latifi
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
| | - Simon Mitchell
- Cancer Research Department, Brighton and Sussex Medical School, BN1 9PX, Brighton, UK
| | - Rouhollah Habibey
- Technische Universität Dresden, CRTD - Center for Regenerative Therapies at TU Dresden, D-01307, Dresden, German
| | | | - Elissa Donzis
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, UCLA School of Medicine, 760 Westwood Plaza, Los
| | - Ana María Estrada-Sánchez
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, UCLA School of Medicine, 760 Westwood Plaza, Los.,Divisioìn de Biologiìa Molecular, Instituto Potosino de Investigacioìn Cientiìfica y Tecnoloìgica (IPICYT), Camino a la presa San Joseì No. 2055, Colonia Lomas 4a seccioìn, C.P. 78216, San Luis Potosiì, Mexico
| | - H Rezaei Nejad
- Tufts University, Electrical and Computer Engineering Department, MA 02155, USA
| | - Michael Levine
- Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, UCLA School of Medicine, 760 Westwood Plaza, Los
| | - Peyman Golshani
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA.,Intellectual and Developmental Disabilities Research Center, Jane and Terry Semel Institute for Neuroscience & Human Behavior, UCLA School of Medicine, 760 Westwood Plaza, Los
| | - S Thomas Carmichael
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, CA 90095, USA
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167
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Umpierre AD, Bystrom LL, Ying Y, Liu YU, Worrell G, Wu LJ. Microglial calcium signaling is attuned to neuronal activity in awake mice. eLife 2020; 9:56502. [PMID: 32716294 PMCID: PMC7402678 DOI: 10.7554/elife.56502] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Accepted: 07/14/2020] [Indexed: 12/14/2022] Open
Abstract
Microglial calcium signaling underlies a number of key physiological and pathological processes in situ, but has not been studied in vivo in awake mice. Using multiple GCaMP6 variants targeted to microglia, we assessed how microglial calcium signaling responds to alterations in neuronal activity across a wide range. We find that only a small subset of microglial somata and processes exhibited spontaneous calcium transients in a chronic window preparation. However, hyperactive shifts in neuronal activity (kainate status epilepticus and CaMKIIa Gq DREADD activation) triggered increased microglial process calcium signaling, often concomitant with process extension. Additionally, hypoactive shifts in neuronal activity (isoflurane anesthesia and CaMKIIa Gi DREADD activation) also increased microglial process calcium signaling. Under hypoactive neuronal conditions, microglia also exhibited process extension and outgrowth with greater calcium signaling. Our work reveals that microglia have highly distinct microdomain signaling, and that processes specifically respond to bi-directional shifts in neuronal activity through increased calcium signaling.
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Affiliation(s)
| | | | - Yanlu Ying
- Department of Neurology, Mayo Clinic, Rochester, United States
| | - Yong U Liu
- Department of Neurology, Mayo Clinic, Rochester, United States
| | - Gregory Worrell
- Department of Neurology, Mayo Clinic, Rochester, United States
| | - Long-Jun Wu
- Department of Neurology, Mayo Clinic, Rochester, United States.,Department of Neuroscience, Mayo Clinic, Jacksonville, United States.,Department of Immunology, Mayo Clinic, Rochester, United States
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168
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Guillot de Suduiraut I, Grosse J, Ramos-Fernández E, Sandi C, Hollis F. Astrocytic release of ATP through type 2 inositol 1,4,5-trisphosphate receptor calcium signaling and social dominance behavior in mice. Eur J Neurosci 2020; 53:2973-2985. [PMID: 32609904 DOI: 10.1111/ejn.14892] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Revised: 05/22/2020] [Accepted: 06/18/2020] [Indexed: 01/08/2023]
Abstract
Brain mitochondrial function is critical for numerous neuronal processes. We recently identified a link between brain energy and social dominance, where higher levels of mitochondrial function resulted in increased social competitive ability. The underlying mechanism of this link, however, remains unclear. Here, we investigated the contribution of astrocytic release of adenosine triphosphate (ATP) through the type 2 inositol 1,4,5-triphosphate receptor to social dominance behavior. Mice lacking the type 2 inositol 1,4,5-triphosphate receptor were characterized for their social dominance behavior, as well as their performance on a nonsocial task, the Morris Water Maze. In parallel, we also examined mitochondrial function in the medial prefrontal cortex, nucleus accumbens, and hippocampus to investigate how deficiencies in astrocytic ATP could modulate overall mitochondrial function. While knockout mice showed similar competitive ability compared with their wild-type littermates, dominant knockout mice exhibited a significant delay in exerting their dominance during the initial encounter. Otherwise, there were no differences in anxiety and exploratory traits, spatial learning and memory, or brain mitochondrial function in either light or dark circadian phases. Our findings point to a marginal role of astrocytic ATP through IP3 R2 in social competition, suggesting that, under basal conditions, the neuronal compartment is predominant for social dominance exertion.
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Affiliation(s)
| | - Jocelyn Grosse
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Eva Ramos-Fernández
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Carmen Sandi
- Brain Mind Institute, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Fiona Hollis
- Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia
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169
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Deciphering the star codings: astrocyte manipulation alters mouse behavior. Exp Mol Med 2020; 52:1028-1038. [PMID: 32665584 PMCID: PMC8080576 DOI: 10.1038/s12276-020-0468-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Revised: 04/30/2020] [Accepted: 06/08/2020] [Indexed: 01/11/2023] Open
Abstract
Astrocytes occupy a vast area within the central nervous system (CNS). Despite their abundance, the functional role of astrocytes in vivo has only begun to be uncovered. Astrocytes were typically thought to be involved in pathophysiological states. However, recent studies have shown that astrocytes are actively involved in cell signaling in normal physiological states; manipulating various aspects of astrocytic cell signaling in vivo has revealed that astrocytes are key players in controlling healthy behavior in the absence of pathophysiology. Unfortunately, the study of astrocyte function is often limited by the number of approaches available due to our lack of understanding of cell physiology. This review summarizes recent studies in which altered astrocyte signaling capacity resulted in dramatic changes in behavior. We not only discuss the methodologies available to manipulate astrocytes but also provide insights into the behavioral roles of astrocytes in the CNS. Genetic studies provide increased evidence that astrocytes, star-shaped cells in the central nervous system, play important roles affecting behavior in mammals. Although they are just as abundant as neurons, astrocytes are not excited by electrical signals. For this reason they have traditionally been regarded simply as ‘support cells’ for neurons, but recent evidence suggests that they can significantly modulate neuron signals. A review paper by Keebum Park and Sung Joong Lee at Seoul National University in South Korea highlights improved methods for monitoring the signaling processes related to astrocytes, which manifest most notably through sharp changes in calcium levels. Several studies have used genetic knockout mice, designer drugs and light-sensitive proteins to change astrocyte activity, affecting a diverse range of behaviors including sleeping and feeding patterns, memory formation, depression and obsessive compulsive disorder.
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170
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Melanopsin for Time-Controlling Activation of Astrocyte -Neuron Networks. Methods Mol Biol 2020. [PMID: 32651909 DOI: 10.1007/978-1-0716-0755-8_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Melanopsin, a mammalian G-protein-coupled photopigment, is a novel optical tool which enables studying astrocyte-neuron networks. Here, we describe the required guidelines to take advantage of this promising optical tool for functional neuron-glia studies. The selective expression of melanopsin in astrocytes allows triggering astrocytic Ca2+ signaling, changes in synaptic transmission, and modifying behavioral responses.
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171
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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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172
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Pham C, Moro DH, Mouffle C, Didienne S, Hepp R, Pfrieger FW, Mangin JM, Legendre P, Martin C, Luquet S, Cauli B, Li D. Mapping astrocyte activity domains by light sheet imaging and spatio-temporal correlation screening. Neuroimage 2020; 220:117069. [PMID: 32585347 DOI: 10.1016/j.neuroimage.2020.117069] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 06/12/2020] [Accepted: 06/15/2020] [Indexed: 02/08/2023] Open
Abstract
Astrocytes are a major type of glial cell in the mammalian brain, essentially regulating neuronal development and function. Quantitative imaging represents an important approach to study astrocytic signaling in neural circuits. Focusing on astrocytic Ca2+ activity, a key pathway implicated in astrocye-neuron interaction, we here report a strategy combining fast light sheet fluorescence microscopy (LSFM) and correlative screening-based time series analysis, to map activity domains in astrocytes in living mammalian nerve tissue. Light sheet of micron-scale thickness enables wide-field optical sectioning to image astrocytes in acute mouse brain slices. Using both chemical and genetically encoded Ca2+ indicators, we demonstrate the complementary advantages of LSFM in mapping Ca2+ domains in astrocyte populations as compared to epifluorescence and two-photon microscopy. Our approach then revealed distinct kinetics of Ca2+ signals between cortical and hypothalamic astrocytes in resting conditions and following the activation of adrenergic G protein coupled receptor (GPCR). This observation highlights the activity heterogeneity across regionally distinct astrocyte populations, and indicates the potential of our method for investigating dynamic signals in astrocytes.
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Affiliation(s)
- Cuong Pham
- Sorbonne Université, Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR8246, INSERM U1130, UPMC UMCR18, Paris, 75005, France
| | - Daniela Herrera Moro
- Unité de Biologie Fonctionnelle et Adaptative, Centre National la Recherche Scientifique, Unité Mixte de Recherche 8251, Université Paris Diderot, Sorbonne Paris Cité, 75205, Paris, France
| | - Christine Mouffle
- Sorbonne Université, Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR8246, INSERM U1130, UPMC UMCR18, Paris, 75005, France
| | - Steve Didienne
- Sorbonne Université, Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR8246, INSERM U1130, UPMC UMCR18, Paris, 75005, France
| | - Régine Hepp
- Sorbonne Université, Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR8246, INSERM U1130, UPMC UMCR18, Paris, 75005, France
| | - Frank W Pfrieger
- Centre National de la Recherche Scientifique, Université de Strasbourg, Institut des Neurosciences Cellulaires et Intégratives, F-67000, Strasbourg, France
| | - Jean-Marie Mangin
- Sorbonne Université, Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR8246, INSERM U1130, UPMC UMCR18, Paris, 75005, France
| | - Pascal Legendre
- Sorbonne Université, Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR8246, INSERM U1130, UPMC UMCR18, Paris, 75005, France
| | - Claire Martin
- Unité de Biologie Fonctionnelle et Adaptative, Centre National la Recherche Scientifique, Unité Mixte de Recherche 8251, Université Paris Diderot, Sorbonne Paris Cité, 75205, Paris, France
| | - Serge Luquet
- Unité de Biologie Fonctionnelle et Adaptative, Centre National la Recherche Scientifique, Unité Mixte de Recherche 8251, Université Paris Diderot, Sorbonne Paris Cité, 75205, Paris, France
| | - Bruno Cauli
- Sorbonne Université, Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR8246, INSERM U1130, UPMC UMCR18, Paris, 75005, France
| | - Dongdong Li
- Sorbonne Université, Institute of Biology Paris Seine, Neuroscience Paris Seine, CNRS UMR8246, INSERM U1130, UPMC UMCR18, Paris, 75005, France.
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173
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Huang AYS, Woo J, Sardar D, Lozzi B, Bosquez Huerta NA, Lin CCJ, Felice D, Jain A, Paulucci-Holthauzen A, Deneen B. Region-Specific Transcriptional Control of Astrocyte Function Oversees Local Circuit Activities. Neuron 2020; 106:992-1008.e9. [PMID: 32320644 PMCID: PMC7879989 DOI: 10.1016/j.neuron.2020.03.025] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 02/24/2020] [Accepted: 03/24/2020] [Indexed: 02/06/2023]
Abstract
Astrocytes play essential roles in brain function by supporting synaptic connectivity and associated circuits. How these roles are regulated by transcription factors is unknown. Moreover, there is emerging evidence that astrocytes exhibit regional heterogeneity, and the mechanisms controlling this diversity remain nascent. Here, we show that conditional deletion of the transcription factor nuclear factor I-A (NFIA) in astrocytes in the adult brain results in region-specific alterations in morphology and physiology that are mediated by selective DNA binding. Disruptions in astrocyte function following loss of NFIA are most pronounced in the hippocampus, manifested by impaired interactions with neurons, coupled with diminution of learning and memory behaviors. These changes in hippocampal astrocytes did not affect basal neuronal properties but specifically inhibited synaptic plasticity, which is regulated by NFIA in astrocytes through calcium-dependent mechanisms. Together, our studies reveal region-specific transcriptional dependencies for astrocytes and identify astrocytic NFIA as a key transcriptional regulator of hippocampal circuits.
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Affiliation(s)
- Anna Yu-Szu Huang
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Junsung Woo
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA
| | - Debosmita Sardar
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA
| | - Brittney Lozzi
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA
| | - Navish A Bosquez Huerta
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Chia-Ching John Lin
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA
| | - Daniela Felice
- Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA
| | - Antrix Jain
- Mass Spectrometry Proteomics Core, Baylor College of Medicine, Houston, TX 77030, USA
| | | | - Benjamin Deneen
- Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, TX 77030, USA; Program in Developmental Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neuroscience, Baylor College of Medicine, Houston, TX 77030, USA; Department of Neurosurgery, Baylor College of Medicine, Houston, TX 77030, USA.
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174
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Abstract
Investigations of the mechanisms generating epileptic seizures have primarily focused on neurons. However, more systemic research of brain circuits has highlighted an important role of non-neuronal cells such as glia in the genesis and spreading of generalized seizures in the brain.
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Affiliation(s)
- Richard E Rosch
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK; Department of Bioengineering, University of Pennsylvania, PA 19104, USA; Department of Paediatric Neurology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, UK
| | - Éric Samarut
- Research Center of the University of Montreal Hospital Center (CRCHUM), Department of Neurosciences, Université de Montréal, Montréal H2X 0A9 QC, Canada; Modelis inc., Montreal, QC, Canada.
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175
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Abstract
Astrocytes are morphologically complex, ubiquitous cells that are viewed as a homogeneous population tiling the entire central nervous system (CNS). However, this view has been challenged in the last few years with the availability of RNA sequencing, immunohistochemistry, electron microscopy, morphological reconstruction, and imaging data. These studies suggest that astrocytes represent a diverse population of cells and that they display brain area- and disease-specific properties and functions. In this review, we summarize these observations, emphasize areas where clear conclusions can be made, and discuss potential unifying themes. We also identify knowledge gaps that need to be addressed in order to exploit astrocyte diversity as a biological phenomenon of physiological relevance in the CNS. We thus provide a summary and a perspective on astrocyte diversity in the vertebrate CNS.
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Affiliation(s)
- Baljit S Khakh
- Departments of Physiology and Neurobiology, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA;
| | - Benjamin Deneen
- Department of Neuroscience and Center for Cell and Gene Therapy, Baylor College of Medicine, Houston, Texas 77030, USA;
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176
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Menacho C, Prigione A. Tackling mitochondrial diversity in brain function: from animal models to human brain organoids. Int J Biochem Cell Biol 2020; 123:105760. [PMID: 32339638 DOI: 10.1016/j.biocel.2020.105760] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 04/20/2020] [Accepted: 04/22/2020] [Indexed: 12/15/2022]
Abstract
Mitochondria exhibit high degree of heterogeneity within various tissues, including differences in terms of morphology, quantity, or function. Mitochondria can even vary among distinct sub-compartments of the same cell. Emerging evidence suggest that the molecular diversity of mitochondria can influence the identity and functionality of a given cell type. Human pathologies affecting mitochondria typically cause tissue and cell-type-specific impairment. Mitochondrial diversity could thus play a contributing role not only in physiological cell fate specification but also during pathological disease development. In this review, we discuss the role of mitochondrial diversity in brain function during health and disease. Recent advances in induced pluripotent stem cells (iPSCs) research and the derivation of cerebral organoids could provide novel opportunities to unveil the role of mitochondrial heterogeneity for the function of the human brain. Mitochondrial diversity might be at the bases of the cell-type-specific vulnerability of mitochondrial disorders and may represent an underappreciated target of disease intervention.
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Affiliation(s)
- Carmen Menacho
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich Heine University, Düsseldorf, Germany
| | - Alessandro Prigione
- Department of General Pediatrics, Neonatology and Pediatric Cardiology, University Children's Hospital, Heinrich Heine University, Düsseldorf, Germany; Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany.
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177
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Structural basis of astrocytic Ca 2+ signals at tripartite synapses. Nat Commun 2020; 11:1906. [PMID: 32312988 PMCID: PMC7170846 DOI: 10.1038/s41467-020-15648-4] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Accepted: 03/19/2020] [Indexed: 02/07/2023] Open
Abstract
Astrocytic Ca2+ signals can be fast and local, supporting the idea that astrocytes have the ability to regulate single synapses. However, the anatomical basis of such specific signaling remains unclear, owing to difficulties in resolving the spongiform domain of astrocytes where most tripartite synapses are located. Using 3D-STED microscopy in living organotypic brain slices, we imaged the spongiform domain of astrocytes and observed a reticular meshwork of nodes and shafts that often formed loop-like structures. These anatomical features were also observed in acute hippocampal slices and in barrel cortex in vivo. The majority of dendritic spines were contacted by nodes and their sizes were correlated. FRAP experiments and Ca2+ imaging showed that nodes were biochemical compartments and Ca2+ microdomains. Mapping astrocytic Ca2+ signals onto STED images of nodes and dendritic spines showed they were associated with individual synapses. Here, we report on the nanoscale organization of astrocytes, identifying nodes as a functional astrocytic component of tripartite synapses that may enable synapse-specific communication between neurons and astrocytes. Astrocytic Ca2+ signals can be fast and local, supporting the idea that astrocytes have the ability to regulate single synapses. Here, the authors report the organization of astrocytes at nanoscale level and identify nodes as a functional astrocytic component of tripartite synapses.
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178
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Guerra-Gomes S, Cunha-Garcia D, Marques Nascimento DS, Duarte-Silva S, Loureiro-Campos E, Morais Sardinha V, Viana JF, Sousa N, Maciel P, Pinto L, Oliveira JF. IP 3 R2 null mice display a normal acquisition of somatic and neurological development milestones. Eur J Neurosci 2020; 54:5673-5686. [PMID: 32166822 DOI: 10.1111/ejn.14724] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 02/19/2020] [Accepted: 03/09/2020] [Indexed: 12/20/2022]
Abstract
Astrocytes are key players in the regulation of brain development and function. They sense and respond to the surrounding activity by elevating their intracellular calcium (Ca2+ ) levels. These astrocytic Ca2+ elevations emerge from different sources and display complex spatio-temporal properties. Ca2+ elevations are spatially distributed in global (soma and main processes) and/or focal regions (microdomains). The inositol 1,4,5-trisphosphate receptor type 2 knockout (IP3 R2 KO) mouse model lacks global Ca2+ elevations in astrocytes, and it has been used by different laboratories. However, the constitutive deletion of IP3 R2 during development may trigger compensating phenotypes, which could bias the results of experiments using developing or adult mice. To address this issue, we performed a detailed neurodevelopmental evaluation of male and female IP3 R2 KO mice, during the first 21 days of life, as well as an evaluation of motor function, strength and neurological reflexes in adult mice. Our results show that male and female IP3 R2 KO mice display a normal acquisition of developmental milestones, as compared with wild-type (WT) mice. We also show that IP3 R2 KO mice display normal motor coordination, strength and neurological reflexes in adulthood. To exclude a potential compensatory overexpression of other IP3 Rs, we quantified the relative mRNA levels of all 3 subtypes, in brain tissue. We found that, along with the complete deletion of Itpr2, there is no compensatory expression of Itpr1 or Itrp3. Overall, our results show that the IP3 R2 KO mouse is a reliable model to study the functional impact of global IP3 R2-dependent astrocytic Ca2+ elevations.
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Affiliation(s)
- Sónia Guerra-Gomes
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Daniela Cunha-Garcia
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Diana Sofia Marques Nascimento
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Sara Duarte-Silva
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Eduardo Loureiro-Campos
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Vanessa Morais Sardinha
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - João Filipe Viana
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Nuno Sousa
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Patrícia Maciel
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - Luísa Pinto
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal
| | - João Filipe Oliveira
- Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, Portugal.,ICVS/3B's - PT Government Associate Laboratory, Braga/Guimarães, Portugal.,Applied Artificial Intelligence Laboratory, IPCA-EST-2Ai, Polytechnic Institute of Cávado and Ave, Barcelos, Portugal
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179
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Ghézali G, Vasile F, Curry N, Fantham M, Cheung G, Ezan P, Cohen-Salmon M, Kaminski C, Rouach N. Neuronal Activity Drives Astroglial Connexin 30 in Perisynaptic Processes and Shapes Its Functions. Cereb Cortex 2020; 30:753-766. [PMID: 31271200 PMCID: PMC7086174 DOI: 10.1093/cercor/bhz123] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 04/22/2019] [Accepted: 05/17/2019] [Indexed: 12/17/2022] Open
Abstract
Astrocytes play key roles in brain functions through dynamic interactions with neurons. One of their typical features is to express high levels of connexins (Cxs), Cx43 and Cx30, the gap junction (GJ)-forming proteins. Cx30 is involved in basic cognitive processes and shapes synaptic and network activities, as shown by recent studies in transgenic animals. Yet it remains unknown whether astroglial Cx30 expression, localization, and functions are endogenously and dynamically regulated by neuronal activity and could therefore play physiological roles in neurotransmission. We here show that neuronal activity increased hippocampal Cx30 protein levels via a posttranslational mechanism regulating lysosomal degradation. Neuronal activity also increased Cx30 protein levels at membranes and perisynaptic processes, as revealed by superresolution imaging. This translated at the functional level in the activation of Cx30 hemichannels and in Cx30-mediated remodeling of astrocyte morphology independently of GJ biochemical coupling. Altogether, these data show activity-dependent dynamics of Cx30 expression, perisynaptic localization, and functions.
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Affiliation(s)
- Grégory Ghézali
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
- Doctoral School N° 158, Pierre and Marie Curie University, 75006 Paris, France
| | - Flora Vasile
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
- Doctoral School N°474, Rene Descartes University, 75006 Paris, France
| | - Nathan Curry
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Marcus Fantham
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Giselle Cheung
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Pascal Ezan
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Martine Cohen-Salmon
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Clemens Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
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180
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High-Frequency Microdomain Ca 2+ Transients and Waves during Early Myelin Internode Remodeling. Cell Rep 2020; 26:182-191.e5. [PMID: 30605675 PMCID: PMC6316190 DOI: 10.1016/j.celrep.2018.12.039] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Revised: 11/09/2018] [Accepted: 12/07/2018] [Indexed: 11/25/2022] Open
Abstract
Ensheathment of axons by myelin is a highly complex and multi-cellular process. Cytosolic calcium (Ca2+) changes in the myelin sheath have been implicated in myelin synthesis, but the source of this Ca2+ and the role of neuronal activity is not well understood. Using one-photon Ca2+ imaging, we investigated myelin sheath formation in the mouse somatosensory cortex and found a high rate of spontaneous microdomain Ca2+ transients and large-amplitude Ca2+ waves propagating along the internode. The frequency of Ca2+ transients and waves rapidly declines with maturation and reactivates during remyelination. Unexpectedly, myelin microdomain Ca2+ transients occur independent of neuronal action potential generation or network activity but are nearly completely abolished when the mitochondrial permeability transition pores are blocked. These findings are supported by the discovery of mitochondria organelles in non-compacted myelin. Together, the results suggest that myelin microdomain Ca2+ signals are cell-autonomously driven by high activity of mitochondria during myelin remodeling. Developing myelin sheaths show high rates of calcium transients and calcium waves Myelin calcium transients are independent from neuronal activity Adaxonal and paranodal myelin contained mitochondria Calcium transients require opening of mitochondrial permeability transition pores
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181
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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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182
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Yu X, Nagai J, Khakh BS. Improved tools to study astrocytes. Nat Rev Neurosci 2020; 21:121-138. [DOI: 10.1038/s41583-020-0264-8] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2020] [Indexed: 12/21/2022]
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183
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Zuend M, Saab AS, Wyss MT, Ferrari KD, Hösli L, Looser ZJ, Stobart JL, Duran J, Guinovart JJ, Barros LF, Weber B. Arousal-induced cortical activity triggers lactate release from astrocytes. Nat Metab 2020; 2:179-191. [PMID: 32694692 DOI: 10.1038/s42255-020-0170-4] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/08/2018] [Accepted: 01/15/2020] [Indexed: 01/01/2023]
Abstract
It has been suggested that, in states of arousal, release of noradrenaline and β-adrenergic signalling affect long-term memory formation by stimulating astrocytic lactate production from glycogen. However, the temporal relationship between cortical activity and cellular lactate fluctuations upon changes in arousal remains to be fully established. Also, the role of β-adrenergic signalling and brain glycogen metabolism on neural lactate dynamics in vivo is still unknown. Here, we show that an arousal-induced increase in cortical activity triggers lactate release into the extracellular space, and this correlates with a fast and prominent lactate dip in astrocytes. The immediate drop in astrocytic lactate concentration and the parallel increase in extracellular lactate levels underline an activity-dependent lactate release from astrocytes. Moreover, when β-adrenergic signalling is blocked or the brain is depleted of glycogen, the arousal-evoked cellular lactate surges are significantly reduced. We provide in vivo evidence that cortical activation upon arousal triggers lactate release from astrocytes, a rise in intracellular lactate levels mediated by β-adrenergic signalling and the mobilization of lactate from glycogen stores.
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Affiliation(s)
- Marc Zuend
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Aiman S Saab
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Matthias T Wyss
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Kim David Ferrari
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Ladina Hösli
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Zoe J Looser
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Jillian L Stobart
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland
| | - Jordi Duran
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Madrid, Spain
| | - Joan J Guinovart
- Institute for Research in Biomedicine, The Barcelona Institute of Science and Technology, Barcelona, Spain
- Centro de Investigación Biomédica en Red de Diabetes y Enfermedades Metabólicas Asociadas, Madrid, Spain
- Department of Biochemistry and Molecular Biomedicine, University of Barcelona, Barcelona, Spain
| | | | - Bruno Weber
- Institute of Pharmacology and Toxicology, University of Zurich, Zurich, Switzerland.
- Neuroscience Center Zurich, University of Zurich and ETH Zurich, Zurich, Switzerland.
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184
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Hirbec H, Déglon N, Foo LC, Goshen I, Grutzendler J, Hangen E, Kreisel T, Linck N, Muffat J, Regio S, Rion S, Escartin C. Emerging technologies to study glial cells. Glia 2020; 68:1692-1728. [PMID: 31958188 DOI: 10.1002/glia.23780] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Revised: 12/20/2019] [Accepted: 12/23/2019] [Indexed: 12/11/2022]
Abstract
Development, physiological functions, and pathologies of the brain depend on tight interactions between neurons and different types of glial cells, such as astrocytes, microglia, oligodendrocytes, and oligodendrocyte precursor cells. Assessing the relative contribution of different glial cell types is required for the full understanding of brain function and dysfunction. Over the recent years, several technological breakthroughs were achieved, allowing "glio-scientists" to address new challenging biological questions. These technical developments make it possible to study the roles of specific cell types with medium or high-content workflows and perform fine analysis of their mutual interactions in a preserved environment. This review illustrates the potency of several cutting-edge experimental approaches (advanced cell cultures, induced pluripotent stem cell (iPSC)-derived human glial cells, viral vectors, in situ glia imaging, opto- and chemogenetic approaches, and high-content molecular analysis) to unravel the role of glial cells in specific brain functions or diseases. It also illustrates the translation of some techniques to the clinics, to monitor glial cells in patients, through specific brain imaging methods. The advantages, pitfalls, and future developments are discussed for each technique, and selected examples are provided to illustrate how specific "gliobiological" questions can now be tackled.
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Affiliation(s)
- Hélène Hirbec
- Institute for Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Nicole Déglon
- Laboratory of Neurotherapies and Neuromodulation, Department of Clinical Neuroscience, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland.,Laboratory of Neurotherapies and Neuromodulation, Neuroscience Research Center, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Lynette C Foo
- Neuroimmunology and Neurodegeneration Section, The Neuroscience and Rare Diseases Discovery and Translational Area, F. Hoffman-La Roche, Basel, Switzerland
| | - Inbal Goshen
- Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Jaime Grutzendler
- Department of Neurology, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Neuroscience, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Emilie Hangen
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Département de la Recherche Fondamentale, Institut de Biologie François Jacob, MIRCen, Fontenay-aux-Roses, France.,Centre National de la Recherche Scientifique, Neurodegenerative Diseases Laboratory, Université Paris-Sud, Université Paris-Saclay, UMR 9199, Fontenay-aux-Roses, France
| | - Tirzah Kreisel
- Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Nathalie Linck
- Institute for Functional Genomics (IGF), University of Montpellier, CNRS, INSERM, Montpellier, France
| | - Julien Muffat
- Program in Neurosciences and Mental Health, The Hospital for Sick Children, and Department of Molecular Genetics, The University of Toronto, Toronto, Canada
| | - Sara Regio
- Laboratory of Neurotherapies and Neuromodulation, Department of Clinical Neuroscience, Lausanne University Hospital, University of Lausanne, Lausanne, Switzerland.,Laboratory of Neurotherapies and Neuromodulation, Neuroscience Research Center, Lausanne University Hospital and University of Lausanne, Lausanne, Switzerland
| | - Sybille Rion
- Neuroimmunology and Neurodegeneration Section, The Neuroscience and Rare Diseases Discovery and Translational Area, F. Hoffman-La Roche, Basel, Switzerland
| | - Carole Escartin
- Commissariat à l'Energie Atomique et aux Energies Alternatives, Département de la Recherche Fondamentale, Institut de Biologie François Jacob, MIRCen, Fontenay-aux-Roses, France.,Centre National de la Recherche Scientifique, Neurodegenerative Diseases Laboratory, Université Paris-Sud, Université Paris-Saclay, UMR 9199, Fontenay-aux-Roses, France
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185
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Kery R, Chen APF, Kirschen GW. Genetic targeting of astrocytes to combat neurodegenerative disease. Neural Regen Res 2020; 15:199-211. [PMID: 31552885 PMCID: PMC6905329 DOI: 10.4103/1673-5374.265541] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Astrocytes, glial cells that interact extensively with neurons and other support cells throughout the central nervous system, have recently come under the spotlight for their potential contribution to, or potential regenerative role in a host of neurodegenerative disorders. It is becoming increasingly clear that astrocytes, in concert with microglial cells, activate intrinsic immunological pathways in the setting of neurodegenerative injury, although the direct and indirect consequences of such activation are still largely unknown. We review the current literature on the astrocyte’s role in several neurodegenerative diseases, as well as highlighting recent advances in genetic manipulation of astrocytes that may prove critical to modulating their response to neurological injury, potentially combatting neurodegenerative damage.
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Affiliation(s)
- Rachel Kery
- Medical Scientist Training Program (MSTP), Stony Brook Medicine; Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY, USA
| | - Allen P F Chen
- Medical Scientist Training Program (MSTP), Stony Brook Medicine; Department of Neurobiology & Behavior, Stony Brook University, Stony Brook, NY, USA
| | - Gregory W Kirschen
- Medical Scientist Training Program (MSTP), Stony Brook Medicine, Stony Brook, NY, USA
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186
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Kastanenka KV, Moreno-Bote R, De Pittà M, Perea G, Eraso-Pichot A, Masgrau R, Poskanzer KE, Galea E. A roadmap to integrate astrocytes into Systems Neuroscience. Glia 2020; 68:5-26. [PMID: 31058383 PMCID: PMC6832773 DOI: 10.1002/glia.23632] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Revised: 04/08/2019] [Accepted: 04/09/2019] [Indexed: 12/14/2022]
Abstract
Systems neuroscience is still mainly a neuronal field, despite the plethora of evidence supporting the fact that astrocytes modulate local neural circuits, networks, and complex behaviors. In this article, we sought to identify which types of studies are necessary to establish whether astrocytes, beyond their well-documented homeostatic and metabolic functions, perform computations implementing mathematical algorithms that sub-serve coding and higher-brain functions. First, we reviewed Systems-like studies that include astrocytes in order to identify computational operations that these cells may perform, using Ca2+ transients as their encoding language. The analysis suggests that astrocytes may carry out canonical computations in a time scale of subseconds to seconds in sensory processing, neuromodulation, brain state, memory formation, fear, and complex homeostatic reflexes. Next, we propose a list of actions to gain insight into the outstanding question of which variables are encoded by such computations. The application of statistical analyses based on machine learning, such as dimensionality reduction and decoding in the context of complex behaviors, combined with connectomics of astrocyte-neuronal circuits, is, in our view, fundamental undertakings. We also discuss technical and analytical approaches to study neuronal and astrocytic populations simultaneously, and the inclusion of astrocytes in advanced modeling of neural circuits, as well as in theories currently under exploration such as predictive coding and energy-efficient coding. Clarifying the relationship between astrocytic Ca2+ and brain coding may represent a leap forward toward novel approaches in the study of astrocytes in health and disease.
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Affiliation(s)
- Ksenia V. Kastanenka
- Department of Neurology, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital and Harvard Medical School, Massachusetts 02129, USA
| | - Rubén Moreno-Bote
- Department of Information and Communications Technologies, Center for Brain and Cognition and Universitat Pompeu Fabra, 08018 Barcelona, Spain
- ICREA, 08010 Barcelona, Spain
| | | | | | - Abel Eraso-Pichot
- Departament de Bioquímica, Institut de Neurociències i Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Roser Masgrau
- Departament de Bioquímica, Institut de Neurociències i Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
| | - Kira E. Poskanzer
- Department of Biochemistry & Biophysics, Neuroscience Graduate Program, and Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, California 94143, USA
- Equally contributing authors
| | - Elena Galea
- ICREA, 08010 Barcelona, Spain
- Departament de Bioquímica, Institut de Neurociències i Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain
- Equally contributing authors
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187
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Spontaneous Ultraslow Na + Fluctuations in the Neonatal Mouse Brain. Cells 2019; 9:cells9010102. [PMID: 31906100 PMCID: PMC7016939 DOI: 10.3390/cells9010102] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/18/2019] [Accepted: 12/24/2019] [Indexed: 12/12/2022] Open
Abstract
In the neonate forebrain, network formation is driven by the spontaneous synchronized activity of pyramidal cells and interneurons, consisting of bursts of electrical activity and intracellular Ca2+ oscillations. By employing ratiometric Na+ imaging in tissue slices obtained from animals at postnatal day 2-4 (P2-4), we found that 20% of pyramidal neurons and 44% of astrocytes in neonatal mouse hippocampus also exhibit transient fluctuations in intracellular Na+. These occurred at very low frequencies (~2/h), were exceptionally long (~8 min), and strongly declined after the first postnatal week. Similar Na+ fluctuations were also observed in the neonate neocortex. In the hippocampus, Na+ elevations in both cell types were diminished when blocking action potential generation with tetrodotoxin. Neuronal Na+ fluctuations were significantly reduced by bicuculline, suggesting the involvement of GABAA-receptors in their generation. Astrocytic signals, by contrast, were neither blocked by inhibition of receptors and/or transporters for different transmitters including GABA and glutamate, nor of various Na+-dependent transporters or Na+-permeable channels. In summary, our results demonstrate for the first time that neonatal astrocytes and neurons display spontaneous ultraslow Na+ fluctuations. While neuronal Na+ signals apparently largely rely on suprathreshold GABAergic excitation, astrocytic Na+ signals, albeit being dependent on neuronal action potentials, appear to have a separate trigger and mechanism, the source of which remains unclear at present.
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188
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Macrophage Migration Inhibitory Factor Alters Functional Properties of CA1 Hippocampal Neurons in Mouse Brain Slices. Int J Mol Sci 2019; 21:ijms21010276. [PMID: 31906137 PMCID: PMC6981710 DOI: 10.3390/ijms21010276] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 12/23/2019] [Accepted: 12/24/2019] [Indexed: 02/06/2023] Open
Abstract
Neuroinflammation is implicated in a host of neurological insults, such as traumatic brain injury (TBI), ischemic stroke, Alzheimer's disease, Parkinson's disease, and epilepsy. The immune response to central nervous system (CNS) injury involves sequelae including the release of numerous cytokines and chemokines. Macrophage migration inhibitory factor (MIF), is one such cytokine that is elevated following CNS injury, and is associated with the prognosis of TBI, and ischemic stroke. MIF has been identified in astrocytes and neurons, and some of the trophic actions of MIF have been related to its direct and indirect actions on astrocytes. However, the potential modulation of CNS neuronal function by MIF has not yet been explored. This study tests the hypothesis that MIF can directly influence hippocampal neuronal function. MIF was microinjected into the hippocampus and the genetically encoded calcium indicator, GCaMP6f, was used to measure Ca2+ events in acute adult mouse brain hippocampal slices. Results demonstrated that a single injection of 200 ng MIF into the hippocampus significantly increased baseline calcium signals in CA1 pyramidal neuron somata, and altered calcium responses to N-methyl-d-aspartate (NMDA) + D-serine in pyramidal cell apical dendrites located in the stratum radiatum. These data are the first to show direct effects of MIF on hippocampal neurons and on NMDA receptor function. Considering that MIF is elevated after brain insults such as TBI, the data suggest that, in addition to the previously described role of MIF in astrocyte reactivity, elevated MIF can have significant effects on neuronal function in the hippocampus.
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189
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Heuser K, Nome CG, Pettersen KH, Åbjørsbråten KS, Jensen V, Tang W, Sprengel R, Taubøll E, Nagelhus EA, Enger R. Ca2+ Signals in Astrocytes Facilitate Spread of Epileptiform Activity. Cereb Cortex 2019; 28:4036-4048. [PMID: 30169757 PMCID: PMC6188565 DOI: 10.1093/cercor/bhy196] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2018] [Accepted: 07/21/2018] [Indexed: 01/04/2023] Open
Abstract
Epileptic seizures are associated with increased astrocytic Ca2+ signaling, but the fine spatiotemporal kinetics of the ictal astrocyte–neuron interplay remains elusive. By using 2-photon imaging of awake head-fixed mice with chronic hippocampal windows we demonstrate that astrocytic Ca2+ signals precede neuronal Ca2+ elevations during the initial bout of kainate-induced seizures. On average, astrocytic Ca2+ elevations preceded neuronal activity in CA1 by about 8 s. In subsequent bouts of epileptic seizures, astrocytes and neurons were activated simultaneously. The initial astrocytic Ca2+ elevation was abolished in mice lacking the type 2 inositol-1,4,5-trisphosphate-receptor (Itpr2−/−). Furthermore, we found that Itpr2−/− mice exhibited 60% less epileptiform activity compared with wild-type mice when assessed by telemetric EEG monitoring. In both genotypes we also demonstrate that spreading depression waves may play a part in seizure termination. Our findings imply a role for astrocytic Ca2+ signals in ictogenesis.
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Affiliation(s)
- Kjell Heuser
- Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Cecilie G Nome
- Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Klas H Pettersen
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Knut S Åbjørsbråten
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Vidar Jensen
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Wannan Tang
- Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Rolf Sprengel
- Max Planck Research Group "Molecular Neurobiology" at the Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Erik Taubøll
- Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.,Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Erlend A Nagelhus
- Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.,Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Rune Enger
- Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway.,Letten Centre and GliaLab, Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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190
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Gu X, Chen W, Volkow ND, Koretsky AP, Du C, Pan Y. Synchronized Astrocytic Ca 2+ Responses in Neurovascular Coupling during Somatosensory Stimulation and for the Resting State. Cell Rep 2019; 23:3878-3890. [PMID: 29949771 PMCID: PMC7469112 DOI: 10.1016/j.celrep.2018.05.091] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Revised: 04/05/2018] [Accepted: 05/27/2018] [Indexed: 02/08/2023] Open
Abstract
The role of astrocytes in neurovascular coupling (NVC) is unclear. Here, we applied a multimodality imaging approach to concomitantly measure synchronized neuronal or astrocytic Ca2+ and hemodynamic changes in the mouse somatosensory cortex at rest and during sensory electrical stimulation. Strikingly, we found that low-frequency stimulation (0.3-1 Hz), which consistently evokes fast neuronal Ca2+ transients (6.0 ± 2.7 ms latency) that always precede vascular responses, does not always elicit astrocytic Ca2+ transients (313 ± 65 ms latency). However, the magnitude of the hemodynamic response is increased when astrocytic transients occur, suggesting a facilitatory role of astrocytes in NVC. High-frequency stimulation (5-10 Hz) consistently evokes a large, delayed astrocytic Ca2+ accumulation (3.48 ± 0.09 s latency) that is temporarily associated with vasoconstriction, suggesting a role for astrocytes in resetting NVC. At rest, neuronal, but not astrocytic, Ca2+ fluctuations correlate with hemodynamic low-frequency oscillations. Taken together, these results support a role for astrocytes in modulating, but not triggering, NVC.
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Affiliation(s)
- Xiaochun Gu
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA; Jiangsu Key Laboratory of Molecular and Functional Imaging, Key Laboratory of Developmental Genes and Human Diseases, Department of Radiology, Zhongda Hospital, Medical School, Southeast University, #87 Dingjiaqiao Road, Nanjing 210009, China
| | - Wei Chen
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
| | - Nora D Volkow
- National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20857, USA
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, NIH, Bethesda, MD 20892, USA
| | - Congwu Du
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA
| | - Yingtian Pan
- Department of Biomedical Engineering, Stony Brook University, Stony Brook, NY 11794, USA.
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191
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NCX activity generates spontaneous Ca 2+ oscillations in the astrocytic leaflet microdomain. Cell Calcium 2019; 86:102137. [PMID: 31838438 DOI: 10.1016/j.ceca.2019.102137] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 12/01/2019] [Accepted: 12/01/2019] [Indexed: 12/13/2022]
Abstract
The synergy between synaptic Glu release and astrocytic Glu-Na+ symport is essential to the signalling function of the tripartite synapse. Here we used kinetic data of astrocytic Glu transporters (EAAT) and the Na+/Ca2+ exchanger (NCX) to simulate Glu release, Glu uptake and subsequent Na+ and Ca2+ dynamics in the astrocytic leaflet microdomain following single release event. Model simulations show that Glu-Na+ symport differently affect intracellular [Na+] in synapses with different extent of astrocytic coverage. Surprisingly, NCX activity alone has been shown to generate markedly stable, spontaneous Ca2+ oscillation in the astrocytic leaflet. These on-going oscillations appear when NCX operates either in the forward or reverse direction. We conjecture that intrinsic NCX activity may play a prominent role in the generation of astrocytic Ca2+ oscillations.
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192
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Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
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193
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Wang Y, DelRosso NV, Vaidyanathan TV, Cahill MK, Reitman ME, Pittolo S, Mi X, Yu G, Poskanzer KE. Accurate quantification of astrocyte and neurotransmitter fluorescence dynamics for single-cell and population-level physiology. Nat Neurosci 2019; 22:1936-1944. [PMID: 31570865 PMCID: PMC6858541 DOI: 10.1038/s41593-019-0492-2] [Citation(s) in RCA: 91] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2019] [Accepted: 08/09/2019] [Indexed: 02/06/2023]
Abstract
Recent work examining astrocytic physiology centers on fluorescence imaging, due to development of sensitive fluorescent indicators and observation of spatiotemporally complex calcium activity. However, the field remains hindered in characterizing these dynamics, both within single cells and at the population level, because of the insufficiency of current region-of-interest (ROI)-based approaches to describe activity that is often spatially unfixed, size-varying, and propagative. Here, we present an analytical framework that releases astrocyte biologists from ROI-based tools. The Astrocyte Quantitative Analysis (AQuA) software takes an event-based perspective to model and accurately quantify complex calcium and neurotransmitter activity in fluorescence imaging datasets. We apply AQuA to a range of ex vivo and in vivo imaging data, and uncover novel physiological phenomena. Since AQuA is data-driven and based on machine learning principles, it can be applied across model organisms, fluorescent indicators, experimental modes, and imaging resolutions and speeds, enabling researchers to elucidate fundamental neural physiology.
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Affiliation(s)
- Yizhi Wang
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Arlington, VA, USA
| | - Nicole V DelRosso
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Trisha V Vaidyanathan
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Michelle K Cahill
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Michael E Reitman
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA
| | - Silvia Pittolo
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Xuelong Mi
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Arlington, VA, USA
| | - Guoqiang Yu
- Bradley Department of Electrical and Computer Engineering, Virginia Polytechnic Institute and State University, Arlington, VA, USA.
| | - Kira E Poskanzer
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA. .,Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA, USA. .,Kavli Institute for Fundamental Neuroscience, San Francisco, CA, USA.
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194
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Abstract
Astrocytes are critical for maintaining the homeostasis of the CNS. Increasing evidence suggests that a number of neurological and neuropsychiatric disorders, including chronic pain, may result from astrocyte 'gliopathy'. Indeed, in recent years there has been substantial progress in our understanding of how astrocytes can regulate nociceptive synaptic transmission via neuronal-glial and glial-glial cell interactions, as well as the involvement of spinal and supraspinal astrocytes in the modulation of pain signalling and the maintenance of neuropathic pain. A role of astrocytes in the pathogenesis of chronic itch is also emerging. These developments suggest that targeting the specific pathways that are responsible for astrogliopathy may represent a novel approach to develop therapies for chronic pain and chronic itch.
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195
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Abstract
Our understanding of astrocytes and their role in neurological diseases has increased considerably over the past two decades as the diverse roles of these cells have become recognized. Our evolving understanding of these cells suggests that they are more than support cells for neurons and that they play important roles in CNS homeostasis under normal conditions, in neuroprotection and in disease exacerbation. These multiple functions make them excellent candidates for targeted therapies to treat neurological disorders. New technological advances, including in vivo imaging, optogenetics and chemogenetics, have allowed us to examine astrocytic functions in ways that have uncovered new insights into the dynamic roles of these cells. Furthermore, the use of induced pluripotent stem cell-derived astrocytes from patients with a host of neurological disorders can help to tease out the contributions of astrocytes to human disease. In this Review, we explore some of the technological advances developed over the past decade that have aided our understanding of astrocyte function. We also highlight neurological disorders in which astrocyte function or dysfunction is believed to have a role in disease pathogenesis or propagation and discuss how the technological advances have been and could be used to study each of these diseases.
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196
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Dallérac G, Zapata J, Rouach N. Versatile control of synaptic circuits by astrocytes: where, when and how? Nat Rev Neurosci 2019; 19:729-743. [PMID: 30401802 DOI: 10.1038/s41583-018-0080-6] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Close structural and functional interactions of astrocytes with synapses play an important role in brain function. The repertoire of ways in which astrocytes can regulate synaptic transmission is complex so that they can both promote and dampen synaptic efficacy. Such contrasting effects raise questions regarding the determinants of these divergent astroglial functions. Recent findings provide insights into where, when and how astroglial regulation of synapses takes place by revealing major molecular and functional intrinsic heterogeneity as well as switches in astrocytes occurring during development or specific patterns of neuronal activity. Astrocytes may therefore be seen as boosters or gatekeepers of synaptic circuits depending on their intrinsic and transformative properties throughout life.
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Affiliation(s)
- Glenn Dallérac
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Jonathan Zapata
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.
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197
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Zhou B, Chen L, Liao P, Huang L, Chen Z, Liao D, Yang L, Wang J, Yu G, Wang L, Zhang J, Zuo Y, Liu J, Jiang R. Astroglial dysfunctions drive aberrant synaptogenesis and social behavioral deficits in mice with neonatal exposure to lengthy general anesthesia. PLoS Biol 2019; 17:e3000086. [PMID: 31433818 PMCID: PMC6719896 DOI: 10.1371/journal.pbio.3000086] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 09/03/2019] [Accepted: 08/05/2019] [Indexed: 02/06/2023] Open
Abstract
Lengthy use of general anesthetics (GAs) causes neurobehavioral deficits in the developing brain, which has raised significant clinical concerns such that the United States Food and Drug Administration (FDA) is warning on the use of GAs in children younger than 3 years. However, the molecular and cellular mechanisms for GAs-induced neurotoxicity remain largely unknown. Here, we report that sevoflurane (Sevo), a commonly used GA in pediatrics, caused compromised astrocyte morphogenesis spatiotemporally correlated to synaptic overgrowth, with reduced synaptic function in developing cortex in a regional-, exposure-length-, and age-specific manner. Sevo disrupted astrocyte Ca2+ homeostasis both acutely and chronically, which led to the down-regulation of Ezrin, an actin-binding membrane-bound protein, which we found was critically involved in astrocyte morphogenesis in vivo. Importantly, overexpression of astrocyte Ezrin rescued astrocytic and neuronal dysfunctions and fully corrected deficits in social behaviors in developing mice with lengthy Sevo exposure. Our data uncover that, in addition to neurons, astrocytes may represent important targets for GAs to exert toxic effects and that astrocyte morphological integrity is crucial for synaptogenesis and neurological behaviors. The extended use of general anesthetics can cause neurobehavioral deficits in the developing brain, leading to clinical concerns regarding their use in children younger than 3 years. This study shows that general anesthetics target glial cells to disrupt neural circuit formation in the developing brain, an effect that may underlie the observed learning, cognitive, or emotional deficits.
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Affiliation(s)
- Bin Zhou
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Lingmin Chen
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ping Liao
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Lu Huang
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Zhuo Chen
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Daqing Liao
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Linghui Yang
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jing Wang
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Guoqiang Yu
- Bradley Department of Electrical & Computer Engineering, Virginia Polytechnic Institute and State University, Arlington, Virginia, United States of America
| | - Li Wang
- Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jianguo Zhang
- Center for Biological Imaging, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yunxia Zuo
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Jin Liu
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ruotian Jiang
- Laboratory of Anesthesia and Critical Care Medicine, Sichuan University, Chengdu, Sichuan, China
- Translational Neuroscience Center, Sichuan University, Chengdu, Sichuan, China
- Department of Anesthesiology of West China Hospital, Sichuan University, Chengdu, Sichuan, China
- * E-mail:
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198
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Denizot A, Arizono M, Nägerl UV, Soula H, Berry H. Simulation of calcium signaling in fine astrocytic processes: Effect of spatial properties on spontaneous activity. PLoS Comput Biol 2019; 15:e1006795. [PMID: 31425510 PMCID: PMC6726244 DOI: 10.1371/journal.pcbi.1006795] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 09/04/2019] [Accepted: 07/08/2019] [Indexed: 12/20/2022] Open
Abstract
Astrocytes, a glial cell type of the central nervous system, have emerged as detectors and regulators of neuronal information processing. Astrocyte excitability resides in transient variations of free cytosolic calcium concentration over a range of temporal and spatial scales, from sub-microdomains to waves propagating throughout the cell. Despite extensive experimental approaches, it is not clear how these signals are transmitted to and integrated within an astrocyte. The localization of the main molecular actors and the geometry of the system, including the spatial organization of calcium channels IP3R, are deemed essential. However, as most calcium signals occur in astrocytic ramifications that are too fine to be resolved by conventional light microscopy, most of those spatial data are unknown and computational modeling remains the only methodology to study this issue. Here, we propose an IP3R-mediated calcium signaling model for dynamics in such small sub-cellular volumes. To account for the expected stochasticity and low copy numbers, our model is both spatially explicit and particle-based. Extensive simulations show that spontaneous calcium signals arise in the model via the interplay between excitability and stochasticity. The model reproduces the main forms of calcium signals and indicates that their frequency crucially depends on the spatial organization of the IP3R channels. Importantly, we show that two processes expressing exactly the same calcium channels can display different types of calcium signals depending on the spatial organization of the channels. Our model with realistic process volume and calcium concentrations successfully reproduces spontaneous calcium signals that we measured in calcium micro-domains with confocal microscopy and predicts that local variations of calcium indicators might contribute to the diversity of calcium signals observed in astrocytes. To our knowledge, this model is the first model suited to investigate calcium dynamics in fine astrocytic processes and to propose plausible mechanisms responsible for their variability.
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Affiliation(s)
- Audrey Denizot
- INRIA, F-69603, Villeurbanne, France
- Univ Lyon, LIRIS, UMR5205 CNRS, F-69621, Villeurbanne, France
| | - Misa Arizono
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - U. Valentin Nägerl
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, Bordeaux, France
| | - Hédi Soula
- INRIA, F-69603, Villeurbanne, France
- Univ P&M Curie, CRC, INSERM UMRS 1138, F-75006, Paris, France
| | - Hugues Berry
- INRIA, F-69603, Villeurbanne, France
- Univ Lyon, LIRIS, UMR5205 CNRS, F-69621, Villeurbanne, France
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199
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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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200
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Verkhratsky A. Astroglial Calcium Signaling in Aging and Alzheimer's Disease. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035188. [PMID: 31110130 DOI: 10.1101/cshperspect.a035188] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Astrocytes are the homeostatic and protective cells of the central nervous system (CNS). In neurological diseases, astrocytes undergo complex changes, which are subclassified into (1) reactive astrogliosis, an evolutionary conserved defensive rearrangement of cellular phenotype aimed at neuroprotection; (2) pathological remodeling, when astrocytes acquire new features driving pathology; and (3) astrodegeneration, which is manifested by astroglial atrophy and loss of homeostatic functions. In aging brains as well as in the brains affected by Alzheimer's disease (AD), astrocytes acquire both atrophic and reactive phenotypes in a region- and disease-stage-dependent manner. Prevalence of atrophy overreactivity, observed in certain brain regions and in terminal stages of the disease, arguably facilitates the development of neurological deficits. Astrocytes exhibit ionic excitability mediated by changes in intracellular concentration of ions, most importantly of Ca2+ and Na+, with intracellular ion dynamics triggered by the activity of neural networks. AD astrocytes associated with senile plaques demonstrate Ca2+ hyperactivity in the form of aberrant Ca2+ oscillations and pathological long-range Ca2+ waves. Astroglial Ca2+ signaling originating from Ca2+ release from the endoplasmic reticulum is a key factor in initiating astrogliotic response; deficient Ca2+ signaling toolkits observed in entorhinal and prefrontal cortices of AD model animals may account for vulnerability of these regions to the pathology.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, United Kingdom.,Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark.,Achucarro Center for Neuroscience, Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
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