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Shiratori-Hayashi M, Tsuda M. IP 3R1-dependent astrocyte calcium signaling in chronic itch. Neurosci Res 2023; 187:40-44. [PMID: 36181909 DOI: 10.1016/j.neures.2022.09.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 09/27/2022] [Indexed: 10/14/2022]
Abstract
Astrocytes, the most abundant type of glial cell, are electrically non-excitable cells that use intracellular calcium (Ca2+) for functional regulation. Changes in intracellular Ca2+ concentration play important roles in the central nervous system (CNS), as they are involved in the release of gliotransmitters and the control of extracellular ion concentrations, thereby affecting the regulation of neuronal excitability, CNS homeostasis, and behavior. Intracellular calcium mobilization in astrocytes is known to be mediated via inositol 1,4,5-trisphosphate receptors (IP3Rs), particularly IP3R2, and its association with CNS pathogenesis has been widely reported. In addition, the existence of IP3R2-independent calcium signaling has recently been postulated; however, the detailed mechanisms and its role in astrocyte functions and CNS pathogenesis are still poorly understood. In this paper, we describe the putative mechanisms underlying IP3R1-dependent calcium signaling in astrocytes and its effects on the reactive state, compare this signaling with IP3R2-dependent calcium signaling, and discuss its contribution to chronic itch-like behavior.
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Affiliation(s)
- Miho Shiratori-Hayashi
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
| | - Makoto Tsuda
- Department of Molecular and System Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan; Kyushu University Institute for Advanced Study, Fukuoka, Japan.
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52
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Myers AJ, Brahimi A, Jenkins IJ, Koob AO. The Synucleins and the Astrocyte. BIOLOGY 2023; 12:biology12020155. [PMID: 36829434 PMCID: PMC9952504 DOI: 10.3390/biology12020155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 01/13/2023] [Accepted: 01/16/2023] [Indexed: 01/21/2023]
Abstract
Synucleins consist of three proteins exclusively expressed in vertebrates. α-Synuclein (αS) has been identified as the main proteinaceous aggregate in Lewy bodies, a pathological hallmark of many neurodegenerative diseases. Less is understood about β-synuclein (βS) and γ-synuclein (γS), although it is known βS can interact with αS in vivo to inhibit aggregation. Likewise, both γS and βS can inhibit αS's propensity to aggregate in vitro. In the central nervous system, βS and αS, and to a lesser extent γS, are highly expressed in the neural presynaptic terminal, although they are not strictly located there, and emerging data have shown a more complex expression profile. Synapse loss and astrocyte atrophy are early aspects of degenerative diseases of the brain and correlate with disease progression. Synucleins appear to be involved in synaptic transmission, and astrocytes coordinate and organize synaptic function, with excess αS degraded by astrocytes and microglia adjacent to the synapse. βS and γS have also been observed in the astrocyte and may provide beneficial roles. The astrocytic responsibility for degradation of αS as well as emerging evidence on possible astrocytic functions of βS and γS, warrant closer inspection on astrocyte-synuclein interactions at the synapse.
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Affiliation(s)
- Abigail J. Myers
- Neuroscience Program, Health Science Research Facility, University of Vermont, 149 Beaumont Ave., Burlington, VT 05405, USA
| | - Ayat Brahimi
- Biology Department, University of Hartford, 200 Bloomfield Ave., West Hartford, CT 06117, USA
| | - Imani J. Jenkins
- Biology Department, University of Hartford, 200 Bloomfield Ave., West Hartford, CT 06117, USA
| | - Andrew O. Koob
- Biology Department, University of Hartford, 200 Bloomfield Ave., West Hartford, CT 06117, USA
- Correspondence: ; Tel.: +1-860-768-5780
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53
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Ozoran H, Srinivasan R. Astrocytes and Alpha-Synuclein: Friend or Foe? JOURNAL OF PARKINSON'S DISEASE 2023; 13:1289-1301. [PMID: 38007674 PMCID: PMC10741342 DOI: 10.3233/jpd-230284] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/21/2023] [Indexed: 11/27/2023]
Abstract
Despite its devastating disease burden and alarming prevalence, the etiology of Parkinson's disease (PD) remains to be completely elucidated. PD is characterized by the degeneration of dopaminergic neurons in the substantia nigra pars compacta and this correlates with the accumulation of misfolded α-synuclein. While the aggregation of α-synuclein in the form of Lewy bodies or Lewy neurites is a well-established intraneuronal hallmark of the disease process, our understanding of the glial contribution to aberrant α-synuclein proteostasis is lacking. In this regard, restoring astrocyte function during early PD could offer a promising therapeutic avenue and understanding the involvement of astrocytes in handling/mishandling of α-synuclein is of particular interest. Here, we explore the growing body of scientific literature implicating aberrant astrocytic α-synuclein proteostasis with the seemingly inexorable pathological sequelae typifying PD. We also provide a perspective on how heterogeneity in the morphological relationship between astrocytes and neurons will need to be considered in the context of PD pathogenesis.
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Affiliation(s)
- Hakan Ozoran
- Clinical Medical School, University of Oxford, Oxford, UK
- Green Templeton College, University of Oxford, Oxford, UK
| | - Rahul Srinivasan
- Department of Neuroscience & Experimental Therapeutics, Texas A&M University School of Medicine, Bryan, TX, USA
- Texas A&M Institute for Neuroscience (TAMIN), College Station, TX, USA
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54
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Eraso‐Pichot A, Pouvreau S, Olivera‐Pinto A, Gomez‐Sotres P, Skupio U, Marsicano G. Endocannabinoid signaling in astrocytes. Glia 2023; 71:44-59. [PMID: 35822691 PMCID: PMC9796923 DOI: 10.1002/glia.24246] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 06/28/2022] [Accepted: 07/04/2022] [Indexed: 01/07/2023]
Abstract
The study of the astrocytic contribution to brain functions has been growing in popularity in the neuroscience field. In the last years, and especially since the demonstration of the involvement of astrocytes in synaptic functions, the astrocyte field has revealed multiple functions of these cells that seemed inconceivable not long ago. In parallel, cannabinoid investigation has also identified different ways by which cannabinoids are able to interact with these cells, modify their functions, alter their communication with neurons and impact behavior. In this review, we will describe the expression of different endocannabinoid system members in astrocytes. Moreover, we will relate the latest findings regarding cannabinoid modulation of some of the most relevant astroglial functions, namely calcium (Ca2+ ) dynamics, gliotransmission, metabolism, and inflammation.
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Affiliation(s)
- Abel Eraso‐Pichot
- U1215 Neurocentre MagendieInstitut national de la santé et de la recherche médicale (INSERM)BordeauxFrance,University of BordeauxBordeauxFrance
| | - Sandrine Pouvreau
- U1215 Neurocentre MagendieInstitut national de la santé et de la recherche médicale (INSERM)BordeauxFrance,University of BordeauxBordeauxFrance
| | - Alexandre Olivera‐Pinto
- U1215 Neurocentre MagendieInstitut national de la santé et de la recherche médicale (INSERM)BordeauxFrance,University of BordeauxBordeauxFrance
| | - Paula Gomez‐Sotres
- U1215 Neurocentre MagendieInstitut national de la santé et de la recherche médicale (INSERM)BordeauxFrance,University of BordeauxBordeauxFrance
| | - Urszula Skupio
- U1215 Neurocentre MagendieInstitut national de la santé et de la recherche médicale (INSERM)BordeauxFrance,University of BordeauxBordeauxFrance
| | - Giovanni Marsicano
- U1215 Neurocentre MagendieInstitut national de la santé et de la recherche médicale (INSERM)BordeauxFrance,University of BordeauxBordeauxFrance
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55
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Goenaga J, Araque A, Kofuji P, Herrera Moro Chao D. Calcium signaling in astrocytes and gliotransmitter release. Front Synaptic Neurosci 2023; 15:1138577. [PMID: 36937570 PMCID: PMC10017551 DOI: 10.3389/fnsyn.2023.1138577] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2023] [Accepted: 02/16/2023] [Indexed: 03/06/2023] Open
Abstract
Glia are as numerous in the brain as neurons and widely known to serve supportive roles such as structural scaffolding, extracellular ionic and neurotransmitter homeostasis, and metabolic support. However, over the past two decades, several lines of evidence indicate that astrocytes, which are a type of glia, play active roles in neural information processing. Astrocytes, although not electrically active, can exhibit a form of excitability by dynamic changes in intracellular calcium levels. They sense synaptic activity and release neuroactive substances, named gliotransmitters, that modulate neuronal activity and synaptic transmission in several brain areas, thus impacting animal behavior. This "dialogue" between astrocytes and neurons is embodied in the concept of the tripartite synapse that includes astrocytes as integral elements of synaptic function. Here, we review the recent work and discuss how astrocytes via calcium-mediated excitability modulate synaptic information processing at various spatial and time scales.
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56
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Brandebura AN, Paumier A, Onur TS, Allen NJ. Astrocyte contribution to dysfunction, risk and progression in neurodegenerative disorders. Nat Rev Neurosci 2023; 24:23-39. [PMID: 36316501 DOI: 10.1038/s41583-022-00641-1] [Citation(s) in RCA: 105] [Impact Index Per Article: 105.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2022] [Indexed: 11/06/2022]
Abstract
There is increasing appreciation that non-neuronal cells contribute to the initiation, progression and pathology of diverse neurodegenerative disorders. This Review focuses on the role of astrocytes in disorders including Alzheimer disease, Parkinson disease, Huntington disease and amyotrophic lateral sclerosis. The important roles astrocytes have in supporting neuronal function in the healthy brain are considered, along with studies that have demonstrated how the physiological properties of astrocytes are altered in neurodegenerative disorders and may explain their contribution to neurodegeneration. Further, the question of whether in neurodegenerative disorders with specific genetic mutations these mutations directly impact on astrocyte function, and may suggest a driving role for astrocytes in disease initiation, is discussed. A summary of how astrocyte transcriptomic and proteomic signatures are altered during the progression of neurodegenerative disorders and may relate to functional changes is provided. Given the central role of astrocytes in neurodegenerative disorders, potential strategies to target these cells for future therapeutic avenues are discussed.
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Affiliation(s)
- Ashley N Brandebura
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Adrien Paumier
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Tarik S Onur
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA
| | - Nicola J Allen
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, CA, USA.
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57
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Myeong J, Klyachko VA. Rapid astrocyte-dependent facilitation amplifies multi-vesicular release in hippocampal synapses. Cell Rep 2022; 41:111820. [PMID: 36516768 PMCID: PMC9805313 DOI: 10.1016/j.celrep.2022.111820] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 09/30/2022] [Accepted: 11/21/2022] [Indexed: 12/15/2022] Open
Abstract
Synaptic facilitation is a major form of short-term plasticity typically driven by an increase in residual presynaptic calcium. Using near-total internal reflection fluorescence (near-TIRF) imaging of single vesicle release in cultured hippocampal synapses, we demonstrate a distinctive, release-dependent form of facilitation in which probability of vesicle release is higher following a successful glutamate release event than following a failure. This phenomenon has an onset of ≤500 ms and lasts several seconds, resulting in clusters of successful release events. The release-dependent facilitation requires neuronal contact with astrocytes and astrocytic glutamate uptake by EAAT1. It is not observed in neurons grown alone or in the presence of astrocyte-conditioned media. This form of facilitation dynamically amplifies multi-vesicular release. Facilitation-evoked release events exhibit spatial clustering and have a preferential localization toward the active zone center. These results uncover a rapid astrocyte-dependent form of facilitation acting via modulation of multi-vesicular release and displaying distinctive spatiotemporal properties.
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Affiliation(s)
- Jongyun Myeong
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63132, USA
| | - Vitaly A. Klyachko
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63132, USA,Lead contact,Correspondence:
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58
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Denizot A, Arizono M, Nägerl UV, Berry H, De Schutter E. Control of Ca 2+ signals by astrocyte nanoscale morphology at tripartite synapses. Glia 2022; 70:2378-2391. [PMID: 36097958 PMCID: PMC9825906 DOI: 10.1002/glia.24258] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Revised: 07/20/2022] [Accepted: 07/28/2022] [Indexed: 01/11/2023]
Abstract
Much of the Ca2+ activity in astrocytes is spatially restricted to microdomains and occurs in fine processes that form a complex anatomical meshwork, the so-called spongiform domain. A growing body of literature indicates that those astrocytic Ca2+ signals can influence the activity of neuronal synapses and thus tune the flow of information through neuronal circuits. Because of technical difficulties in accessing the small spatial scale involved, the role of astrocyte morphology on Ca2+ microdomain activity remains poorly understood. Here, we use computational tools and idealized 3D geometries of fine processes based on recent super-resolution microscopy data to investigate the mechanistic link between astrocytic nanoscale morphology and local Ca2+ activity. Simulations demonstrate that the nano-morphology of astrocytic processes powerfully shapes the spatio-temporal properties of Ca2+ signals and promotes local Ca2+ activity. The model predicts that this effect is attenuated upon astrocytic swelling, hallmark of brain diseases, which we confirm experimentally in hypo-osmotic conditions. Upon repeated neurotransmitter release events, the model predicts that swelling hinders astrocytic signal propagation. Overall, this study highlights the influence of the complex morphology of astrocytes at the nanoscale and its remodeling in pathological conditions on neuron-astrocyte communication at so-called tripartite synapses, where astrocytic processes come into close contact with pre- and postsynaptic structures.
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Affiliation(s)
- Audrey Denizot
- Computational Neuroscience UnitOkinawa Institute of Science and TechnologyOnna‐SonJapan
| | - Misa Arizono
- Interdisciplinary Institute for NeuroscienceUniversité de BordeauxBordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS UMR 5297BordeauxFrance
- Department of PharmacologyKyoto University Graduate School of MedicineKyotoJapan
| | - U. Valentin Nägerl
- Interdisciplinary Institute for NeuroscienceUniversité de BordeauxBordeauxFrance
- Interdisciplinary Institute for NeuroscienceCNRS UMR 5297BordeauxFrance
| | - Hugues Berry
- LIRIS, UMR5205 CNRSUniv LyonVilleurbanneFrance
- INRIAVilleurbanneFrance
| | - Erik De Schutter
- Computational Neuroscience UnitOkinawa Institute of Science and TechnologyOnna‐SonJapan
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59
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Li J, Feng P, Zhao L, Chen J, Du M, Song J, Wu Y. Transition behavior of the seizure dynamics modulated by the astrocyte inositol triphosphate noise. CHAOS (WOODBURY, N.Y.) 2022; 32:113121. [PMID: 36456345 DOI: 10.1063/5.0124123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Accepted: 10/17/2022] [Indexed: 06/17/2023]
Abstract
Epilepsy is a neurological disorder with recurrent seizures, which convey complex dynamical characteristics including chaos and randomness. Until now, the underlying mechanism has not been fully elucidated, especially the bistable property beneath the epileptic random induction phenomena in certain conditions. Inspired by the recent finding that astrocyte GTPase-activating protein (G-protein)-coupled receptors could be involved in stochastic epileptic seizures, we proposed a neuron-astrocyte network model, incorporating the noise of the astrocytic second messenger, inositol triphosphate (IP3) that is modulated by G-protein-coupled receptor activation. Based on this model, we have statistically analyzed the transitions of epileptic seizures by performing repeatable simulation trials. Our simulation results show that the increase in the IP3 noise intensity induces depolarization-block epileptic seizures together with an increase in neuronal firing frequency, consistent with corresponding experiments. Meanwhile, the bistable states of the seizure dynamics were present under certain noise intensities, during which the neuronal firing pattern switches between regular sparse spiking and epileptic seizure states. This random presence of epileptic seizures is absent when the noise intensity continues to increase, accompanying with an increase in the epileptic depolarization block duration. The simulation results also shed light on the fact that calcium signals in astrocytes play significant roles in the pattern formations of the epileptic seizure. Our results provide a potential pathway for understanding the epileptic randomness in certain conditions.
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Affiliation(s)
- Jiajia Li
- College of Information and Control Engineering, Xi'an University of Architecture and Technology, Shaanxi, Xi'an 710055, China
| | - Peihua Feng
- State Key Laboratory for Strength and Vibration of Mechanical Structures, National Demonstration Center for Experimental Mechanics Education, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
| | - Liang Zhao
- College of Information and Control Engineering, Xi'an University of Architecture and Technology, Shaanxi, Xi'an 710055, China
| | - Junying Chen
- College of Information and Control Engineering, Xi'an University of Architecture and Technology, Shaanxi, Xi'an 710055, China
| | - Mengmeng Du
- School of Mathematics and Data Science, Shaanxi University of Science and Technology, Xi'an 710021, China
| | - Jian Song
- Department of Neurosurgery, Wuhan General Hospital of PLA, Wuhan 430070, China
| | - Ying Wu
- State Key Laboratory for Strength and Vibration of Mechanical Structures, National Demonstration Center for Experimental Mechanics Education, School of Aerospace Engineering, Xi'an Jiaotong University, Xi'an 710049, China
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60
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Kruyer A. Astrocyte Heterogeneity in Regulation of Synaptic Activity. Cells 2022; 11:cells11193135. [PMID: 36231097 PMCID: PMC9562199 DOI: 10.3390/cells11193135] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/02/2022] [Accepted: 10/02/2022] [Indexed: 02/07/2023] Open
Abstract
Our awareness of the number of synapse regulatory functions performed by astroglia is rapidly expanding, raising interesting questions regarding astrocyte heterogeneity and specialization across brain regions. Whether all astrocytes are poised to signal in a multitude of ways, or are instead tuned to surrounding synapses and how astroglial signaling is altered in psychiatric and cognitive disorders are fundamental questions for the field. In recent years, molecular and morphological characterization of astroglial types has broadened our ability to design studies to better analyze and manipulate specific functions of astroglia. Recent data emerging from these studies will be discussed in depth in this review. I also highlight remaining questions emerging from new techniques recently applied toward understanding the roles of astrocytes in synapse regulation in the adult brain.
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Affiliation(s)
- Anna Kruyer
- Department of Neuroscience, Medical University of South Carolina, Charleston, SC 29425, USA
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61
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Pittolo S, Yokoyama S, Willoughby DD, Taylor CR, Reitman ME, Tse V, Wu Z, Etchenique R, Li Y, Poskanzer KE. Dopamine activates astrocytes in prefrontal cortex via α1-adrenergic receptors. Cell Rep 2022; 40:111426. [PMID: 36170823 PMCID: PMC9555850 DOI: 10.1016/j.celrep.2022.111426] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 07/19/2022] [Accepted: 09/08/2022] [Indexed: 12/31/2022] Open
Abstract
The prefrontal cortex (PFC) is a hub for cognitive control, and dopamine profoundly influences its functions. In other brain regions, astrocytes sense diverse neurotransmitters and neuromodulators and, in turn, orchestrate regulation of neuroactive substances. However, basic physiology of PFC astrocytes, including which neuromodulatory signals they respond to and how they contribute to PFC function, is unclear. Here, we characterize divergent signaling signatures in mouse astrocytes of the PFC and primary sensory cortex, which show differential responsiveness to locomotion. We find that PFC astrocytes express receptors for dopamine but are unresponsive through the Gs/Gi-cAMP pathway. Instead, fast calcium signals in PFC astrocytes are time locked to dopamine release and are mediated by α1-adrenergic receptors both ex vivo and in vivo. Further, we describe dopamine-triggered regulation of extracellular ATP at PFC astrocyte territories. Thus, we identify astrocytes as active players in dopaminergic signaling in the PFC, contributing to PFC function though neuromodulator receptor crosstalk. Pittolo et al. demonstrate that the neuromodulator dopamine targets astrocytes, a type of brain cell, via receptors specific to another neuromodulator—norepinephrine. This study provides groundwork on how dopamine affects non-neuronal brain cells and suggests that crosstalk between neuromodulatory pathways occurs in vivo, with possible clinical implications.
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Affiliation(s)
- Silvia Pittolo
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Sae Yokoyama
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Drew D Willoughby
- 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
| | - Charlotte R Taylor
- 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
| | - Michael E Reitman
- 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
| | - Vincent Tse
- Department of Biochemistry & Biophysics, University of California, San Francisco, San Francisco, CA, USA
| | - Zhaofa Wu
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - Roberto Etchenique
- Departamento de Química Inorgánica, Analítica y Química Física, INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, CONICET, Intendente Güiraldes 2160, Ciudad Universitaria, Pabellón 2, C1428EGA, Buenos Aires, Argentina
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing 100871, China; Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
| | - 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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62
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Characterization of Macrophage-Tropic HIV-1 Infection of Central Nervous System Cells and the Influence of Inflammation. J Virol 2022; 96:e0095722. [PMID: 35975998 PMCID: PMC9472603 DOI: 10.1128/jvi.00957-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
HIV-1 infection within the central nervous system (CNS) includes evolution of the virus, damaging inflammatory cascades, and the involvement of multiple cell types; however, our understanding of how Env tropism and inflammation can influence CNS infectivity is incomplete. In this study, we utilize macrophage-tropic and T cell-tropic HIV-1 Env proteins to establish accurate infection profiles for multiple CNS cells under basal and interferon alpha (IFN-α) or lipopolysaccharide (LPS)-induced inflammatory states. We found that macrophage-tropic viruses confer entry advantages in primary myeloid cells, including monocyte-derived macrophage, microglia, and induced pluripotent stem cell (iPSC)-derived microglia. However, neither macrophage-tropic or T cell-tropic HIV-1 Env proteins could mediate infection of astrocytes or neurons, and infection was not potentiated by induction of an inflammatory state in these cells. Additionally, we found that IFN-α and LPS restricted replication in myeloid cells, and IFN-α treatment prior to infection with vesicular stomatitis virus G protein (VSV G) Envs resulted in a conserved antiviral response across all CNS cell types. Further, using RNA sequencing (RNA-seq), we found that only myeloid cells express HIV-1 entry receptor/coreceptor transcripts at a significant level and that these transcripts in select cell types responded only modestly to inflammatory signals. We profiled the transcriptional response of multiple CNS cells to inflammation and found 57 IFN-induced genes that were differentially expressed across all cell types. Taken together, these data focus attention on the cells in the CNS that are truly permissive to HIV-1, further highlight the role of HIV-1 Env evolution in mediating infection in the CNS, and point to limitations in using model cell types versus primary cells to explore features of virus-host interaction. IMPORTANCE The major feature of HIV-1 pathogenesis is the induction of an immunodeficient state in the face of an enhanced state of inflammation. However, for many of those infected, there can be an impact on the central nervous system (CNS) resulting in a wide range of neurocognitive defects. Here, we use a highly sensitive and quantitative assay for viral infectivity to explore primary and model cell types of the brain for their susceptibility to infection using viral entry proteins derived from the CNS. In addition, we examine the ability of an inflammatory state to alter infectivity of these cells. We find that myeloid cells are the only cell types in the CNS that can be infected and that induction of an inflammatory state negatively impacts viral infection across all cell types.
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63
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Glutamate Signaling and Filopodiagenesis of Astrocytoma Cells in Brain Cancers: Survey and Questions. Cells 2022; 11:cells11172657. [PMID: 36078065 PMCID: PMC9454653 DOI: 10.3390/cells11172657] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 08/19/2022] [Accepted: 08/24/2022] [Indexed: 11/22/2022] Open
Abstract
Astrocytes are non-excitable cells in the CNS that can cause life-threatening astrocytoma tumors when they transform to cancerous cells. Perturbed homeostasis of the neurotransmitter glutamate is associated with astrocytoma tumor onset and progression, but the factors that govern this phenomenon are less known. Herein, we review possible mechanisms by which glutamate may act in facilitating the growth of projections in astrocytic cells. This review discusses the similarities and differences between the morphology of astrocytes and astrocytoma cells, and the role that dysregulation in glutamate and calcium signaling plays in the aberrant morphology of astrocytoma cells. Converging reports suggest that ionotropic glutamate receptors and voltage-gated calcium channels expressed in astrocytes may be responsible for the abnormal filopodiagenesis or process extension leading to astrocytoma cells’ infiltration throughout the brain.
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64
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Looking to the stars for answers: Strategies for determining how astrocytes influence neuronal activity. Comput Struct Biotechnol J 2022; 20:4146-4156. [PMID: 36016711 PMCID: PMC9379862 DOI: 10.1016/j.csbj.2022.07.052] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/29/2022] [Accepted: 07/29/2022] [Indexed: 11/24/2022] Open
Abstract
Astrocytes are critical components of neural circuits positioned in close proximity to the synapse, allowing them to rapidly sense and respond to neuronal activity. One repeatedly observed biomarker of astroglial activation is an increase in intracellular Ca2+ levels. These astroglial Ca2+ signals are often observed spreading throughout various cellular compartments from perisynaptic astroglial processes, to major astrocytic branches and on to the soma or cell body. Here we review recent evidence demonstrating that astrocytic Ca2+ events are remarkably heterogeneous in both form and function, propagate through the astroglial syncytia, and are directly linked to the ability of astroglia to influence local neuronal activity. As many of the cellular functions of astroglia can be linked to intracellular Ca2+ signaling, and the diversity and heterogeneity of these events becomes more apparent, there is an increasing need for novel experimental strategies designed to better understand the how these signals evolve in parallel with neuronal activity. Here we review the recent advances that enable the characterization of both subcellular and population-wide astrocytic Ca2+ dynamics. Additionally, we also outline the experimental design required for simultaneous in vivo Ca2+ imaging in the context of neuronal or astroglial manipulation, highlighting new experimental strategies made possible by recent advances in viral vector, imaging, and quantification technologies. Through combined usage of these reagents and methodologies, we provide a conceptual framework to study how astrocytes functionally integrate into neural circuits and to what extent they influence and direct the synaptic activity underlying behavioral responses.
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Insulin-like growth factor 1 regulates excitatory synaptic transmission in pyramidal neurons from adult prefrontal cortex. Neuropharmacology 2022; 217:109204. [PMID: 35931212 DOI: 10.1016/j.neuropharm.2022.109204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 07/07/2022] [Accepted: 07/25/2022] [Indexed: 11/24/2022]
Abstract
Insulin-like growth factor 1 (IGF1) influences synaptic function in addition to its role in brain development and aging. Although the expression levels of IGF1 and IGF1 receptor (IGF1R) peak during development and decline with age, the adult brain has abundant IGF1 or IGF1R expression. Studies reveal that IGF1 regulates the synaptic transmission in neurons from young animals. However, the action of IGF1 on neurons in the adult brain is still unclear. Here, we used prefrontal cortical (PFC) slices from adult mice (∼8 weeks old) to characterize the role of IGF1 on excitatory synaptic transmission in pyramidal neurons and the underlying molecular mechanisms. We first validated IGF1R expression in pyramidal neurons using translating ribosomal affinity purification assay. Then, using whole-cell patch-clamp recording, we found that IGF1 attenuated the amplitude of evoked excitatory postsynaptic current (EPSC) without affecting the frequency and amplitude of miniature EPSC. Furthermore, this decrease in excitatory neurotransmission was blocked by pharmacological inhibition of IGF1R or conditionally knockdown of IGF1R in PFC pyramidal neurons. In addition, we determined that IGF1-induced decrease of EPSC amplitude was due to postsynaptic effect (internalization of a-amino-3-hydroxy-5-methyl-4- isoxazolepropionic acid receptors [AMPAR]) rather than presynaptic glutamate release. Finally, we found that inhibition of metabotropic glutamate receptor subtype-1 (mGluR1) abolished IGF1-induced attenuation of evoked EPSC amplitude and decrease of AMPAR expression at synaptic membrane, suggesting mGluR1-mediated endocytosis of AMPAR was involved. Taken together, these data provide the first evidence that IGF1 regulates excitatory synaptic transmission in adult PFC via the interaction between IGF1R-dependent signaling pathway and mGluR1-mediated AMPAR endocytosis.
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Chen W, Meng S, Han Y, Shi J. Astrocytes: the neglected stars in the central nervous system and drug addiction. MEDICAL REVIEW (BERLIN, GERMANY) 2022; 2:417-426. [PMID: 37724324 PMCID: PMC10388769 DOI: 10.1515/mr-2022-0006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 05/31/2022] [Indexed: 09/20/2023]
Abstract
With the advent of improved tools to examine the astrocytes, which have been believed to play a supportive role in the central nervous system (CNS) for years, their participation in the operation of the CNS and drug addiction was unveiled. Assisting the formation and function of the CNS, astrocytes are involved in physiological and pathological brain activities. Drug addiction is a pervasive psychiatric disorder, characterized by compulsive drug-taking behavior and high rate of relapse, impacting individual health and society stability and safety. When exposed to drugs of abuse, astrocytes go through a series of alterations, contributing to the development of addiction. Here we review how astrocytes contribute to the CNS and drug addiction. We hope that understanding the interaction between addictive drugs and astrocytes may help discover new mechanisms underlying the addiction and produce novel therapeutic treatments.
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Affiliation(s)
- Wenjun Chen
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, China
| | - Shiqiu Meng
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, China
| | - Ying Han
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, China
| | - Jie Shi
- National Institute on Drug Dependence and Beijing Key Laboratory of Drug Dependence, Peking University, Beijing, China
- The State Key Laboratory of Natural and Biomimetic Drugs, Peking University, Beijing 100191, China
- The Key Laboratory for Neuroscience of the Ministry of Education and Health, Peking University, Beijing 100191, China
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67
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Pillai AG, Nadkarni S. Amyloid pathology disrupts gliotransmitter release in astrocytes. PLoS Comput Biol 2022; 18:e1010334. [PMID: 35913987 PMCID: PMC9371304 DOI: 10.1371/journal.pcbi.1010334] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Revised: 08/11/2022] [Accepted: 06/28/2022] [Indexed: 01/11/2023] Open
Abstract
Accumulation of amyloid-beta (Aβ) is associated with synaptic dysfunction and destabilization of astrocytic calcium homeostasis. A growing body of evidence support astrocytes as active modulators of synaptic transmission via calcium-mediated gliotransmission. However, the details of mechanisms linking Aβ signaling, astrocytic calcium dynamics, and gliotransmission are not known. We developed a biophysical model that describes calcium signaling and the ensuing gliotransmitter release from a single astrocytic process when stimulated by glutamate release from hippocampal neurons. The model accurately captures the temporal dynamics of microdomain calcium signaling and glutamate release via both kiss-and-run and full-fusion exocytosis. We investigate the roles of two crucial calcium regulating machineries affected by Aβ: plasma-membrane calcium pumps (PMCA) and metabotropic glutamate receptors (mGluRs). When we implemented these Aβ-affected molecular changes in our astrocyte model, it led to an increase in the rate and synchrony of calcium events. Our model also reproduces several previous findings of Aβ associated aberrant calcium activity, such as increased intracellular calcium level and increased spontaneous calcium activity, and synchronous calcium events. The study establishes a causal link between previous observations of hyperactive astrocytes in Alzheimer’s disease (AD) and Aβ-induced modifications in mGluR and PMCA functions. Analogous to neurotransmitter release, gliotransmitter exocytosis closely tracks calcium changes in astrocyte processes, thereby guaranteeing tight control of synaptic signaling by astrocytes. However, the downstream effects of AD-related calcium changes in astrocytes on gliotransmitter release are not known. Our results show that enhanced rate of exocytosis resulting from modified calcium signaling in astrocytes leads to a rapid depletion of docked vesicles that disrupts the crucial temporal correspondence between a calcium event and vesicular release. We propose that the loss of temporal correspondence between calcium events and gliotransmission in astrocytes pathologically alters astrocytic modulation of synaptic transmission in the presence of Aβ accumulation. Signaling by astrocytes is critical to information processing at synapses, and its aberration plays a central role in neurological diseases, especially Alzheimer’s disease (AD). A complete characterization of calcium signaling and the resulting pattern of gliotransmitter release from fine astrocytic processes are not accessible to current experimental tools. We developed a biophysical model that can quantitatively describe signaling by astrocytes in response to a wide range of synaptic activity. We show that AD-related molecular alterations disrupt the concurrence of calcium and gliotransmitter release events, a characterizing feature that enables astrocytes to influence synaptic signaling.
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Affiliation(s)
| | - Suhita Nadkarni
- Indian Institute of Science Education and Research Pune, Pune, India
- * E-mail:
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68
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Covelo A, Badoual A, Denizot A. Reinforcing Interdisciplinary Collaborations to Unravel the Astrocyte "Calcium Code". J Mol Neurosci 2022; 72:1443-1455. [PMID: 35543801 PMCID: PMC9293817 DOI: 10.1007/s12031-022-02006-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/01/2022] [Indexed: 11/19/2022]
Abstract
In this review article, we present the major insights from and challenges faced in the acquisition, analysis and modeling of astrocyte calcium activity, aiming at bridging the gap between those fields to crack the complex astrocyte "Calcium Code". We then propose strategies to reinforce interdisciplinary collaborative projects to unravel astrocyte function in health and disease.
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Affiliation(s)
- Ana Covelo
- Institut National de la Santé et de la Recherche Médicale (INSERM), U1215, NeuroCentre Magendie, 33077, Bordeaux, France
- University of Bordeaux, Bordeaux, 33077, France
| | - Anaïs Badoual
- SERPICO Project-Team, Inria Centre Rennes-Bretagne Atlantique, Rennes Cedex, 35042, France
- SERPICO/STED Team, UMR144 CNRS Institut Curie, PSL Research University, Sorbonne Universités, Paris, 75005, France
| | - Audrey Denizot
- Computational Neuroscience Unit, Okinawa Institute of Science and Technology, Onna, 904-0495, Japan.
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69
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Shen W, Li Z, Tang Y, Han P, Zhu F, Dong J, Ma T, Zhao K, Zhang X, Xie Y, Zeng LH. Somatostatin interneurons inhibit excitatory transmission mediated by astrocytic GABA B and presynaptic GABA B and adenosine A 1 receptors in the hippocampus. J Neurochem 2022; 163:310-326. [PMID: 35775994 DOI: 10.1111/jnc.15662] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 06/14/2022] [Accepted: 06/21/2022] [Indexed: 11/29/2022]
Abstract
GABAergic network activity has been established to be involved in numerous physiological processes and pathological conditions. Extensive studies have corroborated that GABAergic network activity regulates excitatory synaptic networks by activating presynaptic GABAB receptors (GABAB Rs). It is well documented that astrocytes express GABAB Rs and respond to GABAergic network activity. However, little is known about whether astrocytic GABAB Rs regulate excitatory synaptic transmission mediated by GABAergic network activity. To address this issue, we combined whole-cell recordings, optogenetics, calcium imaging, and pharmacological approaches to specifically activate hippocampal somatostatin-expressing interneurons (SOM-INs), a type of interneuron that targets pyramidal cell dendrites, while monitoring excitatory synaptic transmission in CA1 pyramidal cells. We found that optogenetic stimulation of SOM-INs increases astrocyte Ca2+ signaling via the activation of astrocytic GABAB Rs and GAT-3. SOM-INs depress excitatory neurotransmission by activating presynaptic GABAB Rs and astrocytic GABAB Rs, the latter inducing the release of ATP/adenosine. In turn, adenosine inhibits excitatory synaptic transmission by activating presynaptic adenosine A1 receptors (A1 Rs). Overall, our results reveal a novel mechanism that SOM-INs activation-induced synaptic depression is partially mediated by the activation of astrocytic GABAB Rs.
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Affiliation(s)
- Weida Shen
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Zijing Li
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Yejiao Tang
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Pufan Han
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Feng Zhu
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Jingyin Dong
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Tianyu Ma
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Kai Zhao
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Xin Zhang
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
| | - Yicheng Xie
- The Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China
| | - Ling-Hui Zeng
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang, China
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70
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Single-Cell RNA-Sequencing: Astrocyte and Microglial Heterogeneity in Health and Disease. Cells 2022; 11:cells11132021. [PMID: 35805105 PMCID: PMC9265979 DOI: 10.3390/cells11132021] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Revised: 06/17/2022] [Accepted: 06/21/2022] [Indexed: 12/13/2022] Open
Abstract
Astrocytes and microglia are non-neuronal cells that maintain homeostasis within the central nervous system via their capacity to regulate neuronal transmission and prune synapses. Both astrocytes and microglia can undergo morphological and transcriptomic changes in response to infection with human immunodeficiency virus (HIV). While both astrocytes and microglia can be infected with HIV, HIV viral proteins in the local environment can interact with and activate these cells. Given that both astrocytes and microglia play critical roles in maintaining neuronal function, it will be critical to have an understanding of their heterogeneity and to identify genes and mechanisms that modulate their responses to HIV. Heterogeneity may include a depletion or increase in one or more astrocyte or microglial subtypes in different regions of the brain or spine as well as the gain or loss of a specific function. Single-cell RNA sequencing (scRNA-seq) has emerged as a powerful tool that can be used to characterise these changes within a given population. The use of this method facilitates the identification of subtypes and changes in cellular transcriptomes that develop in response to activation and various disease processes. In this review, we will examine recent studies that have used scRNA-seq to explore astrocyte and microglial heterogeneity in neurodegenerative diseases including Alzheimer’s disease and amyotrophic lateral sclerosis as well as in response to HIV infection. A careful review of these studies will expand our current understanding of cellular heterogeneity at homeostasis and in response to specific disease states.
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71
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Choi IS, Kim JH, Jeong JY, Lee MG, Suk K, Jang IS. Astrocyte-derived adenosine excites sleep-promoting neurons in the ventrolateral preoptic nucleus: Astrocyte-neuron interactions in the regulation of sleep. Glia 2022; 70:1864-1885. [PMID: 35638268 DOI: 10.1002/glia.24225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 05/16/2022] [Accepted: 05/17/2022] [Indexed: 11/10/2022]
Abstract
Although ATP and/or adenosine derived from astrocytes are known to regulate sleep, the precise mechanisms underlying the somnogenic effects of ATP and adenosine remain unclear. We selectively expressed channelrhodopsin-2 (ChR2), a light-sensitive ion channel, in astrocytes within the ventrolateral preoptic nucleus (VLPO), which is an essential brain nucleus involved in sleep promotion. We then examined the effects of photostimulation of astrocytic ChR2 on neuronal excitability using whole-cell patch-clamp recordings in two functionally distinct types of VLPO neurons: sleep-promoting GABAergic projection neurons and non-sleep-promoting local GABAergic neurons. Optogenetic stimulation of VLPO astrocytes demonstrated opposite outcomes in the two types of VLPO neurons. It led to the inhibition of non-sleep-promoting neurons and excitation of sleep-promoting neurons. These responses were attenuated by blocking of either adenosine A1 receptors or tissue-nonspecific alkaline phosphatase (TNAP). In contrast, exogenous adenosine decreased the excitability of both VLPO neuron populations. Moreover, TNAP was expressed in galanin-negative VLPO neurons, but not in galanin-positive sleep-promoting projection neurons. Taken together, these results suggest that astrocyte-derived ATP is converted into adenosine by TNAP in non-sleep-promoting neurons. In turn, adenosine decreases the excitability of local GABAergic neurons, thereby increasing the excitability of sleep-promoting GABAergic projection neurons. We propose a novel mechanism involving astrocyte-neuron interactions in sleep regulation, wherein endogenous adenosine derived from astrocytes excites sleep-promoting VLPO neurons, and thus decreases neuronal excitability in arousal-related areas of the brain.
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Affiliation(s)
- In-Sun Choi
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, South Korea
| | - Jae-Hong Kim
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Ji-Young Jeong
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Maan-Gee Lee
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, South Korea.,Brain Science & Engineering Institute, Kyungpook National University, Daegu, South Korea
| | - Kyoungho Suk
- Department of Pharmacology, School of Medicine, Kyungpook National University, Daegu, South Korea.,Brain Science & Engineering Institute, Kyungpook National University, Daegu, South Korea
| | - Il-Sung Jang
- Department of Pharmacology, School of Dentistry, Kyungpook National University, Daegu, South Korea.,Brain Science & Engineering Institute, Kyungpook National University, Daegu, South Korea
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72
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Sobolczyk M, Boczek T. Astrocytic Calcium and cAMP in Neurodegenerative Diseases. Front Cell Neurosci 2022; 16:889939. [PMID: 35663426 PMCID: PMC9161693 DOI: 10.3389/fncel.2022.889939] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Accepted: 05/05/2022] [Indexed: 12/18/2022] Open
Abstract
It is commonly accepted that the role of astrocytes exceeds far beyond neuronal scaffold and energy supply. Their unique morphological and functional features have recently brough much attention as it became evident that they play a fundamental role in neurotransmission and interact with synapses. Synaptic transmission is a highly orchestrated process, which triggers local and transient elevations in intracellular Ca2+, a phenomenon with specific temporal and spatial properties. Presynaptic activation of Ca2+-dependent adenylyl cyclases represents an important mechanism of synaptic transmission modulation. This involves activation of the cAMP-PKA pathway to regulate neurotransmitter synthesis, release and storage, and to increase neuroprotection. This aspect is of paramount importance for the preservation of neuronal survival and functionality in several pathological states occurring with progressive neuronal loss. Hence, the aim of this review is to discuss mutual relationships between cAMP and Ca2+ signaling and emphasize those alterations at the Ca2+/cAMP crosstalk that have been identified in neurodegenerative disorders, such as Alzheimer's and Parkinson's disease.
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73
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Controlling synchronization of gamma oscillations by astrocytic modulation in a model hippocampal neural network. Sci Rep 2022; 12:6970. [PMID: 35484169 PMCID: PMC9050920 DOI: 10.1038/s41598-022-10649-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 04/11/2022] [Indexed: 12/13/2022] Open
Abstract
Recent in vitro and in vivo experiments demonstrate that astrocytes participate in the maintenance of cortical gamma oscillations and recognition memory. However, the mathematical understanding of the underlying dynamical mechanisms remains largely incomplete. Here we investigate how the interplay of slow modulatory astrocytic signaling with fast synaptic transmission controls coherent oscillations in the network of hippocampal interneurons that receive inputs from pyramidal cells. We show that the astrocytic regulation of signal transmission between neurons improves the firing synchrony and extends the region of coherent oscillations in the biologically relevant values of synaptic conductance. Astrocyte-mediated potentiation of inhibitory synaptic transmission markedly enhances the coherence of network oscillations over a broad range of model parameters. Astrocytic regulation of excitatory synaptic input improves the robustness of interneuron network gamma oscillations induced by physiologically relevant excitatory model drive. These findings suggest a mechanism, by which the astrocytes become involved in cognitive function and information processing through modulating fast neural network dynamics.
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74
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Astrocytes Modulate Somatostatin Interneuron Signaling in the Visual Cortex. Cells 2022; 11:cells11091400. [PMID: 35563706 PMCID: PMC9102536 DOI: 10.3390/cells11091400] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 04/14/2022] [Accepted: 04/18/2022] [Indexed: 02/05/2023] Open
Abstract
At glutamatergic synapses, astrocytes respond to the neurotransmitter glutamate with intracellular Ca2+ elevations and the release of gliotransmitters that modulate synaptic transmission. While the functional interactions between neurons and astrocytes have been intensively studied at glutamatergic synapses, the role of astrocytes at GABAergic synapses has been less investigated. In the present study, we combine optogenetics with 2-photon Ca2+ imaging experiments and patch-clamp recording techniques to investigate the signaling between Somatostatin (SST)-releasing GABAergic interneurons and astrocytes in brain slice preparations from the visual cortex (VCx). We found that an intense stimulation of SST interneurons evokes Ca2+ elevations in astrocytes that fundamentally depend on GABAB receptor (GABABR) activation, and that this astrocyte response is modulated by the neuropeptide somatostatin. After episodes of SST interneuron hyperactivity, we also observed a long-lasting reduction of the inhibitory postsynaptic current (IPSC) amplitude onto pyramidal neurons (PNs). This reduction of inhibitory tone (i.e., disinhibition) is counterbalanced by the activation of astrocytes that upregulate SST interneuron-evoked IPSC amplitude by releasing ATP that, after conversion to adenosine, activates A1Rs. Our results describe a hitherto unidentified modulatory mechanism of inhibitory transmission to VCx layer II/III PNs that involves the functional recruitment of astrocytes by SST interneuron signaling.
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75
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Zhou J, Geng Y, Su T, Wang Q, Ren Y, Zhao J, Fu C, Weber M, Lin H, Kaminker JS, Liu N, Sheng M, Chen Y. NMDA receptor-dependent prostaglandin-endoperoxide synthase 2 induction in neurons promotes glial proliferation during brain development and injury. Cell Rep 2022; 38:110557. [PMID: 35354047 DOI: 10.1016/j.celrep.2022.110557] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 08/16/2021] [Accepted: 03/01/2022] [Indexed: 12/25/2022] Open
Abstract
Astrocytes play critical roles in brain development and disease, but the mechanisms that regulate astrocyte proliferation are poorly understood. We report that astrocyte proliferation is bi-directionally regulated by neuronal activity via NMDA receptor (NMDAR) signaling in neurons. Prolonged treatment with an NMDAR antagonist reduced expression of cell-cycle-related genes in astrocytes in hippocampal cultures and suppressed astrocyte proliferation in vitro and in vivo, whereas neuronal activation promoted astrocyte proliferation, dependent on neuronal NMDARs. Expression of prostaglandin-endoperoxide synthase 2 (Ptgs2) is induced specifically in neurons by NMDAR activation and is required for activity-dependent astrocyte proliferation through its product, prostaglandin E2 (PGE2). NMDAR inhibition or Ptgs2 genetic ablation in mice reduced the proliferation of astrocytes and microglia induced by mild traumatic brain injury in the absence of secondary excitotoxicity-induced neuronal death. Our study defines an NMDAR-mediated signaling mechanism that allows trans-cellular control of glial proliferation by neurons in brain development and injury.
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Affiliation(s)
- Jia Zhou
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yang Geng
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China
| | - Tonghui Su
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiuyan Wang
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China
| | - Yongfei Ren
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Jing Zhao
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China; University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chaoying Fu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China
| | - Martin Weber
- Department of Neuroscience, Genentech, 1 DNA Way, South San Francisco, CA 94080, USA
| | - Han Lin
- Department of Neuroscience, Genentech, 1 DNA Way, South San Francisco, CA 94080, USA
| | - Joshua S Kaminker
- Department of Bioinformatics and Computational Biology, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA
| | - Nan Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China
| | - Morgan Sheng
- Department of Neuroscience, Genentech, 1 DNA Way, South San Francisco, CA 94080, USA.
| | - Yelin Chen
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 100 Haike Road, Pudong, Shanghai 201210, China.
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76
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Curreli S, Bonato J, Romanzi S, Panzeri S, Fellin T. Complementary encoding of spatial information in hippocampal astrocytes. PLoS Biol 2022; 20:e3001530. [PMID: 35239646 PMCID: PMC8893713 DOI: 10.1371/journal.pbio.3001530] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 01/05/2022] [Indexed: 01/28/2023] Open
Abstract
Calcium dynamics into astrocytes influence the activity of nearby neuronal structures. However, because previous reports show that astrocytic calcium signals largely mirror neighboring neuronal activity, current information coding models neglect astrocytes. Using simultaneous two-photon calcium imaging of astrocytes and neurons in the hippocampus of mice navigating a virtual environment, we demonstrate that astrocytic calcium signals encode (i.e., statistically reflect) spatial information that could not be explained by visual cue information. Calcium events carrying spatial information occurred in topographically organized astrocytic subregions. Importantly, astrocytes encoded spatial information that was complementary and synergistic to that carried by neurons, improving spatial position decoding when astrocytic signals were considered alongside neuronal ones. These results suggest that the complementary place dependence of localized astrocytic calcium signals may regulate clusters of nearby synapses, enabling dynamic, context-dependent variations in population coding within brain circuits.
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Affiliation(s)
- Sebastiano Curreli
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
| | - Jacopo Bonato
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
- Neural Computation Laboratory, Istituto Italiano di Tecnologia, Rovereto, Italy
- Department of Pharmacy and Biotechnology, University of Bologna, Bologna, Italy
| | - Sara Romanzi
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
- University of Genova, Genova, Italy
| | - Stefano Panzeri
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
- Neural Computation Laboratory, Istituto Italiano di Tecnologia, Rovereto, Italy
- Department of Excellence for Neural Information Processing, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf (UKE), Hamburg, Germany
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova, Italy
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77
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Pogodalla N, Winkler B, Klämbt C. Glial Tiling in the Insect Nervous System. Front Cell Neurosci 2022; 16:825695. [PMID: 35250488 PMCID: PMC8891220 DOI: 10.3389/fncel.2022.825695] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/06/2022] [Indexed: 11/30/2022] Open
Abstract
The Drosophila nervous system comprises a small number of well characterized glial cell classes. The outer surface of the central nervous system (CNS) is protected by a glial derived blood-brain barrier generated by perineurial and subperineurial glia. All neural stem cells and all neurons are engulfed by cortex glial cells. The inner neuropil region, that harbors all synapses and dendrites, is covered by ensheathing glia and infiltrated by astrocyte-like glial cells. All these glial cells show a tiled organization with an often remarkable plasticity where glial cells of one cell type invade the territory of the neighboring glial cell type upon its ablation. Here, we summarize the different glial tiling patterns and based on the different modes of cell-cell contacts we hypothesize that different molecular mechanisms underlie tiling of the different glial cell types.
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78
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Georgiou L, Echeverría A, Georgiou A, Kuhn B. Ca + activity maps of astrocytes tagged by axoastrocytic AAV transfer. SCIENCE ADVANCES 2022; 8:eabe5371. [PMID: 35138891 PMCID: PMC8827655 DOI: 10.1126/sciadv.abe5371] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 12/17/2021] [Indexed: 05/27/2023]
Abstract
Astrocytes exhibit localized Ca2+ microdomain (MD) activity thought to be actively involved in information processing in the brain. However, functional organization of Ca2+ MDs in space and time in relationship to behavior and neuronal activity is poorly understood. Here, we first show that adeno-associated virus (AAV) particles transfer anterogradely from axons to astrocytes. Then, we use this axoastrocytic AAV transfer to express genetically encoded Ca2+ indicators at high-contrast circuit specifically. In combination with two-photon microscopy and unbiased, event-based analysis, we investigated cortical astrocytes embedded in the vibrissal thalamocortical circuit. We found a wide range of Ca2+ MD signals, some of which were ultrafast (≤300 ms). Frequency and size of signals were extensively increased by locomotion but only subtly with sensory stimulation. The overlay of these signals resulted in behavior-dependent maps with characteristic Ca2+ activity hotspots, maybe representing memory engrams. These functional subdomains are stable over days, suggesting subcellular specialization.
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79
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Schroeder ME, Bassett DS, Meaney DF. A multilayer network model of neuron-astrocyte populations in vitro reveals mGluR5 inhibition is protective following traumatic injury. Netw Neurosci 2022; 6:499-527. [PMID: 35733423 PMCID: PMC9208011 DOI: 10.1162/netn_a_00227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 01/04/2022] [Indexed: 11/16/2022] Open
Abstract
Astrocytes communicate bidirectionally with neurons, enhancing synaptic plasticity and promoting the synchronization of neuronal microcircuits. Despite recent advances in understanding neuron-astrocyte signaling, little is known about astrocytic modulation of neuronal activity at the population level, particularly in disease or following injury. We used high-speed calcium imaging of mixed cortical cultures in vitro to determine how population activity changes after disruption of glutamatergic signaling and mechanical injury. We constructed a multilayer network model of neuron-astrocyte connectivity, which captured distinct topology and response behavior from single-cell-type networks. mGluR5 inhibition decreased neuronal activity, but did not on its own disrupt functional connectivity or network topology. In contrast, injury increased the strength, clustering, and efficiency of neuronal but not astrocytic networks, an effect that was not observed in networks pretreated with mGluR5 inhibition. Comparison of spatial and functional connectivity revealed that functional connectivity is largely independent of spatial proximity at the microscale, but mechanical injury increased the spatial-functional correlation. Finally, we found that astrocyte segments of the same cell often belong to separate functional communities based on neuronal connectivity, suggesting that astrocyte segments function as independent entities. Our findings demonstrate the utility of multilayer network models for characterizing the multiscale connectivity of two distinct but functionally dependent cell populations. Astrocytes communicate bidirectionally with neurons, enhancing synaptic plasticity and promoting the synchronization of neuronal microcircuits. We constructed a multilayer network model of neuron-astrocyte connectivity based on calcium activity in mixed cortical cultures, and used this model to evaluate the effect of glutamatergic inhibition and mechanical injury on network topology. We found that injury increased the strength, clustering, and efficiency of neuronal but not astrocytic networks, an effect that was not observed in injured networks pretreated with a glutamate receptor antagonist. Our findings demonstrate the utility of multilayer network models for characterizing the multiscale connectivity of two distinct but functionally dependent cell populations.
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Affiliation(s)
- Margaret E. Schroeder
- Department of Bioengineering, School of Engineering & Applied Science, University of Pennsylvania, Philadelphia, PA, USA
| | - Danielle S. Bassett
- Department of Bioengineering, School of Engineering & Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Department of Physics & Astronomy, College of Arts & Sciences, University of Pennsylvania, Philadelphia, PA, USA
- Department of Electrical & Systems Engineering, School of Engineering & Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
- Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - David F. Meaney
- Department of Bioengineering, School of Engineering & Applied Science, University of Pennsylvania, Philadelphia, PA, USA
- Department of Neurosurgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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80
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Mulkey DK, Olsen ML, Ou M, Cleary CM, Du G. Putative Roles of Astrocytes in General Anesthesia. Curr Neuropharmacol 2022; 20:5-15. [PMID: 33588730 PMCID: PMC9199541 DOI: 10.2174/1570159x19666210215120755] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 01/29/2021] [Accepted: 02/06/2021] [Indexed: 02/08/2023] Open
Abstract
General anesthetics are a mainstay of modern medicine, and although much progress has been made towards identifying molecular targets of anesthetics and neural networks contributing to endpoints of general anesthesia, our understanding of how anesthetics work remains unclear. Reducing this knowledge gap is of fundamental importance to prevent unwanted and life-threatening side-effects associated with general anesthesia. General anesthetics are chemically diverse, yet they all have similar behavioral endpoints, and so for decades, research has sought to identify a single underlying mechanism to explain how anesthetics work. However, this effort has given way to the 'multiple target hypothesis' as it has become clear that anesthetics target many cellular proteins, including GABAA receptors, glutamate receptors, voltage-independent K+ channels, and voltagedependent K+, Ca2+ and Na+ channels, to name a few. Yet, despite evidence that astrocytes are capable of modulating multiple aspects of neural function and express many anesthetic target proteins, they have been largely ignored as potential targets of anesthesia. The purpose of this brief review is to highlight the effects of anesthetic on astrocyte processes and identify potential roles of astrocytes in behavioral endpoints of anesthesia (hypnosis, amnesia, analgesia, and immobilization).
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Affiliation(s)
- Daniel K. Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, StorrsCT, USA;,Address correspondence to this author at the Department of Physiology and Neurobiology, University of Connecticut, Storrs CT, USA; E-mail:
| | | | | | - Colin M. Cleary
- Department of Physiology and Neurobiology, University of Connecticut, StorrsCT, USA
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81
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Di Castro MA, Volterra A. Astrocyte control of the entorhinal cortex-dentate gyrus circuit: Relevance to cognitive processing and impairment in pathology. Glia 2021; 70:1536-1553. [PMID: 34904753 PMCID: PMC9299993 DOI: 10.1002/glia.24128] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 11/28/2021] [Accepted: 11/30/2021] [Indexed: 12/20/2022]
Abstract
The entorhinal cortex-dentate gyrus circuit is centrally involved in memory processing conveying to the hippocampus spatial and nonspatial context information via, respectively, medial and lateral perforant path (MPP and LPP) excitatory projections onto dentate granule cells (GCs). Here, we review work of several years from our group showing that astrocytes sense local synaptic transmission and exert in turn a presynaptic control at PP-GC synapses. Modulation of neurotransmitter release probability by astrocytes sets basal synaptic strength and dynamic range for long-term potentiation of PP-GC synapses. Intriguingly, this astrocyte control is circuit-specific, being present only at MPP-GC (not LPP-GC) synapses, which selectively express atypical presynaptic N-methyl-D-aspartate receptors (NMDAR) suitable to activation by astrocyte-released glutamate. Moreover, the astrocytic control is peculiarly dependent on the cytokine TNFα, which at constitutive levels acts as a gating factor for the astrocyte signaling. During inflammation/infection processes, increased levels of TNFα lead to uncontrolled astrocyte glutamate release, altered PP-GC circuit processing and, ultimately, impaired contextual memory performance. The TNFα-dependent pathological switch of the synaptic control from astrocytes and its deleterious consequences are observed in animal models of HIV brain infection and multiple sclerosis, conditions both known to cause cognitive disturbances in up to 50% of patients. The review also discusses open issues related to the identified astrocytic pathway: its role in contextual memory processing, potential damaging role in Alzheimer's disease, the existence of vesicular glutamate release from DG astrocytes, and the possible synaptic-like connectivity between astrocytic output sites and PP receptive sites.
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Affiliation(s)
- Maria Amalia Di Castro
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland.,Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Andrea Volterra
- Department of Fundamental Neuroscience, University of Lausanne, Lausanne, Switzerland
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82
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Fear learning induces α7-nicotinic acetylcholine receptor-mediated astrocytic responsiveness that is required for memory persistence. Nat Neurosci 2021; 24:1686-1698. [PMID: 34782794 DOI: 10.1038/s41593-021-00949-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/27/2021] [Indexed: 01/28/2023]
Abstract
Memory persistence is a fundamental cognitive process for guiding behaviors and is considered to rely mostly on neuronal and synaptic plasticity. Whether and how astrocytes contribute to memory persistence is largely unknown. Here, by using two-photon Ca2+ imaging in head-fixed mice and fiber photometry in freely moving mice, we show that aversive sensory stimulation activates α7-nicotinic acetylcholine receptors (nAChRs) in a subpopulation of astrocytes in the auditory cortex. We demonstrate that fear learning causes the de novo induction of sound-evoked Ca2+ transients in these astrocytes. The astrocytic responsiveness persisted over days along with fear memory and disappeared in animals that underwent extinction of learned freezing behavior. Conditional genetic deletion of α7-nAChRs in astrocytes significantly impaired fear memory persistence. We conclude that learning-acquired, α7-nAChR-dependent astrocytic responsiveness is an integral part of the cellular substrate underlying memory persistence.
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83
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Toro-Fernández LF, Zuluaga-Monares JC, Saldarriaga-Cartagena AM, Cardona-Gómez GP, Posada-Duque R. Targeting CDK5 in Astrocytes Promotes Calcium Homeostasis Under Excitotoxic Conditions. Front Cell Neurosci 2021; 15:643717. [PMID: 34790098 PMCID: PMC8591049 DOI: 10.3389/fncel.2021.643717] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 10/05/2021] [Indexed: 11/22/2022] Open
Abstract
Glutamate excitotoxicity triggers overactivation of CDK5 and increases calcium influx in neural cells, which promotes dendritic retraction, spine loss, increased mitochondrial calcium from the endoplasmic reticulum, and neuronal death. Our previous studies showed that CDK5 knockdown (KD) in astrocytes improves neurovascular integrity and cognitive functions and exerts neuroprotective effects. However, how CDK5-targeted astrocytes affect calcium regulation and whether this phenomenon is associated with changes in neuronal plasticity have not yet been analyzed. In this study, CDK5 KD astrocytes transplanted in CA3 remained at the injection site without proliferation, regulated calcium in the CA1 hippocampal region after excitotoxicity by glutamate in ex vivo hippocampal slices, improving synapsin and PSD95 clustering. These CDK5 KD astrocytes induced astrocyte stellation and neuroprotection after excitotoxicity induced by glutamate in vitro. Also, these effects were supported by CDK5 inhibition (CDK5i) in vitro through intracellular stabilization of calcium levels in astrocytes. Additionally, these cells in cocultures restored calcium homeostasis in neurons, redistributing calcium from somas to dendrites, accompanied by dendrite branching, higher dendritic spines and synapsin-PSD95 clustering. In summary, induction of calcium homeostasis at the CA1 hippocampal area by CDK5 KD astrocytes transplanted in the CA3 area highlights the role of astrocytes as a cell therapy target due to CDK5-KD astrocyte-mediated synaptic clustering, calcium spreading regulation between both areas, and recovery of the intracellular astrocyte-neuron calcium imbalance and plasticity impairment generated by glutamate excitotoxicity.
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Affiliation(s)
- Luisa Fernanda Toro-Fernández
- Instituto de Biología, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellín, Colombia.,Área de Neurobiología Celular y Molecular, Grupo de Neurociencias de Antioquia, Universidad de Antioquia, Medellín, Colombia
| | - Juan Camilo Zuluaga-Monares
- Instituto de Biología, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellín, Colombia.,Área de Neurobiología Celular y Molecular, Grupo de Neurociencias de Antioquia, Universidad de Antioquia, Medellín, Colombia
| | - Ana María Saldarriaga-Cartagena
- Instituto de Biología, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellín, Colombia.,Área de Neurobiología Celular y Molecular, Grupo de Neurociencias de Antioquia, Universidad de Antioquia, Medellín, Colombia
| | - Gloria Patricia Cardona-Gómez
- Área de Neurobiología Celular y Molecular, Grupo de Neurociencias de Antioquia, Universidad de Antioquia, Medellín, Colombia
| | - Rafael Posada-Duque
- Instituto de Biología, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia, Medellín, Colombia.,Área de Neurobiología Celular y Molecular, Grupo de Neurociencias de Antioquia, Universidad de Antioquia, Medellín, Colombia
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84
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Orts-Del'Immagine A, Dhanasekar M, Lejeune FX, Roussel J, Wyart C. A norepinephrine-dependent glial calcium wave travels in the spinal cord upon acoustovestibular stimuli. Glia 2021; 70:491-507. [PMID: 34773299 DOI: 10.1002/glia.24118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/27/2021] [Accepted: 11/01/2021] [Indexed: 02/06/2023]
Abstract
Although calcium waves have been widely observed in glial cells, their occurrence in vivo during behavior remains less understood. Here, we investigated the recruitment of glial cells in the hindbrain and spinal cord after acousto-vestibular (AV) stimuli triggering escape responses using in vivo population calcium imaging in larval zebrafish. We observed that gap-junction-coupled spinal glial network exhibits large and homogenous calcium increases that rose in the rostral spinal cord and propagated bi-directionally toward the spinal cord and toward the hindbrain. Spinal glial calcium waves were driven by the recruitment of neurons and in particular, of noradrenergic signaling acting through α-adrenergic receptors. Noradrenergic neurons of the medulla-oblongata (NE-MO) were revealed in the vicinity of where the calcium wave started. NE-MO were recruited upon AV stimulation and sent dense axonal projections in the rostro-lateral spinal cord, suggesting these cells could trigger the glial wave to propagate down the spinal cord. Altogether, our results revealed that a simple AV stimulation is sufficient to recruit noradrenergic neurons in the brainstem that trigger in the rostral spinal cord two massive glial calcium waves, one traveling caudally in the spinal cord and another rostrally into the hindbrain.
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Affiliation(s)
| | | | | | | | - Claire Wyart
- Institut du cerveau, Sorbonne Université, Paris, France
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85
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Lalo U, Koh W, Lee CJ, Pankratov Y. The tripartite glutamatergic synapse. Neuropharmacology 2021; 199:108758. [PMID: 34433089 DOI: 10.1016/j.neuropharm.2021.108758] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/25/2021] [Accepted: 08/20/2021] [Indexed: 12/31/2022]
Abstract
Astroglial cells were long considered as structural and metabolic supporting cells are which do not directly participate in information processing in the brain. Discoveries of responsiveness of astrocytes to synaptically-released glutamate and their capability to release agonists of glutamate receptors awakened extensive studies of glia-neuron communications and led to the revolutionary changes in our understanding of brain cellular networks. Nowadays, astrocytes are widely acknowledged as inseparable element of glutamatergic synapses and role for glutamatergic astrocyte-neuron interactions in the brain computation is emerging. Astroglial glutamate receptors, in particular of NMDA, mGluR3 and mGluR5 types, can activate a variety of molecular cascades leading astroglial-driven modulation of extracellular levels of glutamate and activity of neuronal glutamate receptors. Their preferential location to the astroglial perisynaptic processes facilitates interaction of astrocytes with individual excitatory synapses. Bi-directional glutamatergic communication between astrocytes and neurons underpins a complex, spatially-distributed modulation of synaptic signalling thus contributing to the enrichment of information processing by the neuronal networks. Still, further research is needed to bridge the substantial gaps in our understanding of mechanisms and physiological relevance of astrocyte-neuron glutamatergic interactions, in particular ability of astrocytes directly activate neuronal glutamate receptors by releasing glutamate and, arguably, d-Serine. An emerging roles for aberrant changes in glutamatergic astroglial signalling, both neuroprotective and pathogenic, in neurological and neurodegenerative diseases also require further investigation. This article is part of the special Issue on 'Glutamate Receptors - The Glutamatergic Synapse'.
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Affiliation(s)
- Ulyana Lalo
- School of Life Sciences, Immanuel Kant Baltic Federal University, Kaliningrad, Russia
| | - Wuhyun Koh
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, 34126, South Korea
| | - C Justin Lee
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon, 34126, South Korea
| | - Yuriy Pankratov
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, United Kingdom.
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86
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Astrocyte Gliotransmission in the Regulation of Systemic Metabolism. Metabolites 2021; 11:metabo11110732. [PMID: 34822390 PMCID: PMC8623475 DOI: 10.3390/metabo11110732] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 10/25/2021] [Accepted: 10/26/2021] [Indexed: 12/28/2022] Open
Abstract
Normal brain function highly relies on the appropriate functioning of astrocytes. These glial cells are strategically situated between blood vessels and neurons, provide significant substrate support to neuronal demand, and are sensitive to neuronal activity and energy-related molecules. Astrocytes respond to many metabolic conditions and regulate a wide array of physiological processes, including cerebral vascular remodeling, glucose sensing, feeding, and circadian rhythms for the control of systemic metabolism and behavior-related responses. This regulation ultimately elicits counterregulatory mechanisms in order to couple whole-body energy availability with brain function. Therefore, understanding the role of astrocyte crosstalk with neighboring cells via the release of molecules, e.g., gliotransmitters, into the parenchyma in response to metabolic and neuronal cues is of fundamental relevance to elucidate the distinct roles of these glial cells in the neuroendocrine control of metabolism. Here, we review the mechanisms underlying astrocyte-released gliotransmitters that have been reported to be crucial for maintaining homeostatic regulation of systemic metabolism.
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87
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Chipman PH, Fung CCA, Pazo Fernandez A, Sawant A, Tedoldi A, Kawai A, Ghimire Gautam S, Kurosawa M, Abe M, Sakimura K, Fukai T, Goda Y. Astrocyte GluN2C NMDA receptors control basal synaptic strengths of hippocampal CA1 pyramidal neurons in the stratum radiatum. eLife 2021; 10:70818. [PMID: 34693906 PMCID: PMC8594917 DOI: 10.7554/elife.70818] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 10/22/2021] [Indexed: 12/12/2022] Open
Abstract
Experience-dependent plasticity is a key feature of brain synapses for which neuronal N-Methyl-D-Aspartate receptors (NMDARs) play a major role, from developmental circuit refinement to learning and memory. Astrocytes also express NMDARs, although their exact function has remained controversial. Here, we identify in mouse hippocampus, a circuit function for GluN2C NMDAR, a subtype highly expressed in astrocytes, in layer-specific tuning of synaptic strengths in CA1 pyramidal neurons. Interfering with astrocyte NMDAR or GluN2C NMDAR activity reduces the range of presynaptic strength distribution specifically in the stratum radiatum inputs without an appreciable change in the mean presynaptic strength. Mathematical modeling shows that narrowing of the width of presynaptic release probability distribution compromises the expression of long-term synaptic plasticity. Our findings suggest a novel feedback signaling system that uses astrocyte GluN2C NMDARs to adjust basal synaptic weight distribution of Schaffer collateral inputs, which in turn impacts computations performed by the CA1 pyramidal neuron.
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Affiliation(s)
| | - Chi Chung Alan Fung
- Neural Coding and Brain Computing Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | | | | | - Angelo Tedoldi
- RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
| | - Atsushi Kawai
- RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
| | | | | | - Manabu Abe
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata, Japan
| | - Kenji Sakimura
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata, Japan
| | - Tomoki Fukai
- Neural Coding and Brain Computing Unit, Okinawa Institute of Science and Technology Graduate University, Onna-son, Japan
| | - Yukiko Goda
- RIKEN Center for Brain Science, Wako-shi, Saitama, Japan
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88
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Arizono M, Nägerl UV. Deciphering the functional nano-anatomy of the tripartite synapse using stimulated emission depletion microscopy. Glia 2021; 70:607-618. [PMID: 34664734 DOI: 10.1002/glia.24103] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 09/24/2021] [Accepted: 09/30/2021] [Indexed: 11/12/2022]
Abstract
A major challenge for studying neuron-astrocyte communication lies in visualizing the tripartite synapse, which is the physical site where astrocytic processes contact and interact with neuronal synapses. While conventional light microscopy cannot resolve the anatomical details of the tripartite synapse, electron microscopy only provides ultrastructural snapshots that tell us little about its living state and dynamics. Stimulated emission depletion (STED) microscopy is a super-resolution fluorescence imaging technique that can provide live images of tripartite synapses with nanoscale spatial resolution. It is compatible with physiology experiments and imaging in the intact brain in vivo, opening up new opportunities to link the nanoscale structure of the tripartite system with functional readouts of neurons and astrocytes or even behavior. In this review, we first summarize the findings and insights from previous studies addressing the structure-function relationship of the tripartite synapse using conventional imaging techniques. We then explain the basic principle of STED microscopy and the main challenges facing its application to live-tissue imaging of fine astrocytic processes. We summarize insights from our recent STED studies, which revealed new aspects of the structure and physiology of the tripartite synapse and the surrounding extracellular space. Finally, we discuss how the STED approach and other advanced optical techniques can illuminate the role of astrocytes for brain physiology and animal behavior.
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Affiliation(s)
- Misa Arizono
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR, Bordeaux, France
| | - U Valentin Nägerl
- Interdisciplinary Institute for Neuroscience, Université de Bordeaux, Bordeaux, France.,Interdisciplinary Institute for Neuroscience, CNRS UMR, Bordeaux, France
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89
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Ahmadpour N, Kantroo M, Stobart JL. Extracellular Calcium Influx Pathways in Astrocyte Calcium Microdomain Physiology. Biomolecules 2021; 11:1467. [PMID: 34680100 PMCID: PMC8533159 DOI: 10.3390/biom11101467] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/25/2021] [Accepted: 10/01/2021] [Indexed: 02/08/2023] Open
Abstract
Astrocytes are complex glial cells that play many essential roles in the brain, including the fine-tuning of synaptic activity and blood flow. These roles are linked to fluctuations in intracellular Ca2+ within astrocytes. Recent advances in imaging techniques have identified localized Ca2+ transients within the fine processes of the astrocytic structure, which we term microdomain Ca2+ events. These Ca2+ transients are very diverse and occur under different conditions, including in the presence or absence of surrounding circuit activity. This complexity suggests that different signalling mechanisms mediate microdomain events which may then encode specific astrocyte functions from the modulation of synapses up to brain circuits and behaviour. Several recent studies have shown that a subset of astrocyte microdomain Ca2+ events occur rapidly following local neuronal circuit activity. In this review, we consider the physiological relevance of microdomain astrocyte Ca2+ signalling within brain circuits and outline possible pathways of extracellular Ca2+ influx through ionotropic receptors and other Ca2+ ion channels, which may contribute to astrocyte microdomain events with potentially fast dynamics.
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Affiliation(s)
| | | | - Jillian L. Stobart
- College of Pharmacy, Rady Faculty of Health Sciences, University of Manitoba, 750 McDermot Avenue, Winnipeg, MG R3E 0T5, Canada; (N.A.); (M.K.)
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90
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Benfey NJ, Li VJ, Schohl A, Ruthazer ES. Sodium-calcium exchanger mediates sensory-evoked glial calcium transients in the developing retinotectal system. Cell Rep 2021; 37:109791. [PMID: 34610307 DOI: 10.1016/j.celrep.2021.109791] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 06/24/2021] [Accepted: 09/13/2021] [Indexed: 12/14/2022] Open
Abstract
Various types of sensory stimuli have been shown to induce Ca2+ elevations in glia. However, a mechanistic understanding of the signaling pathways mediating sensory-evoked activity in glia in intact animals is still emerging. During early development of the Xenopus laevis visual system, radial astrocytes in the optic tectum are highly responsive to sensory stimulation. Ca2+ transients occur spontaneously in radial astrocytes at rest and are abolished by silencing neuronal activity with tetrodotoxin. Visual stimulation drives temporally correlated increases in the activity patterns of neighboring radial astrocytes. Following blockade of all glutamate receptors (gluRs), visually evoked Ca2+ activity in radial astrocytes persists, while neuronal activity is suppressed. The additional blockade of either glu transporters or sodium-calcium exchangers (NCX) abolishes visually evoked responses in glia. Finally, we demonstrate that blockade of NCX alone is sufficient to prevent visually evoked responses in radial astrocytes, highlighting a pivotal role for NCX in glia during development.
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Affiliation(s)
- Nicholas J Benfey
- Montreal Neurological Institute-Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, H3A 2B4 Canada
| | - Vanessa J Li
- Montreal Neurological Institute-Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, H3A 2B4 Canada
| | - Anne Schohl
- Montreal Neurological Institute-Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, H3A 2B4 Canada
| | - Edward S Ruthazer
- Montreal Neurological Institute-Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec, H3A 2B4 Canada.
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91
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Liu X, Ying J, Wang X, Zheng Q, Zhao T, Yoon S, Yu W, Yang D, Fang Y, Hua F. Astrocytes in Neural Circuits: Key Factors in Synaptic Regulation and Potential Targets for Neurodevelopmental Disorders. Front Mol Neurosci 2021; 14:729273. [PMID: 34658786 PMCID: PMC8515196 DOI: 10.3389/fnmol.2021.729273] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/02/2021] [Indexed: 12/14/2022] Open
Abstract
Astrocytes are the major glial cells in the brain, which play a supporting role in the energy and nutritional supply of neurons. They were initially regarded as passive space-filling cells, but the latest progress in the study of the development and function of astrocytes highlights their active roles in regulating synaptic transmission, formation, and plasticity. In the concept of "tripartite synapse," the bidirectional influence between astrocytes and neurons, in addition to their steady-state and supporting function, suggests that any negative changes in the structure or function of astrocytes will affect the activity of neurons, leading to neurodevelopmental disorders. The role of astrocytes in the pathophysiology of various neurological and psychiatric disorders caused by synaptic defects is increasingly appreciated. Understanding the roles of astrocytes in regulating synaptic development and the plasticity of neural circuits could help provide new treatments for these diseases.
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Affiliation(s)
- Xing Liu
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Jun Ying
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Xifeng Wang
- Department of Anesthesiology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Qingcui Zheng
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Tiancheng Zhao
- Mailman School of Public Health, Columbia University, New York, NY, United States
| | - Sungtae Yoon
- Helping Minds International Charitable Foundation, New York, NY, United States
| | - Wen Yu
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Danying Yang
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Yang Fang
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Fuzhou Hua
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
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92
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Van Den Herrewegen Y, Sanderson TM, Sahu S, De Bundel D, Bortolotto ZA, Smolders I. Side-by-side comparison of the effects of Gq- and Gi-DREADD-mediated astrocyte modulation on intracellular calcium dynamics and synaptic plasticity in the hippocampal CA1. Mol Brain 2021; 14:144. [PMID: 34544455 PMCID: PMC8451082 DOI: 10.1186/s13041-021-00856-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Accepted: 09/11/2021] [Indexed: 12/12/2022] Open
Abstract
Astrocytes express a plethora of G protein-coupled receptors (GPCRs) that are crucial for shaping synaptic activity. Upon GPCR activation, astrocytes can respond with transient variations in intracellular Ca2+. In addition, Ca2+-dependent and/or Ca2+-independent release of gliotransmitters can occur, allowing them to engage in bidirectional neuron-astrocyte communication. The development of designer receptors exclusively activated by designer drugs (DREADDs) has facilitated many new discoveries on the roles of astrocytes in both physiological and pathological conditions. They are an excellent tool, as they can target endogenous GPCR-mediated intracellular signal transduction pathways specifically in astrocytes. With increasing interest and accumulating research on this topic, several discrepancies on astrocytic Ca2+ signalling and astrocyte-mediated effects on synaptic plasticity have emerged, preventing a clear-cut consensus about the downstream effects of DREADDs in astrocytes. In the present study, we performed a side-by-side evaluation of the effects of bath application of the DREADD agonist, clozapine-N-oxide (10 µM), on Gq- and Gi-DREADD activation in mouse CA1 hippocampal astrocytes. In doing so, we aimed to avoid confounding factors, such as differences in experimental procedures, and to directly compare the actions of both DREADDs on astrocytic intracellular Ca2+ dynamics and synaptic plasticity in acute hippocampal slices. We used an adeno-associated viral vector approach to transduce dorsal hippocampi of male, 8-week-old C57BL6/J mice, to drive expression of either the Gq-DREADD or Gi-DREADD in CA1 astrocytes. A viral vector lacking the DREADD construct was used to generate controls. Here, we show that agonism of Gq-DREADDs, but not Gi-DREADDs, induced consistent increases in spontaneous astrocytic Ca2+ events. Moreover, we demonstrate that both Gq-DREADD as well as Gi-DREADD-mediated activation of CA1 astrocytes induces long-lasting synaptic potentiation in the hippocampal CA1 Schaffer collateral pathway in the absence of a high frequency stimulus. Moreover, we report for the first time that astrocytic Gi-DREADD activation is sufficient to elicit de novo potentiation. Our data demonstrate that activation of either Gq or Gi pathways drives synaptic potentiation through Ca2+-dependent and Ca2+-independent mechanisms, respectively.
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Affiliation(s)
- Yana Van Den Herrewegen
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090, Brussels, Belgium
| | - Thomas M Sanderson
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Tankard's Cl, University Walk, BS8 1TD, Bristol, UK
| | - Surajit Sahu
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090, Brussels, Belgium
| | - Dimitri De Bundel
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090, Brussels, Belgium
| | - Zuner A Bortolotto
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Tankard's Cl, University Walk, BS8 1TD, Bristol, UK
| | - Ilse Smolders
- Department of Pharmaceutical Chemistry, Drug Analysis and Drug Information, Research Group Experimental Pharmacology, Center for Neurosciences (C4N), Vrije Universiteit Brussel (VUB), Laarbeeklaan 103, 1090, Brussels, Belgium.
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93
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Weiss S, Clamon LC, Manoim JE, Ormerod KG, Parnas M, Littleton JT. Glial ER and GAP junction mediated Ca 2+ waves are crucial to maintain normal brain excitability. Glia 2021; 70:123-144. [PMID: 34528727 DOI: 10.1002/glia.24092] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 08/29/2021] [Accepted: 08/30/2021] [Indexed: 11/08/2022]
Abstract
Astrocytes play key roles in regulating multiple aspects of neuronal function from invertebrates to humans and display Ca2+ fluctuations that are heterogeneously distributed throughout different cellular microdomains. Changes in Ca2+ dynamics represent a key mechanism for how astrocytes modulate neuronal activity. An unresolved issue is the origin and contribution of specific glial Ca2+ signaling components at distinct astrocytic domains to neuronal physiology and brain function. The Drosophila model system offers a simple nervous system that is highly amenable to cell-specific genetic manipulations to characterize the role of glial Ca2+ signaling. Here we identify a role for ER store-operated Ca2+ entry (SOCE) pathway in perineurial glia (PG), a glial population that contributes to the Drosophila blood-brain barrier. We show that PG cells display diverse Ca2+ activity that varies based on their locale within the brain. Ca2+ signaling in PG cells does not require extracellular Ca2+ and is blocked by inhibition of SOCE, Ryanodine receptors, or gap junctions. Disruption of these components triggers stimuli-induced seizure-like episodes. These findings indicate that Ca2+ release from internal stores and its propagation between neighboring glial cells via gap junctions are essential for maintaining normal nervous system function.
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Affiliation(s)
- Shirley Weiss
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.,Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Lauren C Clamon
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Julia E Manoim
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Kiel G Ormerod
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Moshe Parnas
- Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.,Sagol School of Neuroscience, Tel Aviv University, Tel Aviv, Israel
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.,Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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94
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Müller FE, Cherkas V, Stopper G, Caudal LC, Stopper L, Kirchhoff F, Henneberger C, Ponimaskin EG, Zeug A. Elucidating regulators of astrocytic Ca 2+ signaling via multi-threshold event detection (MTED). Glia 2021; 69:2798-2811. [PMID: 34388285 DOI: 10.1002/glia.24070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 01/23/2023]
Abstract
Recent achievements in indicator optimization and imaging techniques promote the advancement of functional imaging to decipher complex signaling processes in living cells, such as Ca2+ activity patterns. Astrocytes are important regulators of the brain network and well known for their highly complex morphology and spontaneous Ca2+ activity. However, the astrocyte community is lacking standardized methods to analyze and interpret Ca2+ activity recordings, hindering global comparisons. Here, we present a biophysically-based analytical concept for deciphering the complex spatio-temporal changes of Ca2+ biosensor fluorescence for understanding the underlying signaling mechanisms. We developed a pixel-based multi-threshold event detection (MTED) analysis of multidimensional data, which accounts for signal strength as an additional signaling dimension and provides the experimenter with a comprehensive toolbox for a differentiated and in-depth characterization of fluorescence signals. MTED was validated by analyzing astrocytic Ca2+ activity across Ca2+ indicators, imaging setups, and model systems from primary cell culture to awake, head-fixed mice. We identified extended Ca2+ activity at 25°C compared to 37°C physiological body temperature and dissected how neuronal activity shapes long-lasting astrocytic Ca2+ activity. Our MTED strategy, as a parameter-free approach, is easily transferrable to other fluorescent indicators and biosensors and embraces the additional dimensionality of signaling activity strength. It will also advance the definition of standardized procedures and parameters to improve comparability of research data and reports.
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Affiliation(s)
| | - Volodymyr Cherkas
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
| | - Gebhard Stopper
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Laura C Caudal
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Laura Stopper
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Frank Kirchhoff
- Department of Molecular Physiology, Center for Integrative Physiology and Molecular Medicine (CIPMM), University of Saarland, Homburg, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany.,German Center for Neurodegenerative Diseases (DZNE), Bonn, Germany.,Institute of Neurology, University College London, London, UK
| | | | - Andre Zeug
- Cellular Neurophysiology, Hannover Medical School, Hannover, Germany
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95
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Sherwood MW, Arizono M, Panatier A, Mikoshiba K, Oliet SHR. Astrocytic IP 3Rs: Beyond IP 3R2. Front Cell Neurosci 2021; 15:695817. [PMID: 34393726 PMCID: PMC8363081 DOI: 10.3389/fncel.2021.695817] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/30/2021] [Indexed: 12/31/2022] Open
Abstract
Astrocytes are sensitive to ongoing neuronal/network activities and, accordingly, regulate neuronal functions (synaptic transmission, synaptic plasticity, behavior, etc.) by the context-dependent release of several gliotransmitters (e.g., glutamate, glycine, D-serine, ATP). To sense diverse input, astrocytes express a plethora of G-protein coupled receptors, which couple, via Gi/o and Gq, to the intracellular Ca2+ release channel IP3-receptor (IP3R). Indeed, manipulating astrocytic IP3R-Ca2+ signaling is highly consequential at the network and behavioral level: Depleting IP3R subtype 2 (IP3R2) results in reduced GPCR-Ca2+ signaling and impaired synaptic plasticity; enhancing IP3R-Ca2+ signaling affects cognitive functions such as learning and memory, sleep, and mood. However, as a result of discrepancies in the literature, the role of GPCR-IP3R-Ca2+ signaling, especially under physiological conditions, remains inconclusive. One primary reason for this could be that IP3R2 has been used to represent all astrocytic IP3Rs, including IP3R1 and IP3R3. Indeed, IP3R1 and IP3R3 are unique Ca2+ channels in their own right; they have unique biophysical properties, often display distinct distribution, and are differentially regulated. As a result, they mediate different physiological roles to IP3R2. Thus, these additional channels promise to enrich the diversity of spatiotemporal Ca2+ dynamics and provide unique opportunities for integrating neuronal input and modulating astrocyte–neuron communication. The current review weighs evidence supporting the existence of multiple astrocytic-IP3R isoforms, summarizes distinct sub-type specific properties that shape spatiotemporal Ca2+ dynamics. We also discuss existing experimental tools and future refinements to better recapitulate the endogenous activities of each IP3R isoform.
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Affiliation(s)
- Mark W Sherwood
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Misa Arizono
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France
| | - Aude Panatier
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Katsuhiko Mikoshiba
- ShanghaiTech University, Shanghai, China.,Faculty of Science, Toho University, Funabashi, Japan.,RIKEN CLST, Kobe, Japan
| | - Stéphane H R Oliet
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
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96
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Paumier A, Boisseau S, Jacquier-Sarlin M, Pernet-Gallay K, Buisson A, Albrieux M. Astrocyte-neuron interplay is critical for Alzheimer's disease pathogenesis and is rescued by TRPA1 channel blockade. Brain 2021; 145:388-405. [PMID: 34302466 DOI: 10.1093/brain/awab281] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/21/2021] [Accepted: 07/16/2021] [Indexed: 11/12/2022] Open
Abstract
The sequence of cellular dysfunctions in preclinical Alzheimer's disease must be understood if we are to plot new therapeutic routes. Hippocampal neuronal hyperactivity is one of the earliest events occurring during the preclinical stages of Alzheimer's disease in both humans and mouse models. The most common hypothesis describes amyloid β accumulation as the triggering factor of the disease but the effects of this accumulation and the cascade of events leading to cognitive decline remain unclear. In mice, we previously showed that amyloid β-dependent TRPA1 channel activation triggers hippocampal astrocyte hyperactivity, subsequently inducing hyperactivity in nearby neurons. In this work, we investigated the potential protection against Alzheimer's disease progression provided by early chronic pharmacological inhibition of TRPA1 channel. A specific inhibitor of TRPA1 channel (HC030031) was administered intraperitoneally from the onset of amyloid β overproduction in the APP/PS1-21 mouse model of Alzheimer's disease. Short-, medium-, and long-term effects of this chronic pharmacological TRPA1 blockade were characterized on Alzheimer's disease progression at functional (astrocytic and neuronal activity), structural, biochemical, and behavioural levels. Our results revealed that the first observable disruptions in the Alzheimer's disease transgenic mouse model used correspond to aberrant hippocampal astrocyte and neuron hyperactivity. We showed that chronic TRPA1 blockade normalizes astrocytic activity, avoids perisynaptic astrocytic process withdrawal, prevents neuronal dysfunction and preserves structural synaptic integrity. These protective effects preserved spatial working-memory in this Alzheimer's disease mouse model. The toxic effect of amyloid β on astrocytes triggered by TRPA1 channel activation is pivotal to Alzheimer's disease progression. TRPA1 blockade prevents irreversible neuronal dysfunction, making this channel a potential therapeutic target to promote neuroprotection.
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Affiliation(s)
- Adrien Paumier
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Sylvie Boisseau
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Muriel Jacquier-Sarlin
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Karin Pernet-Gallay
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Alain Buisson
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
| | - Mireille Albrieux
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, GIN, 38000 Grenoble, France
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97
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Nanclares C, Baraibar AM, Araque A, Kofuji P. Dysregulation of Astrocyte-Neuronal Communication in Alzheimer's Disease. Int J Mol Sci 2021; 22:7887. [PMID: 34360652 PMCID: PMC8346080 DOI: 10.3390/ijms22157887] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 07/19/2021] [Accepted: 07/20/2021] [Indexed: 12/16/2022] Open
Abstract
Recent studies implicate astrocytes in Alzheimer's disease (AD); however, their role in pathogenesis is poorly understood. Astrocytes have well-established functions in supportive functions such as extracellular ionic homeostasis, structural support, and neurovascular coupling. However, emerging research on astrocytic function in the healthy brain also indicates their role in regulating synaptic plasticity and neuronal excitability via the release of neuroactive substances named gliotransmitters. Here, we review how this "active" role of astrocytes at synapses could contribute to synaptic and neuronal network dysfunction and cognitive impairment in AD.
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Affiliation(s)
| | | | | | - Paulo Kofuji
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA; (C.N.); (A.M.B.); (A.A.)
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98
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Vanacker C, Defazio RA, Sykes CM, Moenter SM. A role for glial fibrillary acidic protein (GFAP)-expressing cells in the regulation of gonadotropin-releasing hormone (GnRH) but not arcuate kisspeptin neuron output in male mice. eLife 2021; 10:68205. [PMID: 34292152 PMCID: PMC8337074 DOI: 10.7554/elife.68205] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 07/21/2021] [Indexed: 01/05/2023] Open
Abstract
GnRH neurons are the final central neural output regulating fertility. Kisspeptin neurons in the hypothalamic arcuate nucleus (KNDy neurons) are considered the main regulator of GnRH output. GnRH and KNDy neurons are surrounded by astrocytes, which can modulate neuronal activity and communicate over distances. Prostaglandin E2 (PGE2), synthesized primarily by astrocytes, increases GnRH neuron activity and downstream pituitary release of luteinizing hormone (LH). We hypothesized that glial fibrillary acidic protein (GFAP)-expressing astrocytes play a role in regulating GnRH and/or KNDy neuron activity and LH release. We used adeno-associated viruses to target designer receptors exclusively activated by designer drugs (DREADDs) to GFAP-expressing cells to activate Gq- or Gi-mediated signaling. Activating Gq signaling in the preoptic area, near GnRH neurons, but not in the arcuate, increases LH release in vivo and GnRH firing in vitro via a mechanism in part dependent upon PGE2. These data suggest that astrocytes can activate GnRH/LH release in a manner independent of KNDy neurons.
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Affiliation(s)
- Charlotte Vanacker
- Departments of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, United States
| | - R Anthony Defazio
- Departments of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, United States
| | - Charlene M Sykes
- Departments of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, United States
| | - Suzanne M Moenter
- Departments of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, United States.,Internal Medicine, University of Michigan, Ann Arbor, United States.,Obstetrics & Gynecology, University of Michigan, Ann Arbor, United States.,Reproductive Sciences Program, University of Michigan, Ann Arbor, United States
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99
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Hart CG, Karimi-Abdolrezaee S. Recent insights on astrocyte mechanisms in CNS homeostasis, pathology, and repair. J Neurosci Res 2021; 99:2427-2462. [PMID: 34259342 DOI: 10.1002/jnr.24922] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/06/2021] [Accepted: 06/24/2021] [Indexed: 12/20/2022]
Abstract
Astrocytes play essential roles in development, homeostasis, injury, and repair of the central nervous system (CNS). Their development is tightly regulated by distinct spatial and temporal cues during embryogenesis and into adulthood throughout the CNS. Astrocytes have several important responsibilities such as regulating blood flow and permeability of the blood-CNS barrier, glucose metabolism and storage, synapse formation and function, and axon myelination. In CNS pathologies, astrocytes also play critical parts in both injury and repair mechanisms. Upon injury, they undergo a robust phenotypic shift known as "reactive astrogliosis," which results in both constructive and deleterious outcomes. Astrocyte activation and migration at the site of injury provides an early defense mechanism to minimize the extent of injury by enveloping the lesion area. However, astrogliosis also contributes to the inhibitory microenvironment of CNS injury and potentiate secondary injury mechanisms, such as inflammation, oxidative stress, and glutamate excitotoxicity, which facilitate neurodegeneration in CNS pathologies. Intriguingly, reactive astrocytes are increasingly a focus in current therapeutic strategies as their activation can be modulated toward a neuroprotective and reparative phenotype. This review will discuss recent advancements in knowledge regarding the development and role of astrocytes in the healthy and pathological CNS. We will also review how astrocytes have been genetically modified to optimize their reparative potential after injury, and how they may be transdifferentiated into neurons and oligodendrocytes to promote repair after CNS injury and neurodegeneration.
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Affiliation(s)
- Christopher G Hart
- Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada
| | - Soheila Karimi-Abdolrezaee
- Department of Physiology and Pathophysiology, Spinal Cord Research Centre, Children's Hospital Research Institute of Manitoba, University of Manitoba, Winnipeg, MB, Canada
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100
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Sherwood MW, Oliet SHR, Panatier A. NMDARs, Coincidence Detectors of Astrocytic and Neuronal Activities. Int J Mol Sci 2021; 22:7258. [PMID: 34298875 PMCID: PMC8307462 DOI: 10.3390/ijms22147258] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/30/2021] [Accepted: 06/30/2021] [Indexed: 12/18/2022] Open
Abstract
Synaptic plasticity is an extensively studied cellular correlate of learning and memory in which NMDARs play a starring role. One of the most interesting features of NMDARs is their ability to act as a co-incident detector. It is unique amongst neurotransmitter receptors in this respect. Co-incident detection is possible because the opening of NMDARs requires membrane depolarisation and the binding of glutamate. Opening of NMDARs also requires a co-agonist. Although the dynamic regulation of glutamate and membrane depolarization have been well studied in coincident detection, the role of the co-agonist site is unexplored. It turns out that non-neuronal glial cells, astrocytes, regulate co-agonist availability, giving them the ability to influence synaptic plasticity. The unique morphology and spatial arrangement of astrocytes at the synaptic level affords them the capacity to sample and integrate information originating from unrelated synapses, regardless of any pre-synaptic and post-synaptic commonality. As astrocytes are classically considered slow responders, their influence at the synapse is widely recognized as modulatory. The aim herein is to reconsider the potential of astrocytes to participate directly in ongoing synaptic NMDAR activity and co-incident detection.
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Affiliation(s)
- Mark W. Sherwood
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, F-3300 Bordeaux, France;
| | | | - Aude Panatier
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, F-3300 Bordeaux, France;
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