1
|
De Bock M, De Smet MA, Verwaerde S, Tahiri H, Schumacher S, Van Haver V, Witschas K, Steinhäuser C, Rouach N, Vandenbroucke RE, Leybaert L. Targeting gliovascular connexins prevents inflammatory blood-brain barrier leakage and astrogliosis. JCI Insight 2022; 7:135263. [PMID: 35881483 PMCID: PMC9462469 DOI: 10.1172/jci.insight.135263] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 07/18/2022] [Indexed: 11/17/2022] Open
Abstract
The blood-brain barrier is formed by capillary endothelial cells expressing Cx37, Cx40 and Cx43, and is joined by closely apposed astrocytes expressing Cx43 and Cx30. We investigated whether connexin-targeting peptides could limit barrier leakage triggered by LPS-induced systemic inflammation in mice. Intraperitoneal LPS increased endothelial and astrocytic Cx43 expression, elevated TNFα, IL1β, IFNγ and IL6 in plasma and IL6 in the brain, and induced barrier leakage recorded over 24h. Barrier leakage was largely prevented by global Cx43 knockdown and Cx43/Cx30 double-knockout in astrocytes, slightly diminished by endothelial Cx43 knockout and not protected by global Cx30 knockout. Intravenous administration of Gap27 or Tat-Gap19 just before LPS also prevented barrier leakage, and intravenous BAPTA-AM to chelate intracellular calcium was equally effective. Patch-clamp experiments demonstrated LPS-induced Cx43 hemichannel opening in endothelial cells, which was suppressed by Gap27, Gap19 and BAPTA. LPS additionally triggered astrogliosis that was prevented by intravenous Tat-Gap19 or BAPTA-AM. Cortically applied Tat-Gap19 or BAPTA-AM to primarily target astrocytes, also strongly diminished barrier leakage. In vivo dye uptake and in vitro patch-clamp showed Cx43 hemichannel opening in astrocytes that was induced by IL6 in a calcium-dependent manner. We conclude that targeting endothelial and astrocytic connexins is a powerful approach to limit barrier failure and astrogliosis.
Collapse
Affiliation(s)
- Marijke De Bock
- Department of Basic & Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Maarten Aj De Smet
- Department of Basic & Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Stijn Verwaerde
- Department of Basic & Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Hanane Tahiri
- Department of Basic & Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Steffi Schumacher
- Department of Basic & Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Valérie Van Haver
- Department of Basic & Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Katja Witschas
- Department of Basic & Applied Medical Sciences, Ghent University, Ghent, Belgium
| | | | - Nathalie Rouach
- Center for Interdisiplinary Research in Biology (CIRB), College de France, Paris, France
| | | | - Luc Leybaert
- Department of Basic & Applied Medical Sciences, Ghent University, Ghent, Belgium
| |
Collapse
|
2
|
Gorzo KA, Gordon GR. Photonics tools begin to clarify astrocyte calcium transients. NEUROPHOTONICS 2022; 9:021907. [PMID: 35211642 PMCID: PMC8857908 DOI: 10.1117/1.nph.9.2.021907] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 02/01/2022] [Indexed: 05/27/2023]
Abstract
Astrocytes integrate information from neurons and the microvasculature to coordinate brain activity and metabolism. Using a variety of calcium-dependent cellular mechanisms, these cells impact numerous aspects of neurophysiology in health and disease. Astrocyte calcium signaling is highly diverse, with complex spatiotemporal features. Here, we review astrocyte calcium dynamics and the optical imaging tools used to measure and analyze these events. We briefly cover historical calcium measurements, followed by our current understanding of how calcium transients relate to the structure of astrocytes. We then explore newer photonics tools including super-resolution techniques and genetically encoded calcium indicators targeted to specific cellular compartments and how these have been applied to astrocyte biology. Finally, we provide a brief overview of analysis software used to accurately quantify the data and ultimately aid in our interpretation of the various functions of astrocyte calcium transients.
Collapse
Affiliation(s)
- Kelsea A. Gorzo
- University of Calgary, Hotchkiss Brain Institute, Cumming School of Medicine, Calgary, Alberta, Canada
| | - Grant R. Gordon
- University of Calgary, Hotchkiss Brain Institute, Cumming School of Medicine, Calgary, Alberta, Canada
| |
Collapse
|
3
|
Liang Y, Walczak P. Long term intravital single cell tracking under multiphoton microscopy. J Neurosci Methods 2020; 349:109042. [PMID: 33340557 DOI: 10.1016/j.jneumeth.2020.109042] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 12/07/2020] [Accepted: 12/11/2020] [Indexed: 12/13/2022]
Abstract
Visualizing and tracking cells over time in a living organism has been a much-coveted dream before the invention of intravital microscopy. The opaque nature of tissue was a major hurdle that was remedied by the multiphoton microscopy. With the advancement of optical imaging and fluorescent labeling tools, intravital high resolution imaging has become increasingly accessible over the past few years. Long-term intravital tracking of single cells (LIST) under multiphoton microscopy provides a unique opportunity to gain insight into the longitudinal changes in the morphology, migration, or function of cells or subcellular structures. It is particularly suitable for studying slow-evolving cellular and molecular events during normal development or disease progression, without losing the opportunity of catching fast events such as calcium signals. Here, we review the application of LIST under 2-photon microscopy in various fields of neurobiology and discuss challenges and new directions in labeling and imaging methods for LIST. Overall, this review provides an overview of current applications of LIST in mammals, which is an emerging field that will contribute to a better understanding of essential molecular and cellular events in health and disease.
Collapse
Affiliation(s)
- Yajie Liang
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, USA.
| | - Piotr Walczak
- Department of Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, Baltimore, MD, USA
| |
Collapse
|
4
|
Zhang X, Mariano CF, Ando Y, Shen K. Bioengineering tools for probing intracellular events in T lymphocytes. WIREs Mech Dis 2020; 13:e1510. [PMID: 33073545 DOI: 10.1002/wsbm.1510] [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: 07/16/2020] [Revised: 09/14/2020] [Accepted: 09/16/2020] [Indexed: 11/11/2022]
Abstract
T lymphocytes are the central coordinator and executor of many immune functions. The activation and function of T lymphocytes are mediated through the engagement of cell surface receptors and regulated by a myriad of intracellular signaling network. Bioengineering tools, including imaging modalities and fluorescent probes, have been developed and employed to elucidate the cellular events throughout the functional lifespan of T cells. A better understanding of these events can broaden our knowledge in the immune systems biology, as well as accelerate the development of effective diagnostics and immunotherapies. Here we review the commonly used and recently developed techniques and probes for monitoring T lymphocyte intracellular events, following the order of intracellular events in T cells from activation, signaling, metabolism to apoptosis. The techniques introduced here can be broadly applied to other immune cells and cell systems. This article is categorized under: Immune System Diseases > Molecular and Cellular Physiology Immune System Diseases > Biomedical Engineering Infectious Diseases > Biomedical Engineering.
Collapse
Affiliation(s)
- Xinyuan Zhang
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA
| | - Chelsea F Mariano
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA
| | - Yuta Ando
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA
| | - Keyue Shen
- Department of Biomedical Engineering, University of Southern California, Los Angeles, California, USA.,Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California, USA.,USC Stem Cell, University of Southern California, Los Angeles, California, USA
| |
Collapse
|
5
|
Farini A, Sitzia C, Cassinelli L, Colleoni F, Parolini D, Giovanella U, Maciotta S, Colombo A, Meregalli M, Torrente Y. Inositol 1,4,5-trisphosphate (IP3)-dependent Ca2+ signaling mediates delayed myogenesis in Duchenne muscular dystrophy fetal muscle. Development 2016; 143:658-69. [DOI: 10.1242/dev.126193] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Duchenne muscular dystrophy (DMD) is a progressive neuromuscular disorder characterized by muscle wasting and premature death. The defective gene is dystrophin, a structural protein, absence of which causes membrane fragility and myofiber necrosis. Several lines of evidence showed that in adult DMD patients dystrophin is involved in signaling pathways that regulate calcium homeostasis and differentiation programs. However, secondary aspects of the disease, such as inflammation and fibrosis development, might represent a bias in the analysis. Because fetal muscle is not influenced by gravity and does not suffer from mechanical load and/or inflammation, we investigated 12-week-old fetal DMD skeletal muscles, highlighting for the first time early alterations in signaling pathways mediated by the absence of dystrophin itself. We found that PLC/IP3/IP3R/Ryr1/Ca2+ signaling is widely active in fetal DMD skeletal muscles and, through the calcium-dependent PKCα protein, exerts a fundamental regulatory role in delaying myogenesis and in myofiber commitment. These data provide new insights into the origin of DMD pathology during muscle development.
Collapse
Affiliation(s)
- Andrea Farini
- Laboratorio di Cellule Staminali, Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milano, Centro Dino Ferrari, Via Francesco Sforza 35, Milan 20122, Centro Dino Ferrari, Italy
| | - Clementina Sitzia
- Laboratorio di Cellule Staminali, Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milano, Centro Dino Ferrari, Via Francesco Sforza 35, Milan 20122, Centro Dino Ferrari, Italy
| | - Letizia Cassinelli
- Laboratorio di Cellule Staminali, Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milano, Centro Dino Ferrari, Via Francesco Sforza 35, Milan 20122, Centro Dino Ferrari, Italy
| | - Federica Colleoni
- Laboratorio di Cellule Staminali, Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milano, Centro Dino Ferrari, Via Francesco Sforza 35, Milan 20122, Centro Dino Ferrari, Italy
| | - Daniele Parolini
- Laboratorio di Cellule Staminali, Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milano, Centro Dino Ferrari, Via Francesco Sforza 35, Milan 20122, Centro Dino Ferrari, Italy
| | - Umberto Giovanella
- Consiglio Nazionale delle Ricerche, Istituto per lo Studio delle Macromolecole (CNR-ISMAC), via Bassini 15, Milano 20133, Italy
| | - Simona Maciotta
- Laboratorio di Cellule Staminali, Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milano, Centro Dino Ferrari, Via Francesco Sforza 35, Milan 20122, Centro Dino Ferrari, Italy
| | - Augusto Colombo
- Servizio ‘Legge 194’ Dipartimento BDN-Fondazione IRCCS, Policlinico Mangiagalli-Regina Elena, Via Francesco Sforza 35, Milan 20122, Italy
| | - Mirella Meregalli
- Laboratorio di Cellule Staminali, Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milano, Centro Dino Ferrari, Via Francesco Sforza 35, Milan 20122, Centro Dino Ferrari, Italy
| | - Yvan Torrente
- Laboratorio di Cellule Staminali, Dipartimento di Fisiopatologia medico-chirurgica e dei Trapianti, Università degli Studi di Milano, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, Milano, Centro Dino Ferrari, Via Francesco Sforza 35, Milan 20122, Centro Dino Ferrari, Italy
| |
Collapse
|
6
|
Li H, Xie Y, Zhang N, Yu Y, Zhang Q, Ding S. Disruption of IP₃R2-mediated Ca²⁺ signaling pathway in astrocytes ameliorates neuronal death and brain damage while reducing behavioral deficits after focal ischemic stroke. Cell Calcium 2015; 58:565-76. [PMID: 26433454 DOI: 10.1016/j.ceca.2015.09.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Revised: 09/19/2015] [Accepted: 09/21/2015] [Indexed: 12/12/2022]
Abstract
Inositol trisphosphate receptor (IP3R)-mediated intracellular Ca(2+) increase is the major Ca(2+) signaling pathway in astrocytes in the central nervous system (CNS). Ca(2+) increases in astrocytes have been found to modulate neuronal function through gliotransmitter release. We previously demonstrated that astrocytes exhibit enhanced Ca(2+) signaling in vivo after photothrombosis (PT)-induced ischemia, which is largely due to the activation of G-protein coupled receptors (GPCRs). The aim of this study is to investigate the role of astrocytic IP3R-mediated Ca(2+) signaling in neuronal death, brain damage and behavior outcomes after PT. For this purpose, we conducted experiments using homozygous type 2 IP3R (IP3R2) knockout (KO) mice. Histological and immunostaining studies showed that IP3R2 KO mice were indeed deficient in IP3R2 in astrocytes and exhibited normal brain cytoarchitecture. IP3R2 KO mice also had the same densities of S100β+ astrocytes and NeuN+ neurons in the cortices, and exhibited the same glial fibrillary acidic protein (GFAP) and glial glutamate transporter (GLT-1) levels in the cortices and hippocampi as compared with wild type (WT) mice. Two-photon (2-P) imaging showed that IP3R2 KO mice did not exhibit ATP-induced Ca(2+) waves in vivo in the astrocytic network, which verified the disruption of IP3R-mediated Ca(2+) signaling in astrocytes of these mice. When subject to PT, IP3R2 KO mice had smaller infarction than WT mice in acute and chronic phases of ischemia. IP3R2 KO mice also exhibited less neuronal apoptosis, reactive astrogliosis, and tissue loss than WT mice. Behavioral tests, including cylinder, hanging wire, pole and adhesive tests, showed that IP3R2 KO mice exhibited reduced functional deficits after PT. Collectively, our study demonstrates that disruption of astrocytic Ca(2+) signaling by deleting IP3R2s has beneficial effects on neuronal and brain protection and functional deficits after stroke. These findings reveal a novel non-cell-autonomous neuronal and brain protective function of astrocytes in ischemic stroke, whereby suggest that the astrocytic IP3R2-mediated Ca(2+) signaling pathway might be a promising target for stroke therapy.
Collapse
Affiliation(s)
- Hailong Li
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, MO 65211, United States; Department of Bioengineering, University of Missouri-Columbia, MO 65211, United States
| | - Yicheng Xie
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, MO 65211, United States; Department of Bioengineering, University of Missouri-Columbia, MO 65211, United States
| | - Nannan Zhang
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, MO 65211, United States
| | - Yang Yu
- Department of Bioengineering, University of Missouri-Columbia, MO 65211, United States
| | - Qiao Zhang
- Department of Bioengineering, University of Missouri-Columbia, MO 65211, United States
| | - Shinghua Ding
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, MO 65211, United States; Department of Bioengineering, University of Missouri-Columbia, MO 65211, United States.
| |
Collapse
|
7
|
Sobol CV, Gapanovich SO. Neuronal cells in the dorsal and ventral roots of the spinal cord of a frog. DOKLADY BIOLOGICAL SCIENCES : PROCEEDINGS OF THE ACADEMY OF SCIENCES OF THE USSR, BIOLOGICAL SCIENCES SECTIONS 2015; 461:80-4. [PMID: 25937327 DOI: 10.1134/s0012496615020106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Indexed: 11/23/2022]
Affiliation(s)
- C V Sobol
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Thorez, 44, St. Petersburg, 194223, Russia,
| | | |
Collapse
|
8
|
Gee JM, Gibbons MB, Taheri M, Palumbos S, Morris SC, Smeal RM, Flynn KF, Economo MN, Cizek CG, Capecchi MR, Tvrdik P, Wilcox KS, White JA. Imaging activity in astrocytes and neurons with genetically encoded calcium indicators following in utero electroporation. Front Mol Neurosci 2015; 8:10. [PMID: 25926768 PMCID: PMC4397926 DOI: 10.3389/fnmol.2015.00010] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Accepted: 03/23/2015] [Indexed: 11/13/2022] Open
Abstract
Complex interactions between networks of astrocytes and neurons are beginning to be appreciated, but remain poorly understood. Transgenic mice expressing fluorescent protein reporters of cellular activity, such as the GCaMP family of genetically encoded calcium indicators (GECIs), have been used to explore network behavior. However, in some cases, it may be desirable to use long-established rat models that closely mimic particular aspects of human conditions such as Parkinson's disease and the development of epilepsy following status epilepticus. Methods for expressing reporter proteins in the rat brain are relatively limited. Transgenic rat technologies exist but are fairly immature. Viral-mediated expression is robust but unstable, requires invasive injections, and only works well for fairly small genes (<5 kb). In utero electroporation (IUE) offers a valuable alternative. IUE is a proven method for transfecting populations of astrocytes and neurons in the rat brain without the strict limitations on transgene size. We built a toolset of IUE plasmids carrying GCaMP variants 3, 6s, or 6f driven by CAG and targeted to the cytosol or the plasma membrane. Because low baseline fluorescence of GCaMP can hinder identification of transfected cells, we included the option of co-expressing a cytosolic tdTomato protein. A binary system consisting of a plasmid carrying a piggyBac inverted terminal repeat (ITR)-flanked CAG-GCaMP-IRES-tdTomato cassette and a separate plasmid encoding for expression of piggyBac transposase was employed to stably express GCaMP and tdTomato. The plasmids were co-electroporated on embryonic days 13.5-14.5 and astrocytic and neuronal activity was subsequently imaged in acute or cultured brain slices prepared from the cortex or hippocampus. Large spontaneous transients were detected in slices obtained from rats of varying ages up to 127 days. In this report, we demonstrate the utility of this toolset for interrogating astrocytic and neuronal activity in the rat brain.
Collapse
Affiliation(s)
- J Michael Gee
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA ; MD-PhD Program, University of Utah Salt Lake City, UT, USA
| | - Meredith B Gibbons
- Glial-Neuronal Interactions in Epilepsy Laboratory, Department of Pharmacology and Toxicology, University of Utah Salt Lake City, UT, USA ; Interdepartmental Program in Neuroscience, University of Utah Salt Lake City, UT, USA
| | - Marsa Taheri
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA
| | - Sierra Palumbos
- Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA
| | - S Craig Morris
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA ; Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA
| | - Roy M Smeal
- Glial-Neuronal Interactions in Epilepsy Laboratory, Department of Pharmacology and Toxicology, University of Utah Salt Lake City, UT, USA
| | - Katherine F Flynn
- Glial-Neuronal Interactions in Epilepsy Laboratory, Department of Pharmacology and Toxicology, University of Utah Salt Lake City, UT, USA
| | - Michael N Economo
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA
| | - Christian G Cizek
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA ; Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA
| | - Mario R Capecchi
- Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA ; Department of Human Genetics, Howard Hughes Medical Institute, University of Utah Salt Lake City, UT, USA
| | - Petr Tvrdik
- Mario Capecchi Laboratory, Department of Human Genetics, University of Utah Salt Lake City, UT, USA
| | - Karen S Wilcox
- Glial-Neuronal Interactions in Epilepsy Laboratory, Department of Pharmacology and Toxicology, University of Utah Salt Lake City, UT, USA
| | - John A White
- Neuronal Dynamics Laboratory, Department of Bioengineering, University of Utah Salt Lake City, UT, USA
| |
Collapse
|
9
|
Abstract
Astrocytes have been found to play important roles in physiology being fundamental for ionic homeostasis and glutamate clearance from the synaptic cleft by their plasma membrane glutamate transporters. Astrocytes are electrically non-excitable, but they exhibit Ca(2+) signaling, which now has been demonstrated to serve as an indirect mediator of neuron-glia bidirectional interactions through gliotransmission via tripartite synapses and to modulate synaptic function and plasticity. Spontaneous astrocytic Ca(2+) signaling was observed in vivo. Intercellular Ca(2+) waves in astrocytes can be evoked by a variety of stimulations. Astrocytes are critically involved in many pathological conditions including ischemic stroke. For example, it is well known that astrocytes become reactive and form glial scar after stroke. In animal models of some brain disorders, astrocytes have been shown to exhibit enhanced Ca(2+) excitability featured as regenerative intercellular Ca(2+) waves. This chapter briefly summarizes astrocytic Ca(2+) signaling pathways under normal conditions and in experimental in vitro and in vivo ischemic models. It discusses the possible mechanisms and therapeutic implication underlying the enhanced astrocytic Ca(2+) excitability in stroke.
Collapse
Affiliation(s)
- Shinghua Ding
- Dalton Cardiovascular Research Center, Department of Bioengineering, University of Missouri-Columbia, 134 Research Park Drive, Columbia, MO, 65211, USA,
| |
Collapse
|
10
|
Role of astrocytes in memory and psychiatric disorders. ACTA ACUST UNITED AC 2014; 108:240-51. [PMID: 25169821 DOI: 10.1016/j.jphysparis.2014.08.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 04/12/2014] [Accepted: 08/18/2014] [Indexed: 01/10/2023]
Abstract
Over the past decade, the traditional description of astrocytes as being merely accessories to brain function has shifted to one in which their role has been pushed into the forefront of importance. Current views suggest that astrocytes:(1) are excitable through calcium fluctuations and respond to neurotransmitters released at synapses; (2) communicate with each other via calcium waves and release their own gliotransmitters which are essential for synaptic plasticity; (3) activate hundreds of synapses at once, thereby synchronizing neuronal activity and activating or inhibiting complete neuronal networks; (4) release vasoactive substances to the smooth muscle surrounding blood vessels enabling the coupling of circulation (blood flow) to local brain activity; and (5) release lactate in an activity-dependent manner in order to supply neuronal metabolic demand. In consequence, the role of astrocytes and astrocytic gliotransmitters is now believed to be critical for higher brain function and recently, evidence begins to gather suggesting that astrocytes are pivotal for learning and memory. All of the above are reviewed here while focusing on the role of astrocytes in memory and psychiatric disorders.
Collapse
|
11
|
Orellana JA, Stehberg J. Hemichannels: new roles in astroglial function. Front Physiol 2014; 5:193. [PMID: 24987373 PMCID: PMC4060415 DOI: 10.3389/fphys.2014.00193] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Accepted: 05/07/2014] [Indexed: 01/16/2023] Open
Abstract
The role of astrocytes in brain function has evolved over the last decade, from support cells to active participants in the neuronal synapse through the release of "gliotransmitters."Astrocytes express receptors for most neurotransmitters and respond to them through Ca(2+) intracellular oscillations and propagation of intercellular Ca(2+) waves. While such waves are able to propagate among neighboring astrocytes through gap junctions, thereby activating several astrocytes simultaneously, they can also trigger the release of gliotransmitters, including glutamate, d-serine, glycine, ATP, adenosine, or GABA. There are several mechanisms by which gliotransmitter release occurs, including functional hemichannels. These gliotransmitters can activate neighboring astrocytes and participate in the propagation of intercellular Ca(2+) waves, or activate pre- and post-synaptic receptors, including NMDA, AMPA, and purinergic receptors. In consequence, hemichannels could play a pivotal role in astrocyte-to-astrocyte communication and astrocyte-to-neuron cross-talk. Recent evidence suggests that astroglial hemichannels are involved in higher brain functions including memory and glucose sensing. The present review will focus on the role of hemichannels in astrocyte-to-astrocyte and astrocyte-to neuron communication and in brain physiology.
Collapse
Affiliation(s)
- Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Jimmy Stehberg
- Laboratorio de Neurobiología, Centro de Investigaciones Médicas, Facultad de Ciencias Biológicas and Facultad de Medicina, Universidad Andrés Bello Santiago, Chile
| |
Collapse
|
12
|
Abstract
Astrocytes are the predominant glial cell type in the CNS. Although astrocytes are electrically nonexcitable, their excitability is manifested by their Ca2+ signaling, which serves as a mediator of neuron-glia bidirectional interactions via tripartite synapses. Studies from in vivo two-photon imaging indicate that in healthy animals, the properties of spontaneous astrocytic Ca2+ signaling are affected by animal species, age, wakefulness and the location of astrocytes in the brain. Intercellular Ca2+ waves in astrocytes can be evoked by a variety of stimulations. In animal models of some brain disorders, astrocytes can exhibit enhanced Ca2+ excitability featured as regenerative intercellular Ca2+ waves. This review first briefly summarizes the astrocytic Ca2+ signaling pathway and the procedure of in vivo two-photon Ca2+ imaging of astrocytes. It subsequently summarizes in vivo astrocytic Ca2+ signaling in health and brain disorders from experimental studies of animal models, and discusses the possible mechanisms and therapeutic implications underlying the enhanced Ca2+ excitability in astrocytes in brain disorders. Finally, this review summarizes molecular genetic approaches used to selectively manipulate astrocyte function in vivo and their applications to study the role of astrocytes in synaptic plasticity and brain disorders.
Collapse
Affiliation(s)
- Shinghua Ding
- Dalton Cardiovascular Research Center, Department of Biological Engineering, University of Missouri, Columbia, MO 65211, USA
| |
Collapse
|