1
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Prabhakar P, Pielot R, Landgraf P, Wissing J, Bayrhammer A, van Ham M, Gundelfinger ED, Jänsch L, Dieterich DC, Müller A. Monitoring regional astrocyte diversity by cell type-specific proteomic labeling in vivo. Glia 2023; 71:682-703. [PMID: 36401581 DOI: 10.1002/glia.24304] [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: 07/05/2022] [Revised: 10/29/2022] [Accepted: 11/03/2022] [Indexed: 11/21/2022]
Abstract
Astrocytes exhibit regional heterogeneity in morphology, function and molecular composition to support and modulate neuronal function and signaling in a region-specific manner. To characterize regional heterogeneity of astrocytic proteomes of different brain regions we established an inducible Aldh1l1-methionyl-tRNA-synthetaseL274G (MetRSL274G ) mouse line that allows astrocyte-specific metabolic labeling of newly synthesized proteins by azidonorleucine (ANL) in vivo and subsequent isolation of tagged proteins by click chemistry. We analyzed astrocytic proteins from four different brain regions by mass spectrometry. The induced expression of MetRSL274G is restricted to astrocytes and identified proteins show a high overlap with proteins compiled in "AstroProt," a newly established database for astrocytic proteins. Gene enrichment analysis reveals a high similarity among brain regions with subtle differences in enriched biological processes and in abundances of key astrocytic proteins for hippocampus, cortex and striatum. However, the cerebellar proteome stands out with proteins being highly associated with the calcium signaling pathway or with bipolar disorder. Subregional analysis of single astrocyte TAMRA intensities in hippocampal layers indicates distinct subregional heterogeneity of astrocytes and highlights the applicability of our toolbox to study differences of astrocytic proteomes in vivo.
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Affiliation(s)
- Priyadharshini Prabhakar
- Institute for Pharmacology and Toxicology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
| | - Rainer Pielot
- Institute for Pharmacology and Toxicology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Peter Landgraf
- Institute for Pharmacology and Toxicology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
| | - Josef Wissing
- Cellular Proteome Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Anne Bayrhammer
- Institute for Pharmacology and Toxicology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Marco van Ham
- Cellular Proteome Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Eckart D Gundelfinger
- Institute for Pharmacology and Toxicology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany.,Leibniz Institute for Neurobiology, RG Neuroplasticity, Magdeburg, Germany
| | - Lothar Jänsch
- Cellular Proteome Research Group, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Daniela C Dieterich
- Institute for Pharmacology and Toxicology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
| | - Anke Müller
- Institute for Pharmacology and Toxicology, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany.,Center for Behavioral Brain Sciences (CBBS), Magdeburg, Germany
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2
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Marchese NA, Ríos MN, Guido ME. Müller glial cell photosensitivity: a novel function bringing higher complexity to vertebrate retinal physiology. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2023. [DOI: 10.1016/j.jpap.2023.100162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
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3
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Butcher JB, Sims RE, Ngum NM, Bazzari AH, Jenkins SI, King M, Hill EJ, Nagel DA, Fox K, Parri HR, Glazewski S. A requirement for astrocyte IP3R2 signaling for whisker experience-dependent depression and homeostatic upregulation in the mouse barrel cortex. Front Cell Neurosci 2022; 16:905285. [PMID: 36090792 PMCID: PMC9452848 DOI: 10.3389/fncel.2022.905285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2022] [Accepted: 07/06/2022] [Indexed: 11/19/2022] Open
Abstract
Changes to sensory experience result in plasticity of synapses in the cortex. This experience-dependent plasticity (EDP) is a fundamental property of the brain. Yet, while much is known about neuronal roles in EDP, very little is known about the role of astrocytes. To address this issue, we used the well-described mouse whiskers-to-barrel cortex system, which expresses a number of forms of EDP. We found that all-whisker deprivation induced characteristic experience-dependent Hebbian depression (EDHD) followed by homeostatic upregulation in L2/3 barrel cortex of wild type mice. However, these changes were not seen in mutant animals (IP3R2–/–) that lack the astrocyte-expressed IP3 receptor subtype. A separate paradigm, the single-whisker experience, induced potentiation of whisker-induced response in both wild-type (WT) mice and IP3R2–/– mice. Recordings in ex vivo barrel cortex slices reflected the in vivo results so that long-term depression (LTD) could not be elicited in slices from IP3R2–/– mice, but long-term potentiation (LTP) could. Interestingly, 1 Hz stimulation inducing LTD in WT paradoxically resulted in NMDAR-dependent LTP in slices from IP3R2–/– animals. The LTD to LTP switch was mimicked by acute buffering astrocytic [Ca2+]i in WT slices. Both WT LTD and IP3R2–/– 1 Hz LTP were mediated by non-ionotropic NMDAR signaling, but only WT LTD was P38 MAPK dependent, indicating an underlying mechanistic switch. These results demonstrate a critical role for astrocytic [Ca2+]i in several EDP mechanisms in neocortex.
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Affiliation(s)
- John B. Butcher
- School of Life Sciences, Keele University, Keele, United Kingdom
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - Robert E. Sims
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - Neville M. Ngum
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - Amjad H. Bazzari
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - Stuart I. Jenkins
- Neural Tissue Engineering Group, Institute for Science and Technology in Medicine (ISTM), Keele University, Keele, United Kingdom
| | - Marianne King
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - Eric J. Hill
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
| | - David A. Nagel
- Aston Medical School, Aston Medical Research Institute, Aston University, Birmingham, United Kingdom
| | - Kevin Fox
- School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | - H. Rheinallt Parri
- College of Health and Life Sciences, Aston University, Birmingham, United Kingdom
- *Correspondence: H. Rheinallt Parri,
| | - Stanislaw Glazewski
- School of Life Sciences, Keele University, Keele, United Kingdom
- Stanislaw Glazewski,
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4
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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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5
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Nippert AR, Chiang PP, Del Franco AP, Newman EA. Astrocyte regulation of cerebral blood flow during hypoglycemia. J Cereb Blood Flow Metab 2022; 42:1534-1546. [PMID: 35296178 PMCID: PMC9274859 DOI: 10.1177/0271678x221089091] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 02/07/2022] [Accepted: 02/28/2022] [Indexed: 12/13/2022]
Abstract
Hypoglycemia triggers increases in cerebral blood flow (CBF), augmenting glucose supply to the brain. We have tested whether astrocytes, which can regulate vessel tone, contribute to this CBF increase. We hypothesized that hypoglycemia-induced adenosine signaling acts to increase astrocyte Ca2+ activity, which then causes the release of prostaglandins (PGs) and epoxyeicosatrienoic acids (EETs), leading to the dilation of brain arterioles and blood flow increases. We used an awake mouse model to investigate the effects of insulin-induced hypoglycemia on arterioles and astrocytes in the somatosensory cortex. During insulin-induced hypoglycemia, penetrating arterioles dilated and astrocyte Ca2+ signaling increased when blood glucose dropped below a threshold of ∼50 mg/dL. Application of the A2A adenosine receptor antagonist ZM-241385 eliminated hypoglycemia-evoked astrocyte Ca2+ increases and reduced arteriole dilations by 44% (p < 0.05). SC-560 and miconazole, which block the production of the astrocyte vasodilators PGs and EETs respectively, reduced arteriole dilations in response to hypoglycemia by 89% (p < 0.001) and 76% (p < 0.001). Hypoglycemia-induced arteriole dilations were decreased by 65% (p < 0.001) in IP3R2 knockout mice, which have reduced astrocyte Ca2+ signaling compared to wild-type. These results support the hypothesis that astrocytes contribute to hypoglycemia-induced increases in CBF by releasing vasodilators in a Ca2+-dependent manner.
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Affiliation(s)
- Amy R Nippert
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | - Pei-Pei Chiang
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
| | | | - Eric A Newman
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, USA
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6
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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.
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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
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7
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Del Franco AP, Chiang PP, Newman EA. Dilation of cortical capillaries is not related to astrocyte calcium signaling. Glia 2022; 70:508-521. [PMID: 34767261 PMCID: PMC8732319 DOI: 10.1002/glia.24119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 10/12/2021] [Accepted: 10/31/2021] [Indexed: 12/30/2022]
Abstract
The brain requires an adequate supply of oxygen and nutrients to maintain proper function as neuronal activity varies. This is achieved, in part, through neurovascular coupling mechanisms that mediate local increases in blood flow through the dilation of arterioles and capillaries. The role of astrocytes in mediating this functional hyperemia response is controversial. Specifically, the function of astrocyte Ca2+ signaling is unclear. Cortical arterioles dilate in the absence of astrocyte Ca2+ signaling, but previous work suggests that Ca2+ increases are necessary for capillary dilation. This question has not been fully addressed in vivo, however, and we have reexamined the role of astrocyte Ca2+ signaling in vessel dilation in the barrel cortex of awake, behaving mice. We recorded evoked vessel dilations and astrocyte Ca2+ signaling in response to whisker stimulation. Experiments were carried out on WT and IP3R2 KO mice, a transgenic model where astrocyte Ca2+ signaling is substantially reduced. Compared to WT mice at rest, Ca2+ signaling in astrocyte endfeet contacting capillaries increased by 240% when whisker stimulation evoked running. In contrast, Ca2+ signaling was reduced to 9% of WT values in IP3R2 KO mice. In all three conditions, however, the amplitude of capillary dilation was largely unchanged. In addition, the latency to the onset of astrocyte Ca2+ signaling lagged behind dilation onset in most trials, although a subset of rapid onset Ca2+ events with latencies as short as 0.15 s occurred. In summary, we found that whisker stimulation-evoked capillary dilations occurred independent of astrocyte Ca2+ increases in the cerebral cortex.
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Affiliation(s)
- Armani P Del Franco
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Pei-Pei Chiang
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Eric A Newman
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
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8
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Marchese NA, Ríos MN, Guido ME. The Intrinsic Blue Light Responses of Avian Müller Glial Cells Imply Calcium Release from Internal Stores. ASN Neuro 2022; 14:17590914221076698. [PMID: 35103506 PMCID: PMC8814826 DOI: 10.1177/17590914221076698] [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] [Indexed: 12/28/2022] Open
Abstract
The retina of vertebrates is responsible for capturing light through visual
(cones and rods) and non-visual photoreceptors (intrinsically photosensitive
retinal ganglion cells and horizontal cells) triggering a number of essential
activities associated to image- and non-image forming functions (photic
entrainment of daily rhythms, pupillary light reflexes, pineal melatonin
inhibition, among others). Although the retina contains diverse types of
neuronal based-photoreceptors cells, originally classified as ciliary- or
rhabdomeric-like types, in recent years, it has been shown that the major glial
cell type of the retina, the Müller glial cells (MC), express blue photopigments
as Opn3 (encephalopsin) and Opn5 (neuropsin) and display light responses
associated to intracellular Ca2 + mobilization. These findings strongly propose
MC as novel retinal photodetectors (Rios et al., 2019). Herein, we further
investigated the intrinsic light responses of primary cultures of MC from
embryonic chicken retinas specially focused on Ca2 + mobilization by
fluorescence imaging and the identity of the internal Ca2 + stores responsible
for blue light responses. Results clearly demonstrated that light responses were
specific to blue light of long time exposure, and that the main Ca2 + reservoir
to trigger downstream responses came from intracellular stores localized in the
endoplasmic reticulum These observations bring more complexity to the intrinsic
photosensitivity of retinal cells, particularly with regard to the detection of
light in the blue range of visible spectra, and add novel functions to glial
cells cooperating with other photoreceptors to detect and integrate ambient
light in the retinal circuit and participate in cell to cell communication.
Summary statement:
Non-neuronal cells in the vertebrate retina, Muller glial cells, express
non-canonical photopigments and sense blue light causing calcium release from
intracellular stores strongly suggesting a novel intrinsic photosensitivity and
new regulatory events mediating light-driven processes with yet unknown
physiological implications.
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Affiliation(s)
- Natalia A Marchese
- 373607CIQUIBIC-CONICET, Facultad de Ciencias Químicas, 28217Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Química Biológica "Ranwel Caputto", Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Maximiliano N Ríos
- 373607CIQUIBIC-CONICET, Facultad de Ciencias Químicas, 28217Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Química Biológica "Ranwel Caputto", Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Mario E Guido
- 373607CIQUIBIC-CONICET, Facultad de Ciencias Químicas, 28217Universidad Nacional de Córdoba, Córdoba, Argentina.,Departamento de Química Biológica "Ranwel Caputto", Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina
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9
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Schulte A, Bieniussa L, Gupta R, Samtleben S, Bischler T, Doering K, Sodmann P, Rittner H, Blum R. Homeostatic calcium fluxes, ER calcium release, SOCE, and calcium oscillations in cultured astrocytes are interlinked by a small calcium toolkit. Cell Calcium 2021; 101:102515. [PMID: 34896701 DOI: 10.1016/j.ceca.2021.102515] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 12/27/2022]
Abstract
How homeostatic ER calcium fluxes shape cellular calcium signals is still poorly understood. Here we used dual-color calcium imaging (ER-cytosol) and transcriptome analysis to link candidates of the calcium toolkit of astrocytes with homeostatic calcium signals. We found molecular and pharmacological evidence that P/Q-type channel Cacna1a contributes to depolarization-dependent calcium entry in astrocytes. For stimulated ER calcium release, the cells express the phospholipase Cb3, IP3 receptors Itpr1 and Itpr2, but no ryanodine receptors (Ryr1-3). After IP3-induced calcium release, Stim1/2 - Orai1/2/3 most likely mediate SOCE. The Serca2 (Atp2a2) is the candidate for refilling of the ER calcium store. The cells highly express adenosine receptor Adora1a for IP3-induced calcium release. Accordingly, adenosine induces fast ER calcium release and subsequent ER calcium oscillations. After stimulation, calcium refilling of the ER depends on extracellular calcium. In response to SOCE, astrocytes show calcium-induced calcium release, notably even after ER calcium was depleted by extracellular calcium removal in unstimulated cells. In contrast, spontaneous ER-cytosol calcium oscillations were not fully dependent on extracellular calcium, as ER calcium oscillations could persist over minutes in calcium-free solution. Additionally, cell-autonomous calcium oscillations show a second-long spatial and temporal delay in the signal dynamics of ER and cytosolic calcium. Our data reveal a rather strong contribution of homeostatic calcium fluxes in shaping IP3-induced and calcium-induced calcium release as well as spatiotemporal components of intracellular calcium oscillations.
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Affiliation(s)
- Annemarie Schulte
- Department of Neurology, University Hospital of Würzburg, Würzburg, 97080 Germany; Institute of Clinical Neurobiology, University Hospital of Würzburg, Würzburg, 97078 Germany
| | - Linda Bieniussa
- Institute of Clinical Neurobiology, University Hospital of Würzburg, Würzburg, 97078 Germany; Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Germany
| | - Rohini Gupta
- Department of Neurology, University Hospital of Würzburg, Würzburg, 97080 Germany; Institute of Clinical Neurobiology, University Hospital of Würzburg, Würzburg, 97078 Germany
| | - Samira Samtleben
- Institute of Clinical Neurobiology, University Hospital of Würzburg, Würzburg, 97078 Germany; Department of Cell Biology, University of Alberta, MSM, Edmonton, T6G 2H7 Canada
| | - Thorsten Bischler
- Core Unit Systems Medicine, University of Würzburg, Würzburg, 97080 Germany
| | - Kristina Doering
- Core Unit Systems Medicine, University of Würzburg, Würzburg, 97080 Germany; Department of Human Genetics, Ruhr University Bochum, Bochum, Germany
| | - Philipp Sodmann
- Department of Internal Medicine II, University Hospital of Würzburg, Würzburg, 97080 Germany
| | - Heike Rittner
- Department of Anesthesiology, Intensive Care, Emergency Medicine and Pain Therapy, University Hospital of Würzburg, Würzburg, 97074 Germany
| | - Robert Blum
- Department of Neurology, University Hospital of Würzburg, Würzburg, 97080 Germany; Institute of Clinical Neurobiology, University Hospital of Würzburg, Würzburg, 97078 Germany.
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Wang Q, Kong Y, Lin S, Wu DY, Hu J, Huang L, Zang WS, Li XW, Yang JM, Gao TM. The ATP Level in the mPFC Mediates the Antidepressant Effect of Calorie Restriction. Neurosci Bull 2021; 37:1303-1313. [PMID: 34089507 PMCID: PMC8423953 DOI: 10.1007/s12264-021-00726-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/31/2021] [Indexed: 11/25/2022] Open
Abstract
Food deprivation can rescue obesity and overweight-induced mood disorders, and promote mood performance in normal subjects. Animal studies and clinical research have revealed the antidepressant-like effect of calorie restriction, but little is known about the mechanism of calorie restriction-induced mood modification. Previous studies have found that astrocytes modulate depressive-like behaviors. Inositol 1,4,5-trisphosphate receptor type 2 (IP3R2) is the predominant isoform in mediating astrocyte Ca2+ signals and its genetic knockout mice are widely used to study astrocyte function in vivo. In this study, we showed that deletion of IP3R2 blocked the antidepressant-like effect induced by calorie restriction. In vivo microdialysis experiments demonstrated that calorie restriction induced an increase in ATP level in the medial prefrontal cortex (mPFC) in naïve mice but this effect disappeared in IP3R2-knockout mice, suggesting a role of astrocytic ATP in the calorie restriction-induced antidepressant effect. Further experiments showed that systemic administration and local infusion of ATP into the mPFC induced an antidepressant effect, whereas decreasing ATP by Apyrase in the mPFC blocked calorie restriction-induced antidepressant regulation. Together, these findings support a role for astrocytic ATP in the antidepressant-like effect caused by calorie restriction.
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Affiliation(s)
- Qian Wang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Ying Kong
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Song Lin
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Ding-Yu Wu
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Jian Hu
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Lang Huang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Wen-Si Zang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Xiao-Wen Li
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Jian-Ming Yang
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China
| | - Tian-Ming Gao
- State Key Laboratory of Organ Failure Research, Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brian Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.
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11
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Sherwood MW, Arizono M, Panatier A, Mikoshiba K, Oliet SHR. Astrocytic IP 3Rs: Beyond IP 3R2. Front Cell Neurosci 2021; 15:695817. [PMID: 34393726 PMCID: PMC8363081 DOI: 10.3389/fncel.2021.695817] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 06/30/2021] [Indexed: 12/31/2022] Open
Abstract
Astrocytes are sensitive to ongoing neuronal/network activities and, accordingly, regulate neuronal functions (synaptic transmission, synaptic plasticity, behavior, etc.) by the context-dependent release of several gliotransmitters (e.g., glutamate, glycine, D-serine, ATP). To sense diverse input, astrocytes express a plethora of G-protein coupled receptors, which couple, via Gi/o and Gq, to the intracellular Ca2+ release channel IP3-receptor (IP3R). Indeed, manipulating astrocytic IP3R-Ca2+ signaling is highly consequential at the network and behavioral level: Depleting IP3R subtype 2 (IP3R2) results in reduced GPCR-Ca2+ signaling and impaired synaptic plasticity; enhancing IP3R-Ca2+ signaling affects cognitive functions such as learning and memory, sleep, and mood. However, as a result of discrepancies in the literature, the role of GPCR-IP3R-Ca2+ signaling, especially under physiological conditions, remains inconclusive. One primary reason for this could be that IP3R2 has been used to represent all astrocytic IP3Rs, including IP3R1 and IP3R3. Indeed, IP3R1 and IP3R3 are unique Ca2+ channels in their own right; they have unique biophysical properties, often display distinct distribution, and are differentially regulated. As a result, they mediate different physiological roles to IP3R2. Thus, these additional channels promise to enrich the diversity of spatiotemporal Ca2+ dynamics and provide unique opportunities for integrating neuronal input and modulating astrocyte–neuron communication. The current review weighs evidence supporting the existence of multiple astrocytic-IP3R isoforms, summarizes distinct sub-type specific properties that shape spatiotemporal Ca2+ dynamics. We also discuss existing experimental tools and future refinements to better recapitulate the endogenous activities of each IP3R isoform.
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Affiliation(s)
- Mark W Sherwood
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Misa Arizono
- University of Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR 5297, Bordeaux, France
| | - Aude Panatier
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
| | - Katsuhiko Mikoshiba
- ShanghaiTech University, Shanghai, China.,Faculty of Science, Toho University, Funabashi, Japan.,RIKEN CLST, Kobe, Japan
| | - Stéphane H R Oliet
- University of Bordeaux, INSERM, Neurocentre Magendie, U1215, Bordeaux, France
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12
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Saito K, Shigetomi E, Koizumi S. [Alexander disease: diversity of cell population and interactions between neuron and glia]. Nihon Yakurigaku Zasshi 2021; 156:239-243. [PMID: 34193704 DOI: 10.1254/fpj.21028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Alexander disease (AxD) is a rare neurodegenerative disorder caused by the mutations in glial fibrillary acidic protein (GFAP) gene. Rosenthal fiber formations in astrocytes are the pathological hallmarks of AxD. Astrocyte dysfunction in the AxD brain is considered to be involved in its pathogenesis. We have previously reported that in AxD model mice aberrant Ca2+ signals in astrocytes were associated with the upregulation of reactive phenotype. Reactive astrocytes are conditions that lead to morphological, functional, and molecular changes by responding to various pathological insults (trauma, inflammation, ischemia), and environmental stimuli. Recent technological advances in single-cell gene expression analysis have revealed that astrocytes have heterogeneity by indicating that they form sub population with different characteristics depending on the brain region, the growth development, aging stage, and the pathological condition. AxD astrocytes are also thought to constitute a heterogeneous population with diverse properties and functions. Moreover, it is presumed that AxD pathogenesis occur due to interactions with neurons and other glial cells, as well as the microenvironment in tissues. Research strategies based on these perspectives will help us understand AxD pathology better and may lead to the elucidation of disease modifiers and clinical diversity.
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Affiliation(s)
- Kozo Saito
- Department of Neuropharmcology, Interdisciplinary Graduate School of Medicine
| | - Eiji Shigetomi
- Department of Neuropharmcology, Interdisciplinary Graduate School of Medicine
| | - Schuichi Koizumi
- Department of Neuropharmcology, Interdisciplinary Graduate School of Medicine
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13
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Lim EY, Ye L, Paukert M. Potential and Realized Impact of Astroglia Ca 2 + Dynamics on Circuit Function and Behavior. Front Cell Neurosci 2021; 15:682888. [PMID: 34163330 PMCID: PMC8215280 DOI: 10.3389/fncel.2021.682888] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/03/2021] [Indexed: 11/13/2022] Open
Abstract
Astroglia display a wide range of spontaneous and behavioral state-dependent Ca2+ dynamics. During heightened vigilance, noradrenergic signaling leads to quasi-synchronous Ca2+ elevations encompassing soma and processes across the brain-wide astroglia network. Distinct from this vigilance-associated global Ca2+ rise are apparently spontaneous fluctuations within spatially restricted microdomains. Over the years, several strategies have been pursued to shed light on the physiological impact of these signals including deletion of endogenous ion channels or receptors and reduction of intracellular Ca2+ through buffering, extrusion or inhibition of release. Some experiments that revealed the most compelling behavioral alterations employed chemogenetic and optogenetic manipulations to modify astroglia Ca2+ signaling. However, there is considerable contrast between these findings and the comparatively modest effects of inhibiting endogenous sources of Ca2+. In this review, we describe the underlying mechanisms of various forms of astroglia Ca2+ signaling as well as the functional consequences of their inhibition. We then discuss how the effects of exogenous astroglia Ca2+ modification combined with our knowledge of physiological mechanisms of astroglia Ca2+ activation could guide further refinement of behavioral paradigms that will help elucidate the natural Ca2+-dependent function of astroglia.
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Affiliation(s)
- Eunice Y. Lim
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Liang Ye
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Martin Paukert
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States,Center for Biomedical Neuroscience, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States,*Correspondence: Martin Paukert,
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14
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McNeill J, Rudyk C, Hildebrand ME, Salmaso N. Ion Channels and Electrophysiological Properties of Astrocytes: Implications for Emergent Stimulation Technologies. Front Cell Neurosci 2021; 15:644126. [PMID: 34093129 PMCID: PMC8173131 DOI: 10.3389/fncel.2021.644126] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Accepted: 04/26/2021] [Indexed: 12/12/2022] Open
Abstract
Astrocytes comprise a heterogeneous cell population characterized by distinct morphologies, protein expression and function. Unlike neurons, astrocytes do not generate action potentials, however, they are electrically dynamic cells with extensive electrophysiological heterogeneity and diversity. Astrocytes are hyperpolarized cells with low membrane resistance. They are heavily involved in the modulation of K+ and express an array of different voltage-dependent and voltage-independent channels to help with this ion regulation. In addition to these K+ channels, astrocytes also express several different types of Na+ channels; intracellular Na+ signaling in astrocytes has been linked to some of their functional properties. The physiological hallmark of astrocytes is their extensive intracellular Ca2+ signaling cascades, which vary at the regional, subregional, and cellular levels. In this review article, we highlight the physiological properties of astrocytes and the implications for their function and influence of network and synaptic activity. Furthermore, we discuss the implications of these differences in the context of optogenetic and DREADD experiments and consider whether these tools represent physiologically relevant techniques for the interrogation of astrocyte function.
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Affiliation(s)
- Jessica McNeill
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
| | | | | | - Natalina Salmaso
- Department of Neuroscience, Carleton University, Ottawa, ON, Canada
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15
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Lim D, Semyanov A, Genazzani A, Verkhratsky A. Calcium signaling in neuroglia. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2021; 362:1-53. [PMID: 34253292 DOI: 10.1016/bs.ircmb.2021.01.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glial cells exploit calcium (Ca2+) signals to perceive the information about the activity of the nervous tissue and the tissue environment to translate this information into an array of homeostatic, signaling and defensive reactions. Astrocytes, the best studied glial cells, use several Ca2+ signaling generation pathways that include Ca2+ entry through plasma membrane, release from endoplasmic reticulum (ER) and from mitochondria. Activation of metabotropic receptors on the plasma membrane of glial cells is coupled to an enzymatic cascade in which a second messenger, InsP3 is generated thus activating intracellular Ca2+ release channels in the ER endomembrane. Astrocytes also possess store-operated Ca2+ entry and express several ligand-gated Ca2+ channels. In vivo astrocytes generate heterogeneous Ca2+ signals, which are short and frequent in distal processes, but large and relatively rare in soma. In response to neuronal activity intracellular and inter-cellular astrocytic Ca2+ waves can be produced. Astrocytic Ca2+ signals are involved in secretion, they regulate ion transport across cell membranes, and are contributing to cell morphological plasticity. Therefore, astrocytic Ca2+ signals are linked to fundamental functions of the central nervous system ranging from synaptic transmission to behavior. In oligodendrocytes, Ca2+ signals are generated by plasmalemmal Ca2+ influx, or by release from intracellular stores, or by combination of both. Microglial cells exploit Ca2+ permeable ionotropic purinergic receptors and transient receptor potential channels as well as ER Ca2+ release. In this contribution, basic morphology of glial cells, glial Ca2+ signaling toolkit, intracellular Ca2+ signals and Ca2+-regulated functions are discussed with focus on astrocytes.
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Affiliation(s)
- Dmitry Lim
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, Italy.
| | - Alexey Semyanov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia; Faculty of Biology, Moscow State University, Moscow, Russia; Sechenov First Moscow State Medical University, Moscow, Russia
| | - Armando Genazzani
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, Italy
| | - Alexei Verkhratsky
- Sechenov First Moscow State Medical University, Moscow, Russia; Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, Bilbao, Spain.
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16
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Sensing and Regulating Synaptic Activity by Astrocytes at Tripartite Synapse. Neurochem Res 2021; 46:2580-2585. [PMID: 33837868 PMCID: PMC10159683 DOI: 10.1007/s11064-021-03317-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/27/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022]
Abstract
Astrocytes are recognized as more important cells than historically thought in synaptic function through the reciprocal exchange of signaling with the neuronal synaptic elements. The idea that astrocytes are active elements in synaptic physiology is conceptualized in the Tripartite Synapse concept. This review article presents and discusses recent representative examples that highlight the heterogeneity of signaling in tripartite synapse function and its consequences on neural network function and animal behavior.
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17
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Jaudon F, Chiacchiaretta M, Albini M, Ferroni S, Benfenati F, Cesca F. Kidins220/ARMS controls astrocyte calcium signaling and neuron-astrocyte communication. Cell Death Differ 2020; 27:1505-1519. [PMID: 31624352 PMCID: PMC7206051 DOI: 10.1038/s41418-019-0431-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 09/30/2019] [Accepted: 09/30/2019] [Indexed: 12/22/2022] Open
Abstract
Through their ability to modulate synaptic transmission, glial cells are key regulators of neuronal circuit formation and activity. Kidins220/ARMS (kinase-D interacting substrate of 220 kDa/ankyrin repeat-rich membrane spanning) is one of the key effectors of the neurotrophin pathways in neurons where it is required for differentiation, survival, and plasticity. However, its role in glial cells remains largely unknown. Here, we show that ablation of Kidins220 in primary cultured astrocytes induced defects in calcium (Ca2+) signaling that were linked to altered store-operated Ca2+ entry and strong overexpression of the transient receptor potential channel TRPV4. Moreover, Kidins220-/- astrocytes were more sensitive to genotoxic stress. We also show that Kidins220 expression in astrocytes is required for the establishment of proper connectivity of cocultured wild-type neurons. Altogether, our data reveal a previously unidentified role for astrocyte-expressed Kidins220 in the control of glial Ca2+ dynamics, survival/death pathways and astrocyte-neuron communication.
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Affiliation(s)
- Fanny Jaudon
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132, Genova, Italy
| | - Martina Chiacchiaretta
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132, Genova, Italy
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA, USA
| | - Martina Albini
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132, Genova, Italy
- Department of Experimental Medicine, University of Genova, 16132, Genova, Italy
| | - Stefano Ferroni
- Department of Pharmacy and Biotechnology, University of Bologna, 40126, Bologna, Italy
| | - Fabio Benfenati
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132, Genova, Italy
- IRCCS Ospedale Policlinico San Martino, Genova, Italy
| | - Fabrizia Cesca
- Center for Synaptic Neuroscience and Technology, Istituto Italiano di Tecnologia, 16132, Genova, Italy.
- Department of Life Sciences, University of Trieste, 34127, Trieste, Italy.
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18
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Kofuji P, Araque A. G-Protein-Coupled Receptors in Astrocyte-Neuron Communication. Neuroscience 2020; 456:71-84. [PMID: 32224231 DOI: 10.1016/j.neuroscience.2020.03.025] [Citation(s) in RCA: 119] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 03/13/2020] [Accepted: 03/18/2020] [Indexed: 12/11/2022]
Abstract
Astrocytes, a major type of glial cell, are known to play key supportive roles in brain function, contributing to ion and neurotransmitter homeostasis, maintaining the blood-brain barrier and providing trophic and metabolic support for neurons. Besides these support functions, astrocytes are emerging as important elements in brain physiology through signaling exchange with neurons at tripartite synapses. Astrocytes express a wide variety of neurotransmitter transporters and receptors that allow them to sense and respond to synaptic activity. Principal among them are the G-protein-coupled receptors (GPCRs) in astrocytes because their activation by synaptically released neurotransmitters leads to mobilization of intracellular calcium. In turn, activated astrocytes release neuroactive substances called gliotransmitters, such as glutamate, GABA, and ATP/adenosine that lead to synaptic regulation through activation of neuronal GPCRs. In this review we will present and discuss recent evidence demonstrating the critical roles played by GPCRs in the bidirectional astrocyte-neuron signaling, and their crucial involvement in the astrocyte-mediated regulation of synaptic transmission and plasticity.
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Affiliation(s)
- Paulo Kofuji
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Alfonso Araque
- Department of Neuroscience, University of Minnesota, Minneapolis, MN 55455, USA.
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19
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Yu X, Nagai J, Khakh BS. Improved tools to study astrocytes. Nat Rev Neurosci 2020; 21:121-138. [DOI: 10.1038/s41583-020-0264-8] [Citation(s) in RCA: 112] [Impact Index Per Article: 28.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/09/2020] [Indexed: 12/21/2022]
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20
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Neuromodulators and Long-Term Synaptic Plasticity in Learning and Memory: A Steered-Glutamatergic Perspective. Brain Sci 2019; 9:brainsci9110300. [PMID: 31683595 PMCID: PMC6896105 DOI: 10.3390/brainsci9110300] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Revised: 10/24/2019] [Accepted: 10/29/2019] [Indexed: 12/19/2022] Open
Abstract
The molecular pathways underlying the induction and maintenance of long-term synaptic plasticity have been extensively investigated revealing various mechanisms by which neurons control their synaptic strength. The dynamic nature of neuronal connections combined with plasticity-mediated long-lasting structural and functional alterations provide valuable insights into neuronal encoding processes as molecular substrates of not only learning and memory but potentially other sensory, motor and behavioural functions that reflect previous experience. However, one key element receiving little attention in the study of synaptic plasticity is the role of neuromodulators, which are known to orchestrate neuronal activity on brain-wide, network and synaptic scales. We aim to review current evidence on the mechanisms by which certain modulators, namely dopamine, acetylcholine, noradrenaline and serotonin, control synaptic plasticity induction through corresponding metabotropic receptors in a pathway-specific manner. Lastly, we propose that neuromodulators control plasticity outcomes through steering glutamatergic transmission, thereby gating its induction and maintenance.
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21
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Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
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22
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Pinto-Duarte A, Roberts AJ, Ouyang K, Sejnowski TJ. Impairments in remote memory caused by the lack of Type 2 IP 3 receptors. Glia 2019; 67:1976-1989. [PMID: 31348567 DOI: 10.1002/glia.23679] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 06/27/2019] [Accepted: 06/27/2019] [Indexed: 11/10/2022]
Abstract
The second messenger inositol 1,4,5-trisphosphate (IP3 ) is paramount for signal transduction in biological cells, mediating Ca2+ release from the endoplasmic reticulum. Of the three isoforms of IP3 receptors identified in the nervous system, Type 2 (IP3 R2) is the main isoform expressed by astrocytes. The complete lack of IP3 R2 in transgenic mice was shown to significantly disrupt Ca2+ signaling in astrocytes, while leaving neuronal intracellular pathways virtually unperturbed. Whether and how this predominantly nonneuronal receptor might affect long-term memory function has been a matter of intense debate. In this work, we found that the absence of IP3 R2-mediated signaling did not disrupt normal learning or recent (24-48 h) memory. Contrary to expectations, however, mice lacking IP3 R2 exhibited remote (2-4 weeks) memory deficits. Not only did the lack of IP3 R2 impair remote recognition, fear, and spatial memories, but it also prevented naturally occurring post-encoding memory enhancements consequent to memory consolidation. Consistent with the key role played by the downscaling of synaptic transmission in memory consolidation, we found that NMDAR-dependent long-term depression was abnormal in ex vivo hippocampal slices acutely prepared from IP3 R2-deficient mice, a deficit that could be prevented upon supplementation with D-serine - an NMDA-receptor co-agonist whose synthesis depends upon astrocytes' activity. Our results reveal that IP3 R2 activation, which in the brain is paramount for Ca2+ signaling in astrocytes, but not in neurons, can help shape brain plasticity by enhancing the consolidation of newly acquired information into long-term memories that can guide remote cognitive behaviors.
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Affiliation(s)
- António Pinto-Duarte
- Computational Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California.,Institute for Neural Computation, University of California San Diego, La Jolla, California
| | - Amanda J Roberts
- Animal Models Core Facility, The Scripps Research Institute, La Jolla, California
| | - Kunfu Ouyang
- School of Chemical Biology and Biotechnology, State Key Laboratory of Chemical Oncogenomics, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Terrence J Sejnowski
- Computational Neurobiology Laboratory, Salk Institute for Biological Studies, La Jolla, California.,Institute for Neural Computation, University of California San Diego, La Jolla, California.,Division of Biological Sciences, University of California San Diego, La Jolla, California
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23
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Smith NA, Bekar LK, Nedergaard M. Astrocytic Endocannabinoids Mediate Hippocampal Transient Heterosynaptic Depression. Neurochem Res 2019; 45:100-108. [PMID: 31254249 DOI: 10.1007/s11064-019-02834-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 06/14/2019] [Accepted: 06/20/2019] [Indexed: 12/29/2022]
Abstract
Astrocytes are highly dynamic cells that modulate synaptic transmission within a temporal domain of seconds to minutes in physiological contexts such as Long-Term Potentiation (LTP) and Heterosynaptic Depression (HSD). Recent studies have revealed that astrocytes also modulate a faster form of synaptic activity (milliseconds to seconds) known as Transient Heterosynaptic Depression (tHSD). However, the mechanism underlying astrocytic modulation of tHSD is not fully understood. Are the traditional gliotransmitters ATP or glutamate released via hemichannels/vesicles or are other, yet, unexplored pathways involved? Using various approaches to manipulate astrocytes, including the Krebs cycle inhibitor fluoroacetate, connexin 43/30 double knockout mice (hemichannels), and inositol triphosphate type-2 receptor knockout mice, we confirmed early reports demonstrating that astrocytes are critical for tHSD. We also confirmed the importance of group II metabotropic glutamate receptors (mGluRs) in astrocytic modulation of tHSD using a group II agonist. Using dominant negative SNARE mice, which have disrupted glial vesicle function, we also found that vesicular release of gliotransmitters and activation of adenosine A1 receptors are not required for tHSD. As astrocytes can release lipids upon receptor stimulation, we asked if astrocyte-derived endocannabinoids are involved in tHSD. Interestingly, a cannabinoid receptor 1 (CB1R) antagonist blocked and an inhibitor of the endogenous endocannabinoid 2-arachidonyl glycerol (2-AG) degradation potentiates tHSD in hippocampal slices. Taken together, this study provides the first evidence for group II mGluR-mediated astrocytic endocannabinoids in transiently suppressing presynaptic neurotransmitter release associated with the phenomenon of tHSD.
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Affiliation(s)
- Nathan A Smith
- Division of Glia Disease and Therapeutics, Dept. of Neurosurgery, Center for Translational Neuromedicine, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA.
- Center for Neuroscience, Children's Research Institute, Children's National Medical Center, 111 Michigan Ave, Washington, NW, 20010, USA.
- George Washington University School of Medicine and Health Sciences, Washington, DC, 20052, USA.
| | - Lane K Bekar
- Department of Anatomy, Physiology and Pharmacology, University of Saskatchewan, Saskatoon, SK, S7N 5E5, Canada
| | - Maiken Nedergaard
- Division of Glia Disease and Therapeutics, Dept. of Neurosurgery, Center for Translational Neuromedicine, School of Medicine and Dentistry, University of Rochester, Rochester, NY, 14642, USA
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24
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Lomash RM, Petralia RS, Holtzclaw LA, Tsuda MC, Wang YX, Badger JD, Cameron HA, Youle RJ, Roche KW. Neurolastin, a dynamin family GTPase, translocates to mitochondria upon neuronal stress and alters mitochondrial morphology in vivo. J Biol Chem 2019; 294:11498-11512. [PMID: 31177092 DOI: 10.1074/jbc.ra118.007245] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 06/03/2019] [Indexed: 02/05/2023] Open
Abstract
Neurolastin is a dynamin family GTPase that also contains a RING domain and exhibits both GTPase and E3 ligase activities. It is specifically expressed in the brain and is important for synaptic transmission, as neurolastin knockout animals have fewer dendritic spines and exhibit a reduction in functional synapses. Our initial study of neurolastin revealed that it is membrane-associated and partially co-localizes with endosomes. Using various biochemical and cell-culture approaches, we now show that neurolastin also localizes to mitochondria in HeLa cells, cultured neurons, and brain tissue. We found that the mitochondrial localization of neurolastin depends upon an N-terminal mitochondrial targeting sequence and that neurolastin is imported into the mitochondrial intermembrane space. Although neurolastin was only partially mitochondrially localized at steady state, it displayed increased translocation to mitochondria in response to neuronal stress and mitochondrial fragmentation. Interestingly, inactivation or deletion of neurolastin's RING domain also increased its mitochondrial localization. Using EM, we observed that neurolastin knockout animals have smaller but more numerous mitochondria in cerebellar Purkinje neurons, indicating that neurolastin regulates mitochondrial morphology. We conclude that the brain-specific dynamin GTPase neurolastin exhibits stress-responsive localization to mitochondria and is required for proper mitochondrial morphology.
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Affiliation(s)
- Richa Madan Lomash
- Receptor Biology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892
| | - Ronald S Petralia
- Advanced Imaging Core, NIDCD, National Institutes of Health, Bethesda, Maryland 20892
| | - Lynne A Holtzclaw
- Microscopy and Imaging Core, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Mumeko C Tsuda
- Section on Neuroplasticity, NIMH, National Institutes of Health, Bethesda, Maryland 20892
| | - Ya-Xian Wang
- Advanced Imaging Core, NIDCD, National Institutes of Health, Bethesda, Maryland 20892
| | - John D Badger
- Receptor Biology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892
| | - Heather A Cameron
- Section on Neuroplasticity, NIMH, National Institutes of Health, Bethesda, Maryland 20892
| | - Richard J Youle
- Surgical Neurology Branch, NINDS, National Institutes of Health, Bethesda, Maryland 20892
| | - Katherine W Roche
- Receptor Biology Section, NINDS, National Institutes of Health, Bethesda, Maryland 20892
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25
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Okubo Y, Iino M. Visualization of astrocytic intracellular Ca 2+ mobilization. J Physiol 2019; 598:1671-1681. [PMID: 30825213 DOI: 10.1113/jp277609] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2018] [Accepted: 02/06/2019] [Indexed: 11/08/2022] Open
Abstract
Astrocytes generate robust intracellular Ca2+ concentration changes (Ca2+ signals), which are assumed to regulate astrocytic functions that play crucial roles in the regulation of brain functions. One frequently used strategy for exploring the role of astrocytic Ca2+ signalling is the use of mice deficient in the type 2 inositol 1,4,5-trisphosphate receptor (IP3 R2). These IP3 R2-knockout (KO) mice are reportedly devoid of Ca2+ mobilization from the endoplasmic reticulum (ER) in astrocytes. However, they have shown no functional deficits in several studies, causing a heated debate as to the functional relevance of ER-mediated Ca2+ signalling in astrocytes. Recently, the assumption that Ca2+ mobilization from the ER is absent in IP3 R2-KO astrocytes has been re-evaluated using intraorganellar Ca2+ imaging techniques. The new results indicated that IP3 R2-independent Ca2+ release may generate Ca2+ nanodomains around the ER, which may help explain the absence of functional deficits in IP3 R2-KO mice.
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Affiliation(s)
- Yohei Okubo
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, 133-0033, Japan
| | - Masamitsu Iino
- Division of Cellular and Molecular Pharmacology, Nihon University School of Medicine, Tokyo, 173-8610, Japan
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Ashhad S, Narayanan R. Stores, Channels, Glue, and Trees: Active Glial and Active Dendritic Physiology. Mol Neurobiol 2019; 56:2278-2299. [PMID: 30014322 PMCID: PMC6394607 DOI: 10.1007/s12035-018-1223-5] [Citation(s) in RCA: 15] [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: 11/24/2017] [Accepted: 07/03/2018] [Indexed: 02/07/2023]
Abstract
Glial cells and neuronal dendrites were historically assumed to be passive structures that play only supportive physiological roles, with no active contribution to information processing in the central nervous system. Research spanning the past few decades has clearly established this assumption to be far from physiological realities. Whereas the discovery of active channel conductances and their localized plasticity was the turning point for dendritic structures, the demonstration that glial cells release transmitter molecules and communicate across the neuroglia syncytium through calcium wave propagation constituted path-breaking discoveries for glial cell physiology. An additional commonality between these two structures is the ability of calcium stores within their endoplasmic reticulum (ER) to support active propagation of calcium waves, which play crucial roles in the spatiotemporal integration of information within and across cells. Although there have been several demonstrations of regulatory roles of glial cells and dendritic structures in achieving common physiological goals such as information propagation and adaptability through plasticity, studies assessing physiological interactions between these two active structures have been few and far. This lacuna is especially striking given the strong connectivity that is known to exist between these two structures through several complex and tightly intercoupled mechanisms that also recruit their respective ER structures. In this review, we present brief overviews of the parallel literatures on active dendrites and active glial physiology and make a strong case for future studies to directly assess the strong interactions between these two structures in regulating physiology and pathophysiology of the brain.
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Affiliation(s)
- Sufyan Ashhad
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
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27
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Multiple Lines of Evidence Indicate That Gliotransmission Does Not Occur under Physiological Conditions. J Neurosci 2019; 38:3-13. [PMID: 29298904 DOI: 10.1523/jneurosci.0016-17.2017] [Citation(s) in RCA: 126] [Impact Index Per Article: 25.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2017] [Revised: 09/01/2017] [Accepted: 10/02/2017] [Indexed: 12/22/2022] Open
Abstract
A major controversy persists within the field of glial biology concerning whether or not, under physiological conditions, neuronal activity leads to Ca2+-dependent release of neurotransmitters from astrocytes, a phenomenon known as gliotransmission. Our perspective is that, while we and others can apply techniques to cause gliotransmission, there is considerable evidence gathered using astrocyte-specific and more physiological approaches which suggests that gliotransmission is a pharmacological phenomenon rather than a physiological process. Approaches providing evidence against gliotransmission include stimulation of Gq-GPCRs expressed only in astrocytes, as well as removal of the primary proposed source of astrocyte Ca2+ responsible for gliotransmission. These approaches contrast with those supportive of gliotransmission, which include mechanical stimulation, strong astrocytic depolarization using whole-cell patch-clamp or optogenetics, uncaging Ca2+ or IP3, chelating Ca2+ using BAPTA, and nonspecific bath application of agonists to receptors expressed by a multitude of cell types. These techniques are not subtle and therefore are not supportive of recent suggestions that gliotransmission requires very specific and delicate temporal and spatial requirements. Other evidence, including lack of propagating Ca2+ waves between astrocytes in healthy tissue, lack of expression of vesicular release machinery, and the demise of the d-serine gliotransmission hypothesis, provides additional evidence against gliotransmission. Overall, the data suggest that Ca2+-dependent release of neurotransmitters is the province of neurons, not astrocytes, in the intact brain under physiological conditions.Dual Perspectives Companion Paper: Gliotransmission: Beyond Black-and-White, by Iaroslav Savtchouk and Andrea Volterra.
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Mays JC, Kelly MC, Coon SL, Holtzclaw L, Rath MF, Kelley MW, Klein DC. Single-cell RNA sequencing of the mammalian pineal gland identifies two pinealocyte subtypes and cell type-specific daily patterns of gene expression. PLoS One 2018; 13:e0205883. [PMID: 30347410 PMCID: PMC6197868 DOI: 10.1371/journal.pone.0205883] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2018] [Accepted: 10/03/2018] [Indexed: 12/31/2022] Open
Abstract
The vertebrate pineal gland is dedicated to the production of the hormone melatonin, which increases at night to influence circadian and seasonal rhythms. This increase is associated with dramatic changes in the pineal transcriptome. Here, single-cell analysis of the rat pineal transcriptome was approached by sequencing mRNA from ~17,000 individual pineal cells, with the goals of profiling the cells that comprise the pineal gland and examining the proposal that there are two distinct populations of pinealocytes differentiated by the expression of Asmt, which encodes the enzyme that converts N-acetylserotonin to melatonin. In addition, this analysis provides evidence of cell-specific time-of-day dependent changes in gene expression. Nine transcriptomically distinct cell types were identified: ~90% were classified as melatonin-producing α- and β-pinealocytes (1:19 ratio). Non-pinealocytes included three astrocyte subtypes, two microglia subtypes, vascular and leptomeningeal cells, and endothelial cells. α-Pinealocytes were distinguished from β-pinealocytes by ~3-fold higher levels of Asmt transcripts. In addition, α-pinealocytes have transcriptomic differences that likely enhance melatonin formation by increasing the availability of the Asmt cofactor S-adenosylmethionine, resulting from increased production of a precursor of S-adenosylmethionine, ATP. These transcriptomic differences include ~2-fold higher levels of the ATP-generating oxidative phosphorylation transcriptome and ~8-fold lower levels of the ribosome transcriptome, which is expected to reduce the consumption of ATP by protein synthesis. These findings suggest that α-pinealocytes have a specialized role in the pineal gland: efficiently O-methylating the N-acetylserotonin produced and released by β-pinealocytes, thereby improving the overall efficiency of melatonin synthesis. We have also identified transcriptomic changes that occur between night and day in seven cell types, the majority of which occur in β-pinealocytes and to a lesser degree in α-pinealocytes; many of these changes were mimicked by adrenergic stimulation with isoproterenol. The cellular heterogeneity of the pineal gland as revealed by this study provides a new framework for understanding pineal cell biology at single-cell resolution.
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Affiliation(s)
- Joseph C. Mays
- Section on Developmental Neuroscience, Laboratory of Cochlear Development, Division of Intramural Research, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Michael C. Kelly
- Section on Developmental Neuroscience, Laboratory of Cochlear Development, Division of Intramural Research, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Steven L. Coon
- Molecular Genomics Core Facility, Office of the Scientific Director, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Lynne Holtzclaw
- Microscopy and Imaging Core, Office of the Scientific Director, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Martin F. Rath
- Department of Neuroscience, Panum Institute, University of Copenhagen, Copenhagen, Denmark
| | - Matthew W. Kelley
- Section on Developmental Neuroscience, Laboratory of Cochlear Development, Division of Intramural Research, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States of America
| | - David C. Klein
- Office of the Scientific Director, Intramural Research Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, United States of America
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29
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Okubo Y, Kanemaru K, Suzuki J, Kobayashi K, Hirose K, Iino M. Inositol 1,4,5-trisphosphate receptor type 2-independent Ca2+
release from the endoplasmic reticulum in astrocytes. Glia 2018; 67:113-124. [DOI: 10.1002/glia.23531] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Yohei Okubo
- Department of Pharmacology; Graduate School of Medicine, The University of Tokyo; Tokyo Japan
| | - Kazunori Kanemaru
- Department of Pharmacology; Graduate School of Medicine, The University of Tokyo; Tokyo Japan
- Department of Cellular and Molecular Pharmacology; Nihon University School of Medicine; Tokyo Japan
| | - Junji Suzuki
- Department of Physiology; University of California San Francisco; San Francisco California
| | - Kenta Kobayashi
- Section of Viral Vector Development; National Institute for Physiological Sciences; Okazaki Japan
- The Graduate University for Advanced Studies (SOKENDAI); Hayama Japan
| | - Kenzo Hirose
- Department of Neurobiology; Graduate School of Medicine, The University of Tokyo; Tokyo Japan
| | - Masamitsu Iino
- Department of Cellular and Molecular Pharmacology; Nihon University School of Medicine; Tokyo Japan
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30
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Ujita S, Sasaki T, Asada A, Funayama K, Gao M, Mikoshiba K, Matsuki N, Ikegaya Y. cAMP-Dependent Calcium Oscillations of Astrocytes: An Implication for Pathology. Cereb Cortex 2018; 27:1602-1614. [PMID: 26803165 DOI: 10.1093/cercor/bhv310] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Astrocytes in various brain regions exhibit spontaneous intracellular calcium elevations both in vitro and in vivo; however, neither the temporal pattern underlying this activity nor its function has been fully evaluated. Here, we utilized a long-term optical imaging technique to analyze the calcium activity of more than 4000 astrocytes in acute hippocampal slices as well as in the neocortex and hippocampus of head-restrained mice. Although astrocytic calcium activity was largely sparse and irregular, we observed a subset of cells in which the fluctuating calcium oscillations repeated at a regular interval of ∼30 s. These intermittent oscillations i) depended on type 2 inositol 1,4,5-trisphosphate receptors; ii) consisted of a complex reverberatory interaction between the soma and processes of individual astrocytes; iii) did not synchronize with those of other astrocytes; iv) did not require neuronal firing; v) were modulated through cAMP-protein kinase A signaling; vi) were facilitated under pathological conditions, such as energy deprivation and epileptiform hyperexcitation; and vii) were associated with enhanced hypertrophy in astrocytic processes, an early hallmark of reactive gliosis, which is observed in ischemia and epilepsy. Therefore, calcium oscillations appear to be associated with a pathological state in astrocytes.
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Affiliation(s)
- Sakiko Ujita
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Takuya Sasaki
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Akiko Asada
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Kenta Funayama
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Mengxuan Gao
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, Riken Brain Science Institute, Saitama, Japan
| | - Norio Matsuki
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.,Center for Information and Neural Networks, Suita City, Osaka, Japan
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31
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Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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32
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Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 928] [Impact Index Per Article: 154.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
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Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
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33
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Copeland CS, Wall TM, Sims RE, Neale SA, Nisenbaum E, Parri HR, Salt TE. Astrocytes modulate thalamic sensory processing via mGlu2 receptor activation. Neuropharmacology 2017; 121:100-110. [PMID: 28416443 PMCID: PMC5480778 DOI: 10.1016/j.neuropharm.2017.04.019] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 03/27/2017] [Accepted: 04/13/2017] [Indexed: 11/27/2022]
Abstract
Astrocytes possess many of the same signalling molecules as neurons. However, the role of astrocytes in information processing, if any, is unknown. Using electrophysiological and imaging methods, we report the first evidence that astrocytes modulate neuronal sensory inhibition in the rodent thalamus. We found that mGlu2 receptor activity reduces inhibitory transmission from the thalamic reticular nucleus to the somatosensory ventrobasal thalamus (VB): mIPSC frequencies in VB slices were reduced by the Group II mGlu receptor agonist LY354740, an effect potentiated by mGlu2 positive allosteric modulator (PAM) LY487379 co-application (30 nM LY354740: 10.0 ± 1.6% reduction; 30 nM LY354740 & 30 μM LY487379: 34.6 ± 5.2% reduction). We then showed activation of mGlu2 receptors on astrocytes: astrocytic intracellular calcium levels were elevated by the Group II agonist, which were further potentiated upon mGlu2 PAM co-application (300 nM LY354740: ratio amplitude 0.016 ± 0.002; 300 nM LY354740 & 30 μM LY487379: ratio amplitude 0.035 ± 0.003). We then demonstrated mGlu2-dependent astrocytic disinhibition of VB neurons in vivo: VB neuronal responses to vibrissae stimulation trains were disinhibited by the Group II agonist and the mGlu2 PAM (LY354740: 156 ± 12% of control; LY487379: 144 ± 10% of control). Presence of the glial inhibitor fluorocitrate abolished the mGlu2 PAM effect (91 ± 5% of control), suggesting the mGlu2 component to the Group II effect can be attributed to activation of mGlu2 receptors localised on astrocytic processes within the VB. Gating of thalamocortical function via astrocyte activation represents a novel sensory processing mechanism. As this thalamocortical circuitry is important in discriminative processes, this demonstrates the importance of astrocytes in synaptic processes underlying attention and cognition. Thalamic inhibition is mediated by both neuronal and astrocytic mechanisms. Group II mGlu receptor (mGlu2/3) activation can modulate this thalamic inhibition. Thalamic astrocytes can be activated upon mGlu2 receptor stimulation. This process may enable relevant activity to be discerned from background noise. Targeting astrocytic mGlu2 receptors may therefore affect attention and cognition.
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Affiliation(s)
- C S Copeland
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK; St George's, University of London, Cranmer Terrace, London, SW17 0RE, UK.
| | - T M Wall
- Eli Lilly and Company, 893 S Delaware Street, Indianapolis, IN 46285, USA.
| | - R E Sims
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK.
| | - S A Neale
- Neurexpert Limited, Kemp House, 152-160 City Road, London, EC1V 2NX, UK.
| | - E Nisenbaum
- Eli Lilly and Company, 893 S Delaware Street, Indianapolis, IN 46285, USA.
| | - H R Parri
- School of Life and Health Sciences, Aston University, Birmingham, B4 7ET, UK.
| | - T E Salt
- Institute of Ophthalmology, University College London, 11-43 Bath Street, London, EC1V 9EL, UK.
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34
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Sherwood MW, Arizono M, Hisatsune C, Bannai H, Ebisui E, Sherwood JL, Panatier A, Oliet SHR, Mikoshiba K. Astrocytic IP 3 Rs: Contribution to Ca 2+ signalling and hippocampal LTP. Glia 2017; 65:502-513. [PMID: 28063222 DOI: 10.1002/glia.23107] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 11/26/2016] [Accepted: 12/01/2016] [Indexed: 12/22/2022]
Abstract
Astrocytes regulate hippocampal synaptic plasticity by the Ca2+ dependent release of the N-methyl d-aspartate receptor (NMDAR) co-agonist d-serine. Previous evidence indicated that d-serine release would be regulated by the intracellular Ca2+ release channel IP3 receptor (IP3 R), however, genetic deletion of IP3 R2, the putative astrocytic IP3 R subtype, had no impact on synaptic plasticity or transmission. Although IP3 R2 is widely believed to be the only functional IP3 R in astrocytes, three IP3 R subtypes (1, 2, and 3) have been identified in vertebrates. Therefore, to better understand gliotransmission, we investigated the functionality of IP3 R and the contribution of the three IP3 R subtypes to Ca2+ signalling. As a proxy for gliotransmission, we found that long-term potentiation (LTP) was impaired by dialyzing astrocytes with the broad IP3 R blocker heparin, and rescued by exogenous d-serine, indicating that astrocytic IP3 Rs regulate d-serine release. To explore which IP3 R subtypes are functional in astrocytes, we used pharmacology and two-photon Ca2+ imaging of hippocampal slices from transgenic mice (IP3 R2-/- and IP3 R2-/- ;3-/- ). This approach revealed that underneath IP3 R2-mediated global Ca2+ events are an overlooked class of IP3 R-mediated local events, occurring in astroglial processes. Notably, multiple IP3 Rs were recruited by high frequency stimulation of the Schaffer collaterals, a classical LTP induction protocol. Together, these findings show the dependence of LTP and gliotransmission on Ca2+ release by astrocytic IP3 Rs. GLIA 2017;65:502-513.
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Affiliation(s)
- Mark William Sherwood
- INSERM U1215, Neurocentre Magendie, Bordeaux, 33077, France.,Université de Bordeaux, Bordeaux, 33077, France.,Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Misa Arizono
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Chihiro Hisatsune
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - Hiroko Bannai
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan.,Division of Biological Sciences, Graduate School of Science, Nagoya University, Furo-cho, Chikusa, Nagoya, 464-8602, Japan
| | - Etsuko Ebisui
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
| | - John Lawrence Sherwood
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Aude Panatier
- INSERM U1215, Neurocentre Magendie, Bordeaux, 33077, France.,Université de Bordeaux, Bordeaux, 33077, France
| | | | - Katsuhiko Mikoshiba
- Laboratory for Developmental Neurobiology, RIKEN Brain Science Institute, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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35
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Selvaraj P, Xiao L, Lee C, Murthy SRK, Cawley NX, Lane M, Merchenthaler I, Ahn S, Loh YP. Neurotrophic Factor-α1: A Key Wnt-β-Catenin Dependent Anti-Proliferation Factor and ERK-Sox9 Activated Inducer of Embryonic Neural Stem Cell Differentiation to Astrocytes in Neurodevelopment. Stem Cells 2016; 35:557-571. [PMID: 27709799 DOI: 10.1002/stem.2511] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 08/08/2016] [Accepted: 09/06/2016] [Indexed: 12/31/2022]
Abstract
Embryonic neurodevelopment involves inhibition of proliferation of multipotent neural stem cells (NSCs) followed by differentiation into neurons, astrocytes and oligodendrocytes to form the brain. We have identified a new neurotrophic factor, NF-α1, which inhibits proliferation and promotes differentiation of NSC/progenitors derived from E13.5 mouse cortex. Inhibition of proliferation of these cells was mediated through negatively regulating the Wnt pathway and decreasing β-catenin. NF-α1 induced differentiation of NSCs to astrocytes by enhancing Glial Fibrillary Acidic Protein (GFAP) expression through activating the ERK1/2-Sox9 signaling pathway. Cultured E13.5 cortical stem cells from NF-α1-knockout mice showed decreased astrocyte numbers compared to wild-type mice, which was rescued by treatment with NF-α1. In vivo, immunocytochemistry of brain sections and Western blot analysis of neocortex of mice showed a gradual increase of NF-α1 expression from E14.5 to P1 and a surge of GFAP expression at P1, the time of increase in astrogenesis. Importantly, NF-α1-Knockout mice showed ∼49% fewer GFAP positive astrocytes in the neocortex compared to WT mice at P1. Thus, NF-α1 is critical for regulating antiproliferation and cell fate determination, through differentiating embryonic stem cells to GFAP-positive astrocytes for normal neurodevelopment. Stem Cells 2017;35:557-571.
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Affiliation(s)
| | - Lan Xiao
- Section on Cellular Neurobiology, Bethesda, Maryland, USA
| | - Cheol Lee
- Unit on Developmental Neurogenetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | | | - Niamh X Cawley
- Section on Cellular Neurobiology, Bethesda, Maryland, USA
| | - Malcolm Lane
- Department of Epidemiology and Public Health and Anatomy and Neurobiology, University of Maryland, Baltimore, Maryland, USA
| | - Istvan Merchenthaler
- Department of Epidemiology and Public Health and Anatomy and Neurobiology, University of Maryland, Baltimore, Maryland, USA
| | - Sohyun Ahn
- Unit on Developmental Neurogenetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Y Peng Loh
- Section on Cellular Neurobiology, Bethesda, Maryland, USA
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36
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Bang J, Kim HY, Lee H. Optogenetic and Chemogenetic Approaches for Studying Astrocytes and Gliotransmitters. Exp Neurobiol 2016; 25:205-221. [PMID: 27790055 PMCID: PMC5081467 DOI: 10.5607/en.2016.25.5.205] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 08/19/2016] [Accepted: 08/19/2016] [Indexed: 12/20/2022] Open
Abstract
The brain consists of heterogeneous populations of neuronal and non-neuronal cells. The revelation of their connections and interactions is fundamental to understanding normal brain functions as well as abnormal changes in pathological conditions. Optogenetics and chemogenetics have been developed to allow functional manipulations both in vitro and in vivo to examine causal relationships between cellular changes and functional outcomes. These techniques are based on genetically encoded effector molecules that respond exclusively to exogenous stimuli, such as a certain wavelength of light or a synthetic ligand. Activation of effector molecules provokes diverse intracellular changes, such as an influx or efflux of ions, depolarization or hyperpolarization of membranes, and activation of intracellular signaling cascades. Optogenetics and chemogenetics have been applied mainly to the study of neuronal circuits, but their use in studying non-neuronal cells has been gradually increasing. Here we introduce recent studies that have employed optogenetics and chemogenetics to reveal the function of astrocytes and gliotransmitters.
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Affiliation(s)
- Juwon Bang
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea
| | - Hak Yeong Kim
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea
| | - Hyosang Lee
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, Korea
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37
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Mariotti L, Losi G, Sessolo M, Marcon I, Carmignoto G. The inhibitory neurotransmitter GABA evokes long-lasting Ca(2+) oscillations in cortical astrocytes. Glia 2015; 64:363-73. [PMID: 26496414 PMCID: PMC5057345 DOI: 10.1002/glia.22933] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 09/28/2015] [Indexed: 12/31/2022]
Abstract
Studies over the last decade provided evidence that in a dynamic interaction with neurons glial cell astrocytes contribut to fundamental phenomena in the brain. Most of the knowledge on this derives, however, from studies monitoring the astrocyte Ca2+ response to glutamate. Whether astrocytes can similarly respond to other neurotransmitters, including the inhibitory neurotransmitter GABA, is relatively unexplored. By using confocal and two photon laser‐scanning microscopy the astrocyte response to GABA in the mouse somatosensory and temporal cortex was studied. In slices from developing (P15‐20) and adult (P30‐60) mice, it was found that in a subpopulation of astrocytes GABA evoked somatic Ca2+ oscillations. This response was mediated by GABAB receptors and involved both Gi/o protein and inositol 1,4,5‐trisphosphate (IP3) signalling pathways. In vivo experiments from young adult mice, revealed that also cortical astrocytes in the living brain exibit GABAB receptor‐mediated Ca2+ elevations. At all astrocytic processes tested, local GABA or Baclofen brief applications induced long‐lasting Ca2+ oscillations, suggesting that all astrocytes have the potential to respond to GABA. Finally, in patch‐clamp recordings it was found that Ca2+ oscillations induced by Baclofen evoked astrocytic glutamate release and slow inward currents (SICs) in pyramidal cells from wild type but not IP3R2−/− mice, in which astrocytic GABAB receptor‐mediated Ca2+ elevations are impaired. These data suggest that cortical astrocytes in the mouse brain can sense the activity of GABAergic interneurons and through their specific recruitment contribut to the distinct role played on the cortical network by the different subsets of GABAergic interneurons. GLIA 2016;64:363–373
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Affiliation(s)
- Letizia Mariotti
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
| | - Gabriele Losi
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
| | - Michele Sessolo
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
| | - Iacopo Marcon
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
| | - Giorgio Carmignoto
- Neuroscience Institute, National Research Council (CNR) and Department of Biomedical Sciences, University of Padova, via U.Bassi 58/B, Padova, 35121, Italy
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38
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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.
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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.
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Xie AX, Petravicz J, McCarthy KD. Molecular approaches for manipulating astrocytic signaling in vivo. Front Cell Neurosci 2015; 9:144. [PMID: 25941472 PMCID: PMC4403552 DOI: 10.3389/fncel.2015.00144] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Accepted: 03/27/2015] [Indexed: 12/26/2022] Open
Abstract
Astrocytes are the predominant glial type in the central nervous system and play important roles in assisting neuronal function and network activity. Astrocytes exhibit complex signaling systems that are essential for their normal function and the homeostasis of the neural network. Altered signaling in astrocytes is closely associated with neurological and psychiatric diseases, suggesting tremendous therapeutic potential of these cells. To further understand astrocyte function in health and disease, it is important to study astrocytic signaling in vivo. In this review, we discuss molecular tools that enable the selective manipulation of astrocytic signaling, including the tools to selectively activate and inactivate astrocyte signaling in vivo. Lastly, we highlight a few tools in development that present strong potential for advancing our understanding of the role of astrocytes in physiology, behavior, and pathology.
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Affiliation(s)
- Alison X Xie
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Jeremy Petravicz
- Department of Brain and Cognitive Sciences, Picower Institute for Learning and Memory, Massachusetts Institute of Technology Cambridge, MA, USA
| | - Ken D McCarthy
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
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Petravicz J, Boyt KM, McCarthy KD. Astrocyte IP3R2-dependent Ca(2+) signaling is not a major modulator of neuronal pathways governing behavior. Front Behav Neurosci 2014; 8:384. [PMID: 25429263 PMCID: PMC4228853 DOI: 10.3389/fnbeh.2014.00384] [Citation(s) in RCA: 82] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Accepted: 10/17/2014] [Indexed: 12/22/2022] Open
Abstract
Calcium-dependent release of gliotransmitters by astrocytes is reported to play a critical role in synaptic transmission and be necessary for long-term potentiation (LTP), long-term depression (LTD) and other forms of synaptic modulation that are correlates of learning and memory. Further, physiological processes reported to be dependent on Ca2+ fluxes in astrocytes include functional hyperemia, sleep, and regulation of breathing. The preponderance of findings indicate that most, if not all, receptor dependent Ca2+ fluxes within astrocytes are due to release of Ca2+ through IP3 receptor/channels in the endoplasmic reticulum. Findings from several laboratories indicate that astrocytes only express IP3 receptor type 2 (IP3R2) and that a knockout of IP3R2 obliterates the GPCR-dependent astrocytic Ca2+ responses. Assuming that astrocytic Ca2+ fluxes play a critical role in synaptic physiology, it would be predicted that elimination of astrocytic Ca2+ fluxes would lead to marked changes in behavioral tests. Here, we tested this hypothesis by conducting a broad series of behavioral tests that recruited multiple brain regions, on an IP3R2 conditional knockout mouse model. We present the novel finding that behavioral processes are unaffected by lack of astrocyte IP3R-mediated Ca2+ signals. IP3R2 cKO animals display no change in anxiety or depressive behaviors, and no alteration to motor and sensory function. Morris water maze testing, a behavioral correlate of learning and memory, was unaffected by lack of astrocyte IP3R2-mediated Ca2+-signaling. Therefore, in contrast to the prevailing literature, we find that neither receptor-driven astrocyte Ca2+ fluxes nor, by extension, gliotransmission is likely to be a major modulating force on the physiological processes underlying behavior.
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Affiliation(s)
- Jeremy Petravicz
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Kristen M Boyt
- Department of Pharmacology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
| | - Ken D McCarthy
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; Department of Pharmacology, University of North Carolina at Chapel Hill Chapel Hill, NC, USA
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Functional MRI in mice lacking IP3-dependent calcium signaling in astrocytes. J Cereb Blood Flow Metab 2014; 34:1599-603. [PMID: 25099754 PMCID: PMC4269735 DOI: 10.1038/jcbfm.2014.144] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 07/17/2014] [Accepted: 07/18/2014] [Indexed: 11/09/2022]
Abstract
Functional magnetic resonance imaging (fMRI) is a fundamental tool to investigate human brain networks. However, the cellular mechanisms underlying fMRI signals are not fully understood. One hypothetical mechanism is the putative vascular control exerted by cytosolic calcium in perivascular astrocytes. We have performed combined fMRI-electrophysiology experiments in mice lacking the inositol 1,4,5-triphosphate-type-2 receptor, with the primary pathway of cytosolic calcium increase eliminated into astrocytes. Our results show that evoked electrophysiologic activity and fMRI signals acquired during either transient or sustained neuronal activations occur independently of these large calcium signals. This result challenges the suggested intermediary role of astrocytic calcium surges in fMRI-signal generation.
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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.
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Affiliation(s)
- Shinghua Ding
- Dalton Cardiovascular Research Center, Department of Bioengineering, University of Missouri-Columbia, 134 Research Park Drive, Columbia, MO, 65211, USA,
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43
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Cao X, Li LP, Qin XH, Li SJ, Zhang M, Wang Q, Hu HH, Fang YY, Gao YB, Li XW, Sun LR, Xiong WC, Gao TM, Zhu XH. Astrocytic adenosine 5'-triphosphate release regulates the proliferation of neural stem cells in the adult hippocampus. Stem Cells 2014; 31:1633-43. [PMID: 23630193 DOI: 10.1002/stem.1408] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Accepted: 03/27/2013] [Indexed: 12/13/2022]
Abstract
Astrocytes are key components of the niche for neural stem cells (NSCs) in the adult hippocampus and play a vital role in regulating NSC proliferation and differentiation. However, the exact molecular mechanisms by which astrocytes modulate NSC proliferation have not been identified. Here, we identified adenosine 5'-triphosphate (ATP) as a proliferative factor required for astrocyte-mediated proliferation of NSCs in the adult hippocampus. Our results indicate that ATP is necessary and sufficient for astrocytes to promote NSC proliferation in vitro. The lack of inositol 1,4,5-trisphosphate receptor type 2 and transgenic blockage of vesicular gliotransmission induced deficient ATP release from astrocytes. This deficiency led to a dysfunction in NSC proliferation that could be rescued via the administration of exogenous ATP. Moreover, P2Y1-mediated purinergic signaling is involved in the astrocyte promotion of NSC proliferation. As adult hippocampal neurogenesis is potentially involved in major mood disorder, our results might offer mechanistic insights into this disease.
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Affiliation(s)
- Xiong Cao
- Department of Neurobiology, School of Basic Medical Sciences; Key Laboratory of Neuroplasticity of Guangdong Higher Education Institutes, and; School of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China
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De Bock M, Decrock E, Wang N, Bol M, Vinken M, Bultynck G, Leybaert L. The dual face of connexin-based astroglial Ca(2+) communication: a key player in brain physiology and a prime target in pathology. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:2211-32. [PMID: 24768716 DOI: 10.1016/j.bbamcr.2014.04.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/11/2014] [Accepted: 04/12/2014] [Indexed: 12/21/2022]
Abstract
For decades, studies have been focusing on the neuronal abnormalities that accompany neurodegenerative disorders. Yet, glial cells are emerging as important players in numerous neurological diseases. Astrocytes, the main type of glia in the central nervous system , form extensive networks that physically and functionally connect neuronal synapses with cerebral blood vessels. Normal brain functioning strictly depends on highly specialized cellular cross-talk between these different partners to which Ca(2+), as a signaling ion, largely contributes. Altered intracellular Ca(2+) levels are associated with neurodegenerative disorders and play a crucial role in the glial responses to injury. Intracellular Ca(2+) increases in single astrocytes can be propagated toward neighboring cells as intercellular Ca(2+) waves, thereby recruiting a larger group of cells. Intercellular Ca(2+) wave propagation depends on two, parallel, connexin (Cx) channel-based mechanisms: i) the diffusion of inositol 1,4,5-trisphosphate through gap junction channels that directly connect the cytoplasm of neighboring cells, and ii) the release of paracrine messengers such as glutamate and ATP through hemichannels ('half of a gap junction channel'). This review gives an overview of the current knowledge on Cx-mediated Ca(2+) communication among astrocytes as well as between astrocytes and other brain cell types in physiology and pathology, with a focus on the processes of neurodegeneration and reactive gliosis. Research on Cx-mediated astroglial Ca(2+) communication may ultimately shed light on the development of targeted therapies for neurodegenerative disorders in which astrocytes participate. This article is part of a Special Issue entitled: Calcium signaling in health and disease. Guest Editors: Geert Bultynck, Jacques Haiech, Claus W. Heizmann, Joachim Krebs, and Marc Moreau.
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Affiliation(s)
- Marijke De Bock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Elke Decrock
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium.
| | - Nan Wang
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mélissa Bol
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
| | - Mathieu Vinken
- Department of Toxicology, Center for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, B-1090 Brussels, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, Laboratory of Molecular and Cellular Signalling, KULeuven, Campus Gasthuisberg O/N-I bus 802, B-3000 Leuven, Belgium
| | - Luc Leybaert
- Department of Basic Medical Sciences, Physiology group, Faculty of Medicine and Health Sciences, Ghent University, B-9000 Ghent, Belgium
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45
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Davila D, Thibault K, Fiacco TA, Agulhon C. Recent molecular approaches to understanding astrocyte function in vivo. Front Cell Neurosci 2013; 7:272. [PMID: 24399932 PMCID: PMC3871966 DOI: 10.3389/fncel.2013.00272] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Accepted: 12/06/2013] [Indexed: 12/11/2022] Open
Abstract
Astrocytes are a predominant glial cell type in the nervous systems, and are becoming recognized as important mediators of normal brain function as well as neurodevelopmental, neurological, and neurodegenerative brain diseases. Although numerous potential mechanisms have been proposed to explain the role of astrocytes in the normal and diseased brain, research into the physiological relevance of these mechanisms in vivo is just beginning. In this review, we will summarize recent developments in innovative and powerful molecular approaches, including knockout mouse models, transgenic mouse models, and astrocyte-targeted gene transfer/expression, which have led to advances in understanding astrocyte biology in vivo that were heretofore inaccessible to experimentation. We will examine the recently improved understanding of the roles of astrocytes – with an emphasis on astrocyte signaling – in the context of both the healthy and diseased brain, discuss areas where the role of astrocytes remains debated, and suggest new research directions.
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Affiliation(s)
- David Davila
- Glia-Glia and Glia-Neuron Interactions Group, National Center for Scientific Research, UFR Biomedicale, Paris Descartes University Paris, France
| | - Karine Thibault
- Glia-Glia and Glia-Neuron Interactions Group, National Center for Scientific Research, UFR Biomedicale, Paris Descartes University Paris, France
| | - Todd A Fiacco
- Department of Cell Biology and Neuroscience, and Center for Glial-Neuronal Interactions and Program in Cellular, Molecular and Developmental Biology, University of California at Riverside Riverside, CA, USA
| | - Cendra Agulhon
- Glia-Glia and Glia-Neuron Interactions Group, National Center for Scientific Research, UFR Biomedicale, Paris Descartes University Paris, France
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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.
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Affiliation(s)
- Shinghua Ding
- Dalton Cardiovascular Research Center, Department of Biological Engineering, University of Missouri, Columbia, MO 65211, USA
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47
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Calcium-dependent N-cadherin up-regulation mediates reactive astrogliosis and neuroprotection after brain injury. Proc Natl Acad Sci U S A 2013; 110:11612-7. [PMID: 23798419 DOI: 10.1073/pnas.1300378110] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Brain injury induces phenotypic changes in astrocytes, known as reactive astrogliosis, which may influence neuronal survival. Here we show that brain injury induces inositol 1,4,5-trisphosphate (IP3)-dependent Ca(2+) signaling in astrocytes, and that the Ca(2+) signaling is required for astrogliosis. We found that type 2 IP3 receptor knockout (IP3R2KO) mice deficient in astrocytic Ca(2+) signaling have impaired reactive astrogliosis and increased injury-associated neuronal death. We identified N-cadherin and pumilio 2 (Pum2) as downstream signaling molecules, and found that brain injury induces up-regulation of N-cadherin around the injured site. This effect is mediated by Ca(2+)-dependent down-regulation of Pum2, which in turn attenuates Pum2-dependent translational repression of N-cadherin. Furthermore, we show that astrocyte-specific knockout of N-cadherin results in impairment of astrogliosis and neuroprotection. Thus, astrocytic Ca(2+) signaling and the downstream function of N-cadherin play indispensable roles in the cellular responses to brain injury. These findings define a previously unreported signaling axis required for reactive astrogliosis and neuroprotection following brain injury.
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48
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Takata N, Nagai T, Ozawa K, Oe Y, Mikoshiba K, Hirase H. Cerebral blood flow modulation by Basal forebrain or whisker stimulation can occur independently of large cytosolic Ca2+ signaling in astrocytes. PLoS One 2013; 8:e66525. [PMID: 23785506 PMCID: PMC3681769 DOI: 10.1371/journal.pone.0066525] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 05/06/2013] [Indexed: 12/13/2022] Open
Abstract
We report that a brief electrical stimulation of the nucleus basalis of Meynert (NBM), the primary source of cholinergic projection to the cerebral cortex, induces a biphasic cerebral cortical blood flow (CBF) response in the somatosensory cortex of C57BL/6J mice. This CBF response, measured by laser Doppler flowmetry, was attenuated by the muscarinic type acetylcholine receptor antagonist atropine, suggesting a possible involvement of astrocytes in this type of CBF modulation. However, we find that IP3R2 knockout mice, which lack cytosolic Ca2+ surges in astrocytes, show similar CBF changes. Moreover, whisker stimulation resulted in similar degrees of CBF increase in IP3R2 knockout mice and the background strain C57BL/6J. Our results show that neural activity-driven CBF modulation could occur without large cytosolic increases of Ca2+ in astrocytes.
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Affiliation(s)
- Norio Takata
- Laboratory for Neuron-Glia Circuit, RIKEN Brain Science Institute, Wako, Saitama, Japan.
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49
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Cao X, Li LP, Wang Q, Wu Q, Hu HH, Zhang M, Fang YY, Zhang J, Li SJ, Xiong WC, Yan HC, Gao YB, Liu JH, Li XW, Sun LR, Zeng YN, Zhu XH, Gao TM. Astrocyte-derived ATP modulates depressive-like behaviors. Nat Med 2013; 19:773-7. [PMID: 23644515 DOI: 10.1038/nm.3162] [Citation(s) in RCA: 395] [Impact Index Per Article: 35.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Accepted: 03/15/2013] [Indexed: 12/15/2022]
Abstract
Major depressive disorder (MDD) is a cause of disability that affects approximately 16% of the world's population; however, little is known regarding the underlying biology of this disorder. Animal studies, postmortem brain analyses and imaging studies of patients with depression have implicated glial dysfunction in MDD pathophysiology. However, the molecular mechanisms through which astrocytes modulate depressive behaviors are largely uncharacterized. Here, we identified ATP as a key factor involved in astrocytic modulation of depressive-like behavior in adult mice. We observed low ATP abundance in the brains of mice that were susceptible to chronic social defeat. Furthermore, we found that the administration of ATP induced a rapid antidepressant-like effect in these mice. Both a lack of inositol 1,4,5-trisphosphate receptor type 2 and transgenic blockage of vesicular gliotransmission induced deficiencies in astrocytic ATP release, causing depressive-like behaviors that could be rescued via the administration of ATP. Using transgenic mice that express a Gq G protein-coupled receptor only in astrocytes to enable selective activation of astrocytic Ca(2+) signaling, we found that stimulating endogenous ATP release from astrocytes induced antidepressant-like effects in mouse models of depression. Moreover, we found that P2X2 receptors in the medial prefrontal cortex mediated the antidepressant-like effects of ATP. These results highlight astrocytic ATP release as a biological mechanism of MDD.
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Affiliation(s)
- Xiong Cao
- Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
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Baker KD, Edwards TM, Rickard NS. The role of intracellular calcium stores in synaptic plasticity and memory consolidation. Neurosci Biobehav Rev 2013; 37:1211-39. [PMID: 23639769 DOI: 10.1016/j.neubiorev.2013.04.011] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 04/18/2013] [Accepted: 04/22/2013] [Indexed: 12/20/2022]
Abstract
Memory processing requires tightly controlled signalling cascades, many of which are dependent upon intracellular calcium (Ca(2+)). Despite this, most work investigating calcium signalling in memory formation has focused on plasma membrane channels and extracellular sources of Ca(2+). The intracellular Ca(2+) release channels, ryanodine receptors (RyRs) and inositol (1,4,5)-trisphosphate receptors (IP3Rs) have a significant capacity to regulate intracellular Ca(2+) signalling. Evidence at both cellular and behavioural levels implicates both RyRs and IP3Rs in synaptic plasticity and memory formation. Pharmacobehavioural experiments using young chicks trained on a single-trial discrimination avoidance task have been particularly useful by demonstrating that RyRs and IP3Rs have distinct roles in memory formation. RyR-dependent Ca(2+) release appears to aid the consolidation of labile memory into a persistent long-term memory trace. In contrast, IP3Rs are required during long-term memory. This review discusses various functions for RyRs and IP3Rs in memory processing, including neuro- and glio-transmitter release, dendritic spine remodelling, facilitating vasodilation, and the regulation of gene transcription and dendritic excitability. Altered Ca(2+) release from intracellular stores also has significant implications for neurodegenerative conditions.
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Affiliation(s)
- Kathryn D Baker
- School of Psychology and Psychiatry, Monash University, Clayton 3800, Victoria, Australia.
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