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Pirnat S, Božić M, Dolanc D, Horvat A, Tavčar P, Vardjan N, Verkhratsky A, Zorec R, Stenovec M. Astrocyte arborization enhances Ca 2+ but not cAMP signaling plasticity. Glia 2021; 69:2899-2916. [PMID: 34406698 PMCID: PMC9290837 DOI: 10.1002/glia.24076] [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: 03/23/2021] [Revised: 08/02/2021] [Accepted: 08/06/2021] [Indexed: 01/07/2023]
Abstract
The plasticity of astrocytes is fundamental for their principal function, maintaining homeostasis of the central nervous system throughout life, and is associated with diverse exposomal challenges. Here, we used cultured astrocytes to investigate at subcellular level basic cell processes under controlled environmental conditions. We compared astroglial functional and signaling plasticity in standard serum‐containing growth medium, a condition mimicking pathologic conditions, and in medium without serum, favoring the acquisition of arborized morphology. Using opto−/electrophysiologic techniques, we examined cell viability, expression of astroglial markers, vesicle dynamics, and cytosolic Ca2+ and cAMP signaling. The results revealed altered vesicle dynamics in arborized astrocytes that was associated with increased resting [Ca2+]i and increased subcellular heterogeneity in [Ca2+]i, whereas [cAMP]i subcellular dynamics remained stable in both cultures, indicating that cAMP signaling is less prone to plastic remodeling than Ca2+ signaling, possibly also in in vivo contexts.
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Affiliation(s)
- Samo Pirnat
- Laboratory of Cell Engineering, Celica BIOMEDICAL, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Mićo Božić
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Dorian Dolanc
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Anemari Horvat
- Laboratory of Cell Engineering, Celica BIOMEDICAL, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Petra Tavčar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Cell Engineering, Celica BIOMEDICAL, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Alexei Verkhratsky
- Laboratory of Cell Engineering, Celica BIOMEDICAL, Ljubljana, Slovenia.,Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Achucarro Center for Neuroscience, IKERBASQUE, Bilbao, Spain
| | - Robert Zorec
- Laboratory of Cell Engineering, Celica BIOMEDICAL, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
| | - Matjaž Stenovec
- Laboratory of Cell Engineering, Celica BIOMEDICAL, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia
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Dopamine-induced calcium signaling in olfactory bulb astrocytes. Sci Rep 2020; 10:631. [PMID: 31959788 PMCID: PMC6971274 DOI: 10.1038/s41598-020-57462-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/30/2019] [Indexed: 11/08/2022] Open
Abstract
It is well established that astrocytes respond to the major neurotransmitters glutamate and GABA with cytosolic calcium rises, whereas less is known about the effect of dopamine on astroglial cells. In the present study, we used confocal calcium imaging in mouse brain slices of the olfactory bulb, a brain region with a large population of dopaminergic neurons, to investigate calcium signaling evoked by dopamine in astrocytes. Our results show that application of dopamine leads to a dose-dependent cytosolic calcium rise in astrocytes (EC50 = 76 µM) which is independent of neuronal activity and mainly mediated by PLC/IP3-dependent internal calcium release. Antagonists of both D1- and D2-class dopamine receptors partly reduce the dopaminergic calcium response, indicating that both receptor classes contribute to dopamine-induced calcium transients in olfactory bulb astrocytes.
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Meng G, Li C, Sun H, Lee I. Multiple calcium patterns of rat osteoblasts under fluidic shear stress. J Orthop Res 2018; 36:2039-2051. [PMID: 29266507 DOI: 10.1002/jor.23843] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 12/14/2017] [Indexed: 02/04/2023]
Abstract
The intracellular calcium ([Ca2+ ]i ) response induced by external forces can be diverse and complex. Using primary osteoblasts from Wistar rats, we found multiple patterns of [Ca2+ ]i responses induced by fluidic shear stress (Fss), including homogeneous non-oscillation and heterogeneous oscillations. These multiple-patterned [Ca2+ ]i responses could be influenced by Fss intensity, cell density, and cell differentiation. Our real-time measurements with free calcium, ATP, ATP without calcium, suramin, apyrase, and thapsigargin confirmed homogeneous [Ca2+ ]i patterns and/or heterogeneous [Ca2+ ]i oscillations with respect to the combined degree of external Ca2+ influx, and intracellular Ca2+ release. Our theoretical model supported diverse Fss-induced calcium activities as well. We concluded that a singular factor of Ca2+ influx or release dominated to produce smooth homogeneous patterns, but combined factors produced oscillatory heterogeneous patterns. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:2039-2051, 2018.
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Affiliation(s)
- Guixian Meng
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin, China.,Academy of Laboratory, Jilin Medical University, Jilin, China
| | - Cunbo Li
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin, China
| | - Haiying Sun
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin, China
| | - Imshik Lee
- The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin, China
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Vergouts M, Doyen PJ, Peeters M, Opsomer R, Hermans E. Constitutive downregulation protein kinase C epsilon in hSOD1 G93A astrocytes influences mGluR5 signaling and the regulation of glutamate uptake. Glia 2017; 66:749-761. [PMID: 29266405 DOI: 10.1002/glia.23279] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 11/19/2017] [Accepted: 11/24/2017] [Indexed: 01/06/2023]
Abstract
Accumulating evidence indicates that motor neuron degeneration in amyotrophic lateral sclerosis (ALS) is a non-cell-autonomous process and that impaired glutamate clearance by astrocytes, leading to excitotoxicity, could participate in progression of the disease. In astrocytes derived from an animal model of ALS (hSOD1G93A rats), activation of type 5 metabotropic glutamate receptor (mGluR5) fails to increase glutamate uptake, impeding a putative dynamic neuroprotective mechanism involving astrocytes. Using astrocyte cultures from hSOD1G93A rats, we have demonstrated that the typical Ca2+ oscillations associated with mGluR5 activation were reduced, and that the majority of cells responded with a sustained elevation of intracellular Ca2+ concentration. Since the expression of protein kinase C epsilon isoform (PKCɛ) has been found to be considerably reduced in astrocytes from hSOD1G93A rats, the consequences of manipulating its activity and expression on mGluR5 signaling and on the regulation of glutamate uptake have been examined. Increasing PKCɛ expression was found to restore Ca2+ oscillations induced by mGluR5 activation in hSOD1G93A -expressing astrocytes. This was also associated with an increase in glutamate uptake capacity in response to mGluR5 activation. Conversely, reducing PKCɛ expression in astrocytes from wild-type animals with specific PKCɛ-shRNAs was found to alter the mGluR5 associated oscillatory signaling profile, and consistently reduced the regulation of the glutamate uptake-mediated by mGluR5 activation. These results suggest that PKCɛ is required to generate Ca2+ oscillations following mGluR5 activation, which support the regulation of astrocytic glutamate uptake. Reduced expression of astrocytic PKCɛ could impair this neuroprotective process and participate in the progression of ALS.
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Affiliation(s)
- Maxime Vergouts
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, 1200, Belgium
| | - Pierre J Doyen
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, 1200, Belgium
| | - Michael Peeters
- De Duve Institute, Université catholique de Louvain, Avenue Hippocrate VIRO B1.74.07, Brussels, 1200, Belgium
| | - Remi Opsomer
- Alzheimer Dementia Group, Institute of Neuroscience, Université catholique de Louvain, Avenue Mounier B1.53.02, Brussels, 1200, Belgium
| | - Emmanuel Hermans
- Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, 1200, Belgium
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Modulation of Dendritic Cell Apoptosis and CD8 + Cytotoxicity by Histamine: Role of Protein Kinase C. Mediators Inflamm 2017; 2017:9402814. [PMID: 28947859 PMCID: PMC5602510 DOI: 10.1155/2017/9402814] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 06/26/2017] [Accepted: 07/18/2017] [Indexed: 11/18/2022] Open
Abstract
Dendritic cells (DC) are able to present extracellular antigens associated with the molecules of the major histocompatibility complex class I. In a previous work, we demonstrated that the histamine (HIS), acting through H1/H4 receptors, increases the cross-presentation of soluble ovalbumin by murine DC and can enhance the recruitment of specific CD8+ T lymphocytes during the development of chronic inflammatory responses. Here, we studied in more depth the mechanisms underlying this enhancement. We showed that the cytotoxicity of specific CD8+ lymphocytes is increased in HIS-treated DC and it is lost by inhibition of vacuolar-ATPase that prevents endosome acidification. It is known that HIS acts through G protein-coupled receptors. The H1/H4 receptors are associated with a Gq subunit, which involves PKC signaling, a pathway related to the apoptotic process. Interestingly, we demonstrated for the first time that HIS prevents DC apoptosis induced by heat shock through the inhibition of caspase-3, a mechanism dependent on PKC activation, since it is reversed by its inhibition. By contrast, cytolytic activity of T lymphocytes induced by HIS-stimulated DC was independent of PKC pathway.
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Vergouts M, Doyen PJ, Peeters M, Opsomer R, Michiels T, Hermans E. PKC epsilon-dependent calcium oscillations associated with metabotropic glutamate receptor 5 prevent agonist-mediated receptor desensitization in astrocytes. J Neurochem 2017; 141:387-399. [PMID: 28266711 DOI: 10.1111/jnc.14007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 01/26/2017] [Accepted: 02/20/2017] [Indexed: 12/16/2022]
Abstract
A critical role has been assigned to protein kinase C (PKC)ε in the control of intracellular calcium oscillations triggered upon activation of type 5 metabotropic glutamate receptor (mGluR5) in cultured astrocytes. Nevertheless, the physiological significance of this particular signalling profile in the response of astrocytes to glutamate remains largely unknown. Considering that kinases are frequently involved in the regulation of G protein-coupled receptors, we have examined a putative link between the nature of the calcium signals and the response regulation upon repeated exposures of astrocytes to the agonist (S)-3,5-dihydroxyphenylglycine. We show that upon repeated mGluR5 activations, a robust desensitization was observed in astrocytes grown in culture conditions favouring the peak-plateau-type response. At variance, in cell cultures where calcium oscillations were predominating, the response was fully preserved even during repeated challenges with the agonist. Pharmacological inhibition of PKCε or genetic suppression of this isoform using shRNA was found to convert an oscillatory calcium profile to a sustained calcium mobilization and this latter profile was subject to desensitization upon repetitive mGluR5 activation. Our results suggest a yet undocumented scheme in which the activity of PKCε contributes to preserve the receptor sensitivity upon repeated or sustained activations. Cover Image for this issue: doi: 10.1111/jnc.13797.
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Affiliation(s)
- Maxime Vergouts
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, Belgium
| | - Pierre J Doyen
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, Belgium
| | - Michael Peeters
- Laboratory of virology, De Duve Institute, Université catholique de Louvain, Avenue Hippocrate B1.74.07, Brussels, Belgium
| | - Remi Opsomer
- Alzheimer Dementia Group, Institute of Neuroscience, Université catholique de Louvain, Avenue Mounier B1.53.02, Brussels, Belgium
| | - Thomas Michiels
- Laboratory of virology, De Duve Institute, Université catholique de Louvain, Avenue Hippocrate B1.74.07, Brussels, Belgium
| | - Emmanuel Hermans
- Group of Neuropharmacology, Institute of Neuroscience, Université catholique de Louvain, Avenue Hippocrate B1.54.10, Brussels, Belgium
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Hertz L, Chen Y. Importance of astrocytes for potassium ion (K+) homeostasis in brain and glial effects of K+ and its transporters on learning. Neurosci Biobehav Rev 2016; 71:484-505. [DOI: 10.1016/j.neubiorev.2016.09.018] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 08/12/2016] [Accepted: 09/23/2016] [Indexed: 10/20/2022]
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