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Srivastava T, Nguyen H, Haden G, Diba P, Sowa S, LaNguyen N, Reed-Dustin W, Zhu W, Gong X, Harris EN, Baltan S, Back SA. TSG-6-Mediated Extracellular Matrix Modifications Regulate Hypoxic-Ischemic Brain Injury. J Neurosci 2024; 44:e2215232024. [PMID: 38569926 PMCID: PMC11112645 DOI: 10.1523/jneurosci.2215-23.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 03/24/2024] [Accepted: 03/27/2024] [Indexed: 04/05/2024] Open
Abstract
Proteoglycans containing link domains modify the extracellular matrix (ECM) to regulate cellular homeostasis and can also sensitize tissues/organs to injury and stress. Hypoxic-ischemic (H-I) injury disrupts cellular homeostasis by activating inflammation and attenuating regeneration and repair pathways. In the brain, the main component of the ECM is the glycosaminoglycan hyaluronic acid (HA), but whether HA modifications of the ECM regulate cellular homeostasis and response to H-I injury is not known. In this report, employing both male and female mice, we demonstrate that link-domain-containing proteoglycan, TNFα-stimulated gene-6 (TSG-6), is active in the brain from birth onward and differentially modifies ECM HA during discrete neurodevelopmental windows. ECM HA modification by TSG-6 enables it to serve as a developmental switch to regulate the activity of the Hippo pathway effector protein, yes-associated protein 1 (YAP1), in the maturing brain and in response to H-I injury. Mice that lack TSG-6 expression display dysregulated expression of YAP1 targets, excitatory amino acid transporter 1 (EAAT1; glutamate-aspartate transporter) and 2 (EAAT2; glutamate transporter-1). Dysregulation of YAP1 activation in TSG-6-/- mice coincides with age- and sex-dependent sensitization of the brain to H-I injury such that 1-week-old neonates display an anti-inflammatory response in contrast to an enhanced proinflammatory injury reaction in 3-month-old adult males but not females. Our findings thus support that a key regulator of age- and sex-dependent H-I injury response in the mouse brain is modulation of the Hippo-YAP1 pathway by TSG-6-dependent ECM modifications.
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Affiliation(s)
- Taasin Srivastava
- Department of Pediatrics, Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Hung Nguyen
- Division of Anesthesiology and Perioperative Medicine (APOM), Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Gage Haden
- Department of Pediatrics, Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Parham Diba
- Department of Pediatrics, Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Steven Sowa
- Department of Pediatrics, Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Norah LaNguyen
- Department of Pediatrics, Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - William Reed-Dustin
- Department of Pediatrics, Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Wenbin Zhu
- Division of Anesthesiology and Perioperative Medicine (APOM), Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Xi Gong
- Department of Pediatrics, Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Edward N Harris
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, Nebraska 68588
| | - Selva Baltan
- Division of Anesthesiology and Perioperative Medicine (APOM), Oregon Health and Science University (OHSU), Portland, Oregon 97239
| | - Stephen A Back
- Department of Pediatrics, Oregon Health and Science University (OHSU), Portland, Oregon 97239
- Department of Neurology, Oregon Health and Science University (OHSU), Portland, Oregon 97239
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Asghari K, Niknam Z, Mohammadpour-Asl S, Chodari L. Cellular junction dynamics and Alzheimer's disease: a comprehensive review. Mol Biol Rep 2024; 51:273. [PMID: 38302794 DOI: 10.1007/s11033-024-09242-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Accepted: 01/11/2024] [Indexed: 02/03/2024]
Abstract
Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by progressive neuronal damage and cognitive decline. Recent studies have shed light on the involvement of not only the blood-brain barrier (BBB) dysfunction but also significant alterations in cellular junctions in AD pathogenesis. In this review article, we explore the role of the BBB and cellular junctions in AD pathology, with a specific focus on the hippocampus. The BBB acts as a crucial protective barrier between the bloodstream and the brain, maintaining brain homeostasis and regulating molecular transport. Preservation of BBB integrity relies on various junctions, including gap junctions formed by connexins, tight junctions composed of proteins such as claudins, occludin, and ZO-1, as well as adherence junctions involving molecules like vascular endothelial (VE) cadherin, Nectins, and Nectin-like molecules (Necls). Abnormalities in these junctions and junctional components contribute to impaired neuronal signaling and increased cerebrovascular permeability, which are closely associated with AD advancement. By elucidating the underlying molecular mechanisms governing BBB and cellular junction dysfunctions within the context of AD, this review offers valuable insights into the pathogenesis of AD and identifies potential therapeutic targets for intervention.
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Affiliation(s)
- Keyvan Asghari
- Student Research Committee, Urmia University of Medical Sciences, Urmia, Iran
| | - Zahra Niknam
- Neurophysiology Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran
| | - Shadi Mohammadpour-Asl
- Student Research Committee, Urmia University of Medical Sciences, Urmia, Iran
- Department of Physiology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran
| | - Leila Chodari
- Neurophysiology Research Center, Cellular and Molecular Medicine Research Institute, Urmia University of Medical Sciences, Urmia, Iran.
- Department of Physiology, School of Medicine, Urmia University of Medical Sciences, Urmia, Iran.
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Zhong S, Kiyoshi CM, Du Y, Wang W, Luo Y, Wu X, Taylor AT, Ma B, Aten S, Liu X, Zhou M. Genesis of a functional astrocyte syncytium in the developing mouse hippocampus. Glia 2023; 71:1081-1098. [PMID: 36598109 PMCID: PMC10777263 DOI: 10.1002/glia.24327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Revised: 12/03/2022] [Accepted: 12/15/2022] [Indexed: 01/05/2023]
Abstract
Astrocytes are increasingly shown to operate as an isopotential syncytium in brain function. Protoplasmic astrocytes acquire this ability to functionally go beyond the single-cell level by evolving into a spongiform morphology, cytoplasmically connecting into a syncytium, and expressing a high density of K+ conductance. However, none of these cellular/functional features exist in neonatal newborn astrocytes, which imposes a basic question of when a functional syncytium evolves in the developing brain. Our results show that the spongiform morphology of individual astrocytes and their spatial organization all reach stationary levels by postnatal day (P) 15 in the hippocampal CA1 region. Functionally, astrocytes begin to uniformly express a mature level of passive K+ conductance by P11. We next used syncytial isopotentiality measurement to monitor the maturation of the astrocyte syncytium. In uncoupled P1 astrocytes, the substitution of endogenous K+ by a Na+ -electrode solution ([Na+ ]p ) resulted in the total elimination of the physiological membrane potential (VM ), and outward K+ conductance as predicted by the Goldman-Hodgkin-Katz (GHK) equation. As more astrocytes are coupled to each other through gap junctions during development, the [Na+ ]p -induced loss of physiological VM and the outward K+ conductance is progressively compensated by the neighboring astrocytes. By P15, a stably established syncytial isopotentiality (-73 mV), and a fully compensated outward K+ conductance appeared in all [Na+ ]p -recorded astrocytes. Thus, in view of the developmental timeframe wherein a singular syncytium is anatomically and functionally established for intra-syncytium K+ equilibration, an astrocyte syncytium becomes fully operational at P15 in the mouse hippocampus.
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Affiliation(s)
- Shiying Zhong
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Department of Neurology, Shanghai 10Hospital of Tongji University, School of Medicine, Shanghai, 200072, China
| | - Conrad M. Kiyoshi
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Yixing Du
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Wei Wang
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
- Department of Physiology, Tongji Medical College, Wuhan, 430030, China
| | - Yumeng Luo
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Xiao Wu
- Department of Neurology, Wuhan First Hospital, Wuhan 430022, China
| | - Anne T. Taylor
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Baofeng Ma
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Sydney Aten
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Xueyuan Liu
- Department of Neurology, Shanghai 10Hospital of Tongji University, School of Medicine, Shanghai, 200072, China
| | - Min Zhou
- Department of Neuroscience, Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
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Regulatory role of endoplasmic reticulum resident chaperone protein ERp29 in anti-murine β-coronavirus host cell response. J Biol Chem 2022; 299:102836. [PMID: 36572185 PMCID: PMC9788854 DOI: 10.1016/j.jbc.2022.102836] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 11/30/2022] [Accepted: 12/03/2022] [Indexed: 12/25/2022] Open
Abstract
Gap junctional intercellular communication (GJIC) involving astrocytes is important for proper CNS homeostasis. As determined in our previous studies, trafficking of the predominant astrocyte GJ protein, Connexin43 (Cx43), is disrupted in response to infection with a neurotropic murine β-coronavirus (MHV-A59). However, how host factors are involved in Cx43 trafficking and the infection response is not clear. Here, we show that Cx43 retention due to MHV-A59 infection was associated with increased ER stress and reduced expression of chaperone protein ERp29. Treatment of MHV-A59-infected astrocytes with the chemical chaperone 4-sodium phenylbutyrate increased ERp29 expression, rescued Cx43 transport to the cell surface, increased GJIC, and reduced ER stress. We obtained similar results using an astrocytoma cell line (delayed brain tumor) upon MHV-A59 infection. Critically, delayed brain tumor cells transfected to express exogenous ERp29 were less susceptible to MHV-A59 infection and showed increased Cx43-mediated GJIC. Treatment with Cx43 mimetic peptides inhibited GJIC and increased viral susceptibility, demonstrating a role for intercellular communication in reducing MHV-A59 infectivity. Taken together, these results support a therapeutically targetable ERp29-dependent mechanism where β-coronavirus infectivity is modulated by reducing ER stress and rescuing Cx43 trafficking and function.
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Connexin 30 Deficiency Ameliorates Disease Progression at the Early Phase in a Mouse Model of Amyotrophic Lateral Sclerosis by Suppressing Glial Inflammation. Int J Mol Sci 2022; 23:ijms232416046. [PMID: 36555685 PMCID: PMC9782489 DOI: 10.3390/ijms232416046] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Connexin 30 (Cx30), which forms gap junctions between astrocytes, regulates cell adhesion and migration, and modulates glutamate transport. Cx30 is upregulated on activated astroglia in central nervous system inflammatory lesions, including spinal cord lesions in mutant superoxide dismutase 1 (mSOD1) transgenic amyotrophic lateral sclerosis (ALS) model mice. Here, we investigated the role of Cx30 in mSOD1 mice. Cx30 was highly expressed in the pre-onset stage in mSOD1 mice. mSOD1 mice with knockout (KO) of the Cx30 gene (Cx30KO-mSOD1 mice) showed delayed disease onset and tended to have an extended survival period (log-rank, p = 0.09). At the progressive and end stages of the disease, anterior horn cells were significantly preserved in Cx30KO-mSOD1 mice. In lesions of these mice, glial fibrillary acidic protein/C3-positive inflammatory astroglia were decreased. Additionally, the activation of astrocytes in Cx30KO-mSOD1 mice was reduced compared with mSOD1 mice by gene expression microarray. Furthermore, expression of connexin 43 at the pre-onset stage was downregulated in Cx30KO-mSOD1 mice. These findings suggest that reduced expression of astroglial Cx30 at the early disease stage in ALS model mice protects neurons by attenuating astroglial inflammation.
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Yang Z, Gong M, Jian T, Li J, Yang C, Ma Q, Deng P, Wang Y, Huang M, Wang H, Yang S, Chen X, Yu Z, Wang M, Chen C, Zhang K. Engrafted glial progenitor cells yield long-term integration and sensory improvement in aged mice. Stem Cell Res Ther 2022; 13:285. [PMID: 35765112 PMCID: PMC9241208 DOI: 10.1186/s13287-022-02959-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 06/05/2022] [Indexed: 12/31/2022] Open
Abstract
Aging causes astrocyte morphological degeneration and functional deficiency, which impairs neuronal functions. Until now, whether age-induced neuronal deficiency could be alleviated by engraftment of glial progenitor cell (GPC) derived astrocytes remained unknown. In the current study, GPCs were generated from embryonic cortical neural stem cells in vitro and transplanted into the brains of aged mice. Their integration and intervention effects in the aged brain were examined 12 months after transplantation. Results indicated that these in-vitro-generated GPC-derived astrocytes possessed normal functional properties. After transplantation they could migrate, differentiate, achieve long-term integration, and maintain much younger morphology in the aged brain. Additionally, these GPC-derived astrocytes established endfeet expressing aquaporin-4 (AQP4) and ameliorate AQP4 polarization in the aged neocortex. More importantly, age-dependent sensory response degeneration was reversed by GPC transplantation. This work demonstrates that rejuvenation of the astrocyte niche is a promising treatment to prevent age-induced degradation of neuronal and behavioral functions.
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Affiliation(s)
- Zhiqi Yang
- Department of Neurology, Lanzhou University Second Hospital, Cuiyingmen 82, Chengguan District, Lanzhou, 730030, Gansu, China.,Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Mingyue Gong
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Tingliang Jian
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Jin Li
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Chuanyan Yang
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Qinlong Ma
- Department of Occupational Health, Third Military Medical University, Chongqing, 400038, China
| | - Ping Deng
- Department of Occupational Health, Third Military Medical University, Chongqing, 400038, China
| | - Yuxia Wang
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Mingzhu Huang
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Haoyu Wang
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Shaofan Yang
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Xiaowei Chen
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China
| | - Zhengping Yu
- Department of Occupational Health, Third Military Medical University, Chongqing, 400038, China
| | - Manxia Wang
- Department of Neurology, Lanzhou University Second Hospital, Cuiyingmen 82, Chengguan District, Lanzhou, 730030, Gansu, China.
| | - Chunhai Chen
- Department of Occupational Health, Third Military Medical University, Chongqing, 400038, China.
| | - Kuan Zhang
- Brain Research Center and State Key Laboratory of Trauma, Burns, and Combined Injury, Third Military Medical University, Chongqing, 400038, China.
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7
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Köse B, Özkan M, Sur-Erdem İ, Çavdar S. Does astrocyte gap junction protein expression level differ during development in the absence epileptic rats? Synapse 2022; 76:e22225. [PMID: 35137459 DOI: 10.1002/syn.22225] [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: 11/17/2021] [Revised: 01/05/2022] [Accepted: 01/27/2022] [Indexed: 11/09/2022]
Abstract
Intercellular communication via gap junctions (GJ) has a wide variety of complex and essential functions in the CNS. In the present developmental study, we aimed to quantify the number of astrocytic GJ protein connexin 30 (Cx30) of genetic absence epilepsy rats from Strasbourg (GAERS) at postnatal P10, P30, and P60 days in the epileptic focal areas involved in the cortico-thalamic circuit. We compared the results with Wistar rats using immunohistochemistry and Western Blotting. The number of Cx30 immunopositive astrocytes in per unit area were quantified for the somatosensory cortex (SSCx), ventrobasal (VB), and lateral geniculate (LGN) of the two strains and Cx30 Western Blot was applied to the tissue samples from the same regions. Both immunohistochemical and Western Blot results revealed the presence of Cx30 in all regions studied at P10 in both Wistar and GAERS animals. The SSCx, VB, and LGN of Wistar animals showed progressive increase in the number of Cx30 immunopositive labelled astrocytes from P10 to P30 and reached a peak at P30; then a significant decline was observed from P30 to P60 for the SSCx and VB. However, in GAERS Cx30 immunopositive labelled astrocytes showed a progressive increase from P10 to P60 for all brain regions studied. The immunohistochemical data highly corresponded with Western Blotting results. We conclude that the developmental disproportional expression of Cx30 in the epileptic focal areas in GAERS may be related to the onset of absence seizures or may be related to the neurogenesis of absence epilepsy. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Büşra Köse
- Department of Anatomy, Koç University School of Medicine, Istanbul, Turkey
| | - Mazhar Özkan
- Department of Anatomy, Tekirdağ Namık Kemal University School of Medicine, Istanbul, Turkey
| | - İlknur Sur-Erdem
- Department of Molecular Biology, Koç University School of Medicine, Istanbul, Turkey
| | - Safiye Çavdar
- Department of Anatomy, Koç University School of Medicine, Istanbul, Turkey
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Velloso FJ, Shankar S, Parpura V, Rakic P, Levison SW. Neural Stem Cells in Adult Mammals are not Astrocytes. ASN Neuro 2022; 14:17590914221134739. [PMID: 36330653 PMCID: PMC9638700 DOI: 10.1177/17590914221134739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/27/2022] [Accepted: 10/01/2022] [Indexed: 11/06/2022] Open
Abstract
At the turn of the 21st century studies of the cells that resided in the adult mammalian subventricular zone (SVZ) characterized the neural stem cells (NSCs) as a subtype of astrocyte. Over the ensuing years, numerous studies have further characterized the properties of these NSCs and compared them to parenchymal astrocytes. Here we have evaluated the evidence collected to date to establish whether classifying the NSCs as astrocytes is appropriate and useful. We also performed a meta-analysis with 4 previously published datasets that used cell sorting and unbiased single-cell RNAseq to highlight the distinct gene expression profiles of adult murine NSCs and niche astrocytes. On the basis of our understanding of the properties and functions of astrocytes versus the properties and functions of NSCs, and from our comparative transcriptomic analyses we conclude that classifying the adult mammalian NSC as an astrocyte is potentially misleading. From our vantage point, it is more appropriate to refer to the cells in the adult mammalian SVZ that retain the capacity to produce new neurons and macroglia as NSCs without attaching the term "astrocyte-like."
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Affiliation(s)
- Fernando Janczur Velloso
- Department of Pharmacology, Physiology & Neuroscience, New
Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Sandhya Shankar
- Department of Pharmacology, Physiology & Neuroscience, New
Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham,
Birmingham, AL, USA
| | - Pasko Rakic
- Department of Neuroscience, Yale School of Medicine, New Haven, CT,
USA
- Kavli Institute for Neuroscience, Yale School of Medicine, New
Haven, CT, USA
| | - Steven W. Levison
- Department of Pharmacology, Physiology & Neuroscience, New
Jersey Medical School, Rutgers University, Newark, NJ, USA
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Cibelli A, Stout R, Timmermann A, de Menezes L, Guo P, Maass K, Seifert G, Steinhäuser C, Spray DC, Scemes E. Cx43 carboxyl terminal domain determines AQP4 and Cx30 endfoot organization and blood brain barrier permeability. Sci Rep 2021; 11:24334. [PMID: 34934080 PMCID: PMC8692511 DOI: 10.1038/s41598-021-03694-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 12/06/2021] [Indexed: 11/08/2022] Open
Abstract
The neurovascular unit (NVU) consists of cells intrinsic to the vessel wall, the endothelial cells and pericytes, and astrocyte endfeet that surround the vessel but are separated from it by basement membrane. Endothelial cells are primarily responsible for creating and maintaining blood-brain-barrier (BBB) tightness, but astrocytes contribute to the barrier through paracrine signaling to the endothelial cells and by forming the glia limitans. Gap junctions (GJs) between astrocyte endfeet are composed of connexin 43 (Cx43) and Cx30, which form plaques between cells. GJ plaques formed of Cx43 do not diffuse laterally in the plasma membrane and thus potentially provide stable organizational features to the endfoot domain, whereas GJ plaques formed of other connexins and of Cx43 lacking a large portion of its cytoplasmic carboxyl terminus are quite mobile. In order to examine the organizational features that immobile GJs impose on the endfoot, we have used super-resolution confocal microscopy to map number and sizes of GJ plaques and aquaporin (AQP)-4 channel clusters in the perivascular endfeet of mice in which astrocyte GJs (Cx30, Cx43) were deleted or the carboxyl terminus of Cx43 was truncated. To determine if BBB integrity was compromised in these transgenic mice, we conducted perfusion studies under elevated hydrostatic pressure using horseradish peroxide as a molecular probe enabling detection of micro-hemorrhages in brain sections. These studies revealed that microhemorrhages were more numerous in mice lacking Cx43 or its carboxyl terminus. In perivascular domains of cerebral vessels, we found that density of Cx43 GJs was higher in the truncation mutant, while GJ size was smaller. Density of perivascular particles formed by AQP4 and its extended isoform AQP4ex was inversely related to the presence of full length Cx43, whereas the ratio of sizes of the particles of the AQP4ex isoform to total AQP4 was directly related to the presence of full length Cx43. Confocal analysis showed that Cx43 and Cx30 were substantially colocalized in astrocyte domains near vasculature of truncation mutant mice. These results showing altered distribution of some astrocyte nexus components (AQP4 and Cx30) in Cx43 null mice and in a truncation mutant, together with leakier cerebral vasculature, support the hypothesis that localization and mobility of gap junction proteins and their binding partners influences organization of astrocyte endfeet which in turn impacts BBB integrity of the NVU.
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Affiliation(s)
- Antonio Cibelli
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
| | - Randy Stout
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY, USA
| | - Aline Timmermann
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Laura de Menezes
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Insitute of Biophysics, Federal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil
| | - Peng Guo
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA
- Cellular Imaging Core Facility, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Karen Maass
- Cardiovascular Research Center, NYU Grossman School of Medicine, New York, NY, USA
| | - Gerald Seifert
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Bonn, Germany
| | - David C Spray
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA.
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - Eliana Scemes
- Department of Anatomy and Cell Biology, New York Medical College, Valhalla, NY, 10595, USA.
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10
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Montana V, Flint D, Waagepetersen HS, Schousboe A, Parpura V. Two Metabolic Fuels, Glucose and Lactate, Differentially Modulate Exocytotic Glutamate Release from Cultured Astrocytes. Neurochem Res 2021; 46:2551-2579. [PMID: 34057673 PMCID: PMC9015689 DOI: 10.1007/s11064-021-03340-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 05/06/2021] [Accepted: 05/10/2021] [Indexed: 12/26/2022]
Abstract
Astrocytes have a prominent role in metabolic homeostasis of the brain and can signal to adjacent neurons by releasing glutamate via a process of regulated exocytosis. Astrocytes synthesize glutamate de novo owing to the pyruvate entry to the citric/tricarboxylic acid cycle via pyruvate carboxylase, an astrocyte specific enzyme. Pyruvate can be sourced from two metabolic fuels, glucose and lactate. Thus, we investigated the role of these energy/carbon sources in exocytotic glutamate release from astrocytes. Purified astrocyte cultures were acutely incubated (1 h) in glucose and/or lactate-containing media. Astrocytes were mechanically stimulated, a procedure known to increase intracellular Ca2+ levels and cause exocytotic glutamate release, the dynamics of which were monitored using single cell fluorescence microscopy. Our data indicate that glucose, either taken-up from the extracellular space or mobilized from the intracellular glycogen storage, sustained glutamate release, while the availability of lactate significantly reduced the release of glutamate from astrocytes. Based on further pharmacological manipulation during imaging along with tandem mass spectrometry (proteomics) analysis, lactate alone, but not in the hybrid fuel, caused metabolic changes consistent with an increased synthesis of fatty acids. Proteomics analysis further unveiled complex changes in protein profiles, which were condition-dependent and generally included changes in levels of cytoskeletal proteins, proteins of secretory organelle/vesicle traffic and recycling at the plasma membrane in aglycemic, lactate or hybrid-fueled astrocytes. These findings support the notion that the availability of energy sources and metabolic milieu play a significant role in gliotransmission.
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Affiliation(s)
- Vedrana Montana
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
| | - Daniel Flint
- Luxumbra Strategic Research, LLC, Arlington, VA, USA
| | - Helle S Waagepetersen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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11
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Kirichenko EY, Skatchkov SN, Ermakov AM. Structure and Functions of Gap Junctions and Their Constituent Connexins in the Mammalian CNS. BIOCHEMISTRY MOSCOW SUPPLEMENT SERIES A-MEMBRANE AND CELL BIOLOGY 2021; 15:107-119. [PMID: 34512926 PMCID: PMC8432592 DOI: 10.1134/s1990747821020069] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Numerous data obtained in the last 20 years indicate that all parts of the mature central nervous system, from the retina and olfactory bulb to the spinal cord and brain, contain cells connected by gap junctions (GJs). The morphological basis of the GJs is a group of joined membrane hemichannels called connexons, the subunit of each connexon is the protein connexin. In the central nervous system, connexins show specificity and certain types of them are expressed either in neurons or in glial cells. Connexins and GJs of neurons, combining certain types of inhibitory hippocampal and neocortical neuronal ensembles, provide synchronization of local impulse and rhythmic activity, thalamocortical conduction, control of excitatory connections, which reflects their important role in the processes of perception, concentration of attention and consolidation of memory, both on the cellular and at the system level. Connexins of glial cells are ubiquitously expressed in the brain, and the GJs formed by them provide molecular signaling and metabolic cooperation and play a certain role in the processes of neuronal migration during brain development, myelination, tissue homeostasis, and apoptosis. At the same time, mutations in the genes of glial connexins, as well as a deficiency of these proteins, are associated with such diseases as congenital neuropathies, hearing loss, skin diseases, and brain tumors. This review summarizes the existing data of numerous molecular, electrophysiological, pharmacological, and morphological studies aimed at progress in the study of the physiological and pathophysiological significance of glial and neuronal connexins and GJs for the central nervous system.
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Affiliation(s)
- E Yu Kirichenko
- Academy of Biology and Biotechnology, Southern Federal University, Rostov-on-Don, 344090 Russia
| | - S N Skatchkov
- Department of Biochemistry, School of Medicine, P.O. Box 60327, Universidad Central del Caribe, Bayamón, PR, 00960-6032 USA.,Department of Physiology, School of Medicine, P.O. Box 60327, Universidad Central del Caribe, Bayamón, PR, 00960-6032 USA
| | - A M Ermakov
- Faculty of Bioengineering and Veterinary Medicine, Don State Technical University, Rostov-on-Don, 344003 Russia
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12
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Ribot J, Breton R, Calvo CF, Moulard J, Ezan P, Zapata J, Samama K, Moreau M, Bemelmans AP, Sabatet V, Dingli F, Loew D, Milleret C, Billuart P, Dallérac G, Rouach N. Astrocytes close the mouse critical period for visual plasticity. Science 2021; 373:77-81. [PMID: 34210880 DOI: 10.1126/science.abf5273] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Accepted: 05/13/2021] [Indexed: 12/26/2022]
Abstract
Brain postnatal development is characterized by critical periods of experience-dependent remodeling of neuronal circuits. Failure to end these periods results in neurodevelopmental disorders. The cellular processes defining critical-period timing remain unclear. Here, we show that in the mouse visual cortex, astrocytes control critical-period closure. We uncover the underlying pathway, which involves astrocytic regulation of the extracellular matrix, allowing interneuron maturation. Unconventional astrocyte connexin signaling hinders expression of extracellular matrix-degrading enzyme matrix metalloproteinase 9 (MMP9) through RhoA-guanosine triphosphatase activation. Thus, astrocytes not only influence the activity of single synapses but also are key elements in the experience-dependent wiring of brain circuits.
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Affiliation(s)
- Jérôme Ribot
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Rachel Breton
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.,Doctoral School N°568, Paris Saclay University, PSL Research University, Le Kremlin Bicetre, France.,Université Paris-Saclay, CNRS, Institut des neurosciences Paris-Saclay, Gif-sur-Yvette, France
| | - Charles-Félix Calvo
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Julien Moulard
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.,Doctoral School N°158, Sorbonne University, Paris, France
| | - Pascal Ezan
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Jonathan Zapata
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Kevin Samama
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Matthieu Moreau
- Université de Paris, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Genetic and Development of Cerebral Cortex Laboratory, GHU Paris Psychiatrie et Neurosciences, Hôpital Saint Anne, Paris, France
| | - Alexis-Pierre Bemelmans
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale, Institut de biologie François Jacob, MIRCen, and CNRS UMR 9199, Université Paris-Saclay, Neurodegenerative Diseases Laboratory, Fontenay-aux-Roses, France
| | - Valentin Sabatet
- Institut Curie, PSL Research University, Mass Spectrometry and Proteomics Laboratory, Paris, France
| | - Florent Dingli
- Institut Curie, PSL Research University, Mass Spectrometry and Proteomics Laboratory, Paris, France
| | - Damarys Loew
- Institut Curie, PSL Research University, Mass Spectrometry and Proteomics Laboratory, Paris, France
| | - Chantal Milleret
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Pierre Billuart
- Université de Paris, Institute of Psychiatry and Neuroscience of Paris (IPNP), INSERM U1266, Genetic and Development of Cerebral Cortex Laboratory, GHU Paris Psychiatrie et Neurosciences, Hôpital Saint Anne, Paris, France
| | - Glenn Dallérac
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.
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13
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Cibelli A, Veronica Lopez-Quintero S, Mccutcheon S, Scemes E, Spray DC, Stout RF, Suadicani SO, Thi MM, Urban-Maldonado M. Generation and Characterization of Immortalized Mouse Cortical Astrocytes From Wildtype and Connexin43 Knockout Mice. Front Cell Neurosci 2021; 15:647109. [PMID: 33790744 PMCID: PMC8005635 DOI: 10.3389/fncel.2021.647109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 02/18/2021] [Indexed: 11/17/2022] Open
Abstract
We transduced mouse cortical astrocytes cultured from four litters of embryonic wildtype (WT) and connexin43 (Cx43) null mouse pups with lentiviral vector encoding hTERT and measured expression of astrocyte-specific markers up to passage 10 (p10). The immortalized cell lines thus generated (designated IWCA and IKOCA, respectively) expressed biomarkers consistent with those of neonatal astrocytes, including Cx43 from wildtype but not from Cx43-null mice, lack of Cx30, and presence of Cx26. AQP4, the water channel that is found in high abundance in astrocyte end-feet, was expressed at moderately high levels in early passages, and its mRNA and protein declined to low but still detectable levels by p10. The mRNA levels of the astrocyte biomarkers aldehyde dehydrogenase 1L1 (ALDH1L1), glutamine synthetase (GS) and glial fibrillary acidic protein (GFAP) remained relatively constant during successive passages. GS protein expression was maintained while GFAP declined with cell passaging but was still detectable at p10. Both mRNA and protein levels of glutamate transporter 1 (GLT-1) declined with passage number. Immunostaining at corresponding times was consistent with the data from Western blots and provided evidence that these proteins were expressed at appropriate intracellular locations. Consistent with our goal of generating immortalized cell lines in which Cx43 was either functionally expressed or absent, IWCA cells were found to be well coupled with respect to intercellular dye transfer and similar to primary astrocyte cultures in terms of time course of junction formation, electrical coupling strength and voltage sensitivity. Moreover, barrier function was enhanced in co-culture of the IWCA cell line with bEnd.3 microvascular endothelial cells. In addition, immunostaining revealed oblate endogenous Cx43 gap junction plaques in IWCA that were similar in appearance to those plaques obtained following transfection of IKOCA cells with fluorescent protein tagged Cx43. Re-expression of Cx43 in IKOCA cells allows experimental manipulation of connexins and live imaging of interactions between connexins and other proteins. We conclude that properties of these cell lines resemble those of primary cultured astrocytes, and they may provide useful tools in functional studies by facilitating genetic and pharmacological manipulations in the context of an astrocyte-appropriate cellular environment.
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Affiliation(s)
- Antonio Cibelli
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
| | | | - Sean Mccutcheon
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
| | - Eliana Scemes
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
| | - David C. Spray
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States,Department of Medicine (Cardiology), Albert Einstein College of Medicine, New York, NY, United States,*Correspondence: David C. Spray,
| | - Randy F. Stout
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States,Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, New York, NY, United States,Randy J. Stout Jr.,
| | - Sylvia O. Suadicani
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States,Department of Urology, Albert Einstein College of Medicine, New York, NY, United States,Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY, United States
| | - Mia M. Thi
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States,Department of Molecular Pharmacology, Albert Einstein College of Medicine, New York, NY, United States,Department of Orthopaedic Surgery, Albert Einstein College of Medicine, New York, NY, United States
| | - Marcia Urban-Maldonado
- Department of Urology, Albert Einstein College of Medicine, New York, NY, United States,Department of Orthopaedic Surgery, Albert Einstein College of Medicine, New York, NY, United States
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14
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Stephan J, Eitelmann S, Zhou M. Approaches to Study Gap Junctional Coupling. Front Cell Neurosci 2021; 15:640406. [PMID: 33776652 PMCID: PMC7987795 DOI: 10.3389/fncel.2021.640406] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 02/03/2021] [Indexed: 12/17/2022] Open
Abstract
Astrocytes and oligodendrocytes are main players in the brain to ensure ion and neurotransmitter homeostasis, metabolic supply, and fast action potential propagation in axons. These functions are fostered by the formation of large syncytia in which mainly astrocytes and oligodendrocytes are directly coupled. Panglial networks constitute on connexin-based gap junctions in the membranes of neighboring cells that allow the passage of ions, metabolites, and currents. However, these networks are not uniform but exhibit a brain region-dependent heterogeneous connectivity influencing electrical communication and intercellular ion spread. Here, we describe different approaches to analyze gap junctional communication in acute tissue slices that can be implemented easily in most electrophysiology and imaging laboratories. These approaches include paired recordings, determination of syncytial isopotentiality, tracer coupling followed by analysis of network topography, and wide field imaging of ion sensitive dyes. These approaches are capable to reveal cellular heterogeneity causing electrical isolation of functional circuits, reduced ion-transfer between different cell types, and anisotropy of tracer coupling. With a selective or combinatory use of these methods, the results will shed light on cellular properties of glial cells and their contribution to neuronal function.
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Affiliation(s)
- Jonathan Stephan
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sara Eitelmann
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Min Zhou
- Department of Neuroscience, Wexner Medical Center, Ohio State University, Columbus, OH, United States
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15
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Charvériat M, Mouthon F, Rein W, Verkhratsky A. Connexins as therapeutic targets in neurological and neuropsychiatric disorders. Biochim Biophys Acta Mol Basis Dis 2021; 1867:166098. [PMID: 33545299 DOI: 10.1016/j.bbadis.2021.166098] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Revised: 01/06/2021] [Accepted: 01/19/2021] [Indexed: 12/16/2022]
Abstract
Astrocytes represent the reticular part of the central nervous system; gap junctions formed by connexins Cx43, Cx30- and Cx26 provide for homocellular astrocyte-astrocyte coupling, whereas connexins Cx30, Cx32, Cx43, and Cx47 connect astrocytes and oligodendrocytes. Astroglial networks are anatomically and functionally segregated being homologous to neuronal ensembles. Connexons, gap junctions and hemichannels (unpaired connexons) are affected in various neuropathologies from neuropsychiatric to neurodegenerative diseases. Manipulation of astrocytic connexins modulates the size and outreach of astroglial syncytia thus affecting astroglial homeostatic support. Modulation of astrocytic connexin significantly modifies pharmacological profile of many CNS drugs, which represents an innovative therapeutic approach for CNS disorders; this approach is now actively tested in pre-clinical and clinical studies. Wide combination of connexin modulators with CNS drugs open new promising perspectives for fundamental studies and therapeutic strategies.
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Affiliation(s)
| | | | | | - A Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK; Achucarro Centre for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
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16
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Novielli-Kuntz NM, Press ER, Barr K, Prado MAM, Laird DW. Mutant Cx30-A88V mice exhibit hydrocephaly and sex-dependent behavioral abnormalities, implicating a functional role for Cx30 in the brain. Dis Model Mech 2021; 14:14/1/dmm046235. [PMID: 33735099 PMCID: PMC7859702 DOI: 10.1242/dmm.046235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 12/03/2020] [Indexed: 01/01/2023] Open
Abstract
Connexin 30 (Cx30; also known as Gjb6 when referring to the mouse gene) is expressed in ependymal cells of the brain ventricles, in leptomeningeal cells and in astrocytes rich in connexin 43 (Cx43), leading us to question whether patients harboring GJB6 mutations exhibit any brain anomalies. Here, we used mice harboring the human disease-associated A88V Cx30 mutation to address this gap in knowledge. Brain Cx30 levels were lower in male and female Cx30A88V/A88V mice compared with Cx30A88V/+ and Cx30+/+ mice, whereas Cx43 levels were lower only in female Cx30 mutant mice. Characterization of brain morphology revealed a disrupted ependymal cell layer, significant hydrocephalus and enlarged ventricles in 3- to 6-month-old adult male and female Cx30A88V/A88V mice compared with Cx30A88V/+ or Cx30+/+ sex-matched littermate mice. To determine the functional significance of these molecular and morphological changes, we investigated a number of behavioral activities in these mice. Interestingly, only female Cx30A88V/A88V mice exhibited abnormal behavior compared with all other groups. Cx30A88V/A88V female mice demonstrated increased locomotor and exploratory activity in both the open field and the elevated plus maze. They also exhibited dramatically reduced ability to learn the location of the escape platform during Morris water maze training, although they were able to swim as well as other genotypes. Our findings suggest that the homozygous A88V mutation in Cx30 causes major morphological changes in the brain of aging mice, possibly attributable to an abnormal ependymal cell layer. Remarkably, these changes had a more pronounced consequence for cognitive function in female mice, which is likely to be linked to the dysregulation of both Cx30 and Cx43 levels in the brain.
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Affiliation(s)
- Nicole M Novielli-Kuntz
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON, Canada N6A 5C1
| | - Eric R Press
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON, Canada N6A 5C1.,Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada N6A 5C1
| | - Kevin Barr
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON, Canada N6A 5C1
| | - Marco A M Prado
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON, Canada N6A 5C1.,Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada N6A 5C1.,Robarts Research Institute, The University of Western Ontario, London, ON, Canada N6A 5K8
| | - Dale W Laird
- Department of Anatomy and Cell Biology, The University of Western Ontario, London, ON, Canada N6A 5C1 .,Department of Physiology and Pharmacology, The University of Western Ontario, London, ON, Canada N6A 5C1
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17
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Altered Gap Junction Network Topography in Mouse Models for Human Hereditary Deafness. Int J Mol Sci 2020; 21:ijms21197376. [PMID: 33036242 PMCID: PMC7582522 DOI: 10.3390/ijms21197376] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/01/2020] [Accepted: 10/02/2020] [Indexed: 12/19/2022] Open
Abstract
Anisotropic gap junctional coupling is a distinct feature of astrocytes in many brain regions. In the lateral superior olive (LSO), astrocytic networks are anisotropic and oriented orthogonally to the tonotopic axis. In CaV1.3 knock-out (KO) and otoferlin KO mice, where auditory brainstem nuclei are deprived from spontaneous cochlea-driven neuronal activity, neuronal circuitry is disturbed. So far it was unknown if this disturbance is also accompanied by an impaired topography of LSO astrocyte networks. To answer this question, we immunohistochemically analyzed the expression of astrocytic connexin (Cx) 43 and Cx30 in auditory brainstem nuclei. Furthermore, we loaded LSO astrocytes with the gap junction-permeable tracer neurobiotin and assessed the network shape and orientation. We found a strong elevation of Cx30 immunoreactivity in the LSO of CaV1.3 KO mice, while Cx43 levels were only slightly increased. In otoferlin KO mice, LSO showed a slight increase in Cx43 as well, whereas Cx30 levels were unchanged. The total number of tracer-coupled cells was unaltered and most networks were anisotropic in both KO strains. In contrast to the WTs, however, LSO networks were predominantly oriented parallel to the tonotopic axis and not orthogonal to it. Taken together, our data demonstrate that spontaneous cochlea-driven neuronal activity is not required per se for the formation of anisotropic LSO astrocyte networks. However, neuronal activity is required to establish the proper orientation of networks. Proper formation of LSO astrocyte networks thus necessitates neuronal input from the periphery, indicating a critical role of neuron-glia interaction during early postnatal development in the auditory brainstem.
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18
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Fumagalli A, Heuninck J, Pizzoccaro A, Moutin E, Koenen J, Séveno M, Durroux T, Junier MP, Schlecht-Louf G, Bachelerie F, Schütz D, Stumm R, Smit MJ, Guérineau NC, Chaumont-Dubel S, Marin P. The atypical chemokine receptor 3 interacts with Connexin 43 inhibiting astrocytic gap junctional intercellular communication. Nat Commun 2020; 11:4855. [PMID: 32978390 PMCID: PMC7519114 DOI: 10.1038/s41467-020-18634-y] [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: 05/31/2019] [Accepted: 09/02/2020] [Indexed: 12/12/2022] Open
Abstract
The atypical chemokine receptor 3 (ACKR3) plays a pivotal role in directing the migration of various cellular populations and its over-expression in tumors promotes cell proliferation and invasiveness. The intracellular signaling pathways transducing ACKR3-dependent effects remain poorly characterized, an issue we addressed by identifying the interactome of ACKR3. Here, we report that recombinant ACKR3 expressed in HEK293T cells recruits the gap junction protein Connexin 43 (Cx43). Cx43 and ACKR3 are co-expressed in mouse brain astrocytes and human glioblastoma cells and form a complex in embryonic mouse brain. Functional in vitro studies show enhanced ACKR3 interaction with Cx43 upon ACKR3 agonist stimulation. Furthermore, ACKR3 activation promotes β-arrestin2- and dynamin-dependent Cx43 internalization to inhibit gap junctional intercellular communication in primary astrocytes. These results demonstrate a functional link between ACKR3 and gap junctions that might be of pathophysiological relevance. The atypical chemokine receptor 3 (ACKR3) is known to regulate cell migration, but the underlying mechanisms are unclear. Here, the authors show, from an interactome analysis, ACKR3 association with the gap junction protein Connexin 43 in vivo and ACKR3-mediated inhibition of astrocyte gap junctional communication.
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Affiliation(s)
- Amos Fumagalli
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Joyce Heuninck
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Anne Pizzoccaro
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Enora Moutin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Joyce Koenen
- Université Paris-Saclay, Inserm, Inflammation, Microbiome and Immunosurveillance, 92140, Clamart, France.,Amsterdam Institute for Molecules Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, 1081, HV, Amsterdam, The Netherlands
| | - Martial Séveno
- Biocampus Montpellier, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Thierry Durroux
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Marie-Pierre Junier
- CNRS UMR8246, Inserm U1130, Neuroscience Paris Seine-IBPS, Sorbonne Universités, Paris, France
| | - Géraldine Schlecht-Louf
- Université Paris-Saclay, Inserm, Inflammation, Microbiome and Immunosurveillance, 92140, Clamart, France
| | - Francoise Bachelerie
- Université Paris-Saclay, Inserm, Inflammation, Microbiome and Immunosurveillance, 92140, Clamart, France
| | - Dagmar Schütz
- Institute of Pharmacology and Toxicology, Jena University Hospital, 07747, Jena, Germany
| | - Ralf Stumm
- Institute of Pharmacology and Toxicology, Jena University Hospital, 07747, Jena, Germany
| | - Martine J Smit
- Amsterdam Institute for Molecules Medicines and Systems, Division of Medicinal Chemistry, Faculty of Sciences, VU University Amsterdam, 1081, HV, Amsterdam, The Netherlands
| | - Nathalie C Guérineau
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Séverine Chaumont-Dubel
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France
| | - Philippe Marin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, Montpellier, France.
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19
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Ghézali G, Vasile F, Curry N, Fantham M, Cheung G, Ezan P, Cohen-Salmon M, Kaminski C, Rouach N. Neuronal Activity Drives Astroglial Connexin 30 in Perisynaptic Processes and Shapes Its Functions. Cereb Cortex 2020; 30:753-766. [PMID: 31271200 PMCID: PMC7086174 DOI: 10.1093/cercor/bhz123] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 04/22/2019] [Accepted: 05/17/2019] [Indexed: 12/17/2022] Open
Abstract
Astrocytes play key roles in brain functions through dynamic interactions with neurons. One of their typical features is to express high levels of connexins (Cxs), Cx43 and Cx30, the gap junction (GJ)-forming proteins. Cx30 is involved in basic cognitive processes and shapes synaptic and network activities, as shown by recent studies in transgenic animals. Yet it remains unknown whether astroglial Cx30 expression, localization, and functions are endogenously and dynamically regulated by neuronal activity and could therefore play physiological roles in neurotransmission. We here show that neuronal activity increased hippocampal Cx30 protein levels via a posttranslational mechanism regulating lysosomal degradation. Neuronal activity also increased Cx30 protein levels at membranes and perisynaptic processes, as revealed by superresolution imaging. This translated at the functional level in the activation of Cx30 hemichannels and in Cx30-mediated remodeling of astrocyte morphology independently of GJ biochemical coupling. Altogether, these data show activity-dependent dynamics of Cx30 expression, perisynaptic localization, and functions.
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Affiliation(s)
- Grégory Ghézali
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
- Doctoral School N° 158, Pierre and Marie Curie University, 75006 Paris, France
| | - Flora Vasile
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
- Doctoral School N°474, Rene Descartes University, 75006 Paris, France
| | - Nathan Curry
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Marcus Fantham
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Giselle Cheung
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Pascal Ezan
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Martine Cohen-Salmon
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Clemens Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
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20
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Connexin Signaling Is Involved in the Reactivation of a Latent Stem Cell Niche after Spinal Cord Injury. J Neurosci 2020; 40:2246-2258. [PMID: 32001613 DOI: 10.1523/jneurosci.2056-19.2020] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Revised: 01/20/2020] [Accepted: 01/23/2020] [Indexed: 12/26/2022] Open
Abstract
The ependyma of the adult spinal cord is a latent stem cell niche that is reactivated by spinal cord injury contributing new cells to the glial scar. The cellular events taking place in the early stages of the reaction of the ependyma to injury remain little understood. Ependymal cells are functionally heterogeneous with a mitotically active subpopulation lining the lateral domains of the central canal (CC) that are coupled via gap junctions. Gap junctions and connexin hemichannels are key regulators of the biology of neural progenitors during development and in adult neurogenic niches. Thus, we hypothesized that communication via connexins in the CC is developmentally regulated and may play a part in the reactivation of this latent stem cell niche after injury. To test these possibilities, we combined patch-clamp recordings of ependymal cells with immunohistochemistry for various connexins in the neonatal and the adult (P > 90) normal and injured spinal cord of male and female mice. We find that coupling among ependymal cells is downregulated as postnatal development proceeds but increases after injury, resembling the immature CC. The increase in gap junction coupling in the adult CC was paralleled by upregulation of connexin 26, which correlated with the resumption of proliferation and a reduction of connexin hemichannel activity. Connexin blockade reduced the injury-induced proliferation of ependymal cells. Our findings suggest that connexins are involved in the early reaction of ependymal cells to injury, representing a potential target to improve the contribution of the CC stem cell niche to repair.SIGNIFICANCE STATEMENT Ependymal cells in the adult spinal cord are latent progenitors that react to injury to support some degree of endogenous repair. Understanding the mechanisms by which these progenitor-like cells are regulated in the aftermath of spinal cord injury is critical to design future manipulations aimed at improving healing and functional recovery. Gap junctions and connexin hemichannels are key regulators of the biology of neural progenitors during development and in adult neurogenic niches. We find here that connexin signaling in the ependyma changes after injury of the adult spinal cord, functionally resembling the immature active-stem cell niche of neonatal animals. Our findings suggest that connexins in ependymal cells are potential targets to improve self-repair of the spinal cord.
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Heterogeneity of Astrocytes in Grey and White Matter. Neurochem Res 2019; 46:3-14. [PMID: 31797158 DOI: 10.1007/s11064-019-02926-x] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 11/21/2019] [Accepted: 11/28/2019] [Indexed: 02/07/2023]
Abstract
Astrocytes are a diverse and heterogeneous type of glial cells. The major task of grey and white matter areas in the brain are computation of information at neuronal synapses and propagation of action potentials along axons, respectively, resulting in diverse demands for astrocytes. Adapting their function to the requirements in the local environment, astrocytes differ in morphology, gene expression, metabolism, and many other properties. Here we review the differential properties of protoplasmic astrocytes of grey matter and fibrous astrocytes located in white matter in respect to glutamate and energy metabolism, to their function at the blood-brain interface and to coupling via gap junctions. Finally, we discuss how this astrocytic heterogeneity might contribute to the different susceptibility of grey and white matter to ischemic insults.
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22
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Evidence of decreased gap junction coupling between astrocytes and oligodendrocytes in the anterior cingulate cortex of depressed suicides. Neuropsychopharmacology 2019; 44:2099-2111. [PMID: 31374562 PMCID: PMC6897926 DOI: 10.1038/s41386-019-0471-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 07/23/2019] [Accepted: 07/26/2019] [Indexed: 12/13/2022]
Abstract
Glial dysfunction is a major pathophysiological feature of mood disorders. While altered astrocyte (AS) and oligodendrocyte-lineage (OL) functions have been associated with depression, the crosstalk between these glial cell types has never been assessed in that context. AS are potent regulators of myelination, in part through gap junction (GJ) channels formed by the heterotypic coupling of AS-specific (Cx30 and Cx43) and OL-specific (Cx32 and Cx47) connexins. This study therefore aimed at addressing the integrity of AS/OL coupling in the anterior cingulate cortex (ACC) of depressed suicides. Using immunofluorescence and confocal imaging, we characterized the distribution of Cx30 and mapped its expression onto OL somas, myelinated axons, and brain vasculature in postmortem brain samples from depressed suicides (N = 48) and matched controls (N = 23). Differential gene expression of key components of the GJ nexus was also screened through RNA-sequencing previously generated by our group, and validated by quantitative real-time PCR. We show that Cx30 expression localized onto OL cells and myelinated fibers is decreased in deep cortical layers of the ACC in male-depressed suicides. This effect was associated with decreased expression of OL-specific connexins, as well as the downregulation of major connexin-interacting proteins essential for the scaffolding, trafficking, and function of GJs. These results provide a first evidence of impaired AS/OL GJ-mediated communication in the ACC of individuals with mood disorders. These changes in glial coupling are likely to have significant impact on brain function, and may contribute to the altered OL function previously reported in this brain region.
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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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Dallérac G, Zapata J, Rouach N. Versatile control of synaptic circuits by astrocytes: where, when and how? Nat Rev Neurosci 2019; 19:729-743. [PMID: 30401802 DOI: 10.1038/s41583-018-0080-6] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Close structural and functional interactions of astrocytes with synapses play an important role in brain function. The repertoire of ways in which astrocytes can regulate synaptic transmission is complex so that they can both promote and dampen synaptic efficacy. Such contrasting effects raise questions regarding the determinants of these divergent astroglial functions. Recent findings provide insights into where, when and how astroglial regulation of synapses takes place by revealing major molecular and functional intrinsic heterogeneity as well as switches in astrocytes occurring during development or specific patterns of neuronal activity. Astrocytes may therefore be seen as boosters or gatekeepers of synaptic circuits depending on their intrinsic and transformative properties throughout life.
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Affiliation(s)
- Glenn Dallérac
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Jonathan Zapata
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris, France.
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25
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Xin W, Mironova YA, Shen H, Marino RAM, Waisman A, Lamers WH, Bergles DE, Bonci A. Oligodendrocytes Support Neuronal Glutamatergic Transmission via Expression of Glutamine Synthetase. Cell Rep 2019; 27:2262-2271.e5. [PMID: 31116973 PMCID: PMC6544175 DOI: 10.1016/j.celrep.2019.04.094] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 01/16/2019] [Accepted: 04/22/2019] [Indexed: 11/30/2022] Open
Abstract
Glutamate has been implicated in a wide range of brain pathologies and is thought to be metabolized via the astrocyte-specific enzyme glutamine synthetase (GS). We show here that oligodendrocytes, the myelinating glia of the central nervous system, also express high levels of GS in caudal regions like the midbrain and the spinal cord. Selective removal of oligodendrocyte GS in mice led to reduced brain glutamate and glutamine levels and impaired glutamatergic synaptic transmission without disrupting myelination. Furthermore, animals lacking oligodendrocyte GS displayed deficits in cocaine-induced locomotor sensitization, a behavior that is dependent on glutamatergic signaling in the midbrain. Thus, oligodendrocytes support glutamatergic transmission through the actions of GS and may represent a therapeutic target for pathological conditions related to brain glutamate dysregulation.
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Affiliation(s)
- Wendy Xin
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | - Yevgeniya A Mironova
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Hui Shen
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA
| | - Rosa A M Marino
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA
| | - Ari Waisman
- Institute for Molecular Medicine, University Medical Center of the Johannes Gutenberg University, 55128 Mainz, Germany
| | - Wouter H Lamers
- Academic Medical Center, Tytgat Institute for Liver and Intestinal Research, 1105 BK Amsterdam, the Netherlands
| | - Dwight E Bergles
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Antonello Bonci
- Intramural Research Program, National Institute on Drug Abuse, NIH, Baltimore, MD 21224, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Neuroscience, Georgetown University Medical Center, School of Medicine, Washington, DC 20007, USA; Department of Psychiatry, University of Maryland, School of Medicine, Baltimore, MD 21205, USA.
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26
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Giaume C, Sáez JC, Song W, Leybaert L, Naus CC. Connexins and pannexins in Alzheimer’s disease. Neurosci Lett 2019; 695:100-105. [DOI: 10.1016/j.neulet.2017.09.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Revised: 08/14/2017] [Accepted: 09/01/2017] [Indexed: 12/22/2022]
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27
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Semyanov A. Spatiotemporal pattern of calcium activity in astrocytic network. Cell Calcium 2019; 78:15-25. [DOI: 10.1016/j.ceca.2018.12.007] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 12/16/2018] [Accepted: 12/16/2018] [Indexed: 12/22/2022]
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Abstract
The gap junctions (GJs), which form intercellular communicating channels between two apposing cells or form hemichannel with extracellular environment, perform crucial functions to maintain small molecule homeostasis. The central nervous system (CNS) GJs are important for maintenance of myelin sheath and neuronal activity. Connexin (Cx) proteins are building blocks of GJs. Recent cell-biological investigations show that amongst the CNS specific Cxs, the most abundant Cx protein, Cx43 and its oligodendrocytic coupling partner Cx47 primarily important for maintenance of CNS myelin. Recent investigations elucidate that the expression of Cx43 and Cx47 is very important to maintain K+ buffering and nutrient homeostasis in oligodendrocytes, CNS myelin and oligodendrocyte function. The investigations on Multiple Sclerosis (MS) patient samples and EAE hypothesized that the functional loss of Cx43/Cx47 could be associated with spread of chronic MS lesions. Exploring the mechanism of initial GJ alteration and its effect on demyelination in this model of MS might play a primary role to understand the basis of altered CNS homeostasis, observed during MS. In this review, we mainly discuss the role of CNS GJs, specifically the Cx43/Cx47 axis in the perspective of demyelination.
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29
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Basu R, Sarma JDAS. Connexin 43/47 channels are important for astrocyte/ oligodendrocyte cross-talk in myelination and demyelination. J Biosci 2018; 43:1055-1068. [PMID: 30541963] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/28/2022]
Abstract
The gap junctions (GJs), which form intercellular communicating channels between two apposing cells or form hemichannel with extracellular environment, perform crucial functions to maintain small molecule homeostasis. The central nervous system (CNS) GJs are important for maintenance of myelin sheath and neuronal activity. Connexin (Cx) proteins are building blocks of GJs. Recent cell-biological investigations show that amongst the CNS specific Cxs, the most abundant Cx protein, Cx43 and its oligodendrocytic coupling partner Cx47 primarily important for maintenance of CNS myelin. Recent investigations elucidate that the expression of Cx43 and Cx47 is very important to maintain K? buffering and nutrient homeostasis in oligodendrocytes, CNS myelin and oligodendrocyte function. The investigations on Multiple Sclerosis (MS) patient samples and EAE hypothesized that the functional loss of Cx43/Cx47 could be associated with spread of chronic MS lesions. Exploring the mechanism of initial GJ alteration and its effect on demyelination in this model of MS might play a primary role to understand the basis of altered CNS homeostasis, observed during MS. In this review, we mainly discuss the role of CNS GJs, specifically the Cx43/Cx47 axis in the perspective of demyelination.
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Affiliation(s)
- Rahul Basu
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, India
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30
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Abudara V, Retamal MA, Del Rio R, Orellana JA. Synaptic Functions of Hemichannels and Pannexons: A Double-Edged Sword. Front Mol Neurosci 2018; 11:435. [PMID: 30564096 PMCID: PMC6288452 DOI: 10.3389/fnmol.2018.00435] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/08/2018] [Indexed: 01/18/2023] Open
Abstract
The classical view of synapses as the functional contact between presynaptic and postsynaptic neurons has been challenged in recent years by the emerging regulatory role of glial cells. Astrocytes, traditionally considered merely supportive elements are now recognized as active modulators of synaptic transmission and plasticity at the now so-called "tripartite synapse." In addition, an increasing body of evidence indicates that beyond immune functions microglia also participate in various processes aimed to shape synaptic plasticity. Release of neuroactive compounds of glial origin, -process known as gliotransmission-, constitute a widespread mechanism through which glial cells can either potentiate or reduce the synaptic strength. The prevailing vision states that gliotransmission depends on an intracellular Ca2+/exocytotic-mediated release; notwithstanding, growing evidence is pointing at hemichannels (connexons) and pannexin channels (pannexons) as alternative non-vesicular routes for gliotransmitters efflux. In concurrence with this novel concept, both hemichannels and pannexons are known to mediate the transfer of ions and signaling molecules -such as ATP and glutamate- between the cytoplasm and the extracellular milieu. Importantly, recent reports show that glial hemichannels and pannexons are capable to perceive synaptic activity and to respond to it through changes in their functional state. In this article, we will review the current information supporting the "double edge sword" role of hemichannels and pannexons in the function of central and peripheral synapses. At one end, available data support the idea that these channels are chief components of a feedback control mechanism through which gliotransmitters adjust the synaptic gain in either resting or stimulated conditions. At the other end, we will discuss how the excitotoxic release of gliotransmitters and [Ca2+]i overload linked to the opening of hemichannels/pannexons might impact cell function and survival in the nervous system.
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Affiliation(s)
- Verónica Abudara
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile.,Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, United States.,Programa de Comunicación Celular en Cáncer, Instituto de Ciencias e Innovación en Medicina, Santiago, Chile
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Departamento de Fisiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Envejecimiento y Regeneración, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina and Centro Interdisciplinario de Neurociencias, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
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31
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Mederos S, González-Arias C, Perea G. Astrocyte-Neuron Networks: A Multilane Highway of Signaling for Homeostatic Brain Function. Front Synaptic Neurosci 2018; 10:45. [PMID: 30542276 PMCID: PMC6277918 DOI: 10.3389/fnsyn.2018.00045] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 11/12/2018] [Indexed: 12/22/2022] Open
Abstract
Research on glial cells over the past 30 years has confirmed the critical role of astrocytes in pathophysiological brain states. However, most of our knowledge about astrocyte physiology and of the interactions between astrocytes and neurons is based on the premises that astrocytes constitute a homogeneous cell type, without considering the particular properties of the circuits or brain nuclei in which the astrocytes are located. Therefore, we argue that more-sophisticated experiments are required to elucidate the specific features of astrocytes in different brain regions, and even within different layers of a particular circuit. Thus, in addition to considering the diverse mechanisms used by astrocytes to communicate with neurons and synaptic partners, it is necessary to take into account the cellular heterogeneity that likely contributes to the outcomes of astrocyte-neuron signaling. In this review article, we briefly summarize the current data regarding the anatomical, molecular and functional properties of astrocyte-neuron communication, as well as the heterogeneity within this communication.
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Affiliation(s)
- Sara Mederos
- Department of Functional and Systems Neurobiology, Instituto Cajal (IC), CSIC, Madrid, Spain
| | - Candela González-Arias
- Department of Functional and Systems Neurobiology, Instituto Cajal (IC), CSIC, Madrid, Spain
| | - Gertrudis Perea
- Department of Functional and Systems Neurobiology, Instituto Cajal (IC), CSIC, Madrid, Spain
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32
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Recabal A, Elizondo-Vega R, Philippot C, Salgado M, López S, Palma A, Tarifeño-Saldivia E, Timmermann A, Seifert G, Caprile T, Steinhäuser C, García-Robles MA. Connexin-43 Gap Junctions Are Responsible for the Hypothalamic Tanycyte-Coupled Network. Front Cell Neurosci 2018; 12:406. [PMID: 30534054 PMCID: PMC6275304 DOI: 10.3389/fncel.2018.00406] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 10/19/2018] [Indexed: 12/21/2022] Open
Abstract
Tanycytes are hypothalamic radial glia-like cells that form the basal wall of the third ventricle (3V) where they sense glucose and modulate neighboring neuronal activity to control feeding behavior. This role requires the coupling of hypothalamic cells since transient decreased hypothalamic Cx43 expression inhibits the increase of brain glucose-induced insulin secretion. Tanycytes have been postulated as possible hypothalamic neuronal precursors due to their privileged position in the hypothalamus that allows them to detect mitogenic signals and because they share the markers and characteristics of neuronal precursors located in other neurogenic niches, including the formation of coupled networks through connexins. Using wild-type (WT), Cx30−/– and Cx30−/–, Cx43fl/fl:glial fibrillary acidic protein (GFAP)-Cre (double knockout, dKO) mouse lines, we demonstrated that tanycytes are highly coupled to each other and also give rise to a panglial network specifically through Cx43. Using the human GFAP (hGFAP)-enhanced green fluorescent protein (EGFP) transgenic mouse line, we provided evidence that the main parenchymal-coupled cells were astrocytes. In addition, electrophysiological parameters, such as membrane resistance, were altered when Cx43 was genetically absent or pharmacologically inhibited. Finally, in the dKO mouse line, we detected a significant decrease in the number of hypothalamic proliferative parenchymal cells. Our results demonstrate the importance of Cx43 in tanycyte homotypic and panglial coupling and show that Cx43 function influences the proliferative potential of hypothalamic cells.
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Affiliation(s)
- Antonia Recabal
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Roberto Elizondo-Vega
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Camille Philippot
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn Bonn, Germany
| | - Magdiel Salgado
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Sergio López
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Alejandra Palma
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Estefanía Tarifeño-Saldivia
- Department of Biochemistry and Molecular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Aline Timmermann
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn Bonn, Germany
| | - Gerald Seifert
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn Bonn, Germany
| | - Teresa Caprile
- Department of Cellular Biology, Faculty of Biological Sciences, University of Concepcion Concepcion, Chile
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn Bonn, Germany
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Fang M, Yamasaki R, Li G, Masaki K, Yamaguchi H, Fujita A, Isobe N, Kira JI. Connexin 30 Deficiency Attenuates Chronic but Not Acute Phases of Experimental Autoimmune Encephalomyelitis Through Induction of Neuroprotective Microglia. Front Immunol 2018; 9:2588. [PMID: 30464764 PMCID: PMC6234958 DOI: 10.3389/fimmu.2018.02588] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 10/19/2018] [Indexed: 01/25/2023] Open
Abstract
Glial connexins (Cxs) form gap junction channels through which a pan-glial network plays key roles in maintaining homeostasis of the central nervous system (CNS). In multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE), expression of astrocytic Cx43 is lost in acute lesions but upregulated in chronic plaques, while astrocytic Cx30 is very low in normal white matter and changes in its expression have not been convincingly shown. In Cx30 or Cx43 single knockout (KO) mice and even in Cx30/Cx43 double KO mice, acute EAE is unaltered. However, the effects of Cx30/Cx43 deficiency on chronic EAE remains to be elucidated. We aimed to clarify the roles of Cx30 in chronic neuroinflammation by studying EAE induced by myelin oligodendrocyte glycoprotein peptide 35–55 in Cx30 KO mice. We found that Cx30 deficiency improved the clinical symptoms and demyelination of chronic but not acute EAE without influencing CD3+ T cell infiltration. Furthermore, increased ramified microglia in the naïve state and induced earlier and stronger microglial activation in the acute and chronic phases of EAE was observed. These activated microglia had an anti-inflammatory phenotype, as shown by the upregulation of arginase-1 and brain-derived neurotrophic factor and the downregulation of nitric oxide synthase 2. In the naïve state, Cx30 deficiency induced modest enlargement of astrocytic processes in the spinal cord gray matter and a partial reduction of Cx43 expression in the spinal cord white matter. These astrocytes in Cx30 KO mice showed earlier and stronger activation during the acute phase of EAE, with upregulated A2 astrocyte markers and a significant decrease in Cx43 in the chronic phases. Spinal cord neurons and axons were more preserved in Cx30 KO mice than in littermates in the chronic phase of EAE. These findings suggest that Cx30 deficiency increased ramified microglia in the CNS in the naïve state and improved chronic EAE through redirecting microglia toward an anti-inflammatory phenotype, suggesting a hitherto unknown critical role of astrocytic Cx30 in regulating microglial number and functional state.
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Affiliation(s)
- Mei Fang
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Ryo Yamasaki
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Guangrui Li
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Katsuhisa Masaki
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Hiroo Yamaguchi
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Atsushi Fujita
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Noriko Isobe
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.,Department of Neurological Therapeutics, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Jun-Ichi Kira
- Department of Neurology, Neurological Institute, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
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Xin W, Bonci A. Functional Astrocyte Heterogeneity and Implications for Their Role in Shaping Neurotransmission. Front Cell Neurosci 2018; 12:141. [PMID: 29896091 PMCID: PMC5987431 DOI: 10.3389/fncel.2018.00141] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 05/08/2018] [Indexed: 12/20/2022] Open
Abstract
In recent years, the role of astrocytes in shaping neuronal signaling has come to the forefront of neuroscience research. The development of genetic tools that enable targeted manipulation of astrocytes has revealed a wealth of mechanisms by which they can alter the synaptic strength and intrinsic excitability of neurons in behaviorally relevant ways. In parallel, several studies have demonstrated significant variability in the gene expression and physiology of astrocytes within and between brain regions. Thus, to form an accurate understanding of how astrocytes contribute to neuronal transmission, we must take into consideration the diversity that exists in their intrinsic properties. In this review, we will summarize recent findings on astrocyte heterogeneity and discuss the implications for their interactions with neurons and their effects on neuronal transmission.
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Affiliation(s)
- Wendy Xin
- Synaptic Plasticity Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, United States.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Antonello Bonci
- Synaptic Plasticity Section, Cellular Neurobiology Branch, National Institute on Drug Abuse Intramural Research Program, Baltimore, MD, United States.,Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Neuroscience, Georgetown University Medical Center, School of Medicine, Washington, DC, United States.,Department of Psychiatry, University of Maryland, School of Medicine, Baltimore, MD, United States
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35
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Juszczak GR, Stankiewicz AM. Glucocorticoids, genes and brain function. Prog Neuropsychopharmacol Biol Psychiatry 2018; 82:136-168. [PMID: 29180230 DOI: 10.1016/j.pnpbp.2017.11.020] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/18/2017] [Accepted: 11/23/2017] [Indexed: 01/02/2023]
Abstract
The identification of key genes in transcriptomic data constitutes a huge challenge. Our review of microarray reports revealed 88 genes whose transcription is consistently regulated by glucocorticoids (GCs), such as cortisol, corticosterone and dexamethasone, in the brain. Replicable transcriptomic data were combined with biochemical and physiological data to create an integrated view of the effects induced by GCs. The most frequently reported genes were Errfi1 and Ddit4. Their up-regulation was associated with the altered transcription of genes regulating growth factor and mTORC1 signaling (Gab1, Tsc22d3, Dusp1, Ndrg2, Ppp5c and Sesn1) and progression of the cell cycle (Ccnd1, Cdkn1a and Cables1). The GC-induced reprogramming of cell function involves changes in the mRNA level of genes responsible for the regulation of transcription (Klf9, Bcl6, Klf15, Tle3, Cxxc5, Litaf, Tle4, Jun, Sox4, Sox2, Sox9, Irf1, Sall2, Nfkbia and Id1) and the selective degradation of mRNA (Tob2). Other genes are involved in the regulation of metabolism (Gpd1, Aldoc and Pdk4), actin cytoskeleton (Myh2, Nedd9, Mical2, Rhou, Arl4d, Osbpl3, Arhgef3, Sdc4, Rdx, Wipf3, Chst1 and Hepacam), autophagy (Eva1a and Plekhf1), vesicular transport (Rhob, Ehd3, Vps37b and Scamp2), gap junctions (Gjb6), immune response (Tiparp, Mertk, Lyve1 and Il6r), signaling mediated by thyroid hormones (Thra and Sult1a1), calcium (Calm2), adrenaline/noradrenaline (Adcy9 and Adra1d), neuropeptide Y (Npy1r) and histamine (Hdc). GCs also affected genes involved in the synthesis of polyamines (Azin1) and taurine (Cdo1). The actions of GCs are restrained by feedback mechanisms depending on the transcription of Sgk1, Fkbp5 and Nr3c1. A side effect induced by GCs is increased production of reactive oxygen species. Available data show that the brain's response to GCs is part of an emergency mode characterized by inactivation of non-core activities, restrained inflammation, restriction of investments (growth), improved efficiency of energy production and the removal of unnecessary or malfunctioning cellular components to conserve energy and maintain nutrient supply during the stress response.
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Affiliation(s)
- Grzegorz R Juszczak
- Department of Animal Behavior, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 36A, 05-552 Magdalenka, Poland.
| | - Adrian M Stankiewicz
- Department of Molecular Biology, Institute of Genetics and Animal Breeding, Jastrzebiec, ul. Postepu 36A, 05-552 Magdalenka, Poland
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36
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Ghézali G, Calvo CF, Pillet LE, Llense F, Ezan P, Pannasch U, Bemelmans AP, Etienne Manneville S, Rouach N. Connexin 30 controls astroglial polarization during postnatal brain development. Development 2018; 145:145/4/dev155275. [PMID: 29475972 PMCID: PMC5869003 DOI: 10.1242/dev.155275] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 01/21/2018] [Indexed: 12/26/2022]
Abstract
Astrocytes undergo intense morphological maturation during development, changing from individual sparsely branched cells to polarized and tremendously ramified cells. Connexin 30, an astroglial gap-junction channel-forming protein expressed postnatally, regulates in situ the extension and ramification of astroglial processes. However, the involvement of connexin 30 in astroglial polarization, which is known to control cell morphology, remains unexplored. We found that connexin 30, independently of gap-junction-mediated intercellular biochemical coupling, alters the orientation of astrocyte protrusion, centrosome and Golgi apparatus during polarized migration in an in vitro wound-healing assay. Connexin 30 sets the orientation of astroglial motile protrusions via modulation of the laminin/β1 integrin/Cdc42 polarity pathway. Connexin 30 indeed reduces laminin levels, inhibits the redistribution of the β1-integrin extracellular matrix receptors, and inhibits the recruitment and activation of the small Rho GTPase Cdc42 at the leading edge of migrating astrocytes. In vivo, connexin 30, the expression of which is developmentally regulated, also contributes to the establishment of hippocampal astrocyte polarity during postnatal maturation. This study thus reveals that connexin 30 controls astroglial polarity during development. Summary: Connexin 30 sets the orientation of astroglial motile protrusions during polarized migration in vitro and contributes in vivo to the establishment of hippocampal astrocyte polarity during postnatal maturation.
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Affiliation(s)
- Grégory Ghézali
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris 75005, France.,Doctoral School N°158, Pierre and Marie Curie University, Paris 75005, France
| | - Charles-Félix Calvo
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris 75005, France
| | - Laure-Elise Pillet
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris 75005, France.,Doctoral School N°562, Paris Descartes University, Paris 75006, France
| | - Flora Llense
- Institut Pasteur, CNRS UMR 3691, Cell Polarity, Migration and Cancer Unit, 25 Rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Pascal Ezan
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris 75005, France
| | - Ulrike Pannasch
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris 75005, France
| | - Alexis-Pierre Bemelmans
- Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Département de la Recherche Fondamentale, Institut de biologie François Jacob, MIRCen, and CNRS UMR 9199, Université Paris-Sud, Neurodegenerative Diseases Laboratory, Fontenay-aux-Roses 92260, France
| | - Sandrine Etienne Manneville
- Institut Pasteur, CNRS UMR 3691, Cell Polarity, Migration and Cancer Unit, 25 Rue du Dr Roux, 75724 Paris Cedex 15, France
| | - Nathalie Rouach
- Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, Paris 75005, France
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37
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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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38
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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: 876] [Impact Index Per Article: 146.0] [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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39
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Heterogeneity and function of hippocampal macroglia. Cell Tissue Res 2017; 373:653-670. [PMID: 29204745 DOI: 10.1007/s00441-017-2746-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Accepted: 11/16/2017] [Indexed: 12/26/2022]
Abstract
The contribution of glial cells to normal and impaired hippocampal function is increasingly being recognized, although important questions as to the mechanisms that these cells use for their crosstalk with neurons and capillaries are still unanswered or lead to controversy. Astrocytes in the hippocampus are morphologically variable and a single cell contacts with its processes more than 100,000 synapses. They predominantly express inward rectifier K+ channels and transporters serving homeostatic function but may also release gliotransmitters to modify neuronal signaling and brain circulation. Intracellular Ca2+ transients are key events in the interaction of astrocytes with neurons and the vasculature. Hippocampal NG2 glia represent a population of cells with proliferative capacity throughout adulthood. Intriguingly, they receive direct synaptic input from pyramidal neurons and interneurons and express a multitude of ion channels and receptors. Despite in-depth knowledge about the features of these transmembrane proteins, the physiological impact of NG2 glial cells and their synaptic input remain nebulous. Because of the low abundance of oligodendrocytes in the hippocampus, limited information is available about their specific properties. Given the multitude of signaling molecules expressed by the various types of hippocampal glial cells (and because of space constraints), we focus, in this review, on those properties that are considered key for the interaction of the respective cell type with its neighborhood.
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40
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Charvériat M, Naus CC, Leybaert L, Sáez JC, Giaume C. Connexin-Dependent Neuroglial Networking as a New Therapeutic Target. Front Cell Neurosci 2017; 11:174. [PMID: 28694772 PMCID: PMC5483454 DOI: 10.3389/fncel.2017.00174] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2017] [Accepted: 06/08/2017] [Indexed: 12/12/2022] Open
Abstract
Astrocytes and neurons dynamically interact during physiological processes, and it is now widely accepted that they are both organized in plastic and tightly regulated networks. Astrocytes are connected through connexin-based gap junction channels, with brain region specificities, and those networks modulate neuronal activities, such as those involved in sleep-wake cycle, cognitive, or sensory functions. Additionally, astrocyte domains have been involved in neurogenesis and neuronal differentiation during development; they participate in the “tripartite synapse” with both pre-synaptic and post-synaptic neurons by tuning down or up neuronal activities through the control of neuronal synaptic strength. Connexin-based hemichannels are also involved in those regulations of neuronal activities, however, this feature will not be considered in the present review. Furthermore, neuronal processes, transmitting electrical signals to chemical synapses, stringently control astroglial connexin expression, and channel functions. Long-range energy trafficking toward neurons through connexin-coupled astrocytes and plasticity of those networks are hence largely dependent on neuronal activity. Such reciprocal interactions between neurons and astrocyte networks involve neurotransmitters, cytokines, endogenous lipids, and peptides released by neurons but also other brain cell types, including microglial and endothelial cells. Over the past 10 years, knowledge about neuroglial interactions has widened and now includes effects of CNS-targeting drugs such as antidepressants, antipsychotics, psychostimulants, or sedatives drugs as potential modulators of connexin function and thus astrocyte networking activity. In physiological situations, neuroglial networking is consequently resulting from a two-way interaction between astrocyte gap junction-mediated networks and those made by neurons. As both cell types are modulated by CNS drugs we postulate that neuroglial networking may emerge as new therapeutic targets in neurological and psychiatric disorders.
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Affiliation(s)
| | - Christian C Naus
- Department of Cellular and Physiological Science, Life Science Institute, University of British ColumbiaVancouver, BC, Canada
| | - Luc Leybaert
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent UniversityGhent, Belgium
| | - Juan C Sáez
- Departamento de Fisiología, Pontificia Universidad Católica de ChileSantiago, Chile.,Centro Interdisciplinario de Neurociencias de Valparaíso, Instituto MilenioValparaíso, Chile
| | - Christian Giaume
- Center of Interdisciplinary Research in Biology, Collège de FranceParis, France
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41
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Bazzigaluppi P, Weisspapir I, Stefanovic B, Leybaert L, Carlen PL. Astrocytic gap junction blockade markedly increases extracellular potassium without causing seizures in the mouse neocortex. Neurobiol Dis 2016; 101:1-7. [PMID: 28007587 DOI: 10.1016/j.nbd.2016.12.017] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/24/2016] [Accepted: 12/18/2016] [Indexed: 10/20/2022] Open
Abstract
Extracellular potassium concentration, [K+]o, is a major determinant of neuronal excitability. In the healthy brain, [K+]o levels are tightly controlled. During seizures, [K+]o increases up to 15mM and is thought to cause seizures due to its depolarizing effect. Although astrocytes have been suggested to play a key role in the redistribution (or spatial buffering) of excess K+ through Connexin-43 (Cx43)-based Gap Junctions (GJs), the relation between this dynamic regulatory process and seizure generation remains unknown. Here we contrasted the role of astrocytic GJs and hemichannels by studying the effect of GJ and hemichannel blockers on [K+]o regulation in vivo. [K+]o was measured by K+-sensitive microelectrodes. Neuronal excitability was estimated by local field potential (LFP) responses to forepaw stimulation and changes in the power of resting state activity. Starting at the baseline [K+]o level of 1.61±0.3mM, cortical microinjection of CBX, a broad spectrum connexin channel blocker, increased [K+]o to 11±3mM, Cx43 GJ/hemichannel blocker Gap27 increased it from 1.9±0.7 to 9±1mM. At these [K+]o levels, no seizures were observed. Cx43 hemichannel blockade with TAT-Gap19 increased [K+]o by only ~1mM. Microinjection of 4-aminopyridine, a known convulsant, increased [K+]o to ~10mM and induced spontaneously recurring seizures, whereas direct application of K+ did not trigger seizure activity. These findings are the first in vivo demonstration that astrocytic GJs are major determinants for the spatial buffering of [K+]o and that an increase in [K+]o alone does not trigger seizures in the neocortex.
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Affiliation(s)
- Paolo Bazzigaluppi
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada; Physical Sciences, Sunnybrook Research Institute, M4N 3M5 Toronto, Ontario, Canada.
| | - Iliya Weisspapir
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada
| | - Bojana Stefanovic
- Physical Sciences, Sunnybrook Research Institute, M4N 3M5 Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Ontario, Canada
| | - Luc Leybaert
- Department of Basic Medical Sciences, University of Ghent, 9000 Ghent, Belgium
| | - Peter L Carlen
- Fundamental Neurobiology, Krembil Research Institute, University Health Network, M5T 2S8 Toronto, Ontario, Canada
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42
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Jeanson T, Duchêne A, Richard D, Bourgoin S, Picoli C, Ezan P, Mouthon F, Giaume C, Hamon M, Charvériat M. Potentiation of Amitriptyline Anti-Hyperalgesic-Like Action By Astroglial Connexin 43 Inhibition in Neuropathic Rats. Sci Rep 2016; 6:38766. [PMID: 27941941 PMCID: PMC5150232 DOI: 10.1038/srep38766] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 11/10/2016] [Indexed: 02/06/2023] Open
Abstract
Antidepressants, prescribed as first line treatment of neuropathic pain, have a limited efficacy and poorly tolerated side effects. Because recent studies pointed out the implication of astroglial connexins (Cx) in both neuropathic pain and antidepressive treatment, we investigated whether their blockade by mefloquine could modulate the action of the tricyclic antidepressant amitriptyline. Using primary cultures, we found that both mefloquine and amitriptyline inhibited Cx43-containing gap junctions, and that the drug combination acted synergically. We then investigated whether mefloquine could enhance amitriptyline efficacy in a preclinical model of neuropathic pain. Sprague-Dawley rats that underwent chronic unilateral constriction injury (CCI) to the sciatic nerve (SN) were treated with either amitriptyline, mefloquine or the combination of both drugs. Whereas acute treatments were ineffective, chronic administration of amitriptyline reduced CCI-SN-induced hyperalgesia-like behavior, and this effect was markedly enhanced by co-administration of mefloquine, which was inactive on its own. No pharmacokinetic interactions between both drugs were observed and CCI-SN-induced neuroinflammatory and glial activation markers remained unaffected by these treatments in dorsal root ganglia and spinal cord. Mechanisms downstream of CCI-SN-induced neuroinflammation and glial activation might therefore be targeted. Connexin inhibition in astroglia could represent a promising approach towards improving neuropathic pain therapy by antidepressants.
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Affiliation(s)
- Tiffany Jeanson
- Theranexus, Lyon, France.,CIRB, Collège de France, Paris, France
| | | | - Damien Richard
- CHU Clermont-Ferrand, Service de Pharmacologie Médicale, Clermont-Ferrand, France
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43
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Augustin V, Bold C, Wadle SL, Langer J, Jabs R, Philippot C, Weingarten DJ, Rose CR, Steinhäuser C, Stephan J. Functional anisotropic panglial networks in the lateral superior olive. Glia 2016; 64:1892-911. [PMID: 27458984 DOI: 10.1002/glia.23031] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 06/24/2016] [Accepted: 06/30/2016] [Indexed: 12/12/2022]
Abstract
Astrocytes form large gap junctional networks that contribute to ion and neurotransmitter homeostasis. Astrocytes concentrate in the lateral superior olive (LSO), a prominent auditory brainstem center. Compared to the LSO, astrocyte density is lower in the region dorsal to the LSO (dLSO) and in the internuclear space between the LSO, the superior paraolivary nucleus (SPN). We questioned whether astrocyte networks exhibit certain properties that reflect the precise neuronal arrangement. Employing whole-cell patch-clamp and concomitant injection of a gap junction-permeable tracer, we analyzed size and orientation of astrocyte networks in LSO, dLSO, and SPN-LSO in acute brainstem slices of mice at postnatal days 10-20. The majority of LSO networks exhibited an oval topography oriented orthogonally to the tonotopic axis, whereas dLSO networks showed no preferred orientation. This correlated with the overall astrocyte morphology in both regions, i.e. LSO astrocyte processes were oriented mainly orthogonally to the tonotopic axis. To assess the spread of small ions within LSO networks, we analyzed the diffusion of Na(+) signals between cells using Na(+) imaging. We found that Na(+) not only diffused between SR101(+) astrocytes, but also from astrocytes into SR101(-) cells. Using PLP-GFP mice for tracing, we could show that LSO networks contained astrocytes and oligodendrocytes. Together, our results demonstrate that LSO astrocytes and LSO oligodendrocytes form functional anisotropic panglial networks that are oriented predominantly orthogonally to the tonotopic axis. Thus, our results point toward an anisotropic ion and metabolite diffusion and a limited glial crosstalk between neighboring isofrequency bands in the LSO. GLIA 2016;64:1892-1911.
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Affiliation(s)
- Vanessa Augustin
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany
| | - Charlotte Bold
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany
| | - Simon L Wadle
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany
| | - Julia Langer
- Institute of Neurobiology, Universitaetsstasse 1, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Ronald Jabs
- Medical Faculty, Institute of Cellular Neurosciences, University of Bonn, Sigmund-Freud-Strasse 25, Bonn, Germany
| | - Camille Philippot
- Medical Faculty, Institute of Cellular Neurosciences, University of Bonn, Sigmund-Freud-Strasse 25, Bonn, Germany
| | - Dennis J Weingarten
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany
| | - Christine R Rose
- Institute of Neurobiology, Universitaetsstasse 1, Heinrich Heine University Duesseldorf, Duesseldorf, Germany
| | - Christian Steinhäuser
- Medical Faculty, Institute of Cellular Neurosciences, University of Bonn, Sigmund-Freud-Strasse 25, Bonn, Germany
| | - Jonathan Stephan
- Department of Biology, Animal Physiology Group, University of Kaiserslautern, Erwin Schroedinger-Strasse 13, Kaiserslautern, Germany.
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44
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Zhang K, Chen C, Yang Z, He W, Liao X, Ma Q, Deng P, Lu J, Li J, Wang M, Li M, Zheng L, Zhou Z, Sun W, Wang L, Jia H, Yu Z, Zhou Z, Chen X. Sensory Response of Transplanted Astrocytes in Adult Mammalian Cortex In Vivo. Cereb Cortex 2016; 26:3690-3704. [PMID: 27405333 PMCID: PMC5004757 DOI: 10.1093/cercor/bhw213] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 06/13/2016] [Indexed: 12/16/2022] Open
Abstract
Glial precursor transplantation provides a potential therapy for brain disorders. Before its clinical application, experimental evidence needs to indicate that engrafted glial cells are functionally incorporated into the existing circuits and become essential partners of neurons for executing fundamental brain functions. While previous experiments supporting for their functional integration have been obtained under in vitro conditions using slice preparations, in vivo evidence for such integration is still lacking. Here, we utilized in vivo two-photon Ca2+ imaging along with immunohistochemistry, fluorescent indicator labeling-based axon tracing and correlated light/electron microscopy to analyze the profiles and the functional status of glial precursor cell-derived astrocytes in adult mouse neocortex. We show that after being transplanted into somatosensory cortex, precursor-derived astrocytes are able to survive for more than a year and respond with Ca2+ signals to sensory stimulation. These sensory-evoked responses are mediated by functionally-expressed nicotinic receptors and newly-established synaptic contacts with the host cholinergic afferents. Our results provide in vivo evidence for a functional integration of transplanted astrocytes into adult mammalian neocortex, representing a proof-of-principle for sensory cortex remodeling through addition of essential neural elements. Moreover, we provide strong support for the use of glial precursor transplantation to understand glia-related neural development in vivo.
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Affiliation(s)
- Kuan Zhang
- Brain Research Center, Third Military Medical University, Chongqing 400038, China
| | - Chunhai Chen
- Department of Occupational Health, Third Military Medical University, Chongqing 400038, China
| | - Zhiqi Yang
- Brain Research Center, Third Military Medical University, Chongqing 400038, China.,Department of Neurology, Lanzhou General Hospital, Lanzhou Military Area Command, Lanzhou, Gansu 730050, China
| | - Wenjing He
- Brain Research Center, Third Military Medical University, Chongqing 400038, China
| | - Xiang Liao
- Brain Research Center, Third Military Medical University, Chongqing 400038, China
| | - Qinlong Ma
- Department of Occupational Health, Third Military Medical University, Chongqing 400038, China
| | - Ping Deng
- Department of Occupational Health, Third Military Medical University, Chongqing 400038, China
| | - Jian Lu
- Brain Research Center, Third Military Medical University, Chongqing 400038, China
| | - Jingcheng Li
- Brain Research Center, Third Military Medical University, Chongqing 400038, China
| | - Meng Wang
- Brain Research Center, Third Military Medical University, Chongqing 400038, China
| | - Mingli Li
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Lianghong Zheng
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Zhuan Zhou
- State Key Laboratory of Biomembrane and Membrane Biotechnology, Institute of Molecular Medicine, Peking-Tsinghua Center for Life Sciences, PKU-IDG/McGovern Institute for Brain Research, Peking University, Beijing 100871, China
| | - Wei Sun
- Brain Research Center, Third Military Medical University, Chongqing 400038, China
| | - Liting Wang
- Brain Research Center, Third Military Medical University, Chongqing 400038, China
| | - Hongbo Jia
- Brain Research Instrument Innovation Center, Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163, China
| | - Zhengping Yu
- Department of Occupational Health, Third Military Medical University, Chongqing 400038, China
| | - Zhou Zhou
- Department of Occupational Health, Third Military Medical University, Chongqing 400038, China
| | - Xiaowei Chen
- Brain Research Center, Third Military Medical University, Chongqing 400038, China.,CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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45
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Connexin 50 modulates Sox2 expression in spinal-cord-derived ependymal stem/progenitor cells. Cell Tissue Res 2016; 365:295-307. [PMID: 27221278 DOI: 10.1007/s00441-016-2421-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 05/01/2016] [Indexed: 12/23/2022]
Abstract
Ion channels included in the family of Connexins (Cx) have been reported to influence the secondary expansion of traumatic spinal cord injury (SCI) and neuropathic pain following SCI. However, Cxs also contribute to spinal cord neurogenesis during the remyelinating process and functional recovery after SCI. Certain Cxs have been recently related to the control of cell proliferation and the differentiation of neuronal progenitors. Adult spinal-cord-derived ependymal stem progenitor cells (epSPC) show high expression levels of Cx50 in non-pathological conditions and lower expression when they actively proliferate after injury (epSPCi). We explore the role of Cx50 in the ependymal population in the modulation of Sox2, a crucial factor of neural progenitor self-renewal and a promising target for promoting neuronal-cell-fate induction for neuronal tissue repair. Short-interfering-RNA ablation or over-expression of Cx50 regulates the expression of Sox2 in both epSPC and epSPCi. Interestingly, Cx50 and Sox2 co-localize at the nucleus indicating a potential role for this ion channel beyond cell-to-cell communication in the spinal cord. In vivo and in vitro experiments with Clotrimazole, a specific pharmacological modulator of Cx50, show the convergent higher expression of Cx50 and Sox2 in the isolated epSPC/epSPCi and in spinal cord tissue. Therefore, the pharmacological modulation of Cx50 might constitute an interesting mechanism for Sox2 induction to modulate the endogenous regenerative potential of neuronal tissue with a potential application in regenerative therapies.
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46
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Hu X, Yuan Y, Wang D, Su Z. Heterogeneous astrocytes: Active players in CNS. Brain Res Bull 2016; 125:1-18. [PMID: 27021168 DOI: 10.1016/j.brainresbull.2016.03.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2016] [Revised: 03/22/2016] [Accepted: 03/24/2016] [Indexed: 12/12/2022]
Abstract
Astrocytes, the predominant cell type that are broadly distributed in the brain and spinal cord, play key roles in maintaining homeostasis of the central nerve system (CNS) in physiological and pathological conditions. Increasing evidence indicates that astrocytes are a complex colony with heterogeneity on morphology, gene expression, function and many other aspects depending on their spatio-temporal distribution and activation level. In pathological conditions, astrocytes differentially respond to all kinds of insults, including injury and disease, and participate in the neuropathological process. Based on current studies, we here give an overview of the roles of heterogeneous astrocytes in CNS, especially in neuropathologies, which focuses on biological and functional diversity of astrocytes. We propose that a precise understanding of the heterogeneous astrocytes is critical to unlocking the secrets about pathogenesis and treatment of the mazy CNS.
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Affiliation(s)
- Xin Hu
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Yimin Yuan
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Dan Wang
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China
| | - Zhida Su
- Institute of Neuroscience and Key Laboratory of Molecular Neurobiology of Ministry of Education, Second Military Medical University, Shanghai, China.
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47
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Liu X, Gangoso E, Yi C, Jeanson T, Kandelman S, Mantz J, Giaume C. General anesthetics have differential inhibitory effects on gap junction channels and hemichannels in astrocytes and neurons. Glia 2015; 64:524-36. [PMID: 26666873 DOI: 10.1002/glia.22946] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2015] [Accepted: 11/16/2015] [Indexed: 11/07/2022]
Abstract
Astrocytes represent a major non-neuronal cell population actively involved in brain functions and pathologies. They express a large amount of gap junction proteins that allow communication between adjacent glial cells and the formation of glial networks. In addition, these membrane proteins can also operate as hemichannels, through which "gliotransmitters" are released, and thus contribute to neuroglial interaction. There are now reports demonstrating that alterations of astroglial gap junction communication and/or hemichannel activity impact neuronal and synaptic activity. Two decades ago we reported that several general anesthetics inhibited gap junctions in primary cultures of astrocytes (Mantz et al., (1993) Anesthesiology 78(5):892-901). As there are increasing studies investigating neuroglial interactions in anesthetized mice, we here updated this previous study by employing acute cortical slices and by characterizing the effects of general anesthetics on both astroglial gap junctions and hemichannels. As hemichannel activity is not detected in cortical astrocytes under basal conditions, we treated acute slices with the endotoxin LPS or proinflammatory cytokines to induce hemichannel activity in astrocytes, which in turn activated neuronal hemichannels. We studied two extensively used anesthetics, propofol and ketamine, and the more recently developed dexmedetomidine. We report that these drugs have differential inhibitory effects on gap junctional communication and hemichannel activity in astrocytes when used in their respective, clinically relevant concentrations, and that dexmedetomidine appears to be the least effective on both channel functions. In addition, the three anesthetics have similar effects on neuronal hemichannels. Altogether, our observations may contribute to optimizing the selection of anesthetics for in vivo animal studies.
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Affiliation(s)
- Xinhe Liu
- Collège De France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National De La Recherche Scientifique, Unité Mixte De Recherche 7241/Institut National De La Santé Et De La Recherche Médicale U1050, Paris Cedex 05, France.,University Pierre Et Marie Curie, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France
| | - Ester Gangoso
- Collège De France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National De La Recherche Scientifique, Unité Mixte De Recherche 7241/Institut National De La Santé Et De La Recherche Médicale U1050, Paris Cedex 05, France.,University Pierre Et Marie Curie, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France
| | - Chenju Yi
- Collège De France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National De La Recherche Scientifique, Unité Mixte De Recherche 7241/Institut National De La Santé Et De La Recherche Médicale U1050, Paris Cedex 05, France.,University Pierre Et Marie Curie, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France
| | - Tiffany Jeanson
- Collège De France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National De La Recherche Scientifique, Unité Mixte De Recherche 7241/Institut National De La Santé Et De La Recherche Médicale U1050, Paris Cedex 05, France.,University Pierre Et Marie Curie, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France
| | - Stanislas Kandelman
- Département D'anesthésie Et De Réanimation, HUPNVS, Université Paris Diderot, Paris, France
| | - Jean Mantz
- Service D'anesthésie Réanimation, Hôpital Européen Georges Pompidou, Paris Descartes University, Paris, France.,Unité D'histopathologie Humaine Et Modèles Animaux Département Infection Et Epidémiologie Institut Pasteur 25, Rue Du Docteur Roux, Paris, France
| | - Christian Giaume
- Collège De France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National De La Recherche Scientifique, Unité Mixte De Recherche 7241/Institut National De La Santé Et De La Recherche Médicale U1050, Paris Cedex 05, France.,University Pierre Et Marie Curie, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France
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48
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Rodriguez-Jimenez FJ, Alastrue-Agudo A, Stojkovic M, Erceg S, Moreno-Manzano V. Connexin 50 Expression in Ependymal Stem Progenitor Cells after Spinal Cord Injury Activation. Int J Mol Sci 2015; 16:26608-18. [PMID: 26561800 PMCID: PMC4661840 DOI: 10.3390/ijms161125981] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Revised: 10/26/2015] [Accepted: 10/30/2015] [Indexed: 12/28/2022] Open
Abstract
Ion channels included in the family of Connexins (Cx) help to control cell proliferation and differentiation of neuronal progenitors. Here we explored the role of Connexin 50 (Cx50) in cell fate modulation of adult spinal cord derived neural precursors located in the ependymal canal (epSPC). epSPC from non-injured animals showed high expression levels of Cx50 compared to epSPC from animals with spinal cord injury (SCI) (epSPCi). When epSPC or epSPCi were induced to spontaneously differentiate in vitro we found that Cx50 favors glial cell fate, since higher expression levels, endogenous or by over-expression of Cx50, augmented the expression of the astrocyte marker GFAP and impaired the neuronal marker Tuj1. Cx50 was found in both the cytoplasm and nucleus of glial cells, astrocytes and oligodendrocyte-derived cells. Similar expression patterns were found in primary cultures of mature astrocytes. In addition, opposite expression profile for nuclear Cx50 was observed when epSPC and activated epSPCi were conducted to differentiate into mature oligodendrocytes, suggesting a different role for this ion channel in spinal cord beyond cell-to-cell communication. In vivo detection of Cx50 by immunohistochemistry showed a defined location in gray matter in non-injured tissues and at the epicenter of the injury after SCI. epSPCi transplantation, which accelerates locomotion regeneration by a neuroprotective effect after acute SCI is associated with a lower signal of Cx50 within the injured area, suggesting a minor or detrimental contribution of this ion channel in spinal cord regeneration by activated epSPCi.
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Affiliation(s)
| | - Ana Alastrue-Agudo
- Neuronal and Tissue Regeneration Laboratory, Centro de Investigación Príncipe Felipe, Valencia E-46012, Spain.
| | - Miodrag Stojkovic
- Spebo Medical, 16000 Leskovac, Serbia.
- Human Genetics, Faculty of Medical Sciences, University of Kragujevac, 34000 Kragujevac, Serbia.
| | - Slaven Erceg
- Stem Cell Therapies in Neurodegenerative Diseases Laboratory, Centro de Investigación Príncipe Felipe, Valencia E-46012, Spain.
| | - Victoria Moreno-Manzano
- Neuronal and Tissue Regeneration Laboratory, Centro de Investigación Príncipe Felipe, Valencia E-46012, Spain.
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Anders S, Minge D, Griemsmann S, Herde MK, Steinhäuser C, Henneberger C. Spatial properties of astrocyte gap junction coupling in the rat hippocampus. Philos Trans R Soc Lond B Biol Sci 2015; 369:20130600. [PMID: 25225094 PMCID: PMC4173286 DOI: 10.1098/rstb.2013.0600] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Gap junction coupling enables astrocytes to form large networks. Its strength determines how easily a signalling molecule diffuses through the network and how far a locally initiated signal can spread. Changes of coupling strength are well-documented during development and in response to various stimuli. Precise quantification of coupling is needed for studying such modifications and their functional consequences. We therefore explored spatial properties of astrocyte coupling in a model simulating dye loading of single astrocytes. Dye spread into the astrocyte network could be characterized by a coupling length constant and coupling anisotropy. In experiments, the fluorescent marker Alexa Fluor 594 was used to measure these parameters in CA1 and dentate gyrus of the rat hippocampus. Coupling did not differ between regions but showed a temperature-dependence, partially owing to changes of intracellular diffusivity, detected by measuring coupling length constants but not the more variable cell counts of dye-coupled astrocytes. We further found that coupling is anisotropic depending on distance to the pyramidal cell layer, which correlated with regional differences of astrocyte morphology. This demonstrates that applying these new analytical approaches provides useful quantitative information on gap junction coupling and its heterogeneity.
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Affiliation(s)
- Stefanie Anders
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany
| | - Daniel Minge
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany
| | - Stephanie Griemsmann
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany
| | - Michel K Herde
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany
| | - Christian Steinhäuser
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany
| | - Christian Henneberger
- Institute of Cellular Neurosciences, Medical School, University of Bonn, Bonn, Germany UCL Institute of Neurology, UCL, London, UK
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50
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Abudara V, Roux L, Dallérac G, Matias I, Dulong J, Mothet JP, Rouach N, Giaume C. Activated microglia impairs neuroglial interaction by opening Cx43 hemichannels in hippocampal astrocytes. Glia 2015; 63:795-811. [PMID: 25643695 DOI: 10.1002/glia.22785] [Citation(s) in RCA: 93] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 12/18/2014] [Indexed: 01/04/2023]
Abstract
Glia plays an active role in neuronal functions and dysfunctions, some of which depend on the expression of astrocyte connexins, the gap junction channel and hemichannel proteins. Under neuroinflammation triggered by the endotoxin lipopolysacharide (LPS), microglia is primary stimulated and releases proinflammatory agents affecting astrocytes and neurons. Here, we investigate the effects of such microglial activation on astrocyte connexin-based channel functions and their consequences on synaptic activity in an ex vivo model. We found that LPS induces astroglial hemichannel opening in acute hippocampal slices while no change is observed in gap junctional communication. Based on pharmacological and genetic approaches we found that the LPS-induced hemichannel opening is mainly due to Cx43 hemichannel activity. This process primarily requires a microglial stimulation resulting in the release of at least two proinflammatory cytokines, IL-1β and TNF-α. Consequences of the hemichannel-mediated increase in membrane permeability are a calcium rise in astrocytes and an enhanced glutamate release associated to a reduction in excitatory synaptic activity of pyramidal neurons in response to Schaffer's collateral stimulation. As a whole our findings point out astroglial hemichannels as key determinants of the impairment of synaptic transmission during neuroinflammation.
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Affiliation(s)
- Verónica Abudara
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050, Paris Cedex, France; University Pierre et Marie Curie, ED, Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, Paris, France; Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
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