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Cooper ML, Pasini S, Lambert WS, D'Alessandro KB, Yao V, Risner ML, Calkins DJ. Redistribution of metabolic resources through astrocyte networks mitigates neurodegenerative stress. Proc Natl Acad Sci U S A 2020; 117:18810-18821. [PMID: 32690710 PMCID: PMC7414143 DOI: 10.1073/pnas.2009425117] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
In the central nervous system, glycogen-derived bioenergetic resources in astrocytes help promote tissue survival in response to focal neuronal stress. However, our understanding of the extent to which these resources are mobilized and utilized during neurodegeneration, especially in nearby regions that are not actively degenerating, remains incomplete. Here we modeled neurodegeneration in glaucoma, the world's leading cause of irreversible blindness, and measured how metabolites mobilize through astrocyte gap junctions composed of connexin 43 (Cx43). We elevated intraocular pressure in one eye and determined how astrocyte-derived metabolites in the contralateral optic projection responded. Remarkably, astrocyte networks expand and redistribute metabolites along distances even 10 mm in length, donating resources from the unstressed to the stressed projection in response to intraocular pressure elevation. While resource donation improves axon function and visual acuity in the directly stressed region, it renders the donating tissue susceptible to bioenergetic, structural, and physiological degradation. Intriguingly, when both projections are stressed in a WT animal, axon function and visual acuity equilibrate between the two projections even when each projection is stressed for a different length of time. This equilibration does not occur when Cx43 is not present. Thus, Cx43-mediated astrocyte metabolic networks serve as an endogenous mechanism used to mitigate bioenergetic stress and distribute the impact of neurodegenerative disease processes. Redistribution ultimately renders the donating optic nerve vulnerable to further metabolic stress, which could explain why local neurodegeneration does not remain confined, but eventually impacts healthy regions of the brain more broadly.
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Affiliation(s)
- Melissa L Cooper
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville TN 37232-0654
| | - Silvia Pasini
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville TN 37232-0654
| | - Wendi S Lambert
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville TN 37232-0654
| | - Karis B D'Alessandro
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville TN 37232-0654
| | - Vincent Yao
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville TN 37232-0654
| | - Michael L Risner
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville TN 37232-0654
| | - David J Calkins
- Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville TN 37232-0654
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Mathews J, Levin M. Gap junctional signaling in pattern regulation: Physiological network connectivity instructs growth and form. Dev Neurobiol 2017; 77:643-673. [PMID: 27265625 PMCID: PMC10478170 DOI: 10.1002/dneu.22405] [Citation(s) in RCA: 58] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2016] [Revised: 05/27/2016] [Accepted: 05/31/2016] [Indexed: 12/19/2022]
Abstract
Gap junctions (GJs) are aqueous channels that allow cells to communicate via physiological signals directly. The role of gap junctional connectivity in determining single-cell functions has long been recognized. However, GJs have another important role: the regulation of large-scale anatomical pattern. GJs are not only versatile computational elements that allow cells to control which small molecule signals they receive and emit, but also establish connectivity patterns within large groups of cells. By dynamically regulating the topology of bioelectric networks in vivo, GJs underlie the ability of many tissues to implement complex morphogenesis. Here, a review of recent data on patterning roles of GJs in growth of the zebrafish fin, the establishment of left-right patterning, the developmental dysregulation known as cancer, and the control of large-scale head-tail polarity, and head shape in planarian regeneration has been reported. A perspective in which GJs are not only molecular features functioning in single cells, but also enable global neural-like dynamics in non-neural somatic tissues has been proposed. This view suggests a rich program of future work which capitalizes on the rapid advances in the biophysics of GJs to exploit GJ-mediated global dynamics for applications in birth defects, regenerative medicine, and morphogenetic bioengineering. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 77: 643-673, 2017.
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Affiliation(s)
- Juanita Mathews
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, MA
| | - Michael Levin
- Department of Biology, Tufts Center for Regenerative and Developmental Biology, Tufts University, Medford, MA
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Pierozan P, Ferreira F, de Lima BO, Pessoa-Pureur R. Quinolinic acid induces disrupts cytoskeletal homeostasis in striatal neurons. Protective role of astrocyte-neuron interaction. J Neurosci Res 2014; 93:268-84. [DOI: 10.1002/jnr.23494] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Revised: 08/29/2014] [Accepted: 09/14/2014] [Indexed: 12/18/2022]
Affiliation(s)
- Paula Pierozan
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul; Porto Alegre Brazil
| | - Fernanda Ferreira
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul; Porto Alegre Brazil
| | - Bárbara Ortiz de Lima
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul; Porto Alegre Brazil
| | - Regina Pessoa-Pureur
- Departamento de Bioquímica; Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul; Porto Alegre Brazil
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Li Z, Lin XM, Gong PL, Zeng FD, Du GH. Effects of Gingko biloba Extract on Gap Junction Changes Induced by Reperfusion/Reoxygenation After Ischemia/Hypoxia in Rat Brain. THE AMERICAN JOURNAL OF CHINESE MEDICINE 2012; 33:923-34. [PMID: 16355449 DOI: 10.1142/s0192415x05003430] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Gap junction communication between astrocytes plays an important role in the brain. The purpose of this study was to investigate the effects of Gingko biloba extract (GBE) on the changes of connexin 43 (Cx43) mRNA and protein expression levels of rat cortex and hippocampus induced by ischemia-reperfusion and astrocyte gap junction intercellular communication (GJIC) induced by hypoxia-reoxygenation. After 2 hours of middle cerebral artery occlusion (MCAO) followed by 24 hours of reperfusion, there was obvious neurological deficit in rats. Cx43 mRNA and protein expression levels of rat cortex and hippocampus in the ischemia hemisphere were decreased significantly. When GBE at doses of 50 and 100 mg/kg body weight was administrated by p.o. daily for 7 days, the neurological deficit was improved, and lower Cx43 mRNA and protein expression levels induced by ischemia-reperfusion were recovered to normal. The i.p. injection of nimodipine (0.7 mg/kg weight body) also showed improvement on neurological deficit and Cx43 expression levels. Astrocyte GJIC was measured by the fluorescence recovery after photobleaching (FRAP). Hypoxia-reoxygenation induced a significant decrease in GJIC. Pretreatment with GBE (100 mg/l) and nimodipine (1.6 mg/l) significantly prevented the hypoxia-reoxygenation inhibition of GJIC. These results suggest that GBE could exert its neuroprotective effects by improvement of Cx43 expression and GJIC induced by hypoxia/ischemia-reoxygenation/ reperfusion injury.
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Affiliation(s)
- Zhen Li
- Institute of Clinical Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Giaume C, Liu X. From a glial syncytium to a more restricted and specific glial networking. ACTA ACUST UNITED AC 2011; 106:34-9. [PMID: 21979115 DOI: 10.1016/j.jphysparis.2011.09.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 08/26/2011] [Accepted: 09/02/2011] [Indexed: 02/03/2023]
Abstract
In the brain, glia represents the cell population that expresses the highest level of connexins, the membrane protein constituents of gap junction channels and hemichannels. This statement has initially led to propose the existence of a glial syncytium. Since then, functional studies have established that connexin channel-mediated communication between glial cells was more restricted and plastic that primarily thought. In particular, this is the case for astrocytes that form functional networks of communicating cells. Altogether these findings lead to reconsider the interaction between neurons and glia that should not be solely studied at the single cell level but also at a more integrated level as the interplay between neuronal circuits and glial networks.
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Affiliation(s)
- Christian Giaume
- CIRB, CNRS UMR UMR7241/INSERM U1050, MEMOLIFE Laboratory of Excellence and Paris Science Lettre, Collège de France, University Pierre et Marie Curie, ED, N°158, 11 Place Marcelin Berthelot, 75005 Paris, France.
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[Biological mechanisms involved in the spread of traumatic brain damage]. Med Intensiva 2011; 36:37-44. [PMID: 21903299 DOI: 10.1016/j.medin.2011.06.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2011] [Revised: 06/23/2011] [Accepted: 06/25/2011] [Indexed: 01/11/2023]
Abstract
Traumatic brain injury (TBI) is a worldwide health problem that is especially prevalent in young adults. It is characterized by one or more primary injury foci, with secondary spread to initially not compromised areas via cascades of inflammatory response, excitotoxicity, energy failure conditions, and amplification of the original tissue injury by glia. In theory, such progression of injury should be amenable to management. However, all neuroprotective drug trials have failed, and specific treatments remain lacking. These negative results can be explained by a neuron centered approach, excluding the participation of other cell types and pathogenic mechanisms. To change this situation, it is necessary to secure a better understanding of the biological mechanisms determining damage progression or spread. We discuss the biological mechanisms involved in the progression of post-trauma tissue damage, including the general physiopathology of TBI and cellular mechanisms of secondary damage such as inflammation, apoptosis, cell tumefaction, excitotoxicity, and the role of glia in damage propagation. We highlight the role of glia in each cellular mechanism discussed. Therapeutic approaches related to the described mechanisms have been included. The discussion is completed with a working model showing the convergence of the main topics.
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Giaume C, Koulakoff A, Roux L, Holcman D, Rouach N. Astroglial networks: a step further in neuroglial and gliovascular interactions. Nat Rev Neurosci 2010; 11:87-99. [DOI: 10.1038/nrn2757] [Citation(s) in RCA: 562] [Impact Index Per Article: 40.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Giaume C, Theis M. Pharmacological and genetic approaches to study connexin-mediated channels in glial cells of the central nervous system. ACTA ACUST UNITED AC 2009; 63:160-76. [PMID: 19963007 DOI: 10.1016/j.brainresrev.2009.11.005] [Citation(s) in RCA: 104] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2009] [Revised: 11/18/2009] [Accepted: 11/19/2009] [Indexed: 11/18/2022]
Abstract
This review gives an overview of connexin expression in glial cells of the central nervous system, the different modes of connexin action, including gap junctional channels and hemichannels, as well as the available methodologies to measure their activity. We summarize the strengths and limitations of current pharmacological and genetic approaches to interfere with connexin channel functions. We outline new avenues not only to study specific mechanisms by which connexins exert these functions but also to selectively investigate well-defined coupling compartments among glial networks.
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Heneka MT, Rodríguez JJ, Verkhratsky A. Neuroglia in neurodegeneration. ACTA ACUST UNITED AC 2009; 63:189-211. [PMID: 19944719 DOI: 10.1016/j.brainresrev.2009.11.004] [Citation(s) in RCA: 199] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2009] [Revised: 11/18/2009] [Accepted: 11/19/2009] [Indexed: 12/11/2022]
Abstract
Neuroglial cells are fundamental for control of brain homeostasis and they represent the intrinsic brain defence system. All forms in neuropathology therefore inevitably involve glia. The neurodegenerative diseases disrupt connectivity within brain circuits affecting neuronal-neuronal, neuronal-glial and glial-glial contacts. In addition neurodegenerative processes trigger universal and conserved glial reactions represented by astrogliosis and microglial activation. The complex of recently acquired knowledge allows us to regard the neurodegenerative diseases as primarily gliodegenerative processes, in which glial cells determine the progression and outcome of neuropathological process.
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Affiliation(s)
- Michael T Heneka
- Klinische Neurowissenschaften, Klinik und Poliklinik für Neurologie, 53127 Bonn, Germany.
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Verkhratsky A. Neuronismo y reticulismo: neuronal-glial circuits unify the reticular and neuronal theories of brain organization. Acta Physiol (Oxf) 2009; 195:111-22. [PMID: 18983447 DOI: 10.1111/j.1748-1716.2008.01926.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The neuronal doctrine, which shaped the development of neuroscience, was born from a long-lasting struggle between reticularists, who assumed internal continuity of neural networks and neuronists, who defined the brain as a network of physically separated cellular entities, defined as neurones. Modern views regard the brain as a complex of constantly interacting cellular circuits, represented by neuronal networks embedded into internally connected astroglial syncytium. The neuronal-glial circuits endowed with distinct signalling cascades form a 'diffuse nervous net' suggested by Golgi, where millions of synapses belonging to very different neurones are integrated first into neuronal-glial-vascular units and then into more complex structures connected through glial syncytium. These many levels of integration, both morphological and functional, presented by neuronal-glial circuitry ensure the spatial and temporal multiplication of brain cognitive power.
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Affiliation(s)
- A Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, UK.
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Giaume C, Kirchhoff F, Matute C, Reichenbach A, Verkhratsky A. Glia: the fulcrum of brain diseases. Cell Death Differ 2007; 14:1324-35. [PMID: 17431421 DOI: 10.1038/sj.cdd.4402144] [Citation(s) in RCA: 202] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Neuroglia represented by astrocytes, oligodendrocytes and microglial cells provide for numerous vital functions. Glial cells shape the micro-architecture of the brain matter; they are involved in information transfer by virtue of numerous plasmalemmal receptors and channels; they receive synaptic inputs; they are able to release 'glio'transmitters and produce long-range information exchange; finally they act as pluripotent neural precursors and some of them can even act as stem cells, which provide for adult neurogenesis. Recent advances in gliology emphasised the role of glia in the progression and handling of the insults to the nervous system. The brain pathology, is, to a very great extent, a pathology of glia, which, when falling to function properly, determines the degree of neuronal death, the outcome and the scale of neurological deficit. Glial cells are central in providing for brain homeostasis. As a result glia appears as a brain warden, and as such it is intrinsically endowed with two opposite features: it protects the nervous tissue as long as it can, but it also can rapidly assume the guise of a natural killer, trying to eliminate and seal the damaged area, to save the whole at the expense of the part.
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Affiliation(s)
- C Giaume
- INSERM, U840 and Collège de France, Paris, France
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12
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Gulinello M, Etgen AM. Sexually dimorphic hormonal regulation of the gap junction protein, CX43, in rats and altered female reproductive function in CX43+/- mice. Brain Res 2005; 1045:107-15. [PMID: 15910768 PMCID: PMC4169114 DOI: 10.1016/j.brainres.2005.03.021] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 03/10/2005] [Accepted: 03/15/2005] [Indexed: 11/19/2022]
Abstract
Astrocytic gap junctional communication is important in steroid hormone regulation of reproductive processes at the level of the hypothalamus, including estrous cyclicity and sexual behavior. We examined the effects of estradiol and progesterone on the abundance of the gap junctional protein, connexin 43 (CX43), which is highly expressed in astrocytes. Gonadectomized rats received hormone treatments that induce maximal sexual behavior and gonadotropin surges in females (estrogen for 48 h followed by progesterone, estrogen alone or progesterone alone). Control animals received vehicle (oil) injections. In the female rat preoptic area (POA), containing the gonadotropin-releasing hormone (GnRH) cell bodies, treatment with estrogen, progesterone or estrogen + progesterone significantly increased CX43 protein levels in immunoblots. In contrast, estrogen + progesterone significantly decreased CX43 levels in the male rat POA. This sexually dimorphic hormonal regulation of CX43 was not evident in the hypothalamus, which contains primarily GnRH nerve terminals. Treatment with estrogen + progesterone significantly decreased CX43 levels in both the male and female hypothalamus. To examine the role of CX43 in female reproductive function, we studied heterozygous female CX43 (CX43+/-) mice. Most mutant mice did not show normal estrous cycles. In addition, when compared to wild type females, CX43+/- mice had reduced lordosis behavior. These data suggest that hypothalamic CX43 expression is regulated by steroid hormones in a brain-region-specific and sexually dimorphic manner. Therefore, gap junctional communication in the POA and hypothalamus may be a factor regulating the estrous cycle and sexual behavior in female rodents.
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Affiliation(s)
- Maria Gulinello
- Albert Einstein College of Medicine, Department of Neuroscience, 1300 Morris Park Avenue F113, Bronx, NY 10461, USA.
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Leybaert L, Braet K, Vandamme W, Cabooter L, Martin PEM, Evans WH. Connexin channels, connexin mimetic peptides and ATP release. ACTA ACUST UNITED AC 2004; 10:251-7. [PMID: 14681025 DOI: 10.1080/cac.10.4-6.251.257] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Connexin hemichannels, that is, half gap junction channels (not connecting cells), have been implicated in the release of various messengers such as ATP and glutamate. We used connexin mimetic peptides, which are, small peptides mimicking a sequence on the connexin subunit, to investigate hemichannel functioning in endothelial cell lines. Short exposure (30 min) to synthetic peptides mimicking a sequence on the first or second extracellular loop of the connexin subunit strongly supressed ATP release and dye uptake triggered by either intracellular InsP(3) elevation or exposure to zero extracellular calcium, while gap junctional coupling was not affected under these conditions. The effect was dependent on the expression of connexin-43 in the cells. Connexin mimetic peptides thus appear to be interesting tools to distinguish connexin hemichannel from gap junction channel functioning. In addition, they are well suited to further explore the role of connexins in cellular release or uptake processes, to investigate hemichannel gating and to reveal new unknown functions of the large conductance hemichannel pathway between the cell and its environment. Work performed up to now with these peptides should be re-interpreted in terms of these new findings.
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Affiliation(s)
- Luc Leybaert
- Department of Physiology and Pathophysiology, Ghent University, Ghent, Belgium.
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Hormuzdi SG, Filippov MA, Mitropoulou G, Monyer H, Bruzzone R. Electrical synapses: a dynamic signaling system that shapes the activity of neuronal networks. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2004; 1662:113-37. [PMID: 15033583 DOI: 10.1016/j.bbamem.2003.10.023] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2003] [Revised: 10/14/2003] [Accepted: 10/14/2003] [Indexed: 01/25/2023]
Abstract
Gap junctions consist of intercellular channels dedicated to providing a direct pathway for ionic and biochemical communication between contacting cells. After an initial burst of publications describing electrical coupling in the brain, gap junctions progressively became less fashionable among neurobiologists, as the consensus was that this form of synaptic transmission would play a minimal role in shaping neuronal activity in higher vertebrates. Several new findings over the last decade (e.g. the implication of connexins in genetic diseases of the nervous system, in processing sensory information and in synchronizing the activity of neuronal networks) have brought gap junctions back into the spotlight. The appearance of gap junctional coupling in the nervous system is developmentally regulated, restricted to distinct cell types and persists after the establishment of chemical synapses, thus suggesting that this form of cell-cell signaling may be functionally interrelated with, rather than alternative to chemical transmission. This review focuses on gap junctions between neurons and summarizes the available data, derived from molecular, biological, electrophysiological, and genetic approaches, that are contributing to a new appreciation of their role in brain function.
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Affiliation(s)
- Sheriar G Hormuzdi
- Department of Clinical Neurobiology, Interdisciplinary Center for Neurosciences, University of Heidelberg, 69120 Heidelberg, Germany
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Zhan H, Yokoyama K, Otani H, Tanigaki K, Shirota N, Takano S, Ohkuma S. Different roles of proteolipids and 70-kDa subunits of V-ATPase in growth and death of cultured human cells. Genes Cells 2003; 8:501-13. [PMID: 12786941 DOI: 10.1046/j.1365-2443.2003.00651.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND The vacuolar-type proton-translocating adenosine triphosphatase (V-ATPase) plays important roles in cell growth and tumour progression. V-ATPase is composed of two distinct structures, a hydrophilic catalytic cytosolic sector (V(1)) and a hydrophobic transmembrane sector (V(0)). The V(1) sector is composed of 5-8 different subunits with the structure A(3)B(3)C(1)D(1)E(1)F(1)G(1)H(1). The V0 sector is composed of 5 different subunits with the structure 1161381191166. The over-expression of 16-kDa proteolipid subunit of V-ATPase in the perinuclear region of the human adventitial fibroblasts promotes phenotypic modulation that contributes to neointimal formation and medial thickening. A relationship between oncogenicity and the expression of the 16-kDa proteolipid has also been suggested in human pancreatic carcinoma tissue. RESULTS We found that the mRNA levels of the 16-kDa proteolipid but not of the 70-kDa subunit of V-ATPase in human myofibroblasts were more abundant in serum-containing medium (MF(+) cells) than serum-free medium (MF(-) cells). In HeLa cells, the levels of mRNA and protein of the 16-kDa, 21-kDa or 70-kDa were clearly suppressed when the corresponding anti-sense oligonucleotides were administered to the culture medium. The growth rate and viability (mostly due to necrosis) of HeLa cells were reduced markedly by the 16-kDa and 21-kDa anti-sense, but little by the 70-kDa anti-sense, and not at all by any sense oligonucleotides. The localization of 16-kDa/21-kDa proteolipid subunits was different from that of the 70-kDa subunit in HeLa cells. CONCLUSION These results suggest that the 16-kDa and 21-kDa proteolipid subunits of the V0 sector play crucial roles in growth and death of cultured human cells. Our results may provide new insights into the mechanism and therapeutic implications for vessel wall hyperplasia and tumorigenesis.
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Affiliation(s)
- Hong Zhan
- Department of Dynamic Physiology, Graduate School of Natural Science and Technology, Ishikawa 920-0934, Japan
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Popratiloff A, Pollack SM, Giaume C, Peusner KD. Differential expression of connexin 43 in the chick tangential vestibular nucleus. J Neurosci Res 2003; 71:617-28. [PMID: 12584721 DOI: 10.1002/jnr.10535] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The chick tangential nucleus is a major vestibular nucleus whose principal cells receive convergent inputs from primary vestibular and nonvestibular fibers and participate in the vestibular reflexes. During development, the principal cells gradually acquire the mature firing pattern in part by losing a specific potassium current around hatching (H). Here we focus on characterizing the expression of connexin 43 (Cx43), a gap junction protein found mainly between astrocytes in the mature brain. The astrocytic syncytium plays an important role in maintaining extracellular potassium ion balance in the brain. Accordingly, it is important to characterize the potential of this syncytium to communicate during the critical developmental age of hatching. Using fluorescence immunocytochemistry, we investigated whether Cx43 staining was concentrated in specific cellular compartments at H1 by applying well-known markers for astrocytes (glial fibrillary acidic protein; GFAP), oligodendrocytes (antimyelin), neurons (microtubule-associated protein 2), and synaptic terminals (synaptotagmin). GFAP-positive astrocytes and GFAP-negative nonneuronal cells around the principal cell bodies were labeled with Cx43, suggesting that Cx43 was expressed exclusively by nonneuronal cells near the neuronal elements. Next, the developmental pattern of expression of Cx43 was studied at embryonic day 16 (E16), H1, and H9. At E16, Cx43 was present weakly as random small clusters in the tangential nucleus, whereas, at H1, overall staining became localized, with increases in size, brightness, and number of immunostained clusters. Finally, at H9, Cx43 staining decreased, but cluster size and location remained unchanged. These results suggest that Cx43 is developmentally regulated with a peak at birth and is associated primarily with astrocytes and nonneuronal cells near the principal cell bodies.
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Affiliation(s)
- Anastas Popratiloff
- Department of Anatomy and Cell Biology, and Neuroscience Program, George Washington University Medical Center, Washington, DC, USA.
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Rochefort N, Quenech'du N, Watroba L, Mallat M, Giaume C, Milleret C. Microglia and astrocytes may participate in the shaping of visual callosal projections during postnatal development. JOURNAL OF PHYSIOLOGY, PARIS 2002; 96:183-92. [PMID: 12445895 DOI: 10.1016/s0928-4257(02)00005-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the adult cat, axons running through the corpus callosum interconnect the border between the visual cortical areas 17 and 18 (A17 and A18) of both hemispheres. This specific pattern emerges during postnatal development, under normal viewing conditions (NR), from the elimination of initially exuberant callosal projections. In contrast, if the postnatal visual experience is monocular from birth (MD), juvenile callosal projections are stabilised throughout A17 and A18. The present study aimed at using such a model in vivo to find indications of a contribution of glial cells in the shaping of projections in the developing CNS through interactions with neurones, both in normal and pathological conditions. As a first stage, the distribution and the morphology of microglial cells and astrocytes were investigated from 2 weeks to adulthood. Microglial cells, stained with isolectin-B4, were clustered in the white matter below A17 and A18. Until one month, these clustered cells displayed an ameboid morphology in NR group, while they were more ramified in MD animals. Their phenotype thus depends on the postnatal visual experience, which indicates that microglial cells may interact with axons of visual neurones. It also suggests that they may differentially contribute to the elimination and the stabilisation of juvenile exuberant callosal fibres in NR and MD animals respectively. Beyond one month, microglial cells were very ramified in both experimental groups. Astrocytes were labelled with a GFAP-antibody. The distributions of connexins 43 (Cx43) and 30 (Cx30), the main proteic components of gap junction channels in astrocytes, were also investigated using specific antibodies. Both in NR and MD groups, until 1 month, GFAP-positive astrocytes and Cx43 were mainly localised within the subcortical white matter. Then GFAP, Cx43 and Cx30 stainings progressively appeared within the cortex, throughout A17 and A18 but with a differential laminar expression according to the age. Thus, the distributions of both astrocytes and connexins changed with age; however, the monocular occlusion had no visible effect. This suggests that astrocytes may contribute to the postnatal development of neuronal projections to the primary visual cortex, including visual callosal projections.
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Affiliation(s)
- N Rochefort
- Laboratoire de Physiologie de la Perception et de l'Action, UMR 7124, Collège de France, 11 Place Marcelin Berthelot, 75005 Paris, France
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Rouach N, Calvo CF, Glowinski J, Giaume C. Brain macrophages inhibit gap junctional communication and downregulate connexin 43 expression in cultured astrocytes. Eur J Neurosci 2002; 15:403-7. [PMID: 11849308 DOI: 10.1046/j.0953-816x.2001.01868.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Astrocytes are typically interconnected by gap junction channels that allow, in vitro as well as in vivo, a high degree of intercellular communication between these glial cells. Using cocultures of astrocytes and neurons, we have demonstrated that gap junctional communication (GJC) and connexin 43 (Cx43) expression, the major junctional protein in astrocytes, are controlled by neuronal activity. Moreover, neuronal death downregulates these two parameters. Because in several brain pathologies neuronal loss is associated with an increase in brain macrophage (BM) density, we have now investigated whether coculture with BM affects astrocyte gap junctions. We report here that addition of BM for 24 h decreases the expression of GJC and Cx43 in astrocytes in a density-dependent manner. In contrast, Cx43 is not detected in BM and no heterotypic coupling is observed between the two cell types. A soluble factor does not seem to be involved in these inhibitions because they are not observed either in the presence of BM conditioned media or in the absence of direct contact between the two cell types by using inserts. These observations could have pathophysiological relevance as neuronal death, microglial proliferation and astrocytic reactions occur in brain injuries and pathologies. Because astrocyte interactions with BM and dying neurons both result in the downregulation of Cx43 expression and in the inhibition of GJC, a critical consequence on astrocytic phenotype in those situations could be the inhibition of gap junctions.
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Affiliation(s)
- N Rouach
- INSERM U114, Chaire de Neuropharmacologie, Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France
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Castonguay A, Lévesque S, Robitaille R. Glial cells as active partners in synaptic functions. PROGRESS IN BRAIN RESEARCH 2001; 132:227-40. [PMID: 11544991 DOI: 10.1016/s0079-6123(01)32079-4] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Affiliation(s)
- A Castonguay
- Centre de Recherche en Sciences Neurologiques and Département de Physiologie, Université de Montréal, Montréal, PQ H3C 3J7, Canada
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Rouach N, Glowinski J, Giaume C. Activity-dependent neuronal control of gap-junctional communication in astrocytes. J Cell Biol 2000; 149:1513-26. [PMID: 10871289 PMCID: PMC2175141 DOI: 10.1083/jcb.149.7.1513] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2000] [Accepted: 05/18/2000] [Indexed: 11/27/2022] Open
Abstract
A typical feature of astrocytes is their high degree of intercellular communication through gap junction channels. Using different models of astrocyte cultures and astrocyte/neuron cocultures, we have demonstrated that neurons upregulate gap-junctional communication and the expression of connexin 43 (Cx43) in astrocytes. The propagation of intercellular calcium waves triggered in astrocytes by mechanical stimulation was also increased in cocultures. This facilitation depends on the age and number of neurons, indicating that the state of neuronal differentiation and neuron density constitute two crucial factors of this interaction. The effects of neurons on astrocytic communication and Cx43 expression were reversed completely after neurotoxic treatments. Moreover, the neuronal facilitation of glial coupling was suppressed, without change in Cx43 expression, after prolonged pharmacological treatments that prevented spontaneous synaptic activity. Altogether, these results demonstrate that neurons exert multiple and differential controls on astrocytic gap-junctional communication. Since astrocytes have been shown to facilitate synaptic efficacy, our findings suggest that neuronal and astrocytic networks interact actively through mutual setting of their respective modes of communication.
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Affiliation(s)
- Nathalie Rouach
- INSERM U114, Collège de France 11, 75231 Paris Cedex 05, France
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