101
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Astrocytes and microglia in acute cerebral injury underlying cerebral palsy associated with preterm birth. Pediatr Res 2014; 75:234-40. [PMID: 24336433 DOI: 10.1038/pr.2013.188] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 07/11/2013] [Indexed: 02/06/2023]
Abstract
Cerebral palsy is one of the most devastating consequences of brain injury around the time of birth, and nearly a third of cases are now associated with premature birth. Compared with term babies, preterm babies have an increased incidence of complications that may increase the risk of disability, such as intraventricular hemorrhage, periventricular leukomalacia, sepsis, and necrotizing enterocolitis. The response to injury is highly dependent on brain maturity, and although cellular vulnerability is well documented, there is now evidence that premyelinating axons are also particularly sensitive to ischemic injury. In this review, we will explore recent evidence highlighting a central role for glia in mediating increased risk of disability in premature infants, including excessive activation of microglia and opening of astrocytic gap junction hemichannels in spreading injury after brain ischemia, in part likely involving release of adenosine triphosphate (ATP) and overactivation of purinergic receptors, particularly in white matter. We propose the hypothesis that inflammation-induced opening of connexin hemichannels is a key regulating event that initiates a vicious circle of excessive ATP release, which in turn propagates activation of purinergic receptors on microglia and astrocytes. This suggests that developing effective neuroprotective strategies for preterm infants requires a detailed understanding of glial responses.
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102
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Dambach H, Hinkerohe D, Prochnow N, Stienen MN, Moinfar Z, Haase CG, Hufnagel A, Faustmann PM. Glia and epilepsy: Experimental investigation of antiepileptic drugs in an astroglia/microglia co-culture model of inflammation. Epilepsia 2013; 55:184-92. [DOI: 10.1111/epi.12473] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2013] [Indexed: 01/22/2023]
Affiliation(s)
- Hannes Dambach
- Department of Neuroanatomy and Molecular Brain Research; Ruhr University Bochum; Bochum Germany
| | - Daniel Hinkerohe
- Department of Neurology; Ruhr-University Bochum; Knappschafts Hospital; Bochum Germany
| | - Nora Prochnow
- Department of Neuroanatomy and Molecular Brain Research; Ruhr University Bochum; Bochum Germany
- International Graduate School of Neuroscience (IGSN); Ruhr University Bochum; Bochum Germany
| | - Martin N. Stienen
- Department of Neuroanatomy and Molecular Brain Research; Ruhr University Bochum; Bochum Germany
| | - Zahra Moinfar
- Department of Neuroanatomy and Molecular Brain Research; Ruhr University Bochum; Bochum Germany
- International Graduate School of Neuroscience (IGSN); Ruhr University Bochum; Bochum Germany
| | - Claus G. Haase
- Department of Neurology; Holy Spirit Hospital; Köln Germany
| | | | - Pedro M. Faustmann
- Department of Neuroanatomy and Molecular Brain Research; Ruhr University Bochum; Bochum Germany
- International Graduate School of Neuroscience (IGSN); Ruhr University Bochum; Bochum Germany
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103
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Kleopa KA, Sargiannidou I, Markoullis K. Connexin pathology in chronic multiple sclerosis and experimental autoimmune encephalomyelitis. ACTA ACUST UNITED AC 2013. [DOI: 10.1111/cen3.12055] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Kleopas A. Kleopa
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
| | - Irene Sargiannidou
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
| | - Kyriaki Markoullis
- Neurology Clinics and Neuroscience Laboratory; The Cyprus Institute of Neurology and Genetics; Nicosia Cyprus
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104
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Hogerton AL, Bowser MT. Monitoring neurochemical release from astrocytes using in vitro microdialysis coupled with high-speed capillary electrophoresis. Anal Chem 2013; 85:9070-7. [PMID: 23984889 DOI: 10.1021/ac401631k] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have developed a novel in vitro approach for monitoring fast neurochemical dynamics in model cell systems using microdialysis sampling coupled with high-speed capillary electrophoresis (CE). Cells from an immortalized astrocyte line (C8-D1A) were cultured in direct contact with the porous membrane of a microdialysis probe. Confocal microscopy was used to confirm cell viability and confluency over the microdialysis sampling region. Small molecules released from the astrocytes were efficiently sampled by the probe due to the direct contact with the membrane. Microdialysis sampling was coupled with online, high-speed CE allowing changes in the dialysate concentration of small molecule amine neurochemicals to be monitored with 20 s temporal resolution. Basal release of a number of important analytes was detected including glycine, taurine, D-serine, and glutamate. The ability of the in vitro microdialysis-CE instrument to monitor dynamic changes in analyte concentration was assessed by transferring a probe cultured with astrocytes from a solution containing artificial cerebrospinal fluid (aCSF) to a high K(+) solution (100 mM K(+)-aCSF). Upon stimulation, the observed concentration of a number of key neurochemicals increased dramatically including glycine (700%), taurine (185%), and serine (215%). Amino acids such as phenylalanine and valine, which are not known to respond to cellular swelling mechanisms, were unaffected by the K(+) stimulation.
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Affiliation(s)
- Amy L Hogerton
- Department of Chemistry, University of Minnesota , 207 Pleasant St. SE, Minneapolis, Minnesota 55455, United States
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105
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Xiong J, Kielian T. Microglia in juvenile neuronal ceroid lipofuscinosis are primed toward a pro-inflammatory phenotype. J Neurochem 2013; 127:245-58. [PMID: 23919525 DOI: 10.1111/jnc.12385] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 07/25/2013] [Accepted: 07/29/2013] [Indexed: 12/11/2022]
Abstract
Juvenile neuronal ceroid lipofuscinosis (JNCL) is a lysosomal storage disease caused by an autosomal recessive mutation in CLN3. Regions of microglial activation precede and predict areas of neuronal loss in JNCL; however, the functional role of activated microglia remains to be defined. The inflammasome is a key molecular pathway for activating pro-IL-1β in microglia, and IL-1β is elevated in the brains of JNCL patients and can induce neuronal cell death. Here, we utilized primary microglia isolated from CLN3(Δex7/8) mutant and wild-type (WT) mice to examine the impact of CLN3 mutation on microglial activation and inflammasome function. Treatment with neuronal lysates and ceramide, a lipid intermediate elevated in the JNCL brain, led to inflammasome activation and IL-1β release in CLN3(Δex7/8) microglia but not WT cells, as well as increased expression of additional pro-inflammatory mediators. Similar effects were observed following either TNF-α or IL-1β treatment, suggesting that CLN3(Δex7/8) microglia exist in primed state and hyper-respond to several inflammatory stimuli compared to WT cells. CLN3(Δex7/8) microglia displayed constitutive caspase-1 activity that when blocked led to increased glutamate release that coincided with hemichannel opening. Conditioned medium from activated CLN3(Δex7/8) or WT microglia induced significant cell death in CLN3(Δex7/8) but not WT neurons, demonstrating that intrinsically diseased CLN3(Δex7/8) neurons are less equipped to withstand cytotoxic insults generated by activated microglia. Collectively, aberrant microglial activation may contribute to the pathological chain of events leading to neurodegeneration during later stages of JNCL.
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Affiliation(s)
- Juan Xiong
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, Nebraska, USA
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106
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Disruption in connexin-based communication is associated with intracellular Ca²⁺ signal alterations in astrocytes from Niemann-Pick type C mice. PLoS One 2013; 8:e71361. [PMID: 23977027 PMCID: PMC3744576 DOI: 10.1371/journal.pone.0071361] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 06/27/2013] [Indexed: 01/12/2023] Open
Abstract
Reduced astrocytic gap junctional communication and enhanced hemichannel activity were recently shown to increase astroglial and neuronal vulnerability to neuroinflammation. Moreover, increasing evidence suggests that neuroinflammation plays a pivotal role in the development of Niemann-Pick type C (NPC) disease, an autosomal lethal neurodegenerative disorder that is mainly caused by mutations in the NPC1 gene. Therefore, we investigated whether the lack of NPC1 expression in murine astrocytes affects the functional state of gap junction channels and hemichannels. Cultured cortical astrocytes of NPC1 knock-out mice (Npc1−/−) showed reduced intercellular communication via gap junctions and increased hemichannel activity. Similarly, astrocytes of newborn Npc1−/− hippocampal slices presented high hemichannel activity, which was completely abrogated by connexin 43 hemichannel blockers and was resistant to inhibitors of pannexin 1 hemichannels. Npc1−/− astrocytes also showed more intracellular Ca2+ signal oscillations mediated by functional connexin 43 hemichannels and P2Y1 receptors. Therefore, Npc1−/− astrocytes present features of connexin based channels compatible with those of reactive astrocytes and hemichannels might be a novel therapeutic target to reduce neuroinflammation in NPC disease.
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107
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Alvis Miranda H, Castellar-Leones SM, Elzain MA, Moscote-Salazar LR. Brain abscess: Current management. J Neurosci Rural Pract 2013; 4:S67-81. [PMID: 24174804 PMCID: PMC3808066 DOI: 10.4103/0976-3147.116472] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Brain abscess (BA) is defined as a focal infection within the brain parenchyma, which starts as a localized area of cerebritis, which is subsequently converted into a collection of pus within a well-vascularized capsule. BA must be differentiated from parameningeal infections, including epidural abscess and subdural empyema. The BA is a challenge for the neurosurgeon because it is needed good clinical, pharmacological, and surgical skills for providing good clinical outcomes and prognosis to BA patients. Considered an infrequent brain infection, BA could be a devastator entity that easily left the patient into dead. The aim of this work is to review the current concepts regarding epidemiology, pathophysiology, etiology, clinical presentation, diagnosis, and management of BA.
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Affiliation(s)
| | | | - Mohammed Awad Elzain
- Department of Neurosurgery, National Center for Neurological Sciences, Shaab Hospital, Khartoum, Sudan
| | - Luis Rafael Moscote-Salazar
- Department of Neurosurgery, Instituto Nacional de Neurología y Neurocirugía, Hospital Ángeles de Pedregal, Mexico City, Colombia
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108
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Giaume C, Leybaert L, Naus CC, Sáez JC. Connexin and pannexin hemichannels in brain glial cells: properties, pharmacology, and roles. Front Pharmacol 2013; 4:88. [PMID: 23882216 PMCID: PMC3713369 DOI: 10.3389/fphar.2013.00088] [Citation(s) in RCA: 171] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2013] [Accepted: 06/21/2013] [Indexed: 12/22/2022] Open
Abstract
Functional interaction between neurons and glia is an exciting field that has expanded tremendously during the past decade. Such partnership has multiple impacts on neuronal activity and survival. Indeed, numerous findings indicate that glial cells interact tightly with neurons in physiological as well as pathological situations. One typical feature of glial cells is their high expression level of gap junction protein subunits, named connexins (Cxs), thus the membrane channels they form may contribute to neuroglial interaction that impacts neuronal activity and survival. While the participation of gap junction channels in neuroglial interactions has been regularly reviewed in the past, the other channel function of Cxs, i.e., hemichannels located at the cell surface, has only recently received attention. Gap junction channels provide the basis for a unique direct cell-to-cell communication, whereas Cx hemichannels allow the exchange of ions and signaling molecules between the cytoplasm and the extracellular medium, thus supporting autocrine and paracrine communication through a process referred to as “gliotransmission,” as well as uptake and release of metabolites. More recently, another family of proteins, termed pannexins (Panxs), has been identified. These proteins share similar membrane topology but no sequence homology with Cxs. They form multimeric membrane channels with pharmacology somewhat overlapping with that of Cx hemichannels. Such duality has led to several controversies in the literature concerning the identification of the molecular channel constituents (Cxs versus Panxs) in glia. In the present review, we update and discuss the knowledge of Cx hemichannels and Panx channels in glia, their properties and pharmacology, as well as the understanding of their contribution to neuroglial interactions in brain health and disease.
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Affiliation(s)
- Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050 Paris, France ; University Pierre et Marie Curie Paris, France ; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University Paris, France
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109
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Possible involvement of TLRs and hemichannels in stress-induced CNS dysfunction via mastocytes, and glia activation. Mediators Inflamm 2013; 2013:893521. [PMID: 23935250 PMCID: PMC3713603 DOI: 10.1155/2013/893521] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 05/16/2013] [Accepted: 06/11/2013] [Indexed: 12/13/2022] Open
Abstract
In the central nervous system (CNS), mastocytes and glial cells (microglia, astrocytes and oligodendrocytes) function as sensors of neuroinflammatory conditions, responding to stress triggers or becoming sensitized to subsequent proinflammatory challenges. The corticotropin-releasing hormone and glucocorticoids are critical players in stress-induced mastocyte degranulation and potentiation of glial inflammatory responses, respectively. Mastocytes and glial cells express different toll-like receptor (TLR) family members, and their activation via proinflammatory molecules can increase the expression of connexin hemichannels and pannexin channels in glial cells. These membrane pores are oligohexamers of the corresponding protein subunits located in the cell surface. They allow ATP release and Ca2+ influx, which are two important elements of inflammation. Consequently, activated microglia and astrocytes release ATP and glutamate, affecting myelinization, neuronal development, and survival. Binding of ligands to TLRs induces a cascade of intracellular events leading to activation of several transcription factors that regulate the expression of many genes involved in inflammation. During pregnancy, the previous responses promoted by viral infections and other proinflammatory conditions are common and might predispose the offspring to develop psychiatric disorders and neurological diseases. Such disorders could eventually be potentiated by stress and might be part of the etiopathogenesis of CNS dysfunctions including autism spectrum disorders and schizophrenia.
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110
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Gap junction channels and hemichannels in the CNS: regulation by signaling molecules. Neuropharmacology 2013; 75:567-82. [PMID: 23499663 DOI: 10.1016/j.neuropharm.2013.02.020] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Revised: 02/08/2013] [Accepted: 02/26/2013] [Indexed: 11/20/2022]
Abstract
Coordinated interaction among cells is critical to develop the extremely complex and dynamic tasks performed by the central nervous system (CNS). Cell synchronization is in part mediated by connexins and pannexins; two different protein families that form gap junction channels and hemichannels. Whereas gap junction channels connect the cytoplasm of contacting cells and coordinate electric and metabolic activities, hemichannels communicate intra- and extra-cellular compartments and serve as diffusional pathways for ions and small molecules. Cells in the CNS depend on paracrine/autocrine communication via several extracellular signaling molecules, such as, cytokines, growth factors, transmitters and free radical species to sense changes in microenvironment as well as to adapt to them. These signaling molecules modulate crucial processes of the CNS, including, cellular migration and differentiation, synaptic transmission and plasticity, glial activation, cell viability and microvascular blood flow. Gap junction channels and hemichannels are affected by different signaling transduction pathways triggered by these paracrine/autocrine signaling molecules. Most of the modulatory effects induced by these signaling molecules are specific to the cell type and the connexin and pannexin subtype expressed in different brain areas. In this review, we summarized and discussed most of the relevant and recently published information on the effects of signaling molecules on connexin or pannexin based channels and their possible relevance in CNS physiology and pathology. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'.
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111
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Cone AC, Ambrosi C, Scemes E, Martone ME, Sosinsky GE. A comparative antibody analysis of pannexin1 expression in four rat brain regions reveals varying subcellular localizations. Front Pharmacol 2013; 4:6. [PMID: 23390418 PMCID: PMC3565217 DOI: 10.3389/fphar.2013.00006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 01/09/2013] [Indexed: 11/13/2022] Open
Abstract
Pannexin1 (Panx1) channels release cytosolic ATP in response to signaling pathways. Panx1 is highly expressed in the central nervous system. We used four antibodies with different Panx1 anti-peptide epitopes to analyze four regions of rat brain. These antibodies labeled the same bands in Western blots and had highly similar patterns of immunofluorescence in tissue culture cells expressing Panx1, but Western blots of brain lysates from Panx1 knockout and control mice showed different banding patterns. Localizations of Panx1 in brain slices were generated using automated wide field mosaic confocal microscopy for imaging large regions of interest while retaining maximum resolution for examining cell populations and compartments. We compared Panx1 expression over the cerebellum, hippocampus with adjacent cortex, thalamus, and olfactory bulb. While Panx1 localizes to the same neuronal cell types, subcellular localizations differ. Two antibodies with epitopes against the intracellular loop and one against the carboxy terminus preferentially labeled cell bodies, while an antibody raised against an N-terminal peptide highlighted neuronal processes more than cell bodies. These labeling patterns may be a reflection of different cellular and subcellular localizations of full-length and/or modified Panx1 channels where each antibody is highlighting unique or differentially accessible Panx1 populations. However, we cannot rule out that one or more of these antibodies have specificity issues. All data associated with experiments from these four antibodies are presented in a manner that allows them to be compared and our claims thoroughly evaluated, rather than eliminating results that were questionable. Each antibody is given a unique identifier through the NIF Antibody Registry that can be used to track usage of individual antibodies across papers and all image and metadata are made available in the public repository, the Cell Centered Database, for on-line viewing, and download.
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Affiliation(s)
- Angela C Cone
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, University of California San Diego, La Jolla, CA, USA
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112
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Abbasian M, Sayyah M, Babapour V, Mahdian R. Intracerebroventricular injection of lipopolysaccharide increases gene expression of connexin32 gap junction in rat hippocampus. Basic Clin Neurosci 2013; 4:334-40. [PMID: 25337366 PMCID: PMC4202574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 03/22/2013] [Accepted: 04/25/2013] [Indexed: 11/10/2022] Open
Abstract
INTRODUCTION Gap junctions are intercellular membrane channels that provide direct cytoplasmic continuity between adjacent cells. This communication can be affected by changes in expression of gap junctional subunits called Connexins (Cx). Changes in the expression and function of connexins are associated with number of brain neurodegenerative diseases. Neuroinflammation is a hallmark of various central nervous system (CNS) diseases, like multiple sclerosis, Alzheimer's disease and epilepsy. Neuroinflammation causes change in Connexins expression. Hippocampus, one of the main brain regions with a wide network of Gap junctions between different neural cell types, has particular vulnerability to damage and consequent inflammation. Cx32 - among Connexins- is expressed in hippocampal Olygodandrocytes and some neural subpopulations. Although multiple lines of evidence indicate that there is an association between neuroinflammation and the expression of connexin, the direct effect of neuroinflammation on the expression of connexins has not been well studied. In the present study, the effect of neuroinflammation induced by the Lipopolysaccharide (LPS) on Cx32 gene and protein expressions in rat hippocampus is evaluated. METHODS LPS (2.5µg/rat) was infused into the rat cerebral ventricles for 14 days. Cx32 mRNA and protein levels were measured by Real Time PCR and Western Blot after 1st, 7th and 14th injection of LPS in the hippocampus. RESULTS Significant increase in Cx32 mRNA expression was observed after 7th injection of LPS (P < 0.001). However, no significant change was observed in Cx32 protein level. CONCLUSION LPS seems to modify Cx32 GJ communication in the hippocampus at transcription level but not at translation or post-translation level. In order to have a full view concerning modification of Cx32 GJ communication, effect of LPS on Cx32 channel gating should also be determined.
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Affiliation(s)
- Mohammad Abbasian
- Department of Physiology, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Mohammad Sayyah
- Department of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran, Iran
| | - Vahab Babapour
- Department of Physiology, Faculty of Veterinary Medicine, Tehran University, Tehran, Iran
| | - Reza Mahdian
- Biotechnology Research Center, Dept. of Molecular Medicine, Pasteur Institute of Iran
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113
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Wang N, De Bock M, Antoons G, Gadicherla AK, Bol M, Decrock E, Evans WH, Sipido KR, Bukauskas FF, Leybaert L. Connexin mimetic peptides inhibit Cx43 hemichannel opening triggered by voltage and intracellular Ca2+ elevation. Basic Res Cardiol 2012; 107:304. [PMID: 23095853 DOI: 10.1007/s00395-012-0304-2] [Citation(s) in RCA: 119] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Revised: 09/10/2012] [Accepted: 09/27/2012] [Indexed: 01/03/2023]
Abstract
Connexin mimetic peptides (CxMPs), such as Gap26 and Gap27, are known as inhibitors of gap junction channels but evidence is accruing that these peptides also inhibit unapposed/non-junctional hemichannels (HCs) residing in the plasma membrane. We used voltage clamp studies to investigate the effect of Gap26/27 at the single channel level. Such an approach allows unequivocal identification of HC currents by their single channel conductance that is typically ~220 pS for Cx43. In HeLa cells stably transfected with Cx43 (HeLa-Cx43), Gap26/27 peptides inhibited Cx43 HC unitary currents over minutes and increased the voltage threshold for HC opening. By contrast, an elevation of intracellular calcium ([Ca(2+)](i)) to 200-500 nM potentiated the unitary HC current activity and lowered the voltage threshold for HC opening. Interestingly, Gap26/27 inhibited the Ca(2+)-potentiated HC currents and prevented lowering of the voltage threshold for HC opening. Experiments on isolated pig ventricular cardiomyocytes, which display strong endogenous Cx43 expression, demonstrated voltage-activated unitary currents with biophysical properties of Cx43 HCs that were inhibited by small interfering RNA targeting Cx43. As observed in HeLa-Cx43 cells, HC current activity in ventricular cardiomyocytes was potentiated by [Ca(2+)](i) elevation to 500 nM and was inhibited by Gap26/27. Our results indicate that under pathological conditions, when [Ca(2+)](i) is elevated, Cx43 HC opening is promoted in cardiomyocytes and CxMPs counteract this effect.
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Affiliation(s)
- Nan Wang
- Physiology Group, Department of Basic Medical Sciences, Faculty of Medicine and Health Sciences, Ghent University, Belgium
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114
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Evans WH, Bultynck G, Leybaert L. Manipulating connexin communication channels: use of peptidomimetics and the translational outputs. J Membr Biol 2012; 245:437-49. [PMID: 22886208 PMCID: PMC3456916 DOI: 10.1007/s00232-012-9488-5] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Accepted: 07/07/2012] [Indexed: 12/22/2022]
Abstract
Gap junctions are key components underpinning multicellularity. They provide cell to cell channel pathways that enable direct intercellular communication and cellular coordination in tissues and organs. The channels are constructed of a family of connexin (Cx) membrane proteins. They oligomerize inside the cell, generating hemichannels (connexons) composed of six subunits arranged around a central channel. After transfer to the plasma membrane, arrays of Cx hemichannels (CxHcs) interact and couple with partners in neighboring attached cells to generate gap junctions. Cx channels have been studied using a range of technical approaches. Short peptides corresponding to sequences in the extra- and intracellular regions of Cxs were used first to generate epitope-specific antibodies that helped studies on the organization and functions of gap junctions. Subsequently, the peptides themselves, especially Gap26 and -27, mimetic peptides derived from each of the two extracellular loops of connexin43 (Cx43), a widely distributed Cx, have been extensively applied to block Cx channels and probe the biology of cell communication. The development of a further series of short peptides mimicking sequences in the intracellular loop, especially the extremity of the intracellular carboxyl tail of Cx43, followed. The primary inhibitory action of the peptidomimetics occurs at CxHcs located at unapposed regions of the cell's plasma membrane, followed by inhibition of cell coupling occurring across gap junctions. CxHcs respond to a range of environmental conditions by increasing their open probability. Peptidomimetics provide a way to block the actions of CxHcs with some selectivity. Furthermore, they are increasingly applied to address the pathological consequences of a range of environmental stresses that are thought to influence Cx channel operation. Cx peptidomimetics show promise as candidates in developing new therapeutic approaches for containing and reversing damage inflicted on CxHcs, especially in hypoxia and ischemia in the heart and in brain functions.
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Affiliation(s)
- W Howard Evans
- Institute of Infection and Immunity, Cardiff University School of Medicine, Heath Park, Cardiff, Wales CF14 4XN, UK.
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115
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Abrams CK, Scherer SS. Gap junctions in inherited human disorders of the central nervous system. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1818:2030-47. [PMID: 21871435 PMCID: PMC3771870 DOI: 10.1016/j.bbamem.2011.08.015] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2011] [Revised: 08/04/2011] [Accepted: 08/10/2011] [Indexed: 12/15/2022]
Abstract
CNS glia and neurons express connexins, the proteins that form gap junctions in vertebrates. We review the connexins expressed by oligodendrocytes and astrocytes, and discuss their proposed physiologic roles. Of the 21 members of the human connexin family, mutations in three are associated with significant central nervous system manifestations. For each, we review the phenotype and discuss possible mechanisms of disease. Mutations in GJB1, the gene for connexin 32 (Cx32) cause the second most common form of Charcot-Marie-Tooth disease (CMT1X). Though the only consistent phenotype in CMT1X patients is a peripheral demyelinating neuropathy, CNS signs and symptoms have been found in some patients. Recessive mutations in GJC2, the gene for Cx47, are one cause of Pelizaeus-Merzbacher-like disease (PMLD), which is characterized by nystagmus within the first 6 months of life, cerebellar ataxia by 4 years, and spasticity by 6 years of age. MRI imaging shows abnormal myelination. A different recessive GJC2 mutation causes a form of hereditary spastic paraparesis, which is a milder phenotype than PMLD. Dominant mutations in GJA1, the gene for Cx43, cause oculodentodigital dysplasia (ODDD), a pleitropic disorder characterized by oculo-facial abnormalities including micropthalmia, microcornia and hypoplastic nares, syndactyly of the fourth to fifth fingers and dental abnormalities. Neurologic manifestations, including spasticity and gait difficulties, are often but not universally seen. Recessive GJA1 mutations cause Hallermann-Streiff syndrome, a disorder showing substantial overlap with ODDD. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and functions.
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Affiliation(s)
- Charles K. Abrams
- Department of Neurology and Physiology & Pharmacology, SUNY Downstate Medical Center, 450 Clarkson Avenue, Brooklyn, NY 11203, 1-718-270-1270 Phone, 1-718-270-8944 Fax,
| | - Steven S. Scherer
- Department of Neurology, The University of Pennsylvania School of Medicine, Room 450 Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, PA 19104-6077, 215-573-3198,
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116
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Wang N, De Bock M, Decrock E, Bol M, Gadicherla A, Vinken M, Rogiers V, Bukauskas FF, Bultynck G, Leybaert L. Paracrine signaling through plasma membrane hemichannels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1828:35-50. [PMID: 22796188 DOI: 10.1016/j.bbamem.2012.07.002] [Citation(s) in RCA: 157] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 06/29/2012] [Accepted: 07/06/2012] [Indexed: 12/24/2022]
Abstract
Plasma membrane hemichannels composed of connexin (Cx) proteins are essential components of gap junction channels but accumulating evidence suggests functions of hemichannels beyond the communication provided by junctional channels. Hemichannels not incorporated into gap junctions, called unapposed hemichannels, can open in response to a variety of signals, electrical and chemical, thereby forming a conduit between the cell's interior and the extracellular milieu. Open hemichannels allow the bidirectional passage of ions and small metabolic or signaling molecules of below 1-2kDa molecular weight. In addition to connexins, hemichannels can also be formed by pannexin (Panx) proteins and current evidence suggests that Cx26, Cx32, Cx36, Cx43 and Panx1, form hemichannels that allow the diffusive release of paracrine messengers. In particular, the case is strong for ATP but substantial evidence is also available for other messengers like glutamate and prostaglandins or metabolic substances like NAD(+) or glutathione. While this field is clearly in expansion, evidence is still lacking at essential points of the paracrine signaling cascade that includes not only messenger release, but also downstream receptor signaling and consequent functional effects. The data available at this moment largely derives from in vitro experiments and still suffers from the difficulty of separating the functions of connexin-based hemichannels from gap junctions and from pannexin hemichannels. However, messengers like ATP or glutamate have universal roles in the body and further defining the contribution of hemichannels as a possible release pathway is expected to open novel avenues for better understanding their contribution to a variety of physiological and pathological processes. This article is part of a Special Issue entitled: The Communicating junctions, roles and dysfunctions.
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Affiliation(s)
- Nan Wang
- Department of Basic Medical Sciences, Ghent University, Ghent, Belgium
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Theis M, Giaume C. Connexin-based intercellular communication and astrocyte heterogeneity. Brain Res 2012; 1487:88-98. [PMID: 22789907 DOI: 10.1016/j.brainres.2012.06.045] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 06/10/2012] [Accepted: 06/13/2012] [Indexed: 12/21/2022]
Abstract
This review gives an overview of the current knowledge on connexin-mediated communication in astrocytes, covering gap junction and hemichannel functions mediated by connexins. Astroglia is the main brain cell type that expresses the largest amount of connexin and exhibits high level of gap junctional communication compared to neurons and oligodendrocytes. However, in certain developmental and regional situations, astrocytes are also coupled with oligodendrocytes and neurons. This heterotypic coupling is infrequent and minor in terms of extent of the coupling area, which does not mean that it is not important in terms of cell interaction. Here, we present an update on heterogeneity of connexin expression and function at the molecular, subcellular, cellular and networking levels. Interestingly, while astrocytes were initially considered as a homogenous population, there is now increasing evidence for morphological, developmental, molecular and physiological heterogeneity of astrocytes. Consequently, the specificity of gap junction channel- and hemichannel-mediated communication, which tends to synchronize cell populations, is also a parameter to take into account when neuroglial interactions are investigated. This article is part of a Special Issue entitled Electrical Synapses.
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Affiliation(s)
- Martin Theis
- Institute of Cellular Neurosciences, Medical Faculty, University of Bonn, Sigmund-Freud-Straße 25, D-53105 Bonn, Germany.
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Markoullis K, Sargiannidou I, Gardner C, Hadjisavvas A, Reynolds R, Kleopa KA. Disruption of oligodendrocyte gap junctions in experimental autoimmune encephalomyelitis. Glia 2012; 60:1053-66. [PMID: 22461072 DOI: 10.1002/glia.22334] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 03/05/2012] [Indexed: 12/16/2023]
Abstract
Gap junctions (GJs) are vital for oligodendrocyte survival and myelination. In order to examine how different stages of inflammatory demyelination affect oligodendrocyte GJs, we studied the expression of oligodendrocytic connexin32 (Cx32) and Cx47 and astrocytic Cx43 in the experimental autoimmune encephalomyelitis (EAE) mouse model of multiple sclerosis (MS) induced by recombinant myelin oligodendrocyte glycoprotein. EAE was characterized by remissions and relapses with demyelination and axonal loss. Formation of GJ plaques was quantified in relation to the lesions and in normal appearing white matter (NAWM). During acute EAE at 14 days postimmunization (dpi) both Cx47 and Cx32 GJs were severely reduced within and around lesions but also in the NAWM. Cx47 was localized intracellularly in oligodendrocytes while protein levels remained unchanged, and this redistribution coincided with the loss of Cx43 GJs in astrocytes. Cx47 and Cx32 expression increased during remyelination at 28 dpi but decreased again at 50 dpi in the relapsing phase. Oligodendrocyte GJs remained reduced even in NAWM, despite increased formation of Cx43 GJs toward lesions indicating astrogliosis. EAE induced in Cx32 knockout mice resulted in an exacerbated clinical course with more demyelination and axonal loss compared with wild-type EAE mice of the same backcross, despite similar degree of inflammation, and an overall milder loss of Cx47 and Cx43 GJs. Thus, EAE causes persistent impairment of both intra- and intercellular oligodendrocyte GJs even in the NAWM, which may be an important mechanism of MS progression. Furthermore, GJ deficient myelinated fibers appear more vulnerable to CNS inflammatory demyelination.
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Affiliation(s)
- Kyriaki Markoullis
- Neuroscience Laboratory, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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119
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IL-1RI (interleukin-1 receptor type I) signalling is essential for host defence and hemichannel activity during acute central nervous system bacterial infection. ASN Neuro 2012; 4:AN20120008. [PMID: 22414156 PMCID: PMC3328864 DOI: 10.1042/an20120008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Staphylococcus aureus is a common aetiological agent of bacterial brain abscesses. We have previously established that a considerable IL-1 (interleukin-1) response is elicited immediately following S. aureus infection, where the cytokine can exert pleiotropic effects on glial activation and blood–brain barrier permeability. To assess the combined actions of IL-1α and IL-1β during CNS (central nervous system) infection, host defence responses were evaluated in IL-1RI (IL-1 receptor type I) KO (knockout) animals. IL-1RI KO mice were exquisitely sensitive to intracerebral S. aureus infection, as demonstrated by enhanced mortality rates and bacterial burdens within the first 24 h following pathogen exposure compared with WT (wild-type) animals. Loss of IL-1RI signalling also dampened the expression of select cytokines and chemokines, concomitant with significant reductions in neutrophil and macrophage infiltrates into the brain. In addition, the opening of astrocyte hemichannels during acute infection was shown to be dependent on IL-1RI activity. Collectively, these results demonstrate that IL-1RI signalling plays a pivotal role in the genesis of immune responses during the acute stage of brain abscess development through S. aureus containment, inflammatory mediator production, peripheral immune cell recruitment, and regulation of astrocyte hemichannel activity. Taken in the context of previous studies with MyD88 (myeloid differentiation primary response gene 88) and TLR2 (Toll-like receptor 2) KO animals, the current report advances our understanding of MyD88-dependent cascades and implicates IL-1RI signalling as a major antimicrobial effector pathway during acute brain-abscess formation.
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Karpuk N, Burkovetskaya M, Kielian T. Neuroinflammation alters voltage-dependent conductance in striatal astrocytes. J Neurophysiol 2012; 108:112-23. [PMID: 22457466 DOI: 10.1152/jn.01182.2011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neuroinflammation has the capacity to alter normal central nervous system (CNS) homeostasis and function. The objective of the present study was to examine the effects of an inflammatory milieu on the electrophysiological properties of striatal astrocyte subpopulations with a mouse bacterial brain abscess model. Whole cell patch-clamp recordings were performed in striatal glial fibrillary acidic protein (GFAP)-green fluorescent protein (GFP)(+) astrocytes neighboring abscesses at postinfection days 3 or 7 in adult mice. Cell input conductance (G(i)) measurements spanning a membrane potential (V(m)) surrounding resting membrane potential (RMP) revealed two prevalent astrocyte subsets. A1 and A2 astrocytes were identified by negative and positive G(i) increments vs. V(m), respectively. A1 and A2 astrocytes displayed significantly different RMP, G(i), and cell membrane capacitance that were influenced by both time after bacterial exposure and astrocyte proximity to the inflammatory site. Specifically, the percentage of A1 astrocytes was decreased immediately surrounding the inflammatory lesion, whereas A2 cells were increased. These changes were particularly evident at postinfection day 7, revealing increased cell numbers with an outward current component. Furthermore, RMP was inversely modified in A1 and A2 astrocytes during neuroinflammation, and resting G(i) was increased from 21 to 30 nS in the latter. In contrast, gap junction communication was significantly decreased in all astrocyte populations associated with inflamed tissues. Collectively, these findings demonstrate the heterogeneity of striatal astrocyte populations, which experience distinct electrophysiological modifications in response to CNS inflammation.
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Affiliation(s)
- Nikolay Karpuk
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198-5900, USA
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Abbasian M, Sayyah M, Babapour V, Mahdian R, Choopani S, Kaviani B. Upregulation of connexins 30 and 32 gap junctions in rat hippocampus at transcription level by chronic central injection of lipopolysaccharide. IRANIAN BIOMEDICAL JOURNAL 2012; 16:127-32. [PMID: 23023213 PMCID: PMC3629930 DOI: 10.6091/ibj.1099.2012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Revised: 06/23/2012] [Accepted: 06/26/2012] [Indexed: 11/17/2022]
Abstract
BACKGROUND Gap junctions composed of connexins (Cx) are functional in cell defense by propagation of toxic/death molecules to neighboring cells. Hippocampus, one of the brain regions with particular vulnerability to damage, has a wide network of gap junctions. Functional response of astrocytic Cx30 and neuronal Cx32 to hippocampal damage is unknown. METHODS We infused lipopolysaccharide (LPS) intracerebroventricularly (2.5 mug/rat) once daily for two weeks to create neuroinflammation. The mRNA and protein levels of the Cx were measured in the hippocampus after 1st, 7th and 14th injection by real-time PCR and Western-blot techniques. RESULTS A significant increase in Cx32 and Cx30 gene expression was observed after 7th and 14th injection of LPS with no significant change in their protein abundance. CONCLUSION Transcriptional overexpression of hippocampal Cx30 and Cx32 could be an adaptive response to production of intracellular toxic molecules but it is not accompanied with post- transcriptional overexpression and might have no functional impact.
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Affiliation(s)
- Mohammad Abbasian
- Dept. of Physiology, Faculty of Veterinary Medicine, Science and Research Branch, Islamic Azad University, Tehran;
- Dept. of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran;
| | - Mohammad Sayyah
- Dept. of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran;
| | - Vahab Babapour
- Dept. of Physiology, Faculty of Veterinary Medicine, Tehran University, Tehran;
| | - Reza Mahdian
- Biotechnology Research Center, Dept. of Molecular Medicine, Pasteur Institute of Iran, Tehran, Iran
| | - Samira Choopani
- Dept. of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran;
| | - Bahar Kaviani
- Dept. of Physiology and Pharmacology, Pasteur Institute of Iran, Tehran;
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Sayyah M, Kaviani B, Khoshkholgh-Sima B, Bagheri M, Olad M, Choopani S, Mahdian R. Effect of chronic intracerebroventricluar administration of lipopolysaccharide on connexin43 protein expression in rat hippocampus. IRANIAN BIOMEDICAL JOURNAL 2012; 16:25-32. [PMID: 22562029 PMCID: PMC3614252 DOI: 10.6091/ibj.1030.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Revised: 10/22/2011] [Accepted: 10/23/2011] [Indexed: 12/22/2022]
Abstract
BACKGROUND Hippocampal damages, which are accompanied by inflammation, are among the main causes of epilepsy acquisition. We previously reported that chronic intracerebroventricular (i.c.v.) injection of lipopolysaccharide (LPS) modulates epileptogenesis in rats. There is a network of gap junction channels in the hippocampus that contribute to epileptogenesis. Gap junction channels are formed by oligomeric protein subunits called connexins (Cx). Astrocytic Cx43 and neuronal Cx36 are expressed in the hippocampus. In order to find out the possible role of gap junctions in seizure-modulating effect of LPS and neuroinflammation, we studied the effect of central administration of LPS on expression of Cx36 and Cx43 in rat hippocampus. METHODS LPS, 2.5 mug/rat/day, was injected i.c.v. to male Wistar rats for 14 days. mRNA and protein abundance of Cx36, Cx43 and IL1-β were measured in rat hippocampus by real time-PCR, Western blot and ELISA techniques, at the beginning, in the middle, and at the end of the treatment period. RESULTS IL1-β protein level was significantly increased 6 h after first injection of LPS. Cx36 and Cx43 mRNA expression did not alter during chronic administration of LPS. A selective decrease in Cx43 protein expression was observed after 7 injections of LPS. CONCLUSION It is suggested that Cx43 containing gap junctions in the hippocampus is down-regulated in response to chronic injection of LPS. This event can inhibit propagation of toxic and noxious molecules to neighboring cells and modulate hippocampal excitability and epileptogenesis.
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Affiliation(s)
- Mohammad Sayyah
- Dept. of Physiology and Pharmacology, the Pasteur Institute of Iran, Tehran, Iran.
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Glial connexin expression and function in the context of Alzheimer's disease. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1818:2048-57. [PMID: 22008509 DOI: 10.1016/j.bbamem.2011.10.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Revised: 09/20/2011] [Accepted: 10/03/2011] [Indexed: 01/26/2023]
Abstract
A hallmark of neurodegenerative diseases is the reactive gliosis characterized by a phenotypic change in astrocytes and microglia. This glial response is associated with modifications in the expression and function of connexins (Cxs), the proteins forming gap junction channels and hemichannels. Increased Cx expression is detected in most reactive astrocytes located at amyloid plaques, the histopathological lesions typically present in the brain of Alzheimer's patients and animal models of the disease. The activity of Cx channels analyzed in vivo as well as in vitro after treatment with the amyloid β peptide is also modified and, in particular, hemichannel activation may contribute to neuronal damage. In this review, we summarize and discuss recent data that suggest glial Cx channels participate in the neurodegenerative process of Alzheimer's disease. This article is part of a Special Issue entitled: The Communicating junctions, composition, structure and characteristics.
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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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Ceelen L, Haesebrouck F, Vanhaecke T, Rogiers V, Vinken M. Modulation of connexin signaling by bacterial pathogens and their toxins. Cell Mol Life Sci 2011; 68:3047-64. [PMID: 21656255 PMCID: PMC11115019 DOI: 10.1007/s00018-011-0737-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Revised: 05/12/2011] [Accepted: 05/17/2011] [Indexed: 02/07/2023]
Abstract
Inherent to their pivotal tasks in the maintenance of cellular homeostasis, gap junctions, connexin hemichannels, and pannexin hemichannels are frequently involved in the dysregulation of this critical balance. The present paper specifically focuses on their roles in bacterial infection and disease. In particular, the reported biological outcome of clinically important bacteria including Escherichia coli, Shigella flexneri, Yersinia enterocolitica, Helicobacter pylori, Bordetella pertussis, Aggregatibacter actinomycetemcomitans, Pseudomonas aeruginosa, Citrobacter rodentium, Clostridium species, Streptococcus pneumoniae, and Staphylococcus aureus and their toxic products on connexin- and pannexin-related signaling in host cells is reviewed. Particular attention is paid to the underlying molecular mechanisms of these effects as well as to the actual biological relevance of these findings.
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Affiliation(s)
- Liesbeth Ceelen
- Department of Toxicology, Centre for Pharmaceutical Research, Faculty of Medicine and Pharmacy, Vrije Universiteit Brussel, Laarbeeklaan 103, 1090 Brussels, Belgium.
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Johansen D, Cruciani V, Sundset R, Ytrehus K, Mikalsen SO. Ischemia Induces Closure of Gap Junctional Channels and Opening of Hemichannels in Heart-derived Cells and Tissue. Cell Physiol Biochem 2011; 28:103-14. [DOI: 10.1159/000331719] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2011] [Indexed: 12/20/2022] Open
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