2701
|
Abstract
Activity-dependent release of ATP from synapses, axons and glia activates purinergic membrane receptors that modulate intracellular calcium and cyclic AMP. This enables glia to detect neural activity and communicate among other glial cells by releasing ATP through membrane channels and vesicles. Through purinergic signalling, impulse activity regulates glial proliferation, motility, survival, differentiation and myelination, and facilitates interactions between neurons, and vascular and immune system cells. Interactions among purinergic, growth factor and cytokine signalling regulate synaptic strength, development and responses to injury. We review the involvement of ATP and adenosine receptors in neuron-glia signalling, including the release and hydrolysis of ATP, how the receptors signal, the pharmacological tools used to study them, and their functional significance.
Collapse
Affiliation(s)
- R Douglas Fields
- National Institute of Child Health and Human Development, National Institutes of Health, Building 35, Room 2A211, MSC 3713, 35 Lincoln Drive, Bethesda, Maryland 20892, USA.
| | | |
Collapse
|
2702
|
Robson SC, Sévigny J, Zimmermann H. The E-NTPDase family of ectonucleotidases: Structure function relationships and pathophysiological significance. Purinergic Signal 2006; 2:409-30. [PMID: 18404480 PMCID: PMC2254478 DOI: 10.1007/s11302-006-9003-5] [Citation(s) in RCA: 712] [Impact Index Per Article: 39.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 01/23/2006] [Indexed: 12/17/2022] Open
Abstract
Ectonucleotidases are ectoenzymes that hydrolyze extracellular nucleotides to the respective nucleosides. Within the past decade, ectonucleotidases belonging to several enzyme families have been discovered, cloned and characterized. In this article, we specifically address the cell surface-located members of the ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase/CD39) family (NTPDase1,2,3, and 8). The molecular identification of individual NTPDase subtypes, genetic engineering, mutational analyses, and the generation of subtype-specific antibodies have resulted in considerable insights into enzyme structure and function. These advances also allow definition of physiological and patho-physiological implications of NTPDases in a considerable variety of tissues. Biological actions of NTPDases are a consequence (at least in part) of the regulated phosphohydrolytic activity on extracellular nucleotides and consequent effects on P2-receptor signaling. It further appears that the spatial and temporal expression of NTPDases by various cell types within the vasculature, the nervous tissues and other tissues impacts on several patho-physiological processes. Examples include acute effects on cellular metabolism, adhesion, activation and migration with other protracted impacts upon developmental responses, inclusive of cellular proliferation, differentiation and apoptosis, as seen with atherosclerosis, degenerative neurological diseases and immune rejection of transplanted organs and cells. Future clinical applications are expected to involve the development of new therapeutic strategies for transplantation and various inflammatory cardiovascular, gastrointestinal and neurological diseases.
Collapse
Affiliation(s)
- Simon C. Robson
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts USA
| | - Jean Sévigny
- Centre de Recherche en Rhumatologie et Immunologie, Université Laval, Québec, Québec Canada
| | - Herbert Zimmermann
- Institut fuer Zellbiologie und Neurowissenschaft, Biozentrum der J.W. Goethe-Universitaet, Marie-Curie-Str. 9, D-60439 Frankfurt am Main, Germany
| |
Collapse
|
2703
|
Abstract
The brain is complex and dynamic. The spatial scales of interest to the neurobiologist range from individual synapses (approximately 1 microm) to neural circuits (centimeters); the timescales range from the flickering of channels (less than a millisecond) to long-term memory (years). Remarkably, fluorescence microscopy has the potential to revolutionize research on all of these spatial and temporal scales. Two-photon excitation (2PE) laser scanning microscopy allows high-resolution and high-sensitivity fluorescence microscopy in intact neural tissue, which is hostile to traditional forms of microscopy. Over the last 10 years, applications of 2PE, including microscopy and photostimulation, have contributed to our understanding of a broad array of neurobiological phenomena, including the dynamics of single channels in individual synapses and the functional organization of cortical maps. Here we review the principles of 2PE microscopy, highlight recent applications, discuss its limitations, and point to areas for future research and development.
Collapse
Affiliation(s)
- Karel Svoboda
- HHMI, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
| | | |
Collapse
|
2704
|
Wilkinson B, Koenigsknecht-Talboo J, Grommes C, Lee CYD, Landreth G. Fibrillar beta-amyloid-stimulated intracellular signaling cascades require Vav for induction of respiratory burst and phagocytosis in monocytes and microglia. J Biol Chem 2006; 281:20842-20850. [PMID: 16728400 DOI: 10.1074/jbc.m600627200] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microglial interaction with extracellular beta-amyloid fibrils (fAbeta) is mediated through an ensemble of cell surface receptors, including the B-class scavenger receptor CD36, the alpha(6)beta(1)-integrin, and the integrin-associated protein/CD47. The binding of fAbeta to this receptor complex has been shown to drive a tyrosine kinase-based signaling cascade leading to production of reactive oxygen species and stimulation of phagocytic activity; however, little is known about the intracellular signaling cascades governing the microglial response to fAbeta. This study reports a direct mechanistic link between the fAbeta cell surface receptor complex and downstream signaling events responsible for NADPH oxidase activation and phagosome formation. The Vav guanine nucleotide exchange factor is tyrosine-phosphorylated in response to fAbeta peptides as a result of the engagement of the microglia fAbeta cell surface receptor complex. Co-immunoprecipitation studies demonstrate an Abeta-dependent association between Vav and both Lyn and Syk kinases. The downstream target of Vav, the small GTPase Rac1, is GTP-loaded in an Abeta-dependent manner. Rac1 is both an essential component of the NADPH oxidase and a critical regulator of microglial phagocytosis. The direct role of Vav in fAbeta-stimulated intracellular signaling cascades was established using primary microglia obtained from Vav(-/-) mice. Stimulation of Vav(-/-) microglia with fAbeta failed to generate NADPH oxidase-derived reactive oxygen species and displayed a dramatically attenuated phagocytic response. These findings directly link Vav phosphorylation to the Abeta-receptor complex and demonstrate that Vav activity is required for fAbeta-stimulated intracellular signaling events upstream of reactive oxygen species production and phagosome formation.
Collapse
Affiliation(s)
- Brandy Wilkinson
- Alzheimer Research Laboratory, Department of Neuroscience, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106.
| | - Jessica Koenigsknecht-Talboo
- Alzheimer Research Laboratory, Department of Neuroscience, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Christian Grommes
- Alzheimer Research Laboratory, Department of Neuroscience, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - C Y Daniel Lee
- Alzheimer Research Laboratory, Department of Neuroscience, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Gary Landreth
- Alzheimer Research Laboratory, Department of Neuroscience, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| |
Collapse
|
2705
|
Rappold PM, Lynd-Balta E, Joseph SA. P2X7 receptor immunoreactive profile confined to resting and activated microglia in the epileptic brain. Brain Res 2006; 1089:171-8. [PMID: 16635480 DOI: 10.1016/j.brainres.2006.03.040] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2005] [Revised: 02/24/2006] [Accepted: 03/01/2006] [Indexed: 11/19/2022]
Abstract
The purpose of this study was to identify the CNS cellular constituent immunoreactive for specific P2X7 receptor antiserum in the kainate-induced seizure and non-seizure rat brain. Analysis of P2X7 immunocytochemistry (ICC) revealed small immunoreactive cells with processes showing distinct morphological changes as seizures progressed in time. These morphological changes were reminiscent of reactive glia during CNS injury. In order to determine the identity of this non-neuronal cellular constituent, we employed dual ICC techniques using sequential antibody incubations and reacted the sections with contrasting chromagens. Specific glial markers tested in the series included Iba1 (microglia), COX-1 (microglia), and GFAP (astroglia). Results of this study revealed distinct colocalization when sections immunostained for P2X7 were dual immunostained with antisera specific for microglia (Iba1, COX-1). In contrast, no colocalization was evident when sections were dual immunostained with P2X7 and GFAP, an astrocytic marker. In the latter experiment, dual ICC revealed two distinct cell populations with contrasting color demonstrating a population of distinct GFAP immunopositive cells and a population of distinct P2X7 immunopositive cells. We conclude that P2X7 antiserum used in this study is specific for and identifies microglia in rat and that there exists a timeline of progressive changes in microglia morphology that can be demonstrated following kainate-induced seizures. In addition, the morphological changes in microglia following seizure induction that can be identified with P2X7 antisera or with antisera specific for microglia suggest a neuroinflammatory milieu in areas of CNS seizure activity.
Collapse
Affiliation(s)
- P M Rappold
- Department of Neurosurgery, Box 670, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | | | | |
Collapse
|
2706
|
Franke H, Krügel U, Illes P. P2 receptors and neuronal injury. Pflugers Arch 2006; 452:622-44. [PMID: 16645849 DOI: 10.1007/s00424-006-0071-8] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2006] [Accepted: 03/09/2006] [Indexed: 02/08/2023]
Abstract
Extracellular adenosine 5'-triphosphate (ATP) was proposed to be an activity-dependent signaling molecule that regulates glia-glia and glia-neuron communications. ATP is a neurotransmitter of its own right and, in addition, a cotransmitter of other classical transmitters such as glutamate or GABA. The effects of ATP are mediated by two receptor families belonging either to the P2X (ligand-gated cationic channels) or P2Y (G protein-coupled receptors) types. P2X receptors are responsible for rapid synaptic responses, whereas P2Y receptors mediate slow synaptic responses and other types of purinergic signaling involved in neuronal damage/regeneration. ATP may act at pre- and postsynaptic sites and therefore, it may participate in the phenomena of long-term potentiation and long-term depression of excitatory synaptic transmission. The release of ATP into the extracellular space, e.g., by exocytosis, membrane transporters, and connexin hemichannels, is a widespread physiological process. However, ATP may also leave cells through their plasma membrane damaged by inflammation, ischemia, and mechanical injury. Functional responses to the activation of multiple P2 receptors were found in neurons and glial cells under normal and pathophysiological conditions. P2 receptor-activation could either be a cause or a consequence of neuronal cell death/glial activation and may be related to detrimental and/or beneficial effects. The present review aims at demonstrating that purinergic mechanisms correlate with the etiopathology of brain insults, especially because of the massive extracellular release of ATP, adenosine, and other neurotransmitters after brain injury. We will focus in this review on the most important P2 receptor-mediated neurodegenerative and neuroprotective processes and their beneficial modulation by possible therapeutic manipulations.
Collapse
Affiliation(s)
- Heike Franke
- Rudolf-Boehm Institute of Pharmacology and Toxicology, University of Leipzig, Härtelstrasse 16-18, 04107, Leipzig, Germany.
| | | | | |
Collapse
|
2707
|
Zimmermann H. Nucleotide signaling in nervous system development. Pflugers Arch 2006; 452:573-88. [PMID: 16639549 DOI: 10.1007/s00424-006-0067-4] [Citation(s) in RCA: 135] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2006] [Accepted: 03/06/2006] [Indexed: 11/24/2022]
Abstract
The development of the nervous system requires complex series of cellular programming and intercellular communication events that lead from the early neural induction to the formation of a highly structured central and peripheral nervous system. Neurogenesis continuously takes place also in select regions of the adult mammalian brain. During the past years, a multiplicity of cellular control mechanisms has been identified, ranging from differential transcriptional mediators to inducers or inhibitors of cell specification or neurite outgrowth. While the identification of transcription factors typical for the stage-specific progression has been a topic of key interest for many years, less is known concerning the potential multiplicity of relevant intercellular signaling pathways and the fine tuning of epigenetic gene regulation. Nucleotide receptors can induce a multiplicity of cellular signaling pathways and are involved in multiple molecular interactions, thus opening the possibility of cross talk between several signaling pathways, including growth factors, cytokines, and extracellular matrix components. An increasing number of studies provides evidence for a role of nucleotide signaling in nervous system development. This includes progenitor cell proliferation, cell migration, neuronal and glial cellular interaction and differentiation, and synaptic network formation.
Collapse
Affiliation(s)
- Herbert Zimmermann
- Institut fuer Zellbiologie und Neurowissenschaft, Biozentrum der J.W. Goethe-Universitaet, Max-von-Lane-Str. 9, 60438, Frankfurt am Main, Germany.
| |
Collapse
|
2708
|
Trang T, Beggs S, Salter MW. Purinoceptors in microglia and neuropathic pain. Pflugers Arch 2006; 452:645-52. [PMID: 16767466 DOI: 10.1007/s00424-006-0074-5] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2006] [Accepted: 03/10/2006] [Indexed: 01/23/2023]
Abstract
Emerging evidence indicates that microglia play a critical role in the pathogenesis of neuropathic pain, a debilitating chronic pain condition that can occur after peripheral nerve damage caused by disease, infection, or physical injury. Microglia are immunocompetent cells of the central nervous system and express various ionotropic P2X and metabotropic P2Y purinoceptors. After injury to a peripheral nerve, microglia in the spinal cord become activated and upregulate expression of the P2X4 receptor. Recent findings suggest that activation of P2X4 receptors evokes release of brain-derived neurotrophic factor from microglia and that this mediates microglia-neuron signaling leading to pain hypersensitivity. Thus, P2X4 receptors and the intracellular signaling mediators in microglia are promising therapeutic targets for the development of novel pharmacological agents in the management of neuropathic pain.
Collapse
Affiliation(s)
- Tuan Trang
- University of Toronto Centre for the Study of Pain, Programmes in Brain and Behaviour and Cell Biology, Hospital for Sick Children, Toronto, Ontario, M5G 1X8, Canada
| | | | | |
Collapse
|
2709
|
Abstract
The concept of a purinergic signaling system, using purine nucleotides and nucleosides as extracellular messengers, was first proposed over 30 years ago. After a brief introduction and update of purinoceptor subtypes, this article focuses on the diverse pathophysiological roles of purines and pyrimidines as signaling molecules. These molecules mediate short-term (acute) signaling functions in neurotransmission, mechanosensory transduction, secretion and vasodilatation, and long-term (chronic) signaling functions in cell proliferation, differentiation, and death involved in development and regeneration. Plasticity of purinoceptor expression in pathological conditions is frequently observed, including an increase in the purinergic component of autonomic cotransmission. Recent advances in therapies using purinergic-related drugs in a wide range of pathological conditions will be addressed with speculation on future developments in the field.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, London NW3 2PF, UK.
| |
Collapse
|
2710
|
Belmadani A, Tran PB, Ren D, Miller RJ. Chemokines regulate the migration of neural progenitors to sites of neuroinflammation. J Neurosci 2006; 26:3182-91. [PMID: 16554469 PMCID: PMC2740990 DOI: 10.1523/jneurosci.0156-06.2006] [Citation(s) in RCA: 245] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Many studies have shown that transplanted or endogenous neural progenitor cells will migrate toward damaged areas of the brain. However, the mechanism underlying this effect is not clear. Here we report that, using hippocampal slice cultures, grafted neural progenitor cells (NPs) migrate toward areas of neuroinflammation and that chemokines are a major regulator of this process. Migration of NPs was observed after injecting an inflammatory stimulus into the area of the fimbria and transplanting enhanced green fluorescent protein (EGFP)-labeled NPs into the dentate gyrus of cultured hippocampal slices. Three to 7 d after transplantation, EGFP-NPs in control slices showed little tendency to migrate and had differentiated into neurons and glia. In contrast, in slices injected with inflammatory stimuli, EGFP-NPs migrated toward the site of the injection. NPs in these slices also survived less well. The inflammatory stimuli used were a combination of the cytokines tumor necrosis factor-alpha and interferon-gamma, the bacterial toxin lipopolysaccharide, the human immunodeficiency virus-1 coat protein glycoprotein 120, or a beta-amyloid-expressing adenovirus. We showed that these inflammatory stimuli increased the synthesis of numerous chemokines and cytokines by hippocampal slices. When EGFP-NPs from CC chemokine receptor CCR2 knock-out mice were transplanted into slices, they exhibited little migration toward sites of inflammation. Similarly, wild-type EGFP-NPs exhibited little migration toward inflammatory sites when transplanted into slices prepared from monocyte chemoattractant protein-1 (MCP-1) knock-out mice. These data indicate that factors secreted by sites of neuroinflammation are attractive to neural progenitors and suggest that chemokines such as MCP-1 play an important role in this process.
Collapse
|
2711
|
Xiang Z, Chen M, Ping J, Dunn P, Lv J, Jiao B, Burnstock G. Microglial morphology and its transformation after challenge by extracellular ATP in vitro. J Neurosci Res 2006; 83:91-101. [PMID: 16323207 DOI: 10.1002/jnr.20709] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The novel morphological characteristics of N9 microglial cells and primary cultured rat microglial cells were examined using the bitotin-IB4 and streptavidin-FITC system. Numerous fine, long processes of both microglial cell preparations formed a network, beginning after 30 min in culture. Dye coupling studies did not show communication between neighbouring cells via the processes in normal conditions. The network of microglial cell processes was well formed into a 'resting state' by 16-24 hr after re-plating. After being challenged by 3 mM ATP the microglial cells were activated, became amoeboid-like cells within 2 hr and finally floated in the culture medium. The complicated network of processes did not retract to the microglial cell body. Flow cytometry analysis showed that the majority of these floating cells were alive and could recover to the resting state after ATP was removed from the culture medium.
Collapse
Affiliation(s)
- Zhenghua Xiang
- Department of Biochemistry and Molecular Biology, Second Military Medical University Shanghai, People's Republic of China
| | | | | | | | | | | | | |
Collapse
|
2712
|
Microglia Biology in Health and Disease. J Neuroimmune Pharmacol 2006; 1:127-37. [DOI: 10.1007/s11481-006-9015-5] [Citation(s) in RCA: 343] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2005] [Accepted: 02/15/2006] [Indexed: 12/21/2022]
|
2713
|
Butovsky O, Landa G, Kunis G, Ziv Y, Avidan H, Greenberg N, Schwartz A, Smirnov I, Pollack A, Jung S, Schwartz M. Induction and blockage of oligodendrogenesis by differently activated microglia in an animal model of multiple sclerosis. J Clin Invest 2006; 116:905-15. [PMID: 16557302 PMCID: PMC1409740 DOI: 10.1172/jci26836] [Citation(s) in RCA: 189] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Accepted: 02/07/2006] [Indexed: 11/17/2022] Open
Abstract
The role of activated microglia (MG) in demyelinating neurodegenerative diseases such as multiple sclerosis is controversial. Here we show that high, but not low, levels of IFN-gamma (a cytokine associated with inflammatory autoimmune diseases) conferred on rodent MG a phenotype that impeded oligodendrogenesis from adult neural stem/progenitor cells. IL-4 reversed the impediment, attenuated TNF-alpha production, and overcame blockage of IGF-I production caused by IFN-gamma. In rodents with acute or chronic EAE, injection of IL-4-activated MG into the cerebrospinal fluid resulted in increased oligodendrogenesis in the spinal cord and improved clinical symptoms. The newly formed oligodendrocytes were spatially associated with MG expressing MHC class II proteins and IGF-I. These results point to what we believe to be a novel role for MG in oligodendrogenesis from the endogenous stem cell pool.
Collapse
Affiliation(s)
- Oleg Butovsky
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Gennady Landa
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Gilad Kunis
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Yaniv Ziv
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Hila Avidan
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Nadav Greenberg
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Adi Schwartz
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Igor Smirnov
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Ayala Pollack
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Steffen Jung
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| | - Michal Schwartz
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel.
Kaplan Medical Center, Rehovot, Israel.
Proneuron Biotechnologies, Ness Ziona, Israel.
Department of Immunology, Weizmann Institute of Science, Rehovot, Israel
| |
Collapse
|
2714
|
Abstract
Microglia are the resident immune cells of the brain, and they are under permanent activity to patrol the cerebral microenvironment. A proper inhibitory feedback onto these cells is critical during both intact and injury conditions. In this issue of Neuron, Eljaschewitsch and colleagues report that such feedback is provided by the endogenous cannabinoid anandamine and CB(1/2) receptor signaling, which ultimately leads to mitogen-activated protein kinase phosphatase-1 (MKP-1) induction. MKP-1 interferes with lipopolysaccharide-induced toll-like receptor 4 signaling and limits brain damage due to exaggerated microglial reactivity following acute NMDA injury.
Collapse
Affiliation(s)
- Serge Rivest
- Laboratory of Molecular Endocrinology, CHUL Research Center, and Department of Anatomy and Physiology, Laval University, Québec, Canada G1V-4G2
| |
Collapse
|
2715
|
Freeman MR. Sculpting the nervous system: glial control of neuronal development. Curr Opin Neurobiol 2006; 16:119-25. [PMID: 16387489 DOI: 10.1016/j.conb.2005.12.004] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2005] [Accepted: 12/16/2005] [Indexed: 11/26/2022]
Abstract
Glial cells are not passive spectators during nervous system assembly, rather they are active participants that exert significant control over neuronal development. Well-established roles for glia in shaping the developing nervous system include providing trophic support to neurons, modulating axon pathfinding, and driving nerve fasciculation. Exciting recent studies have revealed additional ways in which glial cells also modulate neurodevelopment. Glial cells regulate the number of neurons at early developmental stages by dynamically influencing neural precursor divisions, and at later stages by promoting neuronal cell death through engulfment. Glia also participate in the fine sculpting of neuronal connections by pruning excess axonal projections, shaping dendritic spines, and secreting multiple factors that promote synapse formation and functional maturation. These recent insights provide further compelling evidence that glial cells, through their diverse cellular actions, are essential contributors to the construction of a functionally mature nervous system.
Collapse
Affiliation(s)
- Marc R Freeman
- Department of Neurobiology, University of Massachusetts Medical School, Worcester, MA 01605-2324, USA.
| |
Collapse
|
2716
|
Noda M, Kettenmann H, Wada K. Anti-inflammatory effects of kinins via microglia in the central nervous system. Biol Chem 2006; 387:167-71. [PMID: 16497148 DOI: 10.1515/bc.2006.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Abstract
Kinins are important biologically active peptides that are up-regulated after lesions in both the peripheral and central (CNS) nervous systems. Microglia are immune cells in the CNS and play an important role in the defense of the neuronal parenchyma. In cultured murine microglia, bradykinin (BK) induces mobilization of intracellular Ca2+, microglial migration, and increases the release of nitric oxide and prostaglandin E2. On the other hand, BK attenuates lipopolysaccharide-activated TNF-α and IL-1β release. These results suggest that BK functions as a signal in brain trauma and may have an anti-inflammatory role in the CNS.
Collapse
Affiliation(s)
- Mami Noda
- Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka 812-8582, Japan.
| | | | | |
Collapse
|
2717
|
Abstract
With few exceptions biological tissues strongly scatter light, making high-resolution deep imaging impossible for traditional-including confocal-fluorescence microscopy. Nonlinear optical microscopy, in particular two photon-excited fluorescence microscopy, has overcome this limitation, providing large depth penetration mainly because even multiply scattered signal photons can be assigned to their origin as the result of localized nonlinear signal generation. Two-photon microscopy thus allows cellular imaging several hundred microns deep in various organs of living animals. Here we review fundamental concepts of nonlinear microscopy and discuss conditions relevant for achieving large imaging depths in intact tissue.
Collapse
Affiliation(s)
- Fritjof Helmchen
- Department of Neurophysiology, Brain Research Institute, University of Zurich, CH-8057 Zurich, Switzerland.
| | | |
Collapse
|
2718
|
Garção P, Oliveira CR, Agostinho P. Comparative study of microglia activation induced by amyloid-beta and prion peptides: Role in neurodegeneration. J Neurosci Res 2006; 84:182-93. [PMID: 16634056 DOI: 10.1002/jnr.20870] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The inflammatory responses in Alzheimer's disease (AD) and prion-related encephalopathies (PRE) are dominated by microglia activation. Several studies have reported that the amyloid-beta (Abeta) peptides, which are associated with AD, and the pathogenic isoform of prion protein (PrPSc) have a crucial role in neuronal death and gliosis that occur in both of these disorders. In this study, we investigate whether Abeta and PrPSc cause microglia activation per se and whether these amyloidogenic peptides differentially affect these immunoeffector cells. In addition, we also determined whether substances released by Abeta- and PrP-activated microglia induce neuronal death. Cultures of rat brain microglia cells were treated with the synthetic peptides Abeta1-40, Abeta1-42 and PrP106-126 for different time periods. The lipopolysaccharide was used as a positive control of microglia activation. Our results show that Abeta1-40 and PrP106-126 caused similar morphological changes in microglia and increased the production of nitric oxide and hydroperoxides. An increase on inducible nitric oxide synthase expression was also observed in microglia treated with Abeta1-40 or PrP106. However, these peptides affected in a different manner the secretion of interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) secretion. In cocultures of microglia-neurons, it was observed that microglia treated with Abeta1-40 or PrP106-126 induced a comparable extent of neuronal death. The neutralizing antibody for IL-6 significantly reduced the neuronal death induced by Abeta- or PrP-activated microglia. Taken together, the data indicate that Abeta and PrP peptides caused microglia activation and differentially affected cytokine secretion. The IL-6 released by reactive microglia caused neuronal injury.
Collapse
Affiliation(s)
- Pedro Garção
- Center for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal
| | | | | |
Collapse
|
2719
|
Abstract
T cell activation requires interactions of T cell antigen receptors and peptides presented by major histocompatibility complex molecules in an adhesive junction between the T cell and antigen-presenting cell (APC). Stable junctions with bull's-eye supramolecular activation clusters have been defined as immunological synapses (IS). These structures maintain T cell-APC interaction and allow directed secretion. T cells can also be activated by asymmetric hemisynapses (HS) that allow migration during signal integration. IS and HS dominate in different stages of T cell priming. Optimal effector functions may also depend upon cyclical use of IS and HS.
Collapse
Affiliation(s)
- Michael L Dustin
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, and Department of Pathology, New York University School of Medicine, NY 10016, USA.
| |
Collapse
|
2720
|
Bessis A, Béchade C, Bernard D, Roumier A. Microglial control of neuronal death and synaptic properties. Glia 2006; 55:233-8. [PMID: 17106878 DOI: 10.1002/glia.20459] [Citation(s) in RCA: 326] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Microglia have long been characterized by their immune function in the nervous system and are still mainly considered in a beneficial versus detrimental dialectic. However a review of literature enables to shed novel lights on microglial function under physiological conditions. It is now relevant to position these cells as full time partners of neuronal function and more specifically of synaptogenesis and developmental apoptosis. Indeed, microglia can actively control neuronal death. It has actually been shown in retina that microglial nerve growth factor (NGF) is necessary for the developmental apoptosis to occur. Similarly, in cerebellum, microglia induces developmental Purkinje cells death through respiratory burst. Furthermore, in spinal cord, microglial TNFalpha commits motoneurons to a neurotrophic dependent developmental apoptosis. Microglia can also control synaptogenesis. This is suggested by the fact that a mutation in KARAP/DAP12, a key protein of microglial activation impacts synaptic functions in hippocampus, and synapses protein content. In addition it has been now demonstrated that microglial brain-derived neurotrophin factor (BDNF) directly regulates synaptic properties in spinal cord. In conclusion, microglia can control neuronal function under physiological conditions and it is known that neuronal activity reciprocally controls microglial activation. We will discuss the importance of this cross-talk which allows microglia to orchestrate the balance between synaptogenesis and neuronal death occurring during development or injuries.
Collapse
Affiliation(s)
- Alain Bessis
- Biologie Cellulaire de la Synapse, Inserm U789, Ecole Normale Supérieure, 46 rue d'Ulm 75005 Paris, France.
| | | | | | | |
Collapse
|
2721
|
Ubogu EE, Cossoy MB, Ransohoff RM. The expression and function of chemokines involved in CNS inflammation. Trends Pharmacol Sci 2006; 27:48-55. [PMID: 16310865 DOI: 10.1016/j.tips.2005.11.002] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2005] [Revised: 09/21/2005] [Accepted: 11/11/2005] [Indexed: 12/22/2022]
Abstract
Chemokines and their receptors have principal roles in leukocyte trafficking under normal physiological and pathological conditions. The differential expression of the chemokine system in different parts of the CNS provides insights into the processes that are required for normal immune surveillance and pathological immune-mediated effector processes. Insights derived from studying multiple sclerosis, an inflammatory disorder of the CNS in humans, and experimental autoimmune encephalomyelitis, an animal model of this disorder, aid in further understanding the complexities of chemokine-mediated inflammation. Knowledge of the molecular biology of chemokines and their receptors, and the roles of specific chemokine ligands and receptors in the CNS in health and in disease have made these proteins targets for therapeutic intervention in neuroinflammation. We also discuss currently proposed and potentially useful chemokine receptor antagonists.
Collapse
Affiliation(s)
- Eroboghene E Ubogu
- Neuroinflammation Research Center, Department of Neurosciences, Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, Cleveland, OH 44195, USA
| | | | | |
Collapse
|
2722
|
Takano T, Tian GF, Peng W, Lou N, Libionka W, Han X, Nedergaard M. Astrocyte-mediated control of cerebral blood flow. Nat Neurosci 2005; 9:260-7. [PMID: 16388306 DOI: 10.1038/nn1623] [Citation(s) in RCA: 813] [Impact Index Per Article: 42.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2005] [Accepted: 12/02/2005] [Indexed: 12/12/2022]
Abstract
Local increase in blood flow during neural activity forms the basis for functional brain imaging, but its mechanism remains poorly defined. Here we show that cortical astrocytes in vivo possess a powerful mechanism for rapid vasodilation. We imaged the activity of astrocytes labeled with the calcium (Ca(2+))-sensitive indicator rhod-2 in somatosensory cortex of adult mice. Photolysis of caged Ca(2+) in astrocytic endfeet ensheathing the vessel wall was associated with an 18% increase in arterial cross-section area that corresponded to a 37% increase in blood flow. Vasodilation occurred with a latency of only 1-2 s, and both indomethacin and the cyclooxygenase-1 inhibitor SC-560 blocked the photolysis-induced hyperemia. These observations implicate astrocytes in the control of local microcirculation and suggest that one of their physiological roles is to mediate vasodilation in response to increased neural activity.
Collapse
Affiliation(s)
- Takahiro Takano
- Center for Aging and Developmental Biology, Department of Neurosurgery, University of Rochester Medical School, 601 Elmwood Avenue, Rochester, New York 14642, USA.
| | | | | | | | | | | | | |
Collapse
|
2723
|
Weydt P, Möller T. The role of microglial cells in amyotrophic lateral sclerosis. Phys Med Rehabil Clin N Am 2005; 16:1081-90, xi. [PMID: 16214061 DOI: 10.1016/j.pmr.2005.08.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Patrick Weydt
- Department of Laboratory Medicine, University of Washington, 1959 NE Pacific Street, Seattle, WA 98195, USA.
| | | |
Collapse
|
2724
|
Abstract
T cell activation requires interactions of T cell antigen receptors (TCR) and peptides presented by major histocompatibility complex molecules (MHCp) in an adhesive junction between the T cell and antigen-presenting cell. Stable junctions with bull's eye supramolecular activation clusters (SMACs) have been defined as immunological synapses (IS). These structures maintain T cell-APC interaction and allow directed secretion. T cells can also be activated by asymmetric hemi-synapses (HS) that allow migration during signal integration. IS and HS operate in different stages of T cell priming. Optimal effector functions may also depend upon cyclical use of IS and HS.
Collapse
Affiliation(s)
- Michael L Dustin
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, and Department of Pathology, New York University School of Medicine, 540 1st Ave, New York, NY 10016, USA.
| |
Collapse
|
2725
|
Raivich G. Like cops on the beat: the active role of resting microglia. Trends Neurosci 2005; 28:571-3. [PMID: 16165228 DOI: 10.1016/j.tins.2005.09.001] [Citation(s) in RCA: 166] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2005] [Revised: 08/12/2005] [Accepted: 09/05/2005] [Indexed: 11/17/2022]
Abstract
Microglia form the first line of defence for the neural parenchyma. But do these cells pursue an active role in the normal brain, or do they become activated only after injury? Two papers published recently by Nimmerjahn et al. and Davalos et al. used in vivo two-photon laser-scanning microscopy reveal that the fine branches of 'resting' microglia are highly mobile, and provide extensive and continuous surveillance of their cellular environment. These moving branches show a rapid chemotactic response to tissue injury that depends on purine receptors and connexin hemichannels, and they appear to take cues from surrounding astrocytes both in the normal and the injured brain.
Collapse
Affiliation(s)
- Gennadij Raivich
- Perinatal Brain Repair Group, Department of Anatomy, Obstetrics and Gynaecology, University College London, Chenies Mews 86-96, London WC1E 6HX, UK.
| |
Collapse
|
2726
|
Janusonis S. Statistical distribution of blood serotonin as a predictor of early autistic brain abnormalities. Theor Biol Med Model 2005; 2:27. [PMID: 16029508 PMCID: PMC1199627 DOI: 10.1186/1742-4682-2-27] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2005] [Accepted: 07/19/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A wide range of abnormalities has been reported in autistic brains, but these abnormalities may be the result of an earlier underlying developmental alteration that may no longer be evident by the time autism is diagnosed. The most consistent biological finding in autistic individuals has been their statistically elevated levels of 5-hydroxytryptamine (5-HT, serotonin) in blood platelets (platelet hyperserotonemia). The early developmental alteration of the autistic brain and the autistic platelet hyperserotonemia may be caused by the same biological factor expressed in the brain and outside the brain, respectively. Unlike the brain, blood platelets are short-lived and continue to be produced throughout the life span, suggesting that this factor may continue to operate outside the brain years after the brain is formed. The statistical distributions of the platelet 5-HT levels in normal and autistic groups have characteristic features and may contain information about the nature of this yet unidentified factor. RESULTS The identity of this factor was studied by using a novel, quantitative approach that was applied to published distributions of the platelet 5-HT levels in normal and autistic groups. It was shown that the published data are consistent with the hypothesis that a factor that interferes with brain development in autism may also regulate the release of 5-HT from gut enterochromaffin cells. Numerical analysis revealed that this factor may be non-functional in autistic individuals. CONCLUSION At least some biological factors, the abnormal function of which leads to the development of the autistic brain, may regulate the release of 5-HT from the gut years after birth. If the present model is correct, it will allow future efforts to be focused on a limited number of gene candidates, some of which have not been suspected to be involved in autism (such as the 5-HT4 receptor gene) based on currently available clinical and experimental studies.
Collapse
Affiliation(s)
- Skirmantas Janusonis
- Department of Neurobiology, Yale University School of Medicine, New Haven, CT 06520-8001, USA.
| |
Collapse
|
2727
|
Affiliation(s)
- Luc Fetler
- Laboratoire Physico-Chimie Curie, CNRS UMR 168, Institut Curie, Paris, France.
| | | |
Collapse
|