1
|
Mielnicka A, Michaluk P. Exocytosis in Astrocytes. Biomolecules 2021; 11:1367. [PMID: 34572580 PMCID: PMC8471187 DOI: 10.3390/biom11091367] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 09/10/2021] [Accepted: 09/14/2021] [Indexed: 12/17/2022] Open
Abstract
Until recently, astrocytes were thought to be a part of a simple "brain glue" providing only a supporting role for neurons. However, the discoveries of the last two decades have proven astrocytes to be dynamic partners participating in brain metabolism and actively influencing communication between neurons. The means of astrocyte-neuron communication are diverse, although regulated exocytosis has received the most attention but also caused the most debate. Similar to most of eukaryotic cells, astrocytes have a complex range of vesicular organelles which can undergo exocytosis as well as intricate molecular mechanisms that regulate this process. In this review, we focus on the components needed for regulated exocytosis to occur and summarise the knowledge about experimental evidence showing its presence in astrocytes.
Collapse
Affiliation(s)
| | - Piotr Michaluk
- BRAINCITY, Laboratory of Neurobiology, The Nencki Institute of Experimental Biology, PAS, 02-093 Warsaw, Poland;
| |
Collapse
|
2
|
Musto M, Parisse P, Pachetti M, Memo C, Di Mauro G, Ballesteros B, Lozano N, Kostarelos K, Casalis L, Ballerini L. Shedding plasma membrane vesicles induced by graphene oxide nanoflakes in brain cultured astrocytes. CARBON 2021. [DOI: 10.1016/j.carbon.2021.01.142] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
3
|
Infrared Nanospectroscopy of Individual Extracellular Microvesicles. Molecules 2021; 26:molecules26040887. [PMID: 33567597 PMCID: PMC7915346 DOI: 10.3390/molecules26040887] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2021] [Revised: 01/29/2021] [Accepted: 02/04/2021] [Indexed: 01/08/2023] Open
Abstract
Extracellular vesicles are membrane-delimited structures, involved in several inter-cellular communication processes, both physiological and pathological, since they deliver complex biological cargo. Extracellular vesicles have been identified as possible biomarkers of several pathological diseases; thus, their characterization is fundamental in order to gain a deep understanding of their function and of the related processes. Traditional approaches for the characterization of the molecular content of the vesicles require a large quantity of sample, thereby providing an average molecular profile, while their heterogeneity is typically probed by non-optical microscopies that, however, lack the chemical sensitivity to provide information of the molecular cargo. Here, we perform a study of individual microvesicles, a subclass of extracellular vesicles generated by the outward budding of the plasma membrane, released by two cultures of glial cells under different stimuli, by applying a state-of-the-art infrared nanospectroscopy technique based on the coupling of an atomic force microscope and a pulsed laser, which combines the label-free chemical sensitivity of infrared spectroscopy with the nanometric resolution of atomic force microscopy. By correlating topographic, mechanical and spectroscopic information of individual microvesicles, we identified two main populations in both families of vesicles released by the two cell cultures. Subtle differences in terms of nucleic acid content among the two families of vesicles have been found by performing a fitting procedure of the main nucleic acid vibrational peaks in the 1000–1250 cm−1 frequency range.
Collapse
|
4
|
Bilirubin disrupts calcium homeostasis in neonatal hippocampal neurons: a new pathway of neurotoxicity. Arch Toxicol 2020; 94:845-855. [DOI: 10.1007/s00204-020-02659-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 02/03/2020] [Indexed: 12/22/2022]
|
5
|
Vardjan N, Parpura V, Verkhratsky A, Zorec R. Gliocrine System: Astroglia as Secretory Cells of the CNS. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:93-115. [PMID: 31583585 DOI: 10.1007/978-981-13-9913-8_4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Astrocytes are secretory cells, actively participating in cell-to-cell communication in the central nervous system (CNS). They sense signaling molecules in the extracellular space, around the nearby synapses and also those released at much farther locations in the CNS, by their cell surface receptors, get excited to then release their own signaling molecules. This contributes to the brain information processing, based on diffusion within the extracellular space around the synapses and on convection when locales relatively far away from the release sites are involved. These functions resemble secretion from endocrine cells, therefore astrocytes were termed to be a part of the gliocrine system in 2015. An important mechanism, by which astrocytes release signaling molecules is the merger of the vesicle membrane with the plasmalemma, i.e., exocytosis. Signaling molecules stored in astroglial secretory vesicles can be discharged into the extracellular space after the vesicle membrane fuses with the plasma membrane. This leads to a fusion pore formation, a channel that must widen to allow the exit of the Vesiclal cargo. Upon complete vesicle membrane fusion, this process also integrates other proteins, such as receptors, transporters and channels into the plasma membrane, determining astroglial surface signaling landscape. Vesiclal cargo, together with the whole vesicle can also exit astrocytes by the fusion of multivesicular bodies with the plasma membrane (exosomes) or by budding of vesicles (ectosomes) from the plasma membrane into the extracellular space. These astroglia-derived extracellular vesicles can later interact with various target cells. Here, the characteristics of four types of astroglial secretory vesicles: synaptic-like microvesicles, dense-core vesicles, secretory lysosomes, and extracellular vesicles, are discussed. Then machinery for vesicle-based exocytosis, second messenger regulation and the kinetics of exocytotic vesicle content discharge or release of extracellular vesicles are considered. In comparison to rapidly responsive, electrically excitable neurons, the receptor-mediated cytosolic excitability-mediated astroglial exocytotic vesicle-based transmitter release is a relatively slow process.
Collapse
Affiliation(s)
- Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, 1000, Ljubljana, Slovenia. .,Celica Biomedical, 1000, Ljubljana, Slovenia.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK.,Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, 2200, Copenhagen, Denmark.,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, 1000, Ljubljana, Slovenia. .,Celica Biomedical, 1000, Ljubljana, Slovenia.
| |
Collapse
|
6
|
Musto M, Rauti R, Rodrigues AF, Bonechi E, Ballerini C, Kostarelos K, Ballerini L. 3D Organotypic Spinal Cultures: Exploring Neuron and Neuroglia Responses Upon Prolonged Exposure to Graphene Oxide. Front Syst Neurosci 2019; 13:1. [PMID: 30733671 PMCID: PMC6354065 DOI: 10.3389/fnsys.2019.00001] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/03/2019] [Indexed: 11/13/2022] Open
Abstract
Graphene-based nanomaterials are increasingly engineered as components of biosensors, interfaces or drug delivery platforms in neuro-repair strategies. In these developments, the mostly used derivative of graphene is graphene oxide (GO). To tailor the safe development of GO nanosheets, we need to model in vitro tissue responses, and in particular the reactivity of microglia, a sub-population of neuroglia that acts as the first active immune response, when challenged by GO. Here, we investigated central nervous system (CNS) tissue reactivity upon long-term exposure to GO nanosheets in 3D culture models. We used the mouse organotypic spinal cord cultures, ideally suited for studying long-term interference with cues delivered at controlled times and concentrations. In cultured spinal segments, the normal presence, distribution and maturation of anatomically distinct classes of neurons and resident neuroglial cells are preserved. Organotypic explants were developed for 2 weeks embedded in fibrin glue alone or presenting GO nanosheets at 10, 25 and 50 μg/mL. We addressed the impact of such treatments on premotor synaptic activity monitored by patch clamp recordings of ventral interneurons. We investigated by immunofluorescence and confocal microscopy the accompanying glial responses to GO exposure, focusing on resident microglia, tested in organotypic spinal slices and in isolated neuroglia cultures. Our results suggest that microglia reactivity to accumulation of GO flakes, maybe due to active phagocytosis, may trim down synaptic activity, although in the absence of an effective activation of inflammatory response and in the absence of neuronal cell death.
Collapse
Affiliation(s)
- Mattia Musto
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Rossana Rauti
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Trieste, Italy
| | - Artur Filipe Rodrigues
- Nanomedicine Lab, Faculty of Biology, Medicine & Health and National Graphene Institute, University of Manchester, Manchester, United Kingdom
| | - Elena Bonechi
- Department NEUROFARBA, University of Florence, Florence, Italy
| | - Clara Ballerini
- Laboratory of Neuroimmunology, Dipartimento di Medicina Sperimentale e Clinica, University of Firenze, Firenze, Italy
| | - Kostas Kostarelos
- Nanomedicine Lab, Faculty of Biology, Medicine & Health and National Graphene Institute, University of Manchester, Manchester, United Kingdom
| | - Laura Ballerini
- Neuron Physiology and Technology Lab, International School for Advanced Studies (SISSA), Trieste, Italy
| |
Collapse
|
7
|
Horvat A, Vardjan N. Astroglial cAMP signalling in space and time. Neurosci Lett 2018; 689:5-10. [PMID: 29908259 DOI: 10.1016/j.neulet.2018.06.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 06/11/2018] [Accepted: 06/13/2018] [Indexed: 01/14/2023]
Abstract
To maintain a high level of specificity and normal cell function, the cyclic adenosine monophosphate (cAMP) pathway is tightly regulated in space and time. Recent advances in cAMP reporter technology have provided insights into spatio-temporal characteristics of cAMP signalling in individual living cells, including astrocytes. Astrocytes are glial cells in the central nervous system with many homeostatic functions. In contrast to neurons, astrocytes are electrically silent, but, in response to extracellular stimuli through activation of surface receptors, they can increase intracellular levels of secondary messengers, e.g. Ca2+ and cAMP. This enables them to communicate with neighbouring cells, such as neurons and endothelial cells of blood vessels. The dynamics of receptor-mediated Ca2+ signalling in astrocytes has been extensively studied in the past in contrast to cAMP signalling. Here, we present the first insights into the temporal dynamics of cAMP signalling in living astrocytes, which revealed that cAMP signals in astrocytes exhibit tonic dynamics and are slower than Ca2+ signals with phasic dynamics. We debate on the heterogeneity of basal cAMP levels in astrocytes and how hypotonicity-induced astrocyte swelling affects temporal dynamics of cAMP signalling. Understanding the spatio-temporal characteristics of cAMP signalling in astrocytes is of extreme importance because cAMP governs many important cellular processes and any malfunctions may lead to pathology.
Collapse
Affiliation(s)
- Anemari Horvat
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; Laboratory of Cell Engineering, Celica Biomedical, Tehnološki Park 24, 1000 Ljubljana, Slovenia.
| |
Collapse
|
8
|
TNFα and IL-1β modify the miRNA cargo of astrocyte shed extracellular vesicles to regulate neurotrophic signaling in neurons. Cell Death Dis 2018; 9:363. [PMID: 29507357 PMCID: PMC5838212 DOI: 10.1038/s41419-018-0369-4] [Citation(s) in RCA: 126] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/23/2018] [Accepted: 01/25/2018] [Indexed: 11/09/2022]
Abstract
Astrocytes are known to be critical regulators of neuronal function. However, relatively few mediators of astrocyte to neuron communication have been identified. Recent advancements in the biology of extracellular vesicles have begun to implicate astrocyte derived extracellular vesicles (ADEV) as mediators of astrocyte to neuron communication, suggesting that alterations in the release and/or composition of ADEVs could influence gliotransmission. TNFα and IL-1β are key mediators of glial activation and neuronal damage, but the effects of these cytokines on the release or molecular composition of ADEVs is unknown. We found that ADEVs released in response to IL-1β (ADEV-IL-1β) and TNFα (ADEV-TNFα) were enriched with miRNAs that target proteins involved in neurotrophin signaling. We confirmed that miR-125a-5p and miR-16-5p (both enriched in ADEV-IL-1β and ADEV-TNFα) targeted NTKR3 and its downstream effector Bcl2. Downregulation of these targets in neurons was associated with reductions in dendritic growth, dendritic complexity, reduced spike rates, and burst activity. Molecular interference of miR-125a-5p and miR-16-5p prevented ADEV-IL-1β from reducing dendritic complexity, spike, and burst rates. These findings suggest that astrocytes respond to inflammatory challenge by modifying the miRNA cargo of ADEVs to diminish the activity of target neurons by regulating the translational expression of proteins controlling programs essential for synaptic stability and neuronal excitability.
Collapse
|
9
|
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| |
Collapse
|
10
|
Verkhratsky A, Nedergaard M. Physiology of Astroglia. Physiol Rev 2018; 98:239-389. [PMID: 29351512 PMCID: PMC6050349 DOI: 10.1152/physrev.00042.2016] [Citation(s) in RCA: 899] [Impact Index Per Article: 149.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/22/2017] [Accepted: 04/27/2017] [Indexed: 02/07/2023] Open
Abstract
Astrocytes are neural cells of ectodermal, neuroepithelial origin that provide for homeostasis and defense of the central nervous system (CNS). Astrocytes are highly heterogeneous in morphological appearance; they express a multitude of receptors, channels, and membrane transporters. This complement underlies their remarkable adaptive plasticity that defines the functional maintenance of the CNS in development and aging. Astrocytes are tightly integrated into neural networks and act within the context of neural tissue; astrocytes control homeostasis of the CNS at all levels of organization from molecular to the whole organ.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| | - Maiken Nedergaard
- The University of Manchester , Manchester , United Kingdom ; Achúcarro Basque Center for Neuroscience, IKERBASQUE, Basque Foundation for Science , Bilbao , Spain ; Department of Neuroscience, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain ; Center for Basic and Translational Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen , Copenhagen , Denmark ; and Center for Translational Neuromedicine, University of Rochester Medical Center , Rochester, New York
| |
Collapse
|
11
|
Ren Q, Wang ZZ, Chu SF, Xia CY, Chen NH. Gap junction channels as potential targets for the treatment of major depressive disorder. Psychopharmacology (Berl) 2018; 235:1-12. [PMID: 29178009 DOI: 10.1007/s00213-017-4782-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 11/05/2017] [Indexed: 01/08/2023]
Abstract
BACKGROUND Major depressive disorder (MDD) remains a major public health problem worldwide. The association between MDD and the dysfunction of gap junction channels (GJCs) in glial cells, especially astrocytes, is still controversial. OBJECTIVE This review provides an overview of the role of astrocyte GJCs in LMDD. RESULTS Exposure to chronic unpredictable stress caused a reduction in connexin expression in the rat prefrontal cortex, a result that is consistent with clinical findings reported in postmortem studies of brains from MDD patients. Chronic antidepressant treatment in these rats increased the expression of connexins. However, pharmacological GJC blockade in normal rodents decreased connexin expression and caused depressive-like behaviors. Furthermore, GJC dysfunction affects electrical conductance, metabolic coupling and secondary messengers, and inflammatory responses, which are consistent with current hypotheses on MDD. All these results provide a comprehensive overview of the neurobiology of MDD. CONCLUSION This review supports the hypothesis that the regulation of GJCs between astrocytes could be an underlying mechanism for the therapeutic effect of antidepressants.
Collapse
Affiliation(s)
- Qian Ren
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Zhen-Zhen Wang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Shi-Feng Chu
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Cong-Yuan Xia
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica & Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, 100050, China. .,College of Pharmacy, Hunan University of Chinese Medicine, Changsha, Hunan, 410208, China.
| |
Collapse
|
12
|
Astrocytic Pathological Calcium Homeostasis and Impaired Vesicle Trafficking in Neurodegeneration. Int J Mol Sci 2017; 18:ijms18020358. [PMID: 28208745 PMCID: PMC5343893 DOI: 10.3390/ijms18020358] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Revised: 01/30/2017] [Accepted: 01/31/2017] [Indexed: 02/08/2023] Open
Abstract
Although the central nervous system (CNS) consists of highly heterogeneous populations of neurones and glial cells, clustered into diverse anatomical regions with specific functions, there are some conditions, including alertness, awareness and attention that require simultaneous, coordinated and spatially homogeneous activity within a large area of the brain. During such events, the brain, representing only about two percent of body mass, but consuming one fifth of body glucose at rest, needs additional energy to be produced. How simultaneous energy procurement in a relatively extended area of the brain takes place is poorly understood. This mechanism is likely to be impaired in neurodegeneration, for example in Alzheimer’s disease, the hallmark of which is brain hypometabolism. Astrocytes, the main neural cell type producing and storing glycogen, a form of energy in the brain, also hold the key to metabolic and homeostatic support in the central nervous system and are impaired in neurodegeneration, contributing to the slow decline of excitation-energy coupling in the brain. Many mechanisms are affected, including cell-to-cell signalling. An important question is how changes in cellular signalling, a process taking place in a rather short time domain, contribute to the neurodegeneration that develops over decades. In this review we focus initially on the slow dynamics of Alzheimer’s disease, and on the activity of locus coeruleus, a brainstem nucleus involved in arousal. Subsequently, we overview much faster processes of vesicle traffic and cytosolic calcium dynamics, both of which shape the signalling landscape of astrocyte-neurone communication in health and neurodegeneration.
Collapse
|
13
|
Wolfes AC, Ahmed S, Awasthi A, Stahlberg MA, Rajput A, Magruder DS, Bonn S, Dean C. A novel method for culturing stellate astrocytes reveals spatially distinct Ca2+ signaling and vesicle recycling in astrocytic processes. J Gen Physiol 2016; 149:149-170. [PMID: 27908976 PMCID: PMC5217085 DOI: 10.1085/jgp.201611607] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 11/09/2016] [Accepted: 11/11/2016] [Indexed: 12/20/2022] Open
Abstract
Communication between astrocytes and neurons has been difficult to study because cultured astrocytes do not resemble those in vivo. Wolfes et al. develop a stellate astrocyte monoculture with physiological characteristics and find that VAMP2 and SYT7 mark distinct vesicle populations in astrocytes. Interactions between astrocytes and neurons rely on the release and uptake of glial and neuronal molecules. But whether astrocytic vesicles exist and exocytose in a regulated or constitutive fashion is under debate. The majority of studies have relied on indirect methods or on astrocyte cultures that do not resemble stellate astrocytes found in vivo. Here, to investigate vesicle-associated proteins and exocytosis in stellate astrocytes specifically, we developed a simple, fast, and economical method for growing stellate astrocyte monocultures. This method is superior to other monocultures in terms of astrocyte morphology, mRNA expression profile, protein expression of cell maturity markers, and Ca2+ fluctuations: In astrocytes transduced with GFAP promoter–driven Lck-GCaMP3, spontaneous Ca2+ events in distinct domains (somata, branchlets, and microdomains) are similar to those in astrocytes co-cultured with other glia and neurons but unlike Ca2+ events in astrocytes prepared using the McCarthy and de Vellis (MD) method and immunopanned (IP) astrocytes. We identify two distinct populations of constitutively recycling vesicles (harboring either VAMP2 or SYT7) specifically in branchlets of cultured stellate astrocytes. SYT7 is developmentally regulated in these astrocytes, and we observe significantly fewer synapses in wild-type mouse neurons grown on Syt7−/− astrocytes. SYT7 may thus be involved in trafficking or releasing synaptogenic factors. In summary, our novel method yields stellate astrocyte monocultures that can be used to study Ca2+ signaling and vesicle recycling and dynamics in astrocytic processes.
Collapse
Affiliation(s)
- Anne C Wolfes
- Trans-Synaptic Signaling Group, European Neuroscience Institute Göttingen, 37077 Göttingen, Germany
| | - Saheeb Ahmed
- Trans-Synaptic Signaling Group, European Neuroscience Institute Göttingen, 37077 Göttingen, Germany
| | - Ankit Awasthi
- Trans-Synaptic Signaling Group, European Neuroscience Institute Göttingen, 37077 Göttingen, Germany
| | - Markus A Stahlberg
- Trans-Synaptic Signaling Group, European Neuroscience Institute Göttingen, 37077 Göttingen, Germany
| | - Ashish Rajput
- Research Group for Computational Systems Biology, German Center for Neurodegenerative Disease (DZNE), 37075 Göttingen, Germany
| | - Daniel S Magruder
- Research Group for Computational Systems Biology, German Center for Neurodegenerative Disease (DZNE), 37075 Göttingen, Germany
| | - Stefan Bonn
- Research Group for Computational Systems Biology, German Center for Neurodegenerative Disease (DZNE), 37075 Göttingen, Germany
| | - Camin Dean
- Trans-Synaptic Signaling Group, European Neuroscience Institute Göttingen, 37077 Göttingen, Germany
| |
Collapse
|
14
|
Zorec R, Parpura V, Verkhratsky A. Astroglial Vesicular Trafficking in Neurodegenerative Diseases. Neurochem Res 2016; 42:905-917. [DOI: 10.1007/s11064-016-2055-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 08/30/2016] [Accepted: 08/31/2016] [Indexed: 12/20/2022]
|
15
|
Parpura V, Sekler I, Fern R. Plasmalemmal and mitochondrial Na+-Ca2+exchange in neuroglia. Glia 2016; 64:1646-54. [DOI: 10.1002/glia.22975] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 01/07/2016] [Accepted: 01/25/2016] [Indexed: 12/20/2022]
Affiliation(s)
- Vladimir Parpura
- Department of Neurobiology; Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy & Nanotechnology Laboratories, and Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham; Birmingham Alabama
| | - Israel Sekler
- Department of Physiology, Faculty of Health Science; Ben-Gurion University; Ben-Guion Av 84105 POB 653
| | - Robert Fern
- Peninsular School of Medicine and Dentistry; University of Plymouth; Plymouth PL6 8BU United Kingdom
| |
Collapse
|
16
|
Rauti R, Lozano N, León V, Scaini D, Musto M, Rago I, Ulloa Severino FP, Fabbro A, Casalis L, Vázquez E, Kostarelos K, Prato M, Ballerini L. Graphene Oxide Nanosheets Reshape Synaptic Function in Cultured Brain Networks. ACS NANO 2016; 10:4459-71. [PMID: 27030936 DOI: 10.1021/acsnano.6b00130] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Graphene offers promising advantages for biomedical applications. However, adoption of graphene technology in biomedicine also poses important challenges in terms of understanding cell responses, cellular uptake, or the intracellular fate of soluble graphene derivatives. In the biological microenvironment, graphene nanosheets might interact with exposed cellular and subcellular structures, resulting in unexpected regulation of sophisticated biological signaling. More broadly, biomedical devices based on the design of these 2D planar nanostructures for interventions in the central nervous system require an accurate understanding of their interactions with the neuronal milieu. Here, we describe the ability of graphene oxide nanosheets to down-regulate neuronal signaling without affecting cell viability.
Collapse
Affiliation(s)
- Rossana Rauti
- Life Science Department, University of Trieste , 34127 Trieste, Italy
| | - Neus Lozano
- Nanomedicine Lab, School of Medicine and National Graphene Institute, Faculty of Medical & Human Sciences, University of Manchester , M13 9PL Manchester, United Kingdom
| | - Veronica León
- Departamento de Química Orgánica, Facultad de Ciencias y Tecnologías Químicas-IRICA, Universidad de Castilla La Mancha , 13071 Ciudad Real, Spain
| | - Denis Scaini
- Life Science Department, University of Trieste , 34127 Trieste, Italy
- ELETTRA Synchrotron Light Source , 34149 Trieste, Italy
| | - Mattia Musto
- International School for Advanced Studies (SISSA) , 34136 Trieste, Italy
| | - Ilaria Rago
- ELETTRA Synchrotron Light Source , 34149 Trieste, Italy
| | | | - Alessandra Fabbro
- Department of Chemical and Pharmaceutical Sciences, University of Trieste , 34127 Trieste, Italy
| | | | - Ester Vázquez
- Departamento de Química Orgánica, Facultad de Ciencias y Tecnologías Químicas-IRICA, Universidad de Castilla La Mancha , 13071 Ciudad Real, Spain
| | - Kostas Kostarelos
- Nanomedicine Lab, School of Medicine and National Graphene Institute, Faculty of Medical & Human Sciences, University of Manchester , M13 9PL Manchester, United Kingdom
| | - Maurizio Prato
- Department of Chemical and Pharmaceutical Sciences, University of Trieste , 34127 Trieste, Italy
- CIC BiomaGUNE, Parque Tecnológico de San Sebastián, Paseo Miramón, 182, 20009 San Sebastián, Guipúzcoa, Spain
- Basque Foundation for Science , Ikerbasque, Bilbao 48013, Spain
| | - Laura Ballerini
- Life Science Department, University of Trieste , 34127 Trieste, Italy
- International School for Advanced Studies (SISSA) , 34136 Trieste, Italy
| |
Collapse
|
17
|
Potokar M, Jorgačevski J, Lacovich V, Kreft M, Vardjan N, Bianchi V, D'Adamo P, Zorec R. Impaired αGDI Function in the X-Linked Intellectual Disability: The Impact on Astroglia Vesicle Dynamics. Mol Neurobiol 2016; 54:2458-2468. [PMID: 26971292 DOI: 10.1007/s12035-016-9834-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 03/04/2016] [Indexed: 11/25/2022]
Abstract
X-linked non-syndromic intellectual disability (XLID) is a common mental disorder recognized by cognitive and behavioral deficits. Mutations in the brain-specific αGDI, shown to alter a subset of RAB GTPases redistribution in cells, are linked to XLID, likely via changes in vesicle traffic in neurons. Here, we show directly that isolated XLID mice astrocytes, devoid of pathologic tissue environment, exhibit vesicle mobility deficits. Contrary to previous studies, we show that astrocytes express two GDI proteins. The siRNA-mediated suppression of expression of αGDI especially affected vesicle dynamics. A similar defect was recorded in astrocytes from the Gdi1 -/Y mouse model of XLID and in astrocytes with recombinant mutated human XLID αGDI. Endolysosomal vesicles studied here are involved in the release of gliosignaling molecules as well as in regulating membrane receptor density; thus, the observed changes in astrocytic vesicle mobility may, over the long time-course, profoundly affect signaling capacity of these cells, which optimize neural activity.
Collapse
Affiliation(s)
- Maja Potokar
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
| | | | - Marko Kreft
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
- Biotechnical Faculty, University of Ljubljana, 1000, Ljubljana, Slovenia
| | - Nina Vardjan
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
| | - Veronica Bianchi
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Patrizia D'Adamo
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia
- Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132, Milan, Italy
| | - Robert Zorec
- Celica Biomedical, Tehnološki park 24, 1000, Ljubljana, Slovenia.
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000, Ljubljana, Slovenia.
| |
Collapse
|
18
|
Verkhratsky A, Matteoli M, Parpura V, Mothet JP, Zorec R. Astrocytes as secretory cells of the central nervous system: idiosyncrasies of vesicular secretion. EMBO J 2016; 35:239-57. [PMID: 26758544 DOI: 10.15252/embj.201592705] [Citation(s) in RCA: 282] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 12/01/2015] [Indexed: 11/09/2022] Open
Abstract
Astrocytes are housekeepers of the central nervous system (CNS) and are important for CNS development, homeostasis and defence. They communicate with neurones and other glial cells through the release of signalling molecules. Astrocytes secrete a wide array of classic neurotransmitters, neuromodulators and hormones, as well as metabolic, trophic and plastic factors, all of which contribute to the gliocrine system. The release of neuroactive substances from astrocytes occurs through several distinct pathways that include diffusion through plasmalemmal channels, translocation by multiple transporters and regulated exocytosis. As in other eukaryotic cells, exocytotic secretion from astrocytes involves divergent secretory organelles (synaptic-like microvesicles, dense-core vesicles, lysosomes, exosomes and ectosomes), which differ in size, origin, cargo, membrane composition, dynamics and functions. In this review, we summarize the features and functions of secretory organelles in astrocytes. We focus on the biogenesis and trafficking of secretory organelles and on the regulation of the exocytotic secretory system in the context of healthy and diseased astrocytes.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, UK Achucarro Center for Neuroscience, IKERBASQUE Basque Foundation for Science, Bilbao, Spain Department of Neurosciences, University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain University of Nizhny Novgorod, Nizhny Novgorod, Russia Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology University of Ljubljana, Ljubljana, Slovenia Celica BIOMEDICAL, Ljubljana, Slovenia
| | - Michela Matteoli
- CNR Institute of Neuroscience, Milano, Italy Humanitas Research Hospital, Rozzano, Italy
| | - Vladimir Parpura
- Department of Neurobiology, Civitan International Research Center and Center for Glial Biology in Medicine, Evelyn F. McKnight Brain Institute, Atomic Force Microscopy & Nanotechnology Laboratories University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jean-Pierre Mothet
- Team Gliotransmission & Synaptopathies, Aix-Marseille University CNRS, CRN2M UMR7286, Marseille, France
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology University of Ljubljana, Ljubljana, Slovenia Celica BIOMEDICAL, Ljubljana, Slovenia
| |
Collapse
|
19
|
Sahlender DA, Savtchouk I, Volterra A. What do we know about gliotransmitter release from astrocytes? Philos Trans R Soc Lond B Biol Sci 2015; 369:20130592. [PMID: 25225086 PMCID: PMC4173278 DOI: 10.1098/rstb.2013.0592] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Astrocytes participate in information processing by actively modulating synaptic properties via gliotransmitter release. Various mechanisms of astrocytic release have been reported, including release from storage organelles via exocytosis and release from the cytosol via plasma membrane ion channels and pumps. It is still not fully clear which mechanisms operate under which conditions, but some of them, being Ca2+-regulated, may be physiologically relevant. The properties of Ca2+-dependent transmitter release via exocytosis or via ion channels are different and expected to produce different extracellular transmitter concentrations over time and to have distinct functional consequences. The molecular aspects of these two release pathways are still under active investigation. Here, we discuss the existing morphological and functional evidence in support of either of them. Transgenic mouse models, specific antagonists and localization studies have provided insight into regulated exocytosis, albeit not in a systematic fashion. Even more remains to be uncovered about the details of channel-mediated release. Better functional tools and improved ultrastructural approaches are needed in order fully to define specific modalities and effects of astrocytic gliotransmitter release pathways.
Collapse
Affiliation(s)
- Daniela A Sahlender
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, Lausanne 1005, Switzerland
| | - Iaroslav Savtchouk
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, Lausanne 1005, Switzerland
| | - Andrea Volterra
- Department of Fundamental Neurosciences, University of Lausanne, Rue du Bugnon 9, Lausanne 1005, Switzerland
| |
Collapse
|
20
|
Sreetama SC, Takano T, Nedergaard M, Simon SM, Jaiswal JK. Injured astrocytes are repaired by Synaptotagmin XI-regulated lysosome exocytosis. Cell Death Differ 2015; 23:596-607. [PMID: 26450452 DOI: 10.1038/cdd.2015.124] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 08/03/2015] [Accepted: 08/17/2015] [Indexed: 12/21/2022] Open
Abstract
Astrocytes are known to facilitate repair following brain injury; however, little is known about how injured astrocytes repair themselves. Repair of cell membrane injury requires Ca(2+)-triggered vesicle exocytosis. In astrocytes, lysosomes are the main Ca(2+)-regulated exocytic vesicles. Here we show that astrocyte cell membrane injury results in a large and rapid calcium increase. This triggers robust lysosome exocytosis where the fusing lysosomes release all luminal contents and merge fully with the plasma membrane. In contrast to this, receptor stimulation produces a small sustained calcium increase, which is associated with partial release of the lysosomal luminal content, and the lysosome membrane does not merge into the plasma membrane. In most cells, lysosomes express the synaptotagmin (Syt) isoform Syt VII; however, this isoform is not present on astrocyte lysosomes and exogenous expression of Syt VII on lysosome inhibits their exocytosis. Deletion of one of the most abundant Syt isoform in astrocyte--Syt XI--suppresses astrocyte lysosome exocytosis. This identifies lysosome as Syt XI-regulated exocytic vesicle in astrocytes. Further, inhibition of lysosome exocytosis (by Syt XI depletion or Syt VII expression) prevents repair of injured astrocytes. These results identify the lysosomes and Syt XI as the sub-cellular and molecular regulators, respectively of astrocyte cell membrane repair.
Collapse
Affiliation(s)
- S C Sreetama
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC, USA
| | - T Takano
- Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY, USA
| | - M Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY, USA
| | - S M Simon
- Laboratory of Cellular Biophysics, The Rockefeller University, 1230 York Avenue, New York, NY, USA
| | - J K Jaiswal
- Center for Genetic Medicine Research, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC, USA.,Department of Integrative Systems Biology, George Washington University School of Medicine and Health Sciences, 111 Michigan Avenue NW, Washington, DC, USA
| |
Collapse
|
21
|
Scofield MD, Boger HA, Smith RJ, Li H, Haydon PG, Kalivas PW. Gq-DREADD Selectively Initiates Glial Glutamate Release and Inhibits Cue-induced Cocaine Seeking. Biol Psychiatry 2015; 78:441-51. [PMID: 25861696 PMCID: PMC4547911 DOI: 10.1016/j.biopsych.2015.02.016] [Citation(s) in RCA: 132] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 02/10/2015] [Accepted: 02/10/2015] [Indexed: 01/24/2023]
Abstract
BACKGROUND Glial cells of the central nervous system directly influence neuronal activity by releasing neuroactive small molecules, including glutamate. Long-lasting cocaine-induced reductions in extracellular glutamate in the nucleus accumbens core (NAcore) affect synaptic plasticity responsible for relapse vulnerability. METHODS We transduced NAcore astrocytes with an adeno-associated virus vector expressing hM3D designer receptor exclusively activated by a designer drug (DREADD) under control of the glial fibrillary acidic protein promoter in 62 male Sprague Dawley rats, 4 dominant-negative soluble N-ethylmaleimide-sensitive factor attachment protein receptor mice, and 4 wild-type littermates. Using glutamate biosensors, we measured NAcore glutamate levels following intracranial or systemic administration of clozapine N-oxide (CNO) and tested the ability of systemic CNO to inhibit reinstated cocaine or sucrose seeking following self-administration and extinction training. RESULTS Administration of CNO in glial fibrillary acidic protein-hM3D-DREADD transfected animals increased NAcore extracellular glutamate levels in vivo. The glial origin of released glutamate was validated by an absence of CNO-mediated release in mice expressing a dominant-negative soluble N-ethylmaleimide-sensitive factor attachment protein receptor variant in glia. Also, CNO-mediated release was relatively insensitive to N-type calcium channel blockade. Systemic administration of CNO inhibited cue-induced reinstatement of cocaine seeking in rats extinguished from cocaine but not sucrose self-administration. The capacity to inhibit reinstated cocaine seeking was prevented by systemic administration of the group II metabotropic glutamate receptor antagonist LY341495. CONCLUSIONS DREADD-mediated glutamate gliotransmission inhibited cue-induced reinstatement of cocaine seeking by stimulating release-regulating group II metabotropic glutamate receptor autoreceptors to inhibit cue-induced synaptic glutamate spillover.
Collapse
Affiliation(s)
- Michael D Scofield
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina.
| | - Heather A Boger
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina
| | - Rachel J Smith
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina
| | - Hao Li
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina
| | - Philip G Haydon
- Department of Neurosciences, Tufts University, Boston, Massachusetts
| | - Peter W Kalivas
- Department of Neurosciences, Medical University of South Carolina, Charleston, South Carolina
| |
Collapse
|
22
|
Vardjan N, Parpura V, Zorec R. Loose excitation-secretion coupling in astrocytes. Glia 2015; 64:655-67. [PMID: 26358496 DOI: 10.1002/glia.22920] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2015] [Accepted: 08/26/2015] [Indexed: 12/19/2022]
Abstract
Astrocytes play an important housekeeping role in the central nervous system. Additionally, as secretory cells, they actively participate in cell-to-cell communication, which can be mediated by membrane-bound vesicles. The gliosignaling molecules stored in these vesicles are discharged into the extracellular space after the vesicle membrane fuses with the plasma membrane. This process is termed exocytosis, regulated by SNARE proteins, and triggered by elevations in cytosolic calcium levels, which are necessary and sufficient for exocytosis in astrocytes. For astrocytic exocytosis, calcium is sourced from the intracellular endoplasmic reticulum store, although its entry from the extracellular space contributes to cytosolic calcium dynamics in astrocytes. Here, we discuss calcium management in astrocytic exocytosis and the properties of the membrane-bound vesicles that store gliosignaling molecules, including the vesicle fusion machinery and kinetics of vesicle content discharge. In astrocytes, the delay between the increase in cytosolic calcium activity and the discharge of secretions from the vesicular lumen is orders of magnitude longer than that in neurons. This relatively loose excitation-secretion coupling is likely tailored to the participation of astrocytes in modulating neural network processing.
Collapse
Affiliation(s)
- Nina Vardjan
- Celica Biomedical, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Vladimir Parpura
- Department of Neurobiology, Center for Glial Biology in Medicine, Civitan International Research Center, Atomic Force Microscopy & Nanotechnology Laboratories, Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, Alabama
| | - Robert Zorec
- Celica Biomedical, Ljubljana, Slovenia.,Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| |
Collapse
|
23
|
Abstract
Neuroglia, the "glue" that fills the space between neurons in the central nervous system, takes active part in nerve cell signaling. Neuroglial cells, astroglia, oligodendroglia, and microglia, are together about as numerous as neurons in the brain as a whole, and in the cerebral cortex grey matter, but the proportion varies widely among brain regions. Glial volume, however, is less than one-fifth of the tissue volume in grey matter. When stimulated by neurons or other cells, neuroglial cells release gliotransmitters by exocytosis, similar to neurotransmitter release from nerve endings, or by carrier-mediated transport or channel flux through the plasma membrane. Gliotransmitters include the common neurotransmitters glutamate and GABA, the nonstandard amino acid d-serine, the high-energy phosphate ATP, and l-lactate. The latter molecule is a "buffer" between glycolytic and oxidative metabolism as well as a signaling substance recently shown to act on specific lactate receptors in the brain. Complementing neurotransmission at a synapse, neuroglial transmission often implies diffusion of the transmitter over a longer distance and concurs with the concept of volume transmission. Transmission from glia modulates synaptic neurotransmission based on energetic and other local conditions in a volume of tissue surrounding the individual synapse. Neuroglial transmission appears to contribute significantly to brain functions such as memory, as well as to prevalent neuropathologies.
Collapse
Affiliation(s)
- Vidar Gundersen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Jon Storm-Mathisen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| | - Linda Hildegard Bergersen
- SN-Lab, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, and CMBN/SERTA/Healthy Brain Ageing Centre, University of Oslo, Oslo, Norway; Department of Neurology, Oslo University Hospital-Rikshospitalet, Oslo, Norway; Center for Healthy Aging, Department of Neuroscience and Pharmacology, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; and Brain and Muscle Energy Group, Department of Oral Biology and Division of Anatomy, Department of Molecular Medicine, University of Oslo, Oslo, Norway
| |
Collapse
|
24
|
Vardjan N, Verkhratsky A, Zorec R. Pathologic Potential of Astrocytic Vesicle Traffic: New Targets to Treat Neurologic Diseases? Cell Transplant 2015; 24:599-612. [DOI: 10.3727/096368915x687750] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Vesicles are small intracellular organelles that are fundamental for constitutive housekeeping of the plasmalemma, intercellular transport, and cell-to-cell communications. In astroglial cells, traffic of vesicles is associated with cell morphology, which determines the signaling potential and metabolic support for neighboring cells, including when these cells are considered to be used for cell transplantations or for regulating neurogenesis. Moreover, vesicles are used in astrocytes for the release of vesicle-laden chemical messengers. Here we review the properties of membrane-bound vesicles that store gliotransmitters, endolysosomes that are involved in the traffic of plasma membrane receptors, and membrane transporters. These vesicles are all linked to pathological states, including amyotrophic lateral sclerosis, multiple sclerosis, neuroinflammation, trauma, edema, and states in which astrocytes contribute to developmental disorders. In multiple sclerosis, for example, fingolimod, a recently introduced drug, apparently affects vesicle traffic and gliotransmitter release from astrocytes, indicating that this process may well be used as a new pathophysiologic target for the development of new therapies.
Collapse
Affiliation(s)
- Nina Vardjan
- Celica Biomedical, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| | - Alexei Verkhratsky
- Celica Biomedical, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
- Achucarro Center for Neuroscience, Ikerbasque, Basque Foundation for Science, Bilbao, Spain
- Faculty of Life Sciences, The University of Manchester, Manchester, UK
| | - Robert Zorec
- Celica Biomedical, Ljubljana, Slovenia
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Ljubljana, Slovenia
| |
Collapse
|
25
|
Vardjan N, Zorec R. Excitable Astrocytes: Ca(2+)- and cAMP-Regulated Exocytosis. Neurochem Res 2015; 40:2414-24. [PMID: 25732760 DOI: 10.1007/s11064-015-1545-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Revised: 02/15/2015] [Accepted: 02/17/2015] [Indexed: 01/19/2023]
Abstract
During neural activity, neurotransmitters released at synapses reach neighbouring cells, such as astrocytes. These get excited via numerous mechanisms, including the G protein coupled receptors that regulate the cytosolic concentration of second messengers, such as Ca(2+) and cAMP. The stimulation of these pathways leads to feedback modulation of neuronal activity and the activity of other cells by the release of diverse substances, gliosignals that include classical neurotransmitters such as glutamate, ATP, or neuropeptides. Gliosignal molecules are released from astrocytes through several distinct molecular mechanisms, for example, by diffusion through membrane channels, by translocation via plasmalemmal transporters, or by vesicular exocytosis. Vesicular release regulated by a stimulus-mediated increase in cytosolic second messengers involves a SNARE-dependent merger of the vesicle membrane with the plasmalemma. The coupling between the stimulus and vesicular secretion of gliosignals in astrocytes is not as tight as in neurones. This is considered an adaptation to regulate homeostatic processes in a slow time domain as is the case in the endocrine system (slower than the nervous system), hence glial functions constitute the gliocrine system. This article provides an overview of the mechanisms of excitability, involving Ca(2+) and cAMP, where the former mediates phasic signalling and the latter tonic signalling. The molecular, anatomic, and physiologic properties of the vesicular apparatus mediating the release of gliosignals is presented.
Collapse
Affiliation(s)
- Nina Vardjan
- Celica Biomedical, 1000, Ljubljana, Slovenia.
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, 1000, Ljubljana, Slovenia.
| | - Robert Zorec
- Celica Biomedical, 1000, Ljubljana, Slovenia.
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, 1000, Ljubljana, Slovenia.
| |
Collapse
|
26
|
Zorec R, Verkhratsky A, Rodríguez JJ, Parpura V. Astrocytic vesicles and gliotransmitters: Slowness of vesicular release and synaptobrevin2-laden vesicle nanoarchitecture. Neuroscience 2015; 323:67-75. [PMID: 25727638 DOI: 10.1016/j.neuroscience.2015.02.033] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2014] [Revised: 02/01/2015] [Accepted: 02/18/2015] [Indexed: 12/30/2022]
Abstract
Neurotransmitters released at synapses activate neighboring astrocytes, which in turn, modulate neuronal activity by the release of diverse neuroactive substances that include classical neurotransmitters such as glutamate, GABA or ATP. Neuroactive substances are released from astrocytes through several distinct molecular mechanisms, for example, by diffusion through membrane channels, by translocation via plasmalemmal transporters or by vesicular exocytosis. Vesicular release regulated by a stimulus-mediated increase in cytosolic calcium involves soluble N-ethyl maleimide-sensitive fusion protein attachment protein receptor (SNARE)-dependent merger of the vesicle membrane with the plasmalemma. Up to 25 molecules of synaptobrevin 2 (Sb2), a SNARE complex protein, reside at a single astroglial vesicle; an individual neuronal, i.e. synaptic, vesicle contains ∼70 Sb2 molecules. It is proposed that this paucity of Sb2 molecules in astrocytic vesicles may determine the slow secretion. In the present essay we shall overview multiple aspects of vesicular architecture and types of vesicles based on their cargo and dynamics in astroglial cells.
Collapse
Affiliation(s)
- R Zorec
- University of Ljubljana, Institute of Pathophysiology, Laboratory of Neuroendocrinology and Molecular Cell Physiology, Zaloska cesta 4, SI-1000 Ljubljana, Slovenia; Celica, BIOMEDICAL, Technology Park 24, 1000 Ljubljana, Slovenia.
| | - A Verkhratsky
- University of Ljubljana, Institute of Pathophysiology, Laboratory of Neuroendocrinology and Molecular Cell Physiology, Zaloska cesta 4, SI-1000 Ljubljana, Slovenia; Celica, BIOMEDICAL, Technology Park 24, 1000 Ljubljana, Slovenia; Faculty of Life Sciences, The University of Manchester, Manchester M13 9PT, UK; Achucarro Center for Neuroscience, IKERBASQUE, 48011 Bilbao, Spain; University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain.
| | - J J Rodríguez
- Achucarro Center for Neuroscience, IKERBASQUE, 48011 Bilbao, Spain; University of the Basque Country UPV/EHU and CIBERNED, Leioa, Spain.
| | - V Parpura
- Department of Neurobiology, Civitan International Research Center and Center for Glial Biology in Medicine, Evelyn F. McKnight Brain Institute, Atomic Force Microscopy & Nanotechnology Laboratories, 1719 6th Avenue South, CIRC 429, University of Alabama at Birmingham, Birmingham, AL 35294-0021, USA; Department of Biotechnology, University of Rijeka, Radmile Matejčić 2, 51000 Rijeka, Croatia.
| |
Collapse
|
27
|
Tonna N, Bianco F, Matteoli M, Cagnoli C, Antonucci F, Manfredi A, Mauro N, Ranucci E, Ferruti P. A soluble biocompatible guanidine-containing polyamidoamine as promoter of primary brain cell adhesion and in vitro cell culturing. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2014; 15:045007. [PMID: 27877708 PMCID: PMC5090696 DOI: 10.1088/1468-6996/15/4/045007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Revised: 08/20/2014] [Accepted: 07/11/2014] [Indexed: 05/25/2023]
Abstract
This paper reports on a novel application of an amphoteric water-soluble polyamidoamine named AGMA1 bearing 4-butylguanidine pendants. AGMA1 is an amphoteric, prevailingly cationic polyelectrolyte with isoelectric point of about 10. At pH 7.4 it is zwitterionic with an average of 0.55 excess positive charges per unit, notwithstanding it is highly biocompatible. In this work, it was found that AGMA1 surface-adsorbed on cell culturing coverslips exhibits excellent properties as adhesion and proliferation promoter of primary brain cells such as microglia, as well as of hippocampal neurons and astrocytes. Microglia cells cultured on AGMA1-coated coverslips substrate displayed the typical resting, ramified morphology of those cultured on poly-L-lysine and poly-L-ornithine, employed as reference substrates. Mixed cultures of primary astrocytes and neuronal cells grown on AGMA1- and poly-L-lysine coated coverslips were morphologically undistinguishable. On both substrates, neurons differentiated axon and dendrites and eventually established perfectly functional synaptic contacts. Quantitative immunocytochemical staining revealed no difference between AGMA1 and poly-L-lysine. Electrophysiological experiments allowed recording neuron spontaneous activity on AGMA1. In addition, cell cultures on both AGMA1 and PLL displayed comparable excitatory and inhibitory neurotransmission, demonstrating that the synaptic contacts formed were fully functional.
Collapse
Affiliation(s)
- Noemi Tonna
- NeuroZone, Viale Ortles 22/4, I-20129 Milano, Italy
| | - Fabio Bianco
- NeuroZone, Viale Ortles 22/4, I-20129 Milano, Italy
| | - Michela Matteoli
- Department of Medical Biotechnologies and Translational Medicine, Humanitas Clinical and Research Center, Università degli Studi di Milano, Via Manzoni 113, I-20089 Rozzano, Milano, Italy
| | - Cinzia Cagnoli
- Department of Medical Biotechnologies and Translational Medicine, Humanitas Clinical and Research Center, Università degli Studi di Milano, Via Manzoni 113, I-20089 Rozzano, Milano, Italy
| | | | - Amedea Manfredi
- Department of Chemistry, Università degli Studi di Milano, Via C. Golgi 19, I-20133 Milano, Italy
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti 9, I-50121 Firenze, Italy
| | - Nicolò Mauro
- Department of Chemistry, Università degli Studi di Milano, Via C. Golgi 19, I-20133 Milano, Italy
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti 9, I-50121 Firenze, Italy
| | - Elisabetta Ranucci
- Department of Chemistry, Università degli Studi di Milano, Via C. Golgi 19, I-20133 Milano, Italy
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti 9, I-50121 Firenze, Italy
| | - Paolo Ferruti
- Department of Chemistry, Università degli Studi di Milano, Via C. Golgi 19, I-20133 Milano, Italy
- Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Via G. Giusti 9, I-50121 Firenze, Italy
| |
Collapse
|
28
|
Bezzi P, Volterra A. Identification and staining of distinct populations of secretory organelles in astrocytes. Cold Spring Harb Protoc 2014; 2014:2014/5/pdb.prot081703. [PMID: 24786508 DOI: 10.1101/pdb.prot081703] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Increasing evidence indicates that astrocytes, the most abundant glial cell type in the brain, respond to an elevation in cytoplasmic calcium concentration ([Ca(2+)]i) by releasing chemical transmitters (also called gliotransmitters) via regulated exocytosis of heterogeneous classes of organelles. By this process, astrocytes exert modulatory influences on neighboring cells and are thought to participate in the control of synaptic circuits and cerebral blood flow. Studying the properties of exocytosis in astrocytes is a challenge, because the cell biological basis of this process is incompletely defined. Astrocytic exocytosis involves multiple populations of secretory vesicles, including synaptic-like microvesicles (SLMVs), dense-core granules (DCGs), and lysosomes. Here we summarize the available information for identifying individual populations of secretory organelles in astrocytes, including DCGs, SLMVs, and lysosomes, and present experimental procedures for specifically staining such populations.
Collapse
|
29
|
Vardjan N, Kreft M, Zorec R. Regulated Exocytosis in Astrocytes is as Slow as the Metabolic Availability of Gliotransmitters: Focus on Glutamate and ATP. GLUTAMATE AND ATP AT THE INTERFACE OF METABOLISM AND SIGNALING IN THE BRAIN 2014; 11:81-101. [DOI: 10.1007/978-3-319-08894-5_5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
30
|
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.
Collapse
|
31
|
Potokar M, Vardjan N, Stenovec M, Gabrijel M, Trkov S, Jorgačevski J, Kreft M, Zorec R. Astrocytic vesicle mobility in health and disease. Int J Mol Sci 2013; 14:11238-58. [PMID: 23712361 PMCID: PMC3709730 DOI: 10.3390/ijms140611238] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 04/26/2013] [Accepted: 05/08/2013] [Indexed: 12/14/2022] Open
Abstract
Astrocytes are no longer considered subservient to neurons, and are, instead, now understood to play an active role in brain signaling. The intercellular communication of astrocytes with neurons and other non-neuronal cells involves the exchange of molecules by exocytotic and endocytotic processes through the trafficking of intracellular vesicles. Recent studies of single vesicle mobility in astrocytes have prompted new views of how astrocytes contribute to information processing in nervous tissue. Here, we review the trafficking of several types of membrane-bound vesicles that are specifically involved in the processes of (i) intercellular communication by gliotransmitters (glutamate, adenosine 5′-triphosphate, atrial natriuretic peptide), (ii) plasma membrane exchange of transporters and receptors (EAAT2, MHC-II), and (iii) the involvement of vesicle mobility carrying aquaporins (AQP4) in water homeostasis. The properties of vesicle traffic in astrocytes are discussed in respect to networking with neighboring cells in physiologic and pathologic conditions, such as amyotrophic lateral sclerosis, multiple sclerosis, and states in which astrocytes contribute to neuroinflammatory conditions.
Collapse
Affiliation(s)
- Maja Potokar
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Matjaž Stenovec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Mateja Gabrijel
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Saša Trkov
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Jernej Jorgačevski
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
| | - Marko Kreft
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
- Biotechnical Faculty, University of Ljubljana, Večna pot 111, 1000 Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška 4, 1000 Ljubljana, Slovenia; E-Mails: (M.P.); (N.V.); (M.S.); (M.G.); (S.T.); (J.J.); (M.K.)
- Celica Biomedical Center, Tehnološki park 24, 1000 Ljubljana, Slovenia
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +386-1543-7020; Fax: +386-1543-7036
| |
Collapse
|
32
|
Rojas H, Colina C, Ramos M, Benaim G, Jaffe E, Caputo C, Di Polo R. Sodium-calcium exchanger modulates the L-glutamate Ca(i) (2+) signalling in type-1 cerebellar astrocytes. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 961:267-74. [PMID: 23224886 DOI: 10.1007/978-1-4614-4756-6_22] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
We have previously demonstrated that rat type-1 cerebellar astrocytes express a very active Na(+)/Ca(2+) exchanger which accounts for most of the total plasma membrane Ca(2+) fluxes and for the clearance of Ca (i) (2+) induced by physiological agonist. In this chapter, we have explored the mechanism by which the reverse Na(+)/Ca(2+) exchange is involved in agonist-induced Ca(2+) signalling in rat cerebellar astrocytes. Laser-scanning confocal microscopy experiments using immunofluorescence labelling of Na(+)/Ca(2+) exchanger and RyRs demonstrated that they are highly co-localized. The most important finding presented in this chapter is that L-glutamate activates the reverse mode of the Na(+)/Ca(2+) exchange by inducing a Na(+) entry through the electrogenic Na(+)-glutamate co-transporter and not through the ionophoric L-glutamate receptors as confirmed by pharmacological experiments with specific blockers of ionophoric L-glutamate receptors, electrogenic glutamate transporters and the Na/Ca exchange.
Collapse
Affiliation(s)
- Héctor Rojas
- Laboratorio de Fisiología Celular, Centro de Biofísica, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | | | | | | | | | | | | |
Collapse
|
33
|
Thouvenot E, Urbach S, Vigy O, Séveno M, Galéotti N, Nguyen G, Bockaert J, Marin P. Quantitative proteomic analysis reveals protein expression changes in the murine neuronal secretome during apoptosis. J Proteomics 2012; 77:394-405. [DOI: 10.1016/j.jprot.2012.09.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2012] [Revised: 08/24/2012] [Accepted: 09/12/2012] [Indexed: 01/08/2023]
|
34
|
Bianco F, Tonna N, Lovchik RD, Mastrangelo R, Morini R, Ruiz A, Delamarche E, Matteoli M. Overflow Microfluidic Networks: Application to the Biochemical Analysis of Brain Cell Interactions in Complex Neuroinflammatory Scenarios. Anal Chem 2012; 84:9833-40. [DOI: 10.1021/ac302094z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Fabio Bianco
- Neuro-Zone s.r.l., viale Ortles 22/4, 20139 Milano, Italy
| | - Noemi Tonna
- Neuro-Zone s.r.l., viale Ortles 22/4, 20139 Milano, Italy
| | | | | | - Raffaella Morini
- Fondazione Filarete, viale
Ortles 22/4, 20139 Milano, Italy
- Humanitas Clinical and Research Center, Rozzano, Italy
| | - Ana Ruiz
- Fondazione Filarete, viale
Ortles 22/4, 20139 Milano, Italy
- Department of Medical Biotechnology
and Translational Medicine, University of Milano, Milano, Italy
| | | | - Michela Matteoli
- Department of Medical Biotechnology
and Translational Medicine, University of Milano, Milano, Italy
- Humanitas Clinical and Research Center, Rozzano, Italy
| |
Collapse
|
35
|
Liu QS, Xu Q, Kang J, Nedergaard M. Astrocyte activation of presynaptic metabotropic glutamate receptors modulates hippocampal inhibitory synaptic transmission. ACTA ACUST UNITED AC 2012; 1:307-16. [PMID: 16755304 PMCID: PMC1474019 DOI: 10.1017/s1740925x05000190] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the CNS, fine processes of astrocytes often wrap around dendrites, axons and synapses, which provides an interface where neurons and astrocytes might interact. We have reported previously that selective Ca(2+) elevation in astrocytes, by photolysis of caged Ca(2+) by o-nitrophenyl-EGTA (NP-EGTA), causes a kainite receptor-dependent increase in the frequency of spontaneous inhibitory post-synaptic potentials (sIPSCs) in neighboring interneurons in hippocampal slices. However, tetrodotoxin (TTX), which blocks action potentials, reduces the frequency of miniature IPSCs (mIPSCs) in interneurons during Ca(2+) uncaging by an unknown presynaptic mechanism. In this study we investigate the mechanism underlying the presynaptic inhibition. We show that Ca(2+) uncaging in astrocytes is accompanied by a decrease in the amplitude of evoked IPSCs (eIPSCs) in neighboring interneurons. The decreases in eIPSC amplitude and mIPSC frequency are prevented by CPPG, a group II/III metabotropic glutamate receptor (mGluR) antagonist, but not by the AMPA/kainate and NMDA receptor antagonists CNQX/CPP. Application of either the group II mGluR agonist DCG IV or the group III mGluR agonist L-AP4 decreased the amplitude of eIPSCs by a presynaptic mechanism, and both effects are blocked by CPPG. Thus, activation of mGluRs mediates the effects of Ca(2+) uncaging on mIPSCs and eIPSCs. Our results indicate that Ca(2+)-dependent release of glutamate from astrocytes can activate distinct classes of glutamate receptors and differentially modulate inhibitory synaptic transmission in hippocampal interneurons.
Collapse
Affiliation(s)
- Qing-Song Liu
- Center for Aging and Developmental Biology University of Rochester, NY, USA
| | | | | | | |
Collapse
|
36
|
Yin P, Knolhoff AM, Rosenberg HJ, Millet LJ, Gillette MU, Sweedler JV. Peptidomic analyses of mouse astrocytic cell lines and rat primary cultured astrocytes. J Proteome Res 2012; 11:3965-73. [PMID: 22742998 DOI: 10.1021/pr201066t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Astrocytes play an active role in the modulation of synaptic transmission by releasing cell-cell signaling molecules in response to various stimuli that evoke a Ca2+ increase. We expand on recent studies of astrocyte intracellular and secreted proteins by examining the astrocyte peptidome in mouse astrocytic cell lines and rat primary cultured astrocytes, as well as those peptides secreted from mouse astrocytic cell lines in response to Ca2+-dependent stimulations. We identified 57 peptides derived from 24 proteins with LC-MS/MS and CE-MS/MS in the astrocytes. Among the secreted peptides, four peptides derived from elongation factor 1, macrophage migration inhibitory factor, peroxiredoxin-5, and galectin-1 were putatively identified by mass-matching to peptides confirmed to be found in astrocytes. Other peptides in the secretion study were mass-matched to those found in prior peptidomics analyses on mouse brain tissue. Complex peptide profiles were observed after stimulation, suggesting that astrocytes are actively involved in peptide secretion. Twenty-six peptides were observed in multiple stimulation experiments but not in controls and thus appear to be released in a Ca2+-dependent manner. These results can be used in future investigations to better understand stimulus-dependent mechanisms of astrocyte peptide secretion.
Collapse
Affiliation(s)
- Ping Yin
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | | | | | | | | | | |
Collapse
|
37
|
Santello M, Calì C, Bezzi P. Gliotransmission and the tripartite synapse. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 970:307-31. [PMID: 22351062 DOI: 10.1007/978-3-7091-0932-8_14] [Citation(s) in RCA: 145] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
In the last years, the classical view of glial cells (in particular of astrocytes) as a simple supportive cell for neurons has been replaced by a new vision in which glial cells are active elements of the brain. Such a new vision is based on the existence of a bidirectional communication between astrocytes and neurons at synaptic level. Indeed, perisynaptic processes of astrocytes express active G-protein-coupled receptors that are able (1) to sense neurotransmitters released from the synapse during synaptic activity, (2) to increase cytosolic levels of calcium, and (3) to stimulate the release of gliotransmitters that in turn can interact with the synaptic elements. The mechanism(s) by which astrocytes can release gliotransmitter has been extensively studied during the last years. Many evidences have suggested that a fraction of astrocytes in situ release neuroactive substances both with calcium-dependent and calcium-independent mechanism(s); whether these mechanisms coexist and under what physiological or pathological conditions they occur, it remains unclear. However, the calcium-dependent exocytotic vesicular release has received considerable attention due to its potential to occur under physiological conditions via a finely regulated way. By releasing gliotransmitters in millisecond time scale with a specific vesicular apparatus, astrocytes can integrate and process synaptic information and control or modulate synaptic transmission and plasticity.
Collapse
Affiliation(s)
- Mirko Santello
- DBCM, Department of Physiology, University of Bern, Bühlplatz 5, 3012 Bern, Switzerland
| | | | | |
Collapse
|
38
|
Exocytosis in astrocytes: transmitter release and membrane signal regulation. Neurochem Res 2012; 37:2351-63. [PMID: 22528833 DOI: 10.1007/s11064-012-0773-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 03/28/2012] [Accepted: 03/29/2012] [Indexed: 12/14/2022]
Abstract
Astrocytes, a type of glial cells in the brain, are eukaryotic cells, and a hallmark of these are subcellular organelles, such as secretory vesicles. In neurons vesicles play a key role in signaling. Upon a stimulus-an increase in cytosolic concentration of free Ca(2+) ([Ca(2+)](i))-the membrane of vesicle fuses with the presynaptic plasma membrane, allowing the exit of neurotransmitters into the extracellular space and their diffusion to the postsynaptic receptors. For decades it was thought that such vesicle-based mechanisms of gliotransmitter release were not present in astrocytes. However, in the last 30 years experimental evidence showed that astrocytes are endowed with mechanisms for vesicle- and non-vesicle-based gliotransmitter release mechanisms. The aim of this review is to focus on exocytosis, which may play a role in gliotransmission and also in other forms of cell-to-cell communication, such as the delivery of transporters, ion channels and antigen presenting molecules to the cell surface.
Collapse
|
39
|
Verkhratsky A, Rodríguez JJ, Parpura V. Neurotransmitters and integration in neuronal-astroglial networks. Neurochem Res 2012; 37:2326-38. [PMID: 22476701 DOI: 10.1007/s11064-012-0765-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 03/18/2012] [Accepted: 03/22/2012] [Indexed: 10/28/2022]
Abstract
Two major neural cell types, glia, astrocytes in particular, and neurones can release chemical transmitters that act as soluble signalling compounds for intercellular communication. Exocytosis, a process which depends on an increase in cytosolic Ca(2+) levels, represents a common denominator for release of neurotransmitters, stored in secretory vesicles, from these neural cells. While neurones rely predominately on the immediate entry of Ca(2+) from the extracellular space to the cytosol in this process, astrocytes support their cytosolic Ca(2+) increases by appropriating this ion from the intracellular endoplasmic reticulum store and extracellular space. Additionally, astrocytes can release neurotransmitters using a variety of non-vesicular pathways which are mediated by an assortment of plasmalemmal channels and transporters. Once a neuronal and/or astrocytic neurotransmitter is released into the extracellular space, it can activate plasma membrane neurotransmitter receptors on neural cells, causing autocrine and/or paracrine signalling. Moreover, chemical transmission is essential not only for homocellular, but also for heterocellular bi-directional communication in the brain. Further detailed understanding of chemical transmission will aid our comprehension of the brain (dys)function in heath and disease.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK.
| | | | | |
Collapse
|
40
|
Abstract
Astroglial cells, due to their passive electrical properties, were long considered subservient to neurons and to merely provide the framework and metabolic support of the brain. Although astrocytes do play such structural and housekeeping roles in the brain, these glial cells also contribute to the brain's computational power and behavioural output. These more active functions are endowed by the Ca2+-based excitability displayed by astrocytes. An increase in cytosolic Ca2+ levels in astrocytes can lead to the release of signalling molecules, a process termed gliotransmission, via the process of regulated exocytosis. Dynamic components of astrocytic exocytosis include the vesicular-plasma membrane secretory machinery, as well as the vesicular traffic, which is governed not only by general cytoskeletal elements but also by astrocyte-specific IFs (intermediate filaments). Gliotransmitters released into the ECS (extracellular space) can exert their actions on neighbouring neurons, to modulate synaptic transmission and plasticity, and to affect behaviour by modulating the sleep homoeostat. Besides these novel physiological roles, astrocytic Ca2+ dynamics, Ca2+-dependent gliotransmission and astrocyte–neuron signalling have been also implicated in brain disorders, such as epilepsy. The aim of this review is to highlight the newer findings concerning Ca2+ signalling in astrocytes and exocytotic gliotransmission. For this we report on Ca2+ sources and sinks that are necessary and sufficient for regulating the exocytotic release of gliotransmitters and discuss secretory machinery, secretory vesicles and vesicle mobility regulation. Finally, we consider the exocytotic gliotransmission in the modulation of synaptic transmission and plasticity, as well as the astrocytic contribution to sleep behaviour and epilepsy.
Collapse
|
41
|
Verderio C, Cagnoli C, Bergami M, Francolini M, Schenk U, Colombo A, Riganti L, Frassoni C, Zuccaro E, Danglot L, Wilhelm C, Galli T, Canossa M, Matteoli M. TI-VAMP/VAMP7 is the SNARE of secretory lysosomes contributing to ATP secretion from astrocytes. Biol Cell 2012; 104:213-28. [PMID: 22188132 DOI: 10.1111/boc.201100070] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 12/05/2011] [Indexed: 11/26/2022]
Abstract
BACKGROUND INFORMATION ATP is the main transmitter stored and released from astrocytes under physiological and pathological conditions. Morphological and functional evidence suggest that besides secretory granules, secretory lysosomes release ATP. However, the molecular mechanisms involved in astrocytic lysosome fusion remain still unknown. RESULTS In the present study, we identify tetanus neurotoxin-insensitive vesicle-associated membrane protein (TI-VAMP, also called VAMP7) as the vesicular SNARE which mediates secretory lysosome exocytosis, contributing to release of both ATP and cathepsin B from glial cells. We also demonstrate that fusion of secretory lysosomes is triggered by slow and locally restricted calcium elevations, distinct from calcium spikes which induce the fusion of glutamate-containing clear vesicles. Downregulation of TI-VAMP/VAMP7 expression inhibited the fusion of ATP-storing vesicles and ATP-mediated calcium wave propagation. TI-VAMP/VAMP7 downregulation also significantly reduced secretion of cathepsin B from glioma. CONCLUSIONS Given that sustained ATP release from glia upon injury greatly contributes to secondary brain damage and cathepsin B plays a critical role in glioma dissemination, TI-VAMP silencing can represent a novel strategy to control lysosome fusion in pathological conditions.
Collapse
Affiliation(s)
- Claudia Verderio
- Department of Medical Pharmacology and CNR Institute of Neuroscience, Università di Milano, 20129 Milan, Italy.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
42
|
Cellular Mechanisms for the Biogenesis and Transport of Synaptic and Dense-Core Vesicles. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 299:27-115. [DOI: 10.1016/b978-0-12-394310-1.00002-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
|
43
|
Ormel L, Stensrud MJ, Bergersen LH, Gundersen V. VGLUT1 is localized in astrocytic processes in several brain regions. Glia 2011; 60:229-38. [DOI: 10.1002/glia.21258] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 09/26/2011] [Indexed: 01/26/2023]
|
44
|
Prada I, Marchaland J, Podini P, Magrassi L, D'Alessandro R, Bezzi P, Meldolesi J. REST/NRSF governs the expression of dense-core vesicle gliosecretion in astrocytes. ACTA ACUST UNITED AC 2011; 193:537-49. [PMID: 21536750 PMCID: PMC3087003 DOI: 10.1083/jcb.201010126] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The REST/NRSF transcriptional repressor prevents cultured astrocytes from forming DCVs, and its variable expression in human brain cortex astrocytes may account for their functional heterogeneity. Astrocytes are the brain nonnerve cells that are competent for gliosecretion, i.e., for expression and regulated exocytosis of clear and dense-core vesicles (DCVs). We investigated whether expression of astrocyte DCVs is governed by RE-1–silencing transcription factor (REST)/neuron-restrictive silencer factor (NRSF), the transcription repressor that orchestrates nerve cell differentiation. Rat astrocyte cultures exhibited high levels of REST and expressed neither DCVs nor their markers (granins, peptides, and membrane proteins). Transfection of a dominant-negative construct of REST induced the appearance of DCVs filled with secretogranin 2 and neuropeptide Y (NPY) and distinct from other organelles. Total internal reflection fluorescence analysis revealed NPY–monomeric red fluorescent protein–labeled DCVs to undergo Ca2+-dependent exocytosis, which was largely prevented by botulinum toxin B. In the I–II layers of the human temporal brain cortex, all neurons and microglia exhibited the expected inappreciable and high levels of REST, respectively. In contrast, astrocyte REST was variable, going from inappreciable to high, and accompanied by a variable expression of DCVs. In conclusion, astrocyte DCV expression and gliosecretion are governed by REST. The variable in situ REST levels may contribute to the well-known structural/functional heterogeneity of astrocytes.
Collapse
Affiliation(s)
- Ilaria Prada
- San Raffaele Scientific Institute, 20132 Milan, Italy
| | | | | | | | | | | | | |
Collapse
|
45
|
Hydrogel for Cell Housing in the Brain and in the Spinal Cord. Int J Artif Organs 2011; 34:295-303. [DOI: 10.5301/ijao.2011.6488] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/09/2010] [Indexed: 01/08/2023]
Abstract
Purpose Neurons in the adult mammalian central nervous system do not proliferate or renew themselves and consequently strong interest in cell replacement therapies to repair brain and spinal cord damages has emerged in the last decade. Methods An injectable resorbable hydrogel with a controlled nanostructure, specifically designed for neural cell housing, was developed together with a new protocol for building three-dimensional (3D) biohybrid cell/hydrogel constructs: cells are housed within the polymeric matrix which is directly built with a specific cell culture media. This matrix was tested with standard glial populations, primary astrocytes and mesenchymal stem cells. Results Physico-chemical characterization of the hydrogel matrix confirmed a 2- week (+ 2 days) stability before massive degradation; mean mesh size of about 5 nm and thixotropic behavior with transition yield stress at 60+5 Pa. Cell survival within the hydrogel resulted in about 55±5% (minimum value) survivals, data also confirmed by optical assessments. Cell viability also remained high after extraction from the gel, indicating survival to inclusion latency period. Conclusions Since the intimate structure of the gel mimics extracellular matrix cells as would be expected to be found in an in vivo context, this polymeric formulation is a promising base for building 3D constructs for neural cell housing, in which cells are embedded and kept alive directly from the time of polycondensation.
Collapse
|
46
|
Miyazaki T, Yamasaki M, Uchigashima M, Matsushima A, Watanabe M. Cellular expression and subcellular localization of secretogranin II in the mouse hippocampus and cerebellum. Eur J Neurosci 2010; 33:82-94. [PMID: 21044184 DOI: 10.1111/j.1460-9568.2010.07472.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Secretogranin II (SgII), or chromogranin C, is thought to participate in the sorting and packaging of peptide hormones and neuropeptides into secretory granules and large dense-core vesicle (LDCVs), and also functions as a precursor of neuropeptide secretoneurin. Although SgII is widely distributed in the brain and is predominantly localized at terminals of mossy fibers in the hippocampus and cerebellum and climbing fibers in the cerebellum, its cellular expression and ultrastructural localization remain largely unknown. In the present study, we addressed this issue in the adult mouse brain by multiple-labeling fluorescence in situ hybridization and immunofluorescence and by preembedding and postembedding immunoelectron microscopies. SgII was expressed in various neurons, distributed as either tiny puncta or coarse aggregates in the neuropil, and intensely accumulated in perikarya of particular neurons, such as parvalbumin-positive interneurons and mossy cells in the hippocampus and Purkinje cells in the cerebellum. Coarse aggregates were typical of terminals of mossy fibers and climbing fibers. In these terminals, numerous immunogold particles were clustered on individual LDCVs, and one or two particles also fell within small synaptic vesicle-accumulating portions. SgII was further detected as tiny puncta in neural elements lacking LDCVs, such as parallel fibers of cerebellar granule cells, somatodendritic elements of various neurons and Bergmann glia. Thus, SgII is present in LDCV and non-LDCV compartments of various neural cells. The wide subcellular localization of SgII may reflect diverse release sites of neuropeptides and secretorneurin, or suggests its role in the sorting and packaging of molecules other than neuropeptides in non-LDCV compartments.
Collapse
Affiliation(s)
- Taisuke Miyazaki
- Department of Anatomy, Hokkaido University School of Medicine, Sapporo, Japan
| | | | | | | | | |
Collapse
|
47
|
Perrotta C, Bizzozero L, Cazzato D, Morlacchi S, Assi E, Simbari F, Zhang Y, Gulbins E, Bassi MT, Rosa P, Clementi E. Syntaxin 4 is required for acid sphingomyelinase activity and apoptotic function. J Biol Chem 2010; 285:40240-51. [PMID: 20956541 DOI: 10.1074/jbc.m110.139287] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Acid sphingomyelinase (A-SMase) is an important enzyme in sphingolipid metabolism and plays key roles in apoptosis, immunity, development, and cancer. In addition, it mediates cytotoxicity of cisplatin and some other chemotherapeutic drugs. The mechanism of A-SMase activation is still undefined. We now demonstrate that, upon CD95 stimulation, A-SMase is activated through translocation from intracellular compartments to the plasma membrane in an exocytic pathway requiring the t-SNARE protein syntaxin 4. Indeed, down-regulation of syntaxin 4 inhibits A-SMase translocation and activation induced by CD95 stimulation. This leads to inhibition of the CD95-triggered signaling events, including caspase 3 and 9 activation and apoptosis, activation of the survival pathway involving the protein kinase Akt, and important changes in cell cycle and proliferation. The molecular interaction between A-SMase and syntaxin 4 was not known and clarifies the mechanism of A-SMase activation. The novel actions of syntaxin 4 in sphingolipid metabolism and exocytosis we describe here define signaling mechanisms of broad relevance in cell pathophysiology.
Collapse
Affiliation(s)
- Cristiana Perrotta
- Unit of Clinical Pharmacology, Department of Clinical Sciences, University Hospital Luigi Sacco, Università degli Studi di Milano, 20157 Milan, Italy
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
48
|
Hur YS, Kim KD, Paek SH, Yoo SH. Evidence for the existence of secretory granule (dense-core vesicle)-based inositol 1,4,5-trisphosphate-dependent Ca2+ signaling system in astrocytes. PLoS One 2010; 5:e11973. [PMID: 20700485 PMCID: PMC2916839 DOI: 10.1371/journal.pone.0011973] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 07/08/2010] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The gliotransmitters released from astrocytes are deemed to play key roles in the glial cell-neuron communication for normal function of the brain. The gliotransmitters, such as glutamate, ATP, D-serine, neuropeptide Y, are stored in vesicles of astrocytes and secreted following the inositol 1,4,5-trisphosphate (IP3)-induced intracellular Ca2+ releases. Yet studies on the identity of the IP3-dependent intracellular Ca2+ stores remain virtually unexplored. PRINCIPAL FINDINGS We have therefore studied the potential existence of the IP3-sensitive intracellular Ca2+ stores in the cytoplasm of astrocytes using human brain tissue samples in contrast to cultured astrocytes that had primarily been used in the past. It was thus found that secretory granule marker proteins chromogranins and secretogranin II localize in the large dense core vesicles of astrocytes, thereby confirming the large dense core vesicles as bona fide secretory granules. Moreover, consistent with the major IP3-dependent intracellular Ca2+ store role of secretory granules in secretory cells, secretory granules of astrocytes also contained all three (types 1, 2, and 3) IP3R isoforms. SIGNIFICANCE Given that the secretory granule marker proteins chromogranins and secretogranin II are high-capacity, low-affinity Ca2+ storage proteins and chromogranins interact with the IP3Rs to activate the IP3R/Ca2+ channels, i.e., increase both the mean open time and the open probability of the channels, these results imply that secretory granules of astrocytes function as the IP3-sensitive intracellular Ca2+ store.
Collapse
Affiliation(s)
- Yong Suk Hur
- Department of Biochemistry, Inha University School of Medicine, Jung Gu, Incheon, Korea
| | - Ki Deok Kim
- Department of Biochemistry, Inha University School of Medicine, Jung Gu, Incheon, Korea
| | - Sun Ha Paek
- Department of Neurosurgery, Seoul National University College of Medicine, Jongno Gu, Seoul, Korea
| | - Seung Hyun Yoo
- Department of Biochemistry, Inha University School of Medicine, Jung Gu, Incheon, Korea
| |
Collapse
|
49
|
Verkhratsky A, Parpura V, Rodríguez JJ. Where the thoughts dwell: the physiology of neuronal-glial "diffuse neural net". ACTA ACUST UNITED AC 2010; 66:133-51. [PMID: 20546785 DOI: 10.1016/j.brainresrev.2010.05.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 05/11/2010] [Accepted: 05/17/2010] [Indexed: 02/07/2023]
Abstract
The mechanisms underlying the production of thoughts by exceedingly complex cellular networks that construct the human brain constitute the most challenging problem of natural sciences. Our understanding of the brain function is very much shaped by the neuronal doctrine that assumes that neuronal networks represent the only substrate for cognition. These neuronal networks however are embedded into much larger and probably more complex network formed by neuroglia. The latter, although being electrically silent, employ many different mechanisms for intercellular signalling. It appears that astrocytes can control synaptic networks and in such a capacity they may represent an integral component of the computational power of the brain rather than being just brain "connective tissue". The fundamental question of whether neuroglia is involved in cognition and information processing remains, however, open. Indeed, a remarkable increase in the number of glial cells that distinguishes the human brain can be simply a result of exceedingly high specialisation of the neuronal networks, which delegated all matters of survival and maintenance to the neuroglia. At the same time potential power of analogue processing offered by internally connected glial networks may represent the alternative mechanism involved in cognition.
Collapse
|
50
|
Lovchik RD, Bianco F, Tonna N, Ruiz A, Matteoli M, Delamarche E. Overflow Microfluidic Networks for Open and Closed Cell Cultures on Chip. Anal Chem 2010; 82:3936-42. [DOI: 10.1021/ac100771r] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Robert D. Lovchik
- IBM Research—Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland, Neuro-Zone s.r.l., via Fratelli Cervi 93, 20090 Segrate, Italy, Department of Pharmacology, CNR Institute of Neuroscience, University of Milano, via Vanvitelli 32, 20129 Milano, Italy, and Fondazione Filarete, viale Ortles 22/4, 20139 Milano, Italy
| | - Fabio Bianco
- IBM Research—Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland, Neuro-Zone s.r.l., via Fratelli Cervi 93, 20090 Segrate, Italy, Department of Pharmacology, CNR Institute of Neuroscience, University of Milano, via Vanvitelli 32, 20129 Milano, Italy, and Fondazione Filarete, viale Ortles 22/4, 20139 Milano, Italy
| | - Noemi Tonna
- IBM Research—Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland, Neuro-Zone s.r.l., via Fratelli Cervi 93, 20090 Segrate, Italy, Department of Pharmacology, CNR Institute of Neuroscience, University of Milano, via Vanvitelli 32, 20129 Milano, Italy, and Fondazione Filarete, viale Ortles 22/4, 20139 Milano, Italy
| | - Ana Ruiz
- IBM Research—Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland, Neuro-Zone s.r.l., via Fratelli Cervi 93, 20090 Segrate, Italy, Department of Pharmacology, CNR Institute of Neuroscience, University of Milano, via Vanvitelli 32, 20129 Milano, Italy, and Fondazione Filarete, viale Ortles 22/4, 20139 Milano, Italy
| | - Michela Matteoli
- IBM Research—Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland, Neuro-Zone s.r.l., via Fratelli Cervi 93, 20090 Segrate, Italy, Department of Pharmacology, CNR Institute of Neuroscience, University of Milano, via Vanvitelli 32, 20129 Milano, Italy, and Fondazione Filarete, viale Ortles 22/4, 20139 Milano, Italy
| | - Emmanuel Delamarche
- IBM Research—Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland, Neuro-Zone s.r.l., via Fratelli Cervi 93, 20090 Segrate, Italy, Department of Pharmacology, CNR Institute of Neuroscience, University of Milano, via Vanvitelli 32, 20129 Milano, Italy, and Fondazione Filarete, viale Ortles 22/4, 20139 Milano, Italy
| |
Collapse
|