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Velloso FJ, Shankar S, Parpura V, Rakic P, Levison SW. Neural Stem Cells in Adult Mammals are not Astrocytes. ASN Neuro 2022; 14:17590914221134739. [PMID: 36330653 PMCID: PMC9638700 DOI: 10.1177/17590914221134739] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Revised: 09/27/2022] [Accepted: 10/01/2022] [Indexed: 11/06/2022] Open
Abstract
At the turn of the 21st century studies of the cells that resided in the adult mammalian subventricular zone (SVZ) characterized the neural stem cells (NSCs) as a subtype of astrocyte. Over the ensuing years, numerous studies have further characterized the properties of these NSCs and compared them to parenchymal astrocytes. Here we have evaluated the evidence collected to date to establish whether classifying the NSCs as astrocytes is appropriate and useful. We also performed a meta-analysis with 4 previously published datasets that used cell sorting and unbiased single-cell RNAseq to highlight the distinct gene expression profiles of adult murine NSCs and niche astrocytes. On the basis of our understanding of the properties and functions of astrocytes versus the properties and functions of NSCs, and from our comparative transcriptomic analyses we conclude that classifying the adult mammalian NSC as an astrocyte is potentially misleading. From our vantage point, it is more appropriate to refer to the cells in the adult mammalian SVZ that retain the capacity to produce new neurons and macroglia as NSCs without attaching the term "astrocyte-like."
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Affiliation(s)
- Fernando Janczur Velloso
- Department of Pharmacology, Physiology & Neuroscience, New
Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Sandhya Shankar
- Department of Pharmacology, Physiology & Neuroscience, New
Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham,
Birmingham, AL, USA
| | - Pasko Rakic
- Department of Neuroscience, Yale School of Medicine, New Haven, CT,
USA
- Kavli Institute for Neuroscience, Yale School of Medicine, New
Haven, CT, USA
| | - Steven W. Levison
- Department of Pharmacology, Physiology & Neuroscience, New
Jersey Medical School, Rutgers University, Newark, NJ, USA
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2
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Sensing and Regulating Synaptic Activity by Astrocytes at Tripartite Synapse. Neurochem Res 2021; 46:2580-2585. [PMID: 33837868 PMCID: PMC10159683 DOI: 10.1007/s11064-021-03317-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/27/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022]
Abstract
Astrocytes are recognized as more important cells than historically thought in synaptic function through the reciprocal exchange of signaling with the neuronal synaptic elements. The idea that astrocytes are active elements in synaptic physiology is conceptualized in the Tripartite Synapse concept. This review article presents and discusses recent representative examples that highlight the heterogeneity of signaling in tripartite synapse function and its consequences on neural network function and animal behavior.
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3
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Neuroimmune Response Mediated by Cytokines in Natural Scrapie after Chronic Dexamethasone Treatment. Biomolecules 2021; 11:biom11020204. [PMID: 33540568 PMCID: PMC7912810 DOI: 10.3390/biom11020204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 01/27/2021] [Indexed: 01/15/2023] Open
Abstract
The actual role of prion protein-induced glial activation and subsequent cytokine secretion during prion diseases is still incompletely understood. The overall aim of this study is to assess the effect of an anti-inflammatory treatment with dexamethasone on different cytokines released by neuroglial cells that are potentially related to neuroinflammation in natural scrapie. This study emphasizes the complex interactions existent among several pleiotropic neuromodulator peptides and provides a global approach to clarify neuroinflammatory processes in prion diseases. Additionally, an impairment of communication between microglial and astroglial populations mediated by cytokines, mainly IL-1, is suggested. The main novelty of this study is that it is the first one assessing in situ neuroinflammatory activity in relation to chronic anti-inflammatory therapy, gaining relevance because it is based on a natural model. The cytokine profile data would suggest the activation of some neurotoxicity-associated route. Consequently, targeting such a pathway might be a new approach to modify the damaging effects of neuroinflammation.
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4
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Extracellular Alpha-Synuclein Promotes a Neuroinhibitory Secretory Phenotype in Astrocytes. Life (Basel) 2020; 10:life10090183. [PMID: 32911644 PMCID: PMC7555668 DOI: 10.3390/life10090183] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/21/2020] [Accepted: 08/28/2020] [Indexed: 11/16/2022] Open
Abstract
Multiple system atrophy (MSA) and dementia with Lewy bodies (DLB) are α-synucleinopathies that exhibit widespread astrogliosis as a component of the neuroinflammatory response. Munc18, a protein critical to vesicle exocytosis, was previously found to strongly mark morphologically activated astrocytes in brain tissue of MSA patients. Immunofluorescence of MSA, DLB and normal brain tissue sections was combined with cell culture and co-culture experiments to investigate the relationship between extracellular α-synuclein and the transition to a secretory astrocyte phenotype. Increased Munc18-positive vesicles were resolved in activated astrocytes in MSA and DLB tissue compared to controls, and they were also significantly upregulated in the human 1321N1 astrocytoma cell line upon treatment with α-synuclein, with parallel increases in GFAP expression and IL-6 secretion. In co-culture experiments, rat primary astrocytes pretreated with α-synuclein inhibited the growth of neurites of co-cultured primary rat neurons and upregulated chondroitin sulphate proteoglycan. Taken together, these results indicate that the secretory machinery is significantly upregulated in the astrocyte response to extracellular α-synuclein and may participate in the release of neuroinhibitory and proinflammatory factors in α-synucleinopathies.
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5
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Belle MDC, Diekman CO. Neuronal oscillations on an ultra-slow timescale: daily rhythms in electrical activity and gene expression in the mammalian master circadian clockwork. Eur J Neurosci 2018; 48:2696-2717. [PMID: 29396876 DOI: 10.1111/ejn.13856] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 01/16/2018] [Accepted: 01/28/2018] [Indexed: 12/17/2022]
Abstract
Neuronal oscillations of the brain, such as those observed in the cortices and hippocampi of behaving animals and humans, span across wide frequency bands, from slow delta waves (0.1 Hz) to ultra-fast ripples (600 Hz). Here, we focus on ultra-slow neuronal oscillators in the hypothalamic suprachiasmatic nuclei (SCN), the master daily clock that operates on interlocking transcription-translation feedback loops to produce circadian rhythms in clock gene expression with a period of near 24 h (< 0.001 Hz). This intracellular molecular clock interacts with the cell's membrane through poorly understood mechanisms to drive the daily pattern in the electrical excitability of SCN neurons, exhibiting an up-state during the day and a down-state at night. In turn, the membrane activity feeds back to regulate the oscillatory activity of clock gene programs. In this review, we emphasise the circadian processes that drive daily electrical oscillations in SCN neurons, and highlight how mathematical modelling contributes to our increasing understanding of circadian rhythm generation, synchronisation and communication within this hypothalamic region and across other brain circuits.
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Affiliation(s)
- Mino D C Belle
- Institute of Clinical and Biomedical Sciences, University of Exeter Medical School, University of Exeter, Exeter, EX4 4PS, UK
| | - Casey O Diekman
- Department of Mathematical Sciences, New Jersey Institute of Technology, Newark, NJ, USA.,Institute for Brain and Neuroscience Research, New Jersey Institute of Technology, Newark, NJ, USA
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6
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Wu XM, Qian C, Zhou YF, Yan YC, Luo QQ, Yung WH, Zhang FL, Jiang LR, Qian ZM, Ke Y. Bi-directionally protective communication between neurons and astrocytes under ischemia. Redox Biol 2017; 13:20-31. [PMID: 28551085 PMCID: PMC5447396 DOI: 10.1016/j.redox.2017.05.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 05/16/2017] [Accepted: 05/19/2017] [Indexed: 01/10/2023] Open
Abstract
The extensive existing knowledge on bi-directional communication between astrocytes and neurons led us to hypothesize that not only ischemia-preconditioned (IP) astrocytes can protect neurons but also IP neurons protect astrocytes from lethal ischemic injury. Here, we demonstrated for the first time that neurons have a significant role in protecting astrocytes from ischemic injury. The cultured medium from IP neurons (IPcNCM) induced a remarkable reduction in LDH and an increase in cell viability in ischemic astrocytes in vitro. Selective neuronal loss by kainic acid injection induced a significant increase in apoptotic astrocyte numbers in the brain of ischemic rats in vivo. Furthermore, TUNEL analysis, DNA ladder assay, and the measurements of ROS, GSH, pro- and anti-apoptotic factors, anti-oxidant enzymes and signal molecules in vitro and/or in vivo demonstrated that IP neurons protect astrocytes by an EPO-mediated inhibition of pro-apoptotic signals, activation of anti-apoptotic proteins via the P13K/ERK/STAT5 pathways and activation of anti-oxidant proteins via up-regulation of anti-oxidant enzymes. We demonstrated the existence of astro-protection by IP neurons under ischemia and proposed that the bi-directionally protective communications between cells might be a common activity in the brain or peripheral organs under most if not all pathological conditions.
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Affiliation(s)
- Xiao-Mei Wu
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, NT, Hong Kong, China; Department of Biochemistry, Institute for Nautical Medicine, Nantong University, Nantong 226001, China
| | - Christopher Qian
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
| | - Yu-Fu Zhou
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, NT, Hong Kong, China; Laboratory of Neuropharmacology, Fudan University School of Pharmacy, 826 Zhang Heng Road, Shanghai 201203, China
| | - Yick-Chun Yan
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
| | - Qian-Qian Luo
- Laboratory of Neuropharmacology, Fudan University School of Pharmacy, 826 Zhang Heng Road, Shanghai 201203, China; Department of Biochemistry, Institute for Nautical Medicine, Nantong University, Nantong 226001, China
| | - Wing-Ho Yung
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
| | - Fa-Li Zhang
- Laboratory of Neuropharmacology, Fudan University School of Pharmacy, 826 Zhang Heng Road, Shanghai 201203, China
| | - Li-Rong Jiang
- Laboratory of Neuropharmacology, Fudan University School of Pharmacy, 826 Zhang Heng Road, Shanghai 201203, China
| | - Zhong Ming Qian
- Laboratory of Neuropharmacology, Fudan University School of Pharmacy, 826 Zhang Heng Road, Shanghai 201203, China.
| | - Ya Ke
- School of Biomedical Sciences, Faculty of Medicine, the Chinese University of Hong Kong, Shatin, NT, Hong Kong, China
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7
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Lutter D, Ullrich F, Lueck JC, Kempa S, Jentsch TJ. Selective transport of neurotransmitters and modulators by distinct volume-regulated LRRC8 anion channels. J Cell Sci 2017; 130:1122-1133. [PMID: 28193731 DOI: 10.1242/jcs.196253] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 01/31/2017] [Indexed: 01/10/2023] Open
Abstract
In response to swelling, mammalian cells release chloride and organic osmolytes through volume-regulated anion channels (VRACs). VRACs are heteromers of LRRC8A and other LRRC8 isoforms (LRRC8B to LRRC8E), which are co-expressed in HEK293 and most other cells. The spectrum of VRAC substrates and its dependence on particular LRRC8 isoforms remains largely unknown. We show that, besides the osmolytes taurine and myo-inositol, LRRC8 channels transport the neurotransmitters glutamate, aspartate and γ-aminobutyric acid (GABA) and the co-activator D-serine. HEK293 cells engineered to express defined subsets of LRRC8 isoforms were used to elucidate the subunit-dependence of transport. Whereas LRRC8D was crucial for the translocation of overall neutral compounds like myo-inositol, taurine and GABA, and sustained the transport of positively charged lysine, flux of negatively charged aspartate was equally well supported by LRRC8E. Disruption of LRRC8B or LRRC8C failed to decrease the transport rates of all investigated substrates, but their inclusion into LRRC8 heteromers influenced the substrate preference of VRAC. This suggested that individual VRACs can contain three or more different LRRC8 subunits, a conclusion confirmed by sequential co-immunoprecipitations. Our work suggests a composition-dependent role of VRACs in extracellular signal transduction.
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Affiliation(s)
- Darius Lutter
- Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany.,Graduate Program of the Freie Universität Berlin, D-14195 Berlin, Germany
| | - Florian Ullrich
- Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany
| | - Jennifer C Lueck
- Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany.,Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany.,Graduate Program of the Freie Universität Berlin, D-14195 Berlin, Germany
| | - Stefan Kempa
- Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany
| | - Thomas J Jentsch
- Leibniz-Institut für Molekulare Pharmakologie (FMP), D-13125 Berlin, Germany .,Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany.,Neurocure, Charité Universitätsmedizin, D-10117 Berlin, Germany
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Souza-Dantas VC, Póvoa P, Bozza F, Soares M, Salluh J. Preventive strategies and potential therapeutic interventions for delirium in sepsis. Hosp Pract (1995) 2016; 44:190-202. [PMID: 27223862 DOI: 10.1080/21548331.2016.1192453] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/18/2016] [Indexed: 06/05/2023]
Abstract
Delirium is the most frequent and severe clinical presentation of brain dysfunction in critically ill septic patients with an incidence ranging from 9% to 71%. Delirium represents a significant burden for patients and relatives, as well as to the health care system, resulting in higher costs, long-term cognitive impairment and significant risk of death after 6 months. Current interventions for the prevention of delirium typically involve early recognition and amelioration of modifiable risk factors and treatment of underlying conditions that predisposes the individual to delirium. Several pharmacological interventions to prevent and treat delirium have been tested, although their effectiveness remains uncertain, especially in larger and more homogeneous subgroups of ICU patients, like in patients with sepsis. To date, there is inconsistent and conflicting data regarding the efficacy of any particular pharmacological agent, thus substantial attention has been paid to non-pharmacological interventions and preventive strategies should be applied to every patient admitted in the ICU. Future trials should be designed to evaluate the impact of these pharmacologic interventions on the prevention and treatment of delirium on clinically relevant outcomes such as length of stay, hospital mortality and long-term cognitive function. The role of specific medications like statins in delirium prevention is also yet to be evaluated.
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Affiliation(s)
| | - Pedro Póvoa
- b Polyvalent Intensive Care Unit, Hospital S. Francisco Xavier , Centro Hospitalar de Lisboa Ocidental (CHLO) , Lisbon , Portugal
- c Nova Medical School , CEDOC, New University of Lisbon , Portugal
| | - Fernando Bozza
- d Oswaldo Cruz Foundation , Rio de Janeiro , Brazil
- e D'Or Institute for Research and Education , Rio de Janeiro , Brazil
| | - Marcio Soares
- e D'Or Institute for Research and Education , Rio de Janeiro , Brazil
| | - Jorge Salluh
- e D'Or Institute for Research and Education , Rio de Janeiro , Brazil
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9
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Jeanson T, Pondaven A, Ezan P, Mouthon F, Charvériat M, Giaume C. Antidepressants Impact Connexin 43 Channel Functions in Astrocytes. Front Cell Neurosci 2016; 9:495. [PMID: 26778961 PMCID: PMC4703821 DOI: 10.3389/fncel.2015.00495] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2015] [Accepted: 12/09/2015] [Indexed: 12/20/2022] Open
Abstract
Glial cells, and in particular astrocytes, are crucial to maintain neuronal microenvironment by regulating energy metabolism, neurotransmitter uptake, gliotransmission, and synaptic development. Moreover, a typical feature of astrocytes is their high expression level of connexins, a family of membrane proteins that form gap junction channels allowing intercellular exchanges and hemichannels that provide release and uptake pathways for neuroactive molecules. Interestingly, several studies have revealed unexpected changes in astrocytes from depressive patients and rodent models of depressive-like behavior. Moreover, changes in the expression level of the astroglial connexin 43 (Cx43) have been reported in a depressive context. On the other hand, antidepressive drugs have also been shown to impact the expression of this connexin in astrocytes. However, so far there is little information concerning the functional consequence of these changes, i.e., the status of gap junctional communication and hemichannel activity in astrocytes exposed to antidepressants. In the present work we focused our attention on the action of seven antidepressants from four different therapeutic classes and tested their effects on Cx43 expression and on the two connexin-based channels functions studied in cultured astrocytes. We here report that when used at non-toxic and clinically relevant concentrations they have no effects on Cx43 expression but differential effects on Cx43 gap junction channels. Moreover, all tested antidepressants inhibit Cx43 hemichannel with different efficiency depending on their therapeutic classe. By studying the impact of antidepressants on the functional status of astroglial connexin channels, contributing to dynamic neuroglial interactions, our observations should help to better understand the mechanism by which these drugs provide their effect in the brain.
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Affiliation(s)
- Tiffany Jeanson
- Collège de France, Center for Interdisciplinary Research in Biology/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050Paris, France; University Pierre et Marie CurieParis, France; MemoLife Laboratory of Excellence and Paris Science Lettre Research UniversityParis, France; TheranexusLyon, France
| | - Audrey Pondaven
- Collège de France, Center for Interdisciplinary Research in Biology/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050Paris, France; University Pierre et Marie CurieParis, France; MemoLife Laboratory of Excellence and Paris Science Lettre Research UniversityParis, France
| | - Pascal Ezan
- Collège de France, Center for Interdisciplinary Research in Biology/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050Paris, France; University Pierre et Marie CurieParis, France; MemoLife Laboratory of Excellence and Paris Science Lettre Research UniversityParis, France
| | | | | | - Christian Giaume
- Collège de France, Center for Interdisciplinary Research in Biology/Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale U1050Paris, France; University Pierre et Marie CurieParis, France; MemoLife Laboratory of Excellence and Paris Science Lettre Research UniversityParis, France
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10
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Evidence for alterations of the glial syncytial function in major depressive disorder. J Psychiatr Res 2016; 72:15-21. [PMID: 26519765 PMCID: PMC5813495 DOI: 10.1016/j.jpsychires.2015.10.010] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 09/25/2015] [Accepted: 10/13/2015] [Indexed: 11/21/2022]
Abstract
BACKGROUND Glial cells are essential in maintaining synaptic function. In glutamatergic synapses astrocytes remove the products of neural activity, (i.e. potassium, glutamate and excess water) from the synaptic cleft and redistribute them across the glial network; these products of neural activity can then be recycled for neuronal use or released into the vascular compartment. This type of highly coupled cell network -or syncytium-maintains the balance of synaptic activity by restoring the basal levels of such molecules in the synaptic cleft. Previous studies have reported alterations of glia related genes in Major Depressive Disorder, including some genes related to syncytial function. METHODS We used RNA isolated from hippocampal tissues of 13 MDD subjects and 10 healthy controls to broadly examine gene expression using microarrays. Hippocampal RNA samples were isolated by laser capture microdissection from human tissue sections carefully avoiding contamination from neighboring structures. Once RNA quality was validated RNA was labeled and hybridized to microarrays. RESULTS Analysis of microarray data identified mRNA transcripts involved in glial syncytial function that were downregulated in MDD subjects compared to controls, including potassium and water channels (KCNJ10, AQP4), gap junction proteins (GJA1) and glutamate transporters (SLC1A2, SLC1A3). These gene expression differences were confirmed by qPCR. CONCLUSIONS The downregulation of these genes related to the syncytial network activity of glial cells is consistent with the hypothesis that synaptic homeostasis is disrupted thereby disrupting hippocampal synaptic function in MDD patients. Such glial gene expression changes could contribute either to the onset or perpetuation of depressive symptoms and hence, represent targets for novel therapeutics.
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Ureshino RP, Rocha KK, Lopes GS, Bincoletto C, Smaili SS. Calcium signaling alterations, oxidative stress, and autophagy in aging. Antioxid Redox Signal 2014; 21:123-37. [PMID: 24512092 DOI: 10.1089/ars.2013.5777] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
SIGNIFICANCE Aging is a multi-factorial process that may be associated with several functional and structural deficits which can evolve into degenerative diseases. In this review, we present data that may depict an expanded view of molecular aging theories, beginning with the idea that reactive oxygen species (ROS) are the major effectors in this process. In addition, we have correlated the importance of autophagy as a neuroprotective mechanism and discussed a link between age-related molecules, Ca(2+) signaling, and oxidative stress. RECENT ADVANCES There is evidence suggesting that alterations in Ca(2+) homeostasis, including mitochondrial Ca(2+) overload and alterations in electron transport chain (ETC) complexes, which increase cell vulnerability, are linked to oxidative stress in aging. As much as Ca(2+) signaling is altered in aged cells, excess ROS can be produced due to an ineffective coupling of mitochondrial respiration. Damaged mitochondria might not be removed by the macroautophagic system, which is hampered in aging by lipofuscin accumulation, boosting ROS generation, damaging DNA, and, ultimately, leading to apoptosis. CRITICAL ISSUES This process can lead to altered protein expression (such as p53, Sirt1, and IGF-1) and progress to cell death. This cycle can lead to increased cell vulnerability in aging and contribute to an increased susceptibility to degenerative processes. FUTURE DIRECTIONS A better understanding of Ca(2+) signaling and molecular aging alterations is important for preventing apoptosis in age-related diseases. In addition, caloric restriction, resveratrol and autophagy modulation appear to be predominantly cytoprotective, and further studies of this process are promising in age-related disease therapeutics.
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12
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Verkhratsky A, Burnstock G. Purinergic and glutamatergic receptors on astroglia. ADVANCES IN NEUROBIOLOGY 2014; 11:55-79. [PMID: 25236724 DOI: 10.1007/978-3-319-08894-5_4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Astroglial cells express many neurotransmitter receptors; the receptors to glutamate and ATP being the most abundant. Here, we provide a concise overview on the expression and main properties of astroglial glutamate receptors (ionotropic receptors represented by AMPA and NMDA subtypes) and metabotropic (mainly mGluR5 and mGluR3 subtypes) and purinoceptors (adenosine receptors of A1, A2A, A2B, and A3 types, ionotropic P2X1/5 and P2X7 subtypes, and metabotropic P2Y purinoceptors). We also discuss the role of these receptors in glial physiology and pathophysiology.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, School of Biological Sciences, The University of Manchester, 1.124 Stopford Building, Oxford Road, Manchester, M13 9PT, UK,
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13
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Zeidán-Chuliá F, Salmina AB, Malinovskaya NA, Noda M, Verkhratsky A, Moreira JCF. The glial perspective of autism spectrum disorders. Neurosci Biobehav Rev 2014; 38:160-72. [DOI: 10.1016/j.neubiorev.2013.11.008] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Revised: 11/03/2013] [Accepted: 11/21/2013] [Indexed: 01/01/2023]
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14
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Glutamine synthetase in astrocytes from entorhinal cortex of the triple transgenic animal model of Alzheimer’s disease is not affected by pathological progression. Biogerontology 2013; 14:777-87. [DOI: 10.1007/s10522-013-9456-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 08/16/2013] [Indexed: 10/26/2022]
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15
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Abstract
Although severe stress can elicit toxicity, mild stress often elicits adaptations. Here we review the literature on stress-induced adaptations versus stress sensitization in models of neurodegenerative diseases. We also describe our recent findings that chronic proteotoxic stress can elicit adaptations if the dose is low but that high-dose proteotoxic stress sensitizes cells to subsequent challenges. In these experiments, long-term, low-dose proteasome inhibition elicited protection in a superoxide dismutase-dependent manner. In contrast, acute, high-dose proteotoxic stress sensitized cells to subsequent proteotoxic challenges by eliciting catastrophic loss of glutathione. However, even in the latter model of synergistic toxicity, several defensive proteins were upregulated by severe proteotoxicity. This led us to wonder whether high-dose proteotoxic stress can elicit protection against subsequent challenges in astrocytes, a cell type well known for their resilience. In support of this new hypothesis, we found that the astrocytes that survived severe proteotoxicity became harder to kill. The adaptive mechanism was glutathione dependent. If these findings can be generalized to the human brain, similar endogenous adaptations may help explain why neurodegenerative diseases are so delayed in appearance and so slow to progress. In contrast, sensitization to severe stress may explain why defenses eventually collapse in vulnerable neurons.
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Affiliation(s)
- Rehana K Leak
- Division of Pharmaceutical Sciences, Mylan School of Pharmacy, Duquesne University
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16
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Seelke AMH, Dooley JC, Krubitzer LA. Differential changes in the cellular composition of the developing marsupial brain. J Comp Neurol 2013; 521:2602-20. [PMID: 23322491 PMCID: PMC3934569 DOI: 10.1002/cne.23301] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2012] [Revised: 09/18/2012] [Accepted: 01/04/2013] [Indexed: 12/27/2022]
Abstract
Throughout development both the body and the brain change at remarkable rates. Specifically, the number of cells in the brain undergoes dramatic nonlinear changes, first exponentially increasing in cell number and then decreasing in cell number. Different cell types, such as neurons and glia, undergo these changes at different stages of development. The current investigation used the isotropic fractionator method to examine the changes in cellular composition at multiple developmental milestones in the short-tailed opossum, Monodelphis domestica. Here we report several novel findings concerning marsupial brain development and organization. First, during the later stages of neurogenesis (P18), neurons make up most of the cells in the neocortex, although the total number of neurons remains the same throughout the life span. In contrast, in the subcortical regions, the number of neurons decreases dramatically after P18, and a converse relationship is observed for nonneuronal cells. In the cerebellum, the total number of cells gradually increases until P180 and then remains constant, and then the number of neurons is consistent across the developmental ages examined. For the three major structures examined, neuronal density and the percentage of neurons within a structure are highest during neurogenesis and then decrease after this point. Finally, the total number of neurons in the opossum brain is relatively low compared with other small-brained mammals such as mice. The relatively low number of neurons and correspondingly high number of nonneurons suggests that in the marsupial brain nonneurons may play a significant role in signal processing.
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Affiliation(s)
- Adele M H Seelke
- Center for Neuroscience, University of California, Davis, Davis, California 95618, USA
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Parpura V, Verkhratsky A. Astrocytes revisited: concise historic outlook on glutamate homeostasis and signaling. Croat Med J 2013; 53:518-28. [PMID: 23275317 PMCID: PMC3541578 DOI: 10.3325/cmj.2012.53.518] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Astroglia is a main type of brain neuroglia, which includes many cell sub-types that differ in their morphology and physiological properties and yet are united by the main function, which is the maintenance of brain homeostasis. Astrocytes employ a variety of mechanisms for communicating with neuronal networks. The communication mediated by neurotransmitter glutamate has received a particular attention. Glutamate is de novo synthesized exclusively in astrocytes; astroglia-derived glutamine is the source of glutamate for neurons. Glutamate is released from both neurons and astroglia through exocytosis, although various other mechanisms may also play a role. Glutamate-activated specific receptors trigger excitatory responses in neurons and astroglia. Here we overview main properties of glutamatergic transmission in neuronal-glial networks and identify some future challenges facing the field.
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Affiliation(s)
- Vladimir Parpura
- Department of Neurobiology, University of Alabama, Birmingham, AL 35294-0021, USA.
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18
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Marutle A, Gillberg PG, Bergfors A, Yu W, Ni R, Nennesmo I, Voytenko L, Nordberg A. ³H-deprenyl and ³H-PIB autoradiography show different laminar distributions of astroglia and fibrillar β-amyloid in Alzheimer brain. J Neuroinflammation 2013; 10:90. [PMID: 23880036 PMCID: PMC3733895 DOI: 10.1186/1742-2094-10-90] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 07/01/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The pathological features in Alzheimer's disease (AD) brain include the accumulation and deposition of β-amyloid (Aβ), activation of astrocytes and microglia and disruption of cholinergic neurotransmission. Since the topographical characteristics of these different pathological processes in AD brain and how these relate to each other is not clear, this motivated further exploration using binding studies in postmortem brain with molecular imaging tracers. This information could aid the development of specific biomarkers to accurately chart disease progression. RESULTS In vitro binding assays demonstrated increased [³H]-PIB (fibrillar Aβ) and [³H]-PK11195 (activated microglia) binding in the frontal cortex (FC) and hippocampus (HIP), as well as increased binding of [³H]-L-deprenyl (activated astrocytes) in the HIP, but a decreased [³H]-nicotine (α4β2 nicotinic acetylcholine receptor (nAChR)) binding in the FC of AD cases compared to age-matched controls. Quantitative autoradiography binding studies were also performed to investigate the regional laminar distributions of [³H]-L-deprenyl, [³H]-PIB as well as [¹²⁵I]-α-bungarotoxin (α7 nAChRs) and [³H]-nicotine in hemisphere brain of a typical AD case. A clear lamination pattern was observed with high [³H]-PIB binding in all layers and [³H]-deprenyl in superficial layers of the FC. In contrast, [³H]-PIB showed low binding to fibrillar Aβ, but [³H]-deprenyl high binding to activated astrocytes throughout the HIP. The [³H]-PIB binding was also low and the [³H]-deprenyl binding high in all layers of the medial temporal gyrus and insular cortex in comparison to the frontal cortex. Low [³H]-nicotine binding was observed in all layers of the frontal cortex in comparison to layers in the medial temporal gyrus, insular cortex and hippocampus. Immunohistochemical detection in the AD case revealed abundant glial fibrillary acidic protein positive (GFAP+) reactive astrocytes and α7 nAChR expressing GFAP+ astrocytes both in the vicinity and surrounding Aβ neuritic plaques in the FC and HIP. Although fewer Aβ plaques were observed in the HIP, some hippocampal GFAP+ astrocytes contained Aβ-positive (6 F/3D) granules within their somata. CONCLUSIONS Astrocytosis shows a distinct regional pattern in AD brain compared to fibrillar Aβ, suggesting that different types of astrocytes may be associated with the pathophysiological processes in AD.
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Affiliation(s)
- Amelia Marutle
- Alzheimer Neurobiology Center, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Novum Floor-5, Stockholm S-14186, Sweden
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Macdonald CL, Silva GA. A positive feedback cell signaling nucleation model of astrocyte dynamics. FRONTIERS IN NEUROENGINEERING 2013; 6:4. [PMID: 23847529 PMCID: PMC3706728 DOI: 10.3389/fneng.2013.00004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2013] [Accepted: 06/10/2013] [Indexed: 11/13/2022]
Abstract
We constructed a model of calcium signaling in astrocyte neural glial cells that incorporates a positive feedback nucleation mechanism, whereby small microdomain increases in local calcium can stochastically produce global cellular and intercellular network scale dynamics. The model is able to simultaneously capture dynamic spatial and temporal heterogeneities associated with intracellular calcium transients in individual cells and intercellular calcium waves (ICW) in spatially realistic networks of astrocytes, i.e., networks where the positions of cells were taken from real in vitro experimental data of spontaneously forming sparse networks, as opposed to artificially constructed grid networks or other non-realistic geometries. This is the first work we are aware of where an intracellular model of calcium signaling that reproduces intracellular dynamics inherently accounts for intercellular network dynamics. These results suggest that a nucleation type mechanism should be further investigated experimentally in order to test its contribution to calcium signaling in astrocytes and in other cells more broadly. It may also be of interest in engineered neuromimetic network systems that attempt to emulate biological signaling and information processing properties in synthetic hardwired neuromorphometric circuits or coded algorithms.
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Parpura V, Verkhratsky A. Astroglial amino acid-based transmitter receptors. Amino Acids 2013; 44:1151-8. [DOI: 10.1007/s00726-013-1458-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Accepted: 01/02/2013] [Indexed: 10/27/2022]
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Parpura V, Verkhratsky A. Astrogliopathology: could nanotechnology restore aberrant calcium signalling and pathological astroglial remodelling? BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2012; 1833:1625-31. [PMID: 23219860 DOI: 10.1016/j.bbamcr.2012.11.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Revised: 11/23/2012] [Accepted: 11/24/2012] [Indexed: 12/19/2022]
Abstract
Pathology of the brain is caused by the deficiency in tissue homeostasis. As the main homeostatic element of the mammalian nervous system is represented by astrocytes, these glial cells are involved in many, if not all, brain disorders. Diseased astrocytes undergo a variety of morphological and functional changes, including deregulation of calcium dynamics. To rectify undesirable changes in astrocytes and/or neurones that occur in disease, we postulate the future use of nanotechnology-based therapeutics. Carbon nanotubes emerged as one of the most promising advanced nanomaterials for use in neuroprosthesis. Recently, they have been used to affect morpho-functional characteristics of astrocytes. This article is part of a Special Issue entitled: 12th European Symposium on Calcium.
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Affiliation(s)
- Vladimir Parpura
- Department of Neurobiology, University of Alabama, Birmingham, AL 35294, USA.
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22
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Astrocytes and developmental plasticity in fragile X. Neural Plast 2012; 2012:197491. [PMID: 22848847 PMCID: PMC3403619 DOI: 10.1155/2012/197491] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 05/25/2012] [Accepted: 05/27/2012] [Indexed: 01/13/2023] Open
Abstract
A growing body of research indicates a pivotal role for astrocytes at the developing synapse. In particular, astrocytes are dynamically involved in governing synapse structure, function, and plasticity. In the postnatal brain, their appearance at synapses coincides with periods of developmental plasticity when neural circuits are refined and established. Alterations in the partnership between astrocytes and neurons have now emerged as important mechanisms that underlie neuropathology. With overall synaptic function standing as a prominent link to the expression of the disease phenotype in a number of neurodevelopmental disorders and knowing that astrocytes influence synapse development and function, this paper highlights the current knowledge of astrocyte biology with a focus on their involvement in fragile X syndrome.
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