1
|
Hayoz S, Jia C, Hegg CC. Constitutive and evoked release of ATP in adult mouse olfactory epithelium. Open Life Sci 2024; 19:20220811. [PMID: 38250473 PMCID: PMC10795008 DOI: 10.1515/biol-2022-0811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/31/2023] [Accepted: 11/28/2023] [Indexed: 01/23/2024] Open
Abstract
In adult olfactory epithelium (OE), ATP plays a role in constant cell turnover and post-injury neuroregeneration. We previously demonstrated that constitutive and ATP-evoked ATP release are present in neonatal mouse OE and underlie continuous cell turn-over and post-injury neuroregeneration, and that activation of purinergic P2X7 receptors is involved in the evoked release. We hypothesized that both releases are present in adult mouse OE. To study the putative contribution of olfactory sensory neurons to ATP release, we used olfactory sensory neuronal-like OP6 cells derived from the embryonic olfactory placode cells. Calcium imaging showed that OP6 cells and primary adult OE cell cultures express functional purinergic receptors. We monitored ATP release from OP6 cells and whole adult OE turbinates using HEK cells as biosensors and luciferin-luciferase assays. Constitutive ATP release occurs in OP6 cells and whole adult mouse OE turbinates, and P2X7 receptors mediated evoked ATP release occurs only in turbinates. The mechanisms of ATP release described in the present study might underlie the constant cell turn-over and post-injury neuroregeneration present in adult OE and thus, further studies of these mechanisms are warranted as it will improve our knowledge of OE tissue homeostasis and post-injury regeneration.
Collapse
Affiliation(s)
- Sébastien Hayoz
- Department of Physiology, University of Arizona, Tucson, Arizona 85724, USA
| | - Cuihong Jia
- Department of Biomedical Sciences, East Tennessee State University, Johnson City, Tennessee 37614, USA
| | - Colleen Cosgrove Hegg
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing, Michigan 48824, USA
| |
Collapse
|
2
|
O'Grady SM, Kita H. ATP functions as a primary alarmin in allergen-induced type 2 immunity. Am J Physiol Cell Physiol 2023; 325:C1369-C1386. [PMID: 37842751 PMCID: PMC10861152 DOI: 10.1152/ajpcell.00370.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 10/09/2023] [Accepted: 10/09/2023] [Indexed: 10/17/2023]
Abstract
Environmental allergens that interact with the airway epithelium can activate cellular stress pathways that lead to the release of danger signals known as alarmins. The mechanisms of alarmin release are distinct from damage-associated molecular patterns (DAMPs), which typically escape from cells after loss of plasma membrane integrity. Oxidative stress represents a form of allergen-induced cellular stress that stimulates oxidant-sensing mechanisms coupled to pathways, which facilitate alarmin mobilization and efflux across the plasma membrane. In this review, we highlight examples of alarmin release and discuss their roles in the initiation of type 2 immunity and allergic airway inflammation. In addition, we discuss the concept of alarmin amplification, where "primary" alarmins, which are directly released in response to a specific cellular stress, stimulate additional signaling pathways that lead to secretion of "secondary" alarmins that include proinflammatory cytokines, such as IL-33, as well as genomic and mitochondrial DNA that coordinate or amplify type 2 immunity. Accordingly, allergen-evoked cellular stress can elicit a hierarchy of alarmin signaling responses from the airway epithelium that trigger local innate immune reactions, impact adaptive immunity, and exacerbate diseases including asthma and other chronic inflammatory conditions that affect airway function.
Collapse
Affiliation(s)
- Scott M O'Grady
- Department of Animal Science, University of Minnesota, St. Paul, Minnesota, United States
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, Minnesota, United States
| | - Hirohito Kita
- Division of Allergy, Asthma and Immunology, Mayo Clinic, Scottsdale, Arizona, United States
| |
Collapse
|
3
|
Caruso G, Di Pietro L, Caraci F. Gap Junctions and Connexins in Microglia-Related Oxidative Stress and Neuroinflammation: Perspectives for Drug Discovery. Biomolecules 2023; 13:biom13030505. [PMID: 36979440 PMCID: PMC10046203 DOI: 10.3390/biom13030505] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 02/28/2023] [Accepted: 03/07/2023] [Indexed: 03/12/2023] Open
Abstract
Microglia represent the immune system of the brain. Their role is central in two phenomena, neuroinflammation and oxidative stress, which are at the roots of different pathologies related to the central nervous system (CNS). In order to maintain the homeostasis of the brain and re-establish the equilibrium after a threatening imbalance, microglia communicate with each other and other cells within the CNS by receiving specific signals through membrane-bound receptors and then releasing neurotrophic factors into either the extracellular milieu or directly into the cytoplasm of nearby cells, such as astrocytes and neurons. These last two mechanisms rely on the activity of protein structures that enable the formation of channels in the membrane, namely, connexins and pannexins, that group and form gap junctions, hemichannels, and pannexons. These channels allow the release of gliotransmitters, such as adenosine triphosphate (ATP) and glutamate, together with calcium ion (Ca2+), that seem to play a pivotal role in inter-cellular communication. The aim of the present review is focused on the physiology of channel protein complexes and their contribution to neuroinflammatory and oxidative stress-related phenomena, which play a central role in neurodegenerative disorders. We will then discuss how pharmacological modulation of these channels can impact neuroinflammatory phenomena and hypothesize that currently available nutraceuticals, such as carnosine and N-acetylcysteine, can modulate the activity of connexins and pannexins in microglial cells and reduce oxidative stress in neurodegenerative disorders.
Collapse
Affiliation(s)
- Giuseppe Caruso
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Unit of Neuropharmacology and Translational Neurosciences, Oasi Research Institute-IRCCS, 94018 Troina, Italy
- Correspondence: ; Tel.: +39-0957385036
| | - Lucia Di Pietro
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Scuola Superiore di Catania, University of Catania, 95123 Catania, Italy
| | - Filippo Caraci
- Department of Drug and Health Sciences, University of Catania, 95123 Catania, Italy
- Unit of Neuropharmacology and Translational Neurosciences, Oasi Research Institute-IRCCS, 94018 Troina, Italy
| |
Collapse
|
4
|
Mughal A, Nelson MT, Hill-Eubanks D. The post-arteriole transitional zone: a specialized capillary region that regulates blood flow within the CNS microvasculature. J Physiol 2023; 601:889-901. [PMID: 36751860 PMCID: PMC9992301 DOI: 10.1113/jp282246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/13/2023] [Indexed: 02/09/2023] Open
Abstract
The brain is an energy hog, consuming available energy supplies at a rate out of all proportion to its relatively small size. This outsized demand, largely reflecting the unique computational activity of the brain, is met by an ensemble of neurovascular coupling mechanisms that link neuronal activity with local increases in blood delivery. This just-in-time replenishment strategy, made necessary by the limited energy-storage capacity of neurons, complicates the nutrient-delivery task of the cerebral vasculature, layering on a temporo-spatial requirement that invites - and challenges - mechanistic interpretation. The centre of gravity of research efforts to disentangle these mechanisms has shifted from an initial emphasis on astrocyte-arteriole-level processes to mechanisms that operate on the capillary level, a shift that has brought into sharp focus questions regarding the fine control of blood distribution to active neurons. As these investigations have drilled down into finer reaches of the microvasculature, they have revealed an arteriole-proximate subregion of CNS capillary networks that serves a regulatory function in directing blood flow into and within downstream capillaries. They have also illuminated differences in researchers' perspectives on the vascular structures and identity of mural cells in this region that impart the vasomodulatory effects that control blood distribution. In this review, we highlight the regulatory role of a variably named region of the microvasculature, referred to here as the post-arteriole transition zone, in channeling blood flow within CNS capillary networks, and underscore the contribution of dynamically contractile perivascular mural cell - generally, but not universally, recognized as pericytes - to this function.
Collapse
Affiliation(s)
- Amreen Mughal
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
| | - Mark T. Nelson
- Department of Pharmacology, University of Vermont, Burlington, VT, USA
- Division of Cardiovascular Sciences, University of Manchester, Manchester, UK
| | | |
Collapse
|
5
|
Monzón-Sandoval J, Burlacu E, Agarwal D, Handel AE, Wei L, Davis J, Cowley SA, Cader MZ, Webber C. Lipopolysaccharide distinctively alters human microglia transcriptomes to resemble microglia from Alzheimer's disease mouse models. Dis Model Mech 2022; 15:277958. [PMID: 36254682 PMCID: PMC9612871 DOI: 10.1242/dmm.049349] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 08/30/2022] [Indexed: 01/15/2023] Open
Abstract
Alzheimer's disease (AD) is the most common form of dementia, and risk-influencing genetics implicates microglia and neuroimmunity in the pathogenesis of AD. Induced pluripotent stem cell (iPSC)-derived microglia (iPSC-microglia) are increasingly used as a model of AD, but the relevance of historical immune stimuli to model AD is unclear. We performed a detailed cross-comparison over time on the effects of combinatory stimulation of iPSC-microglia, and in particular their relevance to AD. We used single-cell RNA sequencing to measure the transcriptional response of iPSC-microglia after 24 h and 48 h of stimulation with prostaglandin E2 (PGE2) or lipopolysaccharide (LPS)+interferon gamma (IFN-γ), either alone or in combination with ATPγS. We observed a shared core transcriptional response of iPSC-microglia to ATPγS and to LPS+IFN-γ, suggestive of a convergent mechanism of action. Across all conditions, we observed a significant overlap, although directional inconsistency to genes that change their expression levels in human microglia from AD patients. Using a data-led approach, we identify a common axis of transcriptomic change across AD genetic mouse models of microglia and show that only LPS provokes a transcriptional response along this axis in mouse microglia and LPS+IFN-γ in human iPSC-microglia. This article has an associated First Person interview with the first author of the paper.
Collapse
Affiliation(s)
| | - Elena Burlacu
- John Radcliffe Hospital, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DS, UK
| | - Devika Agarwal
- Nuffield Department of Medicine Research Building, Alzheimer's Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK.,Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Adam E Handel
- John Radcliffe Hospital, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DS, UK
| | - Liting Wei
- James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - John Davis
- Nuffield Department of Medicine Research Building, Alzheimer's Research UK Oxford Drug Discovery Institute, University of Oxford, Oxford OX3 7FZ, UK
| | - Sally A Cowley
- Translational Molecular Neuroscience Group, New Biochemistry Building, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX1 3QU, UK
| | - M Zameel Cader
- John Radcliffe Hospital, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DS, UK.,James Martin Stem Cell Facility, Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK
| | - Caleb Webber
- UK Dementia Research Institute, Cardiff University, Cardiff CF24 4HQ, UK
| |
Collapse
|
6
|
Jones JC, Bodenstine TM. Connexins and Glucose Metabolism in Cancer. Int J Mol Sci 2022; 23:ijms231710172. [PMID: 36077565 PMCID: PMC9455984 DOI: 10.3390/ijms231710172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2022] [Revised: 08/26/2022] [Accepted: 08/30/2022] [Indexed: 11/16/2022] Open
Abstract
Connexins are a family of transmembrane proteins that regulate diverse cellular functions. Originally characterized for their ability to mediate direct intercellular communication through the formation of highly regulated membrane channels, their functions have been extended to the exchange of molecules with the extracellular environment, and the ability to modulate numerous channel-independent effects on processes such as motility and survival. Notably, connexins have been implicated in cancer biology for their context-dependent roles that can both promote or suppress cancer cell function. Moreover, connexins are able to mediate many aspects of cellular metabolism including the intercellular coupling of nutrients and signaling molecules. During cancer progression, changes to substrate utilization occur to support energy production and biomass accumulation. This results in metabolic plasticity that promotes cell survival and proliferation, and can impact therapeutic resistance. Significant progress has been made in our understanding of connexin and cancer biology, however, delineating the roles these multi-faceted proteins play in metabolic adaptation of cancer cells is just beginning. Glucose represents a major carbon substrate for energy production, nucleotide synthesis, carbohydrate modifications and generation of biosynthetic intermediates. While cancer cells often exhibit a dependence on glycolytic metabolism for survival, cellular reprogramming of metabolic pathways is common when blood perfusion is limited in growing tumors. These metabolic changes drive aggressive phenotypes through the acquisition of functional traits. Connections between glucose metabolism and connexin function in cancer cells and the surrounding stroma are now apparent, however much remains to be discovered regarding these relationships. This review discusses the existing evidence in this area and highlights directions for continued investigation.
Collapse
|
7
|
Abstract
Drug addiction remains a key biomedical challenge facing current neuroscience research. In addition to neural mechanisms, the focus of the vast majority of studies to date, astrocytes have been increasingly recognized as an "accomplice." According to the tripartite synapse model, astrocytes critically regulate nearby pre- and postsynaptic neuronal substrates to craft experience-dependent synaptic plasticity, including synapse formation and elimination. Astrocytes within brain regions that are implicated in drug addiction exhibit dynamic changes in activity upon exposure to cocaine and subsequently undergo adaptive changes themselves during chronic drug exposure. Recent results have identified several key astrocytic signaling pathways that are involved in cocaine-induced synaptic and circuit adaptations. In this review, we provide a brief overview of the role of astrocytes in regulating synaptic transmission and neuronal function, and discuss how cocaine influences these astrocyte-mediated mechanisms to induce persistent synaptic and circuit alterations that promote cocaine seeking and relapse. We also consider the therapeutic potential of targeting astrocytic substrates to ameliorate drug-induced neuroplasticity for behavioral benefits. While primarily focusing on cocaine-induced astrocytic responses, we also include brief discussion of other drugs of abuse where data are available.
Collapse
|
8
|
Gleizes M, Fonta C, Nowak LG. Inhibitors of ectonucleotidases have paradoxical effects on synaptic transmission in the mouse cortex. J Neurochem 2021; 160:305-324. [PMID: 34905223 DOI: 10.1111/jnc.15558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 12/08/2021] [Accepted: 12/09/2021] [Indexed: 11/30/2022]
Abstract
Extracellular adenosine plays prominent roles in the brain in both physiological and pathological conditions. Adenosine can be generated following the degradation of extracellular nucleotides by various types of ectonucleotidases. Several ectonucleotidases are present in the brain parenchyma: ecto-nucleotide triphosphate diphosphohydrolases 1 and 3 (NTPDase 1 and 3), ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP 1), ecto-5'-nucleotidase (eN), and tissue non-specific alkaline phosphatase (TNAP, whose function in the brain has received little attention). Here we examined, in a living brain preparation, the role of these ectonucleotidases in generating extracellular adenosine. We recorded local field potentials evoked by electrical stimulation of the lateral olfactory tract in the mouse piriform cortex in vitro. Variations in adenosine level were evaluated by measuring changes in presynaptic inhibition generated by adenosine A1 receptors (A1Rs) activation. A1R-mediated presynaptic inhibition was present endogenously and was enhanced by bath-applied AMP and ATP. We hypothesized that inhibiting ectonucleotidases would reduce extracellular adenosine concentration, which would result in a weakening of presynaptic inhibition. However, inhibiting TNAP had no effect in controlling endogenous adenosine action and no effect on presynaptic inhibition induced by bath-applied AMP. Furthermore, contrary to our expectation, inhibiting TNAP reinforced, rather than reduced, presynaptic inhibition induced by bath-applied ATP. Similarly, inhibition of NTPDase 1 and 3, NPP1 and eN induced stronger, rather than weaker, presynaptic inhibition, both in endogenous condition and with bath-applied ATP and AMP. Consequently, attempts to suppress the functions of extracellular adenosine by blocking its extracellular synthesis in living brain tissue could have functional impacts opposite to those anticipated.
Collapse
Affiliation(s)
- Marie Gleizes
- CerCo, Université Toulouse 3, CNRS, CHU Purpan, Pavillon Baudot, BP 25202, 31052, Toulouse Cedex
| | - Caroline Fonta
- CerCo, Université Toulouse 3, CNRS, CHU Purpan, Pavillon Baudot, BP 25202, 31052, Toulouse Cedex
| | - Lionel G Nowak
- CerCo, Université Toulouse 3, CNRS, CHU Purpan, Pavillon Baudot, BP 25202, 31052, Toulouse Cedex
| |
Collapse
|
9
|
Song B, Lee SJ, Kim CH. Roles of Cytokines in the Temporal Changes of Microglial Membrane Currents and Neuronal Excitability and Synaptic Efficacy in ATP-Induced Cortical Injury Model. Int J Mol Sci 2021; 22:ijms22136853. [PMID: 34202215 PMCID: PMC8268462 DOI: 10.3390/ijms22136853] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/18/2021] [Accepted: 06/23/2021] [Indexed: 12/20/2022] Open
Abstract
Cytokines are important neuroinflammatory modulators in neurodegenerative brain disorders including traumatic brain injury (TBI) and stroke. However, their temporal effects on the physiological properties of microglia and neurons during the recovery period have been unclear. Here, using an ATP-induced cortical injury model, we characterized selective effects of ATP injection compared to needle-control. In the damaged region, the fluorescent intensity of CX3CR1-GFP (+) cells, as well as the cell density, was increased and the maturation of newborn BrdU (+) cells continued until 28 day-post-injection (dpi) of ATP. The excitability and synaptic E/I balance of neurons and the inward and outward membrane currents of microglia were increased at 3 dpi, when expressions of tumor necrosis factor (TNF)-α/interleukin (IL)-1β and IL-10/IL-4 were also enhanced. These changes of both cells at 3 dpi were mostly decayed at 7 dpi and were suppressed by any of IL-10, IL-4, suramin (P2 receptor inhibitor) and 4-AP (K+ channel blocker). Acute ATP application alone induced only small effects from both naïve neurons and microglial cells in brain slice. However, TNF-α alone effectively increased the excitability of naïve neurons, which was blocked by suramin or 4-AP. TNF-α and IL-1β increased and decreased membrane currents of naïve microglia, respectively. Our results suggest that ATP and TNF-α dominantly induce the physiological activities of 3 dpi neurons and microglia, and IL-10 effectively suppresses such changes of both activated cells in K+ channel- and P2 receptor-dependent manner, while IL-4 suppresses neurons preferentially.
Collapse
Affiliation(s)
- Bokyung Song
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea;
- Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea
| | - Sung-Joong Lee
- Program in Neuroscience, Dental Research Institute, School of Dentistry, Seoul National University, Seoul 08826, Korea;
| | - Chong-Hyun Kim
- Center for Neuroscience, Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea;
- Neuroscience Program, Division of Bio-Medical Science and Technology, KIST School, Korea University of Science and Technology, Seoul 02792, Korea
- Correspondence:
| |
Collapse
|
10
|
P2X7 receptor in multifaceted cellular signalling and its relevance as a potential therapeutic target in different diseases. Eur J Pharmacol 2021; 906:174235. [PMID: 34097884 DOI: 10.1016/j.ejphar.2021.174235] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 02/07/2023]
Abstract
P2X7 receptor, a purinergic receptor family member, is abundantly expressed on many cells, including immune, muscle, bone, neuron, and glia. It acts as an ATP-activated cation channel that permits the influx of Ca2+, Na+ and efflux of K+ ions. The P2X7 receptor plays crucial roles in many physiological processes including cytokine and chemokine secretion, NLRP3 inflammasome activation, cellular growth and differentiation, locomotion, wound healing, transcription factors activation, cell death and T-lymphocyte survival. Past studies have demonstrated the up-regulation and direct association of this receptor in many pathophysiological conditions such as cancer, diabetics, arthritis, tuberculosis (TB) and inflammatory diseases. Hence, targeting this receptor is considered a worthwhile approach to lessen the afflictions associated with the disorders mentioned above by understanding the receptor architecture and downstream signalling processes. Here, in the present review, we have dissected the structural and functional aspects of the P2X7 receptor, emphasizing its role in various diseased conditions. This information will provide in-depth knowledge about the receptor and help to develop apt curative methodologies for the betterment of humanity in the coming years.
Collapse
|
11
|
Liu YD, Tang G, Qian F, Liu L, Huang JR, Tang FR. Astroglial Connexins in Neurological and Neuropsychological Disorders and Radiation Exposure. Curr Med Chem 2021; 28:1970-1986. [PMID: 32520676 DOI: 10.2174/0929867327666200610175037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 05/03/2020] [Accepted: 05/04/2020] [Indexed: 11/22/2022]
Abstract
Radiotherapy is a common treatment for brain and spinal cord tumors and also a risk factor for neuropathological changes in the brain leading to different neurological and neuropsychological disorders. Astroglial connexins are involved in brain inflammation, development of Alzheimer's Disease (AD), depressive, epilepsy, and amyotrophic lateral sclerosis, and are affected by radiation exposure. Therefore, it is speculated that radiation-induced changes of astroglial connexins may be related to the brain neuropathology and development of neurological and neuropsychological disorders. In this paper, we review the functional expression and regulation of astroglial connexins expressed between astrocytes and different types of brain cells (including oligodendrocytes, microglia, neurons and endothelial cells). The roles of these connexins in the development of AD, depressive, epilepsy, amyotrophic lateral sclerosis and brain inflammation have also been summarized. The radiation-induced astroglial connexins changes and development of different neurological and neuropsychological disorders are then discussed. Based on currently available data, we propose that radiation-induced astroglial connexins changes may be involved in the genesis of different neurological and neuropsychological disorders which depends on the age, brain regions, and radiation doses/dose rates. The abnormal astroglial connexins may be novel therapeutic targets for the prevention of radiation-induced cognitive impairment, neurological and neuropsychological disorders.
Collapse
Affiliation(s)
- Yuan Duo Liu
- Medical School of Yangtze University, Jingzhou 434000, China
| | - Ge Tang
- Woodlands Health Campus, National Healthcare Group Singapore, Singapore
| | - Feng Qian
- Medical School of Yangtze University, Jingzhou 434000, China
| | - Lian Liu
- Medical School of Yangtze University, Jingzhou 434000, China
| | | | - Feng Ru Tang
- Radiation Physiology Laboratory, Singapore Nuclear Research and Safety Initiative, National University of Singapore, Singapore
| |
Collapse
|
12
|
Choi JIV, Tchernookova BK, Kumar W, Kiedrowski L, Goeke C, Guizzetti M, Larson J, Kreitzer MA, Malchow RP. Extracellular ATP-Induced Alterations in Extracellular H + Fluxes From Cultured Cortical and Hippocampal Astrocytes. Front Cell Neurosci 2021; 15:640217. [PMID: 33994945 PMCID: PMC8120152 DOI: 10.3389/fncel.2021.640217] [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: 12/10/2020] [Accepted: 03/19/2021] [Indexed: 12/18/2022] Open
Abstract
Small alterations in the level of extracellular H+ can profoundly alter neuronal activity throughout the nervous system. In this study, self-referencing H+-selective microelectrodes were used to examine extracellular H+ fluxes from individual astrocytes. Activation of astrocytes cultured from mouse hippocampus and rat cortex with extracellular ATP produced a pronounced increase in extracellular H+ flux. The ATP-elicited increase in H+ flux appeared to be independent of bicarbonate transport, as ATP increased H+ flux regardless of whether the primary extracellular pH buffer was 26 mM bicarbonate or 1 mM HEPES, and persisted when atmospheric levels of CO2 were replaced by oxygen. Adenosine failed to elicit any change in extracellular H+ fluxes, and ATP-mediated increases in H+ flux were inhibited by the P2 inhibitors suramin and PPADS suggesting direct activation of ATP receptors. Extracellular ATP also induced an intracellular rise in calcium in cultured astrocytes, and ATP-induced rises in both calcium and H+ efflux were significantly attenuated when calcium re-loading into the endoplasmic reticulum was inhibited by thapsigargin. Replacement of extracellular sodium with choline did not significantly reduce the size of the ATP-induced increases in H+ flux, and the increases in H+ flux were not significantly affected by addition of EIPA, suggesting little involvement of Na+/H+ exchangers in ATP-elicited increases in H+ flux. Given the high sensitivity of voltage-sensitive calcium channels on neurons to small changes in levels of free H+, we hypothesize that the ATP-mediated extrusion of H+ from astrocytes may play a key role in regulating signaling at synapses within the nervous system.
Collapse
Affiliation(s)
- Ji-In Vivien Choi
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States.,Stritch School of Medicine, Loyola University, Maywood, IL, United States
| | - Boriana K Tchernookova
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Wasan Kumar
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States
| | - Lech Kiedrowski
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States.,Spot Cells LLC, Chicago, IL, United States
| | - Calla Goeke
- VA Portland Health Care System, Portland, OR, United States.,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, United States
| | - Marina Guizzetti
- VA Portland Health Care System, Portland, OR, United States.,Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, United States
| | - John Larson
- Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, United States
| | - Matthew A Kreitzer
- Department of Biology, Indiana Wesleyan University, Marion, IN, United States
| | - Robert Paul Malchow
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL, United States.,Department Ophthalmology and Visual Sciences, University of Illinois at Chicago, Chicago, IL, United States
| |
Collapse
|
13
|
Transmembrane Prolyl 4-Hydroxylase is a Novel Regulator of Calcium Signaling in Astrocytes. eNeuro 2021; 8:ENEURO.0253-20.2020. [PMID: 33298456 PMCID: PMC7814479 DOI: 10.1523/eneuro.0253-20.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Revised: 11/09/2020] [Accepted: 11/27/2020] [Indexed: 12/11/2022] Open
Abstract
Prolyl 4-hydroxylases (P4Hs) have vital roles in regulating collagen synthesis and hypoxia response. A transmembrane P4H (P4H-TM) is a recently identified member of the family. Biallelic loss of function P4H-TM mutations cause a severe autosomal recessive intellectual disability syndrome in humans, but functions of P4H-TM are essentially unknown at cellular level. Our microarray data on P4h-tm -/- mouse cortexes where P4H-TM is abundantly expressed indicated expression changes in genes involved in calcium signaling and expression of several calcium sequestering ATPases was upregulated in P4h-tm -/- primary mouse astrocytes. Cytosolic and intraorganellar calcium imaging of P4h-tm -/- cells revealed that receptor-operated calcium entry (ROCE) and store-operated calcium entry (SOCE) and calcium re-uptake by mitochondria were compromised. HIF1, but not HIF2, was found to be a key mediator of the P4H-TM effect on calcium signaling. Furthermore, total internal reflection fluorescence (TIRF) imaging showed that calcium agonist-induced gliotransmission was attenuated in P4h-tm -/- astrocytes. This phenotype was accompanied by redistribution of mitochondria from distal processes to central parts of the cell body and decreased intracellular ATP content. Our data show that P4H-TM is a novel regulator of calcium dynamics and gliotransmission.
Collapse
|
14
|
Onodera J, Nagata H, Nakashima A, Ikegaya Y, Koyama R. Neuronal brain-derived neurotrophic factor manipulates microglial dynamics. Glia 2020; 69:890-904. [PMID: 33119934 DOI: 10.1002/glia.23934] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Revised: 10/22/2020] [Accepted: 10/22/2020] [Indexed: 12/19/2022]
Abstract
Brain-derived neurotrophic factor (BDNF), a main member of the neurotrophin family that is active in the brain, supports neuronal survival and growth. Microglial BDNF affects both the structural and functional properties of neurons. In contrast, whether and how neuronal BDNF affects microglial dynamics remain largely undetermined. Here, we examined the effects of BDNF on the properties of microglia in the CA3 region of the hippocampus. We chose this site because the axonal boutons of hippocampal mossy fibers, which are mostly formed in the CA3 region, contain the highest levels of BDNF in the rodent brain. We transfected mouse dentate granule cells with an adeno-associated virus that encodes both a BDNF short hairpin RNA (shRNA) and red fluorescent protein to examine the effects of mossy fiber-derived BDNF on microglia. Based on immunohistochemistry, BDNF knockdown with an shRNA resulted in an increase in microglial density in the mossy fiber pathway and increased engulfment of mossy fiber axons by microglia. In addition, we performed time-lapse imaging of microglial processes in hippocampal slice cultures to examine the effects of BDNF on microglial motility. Time-lapse imaging revealed increases in the motility of microglial processes and the engulfment of mossy fiber synapses by microglia when BDNF signaling was pharmacologically blocked. Thus, neuronal BDNF prevents microglia from engulfing mossy fiber synapses in the hippocampus.
Collapse
Affiliation(s)
- Junya Onodera
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Hidetaka Nagata
- Platform Technology Research Unit, Sumitomo Dainippon Pharma Co., Ltd., Osaka, Japan
| | - Ai Nakashima
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Yuji Ikegaya
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| | - Ryuta Koyama
- Laboratory of Chemical Pharmacology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan
| |
Collapse
|
15
|
Pizzoni A, Bazzi Z, Di Giusto G, Alvarez CL, Rivarola V, Capurro C, Schwarzbaum PJ, Ford P. Release of ATP by TRPV4 activation is dependent upon the expression of AQP2 in renal cells. J Cell Physiol 2020; 236:2559-2571. [PMID: 33094506 DOI: 10.1002/jcp.30013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 07/18/2020] [Accepted: 08/04/2020] [Indexed: 12/18/2022]
Abstract
Increasing evidence indicates that aquaporins (AQPs) exert an influence in cell signaling by the interplay with the transient receptor potential vanilloid 4 (TRPV4) channel. We previously found that TRPV4 physically and functionally interacts with AQP2 in cortical collecting ducts (CCD) cells, favoring cell volume regulation and cell migration. Because TRPV4 was implicated in ATP release in several tissues, we investigated the possibility that TRPV4/AQP2 interaction influences ATP release in CCD cells. Using two CCD cell lines expressing or not AQP2, we measured extracellular ATP (ATPe) under TRPV4 activation and intracellular Ca2+ under ATP addition. We found that AQP2 is critical for the release of ATP induced by TRPV4 activation. This ATP release occurs by an exocytic and a conductive route. ATPe, in turn, stimulates purinergic receptors leading to ATPe-induced ATP release by a Ca2+ -dependent mechanism. We propose that AQP2 by modulating Ca2+ and ATP differently could explain AQP2-increased cell migration.
Collapse
Affiliation(s)
- Alejandro Pizzoni
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Zaher Bazzi
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini," Consejo Nacional de Investigaciones Científicas y Técnicas, Cátedra de Química Biológica Superior, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Gisela Di Giusto
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Cora L Alvarez
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini," Consejo Nacional de Investigaciones Científicas y Técnicas, Cátedra de Química Biológica Superior, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Valeria Rivarola
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Claudia Capurro
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Pablo J Schwarzbaum
- Departamento de Química Biológica, Facultad de Farmacia y Bioquímica, Instituto de Química y Fisico-Química Biológicas (IQUIFIB) "Prof. Alejandro C. Paladini," Consejo Nacional de Investigaciones Científicas y Técnicas, Cátedra de Química Biológica Superior, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Paula Ford
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| |
Collapse
|
16
|
Hsu SS, Liang WZ. Ca 2+ signaling as a mechanism of haloperidol-induced cytotoxicity in human astrocytes and assessing the protective role of a Ca 2+ chelator. Naunyn Schmiedebergs Arch Pharmacol 2020; 393:2117-2127. [PMID: 32594194 DOI: 10.1007/s00210-020-01929-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/18/2020] [Indexed: 11/28/2022]
Abstract
Haloperidol, a typical antipsychotic medication, has been shown to possess various biological effects in different brain models. However, the impact of haloperidol on Ca2+ signaling in astrocytes is elusive. This study explored the effect of haloperidol on cytosolic free Ca2+ levels ([Ca2+]i) and viability, and established these two connections in Gibco® Human Astrocytes (GHAs) and DI TNC1 rat astrocytes. Haloperidol (5-20 μM) caused [Ca2+]i rises in a concentration-dependent manner in GHAs but not in DI TNC1 cells. Furthermore, removal of extracellular Ca2+ reduced haloperidol's effect by approximately 30% in GHAs. Haloperidol (20-40 μM) evoked concentration-dependent cytotoxicity in GHAs and DI TNC1 cells. However, chelating cytosolic Ca2+ with the Ca2+ chelator BAPTA/AM significantly reversed haloperidol's cytotoxicity only in GHAs. In GHAs, haloperidol-induced Ca2+ entry was inhibited by store-operated Ca2+ modulators (2-APB and SKF96365) and the protein kinase C (PKC) inhibitor GF109203X. This Ca2+ entry induced by haloperidol was confirmed by Mn2+ entry-induced quench of fura-2 fluorescence. In Ca2+-free medium, treatment with the endoplasmic reticulum Ca2+ pump inhibitor 2,5-di-tert-butylhydroquinone (BHQ) abolished haloperidol-induced [Ca2+]i rises. Conversely, treatment with haloperidol inhibited 45% of BHQ-evoked [Ca2+]i rises. Moreover, haloperidol-induced Ca2+ release from the endoplasmic reticulum was abolished by inhibition of phospholipase C (PLC) by U73122. Together, in GHAs but not in DI TNC1 cells, haloperidol caused Ca2+-associated cell death, induced Ca2+ entry via PKC-sensitive store-operated Ca2+ channels, and evoked PLC-dependent Ca2+ release from the endoplasmic reticulum. The protective effect of Ca2+ chelating on haloperidol-induced cytotoxicity in human astrocytes was also demonstrated.
Collapse
Affiliation(s)
- Shu-Shong Hsu
- Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung, 81362, Taiwan.,Department of Surgery, National Defense Medical Center, Taipei, 11490, Taiwan.,College of Health and Nursing, Meiho University, Pingtung, 91202, Taiwan
| | - Wei-Zhe Liang
- Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung, 81362, Taiwan. .,Department of Pharmacy and Master Program, College of Pharmacy and Health Care, Tajen University, Pingtung County, 90741, Taiwan.
| |
Collapse
|
17
|
Shen D, Shen X, Schwarz W, Grygorczyk R, Wang L. P2Y 13 and P2X 7 receptors modulate mechanically induced adenosine triphosphate release from mast cells. Exp Dermatol 2020; 29:499-508. [PMID: 32155290 DOI: 10.1111/exd.14093] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/25/2020] [Accepted: 03/03/2020] [Indexed: 12/15/2022]
Abstract
Subcutaneous mast cells (MCs) are vulnerable to mechanical stimulation from external environment. Thus, MCs immune function could be modulated by their mechanosensitivity. This property has been identified as the trigger mechanism of needling acupuncture, a traditional oriental therapy. Previously we have demonstrated the release of adenosine triphosphate (ATP), a stress-responsive signalling molecule, from mechanical-perturbed MCs. The current work explores its underlying mechanisms. We noticed that propagation of intracellular free Ca2+ occurred among HMC-1 cells in response to 50% hypotonic shock. Additionally, amplifying cascade of ATP-induced ATP release was observed in RBL-2H3 cells stimulated by medium displacement, which could be mimicked by exogenous ATP (exoATP). Secondary ATP liberation induced by low level (50 nmol/L) of exoATP was reduced by inhibiting ecto-ATPase-dependent ADP production with ARL67156, or blocking P2 receptors with suramin or PPADS, or with specific P2Y13 receptor antagonist MRS2211, or siRNA. Secondary ATP release induced by higher dose (200 μmol/L) of exoATP, sufficient to stimulate P2X7 receptor, was attenuated by suramin, PPADS or specific P2X7 receptor antagonist BBG, or siRNA. Finally, RT-PCR confirmed mRNA expression of P2Y13 and P2X7 in RBL-2H3 cells. Additionally, such secondary ATP release was attenuated by DPCPX, specific antagonist of adenosine A1 receptor, but not by MRS2179, specific inhibitor of P2Y1 receptor. In summary, mechanosensitive ATP release from MCs is facilitated by paracrine/autocrine stimulation of P2Y13 and P2X7 receptors. This multi-receptor combination could mediate transmission of information from a local site to distal areas, enabling communication with multiple surrounding cells to coordinate and synchronize their function.
Collapse
Affiliation(s)
- Dan Shen
- Acupuncture and Moxibustion College, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xueyong Shen
- Acupuncture and Moxibustion College, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,Shanghai Research Center for Acupuncture and Meridians, Shanghai, China
| | - Wolfgang Schwarz
- Institute for Biophysics, Goethe-University Frankfurt, Frankfurt a.M., Germany
| | - Ryszard Grygorczyk
- Centre de Recherche, Centre Hospitalier de I'Université de Montréal (CRCHUM), Montréal, QC, Canada.,Department of Medicine, Université de Montréal, Montréal, QC, Canada
| | - Lina Wang
- Acupuncture and Moxibustion College, Shanghai University of Traditional Chinese Medicine, Shanghai, China.,Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function (14DZ2260500), Fudan University, Shanghai, China
| |
Collapse
|
18
|
Hoorelbeke D, Decrock E, De Smet M, De Bock M, Descamps B, Van Haver V, Delvaeye T, Krysko DV, Vanhove C, Bultynck G, Leybaert L. Cx43 channels and signaling via IP 3/Ca 2+, ATP, and ROS/NO propagate radiation-induced DNA damage to non-irradiated brain microvascular endothelial cells. Cell Death Dis 2020; 11:194. [PMID: 32188841 PMCID: PMC7080808 DOI: 10.1038/s41419-020-2392-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Revised: 02/17/2020] [Accepted: 02/18/2020] [Indexed: 02/06/2023]
Abstract
Radiotherapeutic treatment consists of targeted application of radiation beams to a tumor but exposure of surrounding healthy tissue is inevitable. In the brain, ionizing radiation induces breakdown of the blood-brain barrier by effects on brain microvascular endothelial cells. Damage from directly irradiated cells can be transferred to surrounding non-exposed bystander cells, known as the radiation-induced bystander effect. We investigated involvement of connexin channels and paracrine signaling in radiation-induced bystander DNA damage in brain microvascular endothelial cells exposed to focused X-rays. Irradiation caused DNA damage in the directly exposed area, which propagated over several millimeters in the bystander area. DNA damage was significantly reduced by the connexin channel-targeting peptide Gap26 and the Cx43 hemichannel blocker TAT-Gap19. ATP release, dye uptake, and patch clamp experiments showed that hemichannels opened within 5 min post irradiation in both irradiated and bystander areas. Bystander signaling involved cellular Ca2+ dynamics and IP3, ATP, ROS, and NO signaling, with Ca2+, IP3, and ROS as crucial propagators of DNA damage. We conclude that bystander effects are communicated by a concerted cascade involving connexin channels, and IP3/Ca2+, ATP, ROS, and NO as major contributors of regenerative signal expansion.
Collapse
Affiliation(s)
- Delphine Hoorelbeke
- Physiology group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Elke Decrock
- Physiology group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Maarten De Smet
- Physiology group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Marijke De Bock
- Physiology group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Benedicte Descamps
- Infinity Lab, IBiTech-MEDISIP, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Valérie Van Haver
- Physiology group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Tinneke Delvaeye
- Physiology group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium
| | - Dmitri V Krysko
- Cell Death Investigation and Therapy Laboratory, Department of Human Structure and Repair, Ghent University, Ghent, Belgium.,Department of Physiology, Sechenov First Moscow State Medical University, Moskow, Russia
| | - Christian Vanhove
- Infinity Lab, IBiTech-MEDISIP, Department of Electronics and Information Systems, Ghent University, Ghent, Belgium
| | - Geert Bultynck
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Luc Leybaert
- Physiology group, Department of Basic and Applied Medical Sciences, Ghent University, Ghent, Belgium.
| |
Collapse
|
19
|
Rawlinson C, Jenkins S, Thei L, Dallas ML, Chen R. Post-Ischaemic Immunological Response in the Brain: Targeting Microglia in Ischaemic Stroke Therapy. Brain Sci 2020; 10:brainsci10030159. [PMID: 32168831 PMCID: PMC7139954 DOI: 10.3390/brainsci10030159] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 02/27/2020] [Accepted: 03/07/2020] [Indexed: 12/21/2022] Open
Abstract
Microglia, the major endogenous immune cells of the central nervous system, mediate critical degenerative and regenerative responses in ischaemic stroke. Microglia become "activated", proliferating, and undergoing changes in morphology, gene and protein expression over days and weeks post-ischaemia, with deleterious and beneficial effects. Pro-inflammatory microglia (commonly referred to as M1) exacerbate secondary neuronal injury through the release of reactive oxygen species, cytokines and proteases. In contrast, microglia may facilitate neuronal recovery via tissue and vascular remodelling, through the secretion of anti-inflammatory cytokines and growth factors (a profile often termed M2). This M1/M2 nomenclature does not fully account for the microglial heterogeneity in the ischaemic brain, with some simultaneous expression of both M1 and M2 markers at the single-cell level. Understanding and regulating microglial activation status, reducing detrimental and promoting repair behaviours, present the potential for therapeutic intervention, and open a longer window of opportunity than offered by acute neuroprotective strategies. Pharmacological modulation of microglial activation status to promote anti-inflammatory gene expression can increase neurogenesis and improve functional recovery post-stroke, based on promising preclinical data. Cell-based therapies, using preconditioned microglia, are of interest as a method of therapeutic modulation of the post-ischaemic inflammatory response. Currently, there are no clinically-approved pharmacological options targeting post-ischaemic inflammation. A major developmental challenge for clinical translation will be the selective suppression of the deleterious effects of microglial activity after stroke whilst retaining (or enhancing) the neurovascular repair and remodelling responses of microglia.
Collapse
Affiliation(s)
- Charlotte Rawlinson
- School of Pharmacy and Bioengineering, Keele University, Staffordshire ST5 5BG, UK;
| | - Stuart Jenkins
- School of Medicine, Keele University, Staffordshire ST5 5BG, UK;
| | - Laura Thei
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (L.T.); (M.L.D.)
| | - Mark L. Dallas
- School of Pharmacy, University of Reading, Reading RG6 6UB, UK; (L.T.); (M.L.D.)
| | - Ruoli Chen
- School of Pharmacy and Bioengineering, Keele University, Staffordshire ST5 5BG, UK;
- Correspondence: ; Tel.: +44-1782-733849; Fax: 44-1782-733326
| |
Collapse
|
20
|
Jones JR, Kong L, Hanna MG, Hoffman B, Krencik R, Bradley R, Hagemann T, Choi J, Doers M, Dubovis M, Sherafat MA, Bhattacharyya A, Kendziorski C, Audhya A, Messing A, Zhang SC. Mutations in GFAP Disrupt the Distribution and Function of Organelles in Human Astrocytes. Cell Rep 2019; 25:947-958.e4. [PMID: 30355500 PMCID: PMC6275075 DOI: 10.1016/j.celrep.2018.09.083] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 09/05/2018] [Accepted: 09/25/2018] [Indexed: 01/15/2023] Open
Abstract
How mutations in glial fibrillary acidic protein (GFAP) cause Alexander disease (AxD) remains elusive. We generated iPSCs from two AxD patients and corrected the GFAP mutations to examine the effects of mutant GFAP on human astrocytes. AxD astrocytes displayed GFAP aggregates, recapitulating the pathological hallmark of AxD. RNA sequencing implicated the endoplasmic reticulum, vesicle regulation, and cellular metabolism. Corroborating this analysis, we observed enlarged and heterogeneous morphology coupled with perinuclear localization of endoplasmic reticulum and lysosomes in AxD astrocytes. Functionally, AxD astrocytes showed impaired extracellular ATP release, which is responsible for attenuated calcium wave propagation. These results reveal that AxD-causing mutations in GFAP disrupt intracellular vesicle regulation and impair astrocyte secretion, resulting in astrocyte dysfunction and AxD pathogenesis.
Collapse
Affiliation(s)
- Jeffrey R Jones
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Linghai Kong
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Michael G Hanna
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Brianna Hoffman
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Robert Krencik
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Robert Bradley
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Tracy Hagemann
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Jeea Choi
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Matthew Doers
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Marina Dubovis
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | | | | | - Christina Kendziorski
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Anjon Audhya
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Albee Messing
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Su-Chun Zhang
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Neuroscience, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Neurology, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53705, USA; Program in Neuroscience & Behavioral Disorders, Duke-NUS Medical School, Singapore, Singapore.
| |
Collapse
|
21
|
Verkhratsky A, Parpura V, Vardjan N, Zorec R. Physiology of Astroglia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1175:45-91. [PMID: 31583584 DOI: 10.1007/978-981-13-9913-8_3] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Astrocytes are principal cells responsible for maintaining the brain homeostasis. Additionally, these glial cells are also involved in homocellular (astrocyte-astrocyte) and heterocellular (astrocyte-other cell types) signalling and metabolism. These astroglial functions require an expression of the assortment of molecules, be that transporters or pumps, to maintain ion concentration gradients across the plasmalemma and the membrane of the endoplasmic reticulum. Astrocytes sense and balance their neurochemical environment via variety of transmitter receptors and transporters. As they are electrically non-excitable, astrocytes display intracellular calcium and sodium fluctuations, which are not only used for operative signalling but can also affect metabolism. In this chapter we discuss the molecules that achieve ionic gradients and underlie astrocyte signalling.
Collapse
Affiliation(s)
- Alexei Verkhratsky
- Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, M13 9PT, UK. .,Faculty of Health and Medical Sciences, Center for Basic and Translational Neuroscience, University of Copenhagen, 2200, Copenhagen, Denmark. .,Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011, Bilbao, Spain.
| | - Vladimir Parpura
- Department of Neurobiology, The University of Alabama at Birmingham, Birmingham, AL, USA
| | - Nina Vardjan
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| | - Robert Zorec
- Laboratory of Neuroendocrinology-Molecular Cell Physiology, Faculty of Medicine, Institute of Pathophysiology, University of Ljubljana, Ljubljana, Slovenia.,Celica Biomedical, Ljubljana, Slovenia
| |
Collapse
|
22
|
Grygorczyk R, Boudreault F, Tan JJ, Ponomarchuk O, Sokabe M, Furuya K. Mechanosensitive ATP release in the lungs: New insights from real-time luminescence imaging studies. CURRENT TOPICS IN MEMBRANES 2019; 83:45-76. [PMID: 31196610 DOI: 10.1016/bs.ctm.2019.02.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Extracellular ATP and other nucleotides are important autocrine/paracrine mediators that stimulate purinergic receptors and regulate diverse processes in the normal lungs. They are also associated with pathogenesis of a number of respiratory diseases and clinical complications including acute respiratory distress syndrome and ventilator induced lung injury. Mechanical forces are major stimuli for cellular ATP release but precise mechanisms responsible for this release are still debated. The present review intends to provide the current state of knowledge of the mechanisms of ATP release in the lung. Putative pathways of the release, including the contribution of cell membrane injury and cell lysis are discussed addressing their strength, weaknesses and missing evidence that requires future study. We also provide an overview of the recent technical advances in studying cellular ATP release in vitro and ex vivo. Special attention is given to new insights into lung ATP release obtained with the real-time luminescence ATP imaging. This includes recent data on stretch-induced mechanosensitive ATP release in a model and primary cells of lung alveoli in vitro as well as inflation-induced ATP release in airspaces and pulmonary blood vessels of lungs, ex vivo.
Collapse
Affiliation(s)
- Ryszard Grygorczyk
- Department of Medicine, Université de Montréal, Montréal, QC, Canada; Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada.
| | - Francis Boudreault
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Ju Jing Tan
- Department of Medicine, Université de Montréal, Montréal, QC, Canada; Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada
| | - Olga Ponomarchuk
- Centre de recherche, Centre hospitalier de l'Université de Montréal (CRCHUM), Montréal, QC, Canada; Faculty of Biology, M.V. Lomonosov Moscow State University, Moscow, Russia
| | - Masahiro Sokabe
- Mechanobiology Laboratory, Nagoya University, Graduate School of Medicine, Nagoya, Japan
| | - Kishio Furuya
- Mechanobiology Laboratory, Nagoya University, Graduate School of Medicine, Nagoya, Japan
| |
Collapse
|
23
|
Wellmann M, Álvarez-Ferradas C, Maturana CJ, Sáez JC, Bonansco C. Astroglial Ca 2+-Dependent Hyperexcitability Requires P2Y 1 Purinergic Receptors and Pannexin-1 Channel Activation in a Chronic Model of Epilepsy. Front Cell Neurosci 2018; 12:446. [PMID: 30542266 PMCID: PMC6277884 DOI: 10.3389/fncel.2018.00446] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 11/06/2018] [Indexed: 12/31/2022] Open
Abstract
Astrocytes from the hippocampus of chronic epileptic rats exhibit an abnormal pattern of intracellular calcium oscillations, characterized by an augmented frequency of long lasting spontaneous Ca2+ transients, which are sensitive to purinergic receptor antagonists but resistant to tetrodotoxin. The above suggests that alterations in astroglial Ca2+-dependent excitability observed in the epileptic tissue could arise from changes in astrocyte-to-astrocyte signaling, which is mainly mediated by purines in physiological and pathological conditions. In spite of that, how purinergic signaling contributes to astrocyte dysfunction in epilepsy remains unclear. Here, we assessed the possible contribution of P2Y1R as well as pannexin1 and connexin43 hemichannels—both candidates for non-vesicular ATP-release—by performing astroglial Ca2+ imaging and dye uptake experiments in hippocampal slices from control and fully kindled rats. P2Y1R blockade with MRS2179 decreased the mean duration of astroglial Ca2+ oscillations by reducing the frequency of slow Ca2+ transients, and thereby restoring the balance between slow (ST) and fast transients (FT) in the kindled group. The potential contribution of astroglial pannexin1 and connexin43 hemichannels as pathways for purine release (e.g., ATP) was assessed through dye uptake experiments. Astrocytes from kindled hippocampi exhibit three-fold more EtBr uptake than controls, whereby pannexin1 hemichannels (Panx1 HCs) accounts for almost all dye uptake with only a slight contribution from connexin43 hemichannels (Cx43 HCs). Confirming its functional involvement, Panx1 HCs inhibition decreased the mean duration of astroglial Ca2+ transients and the frequency of slow oscillations in kindled slices, but had no noticeable effects on the control group. As expected, Cx43 HCs blockade did not have any effects over the mean duration of astroglial Ca2+ oscillations. These findings suggest that P2Y1R and Panx1 HCs play a pivotal role in astroglial pathophysiology, which would explain the upregulation of glutamatergic neurotransmission in the epileptic brain and thus represents a new potential pharmacological target for the treatment of drug-refractory epilepsy.
Collapse
Affiliation(s)
- Mario Wellmann
- Centro de Neurobiología y Plasticidad Cerebral CNPC, Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Escuela de Fonoaudiología, Facultad de Medicina, Universidad de Valparaíso, Valparaíso, Chile
| | - Carla Álvarez-Ferradas
- Centro de Neurobiología y Plasticidad Cerebral CNPC, Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.,Escuela de Ciencias de la Salud, Universidad Viña del Mar, Valparaíso, Chile
| | - Carola J Maturana
- Departamento de Ciencias Fisiológicas, Facultad Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Juan C Sáez
- Departamento de Ciencias Fisiológicas, Facultad Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile.,Instituto de Neurociencias, Centro Interdisciplinario de Neurociencias de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Christian Bonansco
- Centro de Neurobiología y Plasticidad Cerebral CNPC, Instituto de Fisiología, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| |
Collapse
|
24
|
Mayhew J, Graham BA, Biber K, Nilsson M, Walker FR. Purinergic modulation of glutamate transmission: An expanding role in stress-linked neuropathology. Neurosci Biobehav Rev 2018; 93:26-37. [PMID: 29959963 DOI: 10.1016/j.neubiorev.2018.06.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 06/18/2018] [Accepted: 06/24/2018] [Indexed: 02/04/2023]
Abstract
Chronic stress has been extensively linked to disturbances in glutamatergic signalling. Emerging from this field of research is a considerable number of studies identifying the ability of purines at the pre-, post-, and peri-synaptic levels to tune glutamatergic neurotransmission. While the evidence describing purinergic control of glutamate has continued to grow, there has been relatively little attention given to how chronic stress modulates purinergic functions. The available research on this topic has demonstrated that chronic stress can not only disturb purinergic receptors involved in the regulation of glutamate neurotransmission, but also perturb glial-dependent purinergic signalling. This review will provide a detailed examining of the complex literature relating to glutamatergic-purinergic interactions with a focus on both neuronal and glial contributions. Once these detailed interactions have been described and contextualised, we will integrate recent findings from the field of stress research.
Collapse
Affiliation(s)
- J Mayhew
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia; Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW, Australia; Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.
| | - B A Graham
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia; Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW, Australia; Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| | - K Biber
- Department of Psychiatry and Psychotherapy, University Hospital Freiburg, 79104 Freiburg, Germany; Department of Neuroscience, University Medical Center Groningen, University of Groningen, 9713 AV Groningen, The Netherlands
| | - M Nilsson
- Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW, Australia; Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| | - F R Walker
- School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia; Centre for Translational Neuroscience and Mental Health Research, University of Newcastle, Callaghan, NSW, Australia; Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
| |
Collapse
|
25
|
Wang J, Jackson DG, Dahl G. Cationic control of Panx1 channel function. Am J Physiol Cell Physiol 2018; 315:C279-C289. [PMID: 29719168 DOI: 10.1152/ajpcell.00303.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The sequence and predicted membrane topology of pannexin1 (Panx1) places it in the family of gap junction proteins. However, rather than forming gap junction channels, Panx1 forms channels in the nonjunctional membrane. Panx1 operates in two distinct open states, depending on the mode of stimulation. The exclusively voltage-gated channel has a small conductance (<100 pS) and is highly selective for the flux of chloride ions. The Panx1 channel activated by various physiological stimuli or by increased concentrations of extracellular potassium ions has a large conductance (~500 pS, however, with multiple, long-lasting subconductance states) and is nonselectively permeable to small molecules, including ATP. To test whether the two open conformations also differ pharmacologically, the effects of di-and trivalent cations on the two Panx1 channel conformations were investigated. The rationale for this venture was that, under certain experimental conditions, ATP release from cells can be inhibited by multivalent cations, yet the literature indicates that the ATP release channel Panx1 is not affected by these ions. Consistent with previous reports, the Panx1 channel was not activated by removal of extracellular Ca2+ and the currents through the voltage-activated channel were not altered by Ca2+, Zn2+, Ba2+, or Gd3+. In contrast, the Panx1 channel activated to the large channel conformation by extracellular K+, osmotic stress, or low oxygen was inhibited by the multivalent cations in a dose-dependent way. Thus, monovalent cations activated the Panx1 channel from the closed state to the "large" conformation, while di- and trivalent cations exclusively inhibited this large channel conformation.
Collapse
Affiliation(s)
- Junjie Wang
- Department of Physiology and Biophysics, University of Miami School of Medicine , Miami, Florida
| | - David George Jackson
- Department of Physiology and Biophysics, University of Miami School of Medicine , Miami, Florida
| | - Gerhard Dahl
- Department of Physiology and Biophysics, University of Miami School of Medicine , Miami, Florida
| |
Collapse
|
26
|
Xiong Y, Teng S, Zheng L, Sun S, Li J, Guo N, Li M, Wang L, Zhu F, Wang C, Rao Z, Zhou Z. Stretch-induced Ca 2+ independent ATP release in hippocampal astrocytes. J Physiol 2018; 596:1931-1947. [PMID: 29488635 DOI: 10.1113/jp275805] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 02/21/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Similar to neurons, astrocytes actively participate in synaptic transmission via releasing gliotransmitters. The Ca2+ -dependent release of gliotransmitters includes glutamate and ATP. Following an 'on-cell-like' mechanical stimulus to a single astrocyte, Ca2+ independent single, large, non-quantal, ATP release occurs. Astrocytic ATP release is inhibited by either selective antagonist treatment or genetic knockdown of P2X7 receptor channels. Our work suggests that ATP can be released from astrocytes via two independent pathways in hippocampal astrocytes; in addition to the known Ca2+ -dependent vesicular release, larger non-quantal ATP release depends on P2X7 channels following mechanical stretch. ABSTRACT Astrocytic ATP release is essential for brain functions such as synaptic long-term potentiation for learning and memory. However, whether and how ATP is released via exocytosis remains hotly debated. All previous studies of non-vesicular ATP release have used indirect assays. By contrast, two recent studies report vesicular ATP release using more direct assays. In the present study, using patch clamped 'ATP-sniffer cells', we re-investigated astrocytic ATP release at single-vesicle resolution in hippocampal astrocytes. Following an 'on-cell-like' mechanical stimulus of a single astrocyte, a Ca2+ independent single large non-quantal ATP release occurred, in contrast to the Ca2+ -dependent multiple small quantal ATP release in a chromaffin cell. The mechanical stimulation-induced ATP release from an astrocyte was inhibited by either exposure to a selective antagonist or genetic knockdown of P2X7 receptor channels. Functional P2X7 channels were expressed in astrocytes in hippocampal brain slices. Thus, in addition to small quantal ATP release, larger non-quantal ATP release depends on P2X7 channels in astrocytes.
Collapse
Affiliation(s)
- Yingfei Xiong
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China.,Institute of Neurosciences, Fourth Military Medical University, Xi'an, China.,Department of Neurosurgery, Affiliated Hospital of Air Force Institute of Aeromedicine, Beijing, China
| | - Sasa Teng
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Lianghong Zheng
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Suhua Sun
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Jie Li
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Ning Guo
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Mingli Li
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Li Wang
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Feipeng Zhu
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Changhe Wang
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| | - Zhiren Rao
- Institute of Neurosciences, Fourth Military Medical University, Xi'an, China
| | - Zhuan Zhou
- State Key Laboratory of Biomembrane and Membrane Biotechnology and Peking-Tsinghua Center for Life Sciences and PKU-IDG/McGovern Institute for Brain Research, Institute of Molecular Medicine, Peking University, Beijing, China
| |
Collapse
|
27
|
Wotton CA, Quon EF, Palmer AC, Bekar LK. Corticosterone and serotonin similarly influence GABAergic and purinergic pathways to affect cortical inhibitory networks. J Neuroendocrinol 2018. [PMID: 29543349 DOI: 10.1111/jne.12592] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Both serotonin (5-HT) and stress exert changes in cortical inhibitory tone to shape the activity of cortical networks. Because astrocytes are also known to affect inhibition through established purinergic pathways, we assessed the role of GABA and purinergic pathways with respect to the effects of rapid corticosterone (CORT) and 5-HT on cortical inhibition. We used a paired-pulse paradigm (P1 and P2) in acutely isolated mouse brain slices to evaluate changes in cortical evoked inhibition. Normally, 5-HT decreases the amplitude of the first pulse P1, whereas it increases the amplitude of P2 (increasing frequency transmission). Interestingly, it was observed that CORT application decreased P1 and increased P2 similar to that of 5-HT application. Given that CORT and 5-HT are known to modulate inhibition, we applied the GABAA antagonist bicuculline in the presence of both and found that the increase in P2 and the P2/P1 was lost, providing evidence for a common mechanism involving GABAA receptor signalling. Additional occlusion experiments (ie, 5-HT in presence of CORT and CORT in presence of 5-HT) provide further support for a common mechanism. Because both 5-HT and CORT blocked the increase in P2 and P2/P1 with respect to the other, we suggest 5-HT/CORT already utilise the shared mechanism to affect cortical inhibition. Using low concentrations of the GAPDH inhibitor iodoacetate, as commonly used to selectively disrupt astrocyte metabolism, we found that the increase in P2 and P2/P1 was similarly blocked in response to both CORT and 5-HT. Because astrocyte signalling depends in large part on purinergic pathways, the purinergic contribution was assessed using Ab129 (P2Y antagonist) and SCH 58261 (A2A antagonist). Once again, P2Y and A2A receptor blockade similarly disrupted 5-HT- or CORT-mediated increases in P2 and P2/P1. Taken together, these results support the common involvement of GABAergic and purinergic pathways in the effects of CORT and 5-HT that may also involve astrocytes.
Collapse
Affiliation(s)
- C A Wotton
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - E F Quon
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - A C Palmer
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| | - L K Bekar
- Department of Pharmacology, College of Medicine, University of Saskatchewan, Saskatoon, SK, Canada
| |
Collapse
|
28
|
Labra VC, Santibáñez CA, Gajardo-Gómez R, Díaz EF, Gómez GI, Orellana JA. The Neuroglial Dialog Between Cannabinoids and Hemichannels. Front Mol Neurosci 2018; 11:79. [PMID: 29662436 PMCID: PMC5890195 DOI: 10.3389/fnmol.2018.00079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 02/28/2018] [Indexed: 12/11/2022] Open
Abstract
The formation of gap junctions was initially thought to be the central role of connexins, however, recent evidence had brought to light the high relevance of unopposed hemichannels as an independent mechanism for the selective release of biomolecules during physiological and pathological conditions. In the healthy brain, the physiological opening of astrocyte hemichannels modulates basal excitatory synaptic transmission. At the other end, the release of potentially neurotoxic compounds through astroglial hemichannels and pannexons has been insinuated as one of the functional alterations that negatively affect the progression of multiple brain diseases. Recent insights in this matter have suggested encannabinoids (eCBs) as molecules that could regulate the opening of these channels during diverse conditions. In this review, we discuss and hypothesize the possible interplay between the eCB system and the hemichannel/pannexon-mediated signaling in the inflamed brain and during event of synaptic plasticity. Most findings indicate that eCBs seem to counteract the activation of major neuroinflammatory pathways that lead to glia-mediated production of TNF-α and IL-1β, both well-known triggers of astroglial hemichannel opening. In contrast to the latter, in the normal brain, eCBs apparently elicit the Ca2+-activation of astrocyte hemichannels, which could have significant consequences on eCB-dependent synaptic plasticity.
Collapse
Affiliation(s)
- Valeria C Labra
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Cristian A Santibáñez
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Rosario Gajardo-Gómez
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Esteban F Díaz
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Gonzalo I Gómez
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Investigación y Estudio del Consumo de Alcohol en Adolescentes, Santiago, Chile
| |
Collapse
|
29
|
Svobodova I, Bhattaracharya A, Ivetic M, Bendova Z, Zemkova H. Circadian ATP Release in Organotypic Cultures of the Rat Suprachiasmatic Nucleus Is Dependent on P2X7 and P2Y Receptors. Front Pharmacol 2018; 9:192. [PMID: 29559915 PMCID: PMC5845546 DOI: 10.3389/fphar.2018.00192] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 02/20/2018] [Indexed: 01/22/2023] Open
Abstract
The circadian rhythms in physiological and behavioral functions are driven by a pacemaker located in the suprachiasmatic nucleus (SCN). The rhythms continue in constant darkness and depend on cell-cell communication between neurons and glia. The SCN astrocytes generate also a circadian rhythm in extracellular adenosine 5′-triphosphate (ATP) accumulation, but molecular mechanisms that regulate ATP release are poorly understood. Here, we tested the hypothesis that ATP is released via the plasma membrane purinergic P2X7 receptors (P2X7Rs) and P2Y receptors (P2YRs) which have been previously shown to be expressed in the SCN tissue at transcriptional level. We have investigated this hypothesis using SCN organotypic cultures, primary cultures of SCN astrocytes, ATP bioluminescent assays, immunohistochemistry, patch-clamping, and calcium imaging. We found that extracellular ATP accumulation in organotypic cultures followed a circadian rhythm, with a peak between 24:00 and 04:00 h, and the trough at ~12:00 h. ATP rhythm was inhibited by application of AZ10606120, A438079, and BBG, specific blockers of P2X7R, and potentiated by GW791343, a positive allosteric modulator of this receptor. Double-immunohistochemical staining revealed high expression of the P2X7R protein in astrocytes of SCN slices. PPADS, a non-specific P2 antagonist, and MRS2179, specific P2Y1R antagonist, also abolished ATP rhythm, whereas the specific P2X4R blocker 5-BDBD was not effective. The pannexin-1 hemichannel blocker carbenoxolone displayed a partial inhibitory effect. The P2Y1R agonist MRS2365, and the P2Y2R agonist MRS2768 potentiated ATP release in organotypic cultures and increase intracellular Ca2+ level in cultured astrocytes. Thus, SCN utilizes multiple purinergic receptor systems and pannexin-1 hemichannels to release ATP.
Collapse
Affiliation(s)
- Irena Svobodova
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czechia
| | - Anirban Bhattaracharya
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czechia
| | - Milorad Ivetic
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czechia
| | - Zdenka Bendova
- Department of Physiology, Faculty of Science, Charles University, Prague, Czechia
| | - Hana Zemkova
- Department of Cellular and Molecular Neuroendocrinology, Institute of Physiology of the Czech Academy of Sciences, Prague, Czechia
| |
Collapse
|
30
|
Abstract
The role traditionally assigned to astrocytes in the pathogenesis of multiple sclerosis (MS) lesions has been the formation of the glial scar once inflammation has subsided. Astrocytes are now recognized to be early and highly active players during lesion formation and key for providing peripheral immune cells access to the central nervous system. Here, we review the role of astrocytes in the formation and evolution of MS lesions, including the recently described functional polarization of astrocytes, discuss prototypical pathways for astrocyte activation, and summarize mechanisms by which MS treatments affect astrocyte function.
Collapse
Affiliation(s)
- Gerald Ponath
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
| | - Calvin Park
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
| | - David Pitt
- Department of Neurology, Yale School of Medicine, New Haven, CT, United States
| |
Collapse
|
31
|
Xing F, Zhang P, Jiang P, Chen Z, Yang J, Hu F, Drevenšek-Olenik I, Zhang X, Pan L, Xu J. Spatiotemporal Characteristics of Intercellular Calcium Wave Communication in Micropatterned Assemblies of Single Cells. ACS APPLIED MATERIALS & INTERFACES 2018; 10:2937-2945. [PMID: 29283550 DOI: 10.1021/acsami.7b15759] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Micropatterned substrates offer a unique possibility to define and control spatial organization of biological cells at the microscale, which greatly facilitates investigations of the cell-to-cell communication in vitro. Here, we developed a simple micropatterning strategy to resolve various spatiotemporal characteristics of intercellular calcium wave (ICW) communication among isolated BV-2 microglial cells. By using a single-ring assembly, we found that the direction of the initial transmitter secretion was strongly correlated with the site of the cell at which the mechanical stimulus triggering the ICWs was imposed. By using multiring assemblies, we observed that the response ratio of the same outmost cells 160 μm away from the center increased from 0% in the single-ring assembly to 9.6% in the four-ring assembly. This revealed that cells located in the interring acted as regenerative amplifiers for the ICWs generated by the central cell. By using a special oval-type micropattern, we found that calcium mobilization in lamellipodia of a fusiform BV-2 microglia cell occurred 2.9 times faster than that in the middle part of the cell, demonstrating a higher region-specific sensitivity of lamellipodia to the transmitter. Taken together, our micropatterning strategy opened up new experimental prospects to study ICWs and revealed novel spatiotemporal characteristics of ICW communication including stimulation site-dependent secretion, regenerative propagation, and region-specific cell sensitivity.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Irena Drevenšek-Olenik
- Faculty of Mathematics and Physics, University of Ljubljana, and J. Stefan Institute , Ljubljana SI1000, Slovenia
| | | | | | - Jingjun Xu
- Collaborative Innovation Center of Extreme Optics, Shanxi University , Taiyuan, Shanxi 030006, China
| |
Collapse
|
32
|
Role of Purinergic Receptor P2Y1 in Spatiotemporal Ca 2+ Dynamics in Astrocytes. J Neurosci 2018; 38:1383-1395. [PMID: 29305530 DOI: 10.1523/jneurosci.2625-17.2017] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 12/06/2017] [Accepted: 12/18/2017] [Indexed: 01/08/2023] Open
Abstract
Fine processes of astrocytes enwrap synapses and are well positioned to sense neuronal information via synaptic transmission. In rodents, astrocyte processes sense synaptic transmission via Gq-protein coupled receptors (GqPCR), including the P2Y1 receptor (P2Y1R), to generate Ca2+ signals. Astrocytes display numerous spontaneous microdomain Ca2+ signals; however, it is not clear whether such signals are due to local synaptic transmission and/or in what timeframe astrocytes sense local synaptic transmission. To ask whether GqPCRs mediate microdomain Ca2+ signals, we engineered mice (both sexes) to specifically overexpress P2Y1Rs in astrocytes, and we visualized Ca2+ signals via a genetically encoded Ca2+ indicator, GCaMP6f, in astrocytes from adult mice. Astrocytes overexpressing P2Y1Rs showed significantly larger Ca2+ signals in response to exogenously applied ligand and to repetitive electrical stimulation of axons compared with controls. However, we found no evidence of increased microdomain Ca2+ signals. Instead, Ca2+ waves appeared and propagated to occupy areas that were up to 80-fold larger than microdomain Ca2+ signals. These Ca2+ waves accounted for only 2% of total Ca2+ events, but they were 1.9-fold larger and 2.9-fold longer in duration than microdomain Ca2+ signals at processes. Ca2+ waves did not require action potentials for their generation and occurred in a probenecid-sensitive manner, indicating that the endogenous ligand for P2Y1R is elevated independently of synaptic transmission. Our data suggest that spontaneous microdomain Ca2+ signals occur independently of P2Y1R activation and that astrocytes may not encode neuronal information in response to synaptic transmission at a point source of neurotransmitter release.SIGNIFICANCE STATEMENT Astrocytes are thought to enwrap synapses with their processes to receive neuronal information via Gq-protein coupled receptors (GqPCRs). Astrocyte processes display numerous microdomain Ca2+ signals that occur spontaneously. To determine whether GqPCRs play a role in microdomain Ca2+ signals and the timeframe in which astrocytes sense neuronal information, we engineered mice whose astrocytes specifically overexpress the P2Y1 receptor, a major GqPCR in astrocytes. We found that overexpression of P2Y1 receptors in astrocytes did not increase microdomain Ca2+ signals in astrocyte processes but caused Ca2+ wavelike signals. Our data indicate that spontaneous microdomain Ca2+ signals do not require activation of P2Y1 receptors.
Collapse
|
33
|
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
|
34
|
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: 876] [Impact Index Per Article: 146.0] [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
|
35
|
Evidence for astrocyte purinergic signaling in cortical sensory adaptation and serotonin-mediated neuromodulation. Mol Cell Neurosci 2017; 88:53-61. [PMID: 29277734 DOI: 10.1016/j.mcn.2017.12.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 12/16/2017] [Accepted: 12/19/2017] [Indexed: 11/22/2022] Open
Abstract
In the somatosensory cortex, inhibitory networks are involved in low frequency sensory input adaptation/habituation that can be observed as a paired-pulse depression when using a dual stimulus electrophysiological paradigm. Given that astrocytes have been shown to regulate inhibitory interneuron activity, we hypothesized that astrocytes are involved in cortical sensory adaptation/habituation and constitute effectors of the 5HT-mediated increase in frequency transmission. Using extracellular recordings of evoked excitatory postsynaptic potentials (eEPSPs) in layer II/III of somatosensory cortex, we used various pharmacological approaches to assess the recruitment of astrocyte signaling in paired-pulse depression and serotonin-mediated increase in the paired-pulse ratio (pulse 2/pulse 1). In the absence of neuromodulators or pharmacological agents, the first eEPSP is much larger in amplitude than the second due to the recruitment of long-lasting evoked GABAA-dependent inhibitory activity from the first stimulus. Disruption of glycolysis or mGluR5 signaling resulted in a very similar loss of paired-pulse depression in field recordings. Interestingly, paired-pulse depression was similarly sensitive to disruption by ATP P2Y and adenosine A2A receptor antagonists. In addition, we show that pharmacological disruption of paired-pulse depression by mGluR5, P2Y, and glycolysis inhibition precluded serotonin effects on frequency transmission (typically increased the paired-pulse ratio). These data highlight the possibility for astrocyte involvement in cortical inhibitory activity seen in this simple cortical network and that serotonin may act on astrocytes to exert some aspects of its modulatory influence.
Collapse
|
36
|
Conley JM, Radhakrishnan S, Valentino SA, Tantama M. Imaging extracellular ATP with a genetically-encoded, ratiometric fluorescent sensor. PLoS One 2017; 12:e0187481. [PMID: 29121644 PMCID: PMC5679667 DOI: 10.1371/journal.pone.0187481] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Accepted: 09/08/2017] [Indexed: 01/04/2023] Open
Abstract
Extracellular adenosine triphosphate (ATP) is a key purinergic signal that mediates cell-to-cell communication both within and between organ systems. We address the need for a robust and minimally invasive approach to measuring extracellular ATP by re-engineering the ATeam ATP sensor to be expressed on the cell surface. Using this approach, we image real-time changes in extracellular ATP levels with a sensor that is fully genetically-encoded and does not require an exogenous substrate. In addition, the sensor is ratiometric to allow for reliable quantitation of extracellular ATP fluxes. Using live-cell microscopy, we characterize sensor performance when expressed on cultured Neuro2A cells, and we measure both stimulated release of ATP and its clearance by ectonucleotidases. Thus, this proof-of-principle demonstrates a first-generation sensor to report extracellular ATP dynamics that may be useful for studying purinergic signaling in living specimens.
Collapse
Affiliation(s)
- Jason M. Conley
- Department of Chemistry, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana, United States of America
| | - Saranya Radhakrishnan
- Department of Chemistry, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Interdisciplinary Life Science Graduate Program, Purdue University, West Lafayette, Indiana, United States of America
| | - Stephen A. Valentino
- Department of Chemistry, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana, United States of America
| | - Mathew Tantama
- Department of Chemistry, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Interdisciplinary Life Science Graduate Program, Purdue University, West Lafayette, Indiana, United States of America
- Purdue Institute for Inflammation, Immunology, & Infectious Disease, Purdue University, West Lafayette, Indiana, United States of America
- * E-mail:
| |
Collapse
|
37
|
Taheri M, Handy G, Borisyuk A, White JA. Diversity of Evoked Astrocyte Ca 2+ Dynamics Quantified through Experimental Measurements and Mathematical Modeling. Front Syst Neurosci 2017; 11:79. [PMID: 29109680 PMCID: PMC5660282 DOI: 10.3389/fnsys.2017.00079] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Accepted: 10/04/2017] [Indexed: 01/06/2023] Open
Abstract
Astrocytes are a major cell type in the mammalian brain. They are not electrically excitable, but generate prominent Ca2+ signals related to a wide variety of critical functions. The mechanisms driving these Ca2+ events remain incompletely understood. In this study, we integrate Ca2+ imaging, quantitative data analysis, and mechanistic computational modeling to study the spatial and temporal heterogeneity of cortical astrocyte Ca2+ transients evoked by focal application of ATP in mouse brain slices. Based on experimental results, we tune a single-compartment mathematical model of IP3-dependent Ca2+ responses in astrocytes and use that model to study response heterogeneity. Using information from the experimental data and the underlying bifurcation structure of our mathematical model, we categorize all astrocyte Ca2+ responses into four general types based on their temporal characteristics: Single-Peak, Multi-Peak, Plateau, and Long-Lasting responses. We find that the distribution of experimentally-recorded response types depends on the location within an astrocyte, with somatic responses dominated by Single-Peak (SP) responses and large and small processes generating more Multi-Peak responses. On the other hand, response kinetics differ more between cells and trials than with location within a given astrocyte. We use the computational model to elucidate possible sources of Ca2+ response variability: (1) temporal dynamics of IP3, and (2) relative flux rates through Ca2+ channels and pumps. Our model also predicts the effects of blocking Ca2+ channels/pumps; for example, blocking store-operated Ca2+ (SOC) channels in the model eliminates Plateau and Long-Lasting responses (consistent with previous experimental observations). Finally, we propose that observed differences in response type distributions between astrocyte somas and processes can be attributed to systematic differences in IP3 rise durations and Ca2+ flux rates.
Collapse
Affiliation(s)
- Marsa Taheri
- Department of Bioengineering, University of Utah, Salt Lake City, UT, United States
| | - Gregory Handy
- Department of Mathematics, University of Utah, Salt Lake City, UT, United States
| | - Alla Borisyuk
- Department of Mathematics, University of Utah, Salt Lake City, UT, United States
| | - John A White
- Department of Biomedical Engineering, Boston University, Boston, MA, United States
| |
Collapse
|
38
|
Lohman AW, Weilinger NL, Santos SM, Bialecki J, Werner AC, Anderson CL, Thompson RJ. Regulation of pannexin channels in the central nervous system by Src family kinases. Neurosci Lett 2017; 695:65-70. [PMID: 28911820 DOI: 10.1016/j.neulet.2017.09.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 07/24/2017] [Accepted: 09/10/2017] [Indexed: 02/06/2023]
Abstract
Pannexins form single membrane channels that regulate the passage of ions, small molecules and metabolites between the intra- and extracellular compartments. In the central nervous system, these channels are integrated into numerous signaling cascades that shape brain physiology and pathology. Post-translational modification of pannexins is complex, with phosphorylation emerging as a prominent form of functional regulation. While much is still not known regarding the specific kinases and modified amino acids, recent reports support a role for Src family tyrosine kinases (SFK) in regulating pannexin channel activity. This review outlines the current evidence supporting SFK-dependent pannexin phosphorylation in the CNS and examines the importance of these modifications in the healthy and diseased brain.
Collapse
Affiliation(s)
- Alexander W Lohman
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Nicholas L Weilinger
- Djavad Mowafaghian Centre for Brain Health, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Silva Mf Santos
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Jennifer Bialecki
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Allison C Werner
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Connor L Anderson
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada
| | - Roger J Thompson
- Department of Cell Biology and Anatomy, University of Calgary, Calgary, Alberta, Canada; Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada.
| |
Collapse
|
39
|
Cytokine IL-10, activators of PI3-kinase, agonists of α-2 adrenoreceptor and antioxidants prevent ischemia-induced cell death in rat hippocampal cultures. Arch Biochem Biophys 2017; 615:35-43. [PMID: 28063948 DOI: 10.1016/j.abb.2017.01.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 12/21/2016] [Accepted: 01/03/2017] [Indexed: 12/27/2022]
Abstract
In the present work we compared the protective effect of anti-inflammatory cytokine IL-10 with the action of a PI3-kinase selective activator 740 Y-P, selective agonists of alpha-2 adrenoreceptor, guanfacine and UK-14,304, and compounds having antioxidant effect: recombinant human peroxiredoxin 6 and B27, in hippocampal cell culture during OGD (ischemia-like conditions). It has been shown that the response of cells to OGD in the control includes two phases. The first phase was accompanied by an increase in the frequency of spontaneous synchronous Ca2+-oscillations (SSCO) in neurons and Ca2+-pulse in astrocytes. Spontaneous Ca2+ events in astrocytes during ischemia in control experiments disappeared. The second phase started after a few minutes of OGD and looked like a sharp/avalanche, global synchronic (within 20 s) increase in [Ca2+]i in many cells. Within 1 h after OGD, a mass death of cells, primarily astrocytes, was observed. To study the protective action of the compounds, cells were incubated in the presence of the neuroprotective agents for 10-40 min or 24 h before ischemia. All the neuroprotective agents delayed a global [Ca2+]i increase during OGD or completely inhibited this process and increased cell survival.
Collapse
|
40
|
Furuta T, Mukai A, Ohishi A, Nishida K, Nagasawa K. Oxidative stress-induced increase of intracellular zinc in astrocytes decreases their functional expression of P2X7 receptors and engulfing activity. Metallomics 2017; 9:1839-1851. [DOI: 10.1039/c7mt00257b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Exposure of astrocytes to oxidative stress induces an increase of intracellular labile zinc and a decrease of functional expression of P2X7 receptorviaits translocation from the plasma membrane to the cytosol by altering the expression profile of P2X7 receptor and its splice variants, leading to a decrease of their engulfing activity.
Collapse
Affiliation(s)
- Takahiro Furuta
- Department of Environmental Biochemistry
- Kyoto Pharmaceutical University
- Yamashina-ku
- Japan
| | - Ayumi Mukai
- Department of Environmental Biochemistry
- Kyoto Pharmaceutical University
- Yamashina-ku
- Japan
| | - Akihiro Ohishi
- Department of Environmental Biochemistry
- Kyoto Pharmaceutical University
- Yamashina-ku
- Japan
| | - Kentaro Nishida
- Department of Environmental Biochemistry
- Kyoto Pharmaceutical University
- Yamashina-ku
- Japan
| | - Kazuki Nagasawa
- Department of Environmental Biochemistry
- Kyoto Pharmaceutical University
- Yamashina-ku
- Japan
| |
Collapse
|
41
|
Barańska J, Czajkowski R, Pomorski P. P2Y 1 Receptors - Properties and Functional Activities. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017. [PMID: 28639247 DOI: 10.1007/5584_2017_57] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
In this chapter we try to show a comprehensive image of current knowledge of structure, activity and physiological role of the P2Y1 purinergic receptor. The structure, distribution and changes in the expression of this receptor are summarized, as well as the mechanism of its signaling activity by the intracellular calcium mobilization. We try to show the connection between the components of its G protein activation and cellular or physiological effects, starting from changes in protein phosphorylation patterns and ending with such remote effects as receptor-mediated apoptosis. The special emphasis is put on the role of the P2Y1 receptor in cancer cells and neuronal plasticity. We concentrate on the P2Y1 receptor, it is though impossible to completely abstract from other aspects of nucleotide signaling and cross-talk with other nucleotide receptors is here discussed. Especially, the balance between P2Y1 and P2Y12 receptors, sharing the same ligand but signaling through different pathways, is presented.
Collapse
Affiliation(s)
- Jolanta Barańska
- Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., PL 02-093, Warsaw, Poland
| | - Rafał Czajkowski
- Laboratory of Spatial Memory, Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., PL 02-093, Warsaw, Poland
| | - Paweł Pomorski
- Laboratory of Molecular Basis of Cell Motility, Department of Cell Biochemistry, Nencki Institute of Experimental Biology, Polish Academy of Sciences, 3 Pasteur St., PL 02-093, Warsaw, Poland.
| |
Collapse
|
42
|
Tzour A, Leibovich H, Barkai O, Biala Y, Lev S, Yaari Y, Binshtok AM. K V 7/M channels as targets for lipopolysaccharide-induced inflammatory neuronal hyperexcitability. J Physiol 2016; 595:713-738. [PMID: 27506492 DOI: 10.1113/jp272547] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Accepted: 07/27/2016] [Indexed: 12/11/2022] Open
Abstract
KEY POINTS Neuroinflammation associated with CNS insults leads to neuronal hyperexcitability, which may culminate in epileptiform discharges. Application of the endotoxin lipopolysaccharide (LPS) to brain tissue initiates a neuroinflammatory cascade, providing an experimental model to study the mechanisms of neuroinflammatory neuronal hyperexcitability. Here we show that LPS application to hippocampal slices markedly enhances the excitability of CA1 pyramidal cells by inhibiting a specific potassium current, the M-current, generated by KV 7/M channels, which controls the excitability of almost every neuron in the CNS. The LPS-induced M-current inhibition is triggered by sequential activation of microglia, astrocytes and pyramidal cells, mediated by metabotropic purinergic and glutamatergic transmission, leading to blockade of KV 7/M channels by calcium released from intracellular stores. The identification of the downstream molecular target of neuroinflammation, namely the KV 7/M channel, potentially has far reaching implications for the understanding and treatment of many acute and chronic brain disorders. ABSTRACT Acute brain insults and many chronic brain diseases manifest an innate inflammatory response. The hallmark of this response is glia activation, which promotes repair of damaged tissue, but also induces structural and functional changes that may lead to an increase in neuronal excitability. We have investigated the mechanisms involved in the modulation of neuronal activity by acute inflammation. Initiating inflammatory responses in hippocampal tissue rapidly led to neuronal depolarization and repetitive firing even in the absence of active synaptic transmission. This action was mediated by a complex metabotropic purinergic and glutamatergic glia-to-neuron signalling cascade, leading to the blockade of neuronal KV 7/M channels by Ca2+ released from internal stores. These channels generate the low voltage-activating, non-inactivating M-type K+ current (M-current) that controls intrinsic neuronal excitability, and its inhibition was the predominant cause of the inflammation-induced hyperexcitability. Our discovery that the ubiquitous KV 7/M channels are the downstream target of the inflammation-induced cascade, has far reaching implications for the understanding and treatment of many acute and chronic brain disorders.
Collapse
Affiliation(s)
- Arik Tzour
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| | - Hodaya Leibovich
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| | - Omer Barkai
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| | - Yoav Biala
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
| | - Shaya Lev
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| | - Yoel Yaari
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel
| | - Alexander M Binshtok
- Department of Medical Neurobiology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah School of Medicine, Jerusalem, 91120, Israel.,The Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Israel
| |
Collapse
|
43
|
Gajardo-Gómez R, Labra VC, Orellana JA. Connexins and Pannexins: New Insights into Microglial Functions and Dysfunctions. Front Mol Neurosci 2016; 9:86. [PMID: 27713688 PMCID: PMC5031785 DOI: 10.3389/fnmol.2016.00086] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 09/05/2016] [Indexed: 12/11/2022] Open
Abstract
Under physiological conditions, microglia adopt a resting phenotype associated with the production of anti-inflammatory and neurotrophic factors. In response to a wide variety of insults, these cells shift to an activated phenotype that is necessary for the proper restoration of brain homeostasis. However, when the intensity of a threat is relatively high, microglial activation worsens the progression of damage rather than providing protection, with potentially significant consequences for neuronal survival. Coordinated interactions among microglia and other brain cells, including astrocytes and neurons, are critical for the development of timely and optimal inflammatory responses in the brain parenchyma. Tissue synchronization is in part mediated by connexins and pannexins, which are protein families that form different plasma membrane channels to communicate with neighboring cells. Gap junction channels (which are exclusively formed by connexins in vertebrates) connect the cytoplasm of contacting cells to coordinate electrical and metabolic coupling. Hemichannels (HCs) and pannexons (which are formed by connexins and pannexins, respectively) communicate the intra- and extracellular compartments and serve as diffusion pathways for the exchange of ions and small molecules. In this review article, we discuss the available evidence concerning the functional expression and regulation of connexin- and pannexin-based channels in microglia and their contributions to microglial function and dysfunction. Specifically, we focus on the possible implications of these channels in microglia-to-microglia, microglia-to-astrocyte and neuron-to-microglia interactions in the inflamed brain.
Collapse
Affiliation(s)
- Rosario Gajardo-Gómez
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Valeria C Labra
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Juan A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile Santiago, Chile
| |
Collapse
|
44
|
Dodds KN, Beckett EAH, Evans SF, Grace PM, Watkins LR, Hutchinson MR. Glial contributions to visceral pain: implications for disease etiology and the female predominance of persistent pain. Transl Psychiatry 2016; 6:e888. [PMID: 27622932 PMCID: PMC5048206 DOI: 10.1038/tp.2016.168] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Revised: 07/14/2016] [Accepted: 07/22/2016] [Indexed: 12/27/2022] Open
Abstract
In the central nervous system, bidirectional signaling between glial cells and neurons ('neuroimmune communication') facilitates the development of persistent pain. Spinal glia can contribute to heightened pain states by a prolonged release of neurokine signals that sensitize adjacent centrally projecting neurons. Although many persistent pain conditions are disproportionately common in females, whether specific neuroimmune mechanisms lead to this increased susceptibility remains unclear. This review summarizes the major known contributions of glia and neuroimmune interactions in pain, which has been determined principally in male rodents and in the context of somatic pain conditions. It is then postulated that studying neuroimmune interactions involved in pain attributed to visceral diseases common to females may offer a more suitable avenue for investigating unique mechanisms involved in female pain. Further, we discuss the potential for primed spinal glia and subsequent neurogenic inflammation as a contributing factor in the development of peripheral inflammation, therefore, representing a predisposing factor for females in developing a high percentage of such persistent pain conditions.
Collapse
Affiliation(s)
- K N Dodds
- Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - E A H Beckett
- Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
| | - S F Evans
- Discipline of Pharmacology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
- Pelvic Pain SA, Norwood, SA, Australia
| | - P M Grace
- Discipline of Pharmacology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - L R Watkins
- Department of Psychology and Neuroscience, Center for Neuroscience, University of Colorado Boulder, Boulder, CO, USA
| | - M R Hutchinson
- Discipline of Physiology, School of Medicine, University of Adelaide, Adelaide, SA, Australia
- ARC Centre of Excellence for Nanoscale BioPhotonics, University of Adelaide, Adelaide, SA, Australia
| |
Collapse
|
45
|
Urothelial ATP exocytosis: regulation of bladder compliance in the urine storage phase. Sci Rep 2016; 6:29761. [PMID: 27412485 PMCID: PMC4944198 DOI: 10.1038/srep29761] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 06/24/2016] [Indexed: 12/30/2022] Open
Abstract
The bladder urothelium is more than just a barrier. When the bladder is distended, the urothelium functions as a sensor to initiate the voiding reflex, during which it releases ATP via multiple mechanisms. However, the mechanisms underlying this ATP release in response to the various stretch stimuli caused by bladder filling remain largely unknown. Therefore, the aim of this study was to elucidate these mechanisms. By comparing vesicular nucleotide transporter (VNUT)-deficient and wild-type male mice, we showed that ATP has a crucial role in urine storage through exocytosis via a VNUT-dependent mechanism. VNUT was abundantly expressed in the bladder urothelium, and when the urothelium was weakly stimulated (i.e. in the early filling stages), it released ATP by exocytosis. VNUT-deficient mice showed reduced bladder compliance from the early storage phase and displayed frequent urination in inappropriate places without a change in voiding function. We conclude that urothelial, VNUT-dependent ATP exocytosis is involved in urine storage mechanisms that promote the relaxation of the bladder during the early stages of filling.
Collapse
|
46
|
Purinergic P2Y1 Receptors Control Rapid Expression of Plasma Membrane Processes in Hippocampal Astrocytes. Mol Neurobiol 2016; 54:4081-4093. [PMID: 27318677 DOI: 10.1007/s12035-016-9955-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 06/06/2016] [Indexed: 10/21/2022]
Abstract
Astrocytes regulate neuronal activity and blood brain barrier through tiny plasma membrane branches or astrocytic processes (APs) making contact with synapses and brain vessels. Several transmitters released by astrocytes and exerting their action on several receptor classes expressed by astrocytes themselves influence their physiology. Here we found that APs are dynamically modulated by purines. In live imaging experiments carried out in rat hippocampal astrocytes, Gq-coupled P2Y1 receptor blockade with the selective antagonist MRS2179 (1 μM) or inhibition of its effector phospholipase C using U73122 (3 μM) produced APs retraction, while stimulation of the same receptor with the selective agonist 2MeSADP (100 μM) increased their number. Since astrocytes, among other transmitters, release ATP by several mechanisms including connexin hemichannels, we used the connexin hemichannel inhibitor carbenoxolone (100 μM) and APs retraction was observed. In our system we then measured expression or function of channels important for modulation of volume transmission and K+ buffering, aquaporin-4, and K+ inward rectifying (Kir) channels, respectively. Aquaporin-4 expression level did not change whereas, in whole-cell patch-clamp recordings performed to measure Kir current, we observed an increase in K+ current in all conditions where APs number was reduced. These data are supporting the idea of a dynamic modulation of astrocytic processes by purinergic signal, strengthening the role of purines in brain homeostasis.
Collapse
|
47
|
Filosa JA, Morrison HW, Iddings JA, Du W, Kim KJ. Beyond neurovascular coupling, role of astrocytes in the regulation of vascular tone. Neuroscience 2016; 323:96-109. [PMID: 25843438 PMCID: PMC4592693 DOI: 10.1016/j.neuroscience.2015.03.064] [Citation(s) in RCA: 138] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 03/24/2015] [Accepted: 03/27/2015] [Indexed: 12/22/2022]
Abstract
The brain possesses two intricate mechanisms that fulfill its continuous metabolic needs: cerebral autoregulation, which ensures constant cerebral blood flow over a wide range of arterial pressures and functional hyperemia, which ensures rapid delivery of oxygen and glucose to active neurons. Over the past decade, a number of important studies have identified astrocytes as key intermediaries in neurovascular coupling (NVC), the mechanism by which active neurons signal blood vessels to change their diameter. Activity-dependent increases in astrocytic Ca(2+) activity are thought to contribute to the release of vasoactive substances that facilitate arteriole vasodilation. A number of vasoactive signals have been identified and their role on vessel caliber assessed both in vitro and in vivo. In this review, we discuss mechanisms implicating astrocytes in NVC-mediated vascular responses, limitations encountered as a result of the challenges in maintaining all the constituents of the neurovascular unit intact and deliberate current controversial findings disputing a main role for astrocytes in NVC. Finally, we briefly discuss the potential role of pericytes and microglia in NVC-mediated processes.
Collapse
Affiliation(s)
- J A Filosa
- Georgia Regents University, 1120 15th Street, Augusta, GA 30912, United States.
| | - H W Morrison
- University of Arizona, 1305 N. Martin Avenue, P.O. Box 210203, Tucson, AZ 85721, United States
| | - J A Iddings
- Georgia Regents University, 1120 15th Street, Augusta, GA 30912, United States
| | - W Du
- Georgia Regents University, 1120 15th Street, Augusta, GA 30912, United States
| | - K J Kim
- Georgia Regents University, 1120 15th Street, Augusta, GA 30912, United States
| |
Collapse
|
48
|
Chatton JY, Magistretti PJ, Barros LF. Sodium signaling and astrocyte energy metabolism. Glia 2016; 64:1667-76. [PMID: 27027636 DOI: 10.1002/glia.22971] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Revised: 01/10/2016] [Accepted: 01/13/2016] [Indexed: 12/21/2022]
Abstract
The Na(+) gradient across the plasma membrane is constantly exploited by astrocytes as a secondary energy source to regulate the intracellular and extracellular milieu, and discard waste products. One of the most prominent roles of astrocytes in the brain is the Na(+) -dependent clearance of glutamate released by neurons during synaptic transmission. The intracellular Na(+) load collectively generated by these processes converges at the Na,K-ATPase pump, responsible for Na(+) extrusion from the cell, which is achieved at the expense of cellular ATP. These processes represent pivotal mechanisms enabling astrocytes to increase the local availability of metabolic substrates in response to neuronal activity. This review presents basic principles linking the intracellular handling of Na(+) following activity-related transmembrane fluxes in astrocytes and the energy metabolic pathways involved. We propose a role of Na(+) as an energy currency and as a mediator of metabolic signals in the context of neuron-glia interactions. We further discuss the possible impact of the astrocytic syncytium for the distribution and coordination of the metabolic response, and the compartmentation of these processes in cellular microdomains and subcellular organelles. Finally, we illustrate future avenues of investigation into signaling mechanisms aimed at bridging the gap between Na(+) and the metabolic machinery. GLIA 2016;64:1667-1676.
Collapse
Affiliation(s)
- Jean-Yves Chatton
- Department of Fundamental Neurosciences, University of Lausanne, Rue Du Bugnon 9, Lausanne, Switzerland
| | - Pierre J Magistretti
- King Abdullah University of Science and Technology (KAUST), Thuwal, Kingdom of Saudi Arabia.,Brain Mind Institute, Ecole Polytechnique Fédérale De Lausanne (EPFL), Lausanne, Switzerland
| | | |
Collapse
|
49
|
George J, Cunha RA, Mulle C, Amédée T. Microglia-derived purines modulate mossy fibre synaptic transmission and plasticity through P2X4 and A1 receptors. Eur J Neurosci 2016; 43:1366-78. [PMID: 27199162 PMCID: PMC5069607 DOI: 10.1111/ejn.13191] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 01/21/2016] [Indexed: 12/15/2022]
Abstract
Recent data have provided evidence that microglia, the brain‐resident macrophage‐like cells, modulate neuronal activity in both physiological and pathophysiological conditions, and microglia are therefore now recognized as synaptic partners. Among different neuromodulators, purines, which are produced and released by microglia, have emerged as promising candidates to mediate interactions between microglia and synapses. The cellular effects of purines are mediated through a large family of receptors for adenosine and for ATP (P2 receptors). These receptors are present at brain synapses, but it is unknown whether they can respond to microglia‐derived purines to modulate synaptic transmission and plasticity. Here, we used a simple model of adding immune‐challenged microglia to mouse hippocampal slices to investigate their impact on synaptic transmission and plasticity at hippocampal mossy fibre (MF) synapses onto CA3 pyramidal neurons. MF–CA3 synapses show prominent forms of presynaptic plasticity that are involved in the encoding and retrieval of memory. We demonstrate that microglia‐derived ATP differentially modulates synaptic transmission and short‐term plasticity at MF–CA3 synapses by acting, respectively, on presynaptic P2X4 receptors and on adenosine A1 receptors after conversion of extracellular ATP to adenosine. We also report that P2X4 receptors are densely located in the mossy fibre tract in the dentate gyrus–CA3 circuitry. In conclusion, this study reveals an interplay between microglia‐derived purines and MF–CA3 synapses, and highlights microglia as potent modulators of presynaptic plasticity.
Collapse
Affiliation(s)
- Jimmy George
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, Bordeaux, France.,CNC Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC Centre for Neuroscience and Cell Biology, University of Coimbra, Coimbra, Portugal.,Faculty of Medicine, University of Coimbra, Coimbra, Portugal
| | - Christophe Mulle
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, Bordeaux, France
| | - Thierry Amédée
- Interdisciplinary Institute for Neuroscience, CNRS UMR 5297, University of Bordeaux, Bordeaux, France.,IINS, UMR 5297 CNRS - Université de Bordeaux, Bordeaux Cedex, France
| |
Collapse
|
50
|
1,3-Dinitrobenzene neurotoxicity - Passage effect in immortalized astrocytes. Neurotoxicology 2016; 53:74-84. [PMID: 26769196 DOI: 10.1016/j.neuro.2015.11.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 11/16/2015] [Accepted: 11/18/2015] [Indexed: 11/21/2022]
Abstract
Age-related disturbances in astrocytic mitochondrial function are linked to loss of neuroprotection and decrements in neurological function. The immortalized rat neocortical astrocyte-derived cell line, DI-TNC1, provides a convenient model for the examination of cellular aging processes that are difficult to study in primary cell isolates from aged brain. Successive passages in culture may serve as a surrogate of aging in which time-dependent adaptation to culture conditions may result in altered responses to xenobiotic challenge. To investigate the hypothesis that astrocytic mitochondrial homeostatic function is decreased with time in culture, low passage DI-TNC1 astrocytes (LP; #2-8) and high passage DI-TNC1 astrocytes (HP; #17-28) were exposed to the mitochondrial neurotoxicant 1,3-dinitrobenzene (DNB). Cells were exposed in either monoculture or in co-culture with primary cortical neurons. Astrocyte mitochondrial membrane potential, morphology, ATP production and proliferation were monitored in monoculture, and the ability of DI-TNC1 cells to buffer K(+)-induced neuronal depolarization was examined in co-cultures. In HP DI-TNC1 cells, DNB exposure decreased proliferation, reduced mitochondrial membrane potential and significantly decreased mitochondrial form factor. Low passage DI-TNC1 cells effectively attenuated K(+)-induced neuronal depolarization in the presence of DNB whereas HP counterparts were unable to buffer K(+) in DNB challenge. Following DNB challenge, LP DI-TNC1 cells exhibited greater viability in co-culture than HP. The data provide compelling evidence that there is an abrupt phenotypic change in DI-TNC1 cells between passage #9-16 that significantly diminishes the ability of DI-TNC1 cells to compensate for neurotoxic challenge and provide neuroprotective spatial buffering. Whether or not these functional changes have an in vivo analog in aging brain remains to be determined.
Collapse
|