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Courjaret R, Prakriya M, Machaca K. SOCE as a regulator of neuronal activity. J Physiol 2024; 602:1449-1462. [PMID: 37029630 DOI: 10.1113/jp283826] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2023] [Accepted: 03/28/2023] [Indexed: 04/09/2023] Open
Abstract
Store operated Ca2+ entry (SOCE) is a ubiquitous signalling module with established roles in the immune system, secretion and muscle development. Recent evidence supports a complex role for SOCE in the nervous system. In this review we present an update of the current knowledge on SOCE function in the brain with a focus on its role as a regulator of brain activity and excitability.
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Affiliation(s)
- Raphael Courjaret
- Calcium Signaling Group, Research Department, Weill Cornell Medicine Qatar, Qatar Foundation, Doha, Qatar
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York, USA
| | - Murali Prakriya
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA
| | - Khaled Machaca
- Calcium Signaling Group, Research Department, Weill Cornell Medicine Qatar, Qatar Foundation, Doha, Qatar
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, New York, USA
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2
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Lohr C. Role of P2Y receptors in astrocyte physiology and pathophysiology. Neuropharmacology 2023; 223:109311. [PMID: 36328064 DOI: 10.1016/j.neuropharm.2022.109311] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/24/2022] [Accepted: 10/27/2022] [Indexed: 11/07/2022]
Abstract
Astrocytes are active constituents of the brain that manage ion homeostasis and metabolic support of neurons and directly tune synaptic transmission and plasticity. Astrocytes express all known P2Y receptors. These regulate a multitude of physiological functions such as cell proliferation, Ca2+ signalling, gliotransmitter release and neurovascular coupling. In addition, P2Y receptors are fundamental in the transition of astrocytes into reactive astrocytes, as occurring in many brain disorders such as neurodegenerative diseases, neuroinflammation and epilepsy. This review summarizes the current literature addressing the function of P2Y receptors in astrocytes in the healthy brain as well as in brain diseases.
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Affiliation(s)
- Christian Lohr
- Institute of Cell and Systems Biology of Animals, University of Hamburg, Germany.
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3
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The Impact of the Antipsychotic Medication Chlorpromazine on Cytotoxicity through Ca 2+ Signaling Pathway in Glial Cell Models. Neurotox Res 2022; 40:791-802. [PMID: 35438391 DOI: 10.1007/s12640-022-00507-5] [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: 12/30/2021] [Revised: 04/01/2022] [Accepted: 04/09/2022] [Indexed: 10/18/2022]
Abstract
Chlorpromazine, an antipsychotic medication, is conventionally applied to cope with the psychotic disorder such as schizophrenia. In cellular studies, chlorpromazine exerts many different actions through calcium ion (Ca2+) signaling, but the underlying pathways are elusive. This study explored the effect of chlorpromazine on viability, Ca2+ signaling pathway and their relationship in glial cell models (GBM 8401 human glioblastoma cell line and Gibco® Human Astrocyte (GHA)). First, chlorpromazine between 10 and 40 μM induced cytotoxicity in GBM 8401 cells but not in GHA cells. Second, in terms of Ca2+ homeostasis, chlorpromazine (10-30 μM) increased intracellular Ca2+ concentrations ([Ca2+]i) rises in GBM 8401 cells but not in GHA cells. Ca2+ removal reduced the signal by approximately 55%. Furthermore, chelation of cytosolic Ca2+ with BAPTA-AM reduced chlorpromazine (10-40 μM)-induced cytotoxicity in GBM 8401 cells. Third, in Ca2+-containing medium of GBM 8401 cells, chlorpromazine-induced Ca2+ entry was inhibited by the modulators of store-operated Ca2+ channel (2-APB and SKF96365). Lastly, in Ca2+-free medium of GBM 8401 cells, treatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin completely inhibited chlorpromazine-increased [Ca2+]i rises. Conversely, treatment with chlorpromazine abolished thapsigargin-increased [Ca2+]i rises. Inhibition of phospholipase C (PLC) with U73122 abolished chlorpromazine-increased [Ca2+]i rises. Together, in GBM 8401 cells but not in GHA cells, chlorpromazine increased [Ca2+]i rises by Ca2+ influx via store-operated Ca2+ entry and PLC-dependent Ca2+ release from the endoplasmic reticulum. Moreover, the Ca2+ chelator BAPTA-AM inhibited cytotoxicity in chlorpromazine-treated GBM 8401 cells. Therefore, Ca2+ signaling was involved in chlorpromazine-induced cytotoxicity in GBM 8401 cells.
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4
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Lohr C, Beiersdorfer A, Fischer T, Hirnet D, Rotermund N, Sauer J, Schulz K, Gee CE. Using Genetically Encoded Calcium Indicators to Study Astrocyte Physiology: A Field Guide. Front Cell Neurosci 2021; 15:690147. [PMID: 34177468 PMCID: PMC8226001 DOI: 10.3389/fncel.2021.690147] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/06/2021] [Indexed: 01/14/2023] Open
Abstract
Ca2+ imaging is the most frequently used technique to study glial cell physiology. While chemical Ca2+ indicators served to visualize and measure changes in glial cell cytosolic Ca2+ concentration for several decades, genetically encoded Ca2+ indicators (GECIs) have become state of the art in recent years. Great improvements have been made since the development of the first GECI and a large number of GECIs with different physical properties exist, rendering it difficult to select the optimal Ca2+ indicator. This review discusses some of the most frequently used GECIs and their suitability for glial cell research.
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Affiliation(s)
- Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | | | - Timo Fischer
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Jessica Sauer
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Christine E Gee
- Institute of Synaptic Physiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
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5
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Jin T, Lin J, Gong Y, Bi X, Hu S, Lv Q, Chen J, Li X, Chen J, Zhang W, Wang M, Fu G. iPLA 2β Contributes to ER Stress-Induced Apoptosis during Myocardial Ischemia/Reperfusion Injury. Cells 2021; 10:1446. [PMID: 34207793 PMCID: PMC8227999 DOI: 10.3390/cells10061446] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 06/02/2021] [Accepted: 06/07/2021] [Indexed: 01/09/2023] Open
Abstract
Both calcium-independent phospholipase A2 beta (iPLA2β) and endoplasmic reticulum (ER) stress regulate important pathophysiological processes including inflammation, calcium homeostasis and apoptosis. However, their roles in ischemic heart disease are poorly understood. Here, we show that the expression of iPLA2β is increased during myocardial ischemia/reperfusion (I/R) injury, concomitant with the induction of ER stress and the upregulation of cell death. We further show that the levels of iPLA2β in serum collected from acute myocardial infarction (AMI) patients and in samples collected from both in vivo and in vitro I/R injury models are significantly elevated. Further, iPLA2β knockout mice and siRNA mediated iPLA2β knockdown are employed to evaluate the ER stress and cell apoptosis during I/R injury. Additionally, cell surface protein biotinylation and immunofluorescence assays are used to trace and locate iPLA2β. Our data demonstrate the increase of iPLA2β augments ER stress and enhances cardiomyocyte apoptosis during I/R injury in vitro and in vivo. Inhibition of iPLA2β ameliorates ER stress and decreases cell death. Mechanistically, iPLA2β promotes ER stress and apoptosis by translocating to ER upon myocardial I/R injury. Together, our study suggests iPLA2β contributes to ER stress-induced apoptosis during myocardial I/R injury, which may serve as a potential therapeutic target against ischemic heart disease.
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Affiliation(s)
- Tingting Jin
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
- Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China; (J.C.); (J.C.)
| | - Jun Lin
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
- Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China; (J.C.); (J.C.)
| | - Yingchao Gong
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
- Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China; (J.C.); (J.C.)
| | - Xukun Bi
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
| | - Shasha Hu
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
| | - Qingbo Lv
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
- Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China; (J.C.); (J.C.)
| | - Jiaweng Chen
- Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China; (J.C.); (J.C.)
| | - Xiaoting Li
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
| | - Jiaqi Chen
- Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China; (J.C.); (J.C.)
| | - Wenbin Zhang
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
| | - Meihui Wang
- Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China; (J.C.); (J.C.)
| | - Guosheng Fu
- Department of Cardiology, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310020, China; (T.J.); (J.L.); (Y.G.); (X.B.); (S.H.); (Q.L.); (X.L.)
- Key Laboratory of Cardiovascular Intervention and Regenerative Medicine of Zhejiang Province, Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou 310027, China; (J.C.); (J.C.)
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Moro N, Ghavim SS, Sutton RL. Massive efflux of adenosine triphosphate into the extracellular space immediately after experimental traumatic brain injury. Exp Ther Med 2021; 21:575. [PMID: 33850547 PMCID: PMC8027727 DOI: 10.3892/etm.2021.10007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2020] [Accepted: 02/02/2021] [Indexed: 12/14/2022] Open
Abstract
The aim of the current study was to determine effects of mild traumatic brain injury (TBI), with or without blockade of purinergic ATP Y1 (P2Y1) receptors or store-operated calcium channels, on extracellular levels of ATP, glutamate, glucose and lactate. Concentrations of ATP, glutamate, glucose and lactate were measured in cerebral microdialysis samples obtained from the ipsilateral cortex and underlying hippocampus of rats with mild unilateral controlled cortical impact (CCI) or sham injury. Immediately after CCI, a large release of ATP was observed in the cortex (3.53-fold increase of pre-injury value) and hippocampus (2.97-fold increase of pre-injury value), with ATP returning to the baseline levels within 20 min post-injury and remaining stable for during the 3-h sampling period. In agreement with the results of previous studies, there was a significant increase in glutamate 20 min after CCI, which was concomitant with a decrease in extracellular glucose (20 min) and an increase in lactate (40-60 min) in both brain regions after CCI. Addition of a selective P2Y1 receptor blocker (MRS2179 ammonium salt hydrate) to the microdialysis perfusate significantly lowered pre-injury ATP and glutamate levels, and eliminated the post-CCI peaks. Addition of a blocker of store-operated calcium channels [2-aminoethoxy diphenylborinate (2-APB)] to the microdialysis perfusate significantly lowered pre-injury ATP in the hippocampus, and attenuated the post-CCI peak in both the cortex and hippocampus. 2-APB treatment significantly increased baseline glutamate levels, but the values post-injury did not differ from those in the sham group. Pre-injury glucose levels, but not lactate levels, were increased by MRS2179 and decreased by 2-APB. However, none of these treatments substantially altered the CCI-induced reduction in glucose and increase in lactate in the cortex. In conclusion, the results of the present study demonstrated that a short although extensive release of ATP immediately after experimental TBI can be significantly attenuated by blockade of P2Y1 receptors or store-operated calcium channels.
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Affiliation(s)
- Nobuhiro Moro
- Brain Injury Research Center, Department of Neurosurgery, David Geffen School of Medicine, University of California, LA 90095-6901, USA.,Department of Neurological Surgery, Nihon University School of Medicine, Tokyo 173-8610, Japan
| | - Sima S Ghavim
- Brain Injury Research Center, Department of Neurosurgery, David Geffen School of Medicine, University of California, LA 90095-6901, USA
| | - Richard L Sutton
- Brain Injury Research Center, Department of Neurosurgery, David Geffen School of Medicine, University of California, LA 90095-6901, USA
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Fischer T, Prey J, Eschholz L, Rotermund N, Lohr C. Norepinephrine-Induced Calcium Signaling and Store-Operated Calcium Entry in Olfactory Bulb Astrocytes. Front Cell Neurosci 2021; 15:639754. [PMID: 33833669 PMCID: PMC8021869 DOI: 10.3389/fncel.2021.639754] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 03/02/2021] [Indexed: 11/30/2022] Open
Abstract
It is well-established that astrocytes respond to norepinephrine with cytosolic calcium rises in various brain areas, such as hippocampus or neocortex. However, less is known about the effect of norepinephrine on olfactory bulb astrocytes. In the present study, we used confocal calcium imaging and immunohistochemistry in mouse brain slices of the olfactory bulb, a brain region with a dense innervation of noradrenergic fibers, to investigate the calcium signaling evoked by norepinephrine in astrocytes. Our results show that application of norepinephrine leads to a cytosolic calcium rise in astrocytes which is independent of neuronal activity and mainly mediated by PLC/IP3-dependent internal calcium release. In addition, store-operated calcium entry (SOCE) contributes to the late phase of the response. Antagonists of both α1- and α2-adrenergic receptors, but not β-receptors, largely reduce the adrenergic calcium response, indicating that both α-receptor subtypes mediate norepinephrine-induced calcium transients in olfactory bulb astrocytes, whereas β-receptors do not contribute to the calcium transients.
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Affiliation(s)
- Timo Fischer
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Jessica Prey
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Lena Eschholz
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Natalie Rotermund
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, Department of Biology, Institute of Zoology, University of Hamburg, Hamburg, Germany
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Pham C, Hérault K, Oheim M, Maldera S, Vialou V, Cauli B, Li D. Astrocytes respond to a neurotoxic Aβ fragment with state-dependent Ca 2+ alteration and multiphasic transmitter release. Acta Neuropathol Commun 2021; 9:44. [PMID: 33726852 PMCID: PMC7968286 DOI: 10.1186/s40478-021-01146-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 02/28/2021] [Indexed: 12/13/2022] Open
Abstract
Excessive amounts of amyloid β (Aβ) peptide have been suggested to dysregulate synaptic transmission in Alzheimer's disease (AD). As a major type of glial cell in the mammalian brain, astrocytes regulate neuronal function and undergo activity alterations upon Aβ exposure. Yet the mechanistic steps underlying astrocytic responses to Aβ peptide remain to be elucidated. Here by fluorescence imaging of signaling pathways, we dissected astrocytic responses to Aβ25-35 peptide, a neurotoxic Aβ fragment present in AD patients. In native health astrocytes, Aβ25-35 evoked Ca2+ elevations via purinergic receptors, being also dependent on the opening of connexin (CX) hemichannels. Aβ25-35, however, induced a Ca2+ diminution in Aβ-preconditioned astrocytes as a result of the potentiation of the plasma membrane Ca2+ ATPase (PMCA). The PMCA and CX protein expression was observed with immunostaining in the brain tissue of hAPPJ20 AD mouse model. We also observed both Ca2+-independent and Ca2+-dependent glutamate release upon astrocytic Aβ exposure, with the former mediated by CX hemichannel and the latter by both anion channels and lysosome exocytosis. Our results suggest that Aβ peptide causes state-dependent responses in astrocytes, in association with a multiphasic release of signaling molecules. This study therefore helps to understand astrocyte engagement in AD-related amyloidopathy.
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Gopurappilly R. Pluripotent Stem Cell Derived Neurons as In Vitro Models for Studying Autosomal Recessive Parkinson's Disease (ARPD): PLA2G6 and Other Gene Loci. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1347:115-133. [PMID: 33990932 PMCID: PMC7612166 DOI: 10.1007/5584_2021_643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Parkinson's disease (PD) is a neurodegenerative motor disorder which is largely sporadic; however, some familial forms have been identified. Genetic PD can be inherited by autosomal, dominant or recessive mutations. While the dominant mutations mirror the prototype of PD with adult-onset and L-dopa-responsive cases, autosomal recessive PD (ARPD) exhibit atypical phenotypes with additional clinical manifestations. Young-onset PD is also very common with mutations in recessive gene loci. The main genes associated with ARPD are Parkin, PINK1, DJ-1, ATP13A2, FBXO7 and PLA2G6. Calcium dyshomeostasis is a mainstay in all types of PD, be it genetic or sporadic. Intriguingly, calcium imbalances manifesting as altered Store-Operated Calcium Entry (SOCE) is suggested in PLA2G6-linked PARK 14 PD. The common pathways underlying ARPD pathology, including mitochondrial abnormalities and autophagic dysfunction, can be investigated ex vivo using induced pluripotent stem cell (iPSC) technology and are discussed here. PD pathophysiology is not faithfully replicated by animal models, and, therefore, nigral dopaminergic neurons generated from iPSC serve as improved human cellular models. With no cure to date and treatments aiming at symptomatic relief, these in vitro models derived through midbrain floor-plate induction provide a platform to understand the molecular and biochemical pathways underlying PD etiology in a patient-specific manner.
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Affiliation(s)
- Renjitha Gopurappilly
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India.
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Zhang I, Hu H. Store-Operated Calcium Channels in Physiological and Pathological States of the Nervous System. Front Cell Neurosci 2020; 14:600758. [PMID: 33328896 PMCID: PMC7732603 DOI: 10.3389/fncel.2020.600758] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/03/2020] [Indexed: 12/13/2022] Open
Abstract
Store-operated calcium channels (SOCs) are widely expressed in excitatory and non-excitatory cells where they mediate significant store-operated calcium entry (SOCE), an important pathway for calcium signaling throughout the body. While the activity of SOCs has been well studied in non-excitable cells, attention has turned to their role in neurons and glia in recent years. In particular, the role of SOCs in the nervous system has been extensively investigated, with links to their dysregulation found in a wide variety of neurological diseases from Alzheimer’s disease (AD) to pain. In this review, we provide an overview of their molecular components, expression, and physiological role in the nervous system and describe how the dysregulation of those roles could potentially lead to various neurological disorders. Although further studies are still needed to understand how SOCs are activated under physiological conditions and how they are linked to pathological states, growing evidence indicates that SOCs are important players in neurological disorders and could be potential new targets for therapies. While the role of SOCE in the nervous system continues to be multifaceted and controversial, the study of SOCs provides a potentially fruitful avenue into better understanding the nervous system and its pathologies.
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Affiliation(s)
- Isis Zhang
- Department of Anesthesiology, Rutgers New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
| | - Huijuan Hu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, NJ, United States
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Larramona-Arcas R, González-Arias C, Perea G, Gutiérrez A, Vitorica J, García-Barrera T, Gómez-Ariza JL, Pascua-Maestro R, Ganfornina MD, Kara E, Hudry E, Martinez-Vicente M, Vila M, Galea E, Masgrau R. Sex-dependent calcium hyperactivity due to lysosomal-related dysfunction in astrocytes from APOE4 versus APOE3 gene targeted replacement mice. Mol Neurodegener 2020; 15:35. [PMID: 32517777 PMCID: PMC7285605 DOI: 10.1186/s13024-020-00382-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 05/25/2020] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The apolipoprotein E (APOE) gene exists in three isoforms in humans: APOE2, APOE3 and APOE4. APOE4 causes structural and functional alterations in normal brains, and is the strongest genetic risk factor of the sporadic form of Alzheimer's disease (LOAD). Research on APOE4 has mainly focused on the neuronal damage caused by defective cholesterol transport and exacerbated amyloid-β and Tau pathology. The impact of APOE4 on non-neuronal cell functions has been overlooked. Astrocytes, the main producers of ApoE in the healthy brain, are building blocks of neural circuits, and Ca2+ signaling is the basis of their excitability. Because APOE4 modifies membrane-lipid composition, and lipids regulate Ca2+ channels, we determined whether APOE4 dysregulates Ca2+signaling in astrocytes. METHODS Ca2+ signals were recorded in astrocytes in hippocampal slices from APOE3 and APOE4 gene targeted replacement male and female mice using Ca2+ imaging. Mechanistic analyses were performed in immortalized astrocytes. Ca2+ fluxes were examined with pharmacological tools and Ca2+ probes. APOE3 and APOE4 expression was manipulated with GFP-APOE vectors and APOE siRNA. Lipidomics of lysosomal and whole-membranes were also performed. RESULTS We found potentiation of ATP-elicited Ca2+responses in APOE4 versus APOE3 astrocytes in male, but not female, mice. The immortalized astrocytes modeled the male response, and showed that Ca2+ hyperactivity associated with APOE4 is caused by dysregulation of Ca2+ handling in lysosomal-enriched acidic stores, and is reversed by the expression of APOE3, but not of APOE4, pointing to loss of function due to APOE4 malfunction. Moreover, immortalized APOE4 astrocytes are refractory to control of Ca2+ fluxes by extracellular lipids, and present distinct lipid composition in lysosomal and plasma membranes. CONCLUSIONS Immortalized APOE4 versus APOE3 astrocytes present: increased Ca2+ excitability due to lysosome dysregulation, altered membrane lipidomes and intracellular cholesterol distribution, and impaired modulation of Ca2+ responses upon changes in extracellular lipids. Ca2+ hyperactivity associated with APOE4 is found in astrocytes from male, but not female, targeted replacement mice. The study suggests that, independently of Aβ and Tau pathologies, altered astrocyte excitability might contribute to neural-circuit hyperactivity depending on APOE allele, sex and lipids, and supports lysosome-targeted therapies to rescue APOE4 phenotypes in LOAD.
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Affiliation(s)
- Raquel Larramona-Arcas
- Unitat de Bioquímica de Medicina, Departament de Bioquímica i Biologia Molecular, and, Institut de Neurociències (INc), Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Catalonia Spain
| | - Candela González-Arias
- Cajal Institute, Consejo Superior de Investigaciones Científicas (CSIC), 28002 Madrid, Spain
| | - Gertrudis Perea
- Cajal Institute, Consejo Superior de Investigaciones Científicas (CSIC), 28002 Madrid, Spain
| | - Antonia Gutiérrez
- Departamento de Biología Celular, Genética y Fisiología, Facultad de Ciencias, Instituto de Investigación Biomedica de Málaga (IBIMA), Universidad de Málaga, 29071 Málaga, Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
| | - Javier Vitorica
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Departamento de Bioquímica y Biología Molecular, Facultad de Farmacia, Universidad de Sevilla, Instituto de Biomedicina de Sevilla (IBiS)-Hospital Universitario Virgen del Rocío/CSIC/Universidad de Sevilla, 41012 Sevilla, Spain
| | - Tamara García-Barrera
- Departamento de Química, Facultad de Ciencias Experimentales, Campus de El Carmen, Centro de Investigación en Recursos Naturales, Salud y Medio Ambiente (RENSMA), Universidad de Huelva, 21007 Huelva, Spain
| | - José Luis Gómez-Ariza
- Departamento de Química, Facultad de Ciencias Experimentales, Campus de El Carmen, Centro de Investigación en Recursos Naturales, Salud y Medio Ambiente (RENSMA), Universidad de Huelva, 21007 Huelva, Spain
| | - Raquel Pascua-Maestro
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular, Universidad de Valladolid-CSIC, 43007 Valladolid, Spain
| | - María Dolores Ganfornina
- Departamento de Bioquímica y Biología Molecular y Fisiología, Instituto de Biología y Genética Molecular, Universidad de Valladolid-CSIC, 43007 Valladolid, Spain
| | - Eleanna Kara
- Alzheimer’s Disease Research Laboratory, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129 USA
- Present Address: Institute of Neuropathology, University Hospital of Zurich, 8091 Zurich, Switzerland
| | - Eloise Hudry
- Alzheimer’s Disease Research Laboratory, MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Harvard Medical School, Charlestown, MA 02129 USA
| | - Marta Martinez-Vicente
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Neurodegenerative Diseases Research Group, Vall d’Hebron Research Institute (VHIR), 08035 Barcelona, Spain
| | - Miquel Vila
- Unitat de Bioquímica de Medicina, Departament de Bioquímica i Biologia Molecular, and, Institut de Neurociències (INc), Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Catalonia Spain
- Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), 28031 Madrid, Spain
- Neurodegenerative Diseases Research Group, Vall d’Hebron Research Institute (VHIR), 08035 Barcelona, Spain
- ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Catalonia Spain
| | - Elena Galea
- Unitat de Bioquímica de Medicina, Departament de Bioquímica i Biologia Molecular, and, Institut de Neurociències (INc), Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Catalonia Spain
- ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Catalonia Spain
| | - Roser Masgrau
- Unitat de Bioquímica de Medicina, Departament de Bioquímica i Biologia Molecular, and, Institut de Neurociències (INc), Facultat de Medicina, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Vallès, Barcelona, Catalonia Spain
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12
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Dopamine-induced calcium signaling in olfactory bulb astrocytes. Sci Rep 2020; 10:631. [PMID: 31959788 PMCID: PMC6971274 DOI: 10.1038/s41598-020-57462-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 12/30/2019] [Indexed: 11/08/2022] Open
Abstract
It is well established that astrocytes respond to the major neurotransmitters glutamate and GABA with cytosolic calcium rises, whereas less is known about the effect of dopamine on astroglial cells. In the present study, we used confocal calcium imaging in mouse brain slices of the olfactory bulb, a brain region with a large population of dopaminergic neurons, to investigate calcium signaling evoked by dopamine in astrocytes. Our results show that application of dopamine leads to a dose-dependent cytosolic calcium rise in astrocytes (EC50 = 76 µM) which is independent of neuronal activity and mainly mediated by PLC/IP3-dependent internal calcium release. Antagonists of both D1- and D2-class dopamine receptors partly reduce the dopaminergic calcium response, indicating that both receptor classes contribute to dopamine-induced calcium transients in olfactory bulb astrocytes.
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13
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Okubo Y, Iino M, Hirose K. Store-operated Ca 2+ entry-dependent Ca 2+ refilling in the endoplasmic reticulum in astrocytes. Biochem Biophys Res Commun 2019; 522:1003-1008. [PMID: 31812243 DOI: 10.1016/j.bbrc.2019.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 12/01/2019] [Indexed: 12/11/2022]
Abstract
Astrocytes regulate various brain functions, for which Ca2+ release from the endoplasmic reticulum (ER) often play crucial roles. Because astrocytic ER Ca2+ release is robust and frequent, the ER Ca2+ refilling mechanism should be critical for ongoing Ca2+ signaling in astrocytes. In this study, we focused on the putative functional significance of store-operated Ca2+ entry (SOCE) in ER Ca2+ refilling. We expressed the ER luminal Ca2+ indicator G-CEPIA1er in astrocytes in acute cortical slices to directly monitor the decrease and recovery of ER Ca2+ concentration upon spontaneous or norepinephrine-induced Ca2+ release. Inhibition of SOCE significantly slowed the recovery of ER Ca2+ concentration after Ca2+ release in astrocytes. This delayed recovery resulted in a prolonged decrease in the ER Ca2+ content in astrocytes with periodic spontaneous Ca2+ release, followed by the attenuation of cytosolic Ca2+ responses upon Ca2+ release. Therefore, our results provide direct evidence for the physiological significance of SOCE in ER Ca2+ refilling after ER Ca2+ release.
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Affiliation(s)
- Yohei Okubo
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 133-0033, Japan.
| | - Masamitsu Iino
- Division of Cellular and Molecular Pharmacology, Nihon University School of Medicine, 30-1 Oyaguchi Kamicho, Itabashi-ku, Tokyo, 173-8610, Japan
| | - Kenzo Hirose
- Department of Pharmacology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 133-0033, Japan
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14
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Beiersdorfer A, Lohr C. AMPA Receptor-Mediated Ca 2+ Transients in Mouse Olfactory Ensheathing Cells. Front Cell Neurosci 2019; 13:451. [PMID: 31636544 PMCID: PMC6788192 DOI: 10.3389/fncel.2019.00451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 09/20/2019] [Indexed: 11/13/2022] Open
Abstract
Ca2+ signaling in glial cells is primarily triggered by metabotropic pathways and the subsequent Ca2+ release from internal Ca2+ stores. However, there is upcoming evidence that various ion channels might also initiate Ca2+ rises in glial cells by Ca2+ influx. We investigated AMPA receptor-mediated inward currents and Ca2+ transients in olfactory ensheathing cells (OECs), a specialized glial cell population in the olfactory bulb (OB), using whole-cell voltage-clamp recordings and confocal Ca2+ imaging. By immunohistochemistry we showed immunoreactivity to the AMPA receptor subunits GluA1, GluA2 and GluA4 in OECs, suggesting the presence of AMPA receptors in OECs. Kainate-induced inward currents were mediated exclusively by AMPA receptors, as they were sensitive to the specific AMPA receptor antagonist, GYKI53655. Moreover, kainate-induced inward currents were reduced by the selective Ca2+-permeable AMPA receptor inhibitor, NASPM, suggesting the presence of functional Ca2+-permeable AMPA receptors in OECs. Additionally, kainate application evoked Ca2+ transients in OECs which were abolished in the absence of extracellular Ca2+, indicating that Ca2+ influx via Ca2+-permeable AMPA receptors contribute to kainate-induced Ca2+ transients. However, kainate-induced Ca2+ transients were partly reduced upon Ca2+ store depletion, leading to the conclusion that Ca2+ influx via AMPA receptor channels is essential to trigger Ca2+ transients in OECs, whereas Ca2+ release from internal stores contributes in part to the kainate-evoked Ca2+ response. Endogenous glutamate release by OSN axons initiated Ca2+ transients in OECs, equally mediated by metabotropic receptors (glutamatergic and purinergic) and AMPA receptors, suggesting a prominent role for AMPA receptor mediated Ca2+ signaling in axon-OEC communication.
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Affiliation(s)
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
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15
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Rotermund N, Schulz K, Hirnet D, Lohr C. Purinergic Signaling in the Vertebrate Olfactory System. Front Cell Neurosci 2019; 13:112. [PMID: 31057369 PMCID: PMC6477478 DOI: 10.3389/fncel.2019.00112] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 03/07/2019] [Indexed: 12/15/2022] Open
Abstract
Adenosine 5'-triphosphate (ATP) is an ubiquitous co-transmitter in the vertebrate brain. ATP itself, as well as its breakdown products ADP and adenosine are involved in synaptic transmission and plasticity, neuron-glia communication and neural development. Although purinoceptors have been demonstrated in the vertebrate olfactory system by means of histological techniques for many years, detailed insights into physiological properties and functional significance of purinergic signaling in olfaction have been published only recently. We review the current literature on purinergic neuromodulation, neuron-glia interactions and neurogenesis in the vertebrate olfactory system.
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Affiliation(s)
- Natalie Rotermund
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Daniela Hirnet
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
| | - Christian Lohr
- Division of Neurophysiology, University of Hamburg, Hamburg, Germany
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16
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Mei Y, Barrett JE, Hu H. Calcium release-activated calcium channels and pain. Cell Calcium 2018; 74:180-185. [PMID: 30096536 DOI: 10.1016/j.ceca.2018.07.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/10/2018] [Accepted: 07/27/2018] [Indexed: 12/30/2022]
Abstract
Calcium release-activated calcium (CRAC) channels are unique among ion channels that are activated in response to depletion of intracellular calcium stores and are highly permeable to Ca2+ compared to other cations. CRAC channels mediate an important calcium signal for a wide variety of cell types and are well studied in the immune system. They have been implicated in a number of disorders such as immunodeficiency, musculosketal disorders and cancer. There is growing evidence showing that CRAC channels are expressed in the nervous system and are involved in pathological conditions including pain. This review summarizes the expression, distribution, and function of the CRAC channel family in the dorsal root ganglion, spinal cord and some brain regions, and discusses their functional significance in neurons and glial cells and involvement in nociception and chronic pain. Although further studies are needed to understand how these channels are activated under physiological conditions, the recent findings indicate that the CRAC channel Orai1 is an important player in pain modulation and could represent a new target for pathological pain.
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Affiliation(s)
- Yixiao Mei
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, United States
| | - James E Barrett
- Department of Neurology, Drexel University College of Medicine Philadelphia, PA 19102, United States
| | - Huijuan Hu
- Department of Anesthesiology, Rutgers New Jersey Medical School, Newark, NJ 07103, United States.
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17
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Helleringer R, Chever O, Daniel H, Galante M. Oxygen and Glucose Deprivation Induces Bergmann Glia Membrane Depolarization and Ca 2+ Rises Mainly Mediated by K + and ATP Increases in the Extracellular Space. Front Cell Neurosci 2017; 11:349. [PMID: 29163059 PMCID: PMC5675856 DOI: 10.3389/fncel.2017.00349] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 10/20/2017] [Indexed: 01/24/2023] Open
Abstract
During brain ischemia, intense energy deficiency induces a complex succession of events including pump failure, acidosis and exacerbated glutamate release. In the cerebellum, glutamate is the principal mediator of Purkinje neuron anoxic depolarization during episodes of oxygen and glucose deprivation (OGD). Here, the impact of OGD is studied in Bergmann glia, specialized astrocytes closely associated to Purkinje neurons. Patch clamp experiments reveal that during OGD Bergmann glial cells develop a large depolarizing current that is not mediated by glutamate and purinergic receptors but is mainly due to the accumulation of K+ in the extracellular space. Furthermore, we also found that increases in the intracellular Ca2+ concentration appear in Bergmann glia processes several minutes following OGD. These elevations require, in an early phase, Ca2+ mobilization from internal stores via P2Y receptor activation, and, over longer periods, Ca2+ entry through store-operated calcium channels. Our results suggest that increases of K+ and ATP concentrations in the extracellular space are primordial mediators of the OGD effects on Bergmann glia. In the cerebellum, glial responses to energy deprivation-triggering events are therefore highly likely to follow largely distinct rules from those of their neuronal counterparts.
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Affiliation(s)
- Romain Helleringer
- Pharmacology and Biochemistry of the Synapse, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Université Paris-Sud, CNRS, UMR 9197, Orsay, France
| | - Oana Chever
- Neuroglial Interactions in Cerebral Physiopathology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS, UMR 7241, INSERM U1050, Labex Memolife, PSL Research University Paris, Paris, France
| | - Hervé Daniel
- Pharmacology and Biochemistry of the Synapse, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Université Paris-Sud, CNRS, UMR 9197, Orsay, France
| | - Micaela Galante
- Pharmacology and Biochemistry of the Synapse, Institut des Neurosciences Paris-Saclay, Université Paris-Saclay, Université Paris-Sud, CNRS, UMR 9197, Orsay, France
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18
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Neurons and astrocytes in an infantile neuroaxonal dystrophy (INAD) mouse model show characteristic alterations in glutamate-induced Ca 2+ signaling. Neurochem Int 2017; 108:121-132. [DOI: 10.1016/j.neuint.2017.03.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Revised: 03/03/2017] [Accepted: 03/03/2017] [Indexed: 01/01/2023]
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19
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Papanikolaou M, Lewis A, Butt AM. Store-operated calcium entry is essential for glial calcium signalling in CNS white matter. Brain Struct Funct 2017; 222:2993-3005. [PMID: 28247021 PMCID: PMC5585307 DOI: 10.1007/s00429-017-1380-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/27/2017] [Indexed: 11/06/2022]
Abstract
‘Calcium signalling’ is the ubiquitous response of glial cells to multiple extracellular stimuli. The primary mechanism of glial calcium signalling is by release of calcium from intracellular stores of the endoplasmic reticulum (ER). Replenishment of ER Ca2+ stores relies on store-operated calcium entry (SOCE). However, despite the importance of calcium signalling in glial cells, little is known about their mechanisms of SOCE. Here, we investigated SOCE in glia of the mouse optic nerve, a typical CNS white matter tract that comprises bundles of myelinated axons and the oligodendrocytes and astrocytes that support them. Using quantitative RT-PCR, we identified Orai1 channels, both Stim1 and Stim2, and the transient receptor potential M3 channel (TRPM3) as the primary channels for SOCE in the optic nerve, and their expression in both astrocytes and oligodendrocytes was demonstrated by immunolabelling of optic nerve sections and cultures. The functional importance of SOCE was demonstrated by fluo-4 calcium imaging on isolated intact optic nerves and optic nerve cultures. Removal of extracellular calcium ([Ca2+]o) resulted in a marked depletion of glial cytosolic calcium ([Ca2+]i), which recovered rapidly on restoration of [Ca2+]o via SOCE. 2-aminoethoxydiphenylborane (2APB) significantly decreased SOCE and severely attenuated ATP-mediated calcium signalling. The results provide evidence that Orai/Stim and TRPM3 are important components of the ‘calcium toolkit’ that underpins SOCE and the sustainability of calcium signalling in white matter glia.
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Affiliation(s)
- M Papanikolaou
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - A Lewis
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK
| | - A M Butt
- Institute of Biomedical and Biomolecular Sciences, School of Pharmacy and Biomedical Science, University of Portsmouth, Portsmouth, PO1 2DT, UK.
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20
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Translationally Controlled Tumor Protein Stimulates Dopamine Release from PC12 Cells via Ca 2+-Independent Phospholipase A₂ Pathways. Int J Mol Sci 2016; 17:ijms17101774. [PMID: 27783042 PMCID: PMC5085798 DOI: 10.3390/ijms17101774] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 10/05/2016] [Accepted: 10/10/2016] [Indexed: 11/17/2022] Open
Abstract
The translationally controlled tumor protein (TCTP), initially identified as a tumor- and growth-related protein, is also known as a histamine-releasing factor (HRF). TCTP is widely distributed in the neuronal systems, but its function is largely uncharacterized. Here, we report a novel function of TCTP in the neurotransmitter release from a neurosecretory, pheochromocytoma (PC12) cells. Treatment with recombinant TCTP (rTCTP) enhanced both basal and depolarization (50 mM KCl)-evoked [³H]dopamine release in concentration- and time-dependent manners. Interestingly, even though rTCTP induced the increase in intracellular calcium levels ([Ca2+]i), the rTCTP-driven effect on dopamine release was mediated by a Ca2+-independent pathway, as evidenced by the fact that Ca2+-modulating agents such as Ca2+ chelators and a voltage-gated L-type Ca2+-channel blocker did not produce any changes in rTCTP-evoked dopamine release. In a study to investigate the involvement of phospholipase A₂ (PLA₂) in rTCTP-induced dopamine release, the inhibitor for Ca2+-independent PLA₂ (iPLA₂) produced a significant inhibitory effect on rTCTP-induced dopamine release, whereas this release was not significantly inhibited by Ca2+-dependent cytosolic PLA₂ (cPLA₂) and secretory PLA₂ (sPLA₂) inhibitors. We found that rTCTP-induced dopamine release from neuronal PC12 cells was modulated by a Ca2+-independent mechanism that involved PLA₂ in the process, suggesting the regulatory role of TCTP in the neuronal functions.
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21
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Mitochondria from a mouse model of the human infantile neuroaxonal dystrophy (INAD) with genetic defects in VIA iPLA 2 have disturbed Ca 2+ regulation with reduction in Ca 2+ capacity. Neurochem Int 2016; 99:187-193. [DOI: 10.1016/j.neuint.2016.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 06/30/2016] [Accepted: 07/05/2016] [Indexed: 11/21/2022]
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22
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Store-Operated Calcium Entry in Müller Glia Is Controlled by Synergistic Activation of TRPC and Orai Channels. J Neurosci 2016; 36:3184-98. [PMID: 26985029 DOI: 10.1523/jneurosci.4069-15.2016] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
UNLABELLED The endoplasmic reticulum (ER) is at the epicenter of astrocyte Ca(2+) signaling. We sought to identify the molecular mechanism underlying store-operated calcium entry that replenishes ER stores in mouse Müller cells. Store depletion, induced through blockade of sequestration transporters in Ca(2+)-free saline, induced synergistic activation of canonical transient receptor potential 1 (TRPC1) and Orai channels. Store-operated TRPC1 channels were identified by their electrophysiological properties, pharmacological blockers, and ablation of the Trpc1 gene. Ca(2+) release-activated currents (ICRAC) were identified by ion permeability, voltage dependence, and sensitivity to selective Orai antagonists Synta66 and GSK7975A. Depletion-evoked calcium influx was initiated at the Müller end-foot and apical process, triggering centrifugal propagation of Ca(2+) waves into the cell body. EM analysis of the end-foot compartment showed high-density ER cisternae that shadow retinal ganglion cell (RGC) somata and axons, protoplasmic astrocytes, vascular endothelial cells, and ER-mitochondrial contacts at the vitreal surface of the end-foot. The mouse retina expresses transcripts encoding both Stim and all known Orai genes; Müller glia predominantly express stromal interacting molecule 1 (STIM1), whereas STIM2 is mainly confined to the outer plexiform and RGC layers. Elimination of TRPC1 facilitated Müller gliosis induced by the elevation of intraocular pressure, suggesting that TRPC channels might play a neuroprotective role during mechanical stress. By characterizing the properties of store-operated signaling pathways in Müller cells, these studies expand the current knowledge about the functional roles these cells play in retinal physiology and pathology while also providing further evidence for the complexity of calcium signaling mechanisms in CNS astroglia. SIGNIFICANCE STATEMENT Store-operated Ca(2+) signaling represents a major signaling pathway and source of cytosolic Ca(2+) in astrocytes. Here, we show that the store-operated response in Müller cells, radial glia that perform key structural, signaling, osmoregulatory, and mechanosensory functions within the retina, is mediated through synergistic activation of transient receptor potential and Orai channels. The end-foot disproportionately expresses the depletion sensor stromal interacting molecule 1, which contains an extraordinarily high density of endoplasmic reticulum cisternae that shadow neuronal, astrocytic, vascular, and axonal structures; interface with mitochondria; but also originate store-operated Ca(2+) entry-induced transcellular Ca(2+) waves that propagate glial excitation into the proximal retina. These results identify a molecular mechanism that underlies complex interactions between the plasma membrane and calcium stores, and contributes to astroglial function, regulation, and response to mechanical stress.
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23
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Rudolph R, Jahn HM, Courjaret R, Messemer N, Kirchhoff F, Deitmer JW. The inhibitory input to mouse cerebellar Purkinje cells is reciprocally modulated by Bergmann glial P2Y1 and AMPA receptor signaling. Glia 2016; 64:1265-80. [PMID: 27144942 DOI: 10.1002/glia.22999] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Revised: 04/06/2016] [Accepted: 04/13/2016] [Indexed: 11/10/2022]
Abstract
Synaptic transmission has been shown to be modulated by glial functions, but the modes of specific glial action may vary in different neural circuits. We have tested the hypothesis, if Bergmann GLIA (BG) are involved in shaping neuronal communication in the mouse cerebellar cortex, using acutely isolated cerebellar slices of wild-type (WT) and of glia-specific receptor knockout mice. Activation of P2Y1 receptors by ADP (100 µM) or glutamatergic receptors by AMPA (0.3 µM) resulted in a robust, reversible and repeatable rise of evoked inhibitory input in Purkinje cells by 80% and 150%, respectively. The ADP-induced response was suppressed by prior application of AMPA, and the AMPA-induced response was suppressed by prior application of ADP. Genetic deletion or pharmacological blockade of either receptor restored the response to the other receptor agonist. Both ADP and AMPA responses were sensitive to Rose Bengal, which blocks vesicular glutamate uptake, and to the NMDA receptor antagonist D-AP5. Our results provide strong evidence that activation of both ADP and AMPA receptors, located on BGs, results in the release of glutamate, which in turn activates inhibitory interneurons via NMDA-type glutamate receptors. This infers that BG cells, by means of metabotropic signaling via their AMPA and P2Y1 receptors, which mutually suppress each other, would interdependently contribute to the fine-tuning of Purkinje cell activity in the cerebellar cortex. GLIA 2016. GLIA 2016;64:1265-1280.
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Affiliation(s)
- Ramona Rudolph
- General Zoology, FB Biology, University of Kaiserslautern, P.B. 3049, D-67653, Kaiserslautern, Germany
| | - Hannah M Jahn
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, D-66421 Homburg/Saar, Germany
| | - Raphael Courjaret
- General Zoology, FB Biology, University of Kaiserslautern, P.B. 3049, D-67653, Kaiserslautern, Germany.,Weill Cornell Medical College, Doha, Qatar
| | - Nanette Messemer
- General Zoology, FB Biology, University of Kaiserslautern, P.B. 3049, D-67653, Kaiserslautern, Germany
| | - Frank Kirchhoff
- Molecular Physiology, Center for Integrative Physiology and Molecular Medicine, University of Saarland, D-66421 Homburg/Saar, Germany
| | - Joachim W Deitmer
- General Zoology, FB Biology, University of Kaiserslautern, P.B. 3049, D-67653, Kaiserslautern, Germany
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24
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Toth AB, Shum AK, Prakriya M. Regulation of neurogenesis by calcium signaling. Cell Calcium 2016; 59:124-34. [PMID: 27020657 DOI: 10.1016/j.ceca.2016.02.011] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 02/17/2016] [Accepted: 02/18/2016] [Indexed: 12/22/2022]
Abstract
Calcium (Ca(2+)) signaling has essential roles in the development of the nervous system from neural induction to the proliferation, migration, and differentiation of neural cells. Ca(2+) signaling pathways are shaped by interactions among metabotropic signaling cascades, intracellular Ca(2+) stores, ion channels, and a multitude of downstream effector proteins that activate specific genetic programs. The temporal and spatial dynamics of Ca(2+) signals are widely presumed to control the highly diverse yet specific genetic programs that establish the complex structures of the adult nervous system. Progress in the last two decades has led to significant advances in our understanding of the functional architecture of Ca(2+) signaling networks involved in neurogenesis. In this review, we assess the literature on the molecular and functional organization of Ca(2+) signaling networks in the developing nervous system and its impact on neural induction, gene expression, proliferation, migration, and differentiation. Particular emphasis is placed on the growing evidence for the involvement of store-operated Ca(2+) release-activated Ca(2+) (CRAC) channels in these processes.
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Affiliation(s)
- Anna B Toth
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, United States
| | - Andrew K Shum
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, United States
| | - Murali Prakriya
- Department of Pharmacology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, United States.
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25
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Zhou Q, Yen A, Rymarczyk G, Asai H, Trengrove C, Aziz N, Kirber MT, Mostoslavsky G, Ikezu T, Wolozin B, Bolotina VM. Impairment of PARK14-dependent Ca(2+) signalling is a novel determinant of Parkinson's disease. Nat Commun 2016; 7:10332. [PMID: 26755131 PMCID: PMC4729940 DOI: 10.1038/ncomms10332] [Citation(s) in RCA: 60] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 12/01/2015] [Indexed: 12/12/2022] Open
Abstract
The etiology of idiopathic Parkinson's disease (idPD) remains enigmatic despite recent successes in identification of genes (PARKs) that underlie familial PD. To find new keys to this incurable neurodegenerative disorder we focused on the poorly understood PARK14 disease locus (Pla2g6 gene) and the store-operated Ca(2+) signalling pathway. Analysis of the cells from idPD patients reveals a significant deficiency in store-operated PLA2g6-dependent Ca(2+) signalling, which we can mimic in a novel B6.Cg-Pla2g6(ΔEx2-VB) (PLA2g6 ex2(KO)) mouse model. Here we demonstrate that genetic or molecular impairment of PLA2g6-dependent Ca(2+) signalling is a trigger for autophagic dysfunction, progressive loss of dopaminergic (DA) neurons in substantia nigra pars compacta and age-dependent L-DOPA-sensitive motor dysfunction. Discovery of this previously unknown sequence of pathological events, its association with idPD and our ability to mimic this pathology in a novel genetic mouse model opens new opportunities for finding a cure for this devastating neurodegenerative disease.
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Affiliation(s)
- Qingde Zhou
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Allen Yen
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Grzegorz Rymarczyk
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Hirohide Asai
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Chelsea Trengrove
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Nadine Aziz
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Michael T. Kirber
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Gustavo Mostoslavsky
- Center for Regenerative Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Tsuneya Ikezu
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Benjamin Wolozin
- Department of Pharmacology and Experimental Therapeutics, Boston University School of Medicine, Boston, Massachusetts 02118, USA
| | - Victoria M. Bolotina
- Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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Smani T, Domínguez-Rodriguez A, Callejo-García P, Rosado JA, Avila-Medina J. Phospholipase A2 as a Molecular Determinant of Store-Operated Calcium Entry. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 898:111-31. [PMID: 27161227 DOI: 10.1007/978-3-319-26974-0_6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Activation of phospholipases A2 (PLA2) leads to the generation of biologically active lipid products that can affect numerous cellular events. Ca(2+)-independent PLA2 (iPLA2), also called group VI phospholipase A2, is one of the main types forming the superfamily of PLA2. Beside of its role in phospholipid remodeling, iPLA2 has been involved in intracellular Ca(2+) homeostasis regulation. Several studies proposed iPLA2 as an essential molecular player of store operated Ca(2+) entry (SOCE) in a large number of excitable and non-excitable cells. iPLA2 activation releases lysophosphatidyl products, which were suggested as agonists of store operated calcium channels (SOCC) and other TRP channels. Herein, we will review the important role of iPLA2 on the intracellular Ca(2+) handling focusing on its role in SOCE regulation and its implication in physiological and/or pathological processes.
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Affiliation(s)
- Tarik Smani
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain.
| | - Alejandro Domínguez-Rodriguez
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain
| | - Paula Callejo-García
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain
| | - Juan A Rosado
- Departamento de Fisiología, University of Extremadura, Cáceres, Spain
| | - Javier Avila-Medina
- Department of Medical Physiology and Biophysic, Institute of Biomedicine of Seville (IBiS), University Hospital of Virgen del Rocío/CSIC/University of Seville, Sevilla, 41013, Spain
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Bluhm B, Laffer B, Hirnet D, Rothermundt M, Ambree O, Lohr C. Normal cerebellar development in S100B-deficient mice. THE CEREBELLUM 2015; 14:119-27. [PMID: 25342137 DOI: 10.1007/s12311-014-0606-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The calcium-binding protein S100B has been shown to support neuron proliferation, migration and neurite growth in vitro, while the significance of S100B for neuronal development in vivo is controversial. We have investigated the effect of S100B deficiency on cerebellar development in S100B knockout mice at an age of 5 and 10 days after birth (P5 and P10). This time range covers important developmental steps in the cerebellum such as granule cell proliferation and migration, as well as dendritic growth of Purkinje cells. Bergmann glial cells contain a particularly high concentration of S100B and serve as scaffold for both migrating granule cells and growing Purkinje cell dendrites. This renders the postnatal cerebellum ideal as a model system to study the importance of S100B for glial and neuronal development. We measured the length of Bergmann glial processes, the width of the external granule cell layer as a measure of granule cell proliferation, the decrease in width of the external granule cell layer between P5 and P10 as a measure of granule cell migration, and the length of Purkinje cell dendrites in wild-type and S100B knockout mice. None of these parameters showed significant differences between wild-type and knockout mice. In addition, wild-type and knockout mice performed equally in locomotor behaviour tests. The results indicate that S100B-deficient mice have normal development of the cerebellum and no severe impairment of motor function.
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Affiliation(s)
- Björn Bluhm
- Division of Neurophysiology, Biocenter Grindel, Martin-Luther-King-Pl. 3, D-20146, Hamburg, Germany
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Stavermann M, Meuth P, Doengi M, Thyssen A, Deitmer JW, Lohr C. Calcium-induced calcium release and gap junctions mediate large-scale calcium waves in olfactory ensheathing cells in situ. Cell Calcium 2015; 58:215-25. [DOI: 10.1016/j.ceca.2015.05.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 05/04/2015] [Accepted: 05/26/2015] [Indexed: 02/06/2023]
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Abstract
Astrocytes exhibit cellular excitability through variations in their intracellular calcium (Ca²⁺) levels in response to synaptic activity. Astrocyte Ca²⁺ elevations can trigger the release of neuroactive substances that can modulate synaptic transmission and plasticity, hence promoting bidirectional communication with neurons. Intracellular Ca²⁺ dynamics can be regulated by several proteins located in the plasma membrane, within the cytosol and by intracellular organelles such as mitochondria. Spatial dynamics and strategic positioning of mitochondria are important for matching local energy provision and Ca²⁺ buffering requirements to the demands of neuronal signalling. Although relatively unresolved in astrocytes, further understanding the role of mitochondria in astrocytes may reveal more about the complex bidirectional relationship between astrocytes and neurons in health and disease. In the present review, we discuss some recent insights regarding mitochondrial function, transport and turnover in astrocytes and highlight some important questions that remain to be answered.
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Effects of 39 Compounds on Calmodulin-Regulated Adenylyl Cyclases AC1 and Bacillus anthracis Edema Factor. PLoS One 2015; 10:e0124017. [PMID: 25946093 PMCID: PMC4422518 DOI: 10.1371/journal.pone.0124017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 03/09/2015] [Indexed: 12/29/2022] Open
Abstract
Adenylyl cyclases (ACs) catalyze the conversion of ATP into the second messenger cAMP. Membranous AC1 (AC1) is involved in processes of memory and learning and in muscle pain. The AC toxin edema factor (EF) of Bacillus anthracis is involved in the development of anthrax. Both ACs are stimulated by the eukaryotic Ca2+-sensor calmodulin (CaM). The CaM-AC interaction could constitute a potential target to enhance or impair the AC activity of AC1 and EF to intervene in above (patho)physiological mechanisms. Thus, we analyzed the impact of 39 compounds including typical CaM-inhibitors, an anticonvulsant, an anticholinergic, antidepressants, antipsychotics and Ca2+-antagonists on CaM-stimulated catalytic activity of AC1 and EF. Compounds were tested at 10 μM, i.e., a concentration that can be reached therapeutically for certain antidepressants and antipsychotics. Calmidazolium chloride decreased CaM-stimulated AC1 activity moderately by about 30%. In contrast, CaM-stimulated EF activity was abrogated by calmidazolium chloride and additionally decreased by chlorpromazine, felodipine, penfluridol and trifluoperazine by about 20–40%. The activity of both ACs was decreased by calmidazolium chloride in the presence and absence of CaM. Thus, CaM-stimulated AC1 activity is more insensitive to inhibition by small molecules than CaM-stimulated EF activity. Inhibition of AC1 and EF by calmidazolium chloride is largely mediated via a CaM-independent allosteric mechanism.
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Hossain MI, Roulston CL, Stapleton DI. Molecular basis of impaired glycogen metabolism during ischemic stroke and hypoxia. PLoS One 2014; 9:e97570. [PMID: 24858129 PMCID: PMC4032261 DOI: 10.1371/journal.pone.0097570] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Accepted: 04/21/2014] [Indexed: 02/02/2023] Open
Abstract
Background Ischemic stroke is the combinatorial effect of many pathological processes including the loss of energy supplies, excessive intracellular calcium accumulation, oxidative stress, and inflammatory responses. The brain's ability to maintain energy demand through this process involves metabolism of glycogen, which is critical for release of stored glucose. However, regulation of glycogen metabolism in ischemic stroke remains unknown. In the present study, we investigate the role and regulation of glycogen metabolizing enzymes and their effects on the fate of glycogen during ischemic stroke. Results Ischemic stroke was induced in rats by peri-vascular application of the vasoconstrictor endothelin-1 and forebrains were collected at 1, 3, 6 and 24 hours post-stroke. Glycogen levels and the expression and activity of enzymes involved in glycogen metabolism were analyzed. We found elevated glycogen levels in the ipsilateral hemispheres compared with contralateral hemispheres at 6 and 24 hours (25% and 39% increase respectively; P<0.05). Glycogen synthase activity and glycogen branching enzyme expression were found to be similar between the ipsilateral, contralateral, and sham control hemispheres. In contrast, the rate-limiting enzyme for glycogen breakdown, glycogen phosphorylase, had 58% lower activity (P<0.01) in the ipsilateral hemisphere (24 hours post-stroke), which corresponded with a 48% reduction in cAMP-dependent protein kinase A (PKA) activity (P<0.01). In addition, glycogen debranching enzyme expression 24 hours post-stroke was 77% (P<0.01) and 72% lower (P<0.01) at the protein and mRNA level, respectively. In cultured rat primary cerebellar astrocytes, hypoxia and inhibition of PKA activity significantly reduced glycogen phosphorylase activity and increased glycogen accumulation but did not alter glycogen synthase activity. Furthermore, elevated glycogen levels provided metabolic support to astrocytes during hypoxia. Conclusion Our study has identified that glycogen breakdown is impaired during ischemic stroke, the molecular basis of which includes reduced glycogen debranching enzyme expression level together with reduced glycogen phosphorylase and PKA activity.
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Affiliation(s)
- Mohammed Iqbal Hossain
- Department of Physiology, St. Vincent's Campus, The University of Melbourne, Melbourne, Victoria, Australia
- * E-mail:
| | - Carli Lorraine Roulston
- Department of Medicine, St. Vincent's Campus, The University of Melbourne, Melbourne, Victoria, Australia
| | - David Ian Stapleton
- Department of Physiology, St. Vincent's Campus, The University of Melbourne, Melbourne, Victoria, Australia
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Purinergic neuron-glia interactions in sensory systems. Pflugers Arch 2014; 466:1859-72. [DOI: 10.1007/s00424-014-1510-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2014] [Revised: 03/26/2014] [Accepted: 03/26/2014] [Indexed: 02/06/2023]
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Reyes RC, Verkhratsky A, Parpura V. TRPC1-mediated Ca2+ and Na+ signalling in astroglia: differential filtering of extracellular cations. Cell Calcium 2013; 54:120-5. [PMID: 23764169 DOI: 10.1016/j.ceca.2013.05.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2013] [Revised: 05/13/2013] [Accepted: 05/14/2013] [Indexed: 10/26/2022]
Abstract
Canonical transient receptor potential 1 (TRPC1) plasmalemmal cation channels mediate Ca2+ and Na+ fluxes and control respective cytoplasmic ion signals in rat cortical astrocytes. Mechanical stimulation of astrocytes results in an increase in the levels of cytosolic Ca2+ and Na+ that are in part due to entry of extracellular cations through TRPC1 containing channels. Inhibition of the TRPC1 pore with an antibody against its selective filter reduced cytosolic Ca2+ accumulation caused by mechanical stimulation. In contrast, this immunological treatment increased the cytosolic Na+ peak accumulation induced by mechanical stimulation. We propose that TRPC channels are amenable to changes in selective filtering, as mutations in previous studies and antibody binding in our present study differentially affect the flux of Ca2) and Na+. TRPC1 containing channels might represent focal points for co-ordination of Ca2+ and Na+ signalling in astroglia and this can have consequences on Ca(2+)- and Na(+)-dependent processes such as regulated exocytosis and lactate production, respectively, which in turn can modulate neuronal synaptic transmission.
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Affiliation(s)
- Reno C Reyes
- Department of Neurobiology, Center for Glial Biology in Medicine, Atomic Force Microscopy & Nanotechnology Laboratories, Civitan International Research Center, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL 35294, USA
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Verkhratsky A, Parpura V. Store-operated calcium entry in neuroglia. Neurosci Bull 2013; 30:125-33. [PMID: 23677809 DOI: 10.1007/s12264-013-1343-x] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Accepted: 02/14/2013] [Indexed: 11/30/2022] Open
Abstract
Neuroglial cells are homeostatic neural cells. Generally, they are electrically non-excitable and their activation is associated with the generation of complex intracellular Ca(2+) signals that define the "Ca(2+) excitability" of glia. In mammalian glial cells the major source of Ca(2+) for this excitability is the lumen of the endoplasmic reticulum (ER), which is ultimately (re)filled from the extracellular space. This occurs via store-operated Ca(2+) entry (SOCE) which is supported by a specific signaling system connecting the ER with plasmalemmal Ca(2+) entry. Here, emptying of the ER Ca(2+) store is necessary and sufficient for the activation of SOCE, and without Ca(2+) influx via SOCE the ER store cannot be refilled. The molecular arrangements underlying SOCE are relatively complex and include plasmalemmal channels, ER Ca(2+) sensors, such as stromal interaction molecule, and possibly ER Ca(2+) pumps (of the SERCA type). There are at least two sets of plasmalemmal channels mediating SOCE, the Ca(2+)-release activated channels, Orai, and transient receptor potential (TRP) channels. The molecular identity of neuroglial SOCE has not been yet identified unequivocally. However, it seems that Orai is predominantly expressed in microglia, whereas astrocytes and oligodendrocytes rely more on TRP channels to produce SOCE. In physiological conditions the SOCE pathway is instrumental for the sustained phase of the Ca(2+) signal observed following stimulation of metabotropic receptors on glial cells.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, UK,
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Thyssen A, Stavermann M, Buddrus K, Doengi M, Ekberg JA, St John JA, Deitmer JW, Lohr C. Spatial and developmental heterogeneity of calcium signaling in olfactory ensheathing cells. Glia 2012; 61:327-37. [PMID: 23109369 DOI: 10.1002/glia.22434] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Accepted: 09/11/2012] [Indexed: 12/24/2022]
Abstract
Olfactory ensheathing cells (OECs) are specialized glial cells in the mammalian olfactory system supporting growth of axons from the olfactory epithelium into the olfactory bulb. OECs in the olfactory bulb can be subdivided into OECs of the outer nerve layer and the inner nerve layer according to the expression of marker proteins and their location in the nerve layer. In the present study, we have used confocal calcium imaging of OECs in acute mouse brain slices and olfactory bulbs in toto to investigate physiological differences between OEC subpopulations. OECs in the outer nerve layer, but not the inner nerve layer, responded to glutamate, ATP, serotonin, dopamine, carbachol, and phenylephrine with increases in the cytosolic calcium concentration. The calcium responses consisted of a transient and a tonic component, the latter being mediated by store-operated calcium entry. Calcium measurements in OECs during the first three postnatal weeks revealed a downregulation of mGluR(1) and P2Y(1) receptor-mediated calcium signaling within the first 2 weeks, suggesting that the expression of these receptors is developmentally controlled. In addition, electrical stimulation of sensory axons evoked calcium signaling via mGluR(1) and P2Y(1) only in outer nerve layer OECs. Downregulation of the receptor-mediated calcium responses in postnatal animals is reflected by a decrease in amplitude of stimulation-evoked calcium transients in OECs from postnatal days 3 to 21. In summary, the results presented reveal striking differences in receptor responses during development and in axon-OEC communication between the two subpopulations of OECs in the olfactory bulb.
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Affiliation(s)
- Anne Thyssen
- Abteilung für Allgemeine Zoologie, TU Kaiserslautern, Germany
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36
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Glynn P. Neuronal phospholipid deacylation is essential for axonal and synaptic integrity. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:633-41. [PMID: 22903185 DOI: 10.1016/j.bbalip.2012.07.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 07/20/2012] [Accepted: 07/31/2012] [Indexed: 12/24/2022]
Abstract
Recessively-inherited deficiency in the catalytic activity of calcium-independent phospholipase A2-beta (iPLA2β) and neuropathy target esterase (NTE) causes infantile neuroaxonal dystrophy and hereditary spastic paraplegia, respectively. Thus, these two related phospholipases have non-redundant functions that are essential for structural integrity of synapses and axons. Both enzymes are expressed in essentially all neurons and also have independent roles in glia. iPLA2β liberates sn-2 fatty acid and lysophospholipids from diacyl-phospholipids. Ca(2+)-calmodulin tonically-inhibits iPLA2β, but this can be alleviated by oleoyl-CoA. Together with fatty acyl-CoA-mediated conversion of lysophospholipid to diacyl-phospholipid this may regulate sn-2 fatty acyl composition of phospholipids. In the nervous system, iPLA2β is especially important for the turnover of polyunsaturated fatty acid-associated phospholipid at synapses. More information is required on the interplay between iPLA2β and iPLA2-gamma in deacylation of neuronal mitochondrial phospholipids. NTE reduces levels of phosphatidylcholine (PtdCho) by degrading it to glycerophosphocholine and two free fatty acids. The substrate for NTE may be nascent PtdCho complexed with a phospholipid-binding protein. Protein kinase A-mediated phosphorylation enhances PtdCho synthesis and may allow PtdCho accumulation by coordinate inhibition of NTE activity. NTE operates primarily at the endoplasmic reticulum in neuronal soma but is also present in axons. NTE-mediated PtdCho homeostasis facilitates membrane trafficking and this appears most critical for the integrity of axon terminals in the spinal cord and hippocampus. For maintenance of peripheral nerve axons, iPLA2β activity may be able to compensate for NTE-deficiency but not vice-versa. Whether agonists acting at neuronal receptors modulate the activity of either enzyme remains to be determined. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Paul Glynn
- Department of Cell Physiology & Pharmacology, Henry Wellcome Building, University of Leicester, Lancaster Road, Leicester LE1 9HN, UK.
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37
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Stavermann M, Buddrus K, St John JA, Ekberg JA, Nilius B, Deitmer JW, Lohr C. Temperature-dependent calcium-induced calcium release via InsP3 receptors in mouse olfactory ensheathing glial cells. Cell Calcium 2012; 52:113-23. [DOI: 10.1016/j.ceca.2012.04.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 03/22/2012] [Accepted: 04/24/2012] [Indexed: 02/07/2023]
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Riera J, Hatanaka R, Ozaki T, Kawashima R. Modeling the spontaneous Ca2+ oscillations in astrocytes: Inconsistencies and usefulness. J Integr Neurosci 2012; 10:439-73. [PMID: 22262535 DOI: 10.1142/s0219635211002877] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 11/09/2011] [Indexed: 12/07/2022] Open
Abstract
Spontaneous calcium (Ca2+) oscillations (SCOs) in astrocytes might be a crucial signaling for the multipurpose role of this type of cell in several brain functions. To interpret experimental data of astrocytic SCOs, which has been largely observed in the last decade, several groups have attempted to accommodate biophysical models that were developed in the past for Ca2+ signaling in other cell types. In most of the cases, only predictive strategies were used to estimate specific parameters of these modified models from actual experiments. In this study, we discuss the most remarkable models used to describe Ca2+ signaling in astrocytes. At the same time, we aim to revise the particulars of applying these models to interpret epifluorescent time series obtained from large regions of interest. Specially, we developed a detailed model for global Ca2+ signaling in the somata of astrocytes. In order to estimate some of the parameters in our model, we propose a deductive reasoning strategy, i.e., a statistical inference method that results from combining a filtering technique and a maximum likelihood principle. By means of computer simulations, we evaluate the accuracy of this estimation's strategy. Finally, we use the new model, in combination with a recent experimental findings by our group, to estimate the degree of cluster coupling inside the soma during the genesis of global Ca2+ events.
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Affiliation(s)
- J Riera
- Department of Functional Brain Imaging, Institute for Development, Aging and Cancer, Tohoku University, 4-1 Seiryocho, Aobaku, Sendai 980-8575, Japan.
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Gwozdz T, Dutko-Gwozdz J, Schafer C, Bolotina VM. Overexpression of Orai1 and STIM1 proteins alters regulation of store-operated Ca2+ entry by endogenous mediators. J Biol Chem 2012; 287:22865-72. [PMID: 22549787 DOI: 10.1074/jbc.m112.356626] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Orai1 and STIM1 have been identified as the main determinants of the store-operated Ca(2+) entry (SOCE). Their specific roles in SOCE and their molecular interactions have been studied extensively following heterologous overexpression or molecular knockdown and extrapolated to the endogenous processes in naïve cells. Using molecular and imaging techniques, we found that variation of expression levels of Orai1 or STIM1 can significantly alter expression and role of some endogenous regulators of SOCE. Although functional inhibition of Ca(2+)-independent phospholipase A(2) β (iPLA(2)β or PLA2g6A), or depletion of plasma membrane cholesterol caused a dramatic loss of endogenous SOCE in HEK293 cells, these effects were attenuated significantly when either Orai1 or STIM1 were overexpressed. Molecular knockdown of iPLA(2)β impaired SOCE in both control cells and cells overexpressing STIM1. We also discovered important cross-talk between expression of Orai1 and a specific plasma membrane variant of iPLA(2)β but not STIM1. These data confirm the role of iPLA(2)β as an essential mediator of endogenous SOCE and demonstrate that its physiological role can be obscured by Orai1 and STIM1 overexpression.
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Affiliation(s)
- Tomasz Gwozdz
- Ion Channel and Calcium Signaling Unit, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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40
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Lysophosphatidylinositol signalling: New wine from an old bottle. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1821:694-705. [DOI: 10.1016/j.bbalip.2012.01.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 12/02/2011] [Accepted: 01/03/2012] [Indexed: 01/29/2023]
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41
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Strokin M, Seburn KL, Cox GA, Martens KA, Reiser G. Severe disturbance in the Ca2+ signaling in astrocytes from mouse models of human infantile neuroaxonal dystrophy with mutated Pla2g6. Hum Mol Genet 2012; 21:2807-14. [PMID: 22442204 DOI: 10.1093/hmg/dds108] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Infantile neuroaxonal dystrophy (INAD; OMIM #no. 256600) is an inherited degenerative nervous system disorder characterized by nerve abnormalities in brain, spinal cord and peripheral nerves. About 85% of INAD patients carry mutations in the PLA2G6 gene that encodes for a Ca(2+)-independent phospholipase A(2) (VIA iPLA(2)), but how these mutations lead to disease is unknown. Besides regulating phospholipid homeostasis, VIA iPLA(2) is emerging with additional non-canonical functions, such as modulating store-regulated Ca(2+) entry into cells, and mitochondrial functions. In turn, defective Ca(2+) regulation could contribute to the development of INAD. Here, we studied possible changes in ATP-induced Ca(2+) signaling in astrocytes derived from two mutant strains of mice. The first strain carries a hypomorphic allele of the Pla2g6 that reduces transcript levels to 5-10% of that observed in wild-type mice. The second strain carries a point mutation in Pla2g6 that results in inactive VIA iPLA(2) protein with postulated gain in toxicity. Homozygous mice from both strains develop pathology analogous to that observed in INAD patients. The nucleotide ATP is the most important transmitter inducing Ca(2+) signals in astroglial networks. We demonstrate here a severe disturbance in Ca(2+) responses to ATP in astrocytes derived from both mutant mouse strains. The duration of the Ca(2+) responses in mutant astrocytes was significantly reduced when compared with values observed in control cells. We also show that the reduced Ca(2+) responses are probably due to a reduction in capacitative Ca(2+) entry (2.3-fold). Results suggest that altered Ca(2+) signaling could be a central mechanism in the development of INAD pathology.
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Affiliation(s)
- Mikhail Strokin
- Institut für Neurobiochemie, Medizinische Fakultät, Otto-von-Guericke-Universität Magdeburg, Magdeburg, Germany
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Rojo ML, Rodriguez-Gaztelumendi A, Fowler CJ. Lysophosphatidylinositol stimulates [³⁵S]GTPγS binding in the rat prefrontal cortex and hippocampus. Neurochem Res 2012; 37:1037-42. [PMID: 22270908 DOI: 10.1007/s11064-012-0704-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 01/06/2012] [Indexed: 12/19/2022]
Abstract
Lysophosphatidylinositol (LPI) is a biologically active lipid that produces a number of responses in cultured cells, and has been suggested to have neuroprotective properties in vivo. Some of the actions of LPI are mediated by G-protein coupled receptors, but it is not known whether G-protein coupled receptor-mediated responses can be seen in intact brain tissue. In consequence, in the present study, we investigated autoradiographically whether LPI increased the [(35)S]GTPγS binding level in brain tissue slices. In standard assay conditions, where as a positive control a robust response to cannabinoid receptor activation by the agonist ligand CP55,940 was seen, there was no increase in the autoradiographic density over basal produced by LPI. However, when the conditions were modified (incubation at 4°C rather than at 25°C, incubation time increased to 3 h, GDP concentration reduced from 2 to 0.1 mM), a significant increase in [(35)S]GTPγS autoradiographic density in response to 10 μM LPI was seen in the prefrontal cortex, hippocampus, and cortex at the level of the hippocampus, although the degree of increase was small and very variable. No significant increases were seen in the hypothalamus or cerebellum. It is concluded that LPI, in the right conditions, can activate a sufficient number of G-proteins in the rat prefrontal cortex and hippocampus to produce a response in the [(35)S]GTPγS autoradiographic assay of G-protein coupled receptor function.
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Affiliation(s)
- Maria Luisa Rojo
- Department of Pharmacology and Clinical Neuroscience, Umeå University, 901 87 Umeå, Sweden
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Quantifying the uncertainty of spontaneous Ca2+ oscillations in astrocytes: particulars of Alzheimer's disease. Biophys J 2011; 101:554-64. [PMID: 21806923 DOI: 10.1016/j.bpj.2011.06.041] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Revised: 05/12/2011] [Accepted: 06/21/2011] [Indexed: 11/27/2022] Open
Abstract
The quantification of spontaneous calcium (Ca(2+)) oscillations (SCOs) in astrocytes presents a challenge because of the large irregularities in the amplitudes, durations, and initiation times of the underlying events. In this article, we use a stochastic context to account for such SCO variability, which is based on previous models for cellular Ca(2+) signaling. First, we found that passive Ca(2+) influx from the extracellular space determine the basal concentration of this ion in the cytosol. Second, we demonstrated the feasibility of estimating both the inositol 1,4,5-trisphosphate (IP(3)) production levels and the average number of IP(3) receptor channels in the somatic clusters from epifluorescent Ca(2+) imaging through the combination of a filtering strategy and a maximum-likelihood criterion. We estimated these two biophysical parameters using data from wild-type adult mice and age-matched transgenic mice overexpressing the 695-amino-acid isoform of human Alzheimer β-amyloid precursor protein. We found that, together with an increase in the passive Ca(2+) influx, a significant reduction in the sensitivity of G protein-coupled receptors might lie beneath the abnormalities in the astrocytic Ca(2+) signaling, as was observed in rodent models of Alzheimer's disease. This study provides new, to our knowledge, indices for a quantitative analysis of SCOs in normal and pathological astrocytes.
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Yang B, Gwozdz T, Dutko-Gwozdz J, Bolotina VM. Orai1 and Ca2+-independent phospholipase A2 are required for store-operated Icat-SOC current, Ca2+ entry, and proliferation of primary vascular smooth muscle cells. Am J Physiol Cell Physiol 2011; 302:C748-56. [PMID: 22094335 DOI: 10.1152/ajpcell.00312.2011] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Store-operated Ca(2+) entry (SOCE) is important for multiple functions of vascular smooth muscle cells (SMC), which, depending of their phenotype, can resemble excitable and nonexcitable cells. Similar to nonexcitable cells, Orai1 was found to mediate Ca(2+)-selective (CRAC-like) current and SOCE in dedifferentiated cultured SMC and smooth muscle-derived cell lines. However, the role of Orai1 in cation-selective store-operated channels (cat-SOC), which are responsible for SOCE in primary SMC, remains unclear. Here we focus on primary SMC, and assess the role of Orai1 and Ca(2+)-independent phospholipase A(2) (iPLA(2)β, or PLA2G6) in activation of cat-SOC current (I(cat-SOC)), SOCE, and SMC proliferation. Using molecular, electrophysiological, imaging, and functional approaches, we demonstrate that molecular knockdown of either Orai1 or iPLA(2)β leads to similar inhibition of the whole cell cat-SOC current and SOCE in primary aortic SMC and results in significant reduction in DNA synthesis and impairment of SMC proliferation. This is the first demonstration that Orai1 and iPLA(2)β are equally important for cat-SOC, SOCE, and proliferation of primary aortic SMC.
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Affiliation(s)
- Bo Yang
- Ion Channel and Calcium Signaling Unit, Boston Univ. School of Medicine, Boston, MA 02118-2393, USA
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Dennis EA, Cao J, Hsu YH, Magrioti V, Kokotos G. Phospholipase A2 enzymes: physical structure, biological function, disease implication, chemical inhibition, and therapeutic intervention. Chem Rev 2011; 111:6130-85. [PMID: 21910409 PMCID: PMC3196595 DOI: 10.1021/cr200085w] [Citation(s) in RCA: 804] [Impact Index Per Article: 61.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Edward A. Dennis
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Jian Cao
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Yuan-Hao Hsu
- Department of Chemistry and Biochemistry and Pharmacology, School of Medicine, University of California, San Diego, La Jolla, California 92093-0601
| | - Victoria Magrioti
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771, Greece
| | - George Kokotos
- Laboratory of Organic Chemistry, Department of Chemistry, University of Athens, Panepistimiopolis, Athens 15771, Greece
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Galán C, Dionisio N, Smani T, Salido GM, Rosado JA. The cytoskeleton plays a modulatory role in the association between STIM1 and the Ca2+ channel subunits Orai1 and TRPC1. Biochem Pharmacol 2011; 82:400-10. [PMID: 21640715 DOI: 10.1016/j.bcp.2011.05.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 05/15/2011] [Accepted: 05/18/2011] [Indexed: 10/18/2022]
Abstract
Store-operated Ca(2+) entry (SOCE) is a major pathway for Ca(2+) influx in non-excitable cells. Recent studies favour a conformational coupling mechanism between the endoplasmic reticulum (ER) Ca(2+) sensor STIM1 and Ca(2+) permeable channels in the plasma membrane to explain SOCE. Previous studies have reported a role for the cytoskeleton modulating the activation of SOCE; therefore, here we have investigated whether the interaction between STIM1 and the Ca(2+) permeable channels is modulated by the actin or microtubular network. In HEK-293 cells, treatment with the microtubular disrupter colchicine enhanced both the activation of SOCE and the association between STIM1 and Orai1 or TRPC1 induced by thapsigargin (TG). Conversely, stabilization of the microtubules by paclitaxel attenuated TG-evoked activation of SOCE and the interaction between STIM1 and the Ca(2+) channels Orai1 and TRPC1, altogether suggesting that the microtubules act as a negative regulator of SOCE. Stabilization of the cortical actin filament layer results in inhibition of TG-evoked both association between STIM1, Orai1 and TRPC1 and SOCE. Interestingly, disruption of the actin filament network by cytochalasin D did not significantly modify TG-evoked association between STIM1 and Orai1 or TRPC1 but enhanced TG-stimulated SOCE. Finally, inhibition of calmodulin by calmidazolium enhances TG-evoked SOCE and disruption of the actin cytoskeleton results in inhibition of TG-evoked association of calmodulin with Orai1 and TRPC1. Thus, we demonstrate that the cytoskeleton plays an essential role in the regulation of SOCE through the modulation of the interaction between their main molecular components.
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Affiliation(s)
- Carmen Galán
- Department of Physiology (Cellular Physiology Research Group), University of Extremadura, 10071 Cáceres, Spain
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Strokin M, Sergeeva M, Reiser G. Proinflammatory treatment of astrocytes with lipopolysaccharide results in augmented Ca2+ signaling through increased expression of via phospholipase A2 (iPLA2). Am J Physiol Cell Physiol 2010; 300:C542-9. [PMID: 21178110 DOI: 10.1152/ajpcell.00428.2010] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Many Ca(2+)-regulated intracellular processes are involved in the development of neuroinflammation. However, the changes of Ca(2+) signaling in the brain under inflammatory conditions were hardly studied. ATP-induced Ca(2+) signaling is a central event of signal transmission in astrocytic networks. We investigated primary astrocytes after proinflammatory stimulation with lipopolysaccharide (LPS; 100 ng/ml) for 6-24 h. We reveal that Ca(2+) responses to purinergic ATP stimulation are significantly increased in amplitude and duration after stimulation with LPS. We detected that increased amplitudes of Ca(2+) responses to ATP in LPS-treated astrocytes can be explained by substantial increase of Ca(2+) load in stores in endoplasmic reticulum. The mechanism implies enhanced Ca(2+) store refilling due to the amplification of capacitative Ca(2+) entry. The reason for the increased duration of Ca(2+) responses in LPS-treated cells is also the amplified capacitative Ca(2+) entry. Next, we established that the molecular mechanism for the LPS-induced amplification of Ca(2+) responses in astrocytes is increased expression and activity of VIA phospholipase A(2) (VIA iPLA(2)). Indeed, both gene silencing with specific small interfering RNA and pharmacological inhibition of VIA iPLA(2) with S-bromoenol lactone reduced the load of the Ca(2+) stores and caused a decrease in the amplitudes of Ca(2+) responses in LPS-treated astrocytes to values, which were comparable with those in untreated cells. Our findings highlight a novel regulatory role of VIA iPLA(2) in development of inflammation in brain. We suggest that this enzyme might be a possible target for treatment of pathologies related to brain inflammation.
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Affiliation(s)
- Mikhail Strokin
- Institut für Neurobiochemie, Otto-von-Guericke-Universität Magdeburg, Medizinische Fakultät, Leipziger Straße 44, 39120 Magdeburg, Germany
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48
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Emter CA, Bowles DK. Store-operated Ca(2+) entry is not essential for PDGF-BB induced phenotype modulation in rat aortic smooth muscle. Cell Calcium 2010; 48:10-8. [PMID: 20619453 DOI: 10.1016/j.ceca.2010.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 05/12/2010] [Accepted: 06/08/2010] [Indexed: 12/15/2022]
Abstract
Suppression of smooth muscle cell (SMC) differentiation marker genes is central to SMC phenotype modulation during vasculo-proliferative diseases such as atherosclerosis and restenosis. Upregulation of the intermediate-conductance Ca(2+)-activated K(+) channel (K(Ca)3.1) is integral for mitogen-induced suppression of SMC marker genes and post-angioplasty restenosis. Modulation of SMC marker gene expression has been observed following Ca(2+) influx from multiple sources, however, it is unknown whether upregulation of K(Ca)3.1 and/or suppression of SMC differentiation genes is dependent on a Ca(2+) mediated mechanism. The purpose of this study was to determine the dependence of mitogen-induced SMC phenotype modulation on store-operated Ca(2+) entry (SOCE). In growth-arrested, differentiated rat aortic SMCs, platelet-derived growth factor-BB (PDGF-BB) augmented SOCE. However, PDGF-BB induced upregulation of K(Ca)3.1 and downregulation of the SMC marker gene smooth muscle myosin heavy chain (SMMHC) and myocardin was not dependent on SOCE. Co-treatment with the iPLA2 inhibitor bromoenol lactone (BEL) inhibited the effects of PDGF-BB on SMC phenotype modulation and SOCE. Our results indicate SOCE is not required for PDGF-BB induced phenotype modulation in rat aortic SMCs. Rather, we implicate a novel BEL-sensitive mechanism which regulates both SOCE and phenotype modulation, independently.
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Affiliation(s)
- Craig A Emter
- Department of Biomedical Science, University of Missouri-Columbia, 1600 E. Rollins, W160 Veterinary Medicine, Columbia, MO 65211, United States.
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Bondarenko A, Waldeck-Weiermair M, Naghdi S, Poteser M, Malli R, Graier WF. GPR55-dependent and -independent ion signalling in response to lysophosphatidylinositol in endothelial cells. Br J Pharmacol 2010; 161:308-20. [PMID: 20735417 PMCID: PMC2931756 DOI: 10.1111/j.1476-5381.2010.00744.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Revised: 01/31/2010] [Accepted: 02/06/2010] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND AND PURPOSE The glycerol-based lysophospholipid lysophosphatidylinositol (LPI) is an endogenous agonist of the G-protein-coupled receptor 55 (GPR55) exhibiting cannabinoid receptor-like properties in endothelial cells. To estimate the contribution of GPR55 to the physiological effects of LPI, the GPR55-dependent and -independent electrical responses in this cell type were investigated. EXPERIMENTAL APPROACH Applying small interference RNA-mediated knock-down and transient overexpression, GPR55-dependent and -independent effects of LPI on cytosolic free Ca(2+) concentration, membrane potential and transmembrane ion currents were studied in EA.hy296 cells. KEY RESULTS In a GPR55-dependent, GDPbetaS and U73122-sensitive manner, LPI induced rapid and transient intracellular Ca(2+) release that was associated with activation of charybdotoxin-sensitive, large conductance, Ca(2+)-activated, K(+) channels (BK(Ca)) and temporary membrane hyperpolarization. Following these initial electrical reactions, LPI elicited GPR55-independent long-lasting Na(+) loading and a non-selective inward current causing sustained membrane depolarization that depended on extracellular Ca(2+) and Na(+) and was partially inhibited by Ni(2+) and La(3+). This inward current was due to the activation of a voltage-independent non-selective cation current. The Ni(2+) and La(3+)-insensitive depolarization with LPI was prevented by inhibition of the Na/K-ATPase by ouabain. CONCLUSIONS AND IMPLICATIONS LPI elicited a biphasic response in endothelial cells of which the immediate Ca(2+) signalling depends on GPR55 while the subsequent depolarization is due to Na(+) loading via non-selective cation channels and an inhibition of the Na/K-ATPase. Thus, LPI is a potent signalling molecule that affects endothelial functions by modulating several cellular electrical responses that are only partially linked to GPR55.
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Affiliation(s)
- Alexander Bondarenko
- Institute of Molecular Biology and Biochemistry, Center of Molecular Medicine, Medical University of Graz, Graz, Austria
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Basselin M, Rosa AO, Ramadan E, Cheon Y, Chang L, Chen M, Greenstein D, Wohltmann M, Turk J, Rapoport SI. Imaging decreased brain docosahexaenoic acid metabolism and signaling in iPLA(2)β (VIA)-deficient mice. J Lipid Res 2010; 51:3166-73. [PMID: 20686114 DOI: 10.1194/jlr.m008334] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ca(2+)-independent phospholipase A(2)β (iPLA(2)β) selectively hydrolyzes docosahexaenoic acid (DHA, 22:6n-3) in vitro from phospholipid. Mutations in the PLA2G6 gene encoding this enzyme occur in patients with idiopathic neurodegeneration plus brain iron accumulation and dystonia-parkinsonism without iron accumulation, whereas mice lacking PLA2G6 show neurological dysfunction and neuropathology after 13 months. We hypothesized that brain DHA metabolism and signaling would be reduced in 4-month-old iPLA(2)β-deficient mice without overt neuropathology. Saline or the cholinergic muscarinic M(1,3,5) receptor agonist arecoline (30 mg/kg) was administered to unanesthetized iPLA(2)β(-/-), iPLA(2)β(+/-), and iPLA(2)β(+/+) mice, and [1-(14)C]DHA was infused intravenously. DHA incorporation coefficients k* and rates J(in), representing DHA metabolism, were determined using quantitative autoradiography in 81 brain regions. iPLA(2)β(-/-) or iPLA(2)β(+/-) compared with iPLA(2)β(+/+) mice showed widespread and significant baseline reductions in k* and J(in) for DHA. Arecoline increased both parameters in brain regions of iPLA(2)β(+/+) mice but quantitatively less so in iPLA(2)β(-/-) and iPLA(2)β(+/-) mice. Consistent with iPLA(2)β's reported ability to selectively hydrolyze DHA from phospholipid in vitro, iPLA(2)β deficiency reduces brain DHA metabolism and signaling in vivo at baseline and following M(1,3,5) receptor activation. Positron emission tomography might be used to image disturbed brain DHA metabolism in patients with PLA2G6 mutations.
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Affiliation(s)
- Mireille Basselin
- Brain Physiology and Metabolism Section, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA
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