1
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Karalis T, Poulogiannis G. The Emerging Role of LPA as an Oncometabolite. Cells 2024; 13:629. [PMID: 38607068 PMCID: PMC11011573 DOI: 10.3390/cells13070629] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/25/2024] [Accepted: 04/01/2024] [Indexed: 04/13/2024] Open
Abstract
Lysophosphatidic acid (LPA) is a phospholipid that displays potent signalling activities that are regulated in both an autocrine and paracrine manner. It can be found both extra- and intracellularly, where it interacts with different receptors to activate signalling pathways that regulate a plethora of cellular processes, including mitosis, proliferation and migration. LPA metabolism is complex, and its biosynthesis and catabolism are under tight control to ensure proper LPA levels in the body. In cancer patient specimens, LPA levels are frequently higher compared to those of healthy individuals and often correlate with poor responses and more aggressive disease. Accordingly, LPA, through promoting cancer cell migration and invasion, enhances the metastasis and dissemination of tumour cells. In this review, we summarise the role of LPA in the regulation of critical aspects of tumour biology and further discuss the available pre-clinical and clinical evidence regarding the feasibility and efficacy of targeting LPA metabolism for effective anticancer therapy.
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Affiliation(s)
| | - George Poulogiannis
- Signalling and Cancer Metabolism Laboratory, Division of Cancer Biology, The Institute of Cancer Research, 237 Fulham Road, London SW3 6JB, UK;
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2
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Zhang D, Lü J, Ren Z, Zhang X, Wu H, Sa R, Wang X, Wang Y, Lin Z, Zhang B. Potential cardiotoxicity induced by Euodiae Fructus: In vivo and in vitro experiments and untargeted metabolomics research. Front Pharmacol 2022; 13:1028046. [PMID: 36353487 PMCID: PMC9637925 DOI: 10.3389/fphar.2022.1028046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 10/05/2022] [Indexed: 09/16/2023] Open
Abstract
Background: Euodiae Fructus, a well-known herbal medicine, is widely used in Asia and has also gained in popularity in Western countries over the last decades. It has known side effects, which have been observed in clinical settings, but few studies have reported on its cardiotoxicity. Methods: In the present study, experiments using techniques of untargeted metabolomics clarify the hazardous effects of Euodiae Fructus on cardiac function and metabolism in rats in situations of overdosage and unsuitable syndrome differentiation. In vitro assays are conducted to observe the toxic effects of evodiamine and rutaecarpine, two main chemical constituents of Euodiae Fructus, in H9c2 and neonatal rat cardiomyocytes (NRCMs), with their signaling mechanisms analyzed accordingly. Results: The cardiac cytotoxicity of evodiamine and rutaecarpine in in vivo experiments is associated with remarkable alterations in lactate dehydrogenase, creatine kinase, and mitochondrial membrane potential; also with increased intensity of calcium fluorescence, decreased protein expression of the cGMP-PKG pathway in H9c2 cells, and frequency of spontaneous beat in NRCMs. Additionally, the results in rats with Yin deficiency receiving a high-dosage of Euodiae Fructus suggest obvious cardiac physiological dysfunction, abnormal electrocardiogram, pathological injuries, and decreased expression of PKG protein. At the level of endogenous metabolites, the cardiac side effects of overdose and irrational usage of Euodiae Fructus relate to 34 differential metabolites and 10 metabolic pathways involving among others, the purine metabolism, the glycerophospholipid metabolism, the glycerolipid metabolism, and the sphingolipid metabolism. Conclusion: These findings shed new light on the cardiotoxicity induced by Euodiae Fructus, which might be associated with overdose and unsuitable syndrome differentiation, that comes from modulating the cGMP-PKG pathway and disturbing the metabolic pathways of purine, lipid, and amino acid. Continuing research is needed to ensure pharmacovigilance for the safe administration of Chinese herbs in the future.
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Affiliation(s)
- Dan Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Jintao Lü
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Zhixin Ren
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Xiaomeng Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
- Centre for Pharmacovigilance and Rational Use of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Huanzhang Wu
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Rina Sa
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
- Gansu Provincial Hospital, Lanzhou, China
| | - Xiaofang Wang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
| | - Yu Wang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
- Centre for Pharmacovigilance and Rational Use of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Zhijian Lin
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
- Centre for Pharmacovigilance and Rational Use of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
| | - Bing Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, China
- Centre for Pharmacovigilance and Rational Use of Chinese Medicine, Beijing University of Chinese Medicine, Beijing, China
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3
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Cocozza G, Garofalo S, Capitani R, D’Alessandro G, Limatola C. Microglial Potassium Channels: From Homeostasis to Neurodegeneration. Biomolecules 2021; 11:1774. [PMID: 34944418 PMCID: PMC8698630 DOI: 10.3390/biom11121774] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/21/2022] Open
Abstract
The growing interest in the role of microglia in the progression of many neurodegenerative diseases is developing in an ever-expedited manner, in part thanks to emergent new tools for studying the morphological and functional features of the CNS. The discovery of specific biomarkers of the microglia phenotype could find application in a wide range of human diseases, and creates opportunities for the discovery and development of tailored therapeutic interventions. Among these, recent studies highlight the pivotal role of the potassium channels in regulating microglial functions in physiological and pathological conditions such as Alzheimer's Disease, Parkinson's Disease, and Amyotrophic Lateral Sclerosis. In this review, we summarize the current knowledge of the involvement of the microglial potassium channels in several neurodegenerative diseases and their role as modulators of microglial homeostasis and dysfunction in CNS disorders.
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Affiliation(s)
- Germana Cocozza
- Instituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Neuromed, 86077 Pozzilli, Italy; (G.C.); (G.D.)
| | - Stefano Garofalo
- Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy; (S.G.); (R.C.)
| | - Riccardo Capitani
- Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy; (S.G.); (R.C.)
| | - Giuseppina D’Alessandro
- Instituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Neuromed, 86077 Pozzilli, Italy; (G.C.); (G.D.)
- Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Rome, Italy; (S.G.); (R.C.)
| | - Cristina Limatola
- Instituto di Ricovero e Cura a Carattere Scientifico (IRCCS) Neuromed, 86077 Pozzilli, Italy; (G.C.); (G.D.)
- Department of Physiology and Pharmacology, Laboratory Affiliated to Istituto Pasteur Italia, Sapienza University of Rome, 00185 Rome, Italy
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4
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Ahmad S, Orellana A, Kohler I, Frölich L, de Rojas I, Gil S, Boada M, Hernández I, Hausner L, Bakker MHM, Cabrera-Socorro A, Amin N, Ramírez A, Ruiz A, Hankemeier T, Van Duijn CM. Association of lysophosphatidic acids with cerebrospinal fluid biomarkers and progression to Alzheimer's disease. ALZHEIMERS RESEARCH & THERAPY 2020; 12:124. [PMID: 33008436 PMCID: PMC7532619 DOI: 10.1186/s13195-020-00680-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 09/09/2020] [Indexed: 01/15/2023]
Abstract
Background Lysophosphatidic acids (LPAs) are bioactive signaling phospholipids that have been implicated in Alzheimer’s disease (AD). It is largely unknown whether LPAs are associated with AD pathology and progression from mild cognitive impairment (MCI) to AD. Methods The current study was performed on cerebrospinal fluid (CSF) and plasma samples of 182 MCI patients from two independent cohorts. We profiled LPA-derived metabolites using liquid chromatography-mass spectrometry. We evaluated the association of LPAs with CSF biomarkers of AD, Aβ-42, p-tau, and total tau levels overall and stratified by APOE genotype and with MCI to AD progression. Results Five LPAs (C16:0, C16:1, C22:4, C22:6, and isomer-LPA C22:5) showed significant positive association with CSF biomarkers of AD, Aβ-42, p-tau, and total tau, while LPA C14:0 and C20:1 associated only with Aβ-42 and alkyl-LPA C18:1, and LPA C20:1 associated with tau pathology biomarkers. Association of cyclic-LPA C16:0 and two LPAs (C20:4, C22:4) with Aβ-42 levels was found only in APOE ε4 carriers. Furthermore, LPA C16:0 and C16:1 also showed association with MCI to AD dementia progression, but results did not replicate in an independent cohort. Conclusions Our findings provide evidence that LPAs may contribute to early AD pathogenesis. Future studies are needed to determine whether LPAs play a role in upstream of AD pathology or are downstream markers of neurodegeneration.
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Affiliation(s)
- Shahzad Ahmad
- Department of Epidemiology, Erasmus Medical Centre, Rotterdam, The Netherlands.
| | - Adelina Orellana
- Research Center and Memory Clinic Fundació ACE, Institut Català de Neurociències, Aplicades. Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Isabelle Kohler
- Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands
| | - Lutz Frölich
- Department of Geriatric Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, 68159, Mannheim, Germany
| | - Itziar de Rojas
- Research Center and Memory Clinic Fundació ACE, Institut Català de Neurociències, Aplicades. Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Silvia Gil
- Research Center and Memory Clinic Fundació ACE, Institut Català de Neurociències, Aplicades. Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Mercè Boada
- Research Center and Memory Clinic Fundació ACE, Institut Català de Neurociències, Aplicades. Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Isabel Hernández
- Research Center and Memory Clinic Fundació ACE, Institut Català de Neurociències, Aplicades. Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Lucrezia Hausner
- Department of Geriatric Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, 68159, Mannheim, Germany.,Institute of Cognitive and Clinical Neuroscience, Central Institute of Mental Health, Medical Faculty Mannheim, Heidelberg University, 68159, Mannheim, Germany
| | - Margot H M Bakker
- Discovery Research, AbbVie Deutschland GmbH & Co. KG, Knollstrasse, 67061, Ludwigshafen, Germany
| | | | - Najaf Amin
- Department of Epidemiology, Erasmus Medical Centre, Rotterdam, The Netherlands
| | - Alfredo Ramírez
- Department for Neurodegenerative Diseases and Geriatric Psychiatry, University of Bonn, Bonn, Germany.,Division of Neurogenetics and Molecular Psychiatry, Department of Psychiatry and Psychotherapy, Medical Faculty, University of Cologne, Cologne, Germany
| | - Agustín Ruiz
- Research Center and Memory Clinic Fundació ACE, Institut Català de Neurociències, Aplicades. Universitat Internacional de Catalunya, Barcelona, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Instituto de Salud Carlos III, Madrid, Spain
| | - Thomas Hankemeier
- Department of Epidemiology, Erasmus Medical Centre, Rotterdam, The Netherlands. .,Division of Systems Biomedicine and Pharmacology, Leiden Academic Centre for Drug Research, Leiden University, Leiden, The Netherlands.
| | - Cornelia M Van Duijn
- Department of Epidemiology, Erasmus Medical Centre, Rotterdam, The Netherlands. .,Nuffield Department of Population Health, Oxford University, Oxford, UK.
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5
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Bordet R, Camu W, De Seze J, Laplaud DA, Ouallet JC, Thouvenot E. Mechanism of action of s1p receptor modulators in multiple sclerosis: The double requirement. Rev Neurol (Paris) 2020; 176:100-112. [DOI: 10.1016/j.neurol.2019.02.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 01/31/2019] [Accepted: 02/20/2019] [Indexed: 01/22/2023]
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6
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Role of Infiltrating Microglia/Macrophages in Glioma. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1202:281-298. [PMID: 32034719 DOI: 10.1007/978-3-030-30651-9_14] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In this chapter we describe the state of the art knowledge of the role played by myeloid cells in promoting and supporting the growth and the invasive properties of a deadly brain tumor, glioblastoma. We provide a review of the works describing the intercellular communication among glioma and associated microglia/macrophage cells (GAMs) using in vitro cellular models derived from mice, rats and human patients and in vivo animal models using syngeneic or xenogeneic experimental systems. Special emphasis will be given to 1) the timing alteration of brain microenvironment under the influence of glioma, 2) the bidirectional communication among tumor and GAMs, 3) possible approaches to interfere with or to guide these interactions, with the aim to identify molecular and cellular targets which could revert or delay the vicious cycle that favors tumor biology.
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7
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Plastira I, Joshi L, Bernhart E, Schoene J, Specker E, Nazare M, Sattler W. Small-Molecule Lysophosphatidic Acid Receptor 5 (LPAR5) Antagonists: Versatile Pharmacological Tools to Regulate Inflammatory Signaling in BV-2 Microglia Cells. Front Cell Neurosci 2019; 13:531. [PMID: 31849616 PMCID: PMC6897279 DOI: 10.3389/fncel.2019.00531] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 11/15/2019] [Indexed: 12/30/2022] Open
Abstract
Lysophosphatidic acid (LPA) species in the extracellular environment induce downstream signaling via six different G protein-coupled receptors (LPAR1–6). These signaling cascades are essential for normal brain development and function of the nervous system. However, in response to acute or chronic central nervous system (CNS) damage, LPA levels increase and aberrant signaling events can counteract brain function. Under neuro-inflammatory conditions signaling along the LPA/LPAR5 axis induces a potentially neurotoxic microglia phenotype indicating the need for new pharmacological intervention strategies. Therefore, we compared the effects of two novel small-molecule LPAR5 antagonists on LPA-induced polarization parameters of the BV-2 microglia cell line. AS2717638 is a selective piperidine-based LPAR5 antagonist (IC50 0.038 μM) while compound 3 is a diphenylpyrazole derivative with an IC50 concentration of 0.7 μM in BV-2 cells. Both antagonists compromised cell viability, however, at concentrations above their IC50 concentrations. Both inhibitors blunted LPA-induced phosphorylation of STAT1 and STAT3, p65, and c-Jun and consequently reduced the secretion of pro-inflammatory cyto-/chemokines (IL-6, TNFα, IL-1β, CXCL10, CXCL2, and CCL5) at non-toxic concentrations. Both compounds modulated the expression of intracellular (COX-2 and Arg1) and plasma membrane-located (CD40, CD86, and CD206) polarization markers yet only AS2717638 attenuated the neurotoxic potential of LPA-activated BV-2 cell-conditioned medium towards CATH.a neurons. Our findings from the present in vitro study suggest that the two LPAR5 antagonists represent valuable pharmacological tools to interfere with LPA-induced pro-inflammatory signaling cascades in microglia.
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Affiliation(s)
- Ioanna Plastira
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Lisha Joshi
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Eva Bernhart
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Jens Schoene
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Edgar Specker
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany
| | - Marc Nazare
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.,Berlin Institute of Health (BIH), Charite & MDC, Berlin, Germany
| | - Wolfgang Sattler
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria.,Center for Explorative Lipidomics, BioTechMed-Graz, Graz, Austria
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8
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The Novel Perspectives of Adipokines on Brain Health. Int J Mol Sci 2019; 20:ijms20225638. [PMID: 31718027 PMCID: PMC6887733 DOI: 10.3390/ijms20225638] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 11/05/2019] [Accepted: 11/06/2019] [Indexed: 12/13/2022] Open
Abstract
First seen as a fat-storage tissue, the adipose tissue is considered as a critical player in the endocrine system. Precisely, adipose tissue can produce an array of bioactive factors, including cytokines, lipids, and extracellular vesicles, which target various systemic organ systems to regulate metabolism, homeostasis, and immune response. The global effects of adipokines on metabolic events are well defined, but their impacts on brain function and pathology remain poorly defined. Receptors of adipokines are widely expressed in the brain. Mounting evidence has shown that leptin and adiponectin can cross the blood–brain barrier, while evidence for newly identified adipokines is limited. Significantly, adipocyte secretion is liable to nutritional and metabolic states, where defective circuitry, impaired neuroplasticity, and elevated neuroinflammation are symptomatic. Essentially, neurotrophic and anti-inflammatory properties of adipokines underlie their neuroprotective roles in neurodegenerative diseases. Besides, adipocyte-secreted lipids in the bloodstream can act endocrine on the distant organs. In this article, we have reviewed five adipokines (leptin, adiponectin, chemerin, apelin, visfatin) and two lipokines (palmitoleic acid and lysophosphatidic acid) on their roles involving in eating behavior, neurotrophic and neuroprotective factors in the brain. Understanding and regulating these adipokines can lead to novel therapeutic strategies to counteract metabolic associated eating disorders and neurodegenerative diseases, thus promote brain health.
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9
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Biber K, Bhattacharya A, Campbell BM, Piro JR, Rohe M, Staal RGW, Talanian RV, Möller T. Microglial Drug Targets in AD: Opportunities and Challenges in Drug Discovery and Development. Front Pharmacol 2019; 10:840. [PMID: 31507408 PMCID: PMC6716448 DOI: 10.3389/fphar.2019.00840] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 07/01/2019] [Indexed: 12/20/2022] Open
Abstract
Alzheimer’s disease (AD) is a large and increasing unmet medical need with no disease-modifying treatment currently available. Genetic evidence from genome-wide association studies (GWASs) and gene network analysis has clearly revealed a key role of the innate immune system in the brain, of which microglia are the most important element. Single-nucleotide polymorphisms (SNPs) in genes predominantly expressed in microglia have been associated with altered risk of developing AD. Furthermore, microglia-specific pathways are affected on the messenger RNA (mRNA) expression level in post-mortem AD tissue and in mouse models of AD. Together these findings have increased the interest in microglia biology, and numerous scientific reports have proposed microglial molecules and pathways as drug targets for AD. Target identification and validation are generally the first steps in drug discovery. Both target validation and drug lead identification for central nervous system (CNS) targets and diseases entail additional significant obstacles compared to peripheral targets and diseases. This makes CNS drug discovery, even with well-validated targets, challenging. In this article, we will illustrate the special challenges of AD drug discovery by discussing the viability/practicality of possible microglia drug targets including cluster of differentiation 33 (CD33), KCa3.1, kynurenines, ionotropic P2 receptor 7 (P2X7), programmed death-1 (PD-1), Toll-like receptors (TLRs), and triggering receptor expressed in myeloid cells 2 (TREM2).
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Affiliation(s)
- Knut Biber
- AbbVie Deutschland GmbH & Co. KG, Neuroscience Research, Ludwigshafen, Germany
| | | | | | - Justin R Piro
- AbbVie Foundational Neuroscience Center, Cambridge, MA, United States
| | - Michael Rohe
- AbbVie Deutschland GmbH & Co. KG, Neuroscience Research, Ludwigshafen, Germany
| | | | - Robert V Talanian
- AbbVie Foundational Neuroscience Center, Cambridge, MA, United States
| | - Thomas Möller
- AbbVie Foundational Neuroscience Center, Cambridge, MA, United States
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10
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D'Alessandro G, Limatola C, Catalano M. Functional Roles of the Ca2+-activated K+ Channel, KCa3.1, in Brain Tumors. Curr Neuropharmacol 2018; 16:636-643. [PMID: 28707595 PMCID: PMC5997864 DOI: 10.2174/0929867324666170713103621] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 06/22/2017] [Accepted: 07/12/2017] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Glioblastoma is the most aggressive and deadly brain tumor, with low disease-free period even after surgery and combined radio and chemotherapies. Among the factors contributing to the devastating effect of this tumor in the brain are the elevated proliferation and invasion rate, and the ability to induce a local immunosuppressive environment. The intermediateconductance Ca2+-activated K+ channel KCa3.1 is expressed in glioblastoma cells and in tumorinfiltrating cells. METHODS We first describe the researches related to the role of KCa3.1 channels in the invasion of brain tumor cells and the regulation of cell cycle. In the second part we review the involvement of KCa3.1 channel in tumor-associated microglia cell behaviour. RESULTS In tumor cells, the functional expression of KCa3.1 channels is important to substain cell invasion and proliferation. In tumor infiltrating cells, KCa3.1 channel activity is required to regulate their activation state. Interfering with KCa3.1 activity can be an adjuvant therapeutic approach in addition to classic chemotherapy and radiotherapy, to counteract tumor growth and prolong patient's survival. CONCLUSION In this mini-review we discuss the evidence of the functional roles of KCa3.1 channels in glioblastoma biology.
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Affiliation(s)
- Giuseppina D'Alessandro
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,IRCCS Neuromed, Pozzilli, Italy
| | - Cristina Limatola
- IRCCS Neuromed, Pozzilli, Italy.,Department of Physiology and Pharmacology, Laboratory affiliated to Istituto Pasteur Italia-Fondazione Cenci Bolognetti, Sapienza University of Rome, Rome, Italy
| | - Myriam Catalano
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy.,IRCCS Neuromed, Pozzilli, Italy
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11
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Kwon JH, Gaire BP, Park SJ, Shin DY, Choi JW. Identifying lysophosphatidic acid receptor subtype 1 (LPA 1) as a novel factor to modulate microglial activation and their TNF-α production by activating ERK1/2. Biochim Biophys Acta Mol Cell Biol Lipids 2018; 1863:1237-1245. [PMID: 30071304 DOI: 10.1016/j.bbalip.2018.07.015] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Revised: 07/24/2018] [Accepted: 07/29/2018] [Indexed: 11/29/2022]
Abstract
Microglia regulate immune responses in the brain, and their activation is key to the pathogenesis of diverse neurological diseases. Receptor-mediated lysophosphatidic acid (LPA) signaling has been known to regulate microglial biology, but it is still unclear which receptor subtypes guide the biology, particularly, microglial activation. Here, we investigated the pathogenic aspects of LPA receptor subtype 1 (LPA1) in microglial activation using a systemic lipopolysaccharide (LPS) administration-induced septic mouse model in vivo and LPS-stimulated rat primary microglia in vitro. LPA1 knockdown in the brain with its specific shRNA lentivirus attenuated the sepsis-induced microglia activation, morphological transformation, and proliferation. LPA1 knockdown also resulted in the downregulation of TNF-α, at both mRNA and protein levels in septic brains, but not IL-1β or IL-6. In rat primary microglia, genetic or pharmacological blockade of LPA1 attenuated gene upregulation and secretion of TNF-α in LPS-stimulated cells. In particular, the latter was associated with the suppressed TNF-α converting enzyme (TACE) activity. We reaffirmed these biological aspects using a BV2 microglial cell line in which LPA1 expression was negligible. LPA1 overexpression in BV2 cells led to significant increments in TNF-α production upon stimulation with LPS, whereas inhibiting LPA1 reversed the production. We further identified ERK1/2, but not p38 MAPK or Akt, as the underlying effector pathway after LPA1 activation in both septic brains and stimulated microglia. The current findings of the novel role of LPA1 in microglial activation along with its mechanistic aspects could be applied to understanding the pathogenesis of diverse neurological diseases that involve microglial activation.
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Affiliation(s)
- Jin Hyun Kwon
- College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, Incheon 406-799, Republic of Korea
| | - Bhakta Prasad Gaire
- College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, Incheon 406-799, Republic of Korea
| | - Se Jin Park
- School of Natural Resources and Environmental Sciences, Kangwon National University, Chuncheon 24341, Republic of Korea
| | - Dong-Yoon Shin
- College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, Incheon 406-799, Republic of Korea
| | - Ji Woong Choi
- College of Pharmacy and Gachon Institute of Pharmaceutical Sciences, Gachon University, Incheon 406-799, Republic of Korea.
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Hernández-Araiza I, Morales-Lázaro SL, Canul-Sánchez JA, Islas LD, Rosenbaum T. Role of lysophosphatidic acid in ion channel function and disease. J Neurophysiol 2018; 120:1198-1211. [PMID: 29947596 DOI: 10.1152/jn.00226.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Lysophosphatidic acid (LPA) is a bioactive phospholipid that exhibits a wide array of functions that include regulation of protein synthesis and adequate development of organisms. LPA is present in the membranes of cells and in the serum of several mammals and has also been shown to participate importantly in pathophysiological conditions. For several decades it was known that LPA produces some of its effects in cells through its interaction with specific G protein-coupled receptors, which in turn are responsible for signaling pathways that regulate cellular function. Among the target proteins for LPA receptors are ion channels that modulate diverse aspects of the physiology of cells and organs where they are expressed. However, recent studies have begun to unveil direct effects of LPA on ion channels, highlighting this phospholipid as a direct agonist and adding to the knowledge of the field of lipid-protein interactions. Moreover, the roles of LPA in pathophysiological conditions associated with the function of some ion channels have also begun to be clarified, and molecular mechanisms have been identified. This review focuses on the effects of LPA on ion channel function under normal and pathological conditions and highlights our present knowledge of the mechanisms by which it regulates the function and expression of N- and T-type Ca++ channels; M-type K+ channel and inward rectifier K+ channel subunit 2.1; transient receptor potential (TRP) melastatin 2, TRP vanilloid 1, and TRP ankyrin 1 channels; and TWIK-related K+ channel 1 (TREK-1), TREK-2, TWIK-related spinal cord K+ channel (TRESK), and TWIK-related arachidonic acid-stimulated K+ channel (TRAAK).
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Affiliation(s)
- Ileana Hernández-Araiza
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City, Mexico
| | - Sara L Morales-Lázaro
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City, Mexico
| | - Jesús Aldair Canul-Sánchez
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City, Mexico
| | - León D Islas
- Departamento de Fisiología, Facultad de Medicina, Universidad Nacional Autónoma de México , Mexico City, Mexico
| | - Tamara Rosenbaum
- Departamento de Neurociencia Cognitiva, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México , Mexico City, Mexico
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Ramesh S, Govindarajulu M, Suppiramaniam V, Moore T, Dhanasekaran M. Autotaxin⁻Lysophosphatidic Acid Signaling in Alzheimer's Disease. Int J Mol Sci 2018; 19:ijms19071827. [PMID: 29933579 PMCID: PMC6073975 DOI: 10.3390/ijms19071827] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 06/12/2018] [Accepted: 06/18/2018] [Indexed: 12/14/2022] Open
Abstract
The brain contains various forms of lipids that are important for maintaining its structural integrity and regulating various signaling cascades. Autotaxin (ATX) is an ecto-nucleotide pyrophosphatase/phosphodiesterase-2 enzyme that hydrolyzes extracellular lysophospholipids into the lipid mediator lysophosphatidic acid (LPA). LPA is a major bioactive lipid which acts through G protein-coupled receptors (GPCRs) and plays an important role in mediating cellular signaling processes. The majority of synthesized LPA is derived from membrane phospholipids through the action of the secreted enzyme ATX. Both ATX and LPA are highly expressed in the central nervous system. Dysfunctional expression and activity of ATX with associated changes in LPA signaling have recently been implicated in the pathogenesis of Alzheimer’s disease (AD). This review focuses on the current understanding of LPA signaling, with emphasis on the importance of the autotaxin–lysophosphatidic acid (ATX–LPA) pathway and its alterations in AD and a brief note on future therapeutic applications based on ATX–LPA signaling.
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Affiliation(s)
- Sindhu Ramesh
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
| | - Manoj Govindarajulu
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
| | - Vishnu Suppiramaniam
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
| | - Timothy Moore
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
| | - Muralikrishnan Dhanasekaran
- Department of Drug Discovery and Development, Harrison School of Pharmacy, Auburn University, Auburn, AL 36849, USA.
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14
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Lively S, Lam D, Wong R, Schlichter LC. Comparing Effects of Transforming Growth Factor β1 on Microglia From Rat and Mouse: Transcriptional Profiles and Potassium Channels. Front Cell Neurosci 2018; 12:115. [PMID: 29780305 PMCID: PMC5946019 DOI: 10.3389/fncel.2018.00115] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 04/11/2018] [Indexed: 12/02/2022] Open
Abstract
The cytokine, transforming growth factor β1 (TGFβ1), is up-regulated after central nervous system (CNS) injuries or diseases involving microglial activation, and it has been proposed as a therapeutic agent for treating neuroinflammation. Microglia can produce and respond to TGFβ1. While rats and mice are commonly used for studying neuroinflammation, very few reports directly compare them. Such studies are important for improving pre-clinical studies and furthering translational progress in developing therapeutic interventions. After intracerebral hemorrhage (ICH) in the rat striatum, the TGFβ1 receptor was highly expressed on microglia/macrophages within the hematoma. We recently found species similarities and differences in response to either a pro-inflammatory (interferon-γ, IFN-γ, +tumor necrosis factor, TNF-α) or anti-inflammatory interleukin-4 (IL-4) stimulus. Here, we assessed whether rat and mouse microglia differ in their responses to TGFβ1. Microglia were isolated from Sprague-Dawley rats and C57BL/6 mice and treated with TGFβ1. We quantified changes in expression of >50 genes, in their morphology, proliferation, apoptosis and in three potassium channels that are considered therapeutic targets. Many inflammatory mediators, immune receptors and modulators showed species similarities, but notable differences included that, for some genes, only one species responded (e.g., Il4r, Il10, Tgfbr2, colony-stimulating factor receptor (Csf1r), Itgam, suppressor of cytokine signaling 1 (Socs1), toll-like receptors 4 (Tlr4), P2rx7, P2ry12), and opposite responses were seen for others (Tgfb1, Myc, Ifngr1). In rat only, TGFβ1 affected microglial morphology and proliferation, but there was no apoptosis in either species. In both species, TGFβ1 dramatically increased Kv1.3 channel expression and current (no effects on Kir2.1). KCa3.1 showed opposite species responses: the current was low in unstimulated rat microglia and greatly increased by TGFβ1 but higher in control mouse cells and decreased by TGFβ1. Finally, we compared TGFβ1 and IL10 (often considered similar anti-inflammatory stimuli) and found many different responses in both species. Overall, the numerous species differences should be considered when characterizing neuroinflammation and microglial activation in vitro and in vivo, and when targeting potassium channels.
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Affiliation(s)
- Starlee Lively
- Krembil Research Institute, Genes and Development Division, University Health Network, Toronto, ON, Canada
| | - Doris Lam
- Krembil Research Institute, Genes and Development Division, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Raymond Wong
- Krembil Research Institute, Genes and Development Division, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
| | - Lyanne C Schlichter
- Krembil Research Institute, Genes and Development Division, University Health Network, Toronto, ON, Canada.,Department of Physiology, University of Toronto, Toronto, ON, Canada
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15
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Plastira I, Bernhart E, Goeritzer M, DeVaney T, Reicher H, Hammer A, Lohberger B, Wintersperger A, Zucol B, Graier WF, Kratky D, Malle E, Sattler W. Lysophosphatidic acid via LPA-receptor 5/protein kinase D-dependent pathways induces a motile and pro-inflammatory microglial phenotype. J Neuroinflammation 2017; 14:253. [PMID: 29258556 PMCID: PMC5735906 DOI: 10.1186/s12974-017-1024-1] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/06/2017] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Extracellular lysophosphatidic acid (LPA) species transmit signals via six different G protein-coupled receptors (LPAR1-6) and are indispensible for brain development and function of the nervous system. However, under neuroinflammatory conditions or brain damage, LPA levels increase, thereby inducing signaling cascades that counteract brain function. We describe a critical role for 1-oleyl-2-hydroxy-sn-glycero-3-phosphate (termed "LPA" throughout our study) in mediating a motile and pro-inflammatory microglial phenotype via LPAR5 that couples to protein kinase D (PKD)-mediated pathways. METHODS Using the xCELLigence system and time-lapse microscopy, we investigated the migrational response of microglial cells. Different M1 and M2 markers were analyzed by confocal microscopy, flow cytometry, and immunoblotting. Using qPCR and ELISA, we studied the expression of migratory genes and quantitated the secretion of pro-inflammatory cytokines and chemokines, respectively. Different transcription factors that promote the regulation of pro-inflammatory genes were analyzed by western blot. Reactive oxygen species (ROS) and nitric oxide (NO) production, phagocytosis, and microglial cytotoxicity were determined using commercially available assay kits. RESULTS LPA induces MAPK family and AKT activation and pro-inflammatory transcription factors' phosphorylation (NF-κB, c-Jun, STAT1, and STAT3) that were inhibited by both LPAR5 and PKD family antagonists. LPA increases migratory capacity, induces secretion of pro-inflammatory cytokines and chemokines and expression of M1 markers, enhances production of ROS and NO by microglia, and augments cytotoxicity of microglial cell-conditioned medium towards neurons. The PKD family inhibitor blunted all of these effects. We propose that interference with this signaling axis could aid in the development of new therapeutic approaches to control neuroinflammation under conditions of overshooting LPA production. CONCLUSIONS In the present study, we show that inflammatory LPA levels increased the migratory response of microglia and promoted a pro-inflammatory phenotype via the LPAR5/PKD axis. Interference with this signaling axis reduced microglial migration, blunted microglial cytotoxicity, and abrogated the expression and secretion of pro-inflammatory mediators.
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Affiliation(s)
- I. Plastira
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria
| | - E. Bernhart
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria
| | - M. Goeritzer
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria ,grid.452216.6BioTechMed-Graz, Graz, Austria
| | - T. DeVaney
- 0000 0000 8988 2476grid.11598.34Institute of Biophysics, Medical University of Graz, Graz, Austria
| | - H. Reicher
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria
| | - A. Hammer
- 0000 0000 8988 2476grid.11598.34Institute of Cell Biology, Histology and Embryology, Medical University of Graz, Graz, Austria
| | - B. Lohberger
- 0000 0000 8988 2476grid.11598.34Department of Orthopedic Surgery, Medical University of Graz, Graz, Austria
| | - A. Wintersperger
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria
| | - B. Zucol
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria
| | - W. F. Graier
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria ,grid.452216.6BioTechMed-Graz, Graz, Austria
| | - D. Kratky
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria ,grid.452216.6BioTechMed-Graz, Graz, Austria
| | - E. Malle
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria
| | - W. Sattler
- 0000 0000 8988 2476grid.11598.34Institute of Molecular Biology and Biochemistry, Medical University of Graz, Neue Stiftingtalstrasse 6/6, 8010 Graz, Austria ,grid.452216.6BioTechMed-Graz, Graz, Austria
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16
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Marfia G, Navone SE, Hadi LA, Paroni M, Berno V, Beretta M, Gualtierotti R, Ingegnoli F, Levi V, Miozzo M, Geginat J, Fassina L, Rampini P, Tremolada C, Riboni L, Campanella R. The Adipose Mesenchymal Stem Cell Secretome Inhibits Inflammatory Responses of Microglia: Evidence for an Involvement of Sphingosine-1-Phosphate Signalling. Stem Cells Dev 2016; 25:1095-107. [DOI: 10.1089/scd.2015.0268] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Affiliation(s)
- Giovanni Marfia
- Laboratory of Experimental Neurosurgery and Cell Therapy, Neurosurgery Unit, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Stefania Elena Navone
- Laboratory of Experimental Neurosurgery and Cell Therapy, Neurosurgery Unit, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Loubna Abdel Hadi
- Department of Medical Biotechnology and Translational Medicine, LITA-Segrate, University of Milan, Milan, Italy
| | - Moira Paroni
- Istituto Nazionale di Genetica Molecolare “Romeo ed Enrica Invernizzi,” Milan, Italy
| | - Valeria Berno
- Istituto Nazionale di Genetica Molecolare “Romeo ed Enrica Invernizzi,” Milan, Italy
| | - Matteo Beretta
- Laboratory of Experimental Neurosurgery and Cell Therapy, Neurosurgery Unit, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | | | | | - Vincenzo Levi
- Laboratory of Experimental Neurosurgery and Cell Therapy, Neurosurgery Unit, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Monica Miozzo
- Division of Pathology, Fondazione IRCCS Cà Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | - Jens Geginat
- Istituto Nazionale di Genetica Molecolare “Romeo ed Enrica Invernizzi,” Milan, Italy
| | - Lorenzo Fassina
- Department of Health Sciences and Industrial and Information Engineering, University of Pavia, Pavia, Italy
| | - Paolo Rampini
- Laboratory of Experimental Neurosurgery and Cell Therapy, Neurosurgery Unit, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
| | | | - Laura Riboni
- Department of Medical Biotechnology and Translational Medicine, LITA-Segrate, University of Milan, Milan, Italy
| | - Rolando Campanella
- Laboratory of Experimental Neurosurgery and Cell Therapy, Neurosurgery Unit, Fondazione IRCCS Ca'Granda Ospedale Maggiore Policlinico, University of Milan, Milan, Italy
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Dale E, Staal RGW, Eder C, Möller T. KCa 3.1-a microglial target ready for drug repurposing? Glia 2016; 64:1733-41. [PMID: 27121595 DOI: 10.1002/glia.22992] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 03/29/2016] [Accepted: 04/03/2016] [Indexed: 01/25/2023]
Abstract
Over the past decade, glial cells have attracted attention for harboring unexploited targets for drug discovery. Several glial targets have attracted de novo drug discovery programs, as highlighted in this GLIA Special Issue. Drug repurposing, which has the objective of utilizing existing drugs as well as abandoned, failed, or not yet pursued clinical development candidates for new indications, might provide a faster opportunity to bring drugs for glial targets to patients with unmet needs. Here, we review the potential of the intermediate-conductance calcium-activated potassium channels KCa 3.1 as the target for such a repurposing effort. We discuss the data on KCa 3.1 expression on microglia in vitro and in vivo and review the relevant literature on the two KCa 3.1 inhibitors TRAM-34 and Senicapoc. Finally, we provide an outlook of what it might take to harness the potential of KCa 3.1 as a bona fide microglial drug target. GLIA 2016;64:1733-1741.
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Affiliation(s)
- Elena Dale
- Neuroinflammation Disease Biology Unit, Lundbeck Research USA, Paramus, New Jersey
| | - Roland G W Staal
- Neuroinflammation Disease Biology Unit, Lundbeck Research USA, Paramus, New Jersey
| | - Claudia Eder
- Institute for Infection and Immunity, St. George's, University of London, United Kingdom
| | - Thomas Möller
- Neuroinflammation Disease Biology Unit, Lundbeck Research USA, Paramus, New Jersey
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18
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Kiyomoto M, Shinoda M, Honda K, Nakaya Y, Dezawa K, Katagiri A, Kamakura S, Inoue T, Iwata K. p38 phosphorylation in medullary microglia mediates ectopic orofacial inflammatory pain in rats. Mol Pain 2015; 11:48. [PMID: 26260484 PMCID: PMC4531532 DOI: 10.1186/s12990-015-0053-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 08/03/2015] [Indexed: 12/22/2022] Open
Abstract
Background Orofacial inflammatory pain is likely to accompany referred pain in uninflamed orofacial structures. The ectopic pain precludes precise diagnosis and makes treatment problematic, because the underlying mechanism is not well understood. Using the established ectopic orofacial pain model induced by complete Freund’s adjuvant (CFA) injection into trapezius muscle, we analyzed the possible role of p38 phosphorylation in activated microglia in ectopic orofacial pain. Results Mechanical allodynia in the lateral facial skin was induced following trapezius muscle inflammation, which accompanied microglial activation with p38 phosphorylation and hyperexcitability of wide dynamic range (WDR) neurons in the trigeminal spinal subnucleus caudalis (Vc). Intra-cisterna successive administration of a p38 mitogen-activated protein kinase selective inhibitor, SB203580, suppressed microglial activation and its phosphorylation of p38. Moreover, SB203580 administration completely suppressed mechanical allodynia in the lateral facial skin and enhanced WDR neuronal excitability in Vc. Microglial interleukin-1β over-expression in Vc was induced by trapezius muscle inflammation, which was significantly suppressed by SB203580 administration. Conclusions These findings indicate that microglia, activated via p38 phosphorylation, play a pivotal role in WDR neuronal hyperexcitability, which accounts for the mechanical hypersensitivity in the lateral facial skin associated with trapezius muscle inflammation.
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Affiliation(s)
- Masaaki Kiyomoto
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
| | - Masamichi Shinoda
- Department of Physiology, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
| | - Kuniya Honda
- Department of Physiology, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
| | - Yuka Nakaya
- Department of Oral Diagnostic Sciences, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
| | - Ko Dezawa
- Department of Oral Diagnostic Sciences, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
| | - Ayano Katagiri
- Department of Physiology, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
| | - Satoshi Kamakura
- Department of Physiology, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
| | - Tomio Inoue
- Department of Oral Physiology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
| | - Koichi Iwata
- Department of Physiology, Nihon University School of Dentistry, 1-8-13 Kandasurugadai, Chiyoda-ku, Tokyo, 101-8310, Japan.
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Abstract
Lysophosphatidic acid (LPA) is a bioactive phospholipid that is present in all tissues examined to date. LPA signals extracellularly via cognate G protein-coupled receptors to mediate cellular processes such as survival, proliferation, differentiation, migration, adhesion and morphology. These LPA-influenced processes impact many aspects of organismal development. In particular, LPA signalling has been shown to affect fertility and reproduction, formation of the nervous system, and development of the vasculature. Here and in the accompanying poster, we review the developmentally related features of LPA signalling.
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Affiliation(s)
- Xiaoyan Sheng
- Molecular and Cellular Neuroscience Department, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Yun C Yung
- Molecular and Cellular Neuroscience Department, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Allison Chen
- Molecular and Cellular Neuroscience Department, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jerold Chun
- Molecular and Cellular Neuroscience Department, Dorris Neuroscience Center, The Scripps Research Institute, La Jolla, CA 92037, USA
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20
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Kułakowska A, Byfield FJ, Zendzian-Piotrowska M, Zajkowska JM, Drozdowski W, Mroczko B, Janmey PA, Bucki R. Increased levels of sphingosine-1-phosphate in cerebrospinal fluid of patients diagnosed with tick-borne encephalitis. J Neuroinflammation 2014; 11:193. [PMID: 25421616 PMCID: PMC4258275 DOI: 10.1186/s12974-014-0193-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 11/02/2014] [Indexed: 12/21/2022] Open
Abstract
Background Tick-borne encephalitis (TBE) is a serious acute central nervous system infection that can result in death or long-term neurological dysfunctions. We hypothesize that changes in sphingosine-1-phosphate (S1P) concentration occur during TBE development. Methods S1P and interleukin-6 (IL-6) concentrations in blood plasma and cerebrospinal fluid (CSF) were measured using HPLC and ELISA, respectively. The effects of S1P on cytoskeletal structure and IL-6 production were assessed using rat astrocyte primary cultures with and without addition of plasma gelsolin and the S1P receptor antagonist fingolimod phosphate (FTY720P). Results We report that acute inflammation due to TBE virus infection is associated with elevated levels of S1P and IL-6 in the CSF of infected patients. This elevated concentration is observed even at the earliest neurologic stage of disease, and may be controlled by glucocorticosteroid anti-inflammatory treatment, administered to patients unresponsive to antipyretic drugs and who suffer from a fever above 39°C. In vitro, treatment of confluent rat astrocyte monolayers with a high concentration of S1P (5 μM) results in cytoskeletal actin remodeling that can be prevented by the addition of recombinant plasma gelsolin, FTY720P, or their combination. Additionally, gelsolin and FTY720P significantly decreased S1P-induced release of IL-6. Conclusions TBE is associated with increased concentration of S1P and IL-6 in CSF, and this increase might promote development of inflammation. The consequences of increased extracellular S1P can be modulated by gelsolin and FTY720P. Therefore, blocking the inflammatory response at sites of infection by agents modulating S1P pathways might aid in developing new strategies for TBE treatment.
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Ferreira R, Lively S, Schlichter LC. IL-4 type 1 receptor signaling up-regulates KCNN4 expression, and increases the KCa3.1 current and its contribution to migration of alternative-activated microglia. Front Cell Neurosci 2014; 8:183. [PMID: 25071444 PMCID: PMC4077126 DOI: 10.3389/fncel.2014.00183] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Accepted: 06/14/2014] [Indexed: 01/05/2023] Open
Abstract
The Ca2+-activated K+ channel, KCa3.1 (KCNN4/IK1/SK4), contributes to “classical,” pro-inflammatory activation of microglia, and KCa3.1 blockers have improved the outcome in several rodent models of CNS damage. For instance, blocking KCa3.1 with TRAM-34 rescued retinal ganglion neurons after optic nerve damage in vivo and, reduced p38 MAP kinase activation, production of reactive oxygen and nitrogen species, and neurotoxicity by microglia in vitro. In pursuing the therapeutic potential of KCa3.1 blockers, it is crucial to assess KCa3.1 contributions to other microglial functions and activation states, especially the IL-4-induced “alternative” activation state that can counteract pro-inflammatory states. We recently found that IL-4 increases microglia migration – a crucial function in the healthy and damaged CNS – and that KCa3.1 contributes to P2Y2 receptor-stimulated migration. Here, we discovered that KCa3.1 is greatly increased in alternative-activated rat microglia and then contributes to an enhanced migratory capacity. IL-4 up-regulated KCNN4 mRNA (by 6 h) and greatly increased the KCa3.1 current by 1 day, and this required de novo protein synthesis. The increase in current was sustained for at least 6 days. IL-4 increased microglial migration and this was reversed by blocking KCa3.1 with TRAM-34. A panel of inhibitors of signal-transduction mediators was used to analyze contributions of IL-4-related signaling pathways. Induction of KCNN4 mRNA and KCa3.1 current was mediated specifically through IL-4 binding to the type I receptor and, surprisingly, it required JAK3, Ras/MEK/ERK signaling and the transcription factor, activator protein-1, rather than JAK2, STAT6, or phosphatidylinositol 3-kinase.The same receptor subtype and pathway were required for the enhanced KCa3.1-dependent migration. In providing the first direct signaling link between an IL-4 receptor, expression and roles of an ion channel, this study also highlights the potential importance of KCa3.1 in alternative-activated microglia.
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Affiliation(s)
- Roger Ferreira
- Genes and Development Division, Toronto Western Research Institute, University Health Network Toronto, ON, Canada ; Department of Physiology, University of Toronto Toronto, ON, Canada
| | - Starlee Lively
- Genes and Development Division, Toronto Western Research Institute, University Health Network Toronto, ON, Canada
| | - Lyanne C Schlichter
- Genes and Development Division, Toronto Western Research Institute, University Health Network Toronto, ON, Canada ; Department of Physiology, University of Toronto Toronto, ON, Canada
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22
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Sharma P, Ping L. Calcium ion influx in microglial cells: physiological and therapeutic significance. J Neurosci Res 2014; 92:409-23. [PMID: 24464907 DOI: 10.1002/jnr.23344] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 11/09/2013] [Accepted: 11/12/2013] [Indexed: 01/16/2023]
Abstract
Microglial cells, the immunocompetent cells of the central nervous system (CNS), exhibit a resting phenotype under healthy conditions. In response to injury, however, they transform into an activated state, which is a hallmark feature of many CNS diseases. Factors or agents released from the neurons, blood vessels, and/or astrocytes could activate these cells, leading to their functional and structural modifications. Microglial cells are well equipped to sense environmental changes within the brain under both physiological and pathological conditions. Entry of calcium ions (Ca(2+)) plays a critical role in the process of microglial transformation; several channels and receptors have been identified on the surface of microglial cells. These include store-operated channel, Orai1, and its sensor protein, stromal interaction molecule 1 (STIM1), in microglial cells, and their functions are modulated under pathological stimulations. Transient receptor potential (TRP) channels and voltage- and ligand-gated channels (ionotropic and metabotropic receptors) are also responsible for Ca(2+) influx into the microglial cells. An elevation of intracellular Ca(2+) concentration subsequently regulates microglial cell functions by activating a diverse array of Ca(2+)-sensitive signaling cascades. Perturbed Ca(2+) homeostasis contributes to the progression of a number of CNS disorders. Thus, regulation of Ca(2+) entry into microglial cells could be a pharmacological target for several CNS-related pathological conditions. This Review addresses the recent insights into microglial cell Ca(2+) influx mechanisms, their roles in the regulation of functions, and alterations of Ca(2+) entry in specific CNS disorders.
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Affiliation(s)
- Purnima Sharma
- All India Institute of Medical Sciences-Physiology, Basni Industrial Area Phase II Jodhpur, Rajasthan, India
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Muessel MJ, Harry GJ, Armstrong DL, Storey NM. SDF-1α and LPA modulate microglia potassium channels through rho gtpases to regulate cell morphology. Glia 2013; 61:1620-8. [PMID: 23893870 DOI: 10.1002/glia.22543] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 05/14/2013] [Accepted: 05/16/2013] [Indexed: 12/11/2022]
Abstract
Microglia are the resident immune cells of the brain, which are important therapeutic targets for regulating the inflammatory responses particularly neurodegeneration in the aging human brain. The activation, chemotaxis and migration of microglia are regulated through G-protein coupled receptors by chemokines such as stromal cell-derived factor (SDF)-1α and bioactive lysophospholipids such as lysophosphatidic acid (LPA). Potassium channels play important roles in microglial function and cell fate decisions; however, the regulation of microglial potassium channels has not been fully elucidated. Here we show reciprocal action of SDF-1α and LPA, on potassium currents through Kir2.1 channels in primary murine microglia. The potassium channel modulation is mediated by the same small GTPases, Rac and Rho that regulate the actin cytoskeleton. SDF-1α rapidly increased the Kir2.1 current amplitude and cell spreading. These effects were mimicked by dialysing the cells with constitutively active Rac1 protein, and they were blocked by inhibiting the phosphatidylinositol 3-kinase (PI3K) with wortmannin. In contrast, LPA and constitutively active RhoA decreased the Kir2.1 currents and stimulated cell contraction. Thus, SDF-1α and LPA regulate both the actin cytoskeleton and the Kir2.1 potassium channels through the same Rho GTPase signaling pathways. The inhibition of Kir2.1 with chloroethylclonidine produced cell contraction independently of chemokine action. This suggests that potassium channels are essential for the morphological phenotype and functioning of microglia. In conclusion, the small GTPases, Rac and Rho, modulate Kir2.1 channels and block of Kir2.1 channels causes changes in microglia morphology.
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Affiliation(s)
- Michelle J Muessel
- Laboratory of Neurobiology, NIEHS/NIH, Research Triangle Park, North Carolina, USA
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Fluorescence imaging of intracellular Ca2+, Na+, and H+ in cultured microglia. Methods Mol Biol 2013. [PMID: 23813378 DOI: 10.1007/978-1-62703-520-0_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The behavior of microglial cells involves the activity of a variety of ion channels and ion transporters, which are implicated in the regulation of ion concentrations, membrane potential, and cell volume of microglia. Fluorescence imaging has been proven to be an elegant method to study ion concentration changes in intact microglial cells under physiological and pathophysiological conditions. The development of highly specific ion indicators has made it possible to detect changes in intracellular Ca(2+), Na(+), and H(+) concentrations of microglial cells as a result of ion channel or ion transporter activity. Fluorescence signals of isolated dye-loaded microglial cells can be detected via a CCD camera equipped to a conventional microscope. This chapter summarizes protocols of loading of microglial cells with small-molecule ion indicators as well as protocols optimal for measurement and analysis of intracellular Ca(2+), Na(+), and H(+) concentrations in microglia in vitro.
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Schilling T, Eder C. Patch clamp protocols to study ion channel activity in microglia. Methods Mol Biol 2013; 1041:163-82. [PMID: 23813379 DOI: 10.1007/978-1-62703-520-0_17] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Microglia express a variety of ion channels, which can be distinguished based on their ion selectivity into K(+), H(+), Na(+), Ca(2+), nonselective cation, and Cl(-) channels. With respect to their activation mode, voltage-, Ca(2+)-, calcium release-, G protein-, swelling-, and stretch-activated ion channels have been described in microglia. The best method to study the activity of microglial ion channels is the patch clamp technique. The activity of microglial ion channels under physiological conditions is best explored using the perforated patch clamp technique, which allows recordings of membrane potential or ion currents, while the intracellular milieu of the cells remains intact. In whole-cell patch clamp recordings, application of specific voltage protocols with defined intra- and extracellular solutions allows precise identification of a certain ion channel type in microglia as well as the investigation of the channel's biophysical and pharmacological properties. This chapter summarizes patch clamp protocols optimal for recording and analysis of microglial ion channel activity in vitro and in situ.
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Kashimoto R, Yamanaka H, Kobayashi K, Okubo M, Yagi H, Mimura O, Noguchi K. Phosphorylation of ezrin/radixin/moesin (ERM) protein in spinal microglia following peripheral nerve injury and lysophosphatidic acid administration. Glia 2012; 61:338-48. [PMID: 23065679 DOI: 10.1002/glia.22436] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2011] [Accepted: 09/18/2012] [Indexed: 11/09/2022]
Abstract
Peripheral nerve injury activates spinal glial cells, which may contribute to the development of pain behavioral hypersensitivity. There is growing evidence that activated microglia show dynamic changes in cell morphology; however, the molecular mechanisms that underlie the modification of the membrane and cytoskeleton of microglia are not known. Here, we investigated the phosphorylation of ezrin, radixin, and moesin (ERM) proteins in the spinal cord after peripheral nerve injury. ERM is known to function as membrane-cytoskeletal linkers and be localized at filopodia- and microvilli-like structures. ERM proteins must be phosphorylated at a specific C-terminal threonine residue to be in the active state. The nature of ERM proteins in the spinal cord of animals in a neuropathic pain model has not been investigated and characterized. In the present study, we observed an increase in the phosphorylated ERM in the spinal microglia following spared nerve injury. The intrathecal administration of lysophosphatidic acid induced the phosphorylation of ERM proteins in microglia along with the development of mechanical pain hypersensitivity. Intrathecal administration of ERM antisense locked nucleic acid suppressed nerve injury-induced tactile allodynia and decreased the phosphorylation of ERM, but not the Iba1 staining pattern, in spinal glial cells. These findings suggest that lysophosphatidic acid induced the phosphorylation of ERM proteins in spinal microglia and may be involved in the emergence of neuropathic pain. These findings may underlie the pathological mechanisms of nerve injury-induced neuropathic pain.
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Affiliation(s)
- Ryosuke Kashimoto
- Department of Ophthalmology, Hyogo College of Medicine, Nishinomiya, Japan
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Choi JW, Chun J. Lysophospholipids and their receptors in the central nervous system. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:20-32. [PMID: 22884303 DOI: 10.1016/j.bbalip.2012.07.015] [Citation(s) in RCA: 194] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2012] [Revised: 07/17/2012] [Accepted: 07/18/2012] [Indexed: 02/05/2023]
Abstract
Lysophosphatidic acid (LPA) and sphingosine 1-phosphate (S1P), two of the best-studied lysophospholipids, are known to influence diverse biological events, including organismal development as well as function and pathogenesis within multiple organ systems. These functional roles are due to a family of at least 11 G protein-coupled receptors (GPCRs), named LPA(1-6) and S1P(1-5), which are widely distributed throughout the body and that activate multiple effector pathways initiated by a range of heterotrimeric G proteins including G(i/o), G(12/13), G(q) and G(s), with actual activation dependent on receptor subtypes. In the central nervous system (CNS), a major locus for these signaling pathways, LPA and S1P have been shown to influence myriad responses in neurons and glial cell types through their cognate receptors. These receptor-mediated activities can contribute to disease pathogenesis and have therapeutic relevance to human CNS disorders as demonstrated for multiple sclerosis (MS) and possibly others that include congenital hydrocephalus, ischemic stroke, neurotrauma, neuropsychiatric disorders, developmental disorders, seizures, hearing loss, and Sandhoff disease, based upon the experimental literature. In particular, FTY720 (fingolimod, Gilenya, Novartis Pharma, AG) that becomes an analog of S1P upon phosphorylation, was approved by the FDA in 2010 as a first oral treatment for MS, validating this class of receptors as medicinal targets. This review will provide an overview and update on the biological functions of LPA and S1P signaling in the CNS, with a focus on results from studies using genetic null mutants for LPA and S1P receptors. This article is part of a Special Issue entitled Advances in Lysophospholipid Research.
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Affiliation(s)
- Ji Woong Choi
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
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Kuiper EFE, Nelemans A, Luiten P, Nijholt I, Dolga A, Eisel U. K(Ca)2 and k(ca)3 channels in learning and memory processes, and neurodegeneration. Front Pharmacol 2012; 3:107. [PMID: 22701424 PMCID: PMC3372087 DOI: 10.3389/fphar.2012.00107] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Accepted: 05/19/2012] [Indexed: 11/13/2022] Open
Abstract
Calcium-activated potassium (KCa) channels are present throughout the central nervous system as well as many peripheral tissues. Activation of KCa channels contribute to maintenance of the neuronal membrane potential and was shown to underlie the afterhyperpolarization (AHP) that regulates action potential firing and limits the firing frequency of repetitive action potentials. Different subtypes of KCa channels were anticipated on the basis of their physiological and pharmacological profiles, and cloning revealed two well defined but phylogenetic distantly related groups of channels. The group subject of this review includes both the small conductance KCa2 channels (KCa2.1, KCa2.2, and KCa2.3) and the intermediate-conductance (KCa3.1) channel. These channels are activated by submicromolar intracellular Ca2+ concentrations and are voltage independent. Of all KCa channels only the KCa2 channels can be potently but differentially blocked by the bee-venom apamin. In the past few years modulation of KCa channel activation revealed new roles for KCa2 channels in controlling dendritic excitability, synaptic functioning, and synaptic plasticity. Furthermore, KCa2 channels appeared to be involved in neurodegeneration, and learning and memory processes. In this review, we focus on the role of KCa2 and KCa3 channels in these latter mechanisms with emphasis on learning and memory, Alzheimer’s disease and on the interplay between neuroinflammation and different neurotransmitters/neuromodulators, their signaling components and KCa channel activation.
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Affiliation(s)
- Els F E Kuiper
- Molecular Neurobiology, University of Groningen Groningen, Netherlands
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Frisca F, Sabbadini RA, Goldshmit Y, Pébay A. Biological Effects of Lysophosphatidic Acid in the Nervous System. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY VOLUME 296 2012; 296:273-322. [DOI: 10.1016/b978-0-12-394307-1.00005-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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The GPR55 agonist lysophosphatidylinositol directly activates intermediate-conductance Ca2+ -activated K+ channels. Pflugers Arch 2011; 462:245-55. [PMID: 21603896 PMCID: PMC3132407 DOI: 10.1007/s00424-011-0977-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Revised: 04/27/2011] [Accepted: 05/10/2011] [Indexed: 12/16/2022]
Abstract
Lysophosphatidylinositol (LPI) was recently shown to act both as an extracellular mediator binding to G protein-coupled receptor 55 (GPR55) and as an intracellular messenger directly affecting a number of ion channels including large-conductance Ca(2+) and voltage-gated potassium (BK(Ca)) channels. Here, we explored the effect of LPI on intermediate-conductance Ca(2+)-activated K(+) (IK(Ca)) channels using excised inside-out patches from endothelial cells. The functional expression of IK(Ca) was confirmed by the charybdotoxin- and TRAM-34-sensitive hyperpolarization to histamine and ATP. Moreover, the presence of single IK(Ca) channels with a slope conductance of 39 pS in symmetric K(+) gradient was directly confirmed in inside-out patches. When cytosolically applied in the range of concentrations of 0.3-10 μM, which are well below the herein determined critical micelle concentration of approximately 30 μM, LPI potentiated the IK(Ca) single-channel activity in a concentration-dependent manner, while single-channel current amplitude was not affected. In the whole-cell configuration, LPI in the pipette was found to facilitate membrane hyperpolarization in response to low (0.5 μM) histamine concentrations in a TRAM-34-sensitive manner. These results demonstrate a so far not-described receptor-independent effect of LPI on the IK(Ca) single-channel activity of endothelial cells, thus, highlighting LPI as a potent intracellular messenger capable of modulating electrical responses in the vasculature.
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The GPR55 agonist lysophosphatidylinositol acts as an intracellular messenger and bidirectionally modulates Ca2+ -activated large-conductance K+ channels in endothelial cells. Pflugers Arch 2010; 461:177-89. [PMID: 21072666 PMCID: PMC3014879 DOI: 10.1007/s00424-010-0898-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Revised: 10/08/2010] [Accepted: 10/25/2010] [Indexed: 02/03/2023]
Abstract
Lysophospholipids are known to serve as intra- and extracellular messengers affecting many physiological processes. Lysophosphatidylinositol (LPI), which is produced in endothelial cells, acts as an endogenous agonist of the orphan receptor, G protein-coupled receptor 55 (GPR55). Stimulation of GPR55 by LPI evokes an intracellular Ca2+ rise in several cell types including endothelial cells. In this study, we investigated additional direct, receptor-independent effects of LPI on endothelial large-conductance Ca2+ and voltage-gated potassium (BKCa) channels. Electrophysiological experiments in the inside-out configuration revealed that LPI directly affects the BKCa channel gating properties. This effect of LPI strictly depended on the presence of Ca2+ and was concentration-dependent, reversible, and dual in nature. The modulating effects of LPI on endothelial BKCa channels correlated with their initial open probability (Po): stimulation at low Po (<0.3) and inhibition at high Po levels (>0.3). In the whole-cell configuration, LPI in the pipette facilitated membrane hyperpolarization in response to low (0.1–2 μM) histamine concentrations. In contrast, LPI counteracted membrane hyperpolarization in response to supramaximal cell stimulation with histamine. These results highlight a novel receptor-independent and direct bidirectional modulation of BKCa channels by LPI on endothelial cells. We conclude that LPI via this mechanism serves as an important modulator of endothelial electrical responses to cell stimulation.
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Ma L, Nagai J, Ueda H. Microglial activation mediates de novo lysophosphatidic acid production in a model of neuropathic pain. J Neurochem 2010; 115:643-53. [PMID: 20722972 DOI: 10.1111/j.1471-4159.2010.06955.x] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
We recently demonstrated that de novo lysophosphatidic acid (LPA) production in the spinal cord occurs in the early phase after nerve injury or LPA injection, and underlies the peripheral mechanisms of neuropathic pain. In this study, we examined the possible involvement of spinal cord microglia in such LPA-mediated functions. Intrathecal LPA injection rapidly increased the gene expression of CD11b and protein expression of phosphor-p38, accompanied by a morphological change of microglia from a ramified to amoeboid shape. Although early treatment with minocycline significantly inhibited LPA-induced neuropathic pain-like behavior and microglial activation, late treatment did not. Early treatment with minocycline also blocked LPA-evoked de novo LPA production and the increased activation of cytosolic phospholipase A(2), an LPA synthesis-related enzyme. Similar results were observed when the sciatic nerve was partially injured: early, but not late, treatment with minocycline significantly inhibited the injury-induced neuropathic pain, microglial activation, de novo LPA production and the underlying increased activation of cytosolic phospholipase A(2) as well as calcium-independent phospholipase A(2), another LPA synthesis-related enzyme. These findings suggest that the early phase of microglial activation is involved in de novo LPA production, and that this underlies the initial mechanisms of nerve injury-induced neuropathic pain.
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Affiliation(s)
- Lin Ma
- Division of Molecular Pharmacology and Neuroscience, Nagasaki University Graduate School of Biomedical Sciences, Bunkyo-machi, Nagasaki, Japan
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Choi JW, Herr DR, Noguchi K, Yung YC, Lee CW, Mutoh T, Lin ME, Teo ST, Park KE, Mosley AN, Chun J. LPA receptors: subtypes and biological actions. Annu Rev Pharmacol Toxicol 2010; 50:157-86. [PMID: 20055701 DOI: 10.1146/annurev.pharmtox.010909.105753] [Citation(s) in RCA: 643] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Lysophosphatidic acid (LPA) is a small, ubiquitous phospholipid that acts as an extracellular signaling molecule by binding to and activating at least five known G protein-coupled receptors (GPCRs): LPA(1)-LPA(5). They are encoded by distinct genes named LPAR1-LPAR5 in humans and Lpar1-Lpar5 in mice. The biological roles of LPA are diverse and include developmental, physiological, and pathophysiological effects. This diversity is mediated by broad and overlapping expression patterns and multiple downstream signaling pathways activated by cognate LPA receptors. Studies using cloned receptors and genetic knockout mice have been instrumental in uncovering the significance of this signaling system, notably involving basic cellular processes as well as multiple organ systems such as the nervous system. This has further provided valuable proof-of-concept data to support LPA receptors and LPA metabolic enzymes as targets for the treatment of medically important diseases that include neuropsychiatric disorders, neuropathic pain, infertility, cardiovascular disease, inflammation, fibrosis, and cancer.
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Affiliation(s)
- Ji Woong Choi
- Department of Molecular Biology, Helen L. Dorris Institute for Neurological and Psychiatric Disorders, The Scripps Research Institute, La Jolla, California 92037, USA
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Bernhart E, Kollroser M, Rechberger G, Reicher H, Heinemann A, Schratl P, Hallström S, Wintersperger A, Nusshold C, DeVaney T, Zorn-Pauly K, Malli R, Graier W, Malle E, Sattler W. Lysophosphatidic acid receptor activation affects the C13NJ microglia cell line proteome leading to alterations in glycolysis, motility, and cytoskeletal architecture. Proteomics 2010; 10:141-58. [PMID: 19899077 DOI: 10.1002/pmic.200900195] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Microglia, the immunocompetent cells of the CNS, are rapidly activated in response to injury and microglia migration towards and homing at damaged tissue plays a key role in CNS regeneration. Lysophosphatidic acid (LPA) is involved in signaling events evoking microglia responses through cognate G protein-coupled receptors. Here we show that human immortalized C13NJ microglia express LPA receptor subtypes LPA(1), LPA(2), and LPA(3) on mRNA and protein level. LPA activation of C13NJ cells induced Rho and extracellular signal-regulated kinase activation and enhanced cellular ATP production. In addition, LPA induced process retraction, cell spreading, led to pronounced changes of the actin cytoskeleton and reduced cell motility, which could be reversed by inhibition of Rho activity. To get an indication about LPA-induced global alterations in protein expression patterns a 2-D DIGE/LC-ESI-MS proteomic approach was applied. On the proteome level the most prominent changes in response to LPA were observed for glycolytic enzymes and proteins regulating cell motility and/or cytoskeletal dynamics. The present findings suggest that naturally occurring LPA is a potent regulator of microglia biology. This might be of particular relevance in the pathophysiological context of neurodegenerative disorders where LPA concentrations can be significantly elevated in the CNS.
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Affiliation(s)
- Eva Bernhart
- Institute of Molecular Biology and Biochemistry, Medical University of Graz, Austria
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Molecular and cellular basis of small--and intermediate-conductance, calcium-activated potassium channel function in the brain. Cell Mol Life Sci 2008; 65:3196-217. [PMID: 18597044 PMCID: PMC2798969 DOI: 10.1007/s00018-008-8216-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Small conductance calcium-activated potassium (SK or KCa2) channels link intracellular calcium transients to membrane potential changes. SK channel subtypes present different pharmacology and distribution in the nervous system. The selective blocker apamin, SK enhancers and mice lacking specific SK channel subunits have revealed multifaceted functions of these channels in neurons, glia and cerebral blood vessels. SK channels regulate neuronal firing by contributing to the afterhyperpolarization following action potentials and mediating IAHP, and partake in a calcium-mediated feedback loop with NMDA receptors, controlling the threshold for induction of hippocampal long-term potentiation. The function of distinct SK channel subtypes in different neurons often results from their specific coupling to different calcium sources. The prominent role of SK channels in the modulation of excitability and synaptic function of limbic, dopaminergic and cerebellar neurons hints at their possible involvement in neuronal dysfunction, either as part of the causal mechanism or as potential therapeutic targets.
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Ion channel switching and activation in smooth-muscle cells of occlusive vascular diseases. Biochem Soc Trans 2008; 35:890-4. [PMID: 17956239 DOI: 10.1042/bst0350890] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Blood vessels are essential for animal life, allowing flow of oxygen and nutrients to tissues and removal of waste products. Consequently, inappropriate remodelling of blood vessels, resulting in occlusion, can lead to disabling or catastrophic events: heart attacks, strokes and claudication. An important cell type of remodelling is the VSMC (vascular smooth-muscle cell), a fascinating cell that contributes significantly to occlusive vascular diseases by virtue of its ability to 'modulate' to a cell that no longer contracts and arranges radially in the medial layer of the vessel wall but migrates, invades, proliferates and adopts phenotypes of other cells. An intriguing aspect of modulation is switching to different ion transport systems. Initial events include loss of the Ca(V)1.2 (L-type voltage-gated calcium) channel and gain of the K(Ca)3.1 (IKCa) potassium channel, which putatively occur to enable membrane hyperpolarization that increases rather than decreases a type of calcium entry coupled with cell cycle activity, cell proliferation and cell migration. This type of calcium entry is related to store- and receptor-operated calcium entry phenomena, which, in VSMCs, are contributed to by TRPC [TRP (transient receptor potential) canonical] channel subunits. Instead of being voltage-gated, these channels are chemically gated - importantly, by key phospholipid factors of vascular development and disease. This brief review focuses on the hypothesis that the transition to a modulated cell may require a switch from predominantly voltage- to predominantly lipid-sensing ion channels.
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Bradykinin-induced microglial migration mediated by B1-bradykinin receptors depends on Ca2+ influx via reverse-mode activity of the Na+/Ca2+ exchanger. J Neurosci 2008; 27:13065-73. [PMID: 18045900 DOI: 10.1523/jneurosci.3467-07.2007] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Bradykinin (BK) is produced and acts at the site of injury and inflammation. In the CNS, migration of microglia toward the lesion site plays an important role pathologically. In the present study, we investigated the effect of BK on microglial migration. Increased motility of cultured microglia was mimicked by B1 receptor agonists and markedly inhibited by a B1 antagonist but not by a B2 receptor antagonist. BK induced chemotaxis in microglia isolated from wild-type and B2-knock-out mice but not from B1-knock-out mice. BK-induced motility was not blocked by pertussis toxin but was blocked by chelating intracellular Ca2+ or by low extracellular Ca2+, implying that Ca2+ influx is prerequisite. Blocking the reverse mode of Na+/Ca2+ exchanger (NCX) completely inhibited BK-induced migration. The involvement of NCX was further confirmed by using NCX+/- mice; B1-agonist-induced motility and chemotaxis was decreased compared with that in NCX+/+ mice. Activation of NCX seemed to be dependent on protein kinase C and phosphoinositide 3-kinase, and resultant activation of intermediate-conductance (IK-type) Ca2+-dependent K+ currents (I(K(Ca))) was activated. Despite these effects, BK did not activate microglia, as judged from OX6 staining. Using in vivo lesion models and pharmacological injection to the brain, it was shown that microglial accumulation around the lesion was also dependent on B1 receptors and I(K(Ca)). These observations support the view that BK functions as a chemoattractant by using the distinct signal pathways in the brain and, thus, attracts microglia to the lesion site in vivo.
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Schilling T, Eder C. Ion channel expression in resting and activated microglia of hippocampal slices from juvenile mice. Brain Res 2007; 1186:21-8. [DOI: 10.1016/j.brainres.2007.10.027] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/04/2007] [Accepted: 10/13/2007] [Indexed: 12/18/2022]
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Dev KK, Mullershausen F, Mattes H, Kuhn RR, Bilbe G, Hoyer D, Mir A. Brain sphingosine-1-phosphate receptors: implication for FTY720 in the treatment of multiple sclerosis. Pharmacol Ther 2007; 117:77-93. [PMID: 17961662 DOI: 10.1016/j.pharmthera.2007.08.005] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 08/16/2007] [Indexed: 10/22/2022]
Abstract
Multiple sclerosis (MS) is an autoimmune, neurological disability with unknown etiology. The current therapies available for MS work by an immunomodulatory action, preventing T-cell- and macrophage-mediated destruction of brain-resident oligodendrocytes and axonal loss. Recently, FTY720 (fingolimod) was shown to significantly reduce relapse rates in MS patients and is currently in Phase III clinical trials. This drug attenuates trafficking of harmful T cells entering the brain by regulating sphingosine-1-phosphate (S1P) receptors. Here, we outline the direct roles that S1P receptors play in the central nervous system (CNS) and discuss additional modalities by which FTY720 may provide direct neuroprotection in MS.
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Affiliation(s)
- Kumlesh K Dev
- Department of Anatomy and Neuroscience, University College Cork, Windle Building, Cork, Ireland.
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Stock C, Schilling T, Schwab A, Eder C. Lysophosphatidylcholine stimulates IL-1beta release from microglia via a P2X7 receptor-independent mechanism. THE JOURNAL OF IMMUNOLOGY 2007; 177:8560-8. [PMID: 17142754 DOI: 10.4049/jimmunol.177.12.8560] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IL-1beta released from activated macrophages contributes significantly to tissue damage in inflammatory, degenerative, and autoimmune diseases. In the present study, we identified a novel mechanism of IL-1beta release from activated microglia (brain macrophages) that occurred independently of P2X(7) ATP receptor activation. Stimulation of LPS-preactivated microglia with lysophosphatidylcholine (LPC) caused rapid processing and secretion of mature 17-kDa IL-1beta. Neither LPC-induced IL-1beta release nor LPC-stimulated intracellular Ca(2+) increases were affected by inhibition of P2X(7) ATP receptors with oxidized ATP. Microglial LPC-induced IL-1beta release was suppressed in Ca(2+)-free medium or during inhibition of nonselective cation channels with Gd(3+) or La(3+). It was also attenuated when Ca(2+)-activated K(+) channels were blocked with charybdotoxin (CTX). The electroneutral K(+) ionophore nigericin did not reverse the suppressive effects of CTX on LPC-stimulated IL-1beta release, demonstrating the importance of membrane hyperpolarization. Furthermore, LPC-stimulated caspase activity was unaffected by Ca(2+)-free medium or CTX, suggesting that secretion but not processing of IL-1beta is Ca(2+)- and voltage-dependent. In summary, these data indicate that the activity of nonselective cation channels and Ca(2+)-activated K(+) channels is required for optimal IL-1beta release from LPC-stimulated microglia.
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Affiliation(s)
- Christian Stock
- Institute of Physiology II, University of Muenster, Muenster, Germany
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Femling JK, Cherny VV, Morgan D, Rada B, Davis AP, Czirják G, Enyedi P, England SK, Moreland JG, Ligeti E, Nauseef WM, DeCoursey TE. The antibacterial activity of human neutrophils and eosinophils requires proton channels but not BK channels. J Gen Physiol 2006; 127:659-72. [PMID: 16702353 PMCID: PMC2151543 DOI: 10.1085/jgp.200609504] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2006] [Accepted: 04/25/2006] [Indexed: 02/01/2023] Open
Abstract
Electrophysiological events are of central importance during the phagocyte respiratory burst, because NADPH oxidase is electrogenic and voltage sensitive. We investigated the recent suggestion that large-conductance, calcium-activated K(+) (BK) channels, rather than proton channels, play an essential role in innate immunity (Ahluwalia, J., A. Tinker, L.H. Clapp, M.R. Duchen, A.Y. Abramov, S. Page, M. Nobles, and A.W. Segal. 2004. Nature. 427:853-858). In PMA-stimulated human neutrophils or eosinophils, we did not detect BK currents, and neither of the BK channel inhibitors iberiotoxin or paxilline nor DPI inhibited any component of outward current. BK inhibitors did not inhibit the killing of bacteria, nor did they affect NADPH oxidase-dependent degradation of bacterial phospholipids by extracellular gIIA-PLA(2) or the production of superoxide anion (O(2*)(-)). Moreover, an antibody against the BK channel did not detect immunoreactive protein in human neutrophils. A required role for voltage-gated proton channels is demonstrated by Zn(2+) inhibition of NADPH oxidase activity assessed by H(2)O(2) production, thus validating previous studies showing that Zn(2+) inhibited O(2*)(-) production when assessed by cytochrome c reduction. In conclusion, BK channels were not detected in human neutrophils or eosinophils, and BK inhibitors did not impair antimicrobial activity. In contrast, we present additional evidence that voltage-gated proton channels serve the essential role of charge compensation during the respiratory burst.
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Affiliation(s)
- Jon K Femling
- Inflammation Program, Roy J. and Luille A. Carver College of Medicine, University of Iowa, Coralville, 52241, USA
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42
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Zhang YH, Fehrenbacher JC, Vasko MR, Nicol GD. Sphingosine-1-phosphate via activation of a G-protein-coupled receptor(s) enhances the excitability of rat sensory neurons. J Neurophysiol 2006; 96:1042-52. [PMID: 16723416 DOI: 10.1152/jn.00120.2006] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Sphingosine-1-phosphate (S1P) is released by immune cells and is thought to play a key role in chemotaxis and the onset of the inflammatory response. The question remains whether this lipid mediator also contributes to the enhanced sensitivity of nociceptive neurons that is associated with inflammation. Therefore we examined whether S1P alters the excitability of small diameter, capsaicin-sensitive sensory neurons by measuring action potential (AP) firing and two of the membrane currents critical in regulating the properties of the AP. External application of S1P augments the number of APs evoked by a depolarizing current ramp. The enhanced firing is associated with a decrease in the rheobase and an increase in the resistance at firing threshold although neither the firing threshold nor the resting membrane potential are changed. Treatment with S1P enhanced the tetrodotoxin-resistant sodium current and decreased the total outward potassium current (IK). When sensory neurons were internally perfused with GDP-beta-S, a blocker of G protein activation, the S1P-induced increase in APs was completely blocked and suggests the excitatory actions of S1P are mediated through G-protein-coupled receptors called endothelial differentiation gene or S1PR. In contrast, internal perfusion with GDP-beta-S and S1P increased the number of APs evoked by the current ramp. These results and our finding that the mRNAs for S1PRs are expressed in both the intact dorsal root ganglion and cultures of adult sensory neurons supports the notion that S1P acts on S1PRs linked to G proteins. Together these findings demonstrate that S1P can regulate the excitability of small diameter sensory neurons by acting as an external paracrine-type ligand through activation of G-protein-coupled receptors and thus may contribute to the hypersensitivity during inflammation.
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MESH Headings
- Animals
- Cells, Cultured
- Ganglia, Spinal/physiology
- Lysophospholipids/pharmacology
- Male
- Neurons, Afferent/drug effects
- Neurons, Afferent/physiology
- Patch-Clamp Techniques
- Polymerase Chain Reaction
- Rats
- Rats, Sprague-Dawley
- Receptors, G-Protein-Coupled/drug effects
- Receptors, G-Protein-Coupled/physiology
- Receptors, Lysosphingolipid/drug effects
- Receptors, Lysosphingolipid/genetics
- Receptors, Lysosphingolipid/physiology
- Sphingosine/analogs & derivatives
- Sphingosine/pharmacology
- Tetrodotoxin/pharmacology
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Affiliation(s)
- Y H Zhang
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Abstract
Microglia play an important role in the central nervous system, where these cells, it is believed, have both neuroprotective and neurotoxic effects. In response to acute brain injury or during neurodegenerative and neuroinflammatory diseases, activated microglial cells undergo shape changes, migrate to the affected sites of neuronal damage, proliferate, and release a variety of substances, such as cytokines and reactive oxygen species (ROS). This review summarizes the physiological mechanisms underlying microglial activation and deactivation processes, with particular focus on the involvement of microglial ion channels. Microglial ion channels have been shown to be capable, by regulating membrane potential, cell volume, and intracellular ion concentrations, of modulating or facilitating proliferation, migration, cytokine secretion, shape changes, and the respiratory burst of microglial cells.
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Affiliation(s)
- Claudia Eder
- Institute of Physiology, Humboldt University, Berlin, Germany.
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Noda M, Kariura Y, Amano T, Manago Y, Nishikawa K, Aoki S, Wada K. Kinin receptors in cultured rat microglia. Neurochem Int 2004; 45:437-42. [PMID: 15145558 DOI: 10.1016/j.neuint.2003.07.007] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2003] [Revised: 07/29/2003] [Accepted: 07/29/2003] [Indexed: 11/30/2022]
Abstract
Kinins are produced and act at the site of injury and inflammation in various tissues. They are likely to initiate a particular cascade of inflammatory events, which evokes physiological and pathophysiological responses including an increase in blood flow and plasma leakage. In the central nervous system (CNS), kinins are potent stimulators of the production and release of pro-inflammatory mediators represented by prostanoids and cytotoxins. They are known to induce neural tissue damage. Many of the cytotoxins such as cytokines and free radicals and prostanoids are released from glial cells. Among glial cells, astrocytes and oligodendrocytes are known to possess bradykinin (BK) B(2) receptors that phosphoinositide (PI) turnover and raise intracellular Ca(2+) concentration. The presence of bradykinin receptors in microglia has been of great significance. We recently showed that rat primary microglia express kinin receptors. In resting microglia, B(2) receptors but not B(1) receptors are expressed. When the microglia are activated by bradykinin, B(1) receptors are up-regulated, while B(2) receptors are down-regulated. As observed in other glial cells, electrophysiological measurements suggest that B(2) receptors in phosphoinositide turnover and intracellular Ca(2+) concentration in microglia. Release of cytotoxins is likely consequent upon the activation of BK receptors. Our study provides the first evidence that microglia express functional kinin receptors and suggests that microglia play an important role in CNS inflammatory responses.
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Affiliation(s)
- Mami Noda
- Laboratory of Pathophysiology, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Fukuoka 812-8582, Japan.
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Kuhn SA, van Landeghem FKH, Zacharias R, Färber K, Rappert A, Pavlovic S, Hoffmann A, Nolte C, Kettenmann H. Microglia express GABA(B) receptors to modulate interleukin release. Mol Cell Neurosci 2004; 25:312-22. [PMID: 15019947 DOI: 10.1016/j.mcn.2003.10.023] [Citation(s) in RCA: 152] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2003] [Revised: 10/20/2003] [Accepted: 10/30/2003] [Indexed: 11/24/2022] Open
Abstract
gamma-Aminobutyric acid (GABA) can act as a neuroprotective agent besides its well-established role as the main inhibitory neurotransmitter in the CNS. Here we report that microglial cells express GABA(B) receptors indicating that these prominent immunocompetent cells in the brain are a target for GABA. Agonists of GABA(B) receptors triggered the induction of K(+) conductance in microglial cells from acute brain slices and in culture. Both subunits of GABA(B) receptors were identified in cultured microglia by Western blot analysis and immunocytochemistry, and were detected on a subpopulation of microglia in situ by immunohistochemistry. In response to facial nerve axotomy, we observed an increase in GABA(B) receptor expressing microglial cells in the facial nucleus. We activated microglial cells in culture with lipopolysaccharide (LPS) to induce the release of interleukin-6 and interleukin-12p40. This release activity was attenuated by simultaneous activation of the GABA(B) receptors indicating that GABA can modulate the microglial immune response.
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Affiliation(s)
- Susanne A Kuhn
- Department of Cellular Neuroscience, Max-Delbrück-Center for Molecular Medicine, D-13125 Berlin, Germany
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46
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Hanley PJ, Musset B, Renigunta V, Limberg SH, Dalpke AH, Sus R, Heeg KM, Preisig-Müller R, Daut J. Extracellular ATP induces oscillations of intracellular Ca2+ and membrane potential and promotes transcription of IL-6 in macrophages. Proc Natl Acad Sci U S A 2004; 101:9479-84. [PMID: 15194822 PMCID: PMC439002 DOI: 10.1073/pnas.0400733101] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The effects of low concentrations of extracellular ATP on cytosolic Ca(2+), membrane potential, and transcription of IL-6 were studied in monocyte-derived human macrophages. During inflammation or infection many cells secrete ATP. We show here that application of 10 microM ATP or 10 microM UTP induces oscillations in cytosolic Ca(2+) with a frequency of approximately 12 min(-1) and oscillations in membrane potential. RT-PCR analysis showed expression of P2Y(1), P2Y(2), P2Y(11), P2X(1), P2X(4), and P2X(7) receptors, large-conductance (KCNMA1 and KCNMB1-4), and intermediate-conductance (KCNN4) Ca(2+)-activated K(+) channels. The Ca(2+)oscillations were unchanged after removal of extracellular Ca(2+), indicating that they were mainly due to movements of Ca(2+) between intracellular compartments. Comparison of the effects of different nucleotides suggests that the Ca(2+) oscillations were elicited by activation of P2Y(2) receptors coupled to phospholipase C. Patch-clamp experiments showed that ATP induced a transient depolarization, probably mediated by activation of P2X(4) receptors, followed by membrane potential oscillations due to opening of Ca(2+)-activated K(+) channels. We also found that 10 microM ATP gamma S increased transcription of IL-6 approximately 40-fold within 2 h. This effect was abolished by blockade of P2Y receptors with 100 microM suramin. Our results suggest that ATP released from inflamed, damaged, or metabolically impaired cells represents a "danger signal" that plays a major role in activating the innate immune system.
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Affiliation(s)
- Peter J Hanley
- Institute of Physiology, Marburg University, Deutschhausstrasse 2, 35037 Marburg, Germany
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Schilling T, Stock C, Schwab A, Eder C. Functional importance of Ca2+-activated K+ channels for lysophosphatidic acid-induced microglial migration. Eur J Neurosci 2004; 19:1469-74. [PMID: 15066143 DOI: 10.1111/j.1460-9568.2004.03265.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Abstract Migration of microglial cells towards damaged tissue plays a key role in central nervous system regeneration under pathological conditions. Using time lapse video microscopy we show that lysophosphatidic acid (LPA) enhances chemokinetic migration of murine microglial cells. In the presence of 1 micro m LPA, the mean migration rate of microglial cells was increased 3.8-fold. In patch-clamp studies we demonstrate that LPA induces activation of a Ca(2+)-activated K(+) current. Microglial Ca(2+)-activated K(+) currents were abolished by either 50 nm charybdotoxin or 10 micro m clotrimazole. In contrast, 5 micro m paxilline did not have any significant effects on Ca(2+)-activated K(+) currents. The LPA-stimulated migration of microglial cells was inhibited by blockers of IKCa1 Ca(2+)-activated K(+) channels. The mean migration rate of LPA-stimulated cells was decreased by 61% in the presence of 50 nm charybdotoxin or by 51% during exposure to 10 micro m clotrimazole. Microglial migration was not inhibited by 5 micro m paxilline. It is concluded that IKCa1 Ca(2+)-activated K(+) channels are required for LPA-stimulated migration of microglial cells.
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Affiliation(s)
- Tom Schilling
- Institute of Physiology, Humboldt University Berlin, Tucholsky Strasse 2, D-10117 Berlin, Germany
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48
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Schilling T, Lehmann F, Rückert B, Eder C. Physiological mechanisms of lysophosphatidylcholine-induced de-ramification of murine microglia. J Physiol 2004; 557:105-20. [PMID: 15020687 PMCID: PMC1665039 DOI: 10.1113/jphysiol.2004.060632] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2004] [Accepted: 03/10/2004] [Indexed: 12/16/2022] Open
Abstract
Activation of microglial cells, the resident macrophages of the brain, occurs rapidly following brain injury. De-ramification, i.e. transformation from ramified into amoeboid morphology is one of the earliest manifestations of microglial activation. In the present study, we identified the physiological mechanisms underlying microglial de-ramification induced by lysophosphatidylcholine (LPC). Patch-clamp experiments revealed activation of non-selective cation currents and Ca(2+)-dependent K(+) currents by extracellular LPC. LPC-activated non-selective cation channels were permeable for monovalent and divalent cations. They were inhibited by Gd(3+), La(3+), Zn(2+) and Grammostola spatulata venom, but were unaffected by diltiazem, LOE908MS, amiloride and DIDS. Ca(2+) influx through non-selective cation channels caused sustained increases in intracellular Ca(2+) concentration. These Ca(2+) increases were sufficient to elicit charybdotoxin-sensitive Ca(2+)-dependent K(+) currents. However, increased [Ca(2+)](i) was not required for LPC-induced morphological changes. In LPC-stimulated microglial cells, non-selective cation currents caused transient membrane depolarization, which was followed by sustained membrane hyperpolarization induced by Ca(2+)-dependent K(+) currents. Furthermore, LPC elicited K(+) efflux by stimulating electroneutral K(+)-Cl(-) cotransporters, which were inhibited by furosemide and DIOA. LPC-induced microglial de-ramification was prevented by simultaneous inhibition of non-selective cation channels and K(+)-Cl(-) cotransporters, suggesting their functional importance for microglial activation.
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Affiliation(s)
- Tom Schilling
- Institute of Physiology, Humboldt University, Tucholskystr. 2, D-10117 Berlin, Germany
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49
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Jiang X, Newell EW, Schlichter LC. Regulation of a TRPM7-like current in rat brain microglia. J Biol Chem 2003; 278:42867-76. [PMID: 12904301 DOI: 10.1074/jbc.m304487200] [Citation(s) in RCA: 111] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Non-excitable cells use Ca2+ influx for essential functions but usually lack voltage-gated Ca2+ channels. The main routes of Ca2+ entry appear to be store-operated channels or Ca2+-permeable non-selective cation channels, of which the magnesium-inhibited cation (or magnesium-nucleotide-regulated metal cation) current has received considerable recent attention. This current appears to be produced by one of the recently cloned transient receptor potential (TRP) channels, TRPM7. In this study of rat microglia, we identified TRPM7 transcripts and a prevalent current with the hallmark biophysical and pharmacological features of TRPM7. This is the first identification of a TRPM7-like current in the brain. There is little known about how members of the TRPM sub-family normally become activated. Using whole-cell patch clamp recordings from rat microglia, we found that the TRPM7-like current activates spontaneously after break-in and that the current and its activation are inhibited by elevated intracellular Mg2+ but not affected by cell swelling or a wide range of intracellular Ca2+ concentrations. The TRPM7-like current in microglia appears to depend on tyrosine phosphorylation. It was inhibited by several tyrosine kinase inhibitors, including a peptide (Src 40-58) that was shown previously to inhibit Src actions, but not by inactive drugs or peptide analogues. The current did not depend on the cell activation state; i.e. it was the same in microglia recently removed from the brain or when cultured under a wide range of conditions that favor the resting or activated state. Because TRPM7 channels are permeable to Ca2+, this current may be important for microglia functions that depend on elevations in intracellular Ca2+.
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Affiliation(s)
- Xinpo Jiang
- Division of Cellular and Molecular Biology, Toronto Western Research Institute, 399 Bathurst Street, Toronto, Ontario M5T 2S8, Canada
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50
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Coursol S, Fan LM, Le Stunff H, Spiegel S, Gilroy S, Assmann SM. Sphingolipid signalling in Arabidopsis guard cells involves heterotrimeric G proteins. Nature 2003; 423:651-4. [PMID: 12789341 DOI: 10.1038/nature01643] [Citation(s) in RCA: 235] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2003] [Accepted: 04/07/2003] [Indexed: 11/09/2022]
Abstract
In animals, the sphingolipid metabolite sphingosine-1-phosphate (S1P) functions as both an intracellular messenger and an extracellular ligand for G-protein-coupled receptors of the S1P receptor family, regulating diverse biological processes ranging from cell proliferation to apoptosis. Recently, it was discovered in plants that S1P is a signalling molecule involved in abscisic acid (ABA) regulation of guard cell turgor. Here we report that the enzyme responsible for S1P production, sphingosine kinase (SphK), is activated by ABA in Arabidopsis thaliana, and is involved in both ABA inhibition of stomatal opening and promotion of stomatal closure. Consistent with this observation, inhibition of SphK attenuates ABA regulation of guard cell inward K(+) channels and slow anion channels, which are involved in the regulation of stomatal pore size. Surprisingly, S1P regulates stomatal apertures and guard cell ion channel activities in wild-type plants, but not in knockout lines of the sole prototypical heterotrimeric G-protein alpha-subunit gene, GPA1 (refs 5, 6, 7-8). Our results implicate heterotrimeric G proteins as downstream elements in the S1P signalling pathway that mediates ABA regulation of stomatal function, and suggest that the interplay between S1P and heterotrimeric G proteins represents an evolutionarily conserved signalling mechanism.
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Affiliation(s)
- Sylvie Coursol
- Department of Biology, Pennsylvania State University, 208 Mueller Laboratory, University Park, Pennsylvania 16802-5301, USA
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