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de Melo ASLF, Lima JLD, Malta MCS, Marroquim NF, Moreira ÁR, de Almeida Ladeia I, dos Santos Cardoso F, Gonçalves DB, Dutra BG, dos Santos JCC. The role of microglia in prion diseases and possible therapeutic targets: a literature review. Prion 2021; 15:191-206. [PMID: 34751640 PMCID: PMC8583147 DOI: 10.1080/19336896.2021.1991771] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 10/01/2021] [Indexed: 11/19/2022] Open
Abstract
Creutzfeldt-Jakob disease (CJD) is a rare and fatal condition that leads to progressive neurodegeneration due to gliosis, vacuolation of central nervous system tissue, and loss of neurons. Microglia play a crucial role in maintaining Central Nervous System (CNS) homoeostasis, both in health and disease, through phagocytosis and cytokine production. In the context of CJD, the immunomodulatory function of microglia turns it into a cell of particular interest. Microglia would be activated by infectious prion proteins, initially acquiring a phagocytic and anti-inflammatory profile (M2), and producing cytokines such as IL-4, IL-10, and TGF-β. Therefore, microglia are seen as a key target for the development of new treatment approaches, with many emerging strategies to guide it towards a beneficial role upon neuroinflammation, by manipulating its metabolic pathways. In such a setting, many cellular targets in microglia that can be involved in phenotype modulation, such as membrane receptors, have been identified and pointed out as possible targets for further experiments and therapeutic approaches. In this article, we review the major findings about the role of microglia in CJD, including its relationship to some risk factors associated with the development of the disease. Furthermore, considering its central role in neural immunity, we explore microglial connection with other elements of the immune system and cell signalling, such as inflammasomes, the complement and purinergic systems, and the latest finding strategies to guide these cells from harmful to beneficial roles.
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Affiliation(s)
| | | | | | | | - Álvaro Rivelli Moreira
- Department of Neurology, Centro Universitário Governador Ozanam Coelho, UniFacog, Ubá, MG, Brazil
| | | | - Fabrizio dos Santos Cardoso
- Núcleo de Pesquisas Tecnológicas, Universidade De Mogi Das Cruzes, Mogi das Cruzes, SP, Brazil
- Department of Psychology and Institute for Neuroscience, University of Texas (Ut), Austin, TX, USA
| | | | | | - Júlio César Claudino dos Santos
- Laboratório de Neurociências, Departamento De Neurologia E Neurocirurgia, Universidade Federal de São Paulo, São Paulo, Sp, Brazil
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Neuroinflammation in CNS diseases: Molecular mechanisms and the therapeutic potential of plant derived bioactive molecules. PHARMANUTRITION 2020. [DOI: 10.1016/j.phanu.2020.100176] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Rodrigues RJ, Tomé AR, Cunha RA. ATP as a multi-target danger signal in the brain. Front Neurosci 2015; 9:148. [PMID: 25972780 PMCID: PMC4412015 DOI: 10.3389/fnins.2015.00148] [Citation(s) in RCA: 185] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Accepted: 04/10/2015] [Indexed: 12/13/2022] Open
Abstract
ATP is released in an activity-dependent manner from different cell types in the brain, fulfilling different roles as a neurotransmitter, neuromodulator, in astrocyte-to-neuron communication, propagating astrocytic responses and formatting microglia responses. This involves the activation of different ATP P2 receptors (P2R) as well as adenosine receptors upon extracellular ATP catabolism by ecto-nucleotidases. Notably, brain noxious stimuli trigger a sustained increase of extracellular ATP, which plays a key role as danger signal in the brain. This involves a combined action of extracellular ATP in different cell types, namely increasing the susceptibility of neurons to damage, promoting astrogliosis and recruiting and formatting microglia to mount neuroinflammatory responses. Such actions involve the activation of different receptors, as heralded by neuroprotective effects resulting from blockade mainly of P2X7R, P2Y1R and adenosine A2A receptors (A2AR), which hierarchy, cooperation and/or redundancy is still not resolved. These pleiotropic functions of ATP as a danger signal in brain damage prompt a therapeutic interest to multi-target different purinergic receptors to provide maximal opportunities for neuroprotection.
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Affiliation(s)
- Ricardo J Rodrigues
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal ; Institute for Interdisciplinary Research, University of Coimbra Coimbra, Portugal
| | - Angelo R Tomé
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal ; Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra Coimbra, Portugal
| | - Rodrigo A Cunha
- CNC - Center for Neuroscience and Cell Biology, University of Coimbra Coimbra, Portugal ; Faculty of Medicine, University of Coimbra Coimbra, Portugal
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Network-wide dysregulation of calcium homeostasis in Alzheimer’s disease. Cell Tissue Res 2014; 357:427-38. [DOI: 10.1007/s00441-014-1798-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 01/09/2014] [Indexed: 12/19/2022]
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Burnstock G. Introduction and perspective, historical note. Front Cell Neurosci 2013; 7:227. [PMID: 24312014 PMCID: PMC3836022 DOI: 10.3389/fncel.2013.00227] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2013] [Accepted: 11/04/2013] [Indexed: 12/11/2022] Open
Abstract
P2 nucleotide receptors were proposed to consist of two subfamilies based on pharmacology in 1985, named P2X and P2Y receptors. Later, this was confirmed following cloning of the receptors for nucleotides and studies of transduction mechanisms in the early 1990s. P2X receptors are ion channels and seven subtypes are recognized that form trimeric homomultimers or heteromultimers. P2X receptors are involved in neuromuscular and synaptic neurotransmission and neuromodulation. They are also expressed on many types of non-neuronal cells to mediate smooth muscle contraction, secretion, and immune modulation. The emphasis in this review will be on the pathophysiology of P2X receptors and therapeutic potential of P2X receptor agonists and antagonists for neurodegenerative and inflammatory disorders, visceral and neuropathic pain, irritable bowel syndrome, diabetes, kidney failure, bladder incontinence and cancer, as well as disorders if the special senses, airways, skin, cardiovascular, and musculoskeletal systems.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical SchoolLondon, UK
- Department of Pharmacology, The University of MelbourneMelbourne, VIC, Australia
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P2X7 receptor activation induces reactive oxygen species formation and cell death in murine EOC13 microglia. Mediators Inflamm 2013; 2013:271813. [PMID: 23431238 PMCID: PMC3568910 DOI: 10.1155/2013/271813] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 11/16/2012] [Accepted: 12/04/2012] [Indexed: 12/04/2022] Open
Abstract
The P2X7 purinergic receptor is a ligand-gated cation channel expressed on leukocytes including microglia. This study aimed to determine if P2X7 activation induces the uptake of organic cations, reactive oxygen species (ROS) formation, and death in the murine microglial EOC13 cell line. Using the murine macrophage J774 cell line as a positive control, RT-PCR, immunoblotting, and immunolabelling established the presence of P2X7 in EOC13 cells. A cytofluorometric assay demonstrated that the P2X7 agonists adenosine-5′-triphosphate (ATP) and 2′(3′)-O-(4-benzoylbenzoyl) ATP induced ethidium+ or YO-PRO-12+ uptake into both cell lines. ATP induced ethidium+ uptake into EOC13 cells in a concentration-dependent manner, with an EC50 of ~130 μM. The P2X7 antagonists Brilliant Blue G, A438079, AZ10606120, and AZ11645373 inhibited ATP-induced cation uptake into EOC13 cells by 75–100%. A cytofluorometric assay demonstrated that P2X7 activation induced ROS formation in EOC13 cells, via a mechanism independent of Ca2+ influx and K+ efflux. Cytofluorometric measurements of Annexin-V binding and 7AAD uptake demonstrated that P2X7 activation induced EOC13 cell death. The ROS scavenger N-acetyl-L-cysteine impaired both P2X7-induced EOC13 ROS formation and cell death, suggesting that ROS mediate P2X7-induced EOC13 death. In conclusion, P2X7 activation induces the uptake of organic cations, ROS formation, and death in EOC13 microglia.
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Cytochalasin D enhances the accumulation of a protease-resistant form of prion protein in ScN2a cells: involvement of PI3 kinase/Akt signalling pathway. Cell Biol Int 2012; 36:1223-31. [PMID: 22985412 DOI: 10.1042/cbi20120329] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The conversion of a host-encoded PrPsen (protease-sensitive cellular prion protein) into a PrPres (protease-resistant pathogenic form) is a key process in the pathogenesis of prion diseases, but the intracellular mechanisms underlying PrPres amplification in prion-infected cells remain elusive. To assess the role of cytoskeletal proteins in the regulation of PrPres amplification, the effects of cytoskeletal disruptors on PrPres accumulation in ScN2a cells that were persistently infected with the scrapie Chandler strain have been examined. Actin microfilament disruption with cytochalasin D enhanced PrPres accumulation in ScN2a cells. In contrast, the microtubule-disrupting agents, colchicine, nocodazole and paclitaxel, had no effect on PrPres accumulation. In addition, a PI3K (phosphoinositide 3-kinase) inhibitor, wortmannin and an Akt kinase inhibitor prevented the cytochalasin D-induced enhancement of PrPres accumulation. Cytochalasin D-induced extension of neurite-like processes might correlate with enhanced accumulation of PrPres. The results suggest that the actin cytoskeleton and PI3K/Akt pathway are involved in the regulation of PrPres accumulation in prion-infected cells.
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Iwamaru Y, Takenouchi T, Murayama Y, Okada H, Imamura M, Shimizu Y, Hashimoto M, Mohri S, Yokoyama T, Kitani H. Anti-prion activity of Brilliant Blue G. PLoS One 2012; 7:e37896. [PMID: 22693582 PMCID: PMC3365075 DOI: 10.1371/journal.pone.0037896] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 04/30/2012] [Indexed: 12/11/2022] Open
Abstract
Background Prion diseases are fatal neurodegenerative disorders with no effective therapy currently available. Accumulating evidence has implicated over-activation of P2X7 ionotropic purinergic receptor (P2X7R) in the progression of neuronal loss in several neurodegenerative diseases. This has led to the speculation that simultaneous blockade of this receptor and prion replication can be an effective therapeutic strategy for prion diseases. We have focused on Brilliant Blue G (BBG), a well-known P2X7R antagonist, possessing a chemical structure expected to confer anti-prion activity and examined its inhibitory effect on the accumulation of pathogenic isoforms of prion protein (PrPres) in a cellular and a mouse model of prion disease in order to determine its therapeutic potential. Principal Findings BBG prevented PrPres accumulation in infected MG20 microglial and N2a neural cells at 50% inhibitory concentrations of 14.6 and 3.2 µM, respectively. Administration of BBG in vivo also reduced PrPres accumulation in the brains of mice with prion disease. However, it did not appear to alleviate the disease progression compared to the vehicle-treated controls, implying a complex role of P2X7R on the neuronal degeneration in prion diseases. Significance These results provide novel insights into the pathophysiology of prion diseases and have important implications for the treatment.
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Affiliation(s)
- Yoshifumi Iwamaru
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Takato Takenouchi
- Animal Immune and Cell Biology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
| | - Yuichi Murayama
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Hiroyuki Okada
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Morikazu Imamura
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Yoshihisa Shimizu
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Makoto Hashimoto
- Division of Sensory and Motor Systems, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo, Japan
| | - Shirou Mohri
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Takashi Yokoyama
- Prion Disease Research Center, National Institute of Animal Health, Tsukuba, Ibaraki, Japan
| | - Hiroshi Kitani
- Animal Immune and Cell Biology Research Unit, National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan
- * E-mail:
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Abstract
Different types of ionotropic P2X purinoceptors are expressed in all major types of neuroglia, where they mediate a variety of physiological and pathological signaling. Cortical astrocytes express specific P2X1/5 heteromeric receptors that are activated by ongoing synaptic transmission and can trigger fast local signaling through elevation in cytoplasmic Ca2+ and Na+ concentrations. Oligodendrocytes express several types of P2X receptors that may control their development and mediate axonal-glial interactions. In microglia, P2X4 and P2X7 receptors regulate numerous events associated with microglial activation, motility, and release of proinflammatory factors.
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Affiliation(s)
- Alexei Verkhratsky
- Faculty of Life Sciences, The University of Manchester, Manchester, UK ; IKERBASQUE, Basque Foundation for Science, Bilbao, Spain ; Department of Neurosciences, University of the Basque Country UPV/EHU, Leioa, Spain
| | - Yuri Pankratov
- School of Life Sciences, University of Warwick, Coventry, UK
| | - Ulyana Lalo
- Faculty of Life Sciences, The University of Manchester, Manchester, UK
| | - Maiken Nedergaard
- Division of Glial Disease and Therapeutics, Center for Translational Neuromedicine, Department of Neurosurgery, University of Rochester Medical Center, Rochester, NY, USA
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Abstract
Microglial cells are the resident macrophages in the central nervous system. These cells of mesodermal/mesenchymal origin migrate into all regions of the central nervous system, disseminate through the brain parenchyma, and acquire a specific ramified morphological phenotype termed "resting microglia." Recent studies indicate that even in the normal brain, microglia have highly motile processes by which they scan their territorial domains. By a large number of signaling pathways they can communicate with macroglial cells and neurons and with cells of the immune system. Likewise, microglial cells express receptors classically described for brain-specific communication such as neurotransmitter receptors and those first discovered as immune cell-specific such as for cytokines. Microglial cells are considered the most susceptible sensors of brain pathology. Upon any detection of signs for brain lesions or nervous system dysfunction, microglial cells undergo a complex, multistage activation process that converts them into the "activated microglial cell." This cell form has the capacity to release a large number of substances that can act detrimental or beneficial for the surrounding cells. Activated microglial cells can migrate to the site of injury, proliferate, and phagocytose cells and cellular compartments.
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Burnstock G, Kennedy C. P2X receptors in health and disease. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2011; 61:333-372. [PMID: 21586364 DOI: 10.1016/b978-0-12-385526-8.00011-4] [Citation(s) in RCA: 142] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Seven P2X receptor subunits have been cloned which form functional homo- and heterotrimers. These are cation-selective channels, equally permeable to Na(+) and K(+) and with significant Ca(2+) permeability. The three-dimensional structure of the P2X receptor is described. The channel pore is formed by the α-helical transmembrane spanning region 2 of each subunit. When ATP binds to a P2X receptor, the pore opens within milliseconds, allowing the cations to flow. P2X receptors are expressed on both central and peripheral neurons, where they are involved in neuromuscular and synaptic neurotransmission and neuromodulation. They are also expressed in most types of nonneuronal cells and mediate a wide range of actions, such as contraction of smooth muscle, secretion, and immunomodulation. Changes in the expression of P2X receptors have been characterized in many pathological conditions of the cardiovascular, gastrointestinal, respiratory, and urinogenital systems and in the brain and special senses. The therapeutic potential of P2X receptor agonists and antagonists is currently being investigated in a range of disorders, including chronic neuropathic and inflammatory pain, depression, cystic fibrosis, dry eye, irritable bowel syndrome, interstitial cystitis, dysfunctional urinary bladder, and cancer.
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Affiliation(s)
- G Burnstock
- Autonomic Neuroscience Centre, University College Medical School, London, United Kingdom
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P2X7 Receptor Signaling Pathway as a Therapeutic Target for Neurodegenerative Diseases. Arch Immunol Ther Exp (Warsz) 2010; 58:91-6. [DOI: 10.1007/s00005-010-0069-y] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Accepted: 11/12/2009] [Indexed: 10/19/2022]
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D'Ambrosi N, Finocchi P, Apolloni S, Cozzolino M, Ferri A, Padovano V, Pietrini G, Carrì MT, Volonté C. The Proinflammatory Action of Microglial P2 Receptors Is Enhanced in SOD1 Models for Amyotrophic Lateral Sclerosis. THE JOURNAL OF IMMUNOLOGY 2009; 183:4648-56. [DOI: 10.4049/jimmunol.0901212] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Takenouchi T, Nakai M, Iwamaru Y, Sugama S, Tsukimoto M, Fujita M, Wei J, Sekigawa A, Sato M, Kojima S, Kitani H, Hashimoto M. The activation of P2X7 receptor impairs lysosomal functions and stimulates the release of autophagolysosomes in microglial cells. THE JOURNAL OF IMMUNOLOGY 2009; 182:2051-62. [PMID: 19201858 DOI: 10.4049/jimmunol.0802577] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recently, autophagy has been associated with the TLR signaling pathway to eliminate intracellular pathogens in the innate immune system. However, it is unknown if other pathways regulate autophagy during the immunologic response. Given the critical role of the purinergic P2X7 receptor (P2X7R) pathway during various immunologic functions (i.e., caspase activation and IL-1beta secretion), the principal objective here was to determine whether the P2X7R pathway may regulate autophagy in immune cells. We observed in both MG6 mouse microglial cells and primary microglia that activation of P2X7R by ATP increases the expression of microtubule-associated protein 1 light chain 3 (LC3)-II, the autophagosomal membrane-associated form of LC3, in an extracellular Ca(2+)-dependent manner. Consistent with this, immunohistochemistry showed extensive formation of LC3-immunopositive dots, and electron microscopy demonstrated accumulation of autophagosomes and autophagolysosomes in ATP-treated cells. Importantly, the up-regulation of LC3-II by P2X7R activation was not affected by autophagy inhibitors, such as 3-methyladenine and PI3K inhibitors. Furthermore, while lysosomal functions were impaired by ATP treatment, autophagolysosomal components were released into the extracellular space. Similarly, a phagocytosis assay using Escherichia coli BioParticles showed that phagosome maturation was impaired in ATP-treated cells and a robust release of LC3-immunopositive phagolysosomes was induced along with a radial extension of microtubule bundles. Taken together, the data suggest a novel mechanism whereby the P2X7R signaling pathway may negatively regulate autophagic flux through the impairment of lysosomal functions, leading to stimulation of a release of autophagolysosomes/phagolysosomes into the extracellular space.
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Affiliation(s)
- Takato Takenouchi
- Transgenic Animal Research Center, National Institute of Agrobiological Sciences, Tsukuba, Japan
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Purinergic signalling in inflammation of the central nervous system. Trends Neurosci 2009; 32:79-87. [PMID: 19135728 DOI: 10.1016/j.tins.2008.11.003] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2008] [Revised: 11/19/2008] [Accepted: 11/19/2008] [Indexed: 12/20/2022]
Abstract
Inflammation is the most fundamental body reaction to noxious stimuli. No vascularized tissue, organ or apparatus is free from this response. Several mediators of inflammation, originating from outside (exogenous) or inside (endogenous) the body, are known. Among the endogenous factors, extracellular nucleotides and nucleosides are attracting interest for their ubiquity and striking ability to modulate diverse immune responses. Until recently, it was doubted that the central nervous system (CNS), reportedly an 'immunoprivileged organ', could be the site of immune reactions. Nowadays, it is acknowledged that inflammation and immunity have a key role in a vast range of CNS diseases. Likewise, it is clear that purinergic signalling profoundly affects neuroinflammation. Here, we provide a brief update of the state of the art in this expanding field.
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Jang B, Kim E, Choi JK, Jin JK, Kim JI, Ishigami A, Maruyama N, Carp RI, Kim YS, Choi EK. Accumulation of citrullinated proteins by up-regulated peptidylarginine deiminase 2 in brains of scrapie-infected mice: a possible role in pathogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1129-42. [PMID: 18787103 DOI: 10.2353/ajpath.2008.080388] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Peptidylarginine deiminases (PADs), which are a group of posttranslational modification enzymes, are involved in protein citrullination (deimination) by the conversion of peptidylarginine to peptidylcitrulline in a calcium concentration-dependent manner. Among the PADs, PAD2 is widely distributed in various tissues and is the only type that is expressed in brain. To elucidate the involvement of protein citrullination by PAD2 in the pathogenesis of brain-specific prion diseases, we examined the profiles of citrullinated proteins using the brains of scrapie-infected mice as a prion disease model. We found that, compared with controls, increased levels of citrullinated proteins of various molecular weights were detected in different brain sections of scrapie-infected mice. In support of this data, expression levels of PAD2 protein as well as its enzyme activity were significantly increased in brain sections of scrapie-infected mice, including hippocampus, brain stem, and striatum. Additionally, the expression levels of PAD2 mRNA were increased during scrapie infection. Moreover, PAD2 immunoreactivity was increased in scrapie-infected brains, with staining detected primarily in reactive astrocytes. Using two-dimensional electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry, various citrullinated proteins were identified in the brains of scrapie-infected mice, including glial fibrillary acidic protein, myelin basic protein, enolases, and aldolases. This study suggests that accumulated citrullinated proteins and abnormal activation of PAD2 may function in the pathogenesis of prion diseases and serve as potential therapeutic targets.
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Affiliation(s)
- Byungki Jang
- Ilsong Institute of Life Science, Hallym University, Anyang, Republic of Korea
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Takenouchi T, Iwamaru Y, Sugama S, Sato M, Hashimoto M, Kitani H. Lysophospholipids and ATP mutually suppress maturation and release of IL-1 beta in mouse microglial cells using a Rho-dependent pathway. THE JOURNAL OF IMMUNOLOGY 2008; 180:7827-39. [PMID: 18523246 DOI: 10.4049/jimmunol.180.12.7827] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The P2X7 receptor (P2X7R), an ATP-gated ion channel, plays essential roles in the release and maturation of IL-1beta in microglial cells in the brain. Previously, we found that lysophosphatidylcholine (LPC) potentiated P2X7R-mediated intracellular signals in microglial cells. In this study, we determined whether the lysophospholipids, i.e., LPC and sphingosylphosphorylcholine (SPC), modulate the ATP-induced release and processing of IL-1beta mediated by P2X7R in mouse MG6 microglial cells. LPC or SPC alone induced the release of precursor (pro-IL-1beta) and mature IL-1beta (mIL-1beta) from LPS-primed MG6 cells, possibly due to lytic functions. However, these lysophospholipids inhibited ATP-induced caspase-1 activation that is usually followed by the release of mIL-1beta. Conversely, ATP inhibited the release of pro-IL-1beta and mIL-1beta induced by LPC/SPC. This suggests that lysophospholipids and ATP mutually suppressed each function to release IL-1beta. P2X7R activation resulted in microtubule reorganization in the MG6 cells that was blocked in the presence of LPC and SPC. LPC/SPC reduced the amount of activated RhoA after stimulation with ATP, implying that these lysophospholipids block ATP-induced microtubule reorganization by interfering with RhoA activation. In addition, the microtubule inhibitor colchicine inhibited ATP-induced release of mIL-1beta similar to that of LPC and SPC. This suggests that the impairment of the microtubule reassembly may be associated with the inhibitory effects of LPC/SPC on ATP-induced mIL-1beta release. Mutual suppression by ATP and LPC/SPC on the maturation of IL-1beta was observed in LPS-primed primary microglia. Collectively, these data suggest opposing functions by lysophospholipids, either proinflammatory or anti-inflammatory, in regard to the maturation and release of IL-1beta from microglial cells.
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Affiliation(s)
- Takato Takenouchi
- Transgenic Animal Research Center, National Institute of Agrobiological Sciences, Tsukuba, Japan
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Burnstock G. Purinergic signalling and disorders of the central nervous system. Nat Rev Drug Discov 2008; 7:575-90. [PMID: 18591979 DOI: 10.1038/nrd2605] [Citation(s) in RCA: 446] [Impact Index Per Article: 27.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Purines have key roles in neurotransmission and neuromodulation, with their effects being mediated by the purine and pyrimidine receptor subfamilies, P1, P2X and P2Y. Recently, purinergic mechanisms and specific receptor subtypes have been shown to be involved in various pathological conditions including brain trauma and ischaemia, neurodegenerative diseases involving neuroimmune and neuroinflammatory reactions, as well as in neuropsychiatric diseases, including depression and schizophrenia. This article reviews the role of purinergic signalling in CNS disorders, highlighting specific purinergic receptor subtypes, most notably A(2A), P2X(4) and P2X(7), that might be therapeutically targeted for the treatment of these conditions.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, Rowland Hill Street, London NW3 2PF, UK.
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