1
|
Menéndez Méndez A, Smith J, Engel T. Neonatal Seizures and Purinergic Signalling. Int J Mol Sci 2020; 21:ijms21217832. [PMID: 33105750 PMCID: PMC7660091 DOI: 10.3390/ijms21217832] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/18/2020] [Accepted: 10/20/2020] [Indexed: 02/07/2023] Open
Abstract
Neonatal seizures are one of the most common comorbidities of neonatal encephalopathy, with seizures aggravating acute injury and clinical outcomes. Current treatment can control early life seizures; however, a high level of pharmacoresistance remains among infants, with increasing evidence suggesting current anti-seizure medication potentiating brain damage. This emphasises the need to develop safer therapeutic strategies with a different mechanism of action. The purinergic system, characterised by the use of adenosine triphosphate and its metabolites as signalling molecules, consists of the membrane-bound P1 and P2 purinoreceptors and proteins to modulate extracellular purine nucleotides and nucleoside levels. Targeting this system is proving successful at treating many disorders and diseases of the central nervous system, including epilepsy. Mounting evidence demonstrates that drugs targeting the purinergic system provide both convulsive and anticonvulsive effects. With components of the purinergic signalling system being widely expressed during brain development, emerging evidence suggests that purinergic signalling contributes to neonatal seizures. In this review, we first provide an overview on neonatal seizure pathology and purinergic signalling during brain development. We then describe in detail recent evidence demonstrating a role for purinergic signalling during neonatal seizures and discuss possible purine-based avenues for seizure suppression in neonates.
Collapse
Affiliation(s)
- Aida Menéndez Méndez
- Department of Physiology and Medical Physics, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland; (A.M.M.); (J.S.)
| | - Jonathon Smith
- Department of Physiology and Medical Physics, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland; (A.M.M.); (J.S.)
- FutureNeuro, Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland
| | - Tobias Engel
- Department of Physiology and Medical Physics, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland; (A.M.M.); (J.S.)
- FutureNeuro, Science Foundation Ireland Research Centre for Chronic and Rare Neurological Diseases, RCSI University of Medicine and Health Sciences, Dublin D02 YN77, Ireland
- Correspondence: ; Tel.: +35-314-025-199
| |
Collapse
|
2
|
Shokoples BG, Paradis P, Schiffrin EL. P2X7 Receptors: An Untapped Target for the Management of Cardiovascular Disease. Arterioscler Thromb Vasc Biol 2020; 41:186-199. [PMID: 32998520 PMCID: PMC7752223 DOI: 10.1161/atvbaha.120.315116] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Chronic low-grade inflammation contributes to the development of several diseases, including cardiovascular disease. Adequate strategies to target inflammation in cardiovascular disease are in their infancy and remain an avenue of great interest. The purinergic receptor P2X7 is a ubiquitously expressed receptor that predominately mediates inflammation and cellular death. P2X7 is a ligand-gated cation channel that is activated in response to high concentrations of extracellular ATP, triggering the assembly and activation of the NLRP3 (nuclear oligomerization domain like receptor family pyrin domain containing 3) inflammasome and subsequent release of proinflammatory cytokines IL (interleukin)-1β and IL-18. Increased P2X7 activation and IL-1β and IL-18 concentrations have been implicated in the development of many cardiovascular conditions including hypertension, atherosclerosis, ischemia/reperfusion injury, and heart failure. P2X7 receptor KO (knockout) mice exhibit a significant attenuation of the inflammatory response, which corresponds with reduced disease severity. P2X7 antagonism blunts blood pressure elevation in hypertension and progression of atherosclerosis in animal models. IL-1β and IL-18 inhibition has shown efficacy in clinical trials reducing major adverse cardiac events, including myocardial infarction, and heart failure. With several P2X7 antagonists available with proven safety margins, P2X7 antagonism could represent an untapped potential for therapeutic intervention in cardiovascular disorders.
Collapse
Affiliation(s)
- Brandon G. Shokoples
- Vascular and Hypertension Research Unit, Lady Davis Institute for Medical Research (B.G.S., P.P., E.L.S.), Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Pierre Paradis
- Vascular and Hypertension Research Unit, Lady Davis Institute for Medical Research (B.G.S., P.P., E.L.S.), Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| | - Ernesto L. Schiffrin
- Vascular and Hypertension Research Unit, Lady Davis Institute for Medical Research (B.G.S., P.P., E.L.S.), Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, Quebec, Canada
- Department of Medicine (E.L.S.), Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montreal, Quebec, Canada
| |
Collapse
|
3
|
Rodrigues RJ, Marques JM, Cunha RA. Purinergic signalling and brain development. Semin Cell Dev Biol 2019; 95:34-41. [DOI: 10.1016/j.semcdb.2018.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 12/01/2018] [Accepted: 12/01/2018] [Indexed: 11/27/2022]
|
4
|
Blanchard C, Boué-Grabot E, Massé K. Comparative Embryonic Spatio-Temporal Expression Profile Map of the Xenopus P2X Receptor Family. Front Cell Neurosci 2019; 13:340. [PMID: 31402854 PMCID: PMC6676501 DOI: 10.3389/fncel.2019.00340] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Accepted: 07/10/2019] [Indexed: 01/27/2023] Open
Abstract
P2X receptors are ATP-gated cations channels formed by the homo or hetero-trimeric association from the seven cloned subunits (P2X1-7). P2X receptors are widely distributed in different organs and cell types throughout the body including the nervous system and are involved in a large variety of physiological but also pathological processes in adult mammals. However, their expression and function during embryogenesis remain poorly understood. Here, we report the cloning and the comparative expression map establishment of the entire P2X subunit family in the clawed frog Xenopus. Orthologous sequences for 6 mammalian P2X subunits were identified in both X. laevis and X. tropicalis, but not for P2X3 subunit, suggesting a potential loss of this subunit in the Pipidae family. Three of these genes (p2rx1, p2rx2, and p2rx5) exist as homeologs in the pseudoallotetraploid X. laevis, making a total of 9 subunits in this species. Phylogenetic analyses demonstrate the high level of conservation of these receptors between amphibian and other vertebrate species. RT-PCR revealed that all subunits are expressed during the development although zygotic p2rx6 and p2rx7 transcripts are mainly detected at late organogenesis stages. Whole mount in situ hybridization shows that each subunit displays a specific spatio-temporal expression profile and that these subunits can therefore be grouped into two groups, based on their expression or not in the developing nervous system. Overlapping expression in the central and peripheral nervous system and in the sensory organs suggests potential heteromerization and/or redundant functions of P2X subunits in Xenopus embryos. The developmental expression of the p2rx subunit family during early phases of embryogenesis indicates that these subunits may have distinct roles during vertebrate development, especially embryonic neurogenesis.
Collapse
Affiliation(s)
- Camille Blanchard
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
- CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
| | - Eric Boué-Grabot
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
- CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
| | - Karine Massé
- Université de Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
- CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France
| |
Collapse
|
5
|
Guerra Martinez C. P2X7 receptor in cardiovascular disease: The heart side. Clin Exp Pharmacol Physiol 2019; 46:513-526. [PMID: 30834550 DOI: 10.1111/1440-1681.13079] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 02/21/2019] [Accepted: 02/28/2019] [Indexed: 01/10/2023]
Abstract
The P2X7 receptor is a ligand-gated purinergic receptor activated by extracellular ATP. The receptor is highly expressed in immune cells and in the brain, and, upon activation, the P2X7 receptor allows a cation flux, leading to the distinct activation of intracellular signalling pathways as the secretion of pro-inflammatory cytokines, and modulation of cell survival. Through these molecular mechanisms, P2X7 is known to play important roles in physiology and pathophysiology of a wide spectrum of diseases, including cancer, inflammatory diseases, neurological, respiratory and more recently cardiovascular diseases. Recent studies demonstrated that the P2X7 could modulate the assembly of the NLRP3 inflammasome, leading to the secretion of pro-inflammatory factors and worsen the cardiac disease phenotypes. This review discusses the critical molecular function of P2X7 in the modulation of the onset, progression and resolution of cardiovascular diseases and analyses the putative future use of P2X7-based therapies that modulate the IL-1β secretion arm and direct P2X7 antagonists.
Collapse
Affiliation(s)
- Camila Guerra Martinez
- Department of Microbial Pathogenesis and Immunology, Texas A&M University, College Station, Texas
| |
Collapse
|
6
|
Leeson HC, Kasherman MA, Chan-Ling T, Lovelace MD, Brownlie JC, Toppinen KM, Gu BJ, Weible MW. P2X7 Receptors Regulate Phagocytosis and Proliferation in Adult Hippocampal and SVZ Neural Progenitor Cells: Implications for Inflammation in Neurogenesis. Stem Cells 2018; 36:1764-1777. [PMID: 30068016 PMCID: PMC6635745 DOI: 10.1002/stem.2894] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Revised: 07/04/2018] [Accepted: 07/06/2018] [Indexed: 12/26/2022]
Abstract
Identifying the signaling mechanisms that regulate adult neurogenesis is essential to understanding how the brain may respond to neuro‐inflammatory events. P2X7 receptors can regulate pro‐inflammatory responses, and in addition to their role as cation channels they can trigger cell death and mediate phagocytosis. How P2X7 receptors may regulate adult neurogenesis is currently unclear. Here, neural progenitor cells (NPCs) derived from adult murine hippocampal subgranular (SGZ) and cerebral subventricular (SVZ) zones were utilized to characterize the roles of P2X7 in adult neurogenesis, and assess the effects of high extracellular ATP, characteristic of inflammation, on NPCs. Immunocytochemistry found NPCs in vivo and in vitro expressed P2X7, and the activity of P2X7 in culture was demonstrated using calcium influx and pore formation assays. Live cell and confocal microscopy, in conjunction with flow cytometry, revealed P2X7+ NPCs were able to phagocytose fluorescent beads, and this was inhibited by ATP, indicative of P2X7 involvement. Furthermore, P2X7 receptors were activated with ATP or BzATP, and 5‐ethynyl‐2′‐deoxyuridine (EdU) used to observe a dose‐dependent decrease in NPC proliferation. A role for P2X7 in decreased NPC proliferation was confirmed using chemical inhibition and NPCs from P2X7−/− mice. Together, these data present three distinct roles for P2X7 during adult neurogenesis, depending on extracellular ATP concentrations: (a) P2X7 receptors can form transmembrane pores leading to cell death, (b) P2X7 receptors can regulate rates of proliferation, likely via calcium signaling, and (c) P2X7 can function as scavenger receptors in the absence of ATP, allowing NPCs to phagocytose apoptotic NPCs during neurogenesis. stem cells2018;36:1764–1777
Collapse
Affiliation(s)
- Hannah C Leeson
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Maria A Kasherman
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Tailoi Chan-Ling
- Discipline of Anatomy and Histology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Bosch Institute, The University of Sydney, Sydney, New South Wales, Australia
| | - Michael D Lovelace
- Discipline of Anatomy and Histology, School of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia.,Applied Neurosciences Program, Peter Duncan Neurosciences Research Unit, St. Vincent's Centre for Applied Medical Research, Sydney, New South Wales, Australia.,St. Vincent's Clinical School, University of New South Wales Medicine, UNSW, Sydney, Sydney, New South Wales, Australia
| | - Jeremy C Brownlie
- School of Environment and Science, Griffith University, Brisbane, Queensland, Australia
| | - Kelly M Toppinen
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia
| | - Ben J Gu
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Michael W Weible
- Griffith Institute for Drug Discovery, Griffith University, Brisbane, Queensland, Australia.,Bosch Institute, The University of Sydney, Sydney, New South Wales, Australia.,School of Environment and Science, Griffith University, Brisbane, Queensland, Australia
| |
Collapse
|
7
|
Fry AE, Fawcett KA, Zelnik N, Yuan H, Thompson BAN, Shemer-Meiri L, Cushion TD, Mugalaasi H, Sims D, Stoodley N, Chung SK, Rees MI, Patel CV, Brueton LA, Layet V, Giuliano F, Kerr MP, Banne E, Meiner V, Lerman-Sagie T, Helbig KL, Kofman LH, Knight KM, Chen W, Kannan V, Hu C, Kusumoto H, Zhang J, Swanger SA, Shaulsky GH, Mirzaa GM, Muir AM, Mefford HC, Dobyns WB, Mackenzie AB, Mullins JGL, Lemke JR, Bahi-Buisson N, Traynelis SF, Iago HF, Pilz DT. De novo mutations in GRIN1 cause extensive bilateral polymicrogyria. Brain 2018; 141:698-712. [PMID: 29365063 PMCID: PMC5837214 DOI: 10.1093/brain/awx358] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 10/17/2017] [Accepted: 11/14/2017] [Indexed: 11/14/2022] Open
Abstract
Polymicrogyria is a malformation of cortical development. The aetiology of polymicrogyria remains poorly understood. Using whole-exome sequencing we found de novo heterozygous missense GRIN1 mutations in 2 of 57 parent-offspring trios with polymicrogyria. We found nine further de novo missense GRIN1 mutations in additional cortical malformation patients. Shared features in the patients were extensive bilateral polymicrogyria associated with severe developmental delay, postnatal microcephaly, cortical visual impairment and intractable epilepsy. GRIN1 encodes GluN1, the essential subunit of the N-methyl-d-aspartate receptor. The polymicrogyria-associated GRIN1 mutations tended to cluster in the S2 region (part of the ligand-binding domain of GluN1) or the adjacent M3 helix. These regions are rarely mutated in the normal population or in GRIN1 patients without polymicrogyria. Using two-electrode and whole-cell voltage-clamp analysis, we showed that the polymicrogyria-associated GRIN1 mutations significantly alter the in vitro activity of the receptor. Three of the mutations increased agonist potency while one reduced proton inhibition of the receptor. These results are striking because previous GRIN1 mutations have generally caused loss of function, and because N-methyl-d-aspartate receptor agonists have been used for many years to generate animal models of polymicrogyria. Overall, our results expand the phenotypic spectrum associated with GRIN1 mutations and highlight the important role of N-methyl-d-aspartate receptor signalling in the pathogenesis of polymicrogyria.
Collapse
Affiliation(s)
- Andrew E Fry
- Institute of Medical Genetics, University Hospital of Wales, Cardiff CF14 4XW, UK
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
| | - Katherine A Fawcett
- MRC Computational Genomics Analysis and Training Programme (CGAT), MRC Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK
| | - Nathanel Zelnik
- Pediatric Neurology Unit, Carmel Medical Center, Haifa, Israel
- Bruce and Ruth Rappaport Faculty of Medicine, Technion, Haifa, Israel
| | - Hongjie Yuan
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Center for Functional Evaluation of Rare Variants (CFERV), Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Belinda A N Thompson
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | | | - Thomas D Cushion
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
| | - Hood Mugalaasi
- Institute of Medical Genetics, University Hospital of Wales, Cardiff CF14 4XW, UK
| | - David Sims
- MRC Computational Genomics Analysis and Training Programme (CGAT), MRC Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK
| | - Neil Stoodley
- Department of Neuroradiology, North Bristol NHS Trust, Frenchay Hospital, Bristol BS16 1LE, UK
| | - Seo-Kyung Chung
- Neurology and Molecular Neuroscience Research, Institute of Life Science, Swansea University Medical School, Swansea University, Swansea SA2 8PP, UK
| | - Mark I Rees
- Neurology and Molecular Neuroscience Research, Institute of Life Science, Swansea University Medical School, Swansea University, Swansea SA2 8PP, UK
| | - Chirag V Patel
- Genetic Health Queensland, Royal Brisbane and Women’s Hospital Campus, Herston, Brisbane, Queensland 4029, Australia
| | - Louise A Brueton
- West Midlands Regional Genetics Service, Clinical Genetics Unit, Birmingham Women’s Hospital, Birmingham B15 2TG, UK
| | - Valérie Layet
- Service de Génétique Médicale, Groupe Hospitalier du Havre, Hôpital Jacques Monod, Le Havre, France
| | - Fabienne Giuliano
- Service de Génétique Médicale, Centre Hospitalier Universitaire de Nice, Nice, France
| | - Michael P Kerr
- MRC Centre for Neuropsychiatric Genetics and Genomics, Institute of Psychological Medicine and Clinical Neurosciences, Cardiff University, Cardiff CF24 4HQ, UK
- Learning Disabilities Directorate, Abertawe Bro Morgannwg University NHS Trust, Treseder Way, Caerau, Cardiff CF5 5WF, UK
| | - Ehud Banne
- Clinical Genetics Institute, Kaplan Medical Centre, Rehovot, Israel
| | - Vardiella Meiner
- Department of Genetics and Metabolic Diseases, Hadassah-Hebrew University Hospital, Jerusalem, Israel
| | - Tally Lerman-Sagie
- Pediatric Neurology Unit, Wolfson Medical Centre, Holon, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - Katherine L Helbig
- Division of Neurology, Children’s Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Laura H Kofman
- Kaiser Permanente Mid-Atlantic States, McLean, VA 22102, USA
| | | | - Wenjuan Chen
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Neurology, Xiangya Hospital, Central South University, Changsha 410013, China
| | - Varun Kannan
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Chun Hu
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Hirofumi Kusumoto
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jin Zhang
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Department of Neurology, the First Hospital of Shanxi Medical University, Taiyuan, 030001, China
| | - Sharon A Swanger
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Gil H Shaulsky
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Ghayda M Mirzaa
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98195, USA
| | - Alison M Muir
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - Heather C Mefford
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
| | - William B Dobyns
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, WA 98195, USA
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA 98195, USA
- Department of Neurology, University of Washington, Seattle, WA 98195, USA
| | - Amanda B Mackenzie
- Department of Pharmacy and Pharmacology, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Jonathan G L Mullins
- Genome and Structural Bioinformatics Group, Institute of Life Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Johannes R Lemke
- Institute of Human Genetics, University Medical Center Leipzig, Leipzig 04103, Germany
| | - Nadia Bahi-Buisson
- Imagine Institute, INSERM UMR-1163, Laboratory Genetics and Embryology of Congenital Malformations, Paris Descartes University, Paris, France
| | - Stephen F Traynelis
- Department of Pharmacology and Chemical Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
- Center for Functional Evaluation of Rare Variants (CFERV), Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Heledd F Iago
- Genome and Structural Bioinformatics Group, Institute of Life Science, Swansea University, Singleton Park, Swansea SA2 8PP, UK
| | - Daniela T Pilz
- Division of Cancer and Genetics, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK
- West of Scotland Clinical Genetics Service, Queen Elizabeth University Hospital, Glasgow G51 4TF, UK
| |
Collapse
|
8
|
Puddighinu G, D'Amario D, Foglio E, Manchi M, Siracusano A, Pontemezzo E, Cordella M, Facchiano F, Pellegrini L, Mangoni A, Tafani M, Crea F, Germani A, Russo MA, Limana F. Molecular mechanisms of cardioprotective effects mediated by transplanted cardiac ckit + cells through the activation of an inflammatory hypoxia-dependent reparative response. Oncotarget 2017; 9:937-957. [PMID: 29416668 PMCID: PMC5787525 DOI: 10.18632/oncotarget.22946] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Accepted: 11/12/2017] [Indexed: 12/16/2022] Open
Abstract
The regenerative effects of cardiac ckit+ stem cells (ckit+CSCs) in acute myocardial infarction (MI) have been studied extensively, but how these cells exert a protective effect on cardiomyocytes is not well known. Growing evidences suggest that in adult stem cells injury triggers inflammatory signaling pathways which control tissue repair and regeneration. Aim of the present study was to determine the mechanisms underlying the cardioprotective effects of ckit+CSCs following transplantation in a murine model of MI. Following isolation and in vitro expansion, cardiac ckit+CSCs were subjected to normoxic and hypoxic conditions and assessed at different time points. These cells adapted to hypoxia as showed by the activation of HIF-1α and the expression of a number of genes, such as VEGF, GLUT1, EPO, HKII and, importantly, of alarmin receptors, such as RAGE, P2X7R, TLR2 and TLR4. Activation of these receptors determined an NFkB-dependent inflammatory and reparative gene response (IRR). Importantly, hypoxic ckit+CSCs increased the secretion of the survival growth factors IGF-1 and HGF. To verify whether activation of the IRR in a hypoxic microenvironment could exert a beneficial effect in vivo, autologous ckit+CSCs were transplanted into mouse heart following MI. Interestingly, transplantation of ckit+CSCs lowered apoptotic rates and induced autophagy in the peri-infarct area; further, it reduced hypertrophy and fibrosis and, most importantly, improved cardiac function. ckit+CSCs are able to adapt to a hypoxic environment and activate an inflammatory and reparative response that could account, at least in part, for a protective effect on stressed cardiomyocytes following transplantation in the infarcted heart.
Collapse
Affiliation(s)
- Giovanni Puddighinu
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Domenico D'Amario
- Department of Cardiovascular Sciences, Catholic University of The Sacred Heart, Rome, Italy
| | - Eleonora Foglio
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Melissa Manchi
- Department of Cardiovascular Sciences, Catholic University of The Sacred Heart, Rome, Italy
| | - Andrea Siracusano
- Department of Cardiovascular Sciences, Catholic University of The Sacred Heart, Rome, Italy
| | - Elena Pontemezzo
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Martina Cordella
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - Francesco Facchiano
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Rome, Italy
| | - Laura Pellegrini
- Department of Neurorehabilitation Sciences, Casa Cura Policlinico (CCP), Milan, Italy
| | - Antonella Mangoni
- Department of Pathological Anatomy, Catholic University of The Sacred Heart, Rome, Italy
| | - Marco Tafani
- Department of Experimental Medicine, Sapienza University of Rome, Rome, Italy
| | - Filippo Crea
- Department of Cardiovascular Sciences, Catholic University of The Sacred Heart, Rome, Italy
| | - Antonia Germani
- Laboratory of Vascular Pathology, Istituto Dermopatico dell'Immacolata, IDI-IRCCS, Fondazione Luigi Maria Monti, Rome, Italy
| | - Matteo Antonio Russo
- IRCCS San Raffaele Pisana, Rome, Italy.,MEBIC Consortium, San Raffaele Roma Open University, Rome, Italy
| | - Federica Limana
- IRCCS San Raffaele Pisana, Rome, Italy.,San Raffaele Roma Open University, Rome, Italy
| |
Collapse
|
9
|
Neuronal P2X7 Receptor: Involvement in Neuronal Physiology and Pathology. J Neurosci 2017; 37:7063-7072. [PMID: 28747389 DOI: 10.1523/jneurosci.3104-16.2017] [Citation(s) in RCA: 106] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Revised: 05/12/2017] [Accepted: 05/16/2017] [Indexed: 12/28/2022] Open
Abstract
The proposed presence of P2X7 receptor (P2X7R) in neurons has been the source of some contention. Initial studies suggested an absence of P2X7R mRNA in neurons, and the apparent nonspecificity of the antibodies used to identify P2X7R raised further doubts. However, subsequent studies using new pharmacological and biomolecular tools provided conclusive evidence supporting the existence of functional P2X7Rs in neurons. The P2X7 receptor has since been shown to play a leading role in multiple aspects of neuronal physiology, including axonal elongation and branching and neurotransmitter release. P2X7R has also been implicated in neuronal pathologies, in which it may influence neuronal survival. Together, this body of research suggests that P2X7R may constitute an important therapeutic target for a variety of neurological disorders.
Collapse
|
10
|
Lin C, Zhang J. Inflammasomes in Inflammation-Induced Cancer. Front Immunol 2017; 8:271. [PMID: 28360909 PMCID: PMC5350111 DOI: 10.3389/fimmu.2017.00271] [Citation(s) in RCA: 70] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 02/24/2017] [Indexed: 12/19/2022] Open
Abstract
The inflammasome is an important multiprotein complex that functions during inflammatory immune responses. The activation of inflammasome will lead to the autoactivation of caspase-1 and subsequent cleavage of proIL-1β and proIL-18, which are key sources of inflammatory manifestations. Recently, the roles of inflammasomes in cancers have been extensively explored, especially in inflammation-induced cancers. In different and specific contexts, inflammasomes exhibit distinct and even contrasting effects in cancer development. In some cases, inflammasomes initiate carcinogenesis through the extrinsic pathway and maintain the malignant cancer microenvironment through the intrinsic pathway. On the contrary, inflammasomes also exert anticancer effects by specialized programmed cell death called pyroptosis and immune regulatory functions. The phases and compartments in which inflammasomes are activated strongly influence the final immune effects. We systemically summarize the functions of inflammasomes in inflammation-induced cancers, especially in gastrointestinal and skin cancers. Besides, information about the current therapeutic use of inflammasome-related products and potential future developing directions are also introduced.
Collapse
Affiliation(s)
- Chu Lin
- Department of Immunology, School of Basic Medical Sciences, Key Laboratory of Medical Immunology, National Health and Family Planning Commission of the People's Republic of China, Peking University Health Science Center , Beijing , China
| | - Jun Zhang
- Department of Immunology, School of Basic Medical Sciences, Key Laboratory of Medical Immunology, National Health and Family Planning Commission of the People's Republic of China, Peking University Health Science Center , Beijing , China
| |
Collapse
|
11
|
Di Virgilio F, Adinolfi E. Extracellular purines, purinergic receptors and tumor growth. Oncogene 2016; 36:293-303. [PMID: 27321181 PMCID: PMC5269532 DOI: 10.1038/onc.2016.206] [Citation(s) in RCA: 358] [Impact Index Per Article: 44.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 05/02/2016] [Accepted: 05/02/2016] [Indexed: 12/13/2022]
Abstract
Virtually, all tumor cells as well as all immune cells express plasma membrane receptors for extracellular nucleosides (adenosine) and nucleotides (ATP, ADP, UTP, UDP and sugar UDP). The tumor microenvironment is characterized by an unusually high concentration of ATP and adenosine. Adenosine is a major determinant of the immunosuppressive tumor milieu. Sequential hydrolysis of extracellular ATP catalyzed by CD39 and CD73 is the main pathway for the generation of adenosine in the tumor interstitium. Extracellular ATP and adenosine mold both host and tumor responses. Depending on the specific receptor activated, extracellular purines mediate immunosuppression or immunostimulation on the host side, and growth stimulation or cytotoxicity on the tumor side. Recent progress in this field is providing the key to decode this complex scenario and to lay the basis to harness the potential benefits for therapy. Preclinical data show that targeting the adenosine-generating pathway (that is, CD73) or adenosinergic receptors (that is, A2A) relieves immunosuppresion and potently inhibits tumor growth. On the other hand, growth of experimental tumors is strongly inhibited by targeting the P2X7 ATP-selective receptor of cancer and immune cells. This review summarizes the recent data on the role played by extracellular purines (purinergic signaling) in host-tumor interaction and highlights novel therapeutic options stemming from recent advances in this field.
Collapse
Affiliation(s)
- F Di Virgilio
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, University of Ferrara, Ferrara, Italy
| | - E Adinolfi
- Department of Morphology, Surgery and Experimental Medicine, Section of Pathology, Oncology and Experimental Biology, University of Ferrara, Ferrara, Italy
| |
Collapse
|
12
|
P2 receptors in cancer progression and metastatic spreading. Curr Opin Pharmacol 2016; 29:17-25. [PMID: 27262778 DOI: 10.1016/j.coph.2016.05.001] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 04/27/2016] [Accepted: 05/08/2016] [Indexed: 10/21/2022]
Abstract
Tumor microenvironment is nucleoside and nucleotide rich. Adenosine is a key determinant of the highly immunosuppressive tumor interstitium. Extracellular ATP also affects anti-tumor immunity, albeit its effects on host-tumor interaction are incompletely understood. We give here an overview of recent literature covering the role of nucleotide-selective (P2) plasma membrane receptors in tumor growth and progression. P2 receptors are expressed on both host and cancer cells, where depending on the receptor subtype, the inflammatory infiltrate and the tumor cell type they may drive an anti-tumor response or promote tumor progression. It is anticipated that knowledge of the pharmacology, biochemistry and functional activity of the P2 receptors will allow a better understanding of host-tumor interaction and the development of innovative anti-cancer therapy.
Collapse
|
13
|
Menkova-Garnier I, Hocini H, Foucat E, Tisserand P, Bourdery L, Delaugerre C, Benne C, Lévy Y, Lelièvre JD. P2X7 Receptor Inhibition Improves CD34 T-Cell Differentiation in HIV-Infected Immunological Nonresponders on c-ART. PLoS Pathog 2016; 12:e1005571. [PMID: 27082982 PMCID: PMC4833302 DOI: 10.1371/journal.ppat.1005571] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Accepted: 03/22/2016] [Indexed: 11/18/2022] Open
Abstract
Peripheral CD4+ T-cell levels are not fully restored in a significant proportion of HIV+ individuals displaying long-term viral suppression on c-ART. These immunological nonresponders (INRs) have a higher risk of developing AIDS and non-AIDS events and a lower life expectancy than the general population, but the underlying mechanisms are not fully understood. We used an in vitro system to analyze the T- and B-cell potential of CD34+ hematopoietic progenitor cells. Comparisons of INRs with matched HIV+ patients with high CD4+ T-cell counts (immune responders (IRs)) revealed an impairment of the generation of T-cell progenitors, but not of B-cell progenitors, in INRs. This impairment resulted in the presence of smaller numbers of recent thymic emigrants (RTE) in the blood and lower peripheral CD4+ T-cell counts. We investigated the molecular pathways involved in lymphopoiesis, focusing particularly on T-cell fate specification (Notch pathway), survival (IL7R-IL7 axis) and death (Fas, P2X7, CD39/CD73). P2X7 expression was abnormally strong and there was no CD73 mRNA in the CD34+ cells of INRs, highlighting a role for the ATP pathway. This was confirmed by the demonstration that in vitro inhibition of the P2X7-mediated pathway restored the T-cell potential of CD34+ cells from INRs. Moreover, transcriptomic analysis revealed major differences in cell survival and death pathways between CD34+ cells from INRs and those from IRs. These findings pave the way for the use of complementary immunotherapies, such as P2X7 antagonists, to restore T-cell lymphopoiesis in INRs.
Collapse
Affiliation(s)
- Inna Menkova-Garnier
- INSERM U955, Institut Mondor de Recherche Biomédicale, Créteil, France.,Université Paris Est Créteil, Faculté de Médecine, Créteil, France.,Vaccine Research Institute, Créteil, France
| | - Hakim Hocini
- INSERM U955, Institut Mondor de Recherche Biomédicale, Créteil, France.,Vaccine Research Institute, Créteil, France
| | - Emile Foucat
- Université Paris Est Créteil, Faculté de Médecine, Créteil, France
| | - Pascaline Tisserand
- INSERM U955, Institut Mondor de Recherche Biomédicale, Créteil, France.,Vaccine Research Institute, Créteil, France
| | - Laure Bourdery
- Université Paris Est Créteil, Faculté de Médecine, Créteil, France
| | | | - Clarisse Benne
- INSERM U955, Institut Mondor de Recherche Biomédicale, Créteil, France.,Université Paris Est Créteil, Faculté de Médecine, Créteil, France
| | - Yves Lévy
- INSERM U955, Institut Mondor de Recherche Biomédicale, Créteil, France.,Université Paris Est Créteil, Faculté de Médecine, Créteil, France.,Vaccine Research Institute, Créteil, France.,Groupe Hospitalier Henri-Mondor Albert-Chenevier, Créteil, France
| | - Jean-Daniel Lelièvre
- INSERM U955, Institut Mondor de Recherche Biomédicale, Créteil, France.,Université Paris Est Créteil, Faculté de Médecine, Créteil, France.,Vaccine Research Institute, Créteil, France.,Groupe Hospitalier Henri-Mondor Albert-Chenevier, Créteil, France
| |
Collapse
|
14
|
Cruz LN, Wu Y, Ulrich H, Craig AG, Garcia CRS. Tumor necrosis factor reduces Plasmodium falciparum growth and activates calcium signaling in human malaria parasites. Biochim Biophys Acta Gen Subj 2016; 1860:1489-97. [PMID: 27080559 PMCID: PMC4876768 DOI: 10.1016/j.bbagen.2016.04.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Revised: 03/08/2016] [Accepted: 04/04/2016] [Indexed: 12/29/2022]
Abstract
Background Plasmodium has a complex biology including the ability to interact with host signals modulating their function through cellular machinery. Tumor necrosis factor (TNF) elicits diverse cellular responses including effects in malarial pathology and increased infected erythrocyte cytoadherence. As TNF levels are raised during Plasmodium falciparum infection we have investigated whether it has an effect on the parasite asexual stage. Methods Flow cytometry, spectrofluorimetric determinations, confocal microscopy and PCR real time quantifications were employed for characterizing TNF induced effects and membrane integrity verified by wheat germ agglutinin staining. Results TNF is able to decrease intracellular parasitemia, involving calcium as a second messenger of the pathway. Parasites incubated for 48 h with TNF showed reduced erythrocyte invasion. Thus, TNF induced rises in intracellular calcium concentration, which were blocked by prior addition of the purinergic receptor agonists KN62 and A438079, or interfering with intra- or extracellular calcium release by thapsigargin or EGTA (ethylene glycol tetraacetic acid). Importantly, expression of PfPCNA1 which encodes the Plasmodium falciparum Proliferating-Cell Nuclear Antigen 1, decreased after P. falciparum treatment of TNF (tumor necrosis factor) or 6-Bnz cAMP (N6-benzoyladenosine-3′,5′-cyclic monophosphate sodium salt). Conclusions This is potentially interesting data showing the relevance of calcium in downregulating a gene involved in cellular proliferation, triggered by TNF. General significance The data show that Plasmodium may subvert the immunological system and use TNF for the control of its proliferation within the vertebrate host. TNF is able to decrease parasitemia in P. falciparum‐infected RBCs. TNF induced rises in intracellular calcium concentration, which were blocked by the purinergic receptor agonists KN62 and A438079. Interfering with intra‐ or extracellular calcium release by thapsigargin or EGTA also block TNF‐induce calcium release in P. falciparum. Expression of the P. falciparum Proliferating‐Cell Nuclear Antigen 1 (PfPCNA1) decreased after P. falciparum treatment with TNF or 6‐Bnz cAMP. The data show that Plasmodium may subvert the immunological system and use TNF for the control of its proliferation within the vertebrate host.
Collapse
Affiliation(s)
- Laura N Cruz
- Department of Physiology, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, travessa 14, n321, CEP 05508-900 São Paulo, SP, Brazil
| | - Yang Wu
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Henning Ulrich
- Department of Biochemistry, Instituto de Química, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Alister G Craig
- Department of Parasitology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Célia R S Garcia
- Department of Physiology, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, travessa 14, n321, CEP 05508-900 São Paulo, SP, Brazil.
| |
Collapse
|
15
|
Burnstock G, Dale N. Purinergic signalling during development and ageing. Purinergic Signal 2015; 11:277-305. [PMID: 25989750 PMCID: PMC4529855 DOI: 10.1007/s11302-015-9452-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 04/23/2015] [Indexed: 01/28/2023] Open
Abstract
Extracellular purines and pyrimidines play major roles during embryogenesis, organogenesis, postnatal development and ageing in vertebrates, including humans. Pluripotent stem cells can differentiate into three primary germ layers of the embryo but may also be involved in plasticity and repair of the adult brain. These cells express the molecular components necessary for purinergic signalling, and their developmental fates can be manipulated via this signalling pathway. Functional P1, P2Y and P2X receptor subtypes and ectonucleotidases are involved in the development of different organ systems, including heart, blood vessels, skeletal muscle, urinary bladder, central and peripheral neurons, retina, inner ear, gut, lung and vas deferens. The importance of purinergic signalling in the ageing process is suggested by changes in expression of A1 and A2 receptors in old rat brains and reduction of P2X receptor expression in ageing mouse brain. By contrast, in the periphery, increases in expression of P2X3 and P2X4 receptors are seen in bladder and pancreas.
Collapse
Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
| | | |
Collapse
|
16
|
Ferreira L, Pereira L, Faria R. Fluorescent dyes as a reliable tool in P2X7 receptor-associated pore studies. J Bioenerg Biomembr 2015; 47:283-307. [PMID: 26076670 DOI: 10.1007/s10863-015-9613-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 05/27/2015] [Indexed: 01/09/2023]
Abstract
Since the nineteenth century, a great amount of different biological structures and processes have been assessed by fluorescent dyes. Along with the uses of these compounds as vital and histological dyes, some fluorescent dyes have become valuable tools for the study of the pore phenomenon in plasma membranes. Some ion channels capable of forming large conductance channels, such as P2X7, TRPV1, VDAC-1 and the maxi-anion channels transiently alter the plasma membrane permeability, producing pores, which permit the passage of molecules of up to 1,000 Da. In this review, we discuss the uses of the fluorescent dyes chosen in diverse studies of this topic up to now.
Collapse
Affiliation(s)
- Leonardo Ferreira
- Laboratory of Cellular Communication, Oswaldo Cruz Foundation, Av. Brazil 4365, pavilion 108, room 28B Manguinhos, Rio de Janeiro, Brazil, CEP 21040-360,
| | | | | |
Collapse
|
17
|
Wang H, Hong LJ, Huang JY, Jiang Q, Tao RR, Tan C, Lu NN, Wang CK, Ahmed MM, Lu YM, Liu ZR, Shi WX, Lai EY, Wilcox CS, Han F. P2RX7 sensitizes Mac-1/ICAM-1-dependent leukocyte-endothelial adhesion and promotes neurovascular injury during septic encephalopathy. Cell Res 2015; 25:674-90. [PMID: 25998681 PMCID: PMC4456628 DOI: 10.1038/cr.2015.61] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2014] [Revised: 02/10/2015] [Accepted: 03/12/2015] [Indexed: 12/15/2022] Open
Abstract
Septic encephalopathy (SE) is a critical factor determining sepsis mortality. Vascular inflammation is known to be involved in SE, but the molecular events that lead to the development of encephalopathy remain unclear. Using time-lapse in vivo two-photon laser scanning microscopy, we provide the first direct evidence that cecal ligation and puncture in septic mice induces microglial trafficking to sites adjacent to leukocyte adhesion on inflamed cerebral microvessels. Our data further demonstrate that septic injury increased the chemokine CXCL1 level in brain endothelial cells by activating endothelial P2RX7 and eventually enhanced the binding of Mac-1 (CD11b/CD18)-expressing leukocytes to endothelial ICAM-1. In turn, leukocyte adhesion upregulated endothelial CX3CL1, thereby triggering microglia trafficking to the injured site. The sepsis-induced increase in endothelial CX3CL1 was abolished in CD18 hypomorphic mutant mice. Inhibition of the P2RX7 pathway not only decreased endothelial ICAM-1 expression and leukocyte adhesion but also prevented microglia overactivation, reduced brain injury, and consequently doubled the early survival of septic mice. These results demonstrate the role of the P2RX7 pathway in linking neurovascular inflammation to brain damage in vivo and provide a rationale for targeting endothelial P2RX7 for neurovascular protection during SE.
Collapse
Affiliation(s)
- Huan Wang
- 1] Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China [2] Key Laboratory of Carbohydrate and Lipid Metabolism Research, College of Life Science and Technology, Dalian University, Dalian, Liaoning 116622, China
| | - Ling-Juan Hong
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ji-Yun Huang
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Quan Jiang
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Rong-Rong Tao
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Chao Tan
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Nan-Nan Lu
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Cheng-Kun Wang
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Muhammad M Ahmed
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ying-Mei Lu
- School of Medicine, Zhejiang University City College, Hangzhou, Zhejiang 310015, China
| | - Zhi-Rong Liu
- Department of Neurology, Second Affiliated Hospital of Zhejiang University, School of Medicine, Hangzhou, Zhejiang 310009, China
| | - Wei-Xing Shi
- Department of Basic Sciences, Loma Linda University Health Schools of Medicine, Pharmacy, and Behavioral Health, Loma Linda, CA 92350, USA
| | - En-Yin Lai
- Department of Physiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Christopher S Wilcox
- Hypertension, Kidney, and Vascular Research Center, Georgetown University Medical Center, Washington DC 20007, USA
| | - Feng Han
- Institute of Pharmacology and Toxicology, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, China
| |
Collapse
|
18
|
Fang J, Chen X, Wang S, Xie T, Du X, Liu H, Wang S, Li X, Chen J, Zhang B, Liang H, Yang Y, Zhang W. The expression of P2X₇ receptors in EPCs and their potential role in the targeting of EPCs to brain gliomas. Cancer Biol Ther 2015; 16:498-510. [PMID: 25839324 DOI: 10.1080/15384047.2015.1016663] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
In order to use endothelial progenitor cells (EPCs) as a therapeutic and imaging probe to overcome antiangiogenic resistance for gliomas, how to enhance proliferation and targeting ability of transplanted EPCs is a high priority. Here, we confirmed, for the first time, the expression of P2X7 receptors in rat spleen-derived EPCs. Activation of P2X7 receptors in EPCs by BzATP promoted cells proliferation and migration, rather than apoptosis. In vivo, the homing of transplanted EPCs after long-term suppression of P2X7 receptors by persistent BBG stimulation was evaluated by MRI, immunohistochemistry and flow cytometry. Compared to the group without BBG treatment, less transplanted EPCs homed to gliomas in the group with BBG treatment, especially integrated into the vessels containing tumor-derived endothelial cells in gliomas. Moreover, western blot showed that CXCL1 expression was downregulated in gliomas with BBG treatment, which meant P2X7 receptors suppression inhibited the homing of EPCs to gliomas through down-regulation of CXCLl expression. Further, effects of P2X7 receptors on C6 glioma cells or gliomas were evaluated at the same dose of BzATP or BBG used in EPCs experiments in vitro and in vivo. MTT assay and MRI revealed that P2X7 receptors exerted no significant promoting effect on C6 glioma cells proliferation, gliomas growth and angiogenesis. Taken together, our findings imply the possibility of promoting proliferation and targeting ability of transplanted EPCs to brain gliomas in vivo through P2X7 receptors, which may provide new perspectives on application of EPCs as a therapeutic and imaging probe to overcome antiangiogenic resistance for gliomas.
Collapse
Affiliation(s)
- Jingqin Fang
- a Department of Radiology; Institute of Surgery Research; Daping Hospital; Third Military Medical University ; Chongqing , China
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Bilodeau MS, Arguin G, Gendron FP. C/EBPβ regulates P2X7 receptor expression in response to glucose challenge in intestinal epithelial cells. Biochem Cell Biol 2015; 93:38-46. [DOI: 10.1139/bcb-2014-0098] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Activation of the ATP-dependent P2X7 receptor modulates glucose transport in intestinal epithelial cells through the downregulation of glucose transporter GLUT2. In the present study, we show that an increase in glucose concentration stimulates P2X7 receptor transcription via modulation of CCAAT/enhancer binding proteins (C/EBPs) α and β expression. The described human P2X7 receptor promoter region (GenBank Y12851) was cloned upstream of a luciferase reporter gene in pGL4.10 plasmid and used to determine whether C/EBPs, namely C/EBPα and C/EBPβ, are able to stimulate the transcription of P2X7 receptor. Results show that C/EBPβ was the main regulator of P2X7 receptor expression in response to a glucose challenge. Chromatin immunoprecipitation (ChIP) assays further revealed that C/EBPβ occupied the –213 to +6 nt P2X7 promoter region. Surprisingly, C/EBPα was also able to bind this region as revealed by ChIP assays, but without inducing receptor transcription. In fact, C/EBPα and the C/EBPβ-LIP isoform blocked the C/EBPβ-dependent regulation of P2X7 receptor transcription. These findings suggest that glucose is not only the major source of energy for cell function but may also act as a signaling molecule to stimulate the expression of regulatory proteins.
Collapse
Affiliation(s)
- Maude S. Bilodeau
- Department of Anatomy and Cell Biology, Faculté de Médecine et des Sciences de la Santé, Pavillon de Recherche Appliquée sur le Cancer, Université de Sherbrooke, Sherbrooke, 3201 Jean-Mignault, QC J1E 4K8, Canada
| | - Guillaume Arguin
- Department of Anatomy and Cell Biology, Faculté de Médecine et des Sciences de la Santé, Pavillon de Recherche Appliquée sur le Cancer, Université de Sherbrooke, Sherbrooke, 3201 Jean-Mignault, QC J1E 4K8, Canada
| | - Fernand-Pierre Gendron
- Department of Anatomy and Cell Biology, Faculté de Médecine et des Sciences de la Santé, Pavillon de Recherche Appliquée sur le Cancer, Université de Sherbrooke, Sherbrooke, 3201 Jean-Mignault, QC J1E 4K8, Canada
| |
Collapse
|
20
|
Valproic Acid Influences MTNR1A Intracellular Trafficking and Signaling in a β-Arrestin 2-Dependent Manner. Mol Neurobiol 2015; 53:1237-1246. [DOI: 10.1007/s12035-014-9085-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2014] [Accepted: 12/29/2014] [Indexed: 10/24/2022]
|
21
|
Schneider SL, Ross AL, Grichnik JM. Do inflammatory pathways drive melanomagenesis? Exp Dermatol 2014; 24:86-90. [PMID: 25041143 DOI: 10.1111/exd.12502] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2014] [Indexed: 12/12/2022]
Abstract
Inflammatory pathways serve to protect the host and promote tissue healing/repair; however, over-activation or dysregulation can be pathological with unintended consequences including malignant progression. A correlation between inflammation and cancer has been well established, and anti-inflammatory medications have been shown to be chemopreventive in certain malignancies. Data are now becoming available that outline an inflammatory pathway that may have a critical role in melanomagenesis. ATP-regulated membrane channels/receptors P2X7 and PANX1 have been directly implicated in melanoma tumor growth. Among other potential effects, opening of the P2X7/PANX1 channel results in activation of the NALP3 inflammasome, which in turn leads to caspase-1 activation and increased levels of activated IL-1β. Elevated levels of caspase-1 and IL-1β have been correlated with melanoma progression, and inhibitors of the inflammasome, caspase and IL-1β activity have all been shown to inhibit melanoma growth. Among many other potential actions, IL-1β increases cyclooxygenase-2 expression leading to local increases in inflammatory mediators such as prostaglandin E2 (PGE2). Anti-inflammatory medications targeting the end of this pathway have had positive results for certain cancers but overall remain mixed for melanoma. A better understanding of the pathways and appropriate intervention points may help direct future therapies. In this viewpoint, we will review data and attempt to model an inflammatory pathway that may be critical for melanomagenesis and propose future directions for exploration.
Collapse
Affiliation(s)
- Samantha L Schneider
- Department of Dermatology and Cutaneous Surgery, Miller School of Medicine, University of Miami, Miami, FL, USA; Albert Einstein College of Medicine, Bronx, NY, USA
| | | | | |
Collapse
|
22
|
Kaebisch C, Schipper D, Babczyk P, Tobiasch E. The role of purinergic receptors in stem cell differentiation. Comput Struct Biotechnol J 2014; 13:75-84. [PMID: 26900431 PMCID: PMC4720018 DOI: 10.1016/j.csbj.2014.11.003] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 10/31/2014] [Accepted: 11/03/2014] [Indexed: 12/20/2022] Open
Abstract
A major challenge modern society has to face is the increasing need for tissue regeneration due to degenerative diseases or tumors, but also accidents or warlike conflicts. There is great hope that stem cell-based therapies might improve current treatments of cardiovascular diseases, osteochondral defects or nerve injury due to the unique properties of stem cells such as their self-renewal and differentiation potential. Since embryonic stem cells raise severe ethical concerns and are prone to teratoma formation, adult stem cells are still in the focus of research. Emphasis is placed on cellular signaling within these cells and in between them for a better understanding of the complex processes regulating stem cell fate. One of the oldest signaling systems is based on nucleotides as ligands for purinergic receptors playing an important role in a huge variety of cellular processes such as proliferation, migration and differentiation. Besides their natural ligands, several artificial agonists and antagonists have been identified for P1 and P2 receptors and are already used as drugs. This review outlines purinergic receptor expression and signaling in stem cells metabolism. We will briefly describe current findings in embryonic and induced pluripotent stem cells as well as in cancer-, hematopoietic-, and neural crest-derived stem cells. The major focus will be placed on recent findings of purinergic signaling in mesenchymal stem cells addressed in in vitro and in vivo studies, since stem cell fate might be manipulated by this system guiding differentiation towards the desired lineage in the future.
Collapse
Affiliation(s)
| | | | | | - Edda Tobiasch
- Department of Natural Sciences, Bonn-Rhine-Sieg University of Applied Sciences, Von-Liebig-Str. 20, 53359 Rheinbach, Germany
| |
Collapse
|
23
|
Burnstock G, Di Virgilio F. Purinergic signalling and cancer. Purinergic Signal 2014; 9:491-540. [PMID: 23797685 DOI: 10.1007/s11302-013-9372-5] [Citation(s) in RCA: 234] [Impact Index Per Article: 23.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Accepted: 06/06/2013] [Indexed: 01/24/2023] Open
Abstract
Receptors for extracellular nucleotides are widely expressed by mammalian cells. They mediate a large array of responses ranging from growth stimulation to apoptosis, from chemotaxis to cell differentiation and from nociception to cytokine release, as well as neurotransmission. Pharma industry is involved in the development and clinical testing of drugs selectively targeting the different P1 nucleoside and P2 nucleotide receptor subtypes. As described in detail in the present review, P2 receptors are expressed by all tumours, in some cases to a very high level. Activation or inhibition of selected P2 receptor subtypes brings about cancer cell death or growth inhibition. The field has been largely neglected by current research in oncology, yet the evidence presented in this review, most of which is based on in vitro studies, although with a limited amount from in vivo experiments and human studies, warrants further efforts to explore the therapeutic potential of purinoceptor targeting in cancer.
Collapse
|
24
|
Glaser T, de Oliveira SLB, Cheffer A, Beco R, Martins P, Fornazari M, Lameu C, Junior HMC, Coutinho-Silva R, Ulrich H. Modulation of mouse embryonic stem cell proliferation and neural differentiation by the P2X7 receptor. PLoS One 2014; 9:e96281. [PMID: 24798220 PMCID: PMC4010452 DOI: 10.1371/journal.pone.0096281] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 04/04/2014] [Indexed: 12/31/2022] Open
Abstract
Background Novel developmental functions have been attributed to the P2X7 receptor (P2X7R) including proliferation stimulation and neural differentiation. Mouse embryonic stem cells (ESC), induced with retinoic acid to neural differentiation, closely assemble processes occurring during neuroectodermal development of the early embryo. Principal Findings P2X7R expression together with the pluripotency marker Oct-4 was highest in undifferentiated ESC. In undifferentiated cells, the P2X7R agonist Bz-ATP accelerated cell cycle entry, which was blocked by the specific P2X7R inhibitor KN-62. ESC induced to neural differentiation with retinoic acid, reduced Oct-4 and P2X7R expression. P2X7R receptor-promoted intracellular calcium fluxes were obtained at lower Bz-ATP ligand concentrations in undifferentiated and in neural-differentiated cells compared to other studies. The presence of KN-62 led to increased number of cells expressing SSEA-1, Dcx and β3-tubulin, as well as the number of SSEA-1 and β3-tubulin-double-positive cells confirming that onset of neuroectodermal differentiation and neuronal fate determination depends on suppression of P2X7R activity. Moreover, an increase in the number of Ki-67 positive cells in conditions of P2X7R inhibition indicates rescue of progenitors into the cell cycle, augmenting the number of neuroblasts and consequently neurogenesis. Conclusions In embryonic cells, P2X7R expression and activity is upregulated, maintaining proliferation, while upon induction to neural differentiation P2X7 receptor expression and activity needs to be suppressed.
Collapse
Affiliation(s)
- Talita Glaser
- Departamento de Bioquímica; Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
| | | | - Arquimedes Cheffer
- Departamento de Bioquímica; Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
| | - Renata Beco
- Departamento de Bioquímica; Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
| | - Patrícia Martins
- Departamento de Bioquímica; Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
| | - Maynara Fornazari
- Departamento de Bioquímica; Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
| | - Claudiana Lameu
- Departamento de Bioquímica; Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
| | - Helio Miranda Costa Junior
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, RJ, Brazil
| | - Robson Coutinho-Silva
- Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro - UFRJ, Rio de Janeiro, RJ, Brazil
| | - Henning Ulrich
- Departamento de Bioquímica; Instituto de Química, Universidade de São Paulo, São Paulo, Brasil
- * E-mail:
| |
Collapse
|
25
|
Sun D, Junger WG, Yuan C, Zhang W, Bao Y, Qin D, Wang C, Tan L, Qi B, Zhu D, Zhang X, Yu T. Shockwaves induce osteogenic differentiation of human mesenchymal stem cells through ATP release and activation of P2X7 receptors. Stem Cells 2014; 31:1170-80. [PMID: 23404811 DOI: 10.1002/stem.1356] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 01/13/2013] [Accepted: 01/29/2013] [Indexed: 12/11/2022]
Abstract
Shockwave treatment promotes bone healing of nonunion fractures. In this study, we investigated whether this effect could be due to adenosine 5'-triphosphate (ATP) release-induced differentiation of human mesenchymal stem cells (hMSCs) into osteoprogenitor cells. Cultured bone marrow-derived hMSCs were subjected to shockwave treatment and ATP release was assessed. Osteogenic differentiation and mineralization of hMSCs were evaluated by examining alkaline phosphatase activity, osteocalcin production, and calcium nodule formation. Expression of P2X7 receptors and c-fos and c-jun mRNA was determined with real-time reverse transcription polymerase chain reaction and Western blotting. P2X7-siRNA, apyrase, P2 receptor antagonists, and p38 MAPK inhibitors were used to evaluate the roles of ATP release, P2X7 receptors, and p38 MAPK signaling in shockwave-induced osteogenic hMSCs differentiation. Shockwave treatment released significant amounts (≈ 7 μM) of ATP from hMSCs. Shockwaves and exogenous ATP induced c-fos and c-jun mRNA transcription, p38 MAPK activation, and hMSC differentiation. Removal of ATP with apyrase, targeting of P2X7 receptors with P2X7-siRNA or selective antagonists, or blockade of p38 MAPK with SB203580 prevented osteogenic differentiation of hMSCs. Our findings indicate that shockwaves release cellular ATP that activates P2X7 receptors and downstream signaling events that caused osteogenic differentiation of hMSCs. We conclude that shockwave therapy promotes bone healing through P2X7 receptor signaling, which contributes to hMSC differentiation.
Collapse
Affiliation(s)
- Dahui Sun
- Department of Orthopedics, The First Norman Bethune Hospital of Jilin University, Changchun, People's Republic of China
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Wang N, Gartland A. Role of the P2X7 receptor in the osteogenic differentiation of mesenchymal cells and in osteoclast fusion : presented by: Maria P. Abbracchio. Purinergic Signal 2013; 9:281-4. [PMID: 23949014 PMCID: PMC3757136 DOI: 10.1007/s11302-013-9384-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Affiliation(s)
- Ning Wang
- The Mellanby Centre for Bone Research, Department of Human Metabolism, The University of Sheffield, Beech Hill Road, Sheffield, S10 2RX UK
| | - Alison Gartland
- The Mellanby Centre for Bone Research, Department of Human Metabolism, The University of Sheffield, Beech Hill Road, Sheffield, S10 2RX UK
| |
Collapse
|
27
|
PKC-dependent ERK phosphorylation is essential for P2X7 receptor-mediated neuronal differentiation of neural progenitor cells. Cell Death Dis 2013; 4:e751. [PMID: 23907465 PMCID: PMC3763436 DOI: 10.1038/cddis.2013.274] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Revised: 06/19/2013] [Accepted: 06/21/2013] [Indexed: 01/01/2023]
Abstract
Purinergic receptors have been shown to be involved in neuronal development, but the functions of specific subtypes of P2 receptors during neuronal development remain elusive. In this study we investigate the distribution of P2X7 receptors (P2X7Rs) in the embryonic rat brain using in situ hybridization. At E15.5, P2X7R mRNA was observed in the ventricular zone and subventricular zone, and colocalized with nestin, indicating that P2X7R might be expressed in neural progenitor cells (NPCs). P2X7R mRNA was also detected in the subgranular zone and dentate gyrus of the E18.5 and P4 brain. To investigate the roles of P2X7R and elucidate its mechanism, we established NPC cultures from the E15.5 rat brain. Stimulation of P2X7Rs induced Ca2+ influx, inhibited proliferation, altered cell cycle progression and enhanced the expression of neuronal markers, such as TUJ1 and MAP2. Similarly, knockdown of P2X7R by shRNA nearly abolished the agonist-stimulated increases in intracellular Ca2+ concentration and the expression of TUJ1 and NeuN. Furthermore, stimulation of P2X7R induced activation of ERK1/2, which was inhibited by the removal of extracellular Ca2+ and treatment with blockers for P2X7R and PKC activity. Stimulation of P2X7R also induced translocation of PKCα and PKCγ, but not of PKCβ, whereas knockdown of either PKCα or PKCγ inhibited ERK1/2 activation. Inhibition of PKC or p-ERK1/2 also caused a decrease in the number of TUJ1-positive cells and a concomitant increase in the number of GFAP-positive cells. Taken together, the activation of P2X7R in NPCs induced neuronal differentiation through a PKC-ERK1/2 signaling pathway.
Collapse
|
28
|
Cervetto C, Alloisio S, Frattaroli D, Mazzotta MC, Milanese M, Gavazzo P, Passalacqua M, Nobile M, Maura G, Marcoli M. The P2X7 receptor as a route for non-exocytotic glutamate release: dependence on the carboxyl tail. J Neurochem 2013; 124:821-31. [PMID: 23293841 DOI: 10.1111/jnc.12143] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 12/24/2012] [Accepted: 01/03/2013] [Indexed: 11/28/2022]
Abstract
P2X7 receptors trigger Ca(2+) -dependent exocytotic glutamate release, but also function as a route for non-exocytotic glutamate release from neurons or astrocytes. To gain an insight into the mechanisms involving the P2X7 receptor as a direct pathway for glutamate release, we compared the behavior of a full-length rat P2X7 receptor, a truncated rat P2X7 receptor in which the carboxyl tail had been deleted, a rat P2X7 receptor with the 18-amino acid cysteine-rich motif of the carboxyl tail deleted, and a rat P2X2 receptor, all of which are expressed in HEK293 cells. We found that the P2X7 receptor function as a route for glutamate release was antagonized in a non-competitive way by extracellular Mg(2+) , did not require the recruitment of pore-forming molecules, and was dependent on the carboxyl tail. Indeed, the truncated P2X7 receptor and the P2X7 receptor with the deleted cysteine-rich motif both lost their function as a pathway for glutamate release, while still evoking intracellular Ca(2+) elevation. No glutamate efflux was observed through the P2X2 receptor. Notably, HEK293 cells (lacking the machinery for Ca(2+) -dependent exocytosis), when transfected with P2X7 receptors, appear to be a suitable model for investigating the P2X7 receptor as a route for non-exocytotic glutamate efflux.
Collapse
|
29
|
Foster JG, Carter E, Kilty I, MacKenzie AB, Ward SG. Mitochondrial superoxide generation enhances P2X7R-mediated loss of cell surface CD62L on naive human CD4+ T lymphocytes. THE JOURNAL OF IMMUNOLOGY 2013; 190:1551-9. [PMID: 23319734 DOI: 10.4049/jimmunol.1201510] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Migration of naive CD4(+) T lymphocytes into lymphoid tissue is essential for their activation and subsequent roles in adaptive immunity. The adhesion molecule L-selectin (CD62L), critical for this process, is highly expressed on naive CD4(+) T lymphocytes and is downregulated upon T lymphocyte activation. We demonstrate protein expression of P2X7R on naive CD4(+) T lymphocytes and show functional channel activity in whole-cell patch clamp recordings. CD62L downregulation occurs rapidly in response to extracellular ATP, a process that is blocked by selective antagonists of P2X7R. This loss of surface CD62L expression was not associated with externalization of phosphatidylserine. While investigating the mechanisms for this process, we revealed that pharmacological modulation of mitochondrial complex I or III, but not inhibition of NADPH oxidase, enhanced P2X7R-dependent CD62L downregulation by increasing ATP potency. Enhanced superoxide generation in the mitochondria of rotenone- and antimycin A-treated cells was observed and may contribute to the enhanced sensitivity of P2X7R to ATP. P2X7R-dependent exposure of phosphatidylserine was also revealed by preincubation with mitochondrial uncouplers prior to ATP treatment. This may present a novel mechanism whereby P2X7R-dependent phosphatidylserine exposure occurs only when cells have enhanced mitochondrial reactive oxygen species generation. The clearance of apoptotic cells may therefore be enhanced by this mechanism which requires functional P2X7R expression.
Collapse
Affiliation(s)
- John G Foster
- Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, United Kingdom
| | | | | | | | | |
Collapse
|
30
|
|
31
|
Abstract
Extracellular ATP (eATP), the most abundant among nucleotides, can act as a mediator during inflammatory responses by binding to plasmamembrane P2 purinergic receptors, which are widely expressed on cells of the immune system. eATP is generally considered as a classical danger signal, which stimulates immune responses in the presence of tissue damage. Converging evidence from several studies using murine models of chronic inflammation have supported this hypothesis; however, the role of eATP in the regulation of human immune function appears to be more complex. Chronic stimulation with micromolar eATP concentrations inhibits the proliferation of T and NK lymphocytes and enhances the capacity of dendritic cells to promote tolerance. The effect of eATP depends on multiple factors, such as the extent of stimulation, eATP concentration, presence/absence of other mediators in the microenvironment, and pattern of P2 receptor engagement. Small but significant differences in the pattern of P2 receptor expression in mice and humans confer the diverse capacities of ATP in regulating the immune response. Such diversity, which is often overlooked, should therefore be carefully considered when evaluating the role of eATP in human inflammatory and autoimmune diseases.
Collapse
|