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Resolving the Ionotropic P2X4 Receptor Mystery Points Towards a New Therapeutic Target for Cardiovascular Diseases. Int J Mol Sci 2020; 21:ijms21145005. [PMID: 32679900 PMCID: PMC7404342 DOI: 10.3390/ijms21145005] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 07/09/2020] [Accepted: 07/13/2020] [Indexed: 12/18/2022] Open
Abstract
Adenosine triphosphate (ATP) is a primordial versatile autacoid that changes its role from an intracellular energy saver to a signaling molecule once released to the extracellular milieu. Extracellular ATP and its adenosine metabolite are the main activators of the P2 and P1 purinoceptor families, respectively. Mounting evidence suggests that the ionotropic P2X4 receptor (P2X4R) plays pivotal roles in the regulation of the cardiovascular system, yet further therapeutic advances have been hampered by the lack of selective P2X4R agonists. In this review, we provide the state of the art of the P2X4R activity in the cardiovascular system. We also discuss the role of P2X4R activation in kidney and lungs vis a vis their interplay to control cardiovascular functions and dysfunctions, including putative adverse effects emerging from P2X4R activation. Gathering this information may prompt further development of selective P2X4R agonists and its translation to the clinical practice.
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Zafrah HA, Alotaibi MF. The effect of extracellular ATP on rat uterine contraction from different gestational stages and its possible mechanisms of action. J Basic Clin Physiol Pharmacol 2018; 28:209-217. [PMID: 28358713 DOI: 10.1515/jbcpp-2016-0118] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 02/09/2017] [Indexed: 11/15/2022]
Abstract
BACKGROUND The mechanisms underlying the onset of labor are not fully understood. Extracellular adenosine 5'-triphosphate (ATP) is known to cause uterine contractions in different species but the exact underlying mechanisms are poorly investigated to date. The aims of this study were to investigate the effect of extracellular ATP on spontaneous uterine contractions from different gestational stages and to elucidate its possible underlying mechanisms. METHODS Longitudinal uterine strips were obtained from rats in different gestational stages (nonpregnant, late-pregnant, and term-pregnant). The effects of 1 mM ATP were examined on uterine contractions generated spontaneously, depolarized by high-KCl (60 mM), induced by oxytocin (5 nM), in the presence of high external Ca2+, or in the absence of external Ca2+. RESULTS Application of 1 mM extracellular ATP significantly increased the force of spontaneous contraction in uterine strips obtained from all gestational stages with prominent increase in term-pregnant rats compared to other gestations. ATP significantly increased the force induced by depolarization (122%, p=0.010, n=6), oxytocin (129%, p=0.001, n=7), high-Ca2+ (145%, p=0.005, n=6) and it was able to cause transient contraction in the absence of external Ca2+ (33%, p<0.01). CONCLUSIONS Extracellular ATP is able to increase the force and frequency of uterine contractions and its effect increases with the progression of pregnancy and it involves Ca2+ influx and release. These findings open a new window for clinicians to consider ATP as a therapeutic target to control the uterine activity during difficult labors.
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Affiliation(s)
- Hind A Zafrah
- Department of Physiology, College of Medicine, King Khalid University, Abha, Kingdom of
| | - Mohammed F Alotaibi
- Department of Physiology, College of Medicine, King Saud University, P.O. Box 2925, Riyadh 11461, Kingdom of
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Alotaibi M. Changes in expression of P2X7 receptors in rat myometrium at different gestational stages and the mechanism of ATP-induced uterine contraction. Life Sci 2018. [PMID: 29524518 DOI: 10.1016/j.lfs.2018.03.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
AIMS Given the importance of ATP in the control of uterine activity for successful labor and involution, this study was performed to measure the level of P2X7 receptors (P2X7Rs) in rat myometrium at different gestational stages and to investigate the mechanisms of ATP-induced uterine contraction. MATERIALS AND METHODS Myometrial tissues were obtained from rats at different gestational stages and the level of P2X7Rs was measured by ELISA. In other experiments, the effect of 1 mM ATP was tested on spontaneous contraction and the underlying mechanisms were investigated. KEY FINDINGS P2X7Rs were expressed in nonpregnant uterine tissues, progressively increased throughout pregnancy, and markedly peaked during postpartum involution. ATP significantly increased the force of spontaneous contraction in all uterine strips from different gestational stages with marked increase during labor and postpartum. ATP could not maintain the force when external Ca2+ was removed. In addition, ATP was able to cause tonic transient contraction in the absence of external Ca2+. SIGNIFICANCE P2X7Rs are functionally regulated and contributed to ATP-induced uterine contraction. The sensitivity of the myometrium to ATP increases as pregnancy progresses and it involves Ca2+ influx and Ca2+ release pathways. The clear effects of ATP on contractility suggest its physiological requirement for successful labor and postpartum involution.
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Affiliation(s)
- Mohammed Alotaibi
- Department of Physiology, College of Medicine, King Saud University, P.O Box 2925, Riyadh 11461, Saudi Arabia.
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Zech A, Wiesler B, Ayata CK, Schlaich T, Dürk T, Hoßfeld M, Ehrat N, Cicko S, Idzko M. P2rx4 deficiency in mice alleviates allergen-induced airway inflammation. Oncotarget 2018; 7:80288-80297. [PMID: 27863396 PMCID: PMC5348320 DOI: 10.18632/oncotarget.13375] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 11/09/2016] [Indexed: 02/07/2023] Open
Abstract
Compelling evidences point out a crucial role for extracellular nucleotides such as adenosine triphosphate (ATP) during inflammatory conditions. Once released into the extracellular space, ATP modulates migration, maturation and function of various inflammatory cells via activating of purinergic receptors of the P2Y- and P2X- family. P2RX4 is an ATP-guided ion channel expressed on structural cells such as alveolar epithelial and smooth muscle cells as well as inflammatory cells including macrophages, dendritic cells (DCs) and T cells. P2RX4 has been shown to interact with P2RX7 and promote NLRP3 inflammasome activation. Although P2RX7 has already been implicated in allergic asthma, the role of P2RX4 in airway inflammation has not been elucidated yet. Therefore, we used a selective pharmacological antagonist and genetic ablation to investigate the role of P2RX4 in an ovalbumin (OVA) driven model of allergen-induced airway inflammation (AAI). Both, P2RX4 antagonist 5-BDBD treatment and P2rx4 deficiency resulted in an alleviated broncho alveolar lavage fluid eosinophilia, peribronchial inflammation, Th2 cytokine production and bronchial hyperresponsiveness. Furthermore, P2rx4-deficient bone marrow derived DCs (BMDCs) showed a reduced IL-1ß production in response to ATP accompanied by a decreased P2rx7 expression and attenuated Th2 priming capacity compared to wild type (WT) BMDCs in vitro. Moreover, mice adoptively transferred with P2rx4-deficient BMDCs exhibit a diminished AAI in vivo. In conclusion our data suggests that P2RX4-signaling contributes to AAI pathogenesis by regulating DC mediated Th2 cell priming via modulating IL-1ß secretion and selective P2RX4-antagonists might be a new therapeutic option for allergic asthma.
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Affiliation(s)
- Andreas Zech
- Department of Pneumology, University Medical Centre Freiburg, Germany
| | - Benjamin Wiesler
- Department of Pneumology, University Medical Centre Freiburg, Germany
| | | | - Tilmann Schlaich
- Department of Pneumology, University Medical Centre Freiburg, Germany
| | - Thorsten Dürk
- Department of Pneumology, University Medical Centre Freiburg, Germany
| | - Madelon Hoßfeld
- Department of Pneumology, University Medical Centre Freiburg, Germany
| | - Nicolas Ehrat
- Department of Pneumology, University Medical Centre Freiburg, Germany
| | - Sanja Cicko
- Department of Pneumology, University Medical Centre Freiburg, Germany
| | - Marco Idzko
- Department of Pneumology, University Medical Centre Freiburg, Germany
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Gao ZG, Jacobson KA. Purinergic Signaling in Mast Cell Degranulation and Asthma. Front Pharmacol 2017; 8:947. [PMID: 29311944 PMCID: PMC5744008 DOI: 10.3389/fphar.2017.00947] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 12/14/2017] [Indexed: 11/13/2022] Open
Abstract
Mast cells are responsible for the majority of allergic conditions. It was originally thought that almost all allergic events were mediated directly only via the high-affinity immunoglobulin E receptors. However, recent evidence showed that many other receptors, such as G protein-coupled receptors and ligand-gated ion channels, are also directly involved in mast cell degranulation, the release of inflammatory mediators such as histamine, serine proteases, leukotrienes, heparin, and serotonin. These mediators are responsible for the symptoms in allergic conditions such as allergic asthma. In recent years, it has been realized that purinergic signaling, induced via the activation of G protein-coupled adenosine receptors and P2Y nucleotide receptors, as well as by ATP-gated P2X receptors, plays a significant role in mast cell degranulation. Both adenosine and ATP can induce degranulation and bronchoconstriction on their own and synergistically with allergens. All three classes of receptors, adenosine, P2X and P2Y are involved in tracheal mucus secretion. This review will summarize the currently available knowledge on the role of purinergic signaling in mast cell degranulation and its most relevant disease, asthma.
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Affiliation(s)
- Zhan-Guo Gao
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Kenneth A Jacobson
- Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
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De Ita M, Vargas MH, Carbajal V, Ortiz-Quintero B, López-López C, Miranda-Morales M, Barajas-López C, Montaño LM. ATP releases ATP or other nucleotides from human peripheral blood leukocytes through purinergic P2 receptors. Life Sci 2015; 145:85-92. [PMID: 26679107 DOI: 10.1016/j.lfs.2015.12.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Revised: 11/07/2015] [Accepted: 12/05/2015] [Indexed: 12/29/2022]
Abstract
AIMS Almost every eukaryotic cell releases ATP under certain conditions. The idea that ATP induces the release of ATP has been scantly investigated. METHODS We explored this possibility by assessing the rate of exogenous ATP breakdown (measured by phosphates production) by human peripheral blood leukocytes. The role of P2Y and P2X receptors was evaluated pharmacologically, by patch clamp, or by flow cytometry. KEY FINDINGS In mononuclear and/or polymorphonuclear cells, ATP increased phosphates formation in a time- and concentration-dependent manner. Uncoupling of P2Y receptors with N-ethylmaleimide and antagonism of P2Y and P2X receptors through suramin reduced phosphate formation after 500μM ATP, suggesting that part of the phosphate production was due to activation of P2 receptors, with subsequent release of ATP or other nucleotides. Similar results were obtained with UTP and ATPγS. Gadolinium (connexins inhibitor) also significantly reduced the ATP-induced phosphate production. Blockade of P2X receptors with SKF 96365 or NF023 did not modify the phosphate production. In monocytes, 500μM ATP induced inward currents suggestive of P2X1 activation, but higher concentrations (1-5mM) induced inward currents suggestive of P2X7 activation. We discarded a role of adenosine in the ATP-evoked nucleotides release. Flow cytometry identified that almost all mononuclear and polymorphonuclear cells expressed P2Y1,2,4,6,11 receptors. SIGNIFICANCE 500μM ATP induced the release of ATP or other nucleotides through activation of P2Y2,4,6,11 receptors in human leukocytes, and probably via P2X receptors at higher concentrations. This ATP-induced nucleotides release constitutes a potential mechanism leading to amplification of ATP signaling.
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Affiliation(s)
- Marlon De Ita
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, México
| | - Mario H Vargas
- Departamento de Investigación en Hiperreactividad Bronquial, Instituto Nacional de Enfermedades Respiratorias, México, DF, México
| | - Verónica Carbajal
- Departamento de Investigación en Hiperreactividad Bronquial, Instituto Nacional de Enfermedades Respiratorias, México, DF, México
| | - Blanca Ortiz-Quintero
- Departamento de Investigación en Bioquímica, Instituto Nacional de Enfermedades Respiratorias, México, DF, México
| | - Cintya López-López
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, San Luis Potosí, SLP, México
| | - Marcela Miranda-Morales
- Departamento de Neurobiología Celular y Molecular, Instituto de Neurobiología, Universidad Nacional Autónoma de México, Querétaro, México
| | - Carlos Barajas-López
- División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, San Luis Potosí, SLP, México
| | - Luis M Montaño
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, México.
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Lv Q, Xue Y, Li G, Zou L, Zhang X, Ying M, Wang S, Guo L, Gao Y, Li G, Xu H, Liu S, Xie J, Liang S. Beneficial effects of evodiamine on P2X(4)-mediated inflammatory injury of human umbilical vein endothelial cells due to high glucose. Int Immunopharmacol 2015; 28:1044-9. [PMID: 26344431 DOI: 10.1016/j.intimp.2015.08.020] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Revised: 08/11/2015] [Accepted: 08/14/2015] [Indexed: 12/23/2022]
Abstract
Evodiamine has been reported to exhibit anti-inflammatory and anti-nociceptive effects, but the underlying mechanisms remain to be defined. P2X4 receptor (P2X4R) is a subtype of ATP receptors and plays important roles in pain, inflammatory and immune responses. We aimed to investigate whether evodiamine has beneficial effects on endothelial inflammatory injury mediated by chronic high glucose condition. We found that culturing human umbilical vein endothelial cells (HUVECs) with high glucose significantly increased the expression of P2X4 receptor in HUVECs, cytosolic Ca(2+) concentrations and intracellular reactive oxygen species (ROS) while decreasing nitric oxide (NO); these effects could be reversed by evodiamine. High glucose also significantly increased the expression of the pro-inflammatory activators (NF-κB) and TNFR-ɑ, which was accompanied by the elevation of P2X4R levels. Evodiamine was able to down-regulate the elevated NF-κB, TNFR-ɑ, P2X4R and ROS, and up-regulate the decreased NO. Thus the evodiamine may exert the anti-inflammation activity on high-glucose challenge HUVEC via suppressing the P2X4R signaling pathway, exhibiting beneficial ability to protect HUVECs from glucotoxicity.
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Affiliation(s)
- Qiulan Lv
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Yun Xue
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Guodong Li
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China; Department of Clinical Research, Singapore General Hospital, Singapore
| | - Lifang Zou
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Xi Zhang
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Mofeng Ying
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Shouyu Wang
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Lili Guo
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Yun Gao
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Guilin Li
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Hong Xu
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Shuangmei Liu
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China
| | - Jinyan Xie
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China; Key Laboratory of Molecular Medicine of JiangXi, The Second Affiliated Hospital of Nanchang University, People's Republic of China
| | - Shangdong Liang
- Department of Physiology, Medical School of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China; Institute of Life Science of Nanchang University, Nanchang, Jiangxi 330006, People's Republic of China.
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Koopmans T, Anaparti V, Castro-Piedras I, Yarova P, Irechukwu N, Nelson C, Perez-Zoghbi J, Tan X, Ward JPT, Wright DB. Ca2+ handling and sensitivity in airway smooth muscle: emerging concepts for mechanistic understanding and therapeutic targeting. Pulm Pharmacol Ther 2014; 29:108-20. [PMID: 24831539 DOI: 10.1016/j.pupt.2014.05.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2014] [Revised: 03/28/2014] [Accepted: 05/01/2014] [Indexed: 02/01/2023]
Abstract
Free calcium ions within the cytosol serve as a key secondary messenger system for a diverse range of cellular processes. Dysregulation of cytosolic Ca(2+) handling in airway smooth muscle (ASM) has been implicated in asthma, and it has been hypothesised that this leads, at least in part, to associated changes in both the architecture and function of the lung. Significant research is therefore directed towards furthering our understanding of the mechanisms which control ASM cytosolic calcium, in addition to those regulating the sensitivity of its downstream effector targets to calcium. Key aspects of the recent developments in this field were discussed at the 8th Young Investigators' Symposium on Smooth Muscle (2013, Groningen, The Netherlands), and are outlined in this review.
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Affiliation(s)
- T Koopmans
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands
| | - V Anaparti
- Department of Immunology, University of Manitoba, Winnipeg, Canada
| | - I Castro-Piedras
- Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, TX, USA
| | - P Yarova
- Cardiff School of Biosciences, Cardiff University, UK
| | - N Irechukwu
- Division of Asthma, Allergy and Lung Biology, King's College London, UK
| | - C Nelson
- School of Science & Technology, Nottingham Trent University, Nottingham, UK
| | - J Perez-Zoghbi
- Cell Physiology and Molecular Biophysics, Texas Tech University Health Sciences Center, TX, USA
| | - X Tan
- Lung Inflammation & Infection Lab, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - J P T Ward
- Division of Asthma, Allergy and Lung Biology, King's College London, UK
| | - D B Wright
- Department of Molecular Pharmacology, University of Groningen, Groningen, The Netherlands; Division of Asthma, Allergy and Lung Biology, King's College London, UK.
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Histamine, carbachol, and serotonin induce hyperresponsiveness to ATP in guinea pig tracheas: involvement of COX-2 pathway. Pflugers Arch 2013; 465:1171-9. [PMID: 23475395 DOI: 10.1007/s00424-013-1253-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 02/07/2013] [Accepted: 02/17/2013] [Indexed: 02/06/2023]
Abstract
Extracellular ATP promotes an indirect contraction of airway smooth muscle via the secondary release of thromboxane A2 (TXA2) from airway epithelium. Our aim was to evaluate if common contractile agonists modify this response to ATP. Tracheas from sensitized guinea pigs were used to evaluate ATP-induced contractions before and after a transient contraction produced by histamine, carbachol, or serotonin. Epithelial mRNA for COX-1 and COX-2 was measured by RT-PCR and their expression assessed by immunohistochemistry. Compared with the initial response, ATP-induced contraction was potentiated by pretreatment with histamine, carbachol, or serotonin. Either suramin (antagonist of P2X and P2Y receptors) plus RB2 (antagonist of P2Y receptors) or indomethacin (inhibitor of COX-1 and COX-2) annulled the ATP-induced contraction, suggesting that it was mediated by P2Y receptor stimulation and TXA2 production. When COX-2 was inhibited by SC-58125 or thromboxane receptors were antagonized by SQ-29548, just the potentiation was abolished, leaving the basal response intact. Airway epithelial cells showed increased COX-2 mRNA after stimulation with histamine or carbachol, but not serotonin, while COX-1 mRNA was unaffected. Immunochemistry corroborated this upregulation of COX-2. In conclusion, we showed for the first time that histamine and carbachol cause hyperresponsiveness to ATP by upregulating COX-2 in airway epithelium, which likely increases TXA2 production. Serotonin-mediated hyperresponsiveness seems to be independent of COX-2 upregulation, but nonetheless is TXA2 dependent. Because acetylcholine, histamine, and serotonin can be present during asthmatic exacerbations, their potential interactions with ATP might be relevant in its pathophysiology.
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Burnstock G, Brouns I, Adriaensen D, Timmermans JP. Purinergic signaling in the airways. Pharmacol Rev 2012; 64:834-68. [PMID: 22885703 DOI: 10.1124/pr.111.005389] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Evidence for a significant role and impact of purinergic signaling in normal and diseased airways is now beyond dispute. The present review intends to provide the current state of knowledge of the involvement of purinergic pathways in the upper and lower airways and lungs, thereby differentiating the involvement of different tissues, such as the epithelial lining, immune cells, airway smooth muscle, vasculature, peripheral and central innervation, and neuroendocrine system. In addition to the vast number of well illustrated functions for purinergic signaling in the healthy respiratory tract, increasing data pointing to enhanced levels of ATP and/or adenosine in airway secretions of patients with airway damage and respiratory diseases corroborates the emerging view that purines act as clinically important mediators resulting in either proinflammatory or protective responses. Purinergic signaling has been implicated in lung injury and in the pathogenesis of a wide range of respiratory disorders and diseases, including asthma, chronic obstructive pulmonary disease, inflammation, cystic fibrosis, lung cancer, and pulmonary hypertension. These ostensibly enigmatic actions are based on widely different mechanisms, which are influenced by the cellular microenvironment, but especially the subtypes of purine receptors involved and the activity of distinct members of the ectonucleotidase family, the latter being potential protein targets for therapeutic implementation.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Royal Free Campus, London, UK.
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11
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Gui Y, Wang Z, Sun X, Walsh MP, Li JJ, Gao J, Zheng XL. Uridine adenosine tetraphosphate induces contraction of airway smooth muscle. Am J Physiol Lung Cell Mol Physiol 2011; 301:L789-94. [PMID: 21840961 DOI: 10.1152/ajplung.00203.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Contraction of airway smooth muscle (ASM) plays an important role in the regulation of air flow and is potentially involved in the pathophysiology of certain respiratory diseases. Extracellular nucleotides regulate ASM contraction via purinergic receptors, but the signaling mechanisms involved are not fully understood. Uridine adenosine tetraphosphate (Up(4)A) contains both pyrimidine and purine moieties, which are known to potentially activate P2X and P2Y receptors. Both P2X and P2Y receptors have been identified in the lung, including airway epithelial cells and ASM. We report here a study of purinergic signaling in the respiratory system, with a focus on the effect of Up(4)A on ASM contraction. Up(4)A induced contraction of rat isolated trachea and extrapulmonary bronchi as well as human intrapulmonary bronchioles. Up(4)A-induced contraction was blocked by di-inosine pentaphosphate, a P2X antagonist, but not by suramin, a nonselective P2 antagonist. Up(4)A-induced contraction was also attenuated by α,β-methylene-ATP-mediated P2X receptor desensitization. Several P2X receptors were detected at the mRNA level: P2X1, P2X4, P2X6, and P2X7, and to a lesser extent P2X3. Furthermore, the Up(4)A response was inhibited by removal of extracellular Ca(2+) and by the presence of the L-type Ca(2+) channel blocker, nifedipine, or the Rho-associated kinase inhibitor, H1152. We conclude that Up(4)A stimulates ASM contraction, and the underlying signaling mechanism appears to involve P2X (most likely P2X1) receptors, extracellular Ca(2+) entry via L-type Ca(2+) channels, and Ca(2+) sensitization through the RhoA/Rho-associated kinase pathway. This study will add to our understanding of the pathophysiological roles of extracellular nucleotides in the lung.
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Affiliation(s)
- Yu Gui
- Dept. of Physiology & Pharmacology, Faculty of Medicine, Univ. of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1.
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12
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Coddou C, Yan Z, Obsil T, Huidobro-Toro JP, Stojilkovic SS. Activation and regulation of purinergic P2X receptor channels. Pharmacol Rev 2011; 63:641-83. [PMID: 21737531 DOI: 10.1124/pr.110.003129] [Citation(s) in RCA: 394] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mammalian ATP-gated nonselective cation channels (P2XRs) can be composed of seven possible subunits, denoted P2X1 to P2X7. Each subunit contains a large ectodomain, two transmembrane domains, and intracellular N and C termini. Functional P2XRs are organized as homomeric and heteromeric trimers. This review focuses on the binding sites involved in the activation (orthosteric) and regulation (allosteric) of P2XRs. The ectodomains contain three ATP binding sites, presumably located between neighboring subunits and formed by highly conserved residues. The detection and coordination of three ATP phosphate residues by positively charged amino acids are likely to play a dominant role in determining agonist potency, whereas an AsnPheArg motif may contribute to binding by coordinating the adenine ring. Nonconserved ectodomain histidines provide the binding sites for trace metals, divalent cations, and protons. The transmembrane domains account not only for the formation of the channel pore but also for the binding of ivermectin (a specific P2X4R allosteric regulator) and alcohols. The N- and C- domains provide the structures that determine the kinetics of receptor desensitization and/or pore dilation and are critical for the regulation of receptor functions by intracellular messengers, kinases, reactive oxygen species and mercury. The recent publication of the crystal structure of the zebrafish P2X4.1R in a closed state provides a major advance in the understanding of this family of receptor channels. We will discuss data obtained from numerous site-directed mutagenesis experiments accumulated during the last 15 years with reference to the crystal structure, allowing a structural interpretation of the molecular basis of orthosteric and allosteric ligand actions.
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Affiliation(s)
- Claudio Coddou
- Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Developmant, National Institutes of Health, Bethesda, MD 20892-4510, USA
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13
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Abstract
Seven mammalian purinergic receptor subunits, denoted P2X1-P2X7, and several spliced forms of these subunits have been cloned. When heterologously expressed, these cDNAs encode ATP-gated non-selective cation channels organized as trimers. All activated receptors produce cell depolarization and promote Ca(2+) influx through their pores and indirectly by activating voltage-gated calcium channels. However, the biophysical and pharmacological properties of these receptors differ considerably, and the majority of these subunits are also capable of forming heterotrimers with other members of the P2X receptor family, which confers further different properties. These channels have three ATP binding domains, presumably located between neighboring subunits, and occupancy of at least two binding sites is needed for their activation. In addition to the orthosteric binding sites for ATP, these receptors have additional allosteric sites that modulate the agonist action at receptors, including sites for trace metals, protons, neurosteroids, reactive oxygen species and phosphoinositides. The allosteric regulation of P2X receptors is frequently receptor-specific and could be a useful tool to identify P2X members in native tissues and their roles in signaling. The focus of this review is on common and receptor-specific allosteric modulation of P2X receptors and the molecular base accounting for allosteric binding sites.
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Affiliation(s)
- Claudio Coddou
- Section on Cellular Signaling, Program in Developmental Neuroscience, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-4510, USA.
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Cho YR, Jang HS, Kim W, Park SY, Sohn UD. P2X and P2Y Receptors Mediate Contraction Induced by Electrical Field Stimulation in Feline Esophageal Smooth Muscle. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2010; 14:311-6. [PMID: 21165330 DOI: 10.4196/kjpp.2010.14.5.311] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 10/07/2010] [Accepted: 10/20/2010] [Indexed: 11/15/2022]
Abstract
It is well-known that electrical field stimulation (EFS)-induced contraction is mediated by a cholinergic mechanism and other neurotransmitters. NO, ATP, calcitonin gene-related peptide (CGRP), and substance P are released by EFS. To investigate the purinergic mechanism involved in the EFS-induced contraction, purinegic receptors antagonists were used. Suramine, a non-selective P2 receptor antagonist, reduced the contraction induced by EFS. NF023 (10(-7)~10(-4) M), a selective P2X antagonist, inhibited the contraction evoked by EFS. Reactive blue (10(-6)~10(-4) M), selective P2Y antagonist, also blocked the contraction in a dose-dependent manner. In addition, P2X agonist α,β-methylene 5'-adenosine triphosphate (αβMeATP, 10(-7)~10(-5) M) potentiated EFS-induced contraction in a dose-dependent manner. P2Y agonist adenosine 5'-[β-thio]diphosphate trilithium salt (ADPβS, 10(-7)~10(-5) M) also potentiated EFS-induced contractions in a dose-dependent manner. Ecto-ATPase activator apyrase (5 and 10 U/ml) reduced EFS-induced contractions. Inversely, 6-N,N-diethyl-D-β,γ-dibromomethylene 5'-triphosphate triammonium (ARL 67156, 10(-4) M) increased EFS-induced contraction. These data suggest that endogenous ATP plays a role in EFS-induced contractions which are mediated through both P2X-receptors and P2Y-receptors stimulation in cat esophageal smooth muscle.
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Affiliation(s)
- Young Rae Cho
- Department of Pharmacology, College of Pharmacy, Chung-Ang University, Seoul 156-756, Korea
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Flores-Soto E, Carbajal V, Reyes-García J, García-Hernández LM, Figueroa A, Checa M, Barajas-López C, Montaño LM. In airways ATP refills sarcoplasmic reticulum via P2X smooth muscle receptors and induces contraction through P2Y epithelial receptors. Pflugers Arch 2010; 461:261-75. [PMID: 20953624 DOI: 10.1007/s00424-010-0886-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2010] [Revised: 09/13/2010] [Accepted: 09/23/2010] [Indexed: 11/28/2022]
Abstract
In airway smooth muscle (ASM), ATP induces a contraction associated with the increase of [Ca(2+)](i). Cytosolic Ca(2+) is extruded to the extracellular space by the Na(+)/Ca(2+) exchanger (NCX) in its normal mode. Some agonists activate the reverse mode of the NCX (NCX(REV)), inducing Ca(2+) entry. We investigated whether ATP, via P2X receptors, activates the NCX(REV) and whether the increment in [Ca(2+)](i) is used for contraction or for the sarcoplasmic reticulum (SR) refilling in guinea pig ASM. ATP contracted the ASM and this effect was blocked by indomethacin. Suramin and RB2 diminished the contraction induced by ATP; PPADS did not modify this response. In myocytes, ATP produces an increase in [Ca(2+)](i) not modified by indomethacin. In tracheal strips, using simultaneous measurements, ATP induced a biphasic change in [Ca(2+)](i), (a Ca(2+) peak followed by a plateau) accompanied by a contraction. Indomethacin or epithelium removal abolished this contraction, but not the Ca(2+) peak, whereas the plateau was decreased by indomethacin. In myocytes, the ATP-induced [Ca(2+)](i) increment was inhibited by suramin (~96%), PPADS (~40%), and RB2 (~57%). ATP augmented the NCX(REV) and this effect was abolished by SKF 96365 and TNP-ATP (P2X(1) and P2X(3) receptors antagonist). P2X(1) and P2X(3) receptors were corroborated by immunoblotting of ASM. NCX(REV) activation and ATP in the presence of RB2 favor the SR Ca(2+) refilling. In tracheal rings, successive ATP stimulations were reduced with KB-R7943. Therefore, ATP: (1) indirectly promotes muscle contraction via epithelial P2Y receptors and prostaglandins release; (2) increases the [Ca(2+)](i) through a prostaglandin-independent manner by activating P2X and P2Y receptors in smooth muscle; and (3) activates P2X(1) and P2X(3) receptors and the NCX(REV) which refills the SR.
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Affiliation(s)
- Edgar Flores-Soto
- Departamento de Farmacología, Facultad de Medicina, Universidad Nacional Autónoma de México, México, DF, México
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