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Li H, Bradbury JA, Edin ML, Gruzdev A, Li H, Graves JP, DeGraff LM, Lih FB, Feng C, Wolf ER, Bortner CD, London SJ, Sparks MA, Coffman TM, Zeldin DC. TXA2 attenuates allergic lung inflammation through regulation of Th2, Th9, and Treg differentiation. J Clin Invest 2024; 134:e165689. [PMID: 38483511 PMCID: PMC11060738 DOI: 10.1172/jci165689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 03/12/2024] [Indexed: 05/02/2024] Open
Abstract
In lung, thromboxane A2 (TXA2) activates the TP receptor to induce proinflammatory and bronchoconstrictor effects. Thus, TP receptor antagonists and TXA2 synthase inhibitors have been tested as potential asthma therapeutics in humans. Th9 cells play key roles in asthma and regulate the lung immune response to allergens. Herein, we found that TXA2 reduces Th9 cell differentiation during allergic lung inflammation. Th9 cells were decreased approximately 2-fold and airway hyperresponsiveness was attenuated in lungs of allergic mice treated with TXA2. Naive CD4+ T cell differentiation to Th9 cells and IL-9 production were inhibited dose-dependently by TXA2 in vitro. TP receptor-deficient mice had an approximately 2-fold increase in numbers of Th9 cells in lungs in vivo after OVA exposure compared with wild-type mice. Naive CD4+ T cells from TP-deficient mice exhibited increased Th9 cell differentiation and IL-9 production in vitro compared with CD4+ T cells from wild-type mice. TXA2 also suppressed Th2 and enhanced Treg differentiation both in vitro and in vivo. Thus, in contrast to its acute, proinflammatory effects, TXA2 also has longer-lasting immunosuppressive effects that attenuate the Th9 differentiation that drives asthma progression. These findings may explain the paradoxical failure of anti-thromboxane therapies in the treatment of asthma.
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Affiliation(s)
- Hong Li
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - J. Alyce Bradbury
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Matthew L. Edin
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Artiom Gruzdev
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Huiling Li
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Joan P. Graves
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Laura M. DeGraff
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Fred B. Lih
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Chiguang Feng
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Erin R. Wolf
- Department of Nephrology, Duke University Medical Center, Durham, North Carolina, USA
| | - Carl D. Bortner
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Stephanie J. London
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
| | - Matthew A. Sparks
- Department of Nephrology, Duke University Medical Center, Durham, North Carolina, USA
| | - Thomas M. Coffman
- Department of Nephrology, Duke University Medical Center, Durham, North Carolina, USA
- Program in Cardiovascular and Metabolic Disorders, Duke-NUS Medical School, Singapore
| | - Darryl C. Zeldin
- Division of Intramural Research, National Institute of Environmental Health Sciences/NIH, Research Triangle Park, North Carolina, USA
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2
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Ashton AW. Preparing to strike: Acute events in signaling by the serpentine receptor for thromboxane A 2. Pharmacol Ther 2023:108478. [PMID: 37321373 DOI: 10.1016/j.pharmthera.2023.108478] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 05/31/2023] [Accepted: 06/07/2023] [Indexed: 06/17/2023]
Abstract
Over the last two decades, awareness of the (patho)physiological roles of thromboxane A2 signaling has been greatly extended. From humble beginnings as a short-lived stimulus that activates platelets and causes vasoconstriction to a dichotomous receptor system involving multiple endogenous ligands capable of modifying tissue homeostasis and disease generation in almost every tissue of the body. Thromboxane A2 receptor (TP) signal transduction is associated with the pathogenesis of cancer, atherosclerosis, heart disease, asthma, and host response to parasitic infection amongst others. The two receptors mediating these cellular responses (TPα and TPβ) are derived from a single gene (TBXA2R) through alternative splicing. Recently, knowledge about the mechanism(s) of signal propagation by the two receptors has undergone a revolution in understanding. Not only have the structural relationships associated with G-protein coupling been established but the modulation of that signaling by post-translational modification to the receptor has come sharply into focus. Moreover, the signaling of the receptor unrelated to G-protein coupling has become a burgeoning field of endeavor with over 70 interacting proteins currently identified. These data are reshaping the concept of TP signaling from a mere guanine nucleotide exchange factors for Gα activation to a nexus for the convergence of diverse and poorly characterized signaling pathways. This review summarizes the advances in understanding in TP signaling, and the potential for new growth in a field that after almost 50 years is finally coming of age.
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Affiliation(s)
- Anthony W Ashton
- Division of Cardiovascular Medicine, Lankenau Institute for Medical Research, Rm 128, 100 E Lancaster Ave, Wynnewood, PA 19096, USA; Division of Perinatal Research, Kolling Institute of Medical Research, Faculty of Medicine and Health, University of Sydney, St Leonards, NSW 2065, Australia.
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3
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Rousseau M, Naika GS, Perron J, Jacques F, Gelb MH, Boilard E. Study of the role of cytosolic phospholipase A2 alpha in eicosanoid generation and thymocyte maturation in the thymus. PLoS One 2015; 10:e0126204. [PMID: 25969996 PMCID: PMC4430275 DOI: 10.1371/journal.pone.0126204] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Accepted: 03/30/2015] [Indexed: 11/29/2022] Open
Abstract
The thymus is a primary lymphoid organ, home of maturation and selection of thymocytes for generation of functional T-cells. Multiple factors are involved throughout the different stages of the maturation process to tightly regulate T-cell production. The metabolism of arachidonic acid by cyclooxygenases, lipoxygenases and specific isomerases generates eicosanoids, lipid mediators capable of triggering cellular responses. In this study, we determined the profile of expression of the eicosanoids present in the mouse thymus at different stages of thymocyte development. As the group IVA cytosolic phospholipase A2 (cPLA2α) catalyzes the hydrolysis of phospholipids, thereby generating arachidonic acid, we further verified its contribution by including cPLA2α deficient mice to our investigations. We found that a vast array of eicosanoids is expressed in the thymus, which expression is substantially modulated through thymocyte development. The cPLA2α was dispensable in the generation of most eicosanoids in the thymus and consistently, the ablation of the cPLA2α gene in mouse thymus and the culture of thymuses from human newborns in presence of the cPLA2α inhibitor pyrrophenone did not impact thymocyte maturation. This study provides information on the eicosanoid repertoire present during thymocyte development and suggests that thymocyte maturation can occur independently of cPLA2α.
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Affiliation(s)
- Matthieu Rousseau
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Faculté de Médecine de l’Université Laval, Québec, QC, Canada
| | - Gajendra S. Naika
- Department of Chemistry, University of Washington, Seattle, WA, the United States of America
| | - Jean Perron
- Centre de Recherche du Centre Hospitalier Universitaire de Québec, Faculté de Médecine de l’Université Laval, Québec, QC, Canada
| | - Frederic Jacques
- Centre de Recherche du Centre Hospitalier Universitaire de Québec, Faculté de Médecine de l’Université Laval, Québec, QC, Canada
| | - Michael H. Gelb
- Department of Chemistry, University of Washington, Seattle, WA, the United States of America
| | - Eric Boilard
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du Centre Hospitalier Universitaire de Québec, Faculté de Médecine de l’Université Laval, Québec, QC, Canada
- * E-mail:
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4
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Bauer J, Ripperger A, Frantz S, Ergün S, Schwedhelm E, Benndorf RA. Pathophysiology of isoprostanes in the cardiovascular system: implications of isoprostane-mediated thromboxane A2 receptor activation. Br J Pharmacol 2015; 171:3115-31. [PMID: 24646155 DOI: 10.1111/bph.12677] [Citation(s) in RCA: 119] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Revised: 02/20/2014] [Accepted: 03/03/2014] [Indexed: 12/13/2022] Open
Abstract
Isoprostanes are free radical-catalysed PG-like products of unsaturated fatty acids, such as arachidonic acid, which are widely recognized as reliable markers of systemic lipid peroxidation and oxidative stress in vivo. Moreover, activation of enzymes, such as COX-2, may contribute to isoprostane formation. Indeed, formation of isoprostanes is considerably increased in various diseases which have been linked to oxidative stress, such as cardiovascular disease (CVD), and may predict the atherosclerotic burden and the risk of cardiovascular complications in the latter patients. In addition, several isoprostanes may directly contribute to the functional consequences of oxidant stress via activation of the TxA2 prostanoid receptor (TP), for example, by affecting endothelial cell function and regeneration, vascular tone, haemostasis and ischaemia/reperfusion injury. In this context, experimental and clinical data suggest that selected isoprostanes may represent important alternative activators of the TP receptor when endogenous TxA2 levels are low, for example, in aspirin-treated individuals with CVD. In this review, we will summarize the current understanding of isoprostane formation, biochemistry and (patho) physiology in the cardiovascular context.
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Affiliation(s)
- Jochen Bauer
- Institute of Anatomy and Cell Biology, University of Würzburg, Würzburg, Germany
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5
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da Silva-Souza HA, de Lira MN, Patel NK, Spray DC, Persechini PM, Scemes E. Inhibitors of the 5-lipoxygenase pathway activate pannexin1 channels in macrophages via the thromboxane receptor. Am J Physiol Cell Physiol 2014; 307:C571-9. [PMID: 25080488 DOI: 10.1152/ajpcell.00087.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A multitude of environmental signaling molecules influence monocyte and macrophage innate and adaptive immune responses, including ATP and prostanoids. Interestingly, purinergic (P2) and eicosanoid receptor signaling interact such that the activation of P2 receptors leads to prostanoid production, which can then interfere with P2Y-mediated macrophage migration. Recent studies suggest that blockade of 5-lipoxygenase (5-LOX) in macrophages can activate a permeation pathway involved in the influx of dye and the release of ATP. Here, we provide evidence that pannexin1 (Panx1) is a component of this pathway and present the intracellular signaling molecules linking the thromboxane (TP) receptor to Panx1-mediated dye influx and ATP release. Using pharmacological tools and transgenic mice deficient in Panx1, we show that two 5-LOX pathway inhibitors induce ATP release and influx of dye in a Panx1-dependent manner. Electrophysiological recordings performed in wild-type and Panx1-deficient macrophages confirmed that these 5-LOX pathway inhibitors activate currents characteristic of Panx1 channels. We found that the mechanism by which Panx1 channels are activated under this condition involves activation of the TP receptor that is mediated by the cAMP/PKA pathway. This is to our knowledge the first evidence for the involvement of Panx1 in the TP receptor signaling pathway. Future studies aimed to clarify the contribution of this TP-Panx1 signaling network to macrophage immune responses are likely to be important for targeting inflammatory and autoimmune diseases.
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Affiliation(s)
- Hercules A da Silva-Souza
- Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia de Pesquisa Translacional em Saúde e Ambiente da Região Amazônica-INPeTAm, Rio de Janeiro, Brazil; and Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Maria Nathália de Lira
- Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Naman K Patel
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - David C Spray
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Pedro Muanis Persechini
- Instituto de Biofisica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia de Pesquisa Translacional em Saúde e Ambiente da Região Amazônica-INPeTAm, Rio de Janeiro, Brazil; and
| | - Eliana Scemes
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, New York
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6
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Iwasaki R, Tsuge K, Morimoto K, Inazumi T, Kawahara O, Kawahara A, Tsuchiya S, Sugimoto Y. Molecular and pharmacological characterization of zebrafish 'contractile' and 'inhibitory' prostanoid receptors. Biochem Biophys Res Commun 2013; 438:353-8. [PMID: 23892039 DOI: 10.1016/j.bbrc.2013.07.075] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 07/18/2013] [Indexed: 10/26/2022]
Abstract
Prostanoids comprising prostaglandins (PGs) and thromboxanes (TXs) have been shown to play physiological and pathological roles in zebrafish. However, the molecular basis of zebrafish prostanoid receptors has not been established. Here, we demonstrate that there exist at least five 'contractile' (Ca(2+)-mobilizing) and one 'inhibitory' (Gi-coupled) prostanoid receptors in zebrafish; five 'contractile' receptors consisting of two PGE2 receptors (EP1a and EP1b), two PGF2α receptors (FP1 and FP2), and one TXA2 receptor TP, and one 'inhibitory' receptor, the PGE2 receptor EP3. [(3)H]PGE2 specifically bound to the membranes of cells expressing zebrafish EP1a, EP1b and EP3 with a Kd of 4.8, 1.8 and 13.6nM, respectively, and [(3)H]PGF2α specifically bound to the membranes of cells expressing zebrafish FP1 and FP2, with a Kd of 6.5 and 1.6nM, respectively. U-46619, a stable agonist for human and mouse TP receptors, significantly increased the specific binding of [(35)S]GTPγS to membranes expressing the zebrafish TP receptor. Upon agonist stimulation, all six receptors showed an increase in intracellular Ca(2+) levels, although the increase was very weak in EP1b, and pertussis toxin abolished only the EP3-mediated response. Zebrafish EP3 receptor also suppressed forskolin-induced cAMP formation in a pertussis toxin-sensitive manner. In association with the low structural conservation with mammalian receptors, most agonists and antagonists specific for mammalian EP1, EP3 and TP failed to work on each corresponding zebrafish receptor. This work provides further insights into the diverse prostanoid actions mediated by their receptors in zebrafish.
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Affiliation(s)
- Ryo Iwasaki
- Department of Pharmaceutical Biochemistry, Graduate School of Pharmaceutical Sciences, Kumamoto University, Chuo-ku, Kumamoto 862-0973, Japan
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7
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Frey AJ, Ibrahim S, Gleim S, Hwa J, Smyth EM. Biased suppression of TP homodimerization and signaling through disruption of a TM GxxxGxxxL helical interaction motif. J Lipid Res 2013; 54:1678-1690. [PMID: 23493750 DOI: 10.1194/jlr.m036673] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Thromboxane A2 (TXA2) contributes to cardiovascular disease (CVD) by activating platelets and vascular constriction and proliferation. Despite their preclinical efficacy, pharmacological antagonists of the TXA2 receptor (TP), a G protein-coupled receptor, have not been clinically successful, raising interest in novel approaches to modifying TP function. We determined that disruption of a GxxxGxxxL helical interaction motif in the human TP's (α isoform) fifth transmembrane (TM) domain suppressed TP agonist-induced Gq signaling and TPα homodimerization, but not its cell surface expression, ligand affinity, or Gq association. Heterodimerization of TPα with the functionally opposing prostacyclin receptor (IP) shifts TPα to signal via the IP-Gs cascade contributing to prostacyclin's restraint of TXA2 function. Interestingly, disruption of the TPα-TM5 GxxxGxxxL motif did not modify either IP-TPα heterodimerization or its Gs-cAMP signaling. Our study indicates that distinct regions of the TPα receptor direct its homo- and heterodimerization and that homodimerization is necessary for normal TPα-Gq activation. Targeting the TPα-TM5 GxxxGxxxL domain may allow development of biased TPα homodimer antagonists that avoid suppression of IP-TPα heterodimer function. Such novel therapeutics may prove superior in CVD compared with nonselective suppression of all TP functions with TXA2 biosynthesis inhibitors or TP antagonists.
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Affiliation(s)
- Alexander J Frey
- University of Pennsylvania Institute for Translational Medicine and Therapeutics, Smilow Center for Translational Research, Philadelphia, PA; and
| | - Salam Ibrahim
- University of Pennsylvania Institute for Translational Medicine and Therapeutics, Smilow Center for Translational Research, Philadelphia, PA; and
| | - Scott Gleim
- Yale University School of Medicine, Cardiovascular Research Center, Department of Internal Medicine, Section of Cardiovascular Medicine, New Haven, CT
| | - John Hwa
- Yale University School of Medicine, Cardiovascular Research Center, Department of Internal Medicine, Section of Cardiovascular Medicine, New Haven, CT
| | - Emer M Smyth
- University of Pennsylvania Institute for Translational Medicine and Therapeutics, Smilow Center for Translational Research, Philadelphia, PA; and.
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8
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Sparks MA, Makhanova NA, Griffiths RC, Snouwaert JN, Koller BH, Coffman TM. Thromboxane receptors in smooth muscle promote hypertension, vascular remodeling, and sudden death. Hypertension 2012; 61:166-73. [PMID: 23150508 DOI: 10.1161/hypertensionaha.112.193250] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The prostanoid thromboxane A2 has been implicated to contribute to the pathogenesis of many cardiovascular diseases, including hypertension. To study the role of vascular thromboxane-prostanoid (TP) receptors in blood pressure regulation, we generated mice with cell-specific deletion of TP receptors in smooth muscle using Cre/Loxp technology. We crossed the KISM22α-Cre transgenic mouse line expressing Cre recombinase in smooth muscle cells with a mouse line bearing a conditional allele of the Tbxa2r gene (Tp(flox)). In KISM22α-Cre(+)Tp(flox/flox) (TP-SMKO) mice, TP receptors were efficiently deleted from vascular smooth muscle cells. In TP-SMKOs, acute vasoconstrictor responses to the TP agonist U46619 were attenuated to a similar extent in both the peripheral and renal circulations. Yet, acute vascular responses to angiotensin II were unaffected at baseline and after chronic angiotensin II administration. Infusion of high-dose U46619 caused circulatory collapse and death in a majority of control mice but had negligible hemodynamic effects in TP-SMKOs, which were completely protected from U46619-induced sudden death. Baseline blood pressures were normal in TP-SMKOs. However, the absence of TP receptors in vascular smooth muscle cells was associated with significant attenuation of angiotensin II-induced hypertension and diminished vascular remodeling. This was also associated with reduced urinary thromboxane production after chronic angiotensin II. Thus, TP receptors in vascular smooth muscle cells play a major role in mediating the actions of thromboxane A(2) in TP agonist-induced shock, hypertension, and vascular remodeling of the aorta.
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Affiliation(s)
- Matthew A Sparks
- Division of Nephrology and Department of Medicine, Duke University, Durham, NC 27710, USA
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9
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Mohan S, Ahmad AS, Glushakov AV, Chambers C, Doré S. Putative role of prostaglandin receptor in intracerebral hemorrhage. Front Neurol 2012; 3:145. [PMID: 23097645 PMCID: PMC3477820 DOI: 10.3389/fneur.2012.00145] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2012] [Accepted: 09/30/2012] [Indexed: 01/21/2023] Open
Abstract
Each year, approximately 795,000 people experience a new or recurrent stroke. Of all strokes, 84% are ischemic, 13% are intracerebral hemorrhage (ICH) strokes, and 3% are subarachnoid hemorrhage strokes. Despite the decreased incidence of ischemic stroke, there has been no change in the incidence of hemorrhagic stroke in the last decade. ICH is a devastating disease 37–38% of patients between the ages of 45 and 64 die within 30 days. In an effort to prevent ischemic and hemorrhagic strokes we and others have been studying the role of prostaglandins and their receptors. Prostaglandins are bioactive lipids derived from the metabolism of arachidonic acid. They sustain homeostatic functions and mediate pathogenic mechanisms, including the inflammatory response. Most prostaglandins are produced from specific enzymes and act upon cells via distinct G-protein coupled receptors. The presence of multiple prostaglandin receptors cross-reactivity and coupling to different signal transduction pathways allow differentiated cells to respond to prostaglandins in a unique manner. Due to the number of prostaglandin receptors, prostaglandin-dependent signaling can function either to promote neuronal survival or injury following acute excitotoxicity, hypoxia, and stress induced by ICH. To better understand the mechanisms of neuronal survival and neurotoxicity mediated by prostaglandin receptors, it is essential to understand downstream signaling. Several groups including ours have discovered unique roles for prostaglandin receptors in rodent models of ischemic stroke, excitotoxicity, and Alzheimer disease, highlighting the emerging role of prostaglandin receptor signaling in hemorrhagic stroke with a focus on cyclic-adenosine monophosphate and calcium (Ca2+) signaling. We review current ICH data and discuss future directions notably on prostaglandin receptors, which may lead to the development of unique therapeutic targets against hemorrhagic stroke and brain injuries alike.
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Affiliation(s)
- Shekher Mohan
- Department of Anesthesiology, College of Medicine, University of Florida Gainesville, FL, USA
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10
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Abstract
Potent, oxygenated lipid molecules called prostanoids regulate a wide variety of physiological responses and pathological processes. Prostanoids are produced by various cell types and act on target cells through specific G protein-coupled receptors. Although prostanoids have historically been considered acute inflammation mediators, studies using specific receptor knockout mice indicate that prostanoids, in fact, regulate various aspects of both innate and adaptive immunity. Each prostanoid, depending on which receptor it acts on, exerts specific effects on immune cells such as macrophages, dendritic cells, and T and B lymphocytes, often in concert with microbial ligands and cytokines, to affect the strength, quality, and duration of immune responses. Prostanoids are also relevant to immunopathology, from inflammation to autoimmunity and cancer. Here, we review the role of prostanoids in regulating immunity, their involvement in immunopathology, and areas of insight that may lead to new therapeutic opportunities.
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Affiliation(s)
- Takako Hirata
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto, Japan
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11
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Cyphert JM, Allen IC, Church RJ, Latour AM, Snouwaert JN, Coffman TM, Koller BH. Allergic inflammation induces a persistent mechanistic switch in thromboxane-mediated airway constriction in the mouse. Am J Physiol Lung Cell Mol Physiol 2011; 302:L140-51. [PMID: 21984570 DOI: 10.1152/ajplung.00152.2011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Actions of thromboxane (TXA(2)) to alter airway resistance were first identified over 25 years ago. However, the mechanism underlying this physiological response has remained largely undefined. Here we address this question using a novel panel of mice in which expression of the thromboxane receptor (TP) has been genetically manipulated. We show that the response of the airways to TXA(2) is complex: it depends on expression of other G protein-coupled receptors but also on the physiological context of the signal. In the healthy airway, TXA(2)-mediated airway constriction depends on expression of TP receptors by smooth muscle cells. In contrast, in the inflamed lung, the direct actions of TXA(2) on smooth muscle cell TP receptors no longer contribute to bronchoconstriction. Instead, in allergic lung disease, TXA(2)-mediated airway constriction depends on neuronal TP receptors. Furthermore, this mechanistic switch persists long after resolution of pulmonary inflammation. Our findings demonstrate the powerful ability of lung inflammation to modify pathways leading to airway constriction, resulting in persistent changes in mechanisms of airway reactivity to key bronchoconstrictors. Such alterations are likely to shape the pathogenesis of asthmatic lung disease.
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Affiliation(s)
- Jaime M Cyphert
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7264, USA
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Affiliation(s)
- Takako Hirata
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Shuh Narumiya
- Department of Pharmacology, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
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13
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Smyth EM. Thromboxane and the thromboxane receptor in cardiovascular disease. ACTA ACUST UNITED AC 2010; 5:209-219. [PMID: 20543887 DOI: 10.2217/clp.10.11] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Thromboxane A(2) (TXA(2)), the primary product of COX-1-dependent metabolism of arachidonic acid, mediates its biological actions through the TXA(2) receptor, termed the TP. Irreversible inhibition of platelet COX-1-derived TXA(2) with low-dose aspirin affords protection against primary and secondary vascular thrombotic events, underscoring the central role of TXA(2) as a platelet agonist in cardiovascular disease. The limitations associated with aspirin use include significant gastrointestinal toxicity, bleeding complications, potential interindividual response variability and poor efficacy in some disease states. This, together with the broad role of TXA(2) in cardiovascular disease beyond the platelet, has refocused interest towards additional TXA(2)-associated drug targets, in particular TXA(2) synthase and the TP. The superiority of these agents over low-dose aspirin, in terms of clinical efficacy, tolerability and commercial viability, remain open questions that are the focus of ongoing research.
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Affiliation(s)
- Emer M Smyth
- Institute for Translation Medicine & Therapeutics, University of Pennsylvania, 421 Curie Blvd, 808 BRB 2/3, Philadelphia, PA 19104, USA Tel.: +1 215 573 2323
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Sakariassen KS, Alberts P, Fontana P, Mann J, Bounameaux H, Sorensen AS. Effect of pharmaceutical interventions targeting thromboxane receptors and thromboxane synthase in cardiovascular and renal diseases. Future Cardiol 2009; 5:479-93. [DOI: 10.2217/fca.09.33] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The present review focuses on the roles of thromboxane A2 (TxA2) in arterial thrombosis, atherogenesis, vascular stent-related ischemic events and renal proteinuria. Particular emphasis is laid on therapeutic interventions targeting the TxA2 (TP) receptors and TxA2 synthase (TS), including dual TP-receptor antagonists and TS inhibitors. Their significant inhibitory efficacies on arterial thrombogenesis, atherogenesis, restenosis after stent placement, vasoconstriction and proteinuria indicate novel and improved treatments for cardiovascular and selected renal diseases. New therapeutic interventions of the TxA2 pathway may also be beneficial for patients with poor biological antiplatelet drug response, for example, to aspirin and/or clopidogrel. These new TP/TS agents offer novel improved treatments to efficiently and simultaneously interfere with thrombogenesis and atherogenesis, and to enlarge the existing panel of platelet inhibitors for efficient prophylaxis and treatment of arterial thrombosis and renal proteinuria.
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Affiliation(s)
| | | | - Pierre Fontana
- Division of Angiology & Haemostasis, Faculty of Medicine, University, Hospitals of Geneva, CH-1211 Geneva, Switzerland
| | - Jessica Mann
- Cardiovascular Development Consulting GmbH, Hirzbodenweg 5, CH-4052, Basel, Switzerland
| | - Henri Bounameaux
- Division of Angiology & Haemostasis, Faculty of Medicine, University, Hospitals of Geneva, CH-1211 Geneva, Switzerland
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15
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Shimizu T, Yokotani K. Effects of centrally administered prostaglandin E(3) and thromboxane A(3) on plasma noradrenaline and adrenaline in rats: comparison with prostaglandin E(2) and thromboxane A(2). Eur J Pharmacol 2009; 611:30-4. [PMID: 19344706 DOI: 10.1016/j.ejphar.2009.03.057] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 03/10/2009] [Accepted: 03/23/2009] [Indexed: 10/21/2022]
Abstract
Previously, we reported the involvement of brain omega-6 prostanoids, especially prostaglandin E(2) and thromboxane A(2), in the activation of central sympatho-adrenomedullary outflow in rats. omega-3 Prostanoids, including prostaglandin E(3) and thromboxane A(3), are believed to be less bioactive than omega-6 prostanoids, although studies on the functions of omega-3 prostanoids in the central nervous system have not been reported. In the present study, therefore, we compared the effects of centrally administered omega-3 prostanoids, prostaglandin E(3) and thromboxane A(3), with those of omega-6 prostanoids, prostaglandin E(2) and thromboxane A(2), on the plasma catecholamines in anesthetized rats. Intracerebroventricularly (i.c.v.) administered prostaglandin E(2) (0.15, 0.3 and 1.5 nmol/animal) and prostaglandin E(3) (0.3 and 3 nmol/animal) predominantly elevated plasma noradrenaline but not adrenaline, but the latter was less efficient than the former. On the other hand, U-46619 (an analog of thromboxane A(2)) (30, 100 and 300 nmol/animal, i.c.v.) and Delta(17)-U-46619 (an analog of thromboxane A(3)) (100 and 300 nmol/animal, i.c.v.) both elevated plasma catecholamines (adrenaline>>noradrenaline) to the same degree. These results suggest that centrally administered prostaglandin E(3) is less effective than prostaglandin E(2) to elevate plasma noradrenaline, and that thromboxane A(3) is almost as equipotent as thromboxane A(2) to elevate plasma catecholamines in rats.
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Affiliation(s)
- Takahiro Shimizu
- Department of Pharmacology, School of Medicine, Kochi University, Nankoku, Kochi, Japan.
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16
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Nakahata N. Thromboxane A2: physiology/pathophysiology, cellular signal transduction and pharmacology. Pharmacol Ther 2008; 118:18-35. [PMID: 18374420 DOI: 10.1016/j.pharmthera.2008.01.001] [Citation(s) in RCA: 305] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2007] [Accepted: 01/02/2008] [Indexed: 12/22/2022]
Abstract
Thromboxane A(2) (TXA(2)), an unstable arachidonic acid metabolite, elicits diverse physiological/pathophysiological actions, including platelet aggregation and smooth muscle contraction. TXA(2) has been shown to be involved in allergies, modulation of acquired immunity, atherogenesis, neovascularization, and metastasis of cancer cells. The TXA(2) receptor (TP) communicates mainly with G(q) and G(13), resulting in phospholipase C activation and RhoGEF activation, respectively. In addition, TP couples with G(11), G(12), G(13), G(14), G(15), G(16), G(i), G(s) and G(h). TP is widely distributed in the body, and is expressed at high levels in thymus and spleen. The second extracellular loop of TP is an important ligand-binding site, and Asp(193) is a key amino acid. There are two alternatively spliced isoforms of TP, TPalpha and TPbeta, which differ only in their C-terminals. TPalpha and TPbeta communicate with different G proteins, and undergo hetero-dimerization, resulting in changes in intracellular traffic and receptor protein conformations. TP cross-talks with receptor tyrosine kinases, such as EGF receptor, to induce cell proliferation and differentiation. TP is glycosylated in the N-terminal region for recruitment to plasma membranes. Furthermore, TP conformation is changed by coupling to G proteins, showing several states of agonist binding. Finally, several drugs modify TP-mediated events; these include cyclooxygenase inhibitors, TXA(2) synthase inhibitors and TP antagonists. Some flavonoids of natural origin also have TP receptor antagonistic activity. Recent advances in TP research have clarified TXA(2)-mediated events in detail, and further study will supply more beneficial information about TXA(2) pathophysiology.
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Affiliation(s)
- Norimichi Nakahata
- Department of Cellular Signaling, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba 6-3, Aramaki, Aoba-ku, Sendai 980-0815, Japan
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17
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Zhuge X, Arai H, Xu Y, Murayama T, Kobayashi T, Narumiya S, Kita T, Yokode M. Protection of atherogenesis in thromboxane A2 receptor-deficient mice is not associated with thromboxane A2 receptor in bone marrow-derived cells. Biochem Biophys Res Commun 2006; 351:865-71. [PMID: 17097058 DOI: 10.1016/j.bbrc.2006.10.121] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2006] [Accepted: 10/23/2006] [Indexed: 10/24/2022]
Abstract
In the previous study, we generated mice lacking thromboxane A2 receptor (TP) and apolipoprotein E, apoE(-/-)TP(-/-) mice, and reported that the double knockout mice developed markedly smaller atherosclerotic lesions than those in apoE(-/-) mice. To investigate the mechanism responsible for reduced atherosclerosis in apoE(-/-)TP(-/-) mice, we examined the role of TP in bone marrow (BM)-derived cells in the development of the atherosclerotic lesions. When we compared the function of macrophages in apoE(-/-) and in apoE(-/-)TP(-/-) mouse in vitro, there was no difference in the expression levels of cytokines and chemokines after stimulation with lipopolysaccharide. We then transplanted the BM from either apoE(-/-) or apoE(-/-)TP(-/-) mice to either apoE(-/-) or apoE(-/-)TP(-/-) mice after sublethal irradiation. After 12 weeks with high fat diet, we analyzed the atherosclerotic lesion of aortic sinus. When the BM from apoE(-/-) or apoE(-/-)TP(-/-) mice was transplanted to apoE(-/-) mice, the lesion size was almost the same as that of apoE(-/-) mice without BM transplantation. In contrast, when the BM from apoE(-/-) or apoE(-/-)TP(-/-) mice was transplanted to apoE(-/-)TP(-/-) mice, the lesion size was markedly reduced. These results indicate that the protection of atherogenesis in TP(-/-) mice is not associated with TP in BM-derived cells.
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Affiliation(s)
- Xin Zhuge
- Department of Clinical Innovative Medicine, Kyoto University Graduate School of Medicine, 54 Kawahara-cho, Shogoin, Sakyo-ku, Kyoto 606-8507, Japan
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18
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Yalcin M, Cavun S, Yilmaz MS, Savci V. Activation of the central cholinergic system mediates the reversal of hypotension by centrally administrated U-46619, a thromboxane A2 analog, in hemorrhaged rats. Brain Res 2006; 1118:43-51. [PMID: 16962568 DOI: 10.1016/j.brainres.2006.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 07/31/2006] [Accepted: 08/04/2006] [Indexed: 11/25/2022]
Abstract
In the present study, we investigated the role of the central cholinergic system in mediating the pressor effect of intracerebroventricularly administrated U-46619, a thromboxane A2 (TxA2) analog, in hemorrhaged hypotensive rats. Hemorrhage was performed by withdrawing a total volume of 2.1 ml of blood per 100 g body weight over a period of 10 min. Intracerebroventricular (i.c.v.) injection of U-46619 (0.5, 1, 2 micro g) produced a dose- and time-dependent increase in arterial pressure and reversed the hypotension of this condition. Hemorrhage caused small increases in extracellular hypothalamic acetylcholine and choline levels. Intracerebroventricular administration of U-46619 (1 micro g) further increased the levels of extracellular acetylcholine and choline by 57% and 41%, respectively. Pretreatment with SQ-29548 (8 mug; i.c.v.), a selective TxA2 receptor antagonist, completely abrogated the effects of subsequent injection of U-46619 (1 mug; i.c.v.) on arterial pressure and extracellular acetylcholine and choline levels. Pretreatment with mecamylamine (50 micro g; i.c.v.), a cholinergic nonselective nicotinic receptor antagonist, attenuated the pressor effect of U-46619 (1 micro g, i.c.v.) in hemorrhaged rats whereas pretreatment with atropine (10 micro g; i.c.v.), a cholinergic nonselective muscarinic receptor antagonist, had no effect. Interestingly, pretreatment of rats with methyllycaconitine (10 micro g; i.c.v.) or alpha-bungarotoxin (10 micro g; i.c.v.), selective antagonists of alpha-7 subtype nicotinic acetylcholine receptors (alpha7nAChRs), partially abolished the pressor effect of U-46619 (1 micro g; i.c.v.) in the hypotensive condition. Pretreatment with a combination of mecamylamine plus methyllycaconitine or mecamylamine plus alpha-bungarotoxin attenuated the reversal effect of U-46619, but only to the same extent as pretreatment with either antagonist alone. In conclusion, i.c.v. administration of U-46619 restores arterial pressure and increases posterior hypothalamic acetylcholine and choline levels by activating central TxA2 receptors in hemorrhaged hypotensive rats. The activation of central nicotinic cholinergic receptors, predominantly alpha7nAChRs, partially acts as a mediator in the pressor responses to i.c.v. injection of U-46619 under these conditions.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Acetylcholine/metabolism
- Animals
- Blood Pressure/drug effects
- Blood Pressure/physiology
- Bridged Bicyclo Compounds, Heterocyclic
- Cholinergic Fibers/drug effects
- Cholinergic Fibers/metabolism
- Disease Models, Animal
- Dose-Response Relationship, Drug
- Extracellular Fluid/drug effects
- Extracellular Fluid/metabolism
- Fatty Acids, Unsaturated
- Hemorrhage/complications
- Hemorrhage/physiopathology
- Hydrazines/pharmacology
- Hypotension/drug therapy
- Hypotension/etiology
- Hypotension/physiopathology
- Hypothalamus, Posterior/drug effects
- Hypothalamus, Posterior/metabolism
- Injections, Intraventricular
- Male
- Neural Pathways/drug effects
- Neural Pathways/metabolism
- Nicotinic Antagonists/pharmacology
- Rats
- Rats, Sprague-Dawley
- Receptors, Nicotinic/drug effects
- Receptors, Nicotinic/metabolism
- Receptors, Thromboxane A2, Prostaglandin H2/antagonists & inhibitors
- Receptors, Thromboxane A2, Prostaglandin H2/metabolism
- Thromboxane A2/analogs & derivatives
- Time Factors
- Vasoconstrictor Agents/pharmacology
- alpha7 Nicotinic Acetylcholine Receptor
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Affiliation(s)
- Murat Yalcin
- Uludag University Veterinary Faculty, Department of Physiology, 16059, Görükle, Bursa, Turkey
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19
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Abstract
Cyclooxygenase (COX) enzymes catalyse the biotransformation of arachidonic acid to prostaglandins which subserve important functions in cardiovascular homeostasis. Prostacyclin (PGI2) and prostaglandin (PG)E2, dominant products of COX activityin macro- and microvascular endothelial cells, respectively, in vitro, modulate the interaction of blood cells with the vasculature and contribute to the regulation of blood pressure. COXs are the target for inhibition by nonsteroidal anti-inflammatory drugs (NSAIDs--which include those selective for COX-2) and for aspirin. Modulation of the interaction between COX products of the vasculature and platelets underlies both the cardioprotection afforded by aspirin and the cardiovascular hazard which characterises specific inhibitors of COX-2.
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Affiliation(s)
- K Egan
- Institute for Translational Medicine and Therapeutics, School of Medicine, University of Pennsylvania, 153 Johnson Pavilion, Philadelphia, PA 19104, USA
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20
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Laroche G, Lépine MC, Thériault C, Giguère P, Giguère V, Gallant MA, de Brum-Fernandes A, Parent JL. Oligomerization of the alpha and beta isoforms of the thromboxane A2 receptor: relevance to receptor signaling and endocytosis. Cell Signal 2005; 17:1373-83. [PMID: 15893915 DOI: 10.1016/j.cellsig.2005.02.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2004] [Revised: 02/10/2005] [Accepted: 02/15/2005] [Indexed: 11/19/2022]
Abstract
Thromboxane A(2) (TXA(2)) is a potent mediator of inflammation, vasoconstriction and oxidative stress. The TXA(2) receptor (TP) is a G protein-coupled receptor (GPCR) that is expressed as two alternatively spliced isoforms, alpha (343 residues) and beta (407 residues) that share the first 328 residues. For many years GPCRs were assumed to exist and function as monomeric species, but increasing evidence suggests that a dimer is the minimal functional unit of GPCRs. In the present report, using co-immunoprecipitation of differentially tagged TP expressed in HEK293 cells, we demonstrate that TPalpha and TPbeta form homo- and hetero-oligomers. Immunoblotting of lysates from human platelets with an anti-TP specific antibody revealed the presence of endogenously expressed TP oligomers. We show that TP oligomerization is an agonist-independent process highly affected by the reducing agent dithiothreitol suggesting the involvement of disulfide bonds in TP oligomerization. Over-expression of G protein-coupled receptor kinases and arrestins did not modulate the extent of receptor dimerization/oligomerization. Co-expression of two TP signaling-deficient mutants, R60L and E2402R, resulted in rescuing of receptor signal transduction suggesting that dimers/oligomers constitute the functional units of this receptor. Interestingly, TPalpha which does not undergo constitutive or agonist-induced endocytosis on its own was subjected to both types of endocytosis when co-expressed with TPbeta, indicating that TPalpha can display intracellular trafficking when complexed through hetero-oligomerization with TPbeta.
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Affiliation(s)
- Geneviève Laroche
- Service de Rhumatologie, Faculté de Médecine and Centre de Recherche Clinique, Université de Sherbrooke, Fleurimont, Qc, Canada J1H 5N4
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21
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Rocha PN, Plumb TJ, Robinson LA, Spurney R, Pisetsky D, Koller BH, Coffman TM. Role of thromboxane A2 in the induction of apoptosis of immature thymocytes by lipopolysaccharide. CLINICAL AND DIAGNOSTIC LABORATORY IMMUNOLOGY 2005; 12:896-903. [PMID: 16085905 PMCID: PMC1182190 DOI: 10.1128/cdli.12.8.896-903.2005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Lipopolysaccharide (LPS) causes apoptotic deletion of CD4(+) CD8(+) thymocytes, a phenomenon that has been linked to immune dysfunction and poor survival during sepsis. Given the abundance of thromboxane-prostanoid (TP) receptors in CD4(+) CD8(+) thymocytes and in vitro evidence that thromboxane A(2) (TXA(2)) causes apoptosis of these cells, we tested whether enhanced generation of TXA(2) plays a role in LPS-induced thymocyte apoptosis. Mice injected with 50 micro LPS intraperitoneally displayed a marked increase in generation of TXA(2) and prostaglandin E(2) in the thymus as well as apoptotic deletion of CD4(+) CD8(+) thymocytes. Administration of indomethacin or rofecoxib inhibited prostanoid synthesis but did not affect thymocyte death. In contrast, thymocyte apoptosis in response to LPS was significantly attenuated in TP-deficient mice. These studies indicate that TXA(2) mediates a portion of apoptotic thymocyte death caused by LPS. The absence of an effect of global inhibition of prostanoid synthesis suggests a complex role for prostanoids in this model.
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Affiliation(s)
- Paulo N Rocha
- Division of Nephrology, Duke University, Durham VA Medical Centers, Durham, North Carolina 27705, USA
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22
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Rocha PN, Carvalho EM. Prostanoids modulate inflammation and alloimmune responses during graft rejection. Braz J Med Biol Res 2005; 38:1759-68. [PMID: 16302090 DOI: 10.1590/s0100-879x2005001200004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Acute rejection of a transplanted organ is characterized by intense inflammation within the graft. Yet, for many years transplant researchers have overlooked the role of classic mediators of inflammation such as prostaglandins and thromboxane (prostanoids) in alloimmune responses. It has been demonstrated that local production of prostanoids within the allograft is increased during an episode of acute rejection and that these molecules are able to interfere with graft function by modulating vascular tone, capillary permeability, and platelet aggregation. Experimental data also suggest that prostanoids may participate in alloimmune responses by directly modulating T lymphocyte and antigen-presenting cell function. In the present paper, we provide a brief overview of the alloimmune response, of prostanoid biology, and discuss the available evidence for the role of prostaglandin E2 and thromboxane A2 in graft rejection.
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Affiliation(s)
- P N Rocha
- Serviço de Imunologia, Hospital Universitário Professor Edgard Santos, Faculdade de Medicina, Universidade Federal da Bahia, Rua João das Botas s/n, 40110-160 Salvador, BA, Brazil.
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23
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Allen IC, Hartney JM, Coffman TM, Penn RB, Wess J, Koller BH. Thromboxane A2 induces airway constriction through an M3 muscarinic acetylcholine receptor-dependent mechanism. Am J Physiol Lung Cell Mol Physiol 2005; 290:L526-33. [PMID: 16243899 DOI: 10.1152/ajplung.00340.2005] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Thromboxane A2 (TXA2) is a potent lipid mediator released by platelets and inflammatory cells and is capable of inducing vasoconstriction and bronchoconstriction. In the airways, it has been postulated that TXA2 causes airway constriction by direct activation of thromboxane prostanoid (TP) receptors on airway smooth muscle cells. Here we demonstrate that although TXA2 can mediate a dramatic increase in airway smooth muscle constriction and lung resistance, this response is largely dependent on vagal innervation of the airways and is highly sensitive to muscarinic acetylcholine receptor (mAChR) antagonists. Further analyses employing pharmacological and genetic strategies demonstrate that TP-dependent changes in lung resistance and airway smooth muscle tension require expression of the M2 mAChR subtype. These results raise the possibility that some of the beneficial actions of anticholinergic agents used in the treatment of asthma and chronic obstructive pulmonary disease result from limiting physiological changes mediated through the TP receptor. Furthermore, these findings demonstrate a unique pathway for TP regulation of homeostatic mechanisms in the airway and suggest a paradigm for the role of TXA2 in other organ systems.
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Affiliation(s)
- Irving C Allen
- Curriculum in Genetics and Molecular Biology, Univ. of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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24
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Harenberg A, Girkontaite I, Giehl K, Fischer KD. The Lsc RhoGEF mediates signaling from thromboxane A2 to actin polymerization and apoptosis in thymocytes. Eur J Immunol 2005; 35:1977-86. [PMID: 15884057 DOI: 10.1002/eji.200425769] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The Lsc RhoGEF (also known as p115-RhoGEF) is a GTP exchange factor (GEF), an activator of GTPases of the Rho family. Lsc has a RhoGEF domain specific for Rho GTPase and a regulator of G protein signaling (RGS) domain specific for Galpha(12/13) subunits. One G protein receptor that can couple to Galpha(12/13) subunits is the receptor for thromboxane A(2 )(TXA(2)), thromboxane-prostanoid (called TP), which is highly expressed in immature thymocytes. TXA(2) has been implicated in thymocyte apoptosis. We found that Lsc(-/-) mice on a BALB/c background show thymic hyperplasia due to increased numbers of thymocytes and that these numbers further increase with the age of the mice. To investigate a role for Lsc in TXA(2) signaling, we analyzed activation of primary thymocytes by TXA(2) in vitro. TXA(2)-induced apoptosis of double-positive thymocytes and Rho activation required Lsc, and TXA(2) stimulation of actin polymerization and cofilin phosphorylation required both Lsc and Rho kinase (ROCK). Additionally, in the absence of Lsc, phosphorylation of the survival kinase Akt in response to TXA(2) was greatly enhanced. Together, these data demonstrate that Lsc is essential for mediating TXA(2 )signaling involved in apoptosis and actin organization and suggest that TXA(2) regulates thymic cellularity via Lsc.
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Affiliation(s)
- Anke Harenberg
- Department of Physiological Chemistry, University of Ulm, Ulm, Germany
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25
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Pfister SL, Pratt PE, Kurian J, Campbell WB. Glibenclamide inhibits thromboxane-mediated vasoconstriction by thromboxane receptor blockade. Vascul Pharmacol 2004; 40:285-92. [PMID: 15063832 DOI: 10.1016/j.vph.2004.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2003] [Revised: 07/15/2003] [Accepted: 02/23/2004] [Indexed: 11/30/2022]
Abstract
Because sulfonylureas, such as glibenclamide, are used to treat Type 2 diabetes and because this disease is associated with various cardiovascular complications that may be mediated by thromboxane (TX), this study was designed to characterize the role of glibenclamide on TX-mediated contractions in isolated ring segments of bovine coronary arteries and rabbit aortas. A series of TXA(2) analogs [9,11 Dideoxy-9alpha, 11alpha-methanoepoxy prostaglandin F(2alpha) (U46619), [1S-(1alpha, 2beta(5Z),3alpha(1E, 3R*),4alpha)]-7-[3-(3-hydroxy-4-(4'-iodophenoxy)-1-butenyl)-7-oxabicyclo [2.2.1]heptan-2-yl]-5-heptenoic acid (I-BOP), carbocyclic TXA(2) (CTA(2)) and 9,11-dideoxy-9alpha,11alpha-epoxymethano prostaglandin F(2alpha) (U44069)], endothelin and phenylephrine contracted both types of blood vessels. Glibenclamide (10 microM) inhibited the contraction to each of the TX agonists but had no effect on endothelin- or phenylephrine-induced contractions. We hypothesized that this effect was due to a direct effect to block the vascular smooth muscle cell TX receptor. Receptor binding studies were performed in rabbit vascular smooth muscle cells and indicated that glibenclamide (10 microM) inhibited (125)I-BOP binding by more than 80%. The inhibition constants or K(i) for glibenclamide was 0.53 microM. These studies provide the first evidence that the ability of glibenclamide to inhibit TX-mediated contractions occurs independent of the vascular K(ATP) channel and is, instead, mediated by the blockade of the vascular TX receptor.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Adenosine Triphosphate/physiology
- Animals
- Aorta, Thoracic/drug effects
- Aorta, Thoracic/physiology
- Bridged Bicyclo Compounds, Heterocyclic/pharmacology
- Cattle
- Coronary Vessels/drug effects
- Coronary Vessels/physiology
- Fatty Acids, Unsaturated/pharmacology
- Glyburide/pharmacology
- In Vitro Techniques
- Male
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Muscle, Smooth, Vascular/physiology
- Potassium Channels/drug effects
- Potassium Channels/physiology
- Prostaglandin Endoperoxides, Synthetic/pharmacology
- Rabbits
- Radioligand Assay
- Receptors, Thromboxane/antagonists & inhibitors
- Receptors, Thromboxane/metabolism
- Thromboxane A2/analogs & derivatives
- Thromboxane A2/pharmacology
- Thromboxane A2/physiology
- Vasoconstriction/drug effects
- Vasoconstrictor Agents/pharmacology
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Affiliation(s)
- Sandra L Pfister
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
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26
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Sato Y, Kitasato H, Murakami Y, Hashimoto A, Endo H, Kondo H, Inoue M, Hayashi I. Down-regulation of lipoxin A4 receptor by thromboxane A2 signaling in RAW246.7 cells in vitro and bleomycin-induced lung fibrosis in vivo. Biomed Pharmacother 2004; 58:381-7. [PMID: 15271420 DOI: 10.1016/j.biopha.2004.05.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Accepted: 05/05/2004] [Indexed: 01/25/2023] Open
Abstract
Lipoxins (LXs) are members of eicosanoid family that can be endogenously produced during cell-to-cell interactions such as platelet-leukocyte interactions. Anti-inflammatory function of lipoxin A4 (LXA4) as "braking signals" is mediated by the receptor. On the other hand, thromboxane A2 (TXA2) produced by catalysis of cyclooxygenase and thromboxane synthetase is released during platelet aggregation as a vasoconstrictor and a pro-inflammatory factor. To investigate interaction of TXA2 receptor (TP) and LXA4 receptor, effects of a TP agonist and a thromboxane synthetase inhibitor on expression of LXA4 receptor were examined in vitro and in vivo. A TP agonist, U46619 showed a down-regulation of LXA4 receptor induced by interleukin-1beta (IL-1beta) in RAW246.7 cells. In bleomycin-induced lung fibrosis in mice, administration of a thromboxane synthetase inhibitor DP-1904 increased LXA4 receptor mRNA and decreased type I collagen mRNA. In vitro experiments indicate that LXA4 significantly prevented enhanced proliferation of NIH3T3 fibroblasts and the collagen expression by transforming growth factor-beta (TGF-beta). These results suggest that TXA2-TP signaling could cause negative regulation of lipoxin A4 receptor under the transcriptional level during inflammatory process mediated by IL-1beta and TGF-beta induce the expression of LXA4 receptor. Furthermore, the down-regulation of LXA4 receptor by TXA2 implies a possibility that a cellular signaling by TXA2 may have a novel and potential function as a pro-inflammatory factor to inhibit anti-inflammatory effect of LXA4. Concomitantly, selective blockade of TXA2-TP signaling could be suggested to lead to anti-inflammation through active role of LXA4.
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Affiliation(s)
- Yoshinori Sato
- Department of Microbiology, School of Medicine, Kitasato University, 1-15-1, Sagamihara-shi, Kanagawa 228-8555, Japan
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27
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Thomas DW, Rocha PN, Nataraj C, Robinson LA, Spurney RF, Koller BH, Coffman TM. Proinflammatory actions of thromboxane receptors to enhance cellular immune responses. THE JOURNAL OF IMMUNOLOGY 2004; 171:6389-95. [PMID: 14662837 DOI: 10.4049/jimmunol.171.12.6389] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Metabolism of arachidonic acid by the cyclo-oxygenase (COX) pathway generates a family of prostanoid mediators. Nonsteroidal anti-inflammatory drugs (NSAIDs) act by inhibiting COX, thereby reducing prostanoid synthesis. The efficacy of these agents in reducing inflammation suggests a dominant proinflammatory role for the COX pathway. However, the actions of COX metabolites are complex, and certain prostanoids, such as PGE(2), in some circumstances actually inhibit immune and inflammatory responses. In these studies, we examine the hypothesis that anti-inflammatory actions of NSAIDs may be due, in part, to inhibition of thromboxane A(2) synthesis. To study the immunoregulatory actions of thromboxane A(2), we used mice with a targeted disruption of the gene encoding the thromboxane-prostanoid (TP) receptor. Both mitogen-induced responses and cellular responses to alloantigen were substantially reduced in TP(-/-) spleen cells. Similar attenuation was observed with pharmacological inhibition of TP signaling in wild-type splenocytes, suggesting that reduced responsiveness was not due to subtle developmental abnormalities in the TP-deficient mice. The absence of TP receptors reduced immune-mediated tissue injury following cardiac transplant rejection, an in vivo model of intense inflammation. Taken together, these findings show that thromboxane augments cellular immune responses and inflammatory tissue injury. Specific inhibition of the TP receptor may provide a more precise approach to limit inflammation without some of the untoward effects associated with NSAIDs.
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MESH Headings
- Adjuvants, Immunologic/deficiency
- Adjuvants, Immunologic/genetics
- Adjuvants, Immunologic/physiology
- Animals
- Calcium Signaling/genetics
- Calcium Signaling/immunology
- Cell Division/genetics
- Cell Division/immunology
- Cells, Cultured
- Enzyme Inhibitors/pharmacology
- Graft Rejection/genetics
- Graft Rejection/immunology
- Graft Rejection/pathology
- Heart Transplantation/immunology
- Heart Transplantation/pathology
- Immunity, Cellular/genetics
- Inflammation Mediators/metabolism
- Inflammation Mediators/physiology
- Lymphocyte Culture Test, Mixed
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Receptors, Thromboxane/biosynthesis
- Receptors, Thromboxane/deficiency
- Receptors, Thromboxane/genetics
- Receptors, Thromboxane/physiology
- Ribonucleases/metabolism
- Spleen/cytology
- Spleen/enzymology
- Spleen/immunology
- Spleen/metabolism
- T-Lymphocytes/cytology
- T-Lymphocytes/enzymology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- Thromboxane-A Synthase/antagonists & inhibitors
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Affiliation(s)
- Dennis W Thomas
- Division of Nephrology, Duke University and Durham Veterans Affairs Medical Centers, Durham, NC 27705, USA
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28
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Abstract
Prostanoids including prostaglandins (PGs) and thromboxanes (TX) are a group of lipid mediators formed and released in response to various, often noxious, stimuli. While the roles of prostanoids in acute inflammatory responses are well known and have been extensively studied, it is generally believed that they play very little in immunity. This is partly because non-steroidal anti-inflammatory drugs that inhibit prostanoid synthesis have little effects on immune processes in vivo. Prostanoids exert their actions by acting on a family of G-protein-coupled receptors. They include PGD receptor, EP1, EP2, EP3 and EP4 subtypes of PGE receptor, PGF receptor, PGI receptor and TX receptor. We generated mice deficient in each of these prostanoid receptors individually, and examined their roles under various pathological conditions. These studies have revealed that prostanoids works at various sites or levels of immune responses and exert many, often opposing, actions. For example, using EP4-deficient mice, we found that stimulation of the PGE(2)-EP4 signaling in dendritic cells facilitates their migration and maturation, while the stimulation of the same pathway in T cells potently suppresses their activation and proliferation. The latter action is evident in PGE(2)-mediated suppression of T cell proliferation in the gut of mice subjected to dextran sodium sulfate-induced colitis, a model of inflammatory bowel disease. Here I summarize our findings obtained by these and other studies. These findings suggest that selective manipulation of the prostanoid receptors may be beneficial in treatment of certain immunological disorders.
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Affiliation(s)
- Shuh Narumiya
- Department of Pharmacology, Kyoto University Faculty of Medicine, Yoshida, Sakyo-ku, 606-8501, Kyoto, Japan.
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29
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Qiao N, Reynaud D, Demin P, Halushka PV, Pace-Asciak CR. The Thromboxane Receptor Antagonist PBT-3, a Hepoxilin Stable Analog, Selectively Antagonizes the TPα Isoform in Transfected COS-7 Cells. J Pharmacol Exp Ther 2003; 307:1142-7. [PMID: 14560042 DOI: 10.1124/jpet.103.056705] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hepoxilin analog PBT-3 [10(S)-hydroxy-11,12-cyclopropyleicosa-5Z,8Z,14Z-trienoic acid methyl ester] was previously shown to inhibit the aggregation of human platelets and to antagonize the binding of the thromboxane receptor agonist I-BOP [[1S-[1alpha,2alpha (Z),3beta(1E,3S*),4alpha]]-7-[3-[3-hydroxy-4-(4-iodophenoxy)-1-butenyl]-7-oxabicyclo[2.2.1]hept-2-yl]-5-heptenoic acid] in human platelets (Pace-Asciak et al., 2002). We show herein that PBT-3 inhibits, to different degrees, binding of the TP receptor antagonist [3H]SQ 29,548 [[1S-[1alpha,2alpha (Z),3alpha,4alpha]]-7-[3-[[2-[(phenylamino)carbonyl]hydrazino]methyl]-7-oxabicyclo[2.2. 1]hept-2-yl]-5-heptenoic acid], to the TP receptor isoforms in TPalpha- and TPbeta-transfected COS-7 cells. These isoforms possess a different tail length, the alpha being shorter than the beta isoform. In contrast, SQ 29,548 shows no selection for the two TP isoforms. The IC50 value for PBT-3 = 2.0 +/- 0.3 x 10-7 M was observed for TPalpha, whereas this was one-sixth less active on the TPbeta isoform (IC50 = 1.2 +/- 0.2 x 10-6 M), suggesting selectivity for the TPalpha isoform. To investigate whether the tail contributes to the difference in competition binding by PBT-3, we investigated the tailless TP isoform expressed in transfected COS-7 cells. Its IC50 was similar to that of the TPalpha isoform. In additional studies, we investigated the effect of PBT-3 on the collagen and I-BOP evoked intracellular calcium release and on the collagen and I-BOP evoked phosphorylation of pleckstrin. PBT-3 blocked both pathways further demonstrating its TP receptor antagonist activity. These results demonstrate that the action of PBT-3 in inhibiting platelet aggregation is mediated via inhibition of the TPalpha isoform of the thromboxane receptor and that the tail may play an important role in recognition of this TP receptor antagonist.
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MESH Headings
- 8,11,14-Eicosatrienoic Acid/analogs & derivatives
- 8,11,14-Eicosatrienoic Acid/pharmacology
- Animals
- Autoradiography
- Blood Platelets/drug effects
- Blood Platelets/metabolism
- Blood Proteins/metabolism
- Blotting, Western
- Bridged Bicyclo Compounds, Heterocyclic
- COS Cells
- Calcium/blood
- Cells, Cultured
- Collagen/metabolism
- Densitometry
- Dose-Response Relationship, Drug
- Electrophoresis, Polyacrylamide Gel
- Fatty Acids, Unsaturated
- Humans
- Hydrazines/metabolism
- In Vitro Techniques
- Isomerism
- Phosphoproteins/metabolism
- Phosphorylation
- Radioligand Assay
- Receptors, Thromboxane/antagonists & inhibitors
- Receptors, Thromboxane/genetics
- Receptors, Thromboxane/metabolism
- Stimulation, Chemical
- Transfection
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Affiliation(s)
- Na Qiao
- Research Institute, The Hospital for Sick Children, 555 University Ave., Toronto, ON, Canada M5G 1X8
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30
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Kabashima K, Murata T, Tanaka H, Matsuoka T, Sakata D, Yoshida N, Katagiri K, Kinashi T, Tanaka T, Miyasaka M, Nagai H, Ushikubi F, Narumiya S. Thromboxane A2 modulates interaction of dendritic cells and T cells and regulates acquired immunity. Nat Immunol 2003; 4:694-701. [PMID: 12778172 DOI: 10.1038/ni943] [Citation(s) in RCA: 150] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2003] [Accepted: 05/02/2003] [Indexed: 11/09/2022]
Abstract
Physical interaction of T cells and dendritic cells (DCs) is essential for T cell proliferation and differentiation, but it has been unclear how this interaction is regulated physiologically. Here we show that DCs produce thromboxane A2 (TXA2), whereas naive T cells express the thromboxane receptor (TP). In vitro, a TP agonist enhances random cell movement (chemokinesis) of naive but not memory T cells, impairs DC-T cell adhesion, and inhibits DC-dependent proliferation of T cells. In vivo, immune responses to foreign antigens are enhanced in TP-deficient mice, which also develop marked lymphadenopathy with age. Similar immune responses were seen in wild-type mice treated with a TP antagonist during the sensitization period. Thus, TXA2-TP signaling modulates acquired immunity by negatively regulating DC-T cell interactions.
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Affiliation(s)
- Kenji Kabashima
- Department of Pharmacology, Kyoto University Faculty of Medicine, Kyoto 606-8501, Japan
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31
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Kelley LP, Kinsella BT. The role of N-linked glycosylation in determining the surface expression, G protein interaction and effector coupling of the alpha (alpha) isoform of the human thromboxane A(2) receptor. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1621:192-203. [PMID: 12726995 DOI: 10.1016/s0304-4165(03)00059-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In humans, thromboxane (TX) A(2) signals through two TXA(2) receptor (TP) isoforms, termed TPalpha and TPbeta, that diverge exclusively within the carboxyl terminal cytoplasmic domains. The amino terminal extracellular region of the TPs contains two highly conserved Asn (N)-linked glycosylation sites at Asn(4) and Asn(16). While it has been established that impairment of N-glycosylation of TPalpha significantly affects ligand binding/intracellular signalling, previous studies did not ascertain whether N-linked glycosylation was critical for ligand binding per se or whether it was required for the intracellular trafficking and the functional expression of TPalpha on the plasma membrane (PM). In the current study, we investigated the role of N-linked glycosylation in determining the functional expression of TPalpha, by assessment of its ligand binding, G protein coupling and intracellular signalling properties, correlating it with the level of antigenic TPalpha protein expressed on the PM and/or retained intracellularly. From our data, we conclude that N-glycosylation of either Asn(4) or Asn(16) is required and sufficient for expression of functionally active TPalpha on the PM while the fully non-glycosylated TPalpha(N4,N16-Q4,Q16) is almost completely retained within the endoplasmic reticulum (ER) and remains functionally inactive, failing to associate with its coupling G protein Galpha(q) and, in turn, failing to mediate phospholipase (PL) Cbeta activation.
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Affiliation(s)
- Leanne P Kelley
- Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, Merville House, University College Dublin, Belfield, Dublin 4, Ireland
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32
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Nurden P, Poujol C, Winckler J, Combrié R, Pousseau N, Conley PB, Levy-Toledano S, Habib A, Nurden AT. Immunolocalization of P2Y1 and TPalpha receptors in platelets showed a major pool associated with the membranes of alpha -granules and the open canalicular system. Blood 2003; 101:1400-8. [PMID: 12393588 DOI: 10.1182/blood-2002-02-0642] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
P2Y(1) and thromboxane-prostanoid-alpha (TPalpha) receptors on platelets belong to the G-protein-coupled 7-transmembrane domain family. They transmit signals for shape change, mobilization of calcium, and platelet aggregation. Immunogold labeling with a monoclonal antibody (MoAb) to the amino-terminal domain of P2Y(1) and a polyclonal antibody to the C-terminal domain of TPalpha revealed that while present at the platelet surface, both receptors were abundantly represented inside the platelet. Specifically, receptors were found in membranes of alpha-granules and elements of the open-canalicular system. A similar organization was found in mature megakaryocytes. Activation of platelets by adenosine diphosphate (ADP) and the thromboxane A(2) (TXA(2)) analog, I-BOP [1S-(1 alpha,2 beta(5Z),3 alpha-(1E,3S)4 alpha)-7-(3-(3- hydroxy-4-(p-iodophenoxy)-1-butenyl)-7-oxabicyclo(2.2.1)hept-2-yl)-5-heptenoic acid], increased the labeling of both P2Y(1) and TPalpha at the surface and in intracellular pools, suggesting that activation resulted in greater antibody accessibility to the receptor. A return to a platelet discoid shape and to basal values of labeling accompanied receptor desensitization. Platelets lacking the P2Y(12) ADP receptor normally expressed P2Y(1) and TPalpha, both before and after activation. Studies with the anti-ligand-induced binding site (anti-LIBS) MoAb, AP-6, confirmed that stored fibrinogen associated with internal pools of alpha(IIb)beta(3) at the start of secretion in a microenvironment containing agonist receptors. Pharmacologic antagonism of ADP or TXA(2) receptors in antithrombotic therapy may need to take into account blockade of internal receptor pools.
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Affiliation(s)
- Paquita Nurden
- Centre National de la Recherche Scientifique (CNRS), Hôpital Cardiologique, Pessac, France.
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33
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Murakami Y, Okada S, Nishihara M, Yokotani K. Roles of brain prostaglandin E2 and thromboxane A2 in the activation of the central sympatho-adrenomedullary outflow in rats. Eur J Pharmacol 2002; 452:289-94. [PMID: 12359269 DOI: 10.1016/s0014-2999(02)02308-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We examined the effects of centrally administered active metabolites of the arachidonic acid cascade on activation of the central sympatho-adrenomedullary outflow using urethane-anaesthetized rats. Intracerebroventricularly (i.c.v.) administered prostaglandin E(2) (0.3 nmol/animal) significantly elevated plasma levels of noradrenaline while levels of adrenaline were not affected. Prostaglandin D(2), prostaglandin F(2 alpha) and prostaglandin I(2) at the same dose (0.3 nmol/animal, i.c.v.) had no effect on plasma levels of either catecholamine. Thromboxane A(2) mimetic, 7-[3-[3-hydroxy-4-(4-iodophenoxy)-1-butenyl]-7-oxabicyclo [2.2.1]hept-2-yl], [1S-[1 alpha,2 alpha(Z),3beta(1E,3S),4 alpha]]-5-heptenoic acid (I-BOP) (5 and 10 pmol/animal) microinjected into the paraventricular nucleus of the hypothalamus significantly elevated plasma levels of adrenaline, but had little effect on plasma levels of noradrenaline. The I-BOP-induced (10 pmol/animal) elevation of plasma adrenaline levels was abolished by (+)-(1R,2R,3S,4S)-(5Z)-7-(3-[4-3H]-phenylsulphonyl-aminobicyclo[2.2.1]hept-2-yl)hept-5-enoic acid sodium salt [(+)-S-145] (a blocker of thromboxane A(2) receptors) [625 nmol (250 micro g)/animal, i.c.v.]. These results suggest that brain prostaglandin E(2) and thromboxane A(2) are respectively involved in the activation of the central sympathetic and adrenomedullary outflow in rats.
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Affiliation(s)
- Yoshinori Murakami
- Department of Pharmacology, Kochi Medical School, Nankoku, Kochi 783-8505, Japan
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34
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Flannery PJ, Spurney RF. Desensitization of the mouse thromboxane A2 receptor (TP) by G protein-coupled receptor kinases (Grks). Prostaglandins Other Lipid Mediat 2002; 70:79-90. [PMID: 12428680 DOI: 10.1016/s0090-6980(02)00013-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
GRKs play a key role in regulating G protein-coupled receptor (GPCR) responsiveness. To investigate the role of GRKs in desensitization of TP, we replaced threonines with favorable phosphorylation motifs for GRKs (positions 226 and 230) with alanine. Mutant and wild-type receptors were expressed in cell culture models and clones expressing similar numbers of receptors were studied. We found that: (1) affinity and specificity of thromboxane A2 (TxA2) binding to mutant TP were identical to the wild-type, (2) replacement of threonines 226 and 230 with alanines delayed the onset of agonist-induced desensitization, and (3) inhibition of endogenous GRK activity with a dominant-negative construct inhibited agonist-induced phosphorylation and enhanced responsiveness of wild-type TP but had little effect on responsiveness of the receptor mutant. These data are consistent with the notion that GRKs contribute to desensitization of TP.
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Affiliation(s)
- Patrick J Flannery
- Department of Medicine, Duke University, Durham VA Medical Centers, NC 27710, USA
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35
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Abstract
Prostanoids are a group of lipid mediators that include the prostaglandins (PG) and thromboxanes (TX). Upon cell stimulation, prostanoids are synthesized from arachidonic acid via the cyclooxygenase (COX) pathway and released outside the cells to exert various physiological and pathological actions in a variety of tissues and cells. The activities of prostanoids are mediated by specific G protein-coupled receptors, which have been classified on the basis of pharmacological experiments into eight types and subtypes according to their responsiveness to selective agonists and antagonists. These prostanoid receptors have been cloned from various species including human, and their distinct binding properties and signal transduction pathways have been characterized by analyses of cells expressing each receptor. Furthermore, the distribution patterns of prostanoid receptor mRNAs have been determined in tissues and cells for various species. This information is useful for understanding the molecular basis of the pathophysiological actions of prostanoids.
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Affiliation(s)
- Kazuhito Tsuboi
- Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Japan.
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36
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Abstract
Thromboxane is an important modulator of hemostasis and smooth muscle tonus and signals via G-protein-coupled thromboxane receptor. Previously, we characterized the TP receptor gene and suggested the presence of three promoter regions within the gene. The aim of the present study was to examine the regulation of transcriptional gene expression. By primer extension experiments the major transcription initiation site was shown to be a doublet at -160/165 bp upstream of the ATG codon in human megakaryoblastic MEG-01 cells, endothelial ECV 304 cells and in human myometrium smooth muscle cells. In the erythroleukemic HEL 1 cells transcription initiation site was identified at -10 bp. Transcriptional activity of the three 5'flanking regions of TP receptor gene representing the putative promoter regions was evaluated by transfection of MEG-01 cells with chimeric constructs containing luciferase gene-encoding sequence. Promoter region I displayed highest transcriptional activity and RT-PCR analysis confirmed the transcription of TP receptor mRNA driven by promoter I. Although, weak transcriptional activity was also observed regarding promoter region II, we were unable to amplify cDNA fragments representing promoter II-driven mRNA synthesis. Considering promoter region III, transcriptional activity was barely detectable. Various deletions of the 3.9 kb promoter I region revealed a size-dependent transcriptional activity. Further, for full activity a 'core' promoter corresponding to the region from -160/165 to -588 bp appeared to be necessary for full transcriptional activity of promoter 1.
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Affiliation(s)
- T Saffak
- Department of Pediatrics, Faculty of Medicine, Philipps University, Marburg, Germany
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37
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Mizoguchi A, Eguchi N, Kimura K, Kiyohara Y, Qu WM, Huang ZL, Mochizuki T, Lazarus M, Kobayashi T, Kaneko T, Narumiya S, Urade Y, Hayaishi O. Dominant localization of prostaglandin D receptors on arachnoid trabecular cells in mouse basal forebrain and their involvement in the regulation of non-rapid eye movement sleep. Proc Natl Acad Sci U S A 2001; 98:11674-9. [PMID: 11562489 PMCID: PMC58788 DOI: 10.1073/pnas.201398898] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Infusion of prostaglandin (PG) D(2) into the lateral ventricle of the brain induced an increase in the amount of non-rapid eye movement sleep in wild-type (WT) mice but not in mice deficient in the PGD receptor (DP). Immunofluorescence staining of WT mouse brain revealed that DP immunoreactivity was dominantly localized in the leptomeninges (LM) of the basal forebrain but that PGD synthase immunoreactivity was widely distributed in the LM of the entire brain. Electron microscopic observation indicated that DP-immunoreactive particles were predominantly located on the plasma membranes of arachnoid trabecular cells of the LM. The region with the highest DP immunoreactivity was clearly defined as bilateral wings in the LM of the basal forebrain located lateral to the optic chiasm in the proximity of the ventrolateral preoptic area, one of the putative sleep centers, and the tuberomammillary nucleus, one of the putative wake centers. The LM of this region contained DP mRNA 70-fold higher than that in the cortex as judged from the results of quantitative reverse transcription-PCR. PGD(2) infusion into the subarachnoid space of this region increased the extracellular adenosine level more than 2-fold in WT mice but not in the DP-deficient mice. These results indicate that DPs in the arachnoid trabecular cells of the basal forebrain mediate an increase in the extracellular adenosine level and sleep induction by PGD(2).
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Affiliation(s)
- A Mizoguchi
- Department of Anatomy and Neurobiology, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan
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38
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Abstract
Renal cyclooxygenase 1 and 2 activity produces five primary prostanoids: prostaglandin E2, prostaglandin F2alpha, prostaglandin I2, thromboxane A2, and prostaglandin D2. These lipid mediators interact with a family of distinct G protein-coupled prostanoid receptors designated EP, FP, IP, TP, and DP, respectively, which exert important regulatory effects on renal function. The intrarenal distribution of these prostanoid receptors has been mapped, and the consequences of their activation have been partially characterized. FP, TP, and EP1 receptors preferentially couple to an increase in cell calcium. EP2, EP4, DP, and IP receptors stimulate cyclic AMP, whereas the EP3 receptor preferentially couples to Gi, inhibiting cyclic AMP generation. EP1 and EP3 mRNA expression predominates in the collecting duct and thick limb, respectively, where their stimulation reduces NaCl and water absorption, promoting natriuresis and diuresis. The FP receptor is highly expressed in the distal convoluted tubule, where it may have a distinct effect on renal salt transport. Although only low levels of EP2 receptor mRNA are detected in the kidney and its precise intrarenal localization is uncertain, mice with targeted disruption of the EP2 receptor exhibit salt-sensitive hypertension, suggesting that this receptor may also play an important role in salt excretion. In contrast, EP4 receptor mRNA is predominantly expressed in the glomerulus, where it may contribute to the regulation of glomerular hemodynamics and renin release. The IP receptor mRNA is highly expressed near the glomerulus, in the afferent arteriole, where it may also dilate renal arterioles and stimulate renin release. Conversely, TP receptors in the glomerulus may counteract the effects of these dilator prostanoids and increase glomerular resistance. At present there is little evidence for DP receptor expression in the kidney. These receptors act in a concerted fashion as physiological buffers, protecting the kidney from excessive functional changes during periods of physiological stress. Nonsteroidal anti-inflammatory drug (NSAID)-mediated cyclooxygenase inhibition results in the loss of these combined effects, which contributes to their renal effects. Selective prostanoid receptor antagonists may provide new therapeutic approaches for specific disease states.
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Affiliation(s)
- M D Breyer
- Division of Nephrology, Department of Medicine, Vanderbilt University, Nashville, Tennessee 37232, USA.
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39
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Abstract
Cyclooxygenases metabolize arachidonate to five primary prostanoids: PGE(2), PGF(2 alpha), PGI(2), TxA(2), and PGD(2). These autacrine lipid mediators interact with specific members of a family of distinct G-protein-coupled prostanoid receptors, designated EP, FP, IP, TP, and DP, respectively. Each of these receptors has been cloned, expressed, and characterized. This family of eight prostanoid receptor complementary DNAs encodes seven transmembrane proteins which are typical of G-protein-coupled receptors and these receptors are distinguished by their ligand-binding profiles and the signal transduction pathways activated on ligand binding. Ligand-binding selectivity of these receptors is determined by both the transmembrane sequences and amino acid residues in the putative extracellular-loop regions. The selectivity of interaction between the receptors and G proteins appears to be mediated at least in part by the C-terminal tail region. Each of the EP(1), EP(3), FP, and TP receptors has alternative splice variants described that alter the coding sequence in the C-terminal intracellular tail region. The C-terminal variants modulate signal transduction, phosphorylation, and desensitization of these receptors, as well as altering agonist-independent constitutive activity.
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Affiliation(s)
- R M Breyer
- Division of Nephrology, Department of Medicine, Vanderbilt University, Nashville, Tennessee 37232, USA.
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40
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Nagao T, Koseki J, Suzuki Y, Nagamatsu T. Thromboxane A(2) causes retarded clearance of aggregated protein in glomeruli of nephritic mice. Eur J Pharmacol 2001; 413:271-9. [PMID: 11226403 DOI: 10.1016/s0014-2999(00)00932-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Recently, it has been demonstrated that the production of prostaglandins and thromboxane is increased in patients with chronic glomerulonephritis and lupus nephritis. We recently demonstrated that thromboxane A(2) delayed the clearance of heat-aggregated bovine serum albumin deposited in glomeruli. In the present study, we investigated the effect of thromboxane A(2) on the clearance of macromolecules in nephritic glomeruli. First, we attempted to clarify the conditions for the clearance of heat-aggregated bovine serum albumin in nephritic glomeruli, using glomeruli isolated from control and anti-glomerular basement membrane nephritic mice. Heat-aggregated bovine serum albumin was injected twice into each mouse. The glomeruli were then isolated and incubated in culture medium. The heat-aggregated bovine serum albumin content of control glomeruli gradually diminished with incubation time up to 24 h. The heat-aggregated bovine serum albumin content of nephritic glomeruli was 69% higher than that of control glomeruli at 24 h incubation. The production of thromboxane B(2) (the stable metabolite of thromboxane A(2)) in nephritic glomeruli showed about a sevenfold increase compared with control. DP-1904 [6-(1-imidazolylmethyl)-5,6,7,8-tetrahydro-naphthalene-2-carboxylic acid hydrochloride], a thromboxane A(2) synthase inhibitor, and KT2-962 [sodium 3-(4-(4-chlorophenyl-butylsulfonamido) butyl)-6-isopropylazulene-1-sulfonate], a selective thromboxane A(2) receptor antagonist, significantly reduced the heat-aggregated bovine serum albumin content in nephritic glomeruli. Normal glomeruli treated with U-46619 [15S-hydroxy-11a,9a-(epoxymethano)prosta-5Z,13E-dienoic acid], a stable analogue of thromboxane A(2), had significantly more heat-aggregated bovine serum albumin than control glomeruli. We next investigated whether thromboxane A(2) could affect the uptake/disposal of heat-aggregated bovine serum albumin by cultured rat mesangial cells. U-46619 significantly enhanced the uptake and inhibited the disposal of heat-aggregated bovine serum albumin by mesangial cells. Finally, we performed experiments to elucidate the role of the thromboxane A(2) receptor (TP receptor) in the clearance of heat-aggregated bovine serum albumin using TP-deficient mice. The glomerular heat-aggregated bovine serum albumin content of TP-receptor knockout [TP(-/-)] mice was lower than that of wild-type [WT(+/+)] mice. U-46619 dose dependently increased the uptake of heat-aggregated bovine serum albumin by mesangial cells in WT(+/+) mice, but not in the TP(-/-) mice. These findings suggest that thromboxane A(2) retards the clearance of aggregated protein in nephritic glomeruli and may contribute to the pathophysiology of glomerulonephritis.
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Affiliation(s)
- T Nagao
- Department of Pharmacology, Faculty of Pharmacy, Meijo University, 150 Yagotoyama Tenpaku-Ku, Nagoya 468-8503, Japan
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41
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Abstract
Thromboxane A2 is a biologically potent arachidonate metabolite through the cyclooxygenase pathway. It induces platelet aggregation and smooth muscle contraction and may promote mitogenesis and apoptosis of other cells. Its roles in physiological and pathological conditions have been widely documented. The enzyme that catalyzes its synthesis, thromboxane A2 synthase, and the receptors that mediate its actions, thromboxane A2 receptors, are the two key components critical for the functioning of this potent autacoid. Recent molecular biological studies have revealed the structure-function relationship and gene organizations of these proteins as well as genetic and epigenetic factors modulating their gene expression. Future investigation should shed light on detailed molecular signaling events specifying thromboxane A2 actions, and the genetic underpinning of the enzyme and the receptors in health and disease.
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Affiliation(s)
- R F Shen
- Department of Obstetrics, Gynecology, and Reproductive Sciences and Center for the Genetics of Asthma and Other Complex Diseases, University of Maryland School of Medicine, Baltimore 21201, USA.
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42
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Walsh MT, Kinsella BT. Regulation of the human prostanoid TPalpha and TPbeta receptor isoforms mediated through activation of the EP(1) and IP receptors. Br J Pharmacol 2000; 131:601-9. [PMID: 11015313 PMCID: PMC1572368 DOI: 10.1038/sj.bjp.0703624] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The intermolecular cross-regulation mediated by the prostanoid IP-receptor (IP)/EP(1) receptor (EP(1)) agonists PGI(2) and 17 phenyl trinor PGE(2) on TP receptor (TP) signalling within platelets was compared to that which occurs to the individual TPalpha and TPbeta receptors over-expressed in human embryonic kidney (HEK) 293 cells. Ligand mediated TP receptor activation was monitored by analysing mobilization of intracellular calcium ([Ca(2+)](i)) following stimulation with the selective thromboxane (TX) A(2) mimetic U46619. Consistent with previous studies, in platelets, PGI(2) acting through endogenous IP receptors completely inhibited U46619-mediated TP receptor signalling in a protein kinase (PK) A-dependent, PKC-independent manner. In HEK 293 cells, PGI(2), acting through endogenous AH6809 sensitive EP(1) rather than IP receptors, and the selective EP(1) receptor agonist 17 phenyl trinor PGE(2) antagonized U46619-mediated signalling by both TPalpha and TPbeta receptors in a PKC-dependent, PKA-independent manner. The maximum response induced by either ligand was significantly (P<0.005) greater for the TPalpha receptor than the TPbeta receptor, pointing to possible physiologic differences between the TP isoforms, although the potency of each ligand was similar for both TP receptors. TP(Delta328), a truncated variant of TP receptor lacking the C-tail sequences unique to TPalpha or TPbeta receptors, was not sensitive to EP(1) receptor-mediated regulation by PGI(2) or 17 phenyl trinor PGE(2) In conclusion, these data confirm that TPalpha and TPbeta receptors are subject to cross regulation by EP(1) receptor signalling in HEK 293 cells mediated by PKC at sites unique to the individual TP receptors and that TPalpha receptor responses are significantly more reduced by EP(1) receptor regulation than those of the TPbeta receptor.
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MESH Headings
- 15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid/pharmacology
- Biological Transport/drug effects
- Blood Platelets/drug effects
- Blood Platelets/metabolism
- Calcium/metabolism
- Cells, Cultured
- Dinoprostone/pharmacology
- Drug Interactions
- Enzyme Inhibitors/pharmacology
- Epoprostenol/pharmacology
- Humans
- Indoles/pharmacology
- Isoquinolines/pharmacology
- Maleimides/pharmacology
- Prostaglandin Antagonists/pharmacology
- Prostaglandins/metabolism
- Protein Isoforms/metabolism
- Receptors, Epoprostenol
- Receptors, Prostaglandin/metabolism
- Receptors, Prostaglandin E/metabolism
- Receptors, Prostaglandin E, EP1 Subtype
- Receptors, Thromboxane/antagonists & inhibitors
- Receptors, Thromboxane/metabolism
- Signal Transduction
- Sulfonamides
- Vasoconstrictor Agents/pharmacology
- Xanthenes/pharmacology
- Xanthones
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Affiliation(s)
- Marie-Therese Walsh
- Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, Merville House, University College Dublin, Belfield, Dublin 4, Ireland
| | - B Therese Kinsella
- Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, Merville House, University College Dublin, Belfield, Dublin 4, Ireland
- Author for correspondence:
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43
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Kobayashi T, Ushikubi F, Narumiya S. Amino acid residues conferring ligand binding properties of prostaglandin I and prostaglandin D receptors. Identification by site-directed mutagenesis. J Biol Chem 2000; 275:24294-303. [PMID: 10827082 DOI: 10.1074/jbc.m002437200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Using chimeras of the mouse prostaglandin (PG) I receptor (mIP) and the mouse PGD receptor (mDP), we previously revealed that the cyclopentane ring recognition by these receptors is specified by a region from the first to third transmembrane domain of each receptor; recognition by this region of mIP is broad, accommodating the D, E, and I types of cyclopentane rings, whereas that of mDP binds the D type of PGs alone (Kobayashi, T., Kiriyama, M., Hirata, T., Hirata, M., Ushikubi, F., and Narumiya, S. (1997) J. Biol. Chem. 272, 15154-15160). In the present study, we performed a more detailed chimera analysis, and narrowed the domain for the ring recognition to a region from the first transmembrane domain to the first extracellular loop. One chimera with the replacement of the second transmembrane domain and the first extracellular loop of mDP with that of mIP bound only iloprost. The amino acid substitutions in this chimera suggest that Ser(50) in the first transmembrane domain of mIP confers the broad ligand recognition of mIP and that Lys(75) and Leu(83) in the second transmembrane domain of mDP confer the high affinity to PGD(2) and the strict specificity of ligand binding of mDP, respectively.
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Affiliation(s)
- T Kobayashi
- Department of Pharmacology, Faculty of Medicine, Kyoto University, Kyoto 606-8501, Japan
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44
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Walsh MT, Foley JF, Kinsella BT. The alpha, but not the beta, isoform of the human thromboxane A2 receptor is a target for prostacyclin-mediated desensitization. J Biol Chem 2000; 275:20412-23. [PMID: 10827090 DOI: 10.1074/jbc.m907881199] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In this study, we examined the effects the prostacyclin receptor (IP) agonist cicaprost exhibited on U46619-mediated thromboxane A(2) receptor (TP) signaling in platelets and compared it to that which occurs in human embryonic kidney (HEK) 293 cells stably overexpressing the individual TPalpha or TPbeta isoforms. Consistent with previous studies, cicaprost abrogated U46619-mediated platelet aggregation and mobilization of intracellular calcium ([Ca(2+)](i)). In HEK 293 cells, signaling by TPalpha, but not TPbeta, was subject to IP-mediated desensitization in a protein kinase A-dependent, protein kinase C-independent manner. Desensitization of TPalpha signaling was independent of the nature of the IP agonist used, the level of IP expression, or the subtype of G(q) protein. Signaling by TP(Delta)(328), a truncated variant of TP devoid of the divergent residues of the TPs, or by TPalpha(S329A), a site-directed mutant of TPalpha, were insensitive to IP agonist activation. Whole cell phosphorylations established that TPalpha, but not TPbeta or TPalpha(S329A), is subject to IP-mediated phosphorylation and that TPalpha phosphorylation is inhibited by H-89. Thus, we conclude that TPalpha, but not TPbeta, is subject to cross-desensitization by IP mediated through direct protein kinase A phosphorylation at Ser(329) and propose that TPalpha may be the isoform physiologically relevant to TP:IP-mediated vascular hemostasis.
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Affiliation(s)
- M T Walsh
- Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, Merville House, University College Dublin, Belfield, Dublin 4, Ireland
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45
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Sugimoto Y, Narumiya S, Ichikawa A. Distribution and function of prostanoid receptors: studies from knockout mice. Prog Lipid Res 2000; 39:289-314. [PMID: 10856600 DOI: 10.1016/s0163-7827(00)00008-4] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Recent developments in the molecular biology of the prostanoid receptors has allowed the investigation of the physiological roles of each individual receptor type and subtype. The following article reports the prostanoid receptor distributions deduced from Northern blot and in situ hybridization analyses, summarizes the phenotypes of each receptor knockout mice, and discusses recent studies investigating the effects of each receptor deficiency on the inflammatory response and female reproductive processes. The combination of expression pattern and knockout analyses enabled us to determine which receptor expressed in a particular cell is important for the maintenance of normal and/or pathological physiology. The results from these analyses may be useful in the development of novel therapeutics that can selectively manipulate prostanoid-mediated actions.
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Affiliation(s)
- Y Sugimoto
- Department of Physiological Chemistry, Faculty of Pharmaceutical Sciences, Kyoto University, Japan
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46
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Okada S, Murakami Y, Nishihara M, Yokotani K, Osumi Y. Perfusion of the hypothalamic paraventricular nucleus with N-methyl-D-aspartate produces thromboxane A2 and centrally activates adrenomedullary outflow in rats. Neuroscience 2000; 96:585-90. [PMID: 10717438 DOI: 10.1016/s0306-4522(99)00598-9] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We applied a microdialysis technique for the measurement of hypothalamic thromboxane B2, a stable metabolite of thromboxane A2, in urethane-anesthetized rats. Perfusion with N-methyl-D-aspartate (1.5 and 2.5mM) of the paraventricular nucleus by microdialysis probe concentration-dependently elevated the levels of thromboxane B2 in this region and plasma levels of catecholamines. The elevation of adrenaline was much more marked than that of noradrenaline. Pretreatment with dizocilpine maleate (0.1 mM), a non-competitive antagonist of N-methyl-D-aspartate receptors, of the paraventricular nucleus by microdialysis probe attenuated the N-methyl-D-aspartate (1.5 mM)-induced elevations of both thromboxane B2 and plasma catecholamines. Intracerebroventricular administration of furegrelate (250 microg/animal), a thromboxane A2 synthase inhibitor, also abolished the responses evoked by N-methyl-D-aspartate. These results indicate that N-methyl-D-aspartate applied into the paraventricular nucleus produces thromboxane A2 in this region and elevates plasma levels of catecholamines, especially adrenaline. Thromboxane A2 produced in this hypothalamic nucleus is probably involved in the N-methyl-D-aspartate-induced central adrenomedullary outflow.
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Affiliation(s)
- S Okada
- Department of Pharmacology, Kochi Medical School, Nankoku, Kochi, Japan.
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47
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Affiliation(s)
- P V Halushka
- Department of Cell and Molecular Pharmacology and Experimental Therapeutics, Department of Medicine, Division of Clinical Pharmacology, Medical University of South Carolina, 171 Ashley Ave., Charleston, SC 29425, USA.
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48
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Abstract
Renal cyclooxygenase-1 and cyclooxygenase-2 actively metabolize arachidonate to metabolism five primary prostanoids: prostaglandin E2, prostaglandin F2a, prostaglandin I2, thromboxane A2, and prostaglandin D2. These lipid mediators interact with a family of distinct G-protein-coupled prostanoid receptors designated EP, FP, IP, TP, and DP, respectively, which exert important regulatory effects on renal function. The intrarenal distribution of these prostanoid receptors has been mapped and the consequences their activation are being characterized. The FP, TP, and EP1 receptors preferentially couple to increased cell Ca2+. EP2, EP4, DP, and IP receptors stimulate cyclic adenosine monophosphate, whereas the EP3 receptor preferentially couples to Gi, inhibiting cyclic adenosine monophosphate generation. EP1 and EP3 messenger RNA expression predominate in the collecting duct and thick limb, respectively, where their stimulation reduces sodium chloride and water absorption, promoting natriuresis and diuresis. Interestingly, only a mild change in renal water handling is seen in the EP3 receptor knockout mouse. Although only low levels EP2 receptor messenger RNA are detected in kidney and its precise intrarenal localization is uncertain, mice with targeted disruption of the EP2 receptor display salt-sensitive hypertension, suggesting it also plays an important role in salt excretion. In contrast, EP4 messenger RNA is readily detected in the glomerulus where it may contribute to the regulation of renin release and decrease glomerular resistance. TP receptors are also highly expressed in the glomerulus, where they may increase glomerular vascular resistance. The IP receptor messenger RNA is most highly expressed in the afferent arteriole and it may also modulate renal arterial resistance and renin release. At present there is little evidence for DP receptor expression in the kidney. Together these receptors act as physiologic buffers that protect the kidney from excessive functional changes during periods of physiologic stress. Loss of the combined effects of these receptors contributes to the side effects seen in the setting of nonsteroidal anti-inflammatory drug administration, whereas selective antagonists for these receptors may provide new therapeutic approaches in disease.
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Affiliation(s)
- M D Breyer
- Department of Medicine, Department of Veterans Affairs Medical Center, Vanderbilt University, Nashville, Tennessee, USA.
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49
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Abstract
Prostanoids are the cyclooxygenase metabolites of arachidonic acid and include prostaglandin (PG) D(2), PGE(2), PGF(2alpha), PGI(2), and thromboxne A(2). They are synthesized and released upon cell stimulation and act on cells in the vicinity of their synthesis to exert their actions. Receptors mediating the actions of prostanoids were recently identified and cloned. They are G protein-coupled receptors with seven transmembrane domains. There are eight types and subtypes of prostanoid receptors that are encoded by different genes but as a whole constitute a subfamily in the superfamily of the rhodopsin-type receptors. Each of the receptors was expressed in cultured cells, and its ligand-binding properties and signal transduction pathways were characterized. Moreover, domains and amino acid residues conferring the specificities of ligand binding and signal transduction are being clarified. Information also is accumulating as to the distribution of these receptors in the body. It is also becoming clear for some types of receptors how expression of their genes is regulated. Furthermore, the gene for each of the eight types of prostanoid receptor has been disrupted, and mice deficient in each type of receptor are being examined to identify and assess the roles played by each receptor under various physiological and pathophysiological conditions. In this article, we summarize these findings and attempt to give an overview of the current status of research on the prostanoid receptors.
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Affiliation(s)
- S Narumiya
- Department of Pharmacology, Kyoto University Faculty of Medicine, Kyoto, Japan
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50
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Wattler F, Wattler S, Kelly M, Skinner HB, Nehls M. Cloning, chromosomal location, and expression analysis of murine Smarce1-related, a new member of the high-mobility 365 group gene family. Genomics 1999; 60:172-8. [PMID: 10486208 DOI: 10.1006/geno.1999.5913] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Proteins containing high-mobility group (HMG) domains are segregated into two major groups. Members of one group are identified by the presence of more than one HMG domain that binds to DNA without sequence specificity, and they are usually ubiquitously expressed. In contrast, members of the other group possess a single HMG domain with high affinity to specific DNA sequences. Generally, members of the second group resemble classic tissue-specific transcriptional regulators. In contrast, Smarce1/BAF-57 is a ubiquitously expressed, novel protein with a single HMG domain that displays nonspecific DNA-binding characteristics. Additionally, as a core subunit of the mammalian SWI/SNF-like transcriptional activator complex, Smarce1/BAF-57 is also the first member of the HMG protein family that was reported to contain a kinesin-like coiled-coil (KLCC) domain. Here we report the cloning, as well as the chromosomal and phylogenetic analysis, of a novel mammalian protein that is structurally related to Smarce1, termed Smarce1-related (Smarce1r). The unique arrangement of an HMG with a KLCC domain shared with Smarce1/BAF-57 suggests a similar, albeit still unknown, function in chromatin assembly as part of a mammalian SWI/SNF-like complex. The linkage of a single nonspecific DNA-binding HMG domain with a KLCC domain makes both proteins the founding members of a third group of HMG proteins.
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Affiliation(s)
- F Wattler
- Lexicon Genetics Incorporated, 4000 Research Forest Drive, The Woodlands, Texas 77381, USA
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