1
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Michaelian N, Sadybekov A, Besserer-Offroy É, Han GW, Krishnamurthy H, Zamlynny BA, Fradera X, Siliphaivanh P, Presland J, Spencer KB, Soisson SM, Popov P, Sarret P, Katritch V, Cherezov V. Structural insights on ligand recognition at the human leukotriene B4 receptor 1. Nat Commun 2021; 12:2971. [PMID: 34016973 PMCID: PMC8137929 DOI: 10.1038/s41467-021-23149-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 04/16/2021] [Indexed: 01/09/2023] Open
Abstract
The leukotriene B4 receptor 1 (BLT1) regulates the recruitment and chemotaxis of different cell types and plays a role in the pathophysiology of infectious, allergic, metabolic, and tumorigenic human diseases. Here we present a crystal structure of human BLT1 (hBLT1) in complex with a selective antagonist MK-D-046, developed for the treatment of type 2 diabetes and other inflammatory conditions. Comprehensive analysis of the structure and structure-activity relationship data, reinforced by site-directed mutagenesis and docking studies, reveals molecular determinants of ligand binding and selectivity toward different BLT receptor subtypes and across species. The structure helps to identify a putative membrane-buried ligand access channel as well as potential receptor binding modes of endogenous agonists. These structural insights of hBLT1 enrich our understanding of its ligand recognition and open up future avenues in structure-based drug design.
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Affiliation(s)
- Nairie Michaelian
- grid.42505.360000 0001 2156 6853Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA USA ,grid.42505.360000 0001 2156 6853Department of Chemistry, University of Southern California, Los Angeles, CA USA
| | - Anastasiia Sadybekov
- grid.42505.360000 0001 2156 6853Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA USA ,grid.42505.360000 0001 2156 6853Department of Chemistry, University of Southern California, Los Angeles, CA USA
| | - Élie Besserer-Offroy
- grid.86715.3d0000 0000 9064 6198Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC Canada ,grid.19006.3e0000 0000 9632 6718Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California at Los Angeles, Los Angeles, CA USA
| | - Gye Won Han
- grid.42505.360000 0001 2156 6853Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA USA ,grid.42505.360000 0001 2156 6853Department of Chemistry, University of Southern California, Los Angeles, CA USA
| | - Harini Krishnamurthy
- grid.417993.10000 0001 2260 0793Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ USA
| | - Beata A. Zamlynny
- grid.417993.10000 0001 2260 0793Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ USA
| | - Xavier Fradera
- grid.417993.10000 0001 2260 0793Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ USA
| | - Phieng Siliphaivanh
- grid.417993.10000 0001 2260 0793Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ USA
| | - Jeremy Presland
- grid.417993.10000 0001 2260 0793Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ USA
| | - Kerrie B. Spencer
- grid.417993.10000 0001 2260 0793Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ USA
| | - Stephen M. Soisson
- grid.417993.10000 0001 2260 0793Merck Research Laboratories, Merck & Co., Inc., Kenilworth, NJ USA
| | - Petr Popov
- grid.454320.40000 0004 0555 3608Center for Computational and Data Intensive Science and Engineering, Skolkovo Institute of Science and Technology, Moscow, Russia ,grid.18763.3b0000000092721542Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
| | - Philippe Sarret
- grid.86715.3d0000 0000 9064 6198Department of Pharmacology-Physiology, Faculty of Medicine and Health Sciences, Institut de Pharmacologie de Sherbrooke, Université de Sherbrooke, Sherbrooke, QC Canada
| | - Vsevolod Katritch
- grid.42505.360000 0001 2156 6853Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA USA ,grid.42505.360000 0001 2156 6853Department of Chemistry, University of Southern California, Los Angeles, CA USA ,grid.42505.360000 0001 2156 6853Department of Quantitative and Computational Biology, University of Southern California, Los Angeles, CA USA
| | - Vadim Cherezov
- grid.42505.360000 0001 2156 6853Bridge Institute, USC Michelson Center for Convergent Bioscience, University of Southern California, Los Angeles, CA USA ,grid.42505.360000 0001 2156 6853Department of Chemistry, University of Southern California, Los Angeles, CA USA ,grid.18763.3b0000000092721542Research Center for Molecular Mechanisms of Aging and Age-Related Diseases, Moscow Institute of Physics and Technology, Dolgoprudny, Russia
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2
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Saeki K, Yokomizo T. Identification, signaling, and functions of LTB 4 receptors. Semin Immunol 2018; 33:30-36. [PMID: 29042026 DOI: 10.1016/j.smim.2017.07.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 05/02/2017] [Accepted: 07/26/2017] [Indexed: 10/18/2022]
Abstract
Leukotriene B4 (LTB4), a lipid mediator produced from arachidonic acid, is a chemoattractant for inflammatory leukocytes. We identified two receptors for LTB4, the high-affinity receptor BLT1 and the low-affinity receptor BLT2. BLT1 is expressed in various subsets of leukocytes, and analyses of BLT1-deficient mice revealed that the LTB4/BLT1 axis enhances leukocyte recruitment to infected sites, and is involved in the elimination of pathogens. Hyperactivation of the LTB4/BLT1 axis induces acute and chronic inflammation, resulting in various inflammatory diseases. BLT2 was originally identified as a low-affinity receptor for LTB4, and we later identified 12(S)-hydroxy-5Z,8E,10E-heptadecatrienoic acid (12-HHT) as a high-affinity ligand for BLT2. BLT2 is highly expressed in epithelial cells in various tissues including intestine and skin. Large quantities of 12-HHT are produced by activated platelets during skin injury, and activation of BLT2 on epidermal keratinocytes accelerates skin wound healing by enhancing cell migration. BLT2 signaling also enhances cell-cell junctions, protectes against transepidermal water loss, and preventes entry of environmental substances into the body.
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Affiliation(s)
- Kazuko Saeki
- Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan
| | - Takehiko Yokomizo
- Department of Biochemistry, Juntendo University School of Medicine, Tokyo, Japan.
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3
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Alexander SPH, Benson HE, Faccenda E, Pawson AJ, Sharman JL, Spedding M, Peters JA, Harmar AJ. The Concise Guide to PHARMACOLOGY 2013/14: G protein-coupled receptors. Br J Pharmacol 2013; 170:1459-581. [PMID: 24517644 PMCID: PMC3892287 DOI: 10.1111/bph.12445] [Citation(s) in RCA: 505] [Impact Index Per Article: 45.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The Concise Guide to PHARMACOLOGY 2013/14 provides concise overviews of the key properties of over 2000 human drug targets with their pharmacology, plus links to an open access knowledgebase of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. The full contents can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.12444/full. G protein-coupled receptors are one of the seven major pharmacological targets into which the Guide is divided, with the others being G protein-coupled receptors, ligand-gated ion channels, ion channels, catalytic receptors, nuclear hormone receptors, transporters and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. A new landscape format has easy to use tables comparing related targets. It is a condensed version of material contemporary to late 2013, which is presented in greater detail and constantly updated on the website www.guidetopharmacology.org, superseding data presented in previous Guides to Receptors and Channels. It is produced in conjunction with NC-IUPHAR and provides the official IUPHAR classification and nomenclature for human drug targets, where appropriate. It consolidates information previously curated and displayed separately in IUPHAR-DB and the Guide to Receptors and Channels, providing a permanent, citable, point-in-time record that will survive database updates.
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Affiliation(s)
- Stephen PH Alexander
- School of Life Sciences, University of Nottingham Medical SchoolNottingham, NG7 2UH, UK
| | - Helen E Benson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Elena Faccenda
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Adam J Pawson
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | - Joanna L Sharman
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
| | | | - John A Peters
- Neuroscience Division, Medical Education Institute, Ninewells Hospital and Medical School, University of DundeeDundee, DD1 9SY, UK
| | - Anthony J Harmar
- The University/BHF Centre for Cardiovascular Science, University of EdinburghEdinburgh, EH16 4TJ, UK
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4
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Affiliation(s)
- Motonao Nakamura
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Hongo, Tokyo, Japan.
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5
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Johansson AS, Haeggström JZ, Palmblad J. Commonly used leukotriene B4 receptor antagonists possess intrinsic activity as agonists in human endothelial cells: Effects on calcium transients, adhesive events and mediator release. Prostaglandins Leukot Essent Fatty Acids 2011; 84:109-12. [PMID: 21183325 DOI: 10.1016/j.plefa.2010.11.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 10/29/2010] [Accepted: 11/01/2010] [Indexed: 12/22/2022]
Abstract
Leukotriene B4 (LTB4), a potent chemotactic and immune-modulating lipid mediator, signals via two receptors, BLT1 and BLT2, leading to pro-inflammatory responses in phagocytes. Recently, we reported that BLT1 is the predominating BLT on human umbilical vein endothelial cells (HUVEC) and transmits a variety of functional responses. Here, we demonstrate that, in HUVEC, two BLT1 antagonists (U75302, CP105696) and one BLT2 antagonist (LY255283) possess intrinsic but varying agonist activity for adhesion of neutrophils, up-regulation of E-selectin, ICAM-1 and VCAM-1, and release of MCP-1. These effects were observed after exposure of HUVEC for the drugs for 0.25-6h, persisted for several hours, and were less potent in magnitude as those elicited by LPS. Our findings may have consequences for interpretation of in vitro BLT blockade experiments.
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Affiliation(s)
- Anne-Sofie Johansson
- Center for Inflammation and Hematology Research, Karolinska University Hospital Huddinge, Karolinska Institutet, Stockholm, Sweden
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6
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Yokomizo T. Leukotriene B4 receptors: novel roles in immunological regulations. ACTA ACUST UNITED AC 2010; 51:59-64. [PMID: 21035496 DOI: 10.1016/j.advenzreg.2010.08.002] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Accepted: 08/24/2010] [Indexed: 02/07/2023]
Abstract
Mammals have at least two receptors for LTB4; high-affinity BLT1 and low-affinity BLT2, both of which are GPCRs. 12-HHT serves as a more potent and abundant ligand for BLT2 than LTB4. BLT1 is expressed in a variety of inflammatory and immune cells including granulocytes, eosinophils, macrophages, differentiated Th1, Th2 and Th17 cells, effecter CD8+ T cells, dendritic cells and osteoclasts. BLT1 antagonists will be beneficial for the treatment of various diseases such as bronchial asthma, multiple sclerosis, contact dermatitis, and postmenopausal osteoporosis. BLT2 plays different roles from BLT1, and one important role of BLT2 is the maintenance of mucosal integrity in the colon.
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Affiliation(s)
- Takehiko Yokomizo
- Department of Medical Biochemistry, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
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7
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Hicks A, Goodnow R, Cavallo G, Tannu SA, Ventre JD, Lavelle D, Lora JM, Satjawatcharaphong J, Brovarney M, Dabbagh K, Tare NS, Oh H, Lamb M, Sidduri A, Dominique R, Qiao Q, Lou JP, Gillespie P, Fotouhi N, Kowalczyk A, Kurylko G, Hamid R, Wright MB, Pamidimukkala A, Egan T, Gubler U, Hoffman AF, Wei X, Li YL, O'Neil J, Marcano R, Pozzani K, Molinaro T, Santiago J, Singer L, Hargaden M, Moore D, Catala AR, Chao LCF, Benson J, March T, Venkat R, Mancebo H, Renzetti LM. Effects of LTB4 receptor antagonism on pulmonary inflammation in rodents and non-human primates. Prostaglandins Other Lipid Mediat 2010; 92:33-43. [PMID: 20214997 DOI: 10.1016/j.prostaglandins.2010.02.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2010] [Revised: 02/24/2010] [Accepted: 02/27/2010] [Indexed: 01/15/2023]
Abstract
Asthma, chronic obstructive pulmonary disease (COPD) and acute lung injury/acute respiratory distress syndrome (ALI/ARDS) are characterized by neutrophilic inflammation and elevated levels of leukotriene B4 (LTB4). However, the exact role of LTB4 pathways in mediating pulmonary neutrophilia and the potential therapeutic application of LTB4 receptor antagonists in these diseases remains controversial. Here we show that a novel dual BLT1 and BLT2 receptor antagonist, RO5101576, potently inhibited LTB4-evoked calcium mobilization in HL-60 cells and chemotaxis of human neutrophils. RO5101576 significantly attenuated LTB4-evoked pulmonary eosinophilia in guinea pigs. In non-human primates, RO5101576 inhibited allergen and ozone-evoked pulmonary neutrophilia, with comparable efficacy to budesonide (allergic responses). RO5101576 had no effects on LPS-evoked neutrophilia in guinea pigs and cigarette smoke-evoked neutrophilia in mice and rats. In toxicology studies RO5101576 was well-tolerated. Theses studies show differential effects of LTB4 receptor antagonism on neutrophil responses in vivo and suggest RO5101576 may represent a potential new treatment for pulmonary neutrophilia in asthma.
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Affiliation(s)
- Alexandra Hicks
- Department of RNA Therapeutics, Roche, 340 Kingsland Street, Nutley, NJ 07110, USA.
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8
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Abstract
The guinea pig has been the most commonly used small animal species in preclinical studies related to asthma and COPD. The primary advantages of the guinea pig are the similar potencies and efficacies of agonists and antagonists in human and guinea pig airways and the many similarities in physiological processes, especially airway autonomic control and the response to allergen. The primary disadvantages to using guinea pigs are the lack of transgenic methods, limited numbers of guinea pig strains for comparative studies and a prominent axon reflex that is unlikely to be present in human airways. These attributes and various models developed in guinea pigs are discussed.
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Affiliation(s)
- Brendan J Canning
- Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, MD 21224, USA.
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Bäck M, Qiu H, Haeggström JZ, Sakata K. Leukotriene B4 is an indirectly acting vasoconstrictor in guinea pig aorta via an inducible type of BLT receptor. Am J Physiol Heart Circ Physiol 2004; 287:H419-24. [PMID: 15016629 DOI: 10.1152/ajpheart.00699.2003] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Leukotriene B(4) (LTB(4)) is a potent leukocyte chemoattractant recently implicated in the pathogenesis of atherosclerosis. The aim of this study was to assess the effects of LTB(4) on isolated aortic preparations. Rings of guinea pig aorta were challenged with LTB(4) for recording mechanical responses and measurements of mediator release, and LTB(4) receptor (BLT(1)) expression was assessed by RT-PCR. Single concentrations of LTB(4) induced concentration-dependent contractions that were inhibited by treatment with antihistamines, indomethacin, or the thromboxane receptor antagonist BAYu3405 as well as by denudation of endothelium. In addition, LTB(4) increased the release of histamine and thromboxane in the bath. The contractions induced by LTB(4) were inhibited by either the unselective BLT receptor antagonist ONO-4057 or the selective BLT(1) receptor antagonist U-75302. Pretreatment with all-trans-retinoic acid enhanced the contractions and the release of histamine induced by LTB(4), without affecting either the contractions induced by histamine or the histamine release evoked by calcium ionophore A23187. Analysis by RT-PCR indicated the expression of a BLT(1) receptor in the guinea pig aorta and that BLT(1) receptor mRNA was upregulated after treatment with retinoic acid. These results suggest that LTB(4) contracts the guinea pig aorta via an indirect mechanism involving the release of histamine and thromboxane and that this BLT(1) receptor-mediated response can be upregulated by all-trans-retinoic acid.
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Affiliation(s)
- Magnus Bäck
- Division of Physiology, The National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
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Kotarsky K, Nilsson NE, Olde B, Owman C. Progress in Methodology Improved Reporter Gene Assays Used to Identify Ligands Acting on Orphan Seven-Transmembrane Receptors. ACTA ACUST UNITED AC 2003; 93:249-58. [PMID: 14675457 DOI: 10.1111/j.1600-0773.2003.pto930601.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Seven-transmembrane G-protein-coupled receptors play a central role in physiology by facilitating cell communication through recognition of a wide range of ligands. Even more important, they represent important drug targets. Unfortunately, for many of these receptors the endogenous ligands, and hence their functions, remain to be identified. These receptors are referred to as "orphan" receptors. A pre-requisite for the identification of ligands activating orphan receptors is powerful assay systems. Until now, reporter gene assays have not been in common use in this process. Here, we summarize our development of improved reporter gene assays. We optimized reporter gene assays in respect of (i) the promoter region of the construct, (ii) the reporter enzyme used, (iii) and the assay procedure. Furthermore, an unique fluorescence-based clone selection step was introduced, allowing rapid selection of the most sensitive reporter cell clones when establishing stable reporter cell lines. Mathematical formulae are provided to enable a simple and reliable comparison between different cell lines, when tested with a compound of interest. The resulting reporter cell lines responded in a very sensitive way to the stimulation of various test receptors. The reporter system was termed HighTRACE (high-throughput reporter assay with clone election). Its high assay quality makes it suitable as a primary screening tool. Ligands for two recently unknown 7TM receptors were identified using the HighTRACE system i.e., two cell surface free fatty acid receptors, GPR40 (FFA1R) and GPR43 (FFA2R). The identification was accomplished using a reverse pharmacology approach.
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Affiliation(s)
- Knut Kotarsky
- Division of Molecular Neurobiology, Department of Physiological Sciences, Wallenberg Neuroscience Center, S-221 84 Lund, Sweden
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11
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Abstract
Leukotriene B4 (LTB4) is a potent chemotactic agent and activating factor for granulocytes. Two cell surface receptors for LTB4 (BLT1 and BLT2) have been isolated in the last few years. These receptors are G-protein-coupled receptors (GPCR), and they have 45% amino acid identity. BLT1 and BLT2 are high- and low- affinity receptors, respectively. Cells transfected with BLT1 and BLT2 show LTB4-dependent intracellular signal transduction and chemotaxis in vitro. The distribution and pharmacological characteristics of BLT1 and BLT2 are different, suggesting distinct roles for these receptors in vivo. The open reading frame (ORF) of BLT2 overlaps the promoter of BLT1, a so called 'promoter in ORF'. Based on recent publications on BLT1 transgenic and knock out mice phenotypes, it appears that LTB4 plays important roles in inflammation in addition to host defense in vivo.
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Affiliation(s)
- Akiko Toda
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Japan
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12
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Abstract
Leukotriene B4 (LTB4) is known as one of the most potent chemoattractants and activators of leukocytes and is involved in inflammatory diseases. Enzymes involved in the biosynthesis and metabolism of LTB4 have been cloned, and their properties are well understood. Two G-protein-coupled receptors (BLT1 and BLT2) have been cloned and characterized. BLT1 and BLT2 are high- and low-affinity LTB4 receptors, respectively, and form a gene cluster in human and mouse. In this article recent findings on the metabolism of and the receptors for LTB4 are reviewed. We also discuss briefly a coreceptor role of BLT in HIV infection, and ion channel modification by LTB4.
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Affiliation(s)
- T Yokomizo
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, CREST of Japan, Science and Technology Corporation.
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13
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Yokomizo T, Kato K, Hagiya H, Izumi T, Shimizu T. Hydroxyeicosanoids bind to and activate the low affinity leukotriene B4 receptor, BLT2. J Biol Chem 2001; 276:12454-9. [PMID: 11278893 DOI: 10.1074/jbc.m011361200] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Leukotriene B(4), an arachidonate metabolite, is a potent chemoattractant of leukocytes involved in various inflammatory diseases. Two G-protein-coupled receptors for leukotriene B(4) have been cloned and characterized. BLT1 (Yokomizo, T., Izumi, T., Chang, K., Takuwa, Y., and Shimizu, T. (1997) Nature 387, 620-624) is a high affinity receptor exclusively expressed in leukocytes, and BLT2 (Yokomizo, T., Kato, K., Terawaki, K., Izumi, T., and Shimizu, T. (2000) J. Exp. Med. 192, 421-432) is a low affinity receptor expressed more ubiquitously. Here we report the binding profiles of various BLT antagonists and eicosanoids to either BLT1 or BLT2 using the membrane fractions of Chinese hamster ovary cells stably expressing the receptor. BLT antagonists are grouped into three classes: BLT1-specific U-75302, BLT2-specific LY255283, and BLT1/BLT2 dual-specific ZK 158252 and CP 195543. We also show that 12(S)-hydroxyeicosatetraenoic acid, 12(S)-hydroperxyeicosatetraenoic acid, and 15(S)-hydroxyeicosatetraenoic acid competed with [(3)H]LTB(4) binding to BLT2, but not BLT1, dose dependently. These eicosanoids also cause calcium mobilization and chemotaxis through BLT2, again in contrast to BLT1. These findings suggest that BLT2 functions as a low affinity receptor, with broader ligand specificity for various eicosanoids, and mediates distinct biological and pathophysiological roles from BLT1.
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Affiliation(s)
- T Yokomizo
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo and the Japan Science and Technology Corporation (CREST), Tokyo 113-0033, Japan.
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Abstract
This review describes the aspects of leukotriene (LT) pharmacology and biology that are relevant to their important role in asthma. The biosynthesis and metabolism, including transcellular metabolism, of LTB4 and the cysteinyl-LTs (i.e. LTC4, LTD4 and LTE4) are described, and their transport is briefly outlined. The existence, distribution and pharmacological characterization of the receptors (BLT, CysLT1, CysLT2), as well as the transduction mechanisms triggered, are discussed in detail. We also describe their effects on airway smooth muscle tone, hyperresponsiveness and proliferation, on vascular tone and permeability, on mucus secretion, on neural fibers and inflammatory cell functions. Finally, the evidence supporting their role as asthma mediators is reviewed, including the effects of anti LT drugs (both biosynthesis inhibitors and receptor antagonists) in experimental and clinical asthma.
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Affiliation(s)
- S Nicosia
- Laboratory of Molecular Pharmacology, Institute of Pharmacological Sciences, University of Milan, via Balzaretti, Milan, 9-20133, Italy.
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15
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Kotarsky K, Owman C, Olde B. A chimeric reporter gene allowing for clone selection and high-throughput screening of reporter cell lines expressing G-protein-coupled receptors. Anal Biochem 2001; 288:209-15. [PMID: 11152592 DOI: 10.1006/abio.2000.4898] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Efficient screening of ligands interacting with G-protein-coupled receptors is central for modern drug development. Here, we describe an optimized reporter vector primarily intended for use in reporter cell lines expressing such receptors. The construct consists of a synthetic enhancer containing 9x TRE (12-O-tetradecanoylphorbol-13-acetate-responsive elements) fused to a minimal CMV (cytomegalovirus) promoter. Activation of the promoter construct leads to the expression of a chimeric reporter protein based on the genes for enhanced green fluorescent protein and Photinus luciferase. The chimeric protein allows for both clonal selection by fluorescence, which facilitates the selection of optimal reporter cell lines and high-throughput screening by luminescens. In designing the vector, increasing numbers of TRE motifs were tested in front of two different minimal promoters. The reporter gene was more strongly inducible with increasing numbers of TRE motifs. The constructs were tested in two cell lines, CHO and HeLa. The latter regulated reporter gene activity stronger in response to PMA (phorbol 12-myristate 13-acetate) stimulation and were used to construct HF1 reporter cell lines. Model experiments were carried out on these reporter cells transfected with the human BLTR, human CCR5, or the rat alpha(1b) receptor. After maximal agonist stimulation reporter gene activity was increased 200-, 15-, and 50-fold, respectively.
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Affiliation(s)
- K Kotarsky
- Division of Molecular Neurobiology, Wallenberg Neuroscience Center, Lund, SE-223 62, Sweden.
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16
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Kamohara M, Takasaki J, Matsumoto M, Saito T, Ohishi T, Ishii H, Furuichi K. Molecular Cloning and Characterization of Another Leukotriene B4 Receptor. J Biol Chem 2000. [DOI: 10.1016/s0021-9258(19)61471-7] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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17
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Yokomizo T, Kato K, Terawaki K, Izumi T, Shimizu T. A second leukotriene B(4) receptor, BLT2. A new therapeutic target in inflammation and immunological disorders. J Exp Med 2000; 192:421-32. [PMID: 10934230 PMCID: PMC2193217 DOI: 10.1084/jem.192.3.421] [Citation(s) in RCA: 391] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Leukotriene B(4) (LTB(4)) is a potent chemoattractant and activator of both granulocytes and macrophages. The actions of LTB(4) appear to be mediated by a specific G protein-coupled receptor (GPCR) BLT1, originally termed BLT (Yokomizo, T., T. Izumi, K. Chang, Y. Takuwa, and T. Shimizu. 1997. Nature. 387:620-624). Here, we report the molecular cloning of a novel GPCR for LTB(4), designated BLT2, which binds LTB(4) with a Kd value of 23 nM compared with 1.1 nM for BLT1, but still efficiently transduces intracellular signaling. BLT2 is highly homologous to BLT1, with an amino acid identity of 45.2%, and its open reading frame is located in the promoter region of the BLT1 gene. BLT2 is expressed ubiquitously, in contrast to BLT1, which is expressed predominantly in leukocytes. Chinese hamster ovary cells expressing BLT2 exhibit LTB(4)-induced chemotaxis, calcium mobilization, and pertussis toxin-insensitive inhibition of adenylyl cyclase. Several BLT1 antagonists, including U 75302, failed to inhibit LTB(4) binding to BLT2. Thus, BLT2 is a pharmacologically distinct receptor for LTB(4), and may mediate cellular functions in tissues other than leukocytes. BLT2 provides a novel target for antiinflammatory therapy and promises to expand our knowledge of LTB(4) function. The location of the gene suggests shared transcriptional regulation of these two receptors.
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Affiliation(s)
- Takehiko Yokomizo
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Tokyo 113-0033, Japan
| | - Kazuhiko Kato
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Pharmaceutical Research Center, Meiji Seika Kaisha, Limited, Yokohama 222-8567, Japan
| | - Kan Terawaki
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Tokyo 113-0033, Japan
| | - Takashi Izumi
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Tokyo 113-0033, Japan
| | - Takao Shimizu
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Tokyo 113-0033, Japan
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Kato K, Yokomizo T, Izumi T, Shimizu T. Cell-specific transcriptional regulation of human leukotriene B(4) receptor gene. J Exp Med 2000; 192:413-20. [PMID: 10934229 PMCID: PMC2193224 DOI: 10.1084/jem.192.3.413] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2000] [Accepted: 04/18/2000] [Indexed: 11/04/2022] Open
Abstract
Leukotriene B(4) (LTB(4)) is a lipid mediator that activates leukocytes and is involved in host defense and inflammation. BLT1, a high-affinity receptor for LTB(4) (originally termed BLT), is expressed exclusively in inflammatory cells and is inducible in macrophages upon activation. The mechanisms of tissue-specific expression and induction of BLT1 are important for the understanding of mechanism of onset and the potential treatment of inflammatory disorders. Here, we report the genomic structure and a promoter analysis of the human BLT1 gene, with an emphasis on the mechanism of cell-specific transcription. No TATA or CAAT elements exist around the transcription initiation sites, but a GC-rich sequence is observed in this region. A reporter gene assay revealed that a region approximately 80 basepair upstream from the initiator sequence is required for the basal transcription of the BLT1 gene. Sp1 was found to be a major activator of basal transcription by electrophoretic mobility shift assays and site-directed mutagenesis. The CpG sites of the BLT1 promoter region were highly methylated in BLT1-nonexpressing cells, but not methylated in BLT1-expressing cells. Further, methylation of this region in vitro inhibited the promoter activity to approximately 15% of the control. Thus, methylation at CpG sites in the promoter region is important for cell-specific transcription of the BLT1 gene. The promoter region of the BLT1 gene is localized within the open reading frame (ORF) of the BLT2 gene, which encodes a low-affinity receptor for LTB(4) (Yokomizo, T., K. Kato, K. Terawaki, T. Izumi, and T. Shimizu. 2000. J. Exp. Med. 192:421-431). To our knowledge, this is the first example of "promoter in ORF" in higher eukaryotes.
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Affiliation(s)
- Kazuhiko Kato
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Pharmaceutical Research Center, Meiji Seika Kaisha, Limited, Yokohama 222-8567, Japan
| | - Takehiko Yokomizo
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Tokyo 113-0033, Japan
| | - Takashi Izumi
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Tokyo 113-0033, Japan
| | - Takao Shimizu
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
- Core Research for Evolutional Science and Technology (CREST), Japan Science and Technology Corporation, Tokyo 113-0033, Japan
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Yokomizo T, Masuda K, Kato K, Toda A, Izumi T, Shimizu T. Leukotriene B4 receptor. Cloning and intracellular signaling. Am J Respir Crit Care Med 2000; 161:S51-5. [PMID: 10673227 DOI: 10.1164/ajrccm.161.supplement_1.ltta-11] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- T Yokomizo
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
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