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Subramanian BC, Majumdar R, Parent CA. The role of the LTB 4-BLT1 axis in chemotactic gradient sensing and directed leukocyte migration. Semin Immunol 2018; 33:16-29. [PMID: 29042024 DOI: 10.1016/j.smim.2017.07.002] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 06/07/2017] [Accepted: 07/13/2017] [Indexed: 12/11/2022]
Abstract
Directed leukocyte migration is a hallmark of inflammatory immune responses. Leukotrienes are derived from arachidonic acid and represent a class of potent lipid mediators of leukocyte migration. In this review, we summarize the essential steps leading to the production of LTB4 in leukocytes. We discuss the recent findings on the exosomal packaging and transport of LTB4 in the context of chemotactic gradients formation and regulation of leukocyte recruitment. We also discuss the dynamic roles of the LTB4 receptors, BLT1 and BLT2, in mediating chemotactic signaling in leukocytes and contrast them to other structurally related leukotrienes that bind to distinct GPCRs. Finally, we highlight the specific roles of the LTB4-BLT1 axis in mediating signal-relay between chemotaxing neutrophils and its potential contribution to a wide variety of inflammatory conditions including tumor progression and metastasis, where LTB4 is emerging as a key signaling component.
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Affiliation(s)
- Bhagawat C Subramanian
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, United States.
| | - Ritankar Majumdar
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, United States; Department of Pharmacology, University of Michigan School of Medicine, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, United States.
| | - Carole A Parent
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892, United States; Department of Pharmacology, University of Michigan School of Medicine, Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, United States.
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The Intracellular Localisation and Phosphorylation Profile of the Human 5-Lipoxygenase Δ13 Isoform Differs from That of Its Full Length Counterpart. PLoS One 2015; 10:e0132607. [PMID: 26173130 PMCID: PMC4501781 DOI: 10.1371/journal.pone.0132607] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 06/16/2015] [Indexed: 01/31/2023] Open
Abstract
5-Lipoxygenase (5-LO) catalyzes leukotriene (LT) biosynthesis by a mechanism that involves interactions with 5-lipoxygenase activating protein (FLAP) and coactosin-like protein (CLP). 5-LO splice variants were recently identified in human myeloid and lymphoid cells, including the catalytically inactive ∆13 isoform (5-LO∆13) whose transcript lacks exon 13. 5-LO∆13 inhibits 5-LO product biosynthesis when co-expressed with active full length 5-LO (5-LO1). The objective of this study was to investigate potential mechanisms by which 5-LO∆13 interferes with 5-LO product biosynthesis in transfected HEK293 cells. When co-expressed with 5-LO1, 5-LO∆13 inhibited LT but not 5-hydroxyeicosatetraenoic acid (5-HETE) biosynthesis. This inhibition was independent of 5-LO∆13—FLAP interactions since it occurred in cells expressing FLAP or not. In cell-free assays CLP enhances 5-LO activity through interactions with tryptophan-102 of 5-LO. In the current study, the requirement for W102 was extended to whole cells, as cells expressing the 5-LO1-W102A mutant produced little 5-LO products. W102A mutants of 5-LO∆13 inhibited 5-LO product biosynthesis as effectively as 5-LO∆13 suggesting that inhibition is independent of interactions with CLP. Confocal microscopy showed that 5-LO1 was primarily in the nucleoplasm whereas W102A mutants showed a diffuse cellular expression. Despite the retention of known nuclear localisation sequences, 5-LO∆13 was cytosolic and concentrated in ER-rich perinuclear regions where its effect on LT biosynthesis may occur. W102A mutants of 5-LO∆13 showed the same pattern. Consistent with subcellular distribution patterns, 5-LO∆13 was hyper-phosphorylated on S523 and S273 compared to 5-LO1. Together, these results reveal a role for W102 in nuclear targeting of 5-LO1 suggesting that interactions with CLP are required for nuclear localization of 5-LO1, and are an initial characterisation of the 5-LO∆13 isoform whose inhibition of LT biosynthesis appears independent of interactions with CLP and FLAP. Better knowledge of the regulation and properties of alternative 5-LO isoforms will contribute to understanding the complex regulation of LT biosynthesis.
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Jickling GC, Liu D, Ander BP, Stamova B, Zhan X, Sharp FR. Targeting neutrophils in ischemic stroke: translational insights from experimental studies. J Cereb Blood Flow Metab 2015; 35:888-901. [PMID: 25806703 PMCID: PMC4640255 DOI: 10.1038/jcbfm.2015.45] [Citation(s) in RCA: 388] [Impact Index Per Article: 43.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Revised: 01/23/2015] [Accepted: 01/26/2015] [Indexed: 01/08/2023]
Abstract
Neutrophils have key roles in ischemic brain injury, thrombosis, and atherosclerosis. As such, neutrophils are of great interest as targets to treat and prevent ischemic stroke. After stroke, neutrophils respond rapidly promoting blood-brain barrier disruption, cerebral edema, and brain injury. A surge of neutrophil-derived reactive oxygen species, proteases, and cytokines are released as neutrophils interact with cerebral endothelium. Neutrophils also are linked to the major processes that cause ischemic stroke, thrombosis, and atherosclerosis. Thrombosis is promoted through interactions with platelets, clotting factors, and release of prothrombotic molecules. In atherosclerosis, neutrophils promote plaque formation and rupture by generating oxidized-low density lipoprotein, enhancing monocyte infiltration, and degrading the fibrous cap. In experimental studies targeting neutrophils can improve stroke. However, early human studies have been met with challenges, and suggest that selective targeting of neutrophils may be required. Several properties of neutrophil are beneficial and thus may important to preserve in patients with stroke including antimicrobial, antiinflammatory, and neuroprotective functions.
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Affiliation(s)
- Glen C Jickling
- Department of Neurology, University of California at Davis, Sacramento, California, USA
| | - DaZhi Liu
- Department of Neurology, University of California at Davis, Sacramento, California, USA
| | - Bradley P Ander
- Department of Neurology, University of California at Davis, Sacramento, California, USA
| | - Boryana Stamova
- Department of Neurology, University of California at Davis, Sacramento, California, USA
| | - Xinhua Zhan
- Department of Neurology, University of California at Davis, Sacramento, California, USA
| | - Frank R Sharp
- Department of Neurology, University of California at Davis, Sacramento, California, USA
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Abstract
BACKGROUND Leukotrienes play an important role in allergic and inflammatory diseases, but reports on the involvement of arachidonate 5-lipoxygenase-activating protein (ALOX5AP) and leukotriene A(4) hydrolase (LTA4H) in asthma have been inconclusive. OBJECTIVE To determine whether polymorphisms in ALOX5AP and LTA4H genes are risk factors for asthma in two different Latino groups: Mexicans and Puerto Ricans. METHODS The LTA4H gene was sequenced in individuals from both groups to identify novel polymorphisms. Single-nucleotide polymorphisms (SNPs) in the ALOX5AP and LTA4H genes were analysed for associations with asthma and asthma-related phenotypes in 687 parent-child trios of Mexican and Puerto Rican origin. RESULTS In LTA4H, five previously unknown polymorphisms were identified. Two SNPs within LTA4H (rs17525488 and rs2540493) were protective for asthma in Latinos (P=0.007 and 0.05, respectively). Among the Mexican patients, LTA4H polymorphisms were associated with baseline lung function and IgE levels. For ALOX5AP, the minor allele at SNP rs10507391 was associated with protection from asthma (odds ratio=0.78, P=0.02) and baseline lung function (P=0.018) in Puerto Ricans. A gene-gene interaction was identified between LTA4H (rs17525488) and ALOX5AP (rs10507391), (P=0.003, in the combined sample). CONCLUSION Our results support the role of LTA4H and ALOX5AP variants as risk factors for asthma in Latino populations.
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Madsen-Bouterse SA, Romero R, Tarca AL, Kusanovic JP, Espinoza J, Kim CJ, Kim JS, Edwin SS, Gomez R, Draghici S. The transcriptome of the fetal inflammatory response syndrome. Am J Reprod Immunol 2010; 63:73-92. [PMID: 20059468 PMCID: PMC3437779 DOI: 10.1111/j.1600-0897.2009.00791.x] [Citation(s) in RCA: 104] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PROBLEM The fetal inflammatory response syndrome (FIRS) is considered the counterpart of the systemic inflammatory response syndrome (SIRS), but similarities in their regulatory mechanisms are unclear. This study characterizes the fetal mRNA transcriptome of peripheral leukocytes to identify key biological processes and pathways involved in FIRS. METHOD OF STUDY Umbilical cord blood from preterm neonates with FIRS (funisitis, plasma IL-6 >11 pg/mL; n = 10) and neonates with no evidence of inflammation (n = 10) was collected at birth. Results Microarray analysis of leukocyte RNA revealed differential expression of 541 unique genes, changes confirmed by qRT-PCR for 41 or 44 genes tested. Similar to SIRS and sepsis, ontological and pathway analyses yielded significant enrichment of biological processes including antigen processing and presentation, immune response, and processes critical to cellular metabolism. RESULTS are comparable with microarray studies of endotoxin challenge models and pediatric sepsis, identifying 25 genes across all studies. CONCLUSION This study is the first to profile genome-wide expression in FIRS, which demonstrates a substantial degree of similarity with SIRS despite differences in fetal and adult immune systems.
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Affiliation(s)
| | - Roberto Romero
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan, USA
- Wayne State University/Hutzel Women’s Hospital, Department of Obstetrics and Gynecology, Detroit, Michigan, USA
- Wayne State University, Center for Molecular Medicine and Genetics, Detroit, Michigan, USA
| | - Adi L. Tarca
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan, USA
- Wayne State University, Department of Computer Science, Detroit, Michigan, USA
| | - Juan Pedro. Kusanovic
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan, USA
- Wayne State University/Hutzel Women’s Hospital, Department of Obstetrics and Gynecology, Detroit, Michigan, USA
| | - Jimmy Espinoza
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan, USA
- Wayne State University/Hutzel Women’s Hospital, Department of Obstetrics and Gynecology, Detroit, Michigan, USA
| | - Chong Jai Kim
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan, USA
- Wayne State University, Department of Pathology, Wayne State University, Detroit, MI, USA
| | - Jung-Sun Kim
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan, USA
- Wayne State University, Department of Pathology, Wayne State University, Detroit, MI, USA
| | - Samuel S. Edwin
- Perinatology Research Branch, NICHD/NIH/DHHS, Bethesda, Maryland, and Detroit, Michigan, USA
| | - Ricardo Gomez
- CEDIP (Center for Perinatal Diagnosis and Research), Department of Obstetrics and Gynecology, Sotero del Rio Hospital, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - Sorin Draghici
- Wayne State University, Department of Computer Science, Detroit, Michigan, USA
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Xu S, McKeever BM, Wisniewski D, Miller DK, Spencer RH, Chu L, Ujjainwalla F, Yamin TT, Evans JF, Becker JW, Ferguson AD. Expression, purification and crystallization of human 5-lipoxygenase-activating protein with leukotriene-biosynthesis inhibitors. Acta Crystallogr Sect F Struct Biol Cryst Commun 2007; 63:1054-7. [PMID: 18084092 PMCID: PMC2344111 DOI: 10.1107/s1744309107055571] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 11/02/2007] [Indexed: 02/02/2023]
Abstract
The nuclear membrane protein 5-lipoxygenase-activating protein (FLAP) plays an essential role in leukotriene synthesis. Recombinant full-length human FLAP with a C-terminal hexahistidine tag has been expressed and purified from the cytoplasmic membrane of Escherichia coli. Diffraction-quality crystals of FLAP in complex with leukotriene-synthesis inhibitor MK-591 and with an iodinated analogue of MK-591 have been grown using the sitting-drop vapor-diffusion method. The crystals exhibit tetragonal symmetry (P42(1)2) and diffracted to a resolution limit of 4 A.
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Affiliation(s)
- Shihua Xu
- Department of Medicinal Chemistry, Merck Research Laboratories, Rahway, NJ 07065, USA.
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St-Onge M, Flamand N, Biarc J, Picard S, Bouchard L, Dussault AA, Laflamme C, James MJ, Caughey GE, Cleland LG, Borgeat P, Pouliot M. Characterization of prostaglandin E2 generation through the cyclooxygenase (COX)-2 pathway in human neutrophils. BIOCHIMICA ET BIOPHYSICA ACTA 2007; 1771:1235-45. [PMID: 17643350 PMCID: PMC2891965 DOI: 10.1016/j.bbalip.2007.06.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Revised: 06/01/2007] [Accepted: 06/18/2007] [Indexed: 01/08/2023]
Abstract
In the present study, we characterized the generation of prostaglandin (PG)E2 in human neutrophils. We found that the Ca2+-dependent type IV cytosolic phospholipase A2 (cPLA2) was pivotally involved in the COX-2-mediated generation of PGE2 in response to a calcium ionophore, as determined by the use of selected PLA2 inhibitors. PGE2 biosynthesis elicited by bacterial-derived peptides or by phagocytic stimuli acting on cell surface receptors also showed to be dependent on cPLA2 activity. We then assessed metabolism of unesterified arachidonic acid (AA), and observed that PGE2 production becomes favored over that of LTB4 with higher AA concentrations. Withdrawal of calcium prevented the generation of PGE2 in response to a calcium ionophore but did not affect the up-regulation of COX-2 or its capacity to convert AA, thus limiting its implication at the level of cPLA2 activation. Of the main eicosanoids produced by neutrophils, only LTB4 was able to up-regulate COX-2 expression. Finally, the only PGE synthase isoform found in neutrophils is microsomal PGE synthase-1; it co-localized with COX-2 and its expression appeared mainly constitutive. These results highlight key differences in regulatory processes of the 5-LO and COX pathways, and enhance our knowledge at several levels in the PGE2 biosynthesis in neutrophils.
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Affiliation(s)
- Mireille St-Onge
- Centre de Recherche en Rhumatologie et Immunologie du CHUQ (CHUL), 2705 Laurier Boulevard, Office T1-49, Sainte-Foy, and Department of Anatomy-Physiology, Faculty of Medicine, Laval University, Quebec, Canada G1V 4G2
| | - Nicolas Flamand
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-0642, USA
| | - Jordane Biarc
- Centre de Recherche en Rhumatologie et Immunologie du CHUQ (CHUL), 2705 Laurier Boulevard, Office T1-49, Sainte-Foy, and Department of Anatomy-Physiology, Faculty of Medicine, Laval University, Quebec, Canada G1V 4G2
| | - Serge Picard
- Centre de Recherche en Rhumatologie et Immunologie du CHUQ (CHUL), 2705 Laurier Boulevard, Office T1-49, Sainte-Foy, and Department of Anatomy-Physiology, Faculty of Medicine, Laval University, Quebec, Canada G1V 4G2
| | - Line Bouchard
- Centre de Recherche en Rhumatologie et Immunologie du CHUQ (CHUL), 2705 Laurier Boulevard, Office T1-49, Sainte-Foy, and Department of Anatomy-Physiology, Faculty of Medicine, Laval University, Quebec, Canada G1V 4G2
| | - Andrée-Anne Dussault
- Centre de Recherche en Rhumatologie et Immunologie du CHUQ (CHUL), 2705 Laurier Boulevard, Office T1-49, Sainte-Foy, and Department of Anatomy-Physiology, Faculty of Medicine, Laval University, Quebec, Canada G1V 4G2
| | - Cynthia Laflamme
- Centre de Recherche en Rhumatologie et Immunologie du CHUQ (CHUL), 2705 Laurier Boulevard, Office T1-49, Sainte-Foy, and Department of Anatomy-Physiology, Faculty of Medicine, Laval University, Quebec, Canada G1V 4G2
| | - Michael J. James
- Rheumatology Unit, Royal Adelaide Hospital, North Terrace, Adelaide, SA 5000, Australia
| | - Gillian E. Caughey
- Rheumatology Unit, Royal Adelaide Hospital, North Terrace, Adelaide, SA 5000, Australia
| | - Leslie G. Cleland
- Rheumatology Unit, Royal Adelaide Hospital, North Terrace, Adelaide, SA 5000, Australia
| | - Pierre Borgeat
- Centre de Recherche en Rhumatologie et Immunologie du CHUQ (CHUL), 2705 Laurier Boulevard, Office T1-49, Sainte-Foy, and Department of Anatomy-Physiology, Faculty of Medicine, Laval University, Quebec, Canada G1V 4G2
| | - Marc Pouliot
- Centre de Recherche en Rhumatologie et Immunologie du CHUQ (CHUL), 2705 Laurier Boulevard, Office T1-49, Sainte-Foy, and Department of Anatomy-Physiology, Faculty of Medicine, Laval University, Quebec, Canada G1V 4G2
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Jethwaney D, Islam MR, Leidal KG, de Bernabe DBV, Campbell KP, Nauseef WM, Gibson BW. Proteomic analysis of plasma membrane and secretory vesicles from human neutrophils. Proteome Sci 2007; 5:12. [PMID: 17692124 PMCID: PMC2075486 DOI: 10.1186/1477-5956-5-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Accepted: 08/10/2007] [Indexed: 11/10/2022] Open
Abstract
Background Polymorphonuclear neutrophils (PMN) constitute an essential cellular component of innate host defense against microbial invasion and exhibit a wide array of responses both to particulate and soluble stimuli. As the cells recruited earliest during acute inflammation, PMN respond rapidly and release a variety of potent cytotoxic agents within minutes of exposure to microbes or their products. PMN rely on the redistribution of functionally important proteins, from intracellular compartments to the plasma membrane and phagosome, as the means by which to respond quickly. To determine the range of membrane proteins available for rapid recruitment during PMN activation, we analyzed the proteins in subcellular fractions enriched for plasma membrane and secretory vesicles recovered from the light membrane fraction of resting PMN after Percoll gradient centrifugation and free-flow electrophoresis purification using mass spectrometry-based proteomics methods. Results To identify the proteins light membrane fractions enriched for plasma membrane vesicles and secretory vesicles, we employed a proteomic approach, first using MALDI-TOF (peptide mass fingerprinting) and then by HPLC-MS/MS using a 3D ion trap mass spectrometer to analyze the two vesicle populations from resting PMN. We identified several proteins that are functionally important but had not previously been recovered in PMN secretory vesicles. Two such proteins, 5-lipoxygenase-activating protein (FLAP) and dysferlin were further validated by immunoblot analysis. Conclusion Our data demonstrate the broad array of proteins present in secretory vesicles that provides the PMN with the capacity for remarkable and rapid reorganization of its plasma membrane after exposure to proinflammatory agents or stimuli.
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Affiliation(s)
| | - Md Rafiqul Islam
- Inflammation Program, Department of Medicine, University of Iowa and Veterans Administration Medical Center, Iowa City, IA 52240, USA
| | - Kevin G Leidal
- Inflammation Program, Department of Medicine, University of Iowa and Veterans Administration Medical Center, Iowa City, IA 52240, USA
| | - Daniel Beltran-Valero de Bernabe
- Howard Hughes Medical Institute, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, Department of Molecular Physiology and Biophysics, Department of Neurology, andDepartment of Internal Medicine, University of Iowa, Iowa City, IA 52240, USA
| | - Kevin P Campbell
- Howard Hughes Medical Institute, Senator Paul D. Wellstone Muscular Dystrophy Cooperative Research Center, Department of Molecular Physiology and Biophysics, Department of Neurology, andDepartment of Internal Medicine, University of Iowa, Iowa City, IA 52240, USA
| | - William M Nauseef
- Inflammation Program, Department of Medicine, University of Iowa and Veterans Administration Medical Center, Iowa City, IA 52240, USA
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Ferguson AD, McKeever BM, Xu S, Wisniewski D, Miller DK, Yamin TT, Spencer RH, Chu L, Ujjainwalla F, Cunningham BR, Evans JF, Becker JW. Crystal Structure of Inhibitor-Bound Human 5-Lipoxygenase-Activating Protein. Science 2007; 317:510-2. [PMID: 17600184 DOI: 10.1126/science.1144346] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Leukotrienes are proinflammatory products of arachidonic acid oxidation by 5-lipoxygenase that have been shown to be involved in respiratory and cardiovascular diseases. The integral membrane protein FLAP is essential for leukotriene biosynthesis. We describe the x-ray crystal structures of human FLAP in complex with two leukotriene biosynthesis inhibitors at 4.0 and 4.2 angstrom resolution, respectively. The structures show that inhibitors bind in membrane-embedded pockets of FLAP, which suggests how these inhibitors prevent arachidonic acid from binding to FLAP and subsequently being transferred to 5-lipoxygenase, thereby preventing leukotriene biosynthesis. This structural information provides a platform for the development of therapeutics for respiratory and cardiovascular diseases.
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Affiliation(s)
- Andrew D Ferguson
- Department of Medicinal Chemistry, Merck Research Laboratories, Rahway, NJ 07065, USA
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Rakonjac M, Fischer L, Provost P, Werz O, Steinhilber D, Samuelsson B, Rådmark O. Coactosin-like protein supports 5-lipoxygenase enzyme activity and up-regulates leukotriene A4 production. Proc Natl Acad Sci U S A 2006; 103:13150-5. [PMID: 16924104 PMCID: PMC1559768 DOI: 10.1073/pnas.0605150103] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Regulation of 5-lipoxygenase (5LO) activity is a key determinant for the biosynthesis of proinflammatory leukotrienes. Coactosin-like protein (CLP) is an F-actin-binding protein that can also bind 5LO. Here, we report that CLP can up-regulate and modulate 5LO activity [formation of 5(S)-hydroperoxy-6-trans-8,11,14-cis-eicosatetraenoic acid (5-HPETE)], 5(S)-hydroxy-6-trans-8,11,14-cis-eicosatetraenoic acid (5-HETE), and 5(S)-trans-5,6-oxido-7,9-trans-11,14-cis-eicosatetraenoic acid (LTA(4)) in vitro. Three findings are presented. First, CLP up-regulates Ca(2+)-induced 5LO activity, in the absence of phosphatidylcholine (membrane). Apparently, CLP can function as a scaffold for 5LO, similar to membranes. Second, CLP gives a considerable (3-fold) increase in the amount of LTA(4) formed by 5LO, when present together with phosphatidylcholine. Third, CLP increases the ratio of 5-HETE/5-HPETE. These effects require protein interaction by Trp residues in ligand-binding loops of the 5LO beta-sandwich; both binding and stimulatory effects of CLP were abolished for the mutant 5LO-W13/75/102A. In polymorphonuclear leukocytes stimulated with Ca(2+) ionophore, both CLP and 5LO associated with the nucleus, whereas in resting cells, CLP and 5LO were cytosolic. These findings establish CLP as a factor relevant for 5LO product formation. Functioning as a 5LO scaffold, CLP may provide a basis for the formation of 5-HETE in the cytosol of different cell types. Furthermore, in stimulated cells, CLP appears to function in a complex together with 5LO and membranes, increasing the capacity of 5LO for leukotriene biosynthesis.
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Affiliation(s)
- Marija Rakonjac
- Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Lutz Fischer
- Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
- Institute of Pharmaceutical Chemistry, University of Frankfurt, Marie-Curie-Strasse 9, D-60439 Frankfurt, Germany; and
| | - Patrick Provost
- Centre de Recherche en Rhumatologie et Immunologie, Centre de Recherche du Centre Hospitalier de l’Université Laval (CHUL), Quebec, QC, Canada G1V 4G2
| | - Oliver Werz
- Institute of Pharmaceutical Chemistry, University of Frankfurt, Marie-Curie-Strasse 9, D-60439 Frankfurt, Germany; and
| | - Dieter Steinhilber
- Institute of Pharmaceutical Chemistry, University of Frankfurt, Marie-Curie-Strasse 9, D-60439 Frankfurt, Germany; and
| | - Bengt Samuelsson
- Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
- To whom correspondence may be addressed. E-mail:
or
| | - Olof Rådmark
- Department of Medical Biochemistry and Biophysics, Division of Physiological Chemistry II, Karolinska Institutet, S-171 77 Stockholm, Sweden
- To whom correspondence may be addressed. E-mail:
or
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