1
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George M, Allerkamp HH, Koshenov Z, Oflaz FE, Tam-Amersdorfer C, Kolesnik T, Rittchen S, Lang M, Fröhlich E, Graier W, Strobl H, Wadsack C. Liver X receptor activation mitigates oxysterol-induced dysfunction in fetoplacental endothelial cells. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159466. [PMID: 38369253 DOI: 10.1016/j.bbalip.2024.159466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Revised: 01/19/2024] [Accepted: 02/12/2024] [Indexed: 02/20/2024]
Abstract
Maintaining the homeostasis of the placental vasculature is of paramount importance for ensuring normal fetal growth and development. Any disruption in this balance can lead to perinatal morbidity. Several studies have uncovered an association between high levels of oxidized cholesterol (oxysterols), and complications during pregnancy, including gestational diabetes mellitus (GDM) and preeclampsia (PE). These complications often coincide with disturbances in placental vascular function. Here, we investigate the role of two oxysterols (7-ketocholesterol, 7β-hydroxycholesterol) in (dys)function of primary fetoplacental endothelial cells (fpEC). Our findings reveal that oxysterols exert a disruptive influence on fpEC function by elevating the production of reactive oxygen species (ROS) and interfering with mitochondrial transmembrane potential, leading to its depolarization. Moreover, oxysterol-treated fpEC exhibited alterations in intracellular calcium (Ca2+) levels, resulting in the reorganization of cell junctions and a corresponding increase in membrane stiffness and vascular permeability. Additionally, we observed an enhanced adhesion of THP-1 monocytes to fpEC following oxysterol treatment. We explored the influence of activating the Liver X Receptor (LXR) with the synthetic agonist T0901317 (TO) on oxysterol-induced endothelial dysfunction in fpEC. Our results demonstrate that LXR activation effectively reversed oxysterol-induced ROS generation, monocyte adhesion, and cell junction permeability in fpEC. Although the effects on mitochondrial depolarization and calcium mobilization did not reach statistical significance, a strong trend towards stabilization of calcium mobilization was evident in LXR-activated cells. Taken together, our results suggest that high levels of systemic oxysterols link to placental vascular dysfunction and LXR agonists may alleviate their impact on fetoplacental vasculature.
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Affiliation(s)
- Meekha George
- Department of Obstetrics and Gynecology, Medical University of Graz, 8036 Graz, Austria.
| | | | - Zhanat Koshenov
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria; Department of Biochemistry, Weill Cornell Medicine, New York, USA
| | - Furkan E Oflaz
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Carmen Tam-Amersdorfer
- Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria
| | | | - Sonja Rittchen
- Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria; Department of Pharmacology, Medical University of Graz, Austria
| | - Magdalena Lang
- Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria
| | | | - Wolfgang Graier
- Gottfried Schatz Research Center for Cell Signaling, Metabolism and Aging, Division of Molecular Biology and Biochemistry, Medical University of Graz, 8010 Graz, Austria
| | - Herbert Strobl
- Otto Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria
| | - Christian Wadsack
- Department of Obstetrics and Gynecology, Medical University of Graz, 8036 Graz, Austria; BioTech-Med, 8010 Graz, Austria.
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2
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George M, Lang M, Gali CC, Babalola JA, Tam-Amersdorfer C, Stracke A, Strobl H, Zimmermann R, Panzenboeck U, Wadsack C. Liver X Receptor Activation Attenuates Oxysterol-Induced Inflammatory Responses in Fetoplacental Endothelial Cells. Cells 2023; 12:cells12081186. [PMID: 37190095 DOI: 10.3390/cells12081186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Revised: 04/06/2023] [Accepted: 04/12/2023] [Indexed: 05/17/2023] Open
Abstract
Oxysterols are oxidized cholesterol derivatives whose systemic levels are found elevated in pregnancy disorders such as gestational diabetes mellitus (GDM). Oxysterols act through various cellular receptors and serve as a key metabolic signal, coordinating inflammation. GDM is a condition of low-grade chronic inflammation accompanied by altered inflammatory profiles in the mother, placenta and fetus. Higher levels of two oxysterols, namely 7-ketocholesterol (7-ketoC) and 7β-hydroxycholesterol (7β-OHC), were observed in fetoplacental endothelial cells (fpEC) and cord blood of GDM offspring. In this study, we tested the effects of 7-ketoC and 7β-OHC on inflammation and investigated the underlying mechanisms involved. Primary fpEC in culture treated with 7-ketoC or 7β-OHC, induced the activation of mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NFκB) signaling, which resulted in the expression of pro-inflammatory cytokines (IL-6, IL-8) and intercellular cell adhesion molecule-1 (ICAM-1). Liver-X receptor (LXR) activation is known to repress inflammation. Treatment with LXR synthetic agonist T0901317 dampened oxysterol-induced inflammatory responses. Probucol, an inhibitor of LXR target gene ATP-binding cassette transporter A-1 (ABCA-1), antagonized the protective effects of T0901317, suggesting a potential involvement of ABCA-1 in LXR-mediated repression of inflammatory signaling in fpEC. TLR-4 inhibitor Tak-242 attenuated pro-inflammatory signaling induced by oxysterols downstream of the TLR-4 inflammatory signaling cascade. Taken together, our findings suggest that 7-ketoC and 7β-OHC contribute to placental inflammation through the activation of TLR-4. Pharmacologic activation of LXR in fpEC decelerates its shift to a pro-inflammatory phenotype in the presence of oxysterols.
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Affiliation(s)
- Meekha George
- Department of Obstetrics and Gynecology, Medical University of Graz, 8036 Graz, Austria
| | - Magdalena Lang
- Otto-Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria
| | | | | | - Carmen Tam-Amersdorfer
- Otto-Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria
| | - Anika Stracke
- Otto-Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria
| | - Herbert Strobl
- Otto-Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria
| | - Robert Zimmermann
- Institute for Molecular Biosciences, University of Graz, 8010 Graz, Austria
| | - Ute Panzenboeck
- Otto-Loewi Research Center for Vascular Biology, Immunology and Inflammation, Division of Immunology, Medical University of Graz, 8010 Graz, Austria
| | - Christian Wadsack
- Department of Obstetrics and Gynecology, Medical University of Graz, 8036 Graz, Austria
- BioTech-Med, 8010 Graz, Austria
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3
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Yang Z, Wang H, Liu N, Zhao K, Sheng Y, Pang H, Shao K, Zhang M, Li S, He N. Algal polysaccharides and derivatives as potential therapeutics for obesity and related metabolic diseases. Food Funct 2022; 13:11387-11409. [DOI: 10.1039/d2fo02185d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The potential and challenges of algal polysaccharides and their derivatives as potential therapeutic agents for obesity and its related metabolic diseases.
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Affiliation(s)
- Zizhen Yang
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Haoyu Wang
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Nian Liu
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Kunyi Zhao
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Yingying Sheng
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Hao Pang
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Kaidi Shao
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Mengyao Zhang
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Shangyong Li
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
| | - Ningning He
- School of Basic Medicine, Qingdao Medical College, Qingdao University, Qingdao, China
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4
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Wan YW, Liu W, Feng MT, Pu J, Zhuang SW, He B, Liu X. LXRβ is involved in the control of platelet production from megakaryocytes. Blood Cells Mol Dis 2021; 89:102568. [PMID: 33862368 DOI: 10.1016/j.bcmd.2021.102568] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 03/30/2021] [Accepted: 03/30/2021] [Indexed: 11/30/2022]
Abstract
Liver X receptor β (LXRβ), a nuclear receptor involved in important cellular processes such as cholesterol, glucose and fatty acid metabolism, was suggested to be involved in platelet aggregation but its detailed roles are not clear. In the present study, we evaluated the contribution of LXRβ to platelet functions and production. In the systemic collagen-epinephrine thrombosis mouse model, LXRβ-deficient mice showed increased area of blood clots compared with control wide-type littermates. The aggregation of LXRβ-deficient platelets in response to ADP was stronger than that of control mice platelets. More importantly, the number of platelets in blood of LXRβ-deficient mice was significantly higher than that of wild-type mice, especially for female mice. Knockdown of LXRβ expression in human megakaryoblastic Dami cells also enhanced cell polyploidization, formation of proplatelets and production of platelet-like particles. Increase in expression levels of proteins related to oxidative phosphorylation such as NADH:ubiquinone oxidoreductase core subunit V1 (Ndufv1) was observed in LXRβ-knockdown Dami cells. The levels of Ndufv1 in LXRβ-deficient mice platelets were also higher than that of wild-type mice. Taken together, our findings suggested LXRβ might participate in control of platelet production from megakaryocytes by regulating mitochondrial metabolism.
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Affiliation(s)
- Yu-Wei Wan
- Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Wang Liu
- Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China
| | - Mu-Ting Feng
- Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China
| | - Jun Pu
- Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China
| | - Shao-Wei Zhuang
- Department of Cardiology, Seventh People's Hospital of Shanghai University of Traditional Chinese Medicine, Shanghai 200137, China
| | - Ben He
- Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China.
| | - Xuan Liu
- Institute of Interdisciplinary Integrative Medicine Research, Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
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5
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Guillemot-Legris O, Muccioli GG. The oxysterome and its receptors as pharmacological targets in inflammatory diseases. Br J Pharmacol 2021; 179:4917-4940. [PMID: 33817775 DOI: 10.1111/bph.15479] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Revised: 03/14/2021] [Accepted: 03/17/2021] [Indexed: 12/15/2022] Open
Abstract
Oxysterols have gained attention over the last decades and are now considered as fully fledged bioactive lipids. The study of their levels in several conditions, including atherosclerosis, obesity and neurodegenerative diseases, led to a better understanding of their involvement in (patho)physiological processes such as inflammation and immunity. For instance, the characterization of the cholesterol-7α,25-dihydroxycholesterol/GPR183 axis and its implication in immunity represents an important step in the oxysterome study. Besides this axis, others were identified as important in several inflammatory pathologies (such as colitis, lung inflammation and atherosclerosis). However, the oxysterome is a complex system notably due to a redundancy of metabolic enzymes and a wide range of receptors. Indeed, deciphering oxysterol roles and identifying the potential receptor(s) involved in a given pathology remain challenging. Oxysterol properties are very diverse, but most of them could be connected by a common component: inflammation. Here, we review the implication of oxysterol receptors in inflammatory diseases.
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Affiliation(s)
- Owein Guillemot-Legris
- Bioanalysis and Pharmacology of Bioactive Lipids Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
| | - Giulio G Muccioli
- Bioanalysis and Pharmacology of Bioactive Lipids Research Group, Louvain Drug Research Institute, Université catholique de Louvain, Brussels, Belgium
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6
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Foster H, Wilson C, Philippou H, Foster R. Progress toward a Glycoprotein VI Modulator for the Treatment of Thrombosis. J Med Chem 2020; 63:12213-12242. [PMID: 32463237 DOI: 10.1021/acs.jmedchem.0c00262] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Pathogenic thrombus formation accounts for the etiology of many serious conditions including myocardial infarction, stroke, deep vein thrombosis, and pulmonary embolism. Despite the development of numerous anticoagulants and antiplatelet agents, the mortality rate associated with these diseases remains high. In recent years, however, significant epidemiological evidence and clinical models have emerged to suggest that modulation of the glycoprotein VI (GPVI) platelet receptor could be harnessed as a novel antiplatelet strategy. As such, many peptidic agents have been described in the past decade, while more recent efforts have focused on the development of small molecule modulators. Herein the rationale for targeting GPVI is summarized and the published GPVI modulators are reviewed, with particular focus on small molecules. A qualitative pharmacophore hypothesis for small molecule ligands at GPVI is also presented.
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Affiliation(s)
- Holly Foster
- School of Chemistry and Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
| | - Clare Wilson
- Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
| | - Helen Philippou
- Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
| | - Richard Foster
- School of Chemistry and Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), School of Medicine, University of Leeds, Leeds LS2 9JT, U.K
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7
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Maczewsky J, Kaiser J, Krippeit-Drews P, Drews G. Approved LXR agonists exert unspecific effects on pancreatic β-cell function. Endocrine 2020; 68:526-535. [PMID: 32146655 PMCID: PMC7308254 DOI: 10.1007/s12020-020-02241-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 02/24/2020] [Indexed: 12/20/2022]
Abstract
Novel agonists of the nuclear liver-X-receptor (LXR) are designed to treat metabolic disorders or cancer. The rationale to develop these new drugs is based on promising results with established LXR agonist like T0901317 and GW3965. LXRα and LXRβ are expressed in β-cells, and expression is increased by T0901317. The aim of the present study was to evaluate whether effects of these drugs on β-cell function are specific and reliably linked to LXR activation. T0901317 and GW3965, widely used as specific LXR agonists, show rapid, non-genomic effects on stimulus-secretion coupling of mouse pancreatic β-cells at low µM concentrations. T0901317 lowered the cytosolic Ca2+ concentration, reduced or completely inhibited action potentials, and decreased insulin secretion. GW3965 exerted similar effects on insulin secretion. T0901317 affected the production of reactive oxygen species and ATP. The involvement of the classical nuclear LXRs in T0901317- and GW3965-mediated effects in β-cells could be ruled out using LXRα, LXRβ and double knockout mice. Our results strongly suggest that LXR agonists, that are considered to be specific for this receptor, interfere with mitochondrial metabolism and metabolism-independent processes in β-cells. Thus, it is indispensable to test novel LXR agonists accompanying to ongoing clinical trials for acute and chronic effects on cell function in cellular systems and/or animal models lacking classical LXRs.
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Affiliation(s)
- Jonas Maczewsky
- Institute of Pharmacy, Department of Pharmacology, University of Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany
| | - Julia Kaiser
- Institute of Pharmacy, Department of Pharmacology, University of Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany
| | - Peter Krippeit-Drews
- Institute of Pharmacy, Department of Pharmacology, University of Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany
| | - Gisela Drews
- Institute of Pharmacy, Department of Pharmacology, University of Tübingen, Auf der Morgenstelle 8, 72076, Tübingen, Germany.
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8
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Abstract
Previous studies reported an inverse association between healthy dietary patterns (such as Mediterranean diet) and the incidence of cardiovascular events. As the mechanism accounting for cardiovascular disease is prevalently due to the atherothrombosis, where a pivotal role is played by platelet activation, it would be arguable that diets with protective effects against cardiovascular disease exert an anti-atherothrombotic effect via inhibition of platelet activation. There are several and sparse typologies of studies, which investigated if single nutrients by diets recognized as having cardiovascular protection may exert an antithrombotic effect. The most investigated nutrients are key components of the Mediterranean diets such as fruits and vegetables, fish, olive oil, and wine; other diets with protective effects include nuts and cocoa. Here we summarize experimental and human interventional studies which investigated the antithrombotic effects of such nutrients in experimental models of thrombosis or analyzed biomarkers of clotting, platelet, and fibrinolysis activation in human; furthermore in vitro studies explored the underlying mechanism at level of several cell lines such as platelets or endothelial cells. In this context, we analyzed if nutrients affect simultaneously or separately clotting, platelet, and fibrinolysis pathways giving special attention to the relationship between oxidative stress and thrombosis as most nutrients are believed to possess antioxidant properties.
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Affiliation(s)
- Francesco Violi
- From the Department of Clinical Internal, Anesthesiologic and Cardiovascular Sciences, Sapienza University of Rome, Italy (F.V., D.P., P.P.).,Mediterranea Cardiocentro, Napoli, Italy (F.V., P.P., R.C.)
| | - Daniele Pastori
- From the Department of Clinical Internal, Anesthesiologic and Cardiovascular Sciences, Sapienza University of Rome, Italy (F.V., D.P., P.P.)
| | - Pasquale Pignatelli
- From the Department of Clinical Internal, Anesthesiologic and Cardiovascular Sciences, Sapienza University of Rome, Italy (F.V., D.P., P.P.).,Mediterranea Cardiocentro, Napoli, Italy (F.V., P.P., R.C.)
| | - Roberto Carnevale
- Mediterranea Cardiocentro, Napoli, Italy (F.V., P.P., R.C.).,Department of Medical-Surgical Sciences and Biotechnologies, Sapienza University of Rome, Italy (R.C.)
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9
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Flora GD, Sahli KA, Sasikumar P, Holbrook LM, Stainer AR, AlOuda SK, Crescente M, Sage T, Unsworth AJ, Gibbins JM. Non-genomic effects of the Pregnane X Receptor negatively regulate platelet functions, thrombosis and haemostasis. Sci Rep 2019; 9:17210. [PMID: 31748641 PMCID: PMC6868193 DOI: 10.1038/s41598-019-53218-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 10/29/2019] [Indexed: 01/30/2023] Open
Abstract
The pregnane X receptor (PXR) is a nuclear receptor (NR), involved in the detoxification of xenobiotic compounds. Recently, its presence was reported in the human vasculature and its ligands were proposed to exhibit anti-atherosclerotic effects. Since platelets contribute towards the development of atherosclerosis and possess numerous NRs, we investigated the expression of PXR in platelets along with the ability of its ligands to modulate platelet activation. The expression of PXR in human platelets was confirmed using immunoprecipitation analysis. Treatment with PXR ligands was found to inhibit platelet functions stimulated by a range of agonists, with platelet aggregation, granule secretion, adhesion and spreading on fibrinogen all attenuated along with a reduction in thrombus formation (both in vitro and in vivo). The effects of PXR ligands were observed in a species-specific manner, and the human-specific ligand, SR12813, was observed to attenuate thrombus formation in vivo in humanised PXR transgenic mice. PXR ligand-mediated inhibition of platelet function was found to be associated with the inhibition of Src-family kinases (SFKs). This study identifies acute, non-genomic regulatory effects of PXR ligands on platelet function and thrombus formation. In combination with the emerging anti-atherosclerotic properties of PXR ligands, these anti-thrombotic effects may provide additional cardio-protective benefits.
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Affiliation(s)
- Gagan D Flora
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK.,Department of Internal Medicine, University of Iowa, Iowa City, IA, USA
| | - Khaled A Sahli
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK.,General Directorate of Medical Services, Ministry of Interior, Riyadh, Kingdom of Saudi Arabia
| | - Parvathy Sasikumar
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK.,Centre for Haematology, Imperial College London, London, UK
| | - Lisa-Marie Holbrook
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK.,School of Cardiovascular Medicine and Sciences, King's College London, London, UK
| | - Alexander R Stainer
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Sarah K AlOuda
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Marilena Crescente
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK.,Centre for Immunobiology, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - Tanya Sage
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - Amanda J Unsworth
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK.,School of Healthcare Science, Manchester Metropolitan University, Manchester, UK
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK.
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10
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Stainer AR, Sasikumar P, Bye AP, Unsworth AJ, Holbrook LM, Tindall M, Lovegrove JA, Gibbins JM. The Metabolites of the Dietary Flavonoid Quercetin Possess Potent Antithrombotic Activity, and Interact with Aspirin to Enhance Antiplatelet Effects. TH OPEN 2019; 3:e244-e258. [PMID: 31367693 PMCID: PMC6667742 DOI: 10.1055/s-0039-1694028] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 06/24/2019] [Indexed: 01/09/2023] Open
Abstract
Quercetin, a dietary flavonoid, has been reported to possess antiplatelet activity. However, its extensive metabolism following ingestion has resulted in difficulty elucidating precise mechanisms of action. In this study, we aimed to characterize the antiplatelet mechanisms of two methylated metabolites of quercetin-isorhamnetin and tamarixetin-and explore potential interactions with aspirin. Isorhamnetin and tamarixetin inhibited human platelet aggregation, and suppressed activatory processes including granule secretion, integrin αIIbβ3 function, calcium mobilization, and spleen tyrosine kinase (Syk)/linker for activation of T cells (LAT) phosphorylation downstream of glycoprotein VI with similar potency to quercetin. All three flavonoids attenuated thrombus formation in an in vitro microfluidic model, and isoquercetin, a 3-O-glucoside of quercetin, inhibited thrombosis in a murine laser injury model. Isorhamnetin, tamarixetin, and quercetin enhanced the antiplatelet effects of aspirin more-than-additively in a plate-based aggregometry assay, reducing aspirin IC 50 values by an order of magnitude, with this synergy maintained in a whole blood test of platelet function. Our data provide mechanistic evidence for the antiplatelet activity of two quercetin metabolites, isorhamnetin and tamarixetin, and suggest a potential antithrombotic role for these flavonoids. In combination with their interactions with aspirin, this may represent a novel avenue of investigation for the development of new antithrombotic strategies and management of current therapies.
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Affiliation(s)
- Alexander R Stainer
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Parvathy Sasikumar
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom.,Centre for Haematology, Imperial College London, London, United Kingdom
| | - Alexander P Bye
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
| | - Amanda J Unsworth
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom.,School of Healthcare Science, Manchester Metropolitan University, Manchester, United Kingdom
| | - Lisa M Holbrook
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom.,School of Cardiovascular Medicine and Sciences, King's College London, London, United Kingdom
| | - Marcus Tindall
- Department of Mathematics and Statistics, University of Reading, Reading, United Kingdom
| | - Julie A Lovegrove
- Department of Food and Nutritional Sciences, Hugh Sinclair Unit of Human Nutrition, University of Reading, Reading, United Kingdom
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, United Kingdom
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11
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Unsworth AJ, Flora GD, Gibbins JM. Non-genomic effects of nuclear receptors: insights from the anucleate platelet. Cardiovasc Res 2019; 114:645-655. [PMID: 29452349 PMCID: PMC5915957 DOI: 10.1093/cvr/cvy044] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 02/13/2018] [Indexed: 12/12/2022] Open
Abstract
Nuclear receptors (NRs) have the ability to elicit two different kinds of responses, genomic and non-genomic. Although genomic responses control gene expression by influencing the rate of transcription, non-genomic effects occur rapidly and independently of transcriptional regulation. Due to their anucleate nature and mechanistically well-characterized and rapid responses, platelets provide a model system for the study of any non-genomic effects of the NRs. Several NRs have been found to be present in human platelets, and multiple NR agonists have been shown to elicit anti-platelet effects by a variety of mechanisms. The non-genomic functions of NRs vary, including the regulation of kinase and phosphatase activity, ion channel function, intracellular calcium levels, and production of second messengers. Recently, the characterization of mechanisms and identification of novel binding partners of NRs have further strengthened the prospects of developing their ligands into potential therapeutics that offer cardio-protective properties in addition to their other defined genomic effects.
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Affiliation(s)
- Amanda J Unsworth
- School of Biological Sciences, Institute of Cardiovascular and Metabolic Research, Harborne Building, Whiteknights, Reading RG6 6AS, Berkshire, UK
| | - Gagan D Flora
- School of Biological Sciences, Institute of Cardiovascular and Metabolic Research, Harborne Building, Whiteknights, Reading RG6 6AS, Berkshire, UK
| | - Jonathan M Gibbins
- School of Biological Sciences, Institute of Cardiovascular and Metabolic Research, Harborne Building, Whiteknights, Reading RG6 6AS, Berkshire, UK
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Salamah MF, Ravishankar D, Vaiyapuri R, Moraes LA, Patel K, Perretti M, Gibbins JM, Vaiyapuri S. The formyl peptide fMLF primes platelet activation and augments thrombus formation. J Thromb Haemost 2019; 17:1120-1133. [PMID: 31033193 PMCID: PMC6617722 DOI: 10.1111/jth.14466] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 04/18/2019] [Indexed: 01/07/2023]
Abstract
Essentials The role of formyl peptide receptor 1 (FPR1) and its ligand, fMLF, in the regulation of platelet function, hemostasis, and thrombosis is largely unknown. Fpr1-deficient mice and selective inhibitors for FPR1 were used to investigate the function of fMLF and FPR1 in platelets. N-formyl-methionyl-leucyl-phenylalanine primes platelet activation and augments thrombus formation, mainly through FPR1 in platelets. Formyl peptide receptor 1 plays a pivotal role in the regulation of platelet function. BACKGROUND Formyl peptide receptors (FPRs) play pivotal roles in the regulation of innate immunity and host defense. The FPRs include three family members: FPR1, FPR2/ALX, and FPR3. The activation of FPR1 by its high-affinity ligand, N-formyl-methionyl-leucyl-phenylalanine (fMLF) (a bacterial chemoattractant peptide), triggers intracellular signaling in immune cells such as neutrophils and exacerbates inflammatory responses to accelerate the clearance of microbial infection. Notably, fMLF has been demonstrated to induce intracellular calcium mobilization and chemotaxis in platelets that are known to play significant roles in the regulation of innate immunity and inflammatory responses. Despite a plethora of research focused on the roles of FPR1 and its ligands such as fMLF on the modulation of immune responses, their impact on the regulation of hemostasis and thrombosis remains unexplored. OBJECTIVE To determine the effects of fMLF on the modulation of platelet reactivity, hemostasis, and thrombus formation. METHODS Selective inhibitors for FPR1 and Fpr1-deficient mice were used to determine the effects of fMLF and FPR1 on platelets using various platelet functional assays. RESULTS N-formyl-methionyl-leucyl-phenylalanine primes platelet activation through inducing distinctive functions and enhances thrombus formation under arterial flow conditions. Moreover, FPR1 regulates normal platelet function as its deficiency in mouse or blockade in human platelets using a pharmacological inhibitor resulted in diminished agonist-induced platelet activation. CONCLUSION Since FPR1 plays critical roles in numerous disease conditions, its influence on the modulation of platelet activation and thrombus formation may provide insights into the mechanisms that control platelet-mediated complications under diverse pathological settings.
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Affiliation(s)
| | | | | | | | - Ketan Patel
- School of Biological SciencesUniversity of ReadingReadingUK
| | - Mauro Perretti
- William Harvey Research Institute, Queen Mary University of LondonLondonUK
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Grover SP, Bergmeier W, Mackman N. Platelet Signaling Pathways and New Inhibitors. Arterioscler Thromb Vasc Biol 2019; 38:e28-e35. [PMID: 29563117 DOI: 10.1161/atvbaha.118.310224] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Steven P Grover
- From the Thrombosis and Hemostasis Program, Division of Hematology and Oncology, Department of Medicine (S.P.G., N.M.) and McAllister Heart Institute and Department of Biochemistry and Biophysics (W.B.), University of North Carolina at Chapel Hill
| | - Wolfgang Bergmeier
- From the Thrombosis and Hemostasis Program, Division of Hematology and Oncology, Department of Medicine (S.P.G., N.M.) and McAllister Heart Institute and Department of Biochemistry and Biophysics (W.B.), University of North Carolina at Chapel Hill
| | - Nigel Mackman
- From the Thrombosis and Hemostasis Program, Division of Hematology and Oncology, Department of Medicine (S.P.G., N.M.) and McAllister Heart Institute and Department of Biochemistry and Biophysics (W.B.), University of North Carolina at Chapel Hill.
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Unsworth AJ, Bye AP, Kriek N, Sage T, Osborne AA, Donaghy D, Gibbins JM. Cobimetinib and trametinib inhibit platelet MEK but do not cause platelet dysfunction. Platelets 2018; 30:762-772. [PMID: 30252580 PMCID: PMC6594423 DOI: 10.1080/09537104.2018.1514107] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The MEK inhibitors cobimetinib and trametinib are used in combination with BRAF inhibitors to treat metastatic melanoma but increase rates of hemorrhage relative to BRAF inhibitors alone. Platelets express several members of the MAPK signalling cascade including MEK1 and MEK2 and ERK1 and ERK2 but their role in platelet function and haemostasis is ambiguous as previous reports have been contradictory. It is therefore unclear if MEK inhibitors might be causing platelet dysfunction and contributing to increased hemorrhage. In the present study we performed pharmacological characterisation of cobimetinib and trametinib in vitro to investigate potential for MEK inhibitors to cause platelet dysfunction. We report that whilst both cobimetinib and trametinib are potent inhibitors of platelet MEK activity, treatment with trametinib did not alter platelet function. Treatment with cobimetinib results in inhibition of platelet aggregation, integrin activation, alpha-granule secretion and adhesion but only at suprapharmacological concentrations. We identified that the inhibitory effects of high concentrations of cobimetinib are associated with off-target inhibition on Akt and PKC. Neither inhibitor caused any alteration in thrombus formation on collagen under flow conditions in vitro. Our findings demonstrate that platelets are able to function normally when MEK activity is fully inhibited, indicating MEK activity is dispensable for normal platelet function. We conclude that the MEK inhibitors cobimetinib and trametinib do not induce platelet dysfunction and are therefore unlikely to contribute to increased incidence of bleeding reported during MEK inhibitor therapy.
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Affiliation(s)
- Amanda J Unsworth
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Alexander P Bye
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Neline Kriek
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Tanya Sage
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Ashley A Osborne
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
| | - Dillon Donaghy
- b Department of Microbiology Immunology and Pathology , Colorado State University , Fort Collins , CO , USA
| | - Jonathan M Gibbins
- a Institute for Cardiovascular and Metabolic Research , University of Reading, School of Biological Sciences , Reading , UK
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Differential effects of and mechanisms underlying the protection of cardiomyocytes by liver-X-receptor subtypes against high glucose stress-induced injury. Biochem Biophys Res Commun 2018; 503:1372-1377. [PMID: 30029876 DOI: 10.1016/j.bbrc.2018.07.050] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Accepted: 07/10/2018] [Indexed: 11/21/2022]
Abstract
Liver-X-receptors (LXRs) are ligand-activated transcription factors belonging to the nuclear receptor superfamily. The two popular homologous receptor subtypes, LXRα and LXRβ, exhibit differential expression patterns, thereby probably playing different roles in different contexts. This study aimed to evaluate the different roles of the two LXR subtypes and the mechanisms underlying their protection of cardiomyocytes against high-glucose stress. Silencing of LXRα, but not LXRβ impaired normal LXR-mediated cardioprotective effects against high glucose-induced oxidative stress, apoptosis, and inflammation. Mechanistically, silencing of small ubiquitin-like modifier (SUMO)1 or SUMO2/3 did not affect LXR-mediated cardioprotective effects; however, these were impaired in response to nuclear receptor corepressor (NCoR) silencing. Together, these findings indicate that LXRα, but not LXRβ, protects against high glucose-induced cardiomyocyte injury, probably via the NCoR-dependent transrepression of downstream target genes.
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El-Gendy BEDM, Goher SS, Hegazy LS, Arief MMH, Burris TP. Recent Advances in the Medicinal Chemistry of Liver X Receptors. J Med Chem 2018; 61:10935-10956. [DOI: 10.1021/acs.jmedchem.8b00045] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Bahaa El-Dien M. El-Gendy
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, United States
- Chemistry Department, Faculty of Science, Benha University, Benha 13518, Egypt
| | - Shaimaa S. Goher
- Chemistry Department, Faculty of Science, Benha University, Benha 13518, Egypt
| | - Lamees S. Hegazy
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri 63104, United States
| | - Mohamed M. H. Arief
- Chemistry Department, Faculty of Science, Benha University, Benha 13518, Egypt
| | - Thomas P. Burris
- Center for Clinical Pharmacology, Washington University School of Medicine and St. Louis College of Pharmacy, St. Louis, Missouri 63110, United States
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Unsworth AJ, Bye AP, Tannetta DS, Desborough MJR, Kriek N, Sage T, Allan HE, Crescente M, Yaqoob P, Warner TD, Jones CI, Gibbins JM. Farnesoid X Receptor and Liver X Receptor Ligands Initiate Formation of Coated Platelets. Arterioscler Thromb Vasc Biol 2017; 37:1482-1493. [PMID: 28619996 PMCID: PMC5526435 DOI: 10.1161/atvbaha.117.309135] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Accepted: 05/30/2017] [Indexed: 12/20/2022]
Abstract
OBJECTIVES The liver X receptors (LXRs) and farnesoid X receptor (FXR) have been identified in human platelets. Ligands of these receptors have been shown to have nongenomic inhibitory effects on platelet activation by platelet agonists. This, however, seems contradictory with the platelet hyper-reactivity that is associated with several pathological conditions that are associated with increased circulating levels of molecules that are LXR and FXR ligands, such as hyperlipidemia, type 2 diabetes mellitus, and obesity. APPROACH AND RESULTS We, therefore, investigated whether ligands for the LXR and FXR receptors were capable of priming platelets to the activated state without stimulation by platelet agonists. Treatment of platelets with ligands for LXR and FXR converted platelets to the procoagulant state, with increases in phosphatidylserine exposure, platelet swelling, reduced membrane integrity, depolarization of the mitochondrial membrane, and microparticle release observed. Additionally, platelets also displayed features associated with coated platelets such as P-selectin exposure, fibrinogen binding, fibrin generation that is supported by increased serine protease activity, and inhibition of integrin αIIbβ3. LXR and FXR ligand-induced formation of coated platelets was found to be dependent on both reactive oxygen species and intracellular calcium mobilization, and for FXR ligands, this process was found to be dependent on cyclophilin D. CONCLUSIONS We conclude that treatment with LXR and FXR ligands initiates coated platelet formation, which is thought to support coagulation but results in desensitization to platelet stimuli through inhibition of αIIbβ3 consistent with their ability to inhibit platelet function and stable thrombus formation in vivo.
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Affiliation(s)
- Amanda J Unsworth
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Alexander P Bye
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Dionne S Tannetta
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Michael J R Desborough
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Neline Kriek
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Tanya Sage
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Harriet E Allan
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Marilena Crescente
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Parveen Yaqoob
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Timothy D Warner
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Chris I Jones
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.)
| | - Jonathan M Gibbins
- From the Institute of Cardiovascular and Metabolic Research, School of Biological Sciences (A.J.U., A.P.B., N.K., T.S., M.C., C.I.J., J.M.G.) and Department of Food and Nutritional Sciences (D.S.T., P.Y.), University of Reading, United Kingdom; Oxford Haemophilia and Thrombosis Centre, Oxford Biomedical Research Centre, Churchill Hospital, United Kingdom (M.J.R.D.); Nuffield Division of Clinical Laboratory Sciences, University of Oxford, United Kingdom (M.J.R.D.); and Blizard Institute, Barts & the London School of Medicine & Dentistry, United Kingdom (H.E.A., M.C., T.D.W.).
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Unsworth AJ, Flora GD, Sasikumar P, Bye AP, Sage T, Kriek N, Crescente M, Gibbins JM. RXR Ligands Negatively Regulate Thrombosis and Hemostasis. Arterioscler Thromb Vasc Biol 2017; 37:812-822. [PMID: 28254816 PMCID: PMC5405776 DOI: 10.1161/atvbaha.117.309207] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Accepted: 02/13/2017] [Indexed: 12/17/2022]
Abstract
Supplemental Digital Content is available in the text. Objective— Platelets have been found to express intracellular nuclear receptors including the retinoid X receptors (RXRα and RXRβ). Treatment of platelets with ligands of RXR has been shown to inhibit platelet responses to ADP and thromboxane A2; however, the effects on responses to other platelet agonists and the underlying mechanism have not been fully characterized. Approach and Results— The effect of 9-cis-retinoic acid, docosahexaenoic acid and methoprene acid on collagen receptor (glycoprotein VI [GPVI]) agonists and thrombin-stimulated platelet function; including aggregation, granule secretion, integrin activation, calcium mobilization, integrin αIIbβ3 outside-in signaling and thrombus formation in vitro and in vivo were determined. Treatment of platelets with RXR ligands resulted in attenuation of platelet functional responses after stimulation by GPVI agonists or thrombin and inhibition of integrin αIIbβ3 outside-in signaling. Treatment with 9-cis-retinoic acid caused inhibition of thrombus formation in vitro and an impairment of thrombosis and hemostasis in vivo. Both RXR ligands stimulated protein kinase A activation, measured by VASP S157 phosphorylation, that was found to be dependent on both cAMP and nuclear factor κ-light-chain-enhancer of activated B cell activity. Conclusions— This study identifies a widespread, negative regulatory role for RXR in the regulation of platelet functional responses and thrombus formation and describes novel events that lead to the upregulation of protein kinase A, a known negative regulator of many aspects of platelet function. This mechanism may offer a possible explanation for the cardioprotective effects described in vivo after treatment with RXR ligands.
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Affiliation(s)
- Amanda J Unsworth
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Gagan D Flora
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Parvathy Sasikumar
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Alexander P Bye
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Tanya Sage
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Neline Kriek
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Marilena Crescente
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom
| | - Jonathan M Gibbins
- From the Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, United Kingdom.
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Unsworth AJ, Kriek N, Bye AP, Naran K, Sage T, Flora GD, Gibbins JM. PPARγ agonists negatively regulate αIIbβ3 integrin outside-in signaling and platelet function through up-regulation of protein kinase A activity. J Thromb Haemost 2017; 15:356-369. [PMID: 27896950 PMCID: PMC5396324 DOI: 10.1111/jth.13578] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Indexed: 12/31/2022]
Abstract
Essentials peroxisome proliferator-activated receptor γ (PPARγ) agonists inhibit platelet function. PPARγ agonists negatively regulate outside-in signaling via integrin αIIbβ3. PPARγ agonists disrupt the interaction of Gα13 with integrin β3. This is attributed to an upregulation of protein kinase A activity. SUMMARY Background Agonists for the peroxisome proliferator-activated receptor (PPARγ) have been shown to have inhibitory effects on platelet activity following stimulation by GPVI and GPCR agonists. Objectives Profound effects on thrombus formation led us to suspect a role for PPARγ agonists in the regulation of integrin αIIbβ3 mediated signaling. Both GPVI and GPCR signaling pathways lead to αIIbβ3 activation, and signaling through αIIbβ3 plays a critical role in platelet function and normal hemostasis. Methods The effects of PPARγ agonists on the regulation of αIIbβ3 outside-in signaling was determined by monitoring the ability of platelets to adhere and spread on fibrinogen and undergo clot retraction. Effects on signaling components downstream of αIIbβ3 activation were also determined following adhesion to fibrinogen by Western blotting. Results Treatment of platelets with PPARγ agonists inhibited platelet adhesion and spreading on fibrinogen and diminished clot retraction. A reduction in phosphorylation of several components of αIIbβ3 signaling, including the integrin β3 subunit, Syk, PLCγ2, focal adhesion kinase (FAK) and Akt, was also observed as a result of reduced interaction of the integrin β3 subunit with Gα13. Studies of VASP phosphorylation revealed that this was because of an increase in PKA activity following treatment with PPARγ receptor agonists. Conclusions This study provides further evidence for antiplatelet actions of PPARγ agonists, identifies a negative regulatory role for PPARγ agonists in the control of integrin αIIbβ3 outside-in signaling, and provides a molecular basis by which the PPARγ agonists negatively regulate platelet activation and thrombus formation.
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Affiliation(s)
- A. J. Unsworth
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - N. Kriek
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - A. P. Bye
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - K. Naran
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - T. Sage
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - G. D. Flora
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - J. M. Gibbins
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
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Arthur JF, Jandeleit-Dahm K, Andrews RK. Platelet Hyperreactivity in Diabetes: Focus on GPVI Signaling-Are Useful Drugs Already Available? Diabetes 2017; 66:7-13. [PMID: 27999100 DOI: 10.2337/db16-1098] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 10/24/2016] [Indexed: 11/13/2022]
Abstract
Adults with diabetes are 2-4 times more likely to suffer from heart disease or ischemic stroke than adults without diabetes, yet standard antiplatelet therapy, which is the cornerstone for primary and secondary prevention of cardiovascular disease, fails in many patients with diabetes. Three independent but often interrelated variables that contribute to platelet hyperreactivity-high blood glucose, oxidative stress, and elevated vascular shear forces-coexist in patients with diabetes, creating a perilous concurrence of risk factors for cardiovascular events. Recent research has focused attention on the platelet-specific collagen receptor glycoprotein VI (GPVI) as a potential antithrombotic target. Signaling events downstream of GPVI are influenced by hyperglycemia, oxidative stress, and shear stress. Importantly, drugs targeting these GPVI signaling pathways are already in existence. The potential to repurpose existing drugs is a high-gain strategy for yielding new antiplatelet agents and could have particular benefit in individuals with diabetes.
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Affiliation(s)
- Jane F Arthur
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
| | | | - Robert K Andrews
- Australian Centre for Blood Diseases, Monash University, Melbourne, Australia
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Unsworth AJ, Bye AP, Gibbins JM. Platelet-Derived Inhibitors of Platelet Activation. PLATELETS IN THROMBOTIC AND NON-THROMBOTIC DISORDERS 2017. [PMCID: PMC7123044 DOI: 10.1007/978-3-319-47462-5_37] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Moraes LA, Unsworth AJ, Vaiyapuri S, Ali MS, Sasikumar P, Sage T, Flora GD, Bye AP, Kriek N, Dorchies E, Molendi-Coste O, Dombrowicz D, Staels B, Bishop-Bailey D, Gibbins JM. Farnesoid X Receptor and Its Ligands Inhibit the Function of Platelets. Arterioscler Thromb Vasc Biol 2016; 36:2324-2333. [PMID: 27758768 DOI: 10.1161/atvbaha.116.308093] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 09/20/2016] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Although initially seemingly paradoxical because of the lack of nucleus, platelets possess many transcription factors that regulate their function through DNA-independent mechanisms. These include the farnesoid X receptor (FXR), a member of the superfamily of ligand-activated transcription factors, that has been identified as a bile acid receptor. In this study, we show that FXR is present in human platelets and FXR ligands, GW4064 and 6α-ethyl-chenodeoxycholic acid, modulate platelet activation nongenomically. APPROACH AND RESULTS FXR ligands inhibited the activation of platelets in response to stimulation of collagen or thrombin receptors, resulting in diminished intracellular calcium mobilization, secretion, fibrinogen binding, and aggregation. Exposure to FXR ligands also reduced integrin αIIbβ3 outside-in signaling and thereby reduced the ability of platelets to spread and to stimulate clot retraction. FXR function in platelets was found to be associated with the modulation of cyclic guanosine monophosphate levels in platelets and associated downstream inhibitory signaling. Platelets from FXR-deficient mice were refractory to the actions of FXR agonists on platelet function and cyclic nucleotide signaling, firmly linking the nongenomic actions of these ligands to the FXR. CONCLUSIONS This study provides support for the ability of FXR ligands to modulate platelet activation. The atheroprotective effects of GW4064, with its novel antiplatelet effects, indicate FXR as a potential target for the prevention of atherothrombotic disease.
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Affiliation(s)
- Leonardo A Moraes
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK.,Department of Physiology & NUS Immunology Program, Centre for Life Sciences, Yong Loo Lin School of Medicine, National University of Singapore, 117456, Singapore
| | - Amanda J Unsworth
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK
| | | | - Marfoua S Ali
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK
| | - Parvathy Sasikumar
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK
| | - Tanya Sage
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK
| | - Gagan D Flora
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK
| | - Alex P Bye
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK
| | - Neline Kriek
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK
| | - Emilie Dorchies
- European Genomic Institute for Diabetes (EGID), F-59000, Lille, France; INSERM UMR1011, F-59000 Lille, France, University of Lille, F-59000 Lille, France; Institut Pasteur de Lille, F-59019 Lille, France
| | - Olivier Molendi-Coste
- European Genomic Institute for Diabetes (EGID), F-59000, Lille, France; INSERM UMR1011, F-59000 Lille, France, University of Lille, F-59000 Lille, France; Institut Pasteur de Lille, F-59019 Lille, France
| | - David Dombrowicz
- European Genomic Institute for Diabetes (EGID), F-59000, Lille, France; INSERM UMR1011, F-59000 Lille, France, University of Lille, F-59000 Lille, France; Institut Pasteur de Lille, F-59019 Lille, France
| | - Bart Staels
- European Genomic Institute for Diabetes (EGID), F-59000, Lille, France; INSERM UMR1011, F-59000 Lille, France, University of Lille, F-59000 Lille, France; Institut Pasteur de Lille, F-59019 Lille, France
| | - David Bishop-Bailey
- Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, NW1 OTU, UK
| | - Jonathan M Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, Harborne Building, University of Reading, Reading, Berkshire, RG6 6AS, UK
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25
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Lipoproteins as modulators of atherothrombosis: From endothelial function to primary and secondary coagulation. Vascul Pharmacol 2016; 82:1-10. [DOI: 10.1016/j.vph.2015.10.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 10/23/2015] [Accepted: 10/26/2015] [Indexed: 12/20/2022]
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Bye AP, Unsworth AJ, Gibbins JM. Platelet signaling: a complex interplay between inhibitory and activatory networks. J Thromb Haemost 2016; 14:918-30. [PMID: 26929147 PMCID: PMC4879507 DOI: 10.1111/jth.13302] [Citation(s) in RCA: 104] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 02/11/2016] [Indexed: 01/22/2023]
Abstract
The role of platelets in hemostasis and thrombosis is dependent on a complex balance of activatory and inhibitory signaling pathways. Inhibitory signals released from the healthy vasculature suppress platelet activation in the absence of platelet receptor agonists. Activatory signals present at a site of injury initiate platelet activation and thrombus formation; subsequently, endogenous negative signaling regulators dampen activatory signals to control thrombus growth. Understanding the complex interplay between activatory and inhibitory signaling networks is an emerging challenge in the study of platelet biology, and necessitates a systematic approach to utilize experimental data effectively. In this review, we will explore the key points of platelet regulation and signaling that maintain platelets in a resting state, mediate activation to elicit thrombus formation, or provide negative feedback. Platelet signaling will be described in terms of key signaling molecules that are common to the pathways activated by platelet agonists and can be described as regulatory nodes for both positive and negative regulators.
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Affiliation(s)
- A P Bye
- Institute of Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - A J Unsworth
- Institute of Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
| | - J M Gibbins
- Institute of Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
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27
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Increased mortality and aggravation of heart failure in liver X receptor-α knockout mice after myocardial infarction. Heart Vessels 2016; 31:1370-9. [PMID: 26753692 DOI: 10.1007/s00380-015-0781-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Accepted: 12/02/2015] [Indexed: 12/23/2022]
Abstract
Liver X receptors, LXRα (NR1H3) and LXRβ (NR1H2), are best known as nuclear oxysterol receptors and physiological master regulators of lipid and cholesterol metabolism. LXRα play a protective role in acute myocardial ischemia/reperfusion (MI/R) injury, but its role in myocardial infarction (MI) is unknown. The present study was undertaken to determine the effect of LXRα knockout on survival and development of chronic heart failure after MI. Wild-type (WT) and LXRα(-/-) mice were subjected to MI followed by serial echocardiographic and histological assessments. Greater myocyte apoptosis and inflammation within the infarcted zones were found in LXRα(-/-) group at 3 days after MI. At 4 weeks post-MI, LXRα(-/-) MI murine hearts demonstrated significantly increased infarct size, reduced ejection fraction (LXRα(-/-) 29.4 % versus WT 34.4 %), aggravated left ventricular (LV) chamber dilation, enhanced fibrosis and reduced angiogenesis. In addition, LXRα(-/-) mice had increased mortality compared with WT mice. LXRα deficiency increases mortality, aggravates pathological injury and LV remodeling induced by MI. Drugs specifically targeting LXRα may be promising in the treatment of MI.
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Emerging role of liver X receptors in cardiac pathophysiology and heart failure. Basic Res Cardiol 2015; 111:3. [PMID: 26611207 PMCID: PMC4661180 DOI: 10.1007/s00395-015-0520-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 11/03/2015] [Indexed: 01/09/2023]
Abstract
Liver X receptors (LXRs) are master regulators of metabolism and have been studied for their pharmacological potential in vascular and metabolic disease. Besides their established role in metabolic homeostasis and disease, there is mounting evidence to suggest that LXRs may exert direct beneficial effects in the heart. Here, we aim to provide a conceptual framework to explain the broad mode of action of LXRs and how LXR signaling may be an important local and systemic target for the treatment of heart failure. We discuss the potential role of LXRs in systemic conditions associated with heart failure, such as hypertension, diabetes, and renal and vascular disease. Further, we expound on recent data that implicate a direct role for LXR activation in the heart, for its impact on cardiomyocyte damage and loss due to ischemia, and effects on cardiac hypertrophy, fibrosis, and myocardial metabolism. Taken together, the accumulating evidence supports the notion that LXRs may represent a novel therapeutic target for the treatment of heart failure.
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Receptor-mediated inhibitory mechanisms and the regulation of platelet function. SCIENCE CHINA-LIFE SCIENCES 2015; 58:1299-301. [PMID: 26588910 DOI: 10.1007/s11427-015-4966-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 09/11/2015] [Indexed: 10/22/2022]
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Tannetta DS, Hunt K, Jones CI, Davidson N, Coxon CH, Ferguson D, Redman CW, Gibbins JM, Sargent IL, Tucker KL. Syncytiotrophoblast Extracellular Vesicles from Pre-Eclampsia Placentas Differentially Affect Platelet Function. PLoS One 2015; 10:e0142538. [PMID: 26551971 PMCID: PMC4638362 DOI: 10.1371/journal.pone.0142538] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 10/22/2015] [Indexed: 11/19/2022] Open
Abstract
Pre-eclampsia (PE) complicates around 3% of all pregnancies and is one of the most common causes of maternal mortality worldwide. The pathophysiology of PE remains unclear however its underlying cause originates from the placenta and manifests as raised blood pressure, proteinuria, vascular or systemic inflammation and hypercoagulation in the mother. Women who develop PE are also at significantly higher risk of subsequently developing cardiovascular (CV) disease. In PE, the failing endoplasmic reticulum, oxidative and inflammatory stressed syncytiotrophoblast layer of the placenta sheds increased numbers of syncytiotrophoblast extracellular vesicles (STBEV) into the maternal circulation. Platelet reactivity, size and concentration are also known to be altered in some women who develop PE, although the underlying reasons for this have not been determined. In this study we show that STBEV from disease free placenta isolated ex vivo by dual placental perfusion associate rapidly with platelets. We provide evidence that STBEV isolated from normal placentas cause platelet activation and that this is increased with STBEV from PE pregnancies. Furthermore, treatment of platelets with aspirin, currently prescribed for women at high risk of PE to reduce platelet aggregation, also inhibits STBEV-induced reversible aggregation of washed platelets. Increased platelet reactivity as a result of exposure to PE placenta derived STBEVs correlates with increased thrombotic risk associated with PE. These observations establish a possible direct link between the clotting disturbances of PE and dysfunction of the placenta, as well as the known increased risk of thromboembolism associated with this condition.
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Affiliation(s)
- Dionne S. Tannetta
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Kathryn Hunt
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Chris I. Jones
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom
| | - Naomi Davidson
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Carmen H. Coxon
- School of Physiology and Pharmacology, University of Bristol, Medical Sciences Building, University Walk, Bristol, United Kingdom
| | - David Ferguson
- Nuffield Department of Clinical Laboratory Science, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom
| | - Christopher W. Redman
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Jonathan M. Gibbins
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, Berkshire, United Kingdom
| | - Ian L. Sargent
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Oxford, United Kingdom
| | - Katherine L. Tucker
- Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, United Kingdom
- * E-mail:
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31
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Qi H, Sheng J. The antihyperlipidemic mechanism of high sulfate content ulvan in rats. Mar Drugs 2015; 13:3407-21. [PMID: 26035020 PMCID: PMC4483636 DOI: 10.3390/md13063407] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2015] [Revised: 05/16/2015] [Accepted: 05/19/2015] [Indexed: 02/03/2023] Open
Abstract
Numerous studies have suggested that hyperlipidemia is closely linked to cardiovascular disease. The aim of this study was to investigate the possible antihyperlipidemia mechanism of HU (high sulfate content of ulvan) in high-cholesterol fed rats. Wistar rats were made hyperlipidemic by feeding with a high-cholesterol diet. HU was administered to these hyperlipidemia rats for 30 days. Lipid levels and the mRNA expressions of FXR, LXR and PPARγ in liver were measured after 30 days of treatment. In the HU-treated groups, the middle dosage group of male rats (total cholesterol (TC): p < 0.01) and the low-dosage group of female rats (TC, LDL-C: p < 0.01) showed stronger activity with respect to antihyperlipidemia. Moreover, some HU groups could upregulate the mRNA expression of FXR and PPARγ and downregulate the expression of LXR. For the male rats, compared with the hyperlipidemia group, the middle dosage HU had the most pronounced effect on increasing the mRNA levels of FXR (p < 0.01); low- and high-dosage HU showed a significant inhibition of the mRNA levels of LXR (p < 0.01). All HU female groups could upregulate the mRNA expression of PPARγ in a concentration-dependent manner. In summary, HU could improve lipid profiles through upregulation of FXR and PPARγ and downregulation of LXR.
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Affiliation(s)
- Huimin Qi
- Weifang Medical University, No.7166 Baotong Road, Weifang 261053, China.
| | - Jiwen Sheng
- Weifang Medical University, No.7166 Baotong Road, Weifang 261053, China.
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Lannan KL, Sahler J, Kim N, Spinelli SL, Maggirwar SB, Garraud O, Cognasse F, Blumberg N, Phipps RP. Breaking the mold: transcription factors in the anucleate platelet and platelet-derived microparticles. Front Immunol 2015; 6:48. [PMID: 25762994 PMCID: PMC4327621 DOI: 10.3389/fimmu.2015.00048] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 01/26/2015] [Indexed: 01/15/2023] Open
Abstract
Platelets are small anucleate blood cells derived from megakaryocytes. In addition to their pivotal roles in hemostasis, platelets are the smallest, yet most abundant, immune cells and regulate inflammation, immunity, and disease progression. Although platelets lack DNA, and thus no functional transcriptional activities, they are nonetheless rich sources of RNAs, possess an intact spliceosome, and are thus capable of synthesizing proteins. Previously, it was thought that platelet RNAs and translational machinery were remnants from the megakaryocyte. We now know that the initial description of platelets as "cellular fragments" is an antiquated notion, as mounting evidence suggests otherwise. Therefore, it is reasonable to hypothesize that platelet transcription factors are not vestigial remnants from megakaryocytes, but have important, if only partly understood functions. Proteins play multiple cellular roles to minimize energy expenditure for maximum cellular function; thus, the same can be expected for transcription factors. In fact, numerous transcription factors have non-genomic roles, both in platelets and in nucleated cells. Our lab and others have discovered the presence and non-genomic roles of transcription factors in platelets, such as the nuclear factor kappa β (NFκB) family of proteins and peroxisome proliferator-activated receptor gamma (PPARγ). In addition to numerous roles in regulating platelet activation, functional transcription factors can be transferred to vascular and immune cells through platelet microparticles. This method of transcellular delivery of key immune molecules may be a vital mechanism by which platelet transcription factors regulate inflammation and immunity. At the very least, platelets are an ideal model cell to dissect out the non-genomic roles of transcription factors in nucleated cells. There is abundant evidence to suggest that transcription factors in platelets play key roles in regulating inflammatory and hemostatic functions.
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Affiliation(s)
- Katie L Lannan
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA
| | - Julie Sahler
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA ; Department of Biological and Environmental Engineering, Cornell University , Ithaca, NY , USA
| | - Nina Kim
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA
| | - Sherry L Spinelli
- Department of Pathology and Laboratory Medicine, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA
| | - Sanjay B Maggirwar
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA
| | - Olivier Garraud
- Faculté de Médecine, Université de Lyon , Saint-Etienne , France
| | - Fabrice Cognasse
- Faculté de Médecine, Université de Lyon , Saint-Etienne , France ; Etablissement Français du Sang Auvergne-Loire , Saint-Etienne , France
| | - Neil Blumberg
- Department of Pathology and Laboratory Medicine, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA
| | - Richard P Phipps
- Department of Microbiology and Immunology, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA ; Department of Pathology and Laboratory Medicine, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA ; Department of Environmental Medicine, University of Rochester School of Medicine and Dentistry , Rochester, NY , USA
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He Q, Pu J, Yuan A, Lau WB, Gao E, Koch WJ, Ma XL, He B. Activation of liver-X-receptor α but not liver-X-receptor β protects against myocardial ischemia/reperfusion injury. Circ Heart Fail 2014; 7:1032-41. [PMID: 25277999 DOI: 10.1161/circheartfailure.114.001260] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Liver-X-receptors, LXRα (NR1H3) and LXRβ (NR1H2), encode 2 different but highly homologous isoforms of transcription factors belonging to the nuclear receptor superfamily. Whether LXRα and LXRβ subtypes have discrete roles in the regulation of cardiac physiology/pathology is unknown. We determine the role of each LXR subtype in myocardial ischemia/reperfusion (MI/R) injury. METHODS AND RESULTS Mice (wild type; those genetically depleted of LXRα, LXRβ, or both; and those overexpressing LXRα or LXRβ by in vivo intramyocardial adenoviral vector) were subjected to MI/R injury. Both LXRα and LXRβ were detected in wild-type mouse heart. LXRα, but not LXRβ, was significantly upregulated after MI/R. Dual activation of LXRα and LXRβ by natural and synthetic agonists reduced myocardial infarction and improved contractile function after MI/R. Mechanistically, LXR activation inhibited MI/R-induced oxidative stress and nitrative stress, attenuated endoplasmic reticulum stress and mitochondrial dysfunction, and reduced cardiomyocyte apoptosis in ischemic/reperfused myocardium. The aforementioned cardioprotective effects of LXR agonists were impaired in the setting of cardiac-specific gene silencing of LXRα, but not LXRβ subtype. Moreover, LXRα/β double-knockout and LXRα-knockout mice, but not LXRβ-knockout mice, increased MI/R injury, exacerbated MI/R-induced oxidative/nitrative stress, and aggravated endoplasmic reticulum stress and mitochondrial dysfunction. Furthermore, cardiac LXRα, not LXRβ, overexpression via adenoviral transfection suppressed MI/R injury. CONCLUSIONS Our study provides the first direct evidence that the LXRα, but not LXRβ, subtype is a novel endogenous cardiac protective receptor against MI/R injury. Drug development strategies specifically targeting LXRα may be beneficial in treating ischemic heart disease.
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Affiliation(s)
- Qing He
- From the Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China (Q.H., J.P., A.Y., B.H.); Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (W.B.L., X.-L.M.); and Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA (E.G., W.J.K.)
| | - Jun Pu
- From the Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China (Q.H., J.P., A.Y., B.H.); Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (W.B.L., X.-L.M.); and Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA (E.G., W.J.K.).
| | - Ancai Yuan
- From the Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China (Q.H., J.P., A.Y., B.H.); Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (W.B.L., X.-L.M.); and Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA (E.G., W.J.K.)
| | - Wayne Bond Lau
- From the Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China (Q.H., J.P., A.Y., B.H.); Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (W.B.L., X.-L.M.); and Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA (E.G., W.J.K.)
| | - Erhe Gao
- From the Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China (Q.H., J.P., A.Y., B.H.); Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (W.B.L., X.-L.M.); and Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA (E.G., W.J.K.)
| | - Walter J Koch
- From the Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China (Q.H., J.P., A.Y., B.H.); Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (W.B.L., X.-L.M.); and Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA (E.G., W.J.K.)
| | - Xin-Liang Ma
- From the Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China (Q.H., J.P., A.Y., B.H.); Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (W.B.L., X.-L.M.); and Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA (E.G., W.J.K.).
| | - Ben He
- From the Department of Cardiology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China (Q.H., J.P., A.Y., B.H.); Department of Emergency Medicine, Thomas Jefferson University, Philadelphia, PA (W.B.L., X.-L.M.); and Center for Translational Medicine, Temple University School of Medicine, Philadelphia, PA (E.G., W.J.K.).
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Liver X receptor β activation induces pyroptosis of human and murine colon cancer cells. Cell Death Differ 2014; 21:1914-24. [PMID: 25124554 DOI: 10.1038/cdd.2014.117] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Revised: 06/28/2014] [Accepted: 07/15/2014] [Indexed: 12/23/2022] Open
Abstract
Liver X receptors (LXRs) have been proposed to have some anticancer properties, through molecular mechanisms that remain elusive. Here we report for the first time that LXR ligands induce caspase-1-dependent cell death of colon cancer cells. Caspase-1 activation requires Nod-like-receptor pyrin domain containing 3 (NLRP3) inflammasome and ATP-mediated P2 × 7 receptor activation. Surprisingly, LXRβ is mainly located in the cytoplasm and has a non-genomic role by interacting with pannexin 1 leading to ATP secretion. Finally, LXR ligands have an antitumoral effect in a mouse colon cancer model, dependent on the presence of LXRβ, pannexin 1, NLRP3 and caspase-1 within the tumor cells. Our results demonstrate that LXRβ, through pannexin 1 interaction, can specifically induce caspase-1-dependent colon cancer cell death by pyroptosis.
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35
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Jones CI, Tucker KL, Sasikumar P, Sage T, Kaiser WJ, Moore C, Emerson M, Gibbins JM. Integrin-linked kinase regulates the rate of platelet activation and is essential for the formation of stable thrombi. J Thromb Haemost 2014; 12:1342-52. [PMID: 24888521 DOI: 10.1111/jth.12620] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Accepted: 05/21/2014] [Indexed: 12/18/2022]
Abstract
BACKGROUND Integrin-linked kinase (ILK) and its associated complex of proteins are involved in many cellular activation processes, including cell adhesion and integrin signaling. We have previously demonstrated that mice with induced platelet ILK deficiency show reduced platelet activation and aggregation, but only a minor bleeding defect. Here, we explore this apparent disparity between the cellular and hemostatic phenotypes. METHODS The impact of ILK inhibition on integrin αII b β3 activation and degranulation was assessed with the ILK-specific inhibitor QLT0267, and a conditional ILK-deficient mouse model was used to assess the impact of ILK deficiency on in vivo platelet aggregation and thrombus formation. RESULTS Inhibition of ILK reduced the rate of both fibrinogen binding and α-granule secretion, but was accompanied by only a moderate reduction in the maximum extent of platelet activation or aggregation in vitro. The reduction in the rate of fibrinogen binding occurred prior to degranulation or translocation of αII b β3 to the platelet surface. The change in the rate of platelet activation in the absence of functional ILK led to a reduction in platelet aggregation in vivo, but did not change the size of thrombi formed following laser injury of the cremaster arteriole wall in ILK-deficient mice. It did, however, result in a marked decrease in the stability of thrombi formed in ILK-deficient mice. CONCLUSION Taken together, the findings of this study indicate that, although ILK is not essential for platelet activation, it plays a critical role in facilitating rapid platelet activation, which is essential for stable thrombus formation.
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Affiliation(s)
- C I Jones
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading, UK
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Abstract
While platelet activation is essential to maintain blood vessel patency and minimize loss of blood upon injury, untimely or excessive activity can lead to unwanted platelet activation and aggregation. Resultant thrombosis has the potential to block blood vessels, causing myocardial infarction or stroke. To tackle this major cause of mortality, clinical therapies that target platelet responsiveness (antiplatelet therapy) can successfully reduce cardiovascular events, especially in people at higher risk; however, all current antiplatelet therapies carry an increased probability of bleeding. This review will evaluate new and emerging targets for antithrombotics, focusing particularly on platelet glycoprotein VI, as blockade or depletion of this platelet-specific receptor conveys benefits in experimental models of thrombosis and thromboinflammation without causing major bleeding complications.
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Affiliation(s)
- Robert K Andrews
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
| | - Jane F Arthur
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
| | - Elizabeth E Gardiner
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, Australia
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Abstract
Statins are widely prescribed cholesterol-lowering drugs that are a first-line treatment of coronary artery disease and atherosclerosis, reducing the incidence of thrombotic events such as myocardial infarction and stroke. Statins have been shown to reduce platelet activation, although the mechanism(s) through which this occurs is unclear. Because several of the characteristic effects of statins on platelets are shared with those elicited by the inhibitory platelet adhesion receptor PECAM-1 (platelet endothelial cell adhesion molecule-1), we investigated a potential connection between the influence of statins on platelet function and PECAM-1 signaling. Statins were found to inhibit a range of platelet functional responses and thrombus formation in vitro and in vivo. Notably, these effects of statins on platelet function in vitro and in vivo were diminished in PECAM-1(-/-) platelets. Activation of PECAM-1 signaling results in its tyrosine phosphorylation, the recruitment and activation of tyrosine phosphatase SHP-2, the subsequent binding of phosphoinositol 3-kinase (PI3K), and diminished PI3K signaling. Statins resulted in the stimulation of these events, leading to the inhibition of Akt activation. Together, these data provide evidence for a fundamental role of PECAM-1 in the inhibitory effects of statins on platelet activation, which may explain some of the pleiotropic actions of these drugs.
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Fan S, Guo L, Zhang Y, Sun Q, Yang B, Huang C. Okra polysaccharide improves metabolic disorders in high-fat diet-induced obese C57BL/6 mice. Mol Nutr Food Res 2013; 57:2075-8. [DOI: 10.1002/mnfr.201300054] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Revised: 04/03/2013] [Accepted: 05/11/2013] [Indexed: 01/01/2023]
Affiliation(s)
- Shengjie Fan
- School of Pharmacy; Shanghai University of Traditional Chinese Medicine; Shanghai P. R. China
| | - Lu Guo
- School of Pharmacy; Shanghai University of Traditional Chinese Medicine; Shanghai P. R. China
| | - Yu Zhang
- School of Pharmacy; Shanghai University of Traditional Chinese Medicine; Shanghai P. R. China
| | - Qinhu Sun
- Institute of Chinese Materia Medica; Shanghai University of Traditional Chinese Medicine; Shanghai P. R. China
| | - Baican Yang
- School of Pharmacy; Shanghai University of Traditional Chinese Medicine; Shanghai P. R. China
| | - Cheng Huang
- School of Pharmacy; Shanghai University of Traditional Chinese Medicine; Shanghai P. R. China
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39
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Schaffer S, Tandon R, Zipse H, Siess W, Schmidt A, Jamasbi J, Karshovska E, Steglich W, Lorenz R. Stereo specific platelet inhibition by the natural LXR agonist 22(R)-OH-cholesterol and its fluorescence labelling with preserved bioactivity and chiral handling in macrophages. Biochem Pharmacol 2013; 86:279-85. [DOI: 10.1016/j.bcp.2013.04.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 04/26/2013] [Accepted: 04/30/2013] [Indexed: 01/15/2023]
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41
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Abstract
Liver X receptors (LXRs) belong to the nuclear receptor superfamily of ligand-dependent transcription factors. LXRs are activated by oxysterols, metabolites of cholesterol, and therefore act as intracellular sensors of this lipid. There are two LXR genes (α and β) that display distinct tissue/cell expression profiles. LXRs interact with regulatory sequences in target genes as heterodimers with retinoid X receptor. Such direct targets of LXR actions include important genes implicated in the control of lipid homeostasis, particularly reverse cholesterol transport. In addition, LXRs attenuate the transcription of genes associated with the inflammatory response indirectly by transrepression. In this review, we describe recent evidence that both highlights the key roles of LXRs in atherosclerosis and inflammation and provides novel insights into the mechanisms underlying their actions. In addition, we discuss the major limitations of LXRs as therapeutic targets for the treatment of atherosclerosis and how these are being addressed.
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Mitchell HL, Gibbins JM, Griffin BA, Lovegrove JA, Stowell JD, Foot E. Food and Health Forum meeting - nutritional approaches to cardiovascular health: workshop report. NUTR BULL 2012. [DOI: 10.1111/j.1467-3010.2012.01984.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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43
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Vaiyapuri S, Hutchinson EG, Ali MS, Dannoura A, Stanley RG, Harrison RA, Bicknell AB, Gibbins JM. Rhinocetin, a venom-derived integrin-specific antagonist inhibits collagen-induced platelet and endothelial cell functions. J Biol Chem 2012; 287:26235-44. [PMID: 22689571 PMCID: PMC3406708 DOI: 10.1074/jbc.m112.381483] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Snaclecs are small non-enzymatic proteins present in viper venoms reported to modulate hemostasis of victims through effects on platelets, vascular endothelial, and smooth muscle cells. In this study, we have isolated and functionally characterized a snaclec that we named "rhinocetin" from the venom of West African gaboon viper, Bitis gabonica rhinoceros. Rhinocetin was shown to comprise α and β chains with the molecular masses of 13.5 and 13 kDa, respectively. Sequence and immunoblot analysis of rhinocetin confirmed this to be a novel snaclec. Rhinocetin inhibited collagen-stimulated activation of human platelets in a dose-dependent manner but displayed no inhibitory effects on glycoprotein VI (collagen receptor) selective agonist, CRP-XL-, ADP-, or thrombin-induced platelet activation. Rhinocetin antagonized the binding of monoclonal antibodies against the α2 subunit of integrin α2β1 to platelets and coimmunoprecipitation analysis confirmed integrin α2β1 as a target for this venom protein. Rhinocetin inhibited a range of collagen-induced platelet functions such as fibrinogen binding, calcium mobilization, granule secretion, aggregation, and thrombus formation. It also inhibited integrin α2β1-dependent functions of human endothelial cells. Together, our data suggest rhinocetin to be a modulator of integrin α2β1 function and thus may provide valuable insights into the role of this integrin in physiological and pathophysiological scenarios, including hemostasis, thrombosis, and envenomation.
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Affiliation(s)
- Sakthivel Vaiyapuri
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Reading RG6 6UB, United Kingdom
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44
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Viennois E, Mouzat K, Dufour J, Morel L, Lobaccaro JM, Baron S. Selective liver X receptor modulators (SLiMs): what use in human health? Mol Cell Endocrinol 2012; 351:129-41. [PMID: 21907760 DOI: 10.1016/j.mce.2011.08.036] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Revised: 08/23/2011] [Accepted: 08/27/2011] [Indexed: 11/28/2022]
Abstract
Liver X receptors (LXR) are members of the nuclear receptor family. As activated transcription factors, their putative association with human diseases makes them promising pharmacological targets because of the large potential to develop ligands. LXR are mainly considered as intracellular cholesterol "sensors" whose activation leads to decreased plasma cholesterol. They also modulate numerous physiological functions: fatty acid synthesis and metabolism, glucose homeostasis, steroidogenesis, immunity, and neurological homeostasis. LXR-deficiency in mouse results in several phenotypes mimicking pathological conditions in humans. This review will be focused on the various natural and synthetic LXR agonists and antagonists. Putative clinical targets including atherosclerosis, diabetes, Alzheimer's disease, skin disorders, and cancer will be covered.
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Affiliation(s)
- Emilie Viennois
- Clermont Université, Université Blaise Pascal, Génétique Reproduction et Développement, BP 10448, F-63000 Clermont-Ferrand, France
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45
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Holbrook LM, Sasikumar P, Stanley RG, Simmonds AD, Bicknell AB, Gibbins JM. The platelet-surface thiol isomerase enzyme ERp57 modulates platelet function. J Thromb Haemost 2012; 10:278-88. [PMID: 22168334 PMCID: PMC3444690 DOI: 10.1111/j.1538-7836.2011.04593.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2011] [Accepted: 11/30/2011] [Indexed: 01/06/2023]
Abstract
BACKGROUND Thiol isomerases are a family of endoplasmic reticulum enzymes which orchestrate redox-based modifications of protein disulphide bonds. Previous studies have identified important roles for the thiol isomerases PDI and ERp5 in the regulation of normal platelet function. AIM Recently, we demonstrated the presence of a further five thiol isomerases at the platelet surface. In this report we aim to report the role of one of these enzymes - ERp57 in the regulation of platelet function. METHODS/RESULTS Using enzyme activity function blocking antibodies, we demonstrate a role for ERp57 in platelet aggregation, dense granule secretion, fibrinogen binding, calcium mobilisation and thrombus formation under arterial conditions. In addition to the effects of ERp57 on isolated platelets, we observe the presence of ERp57 in the developing thrombus in vivo. Furthermore the inhibition of ERp57 function was found to reduce laser-injury induced arterial thrombus formation in a murine model of thrombosis. CONCLUSIONS These data suggest that ERp57 is important for normal platelet function and opens up the possibility that the regulation of platelet function by a range of cell surface thiol isomerases may represent a broad paradigm for the regulation of haemostasis and thrombosis.
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Affiliation(s)
- L-M Holbrook
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, University of Reading, Berkshire, UK.
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46
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Abstract
Abstract
Understanding the cellular mechanisms of platelet activation and their pharmacologic modulation is of major interest for basic and clinical research. Here we introduce a comprehensive human platelet repository (PlateletWeb) for systems biologic analysis of platelets in the functional context of integrated networks. Functional, drug, and pathway associations provide a first systemic insight into various aspects of platelet functionality and pharmacologic regulation. Detailed manual curation of recent platelet proteome and transcriptome studies yielded more than 5000 platelet proteins. Integration of protein-protein interactions with kinase-substrate relationships unraveled the platelet signaling network involving more than 70% of all platelet proteins. Analysis of the platelet kinome in the context of the kinase phylogenetic background revealed an over-representation of tyrosine kinase substrates. The extraction and graphical visualization of specific subnetworks allow identification of all major signaling modules involved in activation and inhibition. An in-depth analysis of DOK1 signaling identifies putative signal modulators of the integrin network. Through integration of various information sources and high curation standards, the PlateletWeb knowledge base offers the systems biologic background for the investigation of signal transduction in human platelets (http://plateletweb.bioapps.biozentrum.uni-wuerzburg.de).
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Jones CI, Barrett NE, Moraes LA, Gibbins JM, Jackson DE. Endogenous inhibitory mechanisms and the regulation of platelet function. Methods Mol Biol 2012; 788:341-66. [PMID: 22130718 DOI: 10.1007/978-1-61779-307-3_23] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The response of platelets to changes in the immediate environment is always a balance between activatory and inhibitory signals, the cumulative effect of which is either activation or quiescence. This is true of platelets in free flowing blood and of their regulation of haemostasis and thrombosis. In this review, we consider the endogenous inhibitory mechanisms that combine to regulate platelet activation. These include those derived from the endothelium (nitric oxide, prostacyclin, CD39), inhibitory receptors on the surface of platelets (platelet endothelial cell adhesion molecule-1, carcinoembryonic antigen cell adhesion molecule 1, G6b-B - including evidence for the role of Ig-ITIM superfamily members in the negative regulation of ITAM-associated GPVI platelet-collagen interactions and GPCR-mediated signalling and in positive regulation of "outside-in" integrin α(IIb)β(3)-mediated signalling), intracellular inhibitory receptors (retinoic X receptor, glucocorticoid receptor, peroxisome proliferator-activated receptors, liver X receptor), and emerging inhibitory pathways (canonical Wnt signalling, Semaphorin 3A, endothelial cell specific adhesion molecule, and junctional adhesion molecule-A).
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Affiliation(s)
- Chris I Jones
- Institute for Cardiovascular and Metabolic Research, School of Biological Sciences, The University of Reading, Reading, UK
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48
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Isoform-specific regulation of a steroid hormone nuclear receptor by an E3 ubiquitin ligase in Drosophila melanogaster. Genetics 2011; 189:871-83. [PMID: 21900267 DOI: 10.1534/genetics.111.132191] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The steroid hormone 20-hydroxyecdysone (20E) regulates gene transcription through the heterodimeric nuclear receptor composed of ecdysone receptor (EcR) and Ultraspiracle (USP). The EcR gene encodes three protein isoforms--A, B1, and B2--with variant N-terminal domains that mediate tissue and developmental stage-specific responses to 20E. Ariadne-1a is a conserved member of the RING finger family of ubiquitin ligases first identified in Drosophila melanogaster. Loss-of-function mutations at key cysteines in either of the two RING finger motifs, as well as general overexpression of this enzyme, cause lethality in pupae, which suggests a requirement in metamorphosis. Here, we show that Ariadne-1a binds specifically the isoform A of EcR and ubiquitylates it. Co-immunoprecipitation experiments indicate that the full sequence of EcRA is required for this binding. Protein levels of EcRA and USP change in opposite directions when those of ARI-1a are genetically altered. This is an isoform-specific, E3-dependent regulatory mechanism for a steroid nuclear receptor. Further, qRT-PCR experiments show that the ARI-1a levels lead to the transcriptional regulation of Eip78C, Eip74EF, Eip75B, and Br-C, as well as that of EcR and usp genes. Thus, the activity of this enzyme results in the regulation of dimerizing receptors at the protein and gene transcription levels. This fine-tuned orchestration by a conserved ubiquitin ligase is required during insect metamorphosis and, likely, in other steroid hormone-controlled processes across species.
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49
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Fabri DR, de Paula EV, Costa DSP, Annichino-Bizzacchi JM, Arruda VR. Novel insights into the development of atherosclerosis in hemophilia A mouse models. J Thromb Haemost 2011; 9:1556-61. [PMID: 21692978 DOI: 10.1111/j.1538-7836.2011.04410.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND Cardiovascular diseases in aging people with hemophilia (PWH) represent a growing concern. The underlying hypocoagulability probably provides a protective effect against acute thrombus formation, but the limited data available show no preventive effect against the development of atherogenesis in PWH. Atherosclerosis-prone mice are attractive tools for the study of atherosclerosis development, and may provide insights into disease progression in PWH. METHODS Severe hemophilia A (factor VIII-deficient [FVIII(o)]) mice were crossed with mice lacking apolipoprotein E (ApoE(-/-)) or mice lacking the LDL receptor (LDLR(-/-)), and then compared to hemostatically normal littermate controls. After mice had received atherogenic diets for 8, 22 or 37 weeks, atherosclerotic lesion size and phenotypic characterization were analyzed in the aortic sinus and whole aortas. RESULTS ApoE(-/-)/FVIII(o) mice showed a time-dependent protective effect against the development of atherosclerosis, beginning after 22 diet-weeks and persisting to 37 diet-weeks in both the aorta sinus and whole aorta as compared with ApoE(-/-) mice. Notably, the FVIII deficiency did not influence the progression of atherosclerosis in the FVIII(o)/LDLR(-/-) model as compared with controls at early or late time points. CONCLUSIONS Hypocoagulability ameliorates vascular disease in the ApoE-deficient model in a lipid-independent manner. Interestingly, FVIII deficiency did not affect the development of atherosclerosis in LDLR(-/-) mice. In contrast to the ApoE model, the LDLR model resembles the lipid profile that is commonly observed in humans with atherosclerosis. These findings, to a certain extent, support the notion of atherosclerosis development in the complete absence of FVIII.
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Affiliation(s)
- D R Fabri
- Hematology and Hemotherapy Center, University of Campinas, Campinas, SP, Brazil
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Liver X Receptor: an oxysterol sensor and a major player in the control of lipogenesis. Chem Phys Lipids 2011; 164:500-14. [PMID: 21693109 DOI: 10.1016/j.chemphyslip.2011.06.004] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2011] [Revised: 06/04/2011] [Accepted: 06/06/2011] [Indexed: 01/12/2023]
Abstract
De novo fatty acid biosynthesis is also called lipogenesis. It is a metabolic pathway that provides the cells with fatty acids required for major cellular processes such as energy storage, membrane structures and lipid signaling. In this article we will review the role of the Liver X Receptors (LXRs), nuclear receptors that sense oxysterols, in the transcriptional regulation of genes involved in lipogenesis.
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