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Munno M, Mallia A, Greco A, Modafferi G, Banfi C, Eligini S. Radical Oxygen Species, Oxidized Low-Density Lipoproteins, and Lectin-like Oxidized Low-Density Lipoprotein Receptor 1: A Vicious Circle in Atherosclerotic Process. Antioxidants (Basel) 2024; 13:583. [PMID: 38790688 PMCID: PMC11118168 DOI: 10.3390/antiox13050583] [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: 04/16/2024] [Revised: 05/06/2024] [Accepted: 05/07/2024] [Indexed: 05/26/2024] Open
Abstract
Atherosclerosis is a complex condition that involves the accumulation of lipids and subsequent plaque formation in the arterial intima. There are various stimuli, cellular receptors, and pathways involved in this process, but oxidative modifications of low-density lipoprotein (ox-LDL) are particularly important in the onset and progression of atherosclerosis. Ox-LDLs promote foam-cell formation, activate proinflammatory pathways, and induce smooth-muscle-cell migration, apoptosis, and cell death. One of the major receptors for ox-LDL is LOX-1, which is upregulated in several cardiovascular diseases, including atherosclerosis. LOX-1 activation in endothelial cells promotes endothelial dysfunction and induces pro-atherogenic signaling, leading to plaque formation. The binding of ox-LDLs to LOX-1 increases the generation of reactive oxygen species (ROS), which can induce LOX-1 expression and oxidize LDLs, contributing to ox-LDL generation and further upregulating LOX-1 expression. This creates a vicious circle that is amplified in pathological conditions characterized by high plasma levels of LDLs. Although LOX-1 has harmful effects, the clinical significance of inhibiting this protein remains unclear. Further studies both in vitro and in vivo are needed to determine whether LOX-1 inhibition could be a potential therapeutic target to counteract the atherosclerotic process.
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Affiliation(s)
- Marco Munno
- Unit of Functional Proteomics, Metabolomics and Network Analysis, Centro Cardiologico Monzino, 20138 Milan, Italy; (M.M.); (A.M.); (A.G.); (G.M.); (S.E.)
| | - Alice Mallia
- Unit of Functional Proteomics, Metabolomics and Network Analysis, Centro Cardiologico Monzino, 20138 Milan, Italy; (M.M.); (A.M.); (A.G.); (G.M.); (S.E.)
- Dipartimento di Biologia e Biotecnologie “Lazzaro Spallanzani”, Università di Pavia, 27100 Pavia, Italy
| | - Arianna Greco
- Unit of Functional Proteomics, Metabolomics and Network Analysis, Centro Cardiologico Monzino, 20138 Milan, Italy; (M.M.); (A.M.); (A.G.); (G.M.); (S.E.)
| | - Gloria Modafferi
- Unit of Functional Proteomics, Metabolomics and Network Analysis, Centro Cardiologico Monzino, 20138 Milan, Italy; (M.M.); (A.M.); (A.G.); (G.M.); (S.E.)
| | - Cristina Banfi
- Unit of Functional Proteomics, Metabolomics and Network Analysis, Centro Cardiologico Monzino, 20138 Milan, Italy; (M.M.); (A.M.); (A.G.); (G.M.); (S.E.)
| | - Sonia Eligini
- Unit of Functional Proteomics, Metabolomics and Network Analysis, Centro Cardiologico Monzino, 20138 Milan, Italy; (M.M.); (A.M.); (A.G.); (G.M.); (S.E.)
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The structural basis of effective LOX-1 inhibition. Future Med Chem 2022; 14:731-743. [PMID: 35466695 DOI: 10.4155/fmc-2022-0011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Along with other scavenger receptors, splice variants of LOX-1 play an important role in modulating numerous subcellular mechanisms such as normal cell development, differentiation and growth in response to physiological stimuli. Thus, LOX-1 activity is a key regulator in determining the severity of many genetic, metabolic, cardiovascular, renal, and neurodegenerative diseases and/or cancer. Increased expression of LOX-1 precipitates pathological disorders during the aging process. Therefore, it becomes important to develop novel LOX-1 inhibitors based on its ligand binding polarity and/or affinity and disrupt the uptake of its ligand: oxidized low-density lipoproteins (ox-LDL). In this review, we shed light on the presently studied and developed novel LOX-1 inhibitors that may have potential for treatment of diseases characterized by LOX-1 activation.
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Vitry J, Paré G, Murru A, Charest-Morin X, Maaroufi H, McLeish KR, Naccache PH, Fernandes MJ. Regulation of the Expression, Oligomerisation and Signaling of the Inhibitory Receptor CLEC12A by Cysteine Residues in the Stalk Region. Int J Mol Sci 2021; 22:ijms221910207. [PMID: 34638548 PMCID: PMC8508511 DOI: 10.3390/ijms221910207] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 09/11/2021] [Accepted: 09/15/2021] [Indexed: 01/26/2023] Open
Abstract
CLEC12A is a myeloid inhibitory receptor that negatively regulates inflammation in mouse models of autoimmune and autoinflammatory arthritis. Reduced CLEC12A expression enhances myeloid cell activation and inflammation in CLEC12A knock-out mice with collagen antibody-induced or gout-like arthritis. Similarly to other C-type lectin receptors, CLEC12A harbours a stalk domain between its ligand binding and transmembrane domains. While it is presumed that the cysteines in the stalk domain have multimerisation properties, their role in CLEC12A expression and/or signaling remain unknown. We thus used site-directed mutagenesis to determine whether the stalk domain cysteines play a role in CLEC12A expression, internalisation, oligomerisation, and/or signaling. Mutation of C118 blocks CLEC12A transport through the secretory pathway diminishing its cell-surface expression. In contrast, mutating C130 does not affect CLEC12A cell-surface expression but increases its oligomerisation, inducing ligand-independent phosphorylation of the receptor. Moreover, we provide evidence that CLEC12A dimerisation is regulated in a redox-dependent manner. We also show that antibody-induced CLEC12A cross-linking induces flotillin oligomerisation in insoluble membrane domains in which CLEC12A signals. Taken together, these data indicate that the stalk cysteines in CLEC12A differentially modulate this inhibitory receptor’s expression, oligomerisation and signaling, suggestive of the regulation of CLEC12A in a redox-dependent manner during inflammation.
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Affiliation(s)
- Julien Vitry
- CHU de Québec Research Center, Division of Infectious Diseases and Immunology, Laval University, Québec, QC G1V 4G2, Canada; (J.V.); (G.P.); (A.M.); (P.H.N.)
- Department of Microbiology-Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Québec, QC G1V 4G2, Canada;
| | - Guillaume Paré
- CHU de Québec Research Center, Division of Infectious Diseases and Immunology, Laval University, Québec, QC G1V 4G2, Canada; (J.V.); (G.P.); (A.M.); (P.H.N.)
- Department of Microbiology-Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Québec, QC G1V 4G2, Canada;
| | - Andréa Murru
- CHU de Québec Research Center, Division of Infectious Diseases and Immunology, Laval University, Québec, QC G1V 4G2, Canada; (J.V.); (G.P.); (A.M.); (P.H.N.)
- Department of Microbiology-Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Québec, QC G1V 4G2, Canada;
| | - Xavier Charest-Morin
- Department of Microbiology-Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Québec, QC G1V 4G2, Canada;
| | - Halim Maaroufi
- Institute of Integrative Biology and Systems, Laval University, Québec, QC G1V 0A6, Canada;
| | - Kenneth R. McLeish
- Department of Medicine, University of Louisville School of Medicine, Louisville, KY 40206, USA;
| | - Paul H. Naccache
- CHU de Québec Research Center, Division of Infectious Diseases and Immunology, Laval University, Québec, QC G1V 4G2, Canada; (J.V.); (G.P.); (A.M.); (P.H.N.)
- Department of Microbiology-Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Québec, QC G1V 4G2, Canada;
| | - Maria J. Fernandes
- CHU de Québec Research Center, Division of Infectious Diseases and Immunology, Laval University, Québec, QC G1V 4G2, Canada; (J.V.); (G.P.); (A.M.); (P.H.N.)
- Department of Microbiology-Infectious Diseases and Immunology, Faculty of Medicine, Laval University, Québec, QC G1V 4G2, Canada;
- Correspondence: ; Tel.: +1-418-656-4141 (ext. 46106)
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Barreto J, Karathanasis SK, Remaley A, Sposito AC. Role of LOX-1 (Lectin-Like Oxidized Low-Density Lipoprotein Receptor 1) as a Cardiovascular Risk Predictor: Mechanistic Insight and Potential Clinical Use. Arterioscler Thromb Vasc Biol 2020; 41:153-166. [PMID: 33176449 DOI: 10.1161/atvbaha.120.315421] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Atherosclerosis, the underlying cause of cardiovascular disease (CVD), is a worldwide cause of morbidity and mortality. Reducing ApoB-containing lipoproteins-chiefly, LDL (low-density lipoprotein)-has been the main strategy for reducing CVD risk. Although supported by large randomized clinical trials, the persistence of residual cardiovascular risk after effective LDL reduction has sparked an intense search for other novel CVD biomarkers and therapeutic targets. Recently, Lox-1 (lectin-type oxidized LDL receptor 1), an innate immune scavenger receptor, has emerged as a promising target for early diagnosis and cardiovascular risk prediction and is also being considered as a treatment target. Lox-1 was first described as a 50 kDa transmembrane protein in endothelial cells responsible for oxLDL (oxidized LDL) recognition, triggering downstream pathways that intensify atherosclerosis via endothelial dysfunction, oxLDL uptake, and apoptosis. Lox-1 is also expressed in platelets, where it enhances platelet activation, adhesion to endothelial cells, and ADP-mediated aggregation, thereby favoring thrombus formation. Lox-1 was also identified in cardiomyocytes, where it was implicated in the development of cardiac fibrosis and myocyte apoptosis, the main determinants of cardiac recovery following an ischemic insult. Together, these findings have revealed that Lox-1 is implicated in all the main steps of atherosclerosis and has encouraged the development of immunoassays for measurement of sLox-1 (serum levels of soluble Lox-1) to be used as a potential CVD biomarker. Finally, the recent development of synthetic Lox-1 inhibitors and neutralizing antibodies with promising results in animal models has made Lox-1 a target for drug development. In this review, we discuss the main findings regarding the role of Lox-1 in the development, diagnosis, and therapeutic strategies for CVD prevention and treatment.
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Affiliation(s)
- Joaquim Barreto
- Atherosclerosis and Vascular Biology Lab (Atherolab), Clinical Research Center, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Brazil (J.B., A.C.S.)
| | - Sotirios K Karathanasis
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD (S.K.K., A.R.)
- NeoProgen, Baltimore, MD (S.K.K.)
| | - Alan Remaley
- National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD (S.K.K., A.R.)
| | - Andrei C Sposito
- Atherosclerosis and Vascular Biology Lab (Atherolab), Clinical Research Center, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Brazil (J.B., A.C.S.)
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A small-molecule inhibitor of lectin-like oxidized LDL receptor-1 acts by stabilizing an inactive receptor tetramer state. Commun Chem 2020; 3:75. [PMID: 36703453 PMCID: PMC9814544 DOI: 10.1038/s42004-020-0321-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 05/15/2020] [Indexed: 01/29/2023] Open
Abstract
The C-type lectin family member lectin-like oxidized LDL receptor-1 (LOX-1) has been object of intensive research. Its modulation may offer a broad spectrum of therapeutic interventions ranging from cardiovascular diseases to cancer. LOX-1 mediates uptake of oxLDL by vascular cells and plays an important role in the initiation of endothelial dysfunction and its progression to atherosclerosis. So far only a few compounds targeting oxLDL-LOX-1 interaction are reported with a limited level of characterization. Here we describe the identification and characterization of BI-0115, a selective small molecule inhibitor of LOX-1 that blocks cellular uptake of oxLDL. Identified by a high throughput screening campaign, biophysical analysis shows that BI-0115 binding triggers receptor inhibition by formation of dimers of the homodimeric ligand binding domain. The structure of LOX-1 bound to BI-0115 shows that inter-ligand interactions at the receptor interfaces are key to the formation of the receptor tetramer thereby blocking oxLDL binding.
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Ramos Gómez TI, Toledo Alonso JR. LOX-1 en las afecciones cardiovasculares, perspectivas terapéuticas futuras. BIONATURA 2020. [DOI: 10.21931/rb/2020.05.02.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
El receptor de la lipoproteína de baja densidad oxidado tipo lectina 1 (LOX-1), también conocido como OLR-1, es un receptor scavenger (SR) clase E, que media la absorción del colesterol LDL en su forma oxidada, por las células vasculares. LOX-1 está involucrado en la disfunción endotelial, la adhesión de monocitos, la proliferación, migración y apoptosis de las células del músculo liso, la formación de células espumosas, la activación de plaquetas, así como la inestabilidad a nivel del endotelio vascular; todos eventos críticos en la patogénesis de la aterosclerosis. LOX-1 contribuyen a la inestabilidad de la placa ateroesclerótica y a las últimas secuelas clínicas de ruptura endotelial e isquemia tisular cardíaca potencialmente mortal. No existe en la actualidad ningún fármaco aprobado o en desarrollo clínico a partir de LOX-1, debido a sus complejos mecanismos biológicos no dilucidados completamente. Se han utilizado diversas terapias con el objetivo de inhibir la acción de LOX-1; medicamentos como: antioxidantes, estatinas, agentes antinflamatorios naturales, que actúen sobre su expresión, pero todos con eficacia moderada. También se ha evaluado la administración de anticuerpos anti-LOX-1 inhibe la aterosclerosis al disminuir eventos celulares. El diseño de fármacos enfocados en el conocimiento de las vías de señalización de LOX-1 y la aplicación de herramientas biotecnológicas permite el desarrollo de nuevas dianas terapéuticas basadas en la potencialidad que tienen los anticuerpos monoclonales. Con estos antecedentes el, receptor LOX-1, representa un objetivo terapéutico atractivo para el tratamiento de enfermedades ateroscleróticas humanas. La evidencia reciente indica que la acción sobre este SR es una posible estrategia para el tratamiento de la enfermedad vascular, explorando en esta revisión su papel y posibles futuras aplicaciones en el diagnóstico y la terapéutica.
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Affiliation(s)
- Thelvia I. Ramos Gómez
- Departamento Ciencias de la Vida y de la Agricultura, Universidad de las Fuerzas Armadas ESPE, Av. General Rumiñahui s/n, PO BOX 171-5-231B, Sangolquí, Ecuador
| | - Jorge Roberto Toledo Alonso
- Laboratorio de Biotecnología y Biofármacos, Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Barrio Universitario s/n, Concepción CP. 4030000, Chile
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7
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Kumari S, Achazi K, Dey P, Haag R, Dernedde J. Design and Synthesis of PEG-Oligoglycerol Sulfates as Multivalent Inhibitors for the Scavenger Receptor LOX-1. Biomacromolecules 2019; 20:1157-1166. [PMID: 30642176 DOI: 10.1021/acs.biomac.8b01416] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a cell surface scavenger receptor. The protein is involved in binding and internalization of oxidized low-density lipoprotein (oxLDL), which leads under pathophysiological circumstances to plaque formation in arteries and initiation of atherosclerosis. A structural feature of LOX-1 relevant to oxLDL binding is the "basic spine" motif consisting of linearly aligned arginine residues stretched over the dimer surface. Inhibition of LOX-1 can be done by blocking these positively charged motifs. Here we report on the design, synthesis, and evaluation of a series of novel LOX-1 inhibitors having different numbers of sulfates and polyethylene glycerol (PEG) spacer. Two molecules, compounds 6b and 6d, showed binding affinity in the low nM range, i.e. 45.8 and 47.4 nM, respectively. The in vitro biological studies reveal that these molecules were also able to block the interaction of LOX-1 with its cognate ligands oxLDL, aged RBC, and bacteria.
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Affiliation(s)
- Shalini Kumari
- Institute for Chemistry and Biochemistry, Freie Universität Berlin , Takustr. 3 , 14195 Berlin , Germany
| | - Katharina Achazi
- Institute for Chemistry and Biochemistry, Freie Universität Berlin , Takustr. 3 , 14195 Berlin , Germany
| | - Pradip Dey
- Institute for Chemistry and Biochemistry, Freie Universität Berlin , Takustr. 3 , 14195 Berlin , Germany
| | - Rainer Haag
- Institute for Chemistry and Biochemistry, Freie Universität Berlin , Takustr. 3 , 14195 Berlin , Germany
| | - Jens Dernedde
- Institute of Laboratory Medicine, Clinical Chemistry and Pathobiochemistry, Charité-Universitätsmedizin Berlin , Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Augustenburger Platz 1 , 13353 Berlin , Germany
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Iacovelli F, Tucci FG, Macari G, Falconi M. Multiple molecular dynamics simulations of human LOX-1 and Trp150Ala mutant reveal the structural determinants causing the full deactivation of the receptor. Proteins 2017; 85:1902-1912. [DOI: 10.1002/prot.25344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 06/21/2017] [Accepted: 06/23/2017] [Indexed: 11/06/2022]
Affiliation(s)
| | | | - Gabriele Macari
- Department of Biology; University of Rome “Tor Vergata”; Rome Italy
| | - Mattia Falconi
- Department of Biology; University of Rome “Tor Vergata”; Rome Italy
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Rane L, Rahman S, Magalhaes I, Ambati A, Andersson J, Zumla A, Brighenti S, Maeurer MJ. IL-7δ5 protein is expressed in human tissues and induces expression of the oxidized low density lipoprotein receptor 1 (OLR1) in CD14+ monocytes. Int J Infect Dis 2017; 59:29-36. [PMID: 28279736 DOI: 10.1016/j.ijid.2017.03.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES The 6-exon-spanning 'canonical' Interleukin-7 (IL-7c) is a non-redundant cytokine in human T-cell homeostasis that undergoes extensive alternative pre-mRNA splicing. The IL-7 gene variant lacking, exon 5 (IL-7δ5), exhibits agonistic effects as compared to IL-7c. We studied in this report for the first time the protein expression of IL-7δ5 variant in tissues and its role in monocyte activation. METHODS We visualized the expression of IL-7δ5 protein by immunohistochemistry in both healthy and malignant (human) tissues and investigated the impact of IL-7δ5 stimulation on CD14+ monocytes using gene expression analysis and flow cytometry. RESULTS IL-7δ5 is largely expressed by human epithelial cells, yet also by stromal cells in malignant lesions. Gene expression analysis in CD14+ monocytes, induced by the 6-exon spanning IL-7 or IL-7δ5 showed similar changes resulting in a pro-inflammatory phenotype and increased expression of genes involved in lipid metabolism. IL7δ5 was superior in inducing upregulation of the oxidised low density lipoprotein receptor (OLR), measured by flow cytometry, in CD14+ cells. CONCLUSION IL-7δ5, produced from non-transformed and transformed cells, may contribute to chronic inflammatory responses and development of 'foamy' cells by increased OLR1 expression that mediates increased oxLDL uptake.
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Affiliation(s)
- Lalit Rane
- Department of Microbiology Tumor and Cell Biology (MTC), Karolinska Institute, 171 77, Stockholm, Sweden.
| | - Sayma Rahman
- Center for Infectious Medicine (CIM), Karolinska Institute, 141 86 Stockholm, Sweden.
| | - Isabelle Magalhaes
- Division of Therapeutic Immunology (TIM), Department of Labroratory Medicine, Karolinska Institute, 141 86, Stockholm, Sweden.
| | - Aditya Ambati
- Division of Therapeutic Immunology (TIM), Department of Labroratory Medicine, Karolinska Institute, 141 86, Stockholm, Sweden; Department of Medicine, Karolinska Institute, 141 86, Stockholm, Sweden.
| | - Jan Andersson
- Center for Infectious Medicine (CIM), Karolinska Institute, 141 86 Stockholm, Sweden.
| | - Alimuddin Zumla
- Centre for Clinical Microbiology, Division of Infection and Immunity, University College London, and NIHR Biomedical Research Centre, UCL Hospitals NHS Foundation Trust, London, United Kingdom.
| | - Susanna Brighenti
- Center for Infectious Medicine (CIM), Karolinska Institute, 141 86 Stockholm, Sweden.
| | - Markus J Maeurer
- Department of Microbiology Tumor and Cell Biology (MTC), Karolinska Institute, 171 77, Stockholm, Sweden; Division of Therapeutic Immunology (TIM), Department of Labroratory Medicine, Karolinska Institute, 141 86, Stockholm, Sweden.
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Puttaruk P, Pipatsatitpong D, Siripurkpong P. Soluble lectin-like oxidized low density lipoprotein receptor-1 in metabolic syndrome. ASIAN BIOMED 2017. [DOI: 10.5372/1905-7415.0905.439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Abstract
Background
Serum levels of soluble lectin-like oxidized low-density lipoprotein receptor-1 (sLOX-1) reflect increases in LOX-1 receptor expression associated with inflammation and metabolic disorders.
Objectives
To examine sLOX-1 levels in metabolic syndrome and association of sLOX-1 with classical risk factors, and with metabolic syndrome, a clustering of metabolic disorders associated with cardiovascular risk factors.
Methods
We selected 148 serum samples from patient participants with metabolic syndrome and 206 samples from patients with non-metabolic syndrome as controls, using the modified National Cholesterol Educational Program Adult Treatment Panel III (NCEP-ATP III) criteria.
Results
Levels of sLOX-1 were increased significantly in participants with metabolic syndrome (P < 0.001). Serum sLOX-1 was positively associated with body mass index (BMI), blood pressure, fasting plasma glucose, triglyceride, and total cholesterol, but negatively associated with high-density lipoprotein cholesterol. Analysis of serum sLOX-1 for metabolic syndrome showed 99.03% specificity and 100% sensitivity. The area under the receiver operating characteristic curve was 0.998 (95%CI 0.996-1.001, P < 0.001). A univariate analysis showed sLOX-1 was significantly correlated with metabolic syndrome, but was not after adjustment for sex, age, blood pressure, and BMI. Multivariate regression analysis found that being overweight (82.3; 95%CI 10.7–631.9), hyperglycemia (1.1; 95%CI 1.1–1.2), and hypertriglyceridemia (1.1; 95%CI 1.0–1.1) were significantly correlated with metabolic syndrome. HDL cholesterol was a protective factor (0.96; 95%CI: 0.93–0.99).
Conclusions
Serum sLOX-1 is a suitable biomarker for diagnosis of metabolic syndrome. However, univariate and multivariate analysis suggested that sLOX-1 may be a modulating factor, and not an independent risk factor.
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Affiliation(s)
- Palakorn Puttaruk
- Department of Medical Technology Laboratory , Thammasat University Hospital , Pathum Thani 12120 , Thailand
| | - Duangnate Pipatsatitpong
- Department of Medical Technology , Faculty of Allied Health Sciences , Thammasat University , Pathum Thani , 12120 , Thailand
| | - Pilaiwan Siripurkpong
- Department of Medical Technology , Faculty of Allied Health Sciences , Thammasat University , Pathum Thani 12120 , Thailand
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LOX-1 and Its Splice Variants: A New Challenge for Atherosclerosis and Cancer-Targeted Therapies. Int J Mol Sci 2017; 18:ijms18020290. [PMID: 28146073 PMCID: PMC5343826 DOI: 10.3390/ijms18020290] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 01/15/2017] [Accepted: 01/23/2017] [Indexed: 12/13/2022] Open
Abstract
Alternative splicing (AS) is a process in which precursor messenger RNA (pre-mRNA) splicing sites are differentially selected to diversify the protein isoform population. Changes in AS patterns have an essential role in normal development, differentiation and response to physiological stimuli. It is documented that AS can generate both “risk” and “protective” splice variants that can contribute to the pathogenesis of several diseases including atherosclerosis. The main endothelial receptor for oxidized low-density lipoprotein (ox-LDLs) is LOX-1 receptor protein encoded by the OLR1 gene. When OLR1 undergoes AS events, it generates three variants: OLR1, OLR1D4 and LOXIN. The latter lacks exon 5 and two-thirds of the functional domain. Literature data demonstrate a protective role of LOXIN in pathologies correlated with LOX-1 overexpression such as atherosclerosis and tumors. In this review, we summarize recent developments in understanding of OLR1 AS while also highlighting data warranting further investigation of this process as a novel therapeutic target.
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Johannes L, Wunder C, Shafaq-Zadah M. Glycolipids and Lectins in Endocytic Uptake Processes. J Mol Biol 2016; 428:S0022-2836(16)30453-3. [PMID: 27984039 DOI: 10.1016/j.jmb.2016.10.027] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 10/24/2016] [Accepted: 10/24/2016] [Indexed: 01/04/2023]
Abstract
A host of endocytic processes has been described at the plasma membrane of eukaryotic cells. Their categorization has most commonly referenced cytosolic machinery, of which the clathrin coat has occupied a preponderant position. In what concerns intra-membrane constituents, the focus of interest has been on phosphatidylinositol lipids and their capacity to orchestrate endocytic events on the cytosolic leaflet of the membrane. The contribution of extracellular determinants to the construction of endocytic pits has received much less attention, depite the fact that (glyco)sphingolipids are exoplasmic leaflet fabric of membrane domains, termed rafts, whose contributions to predominantly clathrin-independent internalization processes is well recognized. Furthermore, sugar modifications on extracellular domains of proteins, and sugar-binding proteins, termed lectins, have also been linked to the uptake of endocytic cargoes at the plasma membrane. In this review, we first summarize these contributions by extracellular determinants to the endocytic process. We thus propose a molecular hypothesis - termed the GL-Lect hypothesis - on how GlycoLipids and Lectins drive the formation of compositional nanoenvrionments from which the endocytic uptake of glycosylated cargo proteins is operated via clathrin-independent carriers. Finally, we position this hypothesis within the global context of endocytic pathway proposals that have emerged in recent years.
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Affiliation(s)
- Ludger Johannes
- Institut Curie, PSL Research University, Chemical Biology of Membranes and Therapeutic Delivery unit, INSERM, U 1143, CNRS, UMR 3666, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
| | - Christian Wunder
- Institut Curie, PSL Research University, Chemical Biology of Membranes and Therapeutic Delivery unit, INSERM, U 1143, CNRS, UMR 3666, 26 rue d'Ulm, 75248 Paris Cedex 05, France
| | - Massiullah Shafaq-Zadah
- Institut Curie, PSL Research University, Chemical Biology of Membranes and Therapeutic Delivery unit, INSERM, U 1143, CNRS, UMR 3666, 26 rue d'Ulm, 75248 Paris Cedex 05, France
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Zeya B, Arjuman A, Chandra NC. Lectin-like Oxidized Low-Density Lipoprotein (LDL) Receptor (LOX-1): A Chameleon Receptor for Oxidized LDL. Biochemistry 2016; 55:4437-44. [DOI: 10.1021/acs.biochem.6b00469] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Bushra Zeya
- Department
of Biochemistry, All India Institute of Medical Sciences, Patna 801507, India
| | - Albina Arjuman
- Division of P&I, Indian Council of Medical Research, New Delhi 110 029, India
| | - Nimai Chand Chandra
- Department
of Biochemistry, All India Institute of Medical Sciences, Patna 801507, India
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14
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Jiang L, Jiang S, Lin Y, Yang H, Zhao Z, Xie Z, Lin Y, Long H. Combination of body mass index and oxidized low density lipoprotein receptor 1 in prognosis prediction of patients with squamous non-small cell lung cancer. Oncotarget 2016; 6:22072-80. [PMID: 26061746 PMCID: PMC4673147 DOI: 10.18632/oncotarget.4299] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2015] [Accepted: 05/22/2015] [Indexed: 01/23/2023] Open
Abstract
Lung cancer, especially non-small cell lung cancer (NSCLC), represents enormous challenges in continuously achieving treatment improvements. Besides cancer, obesity is becoming ever more prevalent. Obesity is increasingly acknowledged as a major risk factor for several types of common cancers. Significant mechanisms overlap in the pathobiology of obesity and tumorigenesis. One of these mechanisms involves oxidized low density lipoprotein receptor 1 (OLR1), as a link between obesity and cancer. Additionally, body mass index (BMI) has been widely used in exploiting the role of obesity on a series of diseases, including cancer. Significantly, squamous NSCLC revealed to be divergent clinical and molecular phenotypes compared with non-squamous NSCLC. Consequently, OLR1 immunostaining score and BMI were assessed by Fisher's linear discriminant analysis to discriminate if progression-free survival (PFS) would exceed 2 years. In addition, the final model was utilized to calculate the discriminant score in each study participant. Finally, 131 patients with squamous NCSLC were eligible for analysis. And a prediction model was established for PFS based on these 2 markers and validated in a second set of squamous NCSLC patients. The model offers a novel tool for survival prediction and could establish a framework for future individualized therapy for patients with squamous NCSLC.
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Affiliation(s)
- Long Jiang
- Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Lung Cancer Institute of Sun Yat-Sen University, Guangzhou, China.,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China.,University of California, San Francisco, San Francisco, CA, USA
| | - Shanshan Jiang
- Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China
| | - Yongbin Lin
- Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Lung Cancer Institute of Sun Yat-Sen University, Guangzhou, China.,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Han Yang
- Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Lung Cancer Institute of Sun Yat-Sen University, Guangzhou, China.,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Zerui Zhao
- Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Lung Cancer Institute of Sun Yat-Sen University, Guangzhou, China.,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Zehua Xie
- Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Lung Cancer Institute of Sun Yat-Sen University, Guangzhou, China.,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Yaobin Lin
- Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Lung Cancer Institute of Sun Yat-Sen University, Guangzhou, China.,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China
| | - Hao Long
- Sun Yat-Sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, China.,Lung Cancer Institute of Sun Yat-Sen University, Guangzhou, China.,Department of Thoracic Oncology, Sun Yat-Sen University Cancer Center, Guangzhou, China
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15
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Thakkar S, Wang X, Khaidakov M, Dai Y, Gokulan K, Mehta JL, Varughese KI. Structure-based Design Targeted at LOX-1, a Receptor for Oxidized Low-Density Lipoprotein. Sci Rep 2015; 5:16740. [PMID: 26578342 PMCID: PMC4649741 DOI: 10.1038/srep16740] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 10/19/2015] [Indexed: 01/16/2023] Open
Abstract
Atherosclerosis related cardiovascular diseases continue to be the primary cause of mortality in developed countries. The elevated level of low density lipoprotein (LDL) is generally considered to be the driver of atherosclerosis, but recent years have seen a shift in this perception in that the vascular plaque buildup is mainly caused by oxidized LDL (ox-LDL) rather than native-LDL. The scavenger receptor LOX-1 found in endothelial cells binds and internalizes ox-LDL which leads to the initiation of plaque formation in arteries. Using virtual screening techniques, we identified a few potential small molecule inhibitors of LOX-1 and tested their inhibitory potential using differential scanning fluorimetry and various cellular assays. Two of these molecules significantly reduced the uptake of ox-LDL by human endothelial cells, LOX-1 transcription and the activation of ERK1/2 and p38 MAPKs in human endothelial cells. In addition, these molecules suppressed ox-LDL-induced VCAM-1 expression and monocyte adhesion onto human endothelial cells demonstrating their therapeutic potential.
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Affiliation(s)
- Shraddha Thakkar
- Department of Physiology and Biophysics College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Xianwei Wang
- Department of Medicine, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Magomed Khaidakov
- Department of Medicine, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Yao Dai
- Department of Medicine, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Kuppan Gokulan
- Department of Physiology and Biophysics College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Jawahar L Mehta
- Department of Physiology and Biophysics College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA.,Department of Medicine, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Kottayil I Varughese
- Department of Physiology and Biophysics College of Medicine, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
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16
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Shaw DJ, Seese R, Ponnambalam S, Ajjan R. The role of lectin-like oxidised low-density lipoprotein receptor-1 in vascular pathology. Diab Vasc Dis Res 2014; 11:410-8. [PMID: 25216847 DOI: 10.1177/1479164114547704] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The lectin-like oxidised low-density lipoprotein receptor-1 (LOX-1) is a vascular scavenger receptor that plays a central role in the pathogenesis of atherothrombotic disease, which remains the main cause of mortality in the Western population. Recent evidence indicates that targeting LOX-1 represents a credible strategy for the management vascular disease and the current review explores the role of this molecule in the diagnosis and treatment of atherosclerosis. LOX-1-mediated pro-atherogenic effects can be inhibited by anti-LOX-1 monoclonal antibodies and procyanidins, whereas downregulation of LOX-1 expression has been achieved by antisense oligonucleotides and a specific pyrrole-imidazole polyamide. Furthermore, LOX-1 can be utilised for plaque imaging using monoclonal antibodies and even the selective delivery of anti-atherosclerotic agents employing immunoliposome techniques. Also, plasma levels of the circulating soluble form of LOX-1 levels are elevated in atherosclerosis and therefore may constitute an additional diagnostic biomarker of vascular pathology.
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Affiliation(s)
- Daniel James Shaw
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), University of Leeds, Leeds, UK
| | - Rachel Seese
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), University of Leeds, Leeds, UK
| | - Sreenivasan Ponnambalam
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), University of Leeds, Leeds, UK
| | - Ramzi Ajjan
- Division of Cardiovascular and Diabetes Research, Leeds Institute of Cardiovascular and Metabolic Medicine (LICAMM), University of Leeds, Leeds, UK
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17
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Simulative and experimental investigation on the cleavage site that generates the soluble human LOX-1. Arch Biochem Biophys 2013; 540:9-18. [PMID: 24113299 DOI: 10.1016/j.abb.2013.10.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/11/2013] [Accepted: 10/01/2013] [Indexed: 12/30/2022]
Abstract
Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a scavenger receptor that mediates the recognition, the binding and internalization of ox-LDL. A truncated soluble form of LOX-1 (sLOX-1) has been identified that, at elevated levels, has been associated to acute coronary syndrome. Human sLOX-1 is the extracellular part of membrane LOX-1 which is cleaved in the NECK domain with a mechanism that has not yet been identified. Purification of human sLOX-1 has been carried out to experimentally identify the cleavage site region within the NECK domain. Molecular modelling and classical molecular dynamics simulation techniques have been used to characterize the structural and dynamical properties of the LOX-1 NECK domain in the presence and absence of the CTLD recognition region, taking into account the obtained proteolysis results. The simulative data indicate that the NECK domain is stabilized by the coiled-coil heptad repeat motif along the simulations, shows a definite flexibility pattern and is characterized by specific electrostatic potentials. The detection of a mobile inter-helix space suggests an explanation for the in vivo susceptibility of the NECK domain to the proteolytic cleavage, validating the assumption that the NECK domain sequence is composed of a coiled-coil motif destabilized in specific regions of functional significance.
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18
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Falconi M, Ciccone S, D’Arrigo P, Viani F, Sorge R, Novelli G, Patrizi P, Desideri A, Biocca S. Design of a novel LOX-1 receptor antagonist mimicking the natural substrate. Biochem Biophys Res Commun 2013; 438:340-5. [DOI: 10.1016/j.bbrc.2013.07.073] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 07/18/2013] [Indexed: 11/16/2022]
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19
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Ulrich-Merzenich G, Zeitler H. The lectin-like oxidized low-density lipoprotein receptor-1 as therapeutic target for atherosclerosis, inflammatory conditions and longevity. Expert Opin Ther Targets 2013; 17:905-19. [PMID: 23738516 DOI: 10.1517/14728222.2013.805748] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
INTRODUCTION The lectin-like oxidized LDL receptor-1 (LOX-1) is a scavenger receptor and is regarded as a central element in the initiation of endothelial dysfunction and its further progression to atherosclerosis. Increasing numbers of studies suggest that therapeutic strategies to modulate LOX-1 will have a broad spectrum of applications ranging from cardiovascular diseases to longevity. AREAS COVERED The dual role of LOX-1 as a culprit molecule in the process of atherosclerosis and as a danger signal in various tissues is introduced. The structure of the receptor, its ligands and its modulation by known drugs, by natural products (e.g., statins, imipramine, salicylate-based drugs, procyanidins, curcumin) and by new strategies (antisenseRNA, miRNA, pyrrole-imidazol-polyamides, LOX-1 antibodies, lipid apheresis) are described. EXPERT OPINION Therapeutic approaches via transcript regulation, allowing a modulation of LOX-1, may be an easier and safer strategy than a blockade of the receptor. Considering the wide distribution of LOX-1 on different tissues, research on the mechanisms of LOX-1 modulation by drugs and natural products applying "omic"-technologies will not only allow a better understanding of the role of LOX-1 in the processes of atherosclerosis, inflammation and longevity but also support the development of specific LOX-1 modulators, avoiding the initiation of molecular mechanisms which lead to adverse events.
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20
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Kumano-Kuramochi M, Xie Q, Kajiwara S, Komba S, Minowa T, Machida S. Lectin-like oxidized LDL receptor-1 is palmitoylated and internalizes ligands via caveolae/raft-dependent endocytosis. Biochem Biophys Res Commun 2013; 434:594-9. [DOI: 10.1016/j.bbrc.2013.03.120] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 03/21/2013] [Indexed: 10/26/2022]
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21
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Di Rienzo C, Jacchetti E, Cardarelli F, Bizzarri R, Beltram F, Cecchini M. Unveiling LOX-1 receptor interplay with nanotopography: mechanotransduction and atherosclerosis onset. Sci Rep 2013; 3:1141. [PMID: 23355954 PMCID: PMC3555090 DOI: 10.1038/srep01141] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 12/17/2012] [Indexed: 12/11/2022] Open
Abstract
Lectin-like ox-LDL receptors (LOX-1) play a crucial role in the ox-LDL–induced pathological transformation of vessel-wall components, a crucial early step in atherogenesis. LOX-1 dynamics is quantitatively investigated in human endothelial cells (HUVECs) exposed to environmental nanotopographies. We demonstrate distinct nanotopography-induced cell phenotypes, characterized by different morphology, LOX-1 diffusivity and oligomerization state: HUVECs on flat surfaces exhibit the behavior found in pro-atherogenic conditions, while growth on nanogratings can interfere with LOX-1 dynamics and lead to a behavior characteristic of normal, non-pathological conditions.
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Affiliation(s)
- Carmine Di Rienzo
- NEST, Istituto Nanoscienze-CNR and Scuola Normale Superiore, Piazza San Silvestro 12 , 56127 Pisa, Italy
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22
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Abstract
Leukocytes play a critical role in recognizing and responding to infection and cancer. Central to this function is an array of cell-surface receptors that lack sequence homology. Many of these receptors have in common the fact that their signaling involves phosphorylation of cytoplasmic domains by extrinsic tyrosine kinases. These non-catalytic tyrosine-phosphorylated receptors (NTRs) share a number of other features, including small size and optimal stimulation by surface-associated ligands. We argue here that NTRs are also likely to share the same kinetic-segregation triggering mechanism, which involves segregation of the engaged NTR from receptor tyrosine phosphatases with large ectodomains such as CD45 and CD148. NTRs signal through tyrosine-containing cytoplasmic motifs, which recruit distinct cytoplasmic signaling proteins when phosphorylated, transducing activatory or inhibitory signals. They have two features that make them uniquely well suited to their role in immune recognition of infection and cancer. Their modular structure enables the coupling of many rapidly evolving receptors with diverse ligand specificities to the same conserved signaling machinery. Their similarity in size and shared signaling machinery enables them to colocalize at cell-cell interfaces when they engage ligands, facilitating the integration of activatory and inhibitory signals from multiple receptors at the cell surface.
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Affiliation(s)
- Omer Dushek
- Sir William Dunn School of Pathology, University of Oxford, UK
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23
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Identification of 4-hydroxy-2-nonenal–histidine adducts that serve as ligands for human lectin-like oxidized LDL receptor-1. Biochem J 2012; 442:171-80. [DOI: 10.1042/bj20111029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) is an endothelial scavenger receptor that is important for the uptake of OxLDL (oxidized low-density lipoprotein) and contributes to the pathogenesis of atherosclerosis. However, the precise structural motifs of OxLDL that are recognized by LOX-1 are unknown. In the present study, we have identified products of lipid peroxidation of OxLDL that serve as ligands for LOX-1. We used CHO (Chinese-hamster ovary) cells that stably express LOX-1 to evaluate the ability of BSA modified by lipid peroxidation to compete with AcLDL (acetylated low-density lipoprotein). We found that HNE (4-hydroxy-2-nonenal)-modified proteins most potently inhibited the uptake of AcLDL. On the basis of the findings that HNE-modified BSA and oxidation of LDL resulted in the formation of HNE–histidine Michael adducts, we examined whether the HNE–histidine adducts could serve as ligands for LOX-1. The authentic HNE–histidine adduct inhibited the uptake of AcLDL in a dose-dependent manner. Furthermore, we found the interaction of LOX-1 with the HNE–histidine adduct to have a dissociation constant of 1.22×10−8 M using a surface plasmon resonance assay. Finally, we showed that the HNE–histidine adduct stimulated the formation of reactive oxygen species and activated extracellular-signal-regulated kinase 1/2 and NF-κB (nuclear factor κB) in HAECs (human aortic endothelial cells); these signals initiate endothelial dysfunction and lead to atherosclerosis. The present study provides intriguing insights into the molecular details of LOX-1 recognition of OxLDL.
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24
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Lü J, Mehta JL. LOX-1: A Critical Player in the Genesis and Progression of Myocardial Ischemia. Cardiovasc Drugs Ther 2011; 25:431-40. [DOI: 10.1007/s10557-011-6329-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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25
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Khaidakov M, Mitra S, Kang BY, Wang X, Kadlubar S, Novelli G, Raj V, Winters M, Carter WC, Mehta JL. Oxidized LDL receptor 1 (OLR1) as a possible link between obesity, dyslipidemia and cancer. PLoS One 2011; 6:e20277. [PMID: 21637860 PMCID: PMC3102697 DOI: 10.1371/journal.pone.0020277] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Accepted: 04/28/2011] [Indexed: 02/01/2023] Open
Abstract
Recent studies have linked expression of lectin-like ox-LDL receptor 1
(OLR1) to tumorigenesis. We analyzed microarray data from
Olr1 knockout (KO) and wild type (WT) mice for genes
involved in cellular transformation and evaluated effects of
OLR1 over-expression in normal mammary epithelial cells
(MCF10A) and breast cancer cells (HCC1143) in terms of gene expression,
migration, adhesion and transendothelial migration. Twenty-six out of 238 genes
were inhibited in tissues of OLR1 KO mice; the vast majority of OLR1 sensitive
genes contained NF-κB binding sites in their promoters. Further studies
revealed broad inhibition of NF-kB target genes outside of the
transformation-associated gene pool, with enrichment themes of defense response,
immune response, apoptosis, proliferation, and wound healing. Transcriptome of
Olr1 KO mice also revealed inhibition of de
novo lipogenesis, rate-limiting enzymes fatty acid synthase
(Fasn), stearoyl-CoA desaturase (Scd1) and
ELOVL family member 6 (Elovl6), as well as lipolytic
phospholipase A2 group IVB (Pla2g4b). In studies comparing
MCF10A and HCC1143, the latter displayed 60% higher OLR1
expression. Forced over-expression of OLR1 resulted in
upregulation of NF-κB (p65) and its target pro-oncogenes involved in
inhibition of apoptosis (BCL2, BCL2A1,
TNFAIP3) and regulation of cell cycle
(CCND2) in both cell lines. Basal expression of
FASN, SCD1 and PLA2G4B,
as well as lipogenesis transcription factors PPARA,
SREBF2 and CREM, was higher in HCC1143
cells. Over-expression of OLR1 in HCC1143 cells also enhanced
cell migration, without affecting their adherence to TNFα-activated
endothelium or transendothelial migration. On the other hand,
OLR1 neutralizing antibody inhibited both adhesion and
transmigration of untreated HCC1143 cells. We conclude that
OLR1 may act as an oncogene by activation of NF-kB target
genes responsible for proliferation, migration and inhibition of apoptosis and
de novo lipogenesis genes.
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Affiliation(s)
- Magomed Khaidakov
- Department of Internal Medicine, College of Medicine, and the Central
Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of
America
- * E-mail: (MK); (JLM)
| | - Sona Mitra
- Department of Internal Medicine, College of Medicine, and the Central
Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of
America
| | - Bum-Yong Kang
- Emory University, Atlanta, Georgia, United States of America
| | - Xianwei Wang
- Department of Internal Medicine, College of Medicine, and the Central
Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of
America
| | - Susan Kadlubar
- Division of Medical Genetics, College of Medicine, University of Arkansas
for Medical Sciences, Little Rock, Arkansas, United States of
America
| | - Giuseppe Novelli
- Department of Genetics, University of Rome “Tor Vergata”,
Rome, Italy
| | - Vinay Raj
- Division of Medical Genetics, College of Medicine, University of Arkansas
for Medical Sciences, Little Rock, Arkansas, United States of
America
| | - Maria Winters
- Department of Internal Medicine, College of Medicine, and the Central
Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of
America
| | - Weleetka C. Carter
- Department of Internal Medicine, College of Medicine, and the Central
Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of
America
| | - Jawahar L. Mehta
- Department of Internal Medicine, College of Medicine, and the Central
Arkansas Veterans Healthcare System, Little Rock, Arkansas, United States of
America
- * E-mail: (MK); (JLM)
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26
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Ohki I, Amida H, Yamada R, Sugihara M, Ishigaki T, Tate SI. Surface plasmon resonance study on functional significance of clustered organization of lectin-like oxidized LDL receptor (LOX-1). BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:345-54. [PMID: 21035571 DOI: 10.1016/j.bbapap.2010.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 10/18/2010] [Accepted: 10/20/2010] [Indexed: 11/16/2022]
Abstract
Lectin-like oxidized low-density lipoprotein (OxLDL) receptor 1 (LOX-1) is the major OxLDL receptor of vascular endothelial cells and is involved in an early step of atherogenesis. LOX-1 exists as a disulfide-linked homodimer on the cell surface, which contains a pair of the ligand-binding domains (CTLD; C-type lectin-like domain). Recent research using living cells has suggested that the clustered state of LOX-1 dimer on the cell is functionally required. These results questioned how LOX-1 exists on the cell to achieve OxLDL binding. In this study, we revealed the functional significance of the clustered organization of the ligand-binding domain of LOX-1 with surface plasmon resonance. Biotinylated CTLD was immobilized on a streptavidin sensor chip to make CTLD clusters on the surface. In this state, the CTLD had high affinity for OxLDL with a dissociation constant (K(D)) in the nanomolar range. This value is comparable to the K(D) measured for LOX-1 on the cell. In contrast, a single homodimeric LOX-1 extracellular domain had lower affinity for OxLDL in the supra-micromolar range of K(D). Monomeric CTLD showed marginal binding to OxLDL. In combination with the analyses on the loss-of-binding mutant W150A, we concluded that the clustered organization of the properly formed homodimeric CTLD is essential for the strong binding of LOX-1 to OxLDL.
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Affiliation(s)
- Izuru Ohki
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0198, Japan
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27
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Navarra T, Del Turco S, Berti S, Basta G. The lectin-like oxidized low-density lipoprotein receptor-1 and its soluble form: cardiovascular implications. J Atheroscler Thromb 2009; 17:317-31. [PMID: 20009416 DOI: 10.5551/jat.3228] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The lectin-like oxidized low density lipoprotein receptor-1 (LOX-1) is a multiligand receptor, whose repertoire of ligands includes oxidized low-density lipoprotein, advanced glycation endproducts, platelets, neutrophils, apoptotic/aged cells and bacteria. Sustained expression of LOX-1 by critical target cells, including endothelial cells, smooth muscle cells and macrophages in proximity to these ligands, sets the stage for chronic cellular activation and tissue damage suggesting the interaction of cellular LOX-1 with its ligands to contribute to the formation and development of atherosclerotic plaques. Studies with transgenic and knockout mouse models have elucidated in part the role of LOX-1 in the pathogenesis of atherosclerosis and cardiac remodeling. Recently, a circulating soluble form of LOX-1 (sLOX-1), corresponding solely to its extracellular domain, has been identified in human serum. Circulating levels of sLOX-1 are increased in inflammatory and atherosclerotic conditions and are associated with acute coronary syndrome, with the severity of coronary artery disease, and with serum biomarkers for oxidative stress and inflammation, suggesting that they could be a useful marker for vascular injury. However, many interesting questions have not yet been answered and in this review, we provide an updated overview of the literature on this receptor and on likely future directions.
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28
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Cao W, Calabro V, Root A, Yan G, Lam K, Olland S, Sanford J, Robak A, Zollner R, Lu Z, Ait-Zahra M, Agostinelli R, Tchistiakova L, Gill D, Harnish D, Paulsen J, Shih HH. Oligomerization is required for the activity of recombinant soluble LOX-1. FEBS J 2009; 276:4909-20. [DOI: 10.1111/j.1742-4658.2009.07190.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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29
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Vohra RS, Walker JH, Howell GJ, Homer-Vanniasinkam S, Ponnambalam S. The LOX-1 scavenger receptor cytoplasmic domain contains a transplantable endocytic motif. Biochem Biophys Res Commun 2009; 383:269-74. [DOI: 10.1016/j.bbrc.2009.04.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2009] [Accepted: 04/02/2009] [Indexed: 01/01/2023]
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30
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Francone OL, Tu M, Royer LJ, Zhu J, Stevens K, Oleynek JJ, Lin Z, Shelley L, Sand T, Luo Y, Kane CD. The hydrophobic tunnel present in LOX-1 is essential for oxidized LDL recognition and binding. J Lipid Res 2008; 50:546-555. [PMID: 18845619 DOI: 10.1194/jlr.m800474-jlr200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lectin-like oxidized LDL (ox-LDL) receptor-1 (LOX-1) is a type-II transmembrane protein that belongs to the C-type lectin family of molecules. LOX-1 acts as a cell surface endocytosis receptor and mediates the recognition and internalization of ox-LDL by vascular endothelial cells. Internalization of ox-LDL by LOX-1 results in a number of pro-atherogenic cellular responses implicated in the development and progression of atherosclerosis. In an effort to elucidate the functional domains responsible for the binding of ox-LDL to the receptor, a series of site-directed mutants were designed using computer modeling and X-ray crystallography to study the functional role of the hydrophobic tunnel present in the LOX-1 receptor. The isoleucine residue (I(149)) sitting at the gate of the channel was replaced by phenylalanine, tyrosine, or glutamic acid to occlude the channel opening and restrict the docking of ligands to test its functional role in the binding of ox-LDL. The synthesis, intracellular processing, and cellular distribution of all mutants were identical to those of wild type, whereas there was a marked decrease in the ability of the mutants to bind ox-LDL. These studies suggest that the central hydrophobic tunnel that extends through the entire LOX-1 molecule is a key functional domain of the receptor and is critical for the recognition of modified LDL.
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Affiliation(s)
- Omar L Francone
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340.
| | - Meihua Tu
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Lori J Royer
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Jian Zhu
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Kimberly Stevens
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Joseph J Oleynek
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Zhiwu Lin
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Lorraine Shelley
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Thomas Sand
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Yi Luo
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
| | - Christopher D Kane
- Department of Atherosclerosis Biology, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340
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Murphy JE, Vohra RS, Dunn S, Holloway ZG, Monaco AP, Homer-Vanniasinkam S, Walker JH, Ponnambalam S. Oxidised LDL internalisation by the LOX-1 scavenger receptor is dependent on a novel cytoplasmic motif and is regulated by dynamin-2. J Cell Sci 2008; 121:2136-47. [PMID: 18544637 DOI: 10.1242/jcs.020917] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The LOX-1 scavenger receptor recognises pro-atherogenic oxidised low-density lipoprotein (OxLDL) particles and is implicated in atherosclerotic plaque formation, but this mechanism is not well understood. Here we show evidence for a novel clathrin-independent and cytosolic-signal-dependent pathway that regulates LOX-1-mediated OxLDL internalisation. Cell surface labelling in the absence or presence of OxLDL ligand showed that LOX-1 is constitutively internalised from the plasma membrane and its half-life is not altered upon ligand binding and trafficking. We show that LOX-1-mediated OxLDL uptake is disrupted by overexpression of dominant-negative dynamin-2 but unaffected by CHC17 or mu2 (AP2) depletion. Site-directed mutagenesis revealed a conserved and novel cytoplasmic tripeptide motif (DDL) that regulates LOX-1-mediated endocytosis of OxLDL. Taken together, these findings indicate that LOX-1 is internalised by a clathrin-independent and dynamin-2-dependent pathway and is thus likely to mediate OxLDL trafficking in vascular tissues.
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Affiliation(s)
- Jane E Murphy
- Endothelial Cell Biology Unit, Leeds Institute of Genetics, Health & Therapeutics, University of Leeds, Clarendon Way, Leeds, LS2 9JT, UK
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The lectin-like oxidized low-density-lipoprotein receptor: a pro-inflammatory factor in vascular disease. Biochem J 2008; 409:349-55. [PMID: 18092947 DOI: 10.1042/bj20071196] [Citation(s) in RCA: 121] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Scavenger receptors are membrane glycoproteins that bind diverse ligands including lipid particles, phospholipids, apoptotic cells and pathogens. LOX-1 (lectin-like oxidized low-density lipoprotein receptor-1) is increasingly linked to atherosclerotic plaque formation. Transgenic mouse models for LOX-1 overexpression or gene knockout suggests that LOX-1 contributes to atherosclerotic plaque formation and progression. LOX-1 activation by oxidized LDL (low-density lipoprotein) binding stimulates intracellular signalling, gene expression and production of superoxide radicals. A key question is the role of leucocyte LOX-1 in pro-atherogenic lipid particle trafficking, accumulation and signalling leading to differentiation into foam cells, necrosis and plaque development. LOX-1 expression is elevated within vascular lesions and a serum soluble LOX-1 fragment appears diagnostic of patients with acute coronary syndromes. LOX-1 is increasingly viewed as a vascular disease biomarker and a potential therapeutic target in heart attack and stroke prevention.
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Biocca S, Filesi I, Mango R, Maggiore L, Baldini F, Vecchione L, Viola A, Citro G, Federici G, Romeo F, Novelli G. The splice variant LOXIN inhibits LOX-1 receptor function through hetero-oligomerization. J Mol Cell Cardiol 2007; 44:561-70. [PMID: 18191942 DOI: 10.1016/j.yjmcc.2007.11.017] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2007] [Accepted: 11/28/2007] [Indexed: 01/13/2023]
Abstract
Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), encoded by the OLR1 gene, is a scavenger receptor that plays a central role in the pathogenesis of atherosclerosis. We have recently identified a truncated naturally occurring variant of the human receptor LOX-1, named LOXIN, which lacks part of the C-terminus lectin-like domain. In vivo and in vitro studies support that the new splicing isoform is protective against acute myocardial infarction. The mechanism by which LOXIN exerts its protective role is unknown. In this paper we report studies on the heterologous expression and functional characterization of LOXIN variant in mammalian fibroblasts and human endothelial cells. We found that LOXIN, when expressed in the absence of LOX-1, shows diminished plasma membrane localization and is deficient in ox-LDL ligand binding. When co-transfected with the full-length counterpart LOX-1, the two isoforms interact to form LOX-1 oligomers and their interaction leads to a decrease in the appearance of LOX-1 receptors in the plasma membrane and a marked impairment of ox-LDL binding and uptake. Co-immunoprecipitation studies confirmed the molecular LOX-1/LOXIN interaction and the formation of non-functional hetero-oligomers. Our studies suggest that hetero-oligomerization between naturally occurring isoforms of LOX-1 may represent a general paradigm for regulation of LOX-1 function by its variants.
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Affiliation(s)
- Silvia Biocca
- Department of Neuroscience and Laboratory of Clinical Biochemistry, University of Tor Vergata, Rome, Italy
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34
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Falconi M, Biocca S, Novelli G, Desideri A. Molecular dynamics simulation of human LOX-1 provides an explanation for the lack of OxLDL binding to the Trp150Ala mutant. BMC STRUCTURAL BIOLOGY 2007; 7:73. [PMID: 17988382 PMCID: PMC2194713 DOI: 10.1186/1472-6807-7-73] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2007] [Accepted: 11/07/2007] [Indexed: 12/21/2022]
Abstract
Background Dimeric lectin-like oxidized low-density lipoprotein receptor-1 LOX-1 is the target receptor for oxidized low density lipoprotein in endothelial cells. In vivo assays revealed that in LOX-1 the basic spine arginine residues are important for binding, which is lost upon mutation of Trp150 with alanine. Molecular dynamics simulations of the wild-type LOX-1 and of the Trp150Ala mutant C-type lectin-like domains, have been carried out to gain insight into the severe inactivating effect. Results The mutation does not alter the dimer stability, but a different dynamical behaviour differentiates the two proteins. As described by the residues fluctuation, the dynamic cross correlation map and the principal component analysis in the wild-type the two monomers display a symmetrical motion that is not observed in the mutant. Conclusion The symmetrical motion of monomers is completely damped by the structural rearrangement caused by the Trp150Ala mutation. An improper dynamical coupling of the monomers and different fluctuations of the basic spine residues are observed, with a consequent altered binding affinity.
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Affiliation(s)
- Mattia Falconi
- Department of Biology and Center of Biostatistics and Bioinformatics, University of Rome Tor Vergata, Via della Ricerca Scientifica, Rome, Italy, 00133.
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MESH Headings
- Animals
- Antihypertensive Agents/pharmacology
- Aorta/metabolism
- Atherosclerosis/blood
- Atherosclerosis/genetics
- Atherosclerosis/metabolism
- Cholesterol, Dietary
- Disease Models, Animal
- Disease Progression
- Endothelium, Vascular/drug effects
- Endothelium, Vascular/metabolism
- Humans
- Hypolipidemic Agents/pharmacology
- Lipoproteins, LDL/blood
- Lipoproteins, LDL/metabolism
- Mice
- Mice, Knockout
- Reactive Oxygen Species/metabolism
- Receptors, LDL/genetics
- Scavenger Receptors, Class E/genetics
- Scavenger Receptors, Class E/metabolism
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36
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Lectin-like oxidized low-density lipoprotein receptor-1: protein, ligands, expression and pathophysiological significance. Chin Med J (Engl) 2007. [DOI: 10.1097/00029330-200703010-00015] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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37
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Matsunaga S, Xie Q, Kumano M, Niimi S, Sekizawa K, Sakakibara Y, Komba S, Machida S. Lectin-like oxidized low-density lipoprotein receptor (LOX-1) functions as an oligomer and oligomerization is dependent on receptor density. Exp Cell Res 2007; 313:1203-14. [PMID: 17306253 DOI: 10.1016/j.yexcr.2007.01.007] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2006] [Revised: 12/01/2006] [Accepted: 01/10/2007] [Indexed: 10/23/2022]
Abstract
Lectin-like oxidized low-density lipoprotein (LDL) receptor (LOX-1) exists as a homodimer formed by an intermolecular disulfide bond. Although the dimer is the minimum structural unit of LOX-1 on cell membranes, LOX-1 can form larger noncovalent oligomeric complexes. But, the functional unit of LOX-1 is not known. We quantitatively analyzed the correlation between cyan fluorescent protein-tagged LOX-1 expression and the fluorescence-labeled ligand (DiD-AcLDL) binding ability on each cell. The results clearly indicate that there is a threshold level of expression that enables LOX-1 to bind ligand. Above this threshold level, the ability of LOX-1 to bind ligand was proportional to its level of expression. Using the membrane impermeable crosslinker BS(3), we detected oligomers (primarily hexamers) only on the cell lines that stably expressed LOX-1 above the threshold level. In contrast, little oligomer or ligand binding was detected in cell lines expressing LOX-1 below the threshold level. Moreover, oligomerization was independent of ligand binding. These results indicate that the functional unit of LOX-1 is an oligomer and that oligomerization of LOX-1 is dependent on the receptor density on the plasma membrane.
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Affiliation(s)
- Shigeru Matsunaga
- National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan
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38
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Marshall ASJ, Willment JA, Pyz E, Dennehy KM, Reid DM, Dri P, Gordon S, Wong SYC, Brown GD. Human MICL (CLEC12A) is differentially glycosylated and is down-regulated following cellular activation. Eur J Immunol 2006; 36:2159-69. [PMID: 16838277 DOI: 10.1002/eji.200535628] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
C-type lectins are the most diverse and prevalent lectin family in immunity. Particular interest has recently been attracted by the C-type lectin-like receptors on NK cells, which appear to regulate the activation/inhibitory balance of these cells, controlling cytotoxicity and cytokine production. We previously identified a human C-type lectin-like receptor, closely related to both the beta-glucan receptor and the lectin-like receptor for oxidized-LDL, named MICL (myeloid inhibitory C-type lectin-like receptor), which we had shown using chimeric analysis to function as an inhibitory receptor. Using a novel MICL-specific monoclonal antibody, we show here that human MICL is expressed primarily on myeloid cells, including granulocytes, monocytes, macrophages, and dendritic cells. Although MICL was highly N-glycosylated in primary cells, the level of glycosylation was found to vary between cell types. MICL surface expression was down-regulated during inflammatory/activation conditions in vitro, as well as during an in vivo model of acute inflammation, which we characterize here. This suggests that human MICL may be involved in the control of myeloid cell activation during inflammation.
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39
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Murphy JE, Tedbury PR, Homer-Vanniasinkam S, Walker JH, Ponnambalam S. Biochemistry and cell biology of mammalian scavenger receptors. Atherosclerosis 2006; 182:1-15. [PMID: 15904923 DOI: 10.1016/j.atherosclerosis.2005.03.036] [Citation(s) in RCA: 247] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Revised: 03/10/2005] [Accepted: 03/24/2005] [Indexed: 01/14/2023]
Abstract
Scavenger receptors are integral membrane proteins that bind a wide variety of ligands including modified or oxidised low-density lipoproteins, apoptotic cells and pathogens. Modified low-density lipoprotein accumulation is thought to be an early event in vascular disease and thus scavenger receptor function is critical in this context. The scavenger receptor family has at least eight different subclasses (A-H) which bear little sequence homology to each other but recognize common ligands. Here we review our current understanding of the scavenger receptor subclasses with emphasis on their genetics, protein structure, biochemical properties, membrane trafficking, intracellular signalling and links to disease states. We also highlight emerging areas where scavenger receptors play roles in cell and animal physiology.
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Affiliation(s)
- Jane E Murphy
- School of Biochemistry and Microbiology, University of Leeds, Leeds LS2 9JT, UK
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40
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Taylor PR, Martinez-Pomares L, Stacey M, Lin HH, Brown GD, Gordon S. Macrophage receptors and immune recognition. Annu Rev Immunol 2005; 23:901-44. [PMID: 15771589 DOI: 10.1146/annurev.immunol.23.021704.115816] [Citation(s) in RCA: 926] [Impact Index Per Article: 48.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Macrophages express a broad range of plasma membrane receptors that mediate their interactions with natural and altered-self components of the host as well as a range of microorganisms. Recognition is followed by surface changes, uptake, signaling, and altered gene expression, contributing to homeostasis, host defense, innate effector mechanisms, and the induction of acquired immunity. This review covers recent studies of selected families of structurally defined molecules, studies that have improved understanding of ligand discrimination in the absence of opsonins and differential responses by macrophages and related myeloid cells.
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Affiliation(s)
- P R Taylor
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom, USA
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41
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Ohki I, Ishigaki T, Oyama T, Matsunaga S, Xie Q, Ohnishi-Kameyama M, Murata T, Tsuchiya D, Machida S, Morikawa K, Tate SI. Crystal Structure of Human Lectin-like, Oxidized Low-Density Lipoprotein Receptor 1 Ligand Binding Domain and Its Ligand Recognition Mode to OxLDL. Structure 2005; 13:905-17. [PMID: 15939022 DOI: 10.1016/j.str.2005.03.016] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 03/27/2005] [Accepted: 03/27/2005] [Indexed: 11/24/2022]
Abstract
Lectin-like, oxidized low-density lipoprotein (LDL) receptor 1, LOX-1, is the major receptor for oxidized LDL (OxLDL) in endothelial cells. We have determined the crystal structure of the ligand binding domain of LOX-1, with a short stalk region connecting the domain to the membrane-spanning region, as a homodimer linked by an interchain disulfide bond. In vivo assays with LOX-1 mutants revealed that the "basic spine," consisting of linearly aligned arginine residues spanning over the dimer surface, is responsible for ligand binding. Single amino acid substitution in the dimer interface caused a severe reduction in LOX-1 binding activity, suggesting that the correct dimer arrangement is crucial for binding to OxLDL. Based on the LDL model structure, possible binding modes of LOX-1 to OxLDL are proposed.
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MESH Headings
- Amino Acid Sequence
- Amino Acid Substitution
- Animals
- Arginine/chemistry
- Binding Sites
- CHO Cells
- Conserved Sequence
- Cricetinae
- Cricetulus
- Crystallography, X-Ray
- Cysteine/chemistry
- Dimerization
- Disulfides/chemistry
- Humans
- Hydrogen Bonding
- Ligands
- Lipoproteins, LDL/chemistry
- Lipoproteins, LDL/metabolism
- Models, Chemical
- Models, Molecular
- Molecular Sequence Data
- Protein Binding
- Protein Folding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Receptors, LDL/chemistry
- Receptors, LDL/genetics
- Receptors, LDL/metabolism
- Receptors, Oxidized LDL
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Scavenger Receptors, Class E
- Sequence Homology, Amino Acid
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Affiliation(s)
- Izuru Ohki
- Department of Structural Biology, Biomolecular Engineering Research Institute 6-2-3, Furuedai, Suita, Osaka, 565-0874, Japan
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Park H, Adsit FG, Boyington JC. The 1.4 angstrom crystal structure of the human oxidized low density lipoprotein receptor lox-1. J Biol Chem 2005; 280:13593-9. [PMID: 15695803 DOI: 10.1074/jbc.m500768200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The lectin-like oxidized low density lipoprotein receptor-1 (Lox-1) mediates the recognition and internalization of oxidatively modified low density lipoprotein by vascular endothelial cells. This interaction results in a number of pro-atherogenic cellular responses that probably play a significant role in the pathology of atherosclerosis. The 1.4 angstrom crystal structure of the extracellular C-type lectin-like domain of human Lox-1 reveals a heart-shaped homodimer with a ridge of six basic amino acids extending diagonally across the apolar top of Lox-1, a central hydrophobic tunnel that extends through the entire molecule, and an electrostatically neutral patch of 12 charged residues that resides next to the tunnel at each opening. Based on the arrangement of critical binding residues on the Lox-1 structure, we propose a binding mode for the recognition of modified low density lipoprotein and other Lox-1 ligands.
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Affiliation(s)
- HaJeung Park
- Biomolecular Crystallography Group, Laboratory of Structural Biology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA
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43
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Greaves DR, Gordon S. Thematic review series: the immune system and atherogenesis. Recent insights into the biology of macrophage scavenger receptors. J Lipid Res 2004; 46:11-20. [PMID: 15548472 DOI: 10.1194/jlr.r400011-jlr200] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Scavenger receptors were originally defined by their ability to bind and internalize modified lipoproteins. Macrophages express at least six structurally different cell surface receptors for modified forms of LDL that contribute to foam cell formation in atherosclerosis. In addition to their role in the pathology of atherosclerosis, macrophage scavenger receptors, especially SR-A, play critical roles in innate immunity, apoptotic cell clearance, and tissue homeostasis. In this review, we highlight recent advances in understanding the biology of macrophage scavenger receptors as pattern recognition receptors for both infectious nonself (pathogens) and modified self (apoptotic cells and modified LDL). We critically evaluate the potential of scavenger receptors and their ligands as targets for therapeutic intervention in human disease.
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Affiliation(s)
- David R Greaves
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom.
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