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Casiano Matos J, Harichandran K, Tang J, Sviridov DO, Sidoti Migliore G, Suzuki M, Olano LR, Hobbs A, Kumar A, Paskel MU, Bonsignori M, Dearborn AD, Remaley AT, Marcotrigiano J. Hepatitis C virus E1 recruits high-density lipoprotein to support infectivity and evade antibody recognition. J Virol 2024; 98:e0084923. [PMID: 38174935 PMCID: PMC10804985 DOI: 10.1128/jvi.00849-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 11/28/2023] [Indexed: 01/05/2024] Open
Abstract
Hepatitis C virus (HCV) is a member of the Flaviviridae family; however, unlike other family members, the HCV virion has an unusually high lipid content. HCV has two envelope glycoproteins, E1 and E2. E2 contributes to receptor binding, cell membrane attachment, and immune evasion. In contrast, the functions of E1 are poorly characterized due, in part, to challenges in producing the protein. This manuscript describes the expression and purification of a soluble E1 ectodomain (eE1) that is recognized by conformational, human monoclonal antibodies. eE1 forms a complex with apolipoproteins AI and AII, cholesterol, and phospholipids by recruiting high-density lipoprotein (HDL) from the extracellular media. We show that HDL binding is a function specific to eE1 and HDL hinders recognition of E1 by a neutralizing monoclonal antibody. Either low-density lipoprotein or HDL increases the production and infectivity of cell culture-produced HCV, but E1 preferentially selects HDL, influencing both viral life cycle and antibody evasion.IMPORTANCEHepatitis C virus (HCV) infection is a significant burden on human health, but vaccine candidates have yet to provide broad protection against this infection. We have developed a method to produce high quantities of soluble E1 or E2, the viral proteins located on the surface of HCV. HCV has an unusually high lipid content due to the recruitment of apolipoproteins. We found that E1 (and not E2) preferentially recruits host high-density lipoprotein (HDL) extracellularly. This recruitment of HDL by E1 prevents binding of E1 by a neutralizing antibody and furthermore prevents antibody-mediated neutralization of the virus. By comparison, low-density lipoprotein does not protect the virus from antibody-mediated neutralization. Our findings provide mechanistic insight into apolipoprotein recruitment, which may be critical for vaccine development.
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Affiliation(s)
- Jennifer Casiano Matos
- Structural Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Kaneemozhe Harichandran
- Structural Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jingrong Tang
- Lipoprotein Metabolism Laboratory, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Denis O. Sviridov
- Lipoprotein Metabolism Laboratory, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Giacomo Sidoti Migliore
- Translational Immunobiology Unit, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Motoshi Suzuki
- Protein Chemistry Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Lisa R. Olano
- Protein Chemistry Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland, USA
| | - Alvaro Hobbs
- Structural Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Ashish Kumar
- Structural Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Myeisha U. Paskel
- Structural Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Mattia Bonsignori
- Translational Immunobiology Unit, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Altaira D. Dearborn
- Structural Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Alan T. Remaley
- Lipoprotein Metabolism Laboratory, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Joseph Marcotrigiano
- Structural Virology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, USA
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Franczyk B, Gluba-Brzózka A, Ciałkowska-Rysz A, Ławiński J, Rysz J. The Impact of Aerobic Exercise on HDL Quantity and Quality: A Narrative Review. Int J Mol Sci 2023; 24:ijms24054653. [PMID: 36902082 PMCID: PMC10003711 DOI: 10.3390/ijms24054653] [Citation(s) in RCA: 24] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2022] [Revised: 02/17/2023] [Accepted: 02/22/2023] [Indexed: 03/06/2023] Open
Abstract
High-density lipoproteins comprise roughly 25-30% of the circulating proteins involved in the transport of lipids in circulation. These particles differ in size and lipid composition. Recent evidence suggests that the quality of HDL particles (which depends on shape, size and the composition of proteins and lipids determining HDL functionality) may be more important than their quantity. The functionality of HDL is mirrored by its cholesterol efflux activity, as well as its antioxidant (including the protection of LDL against oxidation), anti-inflammatory and antithrombotic properties. The results of many studies and meta-analyses imply the beneficial impact of aerobic exercise on HDL-C levels. Physical activity was found to be usually associated with an increase in HDL cholesterol and a decrease in LDL cholesterol and triglycerides. Exercise, apart from inducing quantitative alterations in serum lipids, exerts a beneficial impact on HDL particle maturation, composition and functionality. The Physical Activity Guidelines Advisory Committee Report underlined the importance of establishing a program recommending exercises that enable attainment of maximal advantage at the lowest level of risk. The aim of this manuscript is to review the impact of different types of aerobic exercise (various intensities and durations) on the level and quality of HDL.
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Affiliation(s)
- Beata Franczyk
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, 90-549 Lodz, Poland
| | - Anna Gluba-Brzózka
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, 90-549 Lodz, Poland
- Correspondence: ; Tel.: +48-42-639-3750
| | | | - Janusz Ławiński
- Department of Urology, Institute of Medical Sciences, Medical College of Rzeszow University, 35-055 Rzeszow, Poland
| | - Jacek Rysz
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, 90-549 Lodz, Poland
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Cho KH. The Current Status of Research on High-Density Lipoproteins (HDL): A Paradigm Shift from HDL Quantity to HDL Quality and HDL Functionality. Int J Mol Sci 2022; 23:3967. [PMID: 35409326 PMCID: PMC8999423 DOI: 10.3390/ijms23073967] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 02/06/2023] Open
Abstract
The quantity of high-density lipoproteins (HDL) is represented as the serum HDL-C concentration (mg/dL), while the HDL quality manifests as the diverse features of protein and lipid content, extent of oxidation, and extent of glycation. The HDL functionality represents several performance metrics of HDL, such as antioxidant, anti-inflammatory, and cholesterol efflux activities. The quantity and quality of HDL can change during one's lifetime, depending on infection, disease, and lifestyle, such as dietary habits, exercise, and smoking. The quantity of HDL can change according to age and gender, such as puberty, middle-aged symptoms, climacteric, and the menopause. HDL-C can decrease during disease states, such as acute infection, chronic inflammation, and autoimmune disease, while it can be increased by regular aerobic exercise and healthy food consumption. Generally, high HDL-C at the normal level is associated with good HDL quality and functionality. Nevertheless, high HDL quantity is not always accompanied by good HDL quality or functionality. The HDL quality concerns the morphology of the HDL, such as particle size, shape, and number. The HDL quality also depends on the composition of the HDL, such as apolipoproteins (apoA-I, apoA-II, apoC-III, serum amyloid A, and α-synuclein), cholesterol, and triglyceride. The HDL quality is also associated with the extent of HDL modification, such as glycation and oxidation, resulting in the multimerization of apoA-I, and the aggregation leads to amyloidogenesis. The HDL quality frequently determines the HDL functionality, which depends on the attached antioxidant enzyme activity, such as the paraoxonase and cholesterol efflux activity. Conventional HDL functionality is regression, the removal of cholesterol from atherosclerotic lesions, and the removal of oxidized species in low-density lipoproteins (LDL). Recently, HDL functionality was reported to expand the removal of β-amyloid plaque and inhibit α-synuclein aggregation in the brain to attenuate Alzheimer's disease and Parkinson's disease, respectively. More recently, HDL functionality has been associated with the susceptibility and recovery ability of coronavirus disease 2019 (COVID-19) by inhibiting the activity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The appearance of dysfunctional HDL is frequently associated with many acute infectious diseases and chronic aging-related diseases. An HDL can be a suitable biomarker to diagnose many diseases and their progression by monitoring the changes in its quantity and quality in terms of the antioxidant and anti-inflammatory abilities. An HDL can be a protein drug used for the removal of plaque and as a delivery vehicle for non-soluble drugs and genes. A dysfunctional HDL has poor HDL quality, such as a lower apoA-I content, lower antioxidant ability, smaller size, and ambiguous shape. The current review analyzes the recent advances in HDL quantity, quality, and functionality, depending on the health and disease state during one's lifetime.
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Affiliation(s)
- Kyung-Hyun Cho
- LipoLab, Yeungnam University, Gyeongsan 38541, Korea; ; Tel.: +82-53-964-1990; Fax: +82-53-965-1992
- Raydel Research Institute, Medical Innovation Complex, Daegu 41061, Korea
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4
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Powers HR, Sahoo D. SR-B1's Next Top Model: Structural Perspectives on the Functions of the HDL Receptor. Curr Atheroscler Rep 2022; 24:277-288. [PMID: 35107765 PMCID: PMC8809234 DOI: 10.1007/s11883-022-01001-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/23/2021] [Indexed: 02/04/2023]
Abstract
PURPOSE OF REVIEW The binding of high-density lipoprotein (HDL) to its primary receptor, scavenger receptor class B type 1 (SR-B1), is critical for lowering plasma cholesterol levels and reducing cardiovascular disease risk. This review provides novel insights into how the structural elements of SR-B1 drive efficient function with an emphasis on bidirectional cholesterol transport. RECENT FINDINGS We have generated a new homology model of full-length human SR-B1 based on the recent resolution of the partial structures of other class B scavenger receptors. Interrogating this model against previously published observations allows us to generate structurally informed hypotheses about SR-B1's ability to mediate HDL-cholesterol (HDL-C) transport. Furthermore, we provide a structural perspective as to why human variants of SR-B1 may result in impaired HDL-C clearance. A comprehensive understanding of SR-B1's structure-function relationships is critical to the development of therapeutic agents targeting SR-B1 and modulating cardiovascular disease risk.
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Affiliation(s)
- Hayley R. Powers
- grid.30760.320000 0001 2111 8460Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI USA
| | - Daisy Sahoo
- grid.30760.320000 0001 2111 8460Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI USA ,grid.30760.320000 0001 2111 8460Department of Medicine, Division of Endocrinology & Molecular Medicine, Medical College of Wisconsin, Milwaukee, WI USA ,grid.30760.320000 0001 2111 8460Cardiovascular Center, H4930 Health Research Center, Medical College of Wisconsin, 8701 W. Watertown Plank Road, Milwaukee, WI 53226 USA
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5
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Cho KH. Importance of Apolipoprotein A-I and A-II Composition in HDL and Its Potential for Studying COVID-19 and SARS-CoV-2. MEDICINES (BASEL, SWITZERLAND) 2021; 8:medicines8070038. [PMID: 34357154 PMCID: PMC8307872 DOI: 10.3390/medicines8070038] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Revised: 06/30/2021] [Accepted: 07/15/2021] [Indexed: 05/12/2023]
Abstract
The composition and properties of apolipoprotein (apo) A-I and apoA-II in high-density lipoproteins (HDL) might be critical to SARS-CoV-2 infection via SR-BI and antiviral activity against COVID-19. HDL containing native apoA-I showed potent antiviral activity, while HDL containing glycated apoA-I or other apolipoproteins did not. However, there has been no report to elucidate the putative role of apoA-II in the antiviral activity of HDL.
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Affiliation(s)
- Kyung-Hyun Cho
- Medical Innovation Complex, Korea Research Institute of Lipoproteins, Daegu 41061, Korea; ; Tel.: +82-53-964-1990; Fax: +82-53-965-1992
- LipoLab, Yeungnam University, Gyeongsan 712-749, Korea
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6
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Pedrini S, Chatterjee P, Hone E, Martins RN. High‐density lipoprotein‐related cholesterol metabolism in Alzheimer’s disease. J Neurochem 2020; 159:343-377. [DOI: 10.1111/jnc.15170] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Steve Pedrini
- Sarich Neurosciences Research InstituteEdith Cowan University Nedlands WA Australia
| | - Pratishtha Chatterjee
- Sarich Neurosciences Research InstituteEdith Cowan University Nedlands WA Australia
- Department of Biomedical Sciences Faculty of Medicine, Health and Human Sciences Macquarie University Sydney NSW Australia
| | - Eugene Hone
- Sarich Neurosciences Research InstituteEdith Cowan University Nedlands WA Australia
| | - Ralph N. Martins
- Sarich Neurosciences Research InstituteEdith Cowan University Nedlands WA Australia
- Department of Biomedical Sciences Faculty of Medicine, Health and Human Sciences Macquarie University Sydney NSW Australia
- School of Psychiatry and Clinical Neurosciences University of Western Australia Nedlands WA Australia
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7
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Ji A, Wang X, Noffsinger VP, Jennings D, de Beer MC, de Beer FC, Tannock LR, Webb NR. Serum amyloid A is not incorporated into HDL during HDL biogenesis. J Lipid Res 2020; 61:328-337. [PMID: 31915139 DOI: 10.1194/jlr.ra119000329] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 01/06/2020] [Indexed: 11/20/2022] Open
Abstract
Liver-derived serum amyloid A (SAA) is present in plasma where it is mainly associated with HDL and from which it is cleared more rapidly than are the other major HDL-associated apolipoproteins. Although evidence suggests that lipid-free and HDL-associated forms of SAA have different activities, the pathways by which SAA associates and disassociates with HDL are poorly understood. In this study, we investigated SAA lipidation by hepatocytes and how this lipidation relates to the formation of nascent HDL particles. We also examined hepatocyte-mediated clearance of lipid-free and HDL-associated SAA. We prepared hepatocytes from mice injected with lipopolysaccharide or an SAA-expressing adenoviral vector. Alternatively, we incubated primary hepatocytes from SAA-deficient mice with purified SAA. We analyzed conditioned media to determine the lipidation status of endogenously produced and exogenously added SAA. Examining the migration of lipidated species, we found that SAA is lipidated and forms nascent particles that are distinct from apoA-I-containing particles and that apoA-I lipidation is unaltered when SAA is overexpressed or added to the cells, indicating that SAA is not incorporated into apoA-I-containing HDL during HDL biogenesis. Like apoA-I formation, generation of SAA-containing particles was dependent on ABCA1, but not on scavenger receptor class B type I. Hepatocytes degraded significantly more SAA than apoA-I. Taken together, our results indicate that SAA's lipidation and metabolism by the liver is independent of apoA-I and that SAA is not incorporated into HDL during HDL biogenesis.
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Affiliation(s)
- Ailing Ji
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
| | - Xuebing Wang
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY
| | | | - Drew Jennings
- Departments of Agricultural and Medical Biotechnology, University of Kentucky, Lexington, KY
| | - Maria C de Beer
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Physiology, University of Kentucky, Lexington, KY
| | - Frederick C de Beer
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Internal Medicine, University of Kentucky, Lexington, KY
| | - Lisa R Tannock
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY.,Internal Medicine, University of Kentucky, Lexington, KY
| | - Nancy R Webb
- Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY .,Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY
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8
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Chan KW, Ismail M, Mohd Esa N, Imam MU, Ooi DJ, Khong NMH. Dietary supplementation of defatted kenaf (Hibiscus cannabinus L.) seed meal and its phenolics-saponins rich extract effectively attenuates diet-induced hypercholesterolemia in rats. Food Funct 2018; 9:925-936. [PMID: 29313544 DOI: 10.1039/c7fo01109a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Kenaf is one of the important commercial fiber crops worldwide and defatted kenaf seed meal (DKSM) is a secondary by-product from the kenaf industry. Thus, efforts to turn this low-cost agricultural waste into value-added functional food ingredients will definitely bring advantageous impacts to the community health, environment and economy. The present study was aimed to investigate the cardioprotective properties of DKSM and its phenolics-saponins rich extract (PSRE) in diet-induced hypercholesterolemic rat model. Hypercholesterolemia was induced in Sprague-Dawley rats via atherogenic diet feeding and dietary interventions were conducted by incorporating DKSM (15% and 30%) and equivalent levels of PSRE (2.3% and 4.6%, respectively, equivalent to the total content of phenolics and saponins in DKSM groups) into the atherogenic diets. After 10 weeks of DKSM and PSRE supplementation, the hepatosomatic index, hepatosteatosis, serum lipid profile, Castelli risk indexes as well as hepatic and renal functions of hypercholesterolemic rats were significantly improved (p < 0.05). Besides, the levels of hepatic Hmgcr and serum Pcsk9 were lowered, along with transcriptional upregulations of hepatic Cyp7a1, Abca1, Lcat, ApoA2 and ApoE (p < 0.05). The gene expression of hepatic Ldlr was marginally enhanced by DKSM supplementation (p > 0.05), but superiorly upregulated by PSRE (p < 0.05). The combined results showed that hypercholesterolemia and the atherogenic risk in rats were effectively attenuated by DKSM and PSRE supplementation, possibly via modulations of multiple vital processes in hepatic cholesterol metabolism. Furthermore, phenolics and saponins may be the bioactives conferring DKSM and PSRE with their anti-hypercholesterolemic properties. In conclusion, DKSM and PSRE are prospective cardioprotective functional food ingredients for hypercholesterolemic individuals.
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Affiliation(s)
- Kim Wei Chan
- Institute of Bioscience, Universiti Putra Malaysia, 43400 Serdang, Selangor, Malaysia.
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9
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Shen WJ, Asthana S, Kraemer FB, Azhar S. Scavenger receptor B type 1: expression, molecular regulation, and cholesterol transport function. J Lipid Res 2018; 59:1114-1131. [PMID: 29720388 DOI: 10.1194/jlr.r083121] [Citation(s) in RCA: 83] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 04/26/2018] [Indexed: 12/16/2022] Open
Abstract
Cholesterol is required for maintenance of plasma membrane fluidity and integrity and for many cellular functions. Cellular cholesterol can be obtained from lipoproteins in a selective pathway of HDL-cholesteryl ester (CE) uptake without parallel apolipoprotein uptake. Scavenger receptor B type 1 (SR-B1) is a cell surface HDL receptor that mediates HDL-CE uptake. It is most abundantly expressed in liver, where it provides cholesterol for bile acid synthesis, and in steroidogenic tissues, where it delivers cholesterol needed for storage or steroidogenesis in rodents. SR-B1 transcription is regulated by trophic hormones in the adrenal gland, ovary, and testis; in the liver and elsewhere, SR-B1 is subject to posttranscriptional and posttranslational regulation. SR-B1 operates in several metabolic processes and contributes to pathogenesis of atherosclerosis, inflammation, hepatitis C virus infection, and other conditions. Here, we summarize characteristics of the selective uptake pathway and involvement of microvillar channels as facilitators of selective HDL-CE uptake. We also present the potential mechanisms of SR-B1-mediated selective cholesterol transport; the transcriptional, posttranscriptional, and posttranslational regulation of SR-B1; and the impact of gene variants on expression and function of human SR-B1. A better understanding of this unique pathway and SR-B1's role may yield improved therapies for a wide variety of conditions.
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Affiliation(s)
- Wen-Jun Shen
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
| | - Shailendra Asthana
- Drug Discovery Research Center (DDRC), Translational Health Science and Technology Institute (THSTI), NCR Biotech Science Cluster, Faridabad 121001, Haryana, India
| | - Fredric B Kraemer
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
| | - Salman Azhar
- Geriatric Research, Education, and Clinical Research Center (GRECC), Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304 and Division of Endocrinology, Gerontology, and Metabolism, Stanford University School of Medicine, Stanford, CA 94305
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10
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Melchior JT, Street SE, Andraski AB, Furtado JD, Sacks FM, Shute RL, Greve EI, Swertfeger DK, Li H, Shah AS, Lu LJ, Davidson WS. Apolipoprotein A-II alters the proteome of human lipoproteins and enhances cholesterol efflux from ABCA1. J Lipid Res 2017; 58:1374-1385. [PMID: 28476857 DOI: 10.1194/jlr.m075382] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/25/2017] [Indexed: 12/25/2022] Open
Abstract
HDLs are a family of heterogeneous particles that vary in size, composition, and function. The structure of most HDLs is maintained by two scaffold proteins, apoA-I and apoA-II, but up to 95 other "accessory" proteins have been found associated with the particles. Recent evidence suggests that these accessory proteins are distributed across various subspecies and drive specific biological functions. Unfortunately, our understanding of the molecular composition of such subspecies is limited. To begin to address this issue, we separated human plasma and HDL isolated by ultracentrifugation (UC-HDL) into particles with apoA-I and no apoA-II (LpA-I) and those with both apoA-I and apoA-II (LpA-I/A-II). MS studies revealed distinct differences between the subfractions. LpA-I exhibited significantly more protein diversity than LpA-I/A-II when isolated directly from plasma. However, this difference was lost in UC-HDL. Most LpA-I/A-II accessory proteins were associated with lipid transport pathways, whereas those in LpA-I were associated with inflammatory response, hemostasis, immune response, metal ion binding, and protease inhibition. We found that the presence of apoA-II enhanced ABCA1-mediated efflux compared with LpA-I particles. This effect was independent of the accessory protein signature suggesting that apoA-II induces a structural change in apoA-I in HDLs.
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Affiliation(s)
- John T Melchior
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Scott E Street
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Allison B Andraski
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Jeremy D Furtado
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Frank M Sacks
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115; Department of Genetics & Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Rebecca L Shute
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Emily I Greve
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Debi K Swertfeger
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Hailong Li
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Amy S Shah
- Division of Endocrinology, Department of Pediatrics, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - L Jason Lu
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237.
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11
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Apolipoprotein A-II Plus Lipid Emulsion Enhance Cell Growth via SR-B1 and Target Pancreatic Cancer In Vitro and In Vivo. PLoS One 2016; 11:e0151475. [PMID: 27002321 PMCID: PMC4803224 DOI: 10.1371/journal.pone.0151475] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 02/29/2016] [Indexed: 12/18/2022] Open
Abstract
Background Apolipoprotein A-II (ApoA-II) is down regulated in the sera of pancreatic ductal adenocarcinoma (PDAC) patients, which may be due to increase utilization of high density lipoprotein (HDL) lipid by pancreatic cancer tissue. This study examined the influence of exogenous ApoA-II on lipid uptake and cell growth in pancreatic cancer (PC) both in vitro and in vivo. Methods Cryo transmission electron microscopy (TEM) examined ApoA-II’s influence on morphology of SMOFLipid emulsion. The influence of ApoA-II on proliferation of cancer cell lines was determined by incubating them with lipid+/-ApoA-II and anti-SR-B1 antibody. Lipid was labeled with the fluorophore, DiD, to trace lipid uptake by cancer cells in vitro by confocal microscopy and in vivo in PDAC patient derived xenograft tumours (PDXT) by fluorescence imaging. Scavenger receptor class B type-1(SR-B1) expression in PDAC cell lines and in PDAC PDXT was measured by western blotting and immunohistochemistry, respectively. Results ApoA-II spontaneously converted lipid emulsion into very small unilamellar rHDL like vesicles (rHDL/A-II) and enhanced lipid uptake in PANC-1, CFPAC-1 and primary tumour cells as shown by confocal microscopy. SR-B1 expression was 13.2, 10.6, 3.1 and 2.3 fold higher in PANC-1, MIAPaCa-2, CFPAC-1 and BxPC3 cell lines than the normal pancreatic cell line (HPDE6) and 3.7 fold greater in PDAC tissue than in normal pancreas. ApoA-II plus lipid significantly increased the uptake of labeled lipid and promoted cell growth in PANC-1, MIAPaCa-2, CFPAC-1 and BxPC3 cells which was inhibited by anti SR-B1 antibody. Further, ApoA-II increased the uptake of lipid in xenografts by 3.4 fold. Conclusion Our data suggest that ApoA-II enhance targeting potential of lipid in pancreatic cancer which may have imaging and drug delivery potentialities.
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12
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Mutharasan RK, Foit L, Thaxton CS. High-Density Lipoproteins for Therapeutic Delivery Systems. J Mater Chem B 2016; 4:188-197. [PMID: 27069624 PMCID: PMC4825811 DOI: 10.1039/c5tb01332a] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
High-density lipoproteins (HDL) are a class of natural nanostructures found in the blood and are composed of lipids, proteins, and nucleic acids (e.g. microRNA). Their size, which appears to be well-suited for both tissue penetration/retention as well as payload delivery, long circulation half-life, avoidance of endosomal sequestration, and potential low toxicity are all excellent properties to model in a drug delivery vehicle. In this review, we consider high-density lipoproteins for therapeutic delivery systems. First we discuss the structure and function of natural HDL, describing in detail its biogenesis and transformation from immature, discoidal forms, to more mature, spherical forms. Next we consider features of HDL making them suitable vehicles for drug delivery. We then describe the use of natural HDL, discoidal HDL analogs, and spherical HDL analogs to deliver various classes of drugs, including small molecules, lipids, and oligonucleotides. We briefly consider the notion that the drug delivery vehicles themselves are therapeutic, constituting entities that exhibit "theralivery." Finally, we discuss challenges and future directions in the field.
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Affiliation(s)
- R. Kannan Mutharasan
- Feinberg Cardiovascular Research Institute, 303 E. Chicago Ave., Tarry 14-725, Chicago, IL 60611 United States
| | - Linda Foit
- Feinberg School of Medicine, Department of Urology, Northwestern University, Tarry 16-703, 303 E. Chicago Ave, Chicago, IL 60611, USA
| | - C. Shad Thaxton
- Feinberg School of Medicine, Department of Urology, Northwestern University, Tarry 16-703, 303 E. Chicago Ave, Chicago, IL 60611, USA
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, 303 E. Superior St, Chicago, IL 60611, USA
- International Institute for Nanotechnology (IIN), 2145 Sheridan Road, Evanston, IL 60208, USA
- Robert H Lurie Comprehensive Cancer Center (RHLCCC), Northwestern University, Feinberg School of Medicine, 303 E Superior, Chicago, IL 60611, USA
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Gomaraschi M, Ossoli A, Adorni MP, Damonte E, Niesor E, Veglia F, Franceschini G, Benghozi R, Calabresi L. Fenofibrate and extended-release niacin improve the endothelial protective effects of HDL in patients with metabolic syndrome. Vascul Pharmacol 2015; 74:80-86. [DOI: 10.1016/j.vph.2015.06.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 05/19/2015] [Accepted: 06/27/2015] [Indexed: 12/29/2022]
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14
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Gomaraschi M, Ossoli A, Pozzi S, Nilsson P, Cefalù AB, Averna M, Kuivenhoven JA, Hovingh GK, Veglia F, Franceschini G, Calabresi L. eNOS activation by HDL is impaired in genetic CETP deficiency. PLoS One 2014; 9:e95925. [PMID: 24830642 PMCID: PMC4022511 DOI: 10.1371/journal.pone.0095925] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2014] [Accepted: 04/01/2014] [Indexed: 01/09/2023] Open
Abstract
Mutations in the CETP gene resulting in defective CETP activity have been shown to cause remarkable elevations of plasma HDL-C levels, with the accumulation in plasma of large, buoyant HDL particles enriched in apolipoprotein E. Genetic CETP deficiency thus represents a unique tool to evaluate how structural alterations of HDL impact on HDL atheroprotective functions. Aim of the present study was to assess the ability of HDL obtained from CETP-deficient subjects to protect endothelial cells from the development of endothelial dysfunction. HDL isolated from one homozygous and seven heterozygous carriers of CETP null mutations were evaluated for their ability to down-regulate cytokine-induced cell adhesion molecule expression and to promote NO production in cultured endothelial cells. When compared at the same protein concentration, HDL and HDL3 from carriers proved to be as effective as control HDL and HDL3 in down-regulating cytokine-induced VCAM-1, while carrier HDL2 were more effective than control HDL2 in inhibiting VCAM-1 expression. On the other hand, HDL and HDL fractions from carriers of CETP deficiency were significantly less effective than control HDL and HDL fractions in stimulating NO production, due to a reduced eNOS activating capacity, likely because of a reduced S1P content. In conclusion, the present findings support the notion that genetic CETP deficiency, by affecting HDL particle structure, impacts on HDL vasculoprotective functions. Understanding of these effects might be important for predicting the outcomes of pharmacological CETP inhibition.
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Affiliation(s)
- Monica Gomaraschi
- Center E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Alice Ossoli
- Center E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Silvia Pozzi
- Center E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Peter Nilsson
- Department of Clinical Sciences, University Hospital, Malmö, Sweden
| | - Angelo B. Cefalù
- Department of Internal Medicine and Medical Specialties, Policlinico “Paolo Giaccone”, University of Palermo, Palermo, Italy
| | - Maurizio Averna
- Department of Internal Medicine and Medical Specialties, Policlinico “Paolo Giaccone”, University of Palermo, Palermo, Italy
| | | | - G. Kees Hovingh
- Department of Vascular Medicine, Academic Medical Center, Amsterdam, The Netherlands
| | | | - Guido Franceschini
- Center E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Laura Calabresi
- Center E. Grossi Paoletti, Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
- * E-mail:
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15
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Wang Y, Niimi M, Nishijima K, Waqar AB, Yu Y, Koike T, Kitajima S, Liu E, Inoue T, Kohashi M, Keyamura Y, Yoshikawa T, Zhang J, Ma L, Zha X, Watanabe T, Asada Y, Chen YE, Fan J. Human apolipoprotein A-II protects against diet-induced atherosclerosis in transgenic rabbits. Arterioscler Thromb Vasc Biol 2012; 33:224-31. [PMID: 23241412 DOI: 10.1161/atvbaha.112.300445] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Apolipoprotein (apo) A-II is the second major apo of high-density lipoproteins, yet its pathophysiological roles in the development of atherosclerosis remain unknown. We aimed to examine whether apo A-II plays any role in atherogenesis and, if so, to elucidate the mechanism involved. METHODS AND RESULTS We compared the susceptibility of human apo A-II transgenic (Tg) rabbits to cholesterol diet-induced atherosclerosis with non-Tg littermate rabbits. Tg rabbits developed significantly less aortic and coronary atherosclerosis than their non-Tg littermates, while total plasma cholesterol levels were similar. Atherosclerotic lesions of Tg rabbits were characterized by reduced macrophages and smooth muscle cells, and apo A-II immunoreactive proteins were frequently detected in the lesions. Tg rabbits exhibited low levels of plasma C-reactive protein and blood leukocytes compared with non-Tg rabbits, and high-density lipoproteins of Tg rabbit plasma exerted stronger cholesterol efflux activity and inhibitory effects on the inflammatory cytokine expression by macrophages in vitro than high-density lipoproteins isolated from non-Tg rabbits. In addition, β-very-low-density lipoproteins of Tg rabbits were less sensitive to copper-induced oxidation than β-very-low-density lipoproteins of non-Tg rabbits. CONCLUSIONS These results suggest that enrichment of apo A-II in high-density lipoprotein particles has atheroprotective effects and apo A-II may become a target for the treatment of atherosclerosis.
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Affiliation(s)
- Yao Wang
- Department of Molecular Pathology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Shimokato, Chuo-City, Yamanashi, Japan
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16
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Abstract
HDL is known to be inversely correlated with cardiovascular disease due to its diverse antiatherogenic functions. These functions include cholesterol efflux and reverse cholesterol transport, antioxidative and anti-inflammatory activities. However, HDL has been shown to undergo a loss of function in several pathophysiological states, as in the acute phase response, obesity and chronic inflammatory diseases. Some of these diseases were also shown to be associated with increased risk for cardiovascular disease. One such disease that is associated with HDL dysfunction and accelerated atherosclerosis is diabetes mellitus, a disease in which the HDL particle undergoes diverse structural modifications that result in significant changes in its function. This review will summarize the changes that occur in HDL in diabetes mellitus and how these changes lead to HDL dysfunction. Possible treatments for HDL dysfunction are also briefly described.
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Affiliation(s)
- Dan Farbstein
- Technion Faculty of Medicine, Technion Israel Institute of Technology, Haifa, Israel.
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17
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Smith LE, Yang J, Goodman L, Huang X, Huang R, Dressman J, Morris J, Silva RAGD, Davidson WS, Cavigiolio G. High yield expression and purification of recombinant human apolipoprotein A-II in Escherichia coli. J Lipid Res 2012; 53:1708-15. [PMID: 22636422 DOI: 10.1194/jlr.d028043] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Recombinant expression systems have become powerful tools for understanding the structure and function of proteins, including the apolipoproteins that comprise human HDL. However, human apolipoprotein (apo)A-II has proven difficult to produce by recombinant techniques, likely contributing to our lack of knowledge about its structure, specific biological function, and role in cardiovascular disease. Here we present a novel Escherichia coli-based recombinant expression system that produces highly pure mature human apoA-II at substantial yields. A Mxe GyrA intein containing a chitin binding domain was fused at the C terminus of apoA-II. A 6× histidine-tag was also added at the fusion protein's C terminus. After rapid purification on a chitin column, intein auto-cleavage was induced under reducing conditions, releasing a peptide with only one extra N-terminal Met compared with the sequence of human mature apoA-II. A pass through a nickel chelating column removed any histidine-tagged residual fusion protein, leaving highly pure apoA-II. A variety of electrophoretic, mass spectrometric, and spectrophotometric analyses demonstrated that the recombinant form is comparable in structure to human plasma apoA-II. Similarly, recombinant apoA-II is comparable to the plasma form in its ability to bind and reorganize lipid and promote cholesterol efflux from macrophages via the ATP binding cassette transporter A1. This system is ideal for producing large quantities of recombinant wild-type or mutant apoA-II for structural or functional studies.
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Affiliation(s)
- Loren E Smith
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45273, USA
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18
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Al-Zoairy R, Melmer A, Ress C, Laimer M, Kaser S, Ebenbichler C. Lipid profile changes after pronounced weight loss induced by bariatric surgery. ACTA ACUST UNITED AC 2012. [DOI: 10.2217/clp.12.9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Yi DW, Jeong DW, Lee SY, Son SM, Kang YH. The Association between Apolipoprotein A-II and Metabolic Syndrome in Korean Adults: A Comparison Study of Apolipoprotein A-I and Apolipoprotein B. Diabetes Metab J 2012; 36:56-63. [PMID: 22363922 PMCID: PMC3283827 DOI: 10.4093/dmj.2012.36.1.56] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 08/25/2011] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Apolipoprotein A-II (apoA-II) is the second-most abundant apolipoprotein in human high-density lipoprotein and its role in cardio metabolic risk is not entirely clear. It has been suggested to have poor anti-atherogenic or even pro-atherogenic properties, but there are few studies on the possible role of apoA-II in Asian populations. The aim of this study is to evaluate the role of apoA-II in metabolic syndrome (MetS) compared with apolipoprotein A-I (apoA-I) and apolipoprotein B (apoB) in Korean adults. METHODS We analyzed data from 244 adults who visited the Center for Health Promotion in Pusan National University Yangsan Hospital for routine health examinations. RESULTS The mean apoB level was significantly higher, and the mean apoA-I level was significantly lower, in MetS; however, there was no significant difference in apoA-II levels (30.5±4.6 mg/dL vs. 31.2±4.6 mg/dL, P=0.261). ApoA-II levels were more positively correlated with apoA-I levels than apoB levels. ApoA-II levels were less negatively correlated with homocysteine and high sensitivity C-reactive protein levels than apoA-I levels. The differences in MetS prevalence from the lowest to highest quartile of apoA-II were not significant (9.0%, 5.7%, 4.9%, and 6.6%, P=0.279). The relative risk of the highest quartile of apoA-II compared with the lowest quartile also was not significantly different (odds ratio, 0.96; 95% confidence interval, 0.95 to 1.04; P=0.956). CONCLUSION Compared with apoA-I (negative association with MetS) and apoB (positive association with MetS) levels, apoA-II levels did not show any association with MetS in this study involving Korean adults. However, apoA-II may have both anti-atherogenic and pro-atherogenic properties.
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Affiliation(s)
- Dong Won Yi
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Dong Wook Jeong
- Department of Family Medicine, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Sang Yeoup Lee
- Department of Family Medicine, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Seok Man Son
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea
| | - Yang Ho Kang
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Pusan National University Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea
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20
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Gauthamadasa K, Vaitinadin NS, Dressman JL, Macha S, Homan R, Greis KD, Silva RAGD. Apolipoprotein A-II-mediated conformational changes of apolipoprotein A-I in discoidal high density lipoproteins. J Biol Chem 2012; 287:7615-25. [PMID: 22235130 DOI: 10.1074/jbc.m111.291070] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
It is well accepted that HDL has the ability to reduce risks for several chronic diseases. To gain insights into the functional properties of HDL, it is critical to understand the HDL structure in detail. To understand interactions between the two major apolipoproteins (apos), apoA-I and apoA-II in HDL, we generated highly defined benchmark discoidal HDL particles. These particles were reconstituted using a physiologically relevant phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) incorporating two molecules of apoA-I and one homodimer of apoA-II per particle. We utilized two independent mass spectrometry techniques to study these particles. The techniques are both sensitive to protein conformation and interactions and are namely: 1) hydrogen deuterium exchange combined with mass spectrometry and 2) partial acetylation of lysine residues combined with MS. Comparison of mixed particles with apoA-I only particles of similar diameter revealed that the changes in apoA-I conformation in the presence of apoA-II are confined to apoA-I helices 3-4 and 7-9. We discuss these findings with respect to the relative reactivity of these two particle types toward a major plasma enzyme, lecithin:cholesterol acyltransferase responsible for the HDL maturation process.
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Affiliation(s)
- Kekulawalage Gauthamadasa
- Department of Pathology and Laboratory Medicine, Center for Lipids and Atherosclerosis Sciences, University of Cincinnati, Cincinnati, Ohio 45267, USA
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21
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Ji A, Wroblewski JM, Cai L, de Beer MC, Webb NR, van der Westhuyzen DR. Nascent HDL formation in hepatocytes and role of ABCA1, ABCG1, and SR-BI. J Lipid Res 2011; 53:446-455. [PMID: 22190590 DOI: 10.1194/jlr.m017079] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
To study the mechanisms of hepatic HDL formation, we investigated the roles of ABCA1, ABCG1, and SR-BI in nascent HDL formation in primary hepatocytes isolated from mice deficient in ABCA1, ABCG1, or SR-BI and from wild-type (WT) mice. Under basal conditions, in WT hepatocytes, cholesterol efflux to exogenous apoA-I was accompanied by conversion of apoA-I to HDL-sized particles. LXR activation by T0901317 markedly enhanced the formation of larger HDL-sized particles as well as cellular cholesterol efflux to apoA-I. Glyburide treatment completely abolished the formation of 7.4 nm diameter and greater particles but led to the formation of novel 7.2 nm-sized particles. However, cells lacking ABCA1 failed to form such particles. ABCG1-deficient cells showed similar capacity to efflux cholesterol to apoA-I and to form nascent HDL particles compared with WT cells. Cholesterol efflux to apoA-I and nascent HDL formation were slightly but significantly enhanced in SR-BI-deficient cells compared with WT cells under basal but not LXR activated conditions. As in WT but not in ABCA1-deficient hepatocytes, 7.2 nm-sized particles generated by glyburide treatment were also detected in ABCG1-deficient and SR-BI-deficient hepatocytes. Our data indicate that hepatic nascent HDL formation is highly dependent on ABCA1 but not on ABCG1 or SR-BI.
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Affiliation(s)
- Ailing Ji
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Joanne M Wroblewski
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Lei Cai
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Maria C de Beer
- Physiology, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Nancy R Webb
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY
| | - Deneys R van der Westhuyzen
- Departments of Internal Medicine, University of Kentucky, Lexington, KY; Cardiovascular Research Center, University of Kentucky, Lexington, KY; Graduate Center for Nutritional Sciences, University of Kentucky, Lexington, KY; Molecular and Cellular Biochemistry and Physiology, University of Kentucky, Lexington, KY; Department of Veterans Affairs Medical Center, Lexington, KY.
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22
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Rye KA, Barter PJ. Predictive value of different HDL particles for the protection against or risk of coronary heart disease. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:473-80. [PMID: 22051746 DOI: 10.1016/j.bbalip.2011.10.012] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 10/10/2011] [Accepted: 10/13/2011] [Indexed: 12/26/2022]
Abstract
The inverse relationship between plasma HDL levels and the risk of developing coronary heart disease is well established. The underlying mechanisms of this relationship are poorly understood, largely because HDL consist of several functionally distinct subpopulations of particles that are continuously being interconverted from one to another. This review commences with an outline of what is known about the origins of individual HDL subpopulations, how their distribution is regulated, and describes strategies that are currently available for isolating them. We then summarise what is known about the functionality of specific HDL subpopulations, and how these findings might impact on cardiovascular risk. The final section highlights major gaps in existing knowledge of HDL functionality, and suggests how these deficiencies might be addressed. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Kerry-Anne Rye
- Lipid Research Group, The Heart Research Institute, Sydney, NSW, Australia.
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23
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Valacchi G, Sticozzi C, Lim Y, Pecorelli A. Scavenger receptor class B type I: a multifunctional receptor. Ann N Y Acad Sci 2011; 1229:E1-7. [DOI: 10.1111/j.1749-6632.2011.06205.x] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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24
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Rosenson RS, Brewer HB, Chapman MJ, Fazio S, Hussain MM, Kontush A, Krauss RM, Otvos JD, Remaley AT, Schaefer EJ. HDL Measures, Particle Heterogeneity, Proposed Nomenclature, and Relation to Atherosclerotic Cardiovascular Events. Clin Chem 2011; 57:392-410. [DOI: 10.1373/clinchem.2010.155333] [Citation(s) in RCA: 356] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
BACKGROUND
A growing body of evidence from epidemiological data, animal studies, and clinical trials supports HDL as the next target to reduce residual cardiovascular risk in statin-treated, high-risk patients. For more than 3 decades, HDL cholesterol has been employed as the principal clinical measure of HDL and cardiovascular risk associated with low HDL-cholesterol concentrations. The physicochemical and functional heterogeneity of HDL present important challenges to investigators in the cardiovascular field who are seeking to identify more effective laboratory and clinical methods to develop a measurement method to quantify HDL that has predictive value in assessing cardiovascular risk.
CONTENT
In this report, we critically evaluate the diverse physical and chemical methods that have been employed to characterize plasma HDL. To facilitate future characterization of HDL subfractions, we propose the development of a new nomenclature based on physical properties for the subfractions of HDL that includes very large HDL particles (VL-HDL), large HDL particles (L-HDL), medium HDL particles (M-HDL), small HDL particles (S-HDL), and very-small HDL particles (VS-HDL). This nomenclature also includes an entry for the pre-β-1 HDL subclass that participates in macrophage cholesterol efflux.
SUMMARY
We anticipate that adoption of a uniform nomenclature system for HDL subfractions that integrates terminology from several methods will enhance our ability not only to compare findings with different approaches for HDL fractionation, but also to assess the clinical effects of different agents that modulate HDL particle structure, metabolism, and function, and in turn, cardiovascular risk prediction within these HDL subfractions.
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Affiliation(s)
| | | | - M John Chapman
- INSERM Unit 939, UPMC Paris 6, Hôpital de la Pitié, Paris, France
| | | | | | - Anatol Kontush
- INSERM Unit 939, UPMC Paris 6, Hôpital de la Pitié, Paris, France
| | - Ronald M Krauss
- Children's Hospital Oakland Research Institute, University of California, Berkeley
- University of California, San Francisco, CA
| | | | - Alan T Remaley
- Lipoprotein Metabolism Section, Pulmonary and Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD
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25
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Gauthamadasa K, Rosales C, Pownall HJ, Macha S, Jerome WG, Huang R, Silva RAGD. Speciated human high-density lipoprotein protein proximity profiles. Biochemistry 2010; 49:10656-65. [PMID: 21073165 DOI: 10.1021/bi1015452] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
It is expected that the attendant structural heterogeneity of human high-density lipoprotein (HDL) complexes is a determinant of its varied metabolic functions. To determine the structural heterogeneity of HDL, we determined major apolipoprotein stoichiometry profiles in human HDL. First, HDL was separated into two main populations, with and without apolipoprotein (apo) A-II, LpA-I and LpA-I/A-II, respectively. Each main population was further separated into six individual subfractions using size exclusion chromatography (SEC). Protein proximity profiles (PPPs) of major apolipoproteins in each individual subfraction was determined by optimally cross-linking apolipoproteins within individual particles with bis(sulfosuccinimidyl) suberate (BS(3)), a bifunctional cross-linker, followed by molecular mass determination by MALDI-MS. The PPPs of LpA-I subfractions indicated that the number of apoA-I molecules increased from two to three to four with an increase in the LpA-I particle size. On the other hand, the entire population of LpA-I/A-II demonstrated the presence of only two proximal apoA-I molecules per particle, while the number of apoA-II molecules varied from one dimeric apoA-II to two and then to three. For most of the PPPs described above, an additional population that contained a single molecule of apoC-III in addition to apoA-I and/or apoA-II was detected. Upon composition analyses of individual subpopulations, LpA-I/A-II exhibited comparable proportions for total protein (∼58%), phospholipids (∼21%), total cholesterol (∼16%), triglycerides (∼5%), and free cholesterol (∼4%) across subfractions. LpA-I components, on the other hand, showed significant variability. This novel information about HDL subfractions will form a basis for an improved understanding of particle-specific functions of HDL.
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Affiliation(s)
- Kekulawalage Gauthamadasa
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio 45237, United States
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26
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Abstract
PURPOSE OF REVIEW HDL is a cardioprotective lipoprotein, at least in part, because of its ability to mediate reverse cholesterol transport (RCT). It is becoming increasingly clear that the antiatherogenic effects of HDL are not only dependent on its concentration in circulating blood but also on its biological 'quality'. This review summarizes our current understanding of how the biological activities of individual subclasses of HDL particles contribute to overall HDL performance in RCT. RECENT FINDINGS Recent work indicates that apolipoprotein A-I-containing nascent HDL particles are heterogeneous and that such particles exert different effects on the RCT pathway. RCT from macrophages has been examined in detail in mice and the roles of plasma factors (lecithin-cholesterol acyltransferase, cholesterol ester transfer protein, phospholipid transfer protein) and cell factors (ATP-binding cassette transporter A1, ATP-binding cassette transporter G1, scavenger receptor class B type 1) have been evaluated. Manipulation of such factors has consistent effects on RCT and atherosclerosis, but the level of plasma HDL does not reliably predict the degree of RCT. Furthermore, HDL cholesterol or apolipoprotein A-I levels do not necessarily correlate with the magnitude of cholesterol efflux from macrophages; more understanding of the contributions of specific HDL subspecies is required. SUMMARY The antiatherogenic quality of HDL is defined by the functionality of HDL subspecies. In the case of RCT, the rate of cholesterol movement through the pathway is critical and the contributions of particular types of HDL particles to this process are becoming better defined.
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Affiliation(s)
- George H Rothblat
- Gastroenterology, Hepatology and Nutrition Division, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104-4318, USA
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27
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Abstract
High density lipoprotein (HDL) possesses important anti-atherogenic properties and this review addresses the molecular mechanisms underlying these functions. The structures and cholesterol transport abilities of HDL particles are determined by the properties of their exchangeable apolipoprotein (apo) components. ApoA-I and apoE, which are the best characterized in structural terms, contain a series of amphipathic alpha-helical repeats. The helices located in the amino-terminal two-thirds of the molecule adopt a helix bundle structure while the carboxy-terminal segment forms a separately folded, relatively disorganized, domain. The latter domain initiates lipid binding and this interaction induces changes in conformation; the alpha-helix content increases and the amino-terminal helix bundle can open subsequently. These conformational changes alter the abilities of apoA-I and apoE to function as ligands for their receptors. The apoA-I and apoE molecules possess detergent-like properties and they can solubilize vesicular phospholipid to create discoidal HDL particles with hydrodynamic diameters of ~10 nm. In the case of apoA-I, such a particle is stabilized by two protein molecules arranged in an anti-parallel, double-belt, conformation around the edge of the disc. The abilities of apoA-I and apoE to solubilize phospholipid and stabilize HDL particles enable these proteins to be partners with ABCA1 in mediating efflux of cellular phospholipid and cholesterol, and the biogenesis of HDL particles. ApoA-I-containing nascent HDL particles play a critical role in cholesterol transport in the circulation whereas apoE-containing HDL particles mediate cholesterol transport in the brain. The mechanisms by which HDL particles are remodeled by lipases and lipid transfer proteins, and interact with SR-BI to deliver cholesterol to cells, are reviewed.
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de Beer MC, Webb NR, Whitaker NL, Wroblewski JM, Jahangiri A, van der Westhuyzen DR, de Beer FC. SR-BI selective lipid uptake: subsequent metabolism of acute phase HDL. Arterioscler Thromb Vasc Biol 2009; 29:1298-303. [PMID: 19304574 DOI: 10.1161/atvbaha.109.186502] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The purpose of this study was to investigate the interaction of SAA and SR-BI in remodeling of acute phase HDL (AP HDL). METHODS AND RESULTS We used SAA and SR-BI adenoviral vector expression models to study the interaction between these entities. SR-BI processing of mouse AP HDL generated progressively smaller discreet HDL particles with distinct apolipoprotein compositions. SR-BI actions segregated apolipoproteins with the smallest particles containing only apoA-I. Larger remnants contained apoA-I, apoA-II, and SAA. Small apoA-I only particles failed to associate with preformed HDL, whereas larger remnants readily did. The presence of SAA on SR-BI-processed HDL particles propelled apoA-I to a small lipid-poor form and accelerated apoA-I catabolism. CONCLUSIONS Data indicate that after core and surface HDL lipid perturbation by SR-BI, SAA propels apoA-I to a small lipid-poor form while accelerating HDL metabolism.
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Affiliation(s)
- Maria C de Beer
- Graduate Center for Nutritional Science, University of Kentucky Medical Center, Lexington, USA.
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29
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Brousseau ME, Millar JS, Diffenderfer MR, Nartsupha C, Asztalos BF, Wolfe ML, Mancuso JP, Digenio AG, Rader DJ, Schaefer EJ. Effects of cholesteryl ester transfer protein inhibition on apolipoprotein A-II-containing HDL subspecies and apolipoprotein A-II metabolism. J Lipid Res 2009; 50:1456-62. [PMID: 19193611 DOI: 10.1194/jlr.p800037-jlr200] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study was designed to establish the mechanism responsible for the increased apolipoprotein (apo) A-II levels caused by the cholesteryl ester transfer protein inhibitor torcetrapib. Nineteen subjects with low HDL cholesterol (<40 mg/dl), nine of whom were also treated with 20 mg of atorvastatin daily, received placebo for 4 weeks, followed by 120 mg of torcetrapib daily for the next 4 weeks. Six subjects in the nonatorvastatin cohort participated in a third phase, in which they received 120 mg of torcetrapib twice daily for 4 weeks. At the end of each phase, subjects underwent a primed-constant infusion of [5,5,5-(2)H(3)]L-leucine to determine the kinetics of HDL apoA-II. Relative to placebo, torcetrapib significantly increased apoA-II concentrations by reducing HDL apoA-II catabolism in the atorvastatin (-9.4%, P < 0.003) and nonatorvastatin once- (-9.9%, P = 0.02) and twice- (-13.2%, P = 0.02) daily cohorts. Torcetrapib significantly increased the amount of apoA-II in the alpha-2-migrating subpopulation of HDL when given as monotherapy (27%, P < 0.02; 57%, P < 0.003) or on a background of atorvastatin (28%, P < 0.01). In contrast, torcetrapib reduced concentrations of apoA-II in alpha-3-migrating HDL, with mean reductions of -14% (P = 0.23), -18% (P < 0.02), and -18% (P < 0.01) noted during the atorvastatin and nonatorvastatin 120 mg once- and twice-daily phases, respectively. Our findings indicate that CETP inhibition increases plasma concentrations of apoA-II by delaying HDL apoA-II catabolism and significantly alters the remodeling of apoA-II-containing HDL subpopulations.
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Affiliation(s)
- Margaret E Brousseau
- Cardiovascular Research Laboratory, Tufts University School of Medicine, Boston, MA, USA.
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30
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Rye KA, Bursill CA, Lambert G, Tabet F, Barter PJ. The metabolism and anti-atherogenic properties of HDL. J Lipid Res 2008; 50 Suppl:S195-200. [PMID: 19033213 DOI: 10.1194/jlr.r800034-jlr200] [Citation(s) in RCA: 213] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Population studies have shown that plasma HDL levels correlate inversely with cardiovascular disease risk. In recent years there has been intense interest in developing strategies for exploiting these cardioprotective properties by increasing HDL levels. While this approach has considerable merit, it is important to recognize that HDL are structurally and functionally diverse and consist of numerous, highly dynamic subpopulations of particles that do not all inhibit atherosclerosis to the same extent. For this reason it is essential to assess HDL subpopulation distribution and functionality when considering therapeutic interventions that raise HDL levels. This review documents what is known about the relationship between the metabolism and function of HDL subpopulations and how this affects their cardioprotective properties.
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Affiliation(s)
- Kerry-Anne Rye
- Lipid Research Group, The Heart Research Institute, Sydney, NSW, Australia.
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31
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Pownall HJ, Hosken BD, Gillard BK, Higgins CL, Lin HY, Massey JB. Speciation of Human Plasma High-Density Lipoprotein (HDL): HDL Stability and Apolipoprotein A-I Partitioning. Biochemistry 2007; 46:7449-59. [PMID: 17530866 DOI: 10.1021/bi700496w] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The distribution of apolipoprotein (apo) A-I between human high-density lipoproteins (HDL) and water is an important component of reverse cholesterol transport and the atheroprotective effects of HDL. Chaotropic perturbation (CP) with guanidinium chloride (Gdm-Cl) reveals HDL instability by inducing the unfolding and transfer of apo A-I but not apo A-II into the aqueous phase while forming larger apo A-I deficient HDL-like particles and small amounts of cholesteryl ester-rich microemulsions (CERMs). Our kinetic and hydrodynamic studies of the CP of HDL species separated according to size and density show that (1) CP mediated an increase in HDL size, which involves quasi-fusion of surface and core lipids, and release of lipid-free apo A-I (these processes correlate linearly), (2) >94% of the HDL lipids remain with an apo A-I deficient particle, (3) apo A-II remains associated with a very stable HDL-like particle even at high levels of Gdm-Cl, and (4) apo A-I unfolding and transfer from HDL to water vary among HDL subfractions with the larger and more buoyant species exhibiting greater stability. Our data indicate that apo A-I's on small HDL (HDL-S) are highly dynamic and, relative to apo A-I on the larger more mature HDL, partition more readily into the aqueous phase, where they initiate the formation of new HDL species. Our data suggest that the greater instability of HDL-S generates free apo A-I and an apo A-I deficient HDL-S that readily fuses with the more stable HDL-L. Thus, the presence of HDL-L drives the CP remodeling of HDL to an equilibrium with even larger HDL-L and more lipid-free apo A-I than with either HDL-L or HDL-S alone. Moreover, according to dilution studies of HDL in 3 M Gdm-Cl, CP of HDL fits a model of apo A-I partitioning between HDL phospholipids and water that is controlled by the principal of opposing forces. These findings suggest that the size and relative amount of HDL lipid determine the HDL stability and the fraction of apo A-I that partitions into the aqueous phase where it is destined for interaction with ABCA1 transporters, thereby initiating reverse cholesterol transport or, alternatively, renal clearance.
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Affiliation(s)
- Henry J Pownall
- Section of Atherosclerosis and Vascular Medicine, Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA.
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32
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de Beer MC, van der Westhuyzen DR, Whitaker NL, Webb NR, de Beer FC. SR-BI-mediated selective lipid uptake segregates apoA-I and apoA-II catabolism. J Lipid Res 2005; 46:2143-50. [PMID: 16061955 DOI: 10.1194/jlr.m500068-jlr200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The HDL receptor scavenger receptor class B type I (SR-BI) binds HDL and mediates the selective uptake of cholesteryl ester. We previously showed that remnants, produced when human HDL(2) is catabolized in mice overexpressing SR-BI, become incrementally smaller, ultimately consisting of small alpha-migrating particles, distinct from pre-beta HDL. When mixed with mouse plasma, some remnant particles rapidly increase in size by associating with HDL without the mediation of cholesteryl ester transfer protein, LCAT, or phospholipid transfer protein. Here, we show that processing of HDL(2) by SR-BI-overexpressing mice resulted in the preferential loss of apolipoprotein A-II (apoA-II). Short-term processing generated two distinct, small alpha-migrating particles. One particle (8.0 nm diameter) contained apoA-I and apoA-II; the other particle (7.7 nm diameter) contained only apoA-I. With extensive SR-BI processing, only the 7.7 nm particle remained. Only the 8.0 nm remnants were able to associate with HDL. Compared with HDL(2), this remnant was more readily taken up by the liver than by the kidney. We conclude that SR-BI-generated HDL remnants consist of particles with or without apoA-II and that only those containing apoA-II associate with HDL in an enzyme-independent manner. Extensive SR-BI processing generates small apoA-II-depleted particles unable to reassociate with HDL and readily taken up by the liver. This represents a pathway by which apoA-I and apoA-II catabolism are segregated.
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Affiliation(s)
- Maria C de Beer
- Graduate Center for Nutritional Sciences, University of Kentucky Medical Center, Lexington, KY 40536, USA
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33
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Jayaraman S, Gantz DL, Gursky O. Kinetic stabilization and fusion of apolipoprotein A-2:DMPC disks: comparison with apoA-1 and apoC-1. Biophys J 2005; 88:2907-18. [PMID: 15681655 PMCID: PMC1305385 DOI: 10.1529/biophysj.104.055921] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Denaturation studies of high-density lipoproteins (HDL) containing human apolipoprotein A-2 (apoA-2) and dimyristoyl phosphatidylcholine indicate kinetic stabilization. Circular dichroism (CD) and light-scattering melting curves show hysteresis and scan rate dependence, indicating thermodynamically irreversible transition with high activation energy E(a). CD and light-scattering data suggest that protein unfolding triggers HDL fusion. Electron microscopy, gel electrophoresis, and differential scanning calorimetry show that such fusion involves lipid vesicle formation and dissociation of monomolecular lipid-poor protein. Arrhenius analysis reveals two kinetic phases, a slower phase with E(a,slow) = 60 kcal/mol and a faster phase with E(a,fast) = 22 kcal/mol. Only the fast phase is observed upon repetitive heating, suggesting that lipid-poor protein and protein-containing vesicles have lower kinetic stability than the disks. Comparison of the unfolding rates and the melting data recorded by differential scanning calorimetry, CD, and light scattering indicates the rank order for the kinetic disk stability, apoA-1 > apoA-2 > apoC-1, that correlates with protein size rather than hydrophobicity. This contrasts with the tighter association of apoA-2 than apoA-1 with mature HDL, suggesting different molecular determinants for stabilization of model discoidal and plasma spherical HDL. Different effects of apoA-2 and apoA-1 on HDL fusion and stability may reflect different metabolic properties of apoA-2 and/or apoA-1-containing HDL.
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Affiliation(s)
- Shobini Jayaraman
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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34
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Gillard BK, Chen YSA, Gaubatz JW, Massey JB, Pownall HJ. Plasma factors required for human apolipoprotein A-II dimerization. Biochemistry 2005; 44:471-9. [PMID: 15641771 DOI: 10.1021/bi048591j] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Although plasma high-density lipoproteins (HDL) have been implicated in several cardioprotective pathways, the physiologic role of apolipoprotein (apo) A-II, the second most abundant of the HDL proteins, remains ambiguous. Human apo A-II is distinguished from most other species by a single cysteine (Cys6), which forms a disulfide bond with other cysteine-containing apos. In human plasma, nearly all apo A-II occurs as disulfide-linked homodimers of 17.4 kDa. Although dimerization is an important determinant of human apo A-II metabolism, its mechanism and the plasma and/or cellular sites of its dimerization are not known. Using SDS-PAGE and densitometry we investigated the kinetics of apo A-II dimerization and observed a slow (t(1/2) = approximately 10 days), second-order process in Tris-buffered saline. In 3 M guanidine hydrochloride, which disrupts apo A-II secondary structure and self-association, the rate was 3-fold slower. In contrast, lipid surfaces that promote apo A-II alpha-helix formation and lipophilic interaction profoundly enhanced the rate. Reassembled HDL increased the second-order rate constant k(2) by 7500-fold, unilamellar 1-palmitoyl-2-oleoylphosphatidylcholine vesicles increased k(2) 850-fold, and physiological concentrations of human serum albumin increased k(2) 220-fold. Thus, while dimerization of apo A-II in aqueous buffer is too slow to account for the high fraction of dimer found in plasma, lipids and proteins "catalyze" dimer formation, a process that could occur either intracellularly prior to secretion or in the plasma compartment following secretion. These data suggest that formation of disulfide links within or between polypeptide chains can be controlled, in part, by coexisting lipids and proteins.
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Affiliation(s)
- Baiba Kurins Gillard
- Department of Medicine, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
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35
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Cai L, de Beer MC, de Beer FC, van der Westhuyzen DR. Serum amyloid A is a ligand for scavenger receptor class B type I and inhibits high density lipoprotein binding and selective lipid uptake. J Biol Chem 2004; 280:2954-61. [PMID: 15561721 DOI: 10.1074/jbc.m411555200] [Citation(s) in RCA: 142] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Serum amyloid A is an acute phase protein that is carried in the plasma largely as an apolipoprotein of high density lipoprotein (HDL). In this study we investigated whether SAA is a ligand for the HDL receptor, scavenger receptor class B type I (SR-BI), and how SAA may influence SR-BI-mediated HDL binding and selective cholesteryl ester uptake. Studies using Chinese hamster ovary cells expressing SR-BI showed that (125)I-labeled SAA, both in lipid-free form and in reconstituted HDL particles, functions as a high affinity ligand for SR-BI. SAA also bound with high affinity to the hepatocyte cell line, HepG2. Alexa-labeled SAA was shown by fluorescence confocal microscopy to be internalized by cells in a SR-BI-dependent manner. To assess how SAA association with HDL influences HDL interaction with SR-BI, SAA-containing HDL was isolated from mice overexpressing SAA through adenoviral gene transfer. SAA presence on HDL had little effect on HDL binding to SR-BI but decreased (30-50%) selective cholesteryl ester uptake. Lipid-free SAA, unlike lipid-free apoA-I, was an effective inhibitor of both SR-BI-dependent binding and selective cholesteryl ester uptake of HDL. We have concluded that SR-BI plays a key role in SAA metabolism through its ability to interact with and internalize SAA and, further, that SAA influences HDL cholesterol metabolism through its inhibitory effects on SR-BI-mediated selective lipid uptake.
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Affiliation(s)
- Lei Cai
- Department of Internal Medicine, Graduate Center for Nutritional Sciences, University of Kentucky Medical Center, Lexington, Kentucky 40536, USA
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36
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Rhainds D, Brissette L. The role of scavenger receptor class B type I (SR-BI) in lipid trafficking. defining the rules for lipid traders. Int J Biochem Cell Biol 2004; 36:39-77. [PMID: 14592533 DOI: 10.1016/s1357-2725(03)00173-0] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The scavenger receptor class B type I (SR-BI) is a 509-amino acid, 82 kDa glycoprotein, with two cytoplasmic C- and N-terminal domains separated by a large extracellular domain. The aim of this review is to define the role of SR-BI as a lipoprotein receptor responsible for selective uptake of cholesteryl esters (CE) from high density lipoprotein (HDL) and low density lipoprotein (LDL) and free cholesterol (FC) efflux to lipoprotein acceptors. These activities depend on lipoprotein binding to its extracellular domain and subsequent lipid exchange at the plasma membrane. CE selective uptake supplies cholesterol to liver and steroidogenic tissues, for biliary cholesterol secretion and steroid hormone synthesis. Genetically modified mice have confirmed SR-BI's major role in tissue cholesterol uptake and in reverse cholesterol transport, i.e. cholesterol turnover. Accordingly, cellular cholesterol level, estrogens and trophic hormones regulate SR-BI expression by both transcriptional and post-transcriptional mechanisms. Importantly, mouse SR-BI overexpression has both corrective and preventive effects on atherosclerosis. Human SR-BI has very similar tissue distribution, binding properties and lipid transfer activities compared to rodent SR-BI. However, human plasma has most of its cholesterol in LDL. Thus, there is considerable interest to develop anti-atherogenic strategies involving human SR-BI-mediated increases in reverse cholesterol transport through HDL and/or LDL.
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MESH Headings
- Amino Acid Sequence
- Animals
- Biological Transport, Active
- CD36 Antigens
- Cell Membrane/chemistry
- Cell Membrane/genetics
- Cell Membrane/metabolism
- Cell Membrane/physiology
- Humans
- Lipid Metabolism
- Lipoproteins/metabolism
- Models, Biological
- Promoter Regions, Genetic
- Protein Structure, Tertiary
- Receptors, Immunologic/chemistry
- Receptors, Immunologic/genetics
- Receptors, Immunologic/metabolism
- Receptors, Immunologic/physiology
- Receptors, Scavenger
- Scavenger Receptors, Class B
- Tissue Distribution
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Affiliation(s)
- David Rhainds
- Département des Sciences Biologiques, Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montreal, Que., Canada H3C 3P8.
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37
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Asztalos BF. High-density lipoprotein metabolism and progression of atherosclerosis: new insights from the HDL Atherosclerosis Treatment Study. Curr Opin Cardiol 2004; 19:385-91. [PMID: 15218401 DOI: 10.1097/01.hco.0000126979.41946.7e] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW The purpose of this review is to summarize the current understanding of the potentially antiatherogenic properties of high-density lipoprotein related to its different components. RECENT FINDINGS Recent findings on the role of the different high-density lipoprotein subspecies in reverse cholesterol transport, inflammation, endothelial dysfunction, and low-density lipoprotein oxidation are covered. Special emphasis is put on the heterogeneity of high-density lipoprotein and functional changes related to specific high-density lipoprotein particles with the potential therapeutic alterations of high-density lipoprotein metabolism. SUMMARY The diverse action of high-density lipoprotein observed could be explained by the heterogeneity of high-density lipoprotein particles with completely different composition and properties. The modification of specific high-density lipoprotein subpopulations to reach the maximum atheroprotective effects under various pathologic conditions bears great potential in lipid research.
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Affiliation(s)
- Bela F Asztalos
- Lipid Metabolism Laboratory, Human Nutrition Research Center on Aging at Tufts University, Boston, Massachusetts 02111, USA.
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38
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Seong SY, Matzinger P. Hydrophobicity: an ancient damage-associated molecular pattern that initiates innate immune responses. Nat Rev Immunol 2004; 4:469-78. [PMID: 15173835 DOI: 10.1038/nri1372] [Citation(s) in RCA: 875] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Seung-Yong Seong
- Ghost Lab, Laboratory of Cellular and Molecular Immunology, National Insstitute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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39
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Asztalos BF, Horvath KV, Kajinami K, Nartsupha C, Cox CE, Batista M, Schaefer EJ, Inazu A, Mabuchi H. Apolipoprotein composition of HDL in cholesteryl ester transfer protein deficiency. J Lipid Res 2004; 45:448-55. [PMID: 14657195 DOI: 10.1194/jlr.m300198-jlr200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Our purpose was to compare HDL subpopulations, as determined by nondenaturing two-dimensional gel electrophoresis followed by immunoblotting for apolipoprotein A-I (apoA-I), apoA-II, apoA-IV, apoCs, and apoE in heterozygous, compound heterozygous, and homozygous subjects for cholesteryl ester transfer protein (CETP) deficiency and controls. Heterozygotes, compound heterozygotes, and homozygotes had CETP masses that were 30, 63, and more than 90% lower and HDL-cholesterol values that were 64, 168, and 203% higher than those in controls, respectively. Heterozygotes had approximately 50% lower pre-beta-1 and more than 2-fold higher levels of alpha-1 and pre-alpha-1 particles than controls. Three of the five heterozygotes' alpha-1 particles also contained apoA-II, which was not seen in controls. Compound heterozygotes and homozygotes had very large particles not observed in controls and heterozygotes. These particles contained apoA-I, apoA-II, apoCs, and apoE. However, these subjects did not have decreased pre-beta-1 levels. Our data indicate that CETP deficiency results in the formation of very large HDL particles containing all of the major HDL apolipoproteins except for apoA-IV. We hypothesize that the HDL subpopulation profile of heterozygous CETP-deficient patients, especially those with high levels of alpha-1 containing apoA-I but no apoA-II, represent an improved anti-atherogenic state, although this might not be the case for compound heterozygotes and homozygotes with very large, undifferentiated HDL particles.
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Affiliation(s)
- Bela F Asztalos
- Lipid Metabolism Laboratory, Jean Mayer United States Department of Agriculture Human Nutrition Research Center on Aging, Tufts University, Boston, MA, USA.
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40
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de Beer MC, Castellani LW, Cai L, Stromberg AJ, de Beer FC, van der Westhuyzen DR. ApoA-II modulates the association of HDL with class B scavenger receptors SR-BI and CD36. J Lipid Res 2004; 45:706-15. [PMID: 14729860 DOI: 10.1194/jlr.m300417-jlr200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The class B scavenger receptors SR-BI and CD36 exhibit a broad ligand binding specificity. SR-BI is well characterized as a HDL receptor that mediates selective cholesteryl ester uptake from HDL. CD36, a receptor for oxidized LDL, also binds HDL and mediates selective cholesteryl ester uptake, although much less efficiently than SR-BI. Apolipoprotein A-II (apoA-II), the second most abundant HDL protein, is considered to be proatherogenic, but the underlying mechanisms are unclear. We previously showed that apoA-II modulates SR-BI-dependent binding and selective uptake of cholesteryl ester from reconstituted HDL. To investigate the effect of apoA-II in naturally occurring HDL on these processes, we compared HDL without apoA-II (from apoA-II null mice) with HDLs containing differing amounts of apoA-II (from C57BL/6 mice and transgenic mice expressing a mouse apoA-II transgene). The level of apoA-II in HDL was inversely correlated with HDL binding and selective cholesteryl ester uptake by both scavenger receptors, particularly CD36. Interestingly, for HDL lacking apoA-II, the efficiency with which CD36 mediated selective uptake reached a level similar to that of SR-BI. These results demonstrate that apoA-II exerts a marked effect on HDL binding and selective lipid uptake by the class B scavenger receptors and establishes a potentially important relationship between apoA-II and CD36.
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Affiliation(s)
- Maria C de Beer
- Department of Internal Medicine, University of Kentucky Medical Center, Lexington, KY 40536, USA
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41
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Trigatti BL, Krieger M, Rigotti A. Influence of the HDL receptor SR-BI on lipoprotein metabolism and atherosclerosis. Arterioscler Thromb Vasc Biol 2003; 23:1732-8. [PMID: 12920050 DOI: 10.1161/01.atv.0000091363.28501.84] [Citation(s) in RCA: 183] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The scavenger receptor class B type I (SR-BI) was the first molecularly well-defined cell-surface HDL receptor to be described. SR-BI mediates selective HDL cholesterol uptake by formation of a productive lipoprotein/receptor complex, which requires specific structural domains and conformation states of apolipoprotein A-I present in HDL particles. SR-BI is abundantly expressed in several tissues, including the liver, where its expression is regulated by various mechanisms, including the transcriptional activity of nuclear receptors. The importance of SR-BI in overall HDL cholesterol metabolism and its antiatherogenic activity in vivo has been definitively established by SR-BI gene manipulation in mice. Remarkably, SR-BI/apolipoprotein E double-knockout mice develop complex coronary artery disease, myocardial infarction, and heart failure. Additional studies should help to define the importance of SR-BI in human health and disease.
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42
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Rigotti A, Miettinen HE, Krieger M. The role of the high-density lipoprotein receptor SR-BI in the lipid metabolism of endocrine and other tissues. Endocr Rev 2003; 24:357-87. [PMID: 12788804 DOI: 10.1210/er.2001-0037] [Citation(s) in RCA: 313] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Because cholesterol is a precursor for the synthesis of steroid hormones, steroidogenic tissues have evolved multiple pathways to ensure adequate supplies of cholesterol. These include synthesis, storage as cholesteryl esters, and import from lipoproteins. In addition to endocytosis via members of the low-density lipoprotein receptor superfamily, steroidogenic cells acquire cholesterol from lipoproteins by selective lipid uptake. This pathway, which does not involve lysosomal degradation of the lipoprotein, is mediated by the scavenger receptor class B type I (SR-BI). SR-BI is highly expressed in steroidogenic cells, where its expression is regulated by various trophic hormones, as well as in the liver. Studies of genetically manipulated strains of mice have established that SR-BI plays a key role in regulating lipoprotein metabolism and cholesterol transport to steroidogenic tissues and to the liver for biliary secretion. In addition, analysis of SR-BI-deficient mice has shown that SR-BI expression is important for alpha-tocopherol and nitric oxide metabolism, as well as normal red blood cell maturation and female fertility. These mouse models have also revealed that SR-BI can protect against atherosclerosis. If SR-BI plays similar physiological and pathophysiological roles in humans, it may be an attractive target for therapeutic intervention in cardiovascular and reproductive diseases.
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Affiliation(s)
- Attilio Rigotti
- Departamento de Gastroenterología, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile
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43
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Thuahnai ST, Lund-Katz S, Anantharamaiah GM, Williams DL, Phillips MC. A quantitative analysis of apolipoprotein binding to SR-BI: multiple binding sites for lipid-free and lipid-associated apolipoproteins. J Lipid Res 2003; 44:1132-42. [PMID: 12671027 DOI: 10.1194/jlr.m200429-jlr200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Competitive binding experiments were performed using Y1-BS1 adrenal cells to provide information about the interaction of HDL apolipoproteins with scavenger receptor class B, type I (SR-BI). Exchangeable apolipoproteins apolipoprotein A-I (apoA-I), apoA-II, apoE-2, apoE-3, and apoE-4 as phospholipid complexes bind like HDL3 to SR-BI via their multiple amphipathic alpha-helices; the concentrations required to reduce the binding of HDL3 to SR-BI by 50% (IC50) were similar and in the range of 35-50 microgram protein/ml. In the case of apoA-I, peptides corresponding to segments 1-85, 44-65, 44-87, 149-243, and 209-241 all had the same IC50 as each other (P = 0.86), showing that a specific amino acid sequence in apoA-I is not responsible for the interaction with SR-BI. The distribution of charged residues in the amphipathic alpha-helix affects the interaction, with class A and Y helices binding better than class G* helices. Synthetic alpha-helical peptides composed of either l or d amino acids can bind equally to the receptor. Association with phospholipid increases the amount of apolipoprotein binding to SR-BI without altering the affinity of binding. Lipid-free apolipoproteins compete only partially with the binding of HDL to SR-BI, whereas lipidated apolipoproteins compete fully. These results are consistent with the existence of more than one type of apolipoprotein binding site on SR-BI.
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Affiliation(s)
- Stephen T Thuahnai
- Division of GI/Nutrition, Lipid Research Group, The Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine, 19104-4318, USA
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44
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Abstract
The role of low-density lipoprotein (LDL) cholesterol in coronary artery disease (CAD) and the impact of therapeutic agents on LDL cholesterol are well established. Less is known about the role of high-density lipoprotein (HDL) cholesterol and even less about the role of the different HDL subspecies in CAD. HDL particles vary in size and density, mainly because of differences in the number of apolipoprotein (apo) particles and the amount of cholesterol ester in the core of HDL. Apo A-I is essential and, together with lipid, sufficient for the formation of HDL particles. Apo A-I-containing HDL particles play a primary role in cholesterol efflux from membranes, at least in part through interactions with the adenosine triphosphate-binding cassette transporter A1 (ABCA1). Patients with Tangier disease have mutations in the gene encoding ABCA1, which result in functionally impaired protein, a marked deficiency in HDL cholesterol, and a high risk of premature CAD. Our studies of apo A-I-containing HDL subpopulations in various patient populations reveal that patients homozygous for Tangier disease have only the pre-beta(1) HDL subspecies. Tangier heterozygotes are severely depleted in the larger alpha- and pre-alpha-mobility subspecies. Patients with low HDL cholesterol levels and those with CAD also show deficiencies in the alpha(1) and pre-alpha(1-3) HDL subspecies. The 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) increase the levels of the large alpha(1) and pre-alpha(1) subpopulations and decrease the level of the small alpha(3) subpopulation. Thus, atorvastatin, for example, significantly moves the distribution of HDL particles toward normal, followed by simvastatin, pravastatin, and lovastatin in decreasing order of efficiency. A new statin, rosuvastatin, produces greater increases in HDL cholesterol than atorvastatin, but its effect on HDL particle distribution is yet to be determined.
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Affiliation(s)
- Bela F Asztalos
- Atherosclerosis Research Laboratory, New England Medical Center, Boston, Massachusetts, USA.
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45
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Ribalta J, Vallvé JC, Girona J, Masana L. Apolipoprotein and apolipoprotein receptor genes, blood lipids and disease. Curr Opin Clin Nutr Metab Care 2003; 6:177-87. [PMID: 12589187 DOI: 10.1097/00075197-200303000-00006] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE OF REVIEW Apolipoproteins and their receptors are the main controllers of lipid metabolism and, as such, have a major impact not only on the risk of cardiovascular disease but also on the development and degeneration of the central nervous system. Variations in the genes coding for these apolipoproteins and their receptors and the interaction with the environment determine individual susceptibility to metabolic disturbances, the response to dietary or pharmacological intervention and, finally, to disease. RECENT FINDINGS This review will focus on recent findings, such as the latest concepts regarding apolipoprotein E in neurodevelopment, the newly identified apolipoprotein A-V and its influence in triglyceride metabolism, and the improved understanding of apolipoprotein A-I and HDL metabolism in the light of the discovery of the ABC family of transporters. Other key aspects of lipoprotein metabolism and cardiovascular disease risk such as apolipoprotein B-100, the LDL receptor, apolipoprotein C-III or apolipoprotein (a) will be updated. SUMMARY Variations in these genes will be analysed in relation to plasma lipid levels, their interactions with diet, treatment or other environmental stimuli, and their influence on the risk of cardiovascular disease and neurological disorders.
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Affiliation(s)
- Josep Ribalta
- Unitat de Recerca de Lípids i Arteriosclerosi, Facultat de Medicina, Hospital Universitari de Sant Joan, Institut de Recerca en Ciències de la Salut, Universitat Rovira i Virgili, Reus, Spain.
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46
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Temel RE, Parks JS, Williams DL. Enhancement of scavenger receptor class B type I-mediated selective cholesteryl ester uptake from apoA-I(-/-) high density lipoprotein (HDL) by apolipoprotein A-I requires HDL reorganization by lecithin cholesterol acyltransferase. J Biol Chem 2003; 278:4792-9. [PMID: 12473673 DOI: 10.1074/jbc.m208160200] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The severe depletion of cholesteryl ester (CE) in adrenocortical cells of apoA-I(-/-) mice suggests that apolipoprotein (apo) A-I plays an important role in the high density lipoprotein (HDL) CE selective uptake process mediated by scavenger receptor BI (SR-BI) in vivo. A recent study showed that apoA-I(-/-) HDL binds to SR-BI with the same affinity as apoA-I(+/+) HDL, but apoA-I(-/-) HDL has a decreased V(max) for CE transfer from the HDL particle to adrenal cells. The present study was designed to determine the basis for the reduced selective uptake of CE from apoA-I(-/-) HDL. Variations in apoA-I(-/-) HDL particle diameter, free cholesterol or phospholipid content, or the apoE or apoA-II content of apoA-I(-/-) HDL had little effect on HDL CE selective uptake into Y1-BS1 adrenal cells. Lecithin cholesterol acyltransferase treatment alone or addition of apoA-I to apoA-I(-/-) HDL alone also had little effect. However, addition of apoA-I to apoA-I(-/-) HDL in the presence of lecithin cholesterol acyltransferase reorganized the large heterogeneous apoA-I(-/-) HDL to a more discrete particle with enhanced CE selective uptake activity. These results show a unique role for apoA-I in HDL CE selective uptake that is distinct from its role as a ligand for HDL binding to SR-BI. These data suggest that the conformation of apoA-I at the HDL surface is important for the efficient transfer of CE to the cell.
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Affiliation(s)
- Ryan E Temel
- Department of Pharmacological Sciences, University Medical Center, State University of New York, Stony Brook, New York 11794, USA
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47
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Rinninger F, Brundert M, Budzinski RM, Fruchart JC, Greten H, Castro GR. Scavenger receptor BI (SR-BI) mediates a higher selective cholesteryl ester uptake from LpA-I compared with LpA-I:A-II lipoprotein particles. Atherosclerosis 2003; 166:31-40. [PMID: 12482548 DOI: 10.1016/s0021-9150(02)00311-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Scavenger receptor class B, type I (SR-BI) mediates the selective uptake of high-density lipoprotein- (HDL-) associated cholesteryl esters (CE), i.e. lipid uptake independent from HDL holo-particle internalisation. This pathway contributes to the HDL-mediated CE delivery to the liver. From human plasma HDL, two major lipoprotein subfractions can be isolated: one contains apolipoprotein (apo) A-I and apo A-II (LpA-I:A-II) as dominant protein components, whereas in the other population apo A-II is absent (LpA-I). In this investigation the role of SR-BI in selective CE uptake from HDL, LpA-I and LpA-I:A-II was explored. HDL(3) (d=1.125-1.21 g/ml), LpA-I and LpA-I:A-II were isolated from human plasma and radiolabeled in the protein (125I) as well as in the CE moiety ([3H]). Baby hamster kidney (BHK) cells were stably transfected with the full-length human SR-BI cDNA and these cells demonstrate SR-BI expression in immunoblots. In contrast, no SR-BI protein was detectable in control BHK cells (vector). To investigate lipoprotein uptake, cells incubated (37 degrees C, 4 h) in medium containing radiolabeled HDL(3), LpA-I or LpA-I:A-II and finally cellular tracer content was determined. For both types of BHK cells, the rate of apparent lipoprotein particle uptake according to the lipid tracer ([3H]) was in substantial excess over that due to the protein tracer (125I) demonstrating selective CE uptake ([3H]-(125)I) from HDL(3), LpA-I and LpA-I:A-II. SR-BI expression increased cellular selective CE uptake from labeled HDL(3) up to 24-fold. In BHK cells without SR-BI expression, selective CE uptake was higher from LpA-I compared with LpA-I:A-II. Analogously, in BHK cells with SR-BI expression, the rate of selective CE uptake was higher from LpA-I compared with LpA-I:A-II. In summary, SR-BI significantly increases selective CE uptake from HDL(3), LpA-I and LpA-I:A-II. Concerning HDL subfractions, the rate of SR-BI-mediated selective CE uptake is greater from LpA-I compared with LpA-I:A-II and this result suggests that SR-BI preferentially facilitates the CE transfer from LpA-I lipoprotein particles to cells.
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Affiliation(s)
- Franz Rinninger
- Zentrum fuer Innere Medizin, Universitaetsklinikum Hamburg-Eppendorf, Universitaet Hamburg, Martinistrasse 52, 20246 Hamburg, Germany.
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48
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Julve J, Escolà-Gil JC, Ribas V, González-Sastre F, Ordóñez-Llanos J, Sánchez-Quesada JL, Blanco-Vaca F. Mechanisms of HDL deficiency in mice overexpressing human apoA-II. J Lipid Res 2002; 43:1734-42. [PMID: 12364558 DOI: 10.1194/jlr.m200081-jlr200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To ascertain the mechanisms underlying the hypoalphalipoproteinemia present in mice overexpressing human apolipoprotein A-II (apoA-II) (line 11.1), radiolabeled HDL or apoA-I were injected into mice. Fractional catabolic rate of [(3)H]cholesteryl oleoyl ether HDL ([(3)H]HDL) was 2-fold increased in 11.1 transgenic mice compared with control mice and this was concomitant with increased radioactivity in liver, gonads, and adrenals. However, scavenger receptor class B, type I (SR-BI) was increased only in adrenals. [(3)H]HDL of 11.1 transgenic mice presented greater binding but decreased uptake compared with control mice when Chinese hamster ovary cells transfected with SR-BI were used, thereby pointing to unknown but SR-BI-independent mechanisms as being responsible for the increased (3)H-radioactivity seen in liver and gonads. Synthesis rate (SR) of plasma [(3)H]HDL was 2-fold decreased in 11.1 transgenic mice. Mouse (125)I-apoA-I was 2-fold more rapidly catabolized (mainly by the kidney) in transgenic mice. Mouse apoA-I displacement from HDL by the addition of isolated human apoA-II was reproduced ex vivo; thus, this mechanism may be involved in the increased renal catabolism of apoA-I. ApoA-I SR was 2-fold decreased in 11.1 transgenic mice and this was concomitant with a 2.3-fold decrease in hepatic apoA-I mRNA abundance. Our findings show that multiple mechanisms are involved in the HDL deficiency presented by mice overexpressing human apoA-II.
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Affiliation(s)
- Josep Julve
- Servei de Bioquímica, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
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49
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Abstract
Apolipoprotein (Apo) A-I and apo A-II are the major apolipoproteins of HDL. It is clearly demonstrated that there are inverse relationships between HDL-cholesterol and apo A-I plasma levels and the risk of coronary heart disease (CHD) in the general population. On the other hand, it is still not clearly demonstrated whether apo A-II plasma levels are associated with CHD risk. A recent prospective epidemiological (PRIME) study suggests that Lp A-I (HDL containing apo A-I but not apo A-II) and Lp A-I:A-II (HDL containing apo A-I and apo A-II) were both reduced in survivors of myocardial infarction, suggesting that both particles are risk markers of CHD. Apo A-II and Lp A-I:A-II plasma levels should be rather related to apo A-II production rate than to apo A-II catabolism. Mice transgenic for both human apo A-I and apo A-II are less protected against atherosclerosis development than mice transgenic for human apo A-I only, but the results of the effects of trangenesis of human apo A-II (in the absence of a co-transgenesis of human apo A-I) are controversial. It is highly suggested that HDL reduce CHD risk by promoting the transfer of peripherical free cholesterol to the liver through the so-called 'reverse cholesterol transfer'. Apo A-II modulates different steps of HDL metabolism and therefore probably alters reverse cholesterol transport. Nevertheless, some effects of apo A-II on intermediate HDL metabolism might improve reverse cholesterol transport and might reduce atherosclerosis development while some other effects might be deleterious. In different in vitro models of cell cultures, Lp A-I:A-II induce either a lower or a similar cellular cholesterol efflux (the first step of reverse cholesterol transport) than Lp A-I. Results depend on numerous factors such as cultured cell types and experimental conditions. Furthermore, the effects of apo A-II on HDL metabolism, beyond cellular cholesterol efflux, are also complex and controversial: apo A-II may inhibit lecithin-cholesterol acyltransferase (LCAT) (potential deleterious effect) and cholesteryl-ester-transfer protein (CETP) (potential beneficial effect) activities, but may increase the hepatic lipase (HL) activity (potential beneficial effect). Apo A-II may also inhibit the hepatic cholesteryl uptake from HDL (potential deleterious effect) probably through the SR-BI depending pathway. Therefore, in terms of atherogenesis, apo A-II alters the intermediate HDL metabolism in opposing ways by increasing (LCAT, SR-BI) or decreasing (HL, CETP) the atherogenicity of lipid metabolism. Effects of apo A-II on atherogenesis are controversial in humans and in transgenic animals and probably depend on the complex effects of apo A-II on these different intermediate metabolic steps which are in weak equilibrium with each other and which can be modified by both endogenous and environmental factors. It can be suggested that apo A-II is not a strong determinant of lipid metabolism, but is rather a modulator of reverse cholesterol transport.
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Affiliation(s)
- Anne Tailleux
- Faculté de Pharmacie, Département d'athérosclérose et INSERM U 545, Institut Pasteur, Université Lille 2, 1, rue du Professeur Calmette, 59019 Cedex, Lille, France.
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50
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Temel RE, Walzem RL, Banka CL, Williams DL. Apolipoprotein A-I is necessary for the in vivo formation of high density lipoprotein competent for scavenger receptor BI-mediated cholesteryl ester-selective uptake. J Biol Chem 2002; 277:26565-72. [PMID: 12000760 DOI: 10.1074/jbc.m203014200] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The severe depletion of cholesteryl ester (CE) in steroidogenic cells of apoA-I(-/-) mice suggests that apolipoprotein (apo) A-I plays a specific role in the high density lipoprotein (HDL) CE-selective uptake process mediated by scavenger receptor BI (SR-BI) in vivo. The nature of this role, however, is unclear because a variety of apolipoproteins bind to SR-BI expressed in transfected cells. In this study the role of apoA-I in SR-BI-mediated HDL CE-selective uptake was tested via analyses of the biochemical properties of apoA-I(-/-) HDL and its interaction with SR-BI on adrenocortical cells, hepatoma cells, and cells expressing a transfected SR-BI. apoA-I(-/-) HDL are large heterogeneous particles with a core consisting predominantly of CE and a surface enriched in phospholipid, free cholesterol, apoA-II, and apoE. Functional analysis showed apoA-I(-/-) HDL to bind to SR-BI with the same or higher affinity as compared with apoA-I(+/+) HDL, but apoA-I(-/-) HDL showed a 2-3-fold decrease in the V(max) for CE transfer from the HDL particle to adrenal cells. These results indicate that the absence of apoA-I results in HDL particles with a reduced capacity for SR-BI-mediated CE-selective uptake. The reduced V(max) illustrates that HDL properties necessary for binding to SR-BI are distinct from those properties necessary for the transfer of HDL CE from the core of the HDL particle to the plasma membrane. The reduced V(max) for HDL CE-selective uptake likely contributes to the severe reduction in CE accumulation in steroidogenic cells of apoA-I(-/-) mice.
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Affiliation(s)
- Ryan E Temel
- Department of Pharmacological Sciences, University Medical Center, State University of New York, Stony Brook, New York 11794, USA
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