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Botha J, Handberg A, Simonsen JB. Lipid-based strategies used to identify extracellular vesicles in flow cytometry can be confounded by lipoproteins: Evaluations of annexin V, lactadherin, and detergent lysis. J Extracell Vesicles 2022; 11:e12200. [PMID: 35362259 PMCID: PMC8971177 DOI: 10.1002/jev2.12200] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 01/18/2022] [Accepted: 02/21/2022] [Indexed: 11/12/2022] Open
Abstract
Flow cytometry (FCM) is a popular method used in characterisation of extracellular vesicles (EVs). Circulating EVs are often identified by FCM by exploiting the lipid nature of EVs by staining with Annexin V (Anx5) or lactadherin against the membrane phospholipid phosphatidylserine (PS) and evaluating the specificity of the labels by detergent lysis of EVs. Here, we investigate whether PS labelling and detergent lysis approaches are confounded by lipoproteins, another family of lipid-based nanoparticles found in blood, in both frozen and fresh blood plasma. We demonstrated that Anx5 and lactadherin in addition to EVs stained ApoB-containing lipoproteins, identified by the use of fluorophore-labelled polyclonal ApoB-antibody, and that Anx5 had a significantly larger tendency for labelling lipoprotein-bound PS than lactadherin. Furthermore, detergent lysis resulted in a decrease in both EV and lipoprotein events and especially lipoproteins positive for either Anx5 or lactadherin. Taken together, our findings pose concerns to the use of lipid-based strategies in identifying EVs by FCM and support the use of transmembrane proteins such as tetraspannins to distinguish EVs from lipoproteins.
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Affiliation(s)
- Jaco Botha
- Department of Clinical BiochemistryAalborg University Hospital, North Denmark RegionAalborgDenmark
- Department of Clinical MedicineAalborg UniversityAalborgDenmark
- Department of Health TechnologyTechnical University of DenmarkKongens LyngbyDenmark
| | - Aase Handberg
- Department of Clinical BiochemistryAalborg University Hospital, North Denmark RegionAalborgDenmark
- Department of Clinical MedicineAalborg UniversityAalborgDenmark
| | - Jens B. Simonsen
- Department of Health TechnologyTechnical University of DenmarkKongens LyngbyDenmark
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2
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Masuda R, Lodge S, Whiley L, Gray N, Lawler N, Nitschke P, Bong SH, Kimhofer T, Loo RL, Boughton B, Zeng AX, Hall D, Schaefer H, Spraul M, Dwivedi G, Yeap BB, Diercks T, Bernardo-Seisdedos G, Mato JM, Lindon JC, Holmes E, Millet O, Wist J, Nicholson JK. Exploration of Human Serum Lipoprotein Supramolecular Phospholipids Using Statistical Heterospectroscopy in n-Dimensions (SHY- n): Identification of Potential Cardiovascular Risk Biomarkers Related to SARS-CoV-2 Infection. Anal Chem 2022; 94:4426-4436. [PMID: 35230805 DOI: 10.1021/acs.analchem.1c05389] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
SARS-CoV-2 infection causes a significant reduction in lipoprotein-bound serum phospholipids give rise to supramolecular phospholipid composite (SPC) signals observed in diffusion and relaxation edited 1H NMR spectra. To characterize the chemical structural components and compartmental location of SPC and to understand further its possible diagnostic properties, we applied a Statistical HeterospectroscopY in n-dimensions (SHY-n) approach. This involved statistically linking a series of orthogonal measurements made on the same samples, using independent analytical techniques and instruments, to identify the major individual phospholipid components giving rise to the SPC signals. Thus, an integrated model for SARS-CoV-2 positive and control adults is presented that relates three identified diagnostic subregions of the SPC signal envelope (SPC1, SPC2, and SPC3) generated using diffusion and relaxation edited (DIRE) NMR spectroscopy to lipoprotein and lipid measurements obtained by in vitro diagnostic NMR spectroscopy and ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The SPC signals were then correlated sequentially with (a) total phospholipids in lipoprotein subfractions; (b) apolipoproteins B100, A1, and A2 in different lipoproteins and subcompartments; and (c) MS-measured total serum phosphatidylcholines present in the NMR detection range (i.e., PCs: 16.0,18.2; 18.0,18.1; 18.2,18.2; 16.0,18.1; 16.0,20.4; 18.0,18.2; 18.1,18.2), lysophosphatidylcholines (LPCs: 16.0 and 18.2), and sphingomyelin (SM 22.1). The SPC3/SPC2 ratio correlated strongly (r = 0.86) with the apolipoprotein B100/A1 ratio, a well-established marker of cardiovascular disease risk that is markedly elevated during acute SARS-CoV-2 infection. These data indicate the considerable potential of using a serum SPC measurement as a metric of cardiovascular risk based on a single NMR experiment. This is of specific interest in relation to understanding the potential for increased cardiovascular risk in COVID-19 patients and risk persistence in post-acute COVID-19 syndrome (PACS).
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Affiliation(s)
- Reika Masuda
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Samantha Lodge
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Luke Whiley
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Nicola Gray
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Nathan Lawler
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Philipp Nitschke
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Sze-How Bong
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Torben Kimhofer
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Ruey Leng Loo
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Berin Boughton
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Annie X Zeng
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | - Drew Hall
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia
| | | | - Manfred Spraul
- Bruker Biospin GmbH, Silberstreifen, Ettlingen 76275, Germany
| | - Girish Dwivedi
- Department of Cardiology, Fiona Stanley Hospital, Medical School, University of Western Australia, Perth 6150, Western Australia, Australia
| | - Bu B Yeap
- Department of Endocrinology and Diabetes, Fiona Stanley Hospital, Medical School, University of Western Australia, Perth 6150, Western Australia, Australia
| | - Tammo Diercks
- Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Parque Tecnológico de Bizkaia, Bld. 800, 48160 Derio, Spain
| | - Ganeko Bernardo-Seisdedos
- Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Parque Tecnológico de Bizkaia, Bld. 800, 48160 Derio, Spain
| | - José M Mato
- Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Parque Tecnológico de Bizkaia, Bld. 800, 48160 Derio, Spain
| | - John C Lindon
- Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London SW7 2AZ, U.K
| | - Elaine Holmes
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia.,Department of Metabolism, Digestion and Reproduction, Faculty of Medicine, Imperial College London, Sir Alexander Fleming Building, South Kensington, London SW7 2AZ, U.K
| | - Oscar Millet
- Precision Medicine and Metabolism Laboratory, CIC bioGUNE, Parque Tecnológico de Bizkaia, Bld. 800, 48160 Derio, Spain
| | - Julien Wist
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia.,Chemistry Department, Universidad del Valle, 76001 Cali, Colombia
| | - Jeremy K Nicholson
- Australian National Phenome Center, and Center for Computational and Systems Medicine, Health Futures Institute, Murdoch University, Harry Perkins Building, Perth 6150, Western Australia, Australia.,Department of Cardiology, Fiona Stanley Hospital, Medical School, University of Western Australia, Perth 6150, Western Australia, Australia.,Institute of Global Health Innovation, Faculty of Medicine, Imperial College London, Level 1, Faculty Building, South Kensington Campus, London SW7 2NA, U.K
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3
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Kuklenyik Z, Jones JI, Gardner MS, Schieltz DM, Parks BA, Toth CA, Rees JC, Andrews ML, Carter K, Lehtikoski AK, McWilliams LG, Williamson YM, Bierbaum KP, Pirkle JL, Barr JR. Core lipid, surface lipid and apolipoprotein composition analysis of lipoprotein particles as a function of particle size in one workflow integrating asymmetric flow field-flow fractionation and liquid chromatography-tandem mass spectrometry. PLoS One 2018; 13:e0194797. [PMID: 29634782 PMCID: PMC5892890 DOI: 10.1371/journal.pone.0194797] [Citation(s) in RCA: 18] [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: 10/17/2017] [Accepted: 03/09/2018] [Indexed: 12/18/2022] Open
Abstract
Lipoproteins are complex molecular assemblies that are key participants in the intricate cascade of extracellular lipid metabolism with important consequences in the formation of atherosclerotic lesions and the development of cardiovascular disease. Multiplexed mass spectrometry (MS) techniques have substantially improved the ability to characterize the composition of lipoproteins. However, these advanced MS techniques are limited by traditional pre-analytical fractionation techniques that compromise the structural integrity of lipoprotein particles during separation from serum or plasma. In this work, we applied a highly effective and gentle hydrodynamic size based fractionation technique, asymmetric flow field-flow fractionation (AF4), and integrated it into a comprehensive tandem mass spectrometry based workflow that was used for the measurement of apolipoproteins (apos A-I, A-II, A-IV, B, C-I, C-II, C-III and E), free cholesterol (FC), cholesterol esters (CE), triglycerides (TG), and phospholipids (PL) (phosphatidylcholine (PC), sphingomyelin (SM), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and lysophosphatidylcholine (LPC)). Hydrodynamic size in each of 40 size fractions separated by AF4 was measured by dynamic light scattering. Measuring all major lipids and apolipoproteins in each size fraction and in the whole serum, using total of 0.1 ml, allowed the volumetric calculation of lipoprotein particle numbers and expression of composition in molar analyte per particle number ratios. Measurements in 110 serum samples showed substantive differences between size fractions of HDL and LDL. Lipoprotein composition within size fractions was expressed in molar ratios of analytes (A-I/A-II, C-II/C-I, C-II/C-III. E/C-III, FC/PL, SM/PL, PE/PL, and PI/PL), showing differences in sample categories with combinations of normal and high levels of Total-C and/or Total-TG. The agreement with previous studies indirectly validates the AF4-LC-MS/MS approach and demonstrates the potential of this workflow for characterization of lipoprotein composition in clinical studies using small volumes of archived frozen samples.
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Affiliation(s)
- Zsuzsanna Kuklenyik
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jeffery I. Jones
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Michael S. Gardner
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - David M. Schieltz
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Bryan A. Parks
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Christopher A. Toth
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Jon C. Rees
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Michael L. Andrews
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Kayla Carter
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Antony K. Lehtikoski
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Lisa G. McWilliams
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Yulanda M. Williamson
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Kevin P. Bierbaum
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - James L. Pirkle
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - John R. Barr
- Clinical Chemistry Branch, Division of Laboratory Sciences, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
- * E-mail:
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4
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Davis RA. Cell and molecular biology of the assembly and secretion of apolipoprotein B-containing lipoproteins by the liver. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1440:1-31. [PMID: 10477822 DOI: 10.1016/s1388-1981(99)00083-9] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Triglycerides are one of the most efficient storage forms of free energy. Because of their insolubility in biological fluids, their transport between cells and tissues requires that they be assembled into lipoprotein particles. Genetic disruption of the lipoprotein assembly/secretion pathway leads to several human disorders associated with malnutrition and developmental abnormalities. In contrast, patients displaying inappropriately high rates of lipoprotein production display increased risk for the development of atherosclerotic cardiovascular disease. Insights provided by diverse experimental approaches describe an elegant biological adaptation of basic chemical interactions required to overcome the thermodynamic dilemma of producing a stable emulsion vehicle for the transport and tissue targeting of triglycerides. The mammalian lipoprotein assembly/secretion pathway shows an absolute requirement for: (1) the unique amphipathic protein: apolipoprotein B, in a form that is sufficiently large to assemble a lipoprotein particle containing a neutral lipid core; and, (2) a lipid transfer protein (microsomal triglyceride transfer protein-MTP). In the endoplasmic reticulum apolipoprotein B has two distinct metabolic fates: (1) entrance into the lipoprotein assembly pathway within the lumen of the endoplasmic reticulum; or, (2) degradation in the cytoplasm by the ubiquitin-dependent proteasome. The destiny of apolipoprotein B is determined by the relative availability of individual lipids and level of expression of MTP. The dynamically varied expression of cholesterol-7alpha-hydroxylase indirectly influences the rate of lipid biosynthesis and the assembly and secretion lipoprotein particles by the liver.
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Affiliation(s)
- R A Davis
- Mammalian Cell and Molecular Biology Laboratory, Department of Biology, The Molecular Biology Institute, San Diego State University, San Diego, CA 92182-0057, USA.
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5
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Capell WH, Zambon A, Austin MA, Brunzell JD, Hokanson JE. Compositional differences of LDL particles in normal subjects with LDL subclass phenotype A and LDL subclass phenotype B. Arterioscler Thromb Vasc Biol 1996; 16:1040-6. [PMID: 8696944 DOI: 10.1161/01.atv.16.8.1040] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A predominance of small LDL particles (subclass phenotype B), as determined by gradient-gel electrophoresis is found among patients with myocardial infarction. Despite physical differences in phenotype A and B particles, differences in lipid composition of particles in these phenotypes have yet to be reported in an unselected population of males and females. The present study used lipid/apoB ratios to analyze the amount of lipid per LDL particle, isolated by density-gradient ultracentrifugation, in 70 healthy subjects. Relative to apoB, the LDL particles from phenotype B subjects were found to contain less free cholesterol (0.391 +/- 0.05 versus 0.465 +/- 0.05; mean +/- SD; P < .001), phospholipid (1.26 +/- 0.2 versus 1.43 +/- 0.2; P < .001), and cholesteryl ester (1.97 +/- 0.1 versus 2.11 +/- 0.2; P < .001) than particles from phenotype A subjects. The amount of triglyceride per LDL particle did not differ between the two phenotypes (0.410 +/- 0.1 versus 0.406 +/- 0.1; P = NS) despite higher plasma triglyceride levels in the phenotype B subjects. LDL size and buoyancy were positively correlated with particle free cholesterol, phospholipid, and cholesteryl ester but not with particle triglyceride. These data suggest that the physical properties of LDL from subjects with phenotype A and B reflect their lipid composition. The compositional differences between LDL particles of the two phenotypes may provide new insight into the increased risk of myocardial infarction in subjects with small, dense LDL.
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Affiliation(s)
- W H Capell
- Department of Medicine, University of Washington, Seattle 98195, USA
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6
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Cianflone K, Avramoglu RK, Sawyez C, Huff MW. Inhibition of lipoprotein lipase induced cholesterol ester accumulation in human hepatoma HepG2 cells. Atherosclerosis 1996; 120:101-14. [PMID: 8645351 DOI: 10.1016/0021-9150(95)05690-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
It has been suggested previously that lipoprotein lipase may act as a ligand to enhance binding and uptake of lipoprotein particles. In the present study we have examined the capacity of bovine milk lipoprotein lipase to induce intracellular accumulation of triglyceride and cholesterol ester by VLDL (Sr 60-400) isolated from Type IV hypertriglyceridemic subject (HTg-VLDL) in HepG2 cells, independent of its lipolytic activity. We have also attempted to elucidate the cellular receptor mechanisms responsible for these effects. HTg-VLDL-mediated increases in intracellular triglyceride and cholesterol ester were dependent on the presence of an active lipase. Bovine milk lipoprotein lipase (LPL) increases triglyceride mass by 301% +/- 28% (P < 0.0005) and cholesterol ester mass by 176% +/- 12% (P < 0.0005). These HTg-VLDL-mediated increases in intracellular triglyceride and cholesterol ester did not occur when heat-inactivated lipase was used. Rhizopus lipase could replace LPL and cause equivalent increases in intracellular triglyceride and cholesterol ester (472% +/- 61%(P < 0.005) and 202% +/- 25% (P < 0.025) respectively vs. control). HTg-VLDL treated with LPL and reisolated also caused equivalent increases (274% +/- 18%(P < 0.01) and 177% +/- 12% (P < 0.005) for triglyceride and cholesterol ester). LDL also caused increases in intracellular cholesterol ester (189% +/- 20%(P < 0.005)), although three times more LDL cholesterol had to be added to achieve the same effect. These LDL-induced increases were effectively blocked by monoclonal antibodies directed against the B,E receptor binding domains of apo B (-97% +/- 13% (P < 0.0005) with anti-apo B 5E11 and -68% +/- 13% (P < 0.05) for anti-apo B B1B3) or by anti-B,E receptor antibodies (-77% +/- 7% (P < 0.01) antibody C7). These same antibodies had little effect on the HTg-VLDL+LPL-induced increases in cholesterol ester (+21%, +15% and -22% for 5E11, B1B3 and C7, respectively). Monoclonal anti-apo E antibodies also had no effect on LDL-mediated increases in intracellular cholesterol ester, but had a small and significant effect on VLDL-mediated increases in cholesterol ester. However, heparin, which interferes with cell surface proteoglycan interaction, was very effective at blocking HTg-VLDL-mediated increases in cholesterol ester in the presence of LPL (-86% +/- 8% P < 0.0005). Heparin was also effective in the presence of Rhizopus lipase (-79%) or lipolyzed re-isolated HTg-VLDL (-95%). These results suggest that lipoprotein lipase may enhance the uptake process beyond its role in lipolytic remodelling but does not appear to be an absolute requirement. In contrast, heparin had no effect on LDL-mediated cholesterol ester accumulation. Lactoferrin, which inhibits interaction with the low density lipoprotein receptor-related protein (LRP), was also very effective at inhibiting HTg-VLDL increases in intracellular cholesterol ester (-95% +/- 6%, P < 0.01). However, there was no effect of either heparin or lactoferrin on HTg-VLDL-mediated triglyceride accumulation. Thus cell surface heparin sulphate may facilitate intracellular lipid acquisition by providing a stabilizing bridge with the lipoproteins and enhance uptake through receptor-mediated processes such as LRP.
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Affiliation(s)
- K Cianflone
- Robarts Research Institute, University of Western Ontario, London, Canada
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7
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Stefansson S, Chappell DA, Argraves KM, Strickland DK, Argraves WS. Glycoprotein 330/low density lipoprotein receptor-related protein-2 mediates endocytosis of low density lipoproteins via interaction with apolipoprotein B100. J Biol Chem 1995; 270:19417-21. [PMID: 7642623 DOI: 10.1074/jbc.270.33.19417] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The ability of glycoprotein 330/low density lipoprotein receptor-related protein-2 (LRP-2) to function as a lipoprotein receptor was investigated using cultured mouse F9 teratocarcinoma cells. Treatment with retinoic acid and dibutyryl cyclic AMP, which induces F9 cells to differentiate into endoderm-like cells, produced a 50-fold increase in the expression of LRP-2. Levels of the other members of the low density lipoprotein (LDL) receptor (LDLR) family, including LDLR, the very low density lipoprotein receptor, and LRP-1, were reduced. When LDL catabolism was examined in these cells, it was found that the treated cells endocytosed and degraded at 10-fold higher levels than untreated cells. The increased LDL uptake coincided with increased LRP-2 activity of the treated cells, as measured by uptake of both 125I-labeled monoclonal LRP-2 antibody and the LRP-2 ligand prourokinase. The ability of LDL to bind to LRP-2 was demonstrated by solid-phase binding assays. This binding was inhibitable by LRP-2 antibodies, receptor-associated protein (the antagonist of ligand binding for all members of the LDLR family), or antibodies to apoB100, the major apolipoprotein component of LDL. In cell assays, LRP-2 antibodies blocked the elevated 125I-LDL internalization and degradation observed in the retinoic acid/dibutyryl cyclic AMP-treated F9 cells. A low level of LDL endocytosis existed that was likely mediated by LDLR since it could not be inhibited by LRP-2 antibodies, but was inhibited by excess LDL, receptor-associated protein, or apoB100 antibody. The results indicate that LRP-2 can function to mediate cellular endocytosis of LDL, leading to its degradation. LRP-2 represents the second member of the LDLR family identified as functioning in the catabolism of LDL.
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Affiliation(s)
- S Stefansson
- Biochemistry Department, J.H. Holland Laboratory, American Red Cross, Rockville, Maryland 20855, USA
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8
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Hokanson JE, Krauss RM, Albers JJ, Austin MA, Brunzell JD. LDL physical and chemical properties in familial combined hyperlipidemia. Arterioscler Thromb Vasc Biol 1995; 15:452-9. [PMID: 7749856 DOI: 10.1161/01.atv.15.4.452] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Familial combined hyperlipidemia (FCHL) is characterized by elevations of triglyceride and/or cholesterol within families and an elevation in apoB. Although small dense LDL has been consistently associated with hypertriglyceridemia, small dense LDL persists despite reductions in triglyceride after treatment with gemfibrozil in FCHL. The current study evaluated potential differences in the distribution and chemical composition of LDL species in patients with FCHL and normolipidemic control subjects. LDL from FCHL patients was characterized by a relative abundance of a discrete LDL species with a mean peak analytic ultracentrifuge flotation rate (S0f) of 4.7 +/- 0.5 (SEM), a density of 1.041 +/- 0.001 g/mL, and a particle diameter of 250 +/- 1 A as assessed by gradient gel electrophoresis. The major LDL species in the control subjects had a higher mean S0f rate (6.3 +/- 0.4), was more buoyant (density, 1.037 +/- 0.001 g/mL), and was larger (diameter, 262 +/- 2 A). In addition, in a series of six LDL fractions separated by equilibrium density gradient ultracentrifugation, particle diameters were significantly smaller in all fractions from FCHL patients compared with those from control subjects. LDL particles from patients contained less free cholesterol, cholesteryl ester, and phospholipid than LDL from control subjects. The amount of triglyceride per LDL particle, however, did not differ between FCHL patients and control subjects. Differences in flotation rate and mass of the major LDL species between patients and control subjects could not be fully accounted for by differences in plasma triglyceride levels. Thus, LDL particles from FCHL patients are smaller and more dense with less cholesterol and phospholipid. Many of these differences appear to be independent of plasma triglyceride.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J E Hokanson
- Department of Medicine, University of Washington, Seattle 98195, USA
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9
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Valenzuela A, Hougen HP, Villanueva E. Lipoproteins and apolipoproteins in pericardial fluid: new postmortem markers for coronary atherosclerosis. Forensic Sci Int 1994; 66:81-8. [PMID: 8063276 DOI: 10.1016/0379-0738(94)90331-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Determinations of lipoproteins (HDL-cholesterol and LDL-cholesterol) and various apolipoproteins (Apo A-I, Lp(a) and Apo B-100) were performed in postmortem pericardial fluid. Studies were carried out on 77 cadavers: 41 adult subjects with a morphological and biochemical diagnosis of intermediate or fresh myocardial infarction and 36 adults with no previous history of myocardial infarction. HDL and LDL were determined by enzymatic methods. Both apolipoproteins (A-I and B-100) were quantified by radio-immunoassay methods and Lp(a) was measured by enzyme immunoassay. Cases with severe atherosclerosis of coronary arteries showed higher levels of Apo B in pericardial fluid compared to cases without atherosclerosis. A significant increase of Apo B was found in cases with a positive diagnosis of myocardial infarction. Due to the high level of Apo B in pericardial fluid, a decrease in the LDL/Apo B ratio, along with a pronounced increase in the Apo B/Apo A ratio, was detected. The determination of Apo B in pericardial fluid can be a useful parameter to be included in biochemical analysis for the postmortem diagnosis of myocardial infarction related to coronary atherosclerosis.
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Affiliation(s)
- A Valenzuela
- Department of Forensic Medicine, University of Granada, Spain
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10
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Chappell DA, Fry GL, Waknitz MA, Muhonen LE, Pladet MW. Low density lipoprotein receptors bind and mediate cellular catabolism of normal very low density lipoproteins in vitro. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74418-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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11
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Huff MW, Sawyez CG, Connelly PW, Maguire GF, Little JA, Hegele RA. Beta-VLDL in hepatic lipase deficiency induces apoE-mediated cholesterol ester accumulation in macrophages. ARTERIOSCLEROSIS AND THROMBOSIS : A JOURNAL OF VASCULAR BIOLOGY 1993; 13:1282-90. [PMID: 8364012 DOI: 10.1161/01.atv.13.9.1282] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Hepatic lipase-deficient subjects in the Ontario kindred are compound heterozygotes for hepatic lipase mutations (Ser267-->Phe and Thr383-->Met). Cholesteryl ester-rich beta-very-low-density lipoprotein (beta-VLDL) accumulates in plasma and such subjects have premature atherosclerosis. To determine a possible mechanism, we hypothesized that hepatic lipase-deficient beta-VLDL, homozygous for apolipoprotein (apo) E3, would cause cholesteryl ester accumulation and foam cell formation in macrophages. beta-VLDL and pre-beta-VLDL were isolated by Pevikon electrophoresis and incubated with J774 macrophages, cells that do not secrete apoE. beta-VLDL increased cellular cholesteryl ester content 13-fold, whereas pre-beta-VLDL increased cholesteryl ester sevenfold. beta-VLDL increased acyl CoA:cholesterol acyltransferase activity fourfold (measured as [14C]oleate incorporation into cholesteryl ester). Preincubation of hepatic lipase-deficient beta-VLDL with the anti-apoE monoclonal antibody 1D7, which inhibits binding of apoE to low-density lipoprotein receptors, inhibited cellular cholesteryl ester accumulation by 75%, whereas the anti-apoB blocking monoclonal antibody 5E11 failed to inhibit cellular cholesteryl ester accumulation. In contrast to hepatic lipase deficiency, beta-VLDL from type III subjects (E2/E2) failed to increase cellular cholesteryl ester or acyl CoA:cholesterol acyltransferase more than 1.5-fold. Thus, hepatic lipase-deficient beta-VLDL readily induces cholesteryl ester accumulation in J774 macrophages, a process mediated by functional apoE3. This may explain the premature atherosclerosis observed in this kindred.
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Affiliation(s)
- M W Huff
- Department of Medicine, University of Western Ontario, Robarts Research Institute, London, Ontario, Canada
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12
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Evans AJ, Sawyez CG, Wolfe BM, Connelly PW, Maguire GF, Huff MW. Evidence that cholesteryl ester and triglyceride accumulation in J774 macrophages induced by very low density lipoprotein subfractions occurs by different mechanisms. J Lipid Res 1993. [DOI: 10.1016/s0022-2275(20)39692-9] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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13
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Chappell DA, Fry GL, Waknitz MA, Berns JJ. Evidence for isomerization during binding of apolipoprotein-B100 to low density lipoprotein receptors. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)48489-x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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14
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Chappell D, Fry G, Waknitz M, Berns J. Ligand size as a determinant for catabolism by the low density lipoprotein (LDL) receptor pathway. A lattice model for LDL binding. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54997-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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15
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Huff MW, Evans AJ, Sawyez CG, Wolfe BM, Nestel PJ. Cholesterol accumulation in J774 macrophages induced by triglyceride-rich lipoproteins. Comparison of very low density lipoprotein from subjects with type III, IV, and V hyperlipoproteinemias. ARTERIOSCLEROSIS AND THROMBOSIS : A JOURNAL OF VASCULAR BIOLOGY 1991; 11:221-33. [PMID: 1998641 DOI: 10.1161/01.atv.11.2.221] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The capacity of human triglyceride-rich lipoproteins to induce cholesterol accumulation in the murine J774 macrophage cell line was investigated with large very low density lipoprotein (VLDL, Sf 60-400) obtained from subjects with type III, IV, and V hyperlipoproteinemias. After incubation for 24 hours, VLDLs from type IV and type V subjects were similar in their ability to raise cellular cholesterol deposition threefold to fourfold and cellular triglyceride 16-fold. The increase in cholesterol was entirely due to the dramatic increase in cholesterol ester, from less than 1 to greater than 50 micrograms/mg cell protein. Total cholesterol accumulation was fourfold to fivefold greater than the cholesterol accumulation observed for VLDL or low density lipoprotein (LDL) from normal subjects. Cholesterol esterification (acyl coenzyme A: cholesterol acyltransferase [ACAT] activity) paralleled the rate of cholesterol accumulation in these cells. Treating the macrophages with the ACAT inhibitor 58035, which is known to downregulate the LDL receptor in these cells, diminished cholesterol accumulation by 40% for type IV VLDL and by 23% for normal LDL. Since hypertriglyceridemic VLDL carries excess apoprotein (apo) E molecules, we investigated the role of normal and abnormal apo E. An anti-apo E monoclonal antibody, known to block the binding of apo E to the LDL receptor, blocked type IV VLDL-induced cholesterol ester accumulation by approximately 70%. In contrast to type IV subjects, VLDL from type III subjects (homozygous for apo E2) when incubated with J774 macrophages (which do not secrete apo E) caused only a modest 1.5-2-fold increase in cellular cholesterol. Pre-beta- and beta-migrating VLDL subfractions from type III subjects were equally ineffective in causing cholesterol accumulation. By contrast, beta-VLDL from cholesterol-fed rabbits caused a sevenfold to eightfold increase in cellular cholesterol content. These results indicate that triglyceride-rich lipoproteins from type IV and type V subjects can cause substantial cholesterol ester accumulation and enhanced cholesterol esterification in J774 cells. The lower cholesterol accumulation with type IV VLDL in the presence of apo E antibodies and VLDL from type III subjects demonstrates the importance of functional apo E in this process.
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Affiliation(s)
- M W Huff
- Department of Medicine, University of Western Ontario, London, Canada
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16
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Milne R, Théolis R, Maurice R, Pease RJ, Weech PK, Rassart E, Fruchart JC, Scott J, Marcel YL. The Use of Monoclonal Antibodies to Localize the Low Density Lipoprotein Receptor-binding Domain of Apolipoprotein B. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47176-7] [Citation(s) in RCA: 94] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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17
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Phillips ML, Schumaker VN. Conformation of apolipoprotein B after lipid extraction of low density lipoproteins attached to an electron microscope grid. J Lipid Res 1989. [DOI: 10.1016/s0022-2275(20)38356-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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18
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Cardin AD, Weintraub HJ. Molecular modeling of protein-glycosaminoglycan interactions. ARTERIOSCLEROSIS (DALLAS, TEX.) 1989; 9:21-32. [PMID: 2463827 DOI: 10.1161/01.atv.9.1.21] [Citation(s) in RCA: 1044] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Forty-nine regions in 21 proteins were identified as potential heparin-binding sites based on the sequence organizations of their basic and nonbasic residues. Twelve known heparin-binding sequences in vitronectin, apolipoproteins E and B-100, and platelet factor 4 were used to formulate two search strings for identifying potential heparin-binding regions in other proteins. Consensus sequences for glycosaminoglycan recognition were determined as [-X-B-B-X-B-X-] and [-X-B-B-B-X-X-B-X-] where B is the probability of a basic residue and X is a hydropathic residue. Predictions were then made as to the heparin-binding domains in endothelial cell growth factor, purpurin, and antithrombin-III. Many of the natural sequences conforming to these consensus motifs show prominent amphipathic periodicities having both alpha-helical and beta-strand conformations as determined by predictive algorithms and circular dichroism studies. The heparin-binding domain of vitronectin was modeled and formed a hydrophilic pocket that wrapped around and folded over a heparin octasaccharide, yielding a complementary structure. We suggest that these consensus sequence elements form potential nucleation sites for the recognition of polyanions in proteins and may provide a useful guide in identifying heparin-binding regions in other proteins. The possible relevance of protein-glycosaminoglycans interactions in atherosclerosis is discussed.
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Affiliation(s)
- A D Cardin
- Merrell Dow Research Institute, Cincinnati, Ohio 45215
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Detection of the low density lipoprotein (LDL) receptor on nitrocellulose paper with colloidal gold-LDL conjugates. J Lipid Res 1987. [DOI: 10.1016/s0022-2275(20)38584-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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21
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Roach PD, Noël SP. Biotinylation of low density lipoproteins via free amino groups without loss of receptor binding activity. J Lipid Res 1987. [DOI: 10.1016/s0022-2275(20)38583-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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22
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Corsini A, Spilman CH, Innerarity TL, Arnold KS, Rall SC, Boyles JK, Mahley RW. Receptor binding activity of lipid recombinants of apolipoprotein B-100 thrombolytic fragments. J Lipid Res 1987. [DOI: 10.1016/s0022-2275(20)38571-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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23
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Hirose N, Blankenship DT, Krivanek MA, Jackson RL, Cardin AD. Isolation and characterization of four heparin-binding cyanogen bromide peptides of human plasma apolipoprotein B. Biochemistry 1987; 26:5505-12. [PMID: 3676266 DOI: 10.1021/bi00391a044] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Apolipoprotein B-100 (apoB-100) is the major protein constituent of human plasma low-density lipoproteins (LDL). On the basis of its amino acid sequence [Chen, S.-H., Yang, C.-Y., Chen, P.-F., Setzer, D., Tanimura, M., Li, W.-H., Gotto, A. M., Jr., & Chan, L. (1986) J. Biol. Chem. 261, 12918-12921], apo B-100 is one of the largest monomeric proteins known with a calculated molecular weight of 512937. Heparin binds to the LDL surface by interacting with positively charged amino acid residues of apoB-100, forming soluble complexes in the absence of divalent metals and insoluble complexes in their presence. The purpose of this study was to isolate and characterize the heparin-binding domain(s) of apoB-100. Human plasma LDL were fragmented with cyanogen bromide (CNBr). After delipidation and reduction-carboxymethylation, the CNBr peptides were fractionated by sequential chromatography on DEAE-Sephacel, Mono S, and high reactive heparin (HRH) AffiGel-10; HRH was purified by chromatography of crude bovine lung heparin on LDL AffiGel-10. Heparin-binding peptides were further purified by reverse-phase high-performance liquid chromatography. Heparin-binding activity was monitored by a dot-blot assay with 125I-HRH. The amino-terminal sequences of four CNBr heparin-binding peptides (CNBr-I-IV) were determined. CNBr-I-IV correspond to residues 2016-2151, 3109-3240, 3308-3394, and 3570-3719, respectively, of the amino acid sequence of apoB-100. Each CNBr peptide contains a domain(s) of basic amino acid residues which we suggest accounts for their heparin-binding activity.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- N Hirose
- Merrell Dow Research Institute, Cincinnati, Ohio 45215-6300
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24
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Tikkanen MJ. Immunogenetic polymorphism of apolipoprotein B in humans: studies with a monoclonal anti-Ag(c) antibody. Am Heart J 1987; 113:428-32. [PMID: 3544758 DOI: 10.1016/0002-8703(87)90609-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In studies that use a monoclonal antibody (MB-19), apolipoprotein B exhibited one of three immunophenotypes: high, intermediate, or low affinity binding to this antibody. The distribution of these immunophenotypes (allotypes) in families was compatible with a codominant transmission of two alleles, one coding for the high and the other for the low affinity binding allotype. The high affinity binding allotype coincided with antigen Ag(c) and the low affinity binding allotype with Ag(g), two allelic antigenic determinants previously defined by human antisera. Preliminary studies did not reveal differences in plasma lipid levels in association with apolipoprotein B allotypes. Young Finnish men with low affinity binding apolipoprotein B had slightly lower plasma apolipoprotein B levels than those with the intermediate affinity binding phenotype.
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26
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Cardin AD, Ranganathan S, Hirose N, Wallhausser L, Harmony JA, Jackson RL. Effect of trypsin treatment on the heparin- and receptor-binding properties of human plasma low-density lipoproteins. Biochemistry 1986; 25:5258-63. [PMID: 3768346 DOI: 10.1021/bi00366a041] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The effect of trypsin treatment on the heparin- and receptor-binding properties of human plasma low-density lipoproteins (LDL) was examined. LDL were treated with trypsin (2% by weight) for 16 h at 37 degrees C, and the trypsinized core particles (T-LDL) were isolated by gel permeation chromatography on Sepharose CL-4B. Trypsin degraded the apolipoprotein B moiety (Mr = 550,000) of LDL into numerous peptides of Mr less than 110,000, resulting in the release of 25% +/- 5% (n = 6) of its surface-associated protein. Relative to LDL, T-LDL had an increased phospholipid/protein ratio, decreased flotation density and alpha-helical structure, and increased fluidity of the surface and core constituents. Compared to LDL, T-LDL showed a 60% decreased capacity to suppress [1-14C]acetate incorporation into cellular sterols consistent with decreased binding to the LDL receptor. In contrast, T-LDL showed an enhanced capacity to form soluble complexes with heparin in the absence and presence of 2 mM Ca2+. Between 5 and 25 mM Ca2+, both LDL and T-LDL were maximally precipitated by heparin; the stoichiometry of the insoluble complexes (uronic acid/phospholipid, w/w) was 0.054 +/- 0.004 and 0.055 +/- 0.005 (n = 18) for LDL and T-LDL, respectively. Thus, trypsin treatment significantly diminished the lipoprotein's interaction with cells but not with heparin. This finding suggests that proteolysis may decrease receptor-mediated uptake of LDL without diminishing the lipoprotein's reactivity with acellular components of the arterial wall.
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27
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Hospattankar AV, Fairwell T, Meng M, Ronan R, Brewer HB. Identification of sequence homology between human plasma apolipoprotein B-100 and apolipoprotein B-48. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67622-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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28
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Aggerbeck LP, Caron F, Lachacinski N, Bouma ME. Isolation and characterization of three monoclonal antibodies to human serum low density lipoprotein apoprotein B. Biochimie 1986; 68:531-41. [PMID: 2427125 DOI: 10.1016/s0300-9084(86)80197-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Human serum low density lipoprotein (LDL) is a large (Mr = 2-3 X 10(6), complex particle composed of lipid, protein and carbohydrate. We obtained about 40 mouse spleen-myeloma hybrid cell lines which produce antibodies against LDL. Three of them, SC2, SC3 and SC10, have been cloned and subcloned and their antibody products characterized. They recognize three non-overlapping epitopes in native LDL. Two of them, SC3 and SC10, also are capable of recognizing very low density lipoprotein, (VLDL), whereas SC2 reacts only weakly with VLDL. All three antigenic determinants remain intact, and accessible to antibodies on the LDL protein apo B, prepared by delipidation in a 'non-denaturing' detergent, sodium deoxycholate. However, apo B prepared by organic solvent, ether-ethanol, or sodium dodecyl sulfate (SDS) delipidation, while reacting strongly with SC10, is only poorly recognized by SC2 or SC3. Proteolysis of LDL with trypsin, chymotrypsin, Staphylococcus aureus protease, papain or thermolysin gives, in each case, several non-identical protein fragments which are separable by SDS-polyacrylamide gel electrophoresis. Upon immunoblotting, some of these fragments are now recognized by either SC3 or SC10 but not SC2, some are recognized by both SC3 and SC10, and others are immunologically unreactive. The protein bands that are separated by SDS gel electrophoresis are composed of several non-identical fragments and contain the antigenic sites to differing degrees. Some of the immunologically reactive fragments do not appear to contain carbohydrate. Reduction and carboxymethylation do not destroy the immunoreactivity of LDL toward any of the antibodies; however, modification of lysine residues by citraconic anhydride markedly diminishes the reactivity of LDL toward SC3. It is likely that the two antibodies SC3 and SC10 are directed against different linear amino acid sequences or very stable domains, whereas the third, SC2, is directed against a more fragile conformational domain of apo B.
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29
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Young SG, Witztum JL, Casal DC, Curtiss LK, Bernstein S. Conservation of the low density lipoprotein receptor-binding domain of apoprotein B. Demonstration by a new monoclonal antibody, MB47. ARTERIOSCLEROSIS (DALLAS, TEX.) 1986; 6:178-88. [PMID: 3954672 DOI: 10.1161/01.atv.6.2.178] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The fact that low density lipoprotein (LDL) from multiple animal species binds to the human LDL receptor suggested that the LDL-receptor binding domain of apoprotein (apo)B must be evolutionarily conserved. To determine if a common receptor domain epitope existed on apo B, we generated a monoclonal antibody that was specific for the LDL-receptor domain of apo B. This was accomplished by using a screening procedure that selected for a hybridoma supernatant that could block specific cellular uptake and degradation of LDL. Western blots showed that this antibody, termed MB47, was specific for apo B-100. Fluid phase assays indicated a high binding affinity (Ka = 4 X 10(9) M-1) and demonstrated that all human LDL particles expressed the MB47 epitope. Scatchard analysis indicated that a maximum of one MB47 molecule bound to each LDL particle. In solid phase assays, antibody MB47 bound to plasma or LDL of multiple mammalian species, including guinea pig, rabbit, pig, dog, cat, seal, whale, bear, and lion, but it did not bind to mouse or rat LDL. In contrast, a rabbit antiserum to LDL and two other anti-apo B monoclonal antibodies, MB3 and MB19, which do not bind to the receptor domain, were specific only for human LDL. LDL from multiple species, including mouse LDL, competed effectively with 125I-human LDL for binding to human fibroblasts. MB47 effectively inhibited uptake and degradation of labeled human, guinea pig, and rabbit LDL by both human and guinea pig fibroblasts. We conclude that antibody MB47 binds to a single receptor domain on LDL and identifies a vital region conserved through mammalian evolution.
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30
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Marcel YL, Weech PK. Isoelectric focusing of plasma lipoproteins. Methods Enzymol 1986; 128:432-41. [PMID: 3724518 DOI: 10.1016/0076-6879(86)28085-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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31
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Knott TJ, Rall SC, Innerarity TL, Jacobson SF, Urdea MS, Levy-Wilson B, Powell LM, Pease RJ, Eddy R, Nakai H. Human apolipoprotein B: structure of carboxyl-terminal domains, sites of gene expression, and chromosomal localization. Science 1985; 230:37-43. [PMID: 2994225 DOI: 10.1126/science.2994225] [Citation(s) in RCA: 241] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Apolipoprotein (apo-) B is the ligand responsible for the receptor-mediated catabolism of low density lipoproteins, the principal cholesterol-transporting lipoproteins in plasma. The primary structure of the carboxyl-terminal 30 percent (1455 amino acids) of human apo-B (apo-B100) has been deduced from the nucleotide sequence of complementary DNA. Portions of the protein structure that may relate to its receptor binding function and lipid binding properties have been identified. The apo-B100 messenger RNA is about 19 kilobases in length. The apo-B100 gene is expressed primarily in liver and, to a lesser extent, in small intestine, but in no other tissues. The gene for apo-B100 is located in the p24 region (near the tip of the short arm) of chromosome 2.
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32
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Stoichiometric binding of apolipoprotein B-specific monoclonal antibodies to low density lipoproteins. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39129-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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33
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Abstract
A human liver cDNA library was screened for sequences coding for apolipoprotein B (apo B), the major protein of human low density lipoproteins. A mixture of synthetic oligonucleotides (26 bases long) coding for an amino acid sequence known to exist in apo B was used as a hybridization probe. A clone was identified that had a cDNA insert of 593 base pairs and that contained sequences coding for a peptide of 24 residues that had earlier been isolated from apo B by limited proteolysis. The entire nucleotide sequence of the cDNA insert consists of one open reading frame coding for 197 amino acids. Apo B-related RNAs were found in human liver, baboon liver, and the human hepatoma cell line HepG2. None were detected in placenta, simian virus 40 (SV40)-transformed fibroblasts, and a lymphoblastoid cell line. The length of the mature apo B mRNA was estimated to be 18 kb, enough to code for a protein with a molecular weight in the neighborhood of 500,000.
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34
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Tikkanen M, Schonfeld G. The recognition domain for the low density lipoprotein cellular receptor is expressed once on each lipoprotein particle. Biochem Biophys Res Commun 1985; 126:773-7. [PMID: 3977888 DOI: 10.1016/0006-291x(85)90251-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The stoichiometry of binding of monoclonal antibodies and Fab fragments to LDL was assessed. Increasing amounts of two [125I]-labelled antibodies which define epitopes at or near the LDL-receptor recognition domains of apoB were incubated with fixed amounts of LDL and antibody-LDL complexes were separated from free antibodies by heparin-MnCl2 precipitation. Saturation kinetics were obtained and data were analyzed according to Scatchard. One antibody or Fab fragment was bound per LDL particle. Homogeneity of binding was indicated by straight Scatchard lines and by the binding of virtually all LDL particles by an antibody affinity chromatographic column.
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35
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Cazzolato G, Bittolo Bon G, Avogaro P. Apoprotein B-48 is a constant finding in very low density lipoproteins of humans. ARTERIOSCLEROSIS (DALLAS, TEX.) 1985; 5:88-92. [PMID: 3966911 DOI: 10.1161/01.atv.5.1.88] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The results of this study indicate that very low density lipoprotein (VLDL) from the plasma of fasting normolipidemic or slightly hypertriglyceridemic subjects contains two apo B species. In SDS gel electrophoresis, the VLDL shows the presence of a major band corresponding to low density lipoprotein (LDL) apo B (apo B-100) and a minor band with the appropriate mobility of the lymph chylomicron apo B (apo B-48). The reactivity of monoclonal antibodies directed against opportunely selected human apo B suggests that the protein with the lower molecular weight corresponds to apo B-48. This finding was confirmed by using immunoadsorbants and affinity chromatography with monoclonal antibodies that react only with apo B-100. Through this method, VLDL were separated into two fractions: one that had only apo B-100 and one with both apo B-100 and apo B-48. Hepatic and intestinal VLDL may constitute different particles. The ratio of apo B-100 to apo B-48 in VLDL decreased as the mass of fasting plasma VLDL increased. This may improve our understanding of the metabolism of triglyceride-rich lipoproteins. The investigation of the new subspecies of apo B may be relevant in understanding the atherogenetic process and better defining the hyperlipidemic states.
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36
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37
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Cotton RG. Monoclonal antibodies in the study of structure-function relationships of proteins. Med Res Rev 1985; 5:77-106. [PMID: 3884931 DOI: 10.1002/med.2610050104] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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38
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Watt RM, Carhart RL, Gentile TC, Watt TS. Monoclonal antibodies to serum lipoproteins: their present and future use in biology and medicine. Pharmacol Ther 1985; 28:29-50. [PMID: 2414787 DOI: 10.1016/0163-7258(85)90081-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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39
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Mahley RW, Innerarity TL, Rall SC, Weisgraber KH. Plasma lipoproteins: apolipoprotein structure and function. J Lipid Res 1984. [DOI: 10.1016/s0022-2275(20)34443-6] [Citation(s) in RCA: 778] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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40
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Marcel YL, Hogue M, Weech PK, Milne RW. Characterization of antigenic determinants on human solubilized apolipoprotein B. Conformational requirements for lipids. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)39821-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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41
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LeBoeuf RC, Miller C, Shively JE, Schumaker VN, Balla MA, Lusis AJ. Human apolipoprotein B: partial amino acid sequence. FEBS Lett 1984; 170:105-8. [PMID: 6373369 DOI: 10.1016/0014-5793(84)81378-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
A successful approach has been developed for the sequencing of apolipoprotein B based upon the procedure of Cleveland et al. [(1977) J. Biol. Chem. 252, 1102-1106] involving limited proteolysis in the presence of sodium dodecyl sulfate. Staphylococcus aureus protease was employed to produce large peptides which were isolated in relatively pure form by preparative gel electrophoresis. Two peptides were partially sequenced using spinning-cup microsequencing techniques. The sequences are: Peptide R2-5, -Ala-Leu-Val-Gly-Ile-Asn- Gly-Glu-Ala-Asn-Leu-Asp-Phe-Leu-Asn-Ile-Pro-Leu-Arg-Ile-Pro-Pro- Met-Arg-(Arg)-; Peptide R3-1, -Leu-Val-Ala-Lys-Pro-Ser-Val-Ser-Val-Glu- Phe-Val-Thr-Asn-Met-Gly-Ile-Ile-Pro-Lys-Phe-Ala-Arg-. Several stretches of residues suitable for the construction of oligonucleotide probes have been identified.
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