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Rezaei F, Farhat D, Gursu G, Samnani S, Lee JY. Snapshots of ABCG1 and ABCG5/G8: A Sterol's Journey to Cross the Cellular Membranes. Int J Mol Sci 2022; 24:ijms24010484. [PMID: 36613930 PMCID: PMC9820320 DOI: 10.3390/ijms24010484] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/20/2022] [Accepted: 12/22/2022] [Indexed: 12/29/2022] Open
Abstract
The subfamily-G ATP-binding cassette (ABCG) transporters play important roles in regulating cholesterol homeostasis. Recent progress in the structural data of ABCG1 and ABCG5/G8 disclose putative sterol binding sites that suggest the possible cholesterol translocation pathway. ABCG1 and ABCG5/G8 share high similarity in the overall molecular architecture, and both transporters appear to use several unique structural motifs to facilitate cholesterol transport along this pathway, including the phenylalanine highway and the hydrophobic valve. Interestingly, ABCG5/G8 is known to transport cholesterol and phytosterols, whereas ABCG1 seems to exclusively transport cholesterol. Ligand docking analysis indeed suggests a difference in recruiting sterol molecules to the known sterol-binding sites. Here, we further discuss how the different and shared structural features are relevant to their physiological functions, and finally provide our perspective on future studies in ABCG cholesterol transporters.
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Affiliation(s)
- Fatemeh Rezaei
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Danny Farhat
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Gonca Gursu
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Biochemistry Program, Faculty of Science, University of Ottawa, Ottawa, ON K1H 6N5, Canada
| | - Sabrina Samnani
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Biochemistry Program, Faculty of Science, University of Ottawa, Ottawa, ON K1H 6N5, Canada
| | - Jyh-Yeuan Lee
- Department of Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
- Correspondence:
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2
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Examining atherosclerotic lesions in three dimensions at the nanometer scale with cryo-FIB-SEM. Proc Natl Acad Sci U S A 2022; 119:e2205475119. [PMID: 35939716 PMCID: PMC9407640 DOI: 10.1073/pnas.2205475119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We employed in a correlative manner an unconventional combination of methods, comprising cathodoluminescence, cryo-scanning electron microscopy (SEM), and cryo-focused ion beam (FIB)-SEM, to examine the volumes of thousands of cubed micrometers from rabbit atherosclerotic tissues, maintained in close-to-native conditions, with a resolution of tens of nanometers. Data from three different intralesional regions, at the media-lesion interface, in the core, and toward the lumen, were analyzed following segmentation and volume or surface representation. The media-lesion interface region is rich in cells and lipid droplets, whereas the core region is markedly richer in crystals and has lower cell density. In the three regions, thin crystals appear to be associated with intracellular or extracellular lipid droplets and multilamellar bodies. Large crystals are independently positioned in the tissue, not associated with specific cellular components. This extensive evidence strongly supports the idea that the lipid droplet surfaces and the outer membranes of multilamellar bodies play a role in cholesterol crystal nucleation and growth and that crystal formation occurs, in part, inside cells. The correlative combination of methods that allowed the direct examination of cholesterol crystals and lipid deposits in the atherosclerotic lesions may be similarly used for high-resolution examination of other tissues containing pathological or physiological cholesterol deposits.
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3
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Different Pathways of Cellular Cholesterol Efflux. Cell Biochem Biophys 2022; 80:471-481. [PMID: 35737216 DOI: 10.1007/s12013-022-01081-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 06/13/2022] [Indexed: 12/22/2022]
Abstract
Cholesterol efflux is the first and rate-limiting step of reverse cholesterol transport (RCT) from peripheric cells to the liver. The involvement of high-density lipoprotein (HDL) in RCT determines the atheroprotective properties of HDL. Cholesterol efflux from different membrane pools includes both passive and energy-dependent processes. The first type of route consists of cholesterol desorption from the cell membrane into the unstirred layer adjacent to the cell surface and diffusion in the water phase. Moreover, the selective uptake and facilitated diffusion of cholesterol and cholesteryl ester molecules through the hydrophobic tunnel in the scavenger receptor BI molecule does not require energy consumption. The second type of route includes active cholesterol export by the ATP-binding cassette transporters A1 (ABCA1) and G1 (ABCG1). Several cholesterol acceptors specifically bind cholesterol and phospholipid molecules, and cholesterol binding to the albumin molecule, which acts as a shuttle, significantly increases cholesterol movement between acceptors and red blood cells, thus functioning as a sink for cholesterol. Cholesterol and phospholipid molecules effluxed from macrophages by ABCA1 are accepted exclusively by the lipid-free apolipoprotein apoA-I, which is the major protein moiety of HDL, whereas those effluxed by ABCG1 are accepted by HDL. ABCA1- and ABCG1-mediated cholesterol transport, together with cholesterol diffusion, largely determine cholesterol turnover at the physiological level of intracellular cholesterol. However, at cholesterol overload, ABCA1-mediated efflux prevails over other routes. The exchange of apoA-I between lipid-free and lipid-associated states and the synergism of nascent and mature HDL contribute to cholesterol efflux efficiency. Moreover, extracellular cholesterol deposits and microvesicles may be involved in RCT.
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4
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El-Kenawi A, Dominguez-Viqueira W, Liu M, Awasthi S, Abraham-Miranda J, Keske A, Steiner KK, Noel L, Serna AN, Dhillon J, Gillies RJ, Yu X, Koomen JM, Yamoah K, Gatenby RA, Ruffell B. Macrophage-derived cholesterol contributes to therapeutic resistance in prostate cancer. Cancer Res 2021; 81:5477-5490. [PMID: 34301759 DOI: 10.1158/0008-5472.can-20-4028] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 06/16/2021] [Accepted: 07/21/2021] [Indexed: 11/16/2022]
Abstract
Castration-resistant prostate cancer (CRPC) is a lethal stage of disease in which androgen receptor (AR) signaling is persistent despite androgen deprivation therapy (ADT). Most studies have focused on investigating cell-autonomous alterations in CRPC, while the contributions of the tumor microenvironment are less well understood. Here we sought to determine the role of tumor-associated macrophages in CRPC, based upon their role in cancer progression and therapeutic resistance. In a syngeneic model that reflected the mutational landscape of CRPC, macrophage depletion resulted in a reduced transcriptional signature for steroid and bile acid synthesis, indicating potential perturbation of cholesterol metabolism. As cholesterol is the precursor of the five major types of steroid hormones, we hypothesized that macrophages were regulating androgen biosynthesis within the prostate tumor microenvironment. Macrophage depletion reduced androgen levels within prostate tumors and restricted androgen receptor (AR) nuclear localization in vitro and in vivo. Macrophages were also cholesterol-rich and were able to transfer cholesterol to tumor cells in vitro. AR nuclear translocation was inhibited by activation of Liver X Receptor (LXR)-β, the master regulator of cholesterol homeostasis. Consistent with these data, macrophage depletion extended survival during ADT and the presence of macrophages correlated with therapeutic resistance in patient-derived explants. Taken together, these findings support the therapeutic targeting of macrophages in CRPC.
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Affiliation(s)
- Asmaa El-Kenawi
- Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida.
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | | | - Min Liu
- Proteomics and Metabolomics Core, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Shivanshu Awasthi
- Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Julieta Abraham-Miranda
- Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Aysenur Keske
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - KayLee K Steiner
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Leenil Noel
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Amparo N Serna
- Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Jasreman Dhillon
- Department of Pathology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Robert J Gillies
- Department of Cancer Physiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Xiaoqing Yu
- Department of Biostatistics and Bioinformatics, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - John M Koomen
- Proteomics and Metabolomics Core, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
- Department of Molecular Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Kosj Yamoah
- Department of Cancer Epidemiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
- Department of Radiation Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Robert A Gatenby
- Department of Radiology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
| | - Brian Ruffell
- Department of Immunology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida.
- Department of Breast Oncology, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida
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6
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Cultured macrophages transfer surplus cholesterol into adjacent cells in the absence of serum or high-density lipoproteins. Proc Natl Acad Sci U S A 2020; 117:10476-10483. [PMID: 32354992 DOI: 10.1073/pnas.1922879117] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cholesterol-laden macrophage foam cells are a hallmark of atherosclerosis. For that reason, cholesterol metabolism in macrophages has attracted considerable scrutiny, particularly the mechanisms by which macrophages unload surplus cholesterol (a process referred to as "cholesterol efflux"). Many studies of cholesterol efflux in macrophages have focused on the role of ABC transporters in moving cholesterol onto high-density lipoproteins (HDLs), but other mechanisms for cholesterol efflux likely exist. We hypothesized that macrophages have the capacity to unload cholesterol directly onto adjacent cells. To test this hypothesis, we used methyl-β-cyclodextrin (MβCD) to load mouse peritoneal macrophages with [13C]cholesterol. We then plated the macrophages (in the absence of serum or HDL) onto smooth muscle cells (SMCs) that had been metabolically labeled with [15N]choline. After incubating the cells overnight in the absence of HDL or serum, we visualized 13C and 15N distribution by nanoscale secondary ion mass spectrometry (NanoSIMS). We observed substantial 13C enrichment in SMCs that were adjacent to [13C]cholesterol-loaded macrophages-including in cytosolic lipid droplets of SMCs. In follow-up studies, we depleted "accessible cholesterol" from the plasma membrane of [13C]cholesterol-loaded macrophages with MβCD before plating the macrophages onto the SMCs. After an overnight incubation, we again observed substantial 13C enrichment in the SMCs adjacent to macrophages. Thus, macrophages transfer cholesterol to adjacent cells in the absence of serum or HDL. We suspect that macrophages within tissues transfer cholesterol to adjacent cells, thereby contributing to the ability to unload surplus cholesterol.
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7
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van der Vorst EPC, Weber C. Novel Features of Monocytes and Macrophages in Cardiovascular Biology and Disease. Arterioscler Thromb Vasc Biol 2019; 39:e30-e37. [PMID: 30673349 DOI: 10.1161/atvbaha.118.312002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Emiel P C van der Vorst
- From the Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-Universität München, Munich, Germany (E.P.C.v.d.V., C.W.)
| | - Christian Weber
- From the Institute for Cardiovascular Prevention (IPEK), Ludwig-Maximilians-Universität München, Munich, Germany (E.P.C.v.d.V., C.W.).,DZHK (German Centre for Cardiovascular Research), partner site Munich Heart Alliance, Germany (C.W.).,Department of Biochemistry, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, the Netherlands (C.W.)
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Hu X, Weston TA, He C, Jung RS, Heizer PJ, Young BD, Tu Y, Tontonoz P, Wohlschlegel JA, Jiang H, Young SG, Fong LG. Release of cholesterol-rich particles from the macrophage plasma membrane during movement of filopodia and lamellipodia. eLife 2019; 8:50231. [PMID: 31486771 PMCID: PMC6750930 DOI: 10.7554/elife.50231] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Accepted: 09/04/2019] [Indexed: 12/12/2022] Open
Abstract
Cultured mouse peritoneal macrophages release large numbers of ~30-nm cholesterol-rich particles. Here, we show that those particles represent fragments of the plasma membrane that are pulled away and left behind during the projection and retraction of filopodia and lamellipodia. Consistent with this finding, the particles are enriched in proteins found in focal adhesions, which attach macrophages to the substrate. The release of particles is abolished by blocking cell movement (either by depolymerizing actin with latrunculin A or by inhibiting myosin II with blebbistatin). Confocal microscopy and NanoSIMS imaging studies revealed that the plasma membrane-derived particles are enriched in 'accessible cholesterol' (a mobile pool of cholesterol detectable with the modified cytolysin ALO-D4) but not in sphingolipid-sequestered cholesterol [a pool detectable with ostreolysin A (OlyA)]. The discovery that macrophages release cholesterol-rich particles during cellular locomotion is likely relevant to cholesterol efflux and could contribute to extracellular cholesterol deposition in atherosclerotic plaques.
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Affiliation(s)
- Xuchen Hu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Thomas A Weston
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Cuiwen He
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Rachel S Jung
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Patrick J Heizer
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Brian D Young
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, United States
| | - Yiping Tu
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Peter Tontonoz
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, Los Angeles, United States
| | - James A Wohlschlegel
- Department of Biological Chemistry, University of California, Los Angeles, Los Angeles, United States
| | - Haibo Jiang
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States.,School of Molecular Sciences, University of Western Australia, Perth, Australia
| | - Stephen G Young
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States.,Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
| | - Loren G Fong
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, United States
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9
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Baumer Y, McCurdy S, Jin X, Weatherby TM, Dey AK, Mehta NN, Yap JK, Kruth HS, Boisvert WA. Ultramorphological analysis of plaque advancement and cholesterol crystal formation in Ldlr knockout mouse atherosclerosis. Atherosclerosis 2019; 287:100-111. [PMID: 31247346 DOI: 10.1016/j.atherosclerosis.2019.05.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/25/2019] [Accepted: 05/29/2019] [Indexed: 01/17/2023]
Abstract
BACKGOUND AND AIMS The low-density lipoprotein receptor-deficient (Ldlr-/-) mouse has been utilized by cardiovascular researchers for more than two decades to study atherosclerosis. However, there has not yet been a systematic effort to document the ultrastructural changes that accompany the progression of atherosclerotic plaque in this model. METHODS Employing several different staining and microscopic techniques, including immunohistochemistry, as well as electron and polarized microscopy, we analyzed atherosclerotic lesion development in Ldlr-/- mice fed an atherogenic diet over time. RESULTS Lipid-like deposits occurred in the subendothelial space after only one week of atherogenic diet. At two weeks, cholesterol crystals (CC) formed and increased thereafter. Lipid, CC, vascular smooth muscles cells, and collagen progressively increased over time, while after 4 weeks, relative macrophage content decreased. Accelerated accumulation of plate- and needle-shaped CC accompanied plaque core necrosis. Lastly, CC were surrounded by cholesterol microdomains, which co-localized with CC through all stages of atherosclerosis, indicating that the cholesterol microdomains may be a source of CC. CONCLUSIONS Here, we have documented, for the first time in a comprehensive way, atherosclerotic plaque morphology and composition from early to advanced stages in the Ldlr-/- mouse, one of the most commonly used animal models utilized in atherosclerosis research.
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Affiliation(s)
- Yvonne Baumer
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo Street, Honolulu, HI, 96813, USA
| | - Sara McCurdy
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo Street, Honolulu, HI, 96813, USA
| | - Xueting Jin
- Section of Experimental Atherosclerosis, National Heart, Lung and Blood Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Tina M Weatherby
- Pacific Biosciences Research Center, Biological Electron Microscope Facility, University of Hawaii, 2538 The Mall, Snyder Hall, Honolulu, HI, 96822, USA
| | - Amit K Dey
- Section of Inflammation and Cardiometabolic Diseases, National Heart, Lung and Blood Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Nehal N Mehta
- Section of Inflammation and Cardiometabolic Diseases, National Heart, Lung and Blood Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - Jonathan K Yap
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo Street, Honolulu, HI, 96813, USA
| | - Howard S Kruth
- Section of Experimental Atherosclerosis, National Heart, Lung and Blood Institute, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD, 20892, USA
| | - William A Boisvert
- Center for Cardiovascular Research, John A. Burns School of Medicine, University of Hawaii, 651 Ilalo Street, Honolulu, HI, 96813, USA; Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russia.
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Why Is Very High Cholesterol Content Beneficial for the Eye Lens but Negative for Other Organs? Nutrients 2019; 11:nu11051083. [PMID: 31096723 PMCID: PMC6566707 DOI: 10.3390/nu11051083] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 05/08/2019] [Accepted: 05/09/2019] [Indexed: 12/13/2022] Open
Abstract
The plasma membranes of the human lens fiber cell are overloaded with cholesterol that not only saturates the phospholipid bilayer of these membranes but also leads to the formation of pure cholesterol bilayer domains. Cholesterol level increases with age, and for older persons, it exceeds the cholesterol solubility threshold, leading to the formation of cholesterol crystals. All these changes occur in the normal lens without too much compromise to lens transparency. If the cholesterol content in the cell membranes of other organs increases to extent where cholesterol crystals forma, a pathological condition begins. In arterial cells, minute cholesterol crystals activate inflammasomes, induce inflammation, and cause atherosclerosis development. In this review, we will indicate possible factors that distinguish between beneficial and negative cholesterol action, limiting cholesterol actions to those performed through cholesterol in cell membranes and by cholesterol crystals.
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11
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Varsano N, Beghi F, Dadosh T, Elad N, Pereiro E, Haran G, Leiserowitz L, Addadi L. The Effect of the Phospholipid Bilayer Environment on Cholesterol Crystal Polymorphism. Chempluschem 2019; 84:338-344. [DOI: 10.1002/cplu.201800632] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 01/10/2019] [Indexed: 12/23/2022]
Affiliation(s)
- Neta Varsano
- Department of Structural BiologyWeizmann Institute of Science 234 Herzl Street Rehovot Israel
| | - Fabio Beghi
- Department of ChemistryUniversità Degli Studi di Milano Italy
| | - Tali Dadosh
- Department of Chemical Research SupportWeizmann Institute of Science
| | - Nadav Elad
- Department of Chemical Research SupportWeizmann Institute of Science
| | - Eva Pereiro
- MISTRAL Beamline-Experiments DivisionALBA Synchrotron Light Source Cerdanyola del Valles 08290 Barcelona Spain
| | - Gilad Haran
- Department of Chemical & Biological PhysicsWeizmann Institute of Science
| | | | - Lia Addadi
- Department of Structural BiologyWeizmann Institute of Science 234 Herzl Street Rehovot Israel
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12
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Macrophages release plasma membrane-derived particles rich in accessible cholesterol. Proc Natl Acad Sci U S A 2018; 115:E8499-E8508. [PMID: 30127022 DOI: 10.1073/pnas.1810724115] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Macrophages are generally assumed to unload surplus cholesterol through direct interactions between ABC transporters on the plasma membrane and HDLs, but they have also been reported to release cholesterol-containing particles. How macrophage-derived particles are formed and released has not been clear. To understand the genesis of macrophage-derived particles, we imaged mouse macrophages by EM and nanoscale secondary ion mass spectrometry (nanoSIMS). By scanning EM, we found that large numbers of 20- to 120-nm particles are released from the fingerlike projections (filopodia) of macrophages. These particles attach to the substrate, forming a "lawn" of particles surrounding macrophages. By nanoSIMS imaging we showed that these particles are enriched in the mobile and metabolically active accessible pool of cholesterol (detectable by ALO-D4, a modified version of a cholesterol-binding cytolysin). The cholesterol content of macrophage-derived particles was increased by loading the cells with cholesterol or by adding LXR and RXR agonists to the cell-culture medium. Incubating macrophages with HDL reduced the cholesterol content of macrophage-derived particles. We propose that release of accessible cholesterol-rich particles from the macrophage plasma membrane could assist in disposing of surplus cholesterol and increase the efficiency of cholesterol movement to HDL.
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13
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Two polymorphic cholesterol monohydrate crystal structures form in macrophage culture models of atherosclerosis. Proc Natl Acad Sci U S A 2018; 115:7662-7669. [PMID: 29967179 DOI: 10.1073/pnas.1803119115] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The formation of atherosclerotic plaques in the blood vessel walls is the result of LDL particle uptake, and consequently of cholesterol accumulation in macrophage cells. Excess cholesterol accumulation eventually results in cholesterol crystal deposition, the hallmark of mature atheromas. We followed the formation of cholesterol crystals in J774A.1 macrophage cells with time, during accumulation of LDL particles, using a previously developed correlative cryosoft X-ray tomography (cryo-SXT) and stochastic optical reconstruction microscopy (STORM) technique. We show, in the initial accumulation stages, formation of small quadrilateral crystal plates associated with the cell plasma membrane, which may subsequently assemble into large aggregates. These plates match crystals of the commonly observed cholesterol monohydrate triclinic structure. Large rod-like cholesterol crystals form at a later stage in intracellular locations. Using cryotransmission electron microscopy (cryo-TEM) and cryoelectron diffraction (cryo-ED), we show that the structure of the large elongated rods corresponds to that of monoclinic cholesterol monohydrate, a recently determined polymorph of the triclinic crystal structure. These monoclinic crystals form with an unusual hollow cylinder or helical architecture, which is preserved in the mature rod-like crystals. The rod-like morphology is akin to that observed in crystals isolated from atheromas. We suggest that the crystals in the atherosclerotic plaques preserve in their morphology the memory of the structure in which they were formed. The identification of the polymorph structure, besides explaining the different crystal morphologies, may serve to elucidate mechanisms of cholesterol segregation and precipitation in atherosclerotic plaques.
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Jin X, Dimitriadis EK, Liu Y, Combs CA, Chang J, Varsano N, Stempinski E, Flores R, Jackson SN, Muller L, Woods AS, Addadi L, Kruth HS. Macrophages Shed Excess Cholesterol in Unique Extracellular Structures Containing Cholesterol Microdomains. Arterioscler Thromb Vasc Biol 2018; 38:1504-1518. [PMID: 29853567 PMCID: PMC6023747 DOI: 10.1161/atvbaha.118.311269] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Accepted: 05/16/2018] [Indexed: 12/20/2022]
Abstract
Supplemental Digital Content is available in the text. Objective— Cells use various mechanisms to maintain cellular cholesterol homeostasis including efflux of cholesterol from the cellular plasma membrane to cholesterol acceptors such as HDLs (high-density lipoproteins). Little is known about the transfer of cholesterol from cells into the extracellular matrix. Using a unique monoclonal antibody that detects ordered cholesterol arrays (ie, cholesterol micro[or nano]-domains), we previously identified that particles containing these cholesterol domains accumulate in the extracellular matrix during cholesterol enrichment of human monocyte-derived macrophages and are found in atherosclerotic lesions. In this study, we further investigate these deposited particles containing cholesterol microdomains and discover their unexpected morphology. Approach and Results— Although appearing spherical at the resolution of the conventional fluorescence microscope, super-resolution immunofluorescence and atomic force microscopy of in situ cholesterol microdomains, and immunoelectron microscopy of isolated cholesterol microdomains revealed that the microdomains are not vesicles or 3-dimensional crystals but rather appear as branching irregularly shaped deposits of varying size. These cholesterol microdomain-containing deposits are shed from the plasma membrane into the extracellular matrix. Conclusions— To date, research on cellular excretion of excess cholesterol has demonstrated cellular cholesterol efflux in the form of membranous vesicles and discoidal HDL particles released into the fluid-phase medium. Shedding of plasma membrane cholesterol microdomains provides an additional mechanism for cells such as macrophages to maintain plasma membrane cholesterol homeostasis. Furthermore, recognition that macrophages shed cholesterol microdomains into the extracellular matrix is important to our understanding of extracellular buildup of cholesterol in atherosclerosis.
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Affiliation(s)
- Xueting Jin
- From the Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute (X.J., Y.L., J.C., R.F., H.S.K.)
| | - Emilios K Dimitriadis
- Scanning Probe Microscopy Unit, National Institute of Biomedical Imaging and Bioengineering (E.K.D.)
| | - Ying Liu
- From the Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute (X.J., Y.L., J.C., R.F., H.S.K.)
| | - Christian A Combs
- Light Microscopy Core, National Heart, Lung, and Blood Institute (C.A.C.)
| | - Janet Chang
- From the Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute (X.J., Y.L., J.C., R.F., H.S.K.)
| | - Neta Varsano
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (N.V., L.A.)
| | - Erin Stempinski
- Electron Microscopy Core, National Heart, Lung, and Blood Institute (E.S.)
| | - Rhonda Flores
- From the Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute (X.J., Y.L., J.C., R.F., H.S.K.)
| | - Shelley N Jackson
- Structural Biology Core, National Institute of Drug Abuse (S.N.J., L.M., A.S.W.), National Institutes of Health, Baltimore, MD
| | - Ludovic Muller
- Structural Biology Core, National Institute of Drug Abuse (S.N.J., L.M., A.S.W.), National Institutes of Health, Baltimore, MD
| | - Amina S Woods
- Structural Biology Core, National Institute of Drug Abuse (S.N.J., L.M., A.S.W.), National Institutes of Health, Baltimore, MD
| | - Lia Addadi
- Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (N.V., L.A.)
| | - Howard S Kruth
- From the Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute (X.J., Y.L., J.C., R.F., H.S.K.)
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15
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Varsano N, Dadosh T, Kapishnikov S, Pereiro E, Shimoni E, Jin X, Kruth HS, Leiserowitz L, Addadi L. Development of Correlative Cryo-soft X-ray Tomography and Stochastic Reconstruction Microscopy. A Study of Cholesterol Crystal Early Formation in Cells. J Am Chem Soc 2016; 138:14931-14940. [PMID: 27934213 DOI: 10.1021/jacs.6b07584] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
We have developed a high resolution correlative method involving cryo-soft X-ray tomography (cryo-SXT) and stochastic optical reconstruction microscopy (STORM), which provides information in three dimensions on large cellular volumes at 70 nm resolution. Cryo-SXT morphologically identified and localized aggregations of carbon-rich materials. STORM identified specific markers on the desired epitopes, enabling colocalization between the identified objects, in this case cholesterol crystals, and the cellular environment. The samples were studied under ambient and cryogenic conditions without dehydration or heavy metal staining. The early events of cholesterol crystal development were investigated in relation to atherosclerosis, using as model macrophage cell cultures enriched with LDL particles. Atherosclerotic plaques build up in arteries in a slow process involving cholesterol crystal accumulation. Cholesterol crystal deposition is a crucial stage in the pathological cascade. Our results show that cholesterol crystals can be identified and imaged at a very early stage on the cell plasma membrane and in intracellular locations. This technique can in principle be applied to other biological samples where specific molecular identification is required in conjunction with high resolution 3D-imaging.
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Affiliation(s)
| | | | - Sergey Kapishnikov
- Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin , Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Eva Pereiro
- ALBA Synchrotron Light Source, MISTRAL Beamline-Experiments Division, 08290 Cerdanyola del Valles, Barcelona, Spain
| | | | - Xueting Jin
- Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892-1422, United States
| | - Howard S Kruth
- Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute, National Institutes of Health , Bethesda, Maryland 20892-1422, United States
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16
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Jin X, Sviridov D, Liu Y, Vaisman B, Addadi L, Remaley AT, Kruth HS. ABCA1 (ATP-Binding Cassette Transporter A1) Mediates ApoA-I (Apolipoprotein A-I) and ApoA-I Mimetic Peptide Mobilization of Extracellular Cholesterol Microdomains Deposited by Macrophages. Arterioscler Thromb Vasc Biol 2016; 36:2283-2291. [PMID: 27758769 DOI: 10.1161/atvbaha.116.308334] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 09/02/2016] [Indexed: 11/16/2022]
Abstract
OBJECTIVE We examined the function of ABCA1 (ATP-binding cassette transporter A1) in ApoA-I (apolipoprotein A-I) mobilization of cholesterol microdomains deposited into the extracellular matrix by cholesterol-enriched macrophages. We have also determined whether an ApoA-I mimetic peptide without and with complexing to sphingomyelin can mobilize macrophage-deposited cholesterol microdomains. APPROACH AND RESULTS Extracellular cholesterol microdomains deposited by cholesterol-enriched macrophages were detected with a monoclonal antibody, 58B1. ApoA-I and an ApoA-I mimetic peptide 5A mobilized cholesterol microdomains deposited by ABCA1+/+ macrophages but not by ABCA1-/- macrophages. In contrast, ApoA-I mimetic peptide 5A complexed with sphingomyelin could mobilize cholesterol microdomains deposited by ABCA1-/- macrophages. CONCLUSIONS Our findings show that a unique pool of extracellular cholesterol microdomains deposited by macrophages can be mobilized by both ApoA-I and an ApoA-I mimetic peptide but that mobilization depends on macrophage ABCA1. It is known that ABCA1 complexes ApoA-I and ApoA-I mimetic peptide with phospholipid, a cholesterol-solubilizing agent, explaining the requirement for ABCA1 in extracellular cholesterol microdomain mobilization. Importantly, ApoA-I mimetic peptide already complexed with phospholipid can mobilize macrophage-deposited extracellular cholesterol microdomains even in the absence of ABCA1.
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Affiliation(s)
- Xueting Jin
- From the Experimental Atherosclerosis Section (X.J., Y.L., H.S.K.) and Lipoprotein Metabolism Section (D.S., B.V., A.T.R.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (L.A.)
| | - Denis Sviridov
- From the Experimental Atherosclerosis Section (X.J., Y.L., H.S.K.) and Lipoprotein Metabolism Section (D.S., B.V., A.T.R.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (L.A.)
| | - Ying Liu
- From the Experimental Atherosclerosis Section (X.J., Y.L., H.S.K.) and Lipoprotein Metabolism Section (D.S., B.V., A.T.R.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (L.A.)
| | - Boris Vaisman
- From the Experimental Atherosclerosis Section (X.J., Y.L., H.S.K.) and Lipoprotein Metabolism Section (D.S., B.V., A.T.R.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (L.A.)
| | - Lia Addadi
- From the Experimental Atherosclerosis Section (X.J., Y.L., H.S.K.) and Lipoprotein Metabolism Section (D.S., B.V., A.T.R.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (L.A.)
| | - Alan T Remaley
- From the Experimental Atherosclerosis Section (X.J., Y.L., H.S.K.) and Lipoprotein Metabolism Section (D.S., B.V., A.T.R.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (L.A.)
| | - Howard S Kruth
- From the Experimental Atherosclerosis Section (X.J., Y.L., H.S.K.) and Lipoprotein Metabolism Section (D.S., B.V., A.T.R.), National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD; and Department of Structural Biology, Weizmann Institute of Science, Rehovot, Israel (L.A.).
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17
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Jin X, Kruth HS. Culture of Macrophage Colony-stimulating Factor Differentiated Human Monocyte-derived Macrophages. J Vis Exp 2016. [PMID: 27404952 DOI: 10.3791/54244] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
A protocol is presented for cell culture of macrophage colony-stimulating factor (M-CSF) differentiated human monocyte-derived macrophages. For initiation of experiments, fresh or frozen monocytes are cultured in flasks for 1 week with M-CSF to induce their differentiation into macrophages. Then, the macrophages can be harvested and seeded into culture wells at required cell densities for carrying out experiments. The use of defined numbers of macrophages rather than defined numbers of monocytes to initiate macrophage cultures for experiments yields macrophage cultures in which the desired cell density can be more consistently attained. Use of cryopreserved monocytes reduces dependency on donor availability and produces more homogeneous macrophage cultures.
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Affiliation(s)
- Xueting Jin
- Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute, National Institutes of Health
| | - Howard S Kruth
- Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute, National Institutes of Health;
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18
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High-density lipoprotein-mediated transcellular cholesterol transport in mouse aortic endothelial cells. Biochem Biophys Res Commun 2015; 465:256-61. [PMID: 26255968 DOI: 10.1016/j.bbrc.2015.08.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 08/03/2015] [Indexed: 01/26/2023]
Abstract
Accumulation of unesterified cholesterol-rich lipid vesicles in the subendothelial space contributes to atherogenesis. Transport of cholesterol from the subendothelial intima back to the circulating blood inhibits atherosclerosis development; however, the mechanism for this process has not been fully defined. Using cultured mouse aortic endothelial cells (MAECs), we observed that unesterified cholesterol can be transported across the endothelial cell monolayer from the basolateral to the apical compartment. Administration of high-density lipoprotein (HDL) or apolipoprotein AI (apoAI) to the apical compartment enhanced transendothelial cholesterol transport in a concentration-dependent manner. Knockdown of ATP-binding cassette transporter G1 (ABCG1) or scavenger receptor class B type I (SR-B1), or inhibition of SR-B1 diminished HDL-induced transendothelial cholesterol transport; while knockdown of ABCA1 reduced apoAI-mediated cholesterol transport. HDL enhanced phosphorylation of phosphatidylinositol 3-kinase (PI3K) and Akt in MAECs. However, inhibition of PI3K or Akt did not reduce HDL-induced transendothelial cholesterol transport. These results suggest that HDL enhances transendothelial cholesterol transport by activation of a mechanism involving ABCA1, ABCG1 and SR-B1 but not involving PI3K and Akt.
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19
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Jin X, Freeman SR, Vaisman B, Liu Y, Chang J, Varsano N, Addadi L, Remaley A, Kruth HS. ABCA1 contributes to macrophage deposition of extracellular cholesterol. J Lipid Res 2015. [PMID: 26203076 DOI: 10.1194/jlr.m060053] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We previously reported that cholesterol-enriched macrophages excrete cholesterol into the extracellular matrix. A monoclonal antibody that detects cholesterol microdomains labels the deposited extracellular particles. Macro-phage deposition of extracellular cholesterol depends, in part, on ABCG1, and this cholesterol can be mobilized by HDL components of the reverse cholesterol transport process. The objective of the current study was to determine whether ABCA1 also contributes to macrophage deposition of extracellular cholesterol. ABCA1 functioned in extracellular cholesterol deposition. The liver X receptor agonist, TO901317 (TO9), an ABCA1-inducing factor, restored cholesterol deposition that was absent in cholesterol-enriched ABCG1(-/-) mouse macrophages. In addition, the ABCA1 inhibitor, probucol, blocked the increment in cholesterol deposited by TO9-treated wild-type macrophages, and completely inhibited deposition from TO9-treated ABCG1(-/-) macrophages. Lastly, ABCA1(-/-) macrophages deposited much less extracellular cholesterol than wild-type macrophages. These findings demonstrate a novel function of ABCA1 in contributing to macrophage export of cholesterol into the extracellular matrix.
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Affiliation(s)
- Xueting Jin
- Section of Experimental Atherosclerosis National Institutes of Health, Bethesda, MD 20892
| | - Sebastian R Freeman
- Section of Experimental Atherosclerosis National Institutes of Health, Bethesda, MD 20892
| | - Boris Vaisman
- Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Ying Liu
- Section of Experimental Atherosclerosis National Institutes of Health, Bethesda, MD 20892
| | - Janet Chang
- Section of Experimental Atherosclerosis National Institutes of Health, Bethesda, MD 20892
| | - Neta Varsano
- Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Lia Addadi
- Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot, Israel
| | - Alan Remaley
- Lipoprotein Metabolism Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Howard S Kruth
- Section of Experimental Atherosclerosis National Institutes of Health, Bethesda, MD 20892
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20
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Varsano N, Fargion I, Wolf SG, Leiserowitz L, Addadi L. Formation of 3D Cholesterol Crystals from 2D Nucleation Sites in Lipid Bilayer Membranes: Implications for Atherosclerosis. J Am Chem Soc 2015; 137:1601-7. [DOI: 10.1021/ja511642t] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Affiliation(s)
- Neta Varsano
- Department
of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Iael Fargion
- Department
of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sharon G. Wolf
- Department
of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Leslie Leiserowitz
- Department
of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Lia Addadi
- Department
of Structural Biology, Weizmann Institute of Science, Rehovot 76100, Israel
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21
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Lipidomics: Potential role in risk prediction and therapeutic monitoring for diabetes and cardiovascular disease. Pharmacol Ther 2014; 143:12-23. [DOI: 10.1016/j.pharmthera.2014.02.001] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 01/27/2014] [Indexed: 01/07/2023]
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22
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Alsop RJ, Barrett MA, Zheng S, Dies H, Rheinstädter MC. Acetylsalicylic acid (ASA) increases the solubility of cholesterol when incorporated in lipid membranes. SOFT MATTER 2014; 10:4275-4286. [PMID: 24789086 DOI: 10.1039/c4sm00372a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Cholesterol has been well established as a mediator of cell membrane fluidity. By interacting with lipid tails, cholesterol causes the membrane tails to be constrained thereby reducing membrane fluidity, well known as the condensation effect. Acetylsalicylic acid (ASA), the main ingredient in aspirin, has recently been shown to increase fluidity in lipid bilayers by primarily interacting with lipid head groups. We used high-resolution X-ray diffraction to study both ASA and cholesterol coexisting in model membranes of dimyristoylphosphatidylcholine (DMPC). While a high cholesterol concentration of 40 mol% cholesterol leads to the formation of immiscible cholesterol bilayers, as was reported previously, increasing the amount of ASA in the membranes between 0 to 12.5 mol% was found to significantly increase the fluidity of the bilayers and dissolve the cholesterol plaques. We, therefore, present experimental evidence for an interaction between cholesterol and ASA on the level of the cell membrane at elevated levels of cholesterol and ASA.
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Affiliation(s)
- Richard J Alsop
- Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada
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23
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Camejo G, Hurt-Camejo E. Macrophages, extracellular matrix, and lipoproteins in arterial cholesterol balance. J Lipid Res 2013; 55:1-3. [PMID: 24253373 DOI: 10.1194/jlr.e045732] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Germán Camejo
- Cardiovascular and Metabolic Diseases, AstraZeneca, Mölndal, 431 83, Sweden
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24
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Freeman SR, Jin X, Anzinger JJ, Xu Q, Purushothaman S, Fessler MB, Addadi L, Kruth HS. ABCG1-mediated generation of extracellular cholesterol microdomains. J Lipid Res 2013; 55:115-27. [PMID: 24212237 DOI: 10.1194/jlr.m044552] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Previous studies have demonstrated that the ATP-binding cassette transporters (ABC)A1 and ABCG1 function in many aspects of cholesterol efflux from macrophages. In this current study, we continued our investigation of extracellular cholesterol microdomains that form during enrichment of macrophages with cholesterol. Human monocyte-derived macrophages and mouse bone marrow-derived macrophages, differentiated with macrophage colony-stimulating factor (M-CSF) or granulocyte macrophage colony-stimulation factor (GM-CSF), were incubated with acetylated LDL (AcLDL) to allow for cholesterol enrichment and processing. We utilized an anti-cholesterol microdomain monoclonal antibody to reveal pools of unesterified cholesterol, which were found both in the extracellular matrix and associated with the cell surface, that we show function in reverse cholesterol transport. Coincubation of AcLDL with 50 μg/ml apoA-I eliminated all extracellular and cell surface-associated cholesterol microdomains, while coincubation with the same concentration of HDL only removed extracellular matrix-associated cholesterol microdomains. Only at an HDL concentration of 200 µg/ml did HDL eliminate the cholesterol microdomains that were cell-surface associated. The deposition of cholesterol microdomains was inhibited by probucol, but it was increased by the liver X receptor (LXR) agonist TO901317, which upregulates ABCA1 and ABCG1. Extracellular cholesterol microdomains did not develop when ABCG1-deficient mouse bone marrow-derived macrophages were enriched with cholesterol. Our findings show that generation of extracellular cholesterol microdomains is mediated by ABCG1 and that reverse cholesterol transport occurs not only at the cell surface but also within the extracellular space.
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Affiliation(s)
- Sebastian R Freeman
- Section of Experimental Atherosclerosis, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
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25
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Ziblat R, Fargion I, Leiserowitz L, Addadi L. Spontaneous formation of two-dimensional and three-dimensional cholesterol crystals in single hydrated lipid bilayers. Biophys J 2012; 103:255-64. [PMID: 22853903 DOI: 10.1016/j.bpj.2012.05.025] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2012] [Revised: 04/24/2012] [Accepted: 05/16/2012] [Indexed: 01/23/2023] Open
Abstract
Grazing incidence x-ray diffraction measurements were performed on single hydrated bilayers and monolayers of Ceramide/Cholesterol/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocyholine at varying concentrations. There are substantial differences in the phase and structure behavior of the crystalline domains formed within the bilayers relative to the corresponding monolayers, due to interactions between the opposing lipid leaflets. Depending on the lipid composition, these interactions lead to phase separation and formation of cholesterol crystals. The cholesterol and ceramide/cholesterol mixed phases were further characterized at 37°C by immunolabeling with specific antibodies recognizing ordered molecular arrays of cholesterol. Previous studies have shown that cholesterol may nucleate in artificial membranes to form thick two-dimensional bilayer crystals. The study herein demonstrates further growth of cholesterol into three-dimensional crystals. We believe that these results may provide further insight into the formation of cholesterol crystals in early stages of atherosclerosis inflammation.
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Affiliation(s)
- Roy Ziblat
- WYSS Institute for Biologically Inspired Engineering, Harvard University, Cambridge, Massachusetts, USA.
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26
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Ziblat R, Leiserowitz L, Addadi L. Kristalline Lipiddomänen: Charakterisierung durch Röntgenbeugung und ihre Rolle in der Biologie. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201004470] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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27
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Ziblat R, Leiserowitz L, Addadi L. Crystalline lipid domains: characterization by X-ray diffraction and their relation to biology. Angew Chem Int Ed Engl 2011; 50:3620-9. [PMID: 21472900 DOI: 10.1002/anie.201004470] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Indexed: 12/29/2022]
Abstract
Biological membranes comprise thousands of different lipids, differing in their alkyl chains, headgroups, and degree of saturation. It is estimated that 5% of the genes in the human genome are responsible for regulating the lipid composition of cell membranes. Conceivably, the functional explanation for this diversity is found, at least in part, in the propensity of lipids to segregate into distinct domains, which are important for cell function. X-ray diffraction has been used increasingly to characterize the packing and phase behavior of lipids in membranes. Crystalline domains have been studied in synthetic membranes using wide- and small-angle X-ray scattering, and grazing incidence X-ray diffraction. Herein we summarize recent results obtained using the various X-ray methods, discuss the correlation between crystalline domains and liquid ordered domains studied with other techniques, and the relevance of crystalline domains to functional lipid domains in biological membranes.
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Affiliation(s)
- Roy Ziblat
- Department of Structural Biology, Weizmann Institute of Science, 76100 Rehovot, Israel
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