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Petrisková L, Kodedová M, Balážová M, Sychrová H, Valachovič M. Lipid droplets control the negative effect of non-yeast sterols in membranes of Saccharomyces cerevisiae under hypoxic stress. Biochim Biophys Acta Mol Cell Biol Lipids 2024; 1869:159523. [PMID: 38866087 DOI: 10.1016/j.bbalip.2024.159523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 05/13/2024] [Accepted: 06/06/2024] [Indexed: 06/14/2024]
Abstract
The effectivity of utilization of exogenous sterols in the yeast Saccharomyces cerevisiae exposed to hypoxic stress is dependent on the sterol structure. The highly imported sterols include animal cholesterol or plant sitosterol, while ergosterol, typical of yeasts, is imported to a lesser extent. An elevated utilization of non-yeast sterols is associated with their high esterification and relocalization to lipid droplets (LDs). Here we present data showing that LDs and sterol esterification play a critical role in the regulation of the accumulation of non-yeast sterols in membranes. Failure to form LDs during anaerobic growth in media supplemented with cholesterol or sitosterol resulted in an extremely long lag phase, in contrast to normal growth in media with ergosterol or plant stigmasterol. Moreover, in hem1∆, which mimics anaerobiosis, neither cholesterol nor sitosterol supported the growth in an LD-less background. The incorporation of non-ergosterol sterols into the membranes affected fundamental membrane characteristics such as relative membrane potential, permeability, tolerance to osmotic stress and the formation of membrane domains. Our findings reveal that LDs assume an important role in scenarios wherein cells are dependent on the utilization of exogenous lipids, particularly under anoxia. Given the diverse lipid structures present in yeast niches, LDs fulfil a protective role, mitigating the risk of excessive accumulation of potentially toxic steroids and fatty acids in the membranes. Finally, we present a novel function for sterols in a model eukaryotic cell - alleviation of the lipotoxicity of unsaturated fatty acids.
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Affiliation(s)
- Lívia Petrisková
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Marie Kodedová
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Mária Balážová
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Hana Sychrová
- Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Martin Valachovič
- Institute of Animal Biochemistry and Genetics, Centre of Biosciences, Slovak Academy of Sciences, Bratislava, Slovakia.
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2
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Bydlowski SP, Levy D. Association of ABCG5 and ABCG8 Transporters with Sitosterolemia. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1440:31-42. [PMID: 38036873 DOI: 10.1007/978-3-031-43883-7_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Sitosterolemia is a rare genetic lipid disorder, mainly characterized by the accumulation of dietary xenosterols in plasma and tissues. It is caused by inactivating mutations in either ABCG5 or ABCG8 subunits, a subfamily-G ATP-binding cassette (ABCG) transporters. ABCG5/G8 encodes a pair of ABC half transporters that form a heterodimer (G5G8). This heterodimeric ATP-binding cassette (ABC) sterol transporter, ABCG5/G8, is responsible for the hepatobiliary and transintestinal secretion of cholesterol and dietary plant sterols to the surface of hepatocytes and enterocytes, promoting the secretion of cholesterol and xenosterols into the bile and the intestinal lumen. In this way, ABCG5/G8 function in the reverse cholesterol transport pathway and mediate the efflux of cholesterol and xenosterols to high-density lipoprotein and bile salt micelles, respectively. Here, we review the biological characteristics and function of ABCG5/G8, and how the mutations of ABCG5/G8 can cause sitosterolemia, a loss-of-function disorder characterized by plant sterol accumulation and premature atherosclerosis, among other features.
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Affiliation(s)
- Sergio Paulo Bydlowski
- Lipids, Oxidation and Cell Biology Team, Laboratory of Immunology (LIM19), Heart Institute (InCor), Faculdade de Medicina, Universidade de São Paulo, Sao Paulo, Brazil.
- National Institute of Science and Technology in Regenerative Medicine (INCT-Regenera) CNPq, Rio de Janeiro, Brazil.
| | - Debora Levy
- Lipids, Oxidation and Cell Biology Team, Laboratory of Immunology (LIM19), Heart Institute (InCor), Faculdade de Medicina, Universidade de São Paulo, Sao Paulo, Brazil
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3
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Wang Y, Khalil A, Kamar A, Du M, Dinh T, McFarland C, Wang Z. Unveiling immune checkpoint regulation: exploring the power of in vivo CRISPR screenings in cancer immunotherapy. Front Genet 2023; 14:1304425. [PMID: 38162677 PMCID: PMC10755878 DOI: 10.3389/fgene.2023.1304425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Accepted: 11/27/2023] [Indexed: 01/03/2024] Open
Abstract
Immune checkpoint inhibitors (ICIs) have revolutionized cancer immunotherapy by reinvigorating antitumor immune responses, but their efficacy remains limited in most patients. To address this challenge and optimize Immune check inhibitor treatment, understanding the underlying molecular intricacies involved is crucial. The emergence of CRISPR-Cas9 technology has empowered researchers to precisely investigate gene function and has introduced transformative shifts in identifying key genes for various physiological and pathological processes. CRISPR screenings, particularly in vivo CRISPR screenings, have become invaluable tools in deciphering molecular networks and signaling pathways governing suppressive immune checkpoint molecules. In this review, we provide a comprehensive overview of in vivo CRISPR screenings in cancer immunotherapy, exploring how this cutting-edge technology has unraveled potential novel therapeutic targets and combination strategies. We delve into the latest findings and advancements, shedding light on immune checkpoint regulation and offering exciting prospects for the development of innovative and effective treatments for cancer patients.
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Affiliation(s)
- Yuxiang Wang
- Department of Genetics and Genome Sciences and Case Comprehesive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
| | - Athar Khalil
- Department of Genetics and Genome Sciences and Case Comprehesive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
| | - Amina Kamar
- Centre for Digital Transformation, Imperial College, London, United Kingdom
| | - Mengyan Du
- Department of Genetics and Genome Sciences and Case Comprehesive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
| | - Trang Dinh
- Department of Genetics and Genome Sciences and Case Comprehesive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
| | - Christopher McFarland
- Department of Genetics and Genome Sciences and Case Comprehesive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
| | - Zhenghe Wang
- Department of Genetics and Genome Sciences and Case Comprehesive Cancer Center, Case Western Reserve University, Cleveland, OH, United States
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4
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Windler E, Beil FU, Berthold HK, Gouni-Berthold I, Kassner U, Klose G, Lorkowski S, März W, Parhofer KG, Plat J, Silbernagel G, Steinhagen-Thiessen E, Weingärtner O, Zyriax BC, Lütjohann D. Phytosterols and Cardiovascular Risk Evaluated against the Background of Phytosterolemia Cases-A German Expert Panel Statement. Nutrients 2023; 15:nu15040828. [PMID: 36839186 PMCID: PMC9963617 DOI: 10.3390/nu15040828] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2022] [Revised: 01/23/2023] [Accepted: 01/25/2023] [Indexed: 02/08/2023] Open
Abstract
Phytosterols (PSs) have been proposed as dietary means to lower plasma LDL-C. However, concerns are raised that PSs may exert atherogenic effects, which would offset this benefit. Phytosterolemia was thought to mimic increased plasma PSs observed after the consumption of PS-enriched foods. This expert statement examines the possibility of specific atherogenicity of PSs based on sterol metabolism, experimental, animal, and human data. Observational studies show no evidence that plasma PS concentrations would be associated with an increased risk of atherosclerosis or cardiovascular (CV) events. Since variants of the ABCG5/8 transporter affect the absorption of cholesterol and non-cholesterol sterols, Mendelian randomization studies examining the effects of ABCG5/8 polymorphisms cannot support or refute the potential atherogenic effects of PSs due to pleiotropy. In homozygous patients with phytosterolemia, total PS concentrations are ~4000% higher than under physiological conditions. The prevalence of atherosclerosis in these individuals is variable and may mainly relate to concomitant elevated LDL-C. Consuming PS-enriched foods increases PS concentrations by ~35%. Hence, PSs, on a molar basis, would need to have 20-40 times higher atherogenicity than cholesterol to offset their cholesterol reduction benefit. Based on their LDL-C lowering and absence of adverse safety signals, PSs offer a dietary approach to cholesterol management. However, their clinical benefits have not been established in long-term CV endpoint studies.
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Affiliation(s)
- Eberhard Windler
- Preventive Medicine, University Heart Center, University Hospital Hamburg-Eppendorf, Hamburg-Eppendorf, Martinistr. 52-Bldg. N26, 20246 Hamburg, Germany
| | - Frank-Ulrich Beil
- Ambulanzzentrum, Universitätsklinikum Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Heiner K. Berthold
- Department of Internal Medicine and Geriatrics, Bethel Clinic, 33611 Bielefeld, Germany
| | - Ioanna Gouni-Berthold
- Center for Endocrinology, Diabetes and Preventive Medicine, Faculty of Medicine and University Hospital Cologne, University of Cologne, Kerpener Str. 62, 50937 Cologne, Germany
| | - Ursula Kassner
- Lipid Clinic at the Interdisciplinary Metabolism Center, Charite-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Gerald Klose
- Praxen Dres. T. Beckenbauer & S. Maierhof, Am Markt 11, 28195 Bremen und Dres. I. van de Loo & K. Spieker, Gerold Janssen Straße 2 A, 28359 Bremen, Germany
| | - Stefan Lorkowski
- Institute of Nutritional Science and Competence Cluster for Nutrition and Cardiovascular Health (nutriCARD), Halle-Jena-Leipzig, Friedrich Schiller University Jena, Dornburger Str. 25, 07743 Jena, Germany
| | - Winfried März
- SYNLAB Akademie für Ärztliche Fortbildung, SYNLAB Holding Deutschland GmbH, P5,7, 68161 Mannheim, Germany
- Medical Clinic V, Medical Faculty Mannheim, University of Heidelberg, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, 8010 Graz, Austria
- Correspondence:
| | - Klaus G. Parhofer
- Medizinische Klinik IV, Klinikum der Universität München, Grosshadern, Marchioninistr. 15, 81377 München, Germany
| | - Jogchum Plat
- Department of Nutrition and Movement Sciences, School of Nutrition and Translational Research in Metabolism (NUTRIM), Maastricht University, 6211 LK Maastricht, The Netherlands
| | - Günter Silbernagel
- Division of Vascular Medicine, Department of Internal Medicine, Medical University of Graz, 8010 Graz, Austria
| | - Elisabeth Steinhagen-Thiessen
- Arbeitsbereich Lipidstoffwechsel der Medizinischen Klinik für Endokrinologie und Stoffwechselmedizin, Charité—Universitätsmedizin Berlin, Augustenburger Platz 1, 13353 Berlin, Germany
| | - Oliver Weingärtner
- Klinik für Innere Medizin I, Universitätskliniken Jena, Friedrich-Schiller-Universität Jena, 07743 Jena, Germany
| | - Birgit-Christiane Zyriax
- Midwifery Science—Health Care Research and Prevention, Research Group, Preventive Medicine and Nutrition, Institute for Health Services Research in Dermatology and Nursing (IVDP), University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246 Hamburg, Germany
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Clinics Bonn, 53127 Bonn, Germany
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5
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Tada H, Kojima N, Takamura M, Kawashiri MA. Sitosterolemia. Adv Clin Chem 2022; 110:145-169. [DOI: 10.1016/bs.acc.2022.06.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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Abstract
Purpose of Review Coronary heart disease is the leading cause of mortality worldwide. Elevated blood cholesterol levels are not only the major but also the best modifiable cardiovascular risk factor. Lifestyle modifications which include a healthy diet are the cornerstone of lipid-lowering therapy. So-called functional foods supplemented with plant sterols lower blood cholesterol levels by about 10–15%. Recent Findings In the recent revision of the ESC/EAS dyslipidemia guideline 2019, plant sterols are recommended for the first time as an adjunct to lifestyle modification to lower blood cholesterol levels. However, the German Cardiac Society (DGK) is more critical of food supplementation with plant sterols and calls for randomized controlled trials investigating hard cardiovascular outcomes. An increasing body of evidence suggests that plant sterols per se are atherogenic. Summary This review discusses this controversy based on findings from in vitro and in vivo studies, clinical trials, and genetic evidence.
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Affiliation(s)
- Umidakhon Makhmudova
- Klinik Für Innere Medizin I, Universitätsklinikum Jena, Am Klinikum 1, 07747 Jena, Germany
| | - P. Christian Schulze
- Klinik Für Innere Medizin I, Universitätsklinikum Jena, Am Klinikum 1, 07747 Jena, Germany
| | - Dieter Lütjohann
- Institut für klinische Chemie und klinische Pharmakologie, Universitätsklinikum Bonn, Bonn, Germany
| | - Oliver Weingärtner
- Klinik Für Innere Medizin I, Universitätsklinikum Jena, Am Klinikum 1, 07747 Jena, Germany
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7
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Khunweeraphong N, Kuchler K. Multidrug Resistance in Mammals and Fungi-From MDR to PDR: A Rocky Road from Atomic Structures to Transport Mechanisms. Int J Mol Sci 2021; 22:4806. [PMID: 33946618 PMCID: PMC8124828 DOI: 10.3390/ijms22094806] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/27/2021] [Accepted: 04/28/2021] [Indexed: 12/19/2022] Open
Abstract
Multidrug resistance (MDR) can be a serious complication for the treatment of cancer as well as for microbial and parasitic infections. Dysregulated overexpression of several members of the ATP-binding cassette transporter families have been intimately linked to MDR phenomena. Three paradigm ABC transporter members, ABCB1 (P-gp), ABCC1 (MRP1) and ABCG2 (BCRP) appear to act as brothers in arms in promoting or causing MDR in a variety of therapeutic cancer settings. However, their molecular mechanisms of action, the basis for their broad and overlapping substrate selectivity, remains ill-posed. The rapidly increasing numbers of high-resolution atomic structures from X-ray crystallography or cryo-EM of mammalian ABC multidrug transporters initiated a new era towards a better understanding of structure-function relationships, and for the dynamics and mechanisms driving their transport cycles. In addition, the atomic structures offered new evolutionary perspectives in cases where transport systems have been structurally conserved from bacteria to humans, including the pleiotropic drug resistance (PDR) family in fungal pathogens for which high resolution structures are as yet unavailable. In this review, we will focus the discussion on comparative mechanisms of mammalian ABCG and fungal PDR transporters, owing to their close evolutionary relationships. In fact, the atomic structures of ABCG2 offer excellent models for a better understanding of fungal PDR transporters. Based on comparative structural models of ABCG transporters and fungal PDRs, we propose closely related or even conserved catalytic cycles, thus offering new therapeutic perspectives for preventing MDR in infectious disease settings.
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Affiliation(s)
| | - Karl Kuchler
- Center for Medical Biochemistry, Max Perutz Labs Vienna, Campus Vienna Biocenter, Medical University of Vienna, Dr. Bohr-Gasse 9/2, A-1030 Vienna, Austria;
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8
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Williams K, Segard A, Graf GA. Sitosterolemia: Twenty Years of Discovery of the Function of ABCG5ABCG8. Int J Mol Sci 2021; 22:2641. [PMID: 33807969 PMCID: PMC7961684 DOI: 10.3390/ijms22052641] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/19/2021] [Accepted: 02/26/2021] [Indexed: 02/06/2023] Open
Abstract
Sitosterolemia is a lipid disorder characterized by the accumulation of dietary xenosterols in plasma and tissues caused by mutations in either ABCG5 or ABCG8. ABCG5 ABCG8 encodes a pair of ABC half transporters that form a heterodimer (G5G8), which then traffics to the surface of hepatocytes and enterocytes and promotes the secretion of cholesterol and xenosterols into the bile and the intestinal lumen. We review the literature from the initial description of the disease, the discovery of its genetic basis, current therapy, and what has been learned from animal, cellular, and molecular investigations of the transporter in the twenty years since its discovery. The genomic era has revealed that there are far more carriers of loss of function mutations and likely pathogenic variants of ABCG5 ABCG8 than previously thought. The impact of these variants on G5G8 structure and activity are largely unknown. We propose a classification system for ABCG5 ABCG8 mutants based on previously published systems for diseases caused by defects in ABC transporters. This system establishes a framework for the comprehensive analysis of disease-associated variants and their impact on G5G8 structure-function.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 5/genetics
- ATP Binding Cassette Transporter, Subfamily G, Member 5/history
- ATP Binding Cassette Transporter, Subfamily G, Member 5/metabolism
- ATP Binding Cassette Transporter, Subfamily G, Member 8/genetics
- ATP Binding Cassette Transporter, Subfamily G, Member 8/history
- ATP Binding Cassette Transporter, Subfamily G, Member 8/metabolism
- Animals
- Cholesterol/metabolism
- Enterocytes/metabolism
- Enterocytes/pathology
- Hepatocytes/metabolism
- Hepatocytes/pathology
- History, 21st Century
- Humans
- Hypercholesterolemia/genetics
- Hypercholesterolemia/history
- Hypercholesterolemia/metabolism
- Hypercholesterolemia/pathology
- Intestinal Diseases/genetics
- Intestinal Diseases/history
- Intestinal Diseases/metabolism
- Intestinal Diseases/pathology
- Lipid Metabolism, Inborn Errors/genetics
- Lipid Metabolism, Inborn Errors/history
- Lipid Metabolism, Inborn Errors/metabolism
- Lipid Metabolism, Inborn Errors/pathology
- Lipoproteins/genetics
- Lipoproteins/history
- Lipoproteins/metabolism
- Mutation
- Phytosterols/adverse effects
- Phytosterols/genetics
- Phytosterols/history
- Phytosterols/metabolism
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Affiliation(s)
- Kori Williams
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA; (K.W.); (A.S.)
| | - Allison Segard
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA; (K.W.); (A.S.)
| | - Gregory A. Graf
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, KY 40536, USA; (K.W.); (A.S.)
- Saha Cardiovascular Research Center, Lexington, KY 40536, USA
- Barnstable Brown Diabetes and Obesity Center, Lexington, KY 40536, USA
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9
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Feng S, Wang L, Shao P, Sun P, Yang CS. A review on chemical and physical modifications of phytosterols and their influence on bioavailability and safety. Crit Rev Food Sci Nutr 2021; 62:5638-5657. [PMID: 33612007 DOI: 10.1080/10408398.2021.1888692] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Phytosterols have been shown to lower cholesterol levels and to have antioxidant, anti-inflammatory and other biological activities. However, the high melting point and poor solubility limit their bioavailability and practical application. It is advantageous to modify phytosterols chemically and physically. This article reviews and discusses the chemical and physical modifications of phytosterols, as well as their effects on the bioavailability and possible toxicity in vivo. The current research on chemical modifications is mainly focused on esterification to increase the oil solubility and water solubility. For physical modifications (mainly microencapsulation), there are biopolymer-based, surfactant-based and lipid-based nanocarriers. Both chemical and physical modifications of phytosterols can effectively increase the absorption and bioavailability. The safety of modified phytosterols is also an important issue. Phytosterol esters are generally considered to be safe. However, phytosterol oxides, which may be produced during the synthesis of phytosterol esters, have shown toxicity in animal models. The toxicity of nanocarriers also needs further studies.
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Affiliation(s)
- Simin Feng
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou, People's Republic of China.,Key Laboratory of Food Macromolecular Resources Processing Technology Research (Zhejiang University of Technology), China National Light Industry, Beijing, China.,Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers The State University of New Jersey, Piscataway, New Jersey, USA
| | - Liling Wang
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou, People's Republic of China
| | - Ping Shao
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou, People's Republic of China.,Key Laboratory of Food Macromolecular Resources Processing Technology Research (Zhejiang University of Technology), China National Light Industry, Beijing, China
| | - Peilong Sun
- College of Food Science and Technology, Zhejiang University of Technology, Hangzhou, People's Republic of China.,Key Laboratory of Food Macromolecular Resources Processing Technology Research (Zhejiang University of Technology), China National Light Industry, Beijing, China
| | - Chung S Yang
- Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers The State University of New Jersey, Piscataway, New Jersey, USA
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10
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Martianto D, Bararah A, Andarwulan N, Średnicka-Tober D. Cross-Sectional Study of Plant Sterols Intake as a Basis for Designing Appropriate Plant Sterol-Enriched Food in Indonesia. Nutrients 2021; 13:nu13020452. [PMID: 33572980 PMCID: PMC7912629 DOI: 10.3390/nu13020452] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 12/22/2022] Open
Abstract
Coronary heart disease (CHD) is one of the leading causes of mortality in many low-income and middle-income countries, including Indonesia, with elevated blood cholesterol level being one of significant risk factors for this condition. The problem should be addressed by combining healthy lifestyle and diet, where functional foods having a cholesterol-lowering activity could play a significant role. A group of compounds that had been proven to show cholesterol-lowering ability are plant sterols. To develop more suitable functional foods that could substantially contribute to hypercholesterolemia prevention in Indonesian population, up-to-date data about plant sterols dietary intake are required, and were not available until this research was done. This study aimed to estimate daily plant sterols intake and to determine the consumption pattern of foods containing plant sterols in rural and urban area of Bogor, West Java, Indonesia. The research was conducted with a cross-sectional design, with 200 respondents. The study revealed that the level of plant sterols intake in Bogor reached on average 229.76 mg/day and was not significantly different between urban and rural area. Cereals, vegetables, and fruit products were the main food sources of plant sterols in both areas. In addition, a list of several surveyed food items possible to be enriched with plant sterols was developed within the study. These results provide baseline data to develop functional foods fortified with plant sterols suitable for the Indonesian needs and taste. However, further studies are needed to confirm efficacy and safety of introducing such phytosterol-enriched products into a habitual diet, especially considering possible long-term side effects of plant sterol treatment.
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Affiliation(s)
- Drajat Martianto
- Southeast Asian Food and Agricultural Science and Technology (SEAFAST) Center, IPB Darmaga Campus, IPB University, Bogor 16680, West Java, Indonesia; (D.M.); (N.A.)
- Department of Community Nutrition, Faculty of Human Ecology, IPB Darmaga Campus, IPB University, Bogor 16680, West Java, Indonesia
| | - Atikah Bararah
- Department of Food Science and Technology, Faculty of Agricultural Technology, IPB Darmaga Campus, IPB University, P.O. Box 220, Bogor 16680, West Java, Indonesia;
| | - Nuri Andarwulan
- Southeast Asian Food and Agricultural Science and Technology (SEAFAST) Center, IPB Darmaga Campus, IPB University, Bogor 16680, West Java, Indonesia; (D.M.); (N.A.)
- Department of Food Science and Technology, Faculty of Agricultural Technology, IPB Darmaga Campus, IPB University, P.O. Box 220, Bogor 16680, West Java, Indonesia;
| | - Dominika Średnicka-Tober
- Department of Functional and Organic Food, Institute of Human Nutrition Sciences, Warsaw University of Life Sciences, Nowoursynowska 159c, 02-776 Warsaw, Poland
- Correspondence: ; Tel.: +48-225-937-035
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11
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Khunweeraphong N, Mitchell-White J, Szöllősi D, Hussein T, Kuchler K, Kerr ID, Stockner T, Lee JY. Picky ABCG5/G8 and promiscuous ABCG2 - a tale of fatty diets and drug toxicity. FEBS Lett 2020; 594:4035-4058. [PMID: 32978801 PMCID: PMC7756502 DOI: 10.1002/1873-3468.13938] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Accepted: 09/03/2020] [Indexed: 12/20/2022]
Abstract
Structural data on ABCG5/G8 and ABCG2 reveal a unique molecular architecture for subfamily G ATP‐binding cassette (ABCG) transporters and disclose putative substrate‐binding sites. ABCG5/G8 and ABCG2 appear to use several unique structural motifs to execute transport, including the triple helical bundles, the membrane‐embedded polar relay, the re‐entry helices, and a hydrophobic valve. Interestingly, ABCG2 shows extreme substrate promiscuity, whereas ABCG5/G8 transports only sterol molecules. ABCG2 structures suggest a large internal cavity, serving as a binding region for substrates and inhibitors, while mutational and pharmacological analyses support the notion of multiple binding sites. By contrast, ABCG5/G8 shows a collapsed cavity of insufficient size to hold substrates. Indeed, mutational analyses indicate a sterol‐binding site at the hydrophobic interface between the transporter and the lipid bilayer. In this review, we highlight key differences and similarities between ABCG2 and ABCG5/G8 structures. We further discuss the relevance of distinct and shared structural features in the context of their physiological functions. Finally, we elaborate on how ABCG2 and ABCG5/G8 could pave the way for studies on other ABCG transporters.
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Affiliation(s)
- Narakorn Khunweeraphong
- Max Perutz Labs Vienna, Campus Vienna Biocenter, Center for Medical Biochemistry, Medical University of Vienna, Vienna, Austria.,CCRI-St. Anna Children's Cancer Research Institute, Vienna, Austria
| | - James Mitchell-White
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
| | - Dániel Szöllősi
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Toka Hussein
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Karl Kuchler
- Max Perutz Labs Vienna, Campus Vienna Biocenter, Center for Medical Biochemistry, Medical University of Vienna, Vienna, Austria
| | - Ian D Kerr
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK
| | - Thomas Stockner
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Jyh-Yeuan Lee
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, ON, Canada
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12
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Vitamin D Status of Mice Deficient in Scavenger Receptor Class B Type 1, Cluster Determinant 36 and ATP-Binding Cassette Proteins G5/G8. Nutrients 2020; 12:nu12082169. [PMID: 32707802 PMCID: PMC7469065 DOI: 10.3390/nu12082169] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 12/15/2022] Open
Abstract
Classical lipid transporters are suggested to modulate cellular vitamin D uptake. This study investigated the vitamin D levels in serum and tissues of mice deficient in SR-B1 (Srb1-/-), CD36 (Cd36-/-) and ABC-G5/G8 (Abcg5/g8-/-) and compared them with corresponding wild-type (WT) mice. All mice received triple-deuterated vitamin D3 (vitamin D3-d3) for six weeks. All knockout mice vs. WT mice showed specific alterations in their vitamin D concentrations. Srb1-/- mice had higher levels of vitamin D3-d3 in the serum, adipose tissue, kidney and heart, whereas liver levels of vitamin D3-d3 remained unaffected. Additionally, Srb1-/- mice had lower levels of deuterated 25-hydroxyvitamin D3 (25(OH)D3-d3) in the serum, liver and kidney compared to WT mice. In contrast, Cd36-/- and WT mice did not differ in the serum and tissue levels of vitamin D3-d3, but Cd36-/- vs. WT mice were characterized by lower levels of 25(OH)D3-d3 in the serum, liver and kidney. Finally, Abcg5/g8-/- mice tended to have higher levels of vitamin D3-d3 in the serum and liver. Major alterations in Abcg5/g8-/- mice were notably higher levels of 25(OH)D3-d3 in the serum and kidney, accompanied by a higher hepatic mRNA abundance of Cyp27a1 hydroxylase. To conclude, the current data emphasize the significant role of lipid transporters in the uptake, tissue distribution and activation of vitamin D.
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Bastida JM, Benito R, González-Porras JR, Rivera J. ABCG5 and ABCG8 gene variations associated with sitosterolemia and platelet dysfunction. Platelets 2020; 32:573-577. [PMID: 32546081 DOI: 10.1080/09537104.2020.1779926] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Jose María Bastida
- Department of Hematology, Hospital Universitario de Salamanca - IBSAL, Salamanca, Spain
| | - Rocío Benito
- IBSAL, IBMCC, CIC, Universidad de Salamanca-CSIC, Salamanca, Spain
| | | | - José Rivera
- Department of Hematology and Oncology, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, Murcia, Spain
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ABCG5/G8: a structural view to pathophysiology of the hepatobiliary cholesterol secretion. Biochem Soc Trans 2020; 47:1259-1268. [PMID: 31654053 PMCID: PMC6824678 DOI: 10.1042/bst20190130] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 09/26/2019] [Accepted: 09/30/2019] [Indexed: 12/17/2022]
Abstract
The ABCG5/G8 heterodimer is the primary neutral sterol transporter in hepatobiliary and transintestinal cholesterol excretion. Inactivating mutations on either the ABCG5 or ABCG8 subunit cause Sitosterolemia, a rare genetic disorder. In 2016, a crystal structure of human ABCG5/G8 in an apo state showed the first structural information on ATP-binding cassette (ABC) sterol transporters and revealed several structural features that were observed for the first time. Over the past decade, several missense variants of ABCG5/G8 have been associated with non-Sitosterolemia lipid phenotypes. In this review, we summarize recent pathophysiological and structural findings of ABCG5/G8, interpret the structure-function relationship in disease-causing variants and describe the available evidence that allows us to build a mechanistic view of ABCG5/G8-mediated sterol transport.
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Dierckx T, Bogie JFJ, Hendriks JJA. The Impact of Phytosterols on the Healthy and Diseased Brain. Curr Med Chem 2020; 26:6750-6765. [PMID: 29984647 DOI: 10.2174/0929867325666180706113844] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 02/28/2018] [Accepted: 03/07/2018] [Indexed: 02/07/2023]
Abstract
The central nervous system (CNS) is the most cholesterol-rich organ in mammals. Cholesterol homeostasis is essential for proper brain functioning and dysregulation of cholesterol metabolism can lead to neurological problems. Multiple sclerosis (MS) and Alzheimer's disease (AD) are examples of neurological diseases that are characterized by a disturbed cholesterol metabolism. Phytosterols (PS) are plant-derived components that structurally and functionally resemble cholesterol. PS are known for their cholesterol-lowering properties. Due to their ability to reach the brain, researchers have started to investigate the physiological role of PS in the CNS. In this review, the metabolism and function of PS in the diseased and healthy CNS are discussed.
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Affiliation(s)
- Tess Dierckx
- Biomedical Research Institute, Hasselt University, Diepenbeek, Hassett, Belgium
| | - Jeroen F J Bogie
- Biomedical Research Institute, Hasselt University, Diepenbeek, Hassett, Belgium
| | - Jerome J A Hendriks
- Biomedical Research Institute, Hasselt University, Diepenbeek, Hassett, Belgium
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Bastida JM, Girós ML, Benito R, Janusz K, Hernández-Rivas JM, González-Porras JR. Sitosterolemia: Diagnosis, Metabolic and Hematological Abnormalities, Cardiovascular Disease and Management. Curr Med Chem 2019; 26:6766-6775. [DOI: 10.2174/0929867325666180705145900] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Revised: 03/27/2018] [Accepted: 03/27/2018] [Indexed: 12/30/2022]
Abstract
Sitosterolemia is a recessive inherited metabolic disorder of unknown prevalence,
characterized by increased levels of plasma plant sterols. It is caused by 28 and 31 variants in
ABCG5 and ABCG8 genes, respectively, and is characterized by a predisposition to hyperabsorption
and accumulation of toxic levels of plant sterols in plasma. Its clinical picture is extremely
heterogeneous. The main clinical features are tendinous and cutaneous xanthomas, arthritis
or arthralgia, premature cardiovascular disease and atherosclerosis. These characteristics
are shared with familial hypercholesterolemia (FH), making it possible for sitosterolemia to be
misdiagnosed as homozygous FH, especially in pediatric patients. In such cases, a specific
chromatography-based laboratory method is essential to differentiate sitosterol and cholesterol.
Hematological abnormalities (hemolytic anemia and macrothrombocytopenia) may be present in
25-35% of patients, in whom it is usually associated with the main clinical features, as occurs in
the 70% of the cases. In this context, the peripheral blood smear is essential and reveals giant
platelets and stomatocytes. Only 21 causative variants in ABCG5/ABCG8 are associated with
macrothrombocytopenia. Most physicians still do not recognize these hematological abnormalities
or relate them to sitosterolemia. Patients may suffer long-term misdiagnosis of immune
thrombocytopenia and be at high risk of receiving harmful therapies or of not benefitting from a
low-cholesterol diet and/or from the gold standard treatment with ezetimibe. This drug reduces
the levels of plasma plant sterols, provokes regression of xanthomas, and can alleviate hematological
abnormalities. Finally, to identify genetic defects, recent advances in high-throughput
sequencing, especially in the use of targeted sequencing of pre-specified genes, have begun to be
incorporated in the first-line approach in the field of genetic disorders.
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Affiliation(s)
- Jose María Bastida
- Department of Hematology, Hospital Universitario de Salamanca-IBSAL-USAL, Salamanca, Spain
| | - María Luisa Girós
- Seccio d'Errors Congenits del Metabolisme-IBC, Servei de Bioquimica i Genetica Molecular Hospital Clínic, IDIBAPS, CIBERER, Barcelona, Spain
| | - Rocío Benito
- IBSAL, IBMCC, CIC, Universidad de Salamanca-CSIC, Salamanca, Spain
| | - Kamila Janusz
- IBSAL, IBMCC, CIC, Universidad de Salamanca-CSIC, Salamanca, Spain
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Dietary Sargassum fusiforme improves memory and reduces amyloid plaque load in an Alzheimer's disease mouse model. Sci Rep 2019; 9:4908. [PMID: 30894635 PMCID: PMC6426980 DOI: 10.1038/s41598-019-41399-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 03/05/2019] [Indexed: 12/12/2022] Open
Abstract
Activation of liver X receptors (LXRs) by synthetic agonists was found to improve cognition in Alzheimer's disease (AD) mice. However, these LXR agonists induce hypertriglyceridemia and hepatic steatosis, hampering their use in the clinic. We hypothesized that phytosterols as LXR agonists enhance cognition in AD without affecting plasma and hepatic triglycerides. Phytosterols previously reported to activate LXRs were tested in a luciferase-based LXR reporter assay. Using this assay, we found that phytosterols commonly present in a Western type diet in physiological concentrations do not activate LXRs. However, a lipid extract of the 24(S)-Saringosterol-containing seaweed Sargassum fusiforme did potently activate LXRβ. Dietary supplementation of crude Sargassum fusiforme or a Sargassum fusiforme-derived lipid extract to AD mice significantly improved short-term memory and reduced hippocampal Aβ plaque load by 81%. Notably, none of the side effects typically induced by full synthetic LXR agonists were observed. In contrast, administration of the synthetic LXRα activator, AZ876, did not improve cognition and resulted in the accumulation of lipid droplets in the liver. Administration of Sargassum fusiforme-derived 24(S)-Saringosterol to cultured neurons reduced the secretion of Aβ42. Moreover, conditioned medium from 24(S)-Saringosterol-treated astrocytes added to microglia increased phagocytosis of Aβ. Our data show that Sargassum fusiforme improves cognition and alleviates AD pathology. This may be explained at least partly by 24(S)-Saringosterol-mediated LXRβ activation.
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Tao C, Shkumatov AA, Alexander ST, Ason BL, Zhou M. Stigmasterol accumulation causes cardiac injury and promotes mortality. Commun Biol 2019; 2:20. [PMID: 30675518 PMCID: PMC6335236 DOI: 10.1038/s42003-018-0245-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 12/02/2018] [Indexed: 12/11/2022] Open
Abstract
Cardiovascular disease is expected to remain the leading cause of death worldwide despite the introduction of proprotein convertase subtilisin/kexin type 9 inhibitors that effectively control cholesterol. Identifying residual risk factors for cardiovascular disease remains an important step for preventing and clinically managing the disease. Here we report cardiac injury and increased mortality occurring despite a 50% reduction in plasma cholesterol in a mouse model of phytosterolemia, a disease characterized by elevated levels of dietary plant sterols in the blood. Our studies show accumulation of stigmasterol, one of phytosterol species, leads to left ventricle dysfunction, cardiac interstitial fibrosis and macrophage infiltration without atherosclerosis, and increased mortality. A pharmacological inhibitor of sterol absorption prevents cardiac fibrogenesis. We propose that the pathological mechanism linking clinical sitosterolemia to the cardiovascular outcomes primarily involves phytosterols-induced cardiac fibrosis rather than cholesterol-driven atherosclerosis. Our studies suggest stigmasterol is a potent and independent risk factor for cardiovascular disease.
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Affiliation(s)
- Caroline Tao
- Cardiometabolic Disorders Therapeutic Area, Amgen Research, South San Francisco, CA USA
| | - Artem A. Shkumatov
- Comparative Biology and Safety Sciences, Amgen Research, South San Francisco, CA USA
| | - Shawn T. Alexander
- Cardiometabolic Disorders Therapeutic Area, Amgen Research, South San Francisco, CA USA
| | - Brandon L. Ason
- Cardiometabolic Disorders Therapeutic Area, Amgen Research, South San Francisco, CA USA
| | - Mingyue Zhou
- Cardiometabolic Disorders Therapeutic Area, Amgen Research, South San Francisco, CA USA
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Wang Y, Guo YL, Dong QT, Li JJ. Severe aortic valve stenosis in a 14-year-old boy with sitosterolemia. J Clin Lipidol 2019; 13:49-53. [PMID: 30528907 DOI: 10.1016/j.jacl.2018.11.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 11/08/2018] [Accepted: 11/08/2018] [Indexed: 10/27/2022]
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Wadsack D, Sattler H, Kleber ME, Eirich K, Scharnagl H, Fauler G, März W, Grammer TB. Recurrent tendosynovitis as a rare manifestation of a lipid disorder. J Clin Lipidol 2018; 13:54-61. [PMID: 30459115 DOI: 10.1016/j.jacl.2018.10.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 10/28/2022]
Abstract
A 33-year-old female had suffered from spontaneously recurrent bursitis and tendosynovitis/enthesitis of the patellar and Achilles tendons for about 10 years. The episodes of immobilization increased. Ultrasound imaging of the swollen and painful tendons showed chronic inflammation with neoangiogenesis within the tendons and hypoechoic lesions. Clinical and laboratory tests did not provide evidence for a rheumatic disease. Low density lipoprotein cholesterol was elevated. Biopsies of skin lesions did not confirm the suspicion of cutaneous xanthomas. Genetic testing for familial hypercholesterolemia was negative. Campesterol and sitosterol were elevated 7- to 12-fold and 20- to 38-fold over the upper limit of normal on two occasions. There was no relevant mutation in ABCG5. In ABCG8, we identified a missense mutation c.1267G>A in exon 9 changing glutamic acid 423 into lysine within the transmembrane domain, and an insertion of adenine (c.1487insA) leading to a frameshift and a premature stop codon (Ile497Aspfs*105). The patient had no clinical evidence of premature atherosclerosis. Therapeutic approaches with nonsteroidal antirheumatic drugs, prednisone, statins, and ezetimibe accompanied by a diet poor in plant sterols led to a relief of symptoms. This case report shows that tendon xanthoma along with tendosynovitis, especially on extensor areas, is suspicious for hypercholesterolemia as the underlying cause. The absence of atherosclerotic plaques in the abdominal aorta and in the carotid arteries on ultrasound may suggest that phytosterolemia is not necessarily accompanied by premature vascular disease.
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Affiliation(s)
- Daniel Wadsack
- Department of Medicine A, Klinikum Ludwigshafen, Ludwigshafen, Germany
| | - Horst Sattler
- Department of Medicine A, Klinikum Ludwigshafen, Ludwigshafen, Germany
| | - Marcus E Kleber
- Department of Internal Medicine V (Nephrology, Rheumatology, Hypertensiology, Endocrinolgy, Diabetology), Mannheim Medical Faculty, University of Heidelberg, Mannheim, Germany
| | | | - Hubert Scharnagl
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Günter Fauler
- Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria
| | - Winfried März
- Department of Internal Medicine V (Nephrology, Rheumatology, Hypertensiology, Endocrinolgy, Diabetology), Mannheim Medical Faculty, University of Heidelberg, Mannheim, Germany; Clinical Institute of Medical and Chemical Laboratory Diagnostics, Medical University of Graz, Graz, Austria; Synlab Academy, Synlab Holding Deutschland GmbH, Mannheim, Germany
| | - Tanja B Grammer
- Department of Internal Medicine V (Nephrology, Rheumatology, Hypertensiology, Endocrinolgy, Diabetology), Mannheim Medical Faculty, University of Heidelberg, Mannheim, Germany; Mannheim Institute of Public Health, Social and Preventive Medicine, Mannheim Medical Faculty, University of Heidelberg, Mannheim, Germany.
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21
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Patel SB, Graf GA, Temel RE. ABCG5 and ABCG8: more than a defense against xenosterols. J Lipid Res 2018; 59:1103-1113. [PMID: 29728459 DOI: 10.1194/jlr.r084244] [Citation(s) in RCA: 57] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2018] [Revised: 04/17/2018] [Indexed: 12/14/2022] Open
Abstract
The elucidation of the molecular basis of the rare disease, sitosterolemia, has revolutionized our mechanistic understanding of how dietary sterols are excreted and how cholesterol is eliminated from the body. Two proteins, ABCG5 and ABCG8, encoded by the sitosterolemia locus, work as obligate dimers to pump sterols out of hepatocytes and enterocytes. ABCG5/ABCG8 are key in regulating whole-body sterol trafficking, by eliminating sterols via the biliary tree as well as the intestinal tract. Importantly, these transporters keep xenosterols from accumulating in the body. The sitosterolemia locus has been genetically associated with lipid levels and downstream atherosclerotic disease, as well as formation of gallstones and the risk of gallbladder cancer. While polymorphic variants raise or lower the risks of these phenotypes, loss of function of this locus leads to more dramatic phenotypes, such as premature atherosclerosis, platelet dysfunction, and thrombocytopenia, and, perhaps, increased endocrine disruption and liver dysfunction. Whether small amounts of xenosterol exposure over a lifetime cause pathology in normal humans with polymorphic variants at the sitosterolemia locus remains largely unexplored. The purpose of this review will be to summarize the current state of knowledge, but also highlight key conceptual and mechanistic issues that remain to be explored.
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Affiliation(s)
- Shailendra B Patel
- Division of Endocrinology, Diabetes, and Metabolism, University of Cincinnati, Cincinnati, OH 45219
| | - Gregory A Graf
- Department of Pharmaceutical Sciences and Saha Cardiovascular Research Center and University of Kentucky, Lexington, KY 40536
| | - Ryan E Temel
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY 40536
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Half-life of plasma phytosterols in very low birth weight preterm infants on routine parenteral nutrition with vegetable oil-based lipid emulsions. Clin Nutr 2018; 37:262-269. [DOI: 10.1016/j.clnu.2016.12.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 11/15/2016] [Accepted: 12/25/2016] [Indexed: 11/20/2022]
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Kane J, Schaefer E, Malloy M. Xenosterolemia: emerging molecular and clinical insights. Curr Opin Lipidol 2017; 28:518-519. [PMID: 29095365 DOI: 10.1097/mol.0000000000000463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- John Kane
- aCardiovascular Research Institute, UCSF School of Medicine, San Francisco, California bCardiovascular Nutrition Laboratory, Tufts University School of Medicine, Boston, Massachusetts cUCSF School of Medicine, San Francisco, California, USA
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Köhler J, Teupser D, Elsässer A, Weingärtner O. Plant sterol enriched functional food and atherosclerosis. Br J Pharmacol 2017; 174:1281-1289. [PMID: 28253422 PMCID: PMC5429322 DOI: 10.1111/bph.13764] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Revised: 02/09/2017] [Accepted: 02/15/2017] [Indexed: 12/25/2022] Open
Abstract
Hypercholesterolaemia is a major cardiovascular risk factor. A healthy diet and a healthy lifestyle reduces cardiovascular risk. 'Functional foods' supplemented with phytosterols are recommended for the management of hypercholesterolaemia and have become a widely used non-prescription approach to lower plasma cholesterol levels. Two billion euros are spent world-wide each year on various functional foods, which have regulator-approved health claims for the management of elevated cholesterol levels. While international societies, such as the European Atherosclerosis Society or the National Heart Foundation in Australia, still advise phytosterols as an additional dietary option in the management of hypercholesterolaemia, recently released guidelines such as those from the National Institute of Health and Clinical Excellence in the United Kingdom are more critical of food supplementation with phytosterols and draw attention to significant safety issues. This review challenges whether an intervention with phytosterol supplements is beneficial. We summarize the current evidence from genetic diseases, genetic association studies, clinical trial data and data from animal studies. LINKED ARTICLES This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.
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Affiliation(s)
- Jürgen Köhler
- Clinic for Thorax‐, Vascular and Endovascular Surgery, Pius‐Hospital OldenburgCarl von Ossietzky UniversitätOldenburgGermany
| | - Daniel Teupser
- Institute of Laboratory MedicineLudwig‐Maximilians‐University MunichMunichGermany
| | - Albrecht Elsässer
- Department of Cardiology, Klinikum Oldenburg, European Medical School Oldenburg‐GroningenCarl von Ossietzky UniversityOldenburgGermany
| | - Oliver Weingärtner
- Department of Cardiology, Klinikum Oldenburg, European Medical School Oldenburg‐GroningenCarl von Ossietzky UniversityOldenburgGermany
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Nghiem-Rao TH, Patel SB. Investigating Sitosterolemia to Understand Lipid Physiology. ACTA ACUST UNITED AC 2017; 8:649-658. [PMID: 29928317 DOI: 10.2217/clp.13.60] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The cholesterol molecule is at the center of the pathophysiology of many vascular diseases. Whole-body cholesterol pools are maintained by a balance of endogenous synthesis, dietary absorption and elimination from our bodies. While the cellular aspects of cholesterol metabolism received significant impetus from the seminal work of Goldstein and Brown investigating LDL receptor trafficking, how dietary cholesterol was absorbed and eliminated was relatively neglected. The identification of the molecular defect a rare human disorder, Sitosterolemia, led to elucidation of a key mechanism of how we regulate the excretory pathway in the liver and in the intestine. Two proteins, ABCG5 and ABCG8, constitute a heterodimeric transporter that facilitates the extrusion of sterols from the cell into the biliary lumen, with a preference for xenosterols. This mechanism explained how dietary xenosterols are prevented from accumulating in our bodies. In addition, this disease has also highlighted the potential harm of xenosterols; macrothrombocytopenia, liver disease and endocrine disruption are seen when xenosterols accumulate. Mouse models of this disease suggest that there are more dramatic alterations of physiology, suggesting that these highly conserved mechanisms have evolved to prevent these xenosterols from accumulating in our bodies.
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Affiliation(s)
| | - Shailendra B Patel
- Medical College of Wisconsin, and the Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI
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Yoo EG. Sitosterolemia: a review and update of pathophysiology, clinical spectrum, diagnosis, and management. Ann Pediatr Endocrinol Metab 2016; 21:7-14. [PMID: 27104173 PMCID: PMC4835564 DOI: 10.6065/apem.2016.21.1.7] [Citation(s) in RCA: 93] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 03/15/2016] [Indexed: 12/28/2022] Open
Abstract
Sitosterolemia is an autosomal recessive disorder characterized by increased plant sterol levels, xanthomas, and accelerated atherosclerosis. Although it was originally reported in patients with normolipemic xanthomas, severe hypercholesterolemia have been reported in patients with sitosterolemia, especially in children. Sitosterolemia is caused by increased intestinal absorption and decreased biliary excretion of sterols resulting from biallelic mutations in either ABCG5 or ABCG8, which encode the sterol efflux transporter ABCG5 and ABCG8. Patients with sitosterolemia show extreme phenotypic heterogeneity, ranging from almost asymptomatic individuals to those with severe hypercholesterolemia leading to accelerated atherosclerosis and premature cardiac death. Hematologic manifestations include hemolytic anemia with stomatocytosis, macrothrombocytopenia, splenomegaly, and abnormal bleeding. The mainstay of therapy includes dietary restriction of both cholesterol and plant sterols and the sterol absorption inhibitor, ezetimibe. Foods rich in plant sterols include vegetable oils, wheat germs, nuts, seeds, avocado, shortening, margarine and chocolate. Hypercholesterolemia in patients with sitosterolemia is dramatically responsive to low cholesterol diet and bile acid sequestrants. Plant sterol assay should be performed in patients with normocholesterolemic xanthomas, hypercholesterolemia with unexpectedly good response to dietary modifications or to cholesterol absorption inhibitors, or hypercholesterolemia with poor response to statins, or those with unexplained hemolytic anemia and macrothrombocytopenia. Because prognosis can be improved by proper management, it is important to find these patients out and diagnose correctly. This review article aimed to summarize recent publications on sitosterolemia, and to suggest clinical indications for plant sterol assay.
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Affiliation(s)
- Eun-Gyong Yoo
- Department of Pediatrics, CHA Bundang Medical Center, CHA University, Seongnam, Korea
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Brautbar A, Leary E, Rasmussen K, Wilson DP, Steiner RD, Virani S. Genetics of familial hypercholesterolemia. Curr Atheroscler Rep 2015; 17:491. [PMID: 25712136 DOI: 10.1007/s11883-015-0491-z] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Familial hypercholesterolemia (FH) is a genetic disorder characterized by elevated low-density lipoprotein (LDL) cholesterol and premature cardiovascular disease, with a prevalence of approximately 1 in 200-500 for heterozygotes in North America and Europe. Monogenic FH is largely attributed to mutations in the LDLR, APOB, and PCSK9 genes. Differential diagnosis is critical to distinguish FH from conditions with phenotypically similar presentations to ensure appropriate therapeutic management and genetic counseling. Accurate diagnosis requires careful phenotyping based on clinical and biochemical presentation, validated by genetic testing. Recent investigations to discover additional genetic loci associated with extreme hypercholesterolemia using known FH families and population studies have met with limited success. Here, we provide a brief overview of the genetic determinants, differential diagnosis, genetic testing, and counseling of FH genetics.
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Affiliation(s)
- Ariel Brautbar
- Division of Genetics, Cook Children's Medical Center, Fort Worth, TX, USA,
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Kinetics of phytosterol metabolism in neonates receiving parenteral nutrition. Pediatr Res 2015; 78:181-9. [PMID: 25897540 PMCID: PMC4546827 DOI: 10.1038/pr.2015.78] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 01/21/2015] [Indexed: 01/14/2023]
Abstract
BACKGROUND Phytosterols in soybean oil (SO) lipids likely contribute to parenteral nutrition-associated liver disease (PNALD) in infants. No characterization of phytosterol metabolism has been done in infants receiving SO lipids. METHODS In a prospective cohort study, 45 neonates (36 SO lipid vs. 9 control) underwent serial blood sample measurements of sitosterol, campesterol, and stigmasterol. Mathematical modeling was used to determine pharmacokinetic parameters of phytosterol metabolism and phytosterol exposure. RESULTS Compared to controls, SO lipid-exposed infants had significantly higher levels of sitosterol and campesterol (P < 0.01). During SO lipid infusion, sitosterol and campesterol reached half of steady-state plasma levels within 1.5 and 0.8 d, respectively. Steady-state level was highest for sitosterol (1.68 mg/dl), followed by campesterol (0.98 mg/dl), and lowest for stigmasterol (0.01 mg/dl). Infants born < 28 wk gestational age had higher sitosterol steady-state levels (P = 0.03) and higher area under the curve for sitosterol (P = 0.03) during the first 5 d of SO lipid (AUC5) than infants born ≥ 28 wk gestational age. CONCLUSION Phytosterols in SO lipid accumulate rapidly in neonates. Very preterm infants receiving SO lipid have higher sitosterol exposure, and may have poorly developed mechanisms of eliminating phytosterols that may contribute to their vulnerability to PNALD.
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Vanmierlo T, Bogie JF, Mailleux J, Vanmol J, Lütjohann D, Mulder M, Hendriks JJ. Plant sterols: Friend or foe in CNS disorders? Prog Lipid Res 2015; 58:26-39. [DOI: 10.1016/j.plipres.2015.01.003] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 01/15/2015] [Accepted: 01/15/2015] [Indexed: 12/21/2022]
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Othman RA, Myrie SB, Mymin D, Merkens LS, Roullet JB, Steiner RD, Jones PJ. Ezetimibe reduces plant sterol accumulation and favorably increases platelet count in sitosterolemia. J Pediatr 2015; 166:125-31. [PMID: 25444527 PMCID: PMC4274192 DOI: 10.1016/j.jpeds.2014.08.069] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 08/04/2014] [Accepted: 08/28/2014] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To assess if ezetimibe (EZE), a sterol-absorption inhibitor, improves platelet (PLT) count and size relative to its effect on plasma plant sterol (PS) in patients with sitosterolemia (STSL). STUDY DESIGN Patients with STSL (5 males, 3 females, 16-56 years of age) receiving EZE intervention as part of their routine care participated in this study. EZE was discontinued for 14 weeks (off) and then resumed for another 14 weeks (on). Hematology variables along with plasma and red blood cells (RBC) PS and total cholesterol (TC) levels were measured at the end of each phase. RESULTS EZE increased PLT count (23% ± 9%) and decreased mean PLT volume (MPV; 10% ± 3%, all P < .05). In patients off EZE, PLT counts inversely correlated (r = -0.96 and r = -0.91, all P < .01) with plasma and RBC PS to TC ratio (PS/TC), and MPV positively correlated (r = 0.91, P = .03 and r = 0.93, P = .02) with plasma and RBC PS/TC. EZE reduced plasma and RBC sitosterol (-35% ± 4% and -28% ± 3%), total PS (-37% ± 4% and -28% ± 3%, all P < .0001) levels, and PS/TC (-27% ± 4% and -28% ± 4%, P < .01). CONCLUSIONS EZE reduces plasma and RBC PS levels, while increasing PLT count and decreasing MPV, and thereby may reduce the risk for bleeding in STSL. Plasma PS levels and ABCG5/ABCG8 genes should be analyzed in patients with unexplained hematologic abnormalities.
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Affiliation(s)
- Rgia A. Othman
- Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada, R3T 6C5,Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba, Winnipeg, MB, Canada, R3T 6C5
| | - Semone B. Myrie
- Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada, R3T 6C5,Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba, Winnipeg, MB, Canada, R3T 6C5
| | - David Mymin
- Internal Medicine, University of Manitoba, Winnipeg, MB, Canada, R3T 6C5
| | - Louise S. Merkens
- Pediatrics, Institute on Development and Disability/Doernbecher Children’s Hospital, Oregon Health & Science University, 3181 SW Jackson Park Road, Portland, OR 97239
| | - Jean-Baptiste Roullet
- Pediatrics, Institute on Development and Disability/Doernbecher Children’s Hospital, Oregon Health & Science University, 3181 SW Jackson Park Road, Portland, OR 97239
| | - Robert D. Steiner
- Pediatrics, Institute on Development and Disability/Doernbecher Children’s Hospital, Oregon Health & Science University, 3181 SW Jackson Park Road, Portland, OR 97239,Molecular and Medical Genetics, Institute on Development and Disability/Doernbecher Children’s Hospital, Oregon Health & Science University, 3181 SW Jackson Park Road, Portland, OR 97239,Marshfield Clinic Research Foundation, Marshfield, WI and the University of Wisconsin, Madison, WI
| | - Peter J.H. Jones
- Human Nutritional Sciences, University of Manitoba, Winnipeg, MB, Canada, R3T 6C5,Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba, Winnipeg, MB, Canada, R3T 6C5
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Wang J, Mitsche MA, Lütjohann D, Cohen JC, Xie XS, Hobbs HH. Relative roles of ABCG5/ABCG8 in liver and intestine. J Lipid Res 2014; 56:319-30. [PMID: 25378657 PMCID: PMC4306686 DOI: 10.1194/jlr.m054544] [Citation(s) in RCA: 105] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
ABCG5 (G5) and ABCG8 (G8) form a sterol transporter that acts in liver and intestine to prevent accumulation of dietary sterols. Mutations in either G5 or G8 cause sitosterolemia, a recessive disorder characterized by sterol accumulation and premature coronary atherosclerosis. Hepatic G5G8 mediates cholesterol excretion into bile, but the function and relative importance of intestinal G5G8 has not been defined. To determine the role of intestinal G5G8, we developed liver-specific (L-G5G8(-/-)), intestine-specific (I-G5G8(-/-)), and total (G5G8(-/-)) KO mice. Tissue levels of sitosterol, the most abundant plant sterol, were >90-fold higher in G5G8(-/-) mice than in WT animals. Expression of G5G8 only in intestine or only in liver decreased tissue sterol levels by 90% when compared with G5G8(-/-) animals. Biliary sterol secretion was reduced in L-G5G8(-/-) and G5G8(-/-) mice, but not in I-G5G8(-/-) mice. Conversely, absorption of plant sterols was increased in I-G5G8(-/-) and G5G8(-/-) mice, but not in L-G5G8(-/-) mice. Reverse cholesterol transport, as assessed from the fraction of intravenously administered (3)H-cholesterol that appeared in feces, was reduced in G5G8(-/-), I-G5G8(-/-), and L-G5G8(-/-) mice. Thus, G5G8 expression in both the liver and intestine protects animals from sterol accumulation, and intestinal G5G8 contributes to extrahepatic cholesterol efflux in mice.
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Affiliation(s)
- Jin Wang
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Matthew A Mitsche
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Dieter Lütjohann
- Department of Clinical Pharmacology, University of Bonn, D-53105 Bonn, Germany
| | - Jonathan C Cohen
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Xiao-Song Xie
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Helen H Hobbs
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390 Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390 Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390
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Dietrich CG, Geier A. Effect of drug transporter pharmacogenetics on cholestasis. Expert Opin Drug Metab Toxicol 2014; 10:1533-51. [PMID: 25260651 DOI: 10.1517/17425255.2014.963553] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
INTRODUCTION The liver is the central place for the metabolism of drugs and other xenobiotics. In the liver cell, oxidation and conjugation of compounds take place, and at the same time, bile formation helps in extrusion of these compounds via the biliary route. A large number of transporters are responsible for drug uptake into the liver cell and excretion into bile or efflux to the sinusoidal blood. AREAS COVERED Genetic variants of these transporters and their transactivators contribute to changes in drug handling and are also responsible for cholestatic syndromes of different severity. This review summarizes the current knowledge regarding the influence of these genetic changes. The review covers progressive hereditary cholestatic syndromes as well as recurrent or transient cholestatic syndromes such as drug-induced liver injury, intrahepatic cholestasis of pregnancy, and benign recurrent intrahepatic cholestasis. EXPERT OPINION Polymorphisms in transporter genes are frequent. For clinically relevant cholestatic syndromes, it often requires a combination of genetic variants or acquired triggers such as pregnancy or drug treatment. In combination with other pathogenetic aspects, genetic variants in drug transporters may contribute to our understanding of not only cholestatic diseases such as primary sclerosing cholangitis or primary biliary cirrhosis, but also the natural course of chronic liver disease in general.
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Abstract
PURPOSE OF REVIEW To provide an update on recent advances made in our mechanistic and pathophysiological understanding of the rare human disease Sitosterolemia, the role of ABCG5/ABCG8 in sterol trafficking and how newer data implicate a more wider role in the body. RECENT FINDINGS Sitosterolemia is caused by a genetic defect of sterolins (ABCG5/ABCG8) mapped to the STSL locus. Polymorphic variations in STSL have been linked to lipid levels and gallstone disease in whites. Newer studies now link this locus to a more diverse ethnic group for gallstone disease, susceptibility to biliary cancer, and show variants that alter sterolin function. Intriguingly, carriers of a mutant allele seem to show protection against carotid wall disease. Although the 'promoter' region of the STSL is minimal, regulatory regions responsive to liver X receptor have remained elusive, but no longer; two intronic regions in ABCG8 have now been identified. Xenosterol accumulation leads to loss of abdominal fat, infertility, and premature death. Xenosterol accumulation in mouse platelet membranes leads to platelet hyperactivation, increased microparticle formation, and reduced αIIbβ3 surface expression. In humans, phytosterols may promote liver injury in parenteral nutrition-associated liver disease. SUMMARY Progress in understanding sterolin function is beginning to show that xenosterols can be toxic and are involved on pathogenesis, and the role of ABCG5/ABCG8 may extend into other metabolic processes by altering intracellular sterol metabolism.
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Affiliation(s)
- Shailendra B Patel
- aClement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, USA bDivision of Endocrinology, Metabolism and Clinical Nutrition, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
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Escolà-Gil JC, Quesada H, Julve J, Martín-Campos JM, Cedó L, Blanco-Vaca F. Sitosterolemia: Diagnosis, Investigation, and Management. Curr Atheroscler Rep 2014; 16:424. [DOI: 10.1007/s11883-014-0424-2] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Othman RA, Myrie SB, Jones PJH. Non-cholesterol sterols and cholesterol metabolism in sitosterolemia. Atherosclerosis 2013; 231:291-9. [PMID: 24267242 DOI: 10.1016/j.atherosclerosis.2013.09.038] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2013] [Revised: 09/05/2013] [Accepted: 09/30/2013] [Indexed: 12/14/2022]
Abstract
Sitosterolemia (STSL) is a rare autosomal recessive disease, manifested by extremely elevated plant sterols (PS) in plasma and tissue, leading to xanthoma and premature atherosclerotic disease. Therapeutic approaches include limiting PS intake, interrupting enterohepatic circulation of bile acid using bile acid binding resins such as cholestyramine, and/or ileal bypass, and inhibiting intestinal sterol absorption by ezetimibe (EZE). The objective of this review is to evaluate sterol metabolism in STSL and the impact of the currently available treatments on sterol trafficking in this disease. The role of PS in initiation of xanthomas and premature atherosclerosis is also discussed. Blocking sterols absorption with EZE has revolutionized STSL patient treatment as it reduces circulating levels of non-cholesterol sterols in STSL. However, none of the available treatments including EZE have normalized plasma PS concentrations. Future studies are needed to: (i) explore where cholesterol and non-cholesterol sterols accumulate, (ii) assess to what extent these sterols in tissues can be mobilized after blocking their absorption, and (iii) define the factors governing sterol flux.
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Affiliation(s)
- Rgia A Othman
- Department of Human Nutritional Sciences, University of Manitoba, Winnipeg, Manitoba, Canada; Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba, Winnipeg, Manitoba, Canada
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