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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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Resveratrol Modulates the Redox Response and Bile Acid Metabolism to Maintain the Cholesterol Homeostasis in Fish Megalobrama amblycephala Offered a High-Carbohydrate Diet. Antioxidants (Basel) 2023; 12:antiox12010121. [PMID: 36670983 PMCID: PMC9854748 DOI: 10.3390/antiox12010121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/21/2022] [Accepted: 12/30/2022] [Indexed: 01/06/2023] Open
Abstract
This study aimed to characterize the effects of resveratrol on the redox balance, cholesterol homeostasis and bile acid metabolism of Megalobrama amblycephala offered a high-carbohydrate diet. Fish (35.0 ± 0.15 g) were fed four diets including one control diet (32% nitrogen-free extract), one high-carbohydrate diet (45% nitrogen-free extract, HC), and the HC diet supplemented with different levels (0.04%, HCR1; 0.08%, HCR2) of resveratrol for 12 weeks. The HC diet-induced redox imbalance is characterized by increased MDA content and decreased T-SOD and CAT activities in the liver. Resveratrol attenuated this by up-regulating the transcription of Cu/Zn-sod, and increasing the activities of T-SOD, CAT, and GPX. The HC diet enhanced the cholesterol synthesis, but decreased the bile acid synthesis via up-regulating both hmgcr and acat2, and down-regulating cyp7a1, thus resulting in excessive cholesterol accumulation. Resveratrol supplement decreased cholesterol synthesis, and increased cholesterol uptake in the liver by down-regulating both hmgcr and acat2, and up-regulating ldlr. It also increased bile acid synthesis and biliary excretion by up-regulating cyp7a1, and down-regulating mrp2, oatp1, and oatp4 in the hindgut, thereby decreasing cholesterol accumulation. In conclusion, resveratrol improves the cholesterol homeostasis of Megalobrama amblycephala fed a high-carbohydrate diet by modulating the redox response and bile acid metabolism.
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Hamauzu Y, Ikeda E. In vitro and in vivo evaluation of the bile acid-binding properties of dried persimmon and its non-extractable proanthocyanidin fraction. Food Chem 2022; 373:131617. [PMID: 34802807 DOI: 10.1016/j.foodchem.2021.131617] [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: 10/01/2021] [Revised: 11/10/2021] [Accepted: 11/11/2021] [Indexed: 11/04/2022]
Abstract
Dried persimmons contain abundant insoluble tannins comprised of non-extractable proanthocyanidins (NEPAs). To determine the beneficial function of NEPAs, we studied the bile acid-binding ability of NEPAs using in vitro and in vivo experiments. For the in vitro evaluation, 70% (v/v) acetone-insoluble solids (AIS) with different NEPA levels was prepared from persimmon fruits during drying. AIS with higher NEPA levels displayed stronger bile acid-binding activity, and the highest NEPA levels can be obtained from mostly-dried fruits. The in vivo bile acid-excreting effect of dried persimmon powder (DP) and AIS was verified by feeding experiments using C57BL/6J mice. The average bile acid-excretion was in order of low-fat group (1.07 µmol/day) < high-fat (HF) group (3.03 µmol/day) < HF + AIS group (4.44 µmol/day) < HF + DP group (6.74 µmol/day). These results suggest that the bile acid-excreting function of the fruit is related to the presence of NEPAs, which are constitutive ingredients of dried persimmon.
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Affiliation(s)
- Yasunori Hamauzu
- Shinshu University, Department of Agricultural and Life Sciences, Faculty of Agriculture, 8304 Minamiminowa, Nagano 399-4598, Japan.
| | - Erika Ikeda
- Shinshu University, Department of Agricultural and Life Sciences, Faculty of Agriculture, 8304 Minamiminowa, Nagano 399-4598, Japan
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Papotti B, Escolà-Gil JC, Julve J, Potì F, Zanotti I. Impact of Dietary Lipids on the Reverse Cholesterol Transport: What We Learned from Animal Studies. Nutrients 2021; 13:nu13082643. [PMID: 34444804 PMCID: PMC8401548 DOI: 10.3390/nu13082643] [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: 06/28/2021] [Revised: 07/26/2021] [Accepted: 07/28/2021] [Indexed: 12/14/2022] Open
Abstract
Reverse cholesterol transport (RCT) is a physiological mechanism protecting cells from an excessive accumulation of cholesterol. When this process begins in vascular macrophages, it acquires antiatherogenic properties, as has been widely demonstrated in animal models. Dietary lipids, despite representing a fundamental source of energy and exerting multiple biological functions, may induce detrimental effects on cardiovascular health. In the present review we summarize the current knowledge on the mechanisms of action of the most relevant classes of dietary lipids, such as fatty acids, sterols and liposoluble vitamins, with effects on different steps of RCT. We also provide a critical analysis of data obtained from experimental models which can serve as a valuable tool to clarify the effects of dietary lipids on cardiovascular disease.
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Affiliation(s)
- Bianca Papotti
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy;
| | - Joan Carles Escolà-Gil
- Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica (IIB) Sant Pau, 08041 Barcelona, Spain; (J.C.E.-G.); (J.J.)
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Josep Julve
- Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica (IIB) Sant Pau, 08041 Barcelona, Spain; (J.C.E.-G.); (J.J.)
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Francesco Potì
- Unità di Neuroscienze, Dipartimento di Medicina e Chirurgia, Università di Parma, Via Volturno 39/F, 43125 Parma, Italy;
| | - Ilaria Zanotti
- Dipartimento di Scienze degli Alimenti e del Farmaco, Università di Parma, Parco Area delle Scienze 27/A, 43124 Parma, Italy;
- Correspondence: ; Tel.: +39-0521905040
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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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Zhan K, Zheng H, Li J, Wu H, Qin S, Luo L, Huang S. Gut Microbiota-Bile Acid Crosstalk in Diarrhea-Irritable Bowel Syndrome. BIOMED RESEARCH INTERNATIONAL 2020; 2020:3828249. [PMID: 33274207 PMCID: PMC7676935 DOI: 10.1155/2020/3828249] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 10/14/2020] [Indexed: 02/06/2023]
Abstract
The occurrence of diarrhea-predominant irritable bowel syndrome (IBS-D) is the result of multiple factors, and its pathogenesis has not yet been clarified. Emerging evidence indicates abnormal changes in gut microbiota and bile acid (BA) metabolism have a close relationship with IBS-D. Gut microbiota is involved in the secondary BA production via deconjugation, 7α-dehydroxylation, oxidation, epimerization, desulfation, and esterification reactions respectively. Changes in the composition and quantity of gut microbiota have an important impact on the metabolism of BAs, which can lead to the occurrence of gastrointestinal diseases. BAs, synthesized in the hepatocytes, play an important role in maintaining the homeostasis of gut microbiota and the balance of glucose and lipid metabolism. In consideration of the complex biological functional connections among gut microbiota, BAs, and IBS-D, it is urgent to review the latest research progress in this field. In this review, we summarized the alterations of gut microbiota in IBS-D and discussed the mechanistic connections between gut microbiota and BA metabolism in IBS-D, which may be involved in activating two important bile acid receptors, G-protein coupled bile acid receptor 1 (TGR5) and farnesoid X receptor (FXR). We also highlight the strategies of prevention and treatment of IBS-D via regulating gut microbiota-bile acid axis, including probiotics, fecal microbiota transplantation (FMT), cholestyramine, and the cutting-edge technology about bacteria genetic engineering.
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Affiliation(s)
- Kai Zhan
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou 510000, China
| | - Huan Zheng
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou 510000, China
| | - Jianqing Li
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou 510000, China
| | - Haomeng Wu
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou 510000, China
| | - Shumin Qin
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou 510000, China
| | - Lei Luo
- Department of Gastroenterology, The Second People's Hospital of China Three Gorges University, Yichang 443000, China
| | - Shaogang Huang
- The Second Clinical College of Guangzhou University of Chinese Medicine, Guangzhou 510000, China
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Abstract
Cholesterol homeostasis and trafficking are critical to the maintenance of the asymmetric plasma membrane of eukaryotic cells. Disruption or dysfunction of cholesterol trafficking leads to numerous human diseases. ATP-binding cassette (ABC) transporters play several critical roles in this process, and mutations in these sterol transporters lead to disorders such as Tangier disease and sitosterolemia. Biochemical and structural information on ABC sterol transporters is beginning to emerge, with published structures of ABCA1 and ABCG5/G8; these two proteins function in the reverse cholesterol transport pathway and mediate the efflux of cholesterol and xenosterols to high-density lipoprotein and bile salt micelles, respectively. Although both of these transporters belong to the ABC family and mediate the efflux of a sterol substrate, they have many distinct differences. Here, we summarize the current understanding of sterol transport driven by ABC transporters, with an emphasis on these two extensively characterized transporters.
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Affiliation(s)
- Ashlee M Plummer
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Alan T Culbertson
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA;
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8
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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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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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Heidker RM, Caiozzi GC, Ricketts ML. Grape Seed Procyanidins and Cholestyramine Differentially Alter Bile Acid and Cholesterol Homeostatic Gene Expression in Mouse Intestine and Liver. PLoS One 2016; 11:e0154305. [PMID: 27111442 PMCID: PMC4844140 DOI: 10.1371/journal.pone.0154305] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 04/12/2016] [Indexed: 01/05/2023] Open
Abstract
Bile acid (BA) sequestrants, lipid-lowering agents, may be prescribed as a monotherapy or combination therapy to reduce the risk of coronary artery disease. Over 33% of adults in the United States use complementary and alternative medicine strategies, and we recently reported that grape seed procyanidin extract (GSPE) reduces enterohepatic BA recirculation as a means to reduce serum triglyceride (TG) levels. The current study was therefore designed to assess the effects on BA, cholesterol and TG homeostatic gene expression following co-administration with GSPE and the BA sequestrant, cholestyramine (CHY). Eight-week old male C57BL/6 mice were treated for 4 weeks with either a control or 2% CHY-supplemented diet, after which, they were administered vehicle or GSPE for 14 hours. Liver and intestines were harvested and gene expression was analyzed. BA, cholesterol, non-esterified fatty acid and TG levels were also analyzed in serum and feces. Results reveal that GSPE treatment alone, and co-administration with CHY, regulates BA, cholesterol and TG metabolism differently than CHY administration alone. Notably, GSPE decreased intestinal apical sodium-dependent bile acid transporter (Asbt) gene expression, while CHY significantly induced expression. Administration with GSPE or CHY robustly induced hepatic BA biosynthetic gene expression, especially cholesterol 7α-hydroxylase (Cyp7a1), compared to control, while co-administration further enhanced expression. Treatment with CHY induced both intestinal and hepatic cholesterologenic gene expression, while co-administration with GSPE attenuated the CHY-induced increase in the liver but not intestine. CHY also induced hepatic lipogenic gene expression, which was attenuated by co-administration with GSPE. Consequently, a 25% decrease in serum TG levels was observed in the CHY+GSPE group, compared to the CHY group. Collectively, this study presents novel evidence demonstrating that GSPE provides additive and complementary efficacy as a lipid-lowering combination therapy in conjunction with CHY by attenuating hepatic cholesterol synthesis, enhancing BA biosynthesis and decreasing lipogenesis, which warrants further investigation.
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Affiliation(s)
- Rebecca M. Heidker
- Department of Agriculture, Nutrition and Veterinary Sciences, University of Nevada Reno, Reno, Nevada, United States of America
| | - Gianella C. Caiozzi
- Department of Agriculture, Nutrition and Veterinary Sciences, University of Nevada Reno, Reno, Nevada, United States of America
| | - Marie-Louise Ricketts
- Department of Agriculture, Nutrition and Veterinary Sciences, University of Nevada Reno, Reno, Nevada, United States of America
- * E-mail:
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11
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Identification of liver CYP51 as a gene responsive to circulating cholesterol in a hamster model. J Nutr Sci 2016; 5:e16. [PMID: 27110359 PMCID: PMC4831128 DOI: 10.1017/jns.2016.3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 01/05/2016] [Indexed: 12/17/2022] Open
Abstract
Hypercholesterolaemia is a risk factor for CVD, which is a leading cause of death in industrialised societies. The biosynthetic pathways for cholesterol metabolism are well understood; however, the regulation of circulating cholesterol by diet is still not fully elucidated. The present study aimed to gain more comprehensive understanding of the relationship between circulating cholesterol levels and molecular effects in target tissues using the hamster model. Male golden Syrian hamsters were fed with chow or diets containing 36 % energy from fat with or without 1 % cholesteyramine (CA) as a modulator of circulating cholesterol levels for 35 d. It was revealed that the expression of lanosterol 14α-demethylase (CYP51) instead of 3-hydroxy-3-methyl-glutaryl (HMG)-CoA reductase mRNA expression was responsive to circulating cholesterol in hamsters fed hypercholesterolaemic diets. The high-fat diet increased circulating cholesterol and down-regulated CYP51, but not HMG-CoA reductase. The CA diet decreased cholesterol and increased CYP51 expression, but HMG-CoA reductase expression was not affected. The high-fat diet and CA diet altered the expression level of cholesterol, bile acids and lipid metabolism-associated genes (LDL receptor, cholesterol 7α-hydroxylase (CYP7A1), liver X receptor (LXR) α, and ATP-binding cassette subfamily G member 5/8 (ABCG5/8)) in the liver, which were significantly correlated with circulating cholesterol levels. Correlation analysis also showed that circulating cholesterol levels were regulated by LXR/retinoid X receptor and PPAR pathways in the liver. Using the hamster model, the present study provided additional molecular insights into the influence of circulating cholesterol on hepatic cholesterol metabolism pathways during hypercholesterolaemia.
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Key Words
- ABCG5/, ATP-binding cassette subfamily G member 5/8
- CA, cholestyramine
- CYP51
- CYP51, lanosterol 14α-demethylase
- CYP7A1, cholesterol 7α-hydroxylase
- Circulating cholesterol
- HF + CA, high-fat + cholestyramine
- HF, high-fat
- HMG, 3-hydroxy-3-methyl-glutaryl
- Hamsters
- Hypercholesterolaemia
- IPA, Ingenuity Pathway Analysis
- LXRα, liver X receptor α
- RXR, retinoid X receptor
- SREBP, sterol regulatory element-binding protein
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12
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Singhal R, Harrill AH, Menguy-Vacheron F, Jayyosi Z, Benzerdjeb H, Watkins PB. Benign elevations in serum aminotransferases and biomarkers of hepatotoxicity in healthy volunteers treated with cholestyramine. BMC Pharmacol Toxicol 2014; 15:42. [PMID: 25086653 PMCID: PMC4130124 DOI: 10.1186/2050-6511-15-42] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Accepted: 07/03/2014] [Indexed: 12/16/2022] Open
Abstract
Background There are currently no serum biomarkers capable of distinguishing elevations in serum alanine aminotransferase (ALT) that portend serious liver injury potential from benign elevations such as those occurring during cholestyramine treatment. The aim of the research was to test the hypothesis that newly proposed biomarkers of hepatotoxicity would not significantly rise in serum during elevations in serum ALT associated with cholestyramine treatment, which has never been associated with clinically relevant liver injury. Methods In a double-blind placebo-controlled trial, cholestyramine (8g) was administered for 11 days to healthy adult volunteers. Serum from subjects with elevations in alanine aminotransferase (ALT) exceeding three-fold the upper limit of normal (ULN) were utilized for biomarker quantification. Results In 11 of 67 subjects, cholestyramine treatment resulted in ALT elevation by >3x ULN (mean 6.9 fold; range 3–28 fold). In these 11 subjects, there was a 22.4-fold mean increase in serum levels of miR-122 relative to baseline, supporting a liver origin of the serum ALT. Significant elevations were noted in mean levels of necrosis biomarkers sorbitol dehydrogenase (8.1 fold), cytokeratin 18 (2.1 fold) and HMGB1 (1.7 fold). Caspase-cleaved cytokeratin 18, a biomarker of apoptosis was also significantly elevated (1.7 fold). A rise in glutamate dehydrogenase (7.3 fold) may support mitochondrial dysfunction. Conclusion All toxicity biomarkers measured in this study were elevated along with ALT, confirming the liver origin and reflecting both hepatocyte necrosis and apoptosis. Since cholestyramine treatment has no clinical liver safety concerns, we conclude that interpretation of the biomarkers studied may not be straightforward in the context of assessing liver safety of new drugs.
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Affiliation(s)
| | | | | | | | | | - Paul B Watkins
- The Hamner-University of North Carolina Institute for Drug Safety Sciences, 6 Davis Drive, Research Triangle Park, NC 27709, USA.
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13
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Cherrington NJ, Estrada TE, Frisk HA, Canet MJ, Hardwick RN, Dvorak B, Lux K, Halpern MD. The hepatic bile acid transporters Ntcp and Mrp2 are downregulated in experimental necrotizing enterocolitis. Am J Physiol Gastrointest Liver Physiol 2013; 304:G48-56. [PMID: 23125159 PMCID: PMC3543632 DOI: 10.1152/ajpgi.00317.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Necrotizing enterocolitis (NEC) is the most common gastrointestinal emergency of premature infants and is characterized by an extensive hemorrhagic inflammatory necrosis of the distal ileum and proximal colon. We have previously shown that, during the development of experimental NEC, the liver plays an important role in regulating inflammation in the ileum, and accumulation of ileal bile acids (BA) along with dysregulation of ileal BA transporters contributes to ileal damage. Given these findings, we speculated that hepatic BA transporters would also be altered in experimental NEC. Using both rat and mouse models of NEC, levels of Cyp7a1, Cyp27a1, and the hepatic BA transporters Bsep, Ntcp, Oatp2, Oatp4, Mrp2, and Mrp3 were investigated. In addition, levels of hepatic BA transporters were also determined when the proinflammatory cytokines tumor necrosis factor (TNF)-α and interleukin (IL)-18, which are both elevated in NEC, are neutralized during disease development. Ntcp and Mrp2 were decreased in NEC, but elevated ileal BA levels were not responsible for these reductions. However, neutralization of TNF-α normalized Ntcp, whereas removal of IL-18 normalized Mrp2 levels. These data show that the hepatic transporters Ntcp and Mrp2 are downregulated, whereas Cyp27a1 is increased in rodent models of NEC. Furthermore, increased levels of TNF-α and IL-18 in experimental NEC may play a role in the regulation of Ntcp and Mrp2, respectively. These data suggest the gut-liver axis should be considered when therapeutic modalities for NEC are developed.
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Affiliation(s)
- Nathan J. Cherrington
- 1Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona; and
| | - Teresa E. Estrada
- 2Department of Pediatrics and the Steele Children's Research Center, University of Arizona, Tucson Arizona
| | - Harrison A. Frisk
- 2Department of Pediatrics and the Steele Children's Research Center, University of Arizona, Tucson Arizona
| | - Mark J. Canet
- 1Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona; and
| | - Rhiannon N. Hardwick
- 1Department of Pharmacology and Toxicology, University of Arizona, Tucson, Arizona; and
| | - Bohuslav Dvorak
- 2Department of Pediatrics and the Steele Children's Research Center, University of Arizona, Tucson Arizona
| | - Katie Lux
- 2Department of Pediatrics and the Steele Children's Research Center, University of Arizona, Tucson Arizona
| | - Melissa D. Halpern
- 2Department of Pediatrics and the Steele Children's Research Center, University of Arizona, Tucson Arizona
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Fernández-Barrena MG, Monte MJ, Latasa MU, Uriarte I, Vicente E, Chang HCY, Rodriguez-Ortigosa CM, Elferink RO, Berasain C, Marin JJG, Prieto J, Ávila MA. Lack of Abcc3 expression impairs bile-acid induced liver growth and delays hepatic regeneration after partial hepatectomy in mice. J Hepatol 2012; 56:367-73. [PMID: 21756856 DOI: 10.1016/j.jhep.2011.05.031] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2011] [Revised: 05/10/2011] [Accepted: 05/23/2011] [Indexed: 12/22/2022]
Abstract
BACKGROUND & AIMS Bile acids (BA) are increasingly recognized as important modulators of liver regeneration. Increased enterohepatic BA flux has been proposed to generate specific signals that activate hepatocyte proliferation after partial hepatectomy (PH). We have investigated the role of the BA membrane transporter Mrp3 (Abcc3), which is expressed in the liver and gut, in the hepatic growth response elicited by BA and in liver regeneration after PH. METHODS Liver growth and regeneration, and the expression of growth-related genes, were studied in Mrp3(+/+) and Mrp3(-/-) mice fed a cholic acid (CA) supplemented diet and after 2/3 PH. Activation of the BA receptor FXR was measured in mice after in vivo transduction of the liver with a FXR-Luciferase reporter plasmid. BA levels were measured in portal serum and liver tissue by high performance liquid chromatography-tandem mass spectrometry. RESULTS Liver growth elicited by CA feeding was significantly reduced in Mrp3(-/-) mice. These animals showed reduced FXR activation in the liver after CA administration and decreased portal serum levels of BA. Liver regeneration after PH was significantly delayed in Mrp3-deficient mice. Proliferation-related gene expression and peak DNA synthesis in Mrp3(-/-) mice occurred later than in wild types, coinciding with a retarded elevation in intra-hepatic BA levels. CONCLUSIONS Lack of Abcc3 expression markedly impairs liver growth in response to BA and after PH. Our data suggest that Mrp3 plays a non-redundant role in the regulation of BA flux during liver regeneration.
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Li X, Wang L, Li Y, Ho Y, Yang D, Chen Y, Hu X, Xue M. Polysorbates as novel lipid-modulating candidates for reducing serum total cholesterol and low-density lipoprotein levels in hyperlipidemic C57BL/6J mice and rats. Eur J Pharmacol 2011; 660:468-75. [DOI: 10.1016/j.ejphar.2011.03.027] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 02/25/2011] [Accepted: 03/21/2011] [Indexed: 11/27/2022]
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16
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Thomas AM, Hart SN, Kong B, Fang J, Zhong XB, Guo GL. Genome-wide tissue-specific farnesoid X receptor binding in mouse liver and intestine. Hepatology 2010; 51:1410-9. [PMID: 20091679 PMCID: PMC4855519 DOI: 10.1002/hep.23450] [Citation(s) in RCA: 166] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UNLABELLED Farnesoid X receptor (FXR) is a bile acid-activated transcription factor belonging to the nuclear receptor superfamily. FXR is highly expressed in liver and intestine and crosstalk mediated by FXR in these two organs is critical in maintaining bile acid homeostasis. FXR deficiency has been implicated in many liver and intestine diseases. However, regulation of transcription by FXR at the genomic level is not known. This study analyzed genome-wide FXR binding in liver and intestine of mice treated with a synthetic FXR ligand (GW4064) by chromatin immunoprecipitation coupled to massively parallel sequencing (ChIP-seq). The results showed a large degree of tissue-specific FXR binding, with only 11% of total sites shared between liver and intestine. The sites were widely distributed between intergenic, upstream, intragenic, and downstream of genes, with novel sites identified within even known FXR target genes. Motif analysis revealed a half nuclear receptor binding site, normally bound by a few orphan nuclear receptors, adjacent to the FXR response elements, indicating possible involvement of some orphan nuclear receptors in modulating FXR function. Furthermore, pathway analysis indicated that FXR may be extensively involved in multiple cellular metabolic pathways. CONCLUSION This study reports genome-wide FXR binding in vivo and the results clearly demonstrate tissue-specific FXR/gene interaction. In addition, FXR may be involved in regulating broader biological pathways in maintaining hepatic and intestinal homeostasis.
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Affiliation(s)
- Ann M. Thomas
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS
| | - Steven N. Hart
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS
| | - Bo Kong
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS
| | - Jianwen Fang
- Applied Bioinformatics Laboratory, University of Kansas, Lawrence, KS
| | - Xiao-bo Zhong
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS
| | - Grace L. Guo
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, KS
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Korou LM, Agrogiannis G, Pantopoulou A, Vlachos IS, Iliopoulos D, Karatzas T, Perrea DN. Comparative antilipidemic effect of N-acetylcysteine and sesame oil administration in diet-induced hypercholesterolemic mice. Lipids Health Dis 2010; 9:23. [PMID: 20205925 PMCID: PMC2848040 DOI: 10.1186/1476-511x-9-23] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 03/06/2010] [Indexed: 11/10/2022] Open
Abstract
Background There is an increasing number of novel antilipidemic therapies under consideration. The putative hypolipidemic effect of N-acetylcysteine (NAC) and sesame oil was studied in a mouse model of dietary-induced hypercholesterolemia. Methods Male C57bl/6 mice were assigned to the following groups: (NC) control group, (HC) group receiving test diet supplemented with 2% cholesterol and 0.5% cholic acid for 8 weeks, (HCN) group receiving the test diet with NAC supplementation (230 mg/kg p.o.) and (HCS) group fed the test diet enriched with 10% sesame oil. Total serum cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides were assayed at the beginning and at the end of the experiment. Total peroxides and nitric oxide (NO) levels were measured in the serum at the end of the experiment. Hepatic and aortic lesions were evaluated by haematoxylin-eosin staining. Results Higher serum levels of total and LDL-cholesterol were recorded in all groups fed the high cholesterol diet. The HCN group presented reduced lipid levels compared to HC and HCS groups. No differences were observed between HCS and HC groups. Peroxide content in serum was markedly increased in mice consuming high cholesterol diet. NAC and sesame oil administration led to a significant decrease of serum lipid peroxidation in the levels of control group, whereas only NAC restored NO bioavailability. In terms of liver histology, the lesions observed in HCN group were less severe than those seen in the other high cholesterol groups. Conclusion Co-administration of NAC, but not sesame oil, restored the disturbed lipid profile and improved hepatic steatosis in the studied diet-induced hypercholesterolemic mice. Both agents appear to ameliorate serum antioxidant defense.
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Affiliation(s)
- Laskarina-Maria Korou
- Department of Experimental Surgery and Surgical Research NS Christeas, Athens School of Medicine, Athens, Greece.
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PERES AT, DALBONI MA, CANZIANI ME, MANFREDI SR, CARVALHO JTG, BATISTA MC, CUPPARI L, CARVALHO AB, MOYSES RMA, GUIMARÃES N, JORGETTI V, ANDREOLI MC, DRAIBE SA, CENDOROGLO M. Effect of phosphate binders on oxidative stress and inflammation markers in hemodialysis patients. Hemodial Int 2009; 13:271-7. [DOI: 10.1111/j.1542-4758.2009.00369.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Abstract
Bile acids (BAs) have a long established role in fat digestion in the intestine by acting as tensioactives, due to their amphipathic characteristics. BAs are reabsorbed very efficiently by the intestinal epithelium and recycled back to the liver via transport mechanisms that have been largely elucidated. The transport and synthesis of BAs are tightly regulated in part by specific plasma membrane receptors and nuclear receptors. In addition to their primary effect, BAs have been claimed to play a role in gastrointestinal cancer, intestinal inflammation and intestinal ionic transport. BAs are not equivalent in any of these biological activities, and structural requirements have been generally identified. In particular, some BAs may be useful for cancer chemoprevention and perhaps in inflammatory bowel disease, although further research is necessary in this field. This review covers the most recent developments in these aspects of BA intestinal biology.
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Chanda D, Park JH, Choi HS. Molecular basis of endocrine regulation by orphan nuclear receptor Small Heterodimer Partner. Endocr J 2008; 55:253-68. [PMID: 17984569 DOI: 10.1507/endocrj.k07e-103] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Nuclear receptors (NRs) are a unique superfamily of transcription factors (TFs) which are involved in and play a crucial role in almost all aspects of mammalian physiology. Small Heterodimer Partner (SHP; NR0B2), an exceptional member of this superfamily of NRs, have been identified as a key regulatory factor of the transcription of a variety of genes involved in diverse metabolic pathways, and are thereby an important factor in a variety of physiological functions. Since its discovery a decade ago, considerable progress has been made in the elucidation of the underlying mechanism by which SHP regulates various metabolic processes, and the results of previous studies support its importance in the maintenance of metabolic homeostasis. In this review, we have evaluated the current state of understanding of the molecular mechanisms and the resultant physiological interpretations governed by SHP.
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Affiliation(s)
- Dipanjan Chanda
- Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju, Republic of Korea
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NPC1L1 and SR-BI are involved in intestinal cholesterol absorption from small-size lipid donors. Lipids 2008; 43:401-8. [PMID: 18373109 DOI: 10.1007/s11745-008-3172-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Accepted: 03/03/2008] [Indexed: 10/22/2022]
Abstract
In the human intestinal content after a meal, cholesterol is dispersed in a complex mixture of emulsified droplets, vesicles, mixed micelles and precipitated material. The aim of this study was to determine the contribution of the main intestinal cholesterol transporters (NPC1L1, SR-BI) to the absorption processes, using different cholesterol-solubilizing donors. Cholesterol donors prepared with different taurocholate concentrations were added to an apical medium of differentiated TC7/Caco-2 cells. As the taurocholate concentrations increased, cholesterol donor size decreased (from 712 to 7 nm in diameter), which enhanced cholesterol absorption in a dose-dependent manner (38-fold). Two transport processes were observed: (1) absorption from large donors exhibited low-capacity transport with no noticeable transporter contribution; (2) efficient cholesterol absorption occurs from small lipid donors (<or=23 nm diameter), mainly due to NPC1L1 and SR-BI involvement. In addition, bile acids significantly increased mRNA and protein expression of NPC1L1, but not of SR-BI. In conclusion, bile acids present in the intestinal lumen and the micelles enhance intestinal cholesterol transport into the cell by two different regulatory processes: by reducing the lipid donor size, so that small-size mixed micelles can more easily access brush-border membrane transporters, and by increasing the expression level of the enterocyte NPC1L1. These mechanisms could account for the important inter-individual variations observed in cholesterol intestinal absorption.
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