1
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Semova I, Levenson AE, Krawczyk J, Bullock K, Gearing ME, Ling AV, Williams KA, Miao J, Adamson SS, Shin DJ, Chahar S, Graham MJ, Crooke RM, Hagey LR, Vicent D, de Ferranti SD, Kidambi S, Clish CB, Biddinger SB. Insulin Prevents Hypercholesterolemia by Suppressing 12a-Hydroxylated Bile Acid Production. Circulation 2022; 145:969-982. [PMID: 35193378 PMCID: PMC9365453 DOI: 10.1161/circulationaha.120.045373] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background: The risk of cardiovascular disease in type 1 diabetes remains extremely high, despite marked advances in blood glucose control and even the widespread use of cholesterol synthesis inhibitors. Thus, a deeper understanding of insulin regulation of cholesterol metabolism, and its disruption in type 1 diabetes, could reveal better treatment strategies. Methods: To define the mechanisms by which insulin controls plasma cholesterol levels, we knocked down the insulin receptor, FoxO1, and the key bile acid synthesis enzyme, CYP8B1. We measured bile acid composition, cholesterol absorption, and plasma cholesterol. In parallel, we measured markers of cholesterol absorption and synthesis in humans with type 1 diabetes treated with ezetimibe and statins in a double-blind crossover study. Results: Mice with hepatic deletion of the insulin receptor showed marked increases in 12α-hydroxylated bile acids (12HBAs), cholesterol absorption, and plasma cholesterol. This phenotype was entirely reversed by hepatic deletion of FoxO1. FoxO1 is inhibited by insulin, and required for the production of 12HBAs, which promote intestinal cholesterol absorption and suppress hepatic cholesterol synthesis. Knockdown of Cyp8b1 normalized 12HBA levels and completely prevented hypercholesterolemia in mice with hepatic deletion of the insulin receptor (n=5-30) as well as mouse models of type 1 diabetes (n=5-22). In parallel, the cholesterol absorption inhibitor, ezetimibe, normalized cholesterol absorption and LDL-cholesterol in patients with type 1 diabetes as well as, or better than, the cholesterol synthesis inhibitor, simvastatin (n=20). Conclusions: Insulin, by inhibiting FoxO1 in the liver, reduces 12HBAs, cholesterol absorption, and plasma cholesterol levels. Thus, type 1 diabetes leads to a unique set of derangements in cholesterol metabolism, with increased absorption rather than synthesis. These derangements are reversed by ezetimibe, but not statins, which are currently the first line of lipid-lowering treatment in type 1 diabetes. Taken together, these data suggest that a personalized approach to lipid lowering in type 1 diabetes may be more effective and highlight the need for further studies specifically in this group of patients.
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Affiliation(s)
- Ivana Semova
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Amy E Levenson
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Joanna Krawczyk
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | | | - Mary E Gearing
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Alisha V Ling
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Kathryn A Williams
- Biostatistics and Research Design Center, ICCTR, Boston Children's Hospital, Boston, MA
| | - Ji Miao
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Stuart S Adamson
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Dong-Ju Shin
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Satyapal Chahar
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | | | | | - Lee R Hagey
- Department of Medicine, University of California, San Diego, CA
| | - David Vicent
- Instituto de Investigación Sanitaria del Hospital Universitario La Paz (IdiPAZ), Madrid, Spain
| | - Sarah D de Ferranti
- Department of Cardiology, Boston Children's Hospital, Harvard Medical School, Boston, MA
| | - Srividya Kidambi
- Department of Medicine, Medical College of Wisconsin, Milwaukee, WI
| | | | - Sudha B Biddinger
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA
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2
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Li H, Yu XH, Ou X, Ouyang XP, Tang CK. Hepatic cholesterol transport and its role in non-alcoholic fatty liver disease and atherosclerosis. Prog Lipid Res 2021; 83:101109. [PMID: 34097928 DOI: 10.1016/j.plipres.2021.101109] [Citation(s) in RCA: 76] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 12/12/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a quickly emerging global health problem representing the most common chronic liver disease in the world. Atherosclerotic cardiovascular disease represents the leading cause of mortality in NAFLD patients. Cholesterol metabolism has a crucial role in the pathogenesis of both NAFLD and atherosclerosis. The liver is the major organ for cholesterol metabolism. Abnormal hepatic cholesterol metabolism not only leads to NAFLD but also drives the development of atherosclerotic dyslipidemia. The cholesterol level in hepatocytes reflects the dynamic balance between endogenous synthesis, uptake, esterification, and export, a process in which cholesterol is converted to neutral cholesteryl esters either for storage in cytosolic lipid droplets or for secretion as a major constituent of plasma lipoproteins, including very-low-density lipoproteins, chylomicrons, high-density lipoproteins, and low-density lipoproteins. In this review, we describe decades of research aimed at identifying key molecules and cellular players involved in each main aspect of hepatic cholesterol metabolism. Furthermore, we summarize the recent advances regarding the biological processes of hepatic cholesterol transport and its role in NAFLD and atherosclerosis.
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Affiliation(s)
- Heng Li
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Xiao-Hua Yu
- Institute of Clinical Medicine, The Second Affiliated Hospital of Hainan Medical University, Haikou, Hainan 460106, China
| | - Xiang Ou
- Department of Endocrinology, the First Hospital of Changsha, Changsha, Hunan 410005, China
| | - Xin-Ping Ouyang
- Department of Physiology, Institute of Neuroscience Research, Hengyang Key Laboratory of Neurodegeneration and Cognitive Impairment, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China.
| | - Chao-Ke Tang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China.
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3
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Orhan C, Kucuk O, Sahin N, Tuzcu M, Sahin K. Lycopene supplementation does not change productive performance but lowers egg yolk cholesterol and gene expression of some cholesterol-related proteins in laying hens. Br Poult Sci 2020; 62:227-234. [PMID: 33085516 DOI: 10.1080/00071668.2020.1839017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
1. This work examined the effects of purified lycopene (LYC) supplementation or a source of LYC as tomato powder (TP) on productive performance, egg yolk cholesterol levels as well as gene expression related to mechanism and regulation of cholesterol.2. One hundred and fifty laying hens (Lohman LSL, hybrid) were randomly divided into one of three treatments, with 10 replicates of five hens per cage, totalling 50 hens per treatment. The hens were fed either a standard diet (control) or a standard diet supplemented with 20 mg purified lycopene/kg diet (LYC) or an equal amount of lycopene-containing tomato powder (TP) for 12 weeks.3. Feed consumption, egg production, and feed efficiency remained similar among treatments (P ≥ 0.27). Supplementing lycopene, either as a purified form or in TP, increased the levels of serum and egg yolk lycopene and reduced serum and egg yolk cholesterol concentrations (P < 0.001). Supplementation in either form decreased gene expression for intestinal NPC1L1, MTP, ACAT2, hepatic SREBP1c, ACLY, and LXRα but increased hepatic ABCG5 and ABCG8 (P < 0.001).4. The results of the present work revealed that egg yolk cholesterol metabolism is regulated by the modulation of a group of genes, particularly with LYC supplementation.
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Affiliation(s)
- C Orhan
- Department of Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, Firat University, Elazig, Turkey
| | - O Kucuk
- Department of Animal Nutrition and Nutritional Diseases, School of Veterinary Medicine, Erciyes University, Kayseri, Turkey
| | - N Sahin
- Department of Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, Firat University, Elazig, Turkey
| | - M Tuzcu
- Department of Biology, Faculty of Science, Firat University, Elazig, Turkey
| | - K Sahin
- Department of Animal Nutrition and Nutritional Diseases, Faculty of Veterinary Medicine, Firat University, Elazig, Turkey
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4
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Zhu H, Chen J, He Z, Hao W, Liu J, Kwek E, Ma KY, Bi Y. Plasma Cholesterol-Lowering Activity of Soybean Germ Phytosterols. Nutrients 2019; 11:nu11112784. [PMID: 31731675 PMCID: PMC6893772 DOI: 10.3390/nu11112784] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2019] [Revised: 11/08/2019] [Accepted: 11/12/2019] [Indexed: 12/14/2022] Open
Abstract
Soybean germ phytosterols (SGP) largely exist in soybean germ oil. Our previous study demonstrated that soybean germ oil was effective in reducing plasma cholesterol. However, it remains unknown if its phytosterols are the active ingredients responsible for the plasma cholesterol-lowering activity. The present study aimed to test the effect of SGP on plasma cholesterol and to investigate its associated underlying mechanisms using hamsters as animal model. Male hamsters (n = 40) were randomly divided into five groups (n = 8/group) and fed one of the five diets: a non-cholesterol diet (NCD), a high cholesterol diet (HCD), a HCD diet containing 0.5% cholestyramine (PC), and two HCD diets containing 0.1% (LP) and 0.2% (HP) SGP, respectively, for six weeks. Results showed that SPG reduced plasma cholesterol level in a dose-dependent manner, whereas it dose-dependently increased the excretion of both fecal neutral and acidic sterols. SGP was also effective in displacing cholesterol from micelles. It was concluded that SGP possessed hypocholesterolemic activity, likely by inhibiting cholesterol absorption in the intestine and promoting fecal sterol excretion.
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Affiliation(s)
- Hanyue Zhu
- School of Life Sciences, Chinese University of Hong Kong, Shatin, Hong Kong 999077, China; (H.Z.); (Z.H.); (W.H.); (J.L.); (E.K.); (K.Y.M.)
| | - Jingnan Chen
- College of Food Science and Technology, Henan University of Technology, Zhengzhou 450000, China;
- Correspondence: ; Fax: +86-371-6775-8022
| | - Zouyan He
- School of Life Sciences, Chinese University of Hong Kong, Shatin, Hong Kong 999077, China; (H.Z.); (Z.H.); (W.H.); (J.L.); (E.K.); (K.Y.M.)
| | - Wangjun Hao
- School of Life Sciences, Chinese University of Hong Kong, Shatin, Hong Kong 999077, China; (H.Z.); (Z.H.); (W.H.); (J.L.); (E.K.); (K.Y.M.)
| | - Jianhui Liu
- School of Life Sciences, Chinese University of Hong Kong, Shatin, Hong Kong 999077, China; (H.Z.); (Z.H.); (W.H.); (J.L.); (E.K.); (K.Y.M.)
| | - Erika Kwek
- School of Life Sciences, Chinese University of Hong Kong, Shatin, Hong Kong 999077, China; (H.Z.); (Z.H.); (W.H.); (J.L.); (E.K.); (K.Y.M.)
| | - Ka Ying Ma
- School of Life Sciences, Chinese University of Hong Kong, Shatin, Hong Kong 999077, China; (H.Z.); (Z.H.); (W.H.); (J.L.); (E.K.); (K.Y.M.)
| | - Yanlan Bi
- College of Food Science and Technology, Henan University of Technology, Zhengzhou 450000, China;
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5
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Nakano T, Inoue I, Murakoshi T. A Newly Integrated Model for Intestinal Cholesterol Absorption and Efflux Reappraises How Plant Sterol Intake Reduces Circulating Cholesterol Levels. Nutrients 2019; 11:nu11020310. [PMID: 30717222 PMCID: PMC6412963 DOI: 10.3390/nu11020310] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 01/28/2019] [Accepted: 01/29/2019] [Indexed: 12/27/2022] Open
Abstract
Cholesterol homeostasis is maintained through a balance of de novo synthesis, intestinal absorption, and excretion from the gut. The small intestine contributes to cholesterol homeostasis by absorbing and excreting it, the latter of which is referred to as trans-intestinal cholesterol efflux (TICE). Because the excretion efficiency of endogenous cholesterol is inversely associated with the development of atherosclerosis, TICE provides an attractive therapeutic target. Thus, elucidation of the mechanism is warranted. We have shown that intestinal cholesterol absorption and TICE are inversely correlated in intestinal perfusion experiments in mice. In this review, we summarized 28 paired data sets for absorption efficiency and fecal neutral sterol excretion, a surrogate marker of TICE, obtained from 13 available publications in a figure, demonstrating the inverse correlation were nearly consistent with the assumption. We then offer a bidirectional flux model that accommodates absorption and TICE occurring in the same segment. In this model, the brush border membrane (BBM) of intestinal epithelial cells stands as the dividing ridge for cholesterol fluxes, making the opposite fluxes competitive and being coordinated by shared BBM-localized transporters, ATP-binding cassette G5/G8 and Niemann-Pick C1-like 1. Furthermore, the idea is applied to address how excess plant sterol/stanol (PS) intake reduces circulating cholesterol level, because the mechanism is still unclear. We propose that unabsorbable PS repeatedly shuttles between the BBM and lumen and promotes concomitant cholesterol efflux. Additionally, PSs, which are chemically analogous to cholesterol, may disturb the trafficking machineries that transport cholesterol to the cell interior.
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Affiliation(s)
- Takanari Nakano
- Department of Biochemistry, Faculty of Medicine, Saitama Medical University, Saitama 350-0495, Japan.
| | - Ikuo Inoue
- Department of Diabetes and Endocrinology, Faculty of Medicine, Saitama Medical University, Saitama 350-0495, Japan.
| | - Takayuki Murakoshi
- Department of Biochemistry, Faculty of Medicine, Saitama Medical University, Saitama 350-0495, Japan.
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6
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Zhu H, Chen J, He Z, Hao W, Liu J, Kwek E, Zhao Y, Ma KY, He WS, Chen ZY. Soybean germ oil reduces blood cholesterol by inhibiting cholesterol absorption and enhancing bile acid excretion. Food Funct 2019; 10:1836-1845. [DOI: 10.1039/c8fo02585a] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Soybean germ oil is beneficial in management of hypercholesterolemia in hamsters fed a high cholesterol diet.
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Affiliation(s)
- Hanyue Zhu
- School of Life Sciences
- Chinese University of Hong Kong
- Shatin
- China
| | - Jingnan Chen
- College of Food Science and Technology
- Henan University of Technology
- Zhengzhou
- China
| | - Zouyan He
- School of Life Sciences
- Chinese University of Hong Kong
- Shatin
- China
| | - Wangjun Hao
- School of Life Sciences
- Chinese University of Hong Kong
- Shatin
- China
| | - Jianhui Liu
- School of Life Sciences
- Chinese University of Hong Kong
- Shatin
- China
| | - Erika Kwek
- School of Life Sciences
- Chinese University of Hong Kong
- Shatin
- China
| | - Yimin Zhao
- School of Life Sciences
- Chinese University of Hong Kong
- Shatin
- China
| | - Ka Ying Ma
- School of Life Sciences
- Chinese University of Hong Kong
- Shatin
- China
| | - Wen-Sen He
- School of Food and Biological Engineering
- Jiangsu University
- Zhenjiang 212013
- Jiangsu
- China
| | - Zhen-Yu Chen
- School of Life Sciences
- Chinese University of Hong Kong
- Shatin
- China
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7
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Méndez-Lara KA, Santos D, Farré N, Ruiz-Nogales S, Leánez S, Sánchez-Quesada JL, Zapico E, Lerma E, Escolà-Gil JC, Blanco-Vaca F, Martín-Campos JM, Julve J, Pol O. Administration of CORM-2 inhibits diabetic neuropathy but does not reduce dyslipidemia in diabetic mice. PLoS One 2018; 13:e0204841. [PMID: 30286142 PMCID: PMC6171880 DOI: 10.1371/journal.pone.0204841] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 09/14/2018] [Indexed: 12/30/2022] Open
Abstract
The antinociceptive effects of the carbon monoxide-releasing molecule tricarbonyldichlororuthenium (II) dimer (CORM-2) during chronic pain are well documented, but most of its possible side-effects remain poorly understood. In this work, we examine the impact of CORM-2 treatment on the lipoprotein profile and two main atheroprotective functions attributed to high-density lipoprotein (HDL) in a mouse model of type 1 diabetes while analyzing the effect of this drug on diabetic neuropathy. Streptozotocin (Stz)-induced diabetic mice treated with CORM-2 (Stz-CORM-2) or vehicle (Stz-vehicle) were used to evaluate the effect of this drug on the modulation of painful diabetic neuropathy using nociceptive behavioral tests. Plasma and tissue samples were used for chemical and functional analyses, as appropriate. Two main antiatherogenic properties of HDL, i.e., the ability of HDL to protect low-density lipoprotein (LDL) from oxidation and to promote reverse cholesterol transport from macrophages to the liver and feces in vivo (m-RCT), were also assessed. Stz-induced diabetic mice displayed hyperglycemia, dyslipidemia and pain hypersensitivity. The administration of 10 mg/kg CORM-2 during five consecutive days inhibited allodynia and hyperalgesia and significantly ameliorated spinal cord markers (Cybb and Bdkrb1expression) of neuropathic pain in Stz mice, but it did not reduce the combined dyslipidemia shown in Stz-treated mice. Its administration to Stz-treated mice led to a significant increase in the plasma levels of cholesterol (∼ 1.4-fold vs. Ctrl, ∼ 1.3- fold vs. Stz-vehicle; p < 0.05) and was attributed to significant elevations in both non-HDL (∼ 1.8-fold vs. Ctrl; ∼ 1.6-fold vs. Stz-vehicle; p < 0.05) and HDL cholesterol (∼ 1.3-fold vs. Ctrl, ∼ 1.2-fold vs. Stz-vehicle; p < 0.05). The increased HDL in plasma was not accompanied by a commensurate elevation in m-RCT in Stz-CORM-2 compared to Stz-vehicle mice; instead, it was worsened as revealed by decreased [3H]-tracer trafficking into the feces in vivo. Furthermore, the HDL-mediated protection against LDL oxidation ex vivo shown by the HDL isolated from Stz-CORM-2 mice did not differ from that obtained in Stz-vehicle mice. In conclusion, the antinociceptive effects produced by a high dose of CORM-2 were accompanied by antioxidative effects but were without favorable effects on the dyslipidemia manifested in diabetic mice.
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Affiliation(s)
- Karen Alejandra Méndez-Lara
- Grup de Bases Metabòliques de Risc Cardiovascular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - David Santos
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, CIBERDEM, Barcelona, Spain
| | - Núria Farré
- Grup de Bases Metabòliques de Risc Cardiovascular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
| | - Sheila Ruiz-Nogales
- Grup de Bases Metabòliques de Risc Cardiovascular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
| | - Sergi Leánez
- Grup de Neurofarmacologia Molecular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
- Grup de Neurofarmacologia Molecular, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - José Luis Sánchez-Quesada
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, CIBERDEM, Barcelona, Spain
- Grup de Bioquímica Cardiovascular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
| | - Edgar Zapico
- Departament de Bioquímica, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
| | - Enrique Lerma
- Departament de Patologia, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
- Departament de Ciències Morfològiques, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Joan Carles Escolà-Gil
- Grup de Bases Metabòliques de Risc Cardiovascular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, CIBERDEM, Barcelona, Spain
| | - Francisco Blanco-Vaca
- Grup de Bases Metabòliques de Risc Cardiovascular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, CIBERDEM, Barcelona, Spain
| | - Jesús María Martín-Campos
- Grup de Bases Metabòliques de Risc Cardiovascular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, CIBERDEM, Barcelona, Spain
| | - Josep Julve
- Grup de Bases Metabòliques de Risc Cardiovascular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
- Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, CIBERDEM, Barcelona, Spain
- * E-mail: (JJ); (OP)
| | - Olga Pol
- Grup de Neurofarmacologia Molecular, Institut de Recerca de l’Hospital de la Santa Creu i Sant Pau & Institut d’Investigació Biomèdica Sant Pau (IIB Sant Pau), Barcelona, Spain
- Grup de Neurofarmacologia Molecular, Institut de Neurociències, Universitat Autònoma de Barcelona, Barcelona, Spain
- * E-mail: (JJ); (OP)
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8
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Chen F, Li DY, Zhang B, Sun JY, Sun F, Ji X, Qiu JC, Parker RB, Laizure SC, Xu J. Alterations of drug-metabolizing enzymes and transporters under diabetic conditions: what is the potential clinical significance? Drug Metab Rev 2018; 50:369-397. [PMID: 30221555 DOI: 10.1080/03602532.2018.1497645] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Feng Chen
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - De-Yi Li
- School of Life Sciences and Biopharmaceutics, Shenyang Pharmaceutical University, Shenyang, China
| | - Bo Zhang
- Department of Physiology, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jie-Yu Sun
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Fang Sun
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Xing Ji
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Jin-Chun Qiu
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
| | - Robert B. Parker
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - S. Casey Laizure
- Department of Clinical Pharmacy and Translational Science, College of Pharmacy, University of Tennessee Health Science Center, Memphis, TN, USA
| | - Jing Xu
- Department of Pharmacy, Children's Hospital of Nanjing Medical University, Nanjing, China
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9
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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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10
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Errico TL, Méndez-Lara KA, Santos D, Cabrerizo N, Baila-Rueda L, Metso J, Cenarro A, Pardina E, Lecube A, Jauhiainen M, Peinado-Onsurbe J, Escolà-Gil JC, Blanco-Vaca F, Julve J. LXR-dependent regulation of macrophage-specific reverse cholesterol transport is impaired in a model of genetic diabesity. Transl Res 2017; 186:19-35.e5. [PMID: 28583767 DOI: 10.1016/j.trsl.2017.05.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Accepted: 05/11/2017] [Indexed: 12/26/2022]
Abstract
Diabesity and fatty liver have been associated with low levels of high-density lipoprotein cholesterol, and thus could impair macrophage-specific reverse cholesterol transport (m-RCT). Liver X receptor (LXR) plays a critical role in m-RCT. Abcg5/g8 sterol transporters, which are involved in cholesterol trafficking into bile, as well as other LXR targets, could be compromised in the livers of obese individuals. We aimed to determine m-RCT dynamics in a mouse model of diabesity, the db/db mice. These obese mice displayed a significant retention of macrophage-derived cholesterol in the liver and reduced fecal cholesterol elimination compared with nonobese mice. This was associated with a significant downregulation of the hepatic LXR targets, including Abcg5/g8. Pharmacologic induction of LXR promoted the delivery of total tracer output into feces in db/db mice, partly due to increased liver and small intestine Abcg5/Abcg8 gene expression. Notably, a favorable upregulation of the hepatic levels of ABCG5/G8 and NR1H3 was also observed postoperatively in morbidly obese patients, suggesting a similar LXR impairment in these patients. In conclusion, our data show that downregulation of the LXR axis impairs cholesterol transfer from macrophages to feces in db/db mice, whereas the induction of the LXR axis partly restores impaired m-RCT by elevating the liver and small intestine expressions of Abcg5/g8.
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Affiliation(s)
- Teresa L Errico
- Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - Institut d'Investigacions Biomèdiques Sant Pau (IIB-Sant Pau), Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Karen Alejandra Méndez-Lara
- Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - Institut d'Investigacions Biomèdiques Sant Pau (IIB-Sant Pau), Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - David Santos
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Madrid, Spain
| | - Núria Cabrerizo
- Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - Institut d'Investigacions Biomèdiques Sant Pau (IIB-Sant Pau), Barcelona, Spain
| | - Lucía Baila-Rueda
- CIBER de Enfermedades Cardiovasculares, Madrid, Spain; Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Zaragoza, Spain
| | - Jari Metso
- National Institute for Health and Welfare, Genomics and Biomarkers unit, and Minerva Foundation Institute for medical Research, Biomedicum, Helsinki, Finland
| | - Ana Cenarro
- CIBER de Enfermedades Cardiovasculares, Madrid, Spain; Unidad Clínica y de Investigación en Lípidos y Arteriosclerosis, Hospital Universitario Miguel Servet, Instituto de Investigación Sanitaria Aragón (IIS Aragón), Zaragoza, Spain
| | - Eva Pardina
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Albert Lecube
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Madrid, Spain; Unitat de Recerca en Diabetes i Metabolisme, Institut de Recerca Hospital Universitari Vall d'Hebron, Barcelona, Spain
| | - Matti Jauhiainen
- National Institute for Health and Welfare, Genomics and Biomarkers unit, and Minerva Foundation Institute for medical Research, Biomedicum, Helsinki, Finland
| | - Julia Peinado-Onsurbe
- Departament de Bioquímica i Biomedicina Molecular, Facultat de Biologia, Universitat de Barcelona, Barcelona, Spain
| | - Joan Carles Escolà-Gil
- Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - Institut d'Investigacions Biomèdiques Sant Pau (IIB-Sant Pau), Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Madrid, Spain
| | - Francisco Blanco-Vaca
- Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - Institut d'Investigacions Biomèdiques Sant Pau (IIB-Sant Pau), Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Madrid, Spain.
| | - Josep Julve
- Institut de Recerca de l'Hospital de la Santa Creu i Sant Pau - Institut d'Investigacions Biomèdiques Sant Pau (IIB-Sant Pau), Barcelona, Spain; Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain; CIBER de Diabetes y Enfermedades Metabólicas Asociadas, Madrid, Spain.
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Nyima T, Müller M, Hooiveld GJEJ, Morine MJ, Scotti M. Nonlinear transcriptomic response to dietary fat intake in the small intestine of C57BL/6J mice. BMC Genomics 2016; 17:106. [PMID: 26861690 PMCID: PMC4748552 DOI: 10.1186/s12864-016-2424-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Accepted: 02/02/2016] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND A high caloric diet, in conjunction with low levels of physical activity, promotes obesity. Many studies are available regarding the relation between dietary saturated fats and the etiology of obesity, but most focus on liver, muscle and white adipose tissue. Furthermore, the majority of transcriptomic studies seek to identify linear effects of an external stimulus on gene expression, although such an assumption does not necessarily hold. Our work assesses the dose-dependent effects of dietary fat intake on differential gene expression in the proximal, middle and distal sections of the small intestine in C57BL/6J mice. Gene expression is analyzed in terms of either linear or nonlinear responses to fat intake. RESULTS The highest number of differentially expressed genes was observed in the middle section. In all intestine sections, most of the identified processes exhibited a linear response to increasing fat intake. The relative importance of logarithmic and exponential responses was higher in the proximal and distal sections, respectively. Functional enrichment analysis highlighted a constantly linear regulation of acute-phase response along the whole small intestine, with up-regulation of Serpina1b. The study of gene expression showed that exponential down-regulation of cholesterol transport in the middle section is coupled with logarithmic up-regulation of cholesterol homeostasis. A shift from linear to exponential response was observed in genes involved in the negative regulation of caspase activity, from middle to distal section (e.g., Birc5, up-regulated). CONCLUSIONS The transcriptomic signature associated with inflammatory processes preserved a linear response in the whole small intestine (e.g., up-regulation of Serpina1b). Processes related to cholesterol homeostasis were particularly active in the middle small intestine and only the highest fat intake down-regulated cholesterol transport and efflux (with a key role played by the down-regulation of ATP binding cassette transporters). Characterization of nonlinear patterns of gene expression triggered by different levels of dietary fat is an absolute novelty in intestinal studies. This approach helps identifying which processes are overloaded (i.e., positive, logarithmic regulation) or arrested (i.e., negative, exponential regulation) in response to excessive fat intake, and can shed light on the relationships linking lipid intake to obesity and its associated molecular disturbances.
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Affiliation(s)
- Tenzin Nyima
- The Microsoft Research - University of Trento Centre for Computational and Systems Biology, Rovereto, Italy.
| | - Michael Müller
- Nutrition, Metabolism and Genomics group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands. .,Norwich Medical School, University of East Anglia, Norwich, UK.
| | - Guido J E J Hooiveld
- Nutrition, Metabolism and Genomics group, Division of Human Nutrition, Wageningen University, Wageningen, The Netherlands.
| | - Melissa J Morine
- The Microsoft Research - University of Trento Centre for Computational and Systems Biology, Rovereto, Italy.
| | - Marco Scotti
- The Microsoft Research - University of Trento Centre for Computational and Systems Biology, Rovereto, Italy. .,GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany.
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12
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Altered Expression of Transporters, its Potential Mechanisms and Influences in the Liver of Rodent Models Associated with Diabetes Mellitus and Obesity. Eur J Drug Metab Pharmacokinet 2015; 41:199-210. [PMID: 26597190 DOI: 10.1007/s13318-015-0306-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Diabetes mellitus is becoming an increasingly prevalent disease that concerns patients and healthcare professionals worldwide. Among many anti-diabetic agents in clinical uses, numerous reports are available on their altered pharmacokinetics because of changes in the expression of drug transporters and metabolic enzymes under diabetic states. These changes may affect the safety and efficacy of therapeutic agents and/or drug-drug interaction with co-administered agents. Therefore, the changes in transporter expression should be identified, and the underlying mechanisms should be clarified. This review summarizes the progress of recent studies on the alterations in important uptake and efflux transporters in liver of diabetic animals and their regulatory pathways.
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Lambert JE, Ryan EA, Thomson ABR, Clandinin MT. De novo lipogenesis and cholesterol synthesis in humans with long-standing type 1 diabetes are comparable to non-diabetic individuals. PLoS One 2013; 8:e82530. [PMID: 24376543 PMCID: PMC3871159 DOI: 10.1371/journal.pone.0082530] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2013] [Accepted: 10/25/2013] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND Synthesis of lipid species, including fatty acids (FA) and cholesterol, can contribute to pathological disease. The purpose of this study was to investigate FA and cholesterol synthesis in individuals with type 1 diabetes, a group at elevated risk for vascular disease, using stable isotope analysis. METHODS Individuals with type 1 diabetes (n = 9) and age-, sex-, and BMI-matched non-diabetic subjects (n = 9) were recruited. On testing day, meals were provided to standardize food intake and elicit typical feeding responses. Blood samples were analyzed at fasting (0 and 24 h) and postprandial (2, 4, 6, and 8 hours after breakfast) time points. FA was isolated from VLDL to estimate hepatic FA synthesis, whereas free cholesterol (FC) and cholesteryl ester (CE) was isolated from plasma and VLDL to estimate whole-body and hepatic cholesterol synthesis, respectively. Lipid synthesis was measured using deuterium incorporation and isotope ratio mass spectrometry. RESULTS Fasting total hepatic lipogenesis (3.91 ± 0.90% vs. 5.30 ± 1.22%; P = 0.41) was not significantly different between diabetic and control groups, respectively, nor was synthesis of myristic (28.60 ± 4.90% vs. 26.66 ± 4.57%; P = 0.76), palmitic (12.52 ± 2.75% vs. 13.71 ± 2.64%; P = 0.65), palmitoleic (3.86 ± 0.91% vs. 4.80 ± 1.22%; P = 0.65), stearic (5.55 ± 1.04% vs. 6.96 ± 0.97%; P = 0.29), and oleic acid (1.45 ± 0.28% vs. 2.10 ± 0.51%; P = 0.21). Postprandial lipogenesis was also not different between groups (P = 0.38). Similarly, fasting synthesis of whole-body FC (8.2 ± 1.3% vs. 7.3 ± 0.8%/day; P = 0.88) and CE (1.9 ± 0.4% vs. 2.0 ± 0.3%/day; P = 0.96) and hepatic FC (8.2 ± 2.0% vs. 8.1 ± 0.8%/day; P = 0.72) was not significantly different between diabetic and control subjects. CONCLUSIONS Despite long-standing disease, lipogenesis and cholesterol synthesis was not different in individuals with type 1 diabetes compared to healthy non-diabetic humans.
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Affiliation(s)
- Jennifer E. Lambert
- Alberta Institute for Human Nutrition, University of Alberta, Edmonton, Alberta, Canada
- * E-mail:
| | - Edmond A. Ryan
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Alan B. R. Thomson
- Alberta Institute for Human Nutrition, University of Alberta, Edmonton, Alberta, Canada
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
| | - Michael T. Clandinin
- Alberta Institute for Human Nutrition, University of Alberta, Edmonton, Alberta, Canada
- Department of Medicine, University of Alberta, Edmonton, Alberta, Canada
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14
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Li J, Wang X, Liu H, Guo H, Zhang M, Mei D, Liu C, He L, Liu L, Liu X. Impaired hepatic and intestinal ATP-binding cassette transporter G5/8 was associated with high exposure of β-sitosterol and the potential risks to blood-brain barrier integrity in diabetic rats. ACTA ACUST UNITED AC 2013; 66:428-36. [PMID: 24237052 DOI: 10.1111/jphp.12178] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Accepted: 10/10/2013] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Plant sterols are thought to treat hypercholesterolemia via inhibiting intestinal cholesterol absorption. The aim of this study was to evaluate the contribution of impaired ATP-binding cassette transporter G5/8 (ABCG5/8) expression by diabetes to the increased β-sitosterol (BS) exposure and impact of increased BS on integrity of blood-brain barrier (BBB). METHODS Basal BS level in tissues of streptozotocin-inducted rats and ABCG5/8 protein levels in liver and intestine were investigated; pharmacokinetics of BS was studied following oral dose; and primarily cultured rat brain microvessel endothelial cells (rBMECs) were used to study BS transportation across BBB and effect of BS on BBB integrity. KEY FINDINGS Diabetic rats showed greatly upgraded basal levels of BS in plasma, intestine, cerebral and hippocampus, accompanied by impairment of ABCG5/8 protein expression in liver and intestine. Pharmacokinetics studies demonstrated higher AUC0-48 and Cmax , and lower faecal recoveries of BS after oral administration, indicating enhancement of absorption or efflux impairment. In-vitro data showed increased ratio of BS/cholesterol in high levels BS-treated rBMECs was associated with increased BBB permeability of some biomarkers including BS itself. CONCLUSIONS Impaired ABCG5/8 protein expression by diabetes led to increase in BS exposure, which may be harmful to BBB function.
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Affiliation(s)
- Jia Li
- Key Laboratory of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing, China
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15
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Xu X, So JS, Park JG, Lee AH. Transcriptional control of hepatic lipid metabolism by SREBP and ChREBP. Semin Liver Dis 2013; 33:301-11. [PMID: 24222088 PMCID: PMC4035704 DOI: 10.1055/s-0033-1358523] [Citation(s) in RCA: 184] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The liver is a central organ that controls systemic energy homeostasis and nutrient metabolism. Dietary carbohydrates and lipids, and fatty acids derived from adipose tissue are delivered to the liver, and utilized for gluconeogenesis, lipogenesis, and ketogenesis, which are tightly regulated by hormonal and neural signals. Hepatic lipogenesis is activated primarily by insulin that is secreted from the pancreas after a high-carbohydrate meal. Sterol regulatory element binding protein-1c (SREBP-1c) and carbohydrate-responsive element-binding protein (ChREBP) are major transcriptional regulators that induce key lipogenic enzymes to promote lipogenesis in the liver. Sterol regulatory element binding protein-1c is activated by insulin through complex signaling cascades that control SREBP-1c at both transcriptional and posttranslational levels. Carbohydrate-responsive element-binding protein is activated by glucose independently of insulin. Here, the authors attempt to summarize the current understanding of the molecular mechanism for the transcriptional regulation of hepatic lipogenesis, focusing on recent studies that explore the signaling pathways controlling SREBPs and ChREBP.
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Affiliation(s)
| | | | | | - Ann-Hwee Lee
- To whom correspondence should be addressed: Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA. , Tel: 1-212-746-9087
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16
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Hismiogullari AA, Hismiogullari SE, Rahman K. Isolation and biochemical analysis of vesicles from taurohyodeoxycholic acid-infused isolated perfused rat livers. World J Gastroenterol 2013; 19:6228-6236. [PMID: 24115821 PMCID: PMC3787354 DOI: 10.3748/wjg.v19.i37.6228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2013] [Revised: 06/12/2013] [Accepted: 07/05/2013] [Indexed: 02/06/2023] Open
Abstract
AIM: To isolate biliary lipid-carrying vesicles from isolated perfused rat livers after taurohyodeoxycholic acid (THDC) infusion. Biliary lipid vesicles have been implicated in hepatic disease and THDC was used since it increases biliary phospholipid secretion.
METHODS: Rat livers were isolated and perfused via the hepatic portal vein with THDC dissolved in Krebs Ringer Bicarbonate solution, pH 7.4, containing 1 mmol/L CaCl2, 5 mmol/L glucose, a physiological amino acid mixture, 1% bovine serum albumin and 20% (v/v) washed human erythrocytes at a rate of 2000 nmol/min for 2 h. The livers were then removed, homogenized and subjected to centrifugation, and the microsomal fraction was obtained and further centrifuged at 350000 g for 90 min to obtain subcellular fractions. These were analyzed for total phospholipid, cholesterol, protein and alkaline phosphodiesterase I (PDE).
RESULTS: No significant changes were observed in the total phospholipid, cholesterol and protein contents of the gradient fractions obtained from the microsomal preparation. However, the majority of the gradient fractions (ρ= 1.05-1.07 g/mL and ρ = 1.95-1.23 g/mL) obtained from THDC-infused livers had significantly higher PDE activity compared to the control livers. The low density gradient fraction (ρ = 1.05-1.07 g/mL) which was envisaged to contain the putative vesicle population isolated from THDC-perfused livers had relatively small amounts of phospholipids and protein when compared to the relevant control fractions; however, they displayed an increase in cholesterol and PDE activity. The phospholipids were also isolated by thin layer chromatography and subjected to fractionation by high performance liquid chromatography; however, no differences were observed in the pattern of the fatty acid composition of the phospholipids isolated from THDC and control perfused livers. The density gradient fractions (ρ = 1.10-1.23 g/mL) displayed an increase in all the parameters measured from both control and THDC-infused livers.
CONCLUSION: No significant changes in biliary lipids were observed in the fractions from THDC-infused livers; however, PDE activity was significantly increased compared to the control livers.
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Zhu J, Qin Y, Liu T, Wang J, Zheng X. Prioritization of candidate disease genes by topological similarity between disease and protein diffusion profiles. BMC Bioinformatics 2013; 14 Suppl 5:S5. [PMID: 23734762 PMCID: PMC3622672 DOI: 10.1186/1471-2105-14-s5-s5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Identification of gene-phenotype relationships is a fundamental challenge in human health clinic. Based on the observation that genes causing the same or similar phenotypes tend to correlate with each other in the protein-protein interaction network, a lot of network-based approaches were proposed based on different underlying models. A recent comparative study showed that diffusion-based methods achieve the state-of-the-art predictive performance. RESULTS In this paper, a new diffusion-based method was proposed to prioritize candidate disease genes. Diffusion profile of a disease was defined as the stationary distribution of candidate genes given a random walk with restart where similarities between phenotypes are incorporated. Then, candidate disease genes are prioritized by comparing their diffusion profiles with that of the disease. Finally, the effectiveness of our method was demonstrated through the leave-one-out cross-validation against control genes from artificial linkage intervals and randomly chosen genes. Comparative study showed that our method achieves improved performance compared to some classical diffusion-based methods. To further illustrate our method, we used our algorithm to predict new causing genes of 16 multifactorial diseases including Prostate cancer and Alzheimer's disease, and the top predictions were in good consistent with literature reports. CONCLUSIONS Our study indicates that integration of multiple information sources, especially the phenotype similarity profile data, and introduction of global similarity measure between disease and gene diffusion profiles are helpful for prioritizing candidate disease genes. AVAILABILITY Programs and data are available upon request.
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Affiliation(s)
- Jie Zhu
- Department of Mathematics, Shanghai Normal University, Shanghai, China
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18
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Freark de Boer J, Annema W, Schreurs M, van der Veen JN, van der Giet M, Nijstad N, Kuipers F, Tietge UJF. Type I diabetes mellitus decreases in vivo macrophage-to-feces reverse cholesterol transport despite increased biliary sterol secretion in mice. J Lipid Res 2011; 53:348-357. [PMID: 22180634 DOI: 10.1194/jlr.m018671] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Type I diabetes mellitus (T1DM) increases atherosclerotic cardiovascular disease; however, the underlying pathophysiology is still incompletely understood. We investigated whether experimental T1DM impacts HDL-mediated reverse cholesterol transport (RCT). C57BL/6J mice with alloxan-induced T1DM had higher plasma cholesterol levels (P < 0.05), particularly within HDL, and increased hepatic cholesterol content (P < 0.001). T1DM resulted in increased bile flow (2.1-fold; P < 0.05) and biliary secretion of bile acids (BA, 10.5-fold; P < 0.001), phospholipids (4.5-fold; P < 0.001), and cholesterol (5.5-fold; P < 0.05). Hepatic cholesterol synthesis was unaltered, whereas BA synthesis was increased in T1DM (P < 0.001). Mass fecal BA output was significantly higher in T1DM mice (1.5-fold; P < 0.05), fecal neutral sterol excretion did not change due to increased intestinal cholesterol absorption (2.1-fold; P < 0.05). Overall in vivo macrophage-to-feces RCT, using [(3)H]cholesterol-loaded primary mouse macrophage foam cells, was 20% lower in T1DM (P < 0.05), mainly due to reduced tracer excretion within BA (P < 0.05). In vitro experiments revealed unchanged cholesterol efflux toward T1DM HDL, whereas scavenger receptor class BI-mediated selective uptake from T1DM HDL was lower in vitro and in vivo (HDL kinetic experiments) (P < 0.05), conceivably due to increased glycation of HDL-associated proteins (+65%, P < 0.01). In summary, despite higher mass biliary sterol secretion T1DM impairs macrophage-to-feces RCT, mainly by decreasing hepatic selective uptake, a mechanism conceivably contributing to increased cardiovascular disease in T1DM.
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Affiliation(s)
- Jan Freark de Boer
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, Groningen, The Netherlands
| | - Wijtske Annema
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, Groningen, The Netherlands; Top Institute Food and Nutrition, Wageningen, The Netherlands
| | - Marijke Schreurs
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, Groningen, The Netherlands; Department of Pathology and Medical Biology, Medical Biology Section, Molecular Genetics, University Medical Center Groningen, Groningen, The Netherlands
| | - Jelske N van der Veen
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, Groningen, The Netherlands
| | - Markus van der Giet
- Medizinische Klinik IV-Nephrology, Charite-Campus Benjamin Franklin, Berlin, Germany
| | - Niels Nijstad
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, Groningen, The Netherlands
| | - Folkert Kuipers
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, Groningen, The Netherlands; Department of Laboratory Medicine, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands;, University Medical Center Groningen, Groningen, The Netherlands
| | - Uwe J F Tietge
- Department of Pediatrics, Center for Liver, Digestive, and Metabolic Diseases, University Medical Center Groningen, Groningen, The Netherlands; Top Institute Food and Nutrition, Wageningen, The Netherlands.
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The chylomicron: relationship to atherosclerosis. Int J Vasc Med 2011; 2012:784536. [PMID: 22007304 PMCID: PMC3189596 DOI: 10.1155/2012/784536] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2011] [Accepted: 08/08/2011] [Indexed: 12/20/2022] Open
Abstract
The B-containing lipoproteins are the transporters of cholesterol, and the evidence suggests that the apo B48-containing postprandial chylomicron particles and the triglyceride-rich very low density lipoprotein (VLDL) particles play an important part in the development of the plaque both directly and indirectly by their impact on LDL composition. The ratio of dietary to synthesised cholesterol is variable but tightly regulated: hence intervention with diet at best reduces serum cholesterol by <20% andusually <10%. Statins are the mainstay of cholesterol reduction therapy, but they increase cholesterol absorption, an example of the relationship between synthesis and absorption. Inhibition of cholesterol absorption with Ezetimibe, an inhibitor of Niemann Pick C1-like 1 (NPC1-L1), the major regulator of cholesterol absorption, increases cholesterol synthesis and hence the value of adding an inhibitor of cholesterol absorption to an inhibitor of cholesterol synthesis. Apo B48, the structural protein of the chylomicron particle, is synthesised in abundance so that the release of these particles is dependent on the amount of cholesterol and triglyceride available in the intestine. This paper will discuss cholesterol absorption and synthesis, chylomicron formation, and the effect of postprandial lipoproteins on factors involved in atherosclerosis.
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Tomkin GH. Dyslipidaemia--hepatic and intestinal cross-talk. ATHEROSCLEROSIS SUPP 2011; 11:5-9. [PMID: 20434963 DOI: 10.1016/j.atherosclerosissup.2010.03.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 03/25/2010] [Indexed: 01/22/2023]
Abstract
Cholesterol metabolism is tightly regulated with the majority of de novo cholesterol synthesis occurring in the liver and intestine. 3 Hydroxy-3-methylglutaryl coenzyme A reductase, a major enzyme involved in cholesterol synthesis, is raised in both liver and intestine in diabetic animals. Niemann PickC1-like1 protein regulates cholesterol absorption in the intestine and facilitates cholesterol transport through the liver. There is evidence to suggest that the effect of inhibition of Niemann PickC1-like1 lowers cholesterol through its effect not only in the intestine but also in the liver. ATP binding cassette proteins G5/G8 regulate cholesterol re-excretion in the intestine and in the liver, cholesterol excretion into the bile. Diabetes is associated with reduced ATP binding cassette protein G5/G8 expression in both the liver and intestine in animal models. Microsomal triglyceride transfer protein is central to the formation of the chylomicron in the intestine and VLDL in the liver. Microsomal triglyceride transfer protein mRNA is increased in diabetes in both the intestine and liver. Cross-talk between the intestine and liver is poorly documented in humans due to the difficulty in obtaining liver biopsies but animal studies are fairly consistent in showing relationships that explain in part mechanisms involved in cholesterol homeostasis.
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Affiliation(s)
- Gerald H Tomkin
- Trinity College Dublin and Diabetes Institute of Ireland, Beacon Hospital, Sandyford, Clontra, Quinns Road, Shankill Co, Dublin, Ireland. ,
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Gylling H, Hallikainen M, Pihlajamäki J, Simonen P, Kuusisto J, Laakso M, Miettinen TA. Insulin sensitivity regulates cholesterol metabolism to a greater extent than obesity: lessons from the METSIM Study. J Lipid Res 2010; 51:2422-7. [PMID: 20436182 DOI: 10.1194/jlr.p006619] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cholesterol synthesis is upregulated and absorption downregulated in insulin resistance and in type 2 diabetes. We investigated whether alterations in cholesterol metabolism are observed across the glucose tolerance status, from normoglycemia through impaired glucose tolerance to type 2 diabetes, in 781 randomly selected men 45 to 70 years of age from a population-based Metabolic Syndrome in Men Study. Cholesterol metabolism was assayed using surrogate serum markers, squalene, and noncholesterol sterols. The study population was classified into subgroups according to glucose tolerance as follows: normoglycemia, impaired fasting glucose, impaired glucose tolerance, and type 2 diabetes. LDL cholesterol did not differ between the groups. Cholesterol synthesis markers were lowest and absorption markers highest in normoglycemia. Sitosterol was lower in subjects with impaired fasting glucose compared with normoglycemic subjects (113 +/- 7 vs. 136 +/- 3 10(2) mumol/mmol of cholesterol, P < 0.05). LDL cholesterol was not associated with lathosterol/sitosterol ratio, a marker of cholesterol metabolism. Peripheral insulin sensitivity evaluated by the Matsuda index was associated with the lathosterol/sitosterol ratio in the entire population (r = -0.457, P < 0.001) and with that of lathosterol/cholestanol independently of obesity. In conclusion, cholesterol metabolism was altered already from subjects with impaired fasting glucose. Upregulated cholesterol synthesis was associated with peripheral insulin resistance independent of obesity.
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Affiliation(s)
- Helena Gylling
- Department of Clinical Nutrition, University of Eastern Finland, PO Box 1627, FI-70211 Kuopio, Finland.
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Differences in hepatic expression of genes involved in lipid homeostasis between hereditary hypertriglyceridemic rats and healthy Wistar rats and in their response to dietary cholesterol. Food Chem Toxicol 2009; 47:2624-30. [DOI: 10.1016/j.fct.2009.07.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 07/15/2009] [Accepted: 07/21/2009] [Indexed: 11/22/2022]
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Tabák AG, Tamás G, Péterfalvi A, Bosnyák Z, Madarász E, Rákóczi I, Kerényi Z. The effect of paternal and maternal history of diabetes mellitus on the development of gestational diabetes mellitus. J Endocrinol Invest 2009; 32:606-10. [PMID: 19498321 DOI: 10.1007/bf03346517] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
BACKGROUND There is an ongoing debate whether maternal diabetes is a more important risk factor for gestational diabetes (GDM) development than paternal diabetes. AIM To describe the risk of GDM associated with paternal and maternal diabetes, and to further characterise GDM women with maternal diabetes. SUBJECTS AND METHODS Case-control study within a population-based GDM screening program in an urban area of Hungary in 2002-2003. All GDM women (no.=133) and an age-matched control group (no.=135) with a mean age of 31 years was evaluated. Blood pressure, anthropometric data, and blood glucose values from a 75 g Oral Glucose Tolerance Test (OGTT) were recorded at 24-28 weeks of gestation. Family history data were by self-report. RESULTS Known paternal diabetes was not related to GDM risk [odds ratio (OR) 0.83, 95% confidence interval (CI) 0.35-2.00]. Known maternal diabetes (OR 2.90, 95% CI 0.99-8.49) and diabetes in the maternal line (OR 2.83, 95% CI 1.16-6.89) were both related to GDM after adjustment for body mass index (BMI). GDM women with known maternal diabetes had a higher BMI, 31.6 [9.1] kg/m2 median [interquartile range], than GDM women with or without diabetes in the maternal line, 26.1 [4.9] and 26.3 [6.1] kg/m2, respectively, while figures for fasting glucose during OGTT were 5.2 [0.7] vs 4.4 [1.1] vs 4.9 [0.8] mmol/l respectively (all p<0.05). CONCLUSIONS Maternal history of diabetes and history of diabetes in the maternal line seems to be a stronger predictor of GDM than paternal history.
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Affiliation(s)
- A G Tabák
- National Centre for Diabetes Care, Budapest, Hungary.
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25
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Abstract
Cholesterol available for bile secretion is controlled by a wide variety of proteins that mediate lipoprotein cholesterol uptake and cholesterol transport and metabolism in the liver. From a disease perspective, abnormalities in the transhepatic traffic of cholesterol from plasma into the bile may influence the risk of cholesterol gallstone formation. This review summarizes some recent progress in understanding the hepatic determinants of biliary cholesterol secretion and its potential pathogenic implications in cholesterol gallstone disease. This information together with new discoveries in this field may lead to improved risk evaluation, novel surrogate markers and earlier diagnosis, better preventive approaches and more effective pharmacological therapies for this prevalent human disease.
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Affiliation(s)
- Silvana Zanlungo
- Departamento de Gastroenterología, Facultad de Medicina, Pontificia Universidad Católica, Santiago, Chile
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26
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Scoggan KA, Gruber H, Chen Q, Plouffe LJ, Lefebvre JM, Wang B, Bertinato J, L'Abbé MR, Hayward S, Ratnayake WN. Increased incorporation of dietary plant sterols and cholesterol correlates with decreased expression of hepatic and intestinal Abcg5 and Abcg8 in diabetic BB rats. J Nutr Biochem 2009; 20:177-86. [DOI: 10.1016/j.jnutbio.2008.01.011] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Revised: 01/29/2008] [Accepted: 01/31/2008] [Indexed: 10/22/2022]
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27
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Hsieh J, Hayashi AA, Webb J, Adeli K. Postprandial dyslipidemia in insulin resistance: Mechanisms and role of intestinal insulin sensitivity. ATHEROSCLEROSIS SUPP 2008; 9:7-13. [DOI: 10.1016/j.atherosclerosissup.2008.05.011] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 03/03/2008] [Accepted: 05/13/2008] [Indexed: 02/08/2023]
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28
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The intestine as a regulator of cholesterol homeostasis in diabetes. ATHEROSCLEROSIS SUPP 2008; 9:27-32. [PMID: 18693145 DOI: 10.1016/j.atherosclerosissup.2008.05.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 02/27/2008] [Accepted: 05/13/2008] [Indexed: 11/24/2022]
Abstract
The chylomicron influences very low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) composition but itself is atherogenic. Thus abnormalities of chylomicron production are of interest particularly in conditions such as diabetes which confer major cardiovascular risk. Intestinal function is abnormal in diabetes and is a major cause of the dyslipidaemia found in this condition. Studies have suggested that cholesterol absorption is decreased in diabetes and cholesterol synthesis increased. Molecular mechanisms involved in insulin resistance in the intestine and its effect on cholesterol homeostasis in diabetes are described. Abnormalities in triglyceride synthesis and alterations genes regulating cholesterol absorption and intestinal synthesis are discussed. In particular, increase in apolipoprotein B48 synthesis has been demonstrated in animal models of diabetes and insulin resistance. Intestinal mRNA expression of Niemann Pick C1-like 1, protein is increased in both experimental and human diabetes suggesting that an increase in cholesterol transportation does occur. mRNA expression of the ATP binding cassette proteins (ABC) G5 and G8, two proteins working in tandem to excrete cholesterol have been shown to be decreased suggesting increased delivery of cholesterol for absorption. Expression of microsomal triglyceride transfer protein, which assembles the chylomicron particle, is increased in diabetes leading to increase in both number and cholesterol content. In conclusion, diabetes is associated with considerable dysfunction of the intestine leading to abnormal chylomicron composition which may play a major part in the premature development of atherosclerosis.
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Sittiwet C, Gylling H, Hallikainen M, Pihlajamäki J, Moilanen L, Laaksonen DE, Niskanen L, Agren JJ, Laakso M, Miettinen TA. Cholesterol metabolism and non-cholesterol sterol distribution in lipoproteins of type 1 diabetes: The effect of improved glycemic control. Atherosclerosis 2007; 194:465-72. [PMID: 16996519 DOI: 10.1016/j.atherosclerosis.2006.08.044] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 08/15/2006] [Accepted: 08/23/2006] [Indexed: 11/22/2022]
Abstract
In type 1 diabetes, the ratios to cholesterol of serum absorption markers, e.g., cholestanol, are elevated and those of synthesis markers, e.g., lathosterol, are reduced suggesting perturbed cholesterol metabolism. We studied 17 subjects with type 1 diabetes in poor glycemic control at baseline to assess whether improvement of glycemic control affects lathosterol and cholestanol ratios to cholesterol and their distribution in lipoproteins. Cholesterol and the non-cholesterol sterols were assayed directly from serum, and free and ester fractions after thin-layer chromatographic separation of lipoprotein sterols with gas-liquid chromatography. After the 2-6 months follow-up, the mean value of HbA1(c) decreased from 10.8% to 8.6% (p=0.001). Even though the concentrations of serum and lipoprotein cholesterol remained unchanged, the serum lathosterol to cholesterol ratio increased by 28% (p<0.05) and the lathosterol/cholestanol proportion by 23% (p<0.05). The ratios of total and esterified lathosterol to cholesterol in serum, chylomicrons and LDL, and free lathosterol to cholesterol in serum and IDL, were negatively associated with HbA1(c) at baseline and after follow-up, suggesting that the better glycemic control, the higher was cholesterol synthesis. The absorption markers were less consistently associated with HbA1(c). About half of the serum lathosterol and cholestanol was carried in LDL and one-fourth to one-fifth in HDL, but the lathosterol ratios were roughly similar in all lipoproteins. In contrast, cholestanol accumulated in chylomicrons and HDL. Glycemic control did not affect the distributions of lathosterol and cholestanol. In conclusion, improvement in glycemic control increased cholesterol synthesis, but had no effect on cholesterol absorption as measured by the serum or lipoprotein cholestanol to cholesterol ratio. From a clinical point of view, the better the glycemic control, the more antiatherogenic cholesterol metabolism may be in type 1 diabetes.
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Affiliation(s)
- Chaiyasit Sittiwet
- Department of Medicine, Division of Internal Medicine, University of Helsinki, Helsinki, Finland
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30
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Gylling H, Laaksonen DE, Atalay M, Hallikainen M, Niskanen L, Miettinen TA. Markers of absorption and synthesis of cholesterol in men with type 1 diabetes. Diabetes Metab Res Rev 2007; 23:372-7. [PMID: 17080398 DOI: 10.1002/dmrr.697] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND AND METHODS Serum cholestanol and plant sterol ratios to cholesterol, surrogate markers of cholesterol absorption, are assumed to be high in type 1 diabetes (T1D), and the ratios of cholesterol precursor sterols (markers of synthesis) are assumed to be low reflecting downregulated cholesterol synthesis. To this end, we measured serum sterols with gas-liquid-chromatography in 56 men with T1D and in 18 controls to evaluate cholesterol metabolism. Subjects were categorised into tertiles by the cholestanol to cholesterol ratio of controls indicating low to high absorption of cholesterol. RESULTS The ratios of the synthesis markers were negatively related to the absorption markers in controls, but less consistently in T1D. The absorption markers were positively related to each other, but interrelation of the synthesis markers was less consistent in T1D. In the low absorbers the absorption markers were higher in T1D than in controls (e.g. sitosterol ratio 173 +/- 9 in T1D vs 135 +/- 11 10(2) x mmol/mol of cholesterol in controls, p < 0.05). In the high absorbers, the absorption markers were similar in T1D and controls, but the synthesis markers were higher in T1D than in controls (e.g. lathosterol ratio 154 +/- 10 in T1D vs 120 +/- 5 10(2) x mmol/mol of cholesterol in controls, p < 0.05). CONCLUSIONS Absorption and synthesis of cholesterol are less closely related to each other in T1D than in controls, but the markers of cholesterol absorption are interrelated also in T1D. Absorption of cholesterol is higher in T1D than in controls within the range of low absorption, but similar in those with relatively high cholesterol absorption.
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Affiliation(s)
- Helena Gylling
- Department of Clinical Nutrition, University of Kuopio, Kuopio, Finland
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31
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Lally S, Owens D, Tomkin GH. Genes that affect cholesterol synthesis, cholesterol absorption, and chylomicron assembly: the relationship between the liver and intestine in control and streptozotosin diabetic rats. Metabolism 2007; 56:430-8. [PMID: 17292734 DOI: 10.1016/j.metabol.2006.10.028] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2006] [Accepted: 10/13/2006] [Indexed: 11/27/2022]
Abstract
Chylomicrons and very low-density lipoproteins (VLDLs) are abnormal in diabetes. The aim of this study was to compare the expression of Niemann-Pick C1-like1 (NPC1L1), adenosine triphosphate-binding cassette (ABC) proteins G5 and G8, microsomal triglyceride transfer protein (MTP), and 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase in the fasting and fed states in nondiabetic Sprague-Dawley rats fed a high-fat/cholesterol diet and to examine the messenger RNA (mRNA) expression of these proteins in the liver and intestine of diabetic and control animals using streptozotosin diabetic cholesterol-fed rats. Chylomicron and VLDL concentrations were significantly lower after a 12-hour fast in fasted compared with fed rats (P < .02). There was no change with fasting in mRNA expression of any of the genes in the intestine, but MTP level was significantly lower in the liver after the 12-hour fast (P < .01). There was a positive correlation between intestinal NPC1L1 mRNA and chylomicron cholesterol (P < .01) and between hepatic NPC1L1 mRNA and VLDL cholesterol (P < .01). The diabetic rats had significantly higher chylomicron and VLDL cholesterol, triglyceride, and apolipoprotein B-48 and B-100 levels compared with control rats (P < .0001). They had significantly increased NPC1L1 and MTP mRNA in both liver and intestine (P < .05 and P < .0005, respectively), and ABCG5 and ABCG8 mRNA were significantly reduced (P < .05). HMGCoA reductase mRNA was increased in diabetic animals (P < .01). In conclusion, fasting intestinal gene expression reflects the fed state. In diabetes, intestinal and hepatic gene expression correlates with abnormalities in chylomicron and VLDL cholesterol.
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Affiliation(s)
- Sean Lally
- Department of Diabetes and Endocrinology, Trinity College, Dublin 18, Ireland
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32
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Hazard SE, Patel SB. Sterolins ABCG5 and ABCG8: regulators of whole body dietary sterols. Pflugers Arch 2007; 453:745-52. [PMID: 16440216 PMCID: PMC1785388 DOI: 10.1007/s00424-005-0040-7] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 12/13/2005] [Accepted: 12/23/2005] [Indexed: 12/12/2022]
Abstract
ABCG5 and ABCG8 are two ATP-binding cassette half-transporters that belong to the G family members. They were identified as proteins that are mutated in a rare human disorder, sitosterolemia, and their identification led to the completion of the physiological pathways by which dietary cholesterol, as well as noncholesterol sterols, traffics in the mammalian body. These proteins are likely to function as heterodimers, and current evidence suggests that these proteins are responsible for the majority of sterol secretions into bile, thus may define the long sought-after biliary sterol transporters. This review will focus on some of the backgrounds of this physiology, the genetics and regulation of these genes, as well as our current understanding of their functions. This review will also highlight the current limitations in our knowledge gap.
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Affiliation(s)
- Starr E Hazard
- Biomolecular Computing Resource, Medical University of South Carolina, Charleston, SC 29403, USA
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Abstract
A hallmark of atherosclerotic cardiovascular disease (CVD) is the accumulation of cholesterol in arterial macrophages. Factors that modulate circulating and tissue cholesterol levels have major impacts on initiation, progression, and regression of CVD. Four members of the ATP-binding cassette (ABC) transporter family play important roles in this modulation. ABCA1 and ABCG1 export excess cellular cholesterol into the HDL pathway and reduce cholesterol accumulation in macrophages. ABCG5 and ABCG8 form heterodimers that limit absorption of dietary sterols in the intestine and promote cholesterol elimination from the body through hepatobiliary secretion. All 4 transporters are induced by the same sterol-sensing nuclear receptor system. ABCA1 expression and activity are also highly regulated posttranscriptionally by diverse processes. ABCA1 mutations can cause a severe HDL-deficiency syndrome characterized by cholesterol deposition in tissue macrophages and prevalent atherosclerosis. ABCG5 or ABCG8 mutations can cause sitosterolemia, in which patients accumulate cholesterol and plant sterols in the circulation and develop premature CVD. Disrupting Abca1 or Abcg1 in mice promotes accumulation of excess cholesterol in macrophages, and manipulating mouse macrophage ABCA1 expression affects atherogenesis. Overexpressing ABCG5 and ABCG8 in mice attenuates diet-induced atherosclerosis in association with reduced circulating and liver cholesterol. Metabolites elevated in individuals with the metabolic syndrome and diabetes destabilize ABCA1 protein and inhibit transcription of all 4 transporters. Thus, impaired ABC cholesterol transporters might contribute to the enhanced atherogenesis associated with common inflammatory and metabolic disorders. Their beneficial effects on cholesterol homeostasis have made these transporters important new therapeutic targets for preventing and reversing CVD.
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Affiliation(s)
- John F Oram
- Department of Medicine, Box 356426, University of Washington, Seattle, WA 98195-6426, USA.
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34
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Lally S, Owens D, Tomkin GH. The different effect of pioglitazone as compared to insulin on expression of hepatic and intestinal genes regulating post-prandial lipoproteins in diabetes. Atherosclerosis 2006; 193:343-51. [PMID: 17109865 DOI: 10.1016/j.atherosclerosis.2006.09.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/16/2006] [Revised: 08/30/2006] [Accepted: 09/27/2006] [Indexed: 10/23/2022]
Abstract
This study investigates lipoprotein composition in diabetes before and after treatment with insulin or pioglitazone and its relationship to gene expression of five genes found in liver and intestine which are involved in cholesterol homeostasis. Thirty zucker diabetic fatty fa/fa and 10 lean rats were examined. mRNA for 3-hydroxy3-methylglutaryl coenzyme A reductase (HMGCoA), microsomal triglyceride transfer protein (MTTP), Niemann Pick C1-like 1 (NPC1L1) and ATP binding cassette transporters (ABC) G5 and G8 was determined using real-time, reverse transcriptase (RT-PCR). Cholesterol, triglyceride, apo B48 and apo B100 were elevated in chylomicrons and very low density lipoproteins (VLDL) of untreated diabetic animals (p<0.02). For similar blood glucose pioglitazone was more effective than insulin in normalising the lipoproteins. In diabetic animals, HMGCoA reductase, MTTP and NPC1L1 mRNA were significantly elevated (p<0.02) and ABCG5 and ABCG8 were significantly reduced (p<0.02) in the liver. Pioglitazone significantly reduced hepatic MTTP and NPC1L1 mRNA (p<0.0001) and significantly increased ABCG5 and G8 mRNA (p<0.0001) as compared to insulin. In conclusion diabetes was associated with major changes in mRNA levels of proteins involved in the regulation of post-prandial lipoproteins. Pioglitazone and insulin have different effects on post-prandial lipoprotein metabolism in part due their effect on genes regulating cholesterol synthesis and lipoprotein assembly.
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Affiliation(s)
- S Lally
- Department of Diabetes and Endocrinology, Trinity College, Dublin 2, Ireland
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Järvisalo M, Raitakari O, Gylling H, Miettinen TA. Cholesterol absorption and synthesis in children with type 1 diabetes. Diabetes Care 2006; 29:2300-4. [PMID: 17003310 DOI: 10.2337/dc05-2235] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVE The levels of the surrogate markers of cholesterol absorption (cholestanol and plant sterols) and synthesis (cholesterol precursors) in serum have suggested that in adult type 1 diabetes, cholesterol absorption is high and synthesis is low compared with type 2 diabetic or control subjects. Accordingly, these findings were further studied in children with type 1 diabetes. RESEARCH DESIGN AND METHODS Forty-eight children with diabetes were compared with 79 age- and sex-matched control subjects. The serum ratios of cholesterol absorption and synthesis markers were measured with gas-liquid chromatography. The study population was divided into triads (combining the two lowest triads) by serum cholestanol ratios of the control subjects indicating low to high cholesterol absorption efficiency. RESULTS The ratios of the absorption and synthesis markers were similar in case and control subjects, and they were negatively related to each other in control subjects, being less consistent in diabetic patients. Thus, high cholesterol absorption was associated with low synthesis. Plant sterol ratios increased significantly with increasing cholestanol triads in both groups, but the values in the lowest triads were higher in case versus control subjects. CONCLUSIONS Homeostasis between cholesterol absorption and synthesis is maintained in control children and somewhat less consistently in those with diabetes. The higher plant sterol ratios in diabetic versus control subjects in the lowest cholestanol triads suggest that cholesterol absorption is higher in children with diabetes versus control subjects but only within the range of low cholesterol absorption.
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Affiliation(s)
- Mikko Järvisalo
- Centre for Applied and Preventive Cardiovascular Medicine, University of Turku, Turku, Finland
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Kosters A, Kunne C, Looije N, Patel SB, Oude Elferink RPJ, Groen AK. The mechanism of ABCG5/ABCG8 in biliary cholesterol secretion in mice. J Lipid Res 2006; 47:1959-66. [PMID: 16741293 PMCID: PMC1805467 DOI: 10.1194/jlr.m500511-jlr200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The main player in biliary cholesterol secretion is the heterodimeric transporter complex, ABCG5/ABCG8, the function of which is necessary for the majority of sterols secreted into bile. It is not clear whether the primary step in this process is flopping of cholesterol from the inner to the outer leaflet of the canalicular membrane, with desorption by mixed micelles, or decreasing of the activation energy required for cholesterol desorption from the outer membrane leaflet. In this study, we investigated these mechanisms by infusing Abcg8(+/+), Abcg8(+/-), and Abcg8(-/-) mice with hydrophilic and hydrophobic bile salts. In Abcg8(-/-) mice, this failed to substantially stimulate biliary cholesterol secretion. Infusion of the hydrophobic bile salt taurodeoxycholate also resulted in cholestasis, which was induced in Abcg8(-/-) mice at a much lower infusion rate compared with Abc8(-/-) and Abcg8(+/-) mice, suggesting a reduced cholesterol content in the outer leaflet of the canalicular membrane. Indeed, isolation of canalicular membranes revealed a reduction of 45% in cholesterol content under these conditions in Abcg8(-/-) mice. Our data support the model that ABCG5/ABCG8 primarily play a role in flopping cholesterol (and sterols) from the inner leaflet to the outer leaflet of the canalicular membrane.
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Affiliation(s)
- Astrid Kosters
- AMC Liver Center, Academic Medical Center, Amsterdam, The Netherlands.
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37
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Lally S, Tan CY, Owens D, Tomkin GH. Messenger RNA levels of genes involved in dysregulation of postprandial lipoproteins in type 2 diabetes: the role of Niemann-Pick C1-like 1, ATP-binding cassette, transporters G5 and G8, and of microsomal triglyceride transfer protein. Diabetologia 2006; 49:1008-16. [PMID: 16518588 DOI: 10.1007/s00125-006-0177-8] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Accepted: 12/03/2005] [Indexed: 12/11/2022]
Abstract
AIMS/HYPOTHESIS The aim of the present study was to examine the relationship between chylomicron composition and expression of genes that regulate chylomicron production in the intestine. We examined expression of the following: (1) Niemann-Pick C1-like 1 (NPC1L1), which regulates cholesterol absorption; (2) ATP-binding cassette transporters G5 and G8 (ABCG5, ABCG8), which regulate cholesterol homeostasis through their ability to excrete enterocyte cholesterol back into the lumen of the intestine; and (3) microsomal triglyceride transfer protein (MTTP), which packages the chylomicron particle by assembling cholesterol, triglyceride, phospholipids and apolipoprotein B48. SUBJECTS, MATERIALS AND METHODS Type 2 diabetic (26) and non-diabetic (21) patients were examined. Levels of NPC1L1, ABCG5 and ABCG8 and MTTP mRNA were measured in duodenal biopsies by real-time PCR. Lipoproteins were isolated by sequential ultracentrifugation. RESULTS Diabetic patients had more NPC1L1 mRNA than the control subjects (p<0.02). Expression of ABCG5 and ABCG8 mRNA was lower in the diabetic patients (p<0.05) and MTTP expression was increased (p<0.05). There was a positive correlation between NPLC1L1 and MTTP mRNA (p<0.01) and a negative correlation between NPC1L1 and ABCG5 mRNA (p<0.001). Diabetic patients on statin therapy had increased ABCG5 and ABCG8 mRNA compared to those not on statin (p<0.02 and p<0.05) and less MTTP mRNA than those not on statin (p<0.05). CONCLUSIONS/INTERPRETATION This study demonstrates that in type 2 diabetes there are important alterations to the expression of intestinal genes that regulate cholesterol absorption and chylomicron synthesis. In diabetic patients statin therapy is associated with reduced MTTP expression and increased ABCG5 and ABCG8 mRNA. The study suggests new mechanisms to explain postprandial diabetic dyslipidaemia and the beneficial effect of statins.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily G, Member 5
- ATP Binding Cassette Transporter, Subfamily G, Member 8
- ATP-Binding Cassette Transporters/genetics
- ATP-Binding Cassette Transporters/metabolism
- Adenosine Triphosphate/metabolism
- Aged
- Biopsy
- Carrier Proteins/metabolism
- Diabetes Mellitus, Type 2/blood
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/physiopathology
- Eating
- Fasting
- Female
- Gastroscopy
- Gene Expression Regulation
- Glycated Hemoglobin/analysis
- Humans
- Hydroxymethylglutaryl-CoA Reductase Inhibitors/therapeutic use
- Lipoproteins/genetics
- Lipoproteins/metabolism
- Lipoproteins, LDL/blood
- Male
- Membrane Proteins/genetics
- Membrane Transport Proteins
- Middle Aged
- Polymerase Chain Reaction
- Postprandial Period
- RNA, Messenger/genetics
- Transcription, Genetic
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Affiliation(s)
- S Lally
- Department of Diabetes and Endocrinology, Trinity College, Dublin, Ireland
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Gylling H, Miettinen TA. Cholesterol absorption: influence of body weight and the role of plant sterols. Curr Atheroscler Rep 2006; 7:466-71. [PMID: 16256005 DOI: 10.1007/s11883-005-0064-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Cholesterol absorption and synthesis are inter-regulated, so if one changes then the other changes in the opposite direction. The regulation and detailed mechanism of cholesterol absorption have been intensely investigated. Inhibition of cholesterol absorption has become an additional factor for cholesterol lowering. Agents inhibiting cholesterol absorption, mainly plant stanols and sterols or ezetimibe, usually lower low-density lipoprotein cholesterol in monotherapy by less than 20%, indicating that these inhibitors can normalize cholesterol levels only in patients with a modest baseline hypercholesterolemia. Body weight, especially obesity with and without diabetes, and dietary plant sterols alter cholesterol absorption differently. This article briefly reviews some special questions of cholesterol absorption under these conditions.
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Affiliation(s)
- Helena Gylling
- Division of Internal Medicine, Department of Medicine, University of Helsinki, Biomedicum Helsinki, PO Box 700, FIN-00029, Helsinki, Finland
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Wang J, Gåfvels M, Rudling M, Murphy C, Björkhem I, Einarsson C, Eggertsen G. Critical role of cholic acid for development of hypercholesterolemia and gallstones in diabetic mice. Biochem Biophys Res Commun 2006; 342:1382-8. [PMID: 16516849 DOI: 10.1016/j.bbrc.2006.02.108] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2006] [Accepted: 02/15/2006] [Indexed: 10/25/2022]
Abstract
We studied bile acid and cholesterol metabolism in insulin-dependent diabetes utilizing genetically modified mice unable to synthesize cholic acid (Cyp8b1-/-). Diabetes was induced in Cyp8b1-/- and wild type animals (Cyp8b1+/+) by alloxan, and the mice were fed normal or cholesterol-enriched diet for 10 weeks. The serum levels of cholesterol were strongly increased in diabetic Cyp8b1+/+ mice fed cholesterol, while diabetic Cyp8b1-/- mice did not show any aberrations regardless of the diet. Diabetic cholesterol-fed Cyp8b1+/+ mice had much higher biliary cholesterol and cholesterol saturation index than all other groups, their bile contained a large number of cholesterol crystals, and their canalicular cholesterol transporter Abcg5/g8 mRNA levels were much higher. Cyp7a1 mRNA levels were similar in all diabetic mice but higher compared to non-diabetic animals. The results indicate a critical role for cholic acid for the development of hypercholesterolemia and gallstones in our animal model.
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Affiliation(s)
- Jin Wang
- Division of Clinical Chemistry, Department of Laboratory Medicine, Karolinska Institutet, Karolinska University Hospital, Huddinge, Sweden
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Geuken E, Visser DS, Leuvenink HGD, de Jong KP, Peeters PMJG, Slooff MJH, Kuipers F, Porte RJ. Hepatic expression of ABC transporters G5 and G8 does not correlate with biliary cholesterol secretion in liver transplant patients. Hepatology 2005; 42:1166-74. [PMID: 16250035 DOI: 10.1002/hep.20886] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The adenosine triphosphate (ATP)-binding cassette (ABC)-transporters ABCG5 and ABCG8 have been shown to mediate hepatic and intestinal excretion of cholesterol. In various (genetically modified) murine models, a strong relationship was found between hepatic expression of ABCG5/ABCG8 and biliary cholesterol content. Our study aimed to relate levels of hepatic expression of ABCG5 and ABCG8 to biliary excretion of cholesterol in man. From 24 patients who had received a liver transplant, bile samples were collected daily after transplantation over a 2-week period to determine biliary composition. Expression of ABCG5, ABCG8, MDR3, and BSEP was assessed by real-time polymerase chain reaction (PCR) in liver biopsy specimens collected before and after transplantation. Levels of hepatic ABCG5, ABCG8, and MDR3 messenger RNA (mRNA) were strongly correlated. After transplantation, the biliary secretion rate of cholesterol continuously increased, coinciding with gradual increases in bile salt and phospholipid secretion. In contrast, hepatic levels of ABCG5 and ABCG8 mRNA remained unchanged. Surprisingly, no correlation was found between the hepatic expression of ABCG5 and ABCG8 and rates of biliary cholesterol secretion, normalized for biliary phospholipid secretion. As expected, the concentration of biliary phospholipids correlated well with MDR3 expression. In conclusion, the strong relationship between ABCG5 and ABCG8 gene expression is consistent with the coordinate regulation of both genes, and in line with heterodimerization of both proteins into a functional transporter. Hepatic ABCG5/ABCG8 expression, at least during the early phase after transplantation, is not directly related to biliary cholesterol secretion in humans. This finding suggests the existence of alternative pathways for the hepatobiliary transport of cholesterol that are not controlled by ABCG5/ABCG8.
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Affiliation(s)
- Erwin Geuken
- Section of Hepatobiliary Surgery and Liver Transplantation, Department of Surgery, University Medical Center Groningen, University of Groningen, The Netherlands
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Iwasaki T, Takahashi S, Takahashi M, Zenimaru Y, Kujiraoka T, Ishihara M, Nagano M, Suzuki J, Miyamori I, Naiki H, Sakai J, Fujino T, Miller NE, Yamamoto TT, Hattori H. Deficiency of the very low-density lipoprotein (VLDL) receptors in streptozotocin-induced diabetic rats: insulin dependency of the VLDL receptor. Endocrinology 2005; 146:3286-94. [PMID: 15878964 DOI: 10.1210/en.2005-0043] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Hyperlipidemia is a common feature of diabetes and is related to cardiovascular disease. The very low-density lipoprotein receptor (VLDL-R) is a member of the low-density lipoprotein receptor (LDL-R) family. It binds and internalizes triglyceride-rich lipoproteins with high specificity. We examined the etiology of hyperlipidemia in the insulin-deficient state. VLDL-R expression in heart and skeletal muscle were measured in rats with streptozotocin (STZ)-induced diabetes. STZ rats showed severe hyperlipidemia on d 21 and 28, with a dramatic decline in VLDL-R protein in skeletal muscle (>90%), heart (approximately 50%) and a loss of adipose tissues itself on d 28. The reduction of VLDL-R protein in skeletal muscle could not be explained simply by a decrease at the transcriptional level, because a dissociation between VLDL-R protein and mRNA expression was observed. The expression of LDL-R and LDL-R-related protein in liver showed no consistent changes. Furthermore, no effect on VLDL-triglyceride production in liver was observed in STZ rats. A decrease in postheparin plasma lipoprotein lipase activity started on d 7 and continued to d 28 at the 50% level even though severe hyperlipidemia was detected only on d 21 and 28. In rat myoblast cells, serum deprivation for 24 h induced a reduction in VLDL-R proteins. Insulin (10(-6) m), but not IGF-I (10 ng/ml), restored the decreased VLDL-R proteins by serum deprivation. These results suggest that the combination of VLDL-R deficiency and reduced plasma lipoprotein lipase activity may be responsible for severe hyperlipidemia in insulin-deficient diabetes.
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Affiliation(s)
- Tadao Iwasaki
- Department of Advanced Medical Technology and Development, BML, Inc, Kawagoe, Japan
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Current literature in diabetes. Diabetes Metab Res Rev 2004; 20:487-94. [PMID: 15570584 DOI: 10.1002/dmrr.511] [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: 11/06/2022]
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Hori M, Satoh M, Furukawa K, Sakamoto YI, Hakamata H, Komohara Y, Takeya M, Sasaki Y, Miyazaki A, Horiuchi S. Acyl-coenzyme A:cholesterol acyltransferase-2 (ACAT-2) is responsible for elevated intestinal ACAT activity in diabetic rats. Arterioscler Thromb Vasc Biol 2004; 24:1689-95. [PMID: 15242859 DOI: 10.1161/01.atv.0000137976.88533.13] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Diabetes-induced dyslipidemia is seen in streptozotocin-induced diabetic rats. This is caused, in part, by elevated intestinal acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity. Because two ACAT isozymes (ACAT-1 and ACAT-2) were identified, in the present study we determined which ACAT isozyme was involved in the elevated intestinal ACAT activity in diabetic rats. METHODS AND RESULTS We cloned a full-length cDNA of rat ACAT-2. Its overexpression in ACAT-deficient AC29 cells demonstrated that the ACAT activity is derived from the cloned cDNA, and a 45-kDa protein of rat ACAT-2 cross-reacts with an anti-human ACAT-2 antibody. The tissue distribution of rat ACAT-2 mRNA revealed its restricted expression to liver and small intestine. Immunohistochemical analyses using an anti-human ACAT-2 antibody demonstrated that ACAT-2 is localized in villus-crypt axis of rat small intestine. The intestinal ACAT activity in diabetic rats was significantly immunodepleted by an anti-ACAT-2 antibody but not by an anti-ACAT-1 antibody. Finally, intestinal ACAT-2 in diabetic rats significantly increased at both protein and mRNA levels as compared with that in control rats. CONCLUSIONS Our data demonstrate that ACAT-2 isozyme is responsible for the increased intestinal ACAT activity of diabetic rats, suggesting an important role of ACAT-2 for dyslipidemia in diabetic patients. Diabetic rats exhibit dyslipidemia caused, in part, by elevated intestinal acyl-coenzyme A:cholesterol acyltransferase (ACAT) activity. We determined which ACAT isozyme (ACAT-1 or ACAT-2) was involved in the elevated intestinal ACAT activity in diabetic rats. We demonstrated an important role of ACAT-2, implicating its involvement in dyslipidemia in diabetic patients.
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Affiliation(s)
- Masaharu Hori
- Department of Medical Biochemistry, Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto 860-8556, Japan
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Abstract
Little information is available on cholesterol absorption and synthesis in human type 1 diabetes. We studied these variables using serum cholesterol precursor sterol ratios to cholesterol as surrogate markers of cholesterol synthesis and those of cholestanol and plant sterols to reflect cholesterol absorption in seven type 1 diabetic subjects and in five age- and body weight-matched control subjects. Total and lipoprotein cholesterol levels were similar, but triglycerides in intermediate-density lipoprotein (IDL) and LDL were higher in type 1 diabetic than in control subjects. Most of the marker sterols were transported by LDL and HDL in both groups. The percentage of esterified cholesterol was lower in triglyceride-rich lipoproteins in diabetic patients than in control subjects. The ratios of the absorption marker sterols in serum were higher, and those of the synthesis markers were lower in type 1 diabetic than in control subjects. The increased cholestanol ratios were seen in all lipoproteins, and those of free and total plant sterols were mainly in LDL, whereas the decreased free and total synthesis markers were mainly in all lipoproteins. In conclusion, high absorption and low synthesis marker sterols seem to characterize human type 1 diabetes. These findings could be related to low expression of ABC G/5 G/8 genes, resulting in high absorption of cholesterol and sterols in general and low synthesis of cholesterol compared with type 2 diabetes.
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Affiliation(s)
- Helena Gylling
- Department of Clinical Nutrition, University of Kuopio, P.O. Box 1627, FIN-70211 Kuopio, Finland.
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Chen G, Liang G, Ou J, Goldstein JL, Brown MS. Central role for liver X receptor in insulin-mediated activation of Srebp-1c transcription and stimulation of fatty acid synthesis in liver. Proc Natl Acad Sci U S A 2004; 101:11245-50. [PMID: 15266058 PMCID: PMC509189 DOI: 10.1073/pnas.0404297101] [Citation(s) in RCA: 411] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Transcription of the gene encoding sterol regulatory element-binding protein 1c (SREBP-1c) is known to be activated by insulin in the liver. The resultant SREBP-1c protein activates transcription of the genes required for fatty acid synthesis. Here, we use SREBP-1c promoter reporter constructs to dissect the mechanism of insulin activation in freshly isolated rat hepatocytes. The data show that a complete insulin response (increase of 6- to 11-fold) requires two binding sites for liver X receptors (LXRs), which are nuclear receptors that are activated by oxygenated sterols. Disruption of these binding sites did not lower basal transcription but severely reduced the response to insulin. In contrast, disruption of the closely linked binding sites for SREBPs and nuclear factor Y lowered basal transcription drastically but still permitted a 4- to 7-fold increase in response to insulin. Arachidonic acid, an inhibitor of LXR activation, blocked the response to insulin. We conclude that insulin activates the SREBP-1c promoter primarily by increasing the activity of LXRs, possibly through production of a ligand that activates LXRs or their heterodimerizing partner, the retinoid X receptor. Nuclear SREBPs and nuclear factor Y play permissive roles.
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Affiliation(s)
- Guoxun Chen
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX 75390-9046, USA
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Zanlungo S, Rigotti A, Nervi F. Hepatic cholesterol transport from plasma into bile: implications for gallstone disease. Curr Opin Lipidol 2004; 15:279-86. [PMID: 15166783 DOI: 10.1097/00041433-200406000-00007] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE OF REVIEW The transhepatic traffic of cholesterol from plasma lipoproteins into the bile is critical for overall cholesterol homeostasis and its alterations may lead to cholesterol gallstone formation. This review summarizes recent progress in understanding the key hepatic cholesterol metabolism-related proteins and pathways that influence biliary secretion of cholesterol. RECENT FINDINGS In cholesterol-fed apolipoprotein E knockout mice, the availability of dietary cholesterol for biliary disposal is decreased and diet-induced gallstone formation is impaired. Scavenger receptor class B type I is relevant for cholesterol transport from plasma HDL into the bile in chow-fed mice, however its expression is not critical for biliary cholesterol secretion and gallstone formation in lithogenic diet-fed mice. Intrahepatic cholesterol transport proteins (e.g. sterol carrier protein-2, Niemann Pick type C-1 protein) also determine liver cholesterol available for biliary secretion in mice. Genetic manipulation of canalicular ATP-binding cassette transporter G5 and G8 expression in mice has established their essential role for biliary cholesterol secretion. SUMMARY Recent studies have underscored that different proteins involved in hepatic cholesterol transport regulate the availability of cholesterol for biliary secretion. These advances may provide new avenues for prevention and treatment of various disease conditions linked to abnormal cholesterol metabolism.
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Affiliation(s)
- Silvana Zanlungo
- Department of Gastroenterology, Faculty of Medicine, Pontifical Catholic University of Chile, Marcoleta 367, Santiago, Chile
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