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Goldberg IJ, Cabodevilla AG, Younis W. In the Beginning, Lipoproteins Cross the Endothelial Barrier. J Atheroscler Thromb 2024; 31:854-860. [PMID: 38616110 DOI: 10.5551/jat.rv22017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2024] Open
Abstract
Atherosclerosis begins with the infiltration of cholesterol-containing lipoproteins into the arterial wall. White blood cell (WBC)-associated inflammation follows. Despite decades of research using genetic and pharmacologic methods to alter WBC function, in humans, the most effective method to prevent the initiation and progression of disease remains low-density lipoprotein (LDL) reduction. However, additional approaches to reducing cardiovascular disease would be useful as residual risk of events continues even with currently effective LDL-reducing treatments. Some of this residual risk may be due to vascular toxicity of triglyceride-rich lipoproteins (TRLs). Another option is that LDL transcytosis continues, albeit at reduced rates due to lower circulating levels of this lipoprotein. This review will address these two topics. The evidence that TRLs promote atherosclerosis and the processes that allow LDL and TRLs to be taken up by endothelial cells leading to their accumulation with the subendothelial space.
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Affiliation(s)
- Ira J Goldberg
- Division of Endocrinology, New York University Grossman School of Medicine
| | | | - Waqas Younis
- Division of Endocrinology, New York University Grossman School of Medicine
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2
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Hu S, Zhu Y, Zhao X, Li R, Shao G, Gong D, Hu C, Liu H, Xu K, Liu C, Xu M, Zhao Z, Li T, Hu Z, Shao M, Liu J, Li X, Wu H, Li J, Xu Y. Hepatocytic lipocalin-2 controls HDL metabolism and atherosclerosis via Nedd4-1-SR-BI axis in mice. Dev Cell 2023; 58:2326-2337.e5. [PMID: 37863040 DOI: 10.1016/j.devcel.2023.09.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 07/03/2023] [Accepted: 09/25/2023] [Indexed: 10/22/2023]
Abstract
High-density lipoprotein (HDL) metabolism is regulated by complex interplay between the scavenger receptor group B type 1 (SR-BI) and multiple signaling molecules in the liver. Here, we show that lipocalin-2 (Lcn2) is a key regulator of hepatic SR-BI, HDL metabolism, and atherosclerosis. Overexpression of human Lcn2 in hepatocytes attenuates the development of atherosclerosis via SR-BI in western-diet-fed Ldlr-/- mice, whereas hepatocyte-specific ablation of Lcn2 has the opposite effect. Mechanistically, hepatocyte Lcn2 improves HDL metabolism and alleviates atherogenesis by blocking Nedd4-1-mediated SR-BI ubiquitination at K500 and K508. The Lcn2-improved HDL metabolism is abolished in mice with hepatocyte-specific Nedd4-1 or SR-BI deletion and in SR-BI (K500A/K508A) mutation mice. This study identifies a regulatory axis from Lcn2 to HDL via blocking Nedd4-1-mediated SR-BI ubiquitination and demonstrates that hepatocyte Lcn2 may be a promising target to improve HDL metabolism to treat atherosclerotic cardiovascular diseases.
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Affiliation(s)
- Shuwei Hu
- School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China; Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272, USA
| | - Yingdong Zhu
- Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272, USA
| | - Xiaojie Zhao
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Rui Li
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Guangze Shao
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Dongxu Gong
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Chencheng Hu
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Hongjun Liu
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Kexin Xu
- Department of Nephrology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Chenxi Liu
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Minghuan Xu
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Zhonghua Zhao
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Tao Li
- Department of Hepatobiliary Surgery, Peking University People's Hospital Xizhimen South Street, West District, Beijing 100044, China
| | - Zhigang Hu
- Jiangsu Key Laboratory for Molecular and Medical Biotechnology, College of Life Sciences, Nanjing Normal University, Nanjing 210023, China
| | - Mengle Shao
- Center for Microbes, Development and Health, CAS Key Laboratory of Molecular Virology and Immunology, Institut Pasteur of Shanghai, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jun- Liu
- Department of Nephrology, Shanghai General Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200080, China
| | - Xinwei Li
- State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, Institute of Zoonosis, and College of Veterinary Medicine, Jilin University, Changchun 130062, China
| | - Huijuan Wu
- Department of Pathology, School of Basic Medical Sciences, Fudan University Shanghai, Shanghai 200032, China
| | - Jing Li
- Department of Endocrinology, Beijing Chao-yang Hospital, Capital Medical University, Beijing 100020, China.
| | - Yanyong Xu
- Key Laboratory of Metabolism and Molecular Medicine of the Ministry of Education, Department of Pathology of School of Basic Medical Sciences, Frontier Innovation Center, Fudan University Shanghai, Shanghai 200032, China; Diabetes, Obesity and Metabolism Research Center, Department of Integrative Medical Sciences, Northeast Ohio Medical University, Rootstown, OH 44272, USA.
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3
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Ginsberg HN, Goldberg IJ. Broadening the Scope of Dyslipidemia Therapy by Targeting APOC3 (Apolipoprotein C3) and ANGPTL3 (Angiopoietin-Like Protein 3). Arterioscler Thromb Vasc Biol 2023; 43:388-398. [PMID: 36579649 PMCID: PMC9975058 DOI: 10.1161/atvbaha.122.317966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Accepted: 12/13/2022] [Indexed: 12/30/2022]
Abstract
The positive relationship between increased levels of circulating triglycerides and cardiovascular events has been observed for decades. Driven by genetic cohort studies, inhibitors of APOC3 (apolipoprotein C3) and ANGPTL (angiopoietin-like protein) 3 that reduce circulating triglycerides are poised to enter clinical practice. We will review the biology of how inhibition of these 2 proteins affects circulating lipoproteins as well as the current state of clinical development of monoclonal antibodies, antisense oligonucleotides, and silencing RNAs targeting APOC3 and ANGPTL3.
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Affiliation(s)
- Henry N Ginsberg
- Department of Medicine, Vagelos College of Physicians and Surgeons, Columbia University New York (H.N.G.)
| | - Ira J Goldberg
- Division of Endocrinology, Diabetes and Metabolism, New York University Grossman School of Medicine, New York (I.J.G.)
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4
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Xu H, Thomas MJ, Kaul S, Kallinger R, Ouweneel AB, Maruko E, Oussaada SM, Jongejan A, Cense HA, Nieuwdorp M, Serlie MJ, Goldberg IJ, Civelek M, Parks BW, Lusis AJ, Knaack D, Schill RL, May SC, Reho JJ, Grobe JL, Gantner B, Sahoo D, Sorci-Thomas MG. Pcpe2, a Novel Extracellular Matrix Protein, Regulates Adipocyte SR-BI-Mediated High-Density Lipoprotein Uptake. Arterioscler Thromb Vasc Biol 2021; 41:2708-2725. [PMID: 34551590 PMCID: PMC8551036 DOI: 10.1161/atvbaha.121.316615] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 08/24/2021] [Indexed: 01/22/2023]
Abstract
Objective To investigate the role of adipocyte Pcpe2 (procollagen C-endopeptidase enhancer 2) in SR-BI (scavenger receptor class BI)-mediated HDL-C (high-density lipoprotein cholesterol) uptake and contributions to adipose lipid storage. Approach and Results Pcpe2, a glycoprotein devoid of intrinsic proteolytic activity, is believed to participate in extracellular protein-protein interactions, supporting SR-BI- mediated HDL-C uptake. In published studies, Pcpe2 deficiency increased the development of atherosclerosis by reducing SR-BI-mediated HDL-C catabolism, but the biological impact of this deficiency on adipocyte SR-BI-mediated HDL-C uptake is unknown. Differentiated cells from Ldlr-/-/Pcpe2-/- (Pcpe2-/-) mouse adipose tissue showed elevated SR-BI protein levels, but significantly reduced HDL-C uptake compared to Ldlr-/- (control) adipose tissue. SR-BI-mediated HDL-C uptake was restored by preincubation of cells with exogenous Pcpe2. In diet-fed mice lacking Pcpe2, significant reductions in visceral, subcutaneous, and brown adipose tissue mass were observed, despite elevations in plasma triglyceride and cholesterol concentrations. Significant positive correlations exist between adipose mass and Pcpe2 expression in both mice and humans. Conclusions Overall, these findings reveal a novel and unexpected function for Pcpe2 in modulating SR-BI expression and function as it relates to adipose tissue expansion and cholesterol balance in both mice and humans.
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Affiliation(s)
- Hao Xu
- Department of Medicine, Division of Endocrinology and Molecular Medicine
| | - Michael J. Thomas
- Pharmacology & Toxicology and
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Sushma Kaul
- Department of Medicine, Division of Endocrinology and Molecular Medicine
| | | | - Amber B. Ouweneel
- Department of Medicine, Division of Endocrinology and Molecular Medicine
| | - Elisa Maruko
- Department of Medicine, Division of Endocrinology and Molecular Medicine
| | - Sabrina M. Oussaada
- Department of Endocrinology and Metabolism, Amsterdam University Medical Centers, Academic Medical Center, Amsterdam, the Netherlands
| | - Aldo Jongejan
- Department of Bioinformatics, Amsterdam University Medical Centers, Academic Medical Center, Amsterdam, the Netherlands
| | - Huib A. Cense
- Department of Surgery, Rode Kruis Ziekenhuis, Beverwijk, the Netherlands
| | - Max Nieuwdorp
- Department of Internal and Vascular Medicine, Amsterdam University Medical Centers, Academic Medical Center, Amsterdam, the Netherlands
| | - Mireille J. Serlie
- Department of Endocrinology and Metabolism, Amsterdam University Medical Centers, Academic Medical Center, Amsterdam, the Netherlands
| | - Ira J. Goldberg
- Department of Medicine, Division of Endocrinology, Diabetes and Metabolism, New York University Langone School of Medicine, New York, NY
| | - Mete Civelek
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA
| | - Brian W. Parks
- Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI
| | - Aldons J. Lusis
- Department of Medicine, Human Genetics, Microbiology, Immunology and Molecular Genetics, University of California Los Angeles, California
| | - Darcy Knaack
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Rebecca L. Schill
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Sarah C. May
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - John J. Reho
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Comprehensive Rodent Metabolic Phenotyping Core
| | - Justin L. Grobe
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
- Comprehensive Rodent Metabolic Phenotyping Core
- Department of Biomedical Engineering
| | - Benjamin Gantner
- Department of Medicine, Division of Endocrinology and Molecular Medicine
| | - Daisy Sahoo
- Department of Medicine, Division of Endocrinology and Molecular Medicine
- Pharmacology & Toxicology and
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Mary G. Sorci-Thomas
- Department of Medicine, Division of Endocrinology and Molecular Medicine
- Pharmacology & Toxicology and
- Cardiovascular Center, Medical College of Wisconsin, Milwaukee, Wisconsin
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5
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Zhou E, Li Z, Nakashima H, Liu C, Ying Z, Foks AC, Berbée JFP, van Dijk KW, Rensen PCN, Wang Y. Hepatic Scavenger Receptor Class B Type 1 Knockdown Reduces Atherosclerosis and Enhances the Antiatherosclerotic Effect of Brown Fat Activation in APOE*3-Leiden.CETP Mice. Arterioscler Thromb Vasc Biol 2021; 41:1474-1486. [PMID: 33567866 DOI: 10.1161/atvbaha.121.315882] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
[Figure: see text].
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MESH Headings
- Adipose Tissue, Brown/drug effects
- Adipose Tissue, Brown/metabolism
- Adrenergic beta-3 Receptor Agonists/pharmacology
- Animals
- Apolipoprotein E3/genetics
- Apolipoprotein E3/metabolism
- Atherosclerosis/genetics
- Atherosclerosis/metabolism
- Atherosclerosis/pathology
- Atherosclerosis/prevention & control
- Biomarkers/blood
- Cholesterol Ester Transfer Proteins/genetics
- Cholesterol Ester Transfer Proteins/metabolism
- Dioxoles/pharmacology
- Disease Models, Animal
- Gene Knockdown Techniques
- Humans
- Lipids/blood
- Lipolysis/drug effects
- Liver/metabolism
- Mice, Inbred C57BL
- Mice, Transgenic
- Plaque, Atherosclerotic
- RNA Interference
- RNA, Small Interfering/genetics
- RNA, Small Interfering/metabolism
- Scavenger Receptors, Class B/deficiency
- Scavenger Receptors, Class B/genetics
- Mice
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Affiliation(s)
- Enchen Zhou
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
| | - Zhuang Li
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
| | - Hiroyuki Nakashima
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
| | - Cong Liu
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
| | - Zhixiong Ying
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
| | - Amanda C Foks
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, The Netherlands (A.C.F.)
| | - Jimmy F P Berbée
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
| | - Ko Willems van Dijk
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
- Department of Human Genetics (K.W.v.D.), Leiden University Medical Center, The Netherlands
| | - Patrick C N Rensen
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
- Department of Endocrinology, the First Affiliated Hospital of Xi'an Jiaotong University, China (P.C.N.R., Y.W.)
| | - Yanan Wang
- Division of Endocrinology, Department of Medicine, Einthoven Laboratory for Experimental Vascular Medicine (E.Z., Z.L., H.N., C.L., Z.Y., J.F.P.B., KW.v.D., P.C.N.R., Y.W.), Leiden University Medical Center, The Netherlands
- Department of Endocrinology, the First Affiliated Hospital of Xi'an Jiaotong University, China (P.C.N.R., Y.W.)
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6
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SR-BI deficiency disassociates obesity from hepatic steatosis and glucose intolerance development in high fat diet-fed mice. J Nutr Biochem 2021; 89:108564. [DOI: 10.1016/j.jnutbio.2020.108564] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 11/24/2020] [Accepted: 11/24/2020] [Indexed: 01/05/2023]
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7
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Lipoprotein receptor SR-B1 deficiency enhances adipose tissue inflammation and reduces susceptibility to hepatic steatosis during diet-induced obesity in mice. Biochim Biophys Acta Mol Cell Biol Lipids 2021; 1866:158909. [PMID: 33631309 DOI: 10.1016/j.bbalip.2021.158909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 02/05/2021] [Accepted: 02/17/2021] [Indexed: 12/31/2022]
Abstract
Scavenger receptor class B type 1 (SR-B1) is a membrane lipoprotein receptor/lipid transporter involved in the pathogenesis of atherosclerosis, but its role in obesity and fatty liver development is unclear. Here, we determined the effects of SR-B1 deficiency on plasma metabolic and inflammatory parameters as well as fat deposition in adipose tissue and liver during obesity. To induce obesity, we performed high-fat diet (HFD) exposure for 12 weeks in male SR-B1 knock-out (SR-B1-/-, n = 14) and wild-type (WT, n = 12) mice. Compared to HFD-fed WT mice, plasma from HFD-fed SR-B1-/- animals exhibited increased total cholesterol, triglycerides (TG) and tumor necrosis factor-α (TNF-α) levels. In addition, hypertrophied adipocytes and macrophage-containing crown-like structures (CLS) were observed in adipose tissue from HFD-fed SR-B1 deficient mice. Remarkably, liver from obese SR-B1-/- mice showed attenuated TG content, dysregulation in hepatic peroxisome proliferator-activated receptors (PPARs) expression, increased hepatic TG secretion, and altered hepatic fatty acid (FA) composition. In conclusion, we show that SR-B1 deficiency alters the metabolic environment of obese mice through modulation of liver and adipose tissue lipid accumulation. Our findings provide the basis for further elucidation of SR-B1's role in obesity and fatty liver, two major public health issues that increase the risk of advanced chronic diseases and overall mortality.
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8
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Nakano T, Inoue I, Takenaka Y, Ito R, Kotani N, Sato S, Nakano Y, Hirasaki M, Shimada A, Murakoshi T. Ezetimibe impairs transcellular lipid trafficking and induces large lipid droplet formation in intestinal absorptive epithelial cells. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158808. [PMID: 32860884 DOI: 10.1016/j.bbalip.2020.158808] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 07/30/2020] [Accepted: 08/18/2020] [Indexed: 01/26/2023]
Abstract
Ezetimibe inhibits Niemann-Pick C1-like 1 (NPC1L1) protein, which mediates intracellular cholesterol trafficking from the brush border membrane to the endoplasmic reticulum, where chylomicron assembly takes place in enterocytes or in the intestinal absorptive epithelial cells. Cholesterol is a minor lipid constituent of chylomicrons; however, whether or not a shortage of cholesterol attenuates chylomicron assembly is unknown. The aim of this study was to examine the effect of ezetimibe, a potent NPC1L1 inhibitor, on trans-epithelial lipid transport, and chylomicron assembly and secretion in enterocytes. Caco-2 cells, an absorptive epithelial model, grown onto culture inserts were given lipid micelles from the apical side, and chylomicron-like triacylglycerol-rich lipoprotein secreted basolaterally were analyzed after a 24-h incubation period in the presence of ezetimibe up to 50 μM. The secretion of lipoprotein and apolipoprotein B48 were reduced by adding ezetimibe (30% and 34%, respectively). Although ezetimibe allowed the cells to take up cholesterol normally, the esterification was abolished. Meanwhile, oleic acid esterification was unaffected. Moreover, ezetimibe activated sterol regulatory element-binding protein 2 by approximately 1.5-fold. These results suggest that ezetimibe limited cellular cholesterol mobilization required for lipoprotein assembly. In such conditions, large lipid droplet formation in Caco-2 cells and the enterocytes of mice were induced, implying that unprocessed triacylglycerol was sheltered in these compartments. Although ezetimibe did not reduce the post-prandial lipid surge appreciably in triolein-infused mice, the results of the present study indicated that pharmacological actions of ezetimibe may participate in a novel regulatory mechanism for the efficient chylomicron assembly and secretion.
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Affiliation(s)
- Takanari Nakano
- Department of Biochemistry, Faculty of Medicine, Saitama Medical University, Saitama, Japan.
| | - Ikuo Inoue
- Department of Diabetes and Endocrinology, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Yasuhiro Takenaka
- Department of Diabetes and Endocrinology, Faculty of Medicine, Saitama Medical University, Saitama, Japan; Department of Physiology, Graduate School of Medicine, Nippon Medical School, Tokyo, Japan
| | - Rina Ito
- Department of Biochemistry, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Norihiro Kotani
- Department of Biochemistry, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Sawako Sato
- Department of Diabetes and Endocrinology, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Yuka Nakano
- Department of Diabetes and Endocrinology, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Masataka Hirasaki
- Division of Developmental Biology, Research Center for Genomic Medicine, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Akira Shimada
- Department of Diabetes and Endocrinology, Faculty of Medicine, Saitama Medical University, Saitama, Japan
| | - Takayuki Murakoshi
- Department of Biochemistry, Faculty of Medicine, Saitama Medical University, Saitama, Japan
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9
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van der Sluis RJ, Hoekstra M. Glucocorticoids are active players and therapeutic targets in atherosclerotic cardiovascular disease. Mol Cell Endocrinol 2020; 504:110728. [PMID: 31968221 DOI: 10.1016/j.mce.2020.110728] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/19/2019] [Accepted: 01/17/2020] [Indexed: 02/07/2023]
Abstract
Adrenal-derived glucocorticoids mediate the physiological response to stress. Chronic disturbances in glucocorticoid homeostasis, i.e. in Addison's and Cushing's disease patients, predispose to the development of atherosclerotic cardiovascular disease. Here we review preclinical and clinical findings regarding the relation between changes in plasma glucocorticoid levels and the atherosclerosis extent. It appears that, although the altered glucocorticoid function can in most cases be restored in the different patient groups, current therapies do not necessarily reverse the associated risk for atherosclerotic cardiovascular disease. In our opinion much attention should therefore be given to the development of a Cushing's disease mouse model that can (1) effectively replicate the effect of hypercortisolemia on atherosclerosis outcome observed in humans and (2) be used to investigate, in a preclinical setting, the relative impact on atherosclerosis susceptibility of already available (e.g. metyrapone) and potentially novel (i.e. SR-BI activity modulators) therapeutic agents that target the adrenal glucocorticoid output.
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Affiliation(s)
- Ronald J van der Sluis
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Gorlaeus Laboratories, Einsteinweg 55, 2333CC, Leiden, the Netherlands
| | - Menno Hoekstra
- Division of BioTherapeutics, Leiden Academic Centre for Drug Research, Leiden University, Gorlaeus Laboratories, Einsteinweg 55, 2333CC, Leiden, the Netherlands.
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10
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Hoekstra M, van der Sluis RJ, Hildebrand RB, Lammers B, Zhao Y, Praticò D, van Berkel TJC, Rensen PCN, Kooijman S, Jauhiainen M, van Eck M. Disruption of Phospholipid Transfer Protein-Mediated High-Density Lipoprotein Maturation Reduces Scavenger Receptor BI Deficiency-Driven Atherosclerosis Susceptibility Despite Unexpected Metabolic Complications. Arterioscler Thromb Vasc Biol 2020; 40:611-623. [PMID: 31941380 DOI: 10.1161/atvbaha.119.313862] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE We tested the hypothesis that enlarged, dysfunctional HDL (high-density lipoprotein) particles contribute to the augmented atherosclerosis susceptibility associated with SR-BI (scavenger receptor BI) deficiency in mice. Approach and Results: We eliminated the ability of HDL particles to fully mature by targeting PLTP (phospholipid transfer protein) functionality. Particle size of the HDL population was almost fully normalized in male and female SR-BI×PLTP double knockout mice. In contrast, the plasma unesterified cholesterol to cholesteryl ester ratio remained elevated. The PLTP deficiency-induced reduction in HDL size in SR-BI knockout mice resulted in a normalized aortic tissue oxidative stress status on Western-type diet. Atherosclerosis susceptibility was-however-only partially reversed in double knockout mice, which can likely be attributed to the fact that they developed a metabolic syndrome-like phenotype characterized by obesity, hypertriglyceridemia, and a reduced glucose tolerance. Mechanistic studies in chow diet-fed mice revealed that the diminished glucose tolerance was probably secondary to the exaggerated postprandial triglyceride response. The absence of PLTP did not affect LPL (lipoprotein lipase)-mediated triglyceride lipolysis but rather modified the ability of VLDL (very low-density lipoprotein)/chylomicron remnants to be cleared from the circulation by the liver through receptors other than SR-BI. As a result, livers of double knockout mice only cleared 26% of the fractional dose of [14C]cholesteryl oleate after intravenous VLDL-like particle injection. CONCLUSIONS We have shown that disruption of PLTP-mediated HDL maturation reduces SR-BI deficiency-driven atherosclerosis susceptibility in mice despite the induction of proatherogenic metabolic complications in the double knockout mice.
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Affiliation(s)
- Menno Hoekstra
- From the Division of BioTherapeutics, Leiden Academic Centre for Drug Research, The Netherlands (M.H., R.J.v.d.S., R.B.H., B.L., Y.Z., T.J.C.v.B., M.v.E.)
| | - Ronald J van der Sluis
- From the Division of BioTherapeutics, Leiden Academic Centre for Drug Research, The Netherlands (M.H., R.J.v.d.S., R.B.H., B.L., Y.Z., T.J.C.v.B., M.v.E.)
| | - Reeni B Hildebrand
- From the Division of BioTherapeutics, Leiden Academic Centre for Drug Research, The Netherlands (M.H., R.J.v.d.S., R.B.H., B.L., Y.Z., T.J.C.v.B., M.v.E.)
| | - Bart Lammers
- From the Division of BioTherapeutics, Leiden Academic Centre for Drug Research, The Netherlands (M.H., R.J.v.d.S., R.B.H., B.L., Y.Z., T.J.C.v.B., M.v.E.)
| | - Ying Zhao
- From the Division of BioTherapeutics, Leiden Academic Centre for Drug Research, The Netherlands (M.H., R.J.v.d.S., R.B.H., B.L., Y.Z., T.J.C.v.B., M.v.E.)
| | - Domenico Praticò
- Alzheimer's Center at Temple, Department of Pharmacology, Philadelphia, PA (D.P.)
| | - Theo J C van Berkel
- From the Division of BioTherapeutics, Leiden Academic Centre for Drug Research, The Netherlands (M.H., R.J.v.d.S., R.B.H., B.L., Y.Z., T.J.C.v.B., M.v.E.)
| | | | - Sander Kooijman
- Division of Endocrinology, Department of Medicine (P.C.N.R., S.K.)
| | - Matti Jauhiainen
- Einthoven Laboratory for Experimental Vascular and Regenerative Medicine, Leiden University Medical Center, The Netherlands (P.C.N.R., S.K)
| | - Miranda van Eck
- From the Division of BioTherapeutics, Leiden Academic Centre for Drug Research, The Netherlands (M.H., R.J.v.d.S., R.B.H., B.L., Y.Z., T.J.C.v.B., M.v.E.)
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11
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D’Arrigo JS. Nanotargeting of Drug(s) for Delaying Dementia: Relevance of Covid-19 Impact on Dementia. Am J Alzheimers Dis Other Demen 2020; 35:1533317520976761. [PMID: 33307726 PMCID: PMC10623919 DOI: 10.1177/1533317520976761] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
By incorporating appropriate drug(s) into lipid (biobased) nanocarriers, one obtains a combination therapeutic for dementia treatment that targets certain cell-surface scavenger receptors (mainly class B type I, or "SR-BI") and thereby crosses the blood-brain barrier. The cardiovascular risk factors for dementia trigger widespread inflammation -- which lead to neurodegeneration, gradual cognitive/memory decline, and eventually (late-onset) dementia. Accordingly, one useful strategy to delay dementia could be based upon nanotargeting drug(s), using lipid nanocarriers, toward a major receptor class responsible for inflammation-associated (cytokine-mediated) cell signaling events. At the same time, the immune response and excessive inflammation, commonly observed in the very recent human coronavirus (COVID-19) pandemic, may accelerate the progression of brain inflammatory neurodegeneration-which increases the probability of post-infection memory impairment and accelerating progression of Alzheimer's disease. Hence, the proposed multitasking combination therapeutic, using a (biobased) lipid nanocarrier, may also display greater effectiveness at different stages of dementia.
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Affiliation(s)
- Joseph S. D’Arrigo
- Cavitation-Control Technology Inc, Farmington, CT, USA. D’Arrigo is now with Cav-Con, Inc, Bellevue, WA, USA
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12
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Muthuramu I, Amin R, Aboumsallem JP, Mishra M, Robinson EL, De Geest B. Hepatocyte-Specific SR-BI Gene Transfer Corrects Cardiac Dysfunction in
Scarb1
-Deficient Mice and Improves Pressure Overload-Induced Cardiomyopathy. Arterioscler Thromb Vasc Biol 2018; 38:2028-2040. [DOI: 10.1161/atvbaha.118.310946] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Objective—
We investigated the hypothesis that HDL (high-density lipoprotein) dysfunction in
Scarb1
−/−
mice negatively affects cardiac function both in the absence and in the presence of pressure overload. Second, we evaluated whether normalization of HDL metabolism in
Scarb1
−/−
mice by hepatocyte-specific SR-BI (scavenger receptor class B, type I) expression after E1E3E4-deleted adenoviral AdSR-BI (E1E3E4-deleted adenoviral vector expressing SR-BI protein in hepatocytes) transfer abrogates the effects of total body SR-BI deficiency on cardiac structure and function.
Approach and Results—
Transverse aortic constriction (TAC) or sham operation was performed at the age of 14 weeks, 2 weeks after saline injection or after gene transfer with AdSR-BI or with the control vector Adnull. Mortality rate in
Scarb1
−/−
TAC mice was significantly increased compared with wild-type TAC mice during 8 weeks of follow-up (hazard ratio, 2.02; 95% CI, 1.14–3.61). Hepatocyte-specific SR-BI gene transfer performed 2 weeks before induction of pressure overload by TAC potently reduced mortality in
Scarb1
−/−
mice (hazard ratio, 0.329; 95% CI, 0.180–0.600). Hepatocyte-specific SR-BI expression abrogated increased cardiac hypertrophy and lung congestion and counteracted increased myocardial apoptosis and interstitial and perivascular fibrosis in
Scarb1
−/−
TAC mice.
Scarb1
−/−
sham mice were, notwithstanding the absence of detectable structural heart disease, characterized by systolic and diastolic dysfunction and hypotension, which were completely counteracted by AdSR-BI transfer. Furthermore, AdSR-BI transfer abrogated increased end-diastolic pressure and diastolic dysfunction in
Scarb1
−/−
TAC mice. Increased oxidative stress and reduced antioxidant defense systems in
Scarb1
−/−
mice were rescued by AdSR-BI transfer.
Conclusions—
The detrimental effects of SR-BI deficiency on cardiac structure and function are nullified by hepatocyte-specific SR-BI transfer, which restores HDL metabolism.
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Affiliation(s)
- Ilayaraja Muthuramu
- From the Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences (I.M., R.A., J.P.A., M.M., B.D.G.)
| | - Ruhul Amin
- From the Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences (I.M., R.A., J.P.A., M.M., B.D.G.)
| | - Joseph Pierre Aboumsallem
- From the Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences (I.M., R.A., J.P.A., M.M., B.D.G.)
| | - Mudit Mishra
- From the Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences (I.M., R.A., J.P.A., M.M., B.D.G.)
| | - Emma Louise Robinson
- Experimental Cardiology, Department of Cardiovascular Sciences (E.L.R.), Catholic University of Leuven, Belgium
- Center for Heart Failure Research, Cardiovascular Research Institute Maastricht (CARIM), Maastricht University, The Netherlands (E.L.R.)
| | - Bart De Geest
- From the Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences (I.M., R.A., J.P.A., M.M., B.D.G.)
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13
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D'Arrigo JS. Targeting Early Dementia: Using Lipid Cubic Phase Nanocarriers to Cross the Blood⁻Brain Barrier. Biomimetics (Basel) 2018; 3:E4. [PMID: 31105226 PMCID: PMC6352688 DOI: 10.3390/biomimetics3010004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Revised: 02/21/2018] [Accepted: 03/06/2018] [Indexed: 12/14/2022] Open
Abstract
Over the past decades, a frequent co-morbidity of cerebrovascular pathology and Alzheimer's disease has been observed. Numerous published studies indicate that the preservation of a healthy cerebrovascular endothelium can be an important therapeutic target. By incorporating the appropriate drug(s) into biomimetic (lipid cubic phase) nanocarriers, one obtains a multitasking combination therapeutic, which targets certain cell surface scavenger receptors, mainly class B type I (i.e., SR-BI), and crosses the blood⁻brain barrier. This targeting allows for various cell types related to Alzheimer's to be simultaneously searched out for localized drug treatment in vivo.
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14
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Hoekstra M. SR-BI as target in atherosclerosis and cardiovascular disease - A comprehensive appraisal of the cellular functions of SR-BI in physiology and disease. Atherosclerosis 2017; 258:153-161. [DOI: 10.1016/j.atherosclerosis.2017.01.034] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 01/25/2017] [Accepted: 01/27/2017] [Indexed: 12/12/2022]
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15
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Briand O, Touche V, Colin S, Brufau G, Davalos A, Schonewille M, Bovenga F, Carrière V, de Boer JF, Dugardin C, Riveau B, Clavey V, Tailleux A, Moschetta A, Lasunción MA, Groen AK, Staels B, Lestavel S. Liver X Receptor Regulates Triglyceride Absorption Through Intestinal Down-regulation of Scavenger Receptor Class B, Type 1. Gastroenterology 2016; 150:650-8. [PMID: 26602218 DOI: 10.1053/j.gastro.2015.11.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 10/30/2015] [Accepted: 11/10/2015] [Indexed: 12/02/2022]
Abstract
BACKGROUND & AIMS Reducing postprandial triglyceridemia may be a promising strategy to lower the risk of cardiovascular disorders associated with obesity and type 2 diabetes. In enterocytes, scavenger receptor class B, type 1 (SR-B1, encoded by SCARB1) mediates lipid-micelle sensing to promote assembly and secretion of chylomicrons. The nuclear receptor subfamily 1, group H, members 2 and 3 (also known as liver X receptors [LXRs]) regulate genes involved in cholesterol and fatty acid metabolism. We aimed to determine whether intestinal LXRs regulate triglyceride absorption. METHODS C57BL/6J mice were either fed a cholesterol-enriched diet or given synthetic LXR agonists (GW3965 or T0901317). We measured the production of chylomicrons and localized SR-B1 by immunohistochemistry. Mechanisms of postprandial triglyceridemia and SR-B1 regulation were studied in Caco-2/TC7 cells incubated with LXR agonists. RESULTS In mice and in the Caco-2/TC7 cell line, LXR agonists caused localization of intestinal SR-B1 from apical membranes to intracellular organelles and reduced chylomicron secretion. In Caco-2/TC7 cells, LXR agonists reduced SR-B1-dependent lipidic-micelle-induced Erk phosphorylation. LXR agonists also reduced intracellular trafficking of the apical apolipoprotein B pool toward secretory compartments. LXR reduced levels of SR-B1 in Caco-2/TC7 cells via a post-transcriptional mechanism that involves microRNAs. CONCLUSION In Caco-2/TC7 cells and mice, intestinal activation of LXR reduces the production of chylomicrons by a mechanism dependent on the apical localization of SR-B1.
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Affiliation(s)
- Olivier Briand
- University Lille, Inserm, Centre Hospitalier Universitaire (CHU) de Lille, Institut Pasteur de Lille, U1011-European Genomic Institute for Diabetes, Lille, France
| | - Véronique Touche
- University Lille, Inserm, Centre Hospitalier Universitaire (CHU) de Lille, Institut Pasteur de Lille, U1011-European Genomic Institute for Diabetes, Lille, France
| | - Sophie Colin
- University Lille, Inserm, Centre Hospitalier Universitaire (CHU) de Lille, Institut Pasteur de Lille, U1011-European Genomic Institute for Diabetes, Lille, France
| | - Gemma Brufau
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Alberto Davalos
- Madrid Institute for Advanced Studies (IMDEA) Food Institute, Laboratory of Disorders of Lipid Metabolism and Molecular Nutrition, Campus de Excelencia Internacional (CEI), Universidad Autónoma de Madrid (UAM), Consejo Superior de Investigaciones Científicas (CSIC), Madrid, Spain
| | - Marleen Schonewille
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Fabiola Bovenga
- National Research Cancer Center, Giovanni Paolo II, and University of Bari, Bari, Italy
| | - Véronique Carrière
- Institut National de la Santé et de la Recherche Médicale (INSERM), UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France; Université Paris Descartes, Sorbonne Paris Cit, UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France; Servicio de Bioquímica-Investigación, Hospital Ramón y Cajal, Instituto Ramón y Cajal de Investigatión Sanitaria (IRYCIS), Madrid, Spain
| | - Jan Freark de Boer
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Camille Dugardin
- University Lille, Inserm, Centre Hospitalier Universitaire (CHU) de Lille, Institut Pasteur de Lille, U1011-European Genomic Institute for Diabetes, Lille, France
| | - Béatrice Riveau
- Sorbonne Universités, Université Pierre et Marie Curie (UPMC), UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France; Institut National de la Santé et de la Recherche Médicale (INSERM), UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France; Université Paris Descartes, Sorbonne Paris Cit, UMR_S 1138, Centre de Recherche des Cordeliers, Paris, France
| | - Véronique Clavey
- University Lille, Inserm, Centre Hospitalier Universitaire (CHU) de Lille, Institut Pasteur de Lille, U1011-European Genomic Institute for Diabetes, Lille, France
| | - Anne Tailleux
- University Lille, Inserm, Centre Hospitalier Universitaire (CHU) de Lille, Institut Pasteur de Lille, U1011-European Genomic Institute for Diabetes, Lille, France
| | - Antonio Moschetta
- National Research Cancer Center, Giovanni Paolo II, and University of Bari, Bari, Italy
| | - Miguel A Lasunción
- Servicio de Bioquímica-Investigación, Hospital Ramón y Cajal, Instituto Ramón y Cajal de Investigatión Sanitaria (IRYCIS), Madrid, Spain; Centro de Investigatión Biomedica en Red (CIBER) de Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Spain
| | - Albert K Groen
- Department of Pediatrics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - Bart Staels
- University Lille, Inserm, Centre Hospitalier Universitaire (CHU) de Lille, Institut Pasteur de Lille, U1011-European Genomic Institute for Diabetes, Lille, France.
| | - Sophie Lestavel
- University Lille, Inserm, Centre Hospitalier Universitaire (CHU) de Lille, Institut Pasteur de Lille, U1011-European Genomic Institute for Diabetes, Lille, France
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16
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Hoekstra M, Van Eck M. HDL is redundant for adrenal steroidogenesis in LDLR knockout mice with a human-like lipoprotein profile. J Lipid Res 2016; 57:631-7. [PMID: 26891738 DOI: 10.1194/jlr.m066019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Indexed: 11/20/2022] Open
Abstract
The contribution of HDL to adrenal steroidogenesis appears to be different between mice and humans. In the current study, we tested the hypothesis that a difference in lipoprotein profile may be the underlying cause. Hereto, we determined the impact of HDL deficiency on the adrenal glucocorticoid output in genetically modified mice with a human-like lipoprotein profile. Genetic deletion of APOA1 in LDL receptor (LDLR) knockout mice was associated with HDL deficiency and a parallel increase in the level of cholesterol associated with nonHDL fractions. Despite a compensatory increase in the adrenal relative mRNA expression levels of the cholesterol synthesis gene, HMG-CoA reductase, adrenals from APOA1/LDLR double knockout mice were severely depleted of neutral lipids, as compared with those of control LDLR knockout mice. However, basal corticosterone levels and the adrenal glucocorticoid response to stress were not different between the two types of mice. In conclusion, we have shown that HDL is not critical for proper adrenal glucocorticoid function when mice are provided with a human-like lipoprotein profile. Our findings provide the first experimental evidence that APOB-containing lipoproteins may facilitate adrenal steroidogenesis, in an LDLR-independent manner, in vivo in mice.
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Affiliation(s)
- Menno Hoekstra
- Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Gorlaeus Laboratories, 2333CC Leiden, The Netherlands
| | - Miranda Van Eck
- Division of Biopharmaceutics, Cluster BioTherapeutics, Leiden Academic Centre for Drug Research, Gorlaeus Laboratories, 2333CC Leiden, The Netherlands
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17
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Niemsiri V, Wang X, Pirim D, Radwan ZH, Bunker CH, Barmada MM, Kamboh MI, Demirci FY. Genetic contribution of SCARB1 variants to lipid traits in African Blacks: a candidate gene association study. BMC MEDICAL GENETICS 2015; 16:106. [PMID: 26563154 PMCID: PMC4643515 DOI: 10.1186/s12881-015-0250-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 10/30/2015] [Indexed: 12/03/2022]
Abstract
Background High-density lipoprotein cholesterol (HDL-C) exerts many anti-atherogenic properties including its role in reverse cholesterol transport (RCT). Scavenger receptor class B member 1 (SCARB1) plays a key role in RCT by selective uptake of HDL cholesteryl esters. We aimed to explore the genetic contribution of SCARB1 to affecting lipid levels in African Blacks from Nigeria. Methods We resequenced 13 exons and exon-intron boundaries of SCARB1 in 95 individuals with extreme HDL-C levels using Sanger method. Then, we genotyped 147 selected variants (78 sequence variants, 69 HapMap tagSNPs, and 2 previously reported relevant variants) in the entire sample of 788 African Blacks using either the iPLEX Gold or TaqMan methods. A total of 137 successfully genotyped variants were further evaluated for association with major lipid traits. Results The initial gene-based analysis demonstrated evidence of association with HDL-C and apolipoprotein A-I (ApoA-I). The follow-up single-site analysis revealed nominal evidence of novel associations of nine common variants with HDL-C and/or ApoA-I (P < 0.05). The strongest association was between rs11057851 and HDL-C (P = 0.0043), which remained significant after controlling for multiple testing using false discovery rate. Rare variant association testing revealed a group of 23 rare variants (frequencies ≤1 %) associated with HDL-C (P = 0.0478). Haplotype analysis identified four SCARB1 regions associated with HDL-C (global P < 0.05). Conclusions To our knowledge, this is the first report of a comprehensive association study of SCARB1 variations with lipid traits in an African Black population. Our results showed the consistent association of SCARB1 variants with HDL-C across various association analyses, supporting the role of SCARB1 in lipoprotein-lipid regulatory mechanism. Electronic supplementary material The online version of this article (doi:10.1186/s12881-015-0250-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Vipavee Niemsiri
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA.
| | - Xingbin Wang
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA.
| | - Dilek Pirim
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA.
| | - Zaheda H Radwan
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA.
| | - Clareann H Bunker
- Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA.
| | - M Michael Barmada
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA.
| | - M Ilyas Kamboh
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA.
| | - F Yesim Demirci
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, 130 DeSoto Street, Pittsburgh, PA, 15261, USA.
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18
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Lino M, Farr S, Baker C, Fuller M, Trigatti B, Adeli K. Intestinal scavenger receptor class B type I as a novel regulator of chylomicron production in healthy and diet-induced obese states. Am J Physiol Gastrointest Liver Physiol 2015; 309:G350-9. [PMID: 26138463 DOI: 10.1152/ajpgi.00086.2015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 06/25/2015] [Indexed: 01/31/2023]
Abstract
The small intestine contributes to diabetic dyslipidemia through the overproduction of apolipoprotein B48 (apoB48)-containing chylomicron particles. An important regulator of chylomicron generation is dietary lipid absorption, underlining the potential involvement of intestinal lipid transporters for developing dyslipidemia. Intestinal expression of scavenger receptor class B type I (SR-BI) has been found to be upregulated in animal models of insulin resistance. Here we characterized the potential importance of SR-BI in contributing to chylomicron production and postprandial hypertriglyceridemia in vivo. Postprandial triglyceride (TG)-rich lipoprotein (TRL) production was characterized in hamsters treated with the SR-BI inhibitor to block lipid transport-1 (BLT-1) under healthy conditions or conditions of diet-induced obesity and dyslipidemia. BLT-1 (1 mg/kg) or vehicle was administered acutely in chow-fed hamsters or gavaged twice daily over 10 days during high-fructose, high-fat, high-cholesterol (FFC) feeding. Effects of acute SR-BI inhibition by BLT-1 were confirmed in healthy fat-loaded rats. Finally, plasma lipid levels were compared between SR-BI(-/-) mice and their wild-type counterparts fed either chow or a 12-wk high-fat diet. Acute BLT-1 treatment reduced postprandial plasma and TRL TG levels in healthy hamsters and rats. Chronic BLT-1 treatment of FFC-fed hamsters blunted diet-induced weight gain and fasting hypertriglyceridemia, and lowered postprandial TRL-TG, -cholesterol, and -apoB48 levels. Finally, SR-BI(-/-) mice displayed lower plasma and TRL TG levels relative to wild type, and diet-induced weight gain and postprandial hypertriglyceridemia were hindered in SR-BI(-/-) mice. We conclude that intestinal SR-BI is a critical regulator of postprandial lipoprotein production, emphasizing its potential as a target for preventing diabetic dyslipidemia.
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Affiliation(s)
- Marsel Lino
- Department of Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; and
| | - Sarah Farr
- Department of Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; and
| | - Chris Baker
- Department of Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Mark Fuller
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Bernardo Trigatti
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
| | - Khosrow Adeli
- Department of Molecular Structure and Function, Research Institute, The Hospital for Sick Children, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; and
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19
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Zhao Y, Hoekstra M, Korporaal SJA, Van Berkel TJC, Van Eck M. HDL Receptor Scavenger Receptor BI. Atherosclerosis 2015. [DOI: 10.1002/9781118828533.ch25] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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20
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Zannis VI, Fotakis P, Koukos G, Kardassis D, Ehnholm C, Jauhiainen M, Chroni A. HDL biogenesis, remodeling, and catabolism. Handb Exp Pharmacol 2015; 224:53-111. [PMID: 25522986 DOI: 10.1007/978-3-319-09665-0_2] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this chapter, we review how HDL is generated, remodeled, and catabolized in plasma. We describe key features of the proteins that participate in these processes, emphasizing how mutations in apolipoprotein A-I (apoA-I) and the other proteins affect HDL metabolism. The biogenesis of HDL initially requires functional interaction of apoA-I with the ATP-binding cassette transporter A1 (ABCA1) and subsequently interactions of the lipidated apoA-I forms with lecithin/cholesterol acyltransferase (LCAT). Mutations in these proteins either prevent or impair the formation and possibly the functionality of HDL. Remodeling and catabolism of HDL is the result of interactions of HDL with cell receptors and other membrane and plasma proteins including hepatic lipase (HL), endothelial lipase (EL), phospholipid transfer protein (PLTP), cholesteryl ester transfer protein (CETP), apolipoprotein M (apoM), scavenger receptor class B type I (SR-BI), ATP-binding cassette transporter G1 (ABCG1), the F1 subunit of ATPase (Ecto F1-ATPase), and the cubulin/megalin receptor. Similarly to apoA-I, apolipoprotein E and apolipoprotein A-IV were shown to form discrete HDL particles containing these apolipoproteins which may have important but still unexplored functions. Furthermore, several plasma proteins were found associated with HDL and may modulate its biological functions. The effect of these proteins on the functionality of HDL is the topic of ongoing research.
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Affiliation(s)
- Vassilis I Zannis
- Molecular Genetics, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, 02118, USA,
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21
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Challenges in using cultured primary rodent hepatocytes or cell lines to study hepatic HDL receptor SR-BI regulation by its cytoplasmic adaptor PDZK1. PLoS One 2013; 8:e69725. [PMID: 23936087 PMCID: PMC3720616 DOI: 10.1371/journal.pone.0069725] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 06/12/2013] [Indexed: 12/15/2022] Open
Abstract
Background PDZK1 is a four PDZ-domain containing cytoplasmic protein that binds to a variety of membrane proteins via their C-termini and can influence the abundance, localization and/or function of its target proteins. One of these targets in hepatocytes in vivo is the HDL receptor SR-BI. Normal hepatic expression of SR-BI protein requires PDZK1 - <5% of normal hepatic SR-BI is seen in the livers of PDZK1 knockout mice. Progress has been made in identifying features of PDZK1 required to control hepatic SR-BI in vivo using hepatic expression of wild-type and mutant forms of PDZK1 in wild-type and PDZK1 KO transgenic mice. Such in vivo studies are time consuming and expensive, and cannot readily be used to explore many features of the underlying molecular and cellular mechanisms. Methodology/Principal Findings Here we have explored the potential to use either primary rodent hepatocytes in culture using 2D collagen gels with newly developed optimized conditions or PDZK1/SR-BI co-transfected cultured cell lines (COS, HEK293) for such studies. SR-BI and PDZK1 protein and mRNA expression levels fell rapidly in primary hepatocyte cultures, indicating this system does not adequately mimic hepatocytes in vivo for analysis of the PDZK1 dependence of SR-BI. Although PDZK1 did alter SR-BI protein expression in the cell lines, its influence was independent of SR-BI’s C-terminus, and thus is not likely to occur via the same mechanism as that which occurs in hepatocytes in vivo. Conclusions/Significance Caution must be exercised in using primary hepatocytes or cultured cell lines when studying the mechanism underlying the regulation of hepatic SR-BI by PDZK1. It may be possible to use SR-BI and PDZK1 expression as sensitive markers for the in vivo-like state of hepatocytes to further improve primary hepatocyte cell culture conditions.
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22
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Goldberg IJ, Huang LS, Huggins LA, Yu S, Nagareddy PR, Scanlan TS, Ehrenkranz JR. Thyroid hormone reduces cholesterol via a non-LDL receptor-mediated pathway. Endocrinology 2012; 153:5143-9. [PMID: 22948212 PMCID: PMC3473203 DOI: 10.1210/en.2012-1572] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/24/2012] [Accepted: 08/07/2012] [Indexed: 12/27/2022]
Abstract
Although studies in vitro and in hypothyroid animals show that thyroid hormone can, under some circumstances, modulate the actions of low-density lipoprotein (LDL) receptors, the mechanisms responsible for thyroid hormone's lipid-lowering effects are not completely understood. We tested whether LDL receptor (LDLR) expression was required for cholesterol reduction by treating control and LDLR-knockout mice with two forms of thyroid hormone T(3) and 3,5-diiodo-l-thyronine. High doses of both 3,5-diiodo-l-thyronine and T(3) dramatically reduced circulating total and very low-density lipoprotein/LDL cholesterol (∼70%) and were associated with reduced plasma T(4) level. The cholesterol reduction was especially evident in the LDLR-knockout mice. Circulating levels of both apolipoprotein B (apo)B48 and apoB100 were decreased. Surprisingly, this reduction was not associated with increased protein or mRNA expression of the hepatic lipoprotein receptors LDLR-related protein 1 or scavenger receptor-B1. Liver production of apoB was markedly reduced, whereas triglyceride production was increased. Thus, thyroid hormones reduce apoB lipoproteins via a non-LDLR pathway that leads to decreased liver apoB production. This suggests that drugs that operate in a similar manner could be a new therapy for patients with genetic defects in the LDLR.
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Affiliation(s)
- Ira J Goldberg
- Department of Medicine, Columbia University, New York, New York 10032, USA.
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Sy C, Gleize B, Dangles O, Landrier JF, Veyrat CC, Borel P. Effects of physicochemical properties of carotenoids on their bioaccessibility, intestinal cell uptake, and blood and tissue concentrations. Mol Nutr Food Res 2012; 56:1385-97. [PMID: 22815251 DOI: 10.1002/mnfr.201200041] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 05/15/2012] [Accepted: 05/23/2012] [Indexed: 12/16/2022]
Abstract
SCOPE Carotenoid bioavailability is affected by numerous factors. Our aim was to assess the involvement of known carotenoid physicochemical properties (e.g., hydrophobicity, van der Waals volume,…) on the transport of the main dietary carotenoids (β-carotene, lycopene, lutein, and astaxanthin, from their food matrix to their main storage tissues. METHODS AND RESULTS We used four complementary models: synthetic mixed micelles, an in vitro digestion procedure, Caco-2 cell monolayers, and a gavage experiment in rats. The efficiency with which pure carotenoids were incorporated into synthetic mixed micelles was related to their melting points (r = 0.99, p = 0.015). The efficiency with which pure carotenoids were transferred from dietary triglycerides into mixed micelles was related to carotenoid hydrophobicity (r = -1, p = 0.005). There was no relationship between the carotenoid physicochemical properties studied and their uptake efficiency by Caco-2. The postprandial plasma carotenoid response to carotenoid gavage was related to carotenoid hydrophobicity (r = -0.99, p = 0.006). Carotenoid adipose tissue response was not related to the carotenoid physicochemical properties studied. CONCLUSION Thus, carotenoid hydrophobicity is important for bioaccessibility and postprandial blood response of carotenoids. In contrast, the carotenoid physicochemical properties studied are apparently not strong determinants of carotenoid uptake by enterocytes and adipose tissue.
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Affiliation(s)
- Charlotte Sy
- INRA, UMR1260, Nutrition Obesity and Risk of Thrombosis, Marseille, France
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Wang L, Shearer GC, Budamagunta MS, Voss JC, Molfino A, Kaysen GA. Proteinuria decreases tissue lipoprotein receptor levels resulting in altered lipoprotein structure and increasing lipid levels. Kidney Int 2012; 82:990-9. [PMID: 22785171 DOI: 10.1038/ki.2012.244] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Rats with nephrotic syndrome (NS) have a fivefold increase in lipids and a similar decrease in triglyceride-rich lipoprotein (TRL) clearance. Lipoprotein lipase (LPL) is reduced both in NS and in the Nagase analbuminemic rat. These rats have nearly normal triglyceride levels and TRL clearance, suggesting that reduction in LPL alone is insufficient to cause increased TRL levels. Apolipoprotein E (apoE) was decreased in lipoprotein fractions in NS, but not in analbuminemia. Here we tested whether decreased apoE binding to lipoproteins in NS contributes to hyperlipidemia by decreasing their affinity for lipoprotein receptors. Plasma apoE was increased 60% in both NS and analbuminemia compared with control (CTRL) as a result of a 60% decreased apoE clearance. Very-low-density lipoprotein and high-density lipoprotein in NS had significantly less apoE per mole of phospholipid compared with analbuminemia or CTRL and significantly greater lipid content; however, apoE binding did not differ by lipoprotein class or group. There was a significant reduction of receptors for lipoproteins in nearly all tissues in NS compared with CTRL and analbuminemia. Thus, apoE within lipoprotein fractions was reduced by dilution resulting from expansion of the lipid fraction due to decreased lipolysis and not to differing affinity for apoE. Decreased lipoprotein receptors result from proteinuria and contribute to hyperlipidemia in NS.
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Affiliation(s)
- Limin Wang
- Department of Veteran's Affairs, Northern California Health Care System, Mather, California, USA.
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Laatsch A, Panteli M, Sornsakrin M, Hoffzimmer B, Grewal T, Heeren J. Low density lipoprotein receptor-related protein 1 dependent endosomal trapping and recycling of apolipoprotein E. PLoS One 2012; 7:e29385. [PMID: 22238606 PMCID: PMC3251589 DOI: 10.1371/journal.pone.0029385] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Accepted: 11/28/2011] [Indexed: 11/19/2022] Open
Abstract
Background Lipoprotein receptors from the low density lipoprotein (LDL) receptor family are multifunctional membrane proteins which can efficiently mediate endocytosis and thereby facilitate lipoprotein clearance from the plasma. The biggest member of this family, the LDL receptor-related protein 1 (LRP1), facilitates the hepatic uptake of triglyceride-rich lipoproteins (TRL) via interaction with apolipoprotein E (apoE). In contrast to the classical LDL degradation pathway, TRL disintegrate in peripheral endosomes, and core lipids and apoB are targeted along the endocytic pathway for lysosomal degradation. Notably, TRL-derived apoE remains within recycling endosomes and is then mobilized by high density lipoproteins (HDL) for re-secretion. The aim of this study is to investigate the involvement of LRP1 in the regulation of apoE recycling. Principal Findings Immunofluorescence studies indicate the LRP1-dependent trapping of apoE in EEA1-positive endosomes in human hepatoma cells. This processing is distinct from other LRP1 ligands such as RAP which is efficiently targeted to lysosomal compartments. Upon stimulation of HDL-induced recycling, apoE is released from LRP1-positive endosomes but is targeted to another, distinct population of early endosomes that contain HDL, but not LRP1. For subsequent analysis of the recycling capacity, we expressed the full-length human LRP1 and used an RNA interference approach to manipulate the expression levels of LRP1. In support of LRP1 determining the intracellular fate of apoE, overexpression of LRP1 significantly stimulated HDL-induced apoE recycling. Vice versa LRP1 knockdown in HEK293 cells and primary hepatocytes strongly reduced the efficiency of HDL to stimulate apoE secretion. Conclusion We conclude that LRP1 enables apoE to accumulate in an early endosomal recycling compartment that serves as a pool for the intracellular formation and subsequent re-secretion of apoE-enriched HDL particles.
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Affiliation(s)
- Alexander Laatsch
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Malamatenia Panteli
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marijke Sornsakrin
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Britta Hoffzimmer
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Thomas Grewal
- Faculty of Pharmacy A15, The University of Sydney, Sydney, Australia
| | - Joerg Heeren
- Department of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- * E-mail:
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Bassendine MF, Sheridan DA, Felmlee DJ, Bridge SH, Toms GL, Neely RDG. HCV and the hepatic lipid pathway as a potential treatment target. J Hepatol 2011; 55:1428-40. [PMID: 21718665 DOI: 10.1016/j.jhep.2011.06.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 06/15/2011] [Accepted: 06/17/2011] [Indexed: 02/07/2023]
Abstract
Atherosclerosis has been described as a liver disease of the heart [1]. The liver is the central regulatory organ of lipid pathways but since dyslipidaemias are major contributors to cardiovascular disease and type 2 diabetes rather than liver disease, research in this area has not been a major focus for hepatologists. Virus-host interaction is a continuous co-evolutionary process [2] involving the host immune system and viral escape mechanisms [3]. One of the strategies HCV has adopted to escape immune clearance and establish persistent infection is to make use of hepatic lipid pathways. This review aims to: • update the hepatologist on lipid metabolism • review the evidence that HCV exploits hepatic lipid pathways to its advantage • discuss approaches to targeting host lipid pathways as adjunctive therapy.
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Ortega A, Varela LM, Bermudez B, Lopez S, Abia R, Muriana FJG. Dietary fatty acids linking postprandial metabolic response and chronic diseases. Food Funct 2011; 3:22-7. [PMID: 22020286 DOI: 10.1039/c1fo10085h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Chronic diseases are by far one of the main causes of mortality in the world. One of the current global recommendations to counteract disability and premature death resulting from chronic diseases is to decrease the consumption of energy-dense high-fat diets, particularly those rich in saturated fatty acids (SFA). The most effective replacement for SFA in terms of risk factor outcomes for chronic disease are polyunsaturated fatty acids (PUFA) and monounsaturated fatty acids (MUFA). The biochemical basis for healthy benefits of such a dietary pattern has been widely evaluated under fasting conditions. However, the increasing amount of data available from multiple studies suggest that the postprandial state, i.e., "the period that comprises and follows a meal", plays an important, yet underappreciated, role in the genesis of numerous pathological conditions. In this review, the potential of MUFA, PUFA, and SFA to postprandially affect selected metabolic abnormalities related to chronic diseases is discussed.
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Affiliation(s)
- Almudena Ortega
- Laboratory of Cellular and Molecular Nutrition, Instituto de la Grasa (CSIC), 41012 Seville, Spain
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Guo L, Chen M, Song Z, Daugherty A, Li XA. C323 of SR-BI is required for SR-BI-mediated HDL binding and cholesteryl ester uptake. J Lipid Res 2011; 52:2272-2278. [PMID: 21917726 DOI: 10.1194/jlr.m019091] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Scavenger receptor BI (SR-BI) is an HDL receptor. It binds HDL and mediates the uptake of cholesteryl ester from HDL. Early studies have pointed out that the extracellular domain of SR-BI is critical for SR-BI-mediated cholesteryl ester uptake. However, the extracellular loop of SR-BI is large: it contains 403 amino acids. The HDL binding site and the modulation of SR-BI-mediated cholesteryl ester uptake remain to be identified. In this study, using C323G mutant SR-BI, we showed that C323G mutant SR-BI lost its HDL binding and cholesteryl ester uptake activity, indicating that the highly conserved C323 is required for SR-BI-mediated HDL binding and cholesteryl ester uptake. Using a blocking antibody against C323 region, we demonstrated that C323 is directly involved in HDL binding and likely an HDL binding site. Using C323G mutant transgenic mouse model, we further demonstrated that C323 of SR-BI is required for regulating plasma cholesterol levels in vivo. Using redox reagents, we showed that physiological relevant levels of H(2)O(2) upregulated the SR-BI-mediated cholesteryl ester uptake activity by 65%, whereas GSH or DTT significantly downregulated SR-BI-mediated cholesteryl ester uptake activity by 45%. C323 of SR-BI is critical for SR-BI-mediated HDL binding and cholesteryl ester uptake, and changes in redox status may be a regulatory factor modulating SR-BI-mediated cholesterol transport.
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Affiliation(s)
- Ling Guo
- Department of Pediatrics, University of Kentucky Medical School, Lexington, KY
| | - Min Chen
- Department of Pediatrics, University of Kentucky Medical School, Lexington, KY; Taian Central Hospital, Taian, Shandong, China
| | - Zhiqing Song
- Department of Pediatrics, University of Kentucky Medical School, Lexington, KY; Taian Central Hospital, Taian, Shandong, China
| | - Alan Daugherty
- Saha Cardiovascular Research Center, University of Kentucky Medical School, Lexington, KY and
| | - Xiang-An Li
- Department of Pediatrics, University of Kentucky Medical School, Lexington, KY; Saha Cardiovascular Research Center, University of Kentucky Medical School, Lexington, KY and; Graduate Center for Nutritional Sciences, University of Kentucky Medical School, Lexington, KY; and.
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Goldberg IJ, Eckel RH, McPherson R. Triglycerides and heart disease: still a hypothesis? Arterioscler Thromb Vasc Biol 2011; 31:1716-25. [PMID: 21527746 DOI: 10.1161/atvbaha.111.226100] [Citation(s) in RCA: 155] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The purpose of this article is to review the basic and clinical science relating plasma triglycerides and cardiovascular disease. Although many aspects of the basic physiology of triglyceride production, its plasma transport, and its tissue uptake have been known for several decades, the relationship of plasma triglyceride levels to vascular disease is uncertain. Are triglyceride-rich lipoproteins, their influence on high-density lipoprotein and low-density lipoprotein, or the underlying diseases that lead to defects in triglyceride metabolism the culprit? Animal models have failed to confirm that anything other than early fatty lesions can be produced by triglyceride-rich lipoproteins. Metabolic products of triglyceride metabolism can be toxic to arterial cells; however, these studies are primarily in vitro. Correlative studies of fasting and postprandial triglycerides and genetic diseases implicate very-low-density lipoprotein and their remnants and chylomicron remnants in atherosclerosis development, but the concomitant alterations in other lipoproteins and other risk factors obscure any conclusions about direct relationships between disease and triglycerides. Genes that regulate triglyceride levels also correlate with vascular disease. Human intervention trials, however, have lacked an appropriately defined population and have produced outcomes without definitive conclusions. The time is more than ripe for new and creative approaches to understanding the relationship of triglycerides and heart disease.
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Affiliation(s)
- Ira J Goldberg
- Department of Medicine, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA.
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Kent AP, Stylianou IM. Scavenger receptor class B member 1 protein: hepatic regulation and its effects on lipids, reverse cholesterol transport, and atherosclerosis. Hepat Med 2011; 3:29-44. [PMID: 24367219 PMCID: PMC3846864 DOI: 10.2147/hmer.s7860] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Scavenger receptor class B member 1 (SR-BI, also known as SCARB1) is the primary receptor for the selective uptake of cholesterol from high-density lipoprotein (HDL). SR-BI is present in several key tissues; however, its presence and function in the liver is deemed the most relevant for protection against atherosclerosis. Cholesterol is transferred from HDL via SR-BI to the liver, which ultimately results in the excretion of cholesterol via bile and feces in what is known as the reverse cholesterol transport pathway. Much of our knowledge of SR-BI hepatic function and regulation is derived from mouse models and in vitro characterization. Multiple independent regulatory mechanisms of SR-BI have been discovered that operate at the transcriptional and post-transcriptional levels. In this review we summarize the critical discoveries relating to hepatic SR-BI cholesterol metabolism, atherosclerosis, and regulation of SR-BI, as well as alternative functions that may indirectly affect atherosclerosis.
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Affiliation(s)
- Anthony P Kent
- Department of Medicine and Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Ioannis M Stylianou
- Department of Medicine and Institute for Translational Medicine and Therapeutics, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
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D'Ambrosio DN, Clugston RD, Blaner WS. Vitamin A metabolism: an update. Nutrients 2011; 3:63-103. [PMID: 21350678 PMCID: PMC3042718 DOI: 10.3390/nu3010063] [Citation(s) in RCA: 340] [Impact Index Per Article: 26.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Revised: 12/24/2010] [Accepted: 01/11/2011] [Indexed: 12/18/2022] Open
Abstract
Retinoids are required for maintaining many essential physiological processes in the body, including normal growth and development, normal vision, a healthy immune system, normal reproduction, and healthy skin and barrier functions. In excess of 500 genes are thought to be regulated by retinoic acid. 11-cis-retinal serves as the visual chromophore in vision. The body must acquire retinoid from the diet in order to maintain these essential physiological processes. Retinoid metabolism is complex and involves many different retinoid forms, including retinyl esters, retinol, retinal, retinoic acid and oxidized and conjugated metabolites of both retinol and retinoic acid. In addition, retinoid metabolism involves many carrier proteins and enzymes that are specific to retinoid metabolism, as well as other proteins which may be involved in mediating also triglyceride and/or cholesterol metabolism. This review will focus on recent advances for understanding retinoid metabolism that have taken place in the last ten to fifteen years.
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Affiliation(s)
- Diana N D'Ambrosio
- Department of Medicine and Institute of Human Nutrition, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
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Hoekstra M, Berkel TJCV, Eck MV. Scavenger receptor BI: A multi-purpose player in cholesterol and steroid metabolism. World J Gastroenterol 2010; 16:5916-24. [PMID: 21157967 PMCID: PMC3007109 DOI: 10.3748/wjg.v16.i47.5916] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Scavenger receptor class B type I (SR-BI) is an important member of the scavenger receptor family of integral membrane glycoproteins. This review highlights studies in SR-BI knockout mice, which concern the role of SR-BI in cholesterol and steroid metabolism. SR-BI in hepatocytes is the sole molecule involved in selective uptake of cholesteryl esters from high-density lipoprotein (HDL). SR-BI plays a physiological role in binding and uptake of native apolipoprotein B (apoB)-containing lipoproteins by hepatocytes, which identifies SR-BI as a multi-purpose player in lipid uptake from the blood circulation into hepatocytes in mice. In adrenocortical cells, SR-BI mediates the selective uptake of HDL-cholesteryl esters, which is efficiently coupled to the synthesis of glucocorticoids (i.e. corticosterone). SR-BI knockout mice suffer from adrenal glucocorticoid insufficiency, which suggests that functional SR-BI protein is necessary for optimal adrenal steroidogenesis in mice. SR-BI in macrophages plays a dual role in cholesterol metabolism as it is able to take up cholesterol associated with HDL and apoB-containing lipoproteins and can possibly facilitate cholesterol efflux to HDL. Absence of SR-BI is associated with thrombocytopenia and altered thrombosis susceptibility, which suggests a novel role for SR-BI in regulating platelet number and function in mice. Transgenic expression of cholesteryl ester transfer protein in humanized SR-BI knockout mice normalizes hepatic delivery of HDL-cholesteryl esters. However, other pathologies associated with SR-BI deficiency, i.e. increased atherosclerosis susceptibility, adrenal glucocorticoid insufficiency, and impaired platelet function are not normalized, which suggests an important role for SR-BI in cholesterol and steroid metabolism in man. In conclusion, generation of SR-BI knockout mice has significantly contributed to our knowledge of the physiological role of SR-BI. Studies using these mice have identified SR-BI as a multi-purpose player in cholesterol and steroid metabolism because it has distinct roles in reverse cholesterol transport, adrenal steroidogenesis, and platelet function.
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Felmlee DJ, Sheridan DA, Bridge SH, Nielsen SU, Milne RW, Packard CJ, Caslake MJ, McLauchlan J, Toms GL, Neely RDG, Bassendine MF. Intravascular transfer contributes to postprandial increase in numbers of very-low-density hepatitis C virus particles. Gastroenterology 2010; 139:1774-83, 1783.e1-6. [PMID: 20682323 DOI: 10.1053/j.gastro.2010.07.047] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 06/28/2010] [Accepted: 07/22/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND & AIMS The physical association of hepatitis C virus (HCV) particles with lipoproteins in plasma results in distribution of HCV in a broad range of buoyant densities. This association is thought to increase virion infectivity by mediating cell entry via lipoprotein receptors. We sought to determine if factors that affect triglyceride-rich lipoprotein (TRL) metabolism alter the density and dynamics of HCV particles in the plasma of patients with chronic HCV infection. METHODS Fasting patients (n = 10) consumed a high-fat milkshake; plasma was collected and fractionated by density gradients. HCV- RNA was measured in the very-low-density fraction (VLDF, d < 1.025 g/mL) before and at 7 serial time points postprandially. RESULTS The amount of HCV RNA in the VLDF (HCV(VLDF)) increased a mean of 26-fold, peaking 180 minutes after the meal (P < .01). Quantification of HCV RNA throughout the density gradient fractions revealed that HCV(VLDF) rapidly disappeared, rather than migrating into the adjacent density fraction. Immuno-affinity separation of the VLDF, using antibodies that recognize apolipoprotein B-100 and not apolipoprotein B-48, showed that HCV(VLDF) is composed of chylomicron- and VLDL-associated HCV particles; peaking 120 and 180 minutes after the meal, respectively. Plasma from fasting HCV-infected patients mixed with uninfected plasma increased the quantity of HCV(VLDF), compared with that mixed with phosphate-buffered saline, showing extracellular assembly of HCV(VLDF). CONCLUSIONS Dietary triglyceride alters the density and dynamics of HCV in plasma. The rapid clearance rate of HCV(VLDF) indicates that association with TRL is important for HCV infectivity. HCV particles, such as exchangeable apolipoproteins, appear to reassociate with TRLs in the vascular compartment.
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Affiliation(s)
- Daniel J Felmlee
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK.
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Julia Z, Duchene E, Fournier N, Bellanger N, Chapman MJ, Le Goff W, Guerin M. Postprandial lipemia enhances the capacity of large HDL2 particles to mediate free cholesterol efflux via SR-BI and ABCG1 pathways in type IIB hyperlipidemia. J Lipid Res 2010; 51:3350-8. [DOI: 10.1194/jlr.p009746] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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Abstract
PURPOSE OF REVIEW Remnant lipoproteins that persist in the bloodstream after each meal have become increasingly important contributors to atherosclerotic vascular disease, owing to the spread of overnutrition, underexertion, obesity, insulin resistance, and type 2 diabetes. Here, we review recent work that clarified long-standing controversies over the molecular mediators of remnant clearance by the liver, as well as their dysregulation - but possible correction - during alterations in caloric balance. RECENT FINDINGS Two endocytic receptors, the syndecan-1 heparan sulfate proteoglycan (HSPG) and the LDL receptor, plus one docking receptor, SR-BI, significantly contribute to normal hepatic remnant catabolism. Compelling evidence exists for dysfunction of the syndecan-1 HSPG in diabetic states. The major molecular defect identified so far in poorly controlled type 1 diabetes is impaired hepatic HSPG assembly. In contrast, the primary defect in hepatic HSPGs in type 2 diabetes appears to arise from accelerated de-sulfation, owing to the induction of a sulfatase. Moreover, short-term caloric restriction restores hepatic expression of this sulfatase towards normal. SUMMARY Correct identification of hepatic remnant receptors has finally allowed investigations of their molecular dysregulation in diabetes and related conditions. New work points to novel therapeutic targets to correct postprandial dyslipoproteinemia and its consequent arterial damage.
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Affiliation(s)
- Kevin Jon Williams
- Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA.
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36
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Hildebrand RB, Lammers B, Meurs I, Korporaal SJA, De Haan W, Zhao Y, Kruijt JK, Praticò D, Schimmel AWM, Holleboom AG, Hoekstra M, Kuivenhoven JA, Van Berkel TJC, Rensen PCN, Van Eck M. Restoration of high-density lipoprotein levels by cholesteryl ester transfer protein expression in scavenger receptor class B type I (SR-BI) knockout mice does not normalize pathologies associated with SR-BI deficiency. Arterioscler Thromb Vasc Biol 2010; 30:1439-45. [PMID: 20431066 DOI: 10.1161/atvbaha.110.205153] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Disruption of scavenger receptor class B type I (SR-BI) in mice impairs high-density lipoprotein (HDL)-cholesterol (HDL-C) delivery to the liver and induces susceptibility to atherosclerosis. In this study, it was investigated whether introduction of cholesteryl ester transfer protein (CETP) can normalize HDL-C transport to the liver and reduce atherosclerosis in SR-BI knockout (KO) mice. METHODS AND RESULTS Expression of human CETP in SR-BI(KO) mice resulted in decreased plasma HDL-C levels, both on chow diet (1.8-fold, P<0.001) and on challenge with Western-type diet (1.6-fold, P<0.01). Furthermore, the presence of CETP partially normalized the abnormally large HDL particles observed in SR-BI(KO) mice. Unexpectedly, expression of CETP in SR-BI(KO) mice did not reduce atherosclerotic lesion development, probably because of consequences of SR-BI deficiency, including the persistence of higher VLDL-cholesterol (VLDL-C) levels, unchanged elevated free cholesterol/total cholesterol ratio, and the increased oxidative status of the animals. In addition, CETP expression did not normalize other characteristics of SR-BI deficiency, including female infertility, reticulocytosis, thrombocytopenia, and impaired platelet aggregation. CONCLUSIONS CETP restores HDL-C levels in SR-BI(KO) mice, but it does not change the susceptibility to atherosclerosis and other typical characteristics that are associated with SR-BI disruption. This may indicate that the pathophysiology of SR-BI deficiency is not a direct consequence of changes in the HDL pool.
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Affiliation(s)
- Reeni B Hildebrand
- Leiden/Amsterdam Center for Drug Research, Division of Biopharmaceutics, Leiden, the Netherlands
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Levy E, Lalonde G, Delvin E, Elchebly M, Précourt LP, Seidah NG, Spahis S, Rabasa-Lhoret R, Ziv E. Intestinal and hepatic cholesterol carriers in diabetic Psammomys obesus. Endocrinology 2010; 151:958-70. [PMID: 20130116 DOI: 10.1210/en.2009-0866] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Insulin resistance and type 2 diabetes (T2D) are characterized by hyperlipidemia. The aim of the present study was to elucidate whether T2D contributes to abnormal cholesterol (CHOL) homeostasis. Experiments were carried out in the small intestine and liver of Psammomys obesus, a model of nutritionally induced T2D. Our results show that diabetic animals exhibited a lower intestinal CHOL uptake, which was associated with a decrease in 1) the gene and protein expression of Niemann-Pick C1 like 1 that plays a pivotal role in CHOL incorporation in the enterocytes; and 2) mRNA of ATP-binding cassette transporters (ABC)A1 that mediates CHOL efflux from intestinal cells to apolipoprotein A-I and high-density lipoprotein. No changes were observed in the other intestinal transporters scavenger receptor-class B type I (SR-BI) and annexin 2. On the other hand, in diabetic animals, a significant mRNA decrease was noticed in intestinal ABCG5 and ABCG8 responsible for the secretion of absorbed CHOL back into the lumen. Furthermore, jejunal PCSK9 protein was diminished and low-density lipoprotein receptor was raised, along with a significant down-regulation in jejunal 3-hydroxy-3-methylglutaryl-coenzyme A reductase in P. obesus with T2D. Finally, among the transcription factors tested, only an increase in liver X receptors alpha and a decrease in peroxisome proliferator-activated receptors delta/beta mRNAs were detected in the intestine. In the liver, there was 1) an augmentation in the protein mass of Niemann-Pick C1 like 1, SR-BI, and annexin 2; 2) an up-regulation of SR-BI mRNA; 3) a fall in ABCG8 protein content as well as in ABCG5 and ABCA1 mRNA; and 4) an augmentation in liver X receptors alpha and peroxisome proliferator-activated receptors beta/delta mRNA, together with a drop in sterol regulatory element binding protein-2 protein. Our findings show that the development in P. obesus with T2D modifies the whole intraenterocyte and hepatocyte machinery responsible for CHOL homeostasis.
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Affiliation(s)
- Emile Levy
- Gastroenterology, Hepatology, and Nutrition Unit, Research Centre, Sainte-Justine Hospital, 3175 Sainte-Catherine Road, Montréal, Québec, Canada.
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Foley EM, Esko JD. Hepatic heparan sulfate proteoglycans and endocytic clearance of triglyceride-rich lipoproteins. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 93:213-33. [PMID: 20807647 DOI: 10.1016/s1877-1173(10)93010-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hypertriglyceridemia, characterized by the accumulation of triglyceride-rich lipoproteins in the blood, affects 10-20% of the population in western countries and increases the risk of atherosclerosis, coronary artery disease, and pancreatitis. The etiology of hypertriglyceridemia is complex, and much interest exists in identifying and characterizing the biological and environmental factors that affect the synthesis and turnover of plasma triglycerides. Genetic studies in mice have recently identified that heparan sulfate proteoglycans are a class of receptors that mediate the clearance of triglyceride-rich lipoproteins in the liver. Heparan sulfate proteoglycans are expressed by endothelial cells that line the hepatic sinusoids and the underlying hepatocytes, and are present in the perisinusoidal space (space of Disse). This chapter discusses the dependence of lipoprotein binding on heparan sulfate structure and the identification of hepatocyte syndecan-1 as the primary proteoglycan that mediates triglyceride-rich lipoprotein clearance.
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Affiliation(s)
- Erin M Foley
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA, USA
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Röhrl C, Fruhwürth S, Schreier SM, Lohninger A, Dolischka A, Hüttinger M, Zemann N, Hermann M, Strobl W, Stangl H. Scavenger receptor, Class B, Type I provides an alternative means for beta-VLDL uptake independent of the LDL receptor in tissue culture. Biochim Biophys Acta Mol Cell Biol Lipids 2009; 1801:198-204. [PMID: 19932762 DOI: 10.1016/j.bbalip.2009.11.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 10/20/2009] [Accepted: 11/13/2009] [Indexed: 11/19/2022]
Abstract
Recent evidence suggests that scavenger receptor, class B, type I (SR-BI) plays a physiological role in VLDL metabolism. SR-BI was reported to mediate beta-VLDL uptake; however, cellular details of this process are not well characterized. In the present study we show that SR-BI delivers cholesterol derived from beta-VLDL to LDL receptor negative SR-BI over-expressing Chinese Hamster Ovarian cells (ldlA7-SRBI). Cell association of beta-VLDL was approximately 3 times higher after SR-BI over-expression, which was competed by beta-VLDL, but only to a lesser extent by HDL and LDL. Almost all of the associated beta-VLDL was located intracellularly, and therefore could not be released by a 50-fold excess of unlabeled beta-VLDL. beta-VLDL was degraded at a rate of 6 ng beta-VLDL/mg cell protein and hour. In contrast to ldlA7 cells, beta-VLDL association was competed by LDL in cells with a functional LDL receptor like CHO and HepG2 cells, indicating a strong impact of the LDL receptor in beta-VLDL uptake. beta-VLDL degradation was similar to ldlA7-SRBI cells. When beta-VLDL uptake was followed using fluorescence microscopy, beta-VLDL showed a different uptake pattern in SR-BI over-expressing cells, ldlA7-SRBI, compared to LDL receptor containing cells, CHO and HepG2.
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Affiliation(s)
- Clemens Röhrl
- Center for Physiology and Pathophysiology, Department of Medical Chemistry, Medical University of Vienna, Währingerstrabetae 10, 1090 Vienna, Austria
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Wiersma H, Nijstad N, Gautier T, Iqbal J, Kuipers F, Hussain MM, Tietge UJF. Scavenger receptor BI facilitates hepatic very low density lipoprotein production in mice. J Lipid Res 2009; 51:544-53. [PMID: 19723664 DOI: 10.1194/jlr.m000844] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Scavenger receptor BI (SR-BI) is a selective uptake receptor for HDL cholesterol but is also involved in the catabolism of apolipoprotein (apo)B-containing lipoproteins. However, plasma levels of apoB-containing lipoproteins increase following hepatic SR-BI overexpression, suggesting that SR-BI not solely mediates their catabolism. We therefore tested the hypothesis that hepatic SR-BI impacts on VLDL production. On day 7 following adenovirus (Ad)-mediated overexpression of SR-BI, VLDL-triglyceride and VLDL-apoB production rates were significantly increased (P < 0.001), whereas VLDL production was significantly lower in SR-BI knockout mice compared with controls (P < 0.05). In mice injected with AdSR-BI, hepatic cholesterol content increased (P < 0.001), microsomal triglyceride transfer protein activity was higher (P < 0.01) and expression of sterol-regulatory element binding protein (SREBP)2 and its target genes was decreased (P < 0.01). Conversely, in SR-BI knockout mice, microsomal triglyceride transfer protein activity was lower and expression of SREBP2 target genes was increased (P < 0.01). Finally, we demonstrate in vitro in isolated primary hepatocytes as well as in vivo that cholesterol derived from HDL and taken up via SR-BI into the liver can be resecreted within VLDL. These data indicate that hepatic SR-BI expression is linked to VLDL production, and within liver, a metabolic shunt might exist that delivers HDL cholesterol, at least in part, to a pool from which cholesterol is mobilized for VLDL production. These results might have implications for HDL-based therapies against atherosclerotic cardiovascular disease, especially with SR-BI as target.
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Affiliation(s)
- Harmen Wiersma
- Department of Pediatrics, Center for Liver, Digestive and Metabolic Diseases, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
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Santos RD. Commentary on the study of Laatsch et al. “Insulin stimulates hepatic low density lipoprotein receptor-related protein 1 (LRP1) to increase postprandial lipoprotein clearance”. Atherosclerosis 2009; 204:112-3. [DOI: 10.1016/j.atherosclerosis.2008.10.018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 10/17/2008] [Indexed: 11/30/2022]
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Connelly MA. SR-BI-mediated HDL cholesteryl ester delivery in the adrenal gland. Mol Cell Endocrinol 2009; 300:83-8. [PMID: 18840501 DOI: 10.1016/j.mce.2008.09.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2008] [Accepted: 09/04/2008] [Indexed: 10/21/2022]
Abstract
In adrenocortical cells, scavenger receptor class B, type I (SR-BI) is localized in specialized plasma membrane compartments, called microvillar channels, that retain high density lipoprotein particles (HDL) and are sites for the selective uptake of cholesteryl esters (CE). Formation of microvillar channels is regulated by adrenocorticotropic hormone (ACTH) and requires SR-BI expression. Subsequent to SR-BI-mediated delivery to the plasma membrane, HDL-CE is metabolized to free cholesterol by hormone sensitive lipase and transported to the mitochondria for steroid synthesis via START domain proteins. The relevance of SR-BI to adrenal steroidogenesis is evident by the impairment of glucocorticoid-mediated stress response in the absence of SR-BI-mediated HDL-CE uptake in mice. On the molecular level, SR-BI mediates HDL-CE selective uptake by forming a hydrophobic channel. In addition, SR-BI facilitates bi-directional flux of cholesterol by modifying the phospholipid content of the plasma membrane. SR-BI most likely accomplishes these functions by forming homo-oligomers in the plasma membrane. Examination of SR-BI oligomerization using fluorescence resonance energy transfer spectroscopy revealed that SR-BI multimerizes via its C-terminal region. Overall, SR-BI is the cell surface receptor responsible for selective uptake of lipoprotein cholesterol and its ultimate delivery to sites of hormone synthesis in steroidogenic tissues.
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Affiliation(s)
- Margery A Connelly
- Metabolic Diseases, Johnson & Johnson Pharmaceutical Research and Development, LLC, Welsh & McKean Roads, Spring House, PA 19477-0776, United States.
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Fenske SA, Yesilaltay A, Pal R, Daniels K, Barker C, Quiñones V, Rigotti A, Krieger M, Kocher O. Normal hepatic cell surface localization of the high density lipoprotein receptor, scavenger receptor class B, type I, depends on all four PDZ domains of PDZK1. J Biol Chem 2008; 284:5797-806. [PMID: 19116202 DOI: 10.1074/jbc.m808211200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PDZK1 is a four PDZ domain-containing scaffold protein that binds to scavenger receptor class B, type I (SR-BI), the high density lipoprotein receptor, by its first PDZ domain (PDZ1). PDZK1 knock-out mice exhibit a >95% decrease in hepatic SR-BI protein and consequently an approximately 70% increase in plasma cholesterol in abnormally large high density lipoprotein particles. These defects are corrected by hepatic overexpression of full-length PDZK1 but not the PDZ1 domain alone, which partially restores SR-BI protein abundance but not cell surface expression or function. We have generated PDZK1 knock-out mice with hepatic expression of four PDZK1 transgenes encoding proteins with nested C-terminal truncations: pTEM, which lacks the three C-terminal residues (putative PDZ-binding motif), and PDZ1.2, PDZ1.2.3, or PDZ1.2.3.4, which contain only the first two, three, or four N-terminal PDZ domains, respectively, but not the remaining C-terminal sequences. Hepatic overexpression of pTEM restored normal hepatic SR-BI abundance, localization, and function. Hepatic overexpression of PDZ1.2 or PDZ1.2.3 partially restored SR-BI abundance ( approximately 12 or approximately 30% of wild type, respectively) but did not (PDZ1.2) or only slightly (PDZ1.2.3) restored hepatic SR-BI cell surface localization and function. Hepatic overexpression of PDZ1.2.3.4 completely restored SR-BI protein abundance, cell surface expression, and function (normalization of plasma cholesterol levels). Thus, all four PDZ domains in PDZK1, but not PDZ1-3 alone, are sufficient for its normal control of the abundance, localization, and therefore function of hepatic SR-BI, whereas the residues C-terminal to the PDZ4 domain, including the C-terminal putative PDZ-binding domain, are not required.
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Affiliation(s)
- Sara A Fenske
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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de Haan W, Out R, Berbée JFP, van der Hoogt CC, van Dijk KW, van Berkel TJC, Romijn JA, Jukema JW, Havekes LM, Rensen PCN. Apolipoprotein CI inhibits scavenger receptor BI and increases plasma HDL levels in vivo. Biochem Biophys Res Commun 2008; 377:1294-8. [PMID: 18992221 DOI: 10.1016/j.bbrc.2008.10.147] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 10/30/2008] [Indexed: 10/21/2022]
Abstract
Apolipoprotein CI (apoCI) has been suggested to influence HDL metabolism by activation of LCAT and inhibition of HL and CETP. However, the effect of apoCI on scavenger receptor BI (SR-BI)-mediated uptake of HDL-cholesteryl esters (CE), as well as the net effect of apoCI on HDL metabolism in vivo is unknown. Therefore, we evaluated the effect of apoCI on the SR-BI-mediated uptake of HDL-CE in vitro and determined the net effect of apoCI on HDL metabolism in mice. Enrichment of HDL with apoCI dose-dependently decreased the SR-BI-dependent association of [(3)H]CE-labeled HDL with primary murine hepatocytes, similar to the established SR-BI-inhibitors apoCIII and oxLDL. ApoCI deficiency in mice gene dose-dependently decreased HDL-cholesterol levels. Adenovirus-mediated expression of human apoCI in mice increased HDL levels at a low dose and increased the HDL particle size at higher doses. We conclude that apoCI is a novel inhibitor of SR-BI in vitro and increases HDL levels in vivo.
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Affiliation(s)
- Willeke de Haan
- Dept. of General Internal Medicine, Leiden University Medical Center, P.O. Box 9600, Albinusdreef 2, 2300 RC Leiden, The Netherlands
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Insulin stimulates hepatic low density lipoprotein receptor-related protein 1 (LRP1) to increase postprandial lipoprotein clearance. Atherosclerosis 2008; 204:105-11. [PMID: 18834984 DOI: 10.1016/j.atherosclerosis.2008.07.046] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2008] [Revised: 07/28/2008] [Accepted: 07/30/2008] [Indexed: 01/09/2023]
Abstract
BACKGROUND While the role of insulin in glucose uptake and its aberration in diabetes are well established, the effect of insulin on lipoprotein clearance in the postprandial phase is not yet fully understood. The dietary lipids are carried in chylomicron remnants (CR) which are taken up into the liver mainly via LDLR-related protein 1 (LRP1). In this study, the effect of insulin on LRP1-mediated hepatic CR uptake was investigated. METHODS The study was based on determining the subcellular localisation of LRP1 by subcellular fractionation and immunofluorescence microscopy and correlating those findings with the hepatic uptake of fluorescently or radioactively labelled LRP1-specific ligands and CR in hepatoma cells, primary hepatocytes and mouse models. RESULTS AND CONCLUSION In vitro and in vivo, insulin stimulated the translocation of hepatic LRP1 from intracellular vesicles to the plasma membrane, which correlates with an increased uptake of LRP1-specific ligands. In wild-type mice, a glucose-induced insulin response increased the hepatic uptake of LRP1 ligands while in leptin-deficient obese mice (ob/ob), which are characterised by hepatic insulin resistance, insulin-inducible LRP1 ligand uptake was abolished. Finally, upon hepatic LRP1 knockdown, insulin no longer significantly enhanced CR uptake into the liver. The insulin-induced LRP1-mediated CR uptake, as demonstrated here, suggests that impaired hepatic LRP1 translocation can contribute to the postprandial lipaemia in insulin resistance.
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Fenske SA, Yesilaltay A, Pal R, Daniels K, Rigotti A, Krieger M, Kocher O. Overexpression of the PDZ1 domain of PDZK1 blocks the activity of hepatic scavenger receptor, class B, type I by altering its abundance and cellular localization. J Biol Chem 2008; 283:22097-104. [PMID: 18544532 DOI: 10.1074/jbc.m800029200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
PDZK1 is a four-PDZ domain-containing scaffold protein that, via its first PDZ domain (PDZ1), binds to the C terminus of the high density lipoprotein (HDL) receptor scavenger receptor, class B, type I (SR-BI). Abolishing PDZK1 expression in PDZK1 knock-out (KO) mice leads to a post-transcriptional, tissue-specific decrease in SR-BI protein level and an increase in total plasma cholesterol carried in abnormally large HDL particles. Here we show that, although hepatic overexpression of PDZK1 restored normal SR-BI protein abundance and function in PDZK1 KO mice, hepatic overexpression of only the PDZ1 domain was not sufficient to restore normal SR-BI function. In wild-type mice, overexpression of the PDZ1 domain overcame the activity of the endogenous hepatic PDZK1, resulting in a 75% reduction in hepatic SR-BI protein levels and intracellular mislocalization of the remaining SR-BI. As a consequence, the plasma lipoproteins in PDZ1 transgenic mice resembled those in PDZK1 KO mice (hypercholesterolemia due to large HDL). These results indicate that the PDZ1 domain can control the abundance and localization, and therefore the function, of hepatic SR-BI and that structural features of PDZK1 in addition to its SR-BI-binding PDZ1 domain are required for normal hepatic SR-BI regulation.
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Affiliation(s)
- Sara A Fenske
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Goldberg IJ, Hu Y, Noh HL, Wei J, Huggins LA, Rackmill MG, Hamai H, Reid BN, Blaner WS, Huang LS. Decreased lipoprotein clearance is responsible for increased cholesterol in LDL receptor knockout mice with streptozotocin-induced diabetes. Diabetes 2008; 57:1674-82. [PMID: 18346984 DOI: 10.2337/db08-0083] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE Patients with diabetes often have dyslipidemia and increased postprandial lipidmia. Induction of diabetes in LDL receptor (Ldlr(-/-)) knockout mice also leads to marked dyslipidemia. The reasons for this are unclear. RESEARCH DESIGN AND METHODS We placed Ldlr(-/-) and heterozygous LDL receptor knockout (Ldlr(+/-)) mice on a high-cholesterol (0.15%) diet, induced diabetes with streptozotocin (STZ), and assessed reasons for differences in plasma cholesterol. RESULTS STZ-induced diabetic Ldlr(-/-) mice had plasma cholesterol levels more than double those of nondiabetic controls. Fast-performance liquid chromatography and ultracentrifugation showed an increase in both VLDL and LDL. Plasma VLDL became more cholesterol enriched, and both VLDL and LDL had a greater content of apolipoprotein (apo)E. In LDL the ratio of apoB48 to apoB100 was increased. ApoB production, assessed using [(35)S]methionine labeling in Triton WR1339-treated mice, was not increased in fasting STZ-induced diabetic mice. Similarly, postprandial lipoprotein production was not increased. Reduction of cholesterol in the diet to normalize the amount of cholesterol intake by the control and STZ-induced diabetic animals reduced plasma cholesterol levels in STZ-induced diabetic mice, but plasma cholesterol was still markedly elevated compared with nondiabetic controls. LDL from STZ-induced diabetic mice was cleared from the plasma and trapped more rapidly by livers of control mice. STZ treatment reduced liver expression of the proteoglycan sulfation enzyme, heparan sulfate N-deacetylase/N-sulfotrasferase-1, an effect that was reproduced in cultured hepatocytyes by a high glucose-containing medium. CONCLUSIONS STZ-induced diabetic, cholesterol-fed mice developed hyperlipidemia due to a non-LDL receptor defect in clearance of circulating apoB-containing lipoproteins.
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Affiliation(s)
- Ira J Goldberg
- Division of Preventive Medicine, Columbia University, New York, New York 10032, USA.
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Hu L, van der Hoogt CC, Espirito Santo SMS, Out R, Kypreos KE, van Vlijmen BJM, Van Berkel TJC, Romijn JA, Havekes LM, van Dijk KW, Rensen PCN. The hepatic uptake of VLDL in lrp-ldlr-/-vldlr-/- mice is regulated by LPL activity and involves proteoglycans and SR-BI. J Lipid Res 2008; 49:1553-61. [PMID: 18367731 DOI: 10.1194/jlr.m800130-jlr200] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
LPL activity plays an important role in preceding the VLDL remnant clearance via the three major apolipoprotein E (apoE)-recognizing receptors: the LDL receptor (LDLr), LDL receptor-related protein (LRP), and VLDL receptor (VLDLr). The aim of this study was to determine whether LPL activity is also important for VLDL remnant clearance irrespective of these receptors and to determine the mechanisms involved in the hepatic remnant uptake. Administration of an adenovirus expressing LPL (AdLPL) into lrp(-)ldlr(-/-)vldlr(-/-) mice reduced both VLDL-triglyceride (TG) and VLDL-total cholesterol (TC) levels. Conversely, inhibition of LPL by AdAPOC1 increased plasma VLDL-TG and VLDL-TC levels. Metabolic studies with radiolabeled VLDL-like emulsion particles showed that the clearance and hepatic association of their remnants positively correlated with LPL activity. This hepatic association was independent of the bridging function of LPL and HL, since heparin did not reduce the liver association. In vitro studies demonstrated that VLDL-like emulsion particles avidly bound to the cell surface of primary hepatocytes from lrp(-)ldlr(-/-)vldlr(-/-) mice, followed by slow internalization, and involved heparin-releaseable cell surface proteins as well as scavenger receptor class B type I (SR-BI). Collectively, we conclude that hepatic VLDL remnant uptake in the absence of the three classical apoE-recognizing receptors is regulated by LPL activity and involves heparan sulfate proteoglycans and SR-BI.
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Affiliation(s)
- Lihui Hu
- Netherlands Organization for Applied Scientific Research-Quality of Life, Gaubius Laboratory, 2301 CE Leiden, The Netherlands
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Drover VA, Nguyen DV, Bastie CC, Darlington YF, Abumrad NA, Pessin JE, London E, Sahoo D, Phillips MC. CD36 mediates both cellular uptake of very long chain fatty acids and their intestinal absorption in mice. J Biol Chem 2008; 283:13108-15. [PMID: 18332148 DOI: 10.1074/jbc.m708086200] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The intestine has an extraordinary capacity for fatty acid (FA) absorption. Numerous candidates for a protein-mediated mechanism of dietary FA absorption have been proposed, but firm evidence for this process has remained elusive. Here we show that the scavenger receptor CD36 is required both for the uptake of very long chain FAs (VLCFAs) in cultured cells and the absorption of dietary VLCFAs in mice. We found that the fraction of CD36-dependent saturated fatty acid association/absorption in these model systems is proportional to the FA chain length and specific for fatty acids and fatty alcohols containing very long saturated acyl chains. Moreover, intestinal VLCFA absorption is completely abolished in CD36-null mice fed a high fat diet, illustrating that the predominant mechanism for VLCFA absorption is CD36-dependent. Together, these findings represent the first direct evidence for protein-facilitated FA absorption in the intestine and identify a novel therapeutic target for the treatment of diseases characterized by elevated VLCFA levels.
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Affiliation(s)
- Victor A Drover
- Department of Pharmacology, State University of New York, Stony Brook, New York 11794, USA.
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Scavenger receptor of class B expressed by osteoblastic cells are implicated in the uptake of cholesteryl ester and estradiol from LDL and HDL3. J Bone Miner Res 2008; 23:326-37. [PMID: 17967141 DOI: 10.1359/jbmr.071022] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED Lipoproteins transport many vitamins and hormones that have been shown to be necessary for bone formation. However, the metabolism of LDL and HDL3 by bone-forming osteoblastic cells remains unknown. Here we report that osteoblastic cells express scavenger receptors of class B that are implicated in the uptake of cholesterol and estradiol from LDL and HDL3. INTRODUCTION The bone tissue is continuously remodeled, and its integrity requires a balance between osteoclastic bone resorption and osteoblastic bone formation. Recent studies have reported the importance of triglyceride-rich lipoproteins for the delivery of lipophilic vitamins necessary for normal bone metabolism. However, the ability of osteoblastic cells to process low- and high-density lipoproteins (LDL and HDL3) and the receptors involved remain unknown. MATERIALS AND METHODS Binding, competition, degradation, and selective uptake assays with LDL and HDL3 radiolabeled in their protein and lipid moieties or with [3H]estradiol were conducted on human osteoblasts (MG-63 cell line and primary cultures of human osteoblasts [hOB cells]) and on mouse osteoblasts (MC3T3-E1 cell line and primary cultures of murine osteoblasts [mOB cells]). The expression of scavenger receptors (SRs) by osteoblastic cells was determined by RT-PCR and Western immunoblotting, and cellular localization was assessed by sucrose gradient fractionation. RESULTS Osteoblastic cells were able to bind, internalize, and degrade HDL3 and LDL and are capable of selectively taking up cholesteryl esters (CEs) from these lipoproteins. Also, we provide evidence that osteoblastic cells express SR-BI, SR-BII, and CD36 (SR-Bs receptors) and that these receptors are localized in membrane lipid rafts or caveolin-rich membranes. The selective uptake of CE from LDL and HDL3 by osteoblastic cells was strongly inhibited by the known SR-B ligand oxidized LDL, indicating that SR-B receptors are responsible for the selective uptake. Finally, estradiol carried by LDL and HDL3 was selectively transferred to the osteoblastic cells also through SR-B receptors. CONCLUSIONS Overall, our results suggest a novel mechanism for the routing of cholesterol and estradiol to osteoblasts involving the metabolism of LDL and HDL3 by SR-B receptors.
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