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Zhang T, Chen J, Tang X, Luo Q, Xu D, Yu B. Interaction between adipocytes and high-density lipoprotein:new insights into the mechanism of obesity-induced dyslipidemia and atherosclerosis. Lipids Health Dis 2019; 18:223. [PMID: 31842884 PMCID: PMC6913018 DOI: 10.1186/s12944-019-1170-9] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2019] [Accepted: 12/09/2019] [Indexed: 12/19/2022] Open
Abstract
Obesity is the most common nutritional disorder worldwide and is associated with dyslipidemia and atherosclerotic cardiovascular disease. The hallmark of dyslipidemia in obesity is low high density lipoprotein (HDL) cholesterol (HDL-C) levels. Moreover, the quality of HDL is also changed in the obese setting. However, there are still some disputes on the explanations for this phenomenon. There is increasing evidence that adipose tissue, as an energy storage tissue, participates in several metabolism activities, such as hormone secretion and cholesterol efflux. It can influence overall reverse cholesterol transport and plasma HDL-C level. In obesity individuals, the changes in morphology and function of adipose tissue affect plasma HDL-C levels and HDL function, thus, adipose tissue should be the main target for the treatment of HDL metabolism in obesity. In this review, we will summarize the cross-talk between adipocytes and HDL related to cardiovascular disease and focus on the new insights of the potential mechanism underlying obesity and HDL dysfunction.
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Affiliation(s)
- Tianhua Zhang
- Department of Cardiovascular Medicine, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, People's Republic of China
| | - Jin Chen
- Department of Cardiovascular Medicine, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, People's Republic of China
| | - Xiaoyu Tang
- Department of Cardiovascular Medicine, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, People's Republic of China
| | - Qin Luo
- Department of Cardiovascular Medicine, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, People's Republic of China
| | - Danyan Xu
- Department of Cardiovascular Medicine, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, People's Republic of China
| | - Bilian Yu
- Department of Cardiovascular Medicine, the Second Xiangya Hospital, Central South University, Changsha, Hunan, 410011, People's Republic of China.
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2
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Sahebi R, Hassanian SM, Ghayour‐Mobarhan M, Farrokhi E, Rezayi M, Samadi S, Bahramian S, Ferns GA, Avan A. Scavenger receptor Class B type I as a potential risk stratification biomarker and therapeutic target in cardiovascular disease. J Cell Physiol 2019; 234:16925-16932. [DOI: 10.1002/jcp.28393] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/23/2019] [Accepted: 01/24/2019] [Indexed: 12/14/2022]
Affiliation(s)
- Reza Sahebi
- Department of Modern Sciences and Technologies, Faculty of Medicine Mashhad University of Medical Sciences Mashhad Iran
- Department of Molecular Medicine, School of Advanced Technologies Shahrekord University of Medical Sciences Shahrekord Iran
| | - Seyed Mahdi Hassanian
- Metabolic Syndrome Research Center Mashhad University of Medical Sciences Mashhad Iran
| | - Majid Ghayour‐Mobarhan
- Department of Modern Sciences and Technologies, Faculty of Medicine Mashhad University of Medical Sciences Mashhad Iran
- Metabolic Syndrome Research Center Mashhad University of Medical Sciences Mashhad Iran
| | - Effat Farrokhi
- Department of Molecular Medicine, School of Advanced Technologies Shahrekord University of Medical Sciences Shahrekord Iran
| | - Majid Rezayi
- Metabolic Syndrome Research Center Mashhad University of Medical Sciences Mashhad Iran
| | - Sara Samadi
- Department of Modern Sciences and Technologies, Faculty of Medicine Mashhad University of Medical Sciences Mashhad Iran
| | - Shabbou Bahramian
- Stem Cell Research Center Golestan University of Medical Sciences Gorgan Iran
| | - Gordon A. Ferns
- Division of Medical Education Brighton & Sussex Medical School, Falmer Brighton Sussex
| | - Amir Avan
- Metabolic Syndrome Research Center Mashhad University of Medical Sciences Mashhad Iran
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3
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Guo X, Liao J, Huang X, Wang Y, Huang W, Liu G. Reversal of adipose tissue loss by probucol in mice with deficiency of both scavenger receptor class B type 1 and LDL receptor on high fat diet. Biochem Biophys Res Commun 2018; 497:930-936. [PMID: 28522295 DOI: 10.1016/j.bbrc.2017.05.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 05/03/2017] [Indexed: 01/01/2023]
Affiliation(s)
- Xin Guo
- Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University Health Science Center, Beijing, 100191, China
| | - Jiawei Liao
- Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University Health Science Center, Beijing, 100191, China
| | - Xiaomin Huang
- Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University Health Science Center, Beijing, 100191, China
| | - Yuhui Wang
- Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University Health Science Center, Beijing, 100191, China
| | - Wei Huang
- Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University Health Science Center, Beijing, 100191, China.
| | - George Liu
- Institute of Cardiovascular Sciences and Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Peking University Health Science Center, Beijing, 100191, China.
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4
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Abstract
High-density lipoprotein (HDL) and low-density lipoprotein (LDL), as human endogenous lipoprotein particles, have low toxicity, high selectivity, and good safety. They can avoid the recognition and clearance of human reticuloendothelial system. These synthetic lipoproteins (sLPs) have been attracted extensive attention as the nanovectors for tumor-targeted drug and gene delivery. Herein, recent advances in the field of anticancer based on these two lipid proteins and recombinant lipoproteins (rLPs) as target delivery vectors were analyzed and discussed.
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Affiliation(s)
- Xueqin Zhang
- Active Carbohydrate Research Center, College of Chemistry, Chongqing Normal University, Chongqing, PR China
| | - Gangliang Huang
- Active Carbohydrate Research Center, College of Chemistry, Chongqing Normal University, Chongqing, PR China
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5
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He Y, Su Z, Xue L, Xu H, Zhang C. Co-delivery of erlotinib and doxorubicin by pH-sensitive charge conversion nanocarrier for synergistic therapy. J Control Release 2016; 229:80-92. [DOI: 10.1016/j.jconrel.2016.03.001] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 02/04/2016] [Accepted: 03/01/2016] [Indexed: 12/29/2022]
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6
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Abstract
PURPOSE OF REVIEW Adipose tissue is a critical endocrine and immunological organ that regulates systemic energy homeostasis. During the pathogenesis of obesity, adipocyte hypertrophy is accompanied by adipose tissue inflammation, impeding insulin sensitivity and endocrine function of adipose tissue and other tissues. Adipocyte cholesterol accumulates in proportion to triglyceride as adipocytes undergo hypertrophy. Recent studies suggest that dietary cholesterol contributes to increased adipocyte cholesterol. However, how dietary cholesterol accumulates in adipocytes and its metabolic consequences are poorly understood. This review summarizes recent advances in knowledge of adipocyte cholesterol balance and highlights the emerging role of dietary cholesterol in adipose tissue cholesterol balance, inflammation, and systemic energy metabolism. RECENT FINDINGS Perturbation of cholesterol balance in adipocytes alters intracellular cholesterol distribution and modulates adipocyte insulin and proinflammatory signaling. Adipocyte cholesterol levels are maintained by a balance between dietary cholesterol uptake from triglyceride-enriched lipoproteins and cellular cholesterol efflux to HDL. Recent animal studies established a critical role for dietary cholesterol in promoting adipose tissue inflammation, thereby worsening obesity-mediated metabolic complications. SUMMARY Recent studies identified high dietary cholesterol as a potentiator of adipose tissue inflammation and dysfunction. Reducing excessive dietary cholesterol intake is suggested as a simple, but novel, way to attenuate obesity-associated metabolic diseases.
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Affiliation(s)
- Soonkyu Chung
- Department of Nutrition and Health Sciences, University of Nebraska, Lincoln, NE 68516
| | - John S. Parks
- Department of Internal Medicine/Molecular Medicine, Wake Forest School of Medicine, Winston-Salem, NC 27157
- Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC 27157
- Corresponding author: John S. Parks; Department of Internal Medicine/Section on Molecular Medicine, Wake Forest School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157 phone: 336-716-2145 fax: 336-716-6279
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7
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Angius F, Spolitu S, Uda S, Deligia S, Frau A, Banni S, Collu M, Accossu S, Madeddu C, Serpe R, Batetta B. High-density lipoprotein contribute to G0-G1/S transition in Swiss NIH/3T3 fibroblasts. Sci Rep 2015; 5:17812. [PMID: 26640042 PMCID: PMC4671069 DOI: 10.1038/srep17812] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 10/19/2015] [Indexed: 01/08/2023] Open
Abstract
High density lipoproteins (HDLs) play a crucial role in removing excess cholesterol from peripheral tissues. Although their concentration is lower during conditions of high cell growth rate (cancer and infections), their involvement during cell proliferation is not known. To this aim, we investigated the replicative cycles in synchronised Swiss 3T3 fibroblasts in different experimental conditions: i) contact-inhibited fibroblasts re-entering cell cycle after dilution; ii) scratch-wound assay; iii) serum-deprived cells induced to re-enter G1 by FCS, HDL or PDGF. Analyses were performed during each cell cycle up to quiescence. Cholesterol synthesis increased remarkably during the replicative cycles, decreasing only after cells reached confluence. In contrast, cholesteryl ester (CE) synthesis and content were high at 24 h after dilution and then decreased steeply in the successive cycles. Flow cytometry analysis of DiO-HDL, as well as radiolabeled HDL pulse, demonstrated a significant uptake of CE-HDL in 24 h. DiI-HDL uptake, lipid droplets (LDs) and SR-BI immunostaining and expression followed the same trend. Addition of HDL or PDGF partially restore the proliferation rate and significantly increase SR-BI and pAKT expression in serum-deprived cells. In conclusion, cell transition from G0 to G1/S requires CE-HDL uptake, leading to CE-HDL/SR-BI pathway activation and CEs increase into LDs.
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Affiliation(s)
- Fabrizio Angius
- Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy
| | - Stefano Spolitu
- Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy
| | - Sabrina Uda
- Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy
| | - Stefania Deligia
- Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy
| | - Alessandra Frau
- Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy
| | - Sebastiano Banni
- Divisions of Physiology, University of Cagliari, Cagliari, Italy
| | - Maria Collu
- Neuroscience and Clinical Pharmacology, University of Cagliari, Cagliari, Italy
| | - Simonetta Accossu
- Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy
| | - Clelia Madeddu
- Department of Biomedical Sciences, Department of Medical Sciences "Mario Aresu", University of Cagliari, Cagliari, Italy
| | - Roberto Serpe
- Department of Biomedical Sciences, Department of Medical Sciences "Mario Aresu", University of Cagliari, Cagliari, Italy
| | - Barbara Batetta
- Unit of Experimental Medicine, University of Cagliari, Cagliari, Italy
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8
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Lindahl M, Petrlova J, Dalla-Riva J, Wasserstrom S, Rippe C, Domingo-Espin J, Kotowska D, Krupinska E, Berggreen C, Jones HA, Swärd K, Lagerstedt JO, Göransson O, Stenkula KG. ApoA-I Milano stimulates lipolysis in adipose cells independently of cAMP/PKA activation. J Lipid Res 2015; 56:2248-59. [PMID: 26504176 DOI: 10.1194/jlr.m054767] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Indexed: 11/20/2022] Open
Abstract
ApoA-I, the main protein component of HDL, is suggested to be involved in metabolic homeostasis. We examined the effects of Milano, a naturally occurring ApoA-I variant, about which little mechanistic information is available. Remarkably, high-fat-fed mice treated with Milano displayed a rapid weight loss greater than ApoA-I WT treated mice, and a significantly reduced adipose tissue mass, without an inflammatory response. Further, lipolysis in adipose cells isolated from mice treated with either WT or Milano was increased. In primary rat adipose cells, Milano stimulated cholesterol efflux and increased glycerol release, independently of β-adrenergic stimulation and phosphorylation of hormone sensitive lipase (Ser563) and perilipin (Ser522). Stimulation with Milano had a significantly greater effect on glycerol release compared with WT but similar effect on cholesterol efflux. Pharmacological inhibition or siRNA silencing of ABCA1 did not diminish Milano-stimulated lipolysis, although binding to the cell surface was decreased, as analyzed by fluorescence microscopy. Interestingly, methyl-β-cyclodextrin, a well-described cholesterol acceptor, dose-dependently stimulated lipolysis. Together, these results suggest that decreased fat mass and increased lipolysis following Milano treatment in vivo is partly explained by a novel mechanism at the adipose cell level comprising stimulation of lipolysis independently of the canonical cAMP/protein kinase A signaling pathway.
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Affiliation(s)
- Maria Lindahl
- Medical Protein Science, Lund University, 221 84 Lund, Sweden Glucose Transport and Protein Trafficking, Lund University, 221 84 Lund, Sweden
| | - Jitka Petrlova
- Medical Protein Science, Lund University, 221 84 Lund, Sweden
| | | | | | - Catarina Rippe
- Cellular Biomechanics, Lund University, 221 84 Lund, Sweden
| | | | - Dorota Kotowska
- Glucose Transport and Protein Trafficking, Lund University, 221 84 Lund, Sweden
| | - Ewa Krupinska
- Medical Protein Science, Lund University, 221 84 Lund, Sweden
| | | | - Helena A Jones
- Molecular Endocrinology, Department of Experimental Medical Science, Biomedical Center, Lund University, 221 84 Lund, Sweden
| | - Karl Swärd
- Cellular Biomechanics, Lund University, 221 84 Lund, Sweden
| | | | - Olga Göransson
- Protein Phosphorylation, Lund University, 221 84 Lund, Sweden
| | - Karin G Stenkula
- Glucose Transport and Protein Trafficking, Lund University, 221 84 Lund, Sweden
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9
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Samouillan V, Revuelta-López E, Dandurand J, Nasarre L, Badimon L, Lacabanne C, Llorente-Cortés V. Cardiomyocyte intracellular cholesteryl ester accumulation promotes tropoelastin physical alteration and degradation: Role of LRP1 and cathepsin S. Int J Biochem Cell Biol 2014; 55:209-19. [PMID: 25218173 DOI: 10.1016/j.biocel.2014.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Revised: 09/01/2014] [Accepted: 09/03/2014] [Indexed: 11/26/2022]
Abstract
Dyslipemia has a direct impact on cardiac remodeling by altering extracellular matrix (ECM) components. One of the main ECM components is elastin, a proteic three-dimensional network that can be efficiently degraded by cysteine proteases or cathepsins. Dyslipemic status in insulin resistance and combined hyperlipoproteinemia diseases include raised levels of very low density lipoproteins (VLDL), triglyceride (TG)-cholesteryl ester (CE)-rich lipoproteins. Enhanced VLDL concentration promotes cardiomyocyte intracellular cholesteryl ester (CE) accumulation in a LRP1-dependent manner. The aim of this work was to analyze the effect of cardiomyocyte intracellular CE accumulation on tropoelastin (TE) characteristics and to investigate the role of LRP1 and cathepsin S (CatS) on these effects. Molecular studies showed that LRP1 deficiency impaired CE selective uptake and accumulation from TG-CE-rich lipoproteins (VLDL+IDL) and CE-rich lipoproteins (aggregated LDL, agLDL). Biochemical and confocal microscopic studies showed that LRP1-mediated intracellular CE accumulation increased CatS mature protein levels and induced an altered intracellular TE globule structure. Biophysical studies evidenced that LRP1-mediated intracellular CE accumulation caused a significant drop of Tg2 glass transition temperature of cardiomyocyte secreted TE. Moreover, CatS deficiency prevented the alterations in TE intracellular globule structure and on TE glass transition temperature. These results demonstrate that LRP1-mediated cardiomyocyte intracellular CE accumulation alters the structural and physical characteristics of secreted TE through an increase in CatS mature protein levels. Therefore, the modulation of LRP1-mediated intracellular CE accumulation in cardiomyocytes could impact pathological ventricular remodeling associated with insulin-resistance and combined hyperlipoproteinemia, pathologies characterized by enhanced concentrations of TG-CE-rich lipoproteins.
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Affiliation(s)
- Valerie Samouillan
- Physique des Polymères, Institut Carnot, CIRIMAT UMR 5085, Université Paul Sabatier, Bat 3R1B2, 118 route de Narbonne, 31062 Toulouse Cedex 04, France.
| | - Elena Revuelta-López
- Cardiovascular Research Center, CSIC-ICCC, IIB-Sant Pau, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
| | - Jany Dandurand
- Physique des Polymères, Institut Carnot, CIRIMAT UMR 5085, Université Paul Sabatier, Bat 3R1B2, 118 route de Narbonne, 31062 Toulouse Cedex 04, France
| | - Laura Nasarre
- Cardiovascular Research Center, CSIC-ICCC, IIB-Sant Pau, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
| | - Lina Badimon
- Cardiovascular Research Center, CSIC-ICCC, IIB-Sant Pau, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain
| | - Colette Lacabanne
- Physique des Polymères, Institut Carnot, CIRIMAT UMR 5085, Université Paul Sabatier, Bat 3R1B2, 118 route de Narbonne, 31062 Toulouse Cedex 04, France
| | - Vicenta Llorente-Cortés
- Cardiovascular Research Center, CSIC-ICCC, IIB-Sant Pau, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain.
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10
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Aguilar D, Fernandez ML. Hypercholesterolemia induces adipose dysfunction in conditions of obesity and nonobesity. Adv Nutr 2014; 5:497-502. [PMID: 25469381 PMCID: PMC4188221 DOI: 10.3945/an.114.005934] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
It is well known that hypercholesterolemia can lead to atherosclerosis and coronary heart disease. Adipose tissue represents an active endocrine and metabolic site, which might be involved in the development of chronic disease. Because adipose tissue is a key site for cholesterol metabolism and the presence of hypercholesterolemia has been shown to induce adipocyte cholesterol overload, it is critical to investigate the role of hypercholesterolemia on normal adipose function. Studies in preadipocytes revealed that cholesterol accumulation can impair adipocyte differentiation and maturation by affecting multiple transcription factors. Hypercholesterolemia has been observed to cause adipocyte hypertrophy, adipose tissue inflammation, and disruption of endocrine function in animal studies. Moreover, these effects can also be observed in obesity-independent conditions as confirmed by clinical trials. In humans, hypercholesterolemia disrupts adipose hormone secretion of visfatin, leptin, and adiponectin, adipokines that play a central role in numerous metabolic pathways and regulate basic physiologic responses such as appetite and satiety. Remarkably, treatment with cholesterol-lowering drugs has been shown to restore adipose tissue endocrine function. In this review the role of hypercholesterolemia on adipose tissue differentiation and maturation, as well as on hormone secretion and physiologic outcomes, in obesity and non–obesity conditions is presented.
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11
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Rinninger F, Heine M, Singaraja R, Hayden M, Brundert M, Ramakrishnan R, Heeren J. High density lipoprotein metabolism in low density lipoprotein receptor-deficient mice. J Lipid Res 2014; 55:1914-24. [PMID: 24954421 DOI: 10.1194/jlr.m048819] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The LDL receptor (LDLR) and scavenger receptor class B type I (SR-BI) play physiological roles in LDL and HDL metabolism in vivo. In this study, we explored HDL metabolism in LDLR-deficient mice in comparison with WT littermates. Murine HDL was radiolabeled in the protein ((125)I) and in the cholesteryl ester (CE) moiety ([(3)H]). The metabolism of (125)I-/[(3)H]HDL was investigated in plasma and in tissues of mice and in murine hepatocytes. In WT mice, liver and adrenals selectively take up HDL-associated CE ([(3)H]). In contrast, in LDLR(-/-) mice, selective HDL CE uptake is significantly reduced in liver and adrenals. In hepatocytes isolated from LDLR(-/-) mice, selective HDL CE uptake is substantially diminished compared with WT liver cells. Hepatic and adrenal protein expression of lipoprotein receptors SR-BI, cluster of differentiation 36 (CD36), and LDL receptor-related protein 1 (LRP1) was analyzed by immunoblots. The respective protein levels were identical both in hepatic and adrenal membranes prepared from WT or from LDLR(-/-) mice. In summary, an LDLR deficiency substantially decreases selective HDL CE uptake by liver and adrenals. This decrease is independent from regulation of receptor proteins like SR-BI, CD36, and LRP1. Thus, LDLR expression has a substantial impact on both HDL and LDL metabolism in mice.
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Affiliation(s)
- Franz Rinninger
- Department of Medicine, University Hospital Hamburg Eppendorf, 20246 Hamburg, Germany
| | - Markus Heine
- Department of Biochemistry and Molecular Cell Biology, University Hospital Hamburg Eppendorf, 20246 Hamburg, Germany
| | - Roshni Singaraja
- Translational Laboratories in Genetic Medicine, Agency for Science, Technology and Research National University of Singapore, Singapore 117609 Department of Medicine, National University of Singapore, Singapore 117609
| | - Michael Hayden
- Centre for Molecular Medicine and Therapeutics and Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia V5Z 4H4, Canada
| | - May Brundert
- Department of Medicine, University Hospital Hamburg Eppendorf, 20246 Hamburg, Germany
| | - Rajasekhar Ramakrishnan
- Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, NY 10032
| | - Joerg Heeren
- Department of Biochemistry and Molecular Cell Biology, University Hospital Hamburg Eppendorf, 20246 Hamburg, Germany
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12
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Liu M, Seo J, Allegood J, Bi X, Zhu X, Boudyguina E, Gebre AK, Avni D, Shah D, Sorci-Thomas MG, Thomas MJ, Shelness GS, Spiegel S, Parks JS. Hepatic apolipoprotein M (apoM) overexpression stimulates formation of larger apoM/sphingosine 1-phosphate-enriched plasma high density lipoprotein. J Biol Chem 2013; 289:2801-14. [PMID: 24318881 DOI: 10.1074/jbc.m113.499913] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Apolipoprotein M (apoM), a lipocalin family member, preferentially associates with plasma HDL and binds plasma sphingosine 1-phosphate (S1P), a signaling molecule active in immune homeostasis and endothelial barrier function. ApoM overexpression in ABCA1-expressing HEK293 cells stimulated larger nascent HDL formation, compared with cells that did not express apoM; however, the in vivo role of apoM in HDL metabolism remains poorly understood. To test whether hepatic apoM overexpression increases plasma HDL size, we generated hepatocyte-specific apoM transgenic (APOM Tg) mice, which had an ∼3-5-fold increase in plasma apoM levels compared with wild-type mice. Although HDL cholesterol concentrations were similar to wild-type mice, APOM Tg mice had larger plasma HDLs enriched in apoM, cholesteryl ester, lecithin:cholesterol acyltransferase, and S1P. Despite the presence of larger plasma HDLs in APOM Tg mice, in vivo macrophage reverse cholesterol transport capacity was similar to that in wild-type mice. APOM Tg mice had an ∼5-fold increase in plasma S1P, which was predominantly associated with larger plasma HDLs. Primary hepatocytes from APOM Tg mice generated larger nascent HDLs and displayed increased sphingolipid synthesis and S1P secretion. Inhibition of ceramide synthases in hepatocytes increased cellular S1P levels but not S1P secretion, suggesting that apoM is rate-limiting in the export of hepatocyte S1P. Our data indicate that hepatocyte-specific apoM overexpression generates larger nascent HDLs and larger plasma HDLs, which preferentially bind apoM and S1P, and stimulates S1P biosynthesis for secretion. The unique apoM/S1P-enriched plasma HDL may serve to deliver S1P to extrahepatic tissues for atheroprotection and may have other as yet unidentified functions.
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Affiliation(s)
- Mingxia Liu
- From the Departments of Pathology-Lipid Sciences and
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13
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Meyer JM, Ji A, Cai L, van der Westhuyzen DR. High-capacity selective uptake of cholesteryl ester from native LDL during macrophage foam cell formation. J Lipid Res 2012; 53:2081-2091. [PMID: 22833685 PMCID: PMC3435541 DOI: 10.1194/jlr.m026534] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Macrophage foam cells are a defining pathologic feature of atherosclerotic lesions. Recent studies have demonstrated that at high concentrations associated with hypercholesterolemia, native LDL induces macrophage lipid accumulation. LDL particles are taken up by macrophages as part of bulk fluid pinocytosis. However, the uptake and metabolism of cholesterol from native LDL during foam cell formation has not been clearly defined. Previous reports have suggested that selective cholesteryl ester (CE) uptake might contribute to cholesterol uptake from LDL independently of particle endocytosis. In this study we demonstrate that the majority of macrophage LDL-derived cholesterol is acquired by selective CE uptake in excess of LDL pinocytosis and degradation. Macrophage selective CE uptake does not saturate at high LDL concentrations and is not down-regulated during cholesterol accumulation. In contrast to CE uptake, macrophages exhibit little selective uptake of free cholesterol (FC) from LDL. Following selective uptake from LDL, CE is rapidly hydrolyzed by a novel chloroquine-sensitive pathway. FC released from LDL-derived CE hydrolysis is largely effluxed from cells but also is subject to ACAT-mediated reesterification. These results indicate that selective CE uptake plays a major role in macrophage metabolism of LDL.
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Affiliation(s)
- Jason M Meyer
- Departments of Internal Medicine and Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536
| | - Ailing Ji
- Department of Veterans Affairs Medical Center, Lexington, KY 40502; Departments of Internal Medicine and Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536; Barnstable Brown Kentucky Diabetes and Obesity Center, University of Kentucky, Lexington, KY 40536
| | - Lei Cai
- Department of Veterans Affairs Medical Center, Lexington, KY 40502; Departments of Internal Medicine and Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536; Barnstable Brown Kentucky Diabetes and Obesity Center, University of Kentucky, Lexington, KY 40536
| | - Deneys R van der Westhuyzen
- Department of Veterans Affairs Medical Center, Lexington, KY 40502; Departments of Internal Medicine and Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY 40536; Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY 40536; Barnstable Brown Kentucky Diabetes and Obesity Center, University of Kentucky, Lexington, KY 40536.
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14
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Wang H, Peng DQ. New insights into the mechanism of low high-density lipoprotein cholesterol in obesity. Lipids Health Dis 2011; 10:176. [PMID: 21988829 PMCID: PMC3207906 DOI: 10.1186/1476-511x-10-176] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2011] [Accepted: 10/12/2011] [Indexed: 02/06/2023] Open
Abstract
Obesity, a significant risk factor for various chronic diseases, is universally related to dyslipidemia mainly represented by decreasing high-density lipoprotein cholesterol (HDL-C), which plays an indispensible role in development of cardiovascular disease (CVD). However, the mechanisms underlying obesity and low HDL-C have not been fully elucidated. Previous studies have focused on the alteration of HDL catabolism in circulation following elevated triglyceride (TG). But recent findings suggested that liver and fat tissue played pivotal role in obesity related low HDL-C. Some new molecular pathways like microRNA have also been proposed in the regulation of HDL metabolism in obesity. This article will review recent advances in understanding of the potential mechanism of low HDL-C in obesity.
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Affiliation(s)
- Hao Wang
- Departments of Cardiology, the Second Xiangya Hospital, Central South University, Changsha, 410011, Hunan, PR China
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15
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Basford JE, Wancata L, Hofmann SM, Silva RAGD, Davidson WS, Howles PN, Hui DY. Hepatic deficiency of low density lipoprotein receptor-related protein-1 reduces high density lipoprotein secretion and plasma levels in mice. J Biol Chem 2011; 286:13079-87. [PMID: 21343303 DOI: 10.1074/jbc.m111.229369] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The low density lipoprotein receptor-related protein-1 (LRP1) is known to serve as a chylomicron remnant receptor in the liver responsible for the binding and plasma clearance of apolipoprotein E-containing lipoproteins. Previous in vitro studies have provided evidence to suggest that LRP1 expression may also influence high density lipoprotein (HDL) metabolism. The current study showed that liver-specific LRP1 knock-out (hLrp1(-/-)) mice displayed lower fasting plasma HDL cholesterol levels when compared with hLrp1(+/+) mice. Lecithin:cholesterol acyl transferase and hepatic lipase activities in plasma of hLrp1(-/-) mice were comparable with those observed in hLrp1(+/+) mice, indicating that hepatic LRP1 inactivation does not influence plasma HDL remodeling. Plasma clearance of HDL particles and HDL-associated cholesteryl esters was also similar between hLrp1(+/+) and hLrp1(-/-) mice. In contrast, HDL secretion from primary hepatocytes isolated from hLrp1(-/-) mice was significantly reduced when compared with that observed with hLrp1(+/+) hepatocytes. Biotinylation of cell surface proteins revealed decreased surface localization of the ATP-binding cassette, subfamily A, member 1 (ABCA1) protein, but total cellular ABCA1 level was not changed in hLrp1(-/-) hepatocytes. Finally, hLrp1(-/-) hepatocytes displayed reduced binding capacity for extracellular cathepsin D, resulting in lower intracellular cathepsin D content and impairment of prosaposin activation, a process that is required for membrane translocation of ABCA1 to facilitate cholesterol efflux and HDL secretion. Taken together, these results documented that hepatic LRP1 participates in cellular activation of lysosomal enzymes and through this mechanism, indirectly modulates the production and plasma levels of HDL.
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Affiliation(s)
- Joshua E Basford
- Department of Pathology and Laboratory Medicine, Metabolic Diseases Institute, University of Cincinnati College of Medicine, Cincinnati, Ohio 45237, USA
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16
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Brundert M, Heeren J, Merkel M, Carambia A, Herkel J, Groitl P, Dobner T, Ramakrishnan R, Moore KJ, Rinninger F. Scavenger receptor CD36 mediates uptake of high density lipoproteins in mice and by cultured cells. J Lipid Res 2011; 52:745-58. [PMID: 21217164 DOI: 10.1194/jlr.m011981] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mechanisms of HDL-mediated cholesterol transport from peripheral tissues to the liver are incompletely defined. Here the function of scavenger receptor cluster of differentiation 36 (CD36) for HDL uptake by the liver was investigated. CD36 knockout (KO) mice, which were the model, have a 37% increase (P = 0.008) of plasma HDL cholesterol compared with wild-type (WT) littermates. To explore the mechanism of this increase, HDL metabolism was investigated with HDL radiolabeled in the apolipoprotein (¹²⁵I) and cholesteryl ester (CE, [³H]) moiety. Liver uptake of [³H] and ¹²⁵I from HDL decreased in CD36 KO mice and the difference, i. e. hepatic selective CE uptake ([³H]¹²⁵I), declined (-33%, P = 0.0003) in CD36 KO compared with WT mice. Hepatic HDL holo-particle uptake (¹²⁵I) decreased (-29%, P = 0.0038) in CD36 KO mice. In vitro, uptake of ¹²⁵I-/[³H]HDL by primary liver cells from WT or CD36 KO mice revealed a diminished HDL uptake in CD36-deficient hepatocytes. Adenovirus-mediated expression of CD36 in cells induced an increase in selective CE uptake from HDL and a stimulation of holo-particle internalization. In conclusion, CD36 plays a role in HDL uptake in mice and by cultured cells. A physiologic function of CD36 in HDL metabolism in vivo is suggested.
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Affiliation(s)
- May Brundert
- University Hospital Hamburg Eppendorf Hamburg, Germany
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17
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Yue L, Mazzone T. Endogenous adipocyte apolipoprotein E is colocalized with caveolin at the adipocyte plasma membrane. J Lipid Res 2010; 52:489-98. [PMID: 21169230 DOI: 10.1194/jlr.m011809] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Apolipoprotein (apo)E is well established as a secreted protein that plays an important role in systemic lipoprotein metabolism and vascular wall homeostasis. Recently, endogenous expression of apoE in adipocytes has been shown to play an important role in adipocyte lipoprotein metabolism and gene expression consistent with a nonsecreted cellular itinerary for apoE. We designed studies to evaluate if adipocyte apoE was retained as a constituent protein in adipocytes and to identify a cellular retention compartment. Using confocal microscopy, coimmunoprecipitation, and sucrose density cellular fractionation, we establish that endogenous apoE shares a cellular itinerary with the constituent protein caveolin-1. Altering adipocyte caveolar number by modulating cellular cholesterol flux or altering caveolin expression regulates the distribution of cellular apoE between cytoplasmic and plasma membrane compartments. A mechanism for colocalization of apoE with caveolin was established by demonstrating a noncovalent interaction between an aromatic amino acid-enriched apoE N-terminal domain with the caveolin scaffolding domain. Absent apoE expression in adipocytes alters caveolar lipid composition. These observations provide evidence for an interaction between two proteins involved in cellular lipid metabolism in a cell specialized for lipid storage and flux, and rationalize a biological basis for the impact of adipocyte apoE expression on adipocyte lipoprotein metabolism.
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Affiliation(s)
- Lili Yue
- Department of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA
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18
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Yu BL, Zhao SP, Hu JR. Cholesterol imbalance in adipocytes: a possible mechanism of adipocytes dysfunction in obesity. Obes Rev 2010; 11:560-7. [PMID: 20025694 DOI: 10.1111/j.1467-789x.2009.00699.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Studies of the past decade have increased our understanding of the role of adipose tissue dysfunction in obesity and obesity-related insulin resistance and type 2 diabetes. Although adipose tissue is the body's largest pool of free cholesterol, adipocytes have limited activity in cholesterol synthetic pathway. Thus, the majority of adipocyte cholesterol originates from circulating lipoproteins. To maintain cholesterol homeostasis, adipocytes have developed multiple pathways for cholesterol efflux. Several transcriptional factors, such as sterol regulatory element-binding proteins and liver X receptors may be responsible for the regulation of cholesterol homeostasis in adipocytes. Most notably, because altering cholesterol balance profoundly modifies adipocyte metabolism in a way resembling that seen in hypertrophied adipocytes, cholesterol imbalance is recognized as a characteristic for enlarged adipocytes per se in the obese state. In addition, plasma membrane cholesterol normalization by chromium picolinate can fully restore insulin-stimulated glucose transport, further supporting the role of the adipocyte cholesterol imbalance in obesity and insulin resistance.
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Affiliation(s)
- B-L Yu
- Department of Cardiology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, China
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19
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Yue L, Mazzone T. Peroxisome proliferator-activated receptor {gamma} stimulation of adipocyte ApoE gene transcription mediated by the liver receptor X pathway. J Biol Chem 2009; 284:10453-61. [PMID: 19218241 DOI: 10.1074/jbc.m808482200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Peroxisome proliferator-activated receptor (PPARgamma) agonists increase insulin sensitivity in humans and are useful for treating human diabetes. Treatment with these agonists leads to increased apoE expression and triglyceride accumulation in adipocytes. The importance of apoE for adipocyte triglyceride accumulation is demonstrated by observations that triglyceride accumulation is impaired in apoE knockout adipocytes treated with PPARgamma agonists. The current studies investigate the molecular mechanism for PPARgamma stimulation of the adipocyte apoE gene and demonstrate that the liver receptor X (LXR) response element within an apoE gene downstream enhancer is required for the apoE response to PPARgamma agonists. The response of the apoE gene to treatment with PPARgamma agonists was delayed beyond 12 h suggesting the involvement of an intermediary pathway. The combined addition of PPARgamma and LXR agonists did not increase apoE response beyond that observed with addition of either alone. Deletion or mutation of the LXR response element completely eliminated the adipocyte apoE gene response to a PPARgamma agonist. Chromatin immunoprecipitation analyses performed using isolated adipocytes, or adipose tissue from mice treated with PPARgamma agonists, showed increased LXR binding to the apoE gene after PPARgamma agonist treatment. Knockdown of LXR expression completely eliminated the increase in apoE message, protein, and triglyceride in response to PPARgamma stimulation. The LXR response element has been previously shown to mediate sterol responsiveness of the apoE gene, and apoE expression plays an important role in adipocyte triglyceride balance. The current observations suggest that the PPARgamma-LXR-apoE regulatory cascade could be an important molecular link for cross-talk between adipocyte triglyceride and cholesterol homeostasis.
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Affiliation(s)
- Lili Yue
- Departments of Medicine, Pharmacology, and Human Nutrition, University of Illinois, Chicago, Illinois 60612
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20
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Nijstad N, Wiersma H, Gautier T, van der Giet M, Maugeais C, Tietge UJF. Scavenger receptor BI-mediated selective uptake is required for the remodeling of high density lipoprotein by endothelial lipase. J Biol Chem 2009; 284:6093-100. [PMID: 19136670 DOI: 10.1074/jbc.m807683200] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Endothelial lipase (EL) is a negative regulator of high density lipoprotein (HDL) cholesterol plasma levels, and scavenger receptor BI (SR-BI) is involved in remodeling of HDL. The present study investigates the requirement of SR-BI for the effects of EL-mediated phospholipid hydrolysis on HDL metabolism in vivo. In vitro, selective uptake from EL-modified HDL was 129% higher than selective uptake from control HDL in SR-BI-overexpressing cells (p=0.01). In vivo overexpression of human EL by means of recombinant adenovirus decreased HDL plasma levels significantly (p<0.01). Fast protein liquid chromatography analysis and agarose gel electrophoresis revealed that EL expression resulted in the generation of small pre-beta HDL particles in wild-type mice, whereas in SR-BI-/- mice small HDL were preferentially removed. In kinetic experiments the fractional catabolic rate (FCR) of HDL cholesteryl ester increased by 110% (p<0.001), and the FCR of HDL apolipoproteins increased by 64% (p<0.001) in response to EL overexpression in wild-type mice. In SR-BI-/- mice a similar increase in the HDL apolipoprotein FCR occurred (p<0.001); however, there was no further increase in HDL cholesteryl ester catabolism. The apparent whole body selective uptake was increased 3-fold by EL in wild-type mice (p<0.001), whereas there was no selective uptake in SR-BI knock-out mice. EL overexpression increased hepatic selective uptake as well as holoparticle uptake (each p<0.01) in wild-type mice, whereas in SR-BI knock-out mice only holoparticle uptake increased (p<0.01). Our results indicate that SR-BI-mediated selective uptake of HDL cholesteryl ester is essential for the remodeling of large alpha-migrating HDL particles by EL.
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Affiliation(s)
- Niels Nijstad
- Center for Liver, Digestive and Metabolic Diseases, Laboratory of Pediatrics, University Medical Center Groningen, 9713 GZ Groningen, The Netherlands
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21
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Wooten JS, Biggerstaff KD, Anderson C. Response of lipid, lipoprotein-cholesterol, and electrophoretic characteristics of lipoproteins following a single bout of aerobic exercise in women. Eur J Appl Physiol 2008; 104:19-27. [DOI: 10.1007/s00421-008-0770-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/08/2008] [Indexed: 11/28/2022]
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22
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Huang ZH, Reardon CA, Mazzone T. Endogenous ApoE expression modulates adipocyte triglyceride content and turnover. Diabetes 2006; 55:3394-402. [PMID: 17130485 DOI: 10.2337/db06-0354] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Apolipoprotein E (apoE) is highly expressed in adipose tissue and adipocytes in which its expression is regulated by peroxisome proliferator-activated receptor (PPAR)-gamma agonists and tumor necrosis factor-alpha. There is, however, no information regarding a role for endogenous apoE in differentiated adipocyte function. In this report, we define a novel role for apoE in modulating adipocyte lipid metabolism. ApoE(-/-) mice have less body fat and smaller adipocytes compared with wild-type controls. Freshly isolated adipose tissue from apoE(-/-) mice contains lower levels of triglyceride and free fatty acid, and these differences are maintained in cultured adipocytes derived from preadipocytes. Adenoviral expression of apoE in apoE(-/-)-cultured adipocytes increases triglyceride and fatty acid content. During incubation with apoE-containing triglyceride-rich lipoproteins, apoE(-/-) adipose tissue accumulates less triglyceride than wild type. The absence of apoE expression in primary cultured adipocytes also leads to changes in the expression of genes involved in the metabolism/turnover of fatty acids and the triglyceride droplet. Markers of adipocyte differentiation were lower in freshly isolated and cultured apoE(-/-) adipocytes. Importantly, PPAR-gamma-mediated changes in lipid content and gene expression are markedly altered in cultured apoE(-/-) adipocytes. These results establish a novel role for endogenous apoE in adipocyte lipid metabolism and have implications for constructing an integrated model of adipocyte physiology in health and disease.
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Affiliation(s)
- Zhi Hua Huang
- Section of Endocrinology, Diabetes and Metabolism (MC 797), University of Illinois, 1819 W. Polk St., Chicago, IL 60612, USA
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23
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Brundert M, Heeren J, Bahar-Bayansar M, Ewert A, Moore KJ, Rinninger F. Selective uptake of HDL cholesteryl esters and cholesterol efflux from mouse peritoneal macrophages independent of SR-BI. J Lipid Res 2006; 47:2408-21. [PMID: 16926440 DOI: 10.1194/jlr.m600136-jlr200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Scavenger receptor class B type I (SR-BI) mediates the selective uptake of HDL cholesteryl esters (CEs) and facilitates the efflux of unesterified cholesterol. SR-BI expression in macrophages presumably plays a role in atherosclerosis. The role of SR-BI for selective CE uptake and cholesterol efflux in macrophages was explored. Macrophages and HDL originated from wild-type (WT) or SR-BI knockout (KO; homozygous) mice. For uptake, macrophages were incubated in medium containing 125I-/3H-labeled HDL. For lipid removal, [3H]cholesterol efflux was analyzed using HDL as acceptor. Selective uptake of HDL CE ([3H]cholesteryl oleyl ether - 125I-tyramine cellobiose) was similar in WT and SR-BI KO macrophages. Radiolabeled SR-BI KO-HDL yielded a lower rate of selective uptake compared with WT-HDL in WT and SR-BI KO macrophages. Cholesterol efflux was similar in WT and SR-BI KO cells using HDL as acceptor. SR-BI KO-HDL more efficiently promoted cholesterol removal compared with WT-HDL from both types of macrophages. Macrophages selectively take up HDL CE independently of SR-BI. Additionally, in macrophages, there is substantial cholesterol efflux that is not mediated by SR-BI. Therefore, SR-BI-independent mechanisms mediate selective CE uptake and cholesterol removal. SR-BI KO-HDL is an inferior donor for selective CE uptake compared with WT-HDL, whereas SR-BI KO-HDL more efficiently promotes cholesterol efflux.
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Affiliation(s)
- May Brundert
- University Hospital Hamburg Eppendorf, Hamburg, Germany
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24
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Crandall DL, Quinet EM, El Ayachi S, Hreha AL, Leik CE, Savio DA, Juhan-Vague I, Alessi MC. Modulation of adipose tissue development by pharmacological inhibition of PAI-1. Arterioscler Thromb Vasc Biol 2006; 26:2209-15. [PMID: 16825598 DOI: 10.1161/01.atv.0000235605.51400.9d] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The effect of a novel small molecule plasminogen activator inhibitor (PAI-1) inhibitor on adipose tissue physiology was investigated. METHODS AND RESULTS In human preadipocyte cultures, PAI-039 inhibited both basal and glucose-stimulated increases in active PAI-1 antigen, yet had no effect on PAI-1 mRNA, suggesting a direct inactivation of PAI-1. Differentiation of human preadipocytes to adipocytes was associated with leptin synthesis, which was significantly reduced in the presence of PAI-039, together with an atypical adipocyte morphology characterized by a reduction in the size and number of lipid containing vesicles. In a model of diet-induced obesity, pair-fed C57 Bl/6 mice administered PAI-039 in a high-fat diet exhibited a dose-dependent reduction in body weight, epididymal adipose tissue weight, adipocyte volume, and circulating plasma active PAI-1. Plasma glucose, triglycerides, and leptin were also significantly reduced in drug-treated mice, and concentrations of PAI-039 associated with these physiological effects were near the in vitro IC50 for the inhibition of PAI-1. CONCLUSIONS Our results indicate that a small molecule inactivator of PAI-1 can neutralize glucose-stimulated increases in PAI-1 in human preadipocyte cultures, reduce adipocyte differentiation, and prevent the development of diet-induced obesity. These data suggest the pharmacological inhibition of PAI-1 could be beneficial in diseases associated with expansion of adipose tissue mass.
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Affiliation(s)
- David L Crandall
- Cardiovascular and Metabolic Disease Research, Wyeth Research, N2265A, PO Box 42528, Philadelphia, PA 19101, USA.
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25
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Takahashi Y, Zhu H, Xu W, Murakami T, Iwasaki T, Hattori H, Yoshimoto T. Selective uptake and efflux of cholesteryl linoleate in LDL by macrophages expressing 12/15-lipoxygenase. Biochem Biophys Res Commun 2005; 338:128-35. [PMID: 16105647 DOI: 10.1016/j.bbrc.2005.07.182] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2005] [Accepted: 07/30/2005] [Indexed: 01/08/2023]
Abstract
Oxidation of low density lipoprotein (LDL) is a critical step for atherogenesis, and the role of the 12/15-lipoxygenase (12/15-LOX) as well as LDL receptor-related protein (LRP) expressed in macrophages in this process has been suggested. The oxygenation of cholesteryl linoleate in LDL by mouse macrophage-like J774A.1 cells overexpressing 12/15-LOX was inhibited by an anti-LRP antibody but not by an anti-LDL receptor antibody. When the cells were incubated with LDL double-labeled by [3H]cholesteryl linoleate and [125I]apoB, association with the cells of [3H]cholesteryl linoleate expressed as LDL protein equivalent exceeded that of [125I]apoB, indicating selective uptake of [3H]cholesteryl linoleate from LDL to these cells. An anti-LRP antibody inhibited the selective uptake of [3H]cholesteryl ester by 62% and 81% with the 12/15-LOX-expressing cells and macrophages, respectively. Furthermore, addition of LDL to the culture medium of the [3H]cholesteryl linoleate-labeled 12/15-LOX-expressing cells increased the release of [3H]cholesteryl linoleate to the medium in LDL concentration- and time-dependent manners. The transport of [3H]cholesteryl linoleate from the cells to LDL was also inhibited by an anti-LRP antibody by 75%. These results strongly suggest that LRP contributes to the LDL oxidation by 12/15-LOX in macrophages by selective uptake and efflux of cholesteryl ester in the LDL particle.
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Affiliation(s)
- Yoshitaka Takahashi
- Department of Nutritional Science, Faculty of Health and Welfare Science, Okayama Prefectural University, Soja, Okayama 719-1197, Japan.
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26
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Rotllan N, Ribas V, Calpe-Berdiel L, Martín-Campos JM, Blanco-Vaca F, Escolà-Gil JC. Overexpression of Human Apolipoprotein A-II in Transgenic Mice Does Not Impair Macrophage-Specific Reverse Cholesterol Transport In Vivo. Arterioscler Thromb Vasc Biol 2005; 25:e128-32. [PMID: 15994442 DOI: 10.1161/01.atv.0000175760.28378.80] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background—
Overexpression of human apolipoprotein (apo) A-II in transgenic mice induces high-density lipoprotein (HDL) deficiency, and increased atherosclerosis susceptibility only when fed an atherogenic diet. This may, in part, be caused by impairment in reverse cholesterol transport (RCT).
Methods and Results—
[
3
H]cholesterol-labeled macrophages were injected intraperitoneally into mice maintained on a chow diet or an atherogenic diet. Plasma [
3
H]cholesterol did not differ from human apoA-II transgenic and control mice at 24 or 48 hours after the label injection. On the chow diet, human apoA-II transgenic mice presented increased [
3
H]cholesterol in liver (1.3-fold) and feces (6-fold) compared with control mice (
P
<0.05). The magnitude of macrophage-specific RCT did not differ between transgenic and control mice fed the atherogenic diet.
Conclusions—
Human apoA-II maintains effective RCT from macrophages to feces in vivo despite an HDL deficiency. These findings suggest that the increased atherosclerotic lesions observed in apoA-II transgenic mice fed an atherogenic diet are not caused by impairment in macrophage-specific RCT.
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Affiliation(s)
- Noemí Rotllan
- Servei de Bioquímica, Institut de Recerca, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain
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28
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Vassiliou G, McPherson R. Role of cholesteryl ester transfer protein in selective uptake of high density lipoprotein cholesteryl esters by adipocytes. J Lipid Res 2004; 45:1683-93. [PMID: 15231851 DOI: 10.1194/jlr.m400051-jlr200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Previous reports attributed cholesteryl ester transfer protein (CETP)-mediated HDL cholesteryl ester (CE) selective uptake to the CETP-mediated transfer of CE from HDL to newly secreted apolipoprotein B-containing lipoproteins, which are then internalized by the LDL receptor (LDL-R). CETP has also been implicated in the remodeling of HDL, which renders it a better substrate for selective uptake by scavenger receptor class B type I (SR-BI). However, CETP-mediated selective uptake of HDL3-derived CE was not diminished in LDL-R null adipocytes, SR-BI null adipocytes, or in the presence of the receptor-associated protein. We found that monensin treatment or energy depletion of the SW872 liposarcoma cells with 2-deoxyglucose and NaN3 had no effect on CETP-mediated selective uptake, demonstrating that endocytosis is not required. This is supported by data indicating that CETP transfers CE into a compartment from which it can be extracted by unlabeled HDL. CETP could also mediate the selective uptake of HDL3-derived triacylglycerol (TG) and phospholipid (PL). The CETP-specific kinetics for TG and CE uptake were similar, and both reached saturation at approximately 5 microg/ml HDL. In contrast, CETP-specific PL uptake did not attain saturation at 5 microg/ml HDL and was approximately 6-fold greater than the uptake of CE. We propose two possible mechanisms to account for the role of CETP in selective uptake.
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Affiliation(s)
- Gerard Vassiliou
- Lipoprotein and Atherosclerosis Group, University of Ottawa Heart Institute, Ottawa, Ontario K1Y 4E9, Canada.
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