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Rouland A, Masson D, Lagrost L, Vergès B, Gautier T, Bouillet B. Role of apolipoprotein C1 in lipoprotein metabolism, atherosclerosis and diabetes: a systematic review. Cardiovasc Diabetol 2022; 21:272. [PMID: 36471375 PMCID: PMC9724408 DOI: 10.1186/s12933-022-01703-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 11/21/2022] [Indexed: 12/12/2022] Open
Abstract
Apolipoprotein C1 (apoC1) is a small size apolipoprotein whose exact role is not totally clarified but which seems to modulate significantly the metabolism of lipoproteins. ApoC1 is involved in the metabolism of triglyceride-rich lipoproteins by inhibiting the binding of very low density lipoproteins (VLDL) to VLDL-receptor (VLDL-R), to low density lipoprotein receptor (LDL-R) and to LDL receptor related protein (LRP), by reducing the activity of lipoprotein lipase (LPL) and by stimulating VLDL production, all these effects leading to increase plasma triglycerides. ApoC1 takes also part in the metabolism of high density lipoproteins (HDL) by inhibiting Cholesterol Ester Transfer Protein (CETP). The functionality of apoC1 on CETP activity is impaired in diabetes that might account, at least in part, for the increased plasma CETP activity observed in patients with diabetes. Its different effects on lipoprotein metabolism with a possible role in the modulation of inflammation makes the net impact of apoC1 on cardiometabolic risk difficult to figure out and apoC1 might be considered as pro-atherogenic or anti-atherogenic depending on the overall metabolic context. Making the link between total plasma apoC1 levels and the risk of cardio-metabolic diseases is difficult due to the high exchangeability of this small protein whose biological effects might depend essentially on its association with VLDL or HDL. The role of apoC1 in humans is not entirely elucidated and further studies are needed to determine its precise role in lipid metabolism and its possible pleiotropic effects on inflammation and vascular wall biology. In this review, we will present data on apoC1 structure and distribution among lipoproteins, on the effects of apoC1 on VLDL metabolism and HDL metabolism and we will discuss the possible links between apoC1, atherosclerosis and diabetes.
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Affiliation(s)
- Alexia Rouland
- grid.31151.37Endocrinology and Diabetology Unit, University Hospital, Dijon, France ,grid.493090.70000 0004 4910 6615INSERM/University of Bourgogne Franche-Comté, LNC UMR1231, Dijon, France
| | - David Masson
- grid.493090.70000 0004 4910 6615INSERM/University of Bourgogne Franche-Comté, LNC UMR1231, Dijon, France ,LipSTIC LabEx, UFR Sciences de Santé, Dijon, France
| | - Laurent Lagrost
- grid.493090.70000 0004 4910 6615INSERM/University of Bourgogne Franche-Comté, LNC UMR1231, Dijon, France ,LipSTIC LabEx, UFR Sciences de Santé, Dijon, France
| | - Bruno Vergès
- grid.31151.37Endocrinology and Diabetology Unit, University Hospital, Dijon, France ,grid.493090.70000 0004 4910 6615INSERM/University of Bourgogne Franche-Comté, LNC UMR1231, Dijon, France
| | - Thomas Gautier
- grid.493090.70000 0004 4910 6615INSERM/University of Bourgogne Franche-Comté, LNC UMR1231, Dijon, France ,LipSTIC LabEx, UFR Sciences de Santé, Dijon, France
| | - Benjamin Bouillet
- grid.31151.37Endocrinology and Diabetology Unit, University Hospital, Dijon, France ,grid.493090.70000 0004 4910 6615INSERM/University of Bourgogne Franche-Comté, LNC UMR1231, Dijon, France ,grid.31151.37Service Endocrinologie, Diabétologie et Maladies Métaboliques, Hôpital François Mitterrand, CHU Dijon, BP 77908, 21079 Dijon, France
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Morton RE, Liu Y, Izem L. ApoF knockdown increases cholesteryl ester transfer to LDL and impairs cholesterol clearance in fat-fed hamsters. J Lipid Res 2019; 60:1868-1879. [PMID: 31511396 DOI: 10.1194/jlr.ra119000171] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 09/10/2019] [Indexed: 02/04/2023] Open
Abstract
Cholesteryl ester transfer protein (CETP) regulates intravascular lipoprotein metabolism. In vitro studies indicate that ApoF alters CETP function by inhibiting its activity with LDL. To explore in vivo the complexities driving ApoF's effects on CETP, we developed a siRNA-based hamster model of ApoF knockdown. In both male and female hamsters on chow- or fat-fed diets, we measured lipoprotein levels and composition, determined CETP-mediated transfer of cholesteryl esters (CEs) between lipoproteins, and quantified reverse cholesterol transport (RCT). We found that apoF knockdown in chow-fed hamsters had no effect on lipoprotein levels or composition, but these ApoF-deficient lipoproteins supported 50-100% higher LDL CETP activity in vitro. ApoF knockdown in fat-fed male hamsters created a phenotype in which endogenous CETP-mediated CE transfer from HDL to LDL increased up to 2-fold, LDL cholesterol increased 40%, HDL declined 25%, LDL and HDL lipid compositions were altered, and hepatic LDLR gene expression was decreased. Diet-induced hypercholesterolemia obscured this phenotype on occasion. In fat-fed female hamsters, ApoF knockdown caused similar but smaller changes in plasma CETP activity and LDL cholesterol. Notably, ApoF knockdown impaired HDL RCT in fat-fed hamsters but increased sterol excretion in chow-fed animals. These in vivo data validate in vitro findings that ApoF regulates lipid transfer to LDL. The consequences of ApoF knockdown on lipoproteins and sterol excretion depend on the underlying lipid status. By minimizing the transfer of HDL-derived CE to LDL, ApoF helps control LDL cholesterol levels when LDL clearance mechanisms are limiting.
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Affiliation(s)
- Richard E Morton
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
| | - Yan Liu
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
| | - Lahoucine Izem
- Department of Cardiovascular and Metabolic Sciences, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, OH 44195
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Gautier T, Masson D, Lagrost L. The potential of cholesteryl ester transfer protein as a therapeutic target. Expert Opin Ther Targets 2015. [PMID: 26212254 DOI: 10.1517/14728222.2015.1073713] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Over recent decades, attempts to ascertain the pro-atherogenic nature of plasma cholesteryl ester transfer protein (CETP) and to establish the relevance of its pharmacological blockade as a promising high density lipoproteins-raising and anti-atherogenic therapy have been disappointing. AREAS COVERED The current review focuses on CETP as a multifaceted protein, on genetic variations at the CETP gene and on their possible consequences for cardiovascular risk in human populations. Specific attention is given to physiological modulation of endogenous CETP activity by the apoC1 inhibitor. Finally, the rationale behind the need for selection of patients to treat is discussed in the light of recent studies. EXPERT OPINION At this stage one can only speculate on the clinical outcome of pharmacological CETP inhibitors in high-risk populations, but recent advances give cause to adjust the expectations from now on. The CETP effect is probably largely influenced by the overall metabolic state, and whether CETP blockade may be relevant or not in promoting cholesterol disposal is still questioned. The possible need for a careful stratification of patients to treat with CETP inhibitors is outlined. Finally, manipulation of CETP activity should be considered with caution in the context of sepsis and infectious diseases.
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Affiliation(s)
- Thomas Gautier
- a 1 INSERM, LNC UMR866 , F-21000 Dijon, France.,b 2 University of Bourgogne Franche-Comté , F-21000 Dijon, France.,c 3 LipSTIC LabEx, Fondation de Coopération Scientifique Bourgogne-Franche Comté , F-21000 Dijon, France
| | - David Masson
- a 1 INSERM, LNC UMR866 , F-21000 Dijon, France.,b 2 University of Bourgogne Franche-Comté , F-21000 Dijon, France.,c 3 LipSTIC LabEx, Fondation de Coopération Scientifique Bourgogne-Franche Comté , F-21000 Dijon, France.,d 4 University Hospital of Dijon , F-21000 Dijon, France
| | - Laurent Lagrost
- a 1 INSERM, LNC UMR866 , F-21000 Dijon, France.,b 2 University of Bourgogne Franche-Comté , F-21000 Dijon, France.,c 3 LipSTIC LabEx, Fondation de Coopération Scientifique Bourgogne-Franche Comté , F-21000 Dijon, France.,d 4 University Hospital of Dijon , F-21000 Dijon, France.,e 5 UMR866, UFR Sciences de Santé, 7 boulevard Jeanne d'Arc , F-21000 Dijon, France
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Pharmacophore-based design, synthesis, and biological evaluation of novel 3-((3,4-dichlorophenyl)(4-substituted benzyl)amino) propanamides as cholesteryl ester transfer protein (CETP) inhibitors. CHINESE CHEM LETT 2014. [DOI: 10.1016/j.cclet.2013.11.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Rui M, Guo W, Ding Q, Wei X, Xu J, Xu Y. Recombinant high-density lipoprotein nanoparticles containing gadolinium-labeled cholesterol for morphologic and functional magnetic resonance imaging of the liver. Int J Nanomedicine 2012; 7:3751-68. [PMID: 22888232 PMCID: PMC3414207 DOI: 10.2147/ijn.s33139] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Background Natural high-density lipoproteins (HDL) possess important physiological functions to the transport of cholesterol from the peripheral tissues to the liver for metabolic degradation and excretion in the bile. Methods and results In this work, we took advantage of this pathway and prepared two different gadolinium (Gd)-DTPA-labeled cholesterol-containing recombinant HDL nanoparticles (Gd-chol-HDL) and Gd-(chol)2-HDL as liver-specific magnetic resonance imaging (MRI) contrast agents. The reconstituted HDL nanoparticles had structural similarity to native HDL, and could be taken up by HepG2 cells via interaction with HDL receptors in vitro. In vivo MRI studies in rats after intravenous injections of 10 μmol gadolinium per kg of recombinant HDL nanoparticles indicated that both nanoparticles could provide signal enhancement in the liver and related organs. However, different T1-weighted image details suggested that they participated in different cholesterol metabolism and excretion pathways in the liver. Conclusion Such information could be highly useful to differentiate functional changes as well as anatomic differences in the liver. These cholesterol-derived contrast agents and their recombinant HDL preparations may warrant further development as a new class of contrast agents for MRI of the liver and related organs.
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Affiliation(s)
- Mengjie Rui
- School of Life Science and Biotechnology, Shanghai Jiao Tong University, Shanghai, People's Republic of China
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Grion CMC, Cardoso LTQ, Perazolo TF, Garcia AS, Barbosa DS, Morimoto HK, Matsuo T, Carrilho AJF. Lipoproteins and CETP levels as risk factors for severe sepsis in hospitalized patients. Eur J Clin Invest 2010; 40:330-8. [PMID: 20486994 DOI: 10.1111/j.1365-2362.2010.02269.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND The magnitude of lipoprotein level reduction during the acute-phase response may be associated with the severity and mortality of sepsis. However, it remains to be determined whether low lipoprotein levels can be considered a risk factor for developing sepsis. We aimed to investigate lipoprotein levels as risk factors for sepsis in hospitalized patients, and also describe sequential changes in lipoprotein and cholesterol ester transfer protein (CETP) levels during sepsis. DESIGN This is a prospective cohort study and case-control analysis from selected hospitalized patients. Blood samples were collected at admission, and participants were monitored for severe sepsis. Total cholesterol, high density lipoprotein (HDL), low density lipoprotein, and triglyceride levels were compared between sepsis cases and controls. Cholesterol, apolipoprotein, phospholipid and CETP concentrations were monitored in the case group. RESULTS Of 1719 enrolled patients, 51 developed severe sepsis and were paired with 71 controls by age, gender, presence of infection at admission and chronic disease. HDL cholesterol level at admission was a risk factor for severe sepsis (OR = 0.969; 95% CI: 0.944-0.995). Mean CETP levels diminished between hospital admission and day 3 of sepsis. The magnitude of this variation (Delta CETP) was more pronounced in non-survivors (0.78 +/- 1.08 microg mL(-1)) than that in survivors (0.02 +/- 0.58 microg mL(-1), P = 0.01). CONCLUSIONS HDL cholesterol may have a protective effect against sepsis. Each 1 mg dL(-1) increase in HDL decreased the odds of severe sepsis by 3% during hospitalization. The reduction of plasma CETP was associated with mortality.
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Clark RW, Cunningham D, Cong Y, Subashi TA, Tkalcevic GT, Lloyd DB, Boyd JG, Chrunyk BA, Karam GA, Qiu X, Wang IK, Francone OL. Assessment of cholesteryl ester transfer protein inhibitors for interaction with proteins involved in the immune response to infection. J Lipid Res 2009; 51:967-74. [PMID: 19965592 DOI: 10.1194/jlr.m002295] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The CETP inhibitor, torcetrapib, was prematurely terminated from phase 3 clinical trials due to an increase in cardiovascular and noncardiovascular mortality. Because nearly half of the latter deaths involved patients with infection, we have tested torcetrapib and other CETPIs to see if they interfere with lipopolysaccharide binding protein (LBP) or bactericidal/permeability increasing protein (BPI). No effect of these potent CETPIs on LPS binding to either protein was detected. Purified CETP itself bound weakly to LPS with a Kd >or= 25 microM compared with 0.8 and 0.5 nM for LBP and BPI, respectively, and this binding was not blocked by torcetrapib. In whole blood, LPS induced tumor necrosis factor-alpha normally in the presence of torcetrapib. Furthermore, LPS had no effect on CETP activity. We conclude that the sepsis-related mortality of the ILLUMINATE trial was unlikely due to a direct effect of torcetrapib on LBP or BPI function, nor to inhibition of an interaction of CETP with LPS. Instead, we speculate that the negative outcome seen for patients with infections might be related to the changes in plasma lipoprotein composition and metabolism, or alternatively to the known off-target effects of torcetrapib, such as aldosterone elevation, which may have aggravated the effects of sepsis.
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Affiliation(s)
- Ronald W Clark
- Department of Cardiovascular and Metabolic Diseases, Pfizer Global Research and Development, Eastern Point Road, Groton, CT 06340, USA.
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Human cholesteryl ester transfer protein expression enhances the mouse survival rate in an experimental systemic inflammation model: a novel role for CETP. Shock 2009; 30:590-5. [PMID: 18391856 DOI: 10.1097/shk.0b013e31816e30fd] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mice expressing human cholesteryl ester transfer protein (huCETP) are more resistant to Escherichia coli bacterial wall LPS because death rates 5 days after intraperitoneal inoculation of LPS were higher in wild-type than in huCETP+/+ mice, whereas all huCETP+/+ mice remained alive. After LPS inoculation, plasma concentrations of TNF-alpha and IL-6 increased less in huCETP+/+ than in wild-type mice. LPS in vitro elicited lower TNF-alpha production by CETP expressing than by wild-type macrophages. In addition, TNF-alpha production by RAW 264.7 murine macrophages increased on incubation with LPS but decreased in a dose-dependent manner when human CETP was added to the medium. Human CETP in vitro enhanced the LPS binding to plasma high-density lipoprotein/low-density lipoprotein. The liver uptake of intravenous infused 14C-LPS from Salmonella typhimurium was greater in huCETP+/+ than in wild-type mice. Present data indicate for the first time that CETP is an endogenous component involved in the first line of defense against an exacerbated production of proinflammatory mediators.
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Dumont L, Gautier T, de Barros JPP, Laplanche H, Blache D, Ducoroy P, Fruchart J, Fruchart JC, Gambert P, Masson D, Lagrost L. Molecular Mechanism of the Blockade of Plasma Cholesteryl Ester Transfer Protein by Its Physiological Inhibitor Apolipoprotein CI. J Biol Chem 2005; 280:38108-16. [PMID: 16159884 DOI: 10.1074/jbc.m504678200] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Genetically engineered mice demonstrated that apolipoprotein (apo) CI is a potent, physiological inhibitor of plasma cholesteryl ester transfer protein (CETP) activity. The goal of this study was to determine the molecular mechanism of the apoCI-mediated blockade of CETP activity. Kinetic analyses revealed that the inhibitory property of apoCI is independent of the amount of active CETP, but it is tightly dependent on the amount of high density lipoproteins (HDL) in the incubation mixtures. The electrostatic charge of HDL, i.e. the main carrier of apoCI in human plasma, is gradually modified with increasing amounts of apoCI, and the neutralization of apoCI lysine residues by acetylation produces a marked reduction in its inhibitory potential. The inhibitory property of full-length apoCI is shared by its C-terminal alpha-helix with significant electrostratic properties, whereas its N-terminal alpha-helix with no CETP inhibitory property has no effect on HDL electronegativity. Finally, binding experiments demonstrated that apoCI and to a lower extent its C-terminal alpha-helix are able to disrupt CETP-lipoprotein complexes in a concentration-dependent manner. It was concluded that the inhibition of CETP activity by apoCI is in direct link with its specific electrostatic properties, and the apoCI-mediated reduction in the binding properties of lipoproteins results in weaker CETP-HDL interactions and fewer cholesteryl ester transfers.
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Affiliation(s)
- Laure Dumont
- Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté deMédecine, Dijon, France
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Gautier T, Masson D, Jong M, Pais De Barros JP, Duverneuil L, Le Guern N, Deckert V, Dumont L, Bataille A, Zak Z, Jiang XC, Havekes L, Lagrost L. Apolipoprotein CI overexpression is not a relevant strategy to block cholesteryl ester transfer protein (CETP) activity in CETP transgenic mice. Biochem J 2005; 385:189-95. [PMID: 15339254 PMCID: PMC1134687 DOI: 10.1042/bj20041149] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
ApoCI (apolipoprotein CI) is a potent inhibitor of plasma CETP [CE (cholesteryl ester) transfer protein]. The relevance of apoCI overexpression as a method for CETP blockade in vivo was addressed in the present study in CETPTg/apoCITg mice (mice expressing both human CETP and apoCI). Despite a significant reduction in specific CETP activity in CETPTg/apoCITg mice compared with CETPTg mice [transgenic mouse to human CETP; 46.8+/-11.1 versus 101.8+/-25.7 pmol x h(-1).(mug of plasma CETP)(-1) respectively; P<0.05], apoCI overexpression increased both the CETP mass concentration (3-fold increase; P<0.05) and the hepatic CETP mRNA level (4-fold increase, P<0.005), leading to an increase in total plasma CE transfer activity (by 39%, P<0.05). The ratio of apoB-containing lipoprotein to HDL (high-density lipoprotein) CE was 10-fold higher in CETPTg/apoCITg mice than in apoCITg mice (P<0.0005). It is proposed that the increased CETP expression in CETPTg/apoCITg mice is a direct consequence of liver X receptor activation in response to the accumulation of cholesterol-rich apoB-containing lipoproteins. In support of the latter view, hepatic mRNA levels of other liver X receptor-responsive genes [ABCG5 (ATP-binding cassette transporter GS) and SREBP-1c (sterol-regulatory-binding protein-1c)] were higher in CETPTg/apoCITg mice compared with CETPTg mice. In conclusion, overexpression of apoCI, while producing a significant inhibitory effect on specific CETP activity, does not represent a suitable method for decreasing total CE transfer activity in CETPTg/apoCITg mice, owing to an hyperlipidaemia-mediated effect on CETP gene expression.
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Affiliation(s)
- Thomas Gautier
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - David Masson
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - Miek C. Jong
- †Netherlands Organization for Applied Scientific Research (TNO), Prevention and Health, Gaubius Laboratory, 2301 CE Leiden, The Netherlands
| | - Jean-Paul Pais De Barros
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - Linda Duverneuil
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - Naig Le Guern
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - Valérie Deckert
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - Laure Dumont
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - Amandine Bataille
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - Zoulika Zak
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
| | - Xian-Cheng Jiang
- ‡Downstate Medical Center, State University of New York, Brooklyn, NY 11203, U.S.A
| | - Louis M. Havekes
- †Netherlands Organization for Applied Scientific Research (TNO), Prevention and Health, Gaubius Laboratory, 2301 CE Leiden, The Netherlands
- §Departments of Cardiology and General Internal Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Laurent Lagrost
- *Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
- To whom correspondence should be addressed (email )
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Gautier T, Masson D, Jong MC, Duverneuil L, Le Guern N, Deckert V, Pais de Barros JP, Dumont L, Bataille A, Zak Z, Jiang XC, Tall AR, Havekes LM, Lagrost L. Apolipoprotein CI deficiency markedly augments plasma lipoprotein changes mediated by human cholesteryl ester transfer protein (CETP) in CETP transgenic/ApoCI-knocked out mice. J Biol Chem 2002; 277:31354-63. [PMID: 12070157 DOI: 10.1074/jbc.m203151200] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transgenic mice expressing human cholesteryl ester transfer protein (HuCETPTg mice) were crossed with apolipoprotein CI-knocked out (apoCI-KO) mice. Although total cholesterol levels tended to be reduced as the result of CETP expression in HuCETPTg heterozygotes compared with C57BL6 control mice (-13%, not significant), a more pronounced decrease (-28%, p < 0.05) was observed when human CETP was expressed in an apoCI-deficient background (HuCETPTg/apoCI-KO mice). Gel permeation chromatography analysis revealed a significant, 6.1-fold rise (p < 0.05) in the cholesteryl ester content of very low density lipoproteins in HuCETPTg/apoCI-KO mice compared with control mice, whereas the 2.7-fold increase in HuCETPTg mice did not reach the significance level in these experiments. Approximately 50% decreases in the cholesteryl ester content and cholesteryl ester to triglyceride ratio of high density lipoproteins (HDL) were observed in HuCETPTg/apoCI-KO mice compared with controls (p < 0.05 in both cases), with intermediate -20% changes in HuCETPTg mice. The cholesteryl ester depletion of HDL was accompanied with a significant reduction in their mean apparent diameter (8.68 +/- 0.04 nm in HuCETPTg/apoCI-KO mice versus 8.83 +/- 0.02 nm in control mice; p < 0.05), again with intermediate values in HuCETPTg mice (8.77 +/- 0.04 nm). In vitro purified apoCI was able to inhibit cholesteryl ester exchange when added to either total plasma or reconstituted HDL-free mixtures, and coincidently, the specific activity of CETP was significantly increased in the apoCI-deficient state (173 +/- 75 pmol/microg/h in HuCETPTg/apoCI-KO mice versus 72 +/- 19 pmol/microg/h in HuCETPTg, p < 0.05). Finally, HDL from apoCI-KO mice were shown to interact more readily with purified CETP than control HDL that differ only by their apoCI content. Overall, the present observations provide direct support for a potent specific inhibition of CETP by plasma apoCI in vivo.
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Affiliation(s)
- Thomas Gautier
- Laboratoire de Biochimie des Lipoprotéines, INSERM U498, Faculté de Médecine, BP87900, 21079 Dijon Cedex, France
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Gautier T, Masson D, de Barros JP, Athias A, Gambert P, Aunis D, Metz-Boutigue MH, Lagrost L. Human apolipoprotein C-I accounts for the ability of plasma high density lipoproteins to inhibit the cholesteryl ester transfer protein activity. J Biol Chem 2000; 275:37504-9. [PMID: 10978346 DOI: 10.1074/jbc.m007210200] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aim of the present study was to identify the protein that accounts for the cholesteryl ester transfer protein (CETP)-inhibitory activity that is specifically associated with human plasma high density lipoproteins (HDL). To this end, human HDL apolipoproteins were fractionated by preparative polyacrylamide gradient gel electrophoresis, and 30 distinct protein fractions with molecular masses ranging from 80 down to 2 kDa were tested for their ability to inhibit CETP activity. One single apolipoprotein fraction was able to completely inhibit CETP activity. The N-terminal sequence of the 6-kDa protein inhibitor matched the N-terminal sequence of human apoC-I, the inhibition was completely blocked by specific anti-apolipoprotein C-I antibodies, and mass spectrometry analysis confirmed the identity of the isolated inhibitor with full-length human apoC-I. Pure apoC-I was able to abolish CETP activity in a concentration-dependent manner and with a high efficiency (IC(50) = 100 nmol/liter). The inhibitory potency of total delipidated HDL apolipoproteins completely disappeared after a treatment with anti-apolipoprotein C-I antibodies, and the apoC-I deprivation of native plasma HDL by immunoaffinity chromatography produced a mean 43% rise in cholesteryl ester transfer rates. The main localization of apoC-I in HDL and not in low density lipoprotein in normolipidemic plasma provides further support for the specific property of HDL in inhibiting CETP activity.
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Affiliation(s)
- T Gautier
- Laboratoire de Biochimie des Lipoprotéines-INSERM U498, Hôpital du Bocage, BP1542, 21034 Dijon Cedex, France
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Hope HR, Heuvelman D, Duffin K, Smith C, Zablocki J, Schilling R, Hegde S, Lee L, Witherbee B, Baganoff M, Bruce C, Tall AR, Krul E, Glenn K, Connolly DT. Inhibition of cholesteryl ester transfer protein by substituted dithiobisnicotinic acid dimethyl ester: involvement of a critical cysteine. J Lipid Res 2000. [DOI: 10.1016/s0022-2275(20)31993-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Chapter 22. Cholesteryl ester transfer protein as a potential therapeutic target to improve the HDL to LDL cholesterol ratio. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 2000. [DOI: 10.1016/s0065-7743(00)35023-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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Abstract
The interconnections between cholesteryl ester transfer protein (CETP) expression and lipid metabolism, and the possible roles of CETP in atherogenesis are examined. The importance of lipid transfer inhibitor protein in modulating CETP activity is detailed, and the consequences of this inhibitory activity on CETP-mediated events are proposed.
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Affiliation(s)
- R E Morton
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Foundation, Ohio 44195, USA.
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Wang X, Driscoll DM, Morton RE. Molecular cloning and expression of lipid transfer inhibitor protein reveals its identity with apolipoprotein F. J Biol Chem 1999; 274:1814-20. [PMID: 9880564 DOI: 10.1074/jbc.274.3.1814] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Published studies demonstrate that lipid transfer inhibitor protein (LTIP) is an important regulator of cholesteryl ester transfer protein (CETP) activity. Although LTIP inhibits CETP activity among different lipoprotein classes, it preferentially suppresses transfer events involving low density lipoprotein (LDL), whereas transfers involving high density lipoprotein as donor are less affected. In this study, we report the purification of LTIP and the expression of its cDNA in cultured cells. Purification of LTIP, in contrast to other published protocols, took advantage of the tight association of this protein with LDL. Ultracentrifugally isolated LDL was further purified on anti-apoE and apoA-I affinity columns. Affinity purified LDL was delipidated by tetramethylurea, and the tetramethylurea-soluble proteins were separated by SDS-polyacrylamide gel electrophoresis. The protein migrating at a molecular mass of approximately 33 kDa was excised from the gel and its N-terminal amino acid sequence determined. The 14-amino acid sequence obtained showed complete homology with the sequence deduced for apolipoprotein F (apoF) cDNA isolated from Hep G2 cells. On Western blots, peptide-specific antibodies raised against synthetic fragments of apoF reacted with the same 33-kDa protein in LTIP-containing fractions purified from LDL and from lipoprotein-deficient plasma. In contrast to that previously reported, apoF was shown to be associated almost exclusively with LDL, identical to the distribution of LTIP activity. The cDNA for apoF was cloned from a human liver cDNA library, ligated into a mammalian expression vector, and transiently transfected into COS-7 cells. Conditioned media containing secreted apoF demonstrated CETP inhibitor activity, whereas cells transfected with vector alone did not. This CETP inhibitor activity was efficiently removed from the media by nickel-Sepharose, consistent with the 6-His tag incorporated into recombinant apoF. By Western blot, the 6-His-tagged protein had a molecular weight slightly larger than native apoF. The CETP inhibitor activity of recombinant apoF possessed the same LDL specificity, oleate sensitivity, and dependence on lipoprotein concentration as previously noted for LTIP. We conclude that LTIP and apoF are identical.
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Affiliation(s)
- X Wang
- Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA
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