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Zhang Y, Luo S, Gao Y, Tong W, Sun S. High-Density Lipoprotein Subfractions Remodeling: A Critical Process for the Treatment of Atherosclerotic Cardiovascular Diseases. Angiology 2024; 75:441-453. [PMID: 36788038 DOI: 10.1177/00033197231157473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Numerous studies have shown that a low level of high-density lipoprotein cholesterol (HDL-C) is an independent biomarker of cardiovascular disease. High-density lipoprotein (HDL) is considered to be a protective factor for atherosclerosis (AS). Therefore, raising HDL-C has been widely recognized as a promising strategy to treat atherosclerotic cardiovascular diseases (ASCVD). However, several studies have found that increasing HDL-C levels does not necessarily reduce the risk of ASCVD. HDL particles are highly heterogeneous in structure, composition, and biological function. Moreover, HDL particles from atherosclerotic patients exhibit impaired anti-atherogenic functions and these dysfunctional HDL particles might even promote ASCVD. This makes it uncertain that HDL-raising therapy will prevent and treat ASCVD. It is necessary to comprehensively analyze the structure and function of HDL subfractions. We review current advances related to HDL subfractions remodeling and highlight how current lipid-modifying drugs such as niacin, statins, fibrates, and cholesteryl ester transfer protein inhibitors regulate cholesterol concentration of HDL and specific HDL subfractions.
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Affiliation(s)
- Yaling Zhang
- Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, University of South China, Hengyang, China
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang, China
| | - Shiyu Luo
- Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, University of South China, Hengyang, China
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang, China
| | - Yi Gao
- Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, University of South China, Hengyang, China
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang, China
| | - Wenjuan Tong
- Department of Gynecology and Obstetrics, First Affiliated Hospital, University of South China, Hengyang, China
| | - Shaowei Sun
- Hunan Provincial Key Laboratory of Tumor Microenvironment Responsive Drug Research, University of South China, Hengyang, China
- School of Pharmaceutical Science, Hengyang Medical School, University of South China, Hengyang, China
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Gorshkova IN, Meyers NL, Herscovitz H, Mei X, Atkinson D. Human apoA-I[Lys107del] mutation affects lipid surface behavior of apoA-I and its ability to form large nascent HDL. J Lipid Res 2022; 64:100319. [PMID: 36525992 PMCID: PMC9926306 DOI: 10.1016/j.jlr.2022.100319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 11/18/2022] [Accepted: 12/05/2022] [Indexed: 12/15/2022] Open
Abstract
Population studies have found that a natural human apoA-I variant, apoA-I[K107del], is strongly associated with low HDL-C but normal plasma apoA-I levels. We aimed to reveal properties of this variant that contribute to its unusual phenotype associated with atherosclerosis. Our oil-drop tensiometry studies revealed that compared to WT, recombinant apoA-I[K107del] adsorbed to surfaces of POPC-coated triolein drops at faster rates, remodeled the surfaces to a greater extent, and was ejected from the surfaces at higher surface pressures on compression of the lipid drops. These properties may drive increased binding of apoA-I[K107del] to and its better retention on large triglyceride-rich lipoproteins, thereby increasing the variant's content on these lipoproteins. While K107del did not affect apoA-I capacity to promote ABCA1-mediated cholesterol efflux from J774 cells, it impaired the biogenesis of large nascent HDL particles resulting in the formation of predominantly smaller nascent HDL. Size-exclusion chromatography of spontaneously reconstituted 1,2-dimyristoylphosphatidylcholine-apoA-I complexes showed that apoA-I[K107del] had a hampered ability to form larger complexes but formed efficiently smaller-sized complexes. CD analysis revealed a reduced ability of apoA-I[K107del] to increase α-helical structure on binding to 1,2-dimyristoylphosphatidylcholine or in the presence of trifluoroethanol. This property may hinder the formation of large apoA-I[K107del]-containing discoidal and spherical HDL but not smaller HDL. Both factors, the increased content of apoA-I[K107del] on triglyceride-rich lipoproteins and the impaired ability of the variant to stabilize large HDL particles resulting in reduced lipid:protein ratios in HDL, may contribute to normal plasma apoA-I levels along with low HDL-C and increased risk for CVD.
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Dalakoura-Karagkouni K, Tiniakou I, Zannis VI, Kardassis D. Using adenovirus-mediated gene transfer to study the effect of myeloperoxidase on plasma lipid levels, HDL structure and functionality in mice expressing human apoA-I forms. Biochem Biophys Res Commun 2022; 622:108-114. [PMID: 35843089 DOI: 10.1016/j.bbrc.2022.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/01/2022] [Indexed: 11/02/2022]
Abstract
Apolipoprotein A-I (apoA-I), the main protein component of High-Density Lipoprotein (HDL), is modified in plasma and the arterial wall by various enzymes. Myeloperoxidase (MPO), a leukocyte-derived peroxidase, is highly expressed during inflammation and associates with HDL reducing its functionality and contributing to atherosclerosis. In the present study we sought to explore further the effect of MPO on HDL structure and functionality in vivo using adenovirus-mediated gene transfer of human MPO combined with human apoA-I forms containing substitutions at MPO-sensitive sites or wild type apoA-I. We found that overexpression of MPO in mice significantly increased plasma apoA-I and HDL levels without affecting the expression of genes involved in HDL biogenesis or catabolism in the liver. Overexpression of MPO in the liver reduced the expression of pro-inflammatory genes and increased or did not affect the expression of anti-inflammatory genes suggesting that MPO had no toxic effects in this organ. In the plasma of mice overexpressing MPO, no significant alterations in HDL size or electrophoretic mobility was observed with the exception of mice expressing apoA-I (M148A) which showed enriched pre-β relative to α HDL particles, suggesting that the apoA-I (M148A) mutation may interfere with HDL remodelling. Overexpression of MPO was associated with reduced anti-oxidant capacity of HDL particles in all mice. Interestingly, HDL particles bearing apoA-I (Y192A) showed enhanced ABCA1-dependent cholesterol efflux from macrophages which was not affected by MPO and these mice had reduced levels of LDL-c. These findings provide new insights on the role of specific amino acid residues of apoA-I in HDL structure and function following modification by MPO. This knowledge may facilitate the development of novel therapies based on improved HDL forms for patients with chronic diseases that are characterized by dysfunctional HDL.
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Affiliation(s)
- Katerina Dalakoura-Karagkouni
- University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology of Hellas, Heraklion, 71003, Crete, Greece
| | - Ioanna Tiniakou
- University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology of Hellas, Heraklion, 71003, Crete, Greece
| | - Vassilis I Zannis
- Section of Molecular Genetics, Whitaker Cardiovascular Institute, Boston University Medical Center, Boston, MA, 02118, USA
| | - Dimitris Kardassis
- University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology of Hellas, Heraklion, 71003, Crete, Greece.
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4
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Lee CK, Liao CW, Meng SW, Wu WK, Chiang JY, Wu MS. Lipids and Lipoproteins in Health and Disease: Focus on Targeting Atherosclerosis. Biomedicines 2021; 9:biomedicines9080985. [PMID: 34440189 PMCID: PMC8393881 DOI: 10.3390/biomedicines9080985] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 08/01/2021] [Accepted: 08/04/2021] [Indexed: 12/15/2022] Open
Abstract
Despite advances in pharmacotherapy, intervention devices and techniques, residual cardiovascular risks still cause a large burden on public health. Whilst most guidelines encourage achieving target levels of specific lipids and lipoproteins to reduce these risks, increasing evidence has shown that molecular modification of these lipoproteins also has a critical impact on their atherogenicity. Modification of low-density lipoprotein (LDL) by oxidation, glycation, peroxidation, apolipoprotein C-III adhesion, and the small dense subtype largely augment its atherogenicity. Post-translational modification by oxidation, carbamylation, glycation, and imbalance of molecular components can reduce the capacity of high-density lipoprotein (HDL) for reverse cholesterol transport. Elevated levels of triglycerides (TGs), apolipoprotein C-III and lipoprotein(a), and a decreased level of apolipoprotein A-I are closely associated with atherosclerotic cardiovascular disease. Pharmacotherapies aimed at reducing TGs, lipoprotein(a), and apolipoprotein C-III, and enhancing apolipoprotein A-1 are undergoing trials, and promising preliminary results have been reported. In this review, we aim to update the evidence on modifications of major lipid and lipoprotein components, including LDL, HDL, TG, apolipoprotein, and lipoprotein(a). We also discuss examples of translating findings from basic research to potential therapeutic targets for drug development.
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Affiliation(s)
- Chih-Kuo Lee
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu 300, Taiwan
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
| | - Che-Wei Liao
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Department of Internal Medicine, National Taiwan University Cancer Center, Taipei 106, Taiwan
| | - Shih-Wei Meng
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Division of Cardiology, Department of Internal Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu 300, Taiwan
| | - Wei-Kai Wu
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei 100, Taiwan
| | - Jiun-Yang Chiang
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei 100, Taiwan
- Division of Cardiology, Department of Internal Medicine and Cardiovascular Center, National Taiwan University Hospital, Taipei 100, Taiwan
- Correspondence: (J.-Y.C.); (M.-S.W.)
| | - Ming-Shiang Wu
- College of Medicine, National Taiwan University, Taipei 100, Taiwan; (C.-K.L.); (C.-W.L.); (S.-W.M.); (W.-K.W.)
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei 100, Taiwan
- Correspondence: (J.-Y.C.); (M.-S.W.)
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5
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Yelamanchili D, Liu J, Gotto AM, Hurley AE, Lagor WR, Gillard BK, Davidson WS, Pownall HJ, Rosales C. Highly conserved amino acid residues in apolipoprotein A1 discordantly induce high density lipoprotein assembly in vitro and in vivo. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158794. [PMID: 32810603 DOI: 10.1016/j.bbalip.2020.158794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Apolipoprotein A1 (APOA1) is essential to reverse cholesterol transport, a physiologically important process that protects against atherosclerotic cardiovascular disease. APOA1 is a 28 kDa protein comprising multiple lipid-binding amphiphatic helices initialized by proline residues, which are conserved across multiple species. We tested the hypothesis that the evolutionarily conserved residues are essential to high density lipoprotein (HDL) function. APPROACH We used biophysical and physiological assays of the function of APOA1P➔A variants, i.e., rHDL formation via dimyristoylphosphatidylcholine (DMPC) microsolubilization, activation of lecithin: cholesterol acyltransferase, cholesterol efflux from human monocyte-derived macrophages (THP-1) to each variant, and comparison of the size and composition of HDL from APOA1-/- mice receiving adeno-associated virus delivery of each human variant. RESULTS Differences in microsolubilization were profound and showed that conserved prolines, especially those in the C-terminus of APOA1, are essential to efficient rHDL formation. In contrast, P➔A substitutions produced small changes (-25 to +25%) in rates of cholesterol efflux and no differences in the rates of LCAT activation. The HDL particles formed following ectopic expression of each variant in APOA1-/- mice were smaller and more heterogeneous than those from control animals. CONCLUSION Studies of DMPC microsolubilization show that proline residues are essential to the optimal interaction of APOA1 with membranes, the initial step in cholesterol efflux and HDL production. In contrast, P➔A substitutions modestly reduce the cholesterol efflux capacity of APOA1, have no effect on LCAT activation, but according to the profound reduction in the size of HDL formed in vivo, P➔A substitutions alter HDL biogenesis, thereby implicating other cellular and in vivo processes as determinants of HDL metabolism and function.
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Affiliation(s)
- Dedipya Yelamanchili
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA.
| | - Jing Liu
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Department of Cardiovascular Surgery, Xiangya Hospital, Central South University, Changsha 410008, China.
| | - Antonio M Gotto
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Weill Cornell Medicine, 1305 York Avenue, New York, NY 10065, USA.
| | - Ayrea E Hurley
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
| | - Willam R Lagor
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
| | - Baiba K Gillard
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Weill Cornell Medicine, 1305 York Avenue, New York, NY 10065, USA.
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45237, USA.
| | - Henry J Pownall
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Weill Cornell Medicine, 1305 York Avenue, New York, NY 10065, USA.
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Weill Cornell Medicine, 1305 York Avenue, New York, NY 10065, USA.
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6
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Zannis VI, Su S, Fotakis P. Role of apolipoproteins, ABCA1 and LCAT in the biogenesis of normal and aberrant high density lipoproteins. J Biomed Res 2017; 31:471. [PMID: 29109329 PMCID: PMC6307667 DOI: 10.7555/jbr.31.20160082] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 08/30/2016] [Indexed: 12/28/2022] Open
Abstract
In this review, we focus on the pathway of biogenesis of HDL, the essential role of apoA-I, ATP binding cassette transporter A1 (ABCA1), and lecithin: cholesterol acyltransferase (LCAT) in the formation of plasma HDL; the generation of aberrant forms of HDL containing mutant apoA-I forms and the role of apoA-IV and apoE in the formation of distinct HDL subpopulations. The biogenesis of HDL requires functional interactions of the ABCA1 with apoA-I (and to a lesser extent with apoE and apoA-IV) and subsequent interactions of the nascent HDL species thus formed with LCAT. Mutations in apoA-I, ABCA1 and LCAT either prevent or impair the formation of HDL and may also affect the functionality of the HDL species formed. Emphasis is placed on three categories of apoA-I mutations. The first category describes a unique bio-engineered apoA-I mutation that disrupts interactions between apoA-I and ABCA1 and generates aberrant preβ HDL subpopulations that cannot be converted efficiently to α subpopulations by LCAT. The second category describes natural and bio-engineered apoA-I mutations that generate preβ and small size α4 HDL subpopulations, and are associated with low plasma HDL levels. These phenotypes can be corrected by excess LCAT. The third category describes bio-engineered apoA-I mutations that induce hypertriglyceridemia that can be corrected by excess lipoprotein lipase and also have defective maturation of HDL. The HDL phenotypes described here may serve in the future for diagnosis, prognoses and potential treatment of abnormalities that affect the biogenesis and functionality of HDL.
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Affiliation(s)
- Vassilis I. Zannis
- . Molecular Genetics, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA
- . Department University of Crete, School of Medicine, Heraklion, Crete, Greece
| | - Shi Su
- . Molecular Genetics, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA
| | - Panagiotis Fotakis
- . Molecular Genetics, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118, USA
- . Department University of Crete, School of Medicine, Heraklion, Crete, Greece
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7
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Gorshkova IN, Atkinson D. Increased Binding of Apolipoproteins A-I and E4 to Triglyceride-Rich Lipoproteins is linked to Induction of Hypertriglyceridemia. JSM ATHEROSCLEROSIS 2017; 2:1026. [PMID: 28597004 PMCID: PMC5460632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Hypertriglyceridemia (HTG) is an independent factor of atherosclerotic cardiovascular disease and a hallmark of many metabolic disorders. However, the molecular etiology of HTG is still largely unknown. In mice, severe HTG may be induced by expression of specific mutants of apolipoprotein (apo) A-I or wild type (WT) apoE4. Expression of a certain apoE4 mutant results in mild HTG, while expression of another apoE4 mutant or WT apoA-I results in normal plasma triglyceride (TG) levels. Biophysical studies of the apoA-I and apoE4 forms associated with HTG help better understand the molecular mechanisms of induction of HTG by these proteins. The studies show that the apoA-I and apoE4 forms that induce HTG have a destabilized and more loosely folded conformation in solution than their counterparts not associated with HTG. Disruption of the protein salt bridge networks by the mutations is likely responsible for the observed structural changes. Each apoA-I and apoE4 form that induced HTG show enhanced binding to model TG-rich particles. HTG appeared to positively correlate with the apolipoprotein ability to bind to TG-rich particles. This implies that in vivo, the conformational changes in the apolipoproteins that induce HTG facilitate their binding to plasma TG-rich lipoproteins. We discuss metabolic pathways leading to the development of HTG that may result from enhanced binding of the apolipoproteins to TG-rich lipoproteins in circulation. While various factors may be involved in the development of HTG in humans, it is possible that structural alterations that increase affinity of apolipoproteins to TG-rich lipoproteins may contribute to some cases of this disorder.
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Affiliation(s)
- Irina N. Gorshkova
- Corresponding author: Irina N. Gorshkova, Department
of Physiology and Biophysics, Boston University School of Medicine, 700 Albany Street,
Boston, Massachusetts 02118, USA, Tel: 1-617-638-4207;
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8
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Oda MN. Lipid-free apoA-I structure - Origins of model diversity. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1862:221-233. [PMID: 27890580 DOI: 10.1016/j.bbalip.2016.11.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 10/20/2016] [Accepted: 11/20/2016] [Indexed: 01/22/2023]
Abstract
Apolipoprotein A-I (apoA-I) is a prominent member of the exchangeable apolipoprotein class of proteins, capable of transitioning between lipid-bound and lipid-free states. It is the primary structural and functional protein of high density lipoprotein (HDL). Lipid-free apoA-I is critical to de novo HDL formation as it is the preferred substrate of the lipid transporter, ATP Binding Cassette Transporter A1 (ABCA1) Remaley et al. (2001) [1]. Lipid-free apoA-I is an important element in reverse cholesterol transport and comprehension of its structure is a core issue in our understanding of cholesterol metabolism. However, lipid-free apoA-I is highly conformationally dynamic making it a challenging subject for structural analysis. Over the past 20years there have been significant advances in overcoming the dynamic nature of lipid-free apoA-I, which have resulted in a multitude of proposed conformational models.
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Affiliation(s)
- Michael N Oda
- Children's Hospital Oakland Research Institute, Oakland, CA 94609, United States.
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9
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Zannis VI, Fotakis P, Koukos G, Kardassis D, Ehnholm C, Jauhiainen M, Chroni A. HDL biogenesis, remodeling, and catabolism. Handb Exp Pharmacol 2015; 224:53-111. [PMID: 25522986 DOI: 10.1007/978-3-319-09665-0_2] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
In this chapter, we review how HDL is generated, remodeled, and catabolized in plasma. We describe key features of the proteins that participate in these processes, emphasizing how mutations in apolipoprotein A-I (apoA-I) and the other proteins affect HDL metabolism. The biogenesis of HDL initially requires functional interaction of apoA-I with the ATP-binding cassette transporter A1 (ABCA1) and subsequently interactions of the lipidated apoA-I forms with lecithin/cholesterol acyltransferase (LCAT). Mutations in these proteins either prevent or impair the formation and possibly the functionality of HDL. Remodeling and catabolism of HDL is the result of interactions of HDL with cell receptors and other membrane and plasma proteins including hepatic lipase (HL), endothelial lipase (EL), phospholipid transfer protein (PLTP), cholesteryl ester transfer protein (CETP), apolipoprotein M (apoM), scavenger receptor class B type I (SR-BI), ATP-binding cassette transporter G1 (ABCG1), the F1 subunit of ATPase (Ecto F1-ATPase), and the cubulin/megalin receptor. Similarly to apoA-I, apolipoprotein E and apolipoprotein A-IV were shown to form discrete HDL particles containing these apolipoproteins which may have important but still unexplored functions. Furthermore, several plasma proteins were found associated with HDL and may modulate its biological functions. The effect of these proteins on the functionality of HDL is the topic of ongoing research.
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Affiliation(s)
- Vassilis I Zannis
- Molecular Genetics, Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, 02118, USA,
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10
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Gorshkova IN, Mei X, Atkinson D. Binding of human apoA-I[K107del] variant to TG-rich particles: implications for mechanisms underlying hypertriglyceridemia. J Lipid Res 2014; 55:1876-85. [PMID: 24919401 DOI: 10.1194/jlr.m047241] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We found earlier that apoA-I variants that induced hypertriglyceridemia (HTG) in mice had increased affinity to TG-rich lipoproteins and thereby impaired their catabolism. Here, we tested whether a naturally occurring human apoA-I mutation, Lys107del, associated with HTG also promotes apoA-I binding to TG-rich particles. We expressed apoA-I[Lys107del] variant in Escherichia coli, studied its binding to TG-rich emulsion particles, and performed a physicochemical characterization of the protein. Compared with WT apoA-I, apoA-I[Lys107del] showed enhanced binding to TG-rich particles, lower stability, and greater exposure of hydrophobic surfaces. The crystal structure of truncated, Δ(185-243), apoA-I suggests that deletion of Lys107 disrupts helix registration and disturbs a stabilizing salt bridge network in the N-terminal helical bundle. To elucidate the structural changes responsible for the altered function of apoA-I[Lys107del], we studied another mutant, apoA-I [Lys107Ala]. Our findings suggest that the registry shift and ensuing disruption of the inter-helical salt bridges in apoA-I[Lys107del] result in destabilization of the helical bundle structure and greater exposure of hydrophobic surfaces. We conclude that the structural changes in the apoA-I[Lys107del] variant facilitate its binding to TG-rich lipoproteins and thus, may reduce their lipolysis and contribute to the development of HTG in carriers of the mutation.
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Affiliation(s)
- Irina N Gorshkova
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118 Department of Medicine, Boston University School of Medicine, Boston, MA 02118
| | - Xiaohu Mei
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
| | - David Atkinson
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
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11
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Fotakis P, Kateifides AK, Gkolfinopoulou C, Georgiadou D, Beck M, Gründler K, Chroni A, Stratikos E, Kardassis D, Zannis VI. Role of the hydrophobic and charged residues in the 218-226 region of apoA-I in the biogenesis of HDL. J Lipid Res 2013; 54:3281-92. [PMID: 23990662 DOI: 10.1194/jlr.m038356] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We investigated the significance of hydrophobic and charged residues 218-226 on the structure and functions of apoA-I and their contribution to the biogenesis of HDL. Adenovirus-mediated gene transfer of apoA-I[L218A/L219A/V221A/L222A] in apoA-I⁻/⁻ mice decreased plasma cholesterol and apoA-I levels to 15% of wild-type (WT) control mice and generated pre-β- and α4-HDL particles. In apoA-I⁻/⁻ × apoE⁻/⁻ mice, the same mutant formed few discoidal and pre-β-HDL particles that could not be converted to mature α-HDL particles by excess LCAT. Expression of the apoA-I[E223A/K226A] mutant in apoA-I⁻/⁻ mice caused lesser but discrete alterations in the HDL phenotype. The apoA-I[218-222] and apoA-I[E223A/K226A] mutants had 20% and normal capacity, respectively, to promote ABCA1-mediated cholesterol efflux. Both mutants had ∼65% of normal capacity to activate LCAT in vitro. Biophysical analyses suggested that both mutants affected in a distinct manner the structural integrity and plasticity of apoA-I that is necessary for normal functions. We conclude that the alteration of the hydrophobic 218-222 residues of apoA-I disrupts apoA-I/ABCA1 interactions and promotes the generation of defective pre-β particles that fail to mature into α-HDL subpopulations, thus resulting in low plasma apoA-I and HDL. Alterations of the charged 223, 226 residues caused milder but discrete changes in HDL phenotype.
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Affiliation(s)
- Panagiotis Fotakis
- Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA 02118
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