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Ma CIJ, Beckstead JA, Thompson A, Hafiane A, Wang RHL, Ryan RO, Kiss RS. Tweaking the cholesterol efflux capacity of reconstituted HDL. Biochem Cell Biol 2012; 90:636-45. [PMID: 22607224 DOI: 10.1139/o2012-015] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanisms to increase plasma high-density lipoprotein (HDL) or to promote egress of cholesterol from cholesterol-loaded cells (e.g., foam cells from atherosclerotic lesions) remain an important target to regress heart disease. Reconstituted HDL (rHDL) serves as a valuable vehicle to promote cellular cholesterol efflux in vitro and in vivo. rHDL were prepared with wild type apolipoprotein (apo) A-I and the rare variant, apoA-I Milano (M), and each apolipoprotein was reconstituted with phosphatidylcholine (PC) or sphingomyelin (SM). The four distinct rHDL generated were incubated with CHO cells, J774 macrophages, and BHK cells in cellular cholesterol efflux assays. In each cell type, apoA-I(M) SM-rHDL promoted the greatest cholesterol efflux. In BHK cells, the cholesterol efflux capacities of all four distinct rHDL were greatly enhanced by increased expression of ABCG1. Efflux to PC-containing rHDL was stimulated by transfection of a nonfunctional ABCA1 mutant (W590S), suggesting that binding to ABCA1 represents a competing interaction. This interpretation was confirmed by binding experiments. The data show that cholesterol efflux activity is dependent upon the apoA-I protein employed, as well as the phospholipid constituent of the rHDL. Future studies designed to optimize the efflux capacity of therapeutic rHDL may improve the value of this emerging intervention strategy.
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Affiliation(s)
- Cheng-I J Ma
- Cardiovascular Research Laboratories, Department of Medicine, Royal Victoria Hospital, 687 Pine Avenue West, Montreal, QC H3A 1A1, Canada
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Ohnsorg PM, Mary JL, Rohrer L, Pech M, Fingerle J, von Eckardstein A. Trimerized apolipoprotein A-I (TripA) forms lipoproteins, activates lecithin:cholesterol acyltransferase, elicits lipid efflux, and is transported through aortic endothelial cells. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:1115-23. [DOI: 10.1016/j.bbalip.2011.09.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 08/11/2011] [Accepted: 09/02/2011] [Indexed: 02/03/2023]
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Sorci-Thomas MG, Zabalawi M, Bharadwaj MS, Wilhelm AJ, Owen JS, Asztalos BF, Bhat S, Thomas MJ. Dysfunctional HDL containing L159R ApoA-I leads to exacerbation of atherosclerosis in hyperlipidemic mice. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:502-12. [PMID: 21944998 DOI: 10.1016/j.bbalip.2011.08.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2011] [Revised: 08/20/2011] [Accepted: 08/31/2011] [Indexed: 11/16/2022]
Abstract
The mutation L159R apoA-I or apoA-I(L159R) (FIN) is a single amino acid substitution within the sixth helical repeat of apoA-I. It is associated with a dominant negative phenotype, displaying hypoalphaproteinemia and an increased risk for atherosclerosis in humans. Mice lacking both mouse apoA-I and LDL receptor (LDL(-/-), apoA-I(-/-)) (double knockout or DKO) were crossed>9 generations with mice transgenic for human FIN to obtain L159R apoA-I, LDLr(-/-), ApoA-I(-/-) (FIN-DKO) mice. A similar cross was also performed with human wild-type (WT) apoA-I (WT-DKO). In addition, FIN-DKO and WT-DKO were crossed to obtain WT/FIN-DKO mice. To determine the effects of the apoA-I mutations on atherosclerosis, groups of each genotype were fed either chow or an atherogenic diet for 12weeks. Interestingly, the production of dysfunctional HDL-like particles occurred in DKO and FIN-DKO mice. These particles were distinct with respect to size, and their enrichment in apoE and cholesterol esters. Two-dimensional gel electrophoresis indicated that particles found in the plasma of FIN-DKO mice migrated as large α(3)-HDL. Atherosclerosis analysis showed that FIN-DKO mice developed the greatest extent of aortic cholesterol accumulation compared to all other genotypes, including DKO mice which lack any apoA-I. Taken together these data suggest that the presence of large apoE enriched HDL particles containing apoA-I L159R lack the normal cholesterol efflux promoting properties of HDL, rendering them dysfunctional and pro-atherogenic. In conclusion, large HDL-like particles containing apoE and apoA-I(L159R) contribute rather than protect against atherosclerosis, possibly through defective efflux properties and their potential for aggregation at their site of interaction in the aorta. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Mary G Sorci-Thomas
- Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
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Bhat S, Sorci-Thomas MG, Calabresi L, Samuel MP, Thomas MJ. Conformation of dimeric apolipoprotein A-I milano on recombinant lipoprotein particles. Biochemistry 2010; 49:5213-24. [PMID: 20524691 DOI: 10.1021/bi1003734] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Apolipoprotein A-I Milano (apoA-I(Milano)) is a naturally occurring human mutation of wild-type apolipoprotein A-I (apoA-I(WT)) having cystine substituted for arginine(173). Two molecules of apo-I(WT) form disks with phospholipid having a defined relationship between the apoA-I(WT) molecules. ApoA-I(Milano) forms cystine homodimers that would not allow the protein to adopt the conformation reported for apoA-I(WT). The conformational constraints for dimeric apoA-I(Milano) recombinant high-density lipoprotein (rHDL) disks made with phospholipid were deduced from a combination of chemical cross-linking and mass spectrometry. Lysine-selective homobifunctional cross-linkers were reacted with homogeneous rHDL having diameters of 78 and 125 A. After reduction, cross-linked apoA-I(Milano) was separated from monomeric apoprotein by gel electrophoresis and then subjected to in-gel trypsin digest. Cross-linked peptides were confirmed by MS/MS sequencing. The cross-links provided distance constraints that were used to refine models of lipid-bound dimeric apoA-I(Milano). These studies suggest that a single dimeric apoA-I(Milano) on 78 A diameter rHDL girdles the edge of a phospholipid disk assuming a "belt" conformation similar to the "belt" region of apoA-I(WT) on rHDL. However, the C-terminal end of dimeric apoA-I(Milano) wraps around the periphery of the particle to shield the fatty acid chains from water rather than folding back onto the "belt" as does apoA-I(WT). The two apoA-I(Milano) dimers on a 125 A diameter rHDL do not encircle the periphery of a phospholipid disk but appear to reside on the surface of a laminar micelle.
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Affiliation(s)
- Shaila Bhat
- Department of Pathology, Center for Lipid Science, Wake Forest University Health Sciences, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA
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Haas MJ, Mooradian AD. Therapeutic Interventions to Enhance Apolipoprotein A-I-Mediated Cardioprotection. Drugs 2010; 70:805-21. [DOI: 10.2165/11535410-000000000-00000] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Murphy AJ, Chin-Dusting J, Sviridov D. Reconstituted HDL: a therapy for atherosclerosis and beyond. ACTA ACUST UNITED AC 2009. [DOI: 10.2217/clp.09.68] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Favari E, Gomaraschi M, Zanotti I, Bernini F, Lee-Rueckert M, Kovanen PT, Sirtori CR, Franceschini G, Calabresi L. A Unique Protease-sensitive High Density Lipoprotein Particle Containing the Apolipoprotein A-IMilano Dimer Effectively Promotes ATP-binding Cassette A1-mediated Cell Cholesterol Efflux. J Biol Chem 2007; 282:5125-32. [PMID: 17164237 DOI: 10.1074/jbc.m609336200] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Carriers of the apolipoprotein A-I(Milano) (A-I(M)) variant present with severe reductions of plasma HDL levels, not associated with premature coronary heart disease (CHD). Sera from 14 A-I(M) carriers and matched controls were compared for their ability to promote ABCA1-driven cholesterol efflux from J774 macrophages and human fibroblasts. When both cell types are stimulated to express ABCA1, the efflux of cholesterol through this pathway is greater with A-I(M) than control sera (3.4 +/- 1.0% versus 2.3 +/- 1.0% in macrophages; 5.2 +/- 2.4% versus 1.9 +/- 0.1% in fibroblasts). A-I(M) and control sera are instead equally effective in removing cholesterol from unstimulated cells and from fibroblasts not expressing ABCA1. The A-I(M) sera contain normal amounts of apoA-I-containing prebeta-HDL and varying concentrations of a unique small HDL particle containing a single molecule of the A-I(M) dimer; chymase treatment of serum degrades both particles and abolishes ABCA1-mediated cholesterol efflux. The serum content of chymase-sensitive HDL correlates strongly and significantly with ABCA1-mediated cholesterol efflux (r = 0.542, p = 0.004). The enhanced capacity of A-I(M) serum for ABCA1 cholesterol efflux is thus explained by the combined occurrence in serum of normal amounts of apoA-I-containing prebeta-HDL, together with a unique protease-sensitive, small HDL particle containing the A-I(M) dimer, both effective in removing cell cholesterol via ABCA1.
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Affiliation(s)
- Elda Favari
- Department of Pharmacological and Biological Sciences, and Applied Chemistries, University of Parma, Viale delle Scienze 27A, 43100 Parma, Italy
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Thomas MJ, Bhat S, Sorci-Thomas MG. The use of chemical cross-linking and mass spectrometry to elucidate the tertiary conformation of lipid-bound apolipoprotein A-I. Curr Opin Lipidol 2006; 17:214-20. [PMID: 16680024 DOI: 10.1097/01.mol.0000226111.05060.f4] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
PURPOSE OF REVIEW The purpose of this review is to highlight recent advances in mass spectrometry and its use for identifying the lipid-bound conformation of apolipoprotein A-I. Given the current interest in understanding the structure of HDL apolipoprotein A-I, this approach seems ideal in assessing its dual role as mediator of lipid efflux and modulator of cellular inflammation. RECENT FINDINGS A large number of different technical approaches have been employed over the past 25 years in attempts to solve the lipid-bound conformation of apolipoprotein A-I. Since the X-ray crystal structure of lipid-free Delta43 apolipoprotein A-I was reported in 1997, a 'double belt' model describing lipid-bound apolipoprotein A-I conformation for recombinant HDL has prevailed. Recent studies have focused on determining the exact helix-helix registry and salt-bridging partners found on a two apolipoprotein A-I molecule disc as well as on spherical HDL particles. Investigations are all aimed at defining the conformation of lipid-bound apolipoprotein A-I which may provide an explanation for how specific domains of apolipoprotein A-I interact with important HDL-modifying proteins that ultimately determine the apolipoprotein's fate in circulation. SUMMARY Recent advances in mass spectrometric sequencing of cross-linked peptides provide an excellent tool to help define protein tertiary structure. This approach has provided refined structural information on apolipoprotein A-I folding which had eluded all previous approaches.
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Affiliation(s)
- Michael J Thomas
- Department of Biochemistry, Wake Forest University Health Sciences, Winston-Salem, North Carolina, USA.
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Zhu X, Wu G, Zeng W, Xue H, Chen B. Cysteine mutants of human apolipoprotein A-I: a study of secondary structural and functional properties. J Lipid Res 2005; 46:1303-11. [PMID: 15805548 DOI: 10.1194/jlr.m400401-jlr200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Apolipoprotein A-I(Milano) (A-I(M)) (R173C), a natural mutant of human apolipoprotein A-I (apoA-I), and five other cysteine variants of apoA-I at residues 52 (S52C), 74 (N74C), 107 (K107C), 129 (G129C), and 195 (K195C) were generated. Cysteine residues were incorporated in each of the various helices at the same helical wheel position as for the substitution in A-I(M). The secondary structural properties of the monomeric mutants, their abilities to bind lipid and to promote cholesterol efflux from THP-1 macrophages, and the possibility of antiperoxidation were investigated. Results showed that the alpha helical contents of all of the cysteine mutants were similar to that of wild-type apoA-I (wtapoA-I). The cysteine variant of A-I(M) at residue 173 [A-I(M)(R173C)] exhibited weakened structural stability, whereas A-I(G129C) a more stable structure than wtapoA-I. A-I(G129C) and A-I(K195C) exhibited significantly impaired capabilities to bind lipid compared with wtapoA-I. A-I(K107C) possessed a higher capacity to promote cholesterol efflux from macrophages than wtapoA-I, and A-I(M)(R173C) and A-I(K195C) exhibited an impaired efflux capability. Neither A-I(M)(R173C) nor any other cysteine mutant could resist oxidation against lipoxygenase. In summary, in spite of the similar mutant position on the helix, these variants exhibited different structural features or biological activities, suggesting the potential influence of the local environment of mutations on the whole polypeptide chain.
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Affiliation(s)
- Xuewei Zhu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China 100005
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Dayal B, Ertel NH. ProteinChip technology: a new and facile method for the identification and measurement of high-density lipoproteins apoA-I and apoA-II and their glycosylated products in patients with diabetes and cardiovascular disease. J Proteome Res 2002; 1:375-80. [PMID: 12645894 DOI: 10.1021/pr010008n] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
This paper describes a ProteinChip technology for the identification and quantification of apolipoprotein profiles in crude biological samples. Expression levels of apoA-I and apoA-II and their glycosylated products were accomplished using single 1 microL plasma samples. In the present studies, strong anionic and weak cationic exchanger ProteinChips (SAX2 and WCX2 chip surfaces) were tested, and the WCX2 chip was found to be selective for specific apolipoproteins. Using the WCX2 chip and analysis via surface-enhanced laser desorption ionization mass spectrometry (SELDI-MS), apoA-I and apoA-II were separated as sharp peaks at 28 and 17 kD and did not overlap with other serum protein peaks. Since these assays can be completed on a large number of clinical samples in approximately 1 h, further development of this technique will facilitate both epidemiological studies and therapeutic trials in assessing the role of the apolipoproteins and their glycosylated products in atherosclerosis.
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Affiliation(s)
- Bishambar Dayal
- VA NJ Health Care System, East Orange, New Jersey 07018, USA.
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Affiliation(s)
- P P Toth
- Sterling Rock Falls Clinic, Southern Illinois University School of Medicine, USA
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Bielicki JK, Forte TM, McCall MR, Stoltzfus LJ, Chiesa G, Sirtori CR, Franceschini G, Rubin EM. High density lipoprotein particle size restriction in apolipoprotein A-I(Milano) transgenic mice. J Lipid Res 1997. [DOI: 10.1016/s0022-2275(20)34945-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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