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Chroni A, Kardassis D. HDL Dysfunction Caused by Mutations in apoA-I and Other Genes that are Critical for HDL Biogenesis and Remodeling. Curr Med Chem 2019. [DOI: 10.2174/0929867325666180313114950] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The “HDL hypothesis” which suggested that an elevation in HDL cholesterol
(HDL-C) levels by drugs or by life style changes should be paralleled by a decrease in the
risk for Cardiovascular Disease (CVD) has been challenged by recent epidemiological and
clinical studies using HDL-raising drugs. HDL components such as proteins, lipids or small
RNA molecules, but not cholesterol itself, possess various atheroprotective functions in different
cell types and accumulating evidence supports the new hypothesis that HDL functionality
is more important than HDL-C levels for CVD risk prediction. Thus, the detailed characterization
of changes in HDL composition and functions in various pathogenic conditions
is critically important in order to identify new biomarkers for diagnosis, prognosis and therapy
monitoring of CVD. Here we provide an overview of how HDL composition, size and
functionality are affected in patients with monogenic disorders of HDL metabolism due to
mutations in genes that participate in the biogenesis and the remodeling of HDL. We also review
the findings from various mouse models with genetic disturbances in the HDL biogenesis
pathway that have been generated for the validation of the data obtained in human patients
and how these models could be utilized for the evaluation of novel therapeutic strategies such
as the use of adenovirus-mediated gene transfer technology that aim to correct HDL abnormalities.
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Affiliation(s)
- Angeliki Chroni
- Institute of Biosciences and Applications, National Center for Scientific Research , Greece
| | - Dimitris Kardassis
- Department of Basic Medical Sciences, University of Crete Medical School and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology of Hellas, Heraklion 71003, Greece
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2
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Gogonea V. Structural Insights into High Density Lipoprotein: Old Models and New Facts. Front Pharmacol 2016; 6:318. [PMID: 26793109 PMCID: PMC4709926 DOI: 10.3389/fphar.2015.00318] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 12/22/2015] [Indexed: 11/13/2022] Open
Abstract
The physiological link between circulating high density lipoprotein (HDL) levels and cardiovascular disease is well-documented, albeit its intricacies are not well-understood. An improved appreciation of HDL function and overall role in vascular health and disease requires at its foundation a better understanding of the lipoprotein's molecular structure, its formation, and its process of maturation through interactions with various plasma enzymes and cell receptors that intervene along the pathway of reverse cholesterol transport. This review focuses on summarizing recent developments in the field of lipid free apoA-I and HDL structure, with emphasis on new insights revealed by newly published nascent and spherical HDL models constructed by combining low resolution structures obtained from small angle neutron scattering (SANS) with contrast variation and geometrical constraints derived from hydrogen-deuterium exchange (HDX), crosslinking mass spectrometry, electron microscopy, Förster resonance energy transfer, and electron spin resonance. Recently published low resolution structures of nascent and spherical HDL obtained from SANS with contrast variation and isotopic labeling of apolipoprotein A-I (apoA-I) will be critically reviewed and discussed in terms of how they accommodate existing biophysical structural data from alternative approaches. The new low resolution structures revealed and also provided some answers to long standing questions concerning lipid organization and particle maturation of lipoproteins. The review will discuss the merits of newly proposed SANS based all atom models for nascent and spherical HDL, and compare them with accepted models. Finally, naturally occurring and bioengineered mutations in apoA-I, and their impact on HDL phenotype, are reviewed and discuss together with new therapeutics employed for restoring HDL function.
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Affiliation(s)
- Valentin Gogonea
- Department of Chemistry, Cleveland State UniversityCleveland, OH, USA; Departments of Cellular and Molecular Medicine and the Center for Cardiovascular Diagnostics and Prevention, Cleveland ClinicCleveland, OH, USA
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3
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Chetty PS, Ohshiro M, Saito H, Dhanasekaran P, Lund-Katz S, Mayne L, Englander W, Phillips MC. Effects of the Iowa and Milano mutations on apolipoprotein A-I structure and dynamics determined by hydrogen exchange and mass spectrometry. Biochemistry 2012; 51:8993-9001. [PMID: 23066790 DOI: 10.1021/bi300926j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The Iowa point mutation in apolipoprotein A-I (G26R) leads to a systemic amyloidosis condition, and the Milano mutation (R173C) is associated with hypoalphalipoproteinemia, a reduced plasma level of high-density lipoprotein. To probe the structural effects that lead to these outcomes, we used amide hydrogen-deuterium exchange coupled with a fragment separation/mass spectrometry analysis (HX MS). The Iowa mutation inserts an arginine residue into the nonpolar face of an α-helix that spans residues 7-44 and causes changes in structure and structural dynamics. This helix unfolds, and other helices in the N-terminal helix bundle domain are destabilized. The segment encompassing residues 116-158, largely unstructured in wild-type apolipoprotein A-I, becomes helical. The helix spanning residues 81-115 is destabilized by 2 kcal/mol, increasing the small fraction of time it is transiently unfolded to ≥1%, which allows proteolysis at residue 83 in vivo over time, releasing an amyloid-forming peptide. The Milano mutation situated on the polar face of the helix spanning residues 147-178 destabilizes the helix bundle domain only moderately, but enough to allow cysteine-mediated dimerization that leads to the altered functionality of this variant. These results show how the HX MS approach can provide a powerful means of monitoring, in a nonperturbing way and at close to amino acid resolution, the structural, dynamic, and energetic consequences of biologically interesting point mutations.
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Affiliation(s)
- Palaniappan Sevugan Chetty
- Lipid Research Group, Gastroenterology, Hepatology and Nutrition Division, Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104-4318, United States
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4
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Murakami T, Wijagkanalan W, Hashida M, Tsuchida K. Intracellular drug delivery by genetically engineered high-density lipoprotein nanoparticles. Nanomedicine (Lond) 2010; 5:867-79. [DOI: 10.2217/nnm.10.66] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Aim: Nascent high-density lipoprotein (HDL) capable of intracellularly delivering anticancer drugs was developed to potentiate antitumor activities. Materials & methods: Apolipoprotein A-I, a major component protein of HDL, was genetically fused to TAT peptide, a protein transduction domain. Nascent HDL was prepared with this mutant and phospholipids. Results & discussion: Intracellular delivery of doxorubicin (DXR) by TAT-fused HDL was confirmed by confocal microscopy. Treatment of cancer cells with TAT-fused HDL–DXR complex resulted in enhanced growth inhibition. Furthermore, TAT-fused HDL–DXR complex suppressed tumor growth in mice more efficiently than HDL–DXR complex. No bodyweight loss was observed for the TAT complex. These results clearly demonstrate the usefulness of TAT fusion to nascent HDL to potentiate the antitumor activity of DXR. Conclusion: The genetic fusion of apoA-I with biologically active peptides potentially enables a simple assembly of biocompatible and versatile drug carriers.
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Affiliation(s)
- Tatsuya Murakami
- Institute for Comprehensive Medical Science, Fujita Health University, Toyoake, Aichi 470–1192, Japan
- PRESTO, JST, 4–1-8 Honcho Kawaguchi, Saitama 332–0012, Japan
- Institute for Integrated Cell-Material Sciences, Kyoto University, Sakyo-ku, Kyoto 606–8304, Japan
| | - Wassana Wijagkanalan
- Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606–8501, Japan
| | - Mitsuru Hashida
- Institute for Integrated Cell-Material Sciences, Kyoto University, Sakyo-ku, Kyoto 606–8304, Japan
- Department of Drug Delivery Research, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606–8501, Japan
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5
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Kono M, Tanaka T, Tanaka M, Vedhachalam C, Chetty PS, Nguyen D, Dhanasekaran P, Lund-Katz S, Phillips MC, Saito H. Disruption of the C-terminal helix by single amino acid deletion is directly responsible for impaired cholesterol efflux ability of apolipoprotein A-I Nichinan. J Lipid Res 2009; 51:809-18. [PMID: 19805625 DOI: 10.1194/jlr.m002113] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Apolipoprotein A-I (apoA-I) Nichinan, a naturally occurring variant with DeltaE235 in the C terminus, is associated with low plasma HDL levels. Here, we investigated the tertiary structure, lipid-binding properties, and ability to induce cellular cholesterol efflux of apoA-I Nichinan and its C-terminal peptide. Thermal and chemical denaturation experiments demonstrated that the DeltaE235 mutation decreased the protein stability compared with wild type (WT). ApoA-I Nichinan exhibited capabilities to bind to or solubilize lipid vesicles that are intermediate to that of WT and a L230P/L233P/Y236P variant in which the C-terminal alpha-helix folding is completely disrupted and forms relatively larger and unstable discoidal complexes, indicating that perturbation of the C-terminal alpha-helical structure by the DeltaE235 mutation leads to reduced lipid binding. Supporting this, apoA-I 209-241/DeltaE235 peptide showed significantly decreased ability to form alpha-helix both in the lipid-free and lipid-bound states, and reduced efficiency to solubilize vesicles. In addition, both apoA-I Nichinan and its C-terminal peptide exhibited reduced activity in ABCA1-mediated cellular cholesterol efflux. Thus, the disruption of the ability of the C-terminal region to form alpha-helix caused by the E235 deletion appears to be the important determinant of impaired lipid binding and cholesterol efflux ability and, consequently, the low plasma HDL levels of apoA-I Nichinan probands.
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Affiliation(s)
- Momoe Kono
- Department of Biophysical Chemistry, Kobe Pharmaceutical University, Kobe, Japan
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6
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Tanaka T, Tanaka M, Sugiura M, Kawakami T, Aimoto S, Saito H. Deletion of single amino acid E235 affects the structure and lipid interaction of human apolipoprotein A-I C-terminal peptides. Chem Pharm Bull (Tokyo) 2009; 57:499-503. [PMID: 19420782 DOI: 10.1248/cpb.57.499] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The C-terminal domain of apolipoprotein (apo) A-I plays an important role in lipid binding. ApoA-I Nichinan, a naturally occurring human apoA-I variant with a deletion of E235 located in the C-terminus, is associated with low high-density lipoprotein (HDL) cholesterolemia. In the present study, a series of variant peptides corresponding to residues 220-241 of human apoA-I were examined to clarify the influences of E235 deletion (DeltaE235) on the structure and lipid interaction of the C-terminal region. NMR studies demonstrated that in trifluoroethanol, apoA-I 220-241/DeltaE235 peptide forms the alpha-helical structure similar to wild-type (WT) peptide. Circular dichroism measurements revealed that the interaction with phospholipid vesicles induced structural changes from random coil to alpha-helix both in apoA-I 220-241 WT and E235A, a variant with a negative charge ablation, peptides. These peptides also showed abilities to form HDL-like particles through microsolubilization of phospholipid vesicles, indicating that the negative charge ablation in E235 has no effect on the lipid interaction. By contrast, neither lipid binding-induced alpha-helix formation nor microsolubilization of vesicles were observed in apoA-I 220-241/DeltaE235 and L230P, a helix-breaking variant, peptides. In addition, fluorescence measurements showed that tryptophan fluorescence intensity of apoA-I 220-241/F225W greatly increased upon lipid binding, while only a little increase was observed for the corresponding DeltaE235 variant. Taken together, these results suggest that the deletion of E235 causes defective lipid binding of apoA-I Nichinan because of the impaired helix-forming ability of the C-terminal residues.
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Affiliation(s)
- Toshitaka Tanaka
- Department of Biophysical Chemistry, Kobe Pharmaceutical University, Kobe, Hyogo, Japan
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7
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Tanaka M, Tanaka T, Ohta S, Kawakami T, Konno H, Akaji K, Aimoto S, Saito H. Evaluation of lipid-binding properties of the N-terminal helical segments in human apolipoprotein A-I using fragment peptides. J Pept Sci 2009; 15:36-42. [DOI: 10.1002/psc.1092] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Kontush A, Chapman MJ. Functionally defective high-density lipoprotein: a new therapeutic target at the crossroads of dyslipidemia, inflammation, and atherosclerosis. Pharmacol Rev 2006; 58:342-74. [PMID: 16968945 DOI: 10.1124/pr.58.3.1] [Citation(s) in RCA: 533] [Impact Index Per Article: 29.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
High-density lipoproteins (HDL) possess key atheroprotective biological properties, including cellular cholesterol efflux capacity, and anti-oxidative and anti-inflammatory activities. Plasma HDL particles are highly heterogeneous in physicochemical properties, metabolism, and biological activity. Within the circulating HDL particle population, small, dense HDL particles display elevated cellular cholesterol efflux capacity, afford potent protection of atherogenic low-density lipoprotein against oxidative stress and attenuate inflammation. The antiatherogenic properties of HDL can, however be compromised in metabolic diseases associated with accelerated atherosclerosis. Indeed, metabolic syndrome and type 2 diabetes are characterized not only by elevated cardiovascular risk and by low HDL-cholesterol (HDL-C) levels but also by defective HDL function. Functional HDL deficiency is intimately associated with alterations in intravascular HDL metabolism and structure. Indeed, formation of HDL particles with attenuated antiatherogenic activity is mechanistically related to core lipid enrichment in triglycerides and cholesteryl ester depletion, altered apolipoprotein A-I (apoA-I) conformation, replacement of apoA-I by serum amyloid A, and covalent modification of HDL protein components by oxidation and glycation. Deficient HDL function and subnormal HDL-C levels may act synergistically to accelerate atherosclerosis in metabolic disease. Therapeutic normalization of attenuated antiatherogenic HDL function in terms of both particle number and quality of HDL particles is the target of innovative pharmacological approaches to HDL raising, including inhibition of cholesteryl ester transfer protein, enhanced lipidation of apoA-I with nicotinic acid and infusion of reconstituted HDL or apoA-I mimetics. A preferential increase in circulating concentrations of HDL particles possessing normalized antiatherogenic activity is therefore a promising therapeutic strategy for the treatment of common metabolic diseases featuring dyslipidemia, inflammation, and premature atherosclerosis.
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Affiliation(s)
- Anatol Kontush
- Dyslipoproteinemia and Atherosclerosis Research Unit, National Institute for Health and Medical Research, Hôpital de la Pitié, 83 boulevard de l'Hôpital, 75651 Paris Cedex 13, France.
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9
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Kontush A, de Faria EC, Chantepie S, Chapman MJ. A normotriglyceridemic, low HDL-cholesterol phenotype is characterised by elevated oxidative stress and HDL particles with attenuated antioxidative activity. Atherosclerosis 2005; 182:277-85. [PMID: 16159600 DOI: 10.1016/j.atherosclerosis.2005.03.001] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2004] [Accepted: 03/03/2005] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Low levels of high density lipoprotein-cholesterol (HDL-C) are highly prevalent in subjects presenting premature atherosclerosis. It is indeterminate as to whether high cardiovascular risk in low HDL-C subjects occurs concomitantly with elevated oxidative stress and/or with biologically dysfunctional HDL particles. METHODS AND RESULTS Systemic oxidative stress (as plasma 8-isoprostanes) was 2.3-fold elevated (p<0.05) in normocholesterolemic, normotriglyceridemic, normoglycemic low HDL-C subjects (plasma HDL-C, <40 mg/dL; n=8) as compared to normolipidemic controls (n=15). HDL subfractions (HDL2b, 2a, 3a, 3b and 3c) isolated by density gradient ultracentrifugation from low HDL-C subjects displayed significantly lower (-21 to -43%, p<0.05) specific antioxidative activity (sAA; capacity to protect LDL from oxidation on a unit particle mass or on a particle number basis) as compared to controls. Altered chemical composition (core triglyceride enrichment, cholesteryl ester depletion) paralleled antioxidative dysfunction of HDL subfractions. Plasma 8-isoprostane levels negatively correlated with sAA of HDL subfractions and positively correlated with the total cholesterol/HDL-C ratio, which was significantly elevated in the low HDL-C phenotype. CONCLUSIONS Low HDL-C subjects display elevated oxidative stress and possess HDL particle subspecies with attenuated intrinsic antioxidative activity which is intimately related to their altered chemical composition.
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Affiliation(s)
- Anatol Kontush
- Dyslipoproteinemia and Atherosclerosis Research Unit (U.551), National Institute for Health and Medical Research (INSERM), Hôpital de la Pitié, 83 boulevard de l'Hôpital, 75651 Paris Cedex 13, France.
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10
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Hoang A, Huang W, Sasaki J, Sviridov D. Natural mutations of apolipoprotein A-I impairing activation of lecithin:cholesterol acyltransferase. BIOCHIMICA ET BIOPHYSICA ACTA 2003; 1631:72-6. [PMID: 12573451 DOI: 10.1016/s1388-1981(02)00357-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Five natural mutations of apolipoprotein A-I (apoA-I), apoA-I(A95D), apoA-I(Y100H), apoA-I(E110K), apoA-I(V156E) and apoA-I(H162Q), were studied for their ability to activate lecithin:cholesterol acyltransferase (LCAT). Mutants apoA-I(E110K), apoA-I(V156E) and apoA-I(H162Q) had an impaired ability to activate LCAT. Combined with data on other apoA-I mutants this finding is consistent with the idea that the central region between amino acids 110 and 160 is likely to be the "active site" of apoA-I involved in the interaction with LCAT and that a specific sequence of apoA-I is required for activation of the enzyme.
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Affiliation(s)
- Anh Hoang
- Wynn Domain, Baker Medical Research Institute, PO Box 6492 St Kilda Rd Central, Melbourne Vic 8008, Australia
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Sviridov D, Hoang A, Huang W, Sasaki J. Structure-function studies of apoA-I variants:site-directed mutagenesis and natural mutations. J Lipid Res 2002. [DOI: 10.1194/jlr.m100437-jlr200] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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12
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Ritter M, Buechler C, Boettcher A, Barlage S, Schmitz-Madry A, Orsó E, Bared SM, Schmiedeknecht G, Baehr CH, Fricker G, Schmitz G. Cloning and characterization of a novel apolipoprotein A-I binding protein, AI-BP, secreted by cells of the kidney proximal tubules in response to HDL or ApoA-I. Genomics 2002; 79:693-702. [PMID: 11991719 DOI: 10.1006/geno.2002.6761] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Apolipoprotein A-I (apoA-I) is the major apolipoprotein of high-density lipoproteins (HDL) and has an important role in the regulation of the stability, lipid transport, and metabolism of HDL particles. To identify novel proteins that are involved in HDL metabolism, we used mature apoA-I (amino acids 25-267) as a bait for the screening of a human liver two-hybrid cDNA library. Among the identified genes, several encoded known proteins, including serum amyloid A(2a) (SAA(2a)), apoC-I, and phosphodiesterase HCAM1 (PDE1A), found to interact with apoA-I. In addition, we have cloned a novel 29 kDa apoA-I interacting protein, which we named AI-BP (apoA-I binding protein). The AI-BP encoding gene, APOA1BP, which is located on chromosome 1q21, is composed of six exons and five introns and spans 2.5 kb. Northern blot analysis demonstrated ubiquitous expression of the APOA1BP mRNA with the highest expression in kidney, heart, liver, thyroid gland, adrenal gland, and testis. AI-BP protein is not detectable in serum of healthy probands, but serum samples of patients with septic syndromes may contain elevated levels of AI-BP. Significant amounts of AI-BP protein are found in cerebrospinal fluid and urine of healthy probands. The stimulation of cells derived from the kidney proximal tubules with apoA-I or HDL induces a concentration-dependent secretion of AI-BP indicating an important role for AI-BP, in the renal tubular degradation or resorption of apoA-I.
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MESH Headings
- Amino Acid Sequence
- Animals
- Apolipoprotein A-I/genetics
- Apolipoprotein A-I/metabolism
- Apolipoprotein A-I/pharmacology
- Base Sequence
- Caco-2 Cells
- Carrier Proteins/genetics
- Carrier Proteins/metabolism
- Cell Line
- Cloning, Molecular
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Dose-Response Relationship, Drug
- Gene Expression
- Genes/genetics
- Humans
- Kidney Tubules, Proximal/cytology
- Kidney Tubules, Proximal/drug effects
- Kidney Tubules, Proximal/metabolism
- Lipoproteins, HDL/pharmacology
- Mice
- Molecular Sequence Data
- Pregnancy Proteins
- Protein Binding
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Racemases and Epimerases
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tumor Cells, Cultured
- Two-Hybrid System Techniques
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Affiliation(s)
- Mirko Ritter
- Institute for Clinical Chemistry and Laboratory Medicine, University of Regensburg, D-93042 Regensburg, Germany
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13
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Abstract
This review considers the antiatherogenic function of high density lipoprotein (HDL) from the point of view of its dynamics within the sequential steps of reverse cholesterol transport (RCT). It is postulated that the efficiency of cholesterol flux through the RCT pathways is clinically more relevant than the HDL cholesterol concentration. The particular role of pre-beta(1)-HDL is reviewed drawing attention to the relationship between its concentration and the flux of cholesterol through the RCT system.
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Affiliation(s)
- Dmitri Sviridov
- Baker Medical Research Institute, PO Box 6492, St. Kilda Rd. Central, Melbourne, Vic. 8008, Australia.
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14
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Abstract
Approximately 46 human apolipoprotein A-I (apoA-I) coding sequence mutations have been reported to date. Roughly half of these mutations are associated with lower than average plasma concentrations of high-density lipoprotein (HDL) apoA-I. Mutations associated with low HDL apoA-I concentrations fall into two main categories: those which poorly activate the enzyme lecithin:cholesterol acyltransferase (LCAT) and those associated with amyloidosis. These phenotypically distinct groups of mutations are uniquely localized in different regions of the apoprotein sequence. Mutations associated with abnormal LCAT activation are located within repeats 5, 6, and 7, corresponding to amino acids 121 to 186, while many of the mutations found in amyloid deposits are clustered at the amino terminus of the protein, namely residues 1 to 90. These observations strongly support the idea that the tertiary structure of apoA-I determines its intravascular fate and ultimately the steady state concentration of plasma HDL.
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Affiliation(s)
- Mary G Sorci-Thomas
- Department of Pathology, Wake Forest University Baptist Medical Center, Winston-Salem, North Carolina, USA.
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15
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Huang W, Matsunaga A, Li W, Han H, Hoang A, Kugi M, Koga T, Sviridov D, Fidge N, Sasaki J. Recombinant proapoA-I(Lys107del) shows impaired lipid binding associated with reduced binding to plasma high density lipoprotein. Atherosclerosis 2001; 159:85-91. [PMID: 11689210 DOI: 10.1016/s0021-9150(01)00496-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
In the present study apoA-I (Lys 107del), a naturally occurring human apoA-I variant with a deletion of Lys 107, was expressed in E. coli to examine the effect of this mutation on lipid binding, cholesterol efflux and lecithin:cholesterol acyltranferase (LCAT) activation. Dimyristoyl phosphatidylcholine (DMPC) binding studies revealed slow interaction of proapoA-I(Lys107del) with DMPC relative to normal proapoA-I. After preincubation with human plasma lipoprotein (d<1.225 g/ml) for 1 h at 37 degrees C, 125I-labeled normal proapoA-I chromatographed as a single peak with the high density lipoprotein (HDL) fraction, whereas 125I-labeled proapoA-I(Lys107del) chromatographed with both HDL and free proapoA-I (26% of the radioactivity). Circular dichroism measurements showed that the alpha-helical content of lipid-bound proapoA-I (Lys107del) was reduced to 64 versus 73% of normal proapoA-I. Non-denaturing gradient gel electrophoresis of reconstituted HDL assembled with either proapoA-I(Lys107del) or normal proapoA-I showed that the mutation led to the formation of a second population of smaller rHDL particles. DMPC/proapoA-I(Lys107del) and normal DMPC/proapoA-I complexes exhibited a similar capacity to promote cholesterol efflux from fibroblasts. ProapoA-I (Lys107del) also activated LCAT similar to wild type proapoA-I and human plasma apoA-I. We conclude that deletion of Lys 107 substantially alters the lipid binding properties of the protein, which correlated with reduced binding to plasma HDL in vitro, but did not affect the capacity of the mutant/lipid complex to promote cholesterol efflux or activate LCAT.
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Affiliation(s)
- W Huang
- Department of Internal Medicine, Fukuoka University, School of Medicine, 45-1, 7-chome Nanakuma, Jonan-ku, 814-80, Fukuoka, Japan
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16
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Sasaki J, Matsunaga A, Huang W, Han H, Li W, Kugi M, Koga T. Structural and functional properties of apolipoprotein A-I mutants. J Atheroscler Thromb 2001; 7:67-70. [PMID: 11426584 DOI: 10.5551/jat1994.7.67] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Apolipoprotein (apo) A-I is composed of 243 amino acid residues that fold into amphipathic helixes, and plays a central role in the high density lipoprotein (HDL) metabolism. Familial apoA-I deficiency is a rare metabolic disorder of which three cases have been characterized at a molecular level in western Japan. However, in subjects with apoA-I deficiency, coronary artery disease was not always present. One apo A-I deficiency was compound heterozygous apoA-I mutant for a TATA box mutation and a structural nonsense mutation. To date, screening analysis in our laboratory has identified nine genetically-determined structural mutations of apo A-I. We have also characterized these apo A-I mutations, including apoA-I (Glu235del) Nichinan. Few structural mutations were associated with altered HDL cholesterol levels.
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Affiliation(s)
- J Sasaki
- Department of Internal Medicine, Fukuoka University School of Medicine, Japan.
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17
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Affiliation(s)
- P P Toth
- Sterling Rock Falls Clinic, Southern Illinois University School of Medicine, USA
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18
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Pajunen P, Syvänne M, Castro G, Nieminen MS, Taskinen MR. Cholesterol efflux capacity in vitro predicts the severity and extent of coronary artery disease in patients with and without type 2 diabetes. SCAND CARDIOVASC J 2001; 35:96-100. [PMID: 11405504 DOI: 10.1080/140174301750164736] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
OBJECTIVE To investigate the relation between severity and extent of coronary artery disease (CAD) and in vitro cholesterol efflux capacity. DESIGN This study consisted of 46 type 2 diabetic, and 42 nondiabetic men undergoing coronary angiography. Quantitative coronary angiography was used to estimate the severity, extent, and overall "atheroma burden" of CAD. The capacity of patient plasma to induce cholesterol efflux from cultured Fu5AH rat hepatoma cells was measured in vitro. RESULTS In the combined study population (n = 88), there was a significant inverse correlation between efflux and global atheroma burden (r = -0.23, p < 0.05). In the diabetic group, the global atheroma burden index was independently associated both with cholesterol efflux and with LpA-I levels. However, in the nondiabetic CAD group this association was lost when efflux and LpA-I levels were included in the same model. CONCLUSION The present study demonstrated that efflux capacity was inversely associated with the severity and extent of CAD. In the diabetic group this association was independent of LpA-I levels, suggesting impaired antiatherogenic potential of these particles in type 2 diabetic patients.
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Affiliation(s)
- P Pajunen
- Department of Medicine, Helsinki University Central Hospital, Finland
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Hayden MR, Clee SM, Brooks-Wilson A, Genest J, Attie A, Kastelein JJ. Cholesterol efflux regulatory protein, Tangier disease and familial high-density lipoprotein deficiency. Curr Opin Lipidol 2000; 11:117-22. [PMID: 10787172 DOI: 10.1097/00041433-200004000-00003] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Cellular cholesterol efflux, by which cholesterol is transported from peripheral cells to HDL acceptor molecules for transport to the liver, is the first step of reverse cholesterol transport. Two genetic disorders, Tangier disease and some cases of familial HDL deficiency, have defects of cellular cholesterol efflux. The recent discovery of mutations in the ABC1 gene, which encodes the cholesterol efflux regulatory protein, in both these disorders establishes cholesterol efflux regulatory protein as a rate-limiting factor in reverse cholesterol transport.
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Affiliation(s)
- M R Hayden
- Centre for Molecular Medicine & Therapeutics, Department of Medical Genetics, University of British Columbia, Vancouver, Canada.
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