1
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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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2
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Cooke AL, Morris J, Melchior JT, Street SE, Jerome WG, Huang R, Herr AB, Smith LE, Segrest JP, Remaley AT, Shah AS, Thompson TB, Davidson WS. A thumbwheel mechanism for APOA1 activation of LCAT activity in HDL. J Lipid Res 2018; 59:1244-1255. [PMID: 29773713 DOI: 10.1194/jlr.m085332] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2018] [Revised: 05/08/2018] [Indexed: 01/28/2023] Open
Abstract
APOA1 is the most abundant protein in HDL. It modulates interactions that affect HDL's cardioprotective functions, in part via its activation of the enzyme, LCAT. On nascent discoidal HDL, APOA1 comprises 10 α-helical repeats arranged in an anti-parallel stacked-ring structure that encapsulates a lipid bilayer. Previous chemical cross-linking studies suggested that these APOA1 rings can adopt at least two different orientations, or registries, with respect to each other; however, the functional impact of these structural changes is unknown. Here, we placed cysteine residues at locations predicted to form disulfide bonds in each orientation and then measured APOA1's ability to adopt the two registries during HDL particle formation. We found that most APOA1 oriented with the fifth helix of one molecule across from fifth helix of the other (5/5 helical registry), but a fraction adopted a 5/2 registry. Engineered HDLs that were locked in 5/5 or 5/2 registries by disulfide bonds equally promoted cholesterol efflux from macrophages, indicating functional particles. However, unlike the 5/5 registry or the WT, the 5/2 registry impaired LCAT cholesteryl esterification activity (P < 0.001), despite LCAT binding equally to all particles. Chemical cross-linking studies suggest that full LCAT activity requires a hybrid epitope composed of helices 5-7 on one APOA1 molecule and helices 3-4 on the other. Thus, APOA1 may use a reciprocating thumbwheel-like mechanism to activate HDL-remodeling proteins.
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Affiliation(s)
- Allison L Cooke
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - Jamie Morris
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - John T Melchior
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - Scott E Street
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - W Gray Jerome
- Departments of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Rong Huang
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
| | - Andrew B Herr
- Division of Immunobiology and Center for Systems Immunology Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
| | - Loren E Smith
- Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Jere P Segrest
- Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Cardiovascular-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892
| | - Amy S Shah
- Division of Endocrinology, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229
| | - Thomas B Thompson
- Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati, Cincinnati, OH 45237
| | - W Sean Davidson
- Departments of Pathology and Laboratory Medicine University of Cincinnati, Cincinnati, OH 45237
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3
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Leyria J, Fruttero LL, Ligabue-Braun R, Defferrari MS, Arrese EL, Soulages JL, Settembrini BP, Carlini CR, Canavoso LE. DmCatD, a cathepsin D-like peptidase of the hematophagous insect Dipetalogaster maxima (Hemiptera: Reduviidae): Purification, bioinformatic analyses and the significance of its interaction with lipophorin in the internalization by developing oocytes. JOURNAL OF INSECT PHYSIOLOGY 2018; 105:28-39. [PMID: 29325877 PMCID: PMC5892828 DOI: 10.1016/j.jinsphys.2018.01.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Revised: 12/29/2017] [Accepted: 01/06/2018] [Indexed: 06/07/2023]
Abstract
DmCatD, a cathepsin D-like peptidase of the hematophagous insect Dipetalogaster maxima, is synthesized by the fat body and the ovary and functions as yolk protein precursor. Functionally, DmCatD is involved in vitellin proteolysis. In this work, we purified and sequenced DmCatD, performed bioinformatic analyses and investigated the events involved in its targeting and storage in developing oocytes. By ion exchange and gel filtration chromatography, DmCatD was purified from egg homogenates and its identity was confirmed by mass spectrometry. Approximately 73% of the full-length transcript was sequenced. The phylogeny indicated that DmCatD has features which suggest its distancing from "classical" cathepsins D. Bioinformatic analyses using a chimeric construct were employed to predict post-translational modifications. Structural modeling showed that DmCatD exhibited the expected folding for this type of enzyme, and an active site with conserved architecture. The interaction between DmCatD and lipophorin in the hemolymph was demonstrated by co-immunoprecipitation. Colocalization of both proteins in developing oocyte membranes and yolk bodies was detected by immunofluorescence. Docking assays favoring the interaction DmCatD-lipophorin were carried out after modeling lipophorin of a related triatomine species. Our results suggest that lipophorin acts as a carrier for DmCatD to facilitate its further internalization by the oocytes. The mechanisms involved in the uptake of peptidases within the oocytes of insects have not been reported. This is the first experimental work supporting the interaction between cathepsin D and lipophorin in an insect species, enabling us to propose a pathway for its targeting and storage in developing oocytes.
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Affiliation(s)
- Jimena Leyria
- Departamento de Bioquímica Clínica-CIBICI-CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
| | - Leonardo L Fruttero
- Departamento de Bioquímica Clínica-CIBICI-CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina; Brain Institute (Instituto do Cérebro-INSCER), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil.
| | - Rodrigo Ligabue-Braun
- Center of Biotechnology, Universidade Federal do Rio Grande do Sul Porto Alegre, RS, Brazil.
| | - Marina S Defferrari
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada.
| | - Estela L Arrese
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, USA.
| | - José L Soulages
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, OK, USA.
| | | | - Celia R Carlini
- Brain Institute (Instituto do Cérebro-INSCER), Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre, Brazil; Center of Biotechnology, Universidade Federal do Rio Grande do Sul Porto Alegre, RS, Brazil.
| | - Lilián E Canavoso
- Departamento de Bioquímica Clínica-CIBICI-CONICET, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Córdoba, Argentina.
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4
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Melchior JT, Street SE, Andraski AB, Furtado JD, Sacks FM, Shute RL, Greve EI, Swertfeger DK, Li H, Shah AS, Lu LJ, Davidson WS. Apolipoprotein A-II alters the proteome of human lipoproteins and enhances cholesterol efflux from ABCA1. J Lipid Res 2017; 58:1374-1385. [PMID: 28476857 DOI: 10.1194/jlr.m075382] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 04/25/2017] [Indexed: 12/25/2022] Open
Abstract
HDLs are a family of heterogeneous particles that vary in size, composition, and function. The structure of most HDLs is maintained by two scaffold proteins, apoA-I and apoA-II, but up to 95 other "accessory" proteins have been found associated with the particles. Recent evidence suggests that these accessory proteins are distributed across various subspecies and drive specific biological functions. Unfortunately, our understanding of the molecular composition of such subspecies is limited. To begin to address this issue, we separated human plasma and HDL isolated by ultracentrifugation (UC-HDL) into particles with apoA-I and no apoA-II (LpA-I) and those with both apoA-I and apoA-II (LpA-I/A-II). MS studies revealed distinct differences between the subfractions. LpA-I exhibited significantly more protein diversity than LpA-I/A-II when isolated directly from plasma. However, this difference was lost in UC-HDL. Most LpA-I/A-II accessory proteins were associated with lipid transport pathways, whereas those in LpA-I were associated with inflammatory response, hemostasis, immune response, metal ion binding, and protease inhibition. We found that the presence of apoA-II enhanced ABCA1-mediated efflux compared with LpA-I particles. This effect was independent of the accessory protein signature suggesting that apoA-II induces a structural change in apoA-I in HDLs.
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Affiliation(s)
- John T Melchior
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Scott E Street
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Allison B Andraski
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Jeremy D Furtado
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Frank M Sacks
- Department of Nutrition, Harvard T. H. Chan School of Public Health, Boston, MA 02115; Department of Genetics & Complex Diseases, Harvard T. H. Chan School of Public Health, Boston, MA 02115
| | - Rebecca L Shute
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Emily I Greve
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237
| | - Debi K Swertfeger
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Hailong Li
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - Amy S Shah
- Division of Endocrinology, Department of Pediatrics, Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - L Jason Lu
- Division of Biomedical Informatics Cincinnati Children's Hospital Research Foundation, Cincinnati, OH 45229
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, Center for Lipid and Arteriosclerosis Science, University of Cincinnati, Cincinnati, OH 45237.
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5
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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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6
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Polymorphisms of mouse apolipoprotein A-II alter its physical and functional nature. PLoS One 2014; 9:e88705. [PMID: 24520415 PMCID: PMC3919794 DOI: 10.1371/journal.pone.0088705] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2013] [Accepted: 01/16/2014] [Indexed: 11/19/2022] Open
Abstract
ApoA-II is the second most abundant protein on HDL making up ∼ 20% of the total protein but its functions have still only been partially characterized. Recent methodological improvements have allowed for the recombinant expression and characterization of human apoA-II which shares only 55% sequence homology with murine apoA-II. Here we describe the purification of the two most common polymorphic variants of apoA-II found in inbred mouse strains, differing at 3 amino acid sites. C57BL/6 mice having variant apoA-II(a) have lower plasma HDL levels than FVB/N mice that have variant apoA-II(b). Characterization of the helical structure of these two variants reveals a more alpha-helical structure for the FVB/N apoA-II. These changes do not alter the lipid or HDL binding of the two apoA-II variants, but significantly increase the ability of the FVB/N variant to promote both ABCA1 and ABCG1 mediated cellular cholesterol efflux. These differences may be differentially altering plasma HDL apoA-II levels. In vivo, neither C57 nor FVB apoA-II protein levels are affected by the absence of apoE, while an apoE/apoA-I double deficiency results in a 50% decrease of plasma FVB apoA-II but results in undetectable levels of C57 apoA-II in the plasma. FVB apoA-II is able to form an HDL particle in the absence of apoE or apoA-I.
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7
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Kellner-Weibel G, de la Llera-Moya M. Update on HDL receptors and cellular cholesterol transport. Curr Atheroscler Rep 2011; 13:233-41. [PMID: 21302003 DOI: 10.1007/s11883-011-0169-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Efflux is central to maintenance of tissue and whole body cholesterol homeostasis. The discovery of cell surface receptors that bind high-density lipoprotein (HDL) with high specificity and affinity to promote cholesterol release has significantly advanced our understanding of cholesterol efflux. We now know that 1) cells have several mechanisms to promote cholesterol release, including a passive mechanism that depends on the physico-chemical properties of cholesterol molecules and their interactions with phospholipids; 2) a variety of HDL particles can interact with receptors to promote cholesterol transport from tissues to the liver for excretion; and 3) interactions between HDL and receptors show functional synergy. Therefore, efflux efficiency depends both on the arrays of receptors on tissue cells and HDL particles in serum.
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Affiliation(s)
- Ginny Kellner-Weibel
- Division of Gastroenterology, Hepatology and Nutrition, The Children's Hospital of Philadelphia, 3615 Civic Center Blvd., ARC1102G, Philadelphia, PA 19104-4318, USA.
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8
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Tietjen I, Hovingh GK, Singaraja R, Radomski C, McEwen J, Chan E, Mattice M, Legendre A, Kastelein JJP, Hayden MR. Increased risk of coronary artery disease in Caucasians with extremely low HDL cholesterol due to mutations in ABCA1, APOA1, and LCAT. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:416-24. [PMID: 21875686 DOI: 10.1016/j.bbalip.2011.08.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 08/10/2011] [Accepted: 08/15/2011] [Indexed: 11/16/2022]
Abstract
Mutations in ABCA1, APOA1, and LCAT reduce HDL cholesterol (HDLc) in humans. However, the prevalence of these mutations and their relative effects on HDLc reduction and risk of coronary artery disease (CAD) are less clear. Here we searched for ABCA1, APOA1, and LCAT mutations in 178 unrelated probands with HDLc <10th percentile but no other major lipid abnormalities, including 89 with ≥1 first-degree relative with low HDLc (familial probands) and 89 where familial status of low HDLc is uncertain (unknown probands). Mutations were most frequent in LCAT (15.7%), followed by ABCA1 (9.0%) and APOA1 (4.5%), and were found in 42.7% of familial but only 14.6% of unknown probands (p=2.44∗10(-5)). Interestingly, only 16 of 24 (66.7%) mutations assessed in families conferred an average HDLc <10th percentile. Furthermore, only mutation carriers with HDLc <5th percentile had elevated risk of CAD (odds ratio (OR)=2.26 for 34 ABCA1 mutation carriers vs. 149 total first-degree relative controls, p=0.05; OR=2.50 for 26 APOA1 mutation carriers, p=0.04; OR=3.44 for 38 LCAT mutation carriers, p=1.1∗10(-3)). These observations show that mutations in ABCA1, APOA1, and LCAT are sufficient to explain >40% of familial hypoalphalipoproteinemia in this cohort. Moreover, individuals with mutations and large reductions in HDLc have increased risk of CAD. 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)
- Ian Tietjen
- Xenon Pharmaceuticals Inc., Burnaby, BC, Canada
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9
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Sriram R, Lagerstedt JO, Petrlova J, Samardzic H, Kreutzer U, Xie H, Kaysen GA, Desreux JF, Thonon D, Jacques V, Van Loan M, Rutledge JC, Oda MN, Voss JC, Jue T. Imaging apolipoprotein AI in vivo. NMR IN BIOMEDICINE 2011; 24:916-24. [PMID: 21264979 PMCID: PMC3726305 DOI: 10.1002/nbm.1650] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 10/20/2010] [Accepted: 10/31/2010] [Indexed: 05/30/2023]
Abstract
Coronary disease risk increases inversely with high-density lipoprotein (HDL) level. The measurement of the biodistribution and clearance of HDL in vivo, however, has posed a technical challenge. This study presents an approach to the development of a lipoprotein MRI agent by linking gadolinium methanethiosulfonate (Gd[MTS-ADO3A]) to a selective cysteine mutation in position 55 of apo AI, the major protein of HDL. The contrast agent targets both liver and kidney, the sites of HDL catabolism, whereas the standard MRI contrast agent, gadolinium-diethylenetriaminepentaacetic acid-bismethylamide (GdDTPA-BMA, gadodiamide), enhances only the kidney image. Using a modified apolipoprotein AI to create an HDL contrast agent provides a new approach to investigate HDL biodistribution, metabolism and regulation in vivo.
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Affiliation(s)
- Renuka Sriram
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, USA
| | | | - Jitka Petrlova
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, USA
| | - Haris Samardzic
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, USA
| | - Ulrike Kreutzer
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, USA
| | - Hongtao Xie
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, USA
| | - George A. Kaysen
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, USA
| | - Jean F. Desreux
- Coordination and Radiochemistry, University of Liege, Liege, Belgium
| | - David Thonon
- Coordination and Radiochemistry, University of Liege, Liege, Belgium
| | | | - Martha Van Loan
- Nutrition Department, University of California Davis, Davis, CA, USA
| | - John C. Rutledge
- Division of Endocrinology, Clinical Nutrition and Vascular Medicine, Department of Internal Medicine, University of California Davis, Davis, CA, USA
| | - Michael N. Oda
- Children’s Hospital Oakland Research Institute, Oakland, CA, USA
| | - John C. Voss
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, USA
| | - Thomas Jue
- Biochemistry and Molecular Medicine, University of California Davis, Davis, CA, USA
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10
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Tarling EJ, Edwards PA. Dancing with the sterols: critical roles for ABCG1, ABCA1, miRNAs, and nuclear and cell surface receptors in controlling cellular sterol homeostasis. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:386-95. [PMID: 21824529 DOI: 10.1016/j.bbalip.2011.07.011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 07/13/2011] [Accepted: 07/15/2011] [Indexed: 12/29/2022]
Abstract
ATP binding cassette (ABC) transporters represent a large and diverse family of proteins that transport specific substrates across a membrane. The importance of these transporters is illustrated by the finding that inactivating mutations within 17 different family members are known to lead to specific human diseases. Clinical data from humans and/or studies with mice lacking functional transporters indicate that ABCA1, ABCG1, ABCG4, ABCG5 and ABCG8 are involved in cholesterol and/or phospholipid transport. This review discusses the multiple mechanisms that control cellular sterol homeostasis, including the roles of microRNAs, nuclear and cell surface receptors and ABC transporters, with particular emphasis on recent findings that have provided insights into the role(s) of ABCG1. 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)
- Elizabeth J Tarling
- Department of Biological Chemistry, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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11
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Nagao K, Kimura Y, Ueda K. Lysine residues of ABCA1 are required for the interaction with apoA-I. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:530-5. [PMID: 21749932 DOI: 10.1016/j.bbalip.2011.06.024] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 06/07/2011] [Accepted: 06/20/2011] [Indexed: 10/18/2022]
Abstract
ATP-binding cassette protein A1 (ABCA1) plays a pivotal role in cholesterol homeostasis by generating high-density lipoprotein (HDL). Apolipoprotein A-I (apoA-I), a lipid acceptor for ABCA1, reportedly interacts with ABCA1. However, it has also been proposed that apoA-I interacts with ABCA1-generated special domains on the plasma membrane, but apart from ABCA1, and solubilizes membrane lipids. To determine the importance of the apoA-I-ABCA1 interaction in HDL formation, the electrostatic interaction between apoA-I and ABCA1, which mediates the interaction between apoB100 in low-density lipoprotein particles (LDL) and LDL receptor, was analyzed. The apoA-I binding to ABCA1 and the cross-linking between them were inhibited by the highly charged molecules heparin and poly-L-lysine. Treating cells with membrane impermeable reagents that specifically react with primary amino groups abolished the interaction between apoA-I and ABCA1. However, these reagents did not affect the characteristic tight ATP binding to ABCA1. These results suggest that lysine residues in the extracellular domains of ABCA1 contribute to the interaction with apoA-I. The electrostatic interaction between ABCA1 and apoA-I is predicted to be the first step in HDL formation. 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)
- Kohjiro Nagao
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto 606-8502, Japan
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Lagerstedt JO, Cavigiolio G, Budamagunta MS, Pagani I, Voss JC, Oda MN. Structure of apolipoprotein A-I N terminus on nascent high density lipoproteins. J Biol Chem 2010; 286:2966-75. [PMID: 21047795 DOI: 10.1074/jbc.m110.163097] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apolipoprotein A-I (apoA-I) is the major protein component of high density lipoproteins (HDL) and a critical element of cholesterol metabolism. To better elucidate the role of the apoA-I structure-function in cholesterol metabolism, the conformation of the apoA-I N terminus (residues 6-98) on nascent HDL was examined by electron paramagnetic resonance (EPR) spectroscopic analysis. A series of 93 apoA-I variants bearing single nitroxide spin label at positions 6-98 was reconstituted onto 9.6-nm HDL particles (rHDL). These particles were subjected to EPR spectral analysis, measuring regional flexibility and side chain solvent accessibility. Secondary structure was elucidated from side-chain mobility and molecular accessibility, wherein two major α-helical domains were localized to residues 6-34 and 50-98. We identified an unstructured segment (residues 35-39) and a β-strand (residues 40-49) between the two helices. Residues 14, 19, 34, 37, 41, and 58 were examined by EPR on 7.8, 8.4, and 9.6 nm rHDL to assess the effect of particle size on the N-terminal structure. Residues 14, 19, and 58 showed no significant rHDL size-dependent spectral or accessibility differences, whereas residues 34, 37, and 41 displayed moderate spectral changes along with substantial rHDL size-dependent differences in molecular accessibility. We have elucidated the secondary structure of the N-terminal domain of apoA-I on 9.6 nm rHDL (residues 6-98) and identified residues in this region that are affected by particle size. We conclude that the inter-helical segment (residues 35-49) plays a role in the adaptation of apoA-I to the particle size of HDL.
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Affiliation(s)
- Jens O Lagerstedt
- Department of Experimental Medical Science, Lund University, S-221 84 Lund, Sweden
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