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Bhale AS, Meilhac O, d'Hellencourt CL, Vijayalakshmi MA, Venkataraman K. Cholesterol transport and beyond: Illuminating the versatile functions of HDL apolipoproteins through structural insights and functional implications. Biofactors 2024. [PMID: 38661230 DOI: 10.1002/biof.2057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2024] [Accepted: 04/02/2024] [Indexed: 04/26/2024]
Abstract
High-density lipoproteins (HDLs) play a vital role in lipid metabolism and cardiovascular health, as they are intricately involved in cholesterol transport and inflammation modulation. The proteome of HDL particles is indeed complex and distinct from other components in the bloodstream. Proteomics studies have identified nearly 285 different proteins associated with HDL; however, this review focuses more on the 15 or so traditionally named "apo" lipoproteins. Important lipid metabolizing enzymes closely working with the apolipoproteins are also discussed. Apolipoproteins stand out for their integral role in HDL stability, structure, function, and metabolism. The unique structure and functions of each apolipoprotein influence important processes such as inflammation regulation and lipid metabolism. These interactions also shape the stability and performance of HDL particles. HDLs apolipoproteins have multifaceted roles beyond cardiovascular diseases (CVDs) and are involved in various physiological processes and disease states. Therefore, a detailed exploration of these apolipoproteins can offer valuable insights into potential diagnostic markers and therapeutic targets. This comprehensive review article aims to provide an in-depth understanding of HDL apolipoproteins, highlighting their distinct structures, functions, and contributions to various physiological processes. Exploiting this knowledge holds great potential for improving HDL function, enhancing cholesterol efflux, and modulating inflammatory processes, ultimately benefiting individuals by limiting the risks associated with CVDs and other inflammation-based pathologies. Understanding the nature of all 15 apolipoproteins expands our knowledge of HDL metabolism, sheds light on their pathological implications, and paves the way for advancements in the diagnosis, prevention, and treatment of lipid and inflammatory-related disorders.
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Affiliation(s)
- Aishwarya Sudam Bhale
- Centre for Bio-Separation Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Olivier Meilhac
- Inserm, UMR 1188 Diabète Athérothrombose Thérapies Réunion Océan Indien (DéTROI), Université de La Réunion, Saint-Pierre, France
| | - Christian Lefebvre d'Hellencourt
- Inserm, UMR 1188 Diabète Athérothrombose Thérapies Réunion Océan Indien (DéTROI), Université de La Réunion, Saint-Pierre, France
| | | | - Krishnan Venkataraman
- Centre for Bio-Separation Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
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2
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Cho KH, Kim JE, Lee MS, Bahuguna A. Cuban Policosanol (Raydel ®) Exerts Higher Antioxidant and Anti-Glycation Activities than Chinese Policosanol (BOC Sciences) in Reconstituted High-Density Lipoproteins: In Vivo Anti-Inflammatory Activities in Zebrafish and Its Embryos. Pharmaceuticals (Basel) 2024; 17:406. [PMID: 38675370 PMCID: PMC11054325 DOI: 10.3390/ph17040406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 02/21/2024] [Accepted: 03/19/2024] [Indexed: 04/28/2024] Open
Abstract
The present study compares sugarcane-wax purified policosanols sourced from Cuba (Raydel®) and China (BOC Sciences) and utilized following the synthesis of reconstituted high-density lipoproteins (rHDL). The two policosanols exhibited distinctly different ingredient ratios of long-chain aliphatic alcohols, particularly 1-octacosanol (C28) and 1-tetratriacotanol (C34). After synthesizing rHDL with apolipoprotein A-I (apoA-I), the two policosanols bound well with phospholipid and apoA-I to form the discoidal rHDL. Notably, rHDL-1, containing Cuban policosanol, displayed the largest particle diameter at approximately 78 ± 3 nm. In contrast, both control rHDL (rHDL-0) and rHDL containing Chinese policosanol (rHDL-2) exhibited smaller particles, with diameters of approximately 58 ± 3 nm and 61 ± 2 nm, respectively. Furthermore, rHDL-1 demonstrated enhanced anti-glycation activity, safeguarding apoA-I from degradation within HDL, and displayed the antioxidant ability to inhibit LDL oxidation. A microinjection of each rHDL into zebrafish embryos in the presence of carboxymethyllysine (CML) revealed rHDL-1 to have the strongest antioxidant activity with the highest embryo survivability and normal developmental morphology. Dermal application to recover the wound revealed rHDL-1 to have the highest wound-healing activity (75%) and survivability (92%) in the cutaneous wound area in the presence of CML. In adult zebrafish, injecting CML (250 μg) caused acute death and hyperinflammation, marked by heightened neutrophil infiltration and interleukin (IL)-6 production in liver. However, co-administering rHDL-1 notably increased survival (85%) and exhibited strong anti-inflammatory properties, reducing IL-6 production while improving the blood lipid profile. However, a co-injection of rHDL-2 resulted in the lowest survivability (47%) with more hepatic inflammation. In conclusion, Cuban policosanol (Raydel®) has more desirable properties for the in vitro synthesis of rHDL with stronger anti-glycation and antioxidant activities than those of Chinese policosanol (BOC Sciences). Moreover, Raydel-policosanol-integrated rHDL demonstrates a noteworthy effect on accelerated wound healing and robust anti-inflammatory properties, leading to increased survivability in zebrafish embryos and adults by effectively suppressing CML-induced hyperinflammation.
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Affiliation(s)
- Kyung-Hyun Cho
- Raydel Research Institute, Medical Innovation Complex, Daegu 41061, Republic of Korea; (J.-E.K.); (A.B.)
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3
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Rossino G, Marchese E, Galli G, Verde F, Finizio M, Serra M, Linciano P, Collina S. Peptides as Therapeutic Agents: Challenges and Opportunities in the Green Transition Era. Molecules 2023; 28:7165. [PMID: 37894644 PMCID: PMC10609221 DOI: 10.3390/molecules28207165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/05/2023] [Accepted: 10/17/2023] [Indexed: 10/29/2023] Open
Abstract
Peptides are at the cutting edge of contemporary research for new potent, selective, and safe therapeutical agents. Their rise has reshaped the pharmaceutical landscape, providing solutions to challenges that traditional small molecules often cannot address. A wide variety of natural and modified peptides have been obtained and studied, and many others are advancing in clinical trials, covering multiple therapeutic areas. As the demand for peptide-based therapies grows, so does the need for sustainable and environmentally friendly synthesis methods. Traditional peptide synthesis, while effective, often involves environmentally draining processes, generating significant waste and consuming vast resources. The integration of green chemistry offers sustainable alternatives, prioritizing eco-friendly processes, waste reduction, and energy conservation. This review delves into the transformative potential of applying green chemistry principles to peptide synthesis by discussing relevant examples of the application of such approaches to the production of active pharmaceutical ingredients (APIs) with a peptide structure and how these efforts are critical for an effective green transition era in the pharmaceutical field.
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Affiliation(s)
- Giacomo Rossino
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy; (G.R.); (E.M.); (M.S.); (P.L.)
| | - Emanuela Marchese
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy; (G.R.); (E.M.); (M.S.); (P.L.)
- Department of Health Sciences, University “Magna Graecia”, Viale Europa, 88100 Catanzaro, Italy
| | - Giovanni Galli
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy; (G.R.); (E.M.); (M.S.); (P.L.)
| | - Francesca Verde
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy; (G.R.); (E.M.); (M.S.); (P.L.)
| | - Matteo Finizio
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy; (G.R.); (E.M.); (M.S.); (P.L.)
| | - Massimo Serra
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy; (G.R.); (E.M.); (M.S.); (P.L.)
| | - Pasquale Linciano
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy; (G.R.); (E.M.); (M.S.); (P.L.)
| | - Simona Collina
- Department of Drug Sciences, University of Pavia, Viale Taramelli 12, 27100 Pavia, Italy; (G.R.); (E.M.); (M.S.); (P.L.)
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4
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Zvintzou E, Xepapadaki E, Skroubis G, Mparnia V, Giannatou K, Benabdellah K, Kypreos KE. High-Density Lipoprotein in Metabolic Disorders and Beyond: An Exciting New World Full of Challenges and Opportunities. Pharmaceuticals (Basel) 2023; 16:855. [PMID: 37375802 DOI: 10.3390/ph16060855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Revised: 05/17/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
High-density lipoprotein (HDL) is an enigmatic member of the plasma lipid and lipoprotein transport system, best known for its ability to promote the reverse cholesterol efflux and the unloading of excess cholesterol from peripheral tissues. More recently, data in experimental mice and humans suggest that HDL may play important novel roles in other physiological processes associated with various metabolic disorders. Important parameters in the HDL functions are its apolipoprotein and lipid content, further reinforcing the principle that HDL structure defines its functionality. Thus, based on current evidence, low levels of HDL-cholesterol (HDL-C) or dysfunctional HDL particles contribute to the development of metabolic diseases such as morbid obesity, type 2 diabetes mellitus, and nonalcoholic fatty liver disease. Interestingly, low levels of HDL-C and dysfunctional HDL particles are observed in patients with multiple myeloma and other types of cancer. Therefore, adjusting HDL-C levels within the optimal range and improving HDL particle functionality is expected to benefit such pathological conditions. The failure of previous clinical trials testing various HDL-C-raising pharmaceuticals does not preclude a significant role for HDL in the treatment of atherosclerosis and related metabolic disorders. Those trials were designed on the principle of "the more the better", ignoring the U-shape relationship between HDL-C levels and morbidity and mortality. Thus, many of these pharmaceuticals should be retested in appropriately designed clinical trials. Novel gene-editing-based pharmaceuticals aiming at altering the apolipoprotein composition of HDL are expected to revolutionize the treatment strategies, improving the functionality of dysfunctional HDL.
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Affiliation(s)
- Evangelia Zvintzou
- Department of Pharmacology, School of Medicine, University of Patras, Rio Achaias, 26500 Patras, Greece
| | - Eva Xepapadaki
- Department of Pharmacology, School of Medicine, University of Patras, Rio Achaias, 26500 Patras, Greece
| | - George Skroubis
- Morbid Obesity Unit, Department of Surgery, School of Medicine, University of Patras, Rio Achaias, 26500 Patras, Greece
| | - Victoria Mparnia
- Department of Pharmacology, School of Medicine, University of Patras, Rio Achaias, 26500 Patras, Greece
| | - Katerina Giannatou
- Department of Pharmacology, School of Medicine, University of Patras, Rio Achaias, 26500 Patras, Greece
| | - Karim Benabdellah
- Department of Genomic Medicine, Pfizer-University of Granada-Andalusian Regional Government Centre for Genomics and Oncological Research (GENYO), PTS, Avda. de la Ilustración 114, 18016 Granada, Spain
| | - Kyriakos E Kypreos
- Department of Pharmacology, School of Medicine, University of Patras, Rio Achaias, 26500 Patras, Greece
- Department of Life Sciences, School of Sciences, European University Cyprus, 2404 Nicosia, Cyprus
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5
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Bhale AS, Venkataraman K. Delineating the impact of pathogenic mutations on the conformational dynamics of HDL's vital protein ApoA1: a combined computational and molecular dynamic simulation approach. J Biomol Struct Dyn 2023; 41:15661-15681. [PMID: 36943736 DOI: 10.1080/07391102.2023.2191131] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 03/09/2023] [Indexed: 03/23/2023]
Abstract
Apolipoprotein A1 (ApoA1), is the important component of high-density lipoproteins (HDL), that has key role in HDL biogenesis, cholesterol trafficking, and reverse cholesterol transport (RCT). Non-synonymous Single Nucleotide Polymorphisms (nsSNPs) in ApoA1 have been linked to cardiovascular diseases and amyloidosis as they alter the protein's native structure and function. Therefore in this study, we attempted to understand the molecular pathogenicity profile of nsSNPs of ApoA1 using various computational approaches. We used state-of-the-art computational methods to thoroughly investigate the 295 ApoA1 nsSNPs at sequence and structural levels. Seven nsSNPs (L13R, L84R, L84P, L99P, R173P, L187P, and L238P) out of 295 were classified as the most deleterious and destabilizing. In order to estimate the effect of such destabilizing mutations on the protein conformation, all-atom molecular dynamics simulations (MDS) of ApoA1 wild-type (WT), L99P and R173P for 100 ns, was carried out using GROMACS 5.0.1 package. The MD simulation investigation revealed significant structural alterations in L99P and R173P. In addition, they had changed principal component analysis and electrostatic surface potential, decreased structural compactness, and intramolecular hydrogen bonds, which supported the rationale underpinning ApoA1 dysfunction with such mutations. This work sheds light on ApoA1 dysfunction due to single amino acid alterations, and offers new insight into the molecular basis of ApoA1-related diseases progression.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Aishwarya Sudam Bhale
- Centre for Bio-Separation Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
| | - Krishnan Venkataraman
- Centre for Bio-Separation Technology, Vellore Institute of Technology, Vellore, Tamil Nadu, India
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6
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Burdick JP, Basi RS, Burns KS, Weers PMM. The role of C-terminal ionic residues in self-association of apolipoprotein A-I. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2023; 1865:184098. [PMID: 36481181 DOI: 10.1016/j.bbamem.2022.184098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 11/15/2022] [Accepted: 11/27/2022] [Indexed: 12/12/2022]
Abstract
Apolipoprotein A-I (apoA-I) is the main protein of high-density lipoprotein and is comprised of a helical bundle domain and a C-terminal (CT) domain encompassing the last ~65 amino acid residues of the 243-residue protein. The CT domain contains three putative helices (helix 8, 9, and 10) and is critical for initiating lipid binding and harbors sites that mediate self-association of the lipid-free protein. Three lysine residues reside in helix-8 (K195, 206, 208), and three in helix-10 (K226, 238, 239). To determine the role of each CT lysine residue in apoA-I self-association, single, double and triple lysine to glutamine mutants were engineered via site-directed mutagenesis. Circular dichroism and chemical denaturation analysis revealed all mutants retained their structural integrity. Chemical crosslinking and size-exclusion chromatography showed a small effect on self-association when helix-8 lysine residues were changed into glutamine. In contrast, mutation of the three helix-10 lysine residues resulted in a predominantly monomeric protein and K226 was identified as a critical residue. When helix-10 glutamate residues 223, 234, or 235 were substituted with glutamine, reduced self-association was observed similar to that of the helix-10 lysine variants, suggesting ionic interactions between these residues. Thus, helix-10 is a critical part of apoA-I mediating self-association, and disruption of ionic interactions changes apoA-I from an oligomeric state into a monomer. Since the helix-10 triple mutant solubilized phospholipid vesicles at higher rates compared to wild-type apoA-I, this indicates monomeric apoA-I is more potent in lipid binding, presumably because helix-10 is fully accessible to interact with lipids.
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Affiliation(s)
- John P Burdick
- Department of Chemistry and Biochemistry, California State University Long Beach, CA 90840, USA
| | - Rohin S Basi
- Department of Chemistry and Biochemistry, California State University Long Beach, CA 90840, USA
| | - Kaitlyn S Burns
- Department of Chemistry and Biochemistry, California State University Long Beach, CA 90840, USA
| | - Paul M M Weers
- Department of Chemistry and Biochemistry, California State University Long Beach, CA 90840, USA.
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7
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Cyclodextrin boostered-high density lipoprotein for antiatherosclerosis by regulating cholesterol efflux and efferocytosis. Carbohydr Polym 2022; 292:119632. [DOI: 10.1016/j.carbpol.2022.119632] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/07/2022] [Accepted: 05/14/2022] [Indexed: 02/05/2023]
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8
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On the Aggregation of Apolipoprotein A-I. Int J Mol Sci 2022; 23:ijms23158780. [PMID: 35955915 PMCID: PMC9369196 DOI: 10.3390/ijms23158780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Revised: 07/30/2022] [Accepted: 08/02/2022] [Indexed: 11/17/2022] Open
Abstract
In vivo, apolipoprotein A-I (ApoA-I) is commonly found together with lipids in so-called lipoprotein particles. The protein has also been associated with several diseases—such as atherosclerosis and amyloidosis—where insoluble aggregates containing ApoA-I are deposited in various organs or arteries. The deposited ApoA-I has been found in the form of amyloid fibrils, suggesting that amyloid formation may be involved in the development of these diseases. In the present study we investigated ApoA-I aggregation into amyloid fibrils and other aggregate morphologies. We studied the aggregation of wildtype ApoA-I as well as a disease-associated mutant, ApoA-I K107Δ, under different solution conditions. The aggregation was followed using thioflavin T fluorescence intensity. For selected samples the aggregates formed were characterized in terms of size, secondary structure content, and morphology using circular dichroism spectroscopy, dynamic light scattering, atomic force microscopy and cryo transmission electron microscopy. We find that ApoA-I may form globular protein-only condensates, in which the α-helical conformation of the protein is retained. The protein in its unmodified form appears resistant to amyloid formation; however, the conversion into amyloid fibrils rich in β-sheet is facilitated by oxidation or mutation. In particular, the K107Δ mutant shows higher amyloid formation propensity, and the end state appears to be a co-existence of β-sheet rich amyloid fibrils and α-helix-rich condensates.
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9
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Chen L, Zhao ZW, Zeng PH, Zhou YJ, Yin WJ. Molecular mechanisms for ABCA1-mediated cholesterol efflux. Cell Cycle 2022; 21:1121-1139. [PMID: 35192423 PMCID: PMC9103275 DOI: 10.1080/15384101.2022.2042777] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The maintenance of cellular cholesterol homeostasis is essential for normal cell function and viability. Excessive cholesterol accumulation is detrimental to cells and serves as the molecular basis of many diseases, such as atherosclerosis, Alzheimer's disease, and diabetes mellitus. The peripheral cells do not have the ability to degrade cholesterol. Cholesterol efflux is therefore the only pathway to eliminate excessive cholesterol from these cells. This process is predominantly mediated by ATP-binding cassette transporter A1 (ABCA1), an integral membrane protein. ABCA1 is known to transfer intracellular free cholesterol and phospholipids to apolipoprotein A-I (apoA-I) for generating nascent high-density lipoprotein (nHDL) particles. nHDL can accept more free cholesterol from peripheral cells. Free cholesterol is then converted to cholesteryl ester by lecithin:cholesterol acyltransferase to form mature HDL. HDL-bound cholesterol enters the liver for biliary secretion and fecal excretion. Although how cholesterol is transported by ABCA1 to apoA-I remains incompletely understood, nine models have been proposed to explain this effect. In this review, we focus on the current view of the mechanisms underlying ABCA1-mediated cholesterol efflux to provide an important framework for future investigation and lipid-lowering therapy.
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Affiliation(s)
- Lei Chen
- Department of Cardiology, The Second Affiliated Hospital of Hainan Medical University, Haikou, Hainan, China
| | - Zhen-Wang Zhao
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Peng-Hui Zeng
- Department of Clinical Laboratory, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Ying-Jie Zhou
- Department of Clinical Laboratory, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Wen-Jun Yin
- Department of Clinical Laboratory, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan, China,CONTACT Wen-Jun Yin Department of Clinical Laboratory, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan421001, China
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10
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Bedi S, Morris J, Shah A, Hart RC, Jerome WG, Aller SG, Tang C, Vaisar T, Bornfeldt KE, Segrest JP, Heinecke JW, Davidson WS. Conformational flexibility of apolipoprotein A-I amino- and carboxy-termini is necessary for lipid binding but not cholesterol efflux. J Lipid Res 2022; 63:100168. [PMID: 35051413 PMCID: PMC8953623 DOI: 10.1016/j.jlr.2022.100168] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 01/03/2022] [Accepted: 01/11/2022] [Indexed: 11/25/2022] Open
Abstract
Because of its critical role in HDL formation, significant efforts have been devoted to studying apolipoprotein A-I (APOA1) structural transitions in response to lipid binding. To assess the requirements for the conformational freedom of its termini during HDL particle formation, we generated three dimeric APOA1 molecules with their termini covalently joined in different combinations. The dimeric (d)-APOA1C-N mutant coupled the C-terminus of one APOA1 molecule to the N-terminus of a second with a short alanine linker, whereas the d-APOA1C-C and d-APOA1N-N mutants coupled the C-termini and the N-termini of two APOA1 molecules, respectively, using introduced cysteine residues to form disulfide linkages. We then tested the ability of these constructs to generate reconstituted HDL by detergent-assisted and spontaneous phospholipid microsolubilization methods. Using cholate dialysis, we demonstrate WT and all APOA1 mutants generated reconstituted HDL particles of similar sizes, morphologies, compositions, and abilities to activate lecithin:cholesterol acyltransferase. Unlike WT, however, the mutants were incapable of spontaneously solubilizing short chain phospholipids into discoidal particles. We found lipid-free d-APOA1C-N and d-APOA1N-N retained most of WT APOA1's ability to promote cholesterol efflux via the ATP binding cassette transporter A1, whereas d-APOA1C-C exhibited impaired cholesterol efflux. Our data support the double belt model for a lipid-bound APOA1 structure in nascent HDL particles and refute other postulated arrangements like the "double super helix." Furthermore, we conclude the conformational freedom of both the N- and C-termini of APOA1 is important in spontaneous microsolubilization of bulk phospholipid but is not critical for ABCA1-mediated cholesterol efflux.
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Affiliation(s)
- Shimpi Bedi
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Jamie Morris
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Amy Shah
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Rachel C Hart
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - W Gray Jerome
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Stephen G Aller
- Department of Pharmacology and Toxicology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chongren Tang
- Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| | - Tomas Vaisar
- Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| | - Karin E Bornfeldt
- Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| | - Jere P Segrest
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Jay W Heinecke
- Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH, USA.
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11
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Zvintzou E, Karampela DS, Vakka A, Xepapadaki E, Karavia EA, Hatziri A, Giannopoulou PC, Kypreos KE. High density lipoprotein in atherosclerosis and coronary heart disease: Where do we stand today? Vascul Pharmacol 2021; 141:106928. [PMID: 34695591 DOI: 10.1016/j.vph.2021.106928] [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: 05/14/2021] [Revised: 09/28/2021] [Accepted: 10/18/2021] [Indexed: 01/23/2023]
Abstract
Epidemiological studies during the last five years suggest that a relation between high density lipoprotein cholesterol (HDL-C) levels and the risk for cardiovascular disease (CVD) does exist but follows rather a "U-shaped" curve with an optimal range of HDL-C concentration between 40 and 70 mg/dl for men and 50-70 mg/dl for women. Moreover, as research in the field of lipoproteins progresses it becomes increasingly apparent that HDL particles possess different attributes and depending on their structural and functional characteristics, they may be "antiatherogenic" or "proatherogenic". In light of this information, it is highly doubtful that the choice of experimental drugs and the design of respective clinical trials that put the HDL-C raising hypothesis at test, were the most suitable. Here, we compile the existing literature on HDL, providing a critical up-to-date view that focuses on key data from the biochemistry, epidemiology and pharmacology of HDL, including data from clinical trials. We also discuss the most up-to-date information on the contribution of HDL structure and function to the prevention of atherosclerosis. We conclude by summarizing important differences between mouse models and humans, that may explain why pharmacological successes in mice turn out to be failures in humans.
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Affiliation(s)
- Evangelia Zvintzou
- University of Patras, School of Medicine, Department of Pharmacology, Rio Achaias, TK 26500, Greece
| | | | - Aggeliki Vakka
- University of Patras, School of Medicine, Department of Pharmacology, Rio Achaias, TK 26500, Greece
| | - Eva Xepapadaki
- University of Patras, School of Medicine, Department of Pharmacology, Rio Achaias, TK 26500, Greece
| | - Eleni A Karavia
- University of Patras, School of Medicine, Department of Pharmacology, Rio Achaias, TK 26500, Greece
| | - Aikaterini Hatziri
- University of Patras, School of Medicine, Department of Pharmacology, Rio Achaias, TK 26500, Greece
| | - Panagiota C Giannopoulou
- University of Patras, School of Medicine, Department of Pharmacology, Rio Achaias, TK 26500, Greece
| | - Kyriakos E Kypreos
- University of Patras, School of Medicine, Department of Pharmacology, Rio Achaias, TK 26500, Greece; European University Cyprus, Department of Life Sciences, School of Sciences, Nicosia, Cyprus.
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12
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Ohgita T, Furutani Y, Nakano M, Hattori M, Suzuki A, Nakagawa M, Naniwa S, Morita I, Oyama H, Nishitsuji K, Kobayashi N, Saito H. Novel conformation‐selective monoclonal antibodies against apoA‐I amyloid fibrils. FEBS J 2021. [DOI: 10.1111/febs.15487] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Takashi Ohgita
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Yuki Furutani
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Miyu Nakano
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Megumi Hattori
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Ayane Suzuki
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Miho Nakagawa
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
| | - Sera Naniwa
- Department of Bioanalytical Chemistry Kobe Pharmaceutical University Japan
| | - Izumi Morita
- Department of Bioanalytical Chemistry Kobe Pharmaceutical University Japan
| | - Hiroyuki Oyama
- Department of Bioanalytical Chemistry Kobe Pharmaceutical University Japan
| | | | - Norihiro Kobayashi
- Department of Bioanalytical Chemistry Kobe Pharmaceutical University Japan
| | - Hiroyuki Saito
- Department of Biophysical Chemistry Kyoto Pharmaceutical University Japan
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13
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Tárraga WA, Falomir-Lockhart LJ, Garda HA, González MC. Analysis of pyrene-labelled apolipoprotein A-I oligomerization in solution: Spectra deconvolution and changes in P-value and excimer formation. Arch Biochem Biophys 2021; 699:108748. [PMID: 33444627 DOI: 10.1016/j.abb.2020.108748] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2020] [Revised: 12/22/2020] [Accepted: 12/28/2020] [Indexed: 11/15/2022]
Abstract
ApoA-I is the main protein of HDL which has anti-atherogenic properties attributed to reverse cholesterol transport. It shares with other exchangeable apolipoproteins a high level of structural plasticity. In the lipid-free state, the apolipoprotein amphipathic α-helices interact intra- and inter-molecularly, providing structural stabilization by a complex self-association mechanism. In this study, we employed a multi-parametric fluorescent probe to study the self-association of apoA-I. We constructed six single cysteine mutants spanning positions along three helices: F104C, K107C (H4), K133C, L137C (H5), F225C and K226C (H10); and labelled them with N-Maleimide Pyrene. Taking advantage of its spectral properties, namely formation of an excited dimer (excimer) and polarity-dependent changes in its fluorescence fine structure (P-value), we monitored the apoA-I self-association in its lipid-free form as a function of its concentration. Interactions in helices H5 (K133C) and H10 (F225C and K226C) were highlighted by excimer emission; while polarity changes were reported in helix H4 (K107C), as well as in helices H5 and H10. Mathematical models were developed to enrich data analysis and estimate association constants (KA) and oligomeric species distribution. Furthermore, we briefly discuss the usefulness of the multi-parametric fluorescent probe to monitor different equilibria, even at a single labelling position. Results suggest that apoA-I self-association must be considered to fully understand its physiological roles. Particularly, some contacts that stabilize discoidal HDL particles seem to be already present in the lipid-free apoA-I oligomers.
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Affiliation(s)
- Wilson A Tárraga
- Instituto de Investigaciones Bioquímica de La Plata (INIBIOLP), Centro Científico Tecnológico-La Plata, Calle 60 y 120 s/n, 1900, La Plata, Argentina.
| | - Lisandro J Falomir-Lockhart
- Instituto de Investigaciones Bioquímica de La Plata (INIBIOLP), Centro Científico Tecnológico-La Plata, Calle 60 y 120 s/n, 1900, La Plata, Argentina; Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Calle 47 y 115 s/n, 1900, La Plata, Argentina.
| | - Horacio A Garda
- Instituto de Investigaciones Bioquímica de La Plata (INIBIOLP), Centro Científico Tecnológico-La Plata, Calle 60 y 120 s/n, 1900, La Plata, Argentina; Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120 s/n, 1900, La Plata, Argentina.
| | - Marina C González
- Instituto de Investigaciones Bioquímica de La Plata (INIBIOLP), Centro Científico Tecnológico-La Plata, Calle 60 y 120 s/n, 1900, La Plata, Argentina; Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120 s/n, 1900, La Plata, Argentina.
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14
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Ludovico ID, Gisonno RA, Gonzalez MC, Garda HA, Ramella NA, Tricerri MA. Understanding the role of apolipoproteinA-I in atherosclerosis. Post-translational modifications synergize dysfunction? Biochim Biophys Acta Gen Subj 2020; 1865:129732. [PMID: 32946930 DOI: 10.1016/j.bbagen.2020.129732] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 08/17/2020] [Accepted: 09/09/2020] [Indexed: 10/23/2022]
Abstract
BACKGROUND The identification of dysfunctional human apolipoprotein A-I (apoA-I) in atherosclerotic plaques suggests that protein structure and function may be hampered under a chronic pro inflammatory scenario. Moreover, the fact that natural mutants of this protein elicit severe cardiovascular diseases (CVD) strongly indicates that the native folding could shift due to the mutation, yielding a structure more prone to misfold or misfunction. To understand the events that determine the failure of apoA-I structural flexibility to fulfill its protective role, we took advantage of the study of a natural variant with a deletion of the residue lysine 107 (K107del) associated with atherosclerosis. METHODS Biophysical approaches, such as electrophoresis, fluorescence and spectroscopy were used to characterize proteins structure and function, either in native conformation or under oxidation or intramolecular crosslinking. RESULTS K107del structure was more flexible than the protein with the native sequence (Wt) but interactions with artificial membranes were preserved. Instead, structural restrictions by intramolecular crosslinking impaired the Wt and K107del lipid solubilization function. In addition, controlled oxidation decreased the yield of the native dimer conformation for both variants. CONCLUSIONS We conclude that even though mutations may alter protein structure and spatial arrangement, the highly flexible conformation compensates the mild shift from the native folding. Instead, post translational apoA-I modifications (probably chronic and progressive) are required to raise a protein conformation with significant loss of function and increased aggregation tendency. GENERAL SIGNIFICANCE The results learnt from this variant strength a close association between amyloidosis and atherosclerosis.
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Affiliation(s)
- Ivo Díaz Ludovico
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Argentina; Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, La Plata CP 1900, Argentina
| | - Romina A Gisonno
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Argentina; Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, La Plata CP 1900, Argentina
| | - Marina C Gonzalez
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Argentina; Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, La Plata CP 1900, Argentina
| | - Horacio A Garda
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Argentina; Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, La Plata CP 1900, Argentina
| | - Nahuel A Ramella
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Argentina; Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, La Plata CP 1900, Argentina.
| | - M Alejandra Tricerri
- Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP), Argentina; Facultad de Ciencias Médicas, Universidad Nacional de La Plata, Calle 60 y 120, La Plata CP 1900, Argentina.
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15
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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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16
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Gaddi GM, Gisonno RA, Rosú SA, Curto LM, Prieto ED, Schinella GR, Finarelli GS, Cortez MF, Bauzá L, Elías EE, Ramella NA, Tricerri MA. Structural analysis of a natural apolipoprotein A-I variant (L60R) associated with amyloidosis. Arch Biochem Biophys 2020; 685:108347. [DOI: 10.1016/j.abb.2020.108347] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 03/12/2020] [Accepted: 03/14/2020] [Indexed: 01/11/2023]
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17
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First eight residues of apolipoprotein A-I mediate the C-terminus control of helical bundle unfolding and its lipidation. PLoS One 2020; 15:e0221915. [PMID: 31945064 PMCID: PMC6964839 DOI: 10.1371/journal.pone.0221915] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 12/30/2019] [Indexed: 11/23/2022] Open
Abstract
The crystal structure of a C-terminal deletion of apolipoprotein A-I (apoA1) shows a large helical bundle structure in the amino half of the protein, from residues 8 to 115. Using site directed mutagenesis, guanidine or thermal denaturation, cell free liposome clearance, and cellular ABCA1-mediated cholesterol efflux assays, we demonstrate that apoA1 lipidation can occur when the thermodynamic barrier to this bundle unfolding is lowered. The absence of the C-terminus renders the bundle harder to unfold resulting in loss of apoA1 lipidation that can be reversed by point mutations, such as Trp8Ala, and by truncations as short as 8 residues in the amino terminus, both of which facilitate helical bundle unfolding. Locking the bundle via a disulfide bond leads to loss of apoA1 lipidation. We propose a model in which the C-terminus acts on the N-terminus to destabilize this helical bundle. Upon lipid binding to the C-terminus, Trp8 is displaced from its interaction with Phe57, Arg61, Leu64, Val67, Phe71, and Trp72 to destabilize the bundle. However, when the C-terminus is deleted, Trp8 cannot be displaced, the bundle cannot unfold, and apoA1 cannot be lipidated.
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18
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Sharma S, Yadav S, Chandiok K, Sharma RS, Mishra V, Saraswathy KN. Protein signatures linking history of miscarriages and metabolic syndrome: a proteomic study among North Indian women. PeerJ 2019; 7:e6321. [PMID: 30783564 PMCID: PMC6378092 DOI: 10.7717/peerj.6321] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2018] [Accepted: 12/20/2018] [Indexed: 12/14/2022] Open
Abstract
Background Metabolic syndrome (MeS), a constellation of metabolic adversities, and history of miscarriage make women at a higher risk for cardiovascular diseases (CVDs). However, molecular evidence indicating a link between the two phenotypes (history of miscarriage and MeS) among women would offer an opportunity to predict the risk factor for CVDs at an early stage. Thus, the present retrospective study attempts to identify the proteins signatures (if any) to understand the connection between the history of miscarriage and MeS. Methods Age-matched 80 pre-menopausal women who were not on any medical intervention or drugs were recruited from a Mendelian population of the same gene pool. Recruited women were classified into four groups—(a) Group A—absolute cases with history of miscarriage and MeS, (b) Group B—absolute controls without any history of miscarriage and MeS, (c) Group C—cases with MeS but lack any history of miscarriage, (d) Group D—cases with history of miscarriage but lack MeS. Differentially expressed proteins in plasma samples of women from four groups were identified using 2-D gel electrophoresis and mass spectrometry. Results Three case groups (A, C, and D) showed 18 differentially expressed proteins. Nearly 60% of proteins (11/18) were commonly dysregulated in Group C (only with MeS) and Group D (only with miscarriage history). Nearly 40% of proteins (7/18) were commonly dysregulated in the three case groups (Groups A, C, and D), indicating a shared pathophysiology. Four proteins were exclusive but shared by case groups C and D indicating the independent routes for CVDs through MeS or miscarriages. In absolute cases, transthyretin (TTR) showed exclusive upregulation, which was further validated by Western blotting and ELISA. Networking analyses showed the strong association of TTR with haptoglobin, transferrin and ApoA1 hinting toward a cross-talk among these proteins which could be a cause or an effect of TTR upregulation. Conclusion The study provides evidence for molecular link between the history of miscarriage and MeS through a putative role of TTR. However, longitudinal follow-up studies with larger sample size would further help to demonstrate the significance of TTR and other targeted proteins in risk stratification and the onset of CVDs.
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Affiliation(s)
- Saurabh Sharma
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi, India
| | - Suniti Yadav
- Molecular Anthropology Laboratory, Department of Anthropology, University of Delhi, Delhi, India
| | - Ketaki Chandiok
- Molecular Anthropology Laboratory, Department of Anthropology, University of Delhi, Delhi, India
| | - Radhey Shyam Sharma
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi, India
| | - Vandana Mishra
- Bioresources & Environmental Biotechnology Laboratory, Department of Environmental Studies, University of Delhi, Delhi, India
| | - Kallur Nava Saraswathy
- Molecular Anthropology Laboratory, Department of Anthropology, University of Delhi, Delhi, India
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19
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Ray A, Ghosh A, Chakraborty R, Upadhyay SK, Maiti S, Sengupta S, Thukral L. Specific Cholesterol Binding Drives Drastic Structural Alterations in Apolipoprotein A1. J Phys Chem Lett 2018; 9:6060-6065. [PMID: 30256643 DOI: 10.1021/acs.jpclett.8b02042] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Proteins typically adopt a multitude of flexible and rapidly interconverting conformers, many of which are governed by specific protein interaction domains. Whereas disc-shaped oligomeric HDL and its major protein component ApoA1 have been the focus of several investigations, the structural properties of monomeric ApoA1 remain poorly understood. Using tens of independent molecular simulations (>50 μs), we reveal that ApoA1 adopts a compact conformation. Upon the addition of a physiological concentration of cholesterol to ApoA1, the monomeric protein spontaneously formed a circular conformation. Remarkably, these drastic structural perturbations are driven by a specific cholesterol binding site at the C-terminal and a novel cholesterol binding site at the N-terminal. We propose a mechanism whereby ApoA1 opens in a stagewise manner and mutating the N-terminal binding site destroys the open "belt-shaped" topology. Complementary experiments confirm that the structural changes are induced by specific association of cholesterol with ApoA1, not by the nonspecific hydrophobic effect.
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Affiliation(s)
- Arjun Ray
- CSIR-Institute of Genomics and Integrative Biology , South Campus, Mathura Road , New Delhi 110 025 , India
- Academy of Scientific and Innovative Research (AcSIR) , CSIR- Institute of Genomics and Integrative Biology , Mathura Road Campus , New Delhi 110025 , India
| | - Asmita Ghosh
- CSIR-Institute of Genomics and Integrative Biology , South Campus, Mathura Road , New Delhi 110 025 , India
- Academy of Scientific and Innovative Research (AcSIR) , CSIR- Institute of Genomics and Integrative Biology , Mathura Road Campus , New Delhi 110025 , India
| | - Rahul Chakraborty
- CSIR-Institute of Genomics and Integrative Biology , South Campus, Mathura Road , New Delhi 110 025 , India
- Academy of Scientific and Innovative Research (AcSIR) , CSIR- Institute of Genomics and Integrative Biology , Mathura Road Campus , New Delhi 110025 , India
| | - Santosh Kumar Upadhyay
- CSIR-Institute of Genomics and Integrative Biology , South Campus, Mathura Road , New Delhi 110 025 , India
| | - Souvik Maiti
- CSIR-Institute of Genomics and Integrative Biology , South Campus, Mathura Road , New Delhi 110 025 , India
- Academy of Scientific and Innovative Research (AcSIR) , CSIR- Institute of Genomics and Integrative Biology , Mathura Road Campus , New Delhi 110025 , India
| | - Shantanu Sengupta
- CSIR-Institute of Genomics and Integrative Biology , South Campus, Mathura Road , New Delhi 110 025 , India
- Academy of Scientific and Innovative Research (AcSIR) , CSIR- Institute of Genomics and Integrative Biology , Mathura Road Campus , New Delhi 110025 , India
| | - Lipi Thukral
- CSIR-Institute of Genomics and Integrative Biology , South Campus, Mathura Road , New Delhi 110 025 , India
- Academy of Scientific and Innovative Research (AcSIR) , CSIR- Institute of Genomics and Integrative Biology , Mathura Road Campus , New Delhi 110025 , India
- Interdisciplinary Center for Scientific Computing , University of Heidelberg , Im Neuenheimer Feld 205 , 69120 Heidelberg , Germany
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20
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Wilson CJ, Das M, Jayaraman S, Gursky O, Engen JR. Effects of Disease-Causing Mutations on the Conformation of Human Apolipoprotein A-I in Model Lipoproteins. Biochemistry 2018; 57:4583-4596. [PMID: 30004693 DOI: 10.1021/acs.biochem.8b00538] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Plasma high-density lipoproteins (HDLs) are protein-lipid nanoparticles that transport lipids and protect against atherosclerosis. Human apolipoprotein A-I (apoA-I) is the principal HDL protein whose mutations can cause either aberrant lipid metabolism or amyloid disease. Hydrogen-deuterium exchange (HDX) mass spectrometry (MS) was used to study the apoA-I conformation in model discoidal lipoproteins similar in size to large plasma HDL. We examined how point mutations associated with hereditary amyloidosis (F71Y and L170P) or atherosclerosis (L159R) influence the local apoA-I conformation in model lipoproteins. Unlike other apoA-I forms, the large particles showed minimal conformational heterogeneity, suggesting a fully extended protein conformation. Mutation-induced structural perturbations in lipid-bound protein were attenuated compared to the free protein and indicated close coupling between the two belt-forming apoA-I molecules. These perturbations propagated to distant lipoprotein sites, either increasing or decreasing their protection. This HDX MS study of large model HDL, compared with previous studies of smaller particles, ascertained that apoA-I's central region helps accommodate the protein conformation to lipoproteins of various sizes. This study also reveals that the effects of mutations on lipoprotein conformational dynamics are much weaker than those in a lipid-free protein. Interestingly, the mutation-induced perturbations propagate to distant sites nearly 10 nm away and alter their protection in ways that cannot be predicted from the lipoprotein structure and stability. We propose that long-range mutational effects are mediated by both protein and lipid and can influence lipoprotein functionality.
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Affiliation(s)
- Christopher J Wilson
- Department of Chemistry and Chemical Biology , Northeastern University , 360 Huntington Avenue , Boston , Massachusetts 02115 , United States
| | - Madhurima Das
- Department of Physiology & Biophysics , Boston University School of Medicine , 700 Albany Street , Boston , Massachusetts 02118 , United States
| | - Shobini Jayaraman
- Department of Physiology & Biophysics , Boston University School of Medicine , 700 Albany Street , Boston , Massachusetts 02118 , United States
| | - Olga Gursky
- Department of Physiology & Biophysics , Boston University School of Medicine , 700 Albany Street , Boston , Massachusetts 02118 , United States.,Amyloidosis Research Center , Boston University School of Medicine , Boston , Massachusetts 02118 , United States
| | - John R Engen
- Department of Chemistry and Chemical Biology , Northeastern University , 360 Huntington Avenue , Boston , Massachusetts 02115 , United States
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21
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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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22
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Fuentes LA, Beck WHJ, Tsujita M, Weers PMM. Charged Residues in the C-Terminal Domain of Apolipoprotein A-I Modulate Oligomerization. Biochemistry 2018; 57:2200-2210. [PMID: 29578333 DOI: 10.1021/acs.biochem.7b01052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Charged residues of the C-terminal domain of human apolipoprotein A-I (apoA-I) were targeted by site-directed mutagenesis. A series of mutant proteins was engineered in which lysine residues (Lys 195, 206, 208, 226, 238, and 239) or glutamate residues (Glu 234 and 235) were replaced by glutamine. The amino acid substitutions did not result in changes in secondary structure content or protein stability. Cross-linking and size-exclusion chromatography showed that the mutations resulted in reduced self-association, generating a predominantly monomeric apoA-I when five or six lysine residues were substituted. The rate of phosphatidylcholine vesicle solubilization was enhanced for all variants, with approximately a threefold rate enhancement for apoA-I lacking Lys 206, 208, 238, and 239, or Glu 234 and 235. Single or double mutations did not change the ability to protect lipolyzed low density lipoprotein from aggregation, but variants lacking >4 lysine residues were less effective in preventing lipoprotein aggregation. ApoA-I mediated cellular lipid efflux from wild-type mice macrophage foam cells was decreased for the variant with five lysine mutations. However, this protein was more effective in releasing cellular phosphatidylcholine and sphingomyelin from Abca1-null mice macrophage foam cells. This suggests that the mutations caused changes in the interaction with ABCA1 transporters and that membrane microsolubilization was primarily responsible for lipid efflux in cells lacking ABCA1. Taken together, this study indicates that ionic interactions in the C-terminal domain of apoA-I favor self-association and that monomeric apoA-I is more active in solubilizing phospholipid bilayers.
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Affiliation(s)
- Lukas A Fuentes
- Department of Chemistry and Biochemistry , California State University Long Beach , Long Beach , California 90840 , United States
| | - Wendy H J Beck
- Department of Chemistry and Biochemistry , California State University Long Beach , Long Beach , California 90840 , United States
| | - Maki Tsujita
- Department of Biochemistry , Nagoya City University Graduate School of Medical Sciences , Aichi 467-8601 , Japan
| | - Paul M M Weers
- Department of Chemistry and Biochemistry , California State University Long Beach , Long Beach , California 90840 , United States
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23
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Proteomic Analysis of Thermal Regulation of Small Yellow Follicles in Broiler-Type Taiwan Country Chickens. J Poult Sci 2018; 55:120-136. [PMID: 32055165 PMCID: PMC6756493 DOI: 10.2141/jpsa.0170069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 08/03/2017] [Indexed: 11/21/2022] Open
Abstract
Heat stress hampers egg production and lowers fertility in layers. This study investigated global protein abundance in the small yellow follicles (SYFs, 6–8 mm diameter) of a broiler-type strain of Taiwan country chickens (TCCs) under acute heat stress. Twelve 30-week-old TCC hens were allocated to a control group maintained at 25°C, and to three acute heat-stressed groups subjected to 38°C for 2 h without recovery, with 2-h recovery, or with 6-h recovery. Two-dimensional difference gel electrophoresis analysis identified 119 significantly differentially expressed proteins after acute heat exposure. Gene ontology analysis revealed that most of these proteins are involved in molecular binding (34%), catalytic activity (23%), and structural molecule activity (11%), and participate in metabolic processes (20%), cellular processes (20%), and cellular component organization or biogenesis (11%). Proteins associated with stress response and survival (HSP25, HSP47, HSP70, HSC70, HSPA9), cytoskeleton remodeling, mitochondrial metabolic process of ATP production, antioxidative defense (peroxiredoxin-6), cargo lipid export and delivery (vitellogenin, apolipoprotein B and A1), and toxin/metabolite clearance and delivery (albumin) were upregulated after acute heat stress in the SYFs of TCCs. No overt cell death and atresia were observed in SYFs after acute heat stress. Collectively, these responses may represent a protective mechanism to maintain follicle cell integrity and survival, thereby ensuring a sufficient pool of SYFs for selection into the ovulation hierarchy for successful egg production.
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Korber M, Klein I, Daum G. Steryl ester synthesis, storage and hydrolysis: A contribution to sterol homeostasis. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:1534-1545. [DOI: 10.1016/j.bbalip.2017.09.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 08/25/2017] [Accepted: 09/05/2017] [Indexed: 02/01/2023]
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Melchior JT, Walker RG, Cooke AL, Morris J, Castleberry M, Thompson TB, Jones MK, Song HD, Rye KA, Oda MN, Sorci-Thomas MG, Thomas MJ, Heinecke JW, Mei X, Atkinson D, Segrest JP, Lund-Katz S, Phillips MC, Davidson WS. A consensus model of human apolipoprotein A-I in its monomeric and lipid-free state. Nat Struct Mol Biol 2017; 24:1093-1099. [PMID: 29131142 PMCID: PMC5749415 DOI: 10.1038/nsmb.3501] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2017] [Accepted: 10/06/2017] [Indexed: 11/09/2022]
Abstract
Apolipoprotein (apo)A-I is an organizing scaffold protein that is critical to high-density lipoprotein (HDL) structure and metabolism, probably mediating many of its cardioprotective properties. However, HDL biogenesis is poorly understood, as lipid-free apoA-I has been notoriously resistant to high-resolution structural study. Published models from low-resolution techniques share certain features but vary considerably in shape and secondary structure. To tackle this central issue in lipoprotein biology, we assembled a team of structural biologists specializing in apolipoproteins and set out to build a consensus model of monomeric lipid-free human apoA-I. Combining novel and published cross-link constraints, small-angle X-ray scattering (SAXS), hydrogen-deuterium exchange (HDX) and crystallography data, we propose a time-averaged model consistent with much of the experimental data published over the last 40 years. The model provides a long-sought platform for understanding and testing details of HDL biogenesis, structure and function.
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Affiliation(s)
- John T Melchior
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Ryan G Walker
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Allison L Cooke
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Jamie Morris
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Mark Castleberry
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
| | - Thomas B Thompson
- Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio, USA
| | - Martin K Jones
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Hyun D Song
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Kerry-Anne Rye
- School of Medical Sciences, Faculty of Medicine, University of New South Wales, Sydney, New South Wales, Australia
| | - Michael N Oda
- Children's Hospital Oakland Research Institute, Oakland, California, USA
| | - Mary G Sorci-Thomas
- Department of Medicine, Section on Endocrinology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Michael J Thomas
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, USA
| | - Jay W Heinecke
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Xiaohu Mei
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - David Atkinson
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts, USA
| | - Jere P Segrest
- Department of Medicine, Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Sissel Lund-Katz
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Michael C Phillips
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio, USA
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26
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Synchrotron radiation circular dichroism spectroscopy reveals structural divergences in HDL-bound apoA-I variants. Sci Rep 2017; 7:13540. [PMID: 29051568 PMCID: PMC5648894 DOI: 10.1038/s41598-017-13878-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 10/03/2017] [Indexed: 12/15/2022] Open
Abstract
Apolipoprotein A-I (apoA-I) in high-density lipoprotein (HDL) provides cardiovascular protection. Synchrotron radiation circular dichroism (SRCD) spectroscopy was used to analyze the dynamic solution structure of the apoA-I protein in the apo- and HDL-states and the protein structure conversion in HDL formation. Wild-type apoA-I protein was compared to human variants that either are protective (R173C, Milano) or lead to increased risk for ischaemic heart disease (A164S). Comparable secondary structure distributions in the HDL particles, including significant levels of beta strand/turn, were observed. ApoA-I Milano in HDL displayed larger size heterogeneity, increased protein flexibility, and an altered lipid-binding profile, whereas the apoA-I A164S in HDL showed decrease thermal stability, potentially linking the intrinsic HDL propensities of the variants to disease risk.
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Flow Field-Flow Fractionation with Mass Spectrometry for Top-Down and Bottom-Up Lipidomics. JOURNAL OF ANALYSIS AND TESTING 2017. [DOI: 10.1007/s41664-017-0027-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Expression of the C-terminal domain of human apolipoprotein A-I using a chimeric apolipoprotein. Protein Expr Purif 2017. [PMID: 28624493 DOI: 10.1016/j.pep.2017.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Human apolipoprotein A-I (apoA-I) is the most abundant protein in high-density lipoprotein, an anti-atherogenic lipid-protein complex responsible for reverse cholesterol transport. The protein is composed of an N-terminal helix bundle domain, and a small C-terminal (CT) domain. To facilitate study of CT-apoA-I, a novel strategy was employed to produce this small domain in a bacterial expression system. A protein construct was designed of insect apolipophorin III (apoLp-III) and residues 179-243 of apoA-I, with a unique methionine residue positioned between the two proteins and an N-terminal His-tag to facilitate purification. The chimera was expressed in E. coli, purified by Ni-affinity chromatography, and cleaved by cyanogen bromide. SDS-PAGE revealed the presence of three proteins with masses of 7 kDa (CT-apoA-I), 18 kDa (apoLp-III), and a minor 26 kDa band of uncleaved chimera. The digest was reloaded on the Ni-affinity column to bind apoLp-III and uncleaved chimera, while CT-apoA-I was washed from the column and collected. Alternatively, CT-apoA-I was isolated from the digest by reversed-phase HPLC. CT-apoA-I was α-helical, highly effective in solubilizing phospholipid vesicles and disaggregating LPS micelles. However, CT-apoA-I was less active compared to full-length apoA-I in protecting lipolyzed low density lipoproteins from aggregating, and disrupting phosphatidylglycerol bilayer vesicles. Thus the novel expression system produced mg quantities of functional CT-apoA-I, facilitating structural and functional studies of this critical domain of apoA-I.
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Tan XT, Amran FB, Thayan R, Ahmad N, Jaafar R, Haron R, Abdullah R, bin Shamsuddin SR, Md. Riffin NSB, Abdul-Rahman PS. Potential serum biomarkers associated with mild and severe leptospirosis infection: A cohort study in the Malaysian population. Electrophoresis 2017; 38:2141-2149. [DOI: 10.1002/elps.201600471] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2016] [Revised: 04/22/2017] [Accepted: 05/12/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Xue Ting Tan
- Bacteriology Unit; Institute for Medical Research; Kuala Lumpur Malaysia
- Department of Molecular Medicine, Faculty of Medicine; University of Malaya; Kuala Lumpur Malaysia
| | - Fairuz binti Amran
- Bacteriology Unit; Institute for Medical Research; Kuala Lumpur Malaysia
| | - Ravindran Thayan
- Virology Unit; Institute for Medical Research; Kuala Lumpur Malaysia
| | - Norazah Ahmad
- Bacteriology Unit; Institute for Medical Research; Kuala Lumpur Malaysia
| | - Roslinda Jaafar
- Microbiology Unit; Hospital Sultan Haji Ahmad Shah; Pahang Malaysia
| | - Rahimah Haron
- Department of Anesthesiology; Hospital Sultan Haji Ahmad Shah; Pahang Malaysia
| | - Rafidah Abdullah
- Department of Medical; Hospital Sultan Haji Ahmad Shah; Pahang Malaysia
| | | | | | - Puteri Shafinaz Abdul-Rahman
- Department of Molecular Medicine, Faculty of Medicine; University of Malaya; Kuala Lumpur Malaysia
- University of Malaya Centre for Proteomics Research; University of Malaya; Kuala Lumpur Malaysia
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Ding H, Fox I, Patil R, Galstyan A, Black KL, Ljubimova JY, Holler E. Polymalic Acid Tritryptophan Copolymer Interacts with Lipid Membrane Resulting in Membrane Solubilization. JOURNAL OF NANOMATERIALS 2017; 2017:4238697. [PMID: 29081792 PMCID: PMC5656384 DOI: 10.1155/2017/4238697] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Anionic polymers with membrane permeation functionalities are highly desirable for secure cytoplasmic drug delivery. We have developed tritryptophan containing copolymer (P/WWW) of polymalic acid (PMLA) that permeates membranes by a mechanism different from previously described PMLA copolymers of trileucine (P/LLL) and leucine ethyl ester (P/LOEt) that use the "barrel stave" and "carpet" mechanism, respectively. The novel mechanism leads to solubilization of membranes by forming copolymer "belts" around planar membrane "packages." The formation of such packages is supported by results obtained from studies including size-exclusion chromatography, confocal microscopy, and fluorescence energy transfer. According to this "belt" mechanism, it is hypothesized that P/WWW first attaches to the membrane surface. Subsequently the hydrophobic tryptophan side chains translocate into the periphery and insert into the lipid bilayer thereby cutting the membrane into packages. The reaction is driven by the high affinity between the tryptophan residues and lipid side chains resulting in a stable configuration. The formation of the membrane packages requires physical agitation suggesting that the success of the translocation depends on the fluidity of the membrane. It is emphasized that the "belt" mechanism could specifically function in the recognition of abnormal cells with high membrane fluidity and in response to hyperthermia.
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Affiliation(s)
- Hui Ding
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Irving Fox
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Rameshwar Patil
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Anna Galstyan
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Keith L. Black
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Julia Y. Ljubimova
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
| | - Eggehard Holler
- Department of Neurosurgery, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
- Institut für Biophysik und Physikalische Biochemie der Universität Regensburg, Regensburg, Germany
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31
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Horn JVC, Ellena RA, Tran JJ, Beck WHJ, Narayanaswami V, Weers PMM. Transfer of C-terminal residues of human apolipoprotein A-I to insect apolipophorin III creates a two-domain chimeric protein with enhanced lipid binding activity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2017; 1859:1317-1325. [PMID: 28434970 DOI: 10.1016/j.bbamem.2017.04.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Revised: 04/14/2017] [Accepted: 04/19/2017] [Indexed: 01/11/2023]
Abstract
Apolipophorin III (apoLp-III) is an insect apolipoprotein (18kDa) that comprises a single five-helix bundle domain. In contrast, human apolipoprotein A-I (apoA-I) is a 28kDa two-domain protein: an α-helical N-terminal domain (residues 1-189) and a less structured C-terminal domain (residues 190-243). To better understand the apolipoprotein domain organization, a novel chimeric protein was engineered by attaching residues 179 to 243 of apoA-I to the C-terminal end of apoLp-III. The apoLp-III/apoA-I chimera was successfully expressed and purified in E. coli. Western blot analysis and mass spectrometry confirmed the presence of the C-terminal domain of apoA-I within the chimera. While parent apoLp-III did not self-associate, the chimera formed oligomers similar to apoA-I. The chimera displayed a lower α-helical content, but the stability remained similar compared to apoLp-III, consistent with the addition of a less structured domain. The chimera was able to solubilize phospholipid vesicles at a significantly higher rate compared to apoLp-III, approaching that of apoA-I. The chimera was more effective in protecting phospholipase C-treated low density lipoprotein from aggregation compared to apoLp-III. In addition, binding interaction of the chimera with phosphatidylglycerol vesicles and lipopolysaccharides was considerably improved compared to apoLp-III. Thus, addition of the C-terminal domain of apoA-I to apoLp-III created a two-domain protein, with self-association, lipid and lipopolysaccharide binding properties similar to apoA-I. The apoA-I like behavior of the chimera indicate that these properties are independent from residues residing in the N-terminal domain of apoA-I, and that they can be transferred from apoA-I to apoLp-III.
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Affiliation(s)
- James V C Horn
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840, United States
| | - Rachel A Ellena
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840, United States
| | - Jesse J Tran
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840, United States
| | - Wendy H J Beck
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840, United States
| | - Vasanthy Narayanaswami
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840, United States
| | - Paul M M Weers
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, CA 90840, United States.
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32
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Recio C, Maione F, Iqbal AJ, Mascolo N, De Feo V. The Potential Therapeutic Application of Peptides and Peptidomimetics in Cardiovascular Disease. Front Pharmacol 2017; 7:526. [PMID: 28111551 PMCID: PMC5216031 DOI: 10.3389/fphar.2016.00526] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Accepted: 12/19/2016] [Indexed: 12/11/2022] Open
Abstract
Cardiovascular disease (CVD) remains a leading cause of mortality and morbidity worldwide. Numerous therapies are currently under investigation to improve pathological cardiovascular complications, but yet, there have been very few new medications approved for intervention/treatment. Therefore, new approaches to treat CVD are urgently required. Attempts to prevent vascular complications usually involve amelioration of contributing risk factors and underlying processes such as inflammation, obesity, hyperglycaemia, or hypercholesterolemia. Historically, the development of peptides as therapeutic agents has been avoided by the Pharmaceutical industry due to their low stability, size, rate of degradation, and poor delivery. However, more recently, resurgence has taken place in developing peptides and their mimetics for therapeutic intervention. As a result, increased attention has been placed upon using peptides that mimic the function of mediators involved in pathologic processes during vascular damage. This review will provide an overview on novel targets and experimental therapeutic approaches based on peptidomimetics for modulation in CVD. We aim to specifically examine apolipoprotein A-I (apoA-I) and apoE mimetic peptides and their role in cholesterol transport during atherosclerosis, suppressors of cytokine signaling (SOCS)1-derived peptides and annexin-A1 as potent inhibitors of inflammation, incretin mimetics and their function in glucose-insulin tolerance, among others. With improvements in technology and synthesis platforms the future looks promising for the development of novel peptides and mimetics for therapeutic use. However, within the area of CVD much more work is required to identify and improve our understanding of peptide structure, interaction, and function in order to select the best targets to take forward for treatment.
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Affiliation(s)
- Carlota Recio
- Sir William Dunn School of Pathology, University of Oxford Oxford, UK
| | - Francesco Maione
- Department of Pharmacy, University of Naples Federico II Naples, Italy
| | - Asif J Iqbal
- Sir William Dunn School of Pathology, University of Oxford Oxford, UK
| | - Nicola Mascolo
- Department of Pharmacy, University of Naples Federico II Naples, Italy
| | - Vincenzo De Feo
- Department of Pharmacy, University of Salerno Salerno, Italy
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33
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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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34
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Pollard RD, Fulp B, Sorci-Thomas MG, Thomas MJ. High-Density Lipoprotein Biogenesis: Defining the Domains Involved in Human Apolipoprotein A-I Lipidation. Biochemistry 2016; 55:4971-81. [PMID: 27501467 DOI: 10.1021/acs.biochem.6b00347] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The first step in removing cholesterol from a cell is the ATP-binding cassette transporter 1 (ABCA1)-driven transfer of cholesterol to lipid-free or lipid-poor apolipoprotein A-I (apoA-I), which yields cholesterol-rich nascent high-density lipoprotein (nHDL) that then matures in plasma to spherical, cholesteryl ester-rich HDL. However, lipid-free apoA-I has a three-dimensional (3D) conformation that is significantly different from that of lipidated apoA-I on nHDL. By comparing the lipid-free apoA-I 3D conformation of apoA-I to that of 9-14 nm diameter nHDL, we formulated the hypothetical helical domain transitions that might drive particle formation. To test the hypothesis, ten apoA-I mutants were prepared that contained two strategically placed cysteines several of which could form intramolecular disulfide bonds and others that could not form these bonds. Mass spectrometry was used to identify amino acid sequence and intramolecular disulfide bond formation. Recombinant HDL (rHDL) formation was assessed with this group of apoA-I mutants. ABCA1-driven nHDL formation was measured in four mutants and wild-type apoA-I. The mutants contained cysteine substitutions in one of three regions: the N-terminus, amino acids 34 and 55 (E34C to S55C), central domain amino acids 104 and 162 (F104C to H162C), and the C-terminus, amino acids 200 and 233 (L200C to L233C). Mutants were studied in the locked form, with an intramolecular disulfide bond present, or unlocked form, with the cysteine thiol blocked by alkylation. Only small amounts of rHDL or nHDL were formed upon locking the central domain. We conclude that both the N- and C-terminal ends assist in the initial steps in lipid acquisition, but that opening of the central domain was essential for particle formation.
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Affiliation(s)
- Ricquita D Pollard
- Section on Molecular Medicine, Department of Internal Medicine, Wake Forest School of Medicine , Winston-Salem, North Carolina 27101, United States
| | - Brian Fulp
- Department of Biochemistry, Wake Forest School of Medicine , Winston-Salem, North Carolina 27101, United States
| | - Mary G Sorci-Thomas
- Departments of Medicine, Division of Endocrinology, Pharmacology and Toxicology, and Blood Research Institute, BloodCenter of Wisconsin, Medical College of Wisconsin , Milwaukee, Wisconsin 53226, United States
| | - Michael J Thomas
- Department of Pharmacology and Toxicology, Medical College of Wisconsin , 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226, United States
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Petrlova J, Hilt S, Budamagunta M, Domingo-Espín J, Voss JC, Lagerstedt JO. Molecular crowding impacts the structure of apolipoprotein A-I with potential implications on in vivo metabolism and function. Biopolymers 2016; 105:683-92. [PMID: 27122373 DOI: 10.1002/bip.22865] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 03/14/2016] [Accepted: 04/25/2016] [Indexed: 11/08/2022]
Abstract
The effect molecular crowding, defined as the volume exclusion exerted by one soluble inert molecule upon another soluble molecule, has on the structure and self-interaction of lipid-free apoA-I were explored. The influence of molecular crowding on lipid-free apoA-I oligomerization and internal dynamics has been analyzed using electron paramagnetic resonance (EPR) spectroscopy measurements of nitroxide spin label at selected positions throughout the protein sequence and at varying concentrations of the crowding agent Ficoll-70. The targeted positions include sites previously shown to be sensitive for detecting intermolecular interaction via spin-spin coupling. Circular dichroism was used to study secondary structural changes in lipid-free apoA-I imposed by increasing concentrations of the crowding agent. Crosslinking and SDS-PAGE gel analysis was employed to further characterize the role molecular crowding plays in inducing apoA-I oligomerization. It was concluded that the dynamic apoA-I structure and oligomeric state was altered in the presence of the crowding agent. It was also found that the C-terminal was slightly more sensitive to molecular crowding. Finally, the data described the region around residue 217 in the C-terminal domain of apoA-I as the most sensitive reporter of the crowding-induced self-association of apoA-I. The implications of this behavior to in vivo functionality are discussed. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 683-692, 2016.
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Affiliation(s)
- Jitka Petrlova
- Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden
| | - Silvia Hilt
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616
| | - Madhu Budamagunta
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616
| | - Joan Domingo-Espín
- Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden
| | - John C Voss
- Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden.,Department of Biochemistry and Molecular Medicine, University of California, Davis, CA, 95616
| | - Jens O Lagerstedt
- Department of Experimental Medical Science, Lund University, Lund, S-221 84, Sweden
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36
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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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37
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Melchior JT, Walker RG, Morris J, Jones MK, Segrest JP, Lima DB, Carvalho PC, Gozzo FC, Castleberry M, Thompson TB, Davidson WS. An Evaluation of the Crystal Structure of C-terminal Truncated Apolipoprotein A-I in Solution Reveals Structural Dynamics Related to Lipid Binding. J Biol Chem 2016; 291:5439-51. [PMID: 26755744 DOI: 10.1074/jbc.m115.706093] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Indexed: 11/06/2022] Open
Abstract
Apolipoprotein (apo) A-I mediates many of the anti-atherogenic functions attributed to high density lipoprotein. Unfortunately, efforts toward a high resolution structure of full-length apoA-I have not been fruitful, although there have been successes with deletion mutants. Recently, a C-terminal truncation (apoA-I(Δ185-243)) was crystallized as a dimer. The structure showed two helical bundles connected by a long, curved pair of swapped helical domains. To compare this structure to that existing under solution conditions, we applied small angle x-ray scattering and isotope-assisted chemical cross-linking to apoA-I(Δ185-243) in its dimeric and monomeric forms. For the dimer, we found evidence for the shared domains and aspects of the N-terminal bundles, but not the molecular curvature seen in the crystal. We also found that the N-terminal bundles equilibrate between open and closed states. Interestingly, this movement is one of the transitions proposed during lipid binding. The monomer was consistent with a model in which the long shared helix doubles back onto the helical bundle. Combined with the crystal structure, these data offer an important starting point to understand the molecular details of high density lipoprotein biogenesis.
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Affiliation(s)
- John T Melchior
- From the Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio 45237
| | - Ryan G Walker
- the Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio 45237
| | - Jamie Morris
- From the Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio 45237
| | - Martin K Jones
- the Department of Medicine and Atherosclerosis Research Unit, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Jere P Segrest
- the Department of Medicine and Atherosclerosis Research Unit, University of Alabama at Birmingham, Birmingham, Alabama 35294
| | - Diogo B Lima
- the Laboratory for Proteomics and Protein Engineering, Carlos Chagas Institute, Fiocruz, Paraná, Brazil 81350-010, and
| | - Paulo C Carvalho
- the Laboratory for Proteomics and Protein Engineering, Carlos Chagas Institute, Fiocruz, Paraná, Brazil 81350-010, and
| | - Fábio C Gozzo
- the Dalton Mass Spectrometry Laboratory, University of Campinas, São Paulo 13083-970, Brazil
| | - Mark Castleberry
- the Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio 45237
| | - Thomas B Thompson
- the Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati, Cincinnati, Ohio 45237,
| | - W Sean Davidson
- From the Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio 45237,
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Mizuguchi C, Ogata F, Mikawa S, Tsuji K, Baba T, Shigenaga A, Shimanouchi T, Okuhira K, Otaka A, Saito H. Amyloidogenic Mutation Promotes Fibril Formation of the N-terminal Apolipoprotein A-I on Lipid Membranes. J Biol Chem 2015; 290:20947-20959. [PMID: 26175149 DOI: 10.1074/jbc.m115.664227] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Indexed: 02/01/2023] Open
Abstract
The N-terminal amino acid 1-83 fragment of apolipoprotein A-I (apoA-I) has a strong propensity to form amyloid fibrils at physiological neutral pH. Because apoA-I has an ability to bind to lipid membranes, we examined the effects of the lipid environment on fibril-forming properties of the N-terminal fragment of apoA-I variants. Thioflavin T fluorescence assay as well as fluorescence and transmission microscopies revealed that upon lipid binding, fibril formation by apoA-I 1-83 is strongly inhibited, whereas the G26R mutant still retains the ability to form fibrils. Such distinct effects of lipid binding on fibril formation were also observed for the amyloidogenic prone region-containing peptides, apoA-I 8-33 and 8-33/G26R. This amyloidogenic region shifts from random coil to α-helical structure upon lipid binding. The G26R mutation appears to prevent this helix transition because lower helical propensity and more solvent-exposed conformation of the G26R variant upon lipid binding were observed in the apoA-I 1-83 fragment and 8-33 peptide. With a partially α-helical conformation induced by the presence of 2,2,2-trifluoroethanol, fibril formation by apoA-I 1-83 was strongly inhibited, whereas the G26R variant can form amyloid fibrils. These findings suggest a new possible pathway for amyloid fibril formation by the N-terminal fragment of apoA-I variants: the amyloidogenic mutations partially destabilize the α-helical structure formed upon association with lipid membranes, resulting in physiologically relevant conformations that allow fibril formation.
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Affiliation(s)
- Chiharu Mizuguchi
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Fuka Ogata
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Shiho Mikawa
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Kohei Tsuji
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Teruhiko Baba
- Research Center for Stem Cell Engineering (SCRC), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8565, Japan
| | - Akira Shigenaga
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Toshinori Shimanouchi
- Graduate School of Environmental and Life Science, Okayama University, Okayama 700-8530, Japan
| | - Keiichiro Okuhira
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Akira Otaka
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan
| | - Hiroyuki Saito
- Institute of Biomedical Sciences, Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
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Parkinson-causing α-synuclein missense mutations shift native tetramers to monomers as a mechanism for disease initiation. Nat Commun 2015; 6:7314. [PMID: 26076669 PMCID: PMC4490410 DOI: 10.1038/ncomms8314] [Citation(s) in RCA: 221] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/27/2015] [Indexed: 12/20/2022] Open
Abstract
β-Sheet-rich α-synuclein (αS) aggregates characterize Parkinson's disease (PD). αS was long believed to be a natively unfolded monomer, but recent work suggests it also occurs in α-helix-rich tetramers. Crosslinking traps principally tetrameric αS in intact normal neurons, but not after cell lysis, suggesting a dynamic equilibrium. Here we show that freshly biopsied normal human brain contains abundant αS tetramers. The PD-causing mutation A53T decreases tetramers in mouse brain. Neurons derived from an A53T patient have decreased tetramers. Neurons expressing E46K do also, and adding 1-2 E46K-like mutations into the canonical αS repeat motifs (KTKEGV) further reduces tetramers, decreases αS solubility and induces neurotoxicity and round inclusions. The other three fPD missense mutations likewise decrease tetramer:monomer ratios. The destabilization of physiological tetramers by PD-causing missense mutations and the neurotoxicity and inclusions induced by markedly decreasing tetramers suggest that decreased α-helical tetramers and increased unfolded monomers initiate pathogenesis. Tetramer-stabilizing compounds should prevent this.
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40
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Yoo JA, Lee EY, Park JY, Lee ST, Ham S, Cho KH. Different Functional and Structural Characteristics between ApoA-I and ApoA-4 in Lipid-Free and Reconstituted HDL State: ApoA-4 Showed Less Anti-Atherogenic Activity. Mol Cells 2015; 38:573-9. [PMID: 25997739 PMCID: PMC4469915 DOI: 10.14348/molcells.2015.0052] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 03/17/2015] [Accepted: 03/18/2015] [Indexed: 11/27/2022] Open
Abstract
Apolipoprotein A-I and A-IV are protein constituents of high-density lipoproteins although their functional difference in lipoprotein metabolism is still unclear. To compare anti-atherogenic properties between apoA-I and apoA-4, we characterized both proteins in lipid-free and lipid-bound state. In lipid-free state, apoA4 showed two distinct bands, around 78 and 67 Å on native gel electrophoresis, while apoA-I showed scattered band pattern less than 71 Å. In reconstituted HDL (rHDL) state, apoA-4 showed three major bands around 101 Å and 113 Å, while apoA-I-rHDL showed almost single band around 98 Å size. Lipid-free apoA-I showed 2.9-fold higher phospholipid binding ability than apoA-4. In lipid-free state, BS3-crosslinking revealed that apoA-4 showed less multimerization tendency upto dimer, while apoA-I showed pentamerization. In rHDL state (95:1), apoA-4 was existed as dimer as like as apoA-I. With higher phospholipid content (255:1), five apoA-I and three apoA-4 were required to the bigger rHDL formation. Regardless of particle size, apoA-I-rHDL showed superior LCAT activation ability than apoA-4-rHDL. Uptake of acetylated LDL was inhibited by apoA-I in both lipid-free and lipid-bound state, while apoA-4 inhibited it only lipid-free state. ApoA-4 showed less anti-atherogenic activity with more sensitivity to glycation. In conclusion, apoA-4 showed inferior physiological functions in lipid-bound state, compared with those of apoA-I, to induce more pro-atherosclerotic properties.
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Affiliation(s)
- Jeong-Ah Yoo
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749,
Korea
- Research Institute of Protein Sensor, Yeungnam University, Gyeongsan 712-749,
Korea
- BK21plus Program Serum Biomedical Research and Education Team, Yeungnam University, Gyeongsan 712-749,
Korea
| | - Eun-Young Lee
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749,
Korea
- Research Institute of Protein Sensor, Yeungnam University, Gyeongsan 712-749,
Korea
- BK21plus Program Serum Biomedical Research and Education Team, Yeungnam University, Gyeongsan 712-749,
Korea
| | - Ji Yoon Park
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749,
Korea
| | - Seung-Taek Lee
- Department of Biochemistry, College of Life Science and Biotechnology, Yonsei University, Seoul 120-749,
Korea
| | - Sihyun Ham
- Department of Chemistry, Sookmyung Women’s University, Seoul 140-742,
Korea
| | - Kyung-Hyun Cho
- School of Biotechnology, Yeungnam University, Gyeongsan 712-749,
Korea
- Research Institute of Protein Sensor, Yeungnam University, Gyeongsan 712-749,
Korea
- BK21plus Program Serum Biomedical Research and Education Team, Yeungnam University, Gyeongsan 712-749,
Korea
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41
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Zeno WF, Hilt S, Risbud SH, Voss JC, Longo ML. Spectroscopic Characterization of Structural Changes in Membrane Scaffold Proteins Entrapped within Mesoporous Silica Gel Monoliths. ACS APPLIED MATERIALS & INTERFACES 2015; 7:8640-8649. [PMID: 25849085 PMCID: PMC5522711 DOI: 10.1021/acsami.5b00898] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The changes in the orientation and conformation of three different membrane scaffold proteins (MSPs) upon entrapment in sol-gel-derived mesoporous silica monoliths were investigated. MSPs were examined in either a lipid-free or a lipid-bound conformation, where the proteins were associated with lipids to form nanolipoprotein particles (NLPs). NLPs are water-soluble, disk-shaped patches of a lipid bilayer that have amphiphilic MSPs shielding the hydrophobic lipid tails. The NLPs in this work had an average thickness of 5 nm and diameters of 9.2, 9.7, and 14.8 nm. We have previously demonstrated that NLPs are more suitable lipid-based structures for silica gel entrapment than liposomes because of their size compatibility with the mesoporous network (2-50 nm) and minimally altered structure after encapsulation. Here we further elaborate on that work by using a variety of spectroscopic techniques to elucidate whether or not different MSPs maintain their protein-lipid interactions after encapsulation. Fluorescence spectroscopy and quenching of the tryptophan residues with acrylamide, 5-DOXYL-stearic acid, and 16-DOXYL-stearic acid were used to determine the MSP orientation. We also utilized fluorescence anisotropy of tryptophans to measure the relative size of the NLPs and MSP aggregates after entrapment. Finally, circular dichroism spectroscopy was used to examine the secondary structure of the MSPs. Our results showed that, after entrapment, all of the lipid-bound MSPs maintained orientations that were minimally changed and indicative of association with lipids in NLPs. The tryptophan residues appeared to remain buried within the hydrophobic core of the lipid tails in the NLPs and appropriately spaced from the bilayer center. Also, after entrapment, lipid-bound MSPs maintained a high degree of α-helical content, a secondary structure associated with protein-lipid interactions. These findings demonstrate that NLPs are capable of serving as viable hosts for functional integral membrane proteins in the synthesis of sol-gel-derived bioinorganic hybrid nanomaterials.
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Affiliation(s)
- Wade F. Zeno
- Department of Chemical Engineering and Materials Science, University of California Davis, Davis, California, 95616
| | - Silvia Hilt
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, California, 95616
| | - Subhash H. Risbud
- Department of Chemical Engineering and Materials Science, University of California Davis, Davis, California, 95616
| | - John C. Voss
- Department of Biochemistry and Molecular Medicine, University of California Davis, Davis, California, 95616
| | - Marjorie L. Longo
- Department of Chemical Engineering and Materials Science, University of California Davis, Davis, California, 95616
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42
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Deng X, Walker RG, Morris J, Davidson WS, Thompson TB. Role of Conserved Proline Residues in Human Apolipoprotein A-IV Structure and Function. J Biol Chem 2015; 290:10689-702. [PMID: 25733664 PMCID: PMC4409236 DOI: 10.1074/jbc.m115.637058] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 02/23/2015] [Indexed: 11/06/2022] Open
Abstract
Apolipoprotein (apo)A-IV is a lipid emulsifying protein linked to a range of protective roles in obesity, diabetes, and cardiovascular disease. It exists in several states in plasma including lipid-bound in HDL and chylomicrons and as monomeric and dimeric lipid-free/poor forms. Our recent x-ray crystal structure of the central domain of apoA-IV shows that it adopts an elongated helical structure that dimerizes via two long reciprocating helices. A striking feature is the alignment of conserved proline residues across the dimer interface. We speculated that this plays important roles in the structure of the lipid-free protein and its ability to bind lipid. Here we show that the systematic conversion of these prolines to alanine increased the thermodynamic stability of apoA-IV and its propensity to oligomerize. Despite the structural stabilization, we noted an increase in the ability to bind and reorganize lipids and to promote cholesterol efflux from cells. The novel properties of these mutants allowed us to isolate the first trimeric form of an exchangeable apolipoprotein and characterize it by small-angle x-ray scattering and chemical cross-linking. The results suggest that the reciprocating helix interaction is a common feature of all apoA-IV oligomers. We propose a model of how self-association of apoA-IV can result in spherical lipoprotein particles, a model that may have broader applications to other exchangeable apolipoprotein family members.
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Affiliation(s)
- Xiaodi Deng
- From the Departments of Molecular Genetics, Biochemistry and Microbiology and
| | - Ryan G Walker
- From the Departments of Molecular Genetics, Biochemistry and Microbiology and
| | - Jamie Morris
- Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio 45237
| | - W Sean Davidson
- Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, Ohio 45237
| | - Thomas B Thompson
- From the Departments of Molecular Genetics, Biochemistry and Microbiology and
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43
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Zhang L, Sakamoto W. Possible function of VIPP1 in maintaining chloroplast membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1847:831-7. [PMID: 25725437 DOI: 10.1016/j.bbabio.2015.02.013] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 02/09/2015] [Accepted: 02/14/2015] [Indexed: 01/03/2023]
Abstract
A protein designated as VIPP1 is found widely in organisms performing oxygenic photosynthesis, but its precise role in chloroplasts has remained somewhat mysterious. Based on its structural similarity, it presumably has evolved from bacterial Phage shock protein A (PspA) with a C-terminal extension of approximately 40 amino acids. Both VIPP1 and PspA are membrane-associated despite the lack of transmembrane helices. They form an extremely large homo-complex that consists of an oligomeric ring unit. Although PspA is known to respond to membrane stress and although it acts in maintaining proton motive force through membrane repair, the multiple function of VIPP1, such as vesicle budding from inner envelope to deliver lipids to thylakoids, maintenance of photosynthetic complexes in thylakoid membranes, biogenesis of Photosystem I, and protective role of inner envelope against osmotic stress, has been proposed. Whatever its precise function in chloroplasts, it is an important protein because depletion of VIPP1 in mutants severely affects photoautotrophic growth. Recent reports of the relevant literature describe that VIPP1 becomes highly mobile when chloroplasts receive hypotonic stress, and that VIPP1 is tightly bound to lipids, which implies a crucial role of VIPP1 in membrane repair through lipid transfer. This review presents a summary of our current knowledge related to VIPP1, particularly addressing the dynamic behavior of complexes against stress and its property of lipid binding. Those data altogether suggest that VIPP1 acts a priori in chloroplast membrane maintenance through its activity to transfer lipids rather than in thylakoid formation through vesicles. This article is part of a Special Issue titled: Chloroplast Biogenesis.
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Affiliation(s)
- Lingang Zhang
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan
| | - Wataru Sakamoto
- Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan.
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44
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Handa D, Kimura H, Oka T, Takechi Y, Okuhira K, Phillips MC, Saito H. Kinetic and thermodynamic analyses of spontaneous exchange between high-density lipoprotein-bound and lipid-free apolipoprotein A-I. Biochemistry 2015; 54:1123-31. [PMID: 25564321 DOI: 10.1021/bi501345j] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
It is thought that apolipoprotein A-I (apoA-I) spontaneously exchanges between high-density lipoprotein (HDL)-bound and lipid-free states, which is relevant to the occurrence of preβ-HDL particles in plasma. To improve our understanding of the mechanistic basis for this phenomenon, we performed kinetic and thermodynamic analyses for apoA-I exchange between discoidal HDL-bound and lipid-free forms using fluorescence-labeled apoA-I variants. Gel filtration experiments demonstrated that addition of excess lipid-free apoA-I to discoidal HDL particles promotes exchange of apoA-I between HDL-associated and lipid-free pools without alteration of the steady-state HDL particle size. Kinetic analysis of time-dependent changes in NBD fluorescence upon the transition of NBD-labeled apoA-I from HDL-bound to lipid-free state indicates that the exchange kinetics are independent of the collision frequency between HDL-bound and lipid-free apoA-I, in which the lipid binding ability of apoA-I affects the rate of association of lipid-free apoA-I with the HDL particles and not the rate of dissociation of HDL-bound apoA-I. Thus, C-terminal truncations or mutations that reduce the lipid binding affinity of apoA-I strongly impair the transition of lipid-free apoA-I to the HDL-bound state. Thermodynamic analysis of the exchange kinetics demonstrated that the apoA-I exchange process is enthalpically unfavorable but entropically favorable. These results explain the thermodynamic basis of the spontaneous exchange reaction of apoA-I associated with HDL particles. The altered exchangeability of dysfunctional apoA-I would affect HDL particle rearrangement, leading to perturbed HDL metabolism.
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Affiliation(s)
- Daisuke Handa
- Institute of Health Biosciences, Graduate School of Pharmaceutical Sciences, Tokushima University , 1-78-1 Shomachi, Tokushima 770-8505, Japan
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Castelletto V, Hamley IW, Reza M, Ruokolainen J. Interactions between lipid-free apolipoprotein-AI and a lipopeptide incorporating the RGDS cell adhesion motif. NANOSCALE 2015; 7:171-178. [PMID: 25406726 DOI: 10.1039/c4nr05072j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The interaction of a designed bioactive lipopeptide C16-GGGRGDS, comprising a hexadecyl lipid chain attached to a functional heptapeptide, with the lipid-free apoliprotein, Apo-AI, is examined. This apolipoprotein is a major component of high density lipoprotein and it is involved in lipid metabolism and may serve as a biomarker for cardiovascular disease and Alzheimers' disease. We find via isothermal titration calorimetry that binding between the lipopeptide and Apo-AI occurs up to a saturation condition, just above equimolar for a 10.7 μM concentration of Apo-AI. A similar value is obtained from circular dichroism spectroscopy, which probes the reduction in α-helical secondary structure of Apo-AI upon addition of C16-GGGRGDS. Electron microscopy images show a persistence of fibrillar structures due to self-assembly of C16-GGGRGDS in mixtures with Apo-AI above the saturation binding condition. A small fraction of spheroidal or possibly "nanodisc" structures was observed. Small-angle X-ray scattering (SAXS) data for Apo-AI can be fitted using a published crystal structure of the Apo-AI dimer. The SAXS data for the lipopeptide/Apo-AI mixtures above the saturation binding conditions can be fitted to the contribution from fibrillar structures coexisting with flat discs corresponding to Apo-AI/lipopeptide aggregates.
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Affiliation(s)
- V Castelletto
- Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, UK.
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Deng X, Cong Y, Yin R, Yang G, Ding C, Yu S, Liu X, Wang C, Ding Z. Proteomic analysis of chicken peripheral blood mononuclear cells after infection by Newcastle disease virus. J Vet Sci 2014; 15:511-7. [PMID: 25234324 PMCID: PMC4269593 DOI: 10.4142/jvs.2014.15.4.511] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 07/18/2014] [Indexed: 11/20/2022] Open
Abstract
Characteristic clinical manifestations of Newcastle disease include leukopenia and immunosuppression. Peripheral blood mononuclear cells (PBMCs) are the main targets of Newcastle disease virus (NDV) infection. To survey changes in proteomic expression in chicken PBMCs following NDV infection, PBMC proteins from 30 chickens were separated using two- dimensional electrophoresis (2-DE) and subjected to mass spectrometry analysis. Quantitative intensity analysis showed that the expression of 78 proteins increased more than two-fold. Thirty-five proteins exhibited consistent changes in expression and 13 were identified as unique proteins by matrix assisted laser desorption ionization-time of flight mass spectrometer/mass spectrometer including three that were down-regulated and 10 that were up-regulated. These proteins were sorted into five groups based on function: macromolecular biosynthesis, cytoskeleton organization, metabolism, stress responses, and signal transduction. Furthermore, Western blot analysis confirmed the down-regulation of integrin-linked kinase expression and up-regulation of lamin A production. These data provide insight into the in vivo response of target cells to NDV infection at the molecular level. Additionally, results from this study have helped elucidate the molecular pathogenesis of NDV and may facilitate the development of new antiviral therapies as well as innovative diagnostic methods.
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Affiliation(s)
- Xiaoyu Deng
- Laboratory of Infectious Diseases, College of Veterinary Medicine, Jilin University, Changchun 130062, China
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47
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Pollard RD, Fulp B, Samuel MP, Sorci-Thomas MG, Thomas MJ. The conformation of lipid-free human apolipoprotein A-I in solution. Biochemistry 2013; 52:9470-81. [PMID: 24308268 DOI: 10.1021/bi401080k] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Apolipoprotein AI (apoA-I) is the principal acceptor of lipids from ATP-binding cassette transporter A1, a process that yields nascent high density lipoproteins. Analysis of lipidated apoA-I conformation yields a belt or twisted belt in which two strands of apoA-I lie antiparallel to one another. In contrast, biophysical studies have suggested that a part of lipid-free apoA-I was arranged in a four-helix bundle. To understand how lipid-free apoA-I opens from a bundle to a belt while accepting lipid it was necessary to have a more refined model for the conformation of lipid-free apoA-I. This study reports the conformation of lipid-free human apoA-I using lysine-to-lysine chemical cross-linking in conjunction with disulfide cross-linking achieved using selective cysteine mutations. After proteolysis, cross-linked peptides were verified by sequencing using tandem mass spectrometry. The resulting structure is compact with roughly four helical regions, amino acids 44-186, bundled together. C- and N-terminal ends, amino acids 1-43 and 187-243, respectively, are folded such that they lie close to one another. An unusual feature of the molecule is the high degree of connectivity of lysine40 with six other lysines, lysines that are close, for example, lysine59, to distant lysines, for example, lysine239, that are at the opposite end of the primary sequence. These results are compared and contrasted with other reported conformations for lipid-free human apoA-I and an NMR study of mouse apoA-I.
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Affiliation(s)
- Ricquita D Pollard
- Department of Biochemistry and ‡Department of Pathology, Section on Lipid Sciences, Wake Forest School of Medicine , Medical Center Blvd, Winston-Salem, North Carolina 27157-1016, United States
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48
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Wang L, Mei X, Atkinson D, Small DM. Surface behavior of apolipoprotein A-I and its deletion mutants at model lipoprotein interfaces. J Lipid Res 2013; 55:478-92. [PMID: 24308948 DOI: 10.1194/jlr.m044743] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Apolipoprotein A-I (apoA-I) has a great conformational flexibility to exist in lipid-free, lipid-poor, and lipid-bound states during lipid metabolism. To address the lipid binding and the dynamic desorption behavior of apoA-I at lipoprotein surfaces, apoA-I, Δ(185-243)apoA-I, and Δ(1-59)(185-243)apoA-I were studied at triolein/water and phosphatidylcholine/triolein/water interfaces with special attention to surface pressure. All three proteins are surface active to both interfaces lowering the interfacial tension and thus increasing the surface pressure to modify the interfaces. Δ(185-243)apoA-I adsorbs much more slowly and lowers the interfacial tension less than full-length apoA-I, confirming that the C-terminal domain (residues 185-243) initiates the lipid binding. Δ(1-59)(185-243)apoA-I binds more rapidly and lowers the interfacial tension more than Δ(185-243)apoA-I, suggesting that destabilizing the N-terminal α-helical bundle (residues 1-185) restores lipid binding. The three proteins desorb from both interfaces at different surface pressures revealing that different domains of apoA-I possess different lipid affinity. Δ(1-59)(185-243)apoA-I desorbs at lower pressures compared with apoA-I and Δ(185-243)apoA-I indicating that it is missing a strong lipid association motif. We propose that during lipoprotein remodeling, surface pressure mediates the adsorption and partial or full desorption of apoA-I allowing it to exchange among different lipoproteins and adopt various conformations to facilitate its multiple functions.
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Affiliation(s)
- Libo Wang
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
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Gulshan K, Brubaker G, Wang S, Hazen SL, Smith JD. Sphingomyelin depletion impairs anionic phospholipid inward translocation and induces cholesterol efflux. J Biol Chem 2013; 288:37166-79. [PMID: 24220029 DOI: 10.1074/jbc.m113.512244] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phosphatidylserine (PS) floppase activity (outward translocation) of ABCA1 leads to plasma membrane remodeling that plays a role in lipid efflux to apolipoprotein A-I (apoAI) generating nascent high density lipoprotein. The Tangier disease W590S ABCA1 mutation has defective PS floppase activity and diminished cholesterol efflux activity. Here, we report that depletion of sphingomyelin by inhibitors or sphingomyelinase caused plasma membrane remodeling, leading to defective flip (inward translocation) of PS, higher PS exposure, and higher cholesterol efflux from cells by both ABCA1-dependent and ABCA1-independent mechanisms. Mechanistically, sphingomyelin was connected to PS translocation in cell-free liposome studies that showed that sphingomyelin increased the rate of spontaneous PS flipping. Depletion of sphingomyelin in stably transfected HEK293 cells expressing the Tangier disease W590S mutant ABCA1 isoform rescued the defect in PS exposure and restored cholesterol efflux to apoAI. Liposome studies showed that PS directly increased cholesterol accessibility to extraction by cyclodextrin, providing the mechanistic link between cell surface PS and cholesterol efflux. We conclude that altered plasma membrane environment conferred by depleting sphingomyelin impairs PS flip and promotes cholesterol efflux in ABCA1-dependent and -independent manners.
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Nagao K, Hata M, Tanaka K, Takechi Y, Nguyen D, Dhanasekaran P, Lund-Katz S, Phillips MC, Saito H. The roles of C-terminal helices of human apolipoprotein A-I in formation of high-density lipoprotein particles. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:80-7. [PMID: 24120703 DOI: 10.1016/j.bbalip.2013.10.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/07/2013] [Accepted: 10/01/2013] [Indexed: 12/20/2022]
Abstract
Apolipoprotein A-I (apoA-I) accepts cholesterol and phospholipids from ATP-binding cassette transporter A1 (ABCA1)-expressing cells to form high-density lipoprotein (HDL). Human apoA-I has two tertiary structural domains and the C-terminal domain (approximately amino acids 190-243) plays a key role in lipid binding. Although the high lipid affinity region of the C-terminal domain of apoA-I (residues 223-243) is essential for the HDL formation, the function of low lipid affinity region (residues 191-220) remains unclear. To evaluate the role of residues 191-220, we analyzed the structure, lipid binding properties, and HDL formation activity of Δ191-220 apoA-I, in comparison to wild-type and Δ223-243 apoA-I. Although deletion of residues 191-220 has a slight effect on the tertiary structure of apoA-I, the Δ191-220 variant showed intermediate behavior between wild-type and Δ223-243 regarding the formation of hydrophobic sites and lipid interaction through the C-terminal domain. Physicochemical analysis demonstrated that defective lipid binding of Δ191-220 apoA-I is due to the decreased ability to form α-helix structure which provides the energetic source for lipid binding. In addition, the ability to form HDL particles in vitro and induce cholesterol efflux from ABCA1-expressing cells of Δ191-220 apoA-I was also intermediate between wild-type and Δ223-243 apoA-I. These results suggest that despite possessing low lipid affinity, residues 191-220 play a role in enhancing the ability of apoA-I to bind to and solubilize lipids by forming α-helix upon lipid interaction. Our results demonstrate that the combination of low lipid affinity region and high lipid affinity region of apoA-I is required for efficient ABCA1-dependent HDL formation.
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Affiliation(s)
- Kohjiro Nagao
- Institute of Health Biosciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan; Graduate School of Pharmaceutical Sciences, The University of Tokushima, 1-78-1 Shomachi, Tokushima 770-8505, Japan.
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