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Reijnders E, van der Laarse A, Ruhaak LR, Cobbaert CM. Closing the gaps in patient management of dyslipidemia: stepping into cardiovascular precision diagnostics with apolipoprotein profiling. Clin Proteomics 2024; 21:19. [PMID: 38429638 PMCID: PMC10908091 DOI: 10.1186/s12014-024-09465-w] [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: 09/18/2023] [Accepted: 02/14/2024] [Indexed: 03/03/2024] Open
Abstract
In persons with dyslipidemia, a high residual risk of cardiovascular disease remains despite lipid lowering therapy. Current cardiovascular risk prediction mainly focuses on low-density lipoprotein cholesterol (LDL-c) levels, neglecting other contributing risk factors. Moreover, the efficacy of LDL-c lowering by statins resulting in reduced cardiovascular risk is only partially effective. Secondly, from a metrological viewpoint LDL-c falls short as a reliable measurand. Both direct and calculated LDL-c tests produce inaccurate test results at the low end under aggressive lipid lowering therapy. As LDL-c tests underperform both clinically and metrologically, there is an urging need for molecularly defined biomarkers. Over the years, apolipoproteins have emerged as promising biomarkers in the context of cardiovascular disease as they are the functional workhorses in lipid metabolism. Among these, apolipoprotein B (ApoB), present on all atherogenic lipoprotein particles, has demonstrated to clinically outperform LDL-c. Other apolipoproteins, such as Apo(a) - the characteristic apolipoprotein of the emerging risk factor lipoprotein(a) -, and ApoC-III - an inhibitor of triglyceride-rich lipoprotein clearance -, have attracted attention as well. To support personalized medicine, we need to move to molecularly defined risk markers, like the apolipoproteins. Molecularly defined diagnosis and molecularly targeted therapy require molecularly measured biomarkers. This review provides a summary of the scientific validity and (patho)physiological role of nine serum apolipoproteins, Apo(a), ApoB, ApoC-I, ApoC-II, ApoC-III, ApoE and its phenotypes, ApoA-I, ApoA-II, and ApoA-IV, in lipid metabolism, their association with cardiovascular disease, and their potential as cardiovascular risk markers when measured in a multiplex apolipoprotein panel.
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Affiliation(s)
- Esther Reijnders
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, the Netherlands.
| | - Arnoud van der Laarse
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - L Renee Ruhaak
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Christa M Cobbaert
- Department of Clinical Chemistry and Laboratory Medicine, Leiden University Medical Center, Leiden, the Netherlands
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2
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Kumari A, Grønnemose AL, Kristensen KK, Winther AML, Young SG, Jørgensen TJD, Ploug M. Inverse effects of APOC2 and ANGPTL4 on the conformational dynamics of lid-anchoring structures in lipoprotein lipase. Proc Natl Acad Sci U S A 2023; 120:e2221888120. [PMID: 37094117 PMCID: PMC10160976 DOI: 10.1073/pnas.2221888120] [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: 01/03/2023] [Accepted: 03/28/2023] [Indexed: 04/26/2023] Open
Abstract
The lipolytic processing of triglyceride-rich lipoproteins (TRLs) by lipoprotein lipase (LPL) is crucial for the delivery of dietary lipids to the heart, skeletal muscle, and adipose tissue. The processing of TRLs by LPL is regulated in a tissue-specific manner by a complex interplay between activators and inhibitors. Angiopoietin-like protein 4 (ANGPTL4) inhibits LPL by reducing its thermal stability and catalyzing the irreversible unfolding of LPL's α/β-hydrolase domain. We previously mapped the ANGPTL4 binding site on LPL and defined the downstream unfolding events resulting in LPL inactivation. The binding of LPL to glycosylphosphatidylinositol-anchored high-density lipoprotein-binding protein 1 protects against LPL unfolding. The binding site on LPL for an activating cofactor, apolipoprotein C2 (APOC2), and the mechanisms by which APOC2 activates LPL have been unclear and controversial. Using hydrogen-deuterium exchange/mass spectrometry, we now show that APOC2's C-terminal α-helix binds to regions of LPL surrounding the catalytic pocket. Remarkably, APOC2's binding site on LPL overlaps with that for ANGPTL4, but their effects on LPL conformation are distinct. In contrast to ANGPTL4, APOC2 increases the thermal stability of LPL and protects it from unfolding. Also, the regions of LPL that anchor the lid are stabilized by APOC2 but destabilized by ANGPTL4, providing a plausible explanation for why APOC2 is an activator of LPL, while ANGPTL4 is an inhibitor. Our studies provide fresh insights into the molecular mechanisms by which APOC2 binds and stabilizes LPL-and properties that we suspect are relevant to the conformational gating of LPL's active site.
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Affiliation(s)
- Anni Kumari
- Finsen Laboratory, Copenhagen University Hospital-Rigshospitalet, DK-2200Copenhagen N, Denmark
- Finsen Laboratory, Biotech Research and Innovation Centre, University of Copenhagen, DK-2200Copenhagen N, Denmark
| | - Anne Louise Grønnemose
- Finsen Laboratory, Copenhagen University Hospital-Rigshospitalet, DK-2200Copenhagen N, Denmark
- Finsen Laboratory, Biotech Research and Innovation Centre, University of Copenhagen, DK-2200Copenhagen N, Denmark
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK–5320Odense, Denmark
| | - Kristian K. Kristensen
- Finsen Laboratory, Copenhagen University Hospital-Rigshospitalet, DK-2200Copenhagen N, Denmark
- Finsen Laboratory, Biotech Research and Innovation Centre, University of Copenhagen, DK-2200Copenhagen N, Denmark
| | - Anne-Marie L. Winther
- Finsen Laboratory, Copenhagen University Hospital-Rigshospitalet, DK-2200Copenhagen N, Denmark
- Finsen Laboratory, Biotech Research and Innovation Centre, University of Copenhagen, DK-2200Copenhagen N, Denmark
| | - Stephen G. Young
- Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA90095
- Department of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles, CA90095
| | - Thomas J. D. Jørgensen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK–5320Odense, Denmark
| | - Michael Ploug
- Finsen Laboratory, Copenhagen University Hospital-Rigshospitalet, DK-2200Copenhagen N, Denmark
- Finsen Laboratory, Biotech Research and Innovation Centre, University of Copenhagen, DK-2200Copenhagen N, Denmark
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3
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Wen Y, Chen YQ, Konrad RJ. The Regulation of Triacylglycerol Metabolism and Lipoprotein Lipase Activity. Adv Biol (Weinh) 2022; 6:e2200093. [PMID: 35676229 DOI: 10.1002/adbi.202200093] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/03/2022] [Indexed: 01/28/2023]
Abstract
Triacylglycerol (TG) metabolism is tightly regulated to maintain a pool of TG within circulating lipoproteins that can be hydrolyzed in a tissue-specific manner by lipoprotein lipase (LPL) to enable the delivery of fatty acids to adipose or oxidative tissues as needed. Elevated serum TG concentrations, which result from a deficiency of LPL activity or, more commonly, an imbalance in the regulation of tissue-specific LPL activities, have been associated with an increased risk of atherosclerotic cardiovascular disease through multiple studies. Among the most critical LPL regulators are the angiopoietin-like (ANGPTL) proteins ANGPTL3, ANGPTL4, and ANGPTL8, and a number of different apolipoproteins including apolipoprotein A5 (ApoA5), apolipoprotein C2 (ApoC2), and apolipoprotein C3 (ApoC3). These ANGPTLs and apolipoproteins work together to orchestrate LPL activity and therefore play pivotal roles in TG partitioning, hydrolysis, and utilization. This review summarizes the mechanisms of action, epidemiological findings, and genetic data most relevant to these ANGPTLs and apolipoproteins. The interplay between these important regulators of TG metabolism in both fasted and fed states is highlighted with a holistic view toward understanding key concepts and interactions. Strategies for developing safe and effective therapeutics to reduce circulating TG by selectively targeting these ANGPTLs and apolipoproteins are also discussed.
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Affiliation(s)
- Yi Wen
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, 46285, USA
| | - Yan Q Chen
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, 46285, USA
| | - Robert J Konrad
- Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN, 46285, USA
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4
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Lipoprotein size is a main determinant for the rate of hydrolysis by exogenous lipoprotein lipase in human plasma. J Lipid Res 2021; 63:100144. [PMID: 34710432 PMCID: PMC8953621 DOI: 10.1016/j.jlr.2021.100144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 12/19/2022] Open
Abstract
Lipoprotein lipase (LPL) is a key player in plasma triglyceride metabolism. Consequently, LPL is regulated by several proteins during synthesis, folding, secretion, and transport to its site of action at the luminal side of capillaries, as well as during the catalytic reaction. Some proteins are well known, while others have been identified but are still not fully understood. We set out to study the effects of the natural variations in the plasma levels of all known LPL regulators on the activity of purified LPL added to samples of fasted plasma taken from 117 individuals. The enzymatic activity was measured at 25° C using isothermal titration calorimetry. This method allows quantification of the ability of an added fixed amount of exogenous LPL to hydrolyze triglyceride-rich lipoproteins in plasma samples by measuring the heat produced. Our results indicate that, under the conditions used, the normal variation in the endogenous levels of apolipoprotein C1, C2 and C3, or the levels of angiopoietin-like proteins 3, 4, and 8 in the fasted plasma samples had no significant effect on the recorded activity of the added LPL. Instead, the key determinant for the LPL activity was a lipid signature strongly correlated to the average size of the VLDL particles. The signature involved several lipoprotein and plasma lipid parameters, but also apolipoprotein A5 levels. While the measurements cannot fully represent the action of LPL when attached to the capillary wall, our study provides knowledge on the interindividual variation of LPL lipolysis rates in human plasma.
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Benitez Amaro A, Solanelles Curco A, Garcia E, Julve J, Rives J, Benitez S, Llorente Cortes V. Apolipoprotein and LRP1-Based Peptides as New Therapeutic Tools in Atherosclerosis. J Clin Med 2021; 10:jcm10163571. [PMID: 34441867 PMCID: PMC8396846 DOI: 10.3390/jcm10163571] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 08/05/2021] [Accepted: 08/08/2021] [Indexed: 12/17/2022] Open
Abstract
Apolipoprotein (Apo)-based mimetic peptides have been shown to reduce atherosclerosis. Most of the ApoC-II and ApoE mimetics exert anti-atherosclerotic effects by improving lipid profile. ApoC-II mimetics reverse hypertriglyceridemia and ApoE-based peptides such as Ac-hE18A-NH2 reduce cholesterol and triglyceride (TG) levels in humans. Conversely, other classes of ApoE and ApoA-I mimetic peptides and, more recently, ApoJ and LRP1-based peptides, exhibit several anti-atherosclerotic actions in experimental models without influencing lipoprotein profile. These other mimetic peptides display at least one atheroprotective mechanism such as providing LDL stability against mechanical modification or conferring protection against the action of lipolytic enzymes inducing LDL aggregation in the arterial intima. Other anti-atherosclerotic effects exerted by these peptides also include protection against foam cell formation and inflammation, and induction of reverse cholesterol transport. Although the underlying mechanisms of action are still poorly described, the recent findings suggest that these mimetics could confer atheroprotection by favorably influencing lipoprotein function rather than lipoprotein levels. Despite the promising results obtained with peptide mimetics, the assessment of their stability, atheroprotective efficacy and tissue targeted delivery are issues currently under progress.
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Affiliation(s)
- Aleyda Benitez Amaro
- Institute of Biomedical Research of Barcelona (IIBB), Spanish National Research Council (CSIC), 08036 Barcelona, Spain; (A.B.A.); (E.G.)
- Biomedical Research Institute Sant Pau (IIB-Sant Pau), 08041 Barcelona, Spain;
| | | | - Eduardo Garcia
- Institute of Biomedical Research of Barcelona (IIBB), Spanish National Research Council (CSIC), 08036 Barcelona, Spain; (A.B.A.); (E.G.)
- Biomedical Research Institute Sant Pau (IIB-Sant Pau), 08041 Barcelona, Spain;
| | - Josep Julve
- Metabolic Basis of Cardiovascular Risk Group, Biomedical Research Institute Sant Pau (IIB Sant Pau), 08041 Barcelona, Spain;
- CIBER de Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), 28029 Madrid, Spain
| | - Jose Rives
- Biochemistry Department, Hospital de la Santa Creu i Sant Pau, 08025 Barcelona, Spain;
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, Universitat Autònoma de Barcelona (UAB), Cerdanyola del Vallès, 08016 Barcelona, Spain
| | - Sonia Benitez
- Cardiovascular Biochemistry Group, Biomedical Research Institute Sant Pau (IIB Sant Pau), 08041 Barcelona, Spain
- Correspondence: (S.B.); or (V.L.C.)
| | - Vicenta Llorente Cortes
- Institute of Biomedical Research of Barcelona (IIBB), Spanish National Research Council (CSIC), 08036 Barcelona, Spain; (A.B.A.); (E.G.)
- Biomedical Research Institute Sant Pau (IIB-Sant Pau), 08041 Barcelona, Spain;
- CIBERCV, Institute of Health Carlos III, 28029 Madrid, Spain
- Correspondence: (S.B.); or (V.L.C.)
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The Importance of Lipoprotein Lipase Regulation in Atherosclerosis. Biomedicines 2021; 9:biomedicines9070782. [PMID: 34356847 PMCID: PMC8301479 DOI: 10.3390/biomedicines9070782] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 07/02/2021] [Accepted: 07/04/2021] [Indexed: 02/07/2023] Open
Abstract
Lipoprotein lipase (LPL) plays a major role in the lipid homeostasis mainly by mediating the intravascular lipolysis of triglyceride rich lipoproteins. Impaired LPL activity leads to the accumulation of chylomicrons and very low-density lipoproteins (VLDL) in plasma, resulting in hypertriglyceridemia. While low-density lipoprotein cholesterol (LDL-C) is recognized as a primary risk factor for atherosclerosis, hypertriglyceridemia has been shown to be an independent risk factor for cardiovascular disease (CVD) and a residual risk factor in atherosclerosis development. In this review, we focus on the lipolysis machinery and discuss the potential role of triglycerides, remnant particles, and lipolysis mediators in the onset and progression of atherosclerotic cardiovascular disease (ASCVD). This review details a number of important factors involved in the maturation and transportation of LPL to the capillaries, where the triglycerides are hydrolyzed, generating remnant lipoproteins. Moreover, LPL and other factors involved in intravascular lipolysis are also reported to impact the clearance of remnant lipoproteins from plasma and promote lipoprotein retention in capillaries. Apolipoproteins (Apo) and angiopoietin-like proteins (ANGPTLs) play a crucial role in regulating LPL activity and recent insights into LPL regulation may elucidate new pharmacological means to address the challenge of hypertriglyceridemia in atherosclerosis development.
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7
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Fukushima K, Omura K, Goshi S, Okada A, Tanaka M, Tsujimoto T, Iriyama K, Sugioka N. Individualization of the infusion rate of a soybean oil-based intravenous lipid emulsion for inpatients, based on baseline triglyceride concentrations: A population pharmacokinetic approach. JPEN J Parenter Enteral Nutr 2021; 46:104-113. [PMID: 33769561 PMCID: PMC9290941 DOI: 10.1002/jpen.2111] [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: 09/03/2020] [Revised: 02/24/2021] [Accepted: 03/14/2021] [Indexed: 11/11/2022]
Abstract
BACKGROUND A rapid infusion rate for intravenous lipid emulsion (ILE) can cause adverse effects; therefore, safe and efficient infusion rates are desired. This study aimed to develop a triglyceride (TG) kinetic model after soybean oil-based ILE (SO-ILE) administration and individualize the infusion rate via a population pharmacokinetic approach. METHODS Eighty-three inpatients were enrolled in this prospective observational study. A TG kinetic model was applied to the observations based on population pharmacokinetics using a nonlinear mixed-effect model. The patients' characteristics and laboratory parameters were evaluated to identify predictors of TG kinetics, and the maximum acceptable infusion rate was defined as that for which the maximum TG concentration did not exceed 400 mg/dl in 90% of patients. RESULTS No adverse events associated with SO-ILE administration were observed. The developed TG kinetic model explained the observed TG concentrations and identified the baseline TG concentration and body weight as predictors of TG kinetics. The estimated maximum acceptable infusion rates greatly varied among individuals, ranging from <0.01 to 0.3 g/kg/h. CONCLUSION The present study suggested the necessity and demonstrated the feasibility of individualizing the infusion rates of SO-ILE, using a population pharmacokinetic approach.
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Affiliation(s)
- Keizo Fukushima
- Department of Clinical Pharmacokinetics, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Kobe, Japan
| | - Kenji Omura
- Department of Surgery, Ageo Central General Hospital, Saitama, Japan
| | - Satoshi Goshi
- Department of Gastroenterology and Hepatology, Joetsu General Hospital, Niigata, Japan
| | - Akira Okada
- Department of Clinical Pharmacokinetics, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Kobe, Japan.,Department of Regulatory Science, Faculty of Pharmacy, Musashino University, Tokyo, Japan
| | - Motomu Tanaka
- Department of Surgery, Ageo Central General Hospital, Saitama, Japan
| | - Takae Tsujimoto
- Department of Pathophysiology, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Kobe, Japan
| | - Keiji Iriyama
- Department of Surgery, Nagashima Central Hospital, Mie, Japan
| | - Nobuyuki Sugioka
- Department of Clinical Pharmacokinetics, Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Kobe, Japan
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8
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Wolska A, Reimund M, Sviridov DO, Amar MJ, Remaley AT. Apolipoprotein Mimetic Peptides: Potential New Therapies for Cardiovascular Diseases. Cells 2021; 10:597. [PMID: 33800446 PMCID: PMC8000854 DOI: 10.3390/cells10030597] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Revised: 03/01/2021] [Accepted: 03/02/2021] [Indexed: 12/13/2022] Open
Abstract
Since the seminal breakthrough of treating diabetic patients with insulin in the 1920s, there has been great interest in developing other proteins and their peptide mimetics as therapies for a wide variety of other medical disorders. Currently, there are at least 60 different peptides that have been approved for human use and over 150 peptides that are in various stages of clinical development. Peptides mimetic of the major proteins on lipoproteins, namely apolipoproteins, have also been developed first as tools for understanding apolipoprotein structure and more recently as potential therapeutics. In this review, we discuss the biochemistry, peptide mimetics design and clinical trials for peptides based on apoA-I, apoE and apoC-II. We primarily focus on applications of peptide mimetics related to cardiovascular diseases. We conclude with a discussion on the limitations of peptides as therapeutic agents and the challenges that need to be overcome before apolipoprotein mimetic peptides can be developed into new drugs.
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Affiliation(s)
- Anna Wolska
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA; (M.R.); (D.O.S.); (M.J.A.); (A.T.R.)
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Abumrad NA, Cabodevilla AG, Samovski D, Pietka T, Basu D, Goldberg IJ. Endothelial Cell Receptors in Tissue Lipid Uptake and Metabolism. Circ Res 2021; 128:433-450. [PMID: 33539224 DOI: 10.1161/circresaha.120.318003] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Lipid uptake and metabolism are central to the function of organs such as heart, skeletal muscle, and adipose tissue. Although most heart energy derives from fatty acids (FAs), excess lipid accumulation can cause cardiomyopathy. Similarly, high delivery of cholesterol can initiate coronary artery atherosclerosis. Hearts and arteries-unlike liver and adrenals-have nonfenestrated capillaries and lipid accumulation in both health and disease requires lipid movement from the circulation across the endothelial barrier. This review summarizes recent in vitro and in vivo findings on the importance of endothelial cell receptors and uptake pathways in regulating FAs and cholesterol uptake in normal physiology and cardiovascular disease. We highlight clinical and experimental data on the roles of ECs in lipid supply to tissues, heart, and arterial wall in particular, and how this affects organ metabolism and function. Models of FA uptake into ECs suggest that receptor-mediated uptake predominates at low FA concentrations, such as during fasting, whereas FA uptake during lipolysis of chylomicrons may involve paracellular movement. Similarly, in the setting of an intact arterial endothelial layer, recent and historic data support a role for receptor-mediated processes in the movement of lipoproteins into the subarterial space. We conclude with thoughts on the need to better understand endothelial lipid transfer for fuller comprehension of the pathophysiology of hyperlipidemia, and lipotoxic diseases such as some forms of cardiomyopathy and atherosclerosis.
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Affiliation(s)
- Nada A Abumrad
- Division of Nutritional Sciences, Department of Medicine, Washington University School of Medicine, Saint Louis, MO (N.A.A., D.S., T.P.)
| | - Ainara G Cabodevilla
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine (A.G.C., D.B., I.J.G.)
| | - Dmitri Samovski
- Division of Nutritional Sciences, Department of Medicine, Washington University School of Medicine, Saint Louis, MO (N.A.A., D.S., T.P.)
| | - Terri Pietka
- Division of Nutritional Sciences, Department of Medicine, Washington University School of Medicine, Saint Louis, MO (N.A.A., D.S., T.P.)
| | - Debapriya Basu
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine (A.G.C., D.B., I.J.G.)
| | - Ira J Goldberg
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, New York University Grossman School of Medicine (A.G.C., D.B., I.J.G.)
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Abstract
PURPOSE OF REVIEW Apolipoprotein C-II (apoC-II) is a critical cofactor for the activation of lipoprotein lipase (LPL), a plasma enzyme that hydrolyzes triglycerides (TG) on TG-rich lipoproteins (TRL). Although apoC-II was first discovered nearly 50 years ago, there is renewed interest in it because of the recent efforts to develop new drugs for the treatment of hypertriglyceridemia (HTG). The main topic of this review will be the development of apoC-II mimetic peptides as a possible new therapy for cardiovascular disease. RECENT FINDINGS We first describe the biochemistry of apoC-II and its role in TRL metabolism. We then review the clinical findings of HTG, particularly those related to apoC-II deficiency, and how TG metabolism relates to the development of atherosclerosis. We next summarize the current efforts to develop new drugs for HTG. Finally, we describe recent efforts to make small synthetic apoC-II mimetic peptides for activation of LPL and how these peptides unexpectedly have other mechanisms of action mostly related to the antagonism of the TG-raising effects of apoC-III. SUMMARY The role of apoC-II in TG metabolism is reviewed, as well as recent efforts to develop apoC-II mimetic peptides into a novel therapy for HTG.
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Affiliation(s)
- Anna Wolska
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Mart Reimund
- Department of Chemistry and Biotechnology, Tallinn University of Technology, Tallinn, Estonia
| | - Alan T Remaley
- Lipoprotein Metabolism Laboratory, Translational Vascular Medicine Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
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Basu D, Bornfeldt KE. Hypertriglyceridemia and Atherosclerosis: Using Human Research to Guide Mechanistic Studies in Animal Models. Front Endocrinol (Lausanne) 2020; 11:504. [PMID: 32849290 PMCID: PMC7423973 DOI: 10.3389/fendo.2020.00504] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 06/23/2020] [Indexed: 12/18/2022] Open
Abstract
Human studies support a strong association between hypertriglyceridemia and atherosclerotic cardiovascular disease (CVD). However, whether a causal relationship exists between hypertriglyceridemia and increased CVD risk is still unclear. One plausible explanation for the difficulty establishing a clear causal role for hypertriglyceridemia in CVD risk is that lipolysis products of triglyceride-rich lipoproteins (TRLs), rather than the TRLs themselves, are the likely mediators of increased CVD risk. This hypothesis is supported by studies of rare mutations in humans resulting in impaired clearance of such lipolysis products (remnant lipoprotein particles; RLPs). Several animal models of hypertriglyceridemia support this hypothesis and have provided additional mechanistic understanding. Mice deficient in lipoprotein lipase (LPL), the major vascular enzyme responsible for TRL lipolysis and generation of RLPs, or its endothelial anchor GPIHBP1, are severely hypertriglyceridemic but develop only minimal atherosclerosis as compared with animal models deficient in apolipoprotein (APO) E, which is required to clear TRLs and RLPs. Likewise, animal models convincingly show that increased clearance of TRLs and RLPs by LPL activation (achieved by inhibition of APOC3, ANGPTL3, or ANGPTL4 action, or increased APOA5) results in protection from atherosclerosis. Mechanistic studies suggest that RLPs are more atherogenic than large TRLs because they more readily enter the artery wall, and because they are enriched in cholesterol relative to triglycerides, which promotes pro-atherogenic effects in lesional cells. Other mechanistic studies show that hepatic receptors (LDLR and LRP1) and APOE are critical for RLP clearance. Thus, studies in animal models have provided additional mechanistic insight and generally agree with the hypothesis that RLPs derived from TRLs are highly atherogenic whereas hypertriglyceridemia due to accumulation of very large TRLs in plasma is not markedly atherogenic in the absence of TRL lipolysis products.
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Affiliation(s)
- Debapriya Basu
- Division of Endocrinology, Diabetes and Metabolism, New York University School of Medicine, New York, NY, United States
| | - Karin E. Bornfeldt
- Department of Medicine, University of Washington Medicine Diabetes Institute, University of Washington School of Medicine, Seattle, WA, United States
- Department of Pathology, University of Washington Medicine Diabetes Institute, University of Washington School of Medicine, Seattle, WA, United States
- *Correspondence: Karin E. Bornfeldt
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12
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Howlett GJ, Ryan TM, Griffin MD. Lipid-apolipoprotein interactions in amyloid fibril formation and relevance to atherosclerosis. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2019; 1867:502-507. [DOI: 10.1016/j.bbapap.2018.08.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Revised: 08/06/2018] [Accepted: 08/27/2018] [Indexed: 01/08/2023]
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13
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Wolska A, Dunbar RL, Freeman LA, Ueda M, Amar MJ, Sviridov DO, Remaley AT. Apolipoprotein C-II: New findings related to genetics, biochemistry, and role in triglyceride metabolism. Atherosclerosis 2017; 267:49-60. [PMID: 29100061 DOI: 10.1016/j.atherosclerosis.2017.10.025] [Citation(s) in RCA: 127] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 10/03/2017] [Accepted: 10/19/2017] [Indexed: 02/08/2023]
Abstract
Apolipoprotein C-II (apoC-II) is a small exchangeable apolipoprotein found on triglyceride-rich lipoproteins (TRL), such as chylomicrons (CM) and very low-density lipoproteins (VLDL), and on high-density lipoproteins (HDL), particularly during fasting. ApoC-II plays a critical role in TRL metabolism by acting as a cofactor of lipoprotein lipase (LPL), the main enzyme that hydrolyses plasma triglycerides (TG) on TRL. Here, we present an overview of the role of apoC-II in TG metabolism, emphasizing recent novel findings regarding its transcriptional regulation and biochemistry. We also review the 24 genetic mutations in the APOC2 gene reported to date that cause hypertriglyceridemia (HTG). Finally, we describe the clinical presentation of apoC-II deficiency and assess the current therapeutic approaches, as well as potential novel emerging therapies.
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Affiliation(s)
- Anna Wolska
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Richard L Dunbar
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA; ICON plc, North Wales, PA, USA; Cardiometabolic and Lipid Clinic, Corporal Michael J. Crescenz VA Medical Center, Philadelphia, PA, USA
| | - Lita A Freeman
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Masako Ueda
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Marcelo J Amar
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Denis O Sviridov
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
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14
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Lee J, Hegele RA. Investigated treatments for lipoprotein lipase deficiency and related metabolic disorders. Expert Opin Orphan Drugs 2017. [DOI: 10.1080/21678707.2017.1311784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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15
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Ueda M, Dunbar RL, Wolska A, Sikora TU, Escobar MDR, Seliktar N, deGoma E, DerOhannessian S, Morrell L, McIntyre AD, Burke F, Sviridov D, Amar M, Shamburek RD, Freeman L, Hegele RA, Remaley AT, Rader DJ. A Novel APOC2 Missense Mutation Causing Apolipoprotein C-II Deficiency With Severe Triglyceridemia and Pancreatitis. J Clin Endocrinol Metab 2017; 102:1454-1457. [PMID: 28201738 PMCID: PMC6283445 DOI: 10.1210/jc.2016-3903] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Accepted: 10/07/2016] [Indexed: 02/03/2023]
Abstract
CONTEXT Familial chylomicronemia syndrome (FCS) is a rare heritable disorder associated with severe hypertriglyceridemia and recurrent pancreatitis. Lipoprotein lipase deficiency and apolipoprotein C-II deficiency are two well-characterized autosomal recessive causes of FCS, and three other genes have been described to cause FCS. Because therapeutic approaches can vary according to the underlying etiology, it is important to establish the molecular etiology of FCS. CASE DESCRIPTION A man originally from North Africa was referred to the University of Pennsylvania Lipid Clinic for severe hypertriglyceridemia and recurrent pancreatitis, consistent with the clinical diagnosis of FCS. Molecular analyses of FCS-associated genes revealed a homozygous missense variant R72T in APOC2. Molecular modeling of the variant predicted that the apolipoprotein C-II R72T peptide has reduced lipid binding affinity. In vitro studies of the patient's plasma confirmed the lack of functional apoC-II activity. Moreover, the apoC-II protein was undetectable in the patient's plasma, quantitatively as well as qualitatively. CONCLUSIONS We identified a missense APOC2 variant causing apoC-II deficiency in a patient with severe hypertriglyceridemia and recurrent pancreatitis. Beyond dietary management and usual pharmacologic therapies, an apoC-II mimetic peptide may become an optional therapy in patients with apoC-II deficiency in the future.
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Affiliation(s)
- Masako Ueda
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Richard L Dunbar
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Anna Wolska
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20894
| | - Tracey U Sikora
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Maria Del Rosario Escobar
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Naomi Seliktar
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Emil deGoma
- Akebia Therapeutics, Cambridge, Massachusetts 02142
| | - Stephanie DerOhannessian
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Linda Morrell
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Adam D McIntyre
- Blackburn Cardiovascular Genetics Laboratory, Robarts Research Institute, Western University, London, Ontario N6A 5B7, Canada
| | - Frances Burke
- Division of Cardiovascular Medicine, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Denis Sviridov
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20894
| | - Marcelo Amar
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20894
| | - Robert D Shamburek
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20894
| | - Lita Freeman
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20894
| | - Robert A Hegele
- Blackburn Cardiovascular Genetics Laboratory, Robarts Research Institute, Western University, London, Ontario N6A 5B7, Canada
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20894
| | - Daniel J Rader
- Division of Translational Medicine and Human Genetics, Department of Medicine, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania 19104
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16
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Geldenhuys WJ, Lin L, Darvesh AS, Sadana P. Emerging strategies of targeting lipoprotein lipase for metabolic and cardiovascular diseases. Drug Discov Today 2016; 22:352-365. [PMID: 27771332 DOI: 10.1016/j.drudis.2016.10.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Revised: 09/17/2016] [Accepted: 10/12/2016] [Indexed: 12/12/2022]
Abstract
Although statins and other pharmacological approaches have improved the management of lipid abnormalities, there exists a need for newer treatment modalities especially for the management of hypertriglyceridemia. Lipoprotein lipase (LPL), by promoting hydrolytic cleavage of the triglyceride core of lipoproteins, is a crucial node in the management of plasma lipid levels. Although LPL expression and activity modulation is observed as a pleiotropic action of some the commonly used lipid lowering drugs, the deliberate development of drugs targeting LPL has not occurred yet. In this review, we present the biology of LPL, highlight the LPL modulation property of currently used drugs and review the novel emerging approaches to target LPL.
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Affiliation(s)
- Werner J Geldenhuys
- Department of Pharmaceutical Sciences, School of Pharmacy, West Virginia University, Morgantown, WV 26505, USA
| | - Li Lin
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH 44272, USA
| | - Altaf S Darvesh
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH 44272, USA
| | - Prabodh Sadana
- Department of Pharmaceutical Sciences, College of Pharmacy, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH 44272, USA.
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17
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Ryan TM, Griffin MDW, McGillivray DJ, Knott RB, Wood K, Masters CL, Kirby N, Curtain CC. Apolipoprotein C-II Adopts Distinct Structures in Complex with Micellar and Submicellar Forms of the Amyloid-Inhibiting Lipid-Mimetic Dodecylphosphocholine. Biophys J 2016; 110:85-94. [PMID: 26745412 PMCID: PMC4805880 DOI: 10.1016/j.bpj.2015.11.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/03/2015] [Accepted: 11/09/2015] [Indexed: 01/21/2023] Open
Abstract
The formation of amyloid deposits is a common feature of a broad range of diseases, including atherosclerosis, Alzheimer's disease, and Parkinson's disease. The basis and role of amyloid deposition in the pathogenesis of these diseases is still being defined, however an interesting feature of amyloidogenic proteins is that the majority of the pathologically associated proteins are involved in lipid homeostasis, be it in lipid transport, incorporation into membranes, or the regulation of lipid pathways. Thus, amyloid-forming proteins commonly bind lipids, and lipids are generally involved in the proper folding of these proteins. However, understanding of the basis for these lipid-related aspects of amyloidogenesis is lacking. Thus, we have used the apolipoprotein C-II amyloid model system in conjunction with x-ray and neutron scattering analyses to address this problem. Apolipoprotein C-II is a well-studied model system of systemic amyloid fibril formation, with a clear and well-defined pathway for fibril formation, where the effects of lipid interaction are characterized, particularly for the lipid mimetic dodecylphosphocholine. We show that the micellar state of an inhibitory lipid can have a very significant effect on protein conformation, with micelles stabilizing a particular α-helical structure, whereas submicellar lipids stabilize a very different dimeric, α-helical structure. These results indicate that lipids may have an important role in the development and progression of amyloid-related diseases.
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Affiliation(s)
- Timothy M Ryan
- Australian Synchrotron, Clayton, Victoria, Australia; The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia; The MacDiarmid Institute of Advanced Materials and Nanotechnology, Wellington, New Zealand.
| | - Michael D W Griffin
- Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Duncan J McGillivray
- School of Chemical Science, The University of Auckland, Auckland, New Zealand; The MacDiarmid Institute of Advanced Materials and Nanotechnology, Wellington, New Zealand
| | - Robert B Knott
- Australian Nuclear Science and Technology Organisation, New South Wales, Australia
| | - Kathleen Wood
- Australian Nuclear Science and Technology Organisation, New South Wales, Australia
| | - Colin L Masters
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Nigel Kirby
- Australian Synchrotron, Clayton, Victoria, Australia
| | - Cyril C Curtain
- The Florey Institute, The University of Melbourne, Parkville, Victoria, Australia
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18
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Morita SY. Metabolism and Modification of Apolipoprotein B-Containing Lipoproteins Involved in Dyslipidemia and Atherosclerosis. Biol Pharm Bull 2016; 39:1-24. [DOI: 10.1248/bpb.b15-00716] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Shin-ya Morita
- Department of Pharmacy, Shiga University of Medical Science Hospital
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19
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Rahimi M, Ng EP, Bakhtiari K, Vinciguerra M, Ahmad HA, Awala H, Mintova S, Daghighi M, Bakhshandeh Rostami F, de Vries M, Motazacker MM, Peppelenbosch MP, Mahmoudi M, Rezaee F. Zeolite Nanoparticles for Selective Sorption of Plasma Proteins. Sci Rep 2015; 5:17259. [PMID: 26616161 PMCID: PMC4663482 DOI: 10.1038/srep17259] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 10/23/2015] [Indexed: 12/30/2022] Open
Abstract
The affinity of zeolite nanoparticles (diameter of 8-12 nm) possessing high surface area and high pore volume towards human plasma proteins has been investigated. The protein composition (corona) of zeolite nanoparticles has been shown to be more dependent on the plasma protein concentrations and the type of zeolites than zeolite nanoparticles concentration. The number of proteins present in the corona of zeolite nanoparticles at 100% plasma (in vivo state) is less than with 10% plasma exposure. This could be due to a competition between the proteins to occupy the corona of the zeolite nanoparticles. Moreover, a high selective adsorption for apolipoprotein C-III (APOC-III) and fibrinogen on the zeolite nanoparticles at high plasma concentration (100%) was observed. While the zeolite nanoparticles exposed to low plasma concentration (10%) exhibited a high selective adsorption for immunoglobulin gamma (i.e. IGHG1, IGHG2 and IGHG4) proteins. The zeolite nanoparticles can potentially be used for selectively capture of APOC-III in order to reduce the activation of lipoprotein lipase inhibition during hypertriglyceridemia treatment. The zeolite nanoparticles can be adapted to hemophilic patients (hemophilia A (F-VIII deficient) and hemophilia B (F-IX deficient)) with a risk of bleeding, and thus might be potentially used in combination with the existing therapy.
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Affiliation(s)
- M. Rahimi
- Faculty of Science, University of Groningen, University Medical Center Groningen, Groningen, the Netherlands
| | - E.-P. Ng
- School of Chemical Sciences, University Sains Malaysia, 11800 USM, Malaysia
| | - K. Bakhtiari
- Department of Plasma Proteins, Sanquin Research, Amsterdam, The Netherlands
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam, the Netherlands
| | - M. Vinciguerra
- Institute for Liver and Digestive Health, Division of Medicine, University College London (UCL), London, United Kingdom
| | - H. Ali Ahmad
- Laboratory of Catalysis and Spectroscopy, ENSICAEN, University of Caen, CNRS, 6 Boulevard du Maréchal Juin, 14050 Caen, France
| | - H. Awala
- Laboratory of Catalysis and Spectroscopy, ENSICAEN, University of Caen, CNRS, 6 Boulevard du Maréchal Juin, 14050 Caen, France
| | - S. Mintova
- Laboratory of Catalysis and Spectroscopy, ENSICAEN, University of Caen, CNRS, 6 Boulevard du Maréchal Juin, 14050 Caen, France
| | - M. Daghighi
- University of Groningen, University Medical Center Groningen, Department Bioengineering, Groningen, the Netherlands
| | | | - M. de Vries
- University of Groningen, University Medical Center Groningen, Department Cell Biology, Department medical proteomics, Groningen, the Netherlands
| | - M. M. Motazacker
- Department of Clinical Genetics, Academic Medical Center, Amsterdam, the Netherlands
| | - M. P. Peppelenbosch
- Department of Gastroenterology and Hepatology, Erasmus Medical Center, Rotterdam, the Netherlands
| | - M. Mahmoudi
- Division of Cardiovascular Medicine, School of Medicine, Stanford University, Stanford, California, USA
- Cardiovascular Institute, School of Medicine, Stanford University, Stanford, California, USA
| | - F. Rezaee
- University of Groningen, University Medical Center Groningen, Department Cell Biology, Department medical proteomics, Groningen, the Netherlands
- Department of Gastroenterology and Hepatology, Erasmus Medical Center, Rotterdam, the Netherlands
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20
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Sakurai T, Sakurai A, Vaisman BL, Amar MJ, Liu C, Gordon SM, Drake SK, Pryor M, Sampson ML, Yang L, Freeman LA, Remaley AT. Creation of Apolipoprotein C-II (ApoC-II) Mutant Mice and Correction of Their Hypertriglyceridemia with an ApoC-II Mimetic Peptide. J Pharmacol Exp Ther 2015; 356:341-53. [PMID: 26574515 DOI: 10.1124/jpet.115.229740] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 11/11/2015] [Indexed: 12/31/2022] Open
Abstract
Apolipoprotein C-II (apoC-II) is a cofactor for lipoprotein lipase, a plasma enzyme that hydrolyzes triglycerides (TGs). ApoC-II deficiency in humans results in hypertriglyceridemia. We used zinc finger nucleases to create Apoc2 mutant mice to investigate the use of C-II-a, a short apoC-II mimetic peptide, as a therapy for apoC-II deficiency. Mutant mice produced a form of apoC-II with an uncleaved signal peptide that preferentially binds high-density lipoproteins (HDLs) due to a 3-amino acid deletion at the signal peptide cleavage site. Homozygous Apoc2 mutant mice had increased plasma TG (757.5 ± 281.2 mg/dl) and low HDL cholesterol (31.4 ± 14.7 mg/dl) compared with wild-type mice (TG, 55.9 ± 13.3 mg/dl; HDL cholesterol, 55.9 ± 14.3 mg/dl). TGs were found in light (density < 1.063 g/ml) lipoproteins in the size range of very-low-density lipoprotein and chylomicron remnants (40-200 nm). Intravenous injection of C-II-a (0.2, 1, and 5 μmol/kg) reduced plasma TG in a dose-dependent manner, with a maximum decrease of 90% occurring 30 minutes after the high dose. Plasma TG did not return to baseline until 48 hours later. Similar results were found with subcutaneous or intramuscular injections. Plasma half-life of C-II-a is 1.33 ± 0.72 hours, indicating that C-II-a only acutely activates lipolysis, and the sustained TG reduction is due to the relatively slow rate of new TG-rich lipoprotein synthesis. In summary, we describe a novel mouse model of apoC-II deficiency and show that an apoC-II mimetic peptide can reverse the hypertriglyceridemia in these mice, and thus could be a potential new therapy for apoC-II deficiency.
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Affiliation(s)
- Toshihiro Sakurai
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Akiko Sakurai
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Boris L Vaisman
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Marcelo J Amar
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Chengyu Liu
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Scott M Gordon
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Steven K Drake
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Milton Pryor
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Maureen L Sampson
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Ling Yang
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Lita A Freeman
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute (T.S., A.S., B.L.V., M.J.A., C.L., S.M.G., M.P., L.A.F., A.T.R.), Transgenic Core Facility, National Heart, Lung, and Blood Institute (C.L.), Department of Laboratory Medicine, Clinical Center (M.L.S., A.T.R.), Critical Care Medicine Department, Clinical Center (S.K.D.), and Laboratory of Obesity and Metabolic Diseases, National Heart, Lung, and Blood Institute (L.Y.), National Institutes of Health, Bethesda, Maryland
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Lipase-Secreting Bacillus Species in an Oil-Contaminated Habitat: Promising Strains to Alleviate Oil Pollution. BIOMED RESEARCH INTERNATIONAL 2015; 2015:820575. [PMID: 26180812 PMCID: PMC4477129 DOI: 10.1155/2015/820575] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 02/04/2015] [Indexed: 11/17/2022]
Abstract
Lipases are of great interest for different industrial applications due to their diversity and versatility. Among different lipases, microbial lipases are preferable due to their broad substrate specificity, and higher stability with lower production costs compared to the lipases from plants and animals. In the past, a vast number of bacterial species have been reported as potential lipases producers. In this study, the lipases-producing bacterial species were isolated from an oil spillage area in the conventional night market. Isolated species were identified as Bacillus species by biochemical tests which indicate their predominant establishment, and further screened on the agar solid surfaces using lipid and gelatin as the substrates. Out of the ten strains tested, four potential strains were subjected to comparison analysis of the lipolytic versus proteolytic activities. Strain 10 exhibited the highest lipolytic and proteolytic activity. In all the strains, the proteolytic activity is higher than the lipolytic activity except for strain 8, suggesting the possibility for substrate-based extracellular gene induction. The simultaneous secretion of both the lipase and protease is a mean of survival. The isolated bacterial species which harbour both lipase and protease enzymes could render potential industrial-based applications and solve environmental issues.
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22
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Meyers NL, Larsson M, Olivecrona G, Small DM. A Pressure-dependent Model for the Regulation of Lipoprotein Lipase by Apolipoprotein C-II. J Biol Chem 2015; 290:18029-18044. [PMID: 26026161 DOI: 10.1074/jbc.m114.629865] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Indexed: 12/31/2022] Open
Abstract
Apolipoprotein C-II (apoC-II) is the co-factor for lipoprotein lipase (LPL) at the surface of triacylglycerol-rich lipoproteins. LPL hydrolyzes triacylglycerol, which increases local surface pressure as surface area decreases and amphipathic products transiently accumulate at the lipoprotein surface. To understand how apoC-II adapts to these pressure changes, we characterized the behavior of apoC-II at multiple lipid/water interfaces. ApoC-II adsorption to a triacylglycerol/water interface resulted in large increases in surface pressure. ApoC-II was exchangeable at this interface and desorbed on interfacial compressions. These compressions increase surface pressure and mimic the action of LPL. Analysis of gradual compressions showed that apoC-II undergoes a two-step desorption, which indicates that lipid-bound apoC-II can exhibit at least two conformations. We characterized apoC-II at phospholipid/triacylglycerol/water interfaces, which more closely mimic lipoprotein surfaces. ApoC-II had a large exclusion pressure, similar to that of apoC-I and apoC-III. However, apoC-II desorbed at retention pressures higher than those seen with the other apoCs. This suggests that it is unlikely that apoC-I and apoC-III inhibit LPL via displacement of apoC-II from the lipoprotein surface. Upon rapid compressions and re-expansions, re-adsorption of apoC-II increased pressure by lower amounts than its initial adsorption. This indicates that apoC-II removed phospholipid from the interface upon desorption. These results suggest that apoC-II regulates the activity of LPL in a pressure-dependent manner. ApoC-II is provided as a component of triacylglycerol-rich lipoproteins and is the co-factor for LPL as pressure increases. Above its retention pressure, apoC-II desorbs and removes phospholipid. This triggers release of LPL from lipoproteins.
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Affiliation(s)
- Nathan L Meyers
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118
| | - Mikael Larsson
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden; Department of Medicine, UCLA, Los Angeles, California 90095
| | - Gunilla Olivecrona
- Department of Medical Biosciences/Physiological Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Donald M Small
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, Massachusetts 02118.
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The Role of Lipid in Misfolding and Amyloid Fibril Formation by Apolipoprotein C-II. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 855:157-74. [DOI: 10.1007/978-3-319-17344-3_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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Amar MJA, Sakurai T, Sakurai-Ikuta A, Sviridov D, Freeman L, Ahsan L, Remaley AT. A novel apolipoprotein C-II mimetic peptide that activates lipoprotein lipase and decreases serum triglycerides in apolipoprotein E-knockout mice. J Pharmacol Exp Ther 2014; 352:227-35. [PMID: 25395590 DOI: 10.1124/jpet.114.220418] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Apolipoprotein A-I (apoA-I) mimetic peptides are currently being developed as possible new agents for the treatment of cardiovascular disease based on their ability to promote cholesterol efflux and their other beneficial antiatherogenic properties. Many of these peptides, however, have been reported to cause transient hypertriglyceridemia due to inhibition of lipolysis by lipoprotein lipase (LPL). We describe a novel bihelical amphipathic peptide (C-II-a) that contains an amphipathic helix (18A) for binding to lipoproteins and stimulating cholesterol efflux as well as a motif based on the last helix of apolipoprotein C-II (apoC-II) that activates lipolysis by LPL. The C-II-a peptide promoted cholesterol efflux from ATP-binding cassette transporter ABCA1-transfected BHK cells similar to apoA-I mimetic peptides. Furthermore, it was shown in vitro to be comparable to the full-length apoC-II protein in activating lipolysis by LPL. When added to serum from a patient with apoC-II deficiency, it restored normal levels of LPL-induced lipolysis and also enhanced lipolysis in serum from patients with type IV and V hypertriglyceridemia. Intravenous injection of C-II-a (30 mg/kg) in apolipoprotein E-knockout mice resulted in a significant reduction of plasma cholesterol and triglycerides of 38 ± 6% and 85 ± 7%, respectively, at 4 hours. When coinjected with the 5A peptide (60 mg/kg), the C-II-a (30 mg/kg) peptide was found to completely block the hypertriglyceridemic effect of the 5A peptide in C57Bl/6 mice. In summary, C-II-a is a novel peptide based on apoC-II, which promotes cholesterol efflux and lipolysis and may therefore be useful for the treatment of apoC-II deficiency and other forms of hypertriglyceridemia.
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Affiliation(s)
- Marcelo J A Amar
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Toshihiro Sakurai
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Akiko Sakurai-Ikuta
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Denis Sviridov
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Lita Freeman
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Lusana Ahsan
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Cardio-Pulmonary Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
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Yamamoto H, Tanaka M, Yoshiga S, Funahashi T, Shimomura I, Kihara S. Autoimmune severe hypertriglyceridemia induced by anti-apolipoprotein C-II antibody. J Clin Endocrinol Metab 2014; 99:1525-30. [PMID: 24606081 DOI: 10.1210/jc.2013-3619] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Among type V hyperlipoproteinemias, only one-fourth of the patients have genetic defects in lipoprotein lipase (LPL) or in its associated molecules; the exact mechanism in other patients is usually unknown. OBJECTIVE The aim of the study was to report a case of severe hypertriglyceridemia induced by anti-apolipoprotein (apo) C-II autoantibody and to clarify its pathogenesis. SUBJECT AND METHODS A 29-year-old Japanese woman presented with severe persistent hypertriglyceridemia since the age of 20 years. The past history was negative for acute pancreatitis, eruptive xanthomas, or lipemia retinalis. LPL mass and activities were normal. Plasma apo C-II levels were extremely low, but no mutation was observed in APOC2. RESULTS Apo C-II protein was detected in the serum by immunoprecipitation and Western blotting. Large amounts of IgG and IgM were incorporated with apo C-II protein coimmunoprecipitated by anti-apo C-II antibody. IgG, but not IgM, purified from the serum prevented interaction of apo C-II with lipid substrate and diminished LPL hydrolysis activity. CONCLUSION We identified anti-apo C-II antibody in a myeloma-unrelated severe hypertriglyceridemic patient. In vitro analysis confirmed that the autoantibody disrupted the interaction between apo C-II and lipid substrate, suggesting the etiological role of anti-apo C-II antibody in severe hypertriglyceridemia in this patient.
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Affiliation(s)
- Hiroyasu Yamamoto
- Department of Biomedical Informatics, Division of Health Sciences (H.Y., M.T., S.Y., S.K.), and Department of Metabolic Medicine (T.F., I.S.), Osaka University Graduate School of Medicine, 565-0871 Osaka, Japan
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Rundqvist L, Tengel T, Zdunek J, Björn E, Schleucher J, Alcocer MJC, Larsson G. Solution structure, copper binding and backbone dynamics of recombinant Ber e 1-the major allergen from Brazil nut. PLoS One 2012; 7:e46435. [PMID: 23056307 PMCID: PMC3464261 DOI: 10.1371/journal.pone.0046435] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Accepted: 08/29/2012] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The 2S albumin Ber e 1 is the major allergen in Brazil nuts. Previous findings indicated that the protein alone does not cause an allergenic response in mice, but the addition of components from a Brazil nut lipid fraction were required. Structural details of Ber e 1 may contribute to the understanding of the allergenic properties of the protein and its potential interaction partners. METHODOLOGY/PRINCIPAL FINDINGS The solution structure of recombinant Ber e 1 was solved using NMR spectroscopy and measurements of the protein back bone dynamics at a residue-specific level were extracted using (15)N-spin relaxation. A hydrophobic cavity was identified in the structure of Ber e 1. Using the paramagnetic relaxation enhancement property of Cu(2+) in conjunction with NMR, it was shown that Ber e 1 is able to specifically interact with the divalent copper ion and the binding site was modeled into the structure. The IgE binding region as well as the copper binding site show increased dynamics on both fast ps-ns timescale as well as slower µs-ms timescale. CONCLUSIONS/SIGNIFICANCE The overall fold of Ber e 1 is similar to other 2S albumins, but the hydrophobic cavity resembles that of a homologous non-specific lipid transfer protein. Ber e 1 is the first 2S albumin shown to interact with Cu(2+) ions. This Cu(2+) binding has minimal effect on the electrostatic potential on the surface of the protein, but the charge distribution within the hydrophobic cavity is significantly altered. As the hydrophobic cavity is likely to be involved in a putative lipid interaction the Cu(2+) can in turn affect the interaction that is essential to provoke an allergenic response.
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Affiliation(s)
- Louise Rundqvist
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Tobias Tengel
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Janusz Zdunek
- Protein Constructor Developers Company, Umeå, Sweden
| | - Erik Björn
- Department of Chemistry, Umeå University, Umeå, Sweden
| | - Jürgen Schleucher
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Marcos J. C. Alcocer
- Department of Nutritional Sciences, University of Nottingham, Loughborough, United Kingdom
| | - Göran Larsson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
- * E-mail:
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Kei AA, Filippatos TD, Tsimihodimos V, Elisaf MS. A review of the role of apolipoprotein C-II in lipoprotein metabolism and cardiovascular disease. Metabolism 2012; 61:906-21. [PMID: 22304839 DOI: 10.1016/j.metabol.2011.12.002] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Revised: 12/06/2011] [Accepted: 12/08/2011] [Indexed: 12/21/2022]
Abstract
The focus of this review is on the role of apolipoprotein C-II (apoC-II) in lipoprotein metabolism and the potential effects on the risk of cardiovascular disease (CVD). We searched PubMed/Scopus for articles regarding apoC-II and its role in lipoprotein metabolism and the risk of CVD. Apolipoprotein C-II is a constituent of chylomicrons, very low-density lipoprotein, low-density lipoprotein, and high-density lipoprotein (HDL). Apolipoprotein C-II contains 3 amphipathic α-helices. The lipid-binding domain of apoC-II is located in the N-terminal, whereas the C-terminal helix of apoC-II is responsible for the interaction with lipoprotein lipase (LPL). At intermediate concentrations (approximately 4 mg/dL) and in normolipidemic subjects, apoC-II activates LPL. In contrast, both an excess and a deficiency of apoC-II are associated with reduced LPL activity and hypertriglyceridemia. Furthermore, excess apoC-II has been associated with increased triglyceride-rich particles and alterations in HDL particle distribution, factors that may increase the risk of CVD. However, there is not enough current evidence to clarify whether increased apoC-II causes hypertriglyceridemia or is an epiphenomenon reflecting hypertriglyceridemia. A number of pharmaceutical interventions, including statins, fibrates, ezetimibe, nicotinic acid, and orlistat, have been shown to reduce the increased apoC-II concentrations. An excess of apoC-II is associated with increased triglyceride-rich particles and alterations in HDL particle distribution. However, prospective trials are needed to assess if apoC-II is a CVD marker or a risk factor in high-risk patients.
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Affiliation(s)
- Anastazia A Kei
- Department of Internal Medicine, School of Medicine, University of Ioannina, 45 110 Ioannina, Greece
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Shen Y, Lookene A, Zhang L, Olivecrona G. Site-directed mutagenesis of apolipoprotein CII to probe the role of its secondary structure for activation of lipoprotein lipase. J Biol Chem 2009; 285:7484-92. [PMID: 20042600 DOI: 10.1074/jbc.m109.022046] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Apolipoprotein CII (apoCII) is a necessary activator for lipoprotein lipase (LPL). We had identified four residues (Tyr-63, Ile-66, Asp-69, and Gln-70), presumably contained in an alpha-helix, as a potential binding site for LPL. We have now used structure prediction, mutagenesis, and functional assays to explore the functional role of the secondary structure in this part of apoCII. First, mutants were generated by replacements with proline residues to disturb the helical structure. Activation by mutant G65P was reduced by 30%, whereas mutant S54P retained activation ability. Mutants V71P and L72P should be located outside the LPL-binding site, but V71P was totally inactive, whereas activation by L72P was reduced by 65%. Insertion of alanine after Tyr-63, changing the position of the putative LPL-binding site in relation to the hydrophobic face of the alpha-helix, also severely impeded the activation ability, and a double mutant (Y63A/I66A) was completely inactive. Next, to investigate the importance of conserved hydrophobic residues in the C-terminal end of apoCII, Phe-67, Val-71, Leu-72, and Leu-75 were exchanged for polar residues. Only F67S showed dramatic loss of function. Finally, fragment 39-62, previously claimed to activate LPL, was found to be completely inactive. Our data support the view that the helical structure close to the C-terminal end of apoCII is important for activation of LPL, probably by placing residues 63, 66, 69, and 70 in an optimal steric position. The structural requirements for the hydrophobic face on the back side of this helix and further out toward the C terminus were less stringent.
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Affiliation(s)
- Yan Shen
- Department of Medical Biosciences, Physiological Chemistry, Umeå University, SE-90 187 Umeå, Sweden
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Hung A, Griffin MDW, Howlett GJ, Yarovsky I. Lipids Enhance Apolipoprotein C-II-Derived Amyloidogenic Peptide Oligomerization but Inhibit Fibril Formation. J Phys Chem B 2009; 113:9447-53. [DOI: 10.1021/jp901051n] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Andrew Hung
- School of Applied Sciences, RMIT University, GPO Box 2476 V, Victoria 3001, Australia, and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Michael D. W. Griffin
- School of Applied Sciences, RMIT University, GPO Box 2476 V, Victoria 3001, Australia, and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Geoffrey J. Howlett
- School of Applied Sciences, RMIT University, GPO Box 2476 V, Victoria 3001, Australia, and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Irene Yarovsky
- School of Applied Sciences, RMIT University, GPO Box 2476 V, Victoria 3001, Australia, and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne, Victoria 3010, Australia
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Hung A, Griffin MDW, Howlett GJ, Yarovsky I. Effects of oxidation, pH and lipids on amyloidogenic peptide structure: implications for fibril formation? EUROPEAN BIOPHYSICS JOURNAL: EBJ 2008; 38:99-110. [PMID: 18769912 DOI: 10.1007/s00249-008-0363-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2008] [Revised: 08/01/2008] [Accepted: 08/04/2008] [Indexed: 10/21/2022]
Abstract
We have performed experimental and computational studies to investigate the influences of phospholipids, methionine oxidation and acidic pH on amyloid fibril formation by a peptide derived from human apolipoprotein C-II (apoC-II), a known component of proteinaceous atherosclerotic plaques. Fibril growth monitored by thioflavin T fluorescence revealed inhibition under lipid-rich and oxidising conditions. We subsequently performed fully-solvated atomistic molecular dynamics (MD) simulations of the peptide monomer to study its conformations under both fibril favouring (neutral and low pH) and inhibiting (lipid-rich and oxidising) conditions. Examination of the chain topology, backbone hydrogen-bonding patterns and aromatic sidechain orientations of the peptide under different conditions reveals that, while the peptide adopts similar structures under the fibril-favouring conditions, significantly different structures are obtained under fibril-disruptive conditions. Based on our results, we advance hypotheses for the roles of peptide conformation on aggregation and fibrillisation propensities.
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Affiliation(s)
- Andrew Hung
- School of Applied Sciences, RMIT University, GPO Box 2476V, Melbourne, VIC 3001, Australia
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Gangabadage CS, Zdunek J, Tessari M, Nilsson S, Olivecrona G, Wijmenga SS. Structure and Dynamics of Human Apolipoprotein CIII. J Biol Chem 2008; 283:17416-27. [DOI: 10.1074/jbc.m800756200] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Jarymowycz VA, Stone MJ. Fast time scale dynamics of protein backbones: NMR relaxation methods, applications, and functional consequences. Chem Rev 2007; 106:1624-71. [PMID: 16683748 DOI: 10.1021/cr040421p] [Citation(s) in RCA: 342] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Virginia A Jarymowycz
- Department of Chemistry and Interdisciplinary Biochemistry Program, Indiana University, Bloomington, Indiana 47405-0001, USA
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Surface rheology and adsorption kinetics reveal the relative amphiphilicity, interfacial activity, and stability of human exchangeable apolipoproteins. Biophys J 2007; 94:1735-45. [PMID: 17993480 DOI: 10.1529/biophysj.107.115220] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Exchangeable apolipoproteins are located in the surface of lipoprotein particles and regulate lipid metabolism through direct protein-protein and protein-lipid interactions. These proteins are characterized by the presence of tandem repeats of amphiphatic alpha-helix segments and a high surface activity in monolayers and lipoprotein surfaces. A noteworthy aspect in the description of the function of exchangeable apolipoproteins is the requirement of a quantitative account of the relation between their physicochemical and structural characteristics and changes in the mesoscopic system parameters such as the maximum surface pressure and relative stability at interfaces. To comply with this demand, we set out to establish the relations among alpha-helix amphiphilicity, surface concentration, and surface rheology of apolipoproteins ApoA-I, ApoA-II, ApoC-I, ApoC-II, and ApoC-III adsorbed at the air-water interface. Our studies render further insights into the interfacial properties of exchangeable apolipoproteins, including the kinetics of their adsorption and the physical properties of the interfacial layer.
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Chappuis B, Braun M, Stettler C, Allemann S, Diem P, Lumb PJ, Wierzbicki AS, James R, Christ ER. Differential effect of pioglitazone (PGZ) and rosiglitazone (RGZ) on postprandial glucose and lipid metabolism in patients with type 2 diabetes mellitus: a prospective, randomized crossover study. Diabetes Metab Res Rev 2007; 23:392-9. [PMID: 17211855 DOI: 10.1002/dmrr.715] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
BACKGROUND Postprandial metabolism is impaired in patients with type 2 diabetes (T2Dm). Two thiazolidinediones pioglitazone (PGZ) and rosiglitazone (RGZ) have similar effects on glycaemic control but differ in their effects on fasting lipids. This study investigated the effects of RGZ and PGZ on postprandial metabolism in a prospective, randomized crossover trial. METHODS Seventeen patients with T2Dm were randomized to RGZ or PGZ for 12 weeks, with an 8-week wash-out period. Fasting blood samples were taken for glucose (FPG), insulin, HbA(1c), lipids, apolipoproteins (apo), lipoprotein (LPL) and hepatic lipase (HL), and cholesterol ester transfer protein (CETP) activity. A standardized breakfast was served and postprandial glucose, insulin, and lipid subfraction profiles were determined. RESULTS RGZ and PGZ treatment resulted in a similar improvement in FPG, HbA(1c) and homeostasis model assessment. Fasting and postprandial triglyceride (TG) levels were significantly lower following PGZ therapy (fasting: -0.35 vs 0.44 mmol/L; p < 0.04; postprandial AUC-TG: -195.6 vs 127.9 mmol/L/min; p < 0.02) associated with changes in VLDL-2-TG (-0.10 vs 0.21 mmol/L; p = 0.23) and VLDL-3-TG (0.0 vs 0.34 mmol/L; p < 0.04). Fasting cholesterol increased with RGZ compared to PGZ (0.06 vs 0.59 mmol/L; p < 0.04), particularly in VLDL-2-C (-0.30 vs 0.59 mmol/L; p < 0.03) and VLDL-3-C (-0.85 vs 2.11 mmol/L; p < 0.02). Postprandial VLDL lipid and protein content increased after RGZ and decreased after PGZ. Fasting apoB, apoA-I, apoC-II/C-III-ratio, and LPL activity did not differ. CETP activity decreased after RGZ and increased after PGZ (-6.2 vs 4.2 p/mol/mL/min; p < 0.002). CONCLUSIONS Both the glitazones had similar effects on glucose metabolism. The additional beneficial effect of PGZ on lipid metabolism may be related to its effects on insulin-independent VLDL production and CETP activity.
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Affiliation(s)
- Bernard Chappuis
- Division of Endocrinology, Diabetes and Clinical Nutrition, University Hospital of Berne, Inselspital, CH-3010 Bern, Switzerland
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Kostapanos MS, Milionis HJ, Filippatos TD, Nakou ES, Bairaktari ET, Tselepis AD, Elisaf MS. A 12-Week, Prospective, Open-Label Analysis of the Effect of Rosuvastatin on Triglyceride-Rich Lipoprotein Metabolism in Patients with Primary Dyslipidemia. Clin Ther 2007; 29:1403-14. [PMID: 17825691 DOI: 10.1016/j.clinthera.2007.07.019] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/12/2007] [Indexed: 11/16/2022]
Abstract
BACKGROUND Although the effect of statins on lowering low-density lipoprotein cholesterol (LDL-C) has been extensively studied, their hypotriglyceridemic capacity is not fully understood. OBJECTIVE The present study examined clinical and laboratory factors potentially associated with the triglyceride (TG)-lowering effect of rosuvastatin. METHODS Eligible patients had primary dyslipidemia and a moderate risk of heart disease. Patients were prescribed rosuvastatin 10 mg/d in an open-label fashion and kept 3-day food diaries. Laboratory measurements, performed at baseline and 12 weeks, included serum lipid parameters (total cholesterol [TC], TGs, LDL-C, high-density lipoprotein cholesterol [HDL-C], and apolipoprotein [apo] levels), non-lipid metabolic variables (including carbohydrate metabolism parameters and renal, liver, and thyroid function tests), and LDL-subfraction profile (by high-resolution 3% polyacrylamide gel electrophoresis). Tolerability was assessed at each visit. RESULTS Participants were 75 hyperlipidemic patients (39 men and 36 women; mean age, 51.7 years). At 12 weeks, TC levels were reduced by 35.1% (P < 0.001), TGs by 15.2% (P < 0.001), LDL-C by 48.5% (P < 0.001), apoE by 35.4% (P < 0.001), and apoE by 17.3% (P < 0.001) from baseline, whereas HDL-C and apoA1 levels were not significantly changed. Stepwise linear regression analysis showed that baseline TG levels were most significantly correlated (R(2) = 42.0%; P < 0.001) with the TG-lowering effect of rosuvastatin, followed by the reduction in apoCIII levels (R(2) = 13.6%; P < 0.01). Rosuvastatin use was associated with a reduction in cholesterol mass of both large LDL particles (mean [SD], from 150.5 [36.6] to 90.5 [24.3] mg/dL; P < 0.001) and small, dense LDL (sdLDL) particles (from 11.5 [8.4] to 6.6 [4.5] mg/dL; P < 0.001). Rosuvastatin had no effect on cholesterol distribution of the LDL subfractions (mean [SD], large particles, from 90.8% [7.0%] to 91.8% [5.1%]; sdLDL, from 7.1% [4.7%] to 7.5% [4.8%]) or the mean LDL particle size (from 26.5 [4.2] to 26.6 [4.0] rim). A significant increase in mean LDL particle size after rosuvastatin treatment (mean [SD], from 26.4 [0.4] to 26.9 [0.4] rim; P = 0.02) was observed only in patients with baseline TG levels > or =120 mg/dL. No serious adverse events requiring study treatment discontinuation were reported. One patient who presented with headache and 2 patients who presented with fatigue quickly recovered without discontinuing rosuvastatin treatment. A posttreatment elevation in aminotransferase levels <3-fold the upper limit of normal (ULN) was recorded in 5 (6.7%) patients, and 2 (2.7%) patients experienced elevated creatine kinase concentrations <5-fold ULN. CONCLUSION Baseline TG levels were the most important independent variable associated with the TG-lowering effect of rosuvastatin.
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Affiliation(s)
- Michael S Kostapanos
- Department of Internal Medicine, School of Medicine, University of Ioannina, Ioannina, Greece
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Lass A, Zimmermann R, Haemmerle G, Riederer M, Schoiswohl G, Schweiger M, Kienesberger P, Strauss JG, Gorkiewicz G, Zechner R. Adipose triglyceride lipase-mediated lipolysis of cellular fat stores is activated by CGI-58 and defective in Chanarin-Dorfman Syndrome. Cell Metab 2006; 3:309-19. [PMID: 16679289 DOI: 10.1016/j.cmet.2006.03.005] [Citation(s) in RCA: 667] [Impact Index Per Article: 37.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 03/15/2006] [Accepted: 03/17/2006] [Indexed: 12/23/2022]
Abstract
Adipose triglyceride lipase (ATGL) was recently identified as an important triacylglycerol (TG) hydrolase promoting the catabolism of stored fat in adipose and nonadipose tissues. We now demonstrate that efficient ATGL enzyme activity requires activation by CGI-58. Mutations in the human CGI-58 gene are associated with Chanarin-Dorfman Syndrome (CDS), a rare genetic disease where TG accumulates excessively in multiple tissues. CGI-58 interacts with ATGL, stimulating its TG hydrolase activity up to 20-fold. Alleles of CGI-58 carrying point mutations associated with CDS fail to activate ATGL. Moreover, CGI-58/ATGL coexpression attenuates lipid accumulation in COS-7 cells. Antisense RNA-mediated reduction of CGI-58 expression in 3T3-L1 adipocytes inhibits TG mobilization. Finally, expression of functional CGI-58 in CDS fibroblasts restores lipolysis and reverses the abnormal TG accumulation typical for CDS. These data establish an important biochemical function for CGI-58 in the lipolytic degradation of fat, implicating this lipolysis activator in the pathogenesis of CDS.
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Affiliation(s)
- Achim Lass
- Institute of Molecular Biosciences, University of Graz, Heinrichstrasse 31, A-8010 Graz, Austria
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Langham AA, Kaznessis YN. Effects of mutations on the C-terminus of protegrin-1: a molecular dynamics simulation study. MOLECULAR SIMULATION 2006. [DOI: 10.1080/08927020600612205] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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38
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Lam CW, Yuen YP, Cheng WF, Chan YW, Tong SF. Missense mutation Leu72Pro located on the carboxyl terminal amphipathic helix of apolipoprotein C-II causes familial chylomicronemia syndrome. Clin Chim Acta 2006; 364:256-9. [PMID: 16153625 DOI: 10.1016/j.cca.2005.07.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2005] [Revised: 07/15/2005] [Accepted: 07/18/2005] [Indexed: 11/25/2022]
Abstract
BACKGROUND Chylomicronemia syndrome can be caused by 2 autosomal recessive disorders - lipoprotein lipase (LPL) deficiency and apolipoprotein C-II (apo C-II) deficiency. METHODS We described 2 siblings with chylomicronemia syndrome of a consanguineous family. To determine the molecular basis of chylomicronemia syndrome in this family, we performed direct DNA sequencing of the LPL and APOC2 genes of the proband. RESULTS A novel homozygous mutation, Leu72Pro, in the APOC2 gene was found in both siblings whereas their parents were carriers. No LPL mutations were detected in the siblings. Apo C-II contains 3 amphipathic alpha helices; the C-terminal alpha helix is composed of residues 64 to 74. Substitution of residue 72 from a helix former leucine to a helix breaker, proline, is predicted to change the secondary structure of the C-terminal helix and subsequently alter the interaction between apo C-II and LPL. CONCLUSIONS To our knowledge, Leu72Pro is the first missense mutation identified in the C-terminal of apo C-II. The result is consistent with the current biochemical and structural findings that the C-terminal helix of apo C-II is important for activation of LPL.
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Affiliation(s)
- Ching-Wan Lam
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Hong Kong, China.
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Langham AA, Khandelia H, Kaznessis YN. How can a β-sheet peptide be both a potent antimicrobial and harmfully toxic? Molecular dynamics simulations of protegrin-1 in micelles. Biopolymers 2006; 84:219-31. [PMID: 16235232 DOI: 10.1002/bip.20397] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In this work, the naturally occurring beta-hairpin antimicrobial peptide protegrin-1 (PG-1) is studied by molecular dynamics simulation in all-atom sodium dodecylsulfate and dodecylphosphocholine micelles. These simulations provide a high-resolution picture of the interactions between the peptide and simple models of bacterial and mammalian membranes. Both micelles show significant disruption, as is expected for a peptide that is both active against bacteria and toxic to host cells. There is, however, clear differentiation between the behavior in SDS versus DPC, which suggests different mechanisms of interaction for PG-1 with mammalian and bacterial membranes. Specifically, the equilibrium orientation of the peptide relative to SDS is a mirror image of its position relative to DPC. In both systems, the arginine residues of PG-1 strongly interact with the head groups of the micelles. In DPC, the peptide prefers a location closer to the core of the micelle with Phe12, Val14, and Val16 imbedded in the core and the other side of the hairpin, which includes Leu5 and Tyr7, located closer to the surface of the micelle. In SDS, the peptide prefers a location at the micelle-water interface. The peptide position is reversed, with Leu5 and Cys6 imbedded furthest in the micelle core and Phe12, Val14, and Val16 on the surface of the micelle. We discuss the implications of these results with respect to activity and toxicity.
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Affiliation(s)
- Allison A Langham
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA
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Larsson G, Schleucher J, Onions J, Hermann S, Grundström T, Wijmenga SS. Backbone dynamics of a symmetric calmodulin dimer in complex with the calmodulin-binding domain of the basic-helix-loop-helix transcription factor SEF2-1/E2-2: a highly dynamic complex. Biophys J 2005; 89:1214-26. [PMID: 15894636 PMCID: PMC1366606 DOI: 10.1529/biophysj.104.055780] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2004] [Accepted: 05/04/2005] [Indexed: 11/18/2022] Open
Abstract
Calmodulin (CaM) interacts specifically as a dimer with some dimeric basic-Helix-Loop-Helix (bHLH) transcription factors via a novel high affinity binding mode. Here we report a study of the backbone dynamics by (15)N-spin relaxation on the CaM dimer in complex with a dimeric peptide that mimics the CaM binding region of the bHLH transcription factor SEF2-1. The relaxation data were measured at multiple magnetic fields, and analyzed in a model-free manner using in-house written software designed to detect nanosecond internal motion. Besides picosecond motions, all residues also experience internal motion with an effective correlation time of approximately 2.5 ns with squared order parameter (S(2)) of approximately 0.75. Hydrodynamic calculations suggest that this can be attributed to motions of the N- and C-terminal domains of the CaM dimer in the complex. Moreover, residues with significant exchange broadening are found. They are clustered in the CaM:SEF2-1mp binding interface, the CaM:CaM dimer interface, and in the flexible helix connecting the CaM N- and C-terminal domains, and have similar exchange times (approximately 50 micros), suggesting a cooperative mechanism probably caused by protein:protein interactions. The dynamic features presented here support the conclusion that the conformationally heterogeneous bHLH mimicking peptide trapped inside the CaM dimer exchanges between different binding sites on both nanosecond and microsecond timescales. Nature has thus found a way to specifically recognize a relatively ill-fitting target. This novel mode of target-specific binding, which neither belongs to lock-and-key nor induced-fit binding, is characterized by dimerization and continuous exchange between multiple flexible binding alternatives.
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Affiliation(s)
- Göran Larsson
- Department of Medical Biochemistry and Biophysics, University of Umeå, Sweden
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41
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Abstract
PURPOSE OF REVIEW The lipolytic catabolism of stored fat in adipose tissue supplies tissues with fatty acids as metabolites and energy substrates during times of food deprivation. This review focuses on the function of recently discovered enzymes in adipose tissue lipolysis and fatty acid mobilization. RECENT FINDINGS The characterization of hormone-sensitive lipase-deficient mice provided compelling evidence that hormone-sensitive lipase is not uniquely responsible for the hydrolysis of triacylglycerols and diacylglycerols of stored fat. Recently, three different laboratories independently discovered a novel enzyme that also acts in this capacity. We named the enzyme 'adipose triglyceride lipase' in accordance with its predominant expression in adipose tissue, its high substrate specificity for triacylglycerols, and its function in the lipolytic mobilization of fatty acids. Two other research groups showed that adipose triglyceride lipase (named desnutrin and Ca-independent phospholipase A2zeta, respectively) is regulated by the nutritional status and that it might exert acyl-transacylase activity in addition to its activity as triacylglycerol hydrolase. Adipose triglyceride lipase represents a novel type of 'patatin domain-containing' triacylglycerol hydrolase that is more closely related to plant lipases than to other known mammalian metabolic triacylglycerol hydrolases. SUMMARY Although the regulation of adipose triglyceride lipase and its physiological function remain to be determined in mouse lines that lack or overexpress the enzyme, present data permit the conclusion that adipose triglyceride lipase is involved in the cellular mobilization of fatty acids, and they require a revision of the concept that hormone-sensitive lipase is the only enzyme involved in the lipolysis of adipose tissue triglycerides.
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Affiliation(s)
- Rudolf Zechner
- Institute of Molecular Biosciences, Karl-Franzens University Graz, Graz, Austria.
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42
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Abstract
PURPOSE OF REVIEW This review highlights recent advances in structural studies of exchangeable human apolipoproteins and the insights they provide into lipoprotein action in cardiovascular and amyloid diseases. RECENT FINDINGS The high-resolution X-ray crystal structure of free apoA-II reveals a parallel helical array that may represent other lipid-poor apolipoproteins, and the structure in complex with detergent substantiates the belt model for the protein arrangement on lipoproteins. Nuclear magnetic resonance structures of apolipoprotein-detergent complexes show a repertoire of curved helical conformations, suggesting multiple helical arrangements on the lipid. Low-resolution spectroscopic analyses, interface studies and molecular modeling provide new insights into the 'hinge-domain' mechanism of apolipoprotein adaptation at variable lipoprotein surfaces. A kinetic mechanism for lipoprotein stabilization is proposed. SUMMARY Cumulative evidence supports the belt model that provides a general structural basis for understanding the molecular mechanisms of functional apolipoprotein reactions, such as binding to lipoprotein receptors, lipid transporters, and the activation of lipophilic enzymes. However, the detailed protein and lipid conformations on lipoproteins and the underlying molecular interactions are unclear. New insights will hopefully emerge once the first detailed lipoprotein structure is solved.
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Affiliation(s)
- Olga Gursky
- Department of Physiology and Biophysics, Boston University School of Medicine, W329, Boston, Massachusetts 02118, USA.
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Choowongkomon K, Carlin CR, Sönnichsen FD. A structural model for the membrane-bound form of the juxtamembrane domain of the epidermal growth factor receptor. J Biol Chem 2005; 280:24043-52. [PMID: 15840573 DOI: 10.1074/jbc.m502698200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epidermal growth factor receptor (EGFR) is a member of the receptor tyrosine kinase family involved in the regulation of cellular proliferation and differentiation. Its juxtamembrane domain (JX), the region located between the transmembrane and kinase domains, plays important roles in receptor trafficking. Two sorting signals, a PXXP motif and a 658LL659 motif, are responsible for basolateral sorting in polarized epithelial cells, and a 679LL680 motif targets the ligand-activated receptor for lysosomal degradation. To understand the regulation of these signals, we characterized the structural properties of recombinant JX domain in aqueous solution and in dodecylphosphocholine (DPC) detergent. JX is inherently unstructured in aqueous solution, albeit a nascent helix encompasses the lysosomal sorting signal. In DPC micelles, structures derived from NMR data showed three amphipathic, helical segments. A large, internally inconsistent group of long range nuclear Overhauser effects suggest a close proximity of the helices, and the presence of significant conformational averaging. Models were determined for the average JX conformation using restraints representing the translational restriction due to micelle-surface adsorption, and the helix orientations were determined from residual dipolar couplings. Two equivalent average structural models were obtained that differ only in the relative orientation between first and second helices. In these models, the 658LL659 and 679LL680 motifs are located in the first and second helices and face the micelle surface, whereas the PXXP motif is located in a flexible helix-connecting region. The data suggest that the activity of these signals may be regulated by their membrane association and restricted accessibility in the intact receptor.
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Affiliation(s)
- Kiattawee Choowongkomon
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4970, USA
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Lookene A, Zhang L, Tougu V, Olivecrona G. 1,1'-bis(anilino)-4-,4'-bis(naphtalene)-8,8'-disulfonate acts as an inhibitor of lipoprotein lipase and competes for binding with apolipoprotein CII. J Biol Chem 2003; 278:37183-94. [PMID: 12855707 DOI: 10.1074/jbc.m303894200] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Lipoprotein lipase (LPL) is dependent on apolipoprotein CII (apoCII), a component of plasma lipoproteins, for function in vivo. The hydrophobic fluorescent probe 1,1'-bis(anilino)-4,4'-bis(naphthalene)-8,8'-disulfonate (bis-ANS) was found to be a potent inhibitor of LPL. ApoCII prevented the inhibition by bis-ANS, and was also able to restore the activity of inhibited LPL in a competitive manner, but only with triacylglycerols with acyl chains longer than three carbons. Studies of fluorescence and surface plasmon resonance indicated that LPL has an exposed hydrophobic site for binding of bis-ANS. The high affinity interaction was characterized by an equilibrium constant Kd of 0.10-0.26 microm and by a relatively high on rate constant kass = 2.0 x 10(4) m(-1) s(-1) and a slow off-rate with a dissociation rate constant kdiss = 1.2 x 10(-4) s(-1). The high affinity binding of bis-ANS did not influence interaction of LPL with heparin or with lipid/water interfaces and did not dissociate the active LPL dimer into monomers. Analysis of fragments of LPL after photoincorporation of bis-ANS indicated that the high affinity binding site was located in the middle part of the N-terminal folding domain. We propose that bis-ANS binds to an exposed hydrophobic area that is located close to the active site. This area may be the binding site for individual substrate molecules and also for apoCII.
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Affiliation(s)
- Aivar Lookene
- Department of Medical Biosciences, Physiological Chemistry, Umeå University, Umeå, Sweden SE-901 87
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