1
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Villa M, Wu J, Hansen S, Pahnke J. Emerging Role of ABC Transporters in Glia Cells in Health and Diseases of the Central Nervous System. Cells 2024; 13:740. [PMID: 38727275 PMCID: PMC11083179 DOI: 10.3390/cells13090740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Revised: 04/15/2024] [Accepted: 04/20/2024] [Indexed: 05/13/2024] Open
Abstract
ATP-binding cassette (ABC) transporters play a crucial role for the efflux of a wide range of substrates across different cellular membranes. In the central nervous system (CNS), ABC transporters have recently gathered significant attention due to their pivotal involvement in brain physiology and neurodegenerative disorders, such as Alzheimer's disease (AD). Glial cells are fundamental for normal CNS function and engage with several ABC transporters in different ways. Here, we specifically highlight ABC transporters involved in the maintenance of brain homeostasis and their implications in its metabolic regulation. We also show new aspects related to ABC transporter function found in less recognized diseases, such as Huntington's disease (HD) and experimental autoimmune encephalomyelitis (EAE), as a model for multiple sclerosis (MS). Understanding both their impact on the physiological regulation of the CNS and their roles in brain diseases holds promise for uncovering new therapeutic options. Further investigations and preclinical studies are warranted to elucidate the complex interplay between glial ABC transporters and physiological brain functions, potentially leading to effective therapeutic interventions also for rare CNS disorders.
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Affiliation(s)
- Maria Villa
- Translational Neurodegeneration Research and Neuropathology Lab, Department of Clinical Medicine (KlinMed), Medical Faculty, University of Oslo (UiO) and Section of Neuropathology Research, Department of Pathology (PAT), Clinics for Laboratory Medicine (KLM), Oslo University Hospital (OUS), Sognsvannsveien 20, NO-0372 Oslo, Norway
| | - Jingyun Wu
- Translational Neurodegeneration Research and Neuropathology Lab, Department of Clinical Medicine (KlinMed), Medical Faculty, University of Oslo (UiO) and Section of Neuropathology Research, Department of Pathology (PAT), Clinics for Laboratory Medicine (KLM), Oslo University Hospital (OUS), Sognsvannsveien 20, NO-0372 Oslo, Norway
| | - Stefanie Hansen
- Translational Neurodegeneration Research and Neuropathology Lab, Department of Clinical Medicine (KlinMed), Medical Faculty, University of Oslo (UiO) and Section of Neuropathology Research, Department of Pathology (PAT), Clinics for Laboratory Medicine (KLM), Oslo University Hospital (OUS), Sognsvannsveien 20, NO-0372 Oslo, Norway
| | - Jens Pahnke
- Translational Neurodegeneration Research and Neuropathology Lab, Department of Clinical Medicine (KlinMed), Medical Faculty, University of Oslo (UiO) and Section of Neuropathology Research, Department of Pathology (PAT), Clinics for Laboratory Medicine (KLM), Oslo University Hospital (OUS), Sognsvannsveien 20, NO-0372 Oslo, Norway
- Institute of Nutritional Medicine (INUM)/Lübeck Institute of Dermatology (LIED), University of Lübeck (UzL) and University Medical Center Schleswig-Holstein (UKSH), Ratzeburger Allee 160, D-23538 Lübeck, Germany
- Department of Pharmacology, Faculty of Medicine, University of Latvia (LU), Jelgavas iela 3, LV-1004 Rīga, Latvia
- School of Neurobiology, Biochemistry and Biophysics, The Georg S. Wise Faculty of Life Sciences, Tel Aviv University (TAU), Tel Aviv IL-6997801, Israel
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2
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Sacher S, Mukherjee A, Ray A. Deciphering structural aspects of reverse cholesterol transport: mapping the knowns and unknowns. Biol Rev Camb Philos Soc 2023; 98:1160-1183. [PMID: 36880422 DOI: 10.1111/brv.12948] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 02/03/2023] [Accepted: 02/24/2023] [Indexed: 03/08/2023]
Abstract
Atherosclerosis is a major contributor to the onset and progression of cardiovascular disease (CVD). Cholesterol-loaded foam cells play a pivotal role in forming atherosclerotic plaques. Induction of cholesterol efflux from these cells may be a promising approach in treating CVD. The reverse cholesterol transport (RCT) pathway delivers cholesteryl ester (CE) packaged in high-density lipoproteins (HDL) from non-hepatic cells to the liver, thereby minimising cholesterol load of peripheral cells. RCT takes place via a well-organised interplay amongst apolipoprotein A1 (ApoA1), lecithin cholesterol acyltransferase (LCAT), ATP binding cassette transporter A1 (ABCA1), scavenger receptor-B1 (SR-B1), and the amount of free cholesterol. Unfortunately, modulation of RCT for treating atherosclerosis has failed in clinical trials owing to our lack of understanding of the relationship between HDL function and RCT. The fate of non-hepatic CEs in HDL is dependent on their access to proteins involved in remodelling and can be regulated at the structural level. An inadequate understanding of this inhibits the design of rational strategies for therapeutic interventions. Herein we extensively review the structure-function relationships that are essential for RCT. We also focus on genetic mutations that disturb the structural stability of proteins involved in RCT, rendering them partially or completely non-functional. Further studies are necessary for understanding the structural aspects of RCT pathway completely, and this review highlights alternative theories and unanswered questions.
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Affiliation(s)
- Sukriti Sacher
- Department of Computational Biology, Indraprastha Institute of Information Technology, Okhla Phase III, New Delhi, 110019, India
| | - Abhishek Mukherjee
- Dhiti Life Sciences Pvt Ltd, B-107, Okhla Phase I, New Delhi, 110020, India
| | - Arjun Ray
- Department of Computational Biology, Indraprastha Institute of Information Technology, Okhla Phase III, New Delhi, 110019, India
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3
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Plummer-Medeiros AM, Culbertson AT, Morales-Perez CL, Liao M. Activity and Structural Dynamics of Human ABCA1 in a Lipid Membrane. J Mol Biol 2023; 435:168038. [PMID: 36889459 DOI: 10.1016/j.jmb.2023.168038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/08/2023]
Abstract
The human ATP-binding cassette (ABC) transporter ABCA1 plays a critical role in lipid homeostasis as it extracts sterols and phospholipids from the plasma membrane for excretion to the extracellular apolipoprotein A-I and subsequent formation of high-density lipoprotein (HDL) particles. Deleterious mutations of ABCA1 lead to sterol accumulation and are associated with atherosclerosis, poor cardiovascular outcomes, cancer, and Alzheimer's disease. The mechanism by which ABCA1 drives lipid movement is poorly understood, and a unified platform to produce active ABCA1 protein for both functional and structural studies has been missing. In this work, we established a stable expression system for both a human cell-based sterol export assay and protein purification for in vitro biochemical and structural studies. ABCA1 produced in this system was active in sterol export and displayed enhanced ATPase activity after reconstitution into a lipid bilayer. Our single-particle cryo-EM study of ABCA1 in nanodiscs showed protein induced membrane curvature, revealed multiple distinct conformations, and generated a structure of nanodisc-embedded ABCA1 at 4.0-Å resolution representing a previously unknown conformation. Comparison of different ABCA1 structures and molecular dynamics simulations demonstrates both concerted domain movements and conformational variations within each domain. Taken together, our platform for producing and characterizing ABCA1 in a lipid membrane enabled us to gain important mechanistic and structural insights and paves the way for investigating modulators that target the functions of ABCA1.
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Affiliation(s)
- Ashlee M Plummer-Medeiros
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Bryn Mawr College Chemistry Department, 101 N Merion Avenue, Bryn Mawr, PA 19010, USA
| | - Alan T Culbertson
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Roivant Sciences, Inc., 451 D Street, Boston, MA 02210, USA
| | - Claudio L Morales-Perez
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Generate Biomedicines, 4 Corporate Drive Andover, MA, 01810, USA
| | - Maofu Liao
- Department of Cell Biology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA; Department of Chemical Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen 518055, China.
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4
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Ajabnoor GMA, Bahijri SM, Alrashidi W, Enani SM, Alamoudi AA, Al Sheikh L, Eldakhakhny B. ABCA1 C69T Gene Polymorphism Association with Dysglycemia in Saudi Prediabetic Adults. Genes (Basel) 2022; 13:genes13122277. [PMID: 36553543 PMCID: PMC9777653 DOI: 10.3390/genes13122277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Revised: 11/21/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022] Open
Abstract
Studies suggest that ATP-binding cassette transporter A1 (ABCA1 C69T) polymorphism is associated with a decreased incidence of type 2 diabetes mellitus (T2DM) and that there is an association between ABCA1 C69T polymorphism and the risk of dyslipidemia in diabetic individuals. However, other studies contradict these suggestions. Therefore, we aimed to investigate the prevalence of ABCA1 C69T (rs1800977) gene polymorphism in a representative sample of the Saudi population not previously diagnosed with diabetes and its possible association with dyslipidemia and dysglycemia. A cross-sectional design was used to recruit nondiabetic adults of both genders from the Saudi population in Jeddah by employing a stratified, two-stage cluster sampling method. A total of 650 people (337 men and 313 women) were recruited. Demographic, dietary, and lifestyle variables, as well as medical history and family history of chronic diseases, were collected using a predesigned questionnaire. Fasting blood samples were taken for the determination of fasting plasma glucose (FPG), glycated hemoglobin (HbA1c), and lipids profile, which were followed by a 1-h oral glucose tolerance test (OGTT). Real-time PCR technology was used to determine the ABCA1 C69T gene SNP (rs1800977). The T allele of ABCA1 C69T (rs1800977) was very frequent (TT in 44.9% and CT in 43.7%). There was a trend toward significance for a higher dysglycemia percentage in people with CT and TT genotypes (25.7%, and 23.3%, respectively) compared with CC genotypes (16.2%). In addition, FPG and 1-h plasma glucose were significantly higher in people with both TT and CT genotypes compared to CC genotypes. However, T allele was not associated with any dysregulation of lipid parameters.
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Affiliation(s)
- Ghada M. A. Ajabnoor
- Department of Clinical Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah 21551, Saudi Arabia
- Saudi Diabetes Research Group, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah 3270, Saudi Arabia
- Food, Nutrition and Lifestyle Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 3270, Saudi Arabia
- Correspondence:
| | - Suhad M. Bahijri
- Department of Clinical Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah 21551, Saudi Arabia
- Saudi Diabetes Research Group, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah 3270, Saudi Arabia
- Food, Nutrition and Lifestyle Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 3270, Saudi Arabia
| | - Wafa Alrashidi
- Department of Clinical Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah 21551, Saudi Arabia
| | - Sumia Mohammad Enani
- Saudi Diabetes Research Group, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah 3270, Saudi Arabia
- Food, Nutrition and Lifestyle Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 3270, Saudi Arabia
- Department of Food and Nutrition, Faculty of Human Sciences and Design, King Abdulaziz University, Jeddah 3270, Saudi Arabia
| | - Aliaa A. Alamoudi
- Department of Clinical Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah 21551, Saudi Arabia
- Saudi Diabetes Research Group, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah 3270, Saudi Arabia
| | - Lubna Al Sheikh
- Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589, Saudi Arabia
| | - Basmah Eldakhakhny
- Department of Clinical Biochemistry, Faculty of Medicine, King Abdulaziz University, Jeddah 21551, Saudi Arabia
- Saudi Diabetes Research Group, King Fahd Medical Research Centre, King Abdulaziz University, Jeddah 3270, Saudi Arabia
- Food, Nutrition and Lifestyle Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah 3270, Saudi Arabia
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5
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Chen L, Zhao ZW, Zeng PH, Zhou YJ, Yin WJ. Molecular mechanisms for ABCA1-mediated cholesterol efflux. Cell Cycle 2022; 21:1121-1139. [PMID: 35192423 PMCID: PMC9103275 DOI: 10.1080/15384101.2022.2042777] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
The maintenance of cellular cholesterol homeostasis is essential for normal cell function and viability. Excessive cholesterol accumulation is detrimental to cells and serves as the molecular basis of many diseases, such as atherosclerosis, Alzheimer's disease, and diabetes mellitus. The peripheral cells do not have the ability to degrade cholesterol. Cholesterol efflux is therefore the only pathway to eliminate excessive cholesterol from these cells. This process is predominantly mediated by ATP-binding cassette transporter A1 (ABCA1), an integral membrane protein. ABCA1 is known to transfer intracellular free cholesterol and phospholipids to apolipoprotein A-I (apoA-I) for generating nascent high-density lipoprotein (nHDL) particles. nHDL can accept more free cholesterol from peripheral cells. Free cholesterol is then converted to cholesteryl ester by lecithin:cholesterol acyltransferase to form mature HDL. HDL-bound cholesterol enters the liver for biliary secretion and fecal excretion. Although how cholesterol is transported by ABCA1 to apoA-I remains incompletely understood, nine models have been proposed to explain this effect. In this review, we focus on the current view of the mechanisms underlying ABCA1-mediated cholesterol efflux to provide an important framework for future investigation and lipid-lowering therapy.
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Affiliation(s)
- Lei Chen
- Department of Cardiology, The Second Affiliated Hospital of Hainan Medical University, Haikou, Hainan, China
| | - Zhen-Wang Zhao
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Peng-Hui Zeng
- Department of Clinical Laboratory, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Ying-Jie Zhou
- Department of Clinical Laboratory, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan, China
| | - Wen-Jun Yin
- Department of Clinical Laboratory, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan, China,CONTACT Wen-Jun Yin Department of Clinical Laboratory, The First Affiliated Hospital, Hengyang Medical School, University of South China, Hengyang, Hunan421001, China
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6
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Juhl AD, Wüstner D. Pathways and Mechanisms of Cellular Cholesterol Efflux-Insight From Imaging. Front Cell Dev Biol 2022; 10:834408. [PMID: 35300409 PMCID: PMC8920967 DOI: 10.3389/fcell.2022.834408] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Accepted: 02/04/2022] [Indexed: 12/24/2022] Open
Abstract
Cholesterol is an essential molecule in cellular membranes, but too much cholesterol can be toxic. Therefore, mammalian cells have developed complex mechanisms to remove excess cholesterol. In this review article, we discuss what is known about such efflux pathways including a discussion of reverse cholesterol transport and formation of high-density lipoprotein, the function of ABC transporters and other sterol efflux proteins, and we highlight their role in human diseases. Attention is paid to the biophysical principles governing efflux of sterols from cells. We also discuss recent evidence for cholesterol efflux by the release of exosomes, microvesicles, and migrasomes. The role of the endo-lysosomal network, lipophagy, and selected lysosomal transporters, such as Niemann Pick type C proteins in cholesterol export from cells is elucidated. Since oxysterols are important regulators of cellular cholesterol efflux, their formation, trafficking, and secretion are described briefly. In addition to discussing results obtained with traditional biochemical methods, focus is on studies that use established and novel bioimaging approaches to obtain insight into cholesterol efflux pathways, including fluorescence and electron microscopy, atomic force microscopy, X-ray tomography as well as mass spectrometry imaging.
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Affiliation(s)
- Alice Dupont Juhl
- Department of Biochemistry and Molecular Biology, PhyLife, Physical Life Sciences, University of Southern Denmark, Odense, Denmark
| | - Daniel Wüstner
- Department of Biochemistry and Molecular Biology, PhyLife, Physical Life Sciences, University of Southern Denmark, Odense, Denmark
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7
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Molday RS, Garces FA, Scortecci JF, Molday LL. Structure and function of ABCA4 and its role in the visual cycle and Stargardt macular degeneration. Prog Retin Eye Res 2021; 89:101036. [PMID: 34954332 DOI: 10.1016/j.preteyeres.2021.101036] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 12/07/2021] [Accepted: 12/13/2021] [Indexed: 12/17/2022]
Abstract
ABCA4 is a member of the superfamily of ATP-binding cassette (ABC) transporters that is preferentially localized along the rim region of rod and cone photoreceptor outer segment disc membranes. It uses the energy from ATP binding and hydrolysis to transport N-retinylidene-phosphatidylethanolamine (N-Ret-PE), the Schiff base adduct of retinal and phosphatidylethanolamine, from the lumen to the cytoplasmic leaflet of disc membranes. This ensures that all-trans-retinal and excess 11-cis-retinal are efficiently cleared from photoreceptor cells thereby preventing the accumulation of toxic retinoid compounds. Loss-of-function mutations in the gene encoding ABCA4 cause autosomal recessive Stargardt macular degeneration, also known as Stargardt disease (STGD1), and related autosomal recessive retinopathies characterized by impaired central vision and an accumulation of lipofuscin and bis-retinoid compounds. High resolution structures of ABCA4 in its substrate and nucleotide free state and containing bound N-Ret-PE or ATP have been determined by cryo-electron microscopy providing insight into the molecular architecture of ABCA4 and mechanisms underlying substrate recognition and conformational changes induced by ATP binding. The expression and functional characterization of a large number of disease-causing missense ABCA4 variants have been determined. These studies have shed light into the molecular mechanisms underlying Stargardt disease and a classification that reliably predicts the effect of a specific missense mutation on the severity of the disease. They also provide a framework for developing rational therapeutic treatments for ABCA4-associated diseases.
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Affiliation(s)
- Robert S Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada; Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, B.C., Canada.
| | - Fabian A Garces
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
| | | | - Laurie L Molday
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
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8
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Scortecci JF, Molday LL, Curtis SB, Garces FA, Panwar P, Van Petegem F, Molday RS. Cryo-EM structures of the ABCA4 importer reveal mechanisms underlying substrate binding and Stargardt disease. Nat Commun 2021; 12:5902. [PMID: 34625547 PMCID: PMC8501128 DOI: 10.1038/s41467-021-26161-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Accepted: 09/20/2021] [Indexed: 12/04/2022] Open
Abstract
ABCA4 is an ATP-binding cassette (ABC) transporter that flips N-retinylidene-phosphatidylethanolamine (N-Ret-PE) from the lumen to the cytoplasmic leaflet of photoreceptor membranes. Loss-of-function mutations cause Stargardt disease (STGD1), a macular dystrophy associated with severe vision loss. To define the mechanisms underlying substrate binding and STGD1, we determine the cryo-EM structure of ABCA4 in its substrate-free and bound states. The two structures are similar and delineate an elongated protein with the two transmembrane domains (TMD) forming an outward facing conformation, extended and twisted exocytoplasmic domains (ECD), and closely opposed nucleotide binding domains. N-Ret-PE is wedged between the two TMDs and a loop from ECD1 within the lumen leaflet consistent with a lateral access mechanism and is stabilized through hydrophobic and ionic interactions with residues from the TMDs and ECDs. Our studies provide a framework for further elucidating the molecular mechanism associated with lipid transport and disease and developing promising disease interventions.
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Affiliation(s)
| | - Laurie L Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Susan B Curtis
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Fabian A Garces
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Pankaj Panwar
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada
| | - Robert S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, BC, Canada.
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9
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Li H, Yu XH, Ou X, Ouyang XP, Tang CK. Hepatic cholesterol transport and its role in non-alcoholic fatty liver disease and atherosclerosis. Prog Lipid Res 2021; 83:101109. [PMID: 34097928 DOI: 10.1016/j.plipres.2021.101109] [Citation(s) in RCA: 74] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 12/12/2022]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a quickly emerging global health problem representing the most common chronic liver disease in the world. Atherosclerotic cardiovascular disease represents the leading cause of mortality in NAFLD patients. Cholesterol metabolism has a crucial role in the pathogenesis of both NAFLD and atherosclerosis. The liver is the major organ for cholesterol metabolism. Abnormal hepatic cholesterol metabolism not only leads to NAFLD but also drives the development of atherosclerotic dyslipidemia. The cholesterol level in hepatocytes reflects the dynamic balance between endogenous synthesis, uptake, esterification, and export, a process in which cholesterol is converted to neutral cholesteryl esters either for storage in cytosolic lipid droplets or for secretion as a major constituent of plasma lipoproteins, including very-low-density lipoproteins, chylomicrons, high-density lipoproteins, and low-density lipoproteins. In this review, we describe decades of research aimed at identifying key molecules and cellular players involved in each main aspect of hepatic cholesterol metabolism. Furthermore, we summarize the recent advances regarding the biological processes of hepatic cholesterol transport and its role in NAFLD and atherosclerosis.
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Affiliation(s)
- Heng Li
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China
| | - Xiao-Hua Yu
- Institute of Clinical Medicine, The Second Affiliated Hospital of Hainan Medical University, Haikou, Hainan 460106, China
| | - Xiang Ou
- Department of Endocrinology, the First Hospital of Changsha, Changsha, Hunan 410005, China
| | - Xin-Ping Ouyang
- Department of Physiology, Institute of Neuroscience Research, Hengyang Key Laboratory of Neurodegeneration and Cognitive Impairment, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China.
| | - Chao-Ke Tang
- Institute of Cardiovascular Disease, Key Laboratory for Arteriosclerology of Hunan Province, Hunan International Scientific and Technological Cooperation Base of Arteriosclerotic Disease, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, University of South China, Hengyang, Hunan 421001, China.
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10
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Abstract
Cholesterol homeostasis and trafficking are critical to the maintenance of the asymmetric plasma membrane of eukaryotic cells. Disruption or dysfunction of cholesterol trafficking leads to numerous human diseases. ATP-binding cassette (ABC) transporters play several critical roles in this process, and mutations in these sterol transporters lead to disorders such as Tangier disease and sitosterolemia. Biochemical and structural information on ABC sterol transporters is beginning to emerge, with published structures of ABCA1 and ABCG5/G8; these two proteins function in the reverse cholesterol transport pathway and mediate the efflux of cholesterol and xenosterols to high-density lipoprotein and bile salt micelles, respectively. Although both of these transporters belong to the ABC family and mediate the efflux of a sterol substrate, they have many distinct differences. Here, we summarize the current understanding of sterol transport driven by ABC transporters, with an emphasis on these two extensively characterized transporters.
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Affiliation(s)
- Ashlee M Plummer
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Alan T Culbertson
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Maofu Liao
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA;
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11
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Frambach SJCM, de Haas R, Smeitink JAM, Rongen GA, Russel FGM, Schirris TJJ. Brothers in Arms: ABCA1- and ABCG1-Mediated Cholesterol Efflux as Promising Targets in Cardiovascular Disease Treatment. Pharmacol Rev 2020; 72:152-190. [PMID: 31831519 DOI: 10.1124/pr.119.017897] [Citation(s) in RCA: 81] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Atherosclerosis is a leading cause of cardiovascular disease worldwide, and hypercholesterolemia is a major risk factor. Preventive treatments mainly focus on the effective reduction of low-density lipoprotein cholesterol, but their therapeutic value is limited by the inability to completely normalize atherosclerotic risk, probably due to the disease complexity and multifactorial pathogenesis. Consequently, high-density lipoprotein cholesterol gained much interest, as it appeared to be cardioprotective due to its major role in reverse cholesterol transport (RCT). RCT facilitates removal of cholesterol from peripheral tissues, including atherosclerotic plaques, and its subsequent hepatic clearance into bile. Therefore, RCT is expected to limit plaque formation and progression. Cellular cholesterol efflux is initiated and propagated by the ATP-binding cassette (ABC) transporters ABCA1 and ABCG1. Their expression and function are expected to be rate-limiting for cholesterol efflux, which makes them interesting targets to stimulate RCT and lower atherosclerotic risk. This systematic review discusses the molecular mechanisms relevant for RCT and ABCA1 and ABCG1 function, followed by a critical overview of potential pharmacological strategies with small molecules to enhance cellular cholesterol efflux and RCT. These strategies include regulation of ABCA1 and ABCG1 expression, degradation, and mRNA stability. Various small molecules have been demonstrated to increase RCT, but the underlying mechanisms are often not completely understood and are rather unspecific, potentially causing adverse effects. Better understanding of these mechanisms could enable the development of safer drugs to increase RCT and provide more insight into its relation with atherosclerotic risk. SIGNIFICANCE STATEMENT: Hypercholesterolemia is an important risk factor of atherosclerosis, which is a leading pathological mechanism underlying cardiovascular disease. Cholesterol is removed from atherosclerotic plaques and subsequently cleared by the liver into bile. This transport is mediated by high-density lipoprotein particles, to which cholesterol is transferred via ATP-binding cassette transporters ABCA1 and ABCG1. Small-molecule pharmacological strategies stimulating these transporters may provide promising options for cardiovascular disease treatment.
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Affiliation(s)
- Sanne J C M Frambach
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences (S.J.C.M.F., G.A.R., F.G.M.R., T.J.J.S.), Radboud Center for Mitochondrial Medicine (S.J.C.M.F., R.d.H., J.A.M.S., F.G.M.R., T.J.J.S.), Department of Pediatrics (R.d.H., J.A.M.S.), and Department of Internal Medicine, Radboud Institute for Health Sciences (G.A.R.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Ria de Haas
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences (S.J.C.M.F., G.A.R., F.G.M.R., T.J.J.S.), Radboud Center for Mitochondrial Medicine (S.J.C.M.F., R.d.H., J.A.M.S., F.G.M.R., T.J.J.S.), Department of Pediatrics (R.d.H., J.A.M.S.), and Department of Internal Medicine, Radboud Institute for Health Sciences (G.A.R.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Jan A M Smeitink
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences (S.J.C.M.F., G.A.R., F.G.M.R., T.J.J.S.), Radboud Center for Mitochondrial Medicine (S.J.C.M.F., R.d.H., J.A.M.S., F.G.M.R., T.J.J.S.), Department of Pediatrics (R.d.H., J.A.M.S.), and Department of Internal Medicine, Radboud Institute for Health Sciences (G.A.R.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Gerard A Rongen
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences (S.J.C.M.F., G.A.R., F.G.M.R., T.J.J.S.), Radboud Center for Mitochondrial Medicine (S.J.C.M.F., R.d.H., J.A.M.S., F.G.M.R., T.J.J.S.), Department of Pediatrics (R.d.H., J.A.M.S.), and Department of Internal Medicine, Radboud Institute for Health Sciences (G.A.R.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Frans G M Russel
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences (S.J.C.M.F., G.A.R., F.G.M.R., T.J.J.S.), Radboud Center for Mitochondrial Medicine (S.J.C.M.F., R.d.H., J.A.M.S., F.G.M.R., T.J.J.S.), Department of Pediatrics (R.d.H., J.A.M.S.), and Department of Internal Medicine, Radboud Institute for Health Sciences (G.A.R.), Radboud University Medical Center, Nijmegen, The Netherlands
| | - Tom J J Schirris
- Department of Pharmacology and Toxicology, Radboud Institute for Molecular Life Sciences (S.J.C.M.F., G.A.R., F.G.M.R., T.J.J.S.), Radboud Center for Mitochondrial Medicine (S.J.C.M.F., R.d.H., J.A.M.S., F.G.M.R., T.J.J.S.), Department of Pediatrics (R.d.H., J.A.M.S.), and Department of Internal Medicine, Radboud Institute for Health Sciences (G.A.R.), Radboud University Medical Center, Nijmegen, The Netherlands
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12
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Yelamanchili D, Liu J, Gotto AM, Hurley AE, Lagor WR, Gillard BK, Davidson WS, Pownall HJ, Rosales C. Highly conserved amino acid residues in apolipoprotein A1 discordantly induce high density lipoprotein assembly in vitro and in vivo. Biochim Biophys Acta Mol Cell Biol Lipids 2020; 1865:158794. [PMID: 32810603 DOI: 10.1016/j.bbalip.2020.158794] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Revised: 08/10/2020] [Accepted: 08/13/2020] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Apolipoprotein A1 (APOA1) is essential to reverse cholesterol transport, a physiologically important process that protects against atherosclerotic cardiovascular disease. APOA1 is a 28 kDa protein comprising multiple lipid-binding amphiphatic helices initialized by proline residues, which are conserved across multiple species. We tested the hypothesis that the evolutionarily conserved residues are essential to high density lipoprotein (HDL) function. APPROACH We used biophysical and physiological assays of the function of APOA1P➔A variants, i.e., rHDL formation via dimyristoylphosphatidylcholine (DMPC) microsolubilization, activation of lecithin: cholesterol acyltransferase, cholesterol efflux from human monocyte-derived macrophages (THP-1) to each variant, and comparison of the size and composition of HDL from APOA1-/- mice receiving adeno-associated virus delivery of each human variant. RESULTS Differences in microsolubilization were profound and showed that conserved prolines, especially those in the C-terminus of APOA1, are essential to efficient rHDL formation. In contrast, P➔A substitutions produced small changes (-25 to +25%) in rates of cholesterol efflux and no differences in the rates of LCAT activation. The HDL particles formed following ectopic expression of each variant in APOA1-/- mice were smaller and more heterogeneous than those from control animals. CONCLUSION Studies of DMPC microsolubilization show that proline residues are essential to the optimal interaction of APOA1 with membranes, the initial step in cholesterol efflux and HDL production. In contrast, P➔A substitutions modestly reduce the cholesterol efflux capacity of APOA1, have no effect on LCAT activation, but according to the profound reduction in the size of HDL formed in vivo, P➔A substitutions alter HDL biogenesis, thereby implicating other cellular and in vivo processes as determinants of HDL metabolism and function.
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Affiliation(s)
- Dedipya Yelamanchili
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA.
| | - Jing Liu
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Department of Cardiovascular Surgery, Xiangya Hospital, Central South University, Changsha 410008, China.
| | - Antonio M Gotto
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Weill Cornell Medicine, 1305 York Avenue, New York, NY 10065, USA.
| | - Ayrea E Hurley
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
| | - Willam R Lagor
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
| | - Baiba K Gillard
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Weill Cornell Medicine, 1305 York Avenue, New York, NY 10065, USA.
| | - W Sean Davidson
- Department of Pathology and Laboratory Medicine, University of Cincinnati, Cincinnati, OH 45237, USA.
| | - Henry J Pownall
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Weill Cornell Medicine, 1305 York Avenue, New York, NY 10065, USA.
| | - Corina Rosales
- Center for Bioenergetics, Houston Methodist Research Institute, 6670 Bertner Avenue, Houston, TX 77030, USA; Weill Cornell Medicine, 1305 York Avenue, New York, NY 10065, USA.
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13
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ABC Transporters, Cholesterol Efflux, and Implications for Cardiovascular Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1276:67-83. [DOI: 10.1007/978-981-15-6082-8_6] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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14
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Xepapadaki E, Maulucci G, Constantinou C, Karavia EA, Zvintzou E, Daniel B, Sasson S, Kypreos KE. Impact of apolipoprotein A1- or lecithin:cholesterol acyltransferase-deficiency on white adipose tissue metabolic activity and glucose homeostasis in mice. Biochim Biophys Acta Mol Basis Dis 2019; 1865:1351-1360. [DOI: 10.1016/j.bbadis.2019.02.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Revised: 02/04/2019] [Accepted: 02/06/2019] [Indexed: 12/15/2022]
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15
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Kawanobe T, Shiranaga N, Kioka N, Kimura Y, Ueda K. Apolipoprotein A-I directly interacts with extracellular domain 1 of human ABCA1. Biosci Biotechnol Biochem 2019; 83:490-497. [DOI: 10.1080/09168451.2018.1547106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
ABSTRACT
ATP-binding cassette transporter A1 (ABCA1) is critical for the generation of nascent high-density lipoprotein (HDL) and plays important roles in cholesterol homeostasis. ABCA1 has two large extracellular domains (ECDs), which may interact directly with apolipoprotein A-I (apoA-I). However, the molecular mechanisms underlying HDL formation and the importance of ABCA1–apoA-I interactions in HDL formation remain unclear. We investigated the ABCA1–apoA-I interaction in photo-activated crosslinking experiments using sulfo-SBED–labeled apoA-I. ApoA-I bound to cells expressing ABCA1, but not to untransfected cells or cells expressing non-functional ABCA1. Binding was inhibited by sulfo-SBED–labeled apoA-I, and crosslinking of sulfo-SBED–labeled apoA-I with ABCA1 was inhibited by non-labeled apoA-I, suggesting that sulfo-SBED–labeled apoA-I specifically binds and crosslinks with functional ABCA1. Proteolytic digestion of crosslinked ABCA1 revealed that apoA-I bound the N-terminal half of ABCA1, and that the first ECD of ABCA1 is an apoA-I binding site.
Abbreviations: ABC: ATP-binding cassette; apoA-I: apolipoprotein A-I; ATP: adenosine triphosphate; CHAPS: 3-(3-cholamidepropyl)dimethylammonio-1- propanesulphonate; DTT: dithiothreitol; ECD: extra cellular domain; EDTA: ethylenediaminetetraacetic acid; GFP: green fluorescent protein; HA: hemagglutinin; HDL: high density lipoprotein; HEK: human embryonic kidney; HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid; sulfo-SBED: (sulfosuccinimidyl-2-[6-(biotinamido)-2-(p-azidobenzamido)hexanoamido] ethyl-1,3ʹ-dithiopropionate; NHS-ester, N-hydroxysuccinimide-ester
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Affiliation(s)
- Takaaki Kawanobe
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Naoko Shiranaga
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Noriyuki Kioka
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto, Japan
| | - Yasuhisa Kimura
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
| | - Kazumitsu Ueda
- Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University, Kyoto, Japan
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto, Japan
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16
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Liu M, Mei X, Herscovitz H, Atkinson D. N-terminal mutation of apoA-I and interaction with ABCA1 reveal mechanisms of nascent HDL biogenesis. J Lipid Res 2018; 60:44-57. [PMID: 30249788 DOI: 10.1194/jlr.m084376] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 09/21/2018] [Indexed: 12/25/2022] Open
Abstract
ApoA-I and ABCA1 play important roles in nascent HDL (nHDL) biogenesis, the first step in the pathway of reverse cholesterol transport that protects against cardiovascular disease. On the basis of the crystal structure of a C-terminally truncated form of apoA-I[Δ(185-243)] determined in our laboratory, we hypothesized that opening the N-terminal helix bundle would facilitate lipid binding. To that end, we structurally designed a mutant (L38G/K40G) to destabilize the N-terminal helical bundle at the first hinge region. Conformational characterization of this mutant in solution revealed minimally reduced α-helical content, a less-compact overall structure, and increased lipid-binding ability. In solution-binding studies, apoA-I and purified ABCA1 also showed direct binding between them. In ABCA1-transfected HEK293 cells, L38G/K40G had a significantly enhanced ability to form nHDL, which suggests that a destabilized N-terminal bundle facilitates nHDL formation. The total cholesterol efflux from ABCA1-transfected HEK293 cells was unchanged in mutant versus WT apoA-I, though, which suggests that cholesterol efflux and nHDL particle formation might be uncoupled events. Analysis of the particles in the efflux media revealed a population of apoA-I-free lipid particles along with nHDL. This model improves knowledge of nHDL formation for future research.
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Affiliation(s)
- Minjing Liu
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
| | - Xiaohu Mei
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
| | | | - David Atkinson
- Department of Physiology and Biophysics, Boston University School of Medicine, Boston, MA 02118
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17
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Orekhov AN, Pushkarsky T, Oishi Y, Nikiforov NG, Zhelankin AV, Dubrovsky L, Makeev VJ, Foxx K, Jin X, Kruth HS, Sobenin IA, Sukhorukov VN, Zakiev ER, Kontush A, Le Goff W, Bukrinsky M. HDL activates expression of genes stimulating cholesterol efflux in human monocyte-derived macrophages. Exp Mol Pathol 2018; 105:202-207. [PMID: 30118702 DOI: 10.1016/j.yexmp.2018.08.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 08/09/2018] [Accepted: 08/13/2018] [Indexed: 12/24/2022]
Abstract
High density lipoproteins (HDL) are key components of reverse cholesterol transport pathway. HDL removes excessive cholesterol from peripheral cells, including macrophages, providing protection from cholesterol accumulation and conversion into foam cells, which is a key event in pathogenesis of atherosclerosis. The mechanism of cellular cholesterol efflux stimulation by HDL involves interaction with the ABCA1 lipid transporter and ensuing transfer of cholesterol to HDL particles. In this study, we looked for additional proteins contributing to HDL-dependent cholesterol efflux. Using RNAseq, we analyzed mRNAs induced by HDL in human monocyte-derived macrophages and identified three genes, fatty acid desaturase 1 (FADS1), insulin induced gene 1 (INSIG1), and the low-density lipoprotein receptor (LDLR), expression of which was significantly upregulated by HDL. We individually knocked down these genes in THP-1 cells using gene silencing by siRNA, and measured cellular cholesterol efflux to HDL. Knock down of FADS1 did not significantly change cholesterol efflux (p = 0.70), but knockdown of INSIG1 and LDLR resulted in highly significant reduction of the efflux to HDL (67% and 75% of control, respectively, p < 0.001). Importantly, the suppression of cholesterol efflux was independent of known effects of these genes on cellular cholesterol content, as cells were loaded with cholesterol using acetylated LDL. These results indicate that HDL particles stimulate expression of genes that enhance cellular cholesterol transfer to HDL.
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Affiliation(s)
- Alexander N Orekhov
- Institute of General Pathology and Pathophysiology, Moscow, Russia; Institute for Atherosclerosis Research, Skolkovo Innovative Center, Moscow, Russia
| | - Tatiana Pushkarsky
- The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Yumiko Oishi
- Department of Cellular and Molecular Medicine, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
| | - Nikita G Nikiforov
- Institute of General Pathology and Pathophysiology, Moscow, Russia; Laboratory of Medical Genetics, Institute of Experimental Cardiology, National Medical Research Center of Cardiology, Moscow, Russia; Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Andrey V Zhelankin
- Laboratory of postgenomic research, Federal Research and Clinical Center of Physical-Chemical Medicine, Moscow, Russia
| | - Larisa Dubrovsky
- The George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Vsevolod J Makeev
- Vavilov Institute of General Genetics, Russian Academy of Sciences, Moscow, Russia; Scientific Center "Kurchatov Institute", Research Institute for Genetics and Selection of Industrial Microorganisms, Moscow, Russia; Moscow Institute of Physics and Technology (State University), Dolgoprudny, Moscow, Region, Russia; Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, Russia
| | - Kathy Foxx
- Kalen Biomedical LLC, Montgomery Village, MD, USA
| | - Xueting Jin
- Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Howard S Kruth
- Experimental Atherosclerosis Section, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Igor A Sobenin
- Institute of General Pathology and Pathophysiology, Moscow, Russia; Laboratory of Medical Genetics, Institute of Experimental Cardiology, National Medical Research Center of Cardiology, Moscow, Russia
| | - Vasily N Sukhorukov
- Institute of General Pathology and Pathophysiology, Moscow, Russia; Sorbonne Université, Inserm, Institute of Cardiometabolism and Nutrition (ICAN), UMR_S1166, Hôpital de la Pitié, Paris, France
| | - Emile R Zakiev
- Institute of General Pathology and Pathophysiology, Moscow, Russia; Sorbonne Université, Inserm, Institute of Cardiometabolism and Nutrition (ICAN), UMR_S1166, Hôpital de la Pitié, Paris, France
| | - Anatol Kontush
- Sorbonne Université, Inserm, Institute of Cardiometabolism and Nutrition (ICAN), UMR_S1166, Hôpital de la Pitié, Paris, France
| | - Wilfried Le Goff
- Sorbonne Université, Inserm, Institute of Cardiometabolism and Nutrition (ICAN), UMR_S1166, Hôpital de la Pitié, Paris, France
| | - Michael Bukrinsky
- The George Washington University School of Medicine and Health Sciences, Washington, DC, USA.
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18
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Intracellular and Plasma Membrane Events in Cholesterol Transport and Homeostasis. J Lipids 2018; 2018:3965054. [PMID: 30174957 PMCID: PMC6106919 DOI: 10.1155/2018/3965054] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 07/26/2018] [Indexed: 12/13/2022] Open
Abstract
Cholesterol transport between intracellular compartments proceeds by both energy- and non-energy-dependent processes. Energy-dependent vesicular traffic partly contributes to cholesterol flux between endoplasmic reticulum, plasma membrane, and endocytic vesicles. Membrane contact sites and lipid transfer proteins are involved in nonvesicular lipid traffic. Only “active" cholesterol molecules outside of cholesterol-rich regions and partially exposed in water phase are able to fast transfer. The dissociation of partially exposed cholesterol molecules in water determines the rate of passive aqueous diffusion of cholesterol out of plasma membrane. ATP hydrolysis with concomitant conformational transition is required to cholesterol efflux by ABCA1 and ABCG1 transporters. Besides, scavenger receptor SR-B1 is involved also in cholesterol efflux by facilitated diffusion via hydrophobic tunnel within the molecule. Direct interaction of ABCA1 with apolipoprotein A-I (apoA-I) or apoA-I binding to high capacity binding sites in plasma membrane is important in cholesterol escape to free apoA-I. ABCG1-mediated efflux to fully lipidated apoA-I within high density lipoprotein particle proceeds more likely through the increase of “active” cholesterol level. Putative cholesterol-binding linear motifs within the structure of all three proteins ABCA1, ABCG1, and SR-B1 are suggested to contribute to the binding and transfer of cholesterol molecules from cytoplasmic to outer leaflets of lipid bilayer. Together, plasma membrane events and intracellular cholesterol metabolism and traffic determine the capacity of the cell for cholesterol efflux.
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19
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Afonso MS, Machado RM, Lavrador MS, Quintao ECR, Moore KJ, Lottenberg AM. Molecular Pathways Underlying Cholesterol Homeostasis. Nutrients 2018; 10:E760. [PMID: 29899250 PMCID: PMC6024674 DOI: 10.3390/nu10060760] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2018] [Revised: 06/10/2018] [Accepted: 06/11/2018] [Indexed: 01/14/2023] Open
Abstract
Cholesterol is an essential molecule that exerts pleiotropic actions. Although its presence is vital to the cell, its excess can be harmful and, therefore, sustaining cholesterol homeostasis is crucial to maintaining proper cellular functioning. It is well documented that high plasma cholesterol concentration increases the risk of atherosclerotic heart disease. In the last decades, several studies have investigated the association of plasma cholesterol concentrations and the risk of cardiovascular diseases as well as the signaling pathways involved in cholesterol homeostasis. Here, we present an overview of several mechanisms involved in intestinal cholesterol absorption, the regulation of cholesterol synthesis and uptake. We also discuss the importance of reverse cholesterol transport and transintestinal cholesterol transport to maintain cholesterol homeostasis and prevent atherosclerosis development. Additionally, we discuss the influence of dietary cholesterol on plasma cholesterol concentration and the new recommendations for cholesterol intake in a context of a healthy dietary pattern.
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Affiliation(s)
- Milessa Silva Afonso
- Marc and Ruti Bell Vascular Biology and Disease Program, Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA.
| | - Roberta Marcondes Machado
- Laboratorio de Lipides (LIM 10), Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP 05403-000, Brazil.
| | - Maria Silvia Lavrador
- Laboratorio de Lipides (LIM 10), Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP 05403-000, Brazil.
| | - Eder Carlos Rocha Quintao
- Laboratorio de Lipides (LIM 10), Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP 05403-000, Brazil.
| | - Kathryn J Moore
- Marc and Ruti Bell Vascular Biology and Disease Program, Leon H. Charney Division of Cardiology, Department of Medicine, New York University School of Medicine, New York, NY 10016, USA.
- Department of Cell Biology, New York University School of Medicine, New York, NY 10016, USA.
| | - Ana Maria Lottenberg
- Laboratorio de Lipides (LIM 10), Hospital das Clínicas HCFMUSP, Faculdade de Medicina, Universidade de Sao Paulo, Sao Paulo, SP 05403-000, Brazil.
- Faculdade Israelita de Ciências da Saúde, Albert Einstein, São Paulo, SP 05403-000, Brazil.
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20
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Dron JS, Wang J, Berberich AJ, Iacocca MA, Cao H, Yang P, Knoll J, Tremblay K, Brisson D, Netzer C, Gouni-Berthold I, Gaudet D, Hegele RA. Large-scale deletions of the ABCA1 gene in patients with hypoalphalipoproteinemia. J Lipid Res 2018; 59:1529-1535. [PMID: 29866657 PMCID: PMC6071767 DOI: 10.1194/jlr.p086280] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 05/21/2018] [Indexed: 01/07/2023] Open
Abstract
Copy-number variations (CNVs) have been studied in the context of familial hypercholesterolemia but have not yet been evaluated in patients with extreme levels of HDL cholesterol. We evaluated targeted, next-generation sequencing data from patients with very low levels of HDL cholesterol (i.e., hypoalphalipoproteinemia) with the VarSeq-CNV® caller algorithm to screen for CNVs that disrupted the ABCA1, LCAT, or APOA1 genes. In four individuals, we found three unique deletions in ABCA1: a heterozygous deletion of exon 4, a heterozygous deletion that spanned exons 8 to 31, and a heterozygous deletion of the entire ABCA1 gene. Breakpoints were identified with Sanger sequencing, and the full-gene deletion was confirmed by using exome sequencing and the Affymetrix CytoScan HD array. Previously, large-scale deletions in candidate HDL genes had not been associated with hypoalphalipoproteinemia; our findings indicate that CNVs in ABCA1 may be a previously unappreciated genetic determinant of low levels of HDL cholesterol. By coupling bioinformatic analyses with next-generation sequencing data, we can successfully assess the spectrum of genetic determinants of many dyslipidemias, including hypoalphalipoproteinemia.
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Affiliation(s)
- Jacqueline S Dron
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London ON, Canada.,Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London ON, Canada
| | - Jian Wang
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London ON, Canada
| | - Amanda J Berberich
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London ON, Canada.,Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London ON, Canada.,Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London ON, Canada
| | - Michael A Iacocca
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London ON, Canada.,Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London ON, Canada
| | - Henian Cao
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London ON, Canada
| | - Ping Yang
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London ON, Canada
| | - Joan Knoll
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London ON, Canada
| | - Karine Tremblay
- Lipidology Unit, Community Genomic Medicine Centre and ECOGENE-21, Department of Medicine, Université de Montréal, Saguenay QC, Canada
| | - Diane Brisson
- Lipidology Unit, Community Genomic Medicine Centre and ECOGENE-21, Department of Medicine, Université de Montréal, Saguenay QC, Canada
| | | | - Ioanna Gouni-Berthold
- Polyclinic for Endocrinology, Diabetes and Preventive Medicine, University of Cologne, Germany
| | - Daniel Gaudet
- Lipidology Unit, Community Genomic Medicine Centre and ECOGENE-21, Department of Medicine, Université de Montréal, Saguenay QC, Canada
| | - Robert A Hegele
- Robarts Research Institute, Schulich School of Medicine and Dentistry, Western University, London ON, Canada .,Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London ON, Canada.,Department of Medicine, Schulich School of Medicine and Dentistry, Western University, London ON, Canada
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21
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Abstract
PURPOSE OF REVIEW The major cardio-protective function of HDL is to remove excess cellular cholesterol in the process of HDL particle formation and maturation. The HDL biogenic procedure requiring protein-lipid interactions has been incompletely understood, and here we discuss recent progress and insights into the mechanism of HDL biogenesis. RECENT FINDINGS The initial and rate-limiting step of HDL biogenesis is the interaction between apoA-I and plasma membrane microdomains created by ATP-binding cassette transporter A1 (ABCA1) transporter. Computer simulation of molecular dynamics suggests that ABCA1 translocates phospholipids from the inner to the outer leaflet of the plasma membrane to create a transbilayer density gradient leading to the formation of an exovesiculated plasma membrane microdomain. The cryo-electron microscopy structure of ABCA1 suggests that an elongated hydrophobic tunnel formed by the extracellular domain of ABCA1 may function as a passageway to deliver lipids to apoA-I. In contrast to ABCA1-created plasma membrane microdomains, desmocollin 1 (DSC1) contained in a cholesterol-rich plasma membrane microdomain binds apoA-I to prevent HDL biogenesis. The identification of DSC1-containing plasma membrane microdomains as a negative regulator of HDL biogenesis may offer potential therapeutic avenues. SUMMARY Isolation and characterization of plasma membrane microdomains involved in HDL biogenesis may lead to a better understanding of the molecular mechanism of HDL biogenesis.
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Affiliation(s)
- Jacques Genest
- Division of Cardiology, Research Institute of the McGill University Health Center, Montréal, Québec, Canada
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22
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Phillips MC. Is ABCA1 a lipid transfer protein? J Lipid Res 2018; 59:749-763. [PMID: 29305383 DOI: 10.1194/jlr.r082313] [Citation(s) in RCA: 105] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 01/02/2018] [Indexed: 12/16/2022] Open
Abstract
ABCA1 functions as a lipid transporter because it mediates the transfer of cellular phospholipid (PL) and free (unesterified) cholesterol (FC) to apoA-I and related proteins present in the extracellular medium. ABCA1 is a membrane PL translocase and its enzymatic activity leads to transfer of PL molecules from the cytoplasmic leaflet to the exofacial leaflet of a cell plasma membrane (PM). The presence of active ABCA1 in the PM promotes binding of apoA-I to the cell surface. About 10% of this bound apoA-I interacts directly with ABCA1 and stabilizes the transporter. Most of the pool of cell surface-associated apoA-I is bound to lipid domains in the PM that are created by the activity of ABCA1. The amphipathic α-helices in apoA-I confer detergent-like properties on the protein enabling it to solubilize PL and FC in these membrane domains to create a heterogeneous population of discoidal nascent HDL particles. This review focuses on current understanding of the structure-function relationships of human ABCA1 and the molecular mechanisms underlying HDL particle production.
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Affiliation(s)
- Michael C Phillips
- Division of Translational Medicine and Human Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-5158
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23
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Qian H, Zhao X, Cao P, Lei J, Yan N, Gong X. Structure of the Human Lipid Exporter ABCA1. Cell 2017; 169:1228-1239.e10. [DOI: 10.1016/j.cell.2017.05.020] [Citation(s) in RCA: 179] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Revised: 05/01/2017] [Accepted: 05/12/2017] [Indexed: 01/10/2023]
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24
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Papachristou NI, Blair HC, Kypreos KE, Papachristou DJ. High-density lipoprotein (HDL) metabolism and bone mass. J Endocrinol 2017; 233:R95-R107. [PMID: 28314771 PMCID: PMC5598779 DOI: 10.1530/joe-16-0657] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Accepted: 03/17/2017] [Indexed: 02/06/2023]
Abstract
It is well appreciated that high-density lipoprotein (HDL) and bone physiology and pathology are tightly linked. Studies, primarily in mouse models, have shown that dysfunctional and/or disturbed HDL can affect bone mass through many different ways. Specifically, reduced HDL levels have been associated with the development of an inflammatory microenvironment that affects the differentiation and function of osteoblasts. In addition, perturbation in metabolic pathways of HDL favors adipoblastic differentiation and restrains osteoblastic differentiation through, among others, the modification of specific bone-related chemokines and signaling cascades. Increased bone marrow adiposity also deteriorates bone osteoblastic function and thus bone synthesis, leading to reduced bone mass. In this review, we present the current knowledge and the future directions with regard to the HDL-bone mass connection. Unraveling the molecular phenomena that underline this connection will promote the deeper understanding of the pathophysiology of bone-related pathologies, such as osteoporosis or bone metastasis, and pave the way toward the development of novel and more effective therapies against these conditions.
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Affiliation(s)
- Nicholaos I Papachristou
- Department of Anatomy-Histology-EmbryologyUnit of Bone and Soft Tissue Studies, University of Patras Medical School, Patras, Greece
| | - Harry C Blair
- Department of PathologyUniversity of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
- Pittsburgh VA Medical CenterPittsburgh, Pennsylvania, USA
| | - Kyriakos E Kypreos
- Department of PharmacologyUniversity of Patras Medical School, Patras, Greece
| | - Dionysios J Papachristou
- Department of Anatomy-Histology-EmbryologyUnit of Bone and Soft Tissue Studies, University of Patras Medical School, Patras, Greece
- Department of PathologyUniversity of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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El-Awady R, Saleh E, Hashim A, Soliman N, Dallah A, Elrasheed A, Elakraa G. The Role of Eukaryotic and Prokaryotic ABC Transporter Family in Failure of Chemotherapy. Front Pharmacol 2017; 7:535. [PMID: 28119610 PMCID: PMC5223437 DOI: 10.3389/fphar.2016.00535] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 12/23/2016] [Indexed: 12/13/2022] Open
Abstract
Over the years chemotherapy failure has been a vital research topic as researchers have been striving to discover reasons behind it. The extensive studies carried out on chemotherapeutic agents confirm that resistance to chemotherapy is a major reason for treatment failure. “Resistance to chemotherapy,” however, is a comprehensive phrase that refers to a variety of different mechanisms in which ATP-binding cassette (ABC) mediated efflux dominates. The ABC is one of the largest gene superfamily of transporters among both eukaryotes and prokaryotes; it represents a variety of genes that code for proteins, which perform countless functions, including drug efflux – a natural process that protects cells from foreign chemicals. Up to date, chemotherapy failure due to ABC drug efflux is an active research topic that continuously provides further evidence on multiple drug resistance (MDR), aiding scientists in tackling and overcoming this issue. This review focuses on drug resistance by ABC efflux transporters in human, viral, parasitic, fungal and bacterial cells and highlights the importance of the MDR permeability glycoprotein being the mutual ABC transporter among all studied organisms. Current developments and future directions to overcome this problem are also discussed.
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Affiliation(s)
- Raafat El-Awady
- Department of Pharmacy Practice and Pharmacotherapeutics, Sharjah Institute for Medical Research and College of Pharmacy, University of Sharjah Sharjah, United Arab Emirates
| | - Ekram Saleh
- Department of Pharmacy Practice and Pharmacotherapeutics, Sharjah Institute for Medical Research and College of Pharmacy, University of SharjahSharjah, United Arab Emirates; National Cancer Institute - Cancer Biology Department, Cairo UniversityCairo, Egypt
| | - Amna Hashim
- Department of Pharmacy Practice and Pharmacotherapeutics, Sharjah Institute for Medical Research and College of Pharmacy, University of Sharjah Sharjah, United Arab Emirates
| | - Nehal Soliman
- Department of Pharmacy Practice and Pharmacotherapeutics, Sharjah Institute for Medical Research and College of Pharmacy, University of Sharjah Sharjah, United Arab Emirates
| | - Alaa Dallah
- Department of Pharmacy Practice and Pharmacotherapeutics, Sharjah Institute for Medical Research and College of Pharmacy, University of Sharjah Sharjah, United Arab Emirates
| | - Azza Elrasheed
- Department of Pharmacy Practice and Pharmacotherapeutics, Sharjah Institute for Medical Research and College of Pharmacy, University of Sharjah Sharjah, United Arab Emirates
| | - Ghada Elakraa
- Department of Pharmacy Practice and Pharmacotherapeutics, Sharjah Institute for Medical Research and College of Pharmacy, University of Sharjah Sharjah, United Arab Emirates
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Gulshan K, Brubaker G, Conger H, Wang S, Zhang R, Hazen SL, Smith JD. PI(4,5)P2 Is Translocated by ABCA1 to the Cell Surface Where It Mediates Apolipoprotein A1 Binding and Nascent HDL Assembly. Circ Res 2016; 119:827-38. [PMID: 27514935 DOI: 10.1161/circresaha.116.308856] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2016] [Accepted: 08/11/2016] [Indexed: 12/23/2022]
Abstract
RATIONALE The molecular mechanism by which ATP-binding cassette transporter A1 (ABCA1) mediates cellular binding of apolipoprotein A-I (apoA1) and nascent high-density lipoprotein (HDL) assembly is not well understood. OBJECTIVE To determine the cell surface lipid that mediates apoA1 binding to ABCA1-expressing cells and the role it plays in nascent HDL assembly. METHODS AND RESULTS Using multiple biochemical and biophysical methods, we found that apoA1 binds specifically to phosphatidylinositol (4,5) bis-phosphate (PIP2). Flow cytometry and PIP2 reporter-binding assays demonstrated that ABCA1 led to PIP2 redistribution from the inner to the outer leaflet of the plasma membrane. Enzymatic cleavage of cell surface PIP2 or decreased cellular PIP2 by knockdown of phosphatidylinositol-5-phosphate 4-kinase impaired apoA1 binding and cholesterol efflux to apoA1. PIP2 also increased the spontaneous solubilization of phospholipid liposomes by apoA1. Using site-directed mutagenesis, we found that ABCA1's PIP2 and phosphatidylserine translocase activities are independent from each other. Furthermore, we discovered that PIP2 is effluxed from cells to apoA1, where it is associated with HDL in plasma, and that PIP2 on HDL is taken up by target cells in a scavenger receptor-BI-dependent manner. Mouse plasma PIP2 levels are apoA1 gene dosage-dependent and are >1 μM in apoA1 transgenic mice. CONCLUSIONS ABCA1 has PIP2 floppase activity, which increases cell surface PIP2 levels that mediate apoA1 binding and lipid efflux during nascent HDL assembly. We found that PIP2 itself is effluxed to apoA1 and it circulates on plasma HDL, where it can be taken up via the HDL receptor scavenger receptor-BI.
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Affiliation(s)
- Kailash Gulshan
- From the Department of Cellular and Molecular Medicine (K.G., G.B., H.C., S.W., R.Z., S.L.H., J.D.S.) and Department of Cardiovascular Medicine (S.L.H., J.D.S.), Cleveland Clinic, OH.
| | - Gregory Brubaker
- From the Department of Cellular and Molecular Medicine (K.G., G.B., H.C., S.W., R.Z., S.L.H., J.D.S.) and Department of Cardiovascular Medicine (S.L.H., J.D.S.), Cleveland Clinic, OH
| | - Heather Conger
- From the Department of Cellular and Molecular Medicine (K.G., G.B., H.C., S.W., R.Z., S.L.H., J.D.S.) and Department of Cardiovascular Medicine (S.L.H., J.D.S.), Cleveland Clinic, OH
| | - Shuhui Wang
- From the Department of Cellular and Molecular Medicine (K.G., G.B., H.C., S.W., R.Z., S.L.H., J.D.S.) and Department of Cardiovascular Medicine (S.L.H., J.D.S.), Cleveland Clinic, OH
| | - Renliang Zhang
- From the Department of Cellular and Molecular Medicine (K.G., G.B., H.C., S.W., R.Z., S.L.H., J.D.S.) and Department of Cardiovascular Medicine (S.L.H., J.D.S.), Cleveland Clinic, OH
| | - Stanley L Hazen
- From the Department of Cellular and Molecular Medicine (K.G., G.B., H.C., S.W., R.Z., S.L.H., J.D.S.) and Department of Cardiovascular Medicine (S.L.H., J.D.S.), Cleveland Clinic, OH
| | - Jonathan D Smith
- From the Department of Cellular and Molecular Medicine (K.G., G.B., H.C., S.W., R.Z., S.L.H., J.D.S.) and Department of Cardiovascular Medicine (S.L.H., J.D.S.), Cleveland Clinic, OH.
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Lee-Rueckert M, Escola-Gil JC, Kovanen PT. HDL functionality in reverse cholesterol transport--Challenges in translating data emerging from mouse models to human disease. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:566-83. [PMID: 26968096 DOI: 10.1016/j.bbalip.2016.03.004] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 02/26/2016] [Accepted: 03/04/2016] [Indexed: 12/18/2022]
Abstract
Whereas LDL-derived cholesterol accumulates in atherosclerotic lesions, HDL particles are thought to facilitate removal of cholesterol from the lesions back to the liver thereby promoting its fecal excretion from the body. Because generation of cholesterol-loaded macrophages is inherent to atherogenesis, studies on the mechanisms stimulating the release of cholesterol from these cells and its ultimate excretion into feces are crucial to learn how to prevent lesion development or even induce lesion regression. Modulation of this key anti-atherogenic pathway, known as the macrophage-specific reverse cholesterol transport, has been extensively studied in several mouse models with the ultimate aim of applying the emerging knowledge to humans. The present review provides a detailed comparison and critical analysis of the various steps of reverse cholesterol transport in mouse and man. We attempt to translate this in vivo complex scenario into practical concepts, which could serve as valuable tools when developing novel HDL-targeted therapies.
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28
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Constantinou C, Karavia EA, Xepapadaki E, Petropoulou PI, Papakosta E, Karavyraki M, Zvintzou E, Theodoropoulos V, Filou S, Hatziri A, Kalogeropoulou C, Panayiotakopoulos G, Kypreos KE. Advances in high-density lipoprotein physiology: surprises, overturns, and promises. Am J Physiol Endocrinol Metab 2016; 310:E1-E14. [PMID: 26530157 DOI: 10.1152/ajpendo.00429.2015] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Accepted: 10/30/2015] [Indexed: 12/21/2022]
Abstract
Emerging evidence strongly supports that changes in the HDL metabolic pathway, which result in changes in HDL proteome and function, appear to have a causative impact on a number of metabolic disorders. Here, we provide a critical review of the most recent and novel findings correlating HDL properties and functionality with various pathophysiological processes and disease states, such as obesity, type 2 diabetes mellitus, nonalcoholic fatty liver disease, inflammation and sepsis, bone and obstructive pulmonary diseases, and brain disorders.
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Affiliation(s)
| | - Eleni A Karavia
- Pharmacology Department, University of Patras Medical School, Rio Achaias, Greece
| | - Eva Xepapadaki
- Pharmacology Department, University of Patras Medical School, Rio Achaias, Greece
| | | | - Eugenia Papakosta
- Pharmacology Department, University of Patras Medical School, Rio Achaias, Greece
| | - Marilena Karavyraki
- Pharmacology Department, University of Patras Medical School, Rio Achaias, Greece
| | - Evangelia Zvintzou
- Pharmacology Department, University of Patras Medical School, Rio Achaias, Greece
| | | | - Serafoula Filou
- Pharmacology Department, University of Patras Medical School, Rio Achaias, Greece
| | - Aikaterini Hatziri
- Pharmacology Department, University of Patras Medical School, Rio Achaias, Greece
| | | | | | - Kyriakos E Kypreos
- Pharmacology Department, University of Patras Medical School, Rio Achaias, Greece
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29
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Tamehiro N, Park MH, Hawxhurst V, Nagpal K, Adams ME, Zannis VI, Golenbock DT, Fitzgerald ML. LXR Agonism Upregulates the Macrophage ABCA1/Syntrophin Protein Complex That Can Bind ApoA-I and Stabilized ABCA1 Protein, but Complex Loss Does Not Inhibit Lipid Efflux. Biochemistry 2015; 54:6931-41. [PMID: 26506427 DOI: 10.1021/acs.biochem.5b00894] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Macrophage ABCA1 effluxes lipid and has anti-inflammatory activity. The syntrophins, which are cytoplasmic PDZ protein scaffolding factors, can bind ABCA1 and modulate its activity. However, many of the data assessing the function of the ABCA1-syntrophin interaction are based on overexpression in nonmacrophage cells. To assess endogenous complex function in macrophages, we derived immortalized macrophages from Abca1(+/+) and Abca1(-/-) mice and show their phenotype recapitulates primary macrophages. Abca1(+/+) lines express the CD11B and F4/80 macrophage markers and markedly upregulate cholesterol efflux in response to LXR nuclear hormone agonists. In contrast, immortalized Abca1(-/-) macrophages show no efflux to apoA-I. In response to LPS, Abca1(-/-) macrophages display pro-inflammatory changes, including an increased level of expression of cell surface CD14, and 11-26-fold higher levels of IL-6 and IL-12 mRNA. Given recapitulation of phenotype, we show with these lines that the ABCA1-syntrophin protein complex is upregulated by LXR agonists and can bind apoA-I. Moreover, in immortalized macrophages, combined α1/β2-syntrophin loss modulated ABCA1 cell surface levels and induced pro-inflammatory gene expression. However, loss of all three syntrophin isoforms known to bind ABCA1 did not impair lipid efflux in immortalized or primary macrophages. Thus, the ABCA1-syntrophin protein complex is not essential for ABCA1 macrophage lipid efflux but does directly interact with apoA-I and can modulate the pool of cell surface ABCA1 stabilized by apoA-I.
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Affiliation(s)
- Norimasa Tamehiro
- Lipid Metabolism Unit, Massachusetts General Hospital (MGH), Center for Computational & Integrative Biology (CCIB), Richard B. Simches Research Center , 185 Cambridge Street, 7th Floor #7150, Boston, Massachusetts 02114, United States
| | - Min Hi Park
- Lipid Metabolism Unit, Massachusetts General Hospital (MGH), Center for Computational & Integrative Biology (CCIB), Richard B. Simches Research Center , 185 Cambridge Street, 7th Floor #7150, Boston, Massachusetts 02114, United States
| | - Victoria Hawxhurst
- Lipid Metabolism Unit, Massachusetts General Hospital (MGH), Center for Computational & Integrative Biology (CCIB), Richard B. Simches Research Center , 185 Cambridge Street, 7th Floor #7150, Boston, Massachusetts 02114, United States
| | - Kamalpreet Nagpal
- Department of Medicine, Division of Infectious Diseases and Immunology, University of Massachusetts Medical School , Worcester, Massachusetts 01605, United States
| | - Marv E Adams
- University of Washington , 1705 Northeast Pacific Street, H-418 HSB Campus Box 357290, Seattle, Washington 98195, United States
| | - Vassilis I Zannis
- Whitaker Cardiovascular Institute, Boston University School of Medicine , 700 Albany Street, W509, Boston, Massachusetts 02118, United States
| | - Douglas T Golenbock
- Department of Medicine, Division of Infectious Diseases and Immunology, University of Massachusetts Medical School , Worcester, Massachusetts 01605, United States
| | - Michael L Fitzgerald
- Lipid Metabolism Unit, Massachusetts General Hospital (MGH), Center for Computational & Integrative Biology (CCIB), Richard B. Simches Research Center , 185 Cambridge Street, 7th Floor #7150, Boston, Massachusetts 02114, United States
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30
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Yamauchi Y, Yokoyama S, Chang TY. ABCA1-dependent sterol release: sterol molecule specificity and potential membrane domain for HDL biogenesis. J Lipid Res 2015; 57:77-88. [PMID: 26497474 DOI: 10.1194/jlr.m063784] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Indexed: 01/28/2023] Open
Abstract
Mammalian cells synthesize various sterol molecules, including the C30 sterol, lanosterol, as cholesterol precursors in the endoplasmic reticulum. The build-up of precursor sterols, including lanosterol, displays cellular toxicity. Precursor sterols are found in plasma HDL. How these structurally different sterols are released from cells is poorly understood. Here, we show that newly synthesized precursor sterols arriving at the plasma membrane (PM) are removed by extracellular apoA-I in a manner dependent on ABCA1, a key macromolecule for HDL biogenesis. Analysis of sterol molecules by GC-MS and tracing the fate of radiolabeled acetate-derived sterols in normal and mutant Niemann-Pick type C cells reveal that ABCA1 prefers newly synthesized sterols, especially lanosterol, as the substrates before they are internalized from the PM. We also show that ABCA1 resides in a cholesterol-rich membrane domain resistant to the mild detergent, Brij 98. Blocking ACAT activity increases the cholesterol contents of this domain. Newly synthesized C29/C30 sterols are transiently enriched within this domain, but rapidly disappear from this domain with a half-life of less than 1 h. Our work shows that substantial amounts of precursor sterols are transported to a certain PM domain and are removed by the ABCA1-dependent pathway.
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Affiliation(s)
- Yoshio Yamauchi
- Department of Biochemistry II, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Shinji Yokoyama
- Nutritional Health Science Research Center and Department of Food and Nutritional Sciences, Chubu University, Kasugai 487-8501, Japan
| | - Ta-Yuan Chang
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755
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31
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Ween MP, Armstrong MA, Oehler MK, Ricciardelli C. The role of ABC transporters in ovarian cancer progression and chemoresistance. Crit Rev Oncol Hematol 2015; 96:220-56. [PMID: 26100653 DOI: 10.1016/j.critrevonc.2015.05.012] [Citation(s) in RCA: 116] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 04/08/2015] [Accepted: 05/18/2015] [Indexed: 02/06/2023] Open
Abstract
Over 80% of ovarian cancer patients develop chemoresistance which results in a lethal course of the disease. A well-established cause of chemoresistance involves the family of ATP-binding cassette transporters, or ABC transporters that transport a wide range of substrates including metabolic products, nutrients, lipids, and drugs across extra- and intra-cellular membranes. Expressions of various ABC transporters, shown to reduce the intracellular accumulation of chemotherapy drugs, are increased following chemotherapy and impact on ovarian cancer survival. Although clinical trials to date using ABC transporter inhibitors have been disappointing, ABC transporter inhibition remains an attractive potential adjuvant to chemotherapy. A greater understanding of their physiological functions and role in ovarian cancer chemoresistance will be important for the development of more effective targeted therapies. This article will review the role of the ABC transporter family in ovarian cancer progression and chemoresistance as well as the clinical attempts used to date to reverse chemoresistance.
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Affiliation(s)
- M P Ween
- Lung Research, Hanson Institute and Department of Thoracic Medicine, Royal Adelaide Hospital, Adelaide
| | - M A Armstrong
- Data Management and Analysis Centre, University of Adelaide, Australia
| | - M K Oehler
- Gynaecological Oncology Department, Royal Adelaide Hospital, Australia; School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Australia
| | - C Ricciardelli
- School of Paediatrics and Reproductive Health, Robinson Research Institute, University of Adelaide, Australia.
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32
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Abstract
Numerous epidemiologic studies revealed that high-density lipoprotein (HDL) is an important risk factor for coronary heart disease. There are several well-documented HDL functions such as reversed cholesterol transport, inhibition of inflammation, or inhibition of platelet activation that may account for the atheroprotective effects of this lipoprotein. Mechanistically, these functions are carried out by a direct interaction of HDL particle or its components with receptors localized on the cell surface followed by generation of intracellular signals. Several HDL-associated receptor ligands such as apolipoprotein A-I (apoA-I) or sphingosine-1-phosphate (S1P) have been identified in addition to HDL holoparticles, which interact with surface receptors such as ATP-binding cassette transporter A1 (ABCA1); S1P receptor types 1, 2, and 3 (S1P1, S1P2, and S1P3); or scavenger receptor type I (SR-BI) and activate intracellular signaling cascades encompassing kinases, phospholipases, trimeric and small G-proteins, and cytoskeletal proteins such as actin or junctional protein such as connexin43. In addition, depletion of plasma cell cholesterol mediated by ABCA1, ATP-binding cassette transporter G1 (ABCG1), or SR-BI was demonstrated to indirectly inhibit signaling over proinflammatory or proliferation-stimulating receptors such as Toll-like or growth factor receptors. The present review summarizes the current knowledge regarding the HDL-induced signal transduction and its relevance to athero- and cardioprotective effects as well as other physiological effects exerted by HDL.
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Abstract
ABCA1 mediates the secretion of cellular free cholesterol and phospholipids to an extracellular acceptor, apolipoprotein AI, to form nascent high-density lipoprotein (HDL). Thus, ABCA1 is a key molecule in cholesterol homeostasis. Functional studies of certain Tangier disease mutations demonstrate that ABCA1 has multiple activities, including plasma membrane remodeling and apoAI binding to cell surface, which participate in nascent HDL biogenesis. Recent advances in our understanding of ABCA1 have demonstrated that ABCA1also mediates unfolding the N terminus of apoAI on the cell surface, followed by lipidation of apoAI and release of nascent HDL. Although ABCA1-mediated cholesterol efflux to apoAI can occur on the plasma membrane, the role of apoAI retroendocytosis during cholesterol efflux may play a role in macrophage foam cells that store cholesterol esters in cytoplasmic lipid droplets.
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Affiliation(s)
- Shuhui Wang
- Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland OH 44195, USA
| | - Jonathan D. Smith
- Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland OH 44195, USA
- Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland OH 44195, USA
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34
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Multimarker screening of oxidative stress in aging. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2014; 2014:562860. [PMID: 25147595 PMCID: PMC4124763 DOI: 10.1155/2014/562860] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 04/29/2014] [Accepted: 05/19/2014] [Indexed: 11/20/2022]
Abstract
Aging is a complex process of organism decline in physiological functions. There is no clear theory explaining this phenomenon, but the most accepted one is the oxidative stress theory of aging. Biomarkers of oxidative stress, substances, which are formed during oxidative damage of phospholipids, proteins, and nucleic acids, are present in body fluids of diseased people as well as the healthy ones (in a physiological concentration). 8-iso prostaglandin F2α is the most prominent biomarker of phospholipid oxidative damage, o-tyrosine, 3-chlorotyrosine, and 3-nitrotyrosine are biomarkers of protein oxidative damage, and 8-hydroxy-2′-deoxyguanosine and 8-hydroxyguanosine are biomarkers of oxidative damage of nucleic acids. It is thought that the concentration of biomarkers increases as the age of people increases. However, the concentration of biomarkers in body fluids is very low and, therefore, it is necessary to use a sensitive analytical method. A combination of HPLC and MS was chosen to determine biomarker concentration in three groups of healthy people of a different age (twenty, forty, and sixty years) in order to find a difference among the groups.
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35
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Karavia EA, Zvintzou E, Petropoulou PI, Xepapadaki E, Constantinou C, Kypreos KE. HDL quality and functionality: what can proteins and genes predict? Expert Rev Cardiovasc Ther 2014; 12:521-32. [DOI: 10.1586/14779072.2014.896741] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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36
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Leman LJ, Maryanoff BE, Ghadiri MR. Molecules that mimic apolipoprotein A-I: potential agents for treating atherosclerosis. J Med Chem 2013; 57:2169-96. [PMID: 24168751 DOI: 10.1021/jm4005847] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Certain amphipathic α-helical peptides can functionally mimic many of the properties of full-length apolipoproteins, thereby offering an approach to modulate high-density lipoprotein (HDL) for combating atherosclerosis. In this Perspective, we summarize the key findings and advances over the past 25 years in the development of peptides that mimic apolipoproteins, especially apolipoprotein A-I (apoA-I). This assemblage of information provides a reasonably clear picture of the state of the art in the apolipoprotein mimetic field, an appreciation of the potential for such agents in pharmacotherapy, and a sense of the opportunities for optimizing the functional properties of HDL.
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Affiliation(s)
- Luke J Leman
- Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute , 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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37
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Quazi F, Molday RS. Differential phospholipid substrates and directional transport by ATP-binding cassette proteins ABCA1, ABCA7, and ABCA4 and disease-causing mutants. J Biol Chem 2013; 288:34414-26. [PMID: 24097981 DOI: 10.1074/jbc.m113.508812] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
ABCA1, ABCA7, and ABCA4 are members of the ABCA subfamily of ATP-binding cassette transporters that share extensive sequence and structural similarity. Mutations in ABCA1 cause Tangier disease characterized by defective cholesterol homeostasis and high density lipoprotein (HDL) deficiency. Mutations in ABCA4 are responsible for Stargardt disease, a degenerative disorder associated with severe loss in central vision. Although cell-based studies have implicated ABCA proteins in lipid transport, the substrates and direction of transport have not been firmly established. We have purified and reconstituted ABCA1, ABCA7, and ABCA4 into liposomes for fluorescent-lipid transport studies. ABCA1 actively exported or flipped phosphatidylcholine, phosphatidylserine, and sphingomyelin from the cytoplasmic to the exocytoplasmic leaflet of membranes, whereas ABCA7 preferentially exported phosphatidylserine. In contrast, ABCA4 transported phosphatidylethanolamine in the reverse direction. The same phospholipids stimulated the ATPase activity of these ABCA transporters. The transport and ATPase activities of ABCA1 and ABCA4 were reduced by 25% in the presence of 20% cholesterol. Nine ABCA1 Tangier mutants and the corresponding ABCA4 Stargardt mutants showed significantly reduced phospholipid transport activity and subcellular mislocalization. These studies provide the first direct evidence for ABCA1 and ABCA7 functioning as phospholipid transporters and suggest that this activity is an essential step in the loading of apoA-1 with phospholipids for HDL formation.
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Affiliation(s)
- Faraz Quazi
- From the Department of Biochemistry and Molecular Biology, Centre for Macular Research, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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38
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Ontsouka EC, Huang X, Stieger B, Albrecht C. Characteristics and functional relevance of apolipoprotein-A1 and cholesterol binding in mammary gland tissues and epithelial cells. PLoS One 2013; 8:e70407. [PMID: 23936200 PMCID: PMC3729845 DOI: 10.1371/journal.pone.0070407] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 06/18/2013] [Indexed: 11/19/2022] Open
Abstract
Cholesterol in milk is derived from the circulating blood through a complex transport process involving the mammary alveolar epithelium. Details of the mechanisms involved in this transfer are unclear. Apolipoprotein-AI (apoA-I) is an acceptor of cellular cholesterol effluxed by the ATP-binding cassette (ABC) transporter A1 (ABCA1). We aimed to 1) determine the binding characteristics of (125)I-apoA-I and (3)H-cholesterol to enriched plasma membrane vesicles (EPM) isolated from lactating and non-lactating bovine mammary glands (MG), 2) optimize the components of an in vitro model describing cellular (3)H-cholesterol efflux in primary bovine mammary epithelial cells (MeBo), and 3) assess the vectorial cholesterol transport in MeBo using Transwell(®) plates. The amounts of isolated EPM and the maximal binding capacity of (125)I-apoA-I to EPM differed depending on the MG's physiological state, while the kinetics of (3)H-cholesterol and (125)I-apoA-I binding were similar. (3)H-cholesterol incorporated maximally to EPM after 25±9 min. The time to achieve the half-maximum binding of (125)I-apoA-I at equilibrium was 3.3±0.6 min. The dissociation constant (KD) of (125)I-apoA-I ranged between 40-74 nmol/L. Cholesterol loading to EPM increased both cholesterol content and (125)I-apoA-I binding. The ABCA1 inhibitor Probucol displaced (125)I-apoA-I binding to EPM and reduced (3)H-cholesterol efflux in MeBo. Time-dependent (3)H-cholesterol uptake and efflux showed inverse patterns. The defined binding characteristics of cholesterol and apoA-I served to establish an efficient and significantly shorter cholesterol efflux protocol that had been used in MeBo. The application of this protocol in Transwell(®) plates with the upper chamber mimicking the apical (milk-facing) and the bottom chamber corresponding to the basolateral (blood-facing) side of cells showed that the degree of (3)H-cholesterol efflux in MeBo differed significantly between the apical and basolateral aspects. Our findings support the importance of the apoA-I/ABCA1 pathway in MG cholesterol transport and suggest its role in influencing milk composition and directing cholesterol back into the bloodstream.
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Affiliation(s)
- Edgar Corneille Ontsouka
- Institute of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Bern, Bern, Switzerland
- Swiss National Center of Competence in Research, NCCR TransCure, University of Bern, Bern, Switzerland
| | - Xiao Huang
- Institute of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Bern, Bern, Switzerland
- Swiss National Center of Competence in Research, NCCR TransCure, University of Bern, Bern, Switzerland
| | - Bruno Stieger
- Swiss National Center of Competence in Research, NCCR TransCure, University of Bern, Bern, Switzerland
- Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, Zürich, Switzerland
| | - Christiane Albrecht
- Institute of Biochemistry and Molecular Medicine, Faculty of Medicine, University of Bern, Bern, Switzerland
- Swiss National Center of Competence in Research, NCCR TransCure, University of Bern, Bern, Switzerland
- * E-mail:
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Abstract
Members of the ABCA (ATP-binding cassette subfamily A) family are characterized by their ability to transport lipids across cellular membranes and regulate lipid homoeostasis in the brain and peripheral tissues. ABCA8 is a little-known member of this subfamily that was originally cloned from human brain libraries and has no known function. In an effort to elucidate the role of ABCA8 in the brain we first undertook a comprehensive analysis of its expression in the human brain. ABCA8 was differentially expressed in multiple regions of adult human brains with significantly higher expression in oligodendrocyte-enriched white matter regions compared with grey matter cortical regions. We then assessed the impact of ABCA8 on sphingomyelin production in oligodendrocyte and showed that ABCA8 was able to significantly stimulate both sphingomyelin synthase 1 expression and sphingomyelin production. Furthermore, ABCA8 expression in the prefrontal cortex across the human life span correlated strongly with age-associated myelination, and the myelinating gene p25α was significantly up-regulated with ABCA8. The present study represents the first extensive expression and functional study of ABCA8 in the human brain and the results strongly suggest that ABCA8 regulates lipid metabolism in oligodendrocytes and potentially plays a role in myelin formation and maintenance.
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Wang S, Gulshan K, Brubaker G, Hazen SL, Smith JD. ABCA1 mediates unfolding of apolipoprotein AI N terminus on the cell surface before lipidation and release of nascent high-density lipoprotein. Arterioscler Thromb Vasc Biol 2013; 33:1197-205. [PMID: 23559627 DOI: 10.1161/atvbaha.112.301195] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To gain insight into the mechanism by which ABCA1 generates nascent high-density lipoprotein. APPROACH AND RESULTS HEK293 cells were stably transfected with ABCA1 vectors, encoding wild type, and the W590S and C1477R Tangier disease mutation isoforms, along with the K939M ATP-binding domain mutant. Apolipoprotein AI (ApoAI) binding, plasma membrane remodeling, cholesterol efflux, apoAI cell surface unfolding, and apoAI cell surface lipidation were determined, the latter 2 measured using novel fluorescent apoAI indicators. The W590S isoform had decreased plasma membrane remodeling and lipid efflux activities, and the C1477R isoform had decreased apoAI binding, and lipid efflux activities, whereas the K939M isoform did not bind apoAI, remodel the membrane, or efflux cholesterol. However, all ABCA1 isoforms led to apoAI unfolding at the cell surface, which was higher for the isoforms that increased apoAI binding. ApoAI lipidation was not detected on ABCA1-expressing cells, only in the conditioned medium, consistent with rapid release of nascent high-density lipoprotein from ABCA1-expressing cells. CONCLUSIONS We identified a third activity of ABCA1, the ability to unfold the N terminus of apoAI on the cell surface. Our results support a model in which unfolded apoAI on the cell surface is an intermediate in its lipidation and that, once apoAI is lipidated, it forms an unstable structure that is rapidly released from the cells to generate high-density lipoprotein.
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Affiliation(s)
- Shuhui Wang
- Department of Cellular and Molecular Medicine, Cleveland Clinic, Cleveland, OH 44195, USA
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41
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Bonamassa B, Moschetta A. Atherosclerosis: lessons from LXR and the intestine. Trends Endocrinol Metab 2013; 24:120-8. [PMID: 23158108 DOI: 10.1016/j.tem.2012.10.004] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 10/12/2012] [Accepted: 10/18/2012] [Indexed: 12/17/2022]
Abstract
Modulation of the cholesterol-sensing liver X receptors (LXRs) and their downstream targets has emerged as promising therapeutic avenues in atherosclerosis. The intestine is important for its unique capabilities to act as a gatekeeper for cholesterol absorption and to participate in the process of cholesterol elimination in the feces and reverse cholesterol transport (RCT). Pharmacological and genetic intestine-specific LXR activation have been shown to protect against atherosclerosis. In this review we discuss the LXR-targeted molecular players in the enterocytes as well as the intestine-driven pathways contributing to cholesterol homeostasis with therapeutic potential as targets in the prevention and treatment of atherosclerosis..
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Affiliation(s)
- Barbara Bonamassa
- Laboratory of Lipid Metabolism and Cancer, Department of Translational Pharmacology, Consorzio Mario Negri Sud, Via Nazionale 8/A, 66030 Santa Maria Imbaro (CH), Italy
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42
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Reboul E, Dyka FM, Quazi F, Molday RS. Cholesterol transport via ABCA1: new insights from solid-phase binding assay. Biochimie 2012. [PMID: 23201557 DOI: 10.1016/j.biochi.2012.11.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
It is now well established that the ATP-binding cassette transporter A1 (ABCA1) plays a pivotal role in HDL metabolism, reverse cholesterol transport and net efflux of cellular cholesterol and phospholipids. We aimed to resolve some uncertainties related to the putative function of ABCA1 as a mediator of lipid transport by using a methodology developed in the laboratory to isolate a protein and study its interactions with other compounds. ABCA1 was tagged with the 1D4 peptide at the C terminus and expressed in human HEK 293 cells. Preliminary experiments showed that the tag modified neither the protein expression/localization within the cells nor the ability of ABCA1 to promote cholesterol cellular efflux to apolipoprotein A-I. ABCA1-1D4 was then purified and reconstituted in liposomes. ABCA1 displayed an ATPase activity in phospholipid liposomes that was significantly decreased by cholesterol. Finally, interactions with either cholesterol or apolipoprotein A-I were assessed by binding experiments with protein immobilized on an immunoaffinity matrix. Solid-phase binding assays showed no direct binding of cholesterol or apolipoprotein A-I to ABCA1. Overall, our data support the hypothesis that ABCA1 is able to mediate the transport of cholesterol from cells without direct interaction and that apo A-I primarily binds to membrane surface or accessory protein(s).
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Affiliation(s)
- Emmanuelle Reboul
- INRA, UMR1260 Nutrition Obesity and Risk of Thrombosis, F-13385 Marseille, France.
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Coleman JA, Quazi F, Molday RS. Mammalian P4-ATPases and ABC transporters and their role in phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:555-74. [PMID: 23103747 DOI: 10.1016/j.bbalip.2012.10.006] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/16/2012] [Accepted: 10/18/2012] [Indexed: 02/08/2023]
Abstract
Transport of phospholipids across cell membranes plays a key role in a wide variety of biological processes. These include membrane biosynthesis, generation and maintenance of membrane asymmetry, cell and organelle shape determination, phagocytosis, vesicle trafficking, blood coagulation, lipid homeostasis, regulation of membrane protein function, apoptosis, etc. P(4)-ATPases and ATP binding cassette (ABC) transporters are the two principal classes of membrane proteins that actively transport phospholipids across cellular membranes. P(4)-ATPases utilize the energy from ATP hydrolysis to flip aminophospholipids from the exocytoplasmic (extracellular/lumen) to the cytoplasmic leaflet of cell membranes generating membrane lipid asymmetry and lipid imbalance which can induce membrane curvature. Many ABC transporters play crucial roles in lipid homeostasis by actively transporting phospholipids from the cytoplasmic to the exocytoplasmic leaflet of cell membranes or exporting phospholipids to protein acceptors or micelles. Recent studies indicate that some ABC proteins can also transport phospholipids in the opposite direction. The importance of P(4)-ATPases and ABC transporters is evident from the findings that mutations in many of these transporters are responsible for severe human genetic diseases linked to defective phospholipid transport. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
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Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
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Zhao GJ, Yin K, Fu YC, Tang CK. The interaction of ApoA-I and ABCA1 triggers signal transduction pathways to mediate efflux of cellular lipids. Mol Med 2012; 18:149-58. [PMID: 22064972 DOI: 10.2119/molmed.2011.00183] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 11/01/2011] [Indexed: 12/17/2022] Open
Abstract
Reverse cholesterol transport (RCT) has been characterized as a crucial step for antiatherosclerosis, which is initiated by ATP-binding cassette A1 (ABCA1) to mediate the efflux of cellular phospholipids and cholesterol to lipid-free apolipoprotein A-I (apoA-I). However, the mechanisms underlying apoA-I/ABCA1 interaction to lead to the lipidation of apoA-I are poorly understood. There are several models proposed for the interaction of apoA-I with ABCA1 as well as the lipidation of apoA-I mediated by ABCA1. ApoA-I increases the levels of ABCA1 protein markedly. In turn, ABCA1 can stabilize apoA-I. The interaction of apoA-I with ABCA1 could activate signaling molecules that modulate posttranslational ABCA1 activity or lipid transport activity. The key signaling molecules in these processes include protein kinase A (PKA), protein kinase C (PKC), Janus kinase 2 (JAK2), Rho GTPases and Ca²⁺, and many factors also could influence the interaction of apoA-I with ABCA1. This review will summarize these mechanisms for the apoA-I interaction with ABCA1 as well as the signal transduction pathways involved in these processes.
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Affiliation(s)
- Guo-Jun Zhao
- Institute of Cardiovascular Research, Key Laboratory for Atherosclerology of Hunan Province, Life Science Research Center, University of South China, Hengyang, China
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45
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Abstract
ABC (ATP-binding cassette) proteins actively transport a wide variety of substrates, including peptides, amino acids, sugars, metals, drugs, vitamins and lipids, across extracellular and intracellular membranes. Of the 49 hum an ABC proteins, a significant number are known to mediate the extrusion of lipids from membranes or the flipping of membrane lipids across the bilayer to generate and maintain membrane lipid asymmetry. Typical lipid substrates include phospholipids, sterols, sphingolipids, bile acids and related lipid conjugates. Members of the ABCA subfamily of ABC transporters and other ABC proteins such as ABCB4, ABCG1 and ABCG5/8 implicated in lipid transport play important roles in diverse biological processes such as cell signalling, membrane lipid asymmetry, removal of potentially toxic compounds and metabolites, and apoptosis. The importance of these ABC lipid transporters in cell physiology is evident from the finding that mutations in the genes encoding many of these proteins are responsible for severe inherited diseases. For example, mutations in ABCA1 cause Tangier disease associated with defective efflux of cholesterol and phosphatidylcholine from the plasma membrane to the lipid acceptor protein apoA1 (apolipoprotein AI), mutations in ABCA3 cause neonatal surfactant deficiency associated with a loss in secretion of the lipid pulmonary surfactants from lungs of newborns, mutations in ABCA4 cause Stargardt macular degeneration, a retinal degenerative disease linked to the reduced clearance of retinoid compounds from photoreceptor cells, mutations in ABCA12 cause harlequin and lamellar ichthyosis, skin diseases associated with defective lipid trafficking in keratinocytes, and mutations in ABCB4 and ABCG5/ABCG8 are responsible for progressive intrafamilial hepatic disease and sitosterolaemia associated with defective phospholipid and sterol transport respectively. This chapter highlights the involvement of various mammalian ABC transporters in lipid transport in the context of their role in cell signalling, cellular homoeostasis, apoptosis and inherited disorders.
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Hossain MA, Ngeth S, Chan T, Oda MN, Francis GA. Lipid-bound apolipoproteins in tyrosyl radical-oxidized HDL stabilize ABCA1 like lipid-free apolipoprotein A-I. BMC BIOCHEMISTRY 2012; 13:1. [PMID: 22248050 PMCID: PMC3292454 DOI: 10.1186/1471-2091-13-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/21/2011] [Accepted: 01/16/2012] [Indexed: 11/20/2022]
Abstract
Background ATP-binding cassette transporter A1 (ABCA1) mediates the lipidation of exchangeable apolipoproteins, the rate-limiting step in the formation of high density lipoproteins (HDL). We previously demonstrated that HDL oxidized ex vivo by peroxidase-generated tyrosyl radical (tyrosylated HDL, tyrHDL) increases the availability of cellular cholesterol for efflux and reduces the development of atherosclerosis when administered to apolipoprotein E-deficient mice as compared to treatment with control HDL. Results In the current study we determined that tyrHDL requires functional ABCA1 for this enhanced activity. Like lipid-free apolipoprotein A-I (apoA-I), tyrHDL increases total and cell surface ABCA1, inhibits calpain-dependent and -independent proteolysis of ABCA1, and can be bound by cell surface ABCA1 in human skin fibroblasts. Additionally, tyrHDL apoproteins are susceptible to digestion by enteropeptidase like lipid-free apoA-I, but unlike lipid-bound apoA-I on HDL, which is resistant to proteolysis. Conclusions These results provide the first evidence that lipid-bound apolipoproteins on the surface of spherical HDL particles can behave like lipid-free apoA-I to increase ABCA1 protein levels and activity.
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Affiliation(s)
- Mohammad A Hossain
- Department of Medicine, UBC James Hogg Research Centre, Heart and Lung Institute, St, Paul's Hospital, Vancouver, British Columbia, Canada
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Nagao K, Takahashi K, Azuma Y, Takada M, Kimura Y, Matsuo M, Kioka N, Ueda K. ATP hydrolysis-dependent conformational changes in the extracellular domain of ABCA1 are associated with apoA-I binding. J Lipid Res 2011; 53:126-36. [PMID: 22028339 DOI: 10.1194/jlr.m019976] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
ATP-binding cassette protein A1 (ABCA1) plays a major role in cholesterol homeostasis and high-density lipoprotein (HDL) metabolism. Although it is predicted that apolipoprotein A-I (apoA-I) directly binds to ABCA1, the physiological importance of this interaction is still controversial and the conformation required for apoA-I binding is unclear. In this study, the role of the two nucleotide-binding domains (NBD) of ABCA1 in apoA-I binding was determined by inserting a TEV protease recognition sequence in the linker region of ABCA1. Analyses of ATP binding and occlusion to wild-type ABCA1 and various NBD mutants revealed that ATP binds equally to both NBDs and is hydrolyzed at both NBDs. The interaction with apoA-I and the apoA-I-dependent cholesterol efflux required not only ATP binding but also hydrolysis in both NBDs. NBD mutations and cellular ATP depletion decreased the accessibility of antibodies to a hemagglutinin (HA) epitope that was inserted at position 443 in the extracellular domain (ECD), suggesting that the conformation of ECDs is altered by ATP hydrolysis at both NBDs. These results suggest that ATP hydrolysis at both NBDs induces conformational changes in the ECDs, which are associated with apoA-I binding and cholesterol efflux.
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Affiliation(s)
- Kohjiro Nagao
- Laboratory of Cellular Biochemistry, Division of Applied Life Sciences, Graduate School of Agriculture, Kyoto University , Kyoto 606-8502, Japan
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Liu Y, Tang C. Regulation of ABCA1 functions by signaling pathways. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:522-9. [PMID: 21920460 DOI: 10.1016/j.bbalip.2011.08.015] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Revised: 08/02/2011] [Accepted: 08/20/2011] [Indexed: 10/17/2022]
Abstract
ATP-binding cassette transporter A1 (ABCA1) is an integral cell membrane protein that protects cardiovascular disease by at least two mechanisms: by export of excess cholesterol from cells and by suppression of inflammation. ABCA1 exports cholesterol and phospholipids from cells by multiple steps that involve forming cell surface lipid domains, binding of apolipoproteins to ABCA1, activating signaling pathways, and solubilizing these lipids by apolipoproteins. ABCA1 executes its anti-inflammatory effect by modifying cell membrane lipid rafts and directly activating signaling pathways. The interaction of apolipoproteins with ABCA1 activates multiple signaling pathways, including Janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3), protein kinase A, Rho family G protein CDC42 and protein kinase C. Activating protein kinase A and Rho family G protein CDC42 regulates ABCA1-mediated lipid efflux, activating PKC stabilizes ABCA1 protein, and activating JAK2/STAT3 regulates both ABCA1-mediated lipid efflux and anti-inflammation. Thus, ABCA1 behaves both as a lipid exporter and a signaling receptor. Targeting ABCA1 receptor-like property using agonists for ABCA1 protein could become a promising new therapeutic target for increasing ABCA1 function and treating cardiovascular disease. This article is part of a Special Issue entitled Advances in High Density Lipoprotein Formation and Metabolism: A Tribute to John F. Oram (1945-2010).
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Affiliation(s)
- Yuhua Liu
- Deparment of Medicine, Diabetes and Obesity Center of Excellence, University of Washington, Seattle, WA 98195-8055, USA
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Nagao K, Tomioka M, Ueda K. Function and regulation of ABCA1 - membrane meso-domain organization and reorganization. FEBS J 2011; 278:3190-203. [DOI: 10.1111/j.1742-4658.2011.08170.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
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50
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Terao Y, Ayaori M, Ogura M, Yakushiji E, Uto-Kondo H, Hisada T, Ozasa H, Takiguchi S, Nakaya K, Sasaki M, Komatsu T, Iizuka M, Horii S, Mochizuki S, Yoshimura M, Ikewaki K. Effect of sulfonylurea agents on reverse cholesterol transport in vitro and vivo. J Atheroscler Thromb 2011; 18:513-30. [PMID: 21636950 DOI: 10.5551/jat.7641] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
AIM Reverse cholesterol transport (RCT) is a critical mechanism for the anti-atherogenic property of HDL. The inhibitory effect of the sulfonylurea agent (SUA) glibenclamide on ATP binding-cassette transporter (ABC) A1 may decrease HDL function but it remains unclear whether it attenuates RCT in vivo. We therefore investigated how the SUAs glibenclamide and glimepiride affected the functionality of ABCA1/ABCG1 and scavenger receptor class B type I (SR-BI) expression in macrophages in vitro and overall RCT in vivo. METHODS RAW264.7, HEK293 and BHK-21 cells were used for in vitro studies. To investigate RCT in vivo, 3H-cholesterol-labeled and acetyl LDL-loaded RAW264.7 cells were injected into mice. RESULTS High dose (500µM) of glibenclamide inhibited ABCA1 function and apolipoprotein A-I (apoA-I)-mediated cholesterol efflux, and attenuated ABCA1 expression. Although glimepiride maintained apoA-I-mediated cholesterol efflux from RAW264.7 cells, like glibenclamide, it inhibited ABCA1-mediated cholesterol efflux from transfected HEK293 cells. Similarly, the SUAs inhibited SR-BI-mediated cholesterol efflux from transfected BHK-21 cells. High doses of SUAs increased ABCG1 expression in RAW264.7 cells, promoting HDL-mediated cholesterol efflux in an ABCG1-independent manner. Low doses (0.1-100 µM) of SUAs did not affect cholesterol efflux from macrophages despite dose-dependent increases in ABCA1/G1 expression. Furthermore, they did not change RCT or plasma lipid levels in mice. CONCLUSION High doses of SUAs inhibited the functionality of ABCA1/SR-BI, but not ABCG1. At lower doses, they had no unfavorable effects on cholesterol efflux or overall RCT in vivo. These results indicate that SUAs do not have adverse effects on atherosclerosis contrary to previous findings for glibenclamide.
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Affiliation(s)
- Yoshio Terao
- Division of Anti-aging, Department of Internal Medicine, National Defense Medical College, Saitama, Japan
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