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Joshi S, López L, Morosi LG, Amadio R, Pachauri M, Bestagno M, Ogar IP, Giacca M, Piperno GM, Vorselen D, Benvenuti F. Tim4 enables large peritoneal macrophages to cross-present tumor antigens at early stages of tumorigenesis. Cell Rep 2024; 43:114096. [PMID: 38607919 DOI: 10.1016/j.celrep.2024.114096] [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: 09/14/2023] [Revised: 02/20/2024] [Accepted: 03/27/2024] [Indexed: 04/14/2024] Open
Abstract
Receptors controlling the cross-presentation of tumor antigens by macrophage subsets in cancer tissues are poorly explored. Here, we show that TIM4+ large peritoneal macrophages efficiently capture and cross-present tumor-associated antigens at early stages of peritoneal infiltration by ovarian cancer cells. The phosphatidylserine (PS) receptor TIM4 promotes maximal uptake of dead cells or PS-coated artificial targets and triggers inflammatory and metabolic gene programs in combination with cytoskeletal remodeling and upregulation of transcriptional signatures related to antigen processing. At the cellular level, TIM4-mediated engulfment induces nucleation of F-actin around nascent phagosomes, delaying the recruitment of vacuolar ATPase, acidification, and cargo degradation. In vivo, TIM4 deletion blunts induction of early anti-tumoral effector CD8 T cells and accelerates the progression of ovarian tumors. We conclude that TIM4-mediated uptake drives the formation of specialized phagosomes that prolong the integrity of ingested antigens and facilitate cross-presentation, contributing to immune surveillance of the peritoneum.
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Affiliation(s)
- Sonal Joshi
- Cellular Immunology, International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Lucía López
- Cellular Immunology, International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Luciano Gastón Morosi
- Cellular Immunology, International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Roberto Amadio
- Cellular Immunology, International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Manendra Pachauri
- Department of Medical, Surgical, and Health Sciences, University of Trieste and International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Marco Bestagno
- Cellular Immunology, International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Ironya Paul Ogar
- Cellular Immunology, International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy; Department of Biochemistry, Faculty of Basic Medical Sciences, College of Medical Sciences, University of Calabar, P.M.B. 1115 Calabar, Cross River State, Nigeria
| | - Mauro Giacca
- Department of Medical, Surgical, and Health Sciences, University of Trieste and International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy; King's College London, British Heart Foundation Center of Research Excellence, School of Cardiovascular Medicine & Sciences, London, UK
| | - Giulia Maria Piperno
- Cellular Immunology, International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| | - Daan Vorselen
- Department of Cell Biology & Immunology, Wageningen University & Research, 6708 PD Wageningen, the Netherlands
| | - Federica Benvenuti
- Cellular Immunology, International Center for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy.
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Ni D, Lei C, Liu M, Peng J, Yi G, Mo Z. Cell death in atherosclerosis. Cell Cycle 2024; 23:495-518. [PMID: 38678316 PMCID: PMC11135874 DOI: 10.1080/15384101.2024.2344943] [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: 08/10/2022] [Accepted: 04/14/2024] [Indexed: 04/29/2024] Open
Abstract
A complex and evolutionary process that involves the buildup of lipids in the arterial wall and the invasion of inflammatory cells results in atherosclerosis. Cell death is a fundamental biological process that is essential to the growth and dynamic equilibrium of all living things. Serious cell damage can cause a number of metabolic processes to stop, cell structure to be destroyed, or other irreversible changes that result in cell death. It is important to note that studies have shown that the two types of programmed cell death, apoptosis and autophagy, influence the onset and progression of atherosclerosis by controlling these cells. This could serve as a foundation for the creation of fresh atherosclerosis prevention and treatment strategies. Therefore, in this review, we summarized the molecular mechanisms of cell death, including apoptosis, pyroptosis, autophagy, necroptosis, ferroptosis and necrosis, and discussed their effects on endothelial cells, vascular smooth muscle cells and macrophages in the process of atherosclerosis, so as to provide reference for the next step to reveal the mechanism of atherosclerosis.
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Affiliation(s)
- Dan Ni
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang, Hunan, China
- Guangxi Key Laboratory of Diabetic Systems Medicine, Department of Histology and Embryology, Guilin Medical University, Guilin, Guangxi, China
| | - Cai Lei
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang, Hunan, China
| | - Minqi Liu
- Guangxi Key Laboratory of Diabetic Systems Medicine, Department of Histology and Embryology, Guilin Medical University, Guilin, Guangxi, China
- Guangxi Province Postgraduate Co-training Base for Cooperative Innovation in Basic Medicine (Guilin Medical University and Yueyang Women & Children’s Medical Center), Yueyang, China
| | - Jinfu Peng
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang, Hunan, China
| | - Guanghui Yi
- Institute of Cardiovascular Disease, Key Lab for Arteriosclerology of Hunan Province, University of South China, Hengyang, Hunan, China
| | - Zhongcheng Mo
- Guangxi Key Laboratory of Diabetic Systems Medicine, Department of Histology and Embryology, Guilin Medical University, Guilin, Guangxi, China
- Guangxi Province Postgraduate Co-training Base for Cooperative Innovation in Basic Medicine (Guilin Medical University and Yueyang Women & Children’s Medical Center), Yueyang, China
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3
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Behl T, Sehgal A, Grover M, Singh S, Sharma N, Bhatia S, Al-Harrasi A, Aleya L, Bungau S. Uncurtaining the pivotal role of ABC transporters in diabetes mellitus. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:41533-41551. [PMID: 34085197 DOI: 10.1007/s11356-021-14675-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 05/27/2021] [Indexed: 06/12/2023]
Abstract
The metabolic disorders are the edge points for the initiation of various diseases. These disorders comprised of several diseases including diabetes, obesity, and cardiovascular complications. Worldwide, the prevalence of these disorders is increasing day by day. The world's population is at higher threat of developing metabolic disease, especially diabetes. Therefore, there is an impregnable necessity of searching for a newer therapeutic target to reduce the burden of these disorders. Diabetes mellitus (DM) is marked with the dysregulated insulin secretion and resistance. The lipid and glucose transporters portray a pivotal role in the metabolism and transport of both of these. The excess production of lipid and glucose and decreased clearance of these leads to the emergence of DM. The ATP-binding cassette transporters (ABCT) are important for the metabolism of glucose and lipid. Various studies suggest the key involvement of ABCT in the pathologic process of different diseases. In addition, the involvement of other pathways, including IGF signaling, P13-Akt/PKC/MAPK signaling, and GLP-1 via regulation of ABCT, may help develop new treatment strategies to cope with insulin resistance dysregulated glucose metabolism, key features in DM.
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Affiliation(s)
- Tapan Behl
- Chitkara College of Pharmacy, Chitkara University, Punjab, India.
| | - Aayush Sehgal
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Madhuri Grover
- BS Anangpuria Institute of Pharmacy, Faridabad, Haryana, India
| | - Sukhbir Singh
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Neelam Sharma
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Saurabh Bhatia
- Amity Institute of Pharmacy, Amity University, Gurugram, Haryana, India
- Natural & Medical Sciences Research Centre, University of Nizwa, Birkat Al Mauz, Nizwa, Oman
| | - Ahmed Al-Harrasi
- Natural & Medical Sciences Research Centre, University of Nizwa, Birkat Al Mauz, Nizwa, Oman
| | - Lotfi Aleya
- Chrono-Environment Laboratory, UMR CNRS 6249, Bourgogne Franche-Comté University, Besançon, France
| | - Simona Bungau
- Department of Pharmacy, Faculty of Pharmacy, University of Oradea, Oradea, Romania
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4
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Adamson SE, Polanowska-Grabowska R, Marqueen K, Griffiths R, Angdisen J, Breevoort SR, Schulman IG, Leitinger N. Deficiency of Dab2 (Disabled Homolog 2) in Myeloid Cells Exacerbates Inflammation in Liver and Atherosclerotic Plaques in LDLR (Low-Density Lipoprotein Receptor)-Null Mice-Brief Report. Arterioscler Thromb Vasc Biol 2018; 38:1020-1029. [PMID: 29599136 PMCID: PMC5920703 DOI: 10.1161/atvbaha.117.310467] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 03/06/2018] [Indexed: 02/05/2023]
Abstract
OBJECTIVE Inflammatory macrophages promote the development of atherosclerosis. We have identified the adaptor protein Dab2 (disabled homolog 2) as a regulator of phenotypic polarization in macrophages. The absence of Dab2 in myeloid cells promotes an inflammatory phenotype, but the impact of myeloid Dab2 deficiency on atherosclerosis has not been shown. APPROACH AND RESULTS To determine the role of myeloid Dab2 in atherosclerosis, Ldlr-/- mice were reconstituted with either Dab2-positive or Dab2-deficient bone marrow and fed a western diet. Consistent with our previous finding that Dab2 inhibits NFκB (nuclear factor κ-light-chain-enhancer of activated B cells) signaling in macrophages, Ldlr-/- mice reconstituted with Dab2-deficient bone marrow had increased systemic inflammation as evidenced by increased serum IL-6 (interleukin-6) levels and increased inflammatory cytokine expression levels in liver. Serum lipid levels were significantly lower in Ldlr-/- mice reconstituted with Dab2-deficient bone marrow, and further examination of livers from these mice revealed drastically increased inflammatory tissue damage and massive infiltration of immune cells. Surprisingly, the atherosclerotic lesion burden in Ldlr-/- mice reconstituted with Dab2-deficient bone marrow was decreased compared with Ldlr-/- mice reconstituted with wild-type bone marrow. Further analysis of aortic root sections revealed increased macrophage content and evidence of increased apoptosis in lesions from Ldlr-/- mice reconstituted with Dab2-deficient bone marrow but no difference in collagen or α-smooth muscle actin content. CONCLUSIONS Dab2 deficiency in myeloid cells promotes inflammation in livers and atherosclerotic plaques in a mouse model of atherosclerosis. Nevertheless, decreased serum lipids as a result of massive inflammatory liver damage may preclude an appreciable increase in atherosclerotic lesion burden in mice reconstituted with Dab2-deficient bone marrow.
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Affiliation(s)
- Samantha E Adamson
- From the Department of Pharmacology (S.E.A., R.P.-G., K.M., R.G., J.A., S.R.B., I.G.S., N.L.)
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville (S.E.A., R.P.-G., R.G., N.L.)
| | - Renata Polanowska-Grabowska
- From the Department of Pharmacology (S.E.A., R.P.-G., K.M., R.G., J.A., S.R.B., I.G.S., N.L.)
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville (S.E.A., R.P.-G., R.G., N.L.)
| | - Kathryn Marqueen
- From the Department of Pharmacology (S.E.A., R.P.-G., K.M., R.G., J.A., S.R.B., I.G.S., N.L.)
| | - Rachael Griffiths
- From the Department of Pharmacology (S.E.A., R.P.-G., K.M., R.G., J.A., S.R.B., I.G.S., N.L.)
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville (S.E.A., R.P.-G., R.G., N.L.)
| | - Jerry Angdisen
- From the Department of Pharmacology (S.E.A., R.P.-G., K.M., R.G., J.A., S.R.B., I.G.S., N.L.)
| | - Sarah R Breevoort
- From the Department of Pharmacology (S.E.A., R.P.-G., K.M., R.G., J.A., S.R.B., I.G.S., N.L.)
| | - Ira G Schulman
- From the Department of Pharmacology (S.E.A., R.P.-G., K.M., R.G., J.A., S.R.B., I.G.S., N.L.)
| | - Norbert Leitinger
- From the Department of Pharmacology (S.E.A., R.P.-G., K.M., R.G., J.A., S.R.B., I.G.S., N.L.)
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville (S.E.A., R.P.-G., R.G., N.L.)
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Davis W, Tew KD. ATP-binding cassette transporter-2 (ABCA2) as a therapeutic target. Biochem Pharmacol 2017; 151:188-200. [PMID: 29223352 DOI: 10.1016/j.bcp.2017.11.018] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 11/27/2017] [Indexed: 12/28/2022]
Abstract
The ATP binding cassette transporter ABCA2 is primarily an endolysosomal membrane protein that demonstrates pleiotropic functionalities, coalescing around the maintenance of homeostasis of sterols, sphingolipids and cholesterol. It is most highly expressed in brain tissue and ABCA2 knockout mice express neurological defects consistent with aberrant myelination. Increased expression of the transporter has been linked with resistance to cancer drugs, particularly those possessing a steroid backbone and gene expression (in concert with other genes involved in cholesterol metabolism) was found to be regulated by sterols. Moreover, in macrophages ABCA2 is influenced by sterols and has a role in regulating cholesterol sequestration, potentially important in cardiovascular disease. Accumulating data indicate the critical importance of ABCA2 in mediating movement of sphingolipids within cellular compartments and these have been implicated in various aspects of cholesterol trafficking. Perhaps because the functions of ABCA2 are linked with membrane building blocks, there are reports linking it with human pathologies, including, cholesterolemias and cardiovascular disease, Alzheimer's and cancer. The present review addresses whether there is now sufficient information to consider ABCA2 as a plausible therapeutic target.
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Affiliation(s)
- Warren Davis
- Dept. of Cell & Molecular Pharmacology & Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, BSB, MSC 509, Charleston, SC 29425, United States
| | - Kenneth D Tew
- Dept. of Cell & Molecular Pharmacology & Experimental Therapeutics, Medical University of South Carolina, 173 Ashley Avenue, BSB, MSC 509, Charleston, SC 29425, United States.
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Zhong W, Pan G, Wang L, Li S, Ou J, Xu M, Li J, Zhu B, Cao X, Ma H, Li C, Xu J, Olkkonen VM, Staels B, Yan D. ORP4L Facilitates Macrophage Survival via G-Protein-Coupled Signaling: ORP4L-/- Mice Display a Reduction of Atherosclerosis. Circ Res 2016; 119:1296-1312. [PMID: 27729467 DOI: 10.1161/circresaha.116.309603] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Revised: 10/02/2016] [Accepted: 10/11/2016] [Indexed: 02/05/2023]
Abstract
RATIONALE Macrophage survival within the arterial wall is a central factor contributing to atherogenesis. Oxysterols, major components of oxidized low-density lipoprotein, exert cytotoxic effects on macrophages. OBJECTIVE To determine whether oxysterol-binding protein-related protein 4 L (ORP4L), an oxysterol-binding protein, affects macrophage survival and the pathogenesis of atherosclerosis. METHODS AND RESULTS By hiring cell biological approaches and ORP4L-/- mice, we show that ORP4L coexpresses with and forms a complex with Gαq/11 and phospholipase C (PLC)-β3 in macrophages. ORP4L facilitates G-protein-coupled ligand-induced PLCβ3 activation, IP3 production, and Ca2+ release from the endoplasmic reticulum. Through this mechanism, ORP4L sustains antiapoptotic Bcl-XL expression through Ca2+-mediated c-AMP responsive element binding protein transcriptional regulation and thus protects macrophages from apoptosis. Excessive stimulation with the oxysterol 25-hydroxycholesterol disassembles the ORP4L/Gαq/11/PLCβ3 complexes, resulting in reduced PLCβ3 activity, IP3 production, and Ca2+ release, as well as decreased Bcl-XL expression and increased apoptosis. Overexpression of ORP4L counteracts these oxysterol-induced defects. Mice lacking ORP4L exhibit increased apoptosis of macrophages in atherosclerotic lesions and a reduced lesion size. CONCLUSIONS ORP4L is crucial for macrophage survival. It counteracts the cytotoxicity of oxysterols/oxidized low-density lipoprotein to protect macrophage from apoptosis, thus playing an important role in the development of atherosclerosis.
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Affiliation(s)
- Wenbin Zhong
- From the Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Department of Biotechnology, College of Life Science and Technology, Jinan University, Guangzhou, China (W.Z., G.P., L.W., J.L., B.Z., X.C., H.M., C.L., D.Y.); Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland (S.L., V.M.O.); Division of Cardiac Surgery, the First Affiliated Hospital (J.O.) and Research Center for Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China (M.X., J.X.); and U1011 Inserm, EGID, Université Lille, CHU Lille, Institut Pasteur de Lille, France (B.S.)
| | - Guoping Pan
- From the Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Department of Biotechnology, College of Life Science and Technology, Jinan University, Guangzhou, China (W.Z., G.P., L.W., J.L., B.Z., X.C., H.M., C.L., D.Y.); Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland (S.L., V.M.O.); Division of Cardiac Surgery, the First Affiliated Hospital (J.O.) and Research Center for Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China (M.X., J.X.); and U1011 Inserm, EGID, Université Lille, CHU Lille, Institut Pasteur de Lille, France (B.S.)
| | - Lin Wang
- From the Key Laboratory of Functional Protein Research of Guangdong Higher Education Institutes, Department of Biotechnology, College of Life Science and Technology, Jinan University, Guangzhou, China (W.Z., G.P., L.W., J.L., B.Z., X.C., H.M., C.L., D.Y.); Minerva Foundation Institute for Medical Research, Biomedicum 2U, Helsinki, Finland (S.L., V.M.O.); Division of Cardiac Surgery, the First Affiliated Hospital (J.O.) and Research Center for Drug Discovery, School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China (M.X., J.X.); and U1011 Inserm, EGID, Université Lille, CHU Lille, Institut Pasteur de Lille, France (B.S.)
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Park SH, Paek JH, Shin D, Lee JY, Lim SS, Kang YH. Purple perilla extracts with α-asarone enhance cholesterol efflux from oxidized LDL-exposed macrophages. Int J Mol Med 2015; 35:957-65. [PMID: 25673178 PMCID: PMC4356441 DOI: 10.3892/ijmm.2015.2101] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 02/02/2015] [Indexed: 12/12/2022] Open
Abstract
The cellular accumulation of cholesterol is critical in the development and progression of atherosclerosis. ATP-binding cassette (ABC) transporters play an essential role in mediating the efflux of excess cholesterol. In the current study, we investigated whether purple Perilla frutescens extracts (PPE) at a non-toxic concentration of 1-10 µg/ml stimulate the induction of the ABC transporters, ABCA1 and ABCG1, and cholesterol efflux from lipid-laden J774A.1 murine macrophages exposed to 50 ng/ml oxidized low-density lipoprotein (LDL). Purple perilla, an annual herb in the mint family and its constituents, have been reported to exhibit antioxidant and cytostatic activity, as well as to exert anti-allergic effects. Our results revealed that treatment with oxidized LDL for 24 h led to the accumulation of lipid droplets in the macrophages. PPE suppressed the oxidized LDL-induced foam cell formation by blocking the induction of scavenger receptor B1. However, PPE promoted the induction of the ABC transporters, ABCA1 and ABCG1, and subsequently accelerated cholesterol efflux from the lipid-loaded macrophages. The liver X receptor (LXR) agonist, TO-091317, and the peroxisome proliferator-activated receptor (PPAR) agonist, pioglitazone, increased ABCA1 expression and treatment with 10 µg/ml PPE further enhanced this effect. PPE did not induce LXRα and PPARγ expression per se, but enhanced their expression in the macrophages exposed to oxidized LDL. α-asarone was isolated from PPE and characterized as a major component enhancing the induction of ABCA1 and ABCG1 in macrophages exposed to oxidized LDL. α-asarone, but not β-asarone was effective in attenuating foam cell formation and enhancing cholesterol efflux, revealing an isomeric difference in their activity. The results from the present study demonstrate that PPE promotes cholesterol efflux from macrophages by activating the interaction of PPARγ-LXRα-ABC transporters.
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Affiliation(s)
- Sin-Hye Park
- Department of Food Science and Nutrition, Hallym University, Chuncheon, Kangwon-do 200-702, Republic of Korea
| | - Ji Hun Paek
- Department of Food Science and Nutrition, Hallym University, Chuncheon, Kangwon-do 200-702, Republic of Korea
| | - Daekeun Shin
- Department of Food Science and Nutrition, Hallym University, Chuncheon, Kangwon-do 200-702, Republic of Korea
| | - Jae-Yong Lee
- Department of Biochemistry, School of Medicine, Hallym University, Chuncheon, Kangwon-do 200-702, Republic of Korea
| | - Soon Sung Lim
- Department of Food Science and Nutrition, Hallym University, Chuncheon, Kangwon-do 200-702, Republic of Korea
| | - Young-Hee Kang
- Department of Food Science and Nutrition, Hallym University, Chuncheon, Kangwon-do 200-702, Republic of Korea
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8
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Davis W. The ATP-binding cassette transporter-2 (ABCA2) regulates esterification of plasma membrane cholesterol by modulation of sphingolipid metabolism. Biochim Biophys Acta Mol Cell Biol Lipids 2013; 1841:168-79. [PMID: 24201375 DOI: 10.1016/j.bbalip.2013.10.019] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 10/09/2013] [Accepted: 10/29/2013] [Indexed: 10/26/2022]
Abstract
The ATP-binding cassette transporters are a large family (~48 genes divided into seven families A-G) of proteins that utilize the energy of ATP-hydrolysis to pump substrates across lipid bilayers against a concentration gradient. The ABC "A" subfamily is comprised of 13 members and transport sterols, phospholipids and bile acids. ABCA2 is the most abundant ABC transporter in human and rodent brain with highest expression in oligodendrocytes, although it is also expressed in neurons. Several groups have studied a possible connection between ABCA2 and Alzheimer's disease as well as early atherosclerosis. ABCA2 expression levels have been associated with changes in cholesterol and sphingolipid metabolism. In this paper, we hypothesized that ABCA2 expression level may regulate esterification of plasma membrane-derived cholesterol by modulation of sphingolipid metabolism. ABCA2 overexpression in N2a neuroblastoma cells was associated with an altered bilayer distribution of the sphingolipid ceramide that inhibited acylCoA:cholesterol acyltransferase (ACAT) activity and cholesterol esterification. In contrast, depletion of endogenous ABCA2 in the rat schwannoma cell line D6P2T increased esterification of plasma membrane cholesterol following treatment with exogenous bacterial sphingomyelinase. These findings suggest that control of ABCA2 expression level may be a key locus of regulation for esterification of plasma membrane-derived cholesterol through modulation of sphingolipid metabolism.
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Affiliation(s)
- Warren Davis
- Department of Pharmacology, Medical University of South Carolina, Charleston, SC 29403, USA.
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