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Iyer MR, Bhattacharjee P, Kundu B, Rutland N, Wood CM. One-Pot Synthesis of Thio-Augmented Sulfonylureas via a Modified Bunte's Reaction. ACS OMEGA 2022; 7:31612-31620. [PMID: 36092569 PMCID: PMC9453971 DOI: 10.1021/acsomega.2c04816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 08/10/2022] [Indexed: 06/15/2023]
Abstract
We report the development of a one-pot Bunte's reaction-enabled expeditious platform under aqueous conditions for the scalable conversion of sulfonylureas to synthetically versatile thio-sulfonylureas. The reaction was further propagated in the same pot to yield diverse chiral and achiral isothiosulfonyl analogs. The protocol enabled the synthesis of various drug-like molecules and was applied to an enantiomeric synthesis of a cannabinoid receptor antagonist SLV326.
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Ahmadi A, Panahi Y, Johnston TP, Sahebkar A. Antidiabetic drugs and oxidized low-density lipoprotein: A review of anti-atherosclerotic mechanisms. Pharmacol Res 2021; 172:105819. [PMID: 34400317 DOI: 10.1016/j.phrs.2021.105819] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/12/2021] [Accepted: 08/12/2021] [Indexed: 02/07/2023]
Abstract
Cardiovascular disease is one of the leading causes of mortality globally. Atherosclerosis is an important step towards different types of cardiovascular disease. The role of oxidized low-density lipoprotein (oxLDL) in the initiation and progression of atherosclerosis has been thoroughly investigated in recent years. Moreover, clinical trials have established that diabetic patients are at a greater risk of developing atherosclerotic plaques. Hence, we aimed to review the clinical and experimental impacts of various classes of antidiabetic drugs on the circulating levels of oxLDL. Metformin, pioglitazone, and dipeptidyl peptidase-4 inhibitors were clinically associated with a suppressive effect on oxLDL in patients with impaired glucose tolerance. However, there is an insufficient number of studies that have clinically evaluated the relationship between oxLDL and newer agents such as agonists of glucagon-like peptide 1 receptor or inhibitors of sodium-glucose transport protein 2. Next, we attempted to explore the multitude of mechanisms that antidiabetic agents exert to counter the undesirable effects of oxLDL in macrophages, endothelial cells, and vascular smooth muscle cells. In general, antidiabetic drugs decrease the uptake of oxLDL by vascular cells and reduce subsequent inflammatory signaling, which prevents macrophage adhesion and infiltration. Moreover, these agents suppress the oxLDL-induced transformation of macrophages into foam cells by either inhibiting oxLDL entrance, or by facilitating its efflux. Thus, the anti-inflammatory, anti-oxidant, and anti-apoptotic properties of antidiabetic agents abrogate changes induced by oxLDL, which can be extremely beneficial in controlling atherosclerosis in diabetic patients.
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Affiliation(s)
- Ali Ahmadi
- Pharmacotherapy Department, Faculty of Pharmacy, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Yunes Panahi
- Pharmacotherapy Department, Faculty of Pharmacy, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | - Thomas P Johnston
- Division of Pharmacology and Pharmaceutical Sciences, School of Pharmacy, University of Missouri-Kansas City, Kansas City, Missouri, USA
| | - Amirhossein Sahebkar
- Biotechnology Research Center, Pharmaceutical Technology Institute, Mashhad University of Medical Sciences, Mashhad, Iran; Applied Biomedical Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; School of Medicine, The University of Western Asutralia, Perth, Australia; School of Pharmacy, Mashhad University of Medical Sciences, Mashhad 9177948567, Iran.
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3
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Rodriguez-Carlos A, Valdez-Miramontes C, Marin-Luevano P, González-Curiel I, Enciso-Moreno JA, Rivas-Santiago B. Metformin promotes Mycobacterium tuberculosis killing and increases the production of human β-defensins in lung epithelial cells and macrophages. Microbes Infect 2020; 22:111-118. [DOI: 10.1016/j.micinf.2019.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 09/17/2019] [Accepted: 10/28/2019] [Indexed: 02/07/2023]
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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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Choi JH, Rho MC, Lee SW, Choi JN, Kim K, Song GY, Kim YK. Bavachin and isobavachalcone, acyl-coenzyme A: Cholesterol acyltransferase inhibitors from Psoralea corylifolia. Arch Pharm Res 2008; 31:1419-23. [DOI: 10.1007/s12272-001-2126-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2008] [Revised: 11/05/2008] [Accepted: 11/06/2008] [Indexed: 11/28/2022]
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6
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Choi JH, Rho MC, Lee SW, Kwon OE, Park HR, Kang JY, Lee SH, Lee HS, Bae KH, Kim YK. Glabrol, an acyl-coenzyme A: cholesterol acyltransferase inhibitor from licorice roots. JOURNAL OF ETHNOPHARMACOLOGY 2007; 110:563-6. [PMID: 17123760 DOI: 10.1016/j.jep.2006.10.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2006] [Revised: 09/27/2006] [Accepted: 10/13/2006] [Indexed: 05/12/2023]
Abstract
Acyl-coenzyme A: cholesterol acyltransferase (ACAT) esterifies free cholesterol in the liver and the intestine. It has relations with production of lipoproteins and accumulation of cholesteryl esters of the atheroma. Therefore, ACAT inhibitors may act as antihypercholesterolemic and antiatherosclerotic agents. One isoprenyl flavonoid was isolated from ethanol extract of licorice roots. On the basis of spectral evidences, the compound was identified as glabrol (1). Compound 1 inhibited rat liver microsomal ACAT activity with an IC(50) value of 24.6 microM and decreased cholesteryl ester formation with an IC(50) value of 26.0 microM in HepG2 cells. In addition, 1 showed a non-competitive type of inhibition against ACAT.
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Affiliation(s)
- Jung Ho Choi
- Natural Medicine Research Center, Korea Research Institute of Bioscience and Biotechnology, 52 Eoun-dong, Yusong-gu, Daejeon 305-333, Republic of Korea
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Leon C, Hill JS, Wasan KM. Potential role of acyl-coenzyme A:cholesterol transferase (ACAT) Inhibitors as hypolipidemic and antiatherosclerosis drugs. Pharm Res 2005; 22:1578-88. [PMID: 16180116 DOI: 10.1007/s11095-005-6306-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 06/03/2005] [Indexed: 11/29/2022]
Abstract
Acyl-coenzyme A:cholesterol transferase (ACAT) is an integral membrane protein localized in the endoplasmic reticulum. ACAT catalyzes the formation of cholesteryl esters from cholesterol and fatty acyl coenzyme A. The cholesteryl esters are stored as cytoplasmic lipid droplets inside the cell. This process is very important to the organism as high cholesterol levels have been associated with cardiovascular disease. In mammals, two ACAT genes have been identified, ACAT1 and ACAT2. ACAT1 is ubiquitous and is responsible for cholesteryl ester formation in brain, adrenal glands, macrophages, and kidneys. ACAT2 is expressed in the liver and intestine. The inhibition of ACAT activity has been associated with decreased plasma cholesterol levels by suppressing cholesterol absorption and by diminishing the assembly and secretion of apolipoprotein B-containing lipoproteins such as very low density lipoprotein (VLDL). ACAT inhibition also prevents the conversion of macrophages into foam cells in the arterial walls, a critical event in the development of atherosclerosis. This review paper will focus on the role of ACAT in cholesterol metabolism, in particular as a target to develop novel therapeutic agents to control hypercholesterolemia, atherosclerosis, and Alzheimer's disease.
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Affiliation(s)
- Carlos Leon
- Division of Pharmaceutics and Biopharmaceutics, Faculty of Pharmaceutical Sciences, The University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
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Nishikawa Y, Quittnat F, Stedman TT, Voelker DR, Choi JY, Zahn M, Yang M, Pypaert M, Joiner KA, Coppens I. Host cell lipids control cholesteryl ester synthesis and storage in intracellular Toxoplasma. Cell Microbiol 2005; 7:849-67. [PMID: 15888087 DOI: 10.1111/j.1462-5822.2005.00518.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The intracellular protozoan Toxoplasma gondii lacks a de novo mechanism for cholesterol synthesis and therefore must scavenge this essential lipid from the host environment. In this study, we demonstrated that T. gondii diverts cholesterol from low-density lipoproteins for cholesteryl ester synthesis and storage in lipid bodies. We identified and characterized two isoforms of acyl-CoA:cholesterol acyltransferase (ACAT)-related enzymes, designated TgACAT1alpha and TgACAT1beta in T. gondii. Both proteins are coexpressed in the parasite, localized to the endoplasmic reticulum and participate in cholesteryl ester synthesis. In contrast to mammalian ACAT, TgACAT1alpha and TgACAT1beta preferentially incorporate palmitate into cholesteryl esters and present a broad sterol substrate affinity. Mammalian ACAT-deficient cells transfected with either TgACAT1alpha or TgACAT1beta are restored in their capability of cholesterol esterification. TgACAT1alpha produces steryl esters and forms lipid bodies after transformation in a Saccharomyces cerevisiae mutant strain lacking neutral lipids. In addition to their role as ACAT substrates, host fatty acids and low-density lipoproteins directly serve as Toxoplasma ACAT activators by stimulating cholesteryl ester synthesis and lipid droplet biogenesis. Free fatty acids significantly increase TgACAT1alpha mRNA levels. Selected cholesterol esterification inhibitors impair parasite growth by rapid disruption of plasma membrane. Altogether, these studies indicate that host lipids govern neutral lipid synthesis in Toxoplasma and that interference with mechanisms of host lipid storage is detrimental to parasite survival in mammalian cells.
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Affiliation(s)
- Yoshifumi Nishikawa
- Department of Internal Medicine, Yale University School of Medicine, New Haven, CT 06520, USA
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Rho MC, Lee HS, Lee SW, Chang JS, Kwon OE, Chung MY, Kim YK. Polyacetylenic compounds, ACAT inhibitors from the roots of Panax ginseng. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2005; 53:919-22. [PMID: 15712998 DOI: 10.1021/jf040370x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Acyl-CoA: cholesterol acyltransferase (ACAT), which plays a role in the absorption, storage, and production of cholesterol, has been explored as a potential target for pharmacological intervention of hyperlipidemia and atherosclerotic disease. In our search for ACAT inhibitors from natural sources, the petroleum ether extract of Panax ginseng showed moderate inhibition of ACAT enzyme from rat liver microsomes. Bioactivity-guided fractionations led to the isolation of one new polyacetylenic compound, (9R,10S)-epoxy-16-heptadecene-4, 6-diyne-3-one (1), in addition to the previously reported polyacetylenic compounds 2 and 3. Their chemical structures were elucidated on the basis of spectroscopic evidence (UV, IR, NMR, and MS). The compounds 1, 2, and 3 showed significant ACAT inhibition with IC(50) values of 35, 47, and 21 microM, respectively.
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Affiliation(s)
- Mun-Chual Rho
- Laboratory of Lipid Metabolism, Korea Research Institute of Bioscience and Biotechnology, 52 Eoundong, Yusong-gu, Taejon 305-333, Korea
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Abstract
Several drugs or pharmacologically active molecules such as statins, calcium antagonists, and PPAR agonists have been shown to affect macrophage functions that contribute to atherosclerosis and modulate plaque stability. For example, the modulation of matrix metalloproteinase secretion and cholesterol metabolism in macrophages may help to prevent cardiovascular disease independently of the correction of risk factors.
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Affiliation(s)
- S Bellosta
- Department of Pharmacological Sciences, University of Milan, Italy.
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Vielemeyer O, McIntosh MT, Joiner KA, Coppens I. Neutral lipid synthesis and storage in the intraerythrocytic stages of Plasmodium falciparum. Mol Biochem Parasitol 2004; 135:197-209. [PMID: 15110461 DOI: 10.1016/j.molbiopara.2003.08.017] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2003] [Revised: 06/23/2003] [Accepted: 08/18/2003] [Indexed: 11/20/2022]
Abstract
In eukaryotic cells the neutral lipids, steryl esters and triacylglycerol, are synthesized by membrane-bound O-acyltransferases and stored in cytosolic lipid bodies. We show here that the intraerythrocytic stages of Plasmodium falciparum produce triacylglycerol using oleate and diacylglycerol as substrates. Parasite membrane preparations reveal a synthesis rate of 4.5 +/- 0.8 pmol x min(-1)mg(-1) of protein with maximal production occurring in the mid- and late-trophozoite stages in both, membrane preparations and live parasites. In contrast to other eukaryotic cells, no discernable amounts of steryl esters are produced, and the parasite is insensitive to cholesterol esterification inhibitors. Synthesized neutral lipids are stored as lipid bodies in the parasite cytosol in a stage specific manner. Their biogenesis is not modified upon incubation with excess fatty acids or lipoproteins or after lipoprotein depletion of the culture medium. We investigated on the enzymes involved in neutral lipid synthesis and found that only one gene with significant homology to known members of the membrane-bound O-acyltransferase family is present in the P. falciparum genome. It encodes a microsomal transmembrane protein with a predicted size of 78.1 kDa, which we named PfDGAT because of its close identity with various known acyl-CoA:diacylglycerol acyltransferases. PfDGAT is expressed in a stage specific manner as documented by Western blotting and immunoprecipitation assays using antibodies against Toxoplasma DGAT, suggesting that PfDGAT is the most likely candidate for plasmodial triacylglycerol synthesis.
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Affiliation(s)
- Ole Vielemeyer
- Department of Internal Medicine, Yale University School of Medicine, 333 Cedar Street, PO Box 20822, New Haven, CT 06520-8022, USA
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12
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Hori M, Miyazaki A, Tamagawa H, Satoh M, Furukawa K, Hakamata H, Sasaki Y, Horiuchi S. Up-regulation of acyl-coenzyme A:cholesterol acyltransferase-1 by transforming growth factor-β1 during differentiation of human monocytes into macrophages. Biochem Biophys Res Commun 2004; 320:501-5. [PMID: 15219857 DOI: 10.1016/j.bbrc.2004.05.190] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2004] [Indexed: 11/25/2022]
Abstract
Expression of acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) increases during differentiation of human monocytes into macrophages. To further elucidate the mechanism for ACAT-1 regulation in macrophages, we examined the effects of five cytokines including transforming growth factor-beta1 (TGF- beta1) on ACAT-1 expression in cultured human monocyte-macrophages. Immunoblot analyses showed that TGF-beta1 increased ACAT-1 protein expression by two- to threefold when added during differentiation of human monocytes into macrophages. ACAT activity increased in parallel by 1.8-fold. Northern blot analyses revealed that among the three ACAT-1 mRNA transcripts detected (2.8-, 3.6-, and 4.3-kb), the 2.8- and 3.6-kb transcripts were selectively increased by TGF-beta1. When TGF-beta1 was added after differentiation, ACAT-1 expression was not altered. Since TGF-beta1 is expressed in human atherosclerotic lesions, the current results suggest that ACAT-1 expression in monocytes infiltrating from the circulation to vascular walls may be enhanced by pre-existing TGF-beta1.
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Affiliation(s)
- Masaharu Hori
- Department of Medical Biochemistry, Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto 860-8556, Japan
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Furukawa K, Hori M, Ouchi N, Kihara S, Funahashi T, Matsuzawa Y, Miyazaki A, Nakayama H, Horiuchi S. Adiponectin down-regulates acyl-coenzyme A:cholesterol acyltransferase-1 in cultured human monocyte-derived macrophages. Biochem Biophys Res Commun 2004; 317:831-6. [PMID: 15081415 DOI: 10.1016/j.bbrc.2004.03.123] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2004] [Indexed: 11/18/2022]
Abstract
Acyl-coenzyme A:cholesterol acyltransferase-1 (ACAT-1) catalyzes the formation of cholesteryl esters (CE) and plays a significant role in formation of macrophage-derived foam cells in atherosclerotic lesions. Adiponectin was reported to play an anti-atherogenic role by inhibiting class A scavenger receptor (SR-A) expression in human macrophages. To further clarify its additional property, we examined its effect on ACAT-1 expression using human macrophages. Immunoblot analyses revealed a significant reduction of ACAT-1 protein by a low concentration (1 microg/ml) of adiponectin. The ACAT activity was also decreased in parallel by adiponectin. Northern blot analyses revealed that all four ACAT-1 mRNA transcripts (2.8, 3.6, 4.3, and 7.0 kb) were decreased almost equally by adiponectin. Furthermore, acetyl-LDL-induced CE-accumulation in these macrophages was reduced significantly by this adipocytokine. These results demonstrate the inhibitory effect of adiponectin on ACAT-1 expression, suggesting that adiponectin may play an anti-atherogenic role by down-regulating the expression of ACAT-1 as well as SR-A in human macrophages.
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Affiliation(s)
- Kohichiro Furukawa
- Department of Medical Biochemistry, Graduate School of Medical and Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
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Llaverías G, Jové M, Vázquez-Carrera M, Sánchez RM, Díaz C, Hernández G, Laguna JC, Alegret M. Avasimibe and atorvastatin synergistically reduce cholesteryl ester content in THP-1 macrophages. Eur J Pharmacol 2002; 451:11-7. [PMID: 12223223 DOI: 10.1016/s0014-2999(02)02152-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Evidence suggests that the inhibition of both acyl-CoA:cholesterol acyltransferase and hydroxymethyl glutaryl-CoA reductase causes a synergistic direct antiatherosclerotic effect on the vessel wall. To investigate this synergism in a single cell type and to avoid the confounding effect of plasma cholesterol lowering by these drugs, we have used an in vitro model of human macrophages (phorbol ester-treated THP-1 cells). In macrophages incubated simultaneously with acetyl low-density lipoproteins, the novel acyl-CoA:cholesterol acyltransferase inhibitor avasimibe (0.01-0.5 microM) caused a concentration-dependent reduction in cell cholesteryl ester content that was not accompanied by an increase in intracellular free cholesterol. A 5 microM concentration of atorvastatin enhanced by approximately twofold the ability of 0.5 microM avasimibe to reduce the mass of esterified cholesterol, and this was reversed by co-incubation with 200 microM mevalonate or 10 microM geranyl-geraniol. Based on these data, we propose that the synergism between acyl-CoA:cholesterol acyltransferase and hydroxymethyl glutaryl-CoA reductase inhibitors found in several in vivo studies may be explained by a direct additive effect of both agents reducing the lipid content of the macrophages present in the lesion area.
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Affiliation(s)
- Gemma Llaverías
- Unitat de Farmacologia, Departament de Farmacologia i Química Terapèutica, Facultat de Farmàcia, Universitat de Barcelona, Diagonal 643, 08028 Barcelona, Spain
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Abstract
Acyl-coenzyme A:cholesterol acyltransferase (ACAT) is an intracellular enzyme that produces cholesteryl esters in various tissues. In mammals, two ACAT genes (ACAT1 and ACAT2) have been identified. Together, these two enzymes are involved in storing cholesteryl esters as lipid droplets, in macrophage foam-cell formation, in absorbing dietary cholesterol, and in supplying cholesteryl esters as part of the core lipid for lipoprotein synthesis and assembly. The key difference in tissue distribution of ACAT1 and ACAT2 between humans, mice and monkeys is that, in adult human liver (including hepatocytes and bile duct cells), the major enzyme is ACAT1, rather than ACAT2. There is compelling evidence implicating a role for ACAT1 in macrophage foam-cell formation, and for ACAT2 in intestinal cholesterol absorption. However, further studies at the biochemical and cell biological levels are needed in order to clarify the functional roles of ACAT1 and ACAT2 in the VLDL or chylomicron synthesis/assembly process.
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Affiliation(s)
- T Y Chang
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
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