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Chen W, Liu Y, Li L, Liang B, Wang S, Xu X, Xing D, Wu X. The potential role and mechanism of circRNAs in foam cell formation. Noncoding RNA Res 2023; 8:315-325. [PMID: 37032721 PMCID: PMC10074414 DOI: 10.1016/j.ncrna.2023.03.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 03/02/2023] [Accepted: 03/18/2023] [Indexed: 03/29/2023] Open
Abstract
Atherosclerosis is a significant risk factor for coronary heart disease (CHD) and myocardial infarction (MI). Atherosclerosis develops during foam cell generation, which is caused by an imbalance in cholesterol uptake, esterification, and efflux. LOX-1, SR-A1, and CD36 all increased cholesterol uptake. ACAT1 and ACAT2 promote free cholesterol (FC) esterification to cholesteryl esters (CE). The hydrolysis of CE to FC was aided by nCEH. FC efflux was promoted by ABCA1, ABCG1, ADAM10, and apoA-I. SR-BI promotes not only cholesterol uptake but also FC efflux. Circular RNAs (circRNAs), which are single-stranded RNAs with a closed covalent circular structure, have emerged as promising biomarkers and therapeutic targets for atherosclerosis due to their highly tissue, cell, and disease state-specific expression profiles. Numerous studies have shown that circRNAs regulate foam cell formation, acting as miRNA sponges to influence atherosclerosis development by regulating the expression of SR-A1, CD36, ACAT2, ABCA1, ABCG1, ADAM10, apoA-I, SR-B1. Several circRNAs, including circ-Wdr91, circ 0004104, circRNA0044073, circRNA_0001805, circDENND1B, circRSF1, circ 0001445, and circRNA 102682, are potential biomarkers for atherosclerosis to better evaluate cardiovascular risk. It is difficult to deliver synthetic therapeutic circRNAs to the desired target tissues. Nanotechnology, such as GA-RM/GZ/PL, may be an important solution to this problem. In this review, we focus on the potential role and mechanism of circRNA/miRNA axis in foam cell formation in the hopes of discovering new targets for the diagnosis, prevention, and treatment of atherosclerosis.
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Affiliation(s)
- Wujun Chen
- Department of Orthopedics, Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong, 266071, China
| | - Yihui Liu
- Department of Radiotherapy, Affiliated Hospital of Weifang Medical University, Key Laboratory of Precision Radiation Therapy for Tumors in Weifang City, School of Medical Imaging, Weifang Medical University, Weifang, Shandong, 261031, China
| | - Ling Li
- Department of Pharmacy, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, Guangdong, 519000, China
| | - Bing Liang
- Department of Orthopedics, Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong, 266071, China
| | - Shuai Wang
- Department of Radiotherapy, Affiliated Hospital of Weifang Medical University, Key Laboratory of Precision Radiation Therapy for Tumors in Weifang City, School of Medical Imaging, Weifang Medical University, Weifang, Shandong, 261031, China
| | - Xiaodan Xu
- Department of Pathology, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui, 230022, China
- Corresponding author.
| | - Dongming Xing
- Department of Orthopedics, Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong, 266071, China
- School of Life Sciences, Tsinghua University, Beijing, 100084, China
- Corresponding author. Department of Orthopedics, Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong, 266071, China.
| | - Xiaolin Wu
- Department of Orthopedics, Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong, 266071, China
- Corresponding author. Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao University, Qingdao Cancer Institute, Qingdao, Shandong, 266071, China.
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Cheng Y, Yu H, Li K, Lv J, Zhuang J, Bai K, Wu Q, Yang X, Yang H, Lu Q. Hsa_circ_0003098 promotes bladder cancer progression via miR-377-5p/ACAT2 axis. Genomics 2023; 115:110692. [PMID: 37532090 DOI: 10.1016/j.ygeno.2023.110692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 07/20/2023] [Accepted: 07/30/2023] [Indexed: 08/04/2023]
Abstract
Accumulating evidence has proven that circRNAs play vital roles in tumor progression. Nevertheless, the mechanisms underlying circRNAs in bladder cancer (BCa) remain largely unknown. The purpose of this study was to identify the role and investigate the potential molecular mechanisms of hsa_circ_0003098 in BCa. We confirmed that hsa_circ_0003098 expression was significantly upregulated in BCa tissues, of which expression was remarkably associated with poor prognosis. Functionally, overexpression of hsa_circ_0003098 promoted BCa cell proliferation, migration, and invasion in vitro as well as tumor growth in vivo. Mechanistically, hsa_circ_0003098 promoted upregulation of ACAT2 expression and induced cholesteryl ester accumulation via acting as a sponge for miR-377-5p. Thus, hsa_circ_0003098 plays an oncogenic role in BCa and may serve as a potential biomarker and therapeutic target for BCa.
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Affiliation(s)
- Yidong Cheng
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China; Department of Urology, Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, Nanjing 21000, Jiangsu Province, PR China
| | - Hao Yu
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China
| | - Kai Li
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China
| | - Jiancheng Lv
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China
| | - Juntao Zhuang
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China
| | - Kexin Bai
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China
| | - Qikai Wu
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China
| | - Xiao Yang
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China.
| | - Haiwei Yang
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China.
| | - Qiang Lu
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 21000, Jiangsu Province, PR China.
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Bhattacharjee P, Rutland N, Iyer MR. Targeting Sterol O-Acyltransferase/Acyl-CoA:Cholesterol Acyltransferase (ACAT): A Perspective on Small-Molecule Inhibitors and Their Therapeutic Potential. J Med Chem 2022; 65:16062-16098. [PMID: 36473091 DOI: 10.1021/acs.jmedchem.2c01265] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Sterol O-acyltransferase (SOAT) is a membrane-bound enzyme that aids the esterification of cholesterol and fatty acids to cholesterol esters. SOAT has been studied extensively as a potential drug target, since its inhibition can serve as an alternative to statin therapy. Two SOAT isozymes that have discrete functions in the human body, namely, SOAT1 and SOAT2, have been characterized. Over three decades of research has focused on candidate SOAT1 inhibitors with unsatisfactory results in clinical trials. Recent research has focused on targeting SOAT2 selectively. In this perspective, we summarize the literature covering various SOAT inhibitory agents and discuss the design, structural requirements, and mode of action of SOAT inhibitors.
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Affiliation(s)
- Pinaki Bhattacharjee
- Section on Medicinal Chemistry, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland 20852, United States
| | - Nicholas Rutland
- Section on Medicinal Chemistry, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland 20852, United States
| | - Malliga R Iyer
- Section on Medicinal Chemistry, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, 5625 Fishers Lane, Rockville, Maryland 20852, United States
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Agarwal P, Gordon S, Martinez FO. Foam Cell Macrophages in Tuberculosis. Front Immunol 2022; 12:775326. [PMID: 34975863 PMCID: PMC8714672 DOI: 10.3389/fimmu.2021.775326] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 11/29/2021] [Indexed: 12/18/2022] Open
Abstract
Mycobacterium tuberculosis infects primarily macrophages in the lungs. Infected macrophages are surrounded by other immune cells in well organised structures called granulomata. As part of the response to TB, a type of macrophage loaded with lipid droplets arises which we call Foam cell macrophages. They are macrophages filled with lipid laden droplets, which are synthesised in response to increased uptake of extracellular lipids, metabolic changes and infection itself. They share the appearance with atherosclerosis foam cells, but their lipid contents and roles are different. In fact, lipid droplets are immune and metabolic organelles with emerging roles in Tuberculosis. Here we discuss lipid droplet and foam cell formation, evidence regarding the inflammatory and immune properties of foam cells in TB, and address gaps in our knowledge to guide further research.
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Affiliation(s)
- Pooja Agarwal
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Siamon Gordon
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan City, Taiwan.,Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom
| | - Fernando O Martinez
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
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Acidic extracellular pH promotes accumulation of free cholesterol in human monocyte-derived macrophages via inhibition of ACAT1 activity. Atherosclerosis 2020; 312:1-7. [PMID: 32942042 DOI: 10.1016/j.atherosclerosis.2020.08.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 08/14/2020] [Accepted: 08/27/2020] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS In focal areas of advanced human atherosclerotic lesions, the intimal fluid is acidic. An acidic medium impairs the ABCA1-mediated cholesterol efflux from macrophages, so tending to increase their content of free cholesterol, which is then available for esterification by the macrophage enzyme ACAT1. Here we investigated whether low extracellular pH would affect the activity of ACAT1. METHODS - Human monocyte-derived macrophages were first incubated with acetyl-LDL at neutral and acidic conditions (pH 7.5, 6.5, and 5.5) to generate foam cells, and then the foam cells were incubated with [3H]oleate-BSA complexes, and the formation of [3H]oleate-labeled cholesteryl esters was measured. ACAT1 activity was also measured in cell-free macrophage extracts. RESULTS - In acidic media, ACAT1-dependent cholesteryl [3H]oleate generation became compromised in the developing foam cells and their content of free cholesterol increased. In line with this finding, ACAT1 activity in the soluble cell-free fraction derived from macrophage foam cells peaked at pH 7, and gradually decreased under acidic pH with a rapid drop below pH 6.5. Incubation of macrophages under progressively more acidic conditions (until pH 5.5) lowered the cytosolic pH of macrophages (down to pH 6.0). Such intracellular acidification did not affect macrophage gene expression of ACAT1 or the neutral CEH. CONCLUSIONS Exposure of human macrophage foam cells to acidic conditions lowers their intracellular pH with simultaneous decrease in ACAT1 activity. This reduces cholesterol esterification and thus leads to accumulation of potentially toxic levels of free cholesterol, a contributing factor to macrophage foam cell death.
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Xu J, Zhou Y, Yang Y, Lv C, Liu X, Wang Y. Involvement of ABC-transporters and acyltransferase 1 in intracellular cholesterol-mediated autophagy in bovine alveolar macrophages in response to the Bacillus Calmette-Guerin (BCG) infection. BMC Immunol 2020; 21:26. [PMID: 32397995 PMCID: PMC7216371 DOI: 10.1186/s12865-020-00356-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 05/04/2020] [Indexed: 02/07/2023] Open
Abstract
Background Understanding pathogenic mechanisms is imperative for developing novel treatment to the tuberculosis, an important public health burden worldwide. Recent studies demonstrated that host cholesterol levels have implications in the establishment of Mycobacterium tuberculosis (M. tuberculosis, Mtb) infection in host cells, in which the intracellular cholesterol-mediated ATP-binding cassette transporters (ABC-transporters) and cholesterol acyltransferase1 (ACAT1) exhibited abilities to regulate macrophage autophagy induced by Mycobacterium bovis bacillus Calmette–Guérin (BCG). Results The results showed that a down-regulated expression of the ABC-transporters and ACAT1 in primary bovine alveolar macrophages (AMs) and murine RAW264.7 cells in response to a BCG infection. The inhibited expression of ABC-transporters and ACAT1 was associated with the reduction of intracellular free cholesterol, which in turn induced autophagy in macrophages upon to the Mycobacterial infection. These results strongly suggest an involvement of ABC-transporters and ACAT1 in intracellular cholesterol-mediated autophagy in AMs in response to BCG infection. Conclusion This study thus provides an insight into into a mechanism by which the cholesterol metabolism regulated the autophagy in macrophages in response to mycobacterial infections.
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Affiliation(s)
- Jinrui Xu
- Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western, Yinchuan, China.,College of Life Science, Ningxia University, Yinchuan, 750021, Ningxia, China
| | - Yanbing Zhou
- Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western, Yinchuan, China.,College of Life Science, Ningxia University, Yinchuan, 750021, Ningxia, China
| | - Yi Yang
- Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western, Yinchuan, China.,College of Life Science, Ningxia University, Yinchuan, 750021, Ningxia, China
| | - Cuiping Lv
- Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western, Yinchuan, China.,College of Life Science, Ningxia University, Yinchuan, 750021, Ningxia, China
| | - Xiaoming Liu
- Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western, Yinchuan, China. .,College of Life Science, Ningxia University, Yinchuan, 750021, Ningxia, China.
| | - Yujiong Wang
- Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western, Yinchuan, China. .,College of Life Science, Ningxia University, Yinchuan, 750021, Ningxia, China.
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Weng M, Zhang H, Hou W, Sun Z, Zhong J, Miao C. ACAT2 Promotes Cell Proliferation and Associates with Malignant Progression in Colorectal Cancer. Onco Targets Ther 2020; 13:3477-3488. [PMID: 32425549 PMCID: PMC7187938 DOI: 10.2147/ott.s238973] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Accepted: 04/05/2020] [Indexed: 12/24/2022] Open
Abstract
Background and Aims Colorectal cancer (CRC) is a major disease that threatens human health. It has been reported that the acyl-coenzyme A (CoA): cholesterol acyltransferase 2 (ACAT2) gene can promote the progression of hepatocellular carcinoma, but its function in CRC is still unclear. In this study, we aimed to elucidate the function of ACAT2 in CRC. Methods Western blot and qPCR were used to detect the relative level of ACAT2 in CRC tissue and adjacent non-cancerous tissues, and then the association between ACAT2 expression and the clinicopathological features and survival of CRC patients were assessed. The expression of ACAT2 in CT26 and DLD1 cells was down-regulated by siRNA, and the effects of ACAT2 knockdown on cell proliferation were examined. The inhibitory effects of ACAT2 knockdown were further confirmed by tumor growth assays in vivo. Results Our data showed that the expression of ACAT2 in CRC tissues was markedly higher than in adjacent non-cancerous tissues. The high expression of ACAT2 was significantly associated with tumor size, lymph node metastasis and clinical stage. The increased expression of ACAT2 was also significantly associated with worse 5-year overall survival of CRC patients. siRNA-mediated ACAT2 knockdown strongly inhibited CT26 and DLD1 cells proliferation and induced G0/G1 phase cell cycle arrest and apoptosis in these cells. Knockdown of ACAT2 expression suppressed the growth of CRC and inhibited the expression of Ki67 in vivo. Conclusion Our study demonstrated that ACAT2 played a positive role in regulating the proliferation of CRC and may be useful as a potential biomarker and therapeutic target for this disease.
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Affiliation(s)
- Meilin Weng
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, Shanghai 200032, People's Republic of China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, People's Republic of China
| | - Hao Zhang
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, Shanghai 200032, People's Republic of China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, People's Republic of China.,Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai 200032, People's Republic of China
| | - Wenting Hou
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, Shanghai 200032, People's Republic of China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, People's Republic of China
| | - Zhirong Sun
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, Shanghai 200032, People's Republic of China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, People's Republic of China
| | - Jing Zhong
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, Shanghai 200032, People's Republic of China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, People's Republic of China.,Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai 200032, People's Republic of China
| | - Changhong Miao
- Department of Anesthesiology, Fudan University Shanghai Cancer Center, Shanghai 200032, People's Republic of China.,Department of Oncology, Shanghai Medical College, Fudan University, Shanghai 200032, People's Republic of China.,Department of Anesthesiology, Zhongshan Hospital, Fudan University, Shanghai 200032, People's Republic of China
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Iqbal J, Jahangir Z, Al-Qarni AA. Microsomal Triglyceride Transfer Protein: From Lipid Metabolism to Metabolic Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1276:37-52. [DOI: 10.1007/978-981-15-6082-8_4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Wang D, Yang Y, Lei Y, Tzvetkov NT, Liu X, Yeung AWK, Xu S, Atanasov AG. Targeting Foam Cell Formation in Atherosclerosis: Therapeutic Potential of Natural Products. Pharmacol Rev 2019; 71:596-670. [PMID: 31554644 DOI: 10.1124/pr.118.017178] [Citation(s) in RCA: 104] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Foam cell formation and further accumulation in the subendothelial space of the vascular wall is a hallmark of atherosclerotic lesions. Targeting foam cell formation in the atherosclerotic lesions can be a promising approach to treat and prevent atherosclerosis. The formation of foam cells is determined by the balanced effects of three major interrelated biologic processes, including lipid uptake, cholesterol esterification, and cholesterol efflux. Natural products are a promising source for new lead structures. Multiple natural products and pharmaceutical agents can inhibit foam cell formation and thus exhibit antiatherosclerotic capacity by suppressing lipid uptake, cholesterol esterification, and/or promoting cholesterol ester hydrolysis and cholesterol efflux. This review summarizes recent findings on these three biologic processes and natural products with demonstrated potential to target such processes. Discussed also are potential future directions for studying the mechanisms of foam cell formation and the development of foam cell-targeted therapeutic strategies.
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Affiliation(s)
- Dongdong Wang
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China (D.W., X.L.); Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzębiec, Poland (D.W., Y.Y., Y.L., A.G.A.); Department of Pharmacognosy, University of Vienna, Vienna, Austria (A.G.A.); Institute of Clinical Chemistry, University Hospital Zurich, Schlieren, Switzerland (D.W.); Institute of Molecular Biology "Roumen Tsanev," Department of Biochemical Pharmacology and Drug Design, Bulgarian Academy of Sciences, Sofia, Bulgaria (N.T.T.); Pharmaceutical Institute, University of Bonn, Bonn, Germany (N.T.T.); Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York (S.X.); Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China (A.W.K.Y.); and Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria (A.G.A.)
| | - Yang Yang
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China (D.W., X.L.); Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzębiec, Poland (D.W., Y.Y., Y.L., A.G.A.); Department of Pharmacognosy, University of Vienna, Vienna, Austria (A.G.A.); Institute of Clinical Chemistry, University Hospital Zurich, Schlieren, Switzerland (D.W.); Institute of Molecular Biology "Roumen Tsanev," Department of Biochemical Pharmacology and Drug Design, Bulgarian Academy of Sciences, Sofia, Bulgaria (N.T.T.); Pharmaceutical Institute, University of Bonn, Bonn, Germany (N.T.T.); Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York (S.X.); Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China (A.W.K.Y.); and Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria (A.G.A.)
| | - Yingnan Lei
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China (D.W., X.L.); Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzębiec, Poland (D.W., Y.Y., Y.L., A.G.A.); Department of Pharmacognosy, University of Vienna, Vienna, Austria (A.G.A.); Institute of Clinical Chemistry, University Hospital Zurich, Schlieren, Switzerland (D.W.); Institute of Molecular Biology "Roumen Tsanev," Department of Biochemical Pharmacology and Drug Design, Bulgarian Academy of Sciences, Sofia, Bulgaria (N.T.T.); Pharmaceutical Institute, University of Bonn, Bonn, Germany (N.T.T.); Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York (S.X.); Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China (A.W.K.Y.); and Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria (A.G.A.)
| | - Nikolay T Tzvetkov
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China (D.W., X.L.); Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzębiec, Poland (D.W., Y.Y., Y.L., A.G.A.); Department of Pharmacognosy, University of Vienna, Vienna, Austria (A.G.A.); Institute of Clinical Chemistry, University Hospital Zurich, Schlieren, Switzerland (D.W.); Institute of Molecular Biology "Roumen Tsanev," Department of Biochemical Pharmacology and Drug Design, Bulgarian Academy of Sciences, Sofia, Bulgaria (N.T.T.); Pharmaceutical Institute, University of Bonn, Bonn, Germany (N.T.T.); Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York (S.X.); Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China (A.W.K.Y.); and Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria (A.G.A.)
| | - Xingde Liu
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China (D.W., X.L.); Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzębiec, Poland (D.W., Y.Y., Y.L., A.G.A.); Department of Pharmacognosy, University of Vienna, Vienna, Austria (A.G.A.); Institute of Clinical Chemistry, University Hospital Zurich, Schlieren, Switzerland (D.W.); Institute of Molecular Biology "Roumen Tsanev," Department of Biochemical Pharmacology and Drug Design, Bulgarian Academy of Sciences, Sofia, Bulgaria (N.T.T.); Pharmaceutical Institute, University of Bonn, Bonn, Germany (N.T.T.); Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York (S.X.); Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China (A.W.K.Y.); and Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria (A.G.A.)
| | - Andy Wai Kan Yeung
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China (D.W., X.L.); Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzębiec, Poland (D.W., Y.Y., Y.L., A.G.A.); Department of Pharmacognosy, University of Vienna, Vienna, Austria (A.G.A.); Institute of Clinical Chemistry, University Hospital Zurich, Schlieren, Switzerland (D.W.); Institute of Molecular Biology "Roumen Tsanev," Department of Biochemical Pharmacology and Drug Design, Bulgarian Academy of Sciences, Sofia, Bulgaria (N.T.T.); Pharmaceutical Institute, University of Bonn, Bonn, Germany (N.T.T.); Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York (S.X.); Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China (A.W.K.Y.); and Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria (A.G.A.)
| | - Suowen Xu
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China (D.W., X.L.); Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzębiec, Poland (D.W., Y.Y., Y.L., A.G.A.); Department of Pharmacognosy, University of Vienna, Vienna, Austria (A.G.A.); Institute of Clinical Chemistry, University Hospital Zurich, Schlieren, Switzerland (D.W.); Institute of Molecular Biology "Roumen Tsanev," Department of Biochemical Pharmacology and Drug Design, Bulgarian Academy of Sciences, Sofia, Bulgaria (N.T.T.); Pharmaceutical Institute, University of Bonn, Bonn, Germany (N.T.T.); Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York (S.X.); Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China (A.W.K.Y.); and Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria (A.G.A.)
| | - Atanas G Atanasov
- The Second Affiliated Hospital of Guizhou University of Traditional Chinese Medicine, Guiyang, China (D.W., X.L.); Department of Molecular Biology, Institute of Genetics and Animal Breeding of the Polish Academy of Sciences, Jastrzębiec, Poland (D.W., Y.Y., Y.L., A.G.A.); Department of Pharmacognosy, University of Vienna, Vienna, Austria (A.G.A.); Institute of Clinical Chemistry, University Hospital Zurich, Schlieren, Switzerland (D.W.); Institute of Molecular Biology "Roumen Tsanev," Department of Biochemical Pharmacology and Drug Design, Bulgarian Academy of Sciences, Sofia, Bulgaria (N.T.T.); Pharmaceutical Institute, University of Bonn, Bonn, Germany (N.T.T.); Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester, Rochester, New York (S.X.); Oral and Maxillofacial Radiology, Applied Oral Sciences and Community Dental Care, Faculty of Dentistry, The University of Hong Kong, Hong Kong, China (A.W.K.Y.); and Institute of Neurobiology, Bulgarian Academy of Sciences, Sofia, Bulgaria (A.G.A.)
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Munjal A, Khandia R. Atherosclerosis: orchestrating cells and biomolecules involved in its activation and inhibition. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2019; 120:85-122. [PMID: 32085889 DOI: 10.1016/bs.apcsb.2019.11.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The term atherosclerosis refers to the condition of deposition of lipids and other substances in and on the artery walls, called as plaque that restricts the normal blood flow. The plaque may be stable or unstable in nature. Unstable plaque can burst and trigger clot formation adding further adversities. The process of plaque formation involves various stages including fatty streak, intermediate or fibro-fatty lesion and advanced lesion. The cells participating in the formation of atherosclerotic plaque include endothelial cells, vascular smooth muscle cells (VSMC), monocytes, monocytes derived macrophages, macrophages and dendritic cells and regulatory T cells (TREG). The role of a variety of cytokines and chemokines have been studied which either help in progression of atherosclerotic plaque or vice versa. The cytokines involved in atherosclerotic plaque formation include IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-9, IL-10, IL-12, IL-13, IL-15, IL-17, IL-18, IL-20, IL-25, IL-27, IL-33, IL-37, TNF-α, TGF-β and IFN-γ; whereas amongst the chemokines (family of small cytokines) are CCL2, CCL3, CXCL4, CCL5, CXCL1, CX3CL1, CCL17, CXCL8, CXCL10, CCL20, CCL19 and CCL21 and macrophage migration-inhibitory factor. These are involved in the atherosclerosis advancements, whereas the chemokine CXCL12 is play atheroprotective roles. Apart this, contradictory functions have been documented for few other chemokines such as CXCL16. Since the cytokines and chemokines are amongst the key molecules involved in orchestrating the atherosclerosis advancements, targeting them might be an effective strategy to encumber the atherosclerotic progression. Blockage of cytokines and chemokines via the means of broad-spectrum inhibitors, neutralizing antibodies, usage of decoy receptors or RNA interference have been proved to be useful intervention against atherosclerosis.
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Affiliation(s)
- Ashok Munjal
- Department of Genetics, Barkatullah University, Bhopal, MP, India
| | - Rekha Khandia
- Department of Genetics, Barkatullah University, Bhopal, MP, India
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Melton EM, Li H, Benson J, Sohn P, Huang LH, Song BL, Li BL, Chang CCY, Chang TY. Myeloid Acat1/ Soat1 KO attenuates pro-inflammatory responses in macrophages and protects against atherosclerosis in a model of advanced lesions. J Biol Chem 2019; 294:15836-15849. [PMID: 31495784 DOI: 10.1074/jbc.ra119.010564] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 09/02/2019] [Indexed: 11/06/2022] Open
Abstract
Cholesterol esters are a key ingredient of foamy cells in atherosclerotic lesions; their formation is catalyzed by two enzymes: acyl-CoA:cholesterol acyltransferases (ACATs; also called sterol O-acyltransferases, or SOATs) ACAT1 and ACAT2. ACAT1 is present in all body cells and is the major isoenzyme in macrophages. Whether blocking ACAT1 benefits atherosclerosis has been under debate for more than a decade. Previously, our laboratory developed a myeloid-specific Acat1 knockout (KO) mouse (Acat1 -M/-M), devoid of ACAT1 only in macrophages, microglia, and neutrophils. In previous work using the ApoE KO (ApoE -/-) mouse model for early lesions, Acat1 -M/-M significantly reduced lesion macrophage content and suppressed atherosclerosis progression. In advanced lesions, cholesterol crystals become a prominent feature. Here we evaluated the effects of Acat1 -M/-M in the ApoE KO mouse model for more advanced lesions and found that mice lacking myeloid Acat1 had significantly reduced lesion cholesterol crystal contents. Acat1 -M/-M also significantly reduced lesion size and macrophage content without increasing apoptotic cell death. Cell culture studies showed that inhibiting ACAT1 in macrophages caused cells to produce less proinflammatory responses upon cholesterol loading by acetyl low-density lipoprotein. In advanced lesions, Acat1 -M/-M reduced but did not eliminate foamy cells. In advanced plaques isolated from ApoE -/- mice, immunostainings showed that both ACAT1 and ACAT2 are present. In cell culture, both enzymes are present in macrophages and smooth muscle cells and contribute to cholesterol ester biosynthesis. Overall, our results support the notion that targeting ACAT1 or targeting both ACAT1 and ACAT2 in macrophages is a novel strategy to treat advanced lesions.
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Affiliation(s)
- Elaina M Melton
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire 03755
| | - Haibo Li
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire 03755
| | | | - Paul Sohn
- Indiana University School of Medicine, Indianapolis, Indiana 46202
| | - Li-Hao Huang
- Department of Pathology and Immunology, Washington University, St. Louis, Missouri 63130
| | - Bao-Liang Song
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Bo-Liang Li
- Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China
| | - Catherine C Y Chang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire 03755
| | - Ta-Yuan Chang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine, Dartmouth College, Hanover, New Hampshire 03755
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12
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Huang LH, Melton EM, Li H, Sohn P, Jung D, Tsai CY, Ma T, Sano H, Ha H, Friedline RH, Kim JK, Usherwood E, Chang CCY, Chang TY. Myeloid-specific Acat1 ablation attenuates inflammatory responses in macrophages, improves insulin sensitivity, and suppresses diet-induced obesity. Am J Physiol Endocrinol Metab 2018; 315. [PMID: 29533741 PMCID: PMC6171008 DOI: 10.1152/ajpendo.00174.2017] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Macrophages are phagocytes that play important roles in health and diseases. Acyl-CoA:cholesterol acyltransferase 1 (ACAT1) converts cellular cholesterol to cholesteryl esters and is expressed in many cell types. Unlike global Acat1 knockout (KO), myeloid-specific Acat1 KO ( Acat1-) does not cause overt abnormalities in mice. Here, we performed analyses in age- and sex-matched Acat1-M/-M and wild-type mice on chow or Western diet and discovered that Acat1-M/-M mice exhibit resistance to Western diet-induced obesity. On both chow and Western diets, Acat1-M/-M mice display decreased adipocyte size and increased insulin sensitivity. When fed with Western diet, Acat1-M/-M mice contain fewer infiltrating macrophages in white adipose tissue (WAT), with significantly diminished inflammatory phenotype. Without Acat1, the Ly6Chi monocytes express reduced levels of integrin-β1, which plays a key role in the interaction between monocytes and the inflamed endothelium. Adoptive transfer experiment showed that the appearance of leukocytes from Acat1-M/-M mice to the inflamed WAT of wild-type mice is significantly diminished. Under Western diet, Acat1-M/-M causes suppression of multiple proinflammatory genes in WAT. Cell culture experiments show that in RAW 264.7 macrophages, inhibiting ACAT1 with a small-molecule ACAT1-specific inhibitor reduces inflammatory responses to lipopolysaccharide. We conclude that under Western diet, blocking ACAT1 in macrophages attenuates inflammation in WAT. Other results show that Acat1-M/-M does not compromise antiviral immune response. Our work reveals that blocking ACAT1 suppresses diet-induced obesity in part by slowing down monocyte infiltration to WAT as well as by reducing the inflammatory responses of adipose tissue macrophages.
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Affiliation(s)
- Li-Hao Huang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire
| | - Elaina M Melton
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire
| | - Haibo Li
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire
| | - Paul Sohn
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire
| | - DaeYoung Jung
- Program in Molecular Medicine, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Ching-Yi Tsai
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
| | - Tian Ma
- Department of Pharmacology and Toxicology, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire
| | - Hiroyuki Sano
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire
| | - HyeKyung Ha
- Program in Molecular Medicine, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Randall H Friedline
- Program in Molecular Medicine, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Jason K Kim
- Program in Molecular Medicine, University of Massachusetts Medical School , Worcester, Massachusetts
| | - Edward Usherwood
- Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire
| | - Catherine C Y Chang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire
| | - Ta-Yuan Chang
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth , Hanover, New Hampshire
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13
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Qi H, Ning L, Yu Z, Dou G, Li L. Proteomic Identification of eEF1A1 as a Molecular Target of Curcumol for Suppressing Metastasis of MDA-MB-231 Cells. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2017; 65:3074-3082. [PMID: 28345336 DOI: 10.1021/acs.jafc.7b00573] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Curcumol, a major volatile component in Rhizoma Curcumae, exhibits a potent antimetastatic effect on breast cancer cells. However, its molecular mechanism remains poorly understood. In this study, we employed two-dimensional gel electrophoresis-based proteomics to investigate the cellular targets of curcumol in MDA-MB-231 cells and identified 10 differentially expressed proteins. Moreover, Gene Ontology analysis revealed that these proteins are mainly involved in nine types of cellular components, seven different biological processes, and nine kinds of molecular functions, and 35 pathways (p < 0.05) were enriched by KEGG pathway analysis. Specially, eEF1A1, a well-characterized actin binding protein, draws our attention. Curcumol decreased eEF1A1 expression at both mRNA and protein levels. EEF1A1 expression was shown to be correlated with the invasiveness of cancer cells. Importantly, overexpression of eEF1A1 significantly reversed the inhibition of curcumol regarding the invasion and adhesion of MDA-MB-231 cells (p < 0.05). Together, our data suggest that eEF1A1 may be a potential molecular target underlying the antimetastatic effect of curcumol.
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Affiliation(s)
- Hongyi Qi
- College of Pharmaceutical Sciences, Southwest University , Chongqing 400716, P.R. China
| | - Ling Ning
- College of Pharmaceutical Sciences, Southwest University , Chongqing 400716, P.R. China
| | - Zanyang Yu
- College of Pharmaceutical Sciences, Southwest University , Chongqing 400716, P.R. China
| | - Guojun Dou
- College of Pharmaceutical Sciences, Southwest University , Chongqing 400716, P.R. China
| | - Li Li
- College of Pharmaceutical Sciences, Southwest University , Chongqing 400716, P.R. China
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14
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Guo D, Lu M, Hu X, Xu J, Hu G, Zhu M, Zhang X, Li Q, Chang CCY, Chang T, Song B, Xiong Y, Li B. Low-level expression of human ACAT2 gene in monocytic cells is regulated by the C/EBP transcription factors. Acta Biochim Biophys Sin (Shanghai) 2016; 48:980-989. [PMID: 27688151 PMCID: PMC5091289 DOI: 10.1093/abbs/gmw091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 08/18/2016] [Accepted: 07/15/2016] [Indexed: 01/15/2023] Open
Abstract
Acyl-coenzyme A:cholesterol acyltransferases (ACATs) are the exclusive intracellular enzymes that catalyze the formation of cholesteryl/steryl esters (CE/SE). In our previous work, we found that the high-level expression of human ACAT2 gene with the CpG hypomethylation of its whole promoter was synergistically regulated by two transcription factors Cdx2 and HNF1α in the intestine and fetal liver. Here, we first observed that the specific CpG-hypomethylated promoter was correlated with the low expression of human ACAT2 gene in monocytic cell line THP-1. Then, two CCAAT/enhancer binding protein (C/EBP) elements within the activation domain in the specific CpG-hypomethylation promoter region were identified, and the expression of ACAT2 in THP-1 cells was evidently decreased when the C/EBP transcription factors were knock-downed using RNAi technology. Furthermore, ChIP assay confirmed that C/EBPs directly bind to their elements for low-level expression of human ACAT2 gene in THP-1 cells. Significantly, the increased expressions of ACAT2 and C/EBPs were also found in macrophages differentiated from both ATRA-treated THP-1 cells and cultured human blood monocytes. These results demonstrate that the low-level expression of human ACAT2 gene with specific CpG-hypomethylated promoter is regulated by the C/EBP transcription factors in monocytic cells, and imply that the lowly expressed ACAT2 catalyzes the synthesis of certain CE/SE that are assembled into lipoproteins for the secretion.
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Affiliation(s)
- Dongqing Guo
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ming Lu
- Department of General Surgery, Huashan Hospital, Fudan University, Shanghai 200040, China
| | - Xihan Hu
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jiajia Xu
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Guangjing Hu
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ming Zhu
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiaowei Zhang
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Qin Li
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Catherine C Y Chang
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Tayuan Chang
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Baoliang Song
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- College of Life Sciences, The Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
| | - Ying Xiong
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Boliang Li
- Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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15
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Warrier M, Zhang J, Bura K, Kelley K, Wilson MD, Rudel LL, Brown JM. Sterol O-Acyltransferase 2-Driven Cholesterol Esterification Opposes Liver X Receptor-Stimulated Fecal Neutral Sterol Loss. Lipids 2016; 51:151-7. [PMID: 26729489 PMCID: PMC5221701 DOI: 10.1007/s11745-015-4116-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2015] [Accepted: 12/18/2015] [Indexed: 11/28/2022]
Abstract
Statin drugs have proven a successful and relatively safe therapy for the treatment of atherosclerotic cardiovascular disease (CVD). However, even with the substantial low-density lipoprotein (LDL) cholesterol lowering achieved with statin treatment, CVD remains the top cause of death in developed countries. Selective inhibitors of the cholesterol esterifying enzyme sterol-O acyltransferase 2 (SOAT2) hold great promise as effective CVD therapeutics. In mouse models, previous work has demonstrated that either antisense oligonucleotide (ASO) or small molecule inhibitors of SOAT2 can effectively reduce CVD progression, and even promote regression of established CVD. Although it is well known that SOAT2-driven cholesterol esterification can alter both the packaging and retention of atherogenic apoB-containing lipoproteins, here we set out to determine whether SOAT2-driven cholesterol esterification can also impact basal and liver X receptor (LXR)-stimulated fecal neutral sterol loss. These studies demonstrate that SOAT2 is a negative regulator of LXR-stimulated fecal neutral sterol loss in mice.
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Affiliation(s)
- Manya Warrier
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH, 44195, USA
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Jun Zhang
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Kanwardeep Bura
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Kathryn Kelley
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Martha D Wilson
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - Lawrence L Rudel
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA
| | - J Mark Brown
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, OH, 44195, USA.
- Department of Pathology, Wake Forest School of Medicine, Winston-Salem, NC, 27157, USA.
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16
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Abstract
Alzheimer's disease (AD) is the most common cause of dementia with no cure at present. Cholesterol metabolism is closely associated with AD at several stages. ACAT1 converts free cholesterol to cholesteryl esters, and plays important roles in cellular cholesterol homeostasis. Recent studies show that in a mouse model, blocking ACAT1 provides multiple beneficial effects on AD. Here we review the current evidence that implicates ACAT1 as a therapeutic target for AD. We also discuss the potential usage of various ACAT inhibitors currently available to treat AD.
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17
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Gunawardhana LP, Baines KJ, Mattes J, Murphy VE, Simpson JL, Gibson PG. Differential DNA methylation profiles of infants exposed to maternal asthma during pregnancy. Pediatr Pulmonol 2014; 49:852-62. [PMID: 24166889 DOI: 10.1002/ppul.22930] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 07/29/2013] [Accepted: 08/13/2013] [Indexed: 11/06/2022]
Abstract
BACKGROUND Asthma is a complex disease that involves both genetic factors and environmental exposures. Aberrant epigenetic modifications, such as DNA methylation, may be important in asthma development. Fetal exposure to maternal asthma during critical periods of in utero development may lead to epigenetic alterations that predispose infants to a greater risk of developing asthma themselves. We investigated alterations in the DNA methylation profile of peripheral blood from infants exposed to maternal asthma during pregnancy. METHODS Peripheral blood was collected from 12-month-old infants born to women with (n = 25) and without (n = 15) doctor diagnosed asthma during pregnancy. Genomic DNA was extracted, bisulfite converted, and hybridized to Infinium Methylation 27 arrays (Illumina), containing over27,000 CpGs from 14,495 genes. CpG loci in only autosomal genes were classified as differentially methylated at the 99% level (P < 0.01, |DiffScore| > 22 and delta beta >0.06). RESULTS There were 70 CpG loci, corresponding to 67 genes that were significantly differentially methylated. Twelve CpG loci (11 genes) showed greater than 10% comparative difference in DNA methylation, including hyper-methylated loci of FAM181A, MRI1, PIWIL1, CHFR, DEFA1, MRPL28, AURKA, and hypo-methylated loci of NALP1L5, MAP8KIP3, ACAT2, and PM20D1 in maternal asthma. Methylation of MAPK8IP3 was significantly negatively correlated with maternal blood eosinophils (r = -0.38; P = 0.022), maternal eNO (r = -0.44; P = 0.005), and maternal serum total IgE (r = -0.39, P = 0.015). Methylation of AURKA negatively correlated with maternal hemoglobin (r = -0.43; P = 0.008), infants height (r = -0.51; P < 0.001) and weight (r = -0.36; P = 0.021). Methylation of PM20D1 was lower in infants born to mothers with asthma on inhaled corticosteroid treatment. Methylation of PM20D1 was lower and MRI1 was higher in infants born to atopic mothers without asthma. CONCLUSIONS In an Australian study population, exposure to maternal asthma during pregnancy is associated with differential methylation profiles of infants' peripheral blood DNA, which may act as risk factors for future asthma development.
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Affiliation(s)
- Lakshitha P Gunawardhana
- Priority Research Centre for Asthma and Respiratory Disease, Hunter Medical Research Institute, The University of Newcastle, Sydney, NSW, Australia
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Sekiya M, Yamamuro D, Ohshiro T, Honda A, Takahashi M, Kumagai M, Sakai K, Nagashima S, Tomoda H, Igarashi M, Okazaki H, Yagyu H, Osuga JI, Ishibashi S. Absence of Nceh1 augments 25-hydroxycholesterol-induced ER stress and apoptosis in macrophages. J Lipid Res 2014; 55:2082-92. [PMID: 24891333 DOI: 10.1194/jlr.m050864] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
An excess of cholesterol and/or oxysterols induces apoptosis in macrophages, contributing to the development of advanced atherosclerotic lesions. In foam cells, these sterols are stored in esterified forms, which are hydrolyzed by two enzymes: neutral cholesterol ester hydrolase 1 (Nceh1) and hormone-sensitive lipase (Lipe). A deficiency in either enzyme leads to accelerated growth of atherosclerotic lesions in mice. However, it is poorly understood how the esterification and hydrolysis of sterols are linked to apoptosis. Remarkably, Nceh1-deficient thioglycollate-elicited peritoneal macrophages (TGEMs), but not Lipe-deficient TGEMs, were more susceptible to apoptosis induced by oxysterols, particularly 25-hydroxycholesterol (25-HC), and incubation with 25-HC caused massive accumulation of 25-HC ester in the endoplasmic reticulum (ER) due to its defective hydrolysis, thereby activating ER stress signaling such as induction of CCAAT/enhancer-binding protein-homologous protein (CHOP). These changes were nearly reversed by inhibition of ACAT1. In conclusion, deficiency of Nceh1 augments 25-HC-induced ER stress and subsequent apoptosis in TGEMs. In addition to reducing the cholesteryl ester content of foam cells, Nceh1 may protect against the pro-apoptotic effect of oxysterols and modulate the development of atherosclerosis.
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Affiliation(s)
- Motohiro Sekiya
- Departments of Diabetes and Metabolic Diseases, University of Tokyo, Tokyo 113-8655, Japan
| | - Daisuke Yamamuro
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Taichi Ohshiro
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Akira Honda
- Joint Research Center, Tokyo Medical University Ibaraki Medical Center, Ibaraki 300-0395, Japan
| | - Manabu Takahashi
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Masayoshi Kumagai
- Departments of Diabetes and Metabolic Diseases, University of Tokyo, Tokyo 113-8655, Japan
| | - Kent Sakai
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Shuichi Nagashima
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Hiroshi Tomoda
- Department of Microbial Chemistry, Graduate School of Pharmaceutical Sciences, Kitasato University, Tokyo 108-8641, Japan
| | - Masaki Igarashi
- Departments of Diabetes and Metabolic Diseases, University of Tokyo, Tokyo 113-8655, Japan
| | - Hiroaki Okazaki
- Departments of Diabetes and Metabolic Diseases, University of Tokyo, Tokyo 113-8655, Japan
| | - Hiroaki Yagyu
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Jun-ichi Osuga
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
| | - Shun Ishibashi
- Division of Endocrinology and Metabolism, Department of Medicine, Jichi Medical University, Tochigi 329-0498, Japan
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Sakashita N, Lei X, Kamikawa M, Nishitsuji K. Role of ACAT1-positive late endosomes in macrophages: Cholesterol metabolism and therapeutic applications for Niemann-Pick disease type C. THE JOURNAL OF MEDICAL INVESTIGATION 2014; 61:270-7. [DOI: 10.2152/jmi.61.270] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Affiliation(s)
- Naomi Sakashita
- Department of Human Pathology, Institute of Health Biosciences, the University of Tokushima Graduate School
| | | | - Masashi Kamikawa
- Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University
| | - Kazuchika Nishitsuji
- Department of Human Pathology, Institute of Health Biosciences, the University of Tokushima Graduate School
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Huang LH, Gui J, Artinger E, Craig R, Berwin BL, Ernst PA, Chang CCY, Chang TY. Acat1 gene ablation in mice increases hematopoietic progenitor cell proliferation in bone marrow and causes leukocytosis. Arterioscler Thromb Vasc Biol 2013; 33:2081-7. [PMID: 23846496 DOI: 10.1161/atvbaha.112.301080] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE To investigate the role of acyl-CoA:cholesterol acyltransferase 1 (ACAT1) in hematopoiesis. APPROACH AND RESULTS ACAT1 converts cellular cholesterol to cholesteryl esters for storage in multiple cell types and is a potential drug target for human diseases. In mouse models for atherosclerosis, global Acat1 knockout causes increased lesion size; bone marrow transplantation experiments suggest that the increased lesion size might be caused by ACAT1 deficiency in macrophages. However, bone marrow contains hematopoietic stem cells that give rise to cells in myeloid and lymphoid lineages; these cell types affect atherosclerosis at various stages. Here, we test the hypothesis that global Acat1(-/-) may affect hematopoiesis, rather than affecting macrophage function only, and show that Acat1(-/-) mice contain significantly higher numbers of myeloid cells and other cells than wild-type mice. Detailed analysis of bone marrow cells demonstrated that Acat1(-/-) causes a higher proportion of the stem cell-enriched Lin(-)Sca-1(+)c-Kit(+) population to proliferate, resulting in higher numbers of myeloid progenitor cells. In addition, we show that Acat1(-/-) causes higher monocytosis in Apoe(-/-) mouse during atherosclerosis development. CONCLUSIONS ACAT1 plays important roles in hematopoiesis in normal mouse and in Apoe(-/-) mouse during atherosclerosis development.
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Affiliation(s)
- Li-Hao Huang
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
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21
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Eguchi K, Fujiwara Y, Hayashida A, Horlad H, Kato H, Rotinsulu H, Losung F, Mangindaan REP, de Voogd NJ, Takeya M, Tsukamoto S. Manzamine A, a marine-derived alkaloid, inhibits accumulation of cholesterol ester in macrophages and suppresses hyperlipidemia and atherosclerosis in vivo. Bioorg Med Chem 2013; 21:3831-8. [PMID: 23665143 DOI: 10.1016/j.bmc.2013.04.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 04/06/2013] [Accepted: 04/08/2013] [Indexed: 11/28/2022]
Abstract
The formation of foam cells in macrophages plays an essential role in the progression of early atherosclerotic lesions and therefore its prevention is considered to be a promising target for the treatment of atherosclerosis. We found that an extract of the marine sponge Acanthostrongylophora ingens inhibited the foam cell formation induced by acetylated low-density lipoprotein (AcLDL) in human monocyte-derived macrophages, as measured based on the accumulation of cholesterol ester (CE). Bioassay-guided purification of inhibitors from the extract afforded manzamines. Manzamine A was the most potent inhibitor of foam cell formation, and also suppressed CE formation in Chinese hamster ovary cells overexpressing acyl-CoA:cholesterol acyl-transferase (ACAT)-1 or ACAT-2. In addition, manzamine A inhibited ACAT activity. Next, we orally administered manzamine A to apolipoprotein E (apoE)-deficient mice for 80 days, and found that total cholesterol, free cholesterol, LDL-cholesterol, and triglyceride levels in serum were significantly reduced and the area of atherosclerotic lesions in the aortic sinus was also substantially diminished. These findings clearly suggest that manzamine A suppresses hyperlipidemia and atherosclerosis in apoE-deficient mice by inhibiting ACAT and is therefore a promising lead compound in the prevention or treatment of atherosclerosis. Although manzamine A has been reported to show several biological activities, this is the first report of a suppressive effect of manzamine A on atherosclerosis in vivo.
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Affiliation(s)
- Keisuke Eguchi
- Department of Natural Medicines, Graduate School of Pharmaceutical Sciences, Kumamoto University, Oe-honmachi 5-1, Kumamoto 862-0973, Japan
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22
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Acat1 knockdown gene therapy decreases amyloid-β in a mouse model of Alzheimer's disease. Mol Ther 2013; 21:1497-506. [PMID: 23774792 DOI: 10.1038/mt.2013.118] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Accepted: 05/01/2013] [Indexed: 12/13/2022] Open
Abstract
Both genetic inactivation and pharmacological inhibition of the cholesteryl ester synthetic enzyme acyl-CoA:cholesterol acyltransferase 1 (ACAT1) have shown benefit in mouse models of Alzheimer's disease (AD). In this study, we aimed to test the potential therapeutic applications of adeno-associated virus (AAV)-mediated Acat1 gene knockdown in AD mice. We constructed recombinant AAVs expressing artificial microRNA (miRNA) sequences, which targeted Acat1 for knockdown. We demonstrated that our AAVs could infect cultured mouse neurons and glia and effectively knockdown ACAT activity in vitro. We next delivered the AAVs to mouse brains neurosurgically, and demonstrated that Acat1-targeting AAVs could express viral proteins and effectively diminish ACAT activity in vivo, without inducing appreciable inflammation. We delivered the AAVs to the brains of 10-month-old AD mice and analyzed the effects on the AD phenotype at 12 months of age. Acat1-targeting AAV delivered to the brains of AD mice decreased the levels of brain amyloid-β and full-length human amyloid precursor protein (hAPP), to levels similar to complete genetic ablation of Acat1. This study provides support for the potential therapeutic use of Acat1 knockdown gene therapy in AD.
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23
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24
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Fujiwara Y, Kiyota N, Tsurushima K, Yoshitomi M, Horlad H, Ikeda T, Nohara T, Takeya M, Nagai R. Tomatidine, a tomato sapogenol, ameliorates hyperlipidemia and atherosclerosis in apoE-deficient mice by inhibiting acyl-CoA:cholesterol acyl-transferase (ACAT). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:2472-2479. [PMID: 22224814 DOI: 10.1021/jf204197r] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
It was previously revealed that esculeoside A, a new glycoalkaloid, and esculeogenin A, a new aglycon of esculeoside A, contained in ripe tomato ameliorate atherosclerosis in apoE-deficent mice. This study examined whether tomatidine, the aglycone of tomatine, which is a major tomato glycoalkaloid, also shows similar inhibitory effects on cholesterol ester (CE) accumulation in human monocyte-derived macrophages (HMDM) and atherogenesis in apoE-deficient mice. Tomatidine significantly inhibited the CE accumulation induced by acetylated LDL in HMDM in a dose-dependent manner. Tomatidine also inhibited CE formation in Chinese hamster ovary cells overexpressing acyl-CoA:cholesterol acyl-transferase (ACAT)-1 or ACAT-2, suggesting that tomatidine suppresses both ACAT-1 and ACAT-2 activities. Furthermore, the oral administration of tomatidine to apoE-deficient mice significantly reduced levels of serum cholesterol, LDL-cholesterol, and areas of atherosclerotic lesions. The study provides the first evidence that tomatidine significantly suppresses the activity of ACAT and leads to reduction of atherogenesis.
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Affiliation(s)
- Yukio Fujiwara
- Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
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25
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Hussain MM, Rava P, Walsh M, Rana M, Iqbal J. Multiple functions of microsomal triglyceride transfer protein. Nutr Metab (Lond) 2012; 9:14. [PMID: 22353470 PMCID: PMC3337244 DOI: 10.1186/1743-7075-9-14] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 02/21/2012] [Indexed: 02/08/2023] Open
Abstract
Microsomal triglyceride transfer protein (MTP) was first identified as a major cellular protein capable of transferring neutral lipids between membrane vesicles. Its role as an essential chaperone for the biosynthesis of apolipoprotein B (apoB)-containing triglyceride-rich lipoproteins was established after the realization that abetalipoproteinemia patients carry mutations in the MTTP gene resulting in the loss of its lipid transfer activity. Now it is known that it also plays a role in the biosynthesis of CD1, glycolipid presenting molecules, as well as in the regulation of cholesterol ester biosynthesis. In this review, we will provide a historical perspective about the identification, purification and characterization of MTP, describe methods used to measure its lipid transfer activity, and discuss tissue expression and function. Finally, we will review the role MTP plays in the assembly of apoB-lipoprotein, the regulation of cholesterol ester synthesis, biosynthesis of CD1 proteins and propagation of hepatitis C virus. We will also provide a brief overview about the clinical potentials of MTP inhibition.
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Affiliation(s)
- M Mahmood Hussain
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Paul Rava
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Meghan Walsh
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Muhammad Rana
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
| | - Jahangir Iqbal
- Department of Cell Biology and Pediatrics, SUNY Downstate Medical Center, Brooklyn, NY 11203, USA
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26
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Allahverdian S, Pannu PS, Francis GA. Contribution of monocyte-derived macrophages and smooth muscle cells to arterial foam cell formation. Cardiovasc Res 2012; 95:165-72. [PMID: 22345306 DOI: 10.1093/cvr/cvs094] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Smooth muscle cells (SMCs) are the main cell type in intimal thickenings and some stages of human atherosclerosis. Like monocyte-derived macrophages, SMCs accumulate excess lipids and contribute to the total intimal foam cell population. In contrast, apolipoprotein (Apo)E-deficient and LDL receptor-deficient mice develop atherosclerotic lesions that are macrophage- as opposed to SMC-rich. The lesser contribution of SMCs to lesion development in these mouse models has distracted attention away from the importance of SMC cholesterol homeostasis in the artery wall. Intimal SMCs accumulate excess amounts of cholesteryl esters when compared with medial layer SMCs, possibly explained by reduced ATP-binding cassette transporter A1 expression and ApoA-I binding to intimal-type SMCs. The aim of this review is to compare the relative contribution of monocyte-derived macrophages and SMCs to human vs. mouse atherosclerosis, and describe what is known about lipid uptake and removal mechanisms contributing to arterial macrophage and SMC foam cell formation. An increased understanding of the contribution of these cell types to lesion development will help to delineate their relative importance in atherogenesis and as potential therapeutic targets.
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Affiliation(s)
- Sima Allahverdian
- Department of Medicine, UBC James Hogg Research Centre, Providence Heart + Lung Institute at St Paul's Hospital, Room 166, Burrard Building, 1081 Burrard Street, Vancouver, BC, Canada V6Z 1Y6
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27
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Isoform-specific inhibitors of ACATs: recent advances and promising developments. Future Med Chem 2011; 3:2039-61. [DOI: 10.4155/fmc.11.158] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Acyl-CoA:cholesterol acyltransferase (ACAT) is a promising therapeutic target for cardiovascular diseases. Although a number of synthetic ACAT inhibitors have been developed, they have failed to show efficacy in clinical trials. Now, the presence of two ACAT isoforms with distinct functions, ACAT1 and ACAT2, has been discovered. Thus, the selectivity of ACAT inhibitors toward the two isoforms is important for their development as novel anti-atherosclerotic agents. The selectivity study indicated that fungal pyripyropene A (PPPA) is only an ACAT2-specific inhibitor. Furthermore, PPPA proved orally active in atherogenic mouse models, indicating it possessed cholesterol-lowering and atheroprotective activities. Certain PPPA derivatives, semi-synthetically prepared, possessed more potent and selective in vitro activity than PPPA against ACAT2. This review covers these studies and describes the future prospects of ACAT2-specific inhibitors.
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28
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Nohara T, Ono M, Ikeda T, Fujiwara Y, El-Aasr M. The tomato saponin, esculeoside A. JOURNAL OF NATURAL PRODUCTS 2010; 73:1734-1741. [PMID: 20853874 DOI: 10.1021/np100311t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Esculeoside A (2), a spirosolane steroidal glycoside, is a major constituent isolated from Solanum lycopersicum, a commercial strain of mini tomatoes. The content variability of esculeoside A (2) was examined in mini, midi, and Momotaro tomatoes and various processed tomato products. In the green immature tomato fruit, tomatine (1) is oxidized at C-23 and C-27 to produce esculeoside A (2) in the ripe fruit. Further, esculeoside A (2) is partly converted to 3β-hydroxy-5α-pregn-16-en-20-one 3-O-β-lycotetraoside (6), a pregnane glycoside, in the overripe fruit. Esculeogenin A (3), the sapogenol of 2, is easily converted into 3β,16β-dihydroxy-5α-pregn-20-one (17). Metabolic studies showed excretion of androstane derivatives in the urine of human volunteer subjects after tomato consumption. Esculeogenin A (3) inhibited the accumulation of cholesterol esters in macrophages through its effects on acyl-CoA:cholesterol acyl transferase (ACAT). Oral administration of esculeoside A (2) to apoE-deficient mice significantly reduced serum levels of cholesterol, triglycerides, and LDL-cholesterol and ameliorated the severity of atherosclerotic lesions.
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Affiliation(s)
- Toshihiro Nohara
- Faculty of Pharmaceutical Sciences, Sojo University, 22-1, 4-Chome, Ikeda, Kumamoto 860-0082, Japan.
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29
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Sakashita N, Chang CCY, Lei X, Fujiwara Y, Takeya M, Chang TY. Cholesterol loading in macrophages stimulates formation of ER-derived vesicles with elevated ACAT1 activity. J Lipid Res 2010; 51:1263-72. [PMID: 20460577 DOI: 10.1194/jlr.m900288] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
ACAT1 is normally a resident enzyme in the endoplasmic reticulum (ER). We previously showed that treating macrophages with denatured LDL causes a large increase in ER-derived, ACAT1-positive vesicles. Here, we isolated ER membranes and ER-derived vesicles to examine their ACAT enzyme activity in vitro. The results showed that when macrophages are grown under normal conditions, ACAT1 is located in high density ER membrane; its enzymatic activity is relatively low. Loading macrophages with cholesterol did not increase the total cellular ACAT1 protein content significantly but caused more ACAT1 to appear in ER-derived vesicles. These vesicles exhibit lower density and are associated with markers of both ER and the trans-Golgi network. When normalized with equal ACAT1 protein mass, the enzymatic activities of ACAT1 in ER-derived vesicles were 3-fold higher than those present in ER membrane. Results using reconstituted ACAT enzyme assay showed that the increase in enzyme activity in ER-derived vesicles is not due to an increase in the cholesterol content associated with these vesicles. Overall, our results show that macrophages cope with cholesterol loading by using a novel mechanism: they produce more ER-derived vesicles with elevated ACAT1 enzyme activity without having to produce more ACAT1 protein.
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Affiliation(s)
- Naomi Sakashita
- Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto 861-8556, Japan.
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30
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Sakashita N, Chang CC, Lei X, Fujiwara Y, Takeya M, Chang TY. Cholesterol loading in macrophages stimulates formation of ER-derived vesicles with elevated ACAT1 activity. J Lipid Res 2010. [DOI: 10.1194/jlr.m900288-jlr200] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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31
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Lei X, Fujiwara Y, Chang CCY, Chang TY, Takeya M, Sakashita N. Association of ACAT1-Positive Vesicles with Late Endosomes/ Lysosomes in Cholesterol-Rich Human Macrophages. J Atheroscler Thromb 2010; 17:740-50. [DOI: 10.5551/jat.4416] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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32
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Abstract
The enzymes acyl-coenzyme A (CoA):cholesterol acyltransferases (ACATs) are membrane-bound proteins that utilize long-chain fatty acyl-CoA and cholesterol as substrates to form cholesteryl esters. In mammals, two isoenzymes, ACAT1 and ACAT2, encoded by two different genes, exist. ACATs play important roles in cellular cholesterol homeostasis in various tissues. This chapter summarizes the current knowledge on ACAT-related research in two areas: 1) ACAT genes and proteins and 2) ACAT enzymes as drug targets for atherosclerosis and for Alzheimer's disease.
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Affiliation(s)
- Ta-Yuan Chang
- Department of Biochemistry, Dartmouth Medical School, 1 Rope Ferry Rd., Hanover, NH 03755-1404, USA.
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33
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Lei L, Xiong Y, Chen J, Yang JB, Wang Y, Yang XY, Chang CCY, Song BL, Chang TY, Li BL. TNF-alpha stimulates the ACAT1 expression in differentiating monocytes to promote the CE-laden cell formation. J Lipid Res 2009; 50:1057-67. [PMID: 19189937 DOI: 10.1194/jlr.m800484-jlr200] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
High levels of the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) are present in atherosclerotic lesions. TNF-alpha regulates expression of multiple genes involved in various stages of atherosclerosis, and it exhibits proatherosclerotic and antiatherosclerotic properties. ACAT catalyzes the formation of cholesteryl esters (CE) in monocytes/macrophages, and it promotes the foam cell formation at the early stage of atherosclerosis. We hypothesize that TNF-alpha may be involved in regulating the ACAT gene expression in monocytes/macrophages. In this article, we show that in cultured, differentiating human monocytes, TNF-alpha enhances the expression of the ACAT1 but not ACAT2 gene, increases the cholesteryl ester accumulation, and promotes the lipid-laden cell formation. Several other proinflammatory cytokines tested do not affect the ACAT1 gene expression. The stimulation effect is consistent with a receptor-dependent process, and is blocked by using nuclear factor-kappa B (NF-kappa B) inhibitors. A functional and unique NF-kappa B element located within the human ACAT1 gene proximal promoter is required to mediate the action of TNF-alpha. Our data demonstrate that TNF-alpha, through the NF-kappa B pathway, specifically enhances the expression of human ACAT1 gene to promote the CE-laden cell formation from the differentiating monocytes, and our data support the hypothesis that TNF-alpha is proatherosclerotic during early phase of lesion development.
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Affiliation(s)
- Lei Lei
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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Iqbal J, Rudel LL, Hussain MM. Microsomal triglyceride transfer protein enhances cellular cholesteryl esterification by relieving product inhibition. J Biol Chem 2008; 283:19967-80. [PMID: 18502767 DOI: 10.1074/jbc.m800398200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cholesteryl ester synthesis by the acyl-CoA:cholesterol acyltransferase enzymes ACAT1 and ACAT2 is, in part, a cellular homeostatic mechanism to avoid toxicity associated with high free cholesterol levels. In hepatocytes and enterocytes, cholesteryl esters are secreted as part of apoB lipoproteins, the assembly of which is critically dependent on microsomal triglyceride transfer protein (MTP). Conditional genetic ablation of MTP reduces cholesteryl esters and enhances free cholesterol in the liver and intestine without diminishing ACAT1 and ACAT2 mRNA levels. As expected, increases in hepatic free cholesterol are associated with decreases in 3-hydroxy-3-methylglutaryl-CoA reductase and increases in ATP-binding cassette transporter 1 mRNA levels. Chemical inhibition of MTP also decreases esterification of cholesterol in Caco-2 and HepG2 cells. Conversely, coexpression of MTP and apoB in AC29 cells stably transfected with ACAT1 and ACAT2 increases cholesteryl ester synthesis. Liver and enterocyte microsomes from MTP-deficient animals synthesize lesser amounts of cholesteryl esters in vitro, but addition of purified MTP and low density lipoprotein corrects this deficiency. Enrichment of microsomes with cholesteryl esters also inhibits cholesterol ester synthesis. Thus, MTP enhances cellular cholesterol esterification by removing cholesteryl esters from their site of synthesis and depositing them into nascent apoB lipoproteins. Therefore, MTP plays a novel role in regulating cholesteryl ester biosynthesis in cells that produce lipoproteins. We speculate that non-lipoprotein-producing cells may use different mechanisms to alleviate product inhibition and modulate cholesteryl ester biosynthesis.
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Affiliation(s)
- Jahangir Iqbal
- Department of Anatomy and Cell Biology and Pediatrics, State University of New York Downstate Medical Center, Brooklyn, NY 11203, USA
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35
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Fujiwara Y, Kiyota N, Hori M, Matsushita S, Iijima Y, Aoki K, Shibata D, Takeya M, Ikeda T, Nohara T, Nagai R. Esculeogenin A, a new tomato sapogenol, ameliorates hyperlipidemia and atherosclerosis in ApoE-deficient mice by inhibiting ACAT. Arterioscler Thromb Vasc Biol 2007; 27:2400-6. [PMID: 17872457 DOI: 10.1161/atvbaha.107.147405] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE We recently identified esculeoside A, a new spirosolane-type glycoside, with a content in tomatoes that is 4-fold higher than that of lycopene. In the present study, we examined the effects of esculeoside A and esculeogenin A, a new aglycon of esculeoside A, on foam cell formation in vitro and atherogenesis in apoE-deficient mice. METHODS AND RESULTS Esculeogenin A significantly inhibited the accumulation of cholesterol ester (CE) induced by acetylated low density lipoprotein (acetyl-LDL) in human monocyte-derived macrophages (HMDM) in a dose-dependent manner without inhibiting triglyceride accumulation, however, it did not inhibit the association of acetyl-LDL to the cells. Esculeogenin A also inhibited CE formation in Chinese hamster ovary cells overexpressing acyl-coenzymeA (CoA): cholesterol acyl-transferase (ACAT)-1 or ACAT-2, suggesting that esculeogenin A suppresses the activity of both ACAT-1 and ACAT-2. Furthermore, esculeogenin A prevented the expression of ACAT-1 protein, whereas that of SR-A and SR-BI was not suppressed. Oral administration of esculeoside A to apoE-deficient mice significantly reduced the levels of serum cholesterol, triglycerides, LDL-cholesterol, and the areas of atherosclerotic lesions without any detectable side effects. CONCLUSIONS Our study provides the first evidence that purified esculeogenin A significantly suppresses the activity of ACAT protein and leads to reduction of atherogenesis.
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Affiliation(s)
- Yukio Fujiwara
- Department of Medical Biochemistry, Faculty of Medical and Pharmaceutical Sciences, Kumamoto University, Honjo, 1-1-1, Kumamoto 860-8556, Japan
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36
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37
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Song BL, Wang CH, Yao XM, Yang L, Zhang WJ, Wang ZZ, Zhao XN, Yang JB, Qi W, Yang XY, Inoue K, Lin ZX, Zhang HZ, Kodama T, Chang C, Liu YK, Chang TY, Li BL. Human acyl-CoA:cholesterol acyltransferase 2 gene expression in intestinal Caco-2 cells and in hepatocellular carcinoma. Biochem J 2006; 394:617-26. [PMID: 16274362 PMCID: PMC1383711 DOI: 10.1042/bj20051417] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2005] [Revised: 11/02/2005] [Accepted: 11/08/2005] [Indexed: 11/17/2022]
Abstract
Humans express two ACAT (acyl-CoA:cholesterol acyltransferase) genes, ACAT1 and ACAT2. ACAT1 is ubiquitously expressed, whereas ACAT2 is primarily expressed in intestinal mucosa and plays an important role in intestinal cholesterol absorption. To investigate the molecular mechanism(s) responsible for the tissue-specific expression of ACAT2, we identified five cis-elements within the human ACAT2 promoter, four for the intestinal-specific transcription factor CDX2 (caudal type homeobox transcription factor 2), and one for the transcription factor HNF1alpha (hepatocyte nuclear factor 1alpha). Results of luciferase reporter and electrophoretic mobility shift assays show that CDX2 and HNF1alpha exert a synergistic effect, enhancing the ACAT2 promoter activity through binding to these cis-elements. In undifferentiated Caco-2 cells, the ACAT2 expression is increased when exogenous CDX2 and/or HNF1alpha are expressed by co-transfection. In differentiated Caco-2 cells, the ACAT2 expression significantly decreases when the endogenous CDX2 or HNF1alpha expression is suppressed by using RNAi (RNA interference) technology. The expression levels of CDX2, HNF1alpha, and ACAT2 are all greatly increased when the Caco-2 cells differentiate to become intestinal-like cells. These results provide a molecular mechanism for the tissue-specific expression of ACAT2 in intestine. In normal adult human liver, CDX2 expression is not detectable and the ACAT2 expression is very low. In the hepatoma cell line HepG2 the CDX2 expression is elevated, accounting for its elevated ACAT2 expression. A high percentage (seven of fourteen) of liver samples from patients affected with hepatocellular carcinoma exhibited elevated ACAT2 expression. Thus, the elevated ACAT2 expression may serve as a new biomarker for certain form(s) of hepatocellular carcinoma.
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Key Words
- acyl-coa:cholesterol acyltransferase (acat2)
- caudal type homeobox transcription factor 2 (cdx2)
- hepatocyte nuclear factor 1α (hnf1α)
- intestine
- hepatocellular carcinoma (hcc)
- acat, acyl-coa:cholesterol acyltransferase
- afp, α-fetalprotein
- cdx2, caudal type homeobox transcription factor 2
- cldn2, claudin 2 gene
- dmem, dulbecco's modified eagle's medium
- emsa, electrophoretic mobility shift assay
- fbs, fetal bovine serum
- gapdh, glyceraldehyde-3-phosphate dehydrogenase
- hcc, hepatocellular carcinoma
- hnf1α, hepatocyte nuclear factor 1α
- lph, lactase-phlorizin hydrolase gene
- luc, luciferase reporter
- rnai, rna interference
- rt, reverse transcriptase
- ugt1a8–10, udp glucuronosyltransferase 1 family polypeptides a8–10 gene
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Affiliation(s)
- Bao-Liang Song
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Can-Hua Wang
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- †Department of Biochemistry and Technology, Jiao Tong University, Shanghai 200030, China
| | - Xiao-Min Yao
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- †Department of Biochemistry and Technology, Jiao Tong University, Shanghai 200030, China
| | - Li Yang
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Wen-Jing Zhang
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- ‡Department of Biochemistry and Technology, East China University of Science and Technology, Shanghai 200237, China
| | - Zhen-Zhen Wang
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xiao-Nan Zhao
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Jin-Bo Yang
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Wei Qi
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Xin-Ying Yang
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Kenji Inoue
- §Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | - Zhi-Xin Lin
- †Department of Biochemistry and Technology, Jiao Tong University, Shanghai 200030, China
| | - Hui-Zhan Zhang
- ‡Department of Biochemistry and Technology, East China University of Science and Technology, Shanghai 200237, China
| | - Tatsuhiko Kodama
- §Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
| | | | - Yin-Kun Liu
- ¶Liver Cancer Institute of Zhong San Hospital, Fudan University, Shanghai 200031, China
| | - Ta-Yuan Chang
- ∥Department of Biochemistry, Dartmouth Medical School, Hanover, NH 03755, U.S.A
| | - Bo-Liang Li
- *State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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Chang C, Dong R, Miyazaki A, Sakashita N, Zhang Y, Liu J, Guo M, Li BL, Chang TY. Human acyl-CoA:cholesterol acyltransferase (ACAT) and its potential as a target for pharmaceutical intervention against atherosclerosis. Acta Biochim Biophys Sin (Shanghai) 2006; 38:151-6. [PMID: 16518538 DOI: 10.1111/j.1745-7270.2006.00154.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Acyl-CoA:cholesterol acyltransferase (ACAT) catalyzes the formation of cholesteryl esters from cholesterol and long-chain fatty-acyl-coenzyme A. At the single-cell level, ACAT serves as a regulator of intracellular cholesterol homeostasis. In addition, ACAT supplies cholesteryl esters for lipoprotein assembly in the liver and small intestine. Under pathological conditions, the accumulation of cholesteryl esters produced by ACAT in macrophages contributes to foam cell formation, a hallmark of the early stage of atherosclerosis. Several reviews addressing various aspects of ACAT and ACAT inhibitors are available. This review briefly outlines the current knowledge on the biochemical properties of human ACATs, and then focuses on discussing the merit of ACAT as a drug target for pharmaceutical interventions against atherosclerosis.
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Affiliation(s)
- Catherine Chang
- Department of Biochemistry, Dartmouth Medical School, Hanover, New Hampshire 03755, USA.
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Yao XM, Wang CH, Song BL, Yang XY, Wang ZZ, Qi W, Lin ZX, Chang CCY, Chang TY, Li BL. Two human ACAT2 mRNA variants produced by alternative splicing and coding for novel isoenzymes. Acta Biochim Biophys Sin (Shanghai) 2005; 37:797-806. [PMID: 16331323 DOI: 10.1111/j.1745-7270.2005.00118.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Acyl coenzyme A:cholesterol acyltransferase 2 (ACAT2) plays an important role in cholesterol absorption. Human ACAT2 is highly expressed in small intestine and fetal liver, but its expression is greatly diminished in adult liver. The full-length human ACAT2 mRNA encodes a protein, designated ACAT2a, with 522 amino acids. We have previously reported the organization of the human ACAT2 gene and the differentiation-dependent promoter activity in intestinal Caco-2 cells. In the current work, two human ACAT2 mRNA variants produced by alternative splicing are cloned and predicted to encode two novel ACAT2 isoforms, named ACAT2b and ACAT2c, with 502 and 379 amino acids, respectively. These mRNA variants differ from ACAT2a mRNA by lack of the exon 4 (ACAT2b mRNA) and exons 4-5 plus 8-9-10 (ACAT2c mRNA). Significantly, comparable amounts of the alternatively spliced ACAT2 mRNA variants were detected by RT-PCR, and Western blot analysis confirmed the presence of their corresponding proteins in human liver and intestinecells. Furthermore, phosphorylation and enzymatic activity analyses demonstrated that the novel isoenzymes ACAT2b and ACAT2c lacked the phosphorylatable site SLLD, and their enzymatic activities reduced to 25%-35% of that of ACAT2a. These evidences indicate that alternative splicing produces two human ACAT2 mRNA variants that encode the novel ACAT2 isoenzymes. Our findings might help to understand the regulation of the ACAT2 gene expression under certain physiological and pathological conditions.
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Affiliation(s)
- Xiao-Min Yao
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China
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Tosi MR, Tugnoli V. Cholesteryl esters in malignancy. Clin Chim Acta 2005; 359:27-45. [PMID: 15939411 DOI: 10.1016/j.cccn.2005.04.003] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Revised: 03/31/2005] [Accepted: 04/04/2005] [Indexed: 01/23/2023]
Abstract
Cholesteryl esters, formed by the esterification of cholesterol with long-chain fatty acids, on one hand, are the means by which cholesterol is transported through the blood by lipoproteins, on the other, the way cholesterol itself can be accumulated in the cells. Therefore, these important molecules play an active part in metabolic pathways that form the basis of cholesterol trafficking and homeostasis. The role of different regulatory mechanisms in cholesterol homeostasis in physiologic and neoplastic conditions with emphasis on intracellular content of cholesteryl esters is here reviewed. Numerous studies carried out on tumor cell lines, experimental tumors, and human tumors have shown an abnormal cholesterol metabolism that is reflected by an increase in intracellular cholesteryl esters due to an alteration in all the mechanisms that form the basis of regulation, in particular: cholesterol de novo biosynthesis; uptake of exogenous cholesterol LDL receptor mediated; cholesterol esterification mediated by the ACAT activity; cholesterol efflux HDL receptor mediated. The most recent analytic-spectroscopic applications that permit cholesteryl ester determination on tumor lipidic extracts and directly in vivo are also reported. This review gives an overview of cholesterol homeostasis in physiological and pathological conditions where cholesteryl esters are over-expressed.
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Affiliation(s)
- Maria R Tosi
- ITOI-CNR, presso IOR, via di Barbiano 1/10, 40136, Bologna, Italy.
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Freeman NE, Rusinol AE, Linton M, Hachey DL, Fazio S, Sinensky MS, Thewke D. Acyl-coenzyme A:cholesterol acyltransferase promotes oxidized LDL/oxysterol-induced apoptosis in macrophages. J Lipid Res 2005; 46:1933-43. [PMID: 15995174 PMCID: PMC2768430 DOI: 10.1194/jlr.m500101-jlr200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
7-Ketocholesterol (7KC) is a cytotoxic component of oxidized low density lipoproteins (OxLDLs) and induces apoptosis in macrophages by a mechanism involving the activation of cytosolic phospholipase A2 (cPLA2). In the current study, we examined the role of ACAT in 7KC-induced and OxLDL-induced apoptosis in murine macrophages. An ACAT inhibitor, Sandoz 58-035, suppressed 7KC-induced apoptosis in P388D1 cells and both 7KC-induced and OxLDL-induced apoptosis in mouse peritoneal macrophages (MPMs). Furthermore, compared with wild-type MPMs, ACAT-1-deficient MPMs demonstrated significant resistance to both 7KC-induced and OxLDL-induced apoptosis. Macrophages treated with 7KC accumulated ACAT-derived [14C]cholesteryl and [3H]7-ketocholesteryl esters. Tandem LC-MS revealed that the 7KC esters contained primarily saturated and monounsaturated fatty acids. An inhibitor of cPLA2, arachidonyl trifluoromethyl ketone, prevented the accumulation of 7KC esters and inhibited 7KC-induced apoptosis in P388D1 cells. The decrease in 7KC ester accumulation produced by the inhibition of cPLA2 was reversed by supplementing with either oleic or arachidonic acid (AA); however, only AA supplementation restored the induction of apoptosis by 7KC. These results suggest that 7KC not only initiates the apoptosis pathway by activating cPLA2, as we have reported previously, but also participates in the downstream signaling pathway when esterified by ACAT to form 7KC-arachidonate.
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Affiliation(s)
- Natalie E Freeman
- Department of Biochemistry and Molecular Biology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City, TN 37614-0581, USA
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Rudel LL, Lee RG, Parini P. ACAT2 is a target for treatment of coronary heart disease associated with hypercholesterolemia. Arterioscler Thromb Vasc Biol 2005; 25:1112-8. [PMID: 15831806 DOI: 10.1161/01.atv.0000166548.65753.1e] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The inhibition of intracellular cholesterol esterification as a means to prevent atherosclerosis has been considered to have potential for many years. Two different ACAT enzymes were discovered about 7 years ago, and it has become clear that the two enzymes provide separate physiologic functions. Much has been learned from mice with gene deletions for either ACAT1 or ACAT2. Deletion of ACAT2 has consistently been atheroprotective whereas deletion of ACAT1 has been varyingly problematic. ACAT1 functions in converting cellular cholesterol into cholesteryl ester in response to cholesterol abundance inside the cells. In atherosclerotic lesions, where macrophages ingest excess cholesterol, the ability to esterify the newly-acquired cholesterol seems important for cell survival. Inhibition of ACAT1 may bring undesired consequences with destabilization of cellular membrane function upon cholesterol accumulation leading to macrophage cell death. In contrast, ACAT2 is expressed only in hepatocytes and enterocytes, where ACAT1 is silent, and appears to provide cholesteryl esters for transport in lipoproteins. These two cell types have an abundance of additional mechanisms for disposing of cholesterol so that depletion of ACAT2 does not signal apoptosis. At the present time, the bulk of the available data suggest that the strategy seeming to bear the most potential for treatment of coronary heart disease associated with hypercholesterolemia would be to specifically inhibit ACAT2.
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Affiliation(s)
- Lawrence L Rudel
- Lipid Sciences Research Program, Wake Forest University School of Medicine, Winston-Salem, NC 27157-1040, USA.
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Yang L, Lee O, Chen J, Chen J, Chang CCY, Zhou P, Wang ZZ, Ma HH, Sha HF, Feng JX, Wang Y, Yang XY, Wang L, Dong R, Ornvold K, Li BL, Chang TY. Human Acyl-Coenzyme A:Cholesterol Acyltransferase 1 (acat1) Sequences Located in Two Different Chromosomes (7 and 1) Are Required to Produce a Novel ACAT1 Isoenzyme with Additional Sequence at the N Terminus. J Biol Chem 2004; 279:46253-62. [PMID: 15319423 DOI: 10.1074/jbc.m408155200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A rare form of human ACAT1 mRNA, containing the optional long 5'-untranslated region, is produced as a 4.3-kelonucleotide chimeric mRNA through a novel interchromosomal trans-splicing of two discontinuous RNAs transcribed from chromosomes 1 and 7. To investigate its function, we express the chimeric ACAT1 mRNA in Chinese hamster ovary cells and show that it can produce a larger ACAT1 protein, with an apparent molecular mass of 56 kDa on SDS-PAGE, in addition to the normal, 50-kDa ACAT1 protein, which is produced from the ACAT1 mRNAs without the optional long 5'-untranslated repeat. To produce the 56-kDa ACAT1, acat1 sequences located at both chromosomes 7 and 1 are required. The 56-kDa ACAT1 can be recognized by specific antibodies prepared against the predicted additional amino acid sequence located upstream of the N-terminal of the ACAT1(ORF). The translation initiation codon for the 56-kDa protein is GGC, which encodes for glycine, as deduced by mutation analysis and mass spectrometry. Similar to the 50-kDa protein, when expressed alone, the 56-kDa ACAT1 is located in the endoplasmic reticulum and is enzymatically active. The 56-kDa ACAT1 is present in native human cells, including human monocyte-derived macrophages. Our current results show that the function of the chimeric ACAT1 mRNA is to increase the ACAT enzyme diversity by producing a novel isoenzyme. To our knowledge, our result provides the first mammalian example that a trans-spliced mRNA produces a functional protein.
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Affiliation(s)
- Li Yang
- State Key Laboratory of Molecular Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue-Yang Rd., Shanghai 200031, China
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