| Association of ACAT1-positive vesicles with late endosomes/ lysosomes in cholesterol-rich human macrophages. | |
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MedLine Citation:
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PMID: 20523008 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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AIM: Acyl-coenzyme A: cholesterol acyltransferase1 (ACAT1) is an endoplasmic reticulum (ER)-resident enzyme that catalyzes the conversion of cholesterol into cholesteryl esters. We previously showed that cholesterol-loaded macrophages produce numerous ER-derived vesicles with elevated ACAT1 enzyme activity; some of these vesicles were shown to be closely associated with Golgi-related organelle(s). The aim of this study was to investigate the translocation of ACAT1 vesicle in cholesterol-loaded macrophages. METHODS: To demonstrate association of ACAT1 with late endosomes/lysosomes (LE/LS), primary human macrophages with or without cholesterol-loading was subjected to confocal microscopy, immunoelectron microscopy, subcellular fractionation, and immunoadsorption assay. Furthermore, cholesterol esterification assay was also carried out to investigate function of ACAT1 associated LE/LS. RESULTS: Confocal fluorescence microscopy revealed that no significant ACAT1 signal was associated with the signal for LAMP2, a marker protein for LE/LS, in cholesterol non-loaded macrophages; however, approximately 20% of the total ACAT1 signals colocalized with the LAMP2 signal in cholesterol-loaded macrophages. ACAT1-positive membranes isolated by immunoadsorption using ACAT1-specific antibody contained LAMP2, demonstrating the association of ACAT1 and LE/LS. In addition, in macrophages phagocytosing latex beads, the close association of ACAT1 with LE/LS can be demonstrated in phagosomes isolated from cholesterol-loaded macrophages, not from non-loaded macrophages. Furthermore, cholesterol-loaded macrophages re-esterified aggregated LDL-derived cholesteryl ester even in the presence of U18666A, a reagent known to block egression of cholesterol from LE/LS. CONCLUSION: Our results indicated that cholesterol-loaded human macrophages produce LE/LS in close association with ACAT1, and may promote efficient esterification of modified LDL-derived free cholesterol on LE/LS. |
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Authors:
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XiaoFeng Lei; Yukio Fujiwara; Catherine C Y Chang; Ta-Yuan Chang; Motohiro Takeya; Naomi Sakashita |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-06-02 |
Journal Detail:
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Title: Journal of atherosclerosis and thrombosis Volume: 17 ISSN: 1880-3873 ISO Abbreviation: J. Atheroscler. Thromb. Publication Date: 2010 Jul |
Date Detail:
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Created Date: 2010-08-04 Completed Date: 2010-11-16 Revised Date: 2011-07-01 |
Medline Journal Info:
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Nlm Unique ID: 9506298 Medline TA: J Atheroscler Thromb Country: Japan |
Other Details:
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Languages: eng Pagination: 740-50 Citation Subset: IM |
Affiliation:
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Department of Cell Pathology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Kumamoto, Japan. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Acetyl-CoA C-Acetyltransferase
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metabolism* Animals Cells, Cultured Cholesterol / metabolism* Endoplasmic Reticulum / metabolism* Endosomes / metabolism* Esterification Humans Immunoblotting Lysosomal-Associated Membrane Protein 2 / metabolism Lysosomes / metabolism* Macrophages / metabolism* Mice Subcellular Fractions |
| Chemical | |
Reg. No./Substance:
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0/Lysosomal-Associated Membrane Protein 2; 57-88-5/Cholesterol; EC 2.3.1.9/ACAT1 protein, human; EC 2.3.1.9/Acat1 protein, mouse; EC 2.3.1.9/Acetyl-CoA C-Acetyltransferase |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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