15(S)-Lipoxygenase-1 associates with neutral lipid droplets in macrophage foam cells: evidence of lipid droplet metabolism
15(S)-lipoxygenase-1 (15-LO-1) was present in the whole-cell homogenate of an acute human monocytic leukemia cell line (THP-1). Additionally, 15-LO-1 was detected on neutral lipid droplets isolated from THP-1 foam cells. To investigate if 15-LO-1 is active on lipid droplets, we used the mouse leukem...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2009-12-01
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| Series: | Journal of Lipid Research |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S002222752030660X |
| _version_ | 1818735028707786752 |
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| author | Ginny L. Weibel Michelle R. Joshi Cong Wei Sandra R. Bates Ian A. Blair George H. Rothblat |
| author_facet | Ginny L. Weibel Michelle R. Joshi Cong Wei Sandra R. Bates Ian A. Blair George H. Rothblat |
| author_sort | Ginny L. Weibel |
| collection | DOAJ |
| description | 15(S)-lipoxygenase-1 (15-LO-1) was present in the whole-cell homogenate of an acute human monocytic leukemia cell line (THP-1). Additionally, 15-LO-1 was detected on neutral lipid droplets isolated from THP-1 foam cells. To investigate if 15-LO-1 is active on lipid droplets, we used the mouse leukemic monocytic macrophage cell line (RAW 264.7), which are stably transfected with human 15-LO-1. The RAW 15-LO-1 cells were incubated with acetylated low density lipoprotein to generate foam cells. 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE], the major 15-LO-1 metabolite of arachidonic acid, was produced in the 15-LO-1 RAW but not in the mock transfected cells when incubated with arachidonic acid. Lipid droplets were isolated from the cells and incubated with arachidonic acid, and production of 15(S)-HETE was measured over 2 h. 15(S)-HETE was produced in the incubations with the lipid droplets, and this production was attenuated when the lipid droplet fraction was subjected to enzyme inactivation through heating. Efflux of 15(S)-HETE from cholesteryl ester-enriched 15-LO RAW cells, when lipid droplets are present, was significantly reduced compared with that from cells enriched with free cholesterol (lipid droplets are absent). We propose that 15-LO-1 is present and functional on cytoplasmic neutral lipid droplets in macrophage foam cells, and these droplets may act to accumulate the anti-inflammatory lipid mediator 15(S)-HETE. |
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| format | Article |
| id | doaj.art-2a214afe104d4cb1aecd7c9d8101cad8 |
| institution | Directory Open Access Journal |
| issn | 0022-2275 |
| language | English |
| last_indexed | 2024-12-18T00:14:45Z |
| publishDate | 2009-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Lipid Research |
| spelling | doaj.art-2a214afe104d4cb1aecd7c9d8101cad82022-12-21T21:27:33ZengElsevierJournal of Lipid Research0022-22752009-12-0150122371237615(S)-Lipoxygenase-1 associates with neutral lipid droplets in macrophage foam cells: evidence of lipid droplet metabolismGinny L. Weibel0Michelle R. Joshi1Cong Wei2Sandra R. Bates3Ian A. Blair4George H. Rothblat5To whom correspondence should be addressed; Division of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PADivision of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PACenters for Cancer Pharmacology and Excellence in Environmental Toxicology, University of Pennsylvania School of Medicine Philadelphia PAInstitute for Environmental Medicine and Department of Physiology, University of Pennsylvania School of Medicine, Philadelphia, PACenters for Cancer Pharmacology and Excellence in Environmental Toxicology, University of Pennsylvania School of Medicine Philadelphia PADivision of Gastroenterology and Nutrition, The Children's Hospital of Philadelphia, Philadelphia, PA15(S)-lipoxygenase-1 (15-LO-1) was present in the whole-cell homogenate of an acute human monocytic leukemia cell line (THP-1). Additionally, 15-LO-1 was detected on neutral lipid droplets isolated from THP-1 foam cells. To investigate if 15-LO-1 is active on lipid droplets, we used the mouse leukemic monocytic macrophage cell line (RAW 264.7), which are stably transfected with human 15-LO-1. The RAW 15-LO-1 cells were incubated with acetylated low density lipoprotein to generate foam cells. 15(S)-hydroxyeicosatetraenoic acid [15(S)-HETE], the major 15-LO-1 metabolite of arachidonic acid, was produced in the 15-LO-1 RAW but not in the mock transfected cells when incubated with arachidonic acid. Lipid droplets were isolated from the cells and incubated with arachidonic acid, and production of 15(S)-HETE was measured over 2 h. 15(S)-HETE was produced in the incubations with the lipid droplets, and this production was attenuated when the lipid droplet fraction was subjected to enzyme inactivation through heating. Efflux of 15(S)-HETE from cholesteryl ester-enriched 15-LO RAW cells, when lipid droplets are present, was significantly reduced compared with that from cells enriched with free cholesterol (lipid droplets are absent). We propose that 15-LO-1 is present and functional on cytoplasmic neutral lipid droplets in macrophage foam cells, and these droplets may act to accumulate the anti-inflammatory lipid mediator 15(S)-HETE.http://www.sciencedirect.com/science/article/pii/S002222752030660Xlipoxygenasescholesterolcholesteryl ester |
| spellingShingle | Ginny L. Weibel Michelle R. Joshi Cong Wei Sandra R. Bates Ian A. Blair George H. Rothblat 15(S)-Lipoxygenase-1 associates with neutral lipid droplets in macrophage foam cells: evidence of lipid droplet metabolism Journal of Lipid Research lipoxygenases cholesterol cholesteryl ester |
| title | 15(S)-Lipoxygenase-1 associates with neutral lipid droplets in macrophage foam cells: evidence of lipid droplet metabolism |
| title_full | 15(S)-Lipoxygenase-1 associates with neutral lipid droplets in macrophage foam cells: evidence of lipid droplet metabolism |
| title_fullStr | 15(S)-Lipoxygenase-1 associates with neutral lipid droplets in macrophage foam cells: evidence of lipid droplet metabolism |
| title_full_unstemmed | 15(S)-Lipoxygenase-1 associates with neutral lipid droplets in macrophage foam cells: evidence of lipid droplet metabolism |
| title_short | 15(S)-Lipoxygenase-1 associates with neutral lipid droplets in macrophage foam cells: evidence of lipid droplet metabolism |
| title_sort | 15 s lipoxygenase 1 associates with neutral lipid droplets in macrophage foam cells evidence of lipid droplet metabolism |
| topic | lipoxygenases cholesterol cholesteryl ester |
| url | http://www.sciencedirect.com/science/article/pii/S002222752030660X |
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