Journal
ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY
Volume 29, Issue 10, Pages 1615-U504Publisher
LIPPINCOTT WILLIAMS & WILKINS
DOI: 10.1161/ATVBAHA.109.191882
Keywords
atherosclerosis; foam cells; surface-connected compartment; Rho GTPases; F-actin
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Funding
- NIH [R37-DK27083, R01 HL037560]
- NATIONAL HEART, LUNG, AND BLOOD INSTITUTE [R01HL093324] Funding Source: NIH RePORTER
- NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES [R37DK027083] Funding Source: NIH RePORTER
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Objective-Interaction of macrophages with aggregated matrix-anchored lipoprotein deposits is an important initial step in atherogenesis. Aggregated lipoproteins require different cellular uptake processes than those used for endocytosis of monomeric lipoproteins. In this study, we tested the hypothesis that engagement of aggregated LDL (agLDL) by macrophages could lead to local increases in free cholesterol levels and that these increases in free cholesterol regulate signals that control cellular actin. Methods and Results-AgLDL resides for prolonged periods in surface-connected compartments. Although agLDL is still extracellular, we demonstrate that an increase in free cholesterol occurs at sites of contact between agLDL and cells because of hydrolysis of agLDL-derived cholesteryl ester. This increase in free cholesterol causes enhanced actin polymerization around the agLDL. Inhibition of cholesteryl ester hydrolysis results in decreased actin polymerization. Conclusions-We describe a novel process that occurs during agLDL-macrophage interactions in which local release of free cholesterol causes local actin polymerization, promoting a pathological positive feedback loop for increased catabolism of agLDL and eventual foam cell formation. (Arterioscler Thromb Vasc Biol.2009;29:1615-1621.)
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