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Effects of triglyceride‐rich lipoproteins and their lipolysis products on endothelial cell membrane microdomains
Author(s) -
Wang Limin,
Butti Annapoorna R,
Parikh Atul N,
Rutledge John C
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a915-c
Subject(s) - lipid raft , very low density lipoprotein , chylomicron , lipolysis , microbiology and biotechnology , chemistry , biochemistry , perilipin , caveolae , biology , cholesterol , lipoprotein , cell , adipose tissue
Elevation of triglyceride‐rich lipoproteins (TGRL) in the postprandial state is associated with increased endothelial cell inflammation and complications of atherosclerosis. Little is known of how TGRL and their products interact with endothelial cell membrane microdomains (e.g. lipid rafts) in the postprandial state. To observe the interactions of TGRL and their lipolysis products with human aortic endothelial cell (HAECs) membrane microdomains, HAECs were treated with Atto labeled TGRL only or TGRL plus lipoprotein lipase (LPL), and followed by incubation with FITC‐labeled cholera toxin B for lipid raft labeling. Images of confocal laser‐scanning microscopy revealed that fluorescent labeled chylomicrons associated with both raft and nonraft areas of the cell membrane, and had minimal cellular uptake. While fluorescent VLDL primarily associated with rafts and had significant cellular uptake. Addition of LPL to labeled VLDL caused enhanced VLDL association with rafts and increased lipid raft clustering. To investigate how VLDL lipolysis products affect the lipid rafts, rafts were isolated by density gradient and Western blotting showed that VLDL plus LPL caused decreased eNOS and caveolin‐1 proteins in lipid rafts, whereas there was an increased eNOS in detergent‐soluble membrane fractions. These results provide evidence that TGRL and their lipolysis products affect lipid rafts possibly regulating physiologically important cell signalling pathways. (Supported by NIH HL 78615)