Caveolae and caveolin-1 mediate endocytosis and transcytosis of oxidized low density lipoprotein in endothelial cells.
OBJECTIVE
To explore the mechanisms involved in ox-LDL transcytosis across endothelial cells and the role of caveolae in this process.


METHODS
An in vitro model was established to investigate the passage of oxidized low density lipoprotein (ox-LDL) through a tight monolayer of human umbilical vein endothelial cells (HUVEC) cultured on a collagen-coated filter. Passage of DiI-labeled ox-LDL through the monolayer was measured using a fluorescence spectrophotometer. The uptake and efflux of ox-LDL by HUVEC were determined using fluorescence microscopy and HPLC.


RESULTS
Caveolae inhibitors - carrageenan (250 μg/mL), filipin (5 μg/mL), and nocodazole (33 μmol/L)-decreased the transport of ox-LDL across the monolayer by 48.9%, 72.4%, and 79.8% as compared to the control group. In addition, they effectively decreased ox-LDL uptake and inhibited the efflux of ox-LDL. Caveolin-1 and LOX-1 were up-regulated by ox-LDL in a time-dependent manner and decreased gradually after depletion of ox-LDL (P<0.05). After treatment HUVEC with ox-LDL and silencing caveolin-1, NF-κB translocation to the nucleus was blocked and LOX-1 expression decreased (P<0.05).


CONCLUSIONS
Caveolae can be a carrier for ox-LDL and may be involved in the uptake and transcytosis of ox-LDL by HUVEC.
Sun
Shao-wei
SW
Institute of Pharmacy and Pharmacology, University of South China, Hengyang, China.
Zu
Xu-yu
XY
Tuo
Qin-hui
QH
Chen
Lin-xi
LX
Lei
Xiao-yong
XY
Li
Kai
K
Tang
Chao-ke
CK
Liao
Duan-fang
DF
D021941:Caveolae / Q000378:metabolism*; D051242:Caveolin 1 / Q000378:metabolism*; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004705:Endocytosis; D042783:Endothelial Cells / Q000378:metabolism*; D006801:Humans; D008077:Lipoproteins, LDL / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D051127:Scavenger Receptors, Class E / Q000096:biosynthesis; D013050:Spectrometry, Fluorescence; D057900:Transcytosis; D014471:Umbilical Veins / Q000378:metabolism*
D051242:Caveolin 1; D008077:Lipoproteins, LDL; C495137:OLR1 protein, human; D051127:Scavenger Receptors, Class E; C099252:oxidized low density lipoprotein