Original Article

Caveolae and caveolin-1 mediate endocytosis and transcytosis of oxidized low density lipoprotein in endothelial cells

Shao-wei Sun, Xu-yu Zu, Qin-hui Tuo, Lin-xi Chen, Xiao-yong Lei, Kai Li, Chao-ke Tang, Duan-fang Liao
DOI: 10.1038/aps.2010.87


Aim: 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).
Conclusion: Caveolae can be a carrier for ox-LDL and may be involved in the uptake and transcytosis of ox-LDL by HUVEC.

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