Caveolae-mediated endocytosis of VE-Cad contributes to vascular hyperpermeability after LPS treatment

AIM: To observe caveolae-mediated endocytosis of vascular endothelial cadherin (VE-Cad) after lipopolysaccharide (LPS) treatment, and its role in vascular hyperpermeability. METHODS: Human vascular endothelial cell line CRL-2922 was used in the experiment. Western blot, co-immunoprecipitation and immunocytochemistry were adopted to observe the protein expression of caveolin-1 (Cav1), a main structural protein of caveolae, after LPS treatment. Caveolae-mediated endocytosis of VE-Cad after LPS treatment, and the effects of caveolae inhibitor on caveolae-mediated endocytosis of VE-Cad, the protein expression of VE-Cad and monolayer cell permeability after LPS treatment were determined. RESULTS: After LPS treatment, the protein expression of Cav1 did not show a significant change, while the phosphorylation (Tyr14) of Cav1 was significantly increased (P<0.05). No co-immunoprecipitation or co-localization of VE-Cad with Cav1 was observed in the normal control, and that was increased time-dependently after LPS treatment (P<0.05). Filipin, an inhibitor of caveolae, at concentration of 5 mg/L significantly reduced the co-immunoprecipitation of VE-Cad with Cav1 (P<0.05), increased the expression of VE-Cad (P<0.05) in the membrane, and improved the monolayer cell permeability at 4 h after LPS treatment (P<0.05). CONCLUSION: Caveolae-mediated endocytosis of VE-Cad contributes to the internalization of VE-Cad and the monolayer cell hyperpermeability after LPS treatment.