Fig. 1

Bortezomib (BTZ) increases endothelial cell permeability by inducing actin stress fiber to disrupt cell–cell adhesions. (A) Endothelial cell permeability was assessed using a Transwell permeability assay with FITC-labeled dextran. HUVECs grown on Transwell filters were exposed to either vehicle or BTZ at a concentration of 100 nM for 6 h. Endothelial cell permeability was expressed as a fold increase compared to vehicle-treated cells. Data are means ± s.d. (n = 9). (B) HUVECs plated on collagen-coated dishes were treated with vehicle or varying concentrations of BTZ (10, 30, 100, and 300 nM) for 6 h, immunostained with anti-VE-cadherin and anti-vinculin antibodies, and then stained with rhodamine–phalloidin. Representative fluorescence images of F-actin (left panels, red), VE-cadherin (left middle panels, green), and vinculin (right middle panels, white) and their merged images (right panels) are shown at the top. The boxed regions are magnified on the right side. Scale bars, 200 μm. (C, D) The number of actin stress fibers (C) and vinculin-labeled focal adhesions (D), as observed in A, were quantified as described in the Materials and Methods. Data are means ± s.d (n = 9), expressed as fold increases compared to the vehicle-treated cells. In A, C, and D, *, p < 0.05; **, p < 0.01; ***, p < 0.001