Impaired Caveolae Function and Upregulation of Alternative Endocytic Pathways Induced by Experimental Modulation of Intersectin-1s Expression in Mouse Lung Endothelium

Figure 3

Increased endothelial permeability and impaired interendothelial junctional integrity in mouse lung endothelium acutely depleted of ITSN-1s. (a) ELISA applied on mouse lung lysates of control, empty liposomes, and ITSN-1s siRNA-treated mice, (72 h alter siRNA), perfused with 10 mg/mL BSA-DNP, for 10 min. Results were obtained in 4-5 different experiments, (3 mice/experimental condition), and expressed in ng BSA-DNP/mg total protein/10 min. Bars ± SD. (b, c) EM morphology of IEJs in control (b) and ITSN-1s siRNA (c) mouse lung endothelium. Arrows in B point to the dense protein matrix of the tight junctions sealing the interendothelial space. Arrowheads in (c) point to three open IEJs. EC: endothelial cell; m: mitochondria. Bar: 150 nm. (d, e) Representative electron micrographs showing open IEJs labeled throughout their length by 8 nm Au-BSA particles. Arrows in (d) and magnified d1, point to three-four Au-BSA particles located close to each other in the same plan, indicative of the wide opening of the IEJ. Gold particles are also associated with the abluminal exit of IEJs. Note also the limited number of caveolae and dilation of the pericapillary space (pcs; asterisks). Bars: 200 nm (d); 100 nm (e).