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

Figure 6

Chronic inhibition of ITSN-1s expression augments the activation of alternative endocytic/transcytotic pathways. (a–e) Representative EM images of membranous rings with diameters between 100 nm to 400 nm, (a, c), free in the cytosol or open to the lumen and tubules (b, d, e), some of them branching or discharging tracer in the perivascular space, (b, boxed structure, and inset), and enlarged endocytic structures, many of them fused with typical caveolae (a). Note the tubular structures are connected to the plasma membrane and displaying at their cytosolic termini caveolae (b1) or coated vesicles (e, arrowhead). Bars: 100 nm (b, c, d); 250 nm (a); 75 nm (e); (f) membrane ruffles (f, arrow, insets f.1, f.2) and large macropinocytic vesicles (mpv1, mpv2) labeled by tracer particles. Bar: 150 nm.