Figure 1.

Ostreolysin marks the presence of cholesterol-sphingomyelin membrane nanodomains along intercellular membrane nanotubes in T24 cells. The labeling of actin filaments highlights the location of intercellular membrane nanotubes (see close up) between T24 (malignant) cells of urothelial origin grown in lipoprotein poor serum medium (A). The addition of ostreolysin reveals specific binding to cholesterol-sphingomyelin membrane nanodomains along the cell surface and along the intercellular membrane nanotubes (B). The growth of T24 cells in lipoprotein poor serum medium treated with 1 mM methyl-β-cyclodextrin for 2-hour causes the formation of actin stress fibers (C) as well as the dispersion of cholesterol-sphingomyelin membrane nanodomains (D). Note that the intercellular membrane nanotubes are still present following the application of methyl-β-cyclodextrin in low concentration (1 mM) (C), and that ostreolysin labeling on the cell surface is much reduced (D).

Abbreviations: LPPS, lipoprotein poor serum; mβCD, methyl-β-cyclodextrin; Oly, ostreolysin.