Selective block of tunneling nanotube (TNT) formation inhibits intercellular organelle transfer between PC12 cells.

Organelle exchange between cells via tunneling nanotubes (TNTs) is a recently described form of intercellular communication. Here, we show that the selective elimination of filopodia from PC12 cells by 350 nM cytochalasin B (CytoB) blocks TNT formation but has only a weak effect on the stability of existing TNTs. Under these conditions the intercellular organelle transfer was strongly reduced, whereas endocytosis and phagocytosis were not affected. Furthermore, the transfer of organelles significantly correlated with the presence of a TNT-bridge. Thus, our data support that in PC12 cells filopodia-like protrusions are the principal precursors of TNTs and CytoB provides a valuable tool to selectively interfere with TNT-mediated cell-to-cell communication.