Long, delicate tubules are a new trade route for the intercellular exchange of goods, as shown by Amin Rustom, Hans-Hermann Gerdes (University of Heidelberg, Germany), and colleagues.
Rustom noticed these actin-rich extensions, which the group calls tunneling nanotubes (TNTs), while looking for secretory granules near the plasma membrane. The membrane dye that he used revealed long thin tubes, up to several cell diameters long but only ∼100 nm wide, linking some of the plated cells. “They are extremely sensitive,” says Gerdes. “Even light exposure disrupts them. Maybe because of [this sensitivity], this is the first time we realized these unique structures are there.” The group has seen the connectors in kidney and neurosecretory cell lines and primary neuroendocrine cultures, but other cell types could be similarly linked.
The TNTs are made when filopodia contact a distant cell. Once it becomes contiguous with the new partner,...
