Tunneling Nanotubes: Membranous Channels between Animal Cells
Hans-Hermann Gerdes and Amin Rustom
Intercellular communication is a major requirement for the development and maintainance of
multicellular organisms. Diverse mechanisms for the exchange of signals between cells during
evolution have been established. These mechanisms include intercellular membrane channels between plant cells, called plasmodesmata, and proteinaceous channels of animal cells, called gap junctions. Recently, highly sensitive nanotubular structures have been described which are formed de novo between animal cells resulting in the formation of complex cellular networks. These membrane channels mediate membrane continuity between connected cells and are referred to as tunneling nanotubes (TNTs). They have been shown to facilitate the intercellular transfer of organelles as well as, on a limited scale, of membrane components and cytoplasmic molecules. It has been proposed that TNTs represent a novel and general biological principle of cell interaction based on membrane continuity and the intercellular exchange of organelles. It is increasingly apparent that TNTs and TNT-related structures fulfill important functions in the physiological processes of multicellular organisms.