Trends Cell Biol
Ljubojevic N, Henderson JM, Zurzolo C
Novel structures, known as tunneling nanotubes (TNTs), are membranous protrusions supported by filamentous actin that mediate continuity between remote cells by remaining open at both ends for cargo transport.
The formation of morphologically similar protrusions, such as filopodia, microvilli, and immature dendritic spines, involves the processes of initiation, elongation, and stabilization; this includes many actin and membrane regulators, such as Rho GTPases, I-BAR proteins, actin nucleators, and actin bundlers, which likely participate in TNT formation.
The unique length of TNTs implies the involvement of motor proteins able to efficiently transport the required components to the growing end, and likely a specific actin arrangement.
Specificity in TNT biogenesis may arise from differences in the ability of common actin-regulating molecules to promote TNTs versus filopodia.