Optimized methods for imaging membrane nanotubes between T cells and trafficking of HIV-1

The molecular basis of induction and formation of tunneling nanotubes

“…They have also observed that TNTs grow out of the upper area of cell surface distinct from filopodia; subsequently the TNTs reach adjacent cells and are then stabilized to adhere with the adherence junctions containing N-cadherin and β-catenin (Lokar et al, 2010;Veranič et al, 2008). On the other hand, it has been reported that an initial contact of an adequate duration is generally required for TNT formation in the case of macrophages, NK cells and T cells (Sowinski et al, 2011;Chauveau et al, 2010). TNT formation between NK cells and target cells requires interaction of an NK cell activating receptor and its ligand on the target cells (Chauveau et al, 2010).…”

Tunneling nanotubes: Emerging view of their molecular components and formation mechanisms

“…TNTs can be recognized as thin membranous structures connecting two or more cells and, importantly, these structures are not attached to the substratum (Figure 1 A to F) [6] [7]. A different sort of cytoplasmic connection is observed after cell division as a structure containing the midbody; it persists temporarily as a tether between the two 8 daughter cells, contains dense matrix material, and is visible by light microscopy.…”

“…Viruses move directionally along the outer surface of these filopodial bridges to infect neighboring cells. Their contact with substratum and dependence of their formation on envelop protein-receptor interaction are the main features that distinguish filopodial bridges from the TNTs also used by retrovirus for intracellular transfer [6][13] [24].…”

“…One is de novo protrusion from a given cell, ultimately making contact with a neighboring cell, which results in TNT formation, as seen in PC12 cells and T24 cells [7] [14]. In the other pathway, cells first come into contact and then draw out TNTs as they subsequently move apart, which is observed in many types of immune cells [6] [28]. Moreover depletion of choresterol from plasma membrane by treatments of methyl-ocyclodextrin led to significant reduction of the density of TNT in T24 cell surface [28].…”

Prion aggregates transfer through tunneling nanotubes in endocytic vesicles

“…5 TNTs are thin, actin-containing intercellular tubes, that may act as conduits that allow the passage of organelles, endocytic vesicles, protein aggregates and viruses between cells. 6,7,8,9 The mechanism by which PrP Sc transfers through TNTs has not been addressed. Because PrP is a GPI-anchored protein targeted to the outer leaflet of the plasma membrane we envision 2 possibilities by which PrP Sc could transfer though TNTs: by diffusion along the surface of the TNT, consistent with its localization to the plasma membrane or within the tube itself inside specific organelles or vesicles.…”