Figure 1: TNTs connect neighboring epithelial cells.
From: Influenza virus exploits tunneling nanotubes for cell-to-cell spread
(a and b) TNT connecting neighboring A549 cells in a non-confluent monolayer (a) or a confluent monolayer (b) as imaged using the method of expansion microscopy. Lower panels show a higher magnification of the TNT at the cellular ends of the TNT shown in the upper panel. The scale bar corresponds to 10 μm. For both panels a and b, samples were chemically fixed, infused with polyelectrolyte gel, followed by dialysis in water, and image captured with a Zeiss confocal microscope equipped with a 100x/1.4 NA oil objective. (c) Ultra structure of TNTs. Scanning electron microscopy (SEM) shows the ultrastructure of a TNT between two A549 cells. Scale bar corresponds to 6.6 μm. (d) A TEM section of A549 cells cultured for 4 h after seeding, indicates the presence of TNTs connecting neighboring A549 cells. (e) Selected frames of a video sequence showing the dynamic and transient nature of TNTs connecting two A549 cells. Arrowhead highlights a TNT connecting two cells that bursts 45 sec after exposure to high laser power. (f) Mitochondria transfer via TNTs connecting two A549 cells. A549 cells were stained with Mitotracker Green or Mitotracker Red, mixed 1:1, and co-incubated for an additional 4 hrs before imaging. Green arrowheads highlight a red-stained mitochondria in cells stained with Mitotracker Green and red arrowheads highlight a green-stained mitochondria in cell stained with Mitotracker Red.
