Rhes promotes cell–cell transportation of mHTT via Rhes tunnels. (A–D) Representative confocal images of GFP-Rhes in striatal cells (STHdh^Q7/Q7) or mutant striatal cells (STHdh^Q111/Q111) with immunocytochemistry for endogenous (endo) normal full-length (FL) HTT (A) or endogenous FL mutant HTT with anti-HTT MAB2166 antibody (B). WT striatal cells expressing GFP-Rhes and mCherry-tagged N-terminal nonpathogenic HTT fragment (N171-18Q; C), or N-terminal pathogenic HTT fragment (N171-89Q; D). Arrows indicate TNT-like Rhes tunnels, and arrowheads indicate the colocalization of mHTT/HTT in the Rhes tunnel. (E) Confocal time-lapse image (∼7 min) of striatal cells coexpressing GFP-Rhes and mCherry mHTT (N171-89Q). Arrows point to TNT-like Rhes tunnel connecting cell 1 and cell 2. Arrowheads in inset point to the movement of mHTT vesicle in the Rhes tunnel. See related Video 7. (F) Confocal time-lapse image (∼160 s) of striatal cells coexpressing GFP-Rhes and mCherry mHTT (N171-89Q). Blue arrow points to TNT-like Rhes tunnel connecting cell 1 and cell 2. Inset f1 points to the delivery of leading Rhes and mHTT puncta (arrow) and just approaching Rhes and mHTT vesicular puncta (arrowhead) into the acceptor cells. Inset f2 shows 3D rendering of the time-lapse image of F. Arrowhead points to the just approaching Rhes and mHTT puncta, yellow arrow indicates the leading Rhes and mHTT puncta, and red arrow indicates the retracting Rhes tunnel.