Phase Separation Mediates Short-Distance Vesicle Transport in Cells
WU Xiandeng1, QIU Hua1, ZHANG Mingjie2*
Cellular vesicles are moved via two distinct routes: the canonical motor-powered transport, which moves along cytoskeletons typically over long distances, and local and short-distance transport. The short-distance transport is also with directions but does not involve molecular motors and cytoskeletons. The molecular mechanisms underlying short-distance vesicle transport are totally unknown. Using SV (synaptic vesicle) transport as a paradigm, this study discovers a new way of short-distance vesicle transport mediated by phase separation in a Ca2+-regulated and directional manner. Specifically, a scaffold called Pclo (Piccolo) in the presynaptic bouton undergoes phase separation with SV. On the one hand, Pclo can extract SVs from the reserve pool, on the other hand, Pclo can facilitate SV tethering on the active zone. In addition, this study further finds a protein called TFG (Trk-fused gene) can facilitate COPII (coat protein complex II) vesicles transport from ER (endoplasmic reticulum) to the ERGIC (ER-Golgi intermediate compartment) via phase separation. Therefore, phase separation may be a general mechanism for short-distance vesicle transport in cells.
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