posted on 2021-03-17, 10:05authored byLi Xia, Li-Juan Zhang, Hong-Wu Tang, Dai-Wen Pang
Microtubules (MTs) are the main component
of cytoskeletons, providing
long tracks for cargo trafficking across the cytoplasm. In the past
years, transport along MTs was frequently reported to be rapid directed
motions with speeds of several micrometers per second, but is that
all the truth? Using single-particle tracking, we roundly and precisely
analyzed the dynamic behaviors of three kinds of cargoes transported
along MTs in two types of cells. It was found that during the transport
processes, the directed motions of the cargoes were frequently interrupted
by nondirected motions which greatly reduced the translocation rate
toward the nucleus. What is more, in addition to the widely reported
rapid directed motions, a type of directed motions with most speeds
below 0.5 μm/s occurred more frequently. On the whole, these
slow directed motions took longer than the rapid directed motions
and resulted in displacements same as those of the rapid ones. To
sum up, while travelling along MTs toward the cell interior, endocytosed
cargoes moved alternately in rapid-directed, slow-directed and nondirected
modes. In this process, the rapid- and the slow-directed motions contributed
almost equally to the cargoes’ translocation. This work provides
original insights into the transport on MTs, facilitating a more comprehensive
understanding of intracellular trafficking.