V. Prahlad et al., RAPID MOVEMENTS OF VIMENTIN ON MICROTUBULE TRACKS - KINESIN-DEPENDENTASSEMBLY OF INTERMEDIATE FILAMENT NETWORKS, The Journal of cell biology, 143(1), 1998, pp. 159-170
The assembly and maintenance of an extended intermediate filament (TF)
network in fibroblasts requires microtubule (MT) integrity. Using a g
reen fluorescent protein-vimentin construct, and spreading BHK-21 cell
s as a model system to study IF-MT interactions, we have discovered a
novel mechanism involved in the assembly of the vimentin IF cytoskelet
on. This entails the rapid, discontinuous, and MT-dependent movement o
f IF precursors towards the peripheral regions of the cytoplasm where
they appear to assemble into short fibrils. These precursors, or vimen
tin dots, move at speeds averaging 0.55 +/- 0.24 mu m/s. The vimentin
dots colocalize with MT and their motility is inhibited after treatmen
t with nocodazole. Our studies further implicate a conventional kinesi
n in the movement of the vimentin dots. The dots colocalize with conve
ntional kinesin as shown by indirect immunofluorescence, and IF prepar
ations from spreading cells are enriched in kinesin. Furthermore, micr
oinjection of kinesin antibodies into spreading cells prevents the ass
embly of an extended IF network. These studies provide insights into t
he interactions between the IF and MI systems. They also suggest a rol
e for conventional kinesin in the distribution of non-membranous prote
in cargo, and the local regulation of LF assembly.