The universal mechanism of intermediate filament transport

ABSTRACT Intermediate filaments (IFs) are a major component of the cytoskeleton that regulates a wide range of physiological properties in eukaryotic cells. In motile cells, the IF network has to adapt to constant changes of cell shape and tension. In this study, we used two cell lines that express vimentin and keratins 8/18 to study the dynamic behavior of these IFs. We demonstrated that both IF types undergo extensive transport along microtubules. This was an unexpected result as keratin filament remodeling has been described to depend on actin dynamics. We established the role of kinesin-1 in vimentin and keratin IF transport by knocking out KIF5B, the ubiquitous isoform of kinesin-1. Futhermore, we demonstrated that unlike typical membrane cargoes, transport of both types of IFs does not involve kinesin light chains, but requires the presence of the same region of the kinesin-1 tail, suggesting a unified mechanism of IF transport.