PKCε-mediated phosphorylation of vimentin controls integrin recycling and motility

PKC epsilon controls the transport of endocytosed beta 1-integrins to the plasma membrane regulating directional cell motility. Vimentin, an intermediate filament protein upregulated upon epithelial cell transformation, is shown here to be a proximal PKC epsilon target within the recycling integrin compartment. On inhibition of PKC and vimentin phosphorylation, integrins become trapped in vesicles and directional cell motility towards matrix is severely attenuated. In vitro reconstitution assays showed that PKC epsilon dissociates from integrin containing endocytic vesicles in a selectively phosphorylated vimentin containing complex. Mutagenesis of PKC (controlled) sites on vimentin and ectopic expression of the variant leads to the accumulation of intracellular PKC epsilon/integrin positive vesicles. Finally, introduction of ectopic wild-type vimentin is shown to promote cell motility in a PKC epsilon-dependent manner; alanine substitutions in PKC (controlled) sites on vimentin abolishes the ability of vimentin to induce cell migration, whereas the substitution of these sites with acidic residues enables vimentin to rescue motility of PKC epsilon null cells. Our results indicate that PKC-mediated phosphorylation of vimentin is a key process in integrin traffic through the cell.