PKCϵ controls the traffic of β1 integrins in motile cells

Protein kinase C (PKC) has been implicated in β1 integrin‐mediated cell migration. Expression of the novel PKC isoform, PKCϵ, in PKCϵ−/− cells is shown here to stimulate directional migration of cells towards β1 integrin substrates in a manner dependent on PKC catalytic activity. On PKC inhibition, integrin β1 and PKCϵ become reversibly trapped in a tetraspanin (CD81)‐positive intracellular compartment, correlating with reduced haptotaxis. Immunofluorescence and pulse labelling studies indicate that this is a previously uncharacterized recycling compartment trapped by inhibition of PKC. Electron microscopy demonstrated the co‐localization of PKCϵ and integrin β1 on the vesicular membranes. Finally, using a reconstituted in vitro system, the dissociation of PKCϵ from these vesicles is shown to be dependent on both the presence of cytosolic components and energy, and on PKC catalytic activity. The evidence presented indicates that PKCϵ controls an internal traffic step that under uninhibited conditions permits the recycling of β1 integrin, contributing to cell motility.