PKC[epsilon] controls the traffic of [beta]1 integrins in motile cells

Protein kinase C (PKC) has been implicated in [beta]1 integrin-mediated cell migration. Expression of the novel PKC isoform, PKC[epsilon], in PKC[epsilon]-/- cells is shown here to stimulate directional migration of cells towards [beta]1 integrin substrates in a manner dependent on PKC catalytic activity. On PKC inhibition, integrin [beta]1 and PKC[epsilon] 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 PKC[epsilon] and integrin [beta]1 on the vesicular membranes. Finally, using a reconstituted in vitro system, the dissociation of PKC[epsilon] 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 PKC[epsilon] controls an internal traffic step that under uninhibited conditions permits the recycling of [beta]1 integrin, contributing to cell motility.