PKC
controls the traffic of ß1 integrins in motile cells
Johanna Ivaska,
Richard D.H. Whelan,
Rose Watson1, and
Peter J. Parker2
Protein Phosphorylation Laboratory and 1 Electron Microscopy Unit, Cancer Research UK London Institute, Lincoln’s Inn Fields Laboratories, 44 Lincoln’s Inn Fields, London WC2A 3PX, UK 2 Corresponding author e-mail: peter.parker{at}cancer.org.uk
Abstract:
Protein kinase C (PKC) has been implicated in ß1 integrin-mediated cell migration. Expression of the novel PKC isoform, PKC
, in PKC–/– cells is shown here to stimulate directional migration of cells towards ß1 integrin substrates in a manner dependent on PKC catalytic activity. On PKC inhibition, integrin ß1 and PKC 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 and integrin ß1 on the vesicular membranes. Finally, using a reconstituted in vitro system, the dissociation of PKC 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 controls an internal traffic step that under uninhibited conditions permits the recycling of ß1 integrin, contributing to cell motility.
Key Words: Keywords: integrin/migration/protein kinaseC/trafficking
