PKD1/PKCμ promotes αvβ3 integrin recycling and delivery to nascent focal adhesions

To identify kinases that regulate integrin recycling, we have immunoprecipitated αvβ3 integrin from NIH 3T3 fibroblasts in the presence and absence of primaquine (a drug that inhibits receptor recycling and leads to accumulation of integrins in endosomes) and screened for co-precipitating kinases. Primaquine strongly promoted association of αvβ3 integrin with PKD1, and fluorescence microscopy indicated that integrin and PKD1 associate at a vesicular compartment that is downstream of a Rab4-dependent transport step. PKD1 association was mediated by the C-terminal region of the β3 integrin cytodomain, and mutants of β3 that were unable to recruit PKD1 did not recycle in a PDGF-dependent fashion. Furthermore, suppression of endogenous PKD1 levels by RNAi, or over-expression of catalytically inactive PKD1 inhibited PDGF-dependent recycling of αvβ3 from early endosomes to the plasma membrane and blocked recruitment of αvβ3 to newly formed focal adhesions during cell spreading. These data indicate that PKDl influences cell migration by directing vesicular transport of the αvβ3 integrin heterodimer.