PDK1 regulates focal adhesion disassembly through modulation of αvβ3 integrin endocytosis

Non-amoeboid cell migration is characterised by dynamic competition among multiple protrusions to establish new adhesion sites at the cell's leading edge. However, the mechanisms that regulate the decision to disassemble or to grow nascent adhesions are not fully understood. Here we show that, in endothelial cells, 3-phosphoinositide-dependent protein kinase 1 (PDK1) promotes focal adhesion (FA) turnover by controlling endocytosis of integrin αvβ3 in a PI3K-dependent manner. We demonstrate that PDK1 binds and phosphorylates integrin αvβ3. Downregulation of PDK1 increases FA size and slows down their disassembly. This process requires both PDK1 kinase activity and PI3K activation but does not involve Akt. Moreover, PDK1 silencing stabilises FA in membrane protrusions decreasing migration of endothelial cells on vitronectin. These results indicate that modulation of integrin endocytosis by PDK1 hampers endothelial cell adhesion and migration on extracellular matrix, thus unveiling a novel role for this kinase.