Phosphatidylinositol 4-kinase III beta regulates cell shape, migration and focal adhesion number.

Cell shape is regulated by adhesion and by cytoskeletal and membrane proteins. Cell shape, adhesion and motility have a complex relationship and understanding them is important in understanding developmental patterning and diseases such as cancer. Here we show that the lipid kinase phosphatidylinositol 4-kinase III beta (PI4KIIIβ) regulates cell shape, migration and Focal Adhesion number. PI4KIIIβ generates phosphatidylinositol 4-phosphate from phosphatidylinositol and is highly expressed in a subset of human breast cancers. PI4KIIIβ and the PI4P it generates regulate a range of cellular functions, among them Golgi structure, fly fertility and Akt signaling. Here we show that loss of PI4KIIIβ expression decreases cell migration and alters cell shape in NIH3T3 fibroblasts. The changes are accompanied by an increase in the number of Focal Adhesions in cells lacking PI4KIIIβ. Furthermore, we find that PI4P-containing vesicles move to the migratory leading-edge during migration and that some of these vesicles tether to and fuse with FA. This suggests a novel regulatory role for PI4KIIIβ in cell adhesion and cell shape maintenance.