Microtubules cut loose at the cell cortex

The ability of the microtubule cytoskeleton to rapidly and locally reorganize itself in response to intraand extracellular signals is essential to its wide range of functions. A site of tightly regulated microtubule dynamics-and the major interface between the microtubule cytoskeleton and the extracellular environment-is the cell cortex, where the selective stabilization and destabilization of microtubule plus-ends is required for normal cell division, morphogenesis and migration. In a recent study, we found that the cortex of Drosophila S2 and D17 cells is coated with the microtubule severing enzyme and plus-end depolymerase, Kat-60, which actively suppresses microtubule growth and stability along the cell edge. We have proposed that cortical Kat-60 functions by uncapping plus-ends, thereby activating another microtubule depolymerase, KLP10A, preloaded onto the end. The localized destruction of microtubule plusends at a specific cortical could feed into larger regulatory pathways, such as those in control of the actin cytoskeleton, to influence cell polarization and motility.