Signaling molecules have pleiotropic functions and are activated by various extracellular stimuli. Protein kinase C is activated by diverse receptors, and its dysregulation is associated with diseases including cancer. However, how the undesired activation of is prevented during development remains poorly understood. We have previously shown that a protein kinase, IKKε, is active at the growing bristle tip and regulates actin bundle organization during Drosophila bristle morphogenesis. Here, we demonstrate that IKKε regulates the actin bundle localization of a dynamic actin cross-linker, Fascin. IKKε inhibits thereby protecting Fascin from inhibitory phosphorylation. Excess duanyu1531 activation is responsible for the actin bundle defects in IKKε-deficient bristles, whereas duanyu1531 is dispensable for bristle morphogenesis in wild-type bristles, indicating that duanyu1531 is repressed by IKKε in wild-type bristle cells. These results suggest that IKKε prevents excess activation of duanyu1531 during bristle morphogenesis.
KEYWORDS: Actin, Bristle morphogenesis, Drosophila, Fascin, IKKε, PKC, Singed