skittles, a Drosophila phosphatidylinositol 4-phosphate 5-kinase, is required for cell viability, germline development and bristle morphology, but not for neurotransmitter release

The phosphatidylinositol pathway is implicated in the regulation of numerou s cellular functions and responses to extracellular signals. An important b ranching point in the pathway is the phosphorylation of phosphatidylinosito l 4-phosphate by the phosphatidylinositol 4-phosphate 5-kinase (PIP5K) to g enerate the second messenger phosphatidylinositol 4,5-bis-phosphate (PIP2). PIP5K and PIP2 have been implicated in signal transduction, cytoskeletal r egulation, DNA synthesis, and vesicular trafficking. We have cloned and gen erated mutations in a Drosophila PIP5K type I (skittles). Our analysis indi cates that skittles is required for cell viability, germline development, a nd the proper structural development of sensory bristles. Surprisingly, we found no evidence for PIP5KI involvement in neural secretion.