A targeted gene silencing technique shows that Drosophila myosin VI is required for egg chamber and imaginal disc morphogenesis

We report that Drosophila unconventional myosin VI, encoded by Myosin heavy chain at 95F (Mhc95F), is required for both imaginal disc and egg chamber morphogenesis. During oogenesis, Mhc95F is expressed in migrating follicle cells, including the border cells, which migrate between the nurse cells to lie at the anterior of the oocyte; the columnar cells that migrate over th e oocyte; the centripetal cells that migrate between the oocyte and nurse c ells; and the dorsal-anterior follicle cells, which migrate to secrete the chorionic appendages. Its function during development has been studied usin g a targeted gene silencing technique, combining the Gal4-UAS targeted expr ession system and the antisense RNA technique. Antibody staining shows that the expression of myosin 95F is greatly decreased in follicle cells when a ntisense Mhc95F RNA is expressed. Interfering with expression of Drosophila myosin VI at various developmental stages frequently results in lethality, During metamorphosis it results in adult flies with malformed legs and win gs, indicating that myosin VI is essential for imaginal disc morphogenesis. During oogenesis, abnormal follicle cell shapes and aberrant follicle cell migrations are observed when antisense Mhc95F is expressed in follicle cel ls during stages 9 to 10, suggesting that the Drosophila myosin VI is requi red for follicle cell epithelial morphogenesis.