Drosophila filamin is required for follicle cell motility during oogenesis.

The Filamin family of actin binding proteins is required to maintain cell shape and promote cell locomotion. Using the Drosophila ovary, we provide a detailed description of Filamin-deficient cells during morphogenesis. Reduced expression of Filamin in follicle cells causes defects in the initial encapsulation of germline cysts and in the migration of border cells through the germline cyst. However, follicle cell morphogenesis is unaffected by point mutations that produce truncated Filamin proteins. In addition, mutant follicle cell movements can be partially rescued by a transgene encoding only the actin-binding domain and the first six filamin repeats. These data show that Filamin function in cell motility can be provided by a truncated Filamin protein that resembles Dictyostelium Actin Binding Protein-120.