A ROLE FOR THE DROSOPHILA SEGMENT POLARITY GENE ARMADILLO IN CELL-ADHESION AND CYTOSKELETAL INTEGRITY DURING OOGENESIS

The epithelial sheet is a structural unit common to many tissues. Its organization appears to depend on the function of the multi-protein co mplexes that form adherens junctions. Elegant cell biological experime nts have provided support for hypotheses explaining the function of ad herens junctions and of their components. These systems, however, lack the ability to test function within an entire organism during develop ment. The realization that the product of the Drosophila segment polar ity gene armadillo is related to the vertebrate adhesive junction comp onents plakoglobin and beta-catenin led to the suggestion that armadil lo might provide a genetic handle to study adhesive junction structure and function. An examination of the potential function of Armadillo i n cell-cell adhesive junctions was initiated using the Drosophila ovar y as the model system. We examined the distribution of Armadillo in th e Drosophila ovary and demonstrated that this localization often paral lels the location or cell-cell adhesive junctions. The consequences of removing armadillo function from the germ-line cells of the ovary wer e also examined. Germ-line armadillo mutations appear to disrupt proce sses requiring cell adhesion and integrity of the actin cytoskeleton, consistent with a role for Armadillo in cell-cell adhesive junctions. We have also used armadillo mutations to examine the effects on ovaria n development of altering the stereotyped cell arrangements of the ova ry. The implications of these results for the role of adhesive junctio ns during development are discussed.