Role of Scrib and Dlg in anterior-posterior patterning of the follicular epithelium during Drosophila oogenesis

We found that removal of scrib or dlg function from the follicle cells at posterior terminal of the egg chamber causes a complete loss of the PFC fate. Aberrant specification and differentiation of the PFCs in the mosaic clones can be ascribed to defects in coordinated activation of the EGFR, JAK and Notch signaling pathways in the multilayered cells. Meanwhile, the clonal analysis revealed that loss-of-function mutations in scrib/dlg at the anterior domains result in a partially penetrant phenotype of defective induction of the stretched and centripetal cell fate, whereas specification of the border cell fate can still occur in the most anterior region of the mutant clones. Further, we showed that scrib genetically interacts with dlg in regulating posterior patterning of the epithelium.In this study we provide evidence that scrib and dlg function differentially in anterior and posterior patterning of the follicular epithelium at oogenesis. Further genetic analysis indicates that scrib and dlg act in a common pathway to regulate PFC fate induction. This study may open another window for elucidating role of scrib/dlg in controlling epithelial polarity and cell proliferation during development.The follicle cell (FC) epithelium over the egg chamber in Drosophila ovary plays a pivotal role in the egg development. At oogenesis, follicular epithelial cells along the anterior-posterior (AP) axis are specified and differentiated into several distinct cell types that will subsequently either undergo a series of morphogenetic changes, or extend the germline-soma interactions [1-3]. While most of the epithelial FC subpopulations contribute to construction of the eggshell along with its specialized structures such as dorsal appendages through complex morphogenesis, the specified PFCs initiate establishment of the oocyte polarity, and determine the AP and dorsal-ventral (DV) axes of the resulting embryos. Thus, patterning of the follicular epithelium is an essential step for the