The retromer subunit Vps26 mediates Notch signaling during Drosophila oogenesis.

During endocytosis, molecules are internalized by the cell through the invagination of the plasma membrane. Endocytosis is required for proper cell function and for normal development in Drosophila. One component of the endocytic pathway is the retromer complex, which recycles transmembrane proteins to other parts of the cell such as the plasma membrane and the trans-Golgi network. Previous studies have shown that mutations to the retromer complex result in developmental defects in Drosophila. In humans, retromer dysfunction has been implicated in Alzheimer's and Parkinson's disease, but little is known about the role of the retromer complex in Drosophila oogenesis. In the current project, we examined the role of the retromer protein Vps26 in oogenesis by characterizing the phenotype of vps26 germline clones. Immunofluorescence was used to visualize the expression of membrane proteins and vesicular trafficking markers in mutant egg chambers. We find that vps26 germline clones exhibit a signaling defect between the germline cells and follicle cells indicated by an increase in LysoTracker staining of the border cells in the mutants. We show that this signaling defect in vps26 mutants may be the result of impaired Notch signaling based on the misexpression of multiple proteins in the Notch signaling pathway in vps26 mutants.