A genome-scale in vivo RNAi analysis of epithelial development in Drosophila identifies new proliferation domains outside of the stem cell niche

Abstract

The Drosophila oogenesis system provides an excellent model to study the development of epithelial tissues. Here we report the first genome-scale in vivo RNAi screen for genes controlling epithelial development. By directly analysing cell and tissue architecture we identified 1125 genes, which we assigned to seven different functions in epithelial formation and homeostasis. We validated the significance of our screen by generating mutants for Vps60, a component of the ESCRT machinery. This analysis provided new insights into spatiotemporal control of cell proliferation in the follicular epithelium. Previous studies identified signals controlling divisions in the follicle stem cell niche. However, 99% of cell divisions occur outside of the niche and it is unclear how these divisions are controlled. Our data distinguish two new domains with differential proliferation control outside of the stem cell niche. One domain abuts the niche and is characterised by ESCRT, Notch and JAK/STAT mediated proliferation control. Adjacently, another domain is defined by loss of ESCRT impact on cell division. Thus, during development epithelial cells pass through different modes of proliferation control. The switch between these modes might reflect regressing stemness of epithelial cells over time.