Epithelial stem cells are maintained within niches that promote self-renewal by providing signals that specify the stem cell fate. In the Drosophila ovary, epithelial follicle stem cells (FSCs) reside in niches at the anterior tip of the tissue and support continuous growth of the ovarian follicle epithelium. Here, we demonstrate that a neighboring dynamic population of stromal cells, called escort cells, are FSC niche cells. We show that escort cells produce both Wingless and Hedgehog ligands for the FSC lineage, and that Wingless signaling is specific for the FSC niche whereas Hedgehog signaling is active in both FSCs and daughter cells. In addition, we show that multiple escort cells simultaneously encapsulate germ cell cysts and contact FSCs. Thus, FSCs are maintained in a dynamic niche by a non-dedicated population of niche cells.
Author contributions
P.S.-H. conceived of, designed and performed the experiments, analyzed the data and assisted in writing the paper. T.G.N. conceived of the project, designed the experiments, analyzed the data and wrote the paper.
Funding
P.S.-H. is in the UCSF Biomedical Sciences graduate program and is supported by the California Institute for Regenerative Medicine [grant number TG2-01153]; and this work was supported by a National Institutes of Health grant [R01 GM097158] to T.G.N. Deposited in PMC for release after 12 months.
