Signal transduction pathways regulating Drosophila ovarian germline stem cells

Drosophila female germline stem cells (GSCs) serve as one of the best understood stem cell types. GSCs reside in a special microenvironment, the stem cell niche, and their activity is tightly regulated by niche-derived signals. In addition to the stemness-promoting signaling molecules, the niche also generates other signaling molecules that regulate GSC differentiation. Recent studies are beginning to appreciate the intricate interactions among these signaling molecules in the niche and their effects on GSC behaviour. This review summarizes recent advances to demonstrate how the niche functions as a signaling hub to integrate these niche-derived local signals as well as other organ-produced systemic signals to control GSC self-renewal and differentiation.