Autophagy is dispensable in germline stem cells but is required in the cap cells for their maintenance in the Drosophila ovarian niche

Autophagy is a cytoprotective mechanism responsible for the maintenance and long-term survival of various cell types, including stem cells. However, its role in the germline stem cell (GSC) niche remains unexplored. We demonstrate that autophagy flux in female Drosophila GSCs is low and dependent on the core autophagy gene, Atg5. However, the maintenance of Atg5-/- GSCs within the GSC niche was unaffected even under nutrient stress. In contrast, disruption of autophagy within the cap cells (niche cells) leads to the loss of both cap cells and GSCs during aging. Further, reduced autophagy in cap cells severely impairs the crucial GSC self-renewal signal mediated by BMP-pMad emanating from the cap cells at the onset of midlife. Autophagy was essential for the long-term survival of cap cells. Our study reveals a differential role for autophagy, which is dispensable in GSCs but necessary in niche cells, where it supports signaling and survival to maintain GSCs.