A Decline in Follicle Cell Function Is a Major Driver of <i>Drosophila</i> Ovarian Aging

The ovary is one of the first organs to lose functionality with age. We found that aging of the Drosophila ovary is characterized by an accumulation of phenotypes in the somatic compartment, including failure of the follicle cells to encapsulate germ-cell cysts, an extended S phase, and increased DNA damage. In aged ovaries, follicle encapsulation defects are associated with the lack of a germ-cell cyst checkpoint in early oogenesis. Single-cell RNA sequencing revealed that, across all cell types in the ovary, cells in the follicle lineage have the highest number of differentially expressed genes. Overexpression of Atg8a, a key autophagy machinery gene homologous to mammalian LC3, specifically in follicle cells prevents age-associated decline in the follicle epithelium and loss of reproductive capacity. Collectively, these findings demonstrate that genetic manipulation of a small population of ovarian somatic cells is sufficient to improve both cell-autonomous and non-autonomous features of reproductive aging.