Depletion of Eggless may induce ovarian apoptosis through Dpp overexpression during early oogenesis in Drosophila.

Abstract

Fate of germline stem cell (GSC) is determined by precise and exquisite balance between self-renewal and differentiation. In Drosophila ovarian niche, Decapentaplegic (Dpp) plays an essential role in GSC self-renewal and proliferation by suppressing the transcription of differentiation factor bag of marbles (bam). Despite its role in maintaining GSC population, recent studies have revealed that excessive Dpp activity triggers apoptosis in certain developmental contexts. In this study, I show that inordinate dpp expression exacerbate defects in ovarian development by inducing apoptosis in eggless mutants. Mutant females lacking Eggless function exhibited early oogenesis arrest, which led to ovary degeneration. Overall expression of apoptotic genes was increased in eggless mutant ovary. Interestingly, expression of key BMP signaling factor dpp was also drastically increased in the mutant ovary. Moreover, in ovarian somatic cells (OSCs), dpp overexpression stimulated expression of a pro-apoptotic gene reaper and reduced the cell viability. These results suggest that aberrant dpp activation is partly responsible for oogenesis arrest by promoting apoptosis in eggless mutant ovary, which leads to defective ovary development.