Ecdysone signaling-induced dumpless1 expression controls nurse cell dumping in Drosophila oogenesis.

Abstract

Nurse cell (NC) dumping, a process essential for oocyte development, involves the rapid cytoplasmic transfer from germline-derived NCs into the oocyte. However, its regulatory mechanism remains unclear. Here, we report that ecdysone signaling in stretch follicle cells (SFCs) regulates NC dumping through dumpless1, a ZAD-C₂H₂ zinc finger transcription factor, in Drosophila. Ecdysone induced dumpless1 expression in SFCs, and CRISPR/Cas9-mediated knockout of dumpless1 or its functional domain ZAD suppresses NC dumping. Depletion of dumpless1 upregulates integrin βPS expression in SFC plasma membrane, while reducing cortical enrichment of Rho1 signaling-dependent phosphorylated myosin light chain (p-MLC) and disrupting actin cables organization in NCs. SFC-specific overexpression of integrin βPS reduces p-MLC enrichment in the NC cortex, whereas its knockdown in SFCs of dumpless1^-/- mutants partially rescues NC dumping defect. Our findings identify dumpless1 as a critical effector of ecdysone signaling, bridging somatic-germline communication through the integrin βPS-Rho1-p-MLC axis, revealing a multicellular regulatory mechanism in Drosophila oogenesis.