Polished Rice Regulates Maturation but Not Survival of Secondary Cells in Drosophila Male Accessory Gland

In Drosophila males, the accessory gland is responsive to nutrient signal-dependent regulation of fertility/fecundity. The accessory gland is composed of two types of binucleated epithelial cells, about 1000 main cells and 60 secondary cells (SCs). The transcription factors Defective proventriculus (Dve), Abdominal-B, and Ecdysone receptors (EcRs) are strongly expressed in adult SCs. In response to nutrient conditions during development, coordinated action between Dve and ecdysone signaling determines the optimal number of SCs and regulates their maturation. A downstream effector of ecdysone signaling, Ftz-F1, is crucial in this process. Another downstream effector, Polished rice (Pri), is small peptides of 11 or 32 amino acids. Here we show that pri is required for maturation of SCs and for male fecundity, whereas it is not involved in determination of the number of SCs. We provide evidence that Pri acts downstream of Ftz-F1 to regulate maturation but not survival of SCs.