Germline protein, Cup, non-cell autonomously limits migratory cell fate in Drosophila oogenesis

Attaining migratory fate from a stationary cell population is complex and indispensable both for the multicellular organism development as well for the pathological condition like tumor metastasis. Though widely prevalent in the metazoans, the molecular understanding of this phenomenon remains elusive. Specification of migratory border cells from the follicular epithelium during Drosophila oogenesis has emerged as one of the excellent model systems to study how motile cell are specified. JAK-STAT activation in 6-10 anterior most follicle cells of the Drosophila egg chamber transforms them to a migratory cluster called the border cells. We show that a nurse cell protein, Cup, non-cell autonomously restricts the domain of JAK-STAT activation in the anterior follicle cells. Further examination suggests that Cup functions through Rab11GTPase to regulate Delta trafficking in the nurse cells potentiating Notch activation in the anterior follicle cells. Since Notch activity in the follicle cells modulates the JAK-STAT, any perturbation in Notch activation affects the border cell fate. Altogether, we propose that germline Cup affects the border cell fate through appropriate activation of Notch and JAK-STAT signaling in the follicle cells.