Hilmi, A. J. S.; Manning, S. A.; Dent, L. G.; Mitchell, K. A.; Harvey, K. F.

During animal development, cells acquire specialised fates in a precise spatiotemporal order, which is essential for producing tissues that function appropriately. Cell fate specification is governed by multiple signalling pathways, as well as mechanical forces, which impact cellular transcription. Two such signalling pathways are the Hippo pathway and EGFR pathway, which both control organ growth and the fate of certain cell types in multiple species. Here, we show that Hippo signalling is essential for the maintenance of the cone and primary pigment cell fates in the developing Drosophila eye. When Hippo signalling is compromised, its nuclear effectors Yorkie and Scalloped drive increased expression of the EGFR pathway transcription repressor Yan, which antagonises the cone and primary pigment cell fates. Thus, in addition to its role as a growth suppressor, Hippo signalling promotes the fate of multiple eye cells by maintaining their responsiveness to inductive cues from the EGFR pathway.