Hippo signaling regulates dorsoventral patterning in Drosophila head and eye development.

The integration of growth and patterning is essential for proper tissue development. In Drosophila, the Hippo pathway controls organ size, including formation of adult structures from the eye-antennal imaginal disc. Defective Proventriculus (Dve), a K-50 domain transcription factor, regulates dorsal-ventral patterning by suppressing eye fate and promoting head cuticle development, thereby influencing eye position and interocular distance. We investigated how the Hippo effector Yorkie (Yki) and Dve coordinate growth and patterning in the dorsal head region. Our results show that Yki regulates dorsal head size, while Dve suppresses Yki in this region. Yki also controls dorsal-ventral patterning genes, including pnr, wg, and mirr, to coordinate eye and head development. Because mammalian orthologs of yki, dve, pnr, and wg are linked to developmental disorders such as facial dysmorphia, our findings reveal conserved mechanisms connecting growth, patterning, and craniofacial development across species, with potential relevance to human developmental disease and tissue morphogenesis.