Crossroads of Wnt and Hippo in epithelial tissues

• Wnt controls the reciprocal interaction between epithelial and mesenchymal tissue during tubulogenesis.
• Hippo orchestrates proliferation and apoptosis to control organ size.
• Essential crosstalk between Hippo and Wnt occurs during epithelial transcriptional control.
• Epithelial cell junctions sequester the transcription factors β-catenin and Yap/Taz.

Epithelial tissues undergo constant growth and differentiation during embryonic development and to replace damaged tissue in adult organs. These processes are governed by different signaling pathways that ultimately control the expression of genes associated with cell proliferation, patterning, and death. One essential pathway is Wnt, which controls tubulogenesis in several epithelial organs. Recently, Wnt has been closely linked to other signaling pathways, such as Hippo, that orchestrate proliferation and apoptosis to control organ size. There is evidence that epithelial cell junctions may sequester the transcription factors that act downstream of these signaling pathways, which would represent an important aspect of their functional regulation and their influence on cell behavior. Here, we review the transcriptional control exerted by the Wnt and Hippo signaling pathways during epithelial growth, patterning, and differentiation and recent advances in understanding of the regulation and crosstalk of these pathways in epithelial tissues.