Bcl9 and Pygopus (Pygo) are obligate Wnt/β-catenin cofactors in Drosophila, yet their contribution to Wnt signaling during vertebrate development remains unresolved. Combining zebrafish and mouse genetics, we document a conserved, β-catenin-associated function for BCL9 and Pygo proteins during vertebrate heart development. Disrupting the β-catenin-BCL9-Pygo complex results in a broadly maintained canonical Wnt response yet perturbs heart development and proper expression of key cardiac regulators. Our work highlights BCL9 and Pygo as selective β-catenin cofactors in a subset of canonical Wnt responses during vertebrate development. Moreover, our results implicate alterations in BCL9 and BCL9L in human congenital heart defects.
Keywords: Wnt signaling; CRISPR–Cas9; cardiovascular development; congenital heart disease; heart; transcription.
© 2018 Cantù et al.; Published by Cold Spring Harbor Laboratory Press.