Dapper parting of Wnt pathways

The canonical Wnt/β-catenin and Wnt/Ca²⁺ pathways play vital, but distinct, roles in vertebrate development. The first patterns the anteroposterior (AP) axis in early development; the second, together with orthologues of the Drosophila planar cell polarity (PCP) pathway,controls gastrulation cell movements. Both act through Dishevelled (Dvl). On p. 5909, Waxman and colleagues describe how Dapper1 (Dpr1) and Dapper2 (Dpr2), zebrafish proteins that interact with Dvl, help to separate Wnt signalling pathways at Dvl. Loss-of function experiments show that endogenous Dpr1, but not Dpr2, is required for proper dorsoventral and AP patterning in zebrafish embryos with reduced Wnt8 activity, suggesting that Dpr1 enhances Wnt/β-catenin signalling in early development. Conversely, Dpr2, but not Dpr1, is required for proper gastrulation movements in embryos hypomorphic for Wnt11, indicating that Dpr2 enhances the Wnt/Ca²⁺-PCP pathway. These and other experiments indicate that Dpr1 and Dpr2 act in distinct Wnt-dependent developmental processes.