Diversin regulates heart formation and gastrulation movements in development

Canonical and noncanonical Writ signaling regulate crucial events in the development of vertebrates and invertebrates. In this work we show that vertebrate Diversin, a potential orthologue of Drosophila Diego, controls fusion of heart precursors and gastrulation movements in zebrafish embryogenesis. These events are regulated by noncanonical Writ signaling, which is independent of beta-catenin. We found that Diversin directly interacts with Dishevelled and that this interaction is necessary and sufficient to mediate signals of the noncanonical Writ pathway to downstream effectors like Rho family GTPases and Jun N-terminal kinase. The ankyrin repeats of Diversin are required for the interaction with Dishevelled, for the activation of noncanonical Writ signaling, and for the biological responses. The mutation K446M in the DEP domain of vertebrate Dishevelled, which mimics a classical Drosophila loss of function mutation, prevents functional interaction with Diversin's ankyrin repeats. Diversin also affects planar cell polarity in Drosophila, which is controlled by the noncanonical Writ signaling pathway. Our data thus demonstrate that Diversin and Dishevelled function together in a mutually dependent fashion in zebrafish gastrulation and organ formation.