Gone with the Wnts.... The Wnt Signaling Pathway in Pleurobrachia bachei

Abstract

Wnt signaling is known to be critical for proper embryonic development in most animals studied to date15. But key evolutionary questions on the origin and evolution of this pathway in the metazoan common ancestor are still unresolved. Recently, the genome of Pleurobrachia bachei, a member of the early branching metazoan linage ctenophora, has been sequenced. Insights into the function of the Wnt pathway in P. bachei will provide information on early evolution of this key pathway. Three Wnt ligand genes were identified in P. bachei and cloned for in situ hybridization. These genes showed expression in the combs, tentacles, mouth, ciliated grooves and polar fields of the adult P. bachei. In a genomic search for other members of the canonical Wnt pathway, components of the destruction complex and antagonists were incomplete or missing from the genome. Wnt expression in the adult P. bachei indicates that Wnt could also be playing a role in neurotransmission in the adult.