The Wnt/Ca2+ pathway - a new vertebrate Wnt signaling pathway takes shape

Members of the vertebrate Wnt family have been subdivided into two function al classes according to their biological activities. Some Wnts signal throu gh the canonical Wnt-1/wingless pathway by stabilizing cytoplasmic beta-cat enin. By contrast other Wnts stimulate intracellular Ca2+ release and activ ate two kinases, CamKII and PKC, in a G-protein-dependent manner. Moreover, putative Wnt receptors belonging to the Frizzled gene family have been ide ntified that preferentially couple to the two prospective pathways in the a bsence of ectopic Wnt ligand and that might account for the signaling speci ficity of the Wnt pathways. As Ca2+ release was the first described feature of the noncanonical pathway, and as Ca2+ probably plays a key role in the activation of CamKII and PKC, we have named this Wnt pathway the Wnt/Ca2+ p athway.