Wnts are a large family of secreted signalling proteins that act via two main pathways, the canonical and non-canonical pathways, to play important roles in development. At least fifteen different Wnts are found in vertebrates, and each one appears to function in just one pathway and independently of other Wnts. Now, on , Janet Heasman and colleagues report that two Wnts, Wnt5a and Wnt11, act together to activate both the canonical and non-canonical pathways during dorsoventral(DV) patterning in the Xenopus embryo. The authors arrive at this finding through investigating the action of maternal Dkk1, a canonical Wnt inhibitor, in DV patterning. Dkk1 turns out to inhibit both the canonical and non-canonical pathways by targeting maternal Wnt5a and Wnt11, which the authors show interact with each other. Surprisingly, they find that these Wnts are present as homodimers, rather than as monomers, which interact to generate larger signalling complexes. Future work should reveal whether such interactions form a general, hitherto unrecognised feature of Wnt signalling.
