The functions of Wnt/β-catenin signalling during embryogenesis have been well documented, but much less is known about its role in the adult. Now,Randall Moon and colleagues show how distinct Wnt signalling pathways have opposing roles in zebrafish tail fin regeneration. On , they report that, following injury, wnt10a activates the β-catenin signalling pathway, leading to fgf20a expression, which is required for blastema formation and tail fin regeneration. Wnt5b, however,acts independently of, and antagonistically to, the β-catenin pathway,thereby inhibiting regeneration. Because its expression is regulated by theβ-catenin pathway via wnt10a expression, the authors propose that these opposing Wnt pathways establish negative-feedback loops that modulate β-catenin signalling to ensure the correct level, location and duration of this signalling pathway in tail fin regeneration. As the authors discuss, Wnt/β-catenin signalling is also upregulated in the development of vertebrate liver and heart, although its precise role is unclear. Nevertheless, these findings may provide targets for therapeutic regenerative medicine in the future.
