Disarming Wnt

摘要

Cells signal to one other through secreted molecules that are conserved across the evolutionary spectrum. One class of these signals is Wnt proteins, which influence the balance between proliferation and differentiation in many cell types, including stem cells. Because this balance is crucial for normal tissue maintenance, and overactivation of Wnt signalling can cause cancer, the activity of Wnt signals is tightly controlled by various extracellular molecules. In this issue, Kakugawa et al. (page 187) describe an unexpected mechanism by which Wnt signals can be downregulated, showing how an extracellular enzyme called Notum renders Wnt inactive.