Main

Acting as signals between cells, Wnt proteins regulate the proliferation of cells. Wnt signals are active in numerous contexts, during early development and later during the growth and maintenance of various tissues. In comparison to other growth factors, Wnt signals have several unique properties, including a short range of action. Thereby, Wnts predominantly mediate signaling locally, between neighboring  cells. In addition, Wnt signals give shape to tissues as cells are proliferating. This is a consequence of the ability of Wnt signaling to confer polarity and asymmetry to cells. Wnt proteins are highly conserved in evolution and are active in every branch of the animal kingdom.

Wnt signaling is often implicated in stem cell control, as a proliferative and self-renewal signal. Mutations in Wnt genes or Wnt pathway components lead to specific developmental defects, while various human diseases, including cancer, are caused by abnormal Wnt signaling. 

Insights into the mechanisms of Wnt action have emerged from several systems: genetics in Drosophila and Caenorhabditis elegans; biochemistry in cell culture and ectopic gene expression in Xenopus embryos. As currently understood, Wnt proteins bind to receptors of the Frizzled and LRP families on the cell surface. Through several cytoplasmic relay components, the signal is transduced to ß-catenin, which enters the nucleus and forms a complex with TCF to activate transcription of Wnt target genes.