WNTS MODULATE CELL FATE AND BEHAVIOR DURING VERTEBRATE DEVELOPMENT

Wnt genes encode a family of secreted glycoproteins that modulate cell fate and behavior in embryos through activation of receptor-mediated signaling pathways. Wnt sequences, patterns of expression and activiti es are highly conserved in evolution, so it has been possible to gain insights into the functions, and mechanisms of action, of the Wnt gene s through a synthesis of genetic and cell biological approaches in dif ferent organisms. These studies suggest that there are functionally di stinct WNT proteins as assayed by the ability to transform cells and b y differences in embryonic responses to ectopic WNT signals. Moreover, gain-of-function and loss-of-function studies both support the involv ement of Wnt proteins in modulating cell fate and cell behavior during vertebrate development, often through combinatorial interactions with other signaling pathways to regulate gene expression.