Analysis of the role of WNT factors during early mouse development.

A double approach is proposed to help understand the role of Wnts during early embryogenesis. The first approach, now a classical one, is to inactivate the Wnt-13 gene, expressed in the gastrula by replacing it with LacZ and to analyze the the mutant phenotype of embryos. Second, based on the encouraging results obtained with Xenopus Wnt-8, it is proposed to produce various soluble Wnt proteins and analyse their inductive role in ES celldifferentiation and on embryo explants. This second aproach is more risky than the first one but may open a hole new field for studying the roles of Wnt in gastrulation as well as in other operations.