Wnt signalling in mouse gastrulation and anterior development: new players in the pathway and signal output.

Embryonic development and adult homeostasis are dependent upon the coordinated action of signal transduction pathways such as the Wnt signalling pathway which is used iteratively during these processes. In the early post-implantation mouse embryo, Wnt/β-catenin signalling activity plays a critical role in the formation of the primitive streak, progression of gastrulation and tissue patterning in the anterior-posterior axis. The net output of the signalling pathway is influenced by the delivery and post-translational modification of the ligands, the counteracting activities of the activating components and the negative modulators, and the molecular interaction of β-catenin, TCF and other factors regulating the transcription of downstream target genes.