The Wnt‐signaling pathways in mammalian patterning and morphogenesis

Wnt signaling in eye organogenesis

“…Several studies, for example in the gastrulating chick embryo and in cell culture experiments, suggest that Wnt/β-catenin signaling is active in an increasing anterior to posterior gradient along the brain to generate posterior neural tissue. [15][16][17][18][19] Consistent with this model, Wnt/β-catenin signaling is not detectable in the most rostral parts of the forebrain, the telencephalon and rostral diencephalon. 11 To maintain anterior neural tissue, expression of secreted antagonists (SFRP1, Tlc, Dkk-1) or intracellular inhibitors (ICAT, TCF-3/headless, Axin1/masterblind, Shisa) of the Wnt/β-catenin pathway are required in the anterior neural plate (Fig.…”

“…One possible explanation is that different levels of Wnt/β-catenin activation can specify different brain regions, with the lowest level required for telencephalic fate and highest levels for hindbrain specification. 18 Together, these studies suggest that distinct mechanisms precisely coordinate Wnt/β-catenin pathway activation at an appropriate level in the anterior neural plate to permit specification of forebrain subdomains. However, in mammals this model needs to be explored in further detail.…”