Fig. 10. Model for Ring1-mediated ventral specification in the early stage mouse telencephalon.

Ring1 suppresses BMP and Wnt signaling pathways outside of the dorsal midline at the early stage of mouse telencephalic development and thereby confers a permissive state for Shh expression. Shh-inducing signals at the most ventral portion of the telencephalon can thus induce Shh expression in this region, resulting in ventral patterning of the telencephalon. By contrast, Ring1 ablation results in the ectopic activation of BMP and Wnt signaling outside of the dorsal midline and thereby suppresses Shh-mediated ventral patterning of the telencephalon.