Fig. 8.
Regulatory mechanisms among β-catenin, Pax3, Cdx2 and tail bud signaling genes during posterior neural tube closure and elongation processes. (A-D) Cdx2 mRNA is also inactivated in the dorsal PNP domain (between the arrowheads) of the Pax3-null embryo (B) at E9.5; it cannot be restored by the conditional gain-of-function (GOF) of Pax3 in β-catenin cKOs (C) but is expanded in the dorsal PNP of the Pax3Cre;Pax3-GOF embryo (D). (E) Summary of transcriptional regulation by β-catenin of Pax3 expression (1) and possibly co-regulation by β-catenin and Pax3 of Cdx2 expression (2) in the dorsal PNPs, and the regulation by Wnt/β-catenin signaling of T, Tbx6 and Fgf8 at the tail bud (3) during caudal neural tube closure and elongation processes. Solid arrows indicate interactions demonstrated in this study (1-3) and in the literature (3); dashed arrows indicate interactions demonstrated only in the literature. tb, tail bud; dPNP, dorsal posterior neuropore.