Wnt signaling maintains the notochord fate for progenitor cells and supports the posterior extension of the notochord.
The notochord develops from notochord progenitor cells (NPCs) and functions as a major signaling center to regulate trunk and tail development. NPCs are initially specified in the node by Wnt and Nodal signals at the gastrula stage. However, the underlying mechanism that maintains the NPCs throughout embryogenesis to contribute to the posterior extension of the notochord remains unclear. Here, we demonstrate that Wnt signaling in the NPCs is essential for posterior extension of the notochord. Genetic labeling revealed that the Noto-expressing cells in the ventral node contribute the NPCs that reside in the tail bud. Robust Wnt signaling in the NPCs was observed during posterior notochord extension. Genetic attenuation of the Wnt signal via notochord-specific beta-catenin gene ablation resulted in posterior truncation of the notochord. In the NPCs of such mutant embryos, the expression of notochord-specific genes was down-regulated, and an endodermal marker, E-cadherin, was observed. No significant alteration of cell proliferation or apoptosis of the NPCs was detected. Taken together, our data indicate that the NPCs are derived from Noto-positive node cells, and are not fully committed to a notochordal fate. Sustained Wnt signaling is required to maintain the NPCs' notochordal fate.
Ukita
Kanako
K
Laboratory for Embryonic Induction, RIKEN Center for Developmental Biology, Chuo, Kobe, Hyogo 650-0047, Japan.
Hirahara
Shino
S
Oshima
Naoko
N
Imuta
Yu
Y
Yoshimoto
Aki
A
Jang
Chuan-Wei
CW
Oginuma
Masayuki
M
Saga
Yumiko
Y
Behringer
Richard R
RR
Kondoh
Hisato
H
Sasaki
Hiroshi
H
D000818:Animals; D017209:Apoptosis; D049109:Cell Proliferation; D020869:Gene Expression Profiling; D051379:Mice; D008810:Mice, Inbred C57BL; D009672:Notochord / Q000196:embryology* / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology*; D051153:Wnt Proteins / Q000378:metabolism*; D051176:beta Catenin / Q000378:metabolism
D051153:Wnt Proteins; D051176:beta Catenin