Satoh Wataru, Matsuyama Makoto, Takemura Hiromasa, Aizawa Shinichi, Shimono Akihiko
Vertebrate Body Plan, Center for Developmental Biology, RIKEN Kobe, Minatojima-Minami, Chuou-ku, Kobe, Japan.
Genesis. 2008 Feb;46(2):92-103. doi: 10.1002/dvg.20369.
Sfrp is a secreted Wnt antagonist that directly interacts with Wnt ligand. We show here that inactivation of Sfrp1, Sfrp2, and Sfrp5 leads to fused somites formation in early-somite mouse embryos, simultaneously resulting in defective convergent extension (CE), which causes severe shortening of the anteroposterior axis. These observations indicate the redundant roles of Sfrp1, Sfrp2, and Sfrp5 in early trunk formation. The roles of the Sfrps were genetically distinguished in terms of the regulation of Wnt pathways. Genetic analysis combining Sfrps mutants and Loop-tail mice revealed the involvement of Sfrps in CE through the regulation of the planar cell polarity pathway. Furthermore, Dkk1-deficient embryos carrying Sfrp1 homozygous and Sfrp2 heterozygous mutations display irregular somites and indistinct intersomitic boundaries, which indicates that Sfrps-mediated inhibition of the Wnt/beta-catenin pathway is necessary for somitogenesis. Our results suggest that Sfrps regulation of the canonical and noncanonical pathways is essential for proper trunk formation.
Sfrp是一种分泌型Wnt拮抗剂,可直接与Wnt配体相互作用。我们在此表明,Sfrp1、Sfrp2和Sfrp5的失活会导致早期体节期小鼠胚胎中体节融合形成,同时导致缺陷性的汇聚延伸(CE),进而导致前后轴严重缩短。这些观察结果表明Sfrp1、Sfrp2和Sfrp5在早期躯干形成中具有冗余作用。Sfrps的作用在Wnt信号通路的调控方面具有遗传学差异。将Sfrps突变体与弯尾小鼠进行遗传分析,揭示了Sfrps通过调控平面细胞极性信号通路参与汇聚延伸过程。此外,携带Sfrp1纯合突变和Sfrp2杂合突变的Dkk1缺陷胚胎表现出不规则的体节和不清晰的体节间边界,这表明Sfrps介导的对Wnt/β-连环蛋白信号通路的抑制对于体节发生是必要的。我们的结果表明,Sfrps对经典和非经典信号通路的调控对于正常的躯干形成至关重要。