casanova encodes a novel Sox-related protein necessary and sufficient for early endoderm formation in zebrafish
casanova encodes a novel Sox-related protein necessary and sufficient for early endoderm formation in zebrafish
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DOI：
10.1101/gad.892301
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发表时间：
2001-06-15
影响因子：
10.5
通讯作者：
Stainier, DYR
中科院分区：
文献类型：
--
作者：
Kikuchi, Y;Agathon, A;Stainier, DYR
斑马鱼早期内胚层的形成需要至少三个基因座，它们在Nodal信号的下游但在早期内胚层标记sox 17的上游发挥作用：bonnie和克莱德（bon）、浮士德（fau）和卡萨诺瓦（cas）。Cas突变体表现出最严重的表型，因为它们不形成任何肠组织并且缺乏所有sox 17表达。Nodal信号通路的激活或Bon或Fau/Gata 5的过表达不能恢复cas突变体中的任何sox 17表达，表明cas在内胚层形成中起核心作用。在这里，我们表明，CAS编码的一个新成员的Sox家族的转录因子。在早期囊胚中，eas的初始表达出现在背侧卵黄合胞体层（YSL）中，并且不依赖于Nodal信号。与此相反，cas的内胚层表达，开始于晚期囊胚，由Nodal信号调节。Cas是野生型胚胎以及bon和fau/gata 5突变体中sox 17表达的有效诱导剂。Cas也是MZoep突变体中sox 17表达的有效诱导剂，其不能响应Nodal信号传导。此外，cas在假定的中胚层细胞中的异位表达导致其向内胚层的分化。总之，这些数据表明，Cas是斑马鱼内胚层形成过程中Nodal信号传导的主要转录效应子。
Early endoderm formation in zebrafish requires at least three loci that function downstream of Nodal signaling but upstream of the early endodermal marker sox17: bonnie and clyde (bon), faust (fau), and casanova (cas). Cas mutants show the most severe phenotype as they do not form any gut tissue and lack all sox17 expression. Activation of the Nodal signaling pathway or overexpression of Bon or Fau/Gata5 fails to restore any sox17 expression in cas mutants, demonstrating that cas plays a central role in endoderm formation. Here we show that cas encodes a novel member of the Sox family of transcription factors. Initial eas expression appears in the dorsal yolk syncytial layer (YSL) in the early blastula, and is independent of Nodal signaling. In contrast, endodermal expression of cas, which begins in the late blastula, is regulated by Nodal signaling. Cas is a potent inducer of sox17 expression in wild-type embryos as well as in bon and fau/gata5 mutants. Cas is also a potent inducer of sox17 expression in MZoep mutants, which cannot respond to Nodal signaling. In addition, ectopic expression of cas in presumptive mesodermal cells leads to their transfating into endoderm. Altogether, these data indicate that Cas is the principal transcriptional effector of Nodal signaling during zebrafish endoderm formation.