smad2 and smad3 are required for mesendoderm induction by transforming growth factor-β/Nodal signals in zebrafish
smad2 and smad3 are required for mesendoderm induction by transforming growth factor-β/Nodal signals in zebrafish
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DOI：
10.1074/jbc.m707578200
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发表时间：
2008-01-25
影响因子：
4.8
通讯作者：
Meng, Anming
中科院分区：
文献类型：
--
作者：
Jia, Shunji;Ren, Zhen;Meng, Anming
转化生长因子β配体Nodal、激活素和Vg 1在脊椎动物胚胎发生过程中的中内胚层诱导和模式化中起重要作用。据信这些配体通过受体激活的转录因子Smad 2和Smad 3来转导信号。然而，smad 2/ 3基因在斑马鱼胚胎发育中的作用在很大程度上是未知的，因为多个smad 2/ 3基因的存在和它们的母体表达阻碍了它们的发育作用的调查。我们通过突变多个氨基酸产生了有效和特异的显性负性形式的斑马鱼Smad 2、Smad 3a和Smad 3b。这些突变体的过表达废除了斑马鱼胚胎中异位Nodal信号的中内胚层诱导。显性失活Smad 2/3的表达使野生型胚胎中的Smad 2/3活性消失，并引起与Nodal缺陷胚胎相似的各种中内胚层缺陷。移植到野生型宿主胚盘边缘的Smad 2/3缺陷细胞优先分化为外胚层组织而不是中内胚层组织，支持细胞对中内胚层诱导剂的反应需要Smad 2/3活性的观点。在Zoep，Moep和MZoep突变胚胎中干扰Smad 2/3活性导致更严重的中内胚层缺陷。因此，我们的数据显示，Nodal信号和中内胚层诱导依赖于Smad 2/3，并表明，转化生长因子β信号以外的Nodal也有助于Smad 2/3信号和胚胎模式。
The transforming growth factor-beta ligands Nodal, activin, and Vg1 play important roles in mesendoderm induction and patterning during vertebrate embryogenesis. These ligands are believed to transduce the signal through the receptor-activated transcription factors Smad2 and Smad3. However, the roles of smad2/ 3 genes in development of zebrafish embryos are largely unknown because the presence of multiple smad2/ 3 genes and their maternal expression have hampered the investigation of their developmental roles. We generated potent and specific dominant- negative forms of zebrafish Smad2, Smad3a, and Smad3b by mutating multiple amino acids. Overexpression of these mutants abolished mesendoderm induction by ectopic Nodal signaling in zebrafish embryos. Expression of dominantnegative smad2/3 abrogated Smad2/3 activities in wild- type embryos and caused various mesendodermal defects similar to those in Nodal- deficient embryos. Smad2/3-deficient cells transplanted into the blastodermal margin of wild- type hosts preferentially differentiated into ectodermal tissues rather than mesendodermal tissues, supporting the idea that response of cells to mesendoderm inducers requires Smad2/3 activities. Interference with Smad2/3 activities in Zoep, Moep, and MZoep mutant embryos resulted in more severe mesendodermal defects. Thus, our data reveal that Nodal signaling and mesendoderm induction depend on Smad2/3 and suggest that transforming growth factor-beta signals other than Nodal also contribute to Smad2/3 signaling and embryonic patterning.