Nodal/activin signaling establishes oral-aboral polarity in the early sea urchin embryo
Nodal/activin signaling establishes oral-aboral polarity in the early sea urchin embryo
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DOI：
10.1002/dvdy.20194
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发表时间：
2004-12-01
影响因子：
2.5
通讯作者：
Venuti, JM
中科院分区：
文献类型：
--
作者：
Flowers, VL;Courteau, GR;Venuti, JM
Wnt信号通路的组成部分参与了海胆初级或动物-植物（AV）轴的模式化，但模式化次级胚胎轴（aboral/oral（AO）轴）的分子线索尚不清楚。在信号分子的分析，影响图案沿着海胆胚胎轴，我们发现，成员的活化素亚家族的转化生长因子-β（TGF-β）信号分子的影响建立AO极性在早期胚胎。将激活素mRNA注射到受精卵中或用外源性重组激活素处理改变了外胚层命运的分配并使胚胎腹侧化。观察到的表型类似于先前报道的腹型NiCl 2，一个已知的AO图案的破坏者。对外源激活素的敏感性发生在受精和囊胚晚期之间，这也是NiCl 2敏感性最高的时间。这些结果表明，规格的命运沿着胚胎AO轴涉及TGF-β信号。为了进一步研究这些胚胎中的TGF-β信号传导，我们从海胆胚胎中克隆了一种内源性TGF-β，它是激活素亚家族SpNodal的成员，并通过功能分析表明，它概括了外源性激活素和NiCl 2获得的结果。SpNodal的表达模式与节点信号传导在沿AO轴沿着建立命运中的作用一致。使用SpNodal反义吗啉代的功能丧失实验也支持SpNodal在AO轴的建立中的作用。(C)2004威利-利斯公司
Components of the Wnt signaling pathway are involved in patterning the sea urchin primary or animal-vegetal (AV) axis, but the molecular cues that pattern the secondary embryonic axis, the aboral/oral (AO) axis, are not known. In an analysis of signaling molecules that influence patterning along the sea urchin embryonic axes, we found that members of the activin subfamily of transforming growth factor-beta (TGF-beta) signaling molecules influence the establishment of AO polarities in the early embryo. Injection of activin mRNAs into fertilized eggs or treatment with exogenously applied recombinant activin altered the allocation of ectodermal fates and ventralized the embryo. The phenotypes observed resemble the ventralized phenotype previously reported for NiCl2, a known disrupter of AO patterning. Sensitivity to exogenous activin occurs between fertilization and the late blastula stage, which is also the time of highest NiCl2 sensitivity. These results argue that specification of fates along the embryonic AO axis involves TGF-beta signaling. To further examine TGF-beta signaling in these embryos, we cloned an endogenous TGF-beta from sea urchin embryos that is a member of the activin subfamily, SpNodal, and show through gain of function analysis that it recapitulates results obtained with exogenous activins and NiCl2. The expression pattern of SpNodal is consistent with a role for nodal signaling in the establishment of fates along the AO axis. Loss of function experiments using SpNodal antisense morpholinos also support a role for SpNodal in the establishment of the AO axis. (C) 2004 Wiley-Liss, Inc.