Hindbrain-derived Wnt and Fgf signals cooperate to specify the otic placode in Xenopus.
Hindbrain-derived Wnt and Fgf signals cooperate to specify the otic placode in Xenopus.
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DOI：
10.1016/j.ydbio.2008.09.009
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发表时间：
2008-12-01
影响因子：
2.7
通讯作者：
Saint-Jeannet, Jean-Pierre
中科院分区：
文献类型：
--
作者：
Park, Byung-Yong;Saint-Jeannet, Jean-Pierre
耳基板（内耳的雏形）的诱导被认为取决于来自周围组织、头部中胚层和预期的后脑的信号。在这里，我们报告的第一次尝试，以确定具体的神经外胚层的这种诱导过程中爪蟾。为此，我们测试了从不同轴向水平分离的神经板（NP）片段与囊胚期动物帽重组时诱导耳标记Pax8的能力。我们发现，一个单一的结构域的NP，对应于前瞻性的前后脑，有Pax8诱导活性，在此测定。令人惊讶的是，超过一半的这些重组形成耳囊样结构。谱系追踪实验表明，这些囊泡样结构完全来自动物帽，并表达几个泛耳标记。这些重组体中的Pax8激活需要活性Fgf和经典Wnt信号传导，因为干扰任一途径都会阻断Pax8诱导。此外，我们证明了成纤维细胞生长因子和经典的Wnt信号合作激活Pax8表达在孤立的动物帽。我们提出，在缺乏中胚层线索的情况下，后脑来源的Wnt和Fgf信号的联合活性指定了非洲爪蟾的耳基板，并促进其形态发生为耳囊。
Induction of the otic placode, the rudiment of the inner ear, is believed to depend on signals derived from surrounding tissues, the head mesoderm and the prospective hindbrain. Here we report the first attempt to define the specific contribution of the neuroectoderm to this inductive process in Xenopus. To this end we tested the ability of segments of the neural plate (NP), isolated from different axial levels, to induce the otic marker Pax8 when recombined with blastula stage animal caps. We found that one single domain of the NP, corresponding to the prospective anterior hindbrain, had Pax8-inducing activity in this assay. Surprisingly, more than half of these recombinants formed otic vesicle-like structures. Lineage tracing experiments indicate that these vesicle-like structures are entirely derived from the animal cap and express several pan-otic markers. Pax8 activation in these recombinants requires active Fgf and canonical Wnt signaling, as interference with either pathway blocks Pax8 induction. Furthermore, we demonstrate that Fgf and canonical Wnt signaling cooperate to activate Pax8 expression in isolated animal caps. We propose that in the absence of mesoderm cues the combined activity of hindbrain-derived Wnt and Fgf signals specifies the otic placode in Xenopus, and promotes its morphogenesis into an otocyst.
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