Specification of epibranchial placodes in zebrafish
Specification of epibranchial placodes in zebrafish
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DOI：
10.1242/dev.02749
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发表时间：
2007-02-01
期刊：
影响因子：
4.6
通讯作者：
Raible, David W.
中科院分区：
文献类型：
--
作者：
Nechiporuk, Alexei;Linbo, Tor;Raible, David W.
在所有脊椎动物中，神经原基板是短暂的外胚层增厚，引起颅神经节的感觉神经元。上鳃基板产生面神经、舌咽神经和迷走神经的神经元，这些神经元将感觉从内脏（包括咽内胚层结构）传递到CNS。最近的研究表明，咽内胚层的信号在EB基板神经发生的启动，然而，基板形成的信号是未知的。在这里，我们表明，斑马鱼胚胎fgf3和fgf8突变体不表达早期EB基板标记，包括foxi1和pax2a。镶嵌分析表明，基板细胞必须直接接收FGF信号在特定的关键时期的发展。移植实验和突变体分析表明，头中胚层是FGF信号的来源。最后，Fgf3和Fgf8都足以在野生型以及Fgf3加Fgf8耗尽的胚胎中诱导foxi1阳性基板前体。我们提出了一个模型，其中中胚层来源的FGF3和FGF8信号建立EB基板和咽内胚层的发展，随后的相互作用促进神经发生。因此，颅面组织之间的协调相互作用将确保在脊椎动物头部的成形中适当的空间和时间相互作用。
In all vertebrates, the neurogenic placodes are transient ectodermal thickenings that give rise to sensory neurons of the cranial ganglia. Epibranchial (EB) placodes generate neurons of the distal facial, glossopharyngeal and vagal ganglia, which convey sensation from the viscera, including pharyngeal endoderm structures, to the CNS. Recent studies have implicated signals from pharyngeal endoderm in the initiation of neurogenesis from EB placodes; however, the signals underlying the formation of placodes are unknown. Here, we show that zebrafish embryos mutant for fgf3 and fgf8 do not express early EB placode markers, including foxi1 and pax2a. Mosaic analysis demonstrates that placodal cells must directly receive Fgf signals during a specific crucial period of development. Transplantation experiments and mutant analysis reveal that cephalic mesoderm is the source of Fgf signals. Finally, both Fgf3 and Fgf8 are sufficient to induce foxi1-positive placodal precursors in wild-type as well as Fgf3- plus Fgf8-depleted embryos. We propose a model in which mesoderm-derived Fgf3 and Fgf8 signals establish both the EB placodes and the development of the pharyngeal endoderm, the subsequent interaction of which promotes neurogenesis. The coordinated interplay between craniofacial tissues would thus assure proper spatial and temporal interactions in the shaping of the vertebrate head.