FGF signaling induces mesoderm in the hemichordate Saccoglossus kowalevskii
FGF signaling induces mesoderm in the hemichordate Saccoglossus kowalevskii
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DOI：
10.1242/dev.083790
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发表时间：
2013-03-01
期刊：
影响因子：
4.6
通讯作者：
Lowe, Christopher J.
中科院分区：
文献类型：
--
作者：
Green, Stephen A.;Norris, Rachael P.;Lowe, Christopher J.
FGF在脊椎动物中胚层诱导中起作用，并且在海鞘和文昌鱼的早期中胚层形成中也起关键作用。然而，在海胆中，FGF功能的初始表征不支持早期中胚层诱导的作用，使得FGF信号传导的祖先作用和后口动物中胚层规范的机制不清楚。为了更好地表征中胚层形成的演变，我们研究了FGF信号在Saccoglossus kowalevskii中胚层发育过程中的作用，Saccoglossus kowalevskii是一种实验上易于处理的半索动物代表。我们报告的FGF配体，FGF 8/17/18，在外胚层覆盖网站内的原肠内中胚层中胚层规格的表达。胚胎学实验表明，在原肠中的中胚层诱导需要与外胚层接触，和功能丧失的实验表明，FGF配体和受体是必要的中胚层规范。fgf 8/17/18功能获得性实验证实，FGF 8/17/18足以在相邻的内中胚层中诱导中胚层。这些实验表明，FGF信号是必需的中胚层规格的最早阶段，是所有中胚层发育所需的。此外，他们认为原肠能够形成中胚层或内胚层，并且来自外胚层的FGF信号传导限定了中胚层的位置和量。当考虑在比较的情况下，这些数据支持在中胚层规格的FGF 8/17/18信号转导的遗传学广泛的要求，并表明FGF信号转导后口中胚层形成中发挥了祖先的作用。
FGFs act in vertebrate mesoderm induction and also play key roles in early mesoderm formation in ascidians and amphioxus. However, in sea urchins initial characterizations of FGF function do not support a role in early mesoderm induction, making the ancestral roles of FGF signaling and mechanisms of mesoderm specification in deuterostomes unclear. In order to better characterize the evolution of mesoderm formation, we have examined the role of FGF signaling during mesoderm development in Saccoglossus kowalevskii, an experimentally tractable representative of hemichordates. We report the expression of an FGF ligand, fgf8/17/18, in ectoderm overlying sites of mesoderm specification within the archenteron endomesoderm. Embryological experiments demonstrate that mesoderm induction in the archenteron requires contact with ectoderm, and loss-of-function experiments indicate that both FGF ligand and receptor are necessary for mesoderm specification. fgf8/17/18 gain-of-function experiments establish that FGF8/17/18 is sufficient to induce mesoderm in adjacent endomesoderm. These experiments suggest that FGF signaling is necessary from the earliest stages of mesoderm specification and is required for all mesoderm development. Furthermore, they suggest that the archenteron is competent to form mesoderm or endoderm, and that FGF signaling from the ectoderm defines the location and amount of mesoderm. When considered in a comparative context, these data support a phylogenetically broad requirement for FGF8/17/18 signaling in mesoderm specification and suggest that FGF signaling played an ancestral role in deuterostome mesoderm formation.