Zebrafish Embryonic Neurons Transport Messenger RNA to Axons and Growth Cones In Vivo
Zebrafish Embryonic Neurons Transport Messenger RNA to Axons and Growth Cones In Vivo
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DOI：
10.1523/jneurosci.1510-13.2013
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发表时间：
2013-10-02
影响因子：
5.3
通讯作者：
Giudicelli, Francois
中科院分区：
文献类型：
--
作者：
Baraban, Marion;Anselme, Isabelle;Giudicelli, Francois
虽然mRNA曾经被认为是从轴突隔室中排除的，但在培养中生长或再生轴突中蛋白质合成的存在现在被普遍接受。然而，其范围和功能的重要性仍然是一个深入调查的主题。此外，明确的证据mRNA轴突运输和本地翻译在体内，在一个完整的发展有机体的背景下仍然缺乏。在这里，我们提供了直接证据，证明tubb 5、nefma和stmnb 2基因的mRNA存在于发育中的斑马鱼（Danio rerio）胚胎的几种类型的轴突中，并在生长锥处频繁积累。我们进一步表明，轴突定位的mRNA是一个特定的属性的一个子集的基因，作为mRNA的huc和neurod基因，大量表达在神经元中，没有发现在轴突。我们建立了一个报告系统，其中候选mRNA的3'非翻译区（UTR）与荧光蛋白编码序列融合，在分离的斑马鱼胚胎神经元中表达。使用这个报告基因，我们在tubb5 mRNA的3'UTR中鉴定了轴突定位所必需和足够的基序。因此，我们的工作建立了斑马鱼作为一个模型系统，以研究轴突运输在一个完整的发展脊椎动物有机体，提供了一个实验框架，在体内分析这种运输和研究其机制，并确定了一个新的邮政编码参与轴突mRNA的定位。
Although mRNA was once thought to be excluded from the axonal compartment, the existence of protein synthesis in growing or regenerating axons in culture is now generally accepted. However, its extent and functional importance remain a subject of intense investigation. Furthermore, unambiguous evidence of mRNA axonal transport and local translation in vivo, in the context of a whole developing organism is still lacking. Here, we provide direct evidence of the presence of mRNAs of the tubb5, nefma, and stmnb2 genes in several types of axons in the developing zebrafish (Danio rerio) embryo, with frequent accumulation at the growth cone. We further show that axonal localization of mRNA is a specific property of a subset of genes, as mRNAs of the huc and neurod genes, abundantly expressed in neurons, were not found in axons. We set up a reporter system in which the 3' untranslated region (UTR) of candidate mRNA, fused to a fluorescent protein coding sequence, was expressed in isolated neurons of the zebrafish embryo. Using this reporter, we identified in the 3'UTR of tubb5 mRNA a motif necessary and sufficient for axonal localization. Our work thus establishes the zebrafish as a model system to study axonal transport in a whole developing vertebrate organism, provides an experimental frame to assay this transport in vivo and to study its mechanisms, and identifies a new zipcode involved in axonal mRNA localization.