The zebrafish Iroquois gene iro7 positions the r4/r5 boundary and controls neurogenesis in the rostral hindbrain
The zebrafish Iroquois gene iro7 positions the r4/r5 boundary and controls neurogenesis in the rostral hindbrain
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DOI：
10.1242/dev.01190
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发表时间：
2004-07-01
期刊：
影响因子：
4.6
通讯作者：
Schneider-Maunoury, S
中科院分区：
文献类型：
--
作者：
Lecaudey, V;Anselme, I;Schneider-Maunoury, S
早期大脑区域化涉及神经板不同结构域中编码转录因子的基因的激活。这些领域的界限往往预示着形态学的边界。在后脑中，前后模式依赖于一个分割过程，导致形成七个称为菱形（r）的凸起。参与后脑早期细分和菱体形成的分子线索还没有很好的理解。我们发现，iro 7，斑马鱼基因编码的转录因子的易洛魁族，在原肠胚形成结束时，在未来的中脑和后脑领土的前景r4/r5边界。这一领域是严格互补的表达域的另一个同源框基因，vhnf 1，在尾神经板。我们证明，Iro 7抑制vhnf 1表达前，他们的共同边界，相反，vHnf 1抑制Iro 7表达尾向it. This表明，r4/r5边界定位这两个转录因子之间的相互抑制。此外，iro 7还参与喙侧后脑初级神经元的特化。特别是，它是必不可少的，在r4的毛特纳神经元的形成。我们认为，iro 7在斑马鱼胚胎的后脑中具有双重功能：它是正确定位未来r4/r5边界所必需的，它促进了前后脑的神经发生。
Early brain regionalisation involves the activation of genes coding for transcription factors in distinct domains of the neural plate. The limits of these domains often prefigure morphological boundaries. In the hindbrain, anteroposterior patterning depends on a segmentation process that leads to the formation of seven bulges called rhombomeres (r). The molecular cues involved in the early subdivision of the hindbrain and in rhombomere formation are not well understood. We show that iro7, a zebrafish gene coding for a transcription factor of the Iroquois family, is expressed at the end of gastrulation in the future midbrain and hindbrain territories up to the prospective r4/r5 boundary. This territory is strictly complementary to the expression domain of another homeobox gene, vhnf1, in the caudal neural plate. We demonstrate that Iro7 represses vhnf1 expression anterior to their common border and that, conversely, vHnf1 represses iro7 expression caudal to it. This suggests that the r4/r5 boundary is positioned by mutual repression between these two transcription factors. In addition, iro7 is involved in the specification of primary neurons in the rostral hindbrain. In particular, it is essential for the formation of the Mauthner neurons in r4. We propose that iro7 has a dual function in the hindbrain of the zebrafish embryo: it is required for the proper positioning of the prospective r4/r5 boundary and it promotes neurogenesis in the anterior hindbrain.