Acquisition of Hox codes during gastrulation and axial elongation in the mouse embryo
Acquisition of Hox codes during gastrulation and axial elongation in the mouse embryo
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DOI：
10.1242/dev.00573
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发表时间：
2003-08-01
期刊：
影响因子：
4.6
通讯作者：
Deschamps, J
中科院分区：
文献类型：
--
作者：
Forlani, S;Lawson, KA;Deschamps, J
小鼠 Hox 基因的早期连续表达对其后期功能至关重要。因此，分析早期 Hox 基因表达与原肠胚形成期间和之后前后结构的铺设之间的关系对于理解 Hox 介导的轴向模式的本体发生至关重要。使用原肠胚阶段胚胎的外植体，我们发现表达 3' 和 5' Hox 基因的能力在原条区域中顺序发展，随着条线延伸，从后到前，比明显的 Hox 表达早约 12 小时。在原肠胚形成开始时，后条纹区域存在自主表达最早的 Hox 基因 Hoxb1 的能力，但在此阶段的前部区域不存在。然而，后部区域可以诱导这些前部区域细胞中 Hoxb1 的表达。我们得出的结论是，组织在原肠胚形成早期就已准备好表达Hox基因，伴随着原条的形成和延伸，并且Hox基因诱导性是通过细胞间的信号传导传递的。在Hox表达域到达节点区域并继续向喙部扩散期间，随后表达Hox基因的轴向结构在节点区域中产生。然而，谱系分析表明，最终的 Hox 代码并不固定在节点上，而是必须在神经外胚层中的节点之后和之前获得，并且在中胚层中独立获得。我们得出的结论是，Hox 基因表达的头端进展必须从后条的早期开始就受到基因调控影响的调节，直到细胞沿着节点前方的轴获得稳定的位置。
Early sequential expression of mouse Hox genes is essential for their later function. Analysis of the relationship between early Hox gene expression and the laying down of anterior to posterior structures during and after gastrulation is therefore crucial for understanding the ontogenesis of Hox-mediated axial patterning. Using explants from gastrulation stage embryos, we show that the ability to express 3' and 5' Hox genes develops sequentially in the primitive streak region, from posterior to anterior as the streak extends, about 12 hours earlier than overt Hox expression. The ability to express autonomously the earliest Hox gene, Hoxb1, is present in the posterior streak region at the onset of gastrulation, but not in the anterior region at this stage. However, the posterior region can induce Hoxb1 expression in these anterior region cells. We conclude that tissues are primed to express Hox genes early in gastrulation, concomitant with primitive streak formation and extension, and that Hox gene inducibility is transferred by cell to cell signalling.Axial structures that will later express Hox genes are generated in the node region in the period that Hox expression domains arrive there and continue to spread rostrally. However, lineage analysis showed that definitive Hox codes are not fixed at the node, but must be acquired later and anterior to the node in the neurectoderm, and independently in the mesoderm. We conclude that the rostral progression of Hox gene expression must be modulated by gene regulatory influences from early on in the posterior streak, until the time cells have acquired their stable positions along the axis well anterior to the node.