Two distinct sources for a population of maturing axial progenitors
Two distinct sources for a population of maturing axial progenitors
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DOI：
10.1242/dev.02877
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发表时间：
2007-08-01
期刊：
影响因子：
4.6
通讯作者：
Wilson, Valerie
中科院分区：
文献类型：
--
作者：
Cambray, Noemi;Wilson, Valerie
在哺乳动物中，原始条纹区及其后代，尾芽，是新生中胚层和脊髓的来源，贯穿轴向伸长。长期轴向祖细胞的局部种群已经在尾芽，脊索神经铰链的区域被确定，但这种祖细胞在早期阶段的局部种群迄今尚未得到测试。通过研究基因表达，我们已经表明，从条纹到尾芽，区域的特定拓扑排列持续存在，包括一个区域（节点-条纹边界），其中表达原始条纹标记的外胚层覆盖在未来的脊索上。这种排列在脊索神经铰链中仍然存在。同位移植物显示，与其他脊椎动物一样，条纹和节中的细胞主要产生中胚层，而在节-条纹边界和条纹外侧的细胞也产生神经胚层。结点条纹边界后代不仅分布在整个神经轴上的神经直胚层、节体和脊索，而且分布在脊索神经铰链上。胚日(E)8.5条纹外侧的外胚层后来被招募到中线，在那里它产生体和脊索神经铰链细胞，其位置与边界来源的细胞重叠。因此，将形成尾巴的E8.5轴向祖细胞包括来自两个不同来源的细胞：边缘和外侧外胚层。此外，来自边界外的异位细胞移植到该区域也填充脊索神经铰链。一些条纹芽和尾芽特异性基因的表达在伸长结束之前就下降了，即使这个晚期群体可以成功地移植到早期胚胎中。因此，至少祖细胞状态的某些方面是由环境赋予的，而不是细胞的固有属性。
In mammals, the primitive streak region and its descendant, the tail bud, are the source of nascent mesoderm and spinal cord throughout axial elongation. A localised population of long-term axial progenitors has been identified in a region of the tail bud, the chordoneural hinge, but the localisation of such progenitors at earlier stages is so far untested. By studying gene expression, we have shown that a specific topological arrangement of domains persists from the streak to the tail bud, and includes an area (the node-streak border) in which ectoderm that expresses primitive streak markers overlies the prospective notochord. This arrangement persists in the chordoneural hinge. Homotopic grafts show that, as in other vertebrates, cells in the streak and node predominantly produce mesoderm, whereas those in the node-streak border and lateral to the streak additionally produce neurectoderm. Node-streak border descendants populate not only neurectoderm, somites and notochord throughout the axis, but also the chordoneural hinge. Ectoderm lateral to the embryonic day (E)8.5 streak is later recruited to the midline, where it produces somites and chordoneural hinge cells, the position of which overlaps that of border-derived cells. Therefore, the E8.5 axial progenitors that will make the tail comprise cells from two distinct sources: the border and lateral ectoderm. Furthermore, heterotopic grafts of cells from outside the border to this region also populate the chordoneural hinge. Expression of several streak- and tail bud-specific genes declines well before elongation ends, even though this late population can be successfully transplanted into earlier embryos. Therefore, at least some aspects of progenitor status are conferred by the environment and are not an intrinsic property of the cells.