Notochord-Neuron interaction during the chordate evolution.

中线器官脊索及其覆盖的背侧神经管是脊索体计划最突出的特征。尽管在脊椎动物胚胎中对神经系统背侧模式的分子机制进行了广泛的研究，但还没有发现在脊索细胞中特异表达的基因在这一过程中发挥作用。在这里，我们报道了在肠索脊索动物中编码一种纤维蛋白原样蛋白的基因，该蛋白在神经细胞依赖于脊索的背部定位中起着关键作用。因此，基于脊索的纤维蛋白原样蛋白和基于神经管的Notch信号的相互作用很可能是神经系统背侧模式或建立脊索体计划所必需的。

The midline organ notochord and its overlying dorsal neural tube are the most prominent features of the chordate body plan. Although molecular mechanisms involved in the dorsal patterning of the nervous system have been studied extensively in vertebrate embryos, none of the genes that are expressed specifically in notochord cells have been shown to function in this process. Here, we report a gene in the urochordate Ciona intestinalis encoding a fibrinogen-like protein that plays a pivotal role in the notochord-dependent dorsal positioning of neuronal cells. Therefore, it is highly likely that the interaction of the notochord-based fibrinogen-like protein and the neural tube-based Notch signaling is essential for the dorsal patterning of the nervous system or for the establishment of the chordate body plan.