Jiang Y J, Aerne B L, Smithers L, Haddon C, Ish-Horowicz D, Lewis J
Vertebrate Development Laboratory, Imperial Cancer Research Fund, London, UK.
Nature. 2000 Nov 23;408(6811):475-9. doi: 10.1038/35044091.
In vertebrates with mutations in the Notch cell-cell communication pathway, segmentation fails: the boundaries demarcating somites, the segments of the embryonic body axis, are absent or irregular. This phenotype has prompted many investigations, but the role of Notch signalling in somitogenesis remains mysterious. Somite patterning is thought to be governed by a "clock-and-wavefront" mechanism: a biochemical oscillator (the segmentation clock) operates in the cells of the presomitic mesoderm, the immature tissue from which the somites are sequentially produced, and a wavefront of maturation sweeps back through this tissue, arresting oscillation and initiating somite differentiation. Cells arrested in different phases of their cycle express different genes, defining the spatially periodic pattern of somites and controlling the physical process of segmentation. Notch signalling, one might think, must be necessary for oscillation, or to organize subsequent events that create the somite boundaries. Here we analyse a set of zebrafish mutants and arrive at a different interpretation: the essential function of Notch signalling in somite segmentation is to keep the oscillations of neighbouring presomitic mesoderm cells synchronized.
在Notch细胞间通讯途径发生突变的脊椎动物中，体节形成失败：界定体节（胚胎体轴的节段）的边界缺失或不规则。这种表型引发了许多研究，但Notch信号在体节发生中的作用仍然神秘。体节模式形成被认为受“时钟和波前”机制控制：一个生化振荡器（分割时钟）在前体节中胚层（依次产生体节的未成熟组织）的细胞中运作，一个成熟波前向后扫过该组织，停止振荡并启动体节分化。处于细胞周期不同阶段的细胞表达不同的基因，定义了体节的空间周期性模式并控制分割的物理过程。有人可能认为，Notch信号对于振荡或组织形成体节边界的后续事件是必需的。在这里，我们分析了一组斑马鱼突变体并得出了不同的解释：Notch信号在体节分割中的基本功能是使相邻前体节中胚层细胞的振荡保持同步。
