Laboratory for Morphogenetic Signaling, RIKEN Center for Developmental Biology, 2-2-3, Minatojima-Minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan.
Dev Biol. 2013 Sep 15;381(2):460-70. doi: 10.1016/j.ydbio.2013.04.010. Epub 2013 Apr 20.
Segmentation is a body-patterning strategy in which new segments are specified from a segment-addition zone containing uncommitted cells. However, the cell-recruitment process is poorly understood. Here we investigated in detail the segmentation in a polychaete annelid, Perinereis nuntia (Lophotrochozoa), in which new segments emerge at the boundary between the posterior end of the segmented region and the terminal pygidium. Cells at this border synchronously remodel their chromatin, enter the cell cycle, and undergo oriented cell division, before being added to new segments. wingless is expressed at the posterior edge of the pre-existing segment, abutted by hedgehog in the first row of the new segment. Overstimulation of Wingless signaling caused excess cells to enter the cell cycle, prolonging segmentation and widening the new segment. Thus, segment addition may occur by a homeogenetic mechanism, in which Wingless expressed in the differentiated segment coordinates the stepwise recruitment of undifferentiated cells from the segment/pygidium boundary.
分段是一种体模式形成策略，其中新的体节是从含有未分化细胞的分段添加区指定的。然而，细胞募集过程还知之甚少。在这里，我们详细研究了多毛环节动物 Perinereis nuntia（螺旋体动物）中的分段，在这种动物中，新的体节出现在分段区域的后端和末端尾鳍之间的边界处。这个边界处的细胞同步重塑它们的染色质，进入细胞周期，并进行定向细胞分裂，然后被添加到新的体节中。Wingless 在已存在的体节的后缘表达，与新体节的第一排中的 Hedgehog 相邻。Wingless 信号的过度刺激导致过多的细胞进入细胞周期，延长了分段并扩大了新的体节。因此，体节的添加可能是通过同源发生机制发生的，其中在分化的体节中表达的 Wingless 协调从体节/尾鳍边界逐步招募未分化细胞。
