Department of Cell Biology and Anatomy, Graduate School of Medicine, University of Tokyo, Hongo, Tokyo 113-0033, Japan.
Curr Opin Cell Biol. 2012 Feb;24(1):31-9. doi: 10.1016/j.ceb.2012.01.002. Epub 2012 Jan 28.
The establishment of left-right asymmetry during development of vertebrate embryos depends on leftward flow in the nodal cavity. The flow is produced by the rotational movement of the posteriorly tilted nodal cilia. However, it remains poorly understood how the nodal cilia are tilted posteriorly, and how the directionality of the flow is translated into gene expression patterns in the embryo. Recent studies have identified signaling molecules involved in these processes. First, planar cell polarity signaling has been shown to be involved in the posterior positioning of the basal bodies of nodal cilia, which leads to the posterior tilting of their rotation axes. Second, identification of putative receptors and signaling molecules suggests a link between the signaling molecules delivered by the nodal flow, and downstream signaling in the cells surrounding the nodal cavity and the lateral plate mesoderm.
脊椎动物胚胎发育过程中左右不对称的建立依赖于 nodal 腔中的左向流动。该流动是由向后倾斜的 nodal 纤毛的旋转运动产生的。然而，向后倾斜的节点纤毛是如何倾斜的，以及流动的方向如何转化为胚胎中的基因表达模式，这些仍然知之甚少。最近的研究已经确定了参与这些过程的信号分子。首先，平面细胞极性信号已被证明参与了 nodal 纤毛的基底体的后定位，这导致了它们旋转轴的向后倾斜。其次，假定受体和信号分子的鉴定表明，由节点流传递的信号分子与节点腔周围的细胞和侧板中胚层中的下游信号之间存在联系。
