Department of Biology, Faculty of Sciences, Kyushu University, Fukuoka 812-8581, Japan.
J Theor Biol. 2009 Apr 7;257(3):385-96. doi: 10.1016/j.jtbi.2009.01.003. Epub 2009 Jan 9.
In vertebrate somitogenesis, "segmentation clock" genes (such as her in zebrafish, hairy in chick, and hes in mouse) show oscillation, synchronized over nearby cells through cell-cell interaction. The locations of high gene expression appear with regular intervals and move like a wave from posterior to anterior with the speed slowing down toward the anterior end. We analyze traveling wave pattern of her gene expression when there is an anterior-posterior gradient of one of the reaction rates in the gene-protein kinetics. We adopt a model which includes the kinetics of mRNA and proteins of her gene in each cell and cell-cell interaction by Delta-Notch system explicitly. We show that the observed spatio-temporal pattern can be explained if mRNA degradation, protein translation, protein transportation to nucleus occurs faster, or mRNA transcription, Delta protein synthesis occurs slower in posterior than in anterior regions. All of these gradients are those that produce longer periodicity of oscillation of clock gene expression in the anterior than in the posterior. Based on this result, we derive a mathematical formula for how the peak of gene expression moves along the pre-somitic mesoderm.
在脊椎动物体节形成过程中，“分段时钟”基因（如斑马鱼中的 her、鸡中的 hairy 和鼠中的 hes）表现出振荡，通过细胞间的相互作用在附近细胞中同步。高基因表达的位置以规则的间隔出现，并像波一样从前向后移动，速度在前部逐渐减慢。当基因-蛋白动力学中的一个反应速率存在前后梯度时，我们分析了 her 基因表达的移动波模式。我们采用了一个模型，该模型在每个细胞中明确包括 her 基因的 mRNA 和蛋白质的动力学以及 Delta-Notch 系统的细胞间相互作用。我们表明，如果 mRNA 降解、蛋白质翻译、蛋白质向核内运输在后部比在前部更快，或者 mRNA 转录、Delta 蛋白合成在后部比在前部更慢，则可以解释观察到的时空模式。所有这些梯度都是在后部产生比前部更长的时钟基因表达振荡周期的梯度。基于这个结果，我们推导出了一个关于基因表达如何沿着体节中胚层移动的数学公式。
