Otto S P, Walbot V
Department of Biological Sciences, Stanford University, California 94305-5020.
Genetics. 1990 Feb;124(2):429-37. doi: 10.1093/genetics/124.2.429.
We present a model for the kinetics of methylation and demethylation of eukaryotic DNA; the model incorporates values for de novo methylation and the error rate of maintenance methylation. From the equations, an equilibrium is reached such that the proportion of sites which are newly methylated equals the proportion of sites which become demethylated in a cell generation. This equilibrium is empirically determined as the level of maintenance methylation. We then chose reasonable values for the parameters using maize and mice as model species. In general, if the genome is either hypermethylated or hypomethylated it will approach the equilibrium level of maintenance methylation asymptotically over time; events occurring just once per life cycle to suppress methylation can maintain a relatively hypomethylated state. Although the equations developed are used here as framework for evaluating events in the whole genome, they can also be used to evaluate the rates of methylation and demethylation in specific sites over time.
我们提出了一个真核生物DNA甲基化和去甲基化动力学模型；该模型纳入了从头甲基化的值和维持甲基化的错误率。从这些方程可以得出一个平衡状态，即新甲基化的位点比例等于在一个细胞世代中去甲基化的位点比例。这个平衡通过实验确定为维持甲基化水平。然后，我们以玉米和小鼠为模型物种，为参数选择了合理的值。一般来说，如果基因组要么高度甲基化要么低甲基化，随着时间的推移它将渐近地接近维持甲基化的平衡水平；在每个生命周期仅发生一次以抑制甲基化的事件可以维持相对低甲基化的状态。尽管这里开发的方程用作评估全基因组事件的框架，但它们也可用于评估特定位点随时间的甲基化和去甲基化速率。
