脊椎动物父系基因组主动去甲基化研究进展

Research progress on active demethylation of paternal genome in vertebrates

基因组表观遗传重组出现在细胞发育潜能发生变化的时期。早期植入前胚胎的表观遗传重新编程对于细胞分化和胚胎的生长发育是至关重要的,这涉及到表观遗传印记(尤其是DNA甲基化)的消除和重建过程。脊椎动物许多物种中,DNA复制起始前父系基因组通常要经历主动去甲基化,而母系基因组则可以保持甲基化的状态不变,直到在随后的卵裂过程中被动去甲基化。综述了脊椎动物父系基因组主动去甲基化的机制,这种去甲基化在脊椎动物各物种间的差异,以及影响这种主动去甲基化机制的因素。另外,研究外源基因表达的表观调控机制(尤其是表观遗传重编程的异常现象)有利于理解转基因克隆水产动物中普遍存在的授精成功率较低,基因整合率较低,以及胚胎发育异常等现象,有利于更好地应用转基因克隆技术。

Genome-wide epigenetic reprogramming occurs at stages when developmental potency of ceils changes. Epigenetic repro- gramming in early preimplantation embryos which erase and remodel epigenetic marks, especially DNA methylation, is essential for differentiation and development. In many vertebrate species, paternal genome is subjected to genome-wide active demethylation before the DNA replication commences, while maternal genome maintains its methylation status until being demethylated passively during the sub- sequent cleavage divisions. This review introduces the available knowledge about the paternal genome active demethylation process in vertebrates, concerning the possible mechanisms, species variation and the factors affecting the active demethylation dynamics. Research on regulatory mechanism of exogenous gene expression （ especially abnormal epigenetic reprogramming） contributes to the better understanding of many problems, such as low successful rate of insemination and gene integration, and abnormal development of embryos in transgenic aquatic animals, and is also beneficial to the more efficient application of transgenic cloning technology.