Temasek Lifescience Laboratory, 1 Research Link, National University of Singapore, 117604 Singapore.
Trends Genet. 2010 Sep;26(9):394-9. doi: 10.1016/j.tig.2010.06.001. Epub 2010 Jul 6.
Chromatin modifications including histone marks and DNA methylation restrict the transcriptional repertoire and participate in cell fate establishment. Conservation of modified chromatin states through cell division and their inheritance through meiosis create mitotic and trans-generational forms of epigenetic memory, respectively. This lies in apparent contradiction with the requirement to reset cell-fate instructive chromatin states between generations. Although DNA methylation is reset in mammals, its resetting in plants remains controversial, and several lines of evidence support trans-generational inheritance of DNA methylation. Based on recent reports we propose that DNA demethylation during female gametogenesis is followed by DNA remethylation during early embryo development. We propose that this reprogramming event is achieved through interplay between active and passive mechanisms that involve both DNA demethylation and de novo DNA methylation.
染色质修饰，包括组蛋白标记和 DNA 甲基化，限制了转录组的范围，并参与了细胞命运的建立。通过有丝分裂和减数分裂分别将修饰的染色质状态保留下来，并将其传递下去，分别产生了有丝分裂和跨代的表观遗传记忆形式。这与在世代之间重置细胞命运指令性染色质状态的要求明显矛盾。尽管哺乳动物的 DNA 甲基化被重置，但植物中的重置仍然存在争议，并且有几条证据支持 DNA 甲基化的跨代遗传。基于最近的报道，我们提出在雌性配子发生过程中发生 DNA 去甲基化，随后在早期胚胎发育过程中发生 DNA 再甲基化。我们提出，这种重编程事件是通过涉及 DNA 去甲基化和从头 DNA 甲基化的主动和被动机制的相互作用来实现的。
