Mammalian zygotic genome activation

Abstract

Zygotic genome activation (ZGA) denotes the initiation of gene expression after fertilization. It is part of the complex oocyte-to-embryo transition (OET) in which a highly specialized cell - the oocyte - is fertilized and transformed into a zygote that gives rise to an embryo that will develop into a newborn. From the perspective of gene expression, the OET reflects reprogramming of germ cell gene expression into the new developmental program of the zygote. This reprogramming occurs at transcriptional and post-transcriptional levels. This review will discuss selected aspects of mammalian ZGA, highlighting shared features and evolved differences observed in commonly investigated mammals and non-mammalian model animals.

Keywords: Chromatin; DNA methylation; Epigenetics; Gene expression; Histone modifications; Oocyte-to-embryo transition; Protamine/histone exchange; Retrotransponsons; Transcription; Zygotic genome activation.