The oocyte-to-embryo transition in mouse: past, present, and future†

Abstract

The oocyte-to-embryo transition (OET) arguably initiates with formation of a primordial follicle and culminates with reprogramming of gene expression during the course of zygotic genome activation. This transition results in converting a highly differentiated cell, i.e. oocyte, to undifferentiated cells, i.e. initial blastomeres of a preimplantation embryo. A plethora of changes occur during the OET and include, but are not limited to, changes in transcription, chromatin structure, and protein synthesis; accumulation of macromolecules and organelles that will comprise the oocyte's maternal contribution to the early embryo; sequential acquisition of meiotic and developmental competence to name but a few. This review will focus on transcriptional and post-transcriptional changes that occur during OET in mouse because such changes are likely the major driving force for OET. We often take a historical and personal perspective, and highlight how advances in experimental methods often catalyzed conceptual advances in understanding the molecular bases for OET. We also point out questions that remain open and therefore represent topics of interest for future investigation.

Dynamic Alternative Splicing During Mouse Preimplantation Embryo Development

“…During preimplantation development from an occyte, cells progressively develop toward to the blastocyst as zygotic genome is activated. It has been extensively studied that gene expression level is spatial-temporally dynamic during early embryonic development (Fan et al, 2015;Schultz et al, 2018). Recently, some evidence indicated that AS could correlate closely with preimplantation development, suggesting a key role for splicing in regulating early embryonic development (Revil et al, 2010;Yan et al, 2013).…”

“…The number of protein-coding genes (1,3259) in the 2-cell stage is larger than other developmental stages. ZGA is the first major developmental event that occurs following fertilization (Schultz et al, 2018). After ZGA process, the genetic program governed by maternal transcripts/proteins should be switched to that dominated by transcripts/proteins from the newly formed zygotic genome (Kanka, 2003;Hamatani et al, 2004).…”

DUX4 regulates oocyte to embryo transition in human

“…The oocyte-to-embryo transition gradually sets the stage for embryo development 30–33 . DUX4 is an obvious primary candidate mediating chromatin and transcriptome changes that are crucial for oocyte-to-embryo transition.…”

Essential roles of Hdac1 and 2 in lineage development and genome-wide DNA methylation during mouse preimplantation development

“…A distinguishing feature of preimplantation development is a remarkable reprograming of the epigenome, including DNA modifications and post-translational histone modifications (1, 2). Aberrant epigenetic reprograming has been associated with defects in various biological processes, including DNA replication and embryonic genome activation (EGA), which eventually leads to early embryonic death (3).…”