Totipotency in the mouse

Abstract

In mammals, the unicellular zygote starts the process of embryogenesis and differentiates into all types of somatic cells, including both fetal and extraembryonic lineages-in a highly organized manner to eventually give rise to an entire multicellular organism comprising more than 200 different tissue types. This feature is referred to as totipotency. Upon fertilization, oocyte maternal factors epigenetically reprogram the genomes of the terminally differentiated oocyte and spermatozoon and turn the zygote into a totipotent cell. Today, we still do not fully understand the molecular properties of totipotency. In this review, we discuss recent findings on the molecular signature and mechanism of transcriptional regulation networks in the totipotent mouse embryo.

Keywords: Totipotency; Transcription factors; Zygote.

Fig. 1

Mouse preimplantation development. a Mature oocytes are ovulated from the ovary into the oviduct and fertilized by sperm to establish totipotent zygotes that divide and become blastocysts, and finally implant in the uterus at embryonic day 4.5. b After fertilization, stored maternal factors trigger zygotic genome activation (ZGA) that results in formation of a totipotent zygote with a unique two-cell-specific gene-expression profile, followed by waves of transcription activations of lineage specific genes during preimplantation development