Transcription Factor <scp>TCF12</scp> ‐Mediated Maternal Gene Expressions in Mouse Oocyte Are Prerequisites of Successful Fertilisation and Zygotic Genome Activation

The maternal gene products stored in oocytes control the initial development of multicellular animals. Alteration within the dual allelic variants of transcription factor TCF12 causes female infertility; however, its impact on female reproduction is still unknown. In this study, we provide evidence that TCF12 is abundantly expressed within the nucleus of oocytes during growth at the germinal vesicle (GV) stage, recognising and binding to the functional domain of target genes to moderate transcriptional activity. The absence of Tcf12 in oocytes during the primordial follicular phase causes female sterility. Tcf12 does not participate in meiotic maturation; however, unlike Tcf3, it is essential for fertilisation and preimplantation development. Tcf12 maintains fertilisation competence by controlling the proper expression and location of cortical granules and protease ovastacin (encoded by Astl). In contrast, zygotes without TCF12 have a prolonged mitotic cell cycle upon a decrease in protein phosphatase 2A (PP2A) activity inhibition, resulting in zygotic genome activation (ZGA) failure during the 2-cell stage. Maternal knockout embryos gradually lose their developmental potential in subsequent developmental processes. These observations indicate that the maternal effect induced by Tcf12 ensures preimplantation development.