Oogenesis is regulated by precise gene expression. One of important gene of mouse oogenesis is Dazl which has a role in translation promotion and indispensable for embryonic oocytes. Dazl is thought to be important whole life of oocyte because the expression of Dazl mRNA is detectable from embryonic to postnatal stage. In this study, we found that Dazl protein need to be suppressed in postnatal ovary whereas it has indispensable role in embryonic ovary. If this regulation does not work, female causes litter size reduction due to the defect in pre-implantation development. Thus, switching the Dazl expression from embryonic to postnatal stage by post-transcriptional regulation via Dazl’s 3’UTR is crucial for regulation production of next generation.

This study was partly supported by Grant-in-Aid for Young Scientists (B) to Y.K. (No. 25840091) and Grant-in-Aid for Scientific Research (A) to Y.S. (No. 26251025) from JSPS and by Grant-in-Aid for Scientific Research on Innovative Areas from MEXT to Y.S. (No. 25112002), A.S. (No. 16H01252), and Y.K. (No. 16H01259). K.F. is a JSPS Research Fellow (No. 16J11687).

Figure: DAZL expression is suppressed in postnatal ovary in control (Upper left scheme). On the other hands, the mutant oocytes which lack 3’UTR of Dazl retain DAZL expression even in the postnatal stage and exhibit defects during preimplantation zygote stages (Upper right scheme). In control, most of all E3.5 zygotes became blastocysts (lower left panel), but in the mutant half of them stopped development (lower right panel). Yellow arrow heads indicate zygotes showing arrested development.