@misc{oai:repo.qst.go.jp:00069842,
 author = {Imaichi, Hisashi and Tsukamoto, Satoshi and Oota, Yuki and Kito, Seiji and Imai, Hiroshi and Minami, Naojiro and et.al and 塚本 智史 and 太田 有紀 and 鬼頭 靖司 and 南 直治郎},
 month = {May},
 note = {Gene products stored in oocytes play important roles after the completion of meiosis and fertilization. These genes are called maternal effect gene and shown to be important in early embryonic development in many species. We previously identified Oog1 that is expressed specifically in oocytes of all stages of follicles and preimplantation embryos by the late 2-cell stage. It has also been revealed that Oog1 protein localized in nuclei at the late 1-cell and early 2-cell stages, the time of the occurrence of zygotic genome activation (ZGA) in mice. We also reported that Oog1 interacts with RAS effectors (e.g., RALGDS and RASA4) and also binds to RAS in a GTP dependent manner. These results suggest that Oog1 is one of the RAS mediated signaling proteins. However, the biological function of Oog1 in oogenesis and/or in early embryogenesis is still unclear. In the present study, we attempted to knock down Oog1 specifically in mouse oocyte using a recently developed transgenic RNAi approach. We first constructed two transgenes differing in the sequence of Oog1 inverted repeats (IR1 and IR2). The expression of transgenes is controlled by Zp3 promoter that directs oocyte-specific expression of the Oog1 double-stranded (ds) RNA. The zygotes of C57BL/6J were used for microinjection. Nine founder mice (5 females and 4 males) were obtained, of which 5 were generated by IR1 and 4 by IR2. To examine the fertility of these transgenic founder females, the mice were mated with four wild-type males in a random sequence. Successful mating was verified by detecting a vaginal plug, and then the mated females were housed separately for recording the average number of pups delivered per litter to assess the fertility. Finally, the oocytes of founder females were used to measure the amount of Oog1 transcripts by real-time RT-PCR and the ovaries were used for morphological analysis. To examine the effect of Oog1 knock down on preimplantation embryo development, we obtained transgenic F1 female progenies by mating four transgenic founder males with wild-type females. Fertilized embryos were collected from transgenic F1 females mated with wild-type males and then cultured in KSOM medium for 96 hours. At the time of embryo collection, GV stage oocytes were simultaneously collected from the same female ovaries and the amount of Oog1 transcript was measured by real-time RT-PCR. In four of five transgenic founder females, the average litter sizes were apparently reduced compared with control mice and the amount of Oog1 transcript was markedly reduced except one transgenic line. In some transgenic line, the embryos obtained from F1 females stopped development at the 2- to 8-cell stages and the amount of Oog1 transcript was reduced compared with wild-type oocytes. In these transgenic females, the morphology of ovaries and the ovulation looked normal, suggesting that Oog1 is possibly a novel maternal effect gene functioned in early embryo development. However, in some transgenic lines, although the amount of Oog1 transcript in GV oocyte was not reduced, the female showed sub-fertility and the embryos stopped development. From these controversial results, it is necessary to examine the relationship between the amount of Oog1 protein and female fertility and the developmental competence of embryo. In addition, further investigations to examine the phenotype of F2 and F3 females are required to reveal the biological function of Oog1., The 41st annual Meeting, Society for the Study of Reproduction},
 title = {Analysis of Oog1, an oocyte-specific gene, using transgenic RNAi approach.},
 year = {2008}
}