Medaka oct4 is essential for gastrulation, central nervous system development and angiogenesis.

Gene oct4 (also called oct3/4 or pou5f1) encodes an octamer-binding transcription factor and is best known for its pluripotency-specific expression and pluripotency-maintaining role in early embryos and embryonic stem cells of mouse and human. Its fish paralog oct4 (also called pou2 or pou5f3) plays divergent roles in embryos and stem cells development. Here the expression and function of the medaka oct4 (Oloct4) during gastrulation and organogenesis were analysed. Oloct4 RNA was abundant in pluripotent cells and differentiated extraembryonic cells of blastula embryos. It was also detectable in primordial germ cells, brain, eye and tail bud at advanced stages. Importantly, oct4 depletion at high dosages severely affected gastrulation and axis formation. Surprisingly, Oloct4 depletion at low dosages also led to embryos that either had defective brain, eye and/or blood vessels or completely lacked them. Oloct4 depletion in transgenic embryos caused the loss of rx2-positive retinal stem cells in the developing eye. Therefore, Oloct4 is essential for gastrulation, central nervous system development as well as angiogenesis in medaka besides its role in pluripotency maintenance. These results together with previous studies suggest that Oloct4 play pleiotropic roles and represent the ancestral prototype of vertebrate oct4 and pou2 genes.

Sun B ，Gui L ，Liu R ，Hong Y ，Li M ... -  《-》

Medaka Oct4 is essential for pluripotency in blastula formation and ES cell derivation.

Liu R ，Li M ，Li Z ，Hong N ，Xu H ，Hong Y ... -  《-》

Medaka Oct4 is expressed during early embryo development, and in primordial germ cells and adult gonads.

Sánchez-Sánchez AV ，Camp E ，García-España A ，Leal-Tassias A ，Mullor JL ... -  《-》

oct4-EGFP reporter gene expression marks the stem cells in embryonic development and in adult gonads of transgenic medaka.

Maintenance of pluripotency in stem cells is tightly regulated among vertebrates. One of the key genes in this process is oct4, also referred to as pou5f1 in mammals and pou2 in teleosts. Pou5f1 evolved by duplication of pou2 early in the tetrapod lineage, but only monotremes and marsupials retained both genes. Either pou2 or pou5f1 was lost from the genomes of the other tetrapods that have been analyzed to date. Consequently, these two homologous genes are often designated oct4 in functional studies. In most vertebrates oct4 is expressed in pluripotent cells of the early embryo until the blastula stage, and later persist in germline stem cells until adulthood. The isolation and analysis of stem cells from embryo or adult individuals is hampered by the need for reliable markers that can identify and define the cell populations. Here, we report the faithful expression of EGFP under the control of endogenous pou2/oct4 promoters in transgenic medaka (Oryzias latipes). In vivo imaging in oct4-EGFP transgenic medaka reveals the temporal and spatial expression of pou2 in embryos and adults alike. We describe the temporal and spatial patterns of endogenous pou2 and oct4-EGFP expression in medaka with respect to germline and adult stem cells, and discuss applications of oct4-EGFP transgenic medaka in reproductive and stem cell biology.

Froschauer A ，Khatun MM ，Sprott D ，Franz A ，Rieger C ，Pfennig F ，Gutzeit HO ... -  《-》

Identification of pluripotency genes in the fish medaka.

Wang D ，Manali D ，Wang T ，Bhat N ，Hong N ，Li Z ，Wang L ，Yan Y ，Liu R ，Hong Y ... -  《International Journal of Biological Sciences》