Morichika Keisuke, Sugimoto Makoto, Yasuda Katsuki, Kinoshita Tsutomu
Department of Life Science, School of Science, Rikkyo University, 3-34-1 Nishi-ikebukuro, Toshima, Tokyo 178-8501, Japan.
Department of Bioscience, School of Science and Technology, Kwansei Gakuin University, 2-1 Gakuen, Sanda, Hyogo, 669-1337, Japan.
Zygote. 2014 May;22(2):266-74. doi: 10.1017/S0967199412000536. Epub 2012 Nov 28.
The POU family subclass V (POU-V) proteins have important roles in maintaining cells in an undifferentiated state. In Xenopus, expression of the POU-V protein Oct60 was detected in oocytes and was found to decrease in blastula- to gastrula-stage embryos. In addition, Oct60 overexpression inhibits some signals in early embryogenesis, including Activin/Nodal, BMP, and Wnt signalling. In this report, we analysed mechanisms of Oct60 promoter activation and discovered that Oct60 transcription was activated ectopically in somatic nuclei by oocyte extract treatment. Promoter assays demonstrated that Oct60 transcription was activated in oocytes specifically and that this activation was dependent on an Octamer-Sox binding motif. ChIP assays showed that the Oct60 protein binds the motif. These results suggest that Oct60 transcription is regulated by a positive-feedback loop in Xenopus oocytes.
POU家族V亚类（POU-V）蛋白在维持细胞的未分化状态中发挥着重要作用。在非洲爪蟾中，POU-V蛋白Oct60在卵母细胞中被检测到，并且发现在囊胚期到原肠胚期的胚胎中其表达量下降。此外，Oct60的过表达会抑制早期胚胎发育中的一些信号通路，包括激活素/节点信号通路、骨形态发生蛋白（BMP）信号通路和Wnt信号通路。在本报告中，我们分析了Oct60启动子激活的机制，并发现通过卵母细胞提取物处理，Oct60转录在体细胞核中异位激活。启动子分析表明，Oct60转录在卵母细胞中特异性激活，并且这种激活依赖于一个八聚体-Sox结合基序。染色质免疫沉淀（ChIP）分析表明，Oct60蛋白与该基序结合。这些结果表明，在非洲爪蟾卵母细胞中，Oct60转录受正反馈环调控。
