Ishiguro Kei-Ichiro, Monti Manuela, Akiyama Tomohiko, Kimura Hiromi, Chikazawa-Nohtomi Nana, Sakota Miki, Sato Saeko, Redi Carlo Alberto, Ko Shigeru B H, Ko Minoru S H
Department of Systems Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo, 160-8582, Japan.
Institute of Molecular Embryology and Genetics, Kumamoto University, 2-2-1 Honjo, Chuo-ku, Kumamoto, 860-0811, Japan.
In Vitro Cell Dev Biol Anim. 2017 Feb;53(2):167-178. doi: 10.1007/s11626-016-0096-z. Epub 2016 Oct 3.
Mouse zinc finger and SCAN domain containing 4 (Zscan4) proteins, which are encoded by multiple copies of Zscan4 genes, are expressed specifically in preimplantation embryos in vivo and embryonic stem (ES) cells in vitro. However, the expression patterns of mouse Zscan4 in vivo have been largely elusive. Here, we show that Zscan4 proteins are expressed in adult ovaries and testes. In ovaries, Zscan4 proteins were detected in germinal vesicle (GV) stage oocytes in antral follicles, indicating that Zscan4 genes are activated during the diplotene/dictyate stage in meiotic prophase I. Remarkably, Zscan4 showed different spatial localization patterns between two distinct GV oocytes, which can be distinguished by global chromatin organization-surrounded nucleolus (SN) and non-surrounded nucleolus (NSN). These spatiotemporal differences in Zscan4 localizations correlated with the transition of RNA polymerase II-mediated transcriptional status during GV oocyte maturation. In testes, Zscan4 proteins were detected in spermatocytes at late pachytene/diplotene stages and in Sertoli cells. These results suggest that Zscan4 may play critical roles during late meiotic prophase in both males and females.
小鼠含锌指和SCAN结构域4（Zscan4）蛋白由多个Zscan4基因拷贝编码，在体内植入前胚胎和体外胚胎干细胞（ES细胞）中特异性表达。然而，小鼠Zscan4在体内的表达模式在很大程度上仍不清楚。在此，我们表明Zscan4蛋白在成年卵巢和睾丸中表达。在卵巢中，在窦状卵泡的生发泡（GV）期卵母细胞中检测到Zscan4蛋白，这表明Zscan4基因在减数分裂前期I的双线期/核网期被激活。值得注意的是，Zscan4在两种不同的GV卵母细胞之间表现出不同的空间定位模式，这两种卵母细胞可通过整体染色质组织——围绕核仁（SN）和非围绕核仁（NSN）来区分。Zscan4定位的这些时空差异与GV卵母细胞成熟过程中RNA聚合酶II介导的转录状态转变相关。在睾丸中，在粗线期/双线期后期的精母细胞和支持细胞中检测到Zscan4蛋白。这些结果表明，Zscan4可能在雄性和雌性减数分裂前期后期发挥关键作用。
