Teranishi Takahide, Tanaka Mamoru, Kimoto Shingo, Ono Yukiko, Miyakoshi Kei, Kono Tomohiro, Yoshimura Yasunori
Department of Obstetrics and Gynecology, Keio University School of Medicine, Shinjuku, Tokyo 160-8582, Japan.
Dev Biol. 2004 Feb 1;266(1):76-86. doi: 10.1016/j.ydbio.2003.10.004.
The most distinctive feature of oocyte-specific linker histones is the specific timing of their expression during embryonic development. In Xenopus nuclear transfer, somatic linker histones in the donor nucleus are replaced with oocyte-specific linker histone B4, leading to the involvement of oocyte-specific linker histones in nuclear reprogramming. We recently have discovered a mouse oocyte-specific linker histone, named H1foo, and demonstrated its expression pattern in normal preimplantation embryos. The present study was undertaken to determine whether the replacement of somatic linker histones with H1foo occurs during the process of mouse nuclear transfer. H1foo was detected in the donor nucleus soon after transplantation. Thereafter, H1foo was restricted to the chromatin in up to two-cell stage embryos. After fusion of an oocyte with a cell expressing GFP (green fluorescent protein)-tagged somatic linker histone H1c, immediate release of H1c in the donor nucleus was observed. In addition, we used fluorescence recovery after photobleaching (FRAP), and found that H1foo is more mobile than H1c in living cells. The greater mobility of H1foo may contribute to its rapid replacement and decreased stability of the embryonic chromatin structure. These results suggest that rapid replacement of H1c with H1foo may play an important role in nuclear remodeling.
卵母细胞特异性连接组蛋白最显著的特征是其在胚胎发育过程中表达的特定时间。在非洲爪蟾核移植中，供体细胞核中的体细胞连接组蛋白被卵母细胞特异性连接组蛋白B4所取代，这导致卵母细胞特异性连接组蛋白参与核重编程。我们最近发现了一种小鼠卵母细胞特异性连接组蛋白，命名为H1foo，并展示了其在正常植入前胚胎中的表达模式。本研究旨在确定在小鼠核移植过程中是否发生了用H1foo取代体细胞连接组蛋白的情况。移植后不久就在供体细胞核中检测到了H1foo。此后，H1foo在直至二细胞期胚胎中都局限于染色质。在一个卵母细胞与表达绿色荧光蛋白（GFP）标记的体细胞连接组蛋白H1c的细胞融合后，观察到供体细胞核中H1c立即释放。此外，我们使用了光漂白后荧光恢复（FRAP）技术，发现H1foo在活细胞中的流动性比H1c更大。H1foo更大的流动性可能有助于其快速取代以及胚胎染色质结构稳定性的降低。这些结果表明，用H1foo快速取代H1c可能在核重塑中起重要作用。
