Laboratory of Cell Morphology, Institute of Cytology of the Russian Academy of Science, 4 Tikhoretsky Ave., 194064 St. Petersburg, Russia.
St. Petersburg State University, 7/9 Universitetskaya Emb., 199034 St. Petersburg, Russia.
Acta Histochem. 2019 May;121(4):522-529. doi: 10.1016/j.acthis.2019.04.007. Epub 2019 Apr 24.
Nuclear distribution of Death-associated protein 6 (Daxx) was studied using fluorescent and electron microscopy in mouse embryos at different stages of development in vivo, from zygote to morula. Daxx was found in association with transcriptionally silent chromatin predominantly with a heterochromatin rim surrounding the nucleolus precursor bodies (NPBs) at all stages studied. At the zygote stage, Daxx was detected only at the periphery of NPBs both in male and female pronuclei. At the late two-cell stage, Daxx was localized not only in the heterochromatin rim at the periphery of NPBs but also in heterochromatin zones not associated with NPBs. At the morula stage, a diffuse distribution of Daxx prevailed. Scarce Daxx-positive zones were detected only in some embryos at the nucleolar periphery. Thus, Daxx is noticeably redistributed during mouse embryo cleavage, and the most conspicuous areas of Daxx concentration are observed at the end of two-cell stage. Daxx is found colocalized with the chromatin-remodeling protein ATRX exclusively in two-cell embryos, but the heterochromatin areas containing either Daxx or ATRX individually are also observed at this stage. However, most zones containing both Daxx and ATRX demonstrated a low FRET-efficiency. This suggest that two molecules are not approached sufficiently close for molecular interactions to occur. Our data suggests that Daxx may function without cooperation with ATRX at least at some stages of early mouse development.
在体内从受精卵到桑椹胚的不同发育阶段的小鼠胚胎中，使用荧光和电子显微镜研究了死亡相关蛋白 6（Daxx）的核分布。发现 Daxx 与转录沉默染色质相关，主要与核前体体（NPB）周围的异染色质边缘相关，在所有研究的阶段均如此。在受精卵阶段，Daxx 仅在雄性和雌性原核的 NPB 周边被检测到。在晚期的两细胞阶段，Daxx 不仅定位于 NPB 周边的异染色质边缘，而且定位于与 NPB 无关的异染色质区域。在桑椹胚阶段，Daxx 呈弥散分布。仅在一些胚胎的核仁周边检测到稀少的 Daxx 阳性区域。因此，Daxx 在小鼠胚胎分裂过程中明显重新分布，在两细胞阶段末期观察到最明显的 Daxx 浓度区域。发现 Daxx 与染色质重塑蛋白 ATRX 共定位于两细胞胚胎中，但在该阶段也观察到单独含有 Daxx 或 ATRX 的异染色质区域。然而，大多数含有 Daxx 和 ATRX 的区域表现出低 FRET 效率。这表明两个分子没有足够接近以发生分子相互作用。我们的数据表明，Daxx 可能在至少一些早期小鼠发育阶段无需与 ATRX 合作即可发挥作用。
