Gautier T, Fomproix N, Masson C, Azum-Gélade M C, Gas N, Hernandez-Verdun D
Institut Jacques Monod, Paris, France.
Biol Cell. 1994;82(2-3):81-93. doi: 10.1016/s0248-4900(94)80010-3.
In mammalian cells, the nucleoli disintegrate during mitosis and some nucleolar proteins disperse at the periphery of all chromosomes forming a novel class of chromosomal passenger proteins. The nucleolar components which participate in the formation of this perichromosomal layer have been investigated to elucidate the role of these perichromosomal proteins in the assembly and disassembly of the nucleoli. i) Electron microscopy immunolabelling reveals that these proteins are predominantly located in the granular component of the nucleoli during interphase. ii) Immunoprecipitation data suggest that they are distributed at the chromosome periphery in association with U3 small nucleolar RNA (snoRNA). In addition, the distribution of U3 snoRNA visualized by in situ hybridization, is similar to that observed for the perichromosomal proteins. iii) In cells which possess a nucleolar remnant during mitosis, U3 snoRNA and perichromosomal proteins were found both in the perichromosomal layer and in the nucleolar remnant. iv) Some of these proteins are conserved from yeast to man such as fibrillarin and a protein of 52 kDa. v) The location of these proteins observed in yeast by confocal microscopy shows that they are not dispersed during mitosis. Their partition between the two daughter cells is performed by scission of nucleolar structures forming a rod during the budding process. Therefore RNP complexes related to the processing steps of ribosome biogenesis in mammalian cells quit the nucleolus in late G2 and associate with the chromosome periphery until late telophase. They associate in the perichromosomal layer in human and PtK1 cells and both in the perichromosomal layer and the nucleolar remnant in CHO cells.
在哺乳动物细胞中，核仁在有丝分裂期间解体，一些核仁蛋白分散在所有染色体的周边，形成一类新型的染色体乘客蛋白。为了阐明这些染色体周边蛋白在核仁组装和解体中的作用，研究了参与形成这种染色体周边层的核仁成分。i）电子显微镜免疫标记显示，在间期这些蛋白主要位于核仁的颗粒成分中。ii）免疫沉淀数据表明，它们与U3小核仁RNA（snoRNA）一起分布在染色体周边。此外，通过原位杂交观察到的U3 snoRNA的分布与染色体周边蛋白的分布相似。iii）在有丝分裂期间具有核仁残余物的细胞中，在染色体周边层和核仁残余物中都发现了U3 snoRNA和染色体周边蛋白。iv）其中一些蛋白从酵母到人类都是保守的，如纤维蛋白原和一种52 kDa的蛋白。v）通过共聚焦显微镜在酵母中观察到的这些蛋白的位置表明，它们在有丝分裂期间不会分散。它们在两个子细胞之间的分配是通过在出芽过程中形成杆状的核仁结构分裂来完成的。因此，与哺乳动物细胞核糖体生物合成加工步骤相关的核糖核蛋白复合物在G2晚期离开核仁，并与染色体周边结合，直到末期晚期。它们在人类和PtK1细胞的染色体周边层中结合，在CHO细胞的染色体周边层和核仁残余物中都有结合。
