COMPONENTS OF THE NUCLEOLAR PROCESSING COMPLEX (PRE-RIBOSOMAL-RNA, FIBRILLARIN, AND NUCLEOLIN) COLOCALIZE DURING MITOSIS AND ARE INCORPORATED TO DAUGHTER CELL NUCLEOLI
COMPONENTS OF THE NUCLEOLAR PROCESSING COMPLEX (PRE-RIBOSOMAL-RNA, FIBRILLARIN, AND NUCLEOLIN) COLOCALIZE DURING MITOSIS AND ARE INCORPORATED TO DAUGHTER CELL NUCLEOLI
复制标题
DOI：
10.1006/excr.1995.1358
复制
发表时间：
1995-11-01
影响因子：
3.7
通讯作者：
FERNANDEZGOMEZ, ME
中科院分区：
文献类型：
--
作者：
MEDINA, FJ;CERDIDO, A;FERNANDEZGOMEZ, ME
我们在洋葱根细胞中追踪了rRNA、前一个间期G2期合成的RNA以及核仁蛋白纤维蛋白和核仁蛋白的有丝分裂过程。用能够与成熟rRNA杂交的rDNA探针以及Pre-rRNA加工的中间形式进行超微结构原位杂交检测rRNA。用氚尿苷标记的G2同步细胞的放射自显影显示，前一代细胞中合成的RNA(根据经典数据，主要是rRNA)。用免疫荧光法在哺乳动物细胞和洋葱细胞中检测纤维蛋白原，并将后者的结果与AgNOR染色后的结果进行比较。用电子显微镜免疫细胞化学方法检测洋葱细胞中的纤维蛋白和核仁素。在所有病例中，核仁在前期分散后，在中期和后期的染色体周边、末期染色体之间的不规则纤维团、末期的核仁前小体和核发生后的新形成的核仁中均可检测到该信号。此外，不出所料，核糖体在原位杂交后出现了标记，但在所有实验中都观察到了分散的细胞质标记，主要是在中期和后期。这些结果表明，参与Pre-rRNA加工的核仁成分，包括rRNA本身，可能是以不完全加工的形式从亲本核仁转移到子细胞核仁，通过瞬时结构，如染色体周鞘和核仁前小体。由于这些大分子组分组装在间期核仁中，形成RNP加工复合体，因此它们在有丝分裂期间在相同的瞬时结构中的共存强烈表明，至少这些复合体的子集在细胞分裂期间不会解体，而是保持组装并并入新的核仁。因此，核糖体的生物发生不仅在转录水平上的有丝分裂后重新启动，而且在前rRNA加工的中间水平上也重新启动。(C)1995年学术出版社。
We have traced in onion root cells the mitotic course of rRNA, of the RNA synthesized in the G2 period of the preceding interphase, and of the nucleolar proteins fibrillarin and nucleolin. The rRNA was detected by ultrastructural in situ hybridization with a rDNA probe capable of hybridizing mature rRNAs and also the intermediate forms of pre-rRNA processing. The RNA synthesized in the preceding G2 (which, according to classical data, is mostly rRNA) was revealed by autoradiography on synchronous cells labeled in G2 by tritiated uridine. Fibrillarin was detected by immunofluorescence in both mammalian and onion cells; the results in the latter cells were compared with those obtained after AgNOR staining. Electron microscopical immunocytochemistry was used to detect fibrillarin and nucleolin in onion cells. In all cases, following nucleolar dispersion in prophase, the signal was detected in the chromosome periphery during metaphase and anaphase, in irregular fibrillar masses located between chromosomes in ana-telophase, in prenucleolar bodies during telophase, and in the newly formed nucleoli, after nucleologenesis. Moreover, as expected, ribosomes appeared labeled after in situ hybridization, but a dispersed cytoplasmic labeling was observed in all experiments, mainly during metaphase and anaphase. These results demonstrate that nucleolar components involved in pre-rRNA processing, including rRNA itself, probably in an incompletely processed form, are transferred from the parental to the daughter cell nucleoli by means of transient structures, such as the perichromosomal sheath and prenucleolar bodies. Since these macromolecular components are assembled in the interphase nucleolus, forming the RNP processing complex, their colocalization during mitosis in the same transient structures strongly suggests that at least a subset of these complexes does not disaggregate during cell division, but remains assembled and becomes incorporated to the new nucleolus. Therefore, ribosome biogenesis restarts not only after mitosis at the level of transcription, but also at the intermediate levels of pre-rRNA processing. (C) 1995 Academic Press, Inc.