The nucleolar structure and the activity of NopA100, a nucleolin-like protein, during the cell cycle in proliferating plant cells
The nucleolar structure and the activity of NopA100, a nucleolin-like protein, during the cell cycle in proliferating plant cells
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DOI：
10.1007/s00418-005-0081-1
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发表时间：
2006-01-01
影响因子：
2.3
通讯作者：
Medina, FJ
中科院分区：
文献类型：
--
作者：
González-Camacho, F;Medina, FJ
为了了解细胞增殖和核糖体生物发生之间的关系，作为两个相互关联的基本细胞过程，通过用羟基脲处理，然后在去除羟基脲后在不同时间取样，对细胞周期进展同步的细胞群进行了研究。在整个间期观察到核仁的结构重排，以及不同核仁亚成分相对量的变化。核仁组织的结构模型与每个间期相关。在整个间期，核仁样蛋白 NopA100 在核仁的致密原纤维成分中进行免疫检测，特别是在原纤维中心附近，其水平从 G1 到 G2 有所增加。使用抗 NopA100 抗体对可溶性核蛋白提取物进行蛋白质印迹分析，结果显示 100 kDa 条带以及一系列与其相关的蛋白质被强烈标记，这表明 NopA100 经历了蛋白水解成熟的生理过程，类似于哺乳动物核蛋白的描述，但在其他生物模型系统中尚未报道。根据细胞周期阶段，用蛋白酶抑制剂亮肽素处理从同步细胞中提取的细胞核后，证实了与细胞周期进展相关的 NopA100 的生理蛋白水解作用，导致 100 kDa 条带增加，但代价是其他一些条带减少。因此，我们得出结论，核仁活性的增加、细胞周期进程、核仁结构、NopA100 的活性和这种核仁样蛋白的蛋白水解之间存在关系。
For the purpose of gaining knowledge of the relationships between cell proliferation and ribosome biogenesis, as two fundamental mutually interconnected cellular processes, studies were performed on cell populations synchronized in their cell-cycle progression by treatment with hydroxyurea, followed by sampling at different times after its removal. A structural rearrangement of the nucleolus was observed throughout the interphase, along with changes in the relative amounts of different nucleolar subcomponents. A structural model of nucleolar organization was associated with each interphase period. Throughout interphase, the nucleolin-like protein, NopA100, was immunodetected in the dense fibrillar component of the nucleolus, preferentially near fibrillar centers and its levels were shown to increase from G1 to G2. A western blotting analysis of soluble nuclear protein extracts with anti-NopA100 antibody resulted in the intense labeling of a 100-kDa band, but also of a series of proteins related to it, suggesting that NopA100 undergoes a physiological process of proteolytic maturation, similar to that described for mammalian nucleolin, but not reported in other biological model systems. Physiological proteolysis of NopA100, related to cell-cycle progression, was confirmed after the nuclei extracted from synchronized cells were treated with the protease inhibitor, leupeptin, which resulted in an increase of the 100-kDa band at the expenses of the decrease of some other bands, according to the cell-cycle stages. We therefore conclude that there is a relationship between the increase in nucleolar activity, cell-cycle progression, nucleolar structure, the activity of NopA100, and the proteolysis of this nucleolin-like protein.