Depletion of nucleophosmin leads to distortion of nucleolar and nuclear structures in HeLa cells
Depletion of nucleophosmin leads to distortion of nucleolar and nuclear structures in HeLa cells
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DOI：
10.1042/bj20081411
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发表时间：
2008-11-01
影响因子：
4.1
通讯作者：
Fukui, Kiichi
中科院分区：
文献类型：
--
作者：
Amin, Mohammed Abdullahel;Matsunaga, Sachihiro;Fukui, Kiichi
NPM（核磷蛋白;也称为B23）是一种大量且普遍表达的多功能核仁磷蛋白，其参与许多细胞过程，包括核糖体生物合成、蛋白质伴侣和中心体复制;然而，NPM在细胞周期中的作用仍然未知。在本研究中，我们显示了动态定位的NPM在整个细胞周期的HeLa细胞。使用RNAi（RNA干扰）和三维显微镜的组合，我们表明，NPM是本地化在有丝分裂过程中的染色体外周。我们还表明，耗尽的NPM引起核仁结构的扭曲，如预期的那样，并导致意外的戏剧性变化，在核形态与多个微核的形成。通过活细胞成像清楚地观察到的NPM耗尽的细胞的核形状的缺陷是由于细胞骨架（α-微管蛋白和β-肌动蛋白）结构的畸变，这是由中心体微管成核的缺陷引起的。这些结果表明，NPM是一个必要的蛋白质，不仅为正常的核仁结构的形成，而且为维持规则的核形状在HeLa细胞。
NPM (nucleophosmin; also known as B23) is an abundantly and ubiquitously expressed multifunctional nucleolar phosphoprotein, which is involved in numerous cellular processes, including ribosome biogenesis, protein chaperoning and centrosome duplication; however, the role of NPM in the cell cycle still remains unknown. In the present study, we show dynamic localization of NPM throughout the cell cycle of HeLa cells. Using a combination of RNAi (RNA interference) and three-dimensional microscopy we show that NPM is localized at the chromosome periphery during mitosis. We also demonstrate that depletion of NPM causes distortion of nucleolar structure as expected and leads to unexpected dramatic changes in nuclear morphology with multiple micronuclei formation. The defect in nuclear shape of NPM-depleted cells, which is clearly observed by live-cell imaging, is due to the distortion of cytoskeletal (alpha-tubulin and beta-actin) structure, resulting from the defects in centrosomal microtubule nucleation. These results indicate that NPM is an essential protein not only for the formation of normal nucleolar structure, but also for the maintenance of regular nuclear shape in HeLa cells.