Protein Interaction of Nucleophosmin/B23 with Nucleolin/C23 in Cell Proliferation and Cell Cycle

• Main Authors: Liu, Hsien-Ta, 劉顯達
• Other Authors: Benjamin Yat-Ming Yung
• Format: Others
• Language: zh-TW
• Published: 1997
• Online Access: http://ndltd.ncl.edu.tw/handle/94784220798883938947

碩士 === 長庚醫學暨工程學院 === 基礎醫學研究所 === 85 === Nucleophosmin/B23, is a major nucleolar phosphoprotein which is more abundant in tumor cells as compared to normal resting cells. When cells are treatment with an anti-tumor drug, such as actinomycin D, that inhibits cell growth or during the stationary phase of growth, nucleophosmin/B23 translocates from nucleolus to nucleoplasm. Nucleophosmin/B23 has been proposed to be involved in the preribosomal particle assembly and nucleolin/ C23 has been proposed to be involved in rRNA processing. In this report, cross-linking reagent, dithiobis succinimidyl propionate (DSP), was used to detect nucleophosmin/B23-nucleolin/C23 complex in HeLa cells. By using immunoprecipitation, immunofluorescence and confocal microscopy, I have found that nucleophosmin/B23 interacts with nucleolin/C23 in interphase as well as in cytokinesis, but not in prometaphase nor in metaphase of cell cycle. In actinomycin D-induced inhibition of cell growth, the interaction of nucleophosmin/B23 and nucleolin/C23 is found not only in cells in which both proteins are localized in nucleolus but also in cells in which they have translocated from nucleolus to nucleoplasm. In cell free kinase and immunoprecipitation assays, the nucleophosmin/B23-nucleolin/C23 interaction is not related to the cell cycle dependent phosphorylation states of nucleophosmin/B23. These results indicate: (1) The associated complex of nucleophosmin/B23 and nucleolin/C23 during cytokinesis and interphase may be a part of the assembly line responsible for the synthesis and processing of pre-ribosomal particles and rRNA. (2) Factors other than phosphorylations of nucleophosmin/B23 to interact with nucleolin/C23, resulting in the cease of nucleolar activities and mitotically structural dissolution of the nucleolus.