Osteopontin localizes to the nucleus of 293 cells and associates with polo-like kinase-1
Osteopontin localizes to the nucleus of 293 cells and associates with polo-like kinase-1
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DOI：
10.1152/ajpcell.00477.2006
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发表时间：
2007-02-01
影响因子：
5.5
通讯作者：
Zahradka, Peter
中科院分区：
文献类型：
--
作者：
Junaid, Asad;Moon, Michael C.;Zahradka, Peter
骨桥蛋白（OPN）是一种分泌型磷蛋白，参与细胞增殖并与肿瘤进展相关。虽然已经描述了OPN的细胞内形式，但其功能仍然未知。在这项研究中，一种新的细胞内骨桥蛋白的核定位和与细胞分裂的相关性被证明。在瞬时转染的人胚肾293细胞亚群中，OPN明显定位于细胞核。免疫印迹证实了天然OPN的核定位，免疫荧光研究的结果表明核OPN和细胞周期进程之间的关联。流式细胞术显示，细胞核和细胞内OPN含量在S期和G（2）/M期分别显着升高。用DNA聚合酶抑制剂aphidicolin处理细胞阻止细胞周期，并大大降低细胞OPN含量。OPN的细胞内定位与波罗样激酶-1（Plk-1）一致，后者是波罗样激酶家族的成员，其部分通过调节中心体相关事件，是成功的细胞有丝分裂的组成部分.骨桥蛋白和Plk-1共免疫沉淀从核，但不cystoslic，提取物，证明了相互作用，是有限的细胞核，大概在有丝分裂。OPN羧基端的缺失不利于核定位和Plk-1相互作用。OPN表达的增加也与多核293细胞数量的增加有关，而转染COOH末端缺失的OPN使多核细胞的百分比降低到低于基础水平.这些发现暗示核内OPN作为细胞复制过程的参与者。
Osteopontin ( OPN) is a secreted phosphoprotein involved in cellular proliferation and associated with tumor progression. Although an intracellular form of OPN has been described, its function remains unknown. In this study, a novel nuclear location for intracellular OPN and a correlation with cell division were demonstrated. OPN distinctly localized to the nucleus in a subset of transiently transfected human embryonic kidney 293 cells. Immunoblotting confirmed the nuclear location of native OPN, and results from immunofluorescence studies suggested an association between nuclear OPN and cell cycle progression. Flow cytometry revealed that nuclear and cellular OPN content rose significantly during the S and G(2)/M phases, respectively. Treatment of cells with the DNA polymerase inhibitor aphidicolin prevented cell cycling and greatly reduced cellular OPN content. The intracellular location of OPN coincided with polo- like kinase-1 ( Plk-1), a member of the polo- like kinase family, which, in part through their regulation of centrosome- related events, are integral to successful cellular mitosis. OPN and Plk-1 were coimmunoprecipitated from nuclear, but not cystoslic, extracts, demonstrating an interaction that is limited to the nucleus, presumably during mitosis. Deletion of the COOH terminus of OPN militated against nuclear localization and Plk-1 interaction. Elevated expression of OPN was also associated with an increase in the number of multinucleate 293 cells, whereas transfection of the COOH- terminal- deleted OPN decreased the percentage of multinucleate cells below basal levels. These findings implicate intranuclear OPN as a participant in the process of cell duplication.