Depletion of nucleophosmin leads to distortion of nucleolar and nuclear structures in HeLa cells.
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.
Amin
Mohammed Abdullahel
MA
Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Osaka, Japan.
Matsunaga
Sachihiro
S
Uchiyama
Susumu
S
Fukui
Kiichi
K
D002466:Cell Nucleolus / Q000378:metabolism / Q000648:ultrastructure*; D002467:Cell Nucleus / Q000378:metabolism / Q000648:ultrastructure*; D006367:HeLa Cells; D006801:Humans; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D000090243:Nucleophosmin; D034622:RNA Interference
C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D000090243:Nucleophosmin