The role of nucleophosmin in centrosome duplication.
In higher animal cells, duplication of centrosomes is triggered by CDK2/cyclin E-mediated phosphorylation. Nucleophosmin (NPM)/B23, a multifunctional protein, has recently been identified as one of the substrates of CDK2/cyclin E in centrosome duplication. Centrosome-bound NPM/B23 dissociates from centrosome upon phosphorylation by CDK2/cyclin E, which in turn triggers initiation of centriole duplication. Duplicated centrosomes remain free of NPM/B23 till mitosis. When the nuclear membrane breaks down during mitosis, NPM/B23 re-localizes to centrosomes. Upon cytokinesis, each daughter cell receives one centrosome bound by NPM/B23, which again dissociates from the centrosome upon exposure to CDK2/cyclin E at mid-late G1 phase of the next cell cycle. Thus, NPM/B23 would constitute one of the licensing systems for centrosome duplication, ensuring the coordination of centrosome and DNA duplication, which limiting duplication once per cell cycle.
Okuda
Masaru
M
Laboratory of Veterinary Internal Medicine, Faculty of Agriculture, Yamaguchi University, Yoshida 1677-1, Yamaguchi, Japan, 753-8515. okuda@agr.yamaguchi-u.ac.jp
D000818:Animals; D042846:CDC2-CDC28 Kinases; D018385:Centrosome; D019927:Cyclin E / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism / Q000502:physiology*; D000090243:Nucleophosmin; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism
D019927:Cyclin E; D009687:Nuclear Proteins; D000090243:Nucleophosmin; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases