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Cell cycle regulation of Greatwall kinase nuclear localization facilitates mitotic progression.

Wang P, Galan JA, Normandin K, Bonneil E, Hickson GR, Roux PP, Thibault P, Archambault V

Institut de recherche en immunologie et en cancérologie, 2 Department of Biochemistry, 3 Department of Pathology and Cell Biology, 4 Centre de recherche CHU Ste-Justine, and 5 Department of Chemistry, Université de Montréal, Montréal, Québec H3C 3J7, Canada.

Cell division requires the coordination of critical protein kinases and phosphatases. Greatwall (Gwl) kinase activity inactivates PP2A-B55 at mitotic entry to promote the phosphorylation of cyclin B-Cdk1 substrates, but how Gwl is regulated is poorly understood. We found that the subcellular localization of Gwl changed dramatically during the cell cycle in Drosophila. Gwl translocated from the nucleus to the cytoplasm in prophase. We identified two critical nuclear localization signals in the central, poorly characterized region of Gwl, which are required for its function. The Polo kinase associated with and phosphorylated Gwl in this region, promoting its binding to 14-3-3ε and its localization to the cytoplasm in prophase. Our results suggest that cyclin B-Cdk1 phosphorylation of Gwl is also required for its nuclear exclusion by a distinct mechanism. We show that the nucleo-cytoplasmic regulation of Gwl is essential for its functions in vivo and propose that the spatial regulation of Gwl at mitotic entry contributes to the mitotic switch.

J. Cell Biol. 2013;202(2):277-93.

Pubmed ID: 23857770

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