title: Regulation of Greatwall kinase by protein stabilization and nuclear localization.
abstract: Greatwall (Gwl) functions as an essential mitotic kinase by antagonizing protein phosphatase 2A. In this study we identified Hsp90, Cdc37 and members of the importin α and β families as the major binding partners of Gwl. Both Hsp90/Cdc37 chaperone and importin complexes associated with the N-terminal kinase domain of Gwl, whereas an intact glycine-rich loop at the N-terminus of Gwl was essential for binding of Hsp90/Cdc37 but not importins. We found that Hsp90 inhibition led to destabilization of Gwl, a mechanism that may partially contribute to the emerging role of Hsp90 in cell cycle progression and the anti-proliferative potential of Hsp90 inhibition. Moreover, in agreement with its importin association, Gwl exhibited nuclear localization in interphase Xenopus S3 cells, and dynamic nucleocytoplasmic distribution during mitosis. We identified KR456/457 as the locus of importin binding and the functional NLS of Gwl. Mutation of this site resulted in exclusion of Gwl from the nucleus. Finally, we showed that the Gwl nuclear localization is indispensable for the biochemical function of Gwl in promoting mitotic entry.
authors.affiliation: a Department of Oral Biology ; University of Nebraska Medical Center ; Lincoln , NE USA.
authors.forename: Tomomi M
authors.initials: TM
authors.lastname: Yamamoto
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Laura A
authors.initials: LA
authors.lastname: Fisher
authors.forename: Frank D
authors.initials: FD
authors.lastname: Eckerdt
authors.forename: Aimin
authors.initials: A
authors.lastname: Peng
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000235:genetics* / Q000378:metabolism; D004330:Drosophila / Q000235:genetics; D029721:Drosophila Proteins / Q000096:biosynthesis / Q000235:genetics*; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008938:Mitosis / Q000235:genetics; D009865:Oocytes / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D054648:Protein Phosphatase 2 / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics*; D014982:Xenopus laevis / Q000235:genetics; D028901:alpha Karyopherins / Q000378:metabolism
chemical_list: D029721:Drosophila Proteins; D018841:HSP90 Heat-Shock Proteins; D028901:alpha Karyopherins; C087978:karyopherin alpha 2; C490167:Gwl protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D054648:Protein Phosphatase 2
keywords: CDK, cyclin-dependent kinase; GVBD, germinal vesicle breakdown; Greatwall kinase; Gwl, Greatwall; HSP, heat shock protein; Hsp90; IP, immunoprecipitation; MPF, maturation-promoting factor; NLS, nuclear localization signal; Nuclear localization; importin; mitosis