title: Chromosomal passenger complex hydrodynamics suggests chaperoning of the inactive state by nucleoplasmin/nucleophosmin.
abstract: The chromosomal passenger complex (CPC) is a conserved, essential regulator of cell division. As such, significant anti-cancer drug development efforts have been focused on targeting it, most notably by inhibiting its AURKB kinase subunit. The CPC is activated by AURKB-catalyzed autophosphorylation on multiple subunits, but how this regulates CPC interactions with other mitotic proteins remains unclear. We investigated the hydrodynamic behavior of the CPC inXenopus laevisegg cytosol using sucrose gradient sedimentation and in HeLa cells using fluorescence correlation spectroscopy. We found that autophosphorylation of the CPC decreases its sedimentation coefficient in egg cytosol and increases its diffusion coefficient in live cells, indicating a decrease in mass. Using immunoprecipitation coupled with mass spectrometry and immunoblots, we discovered that inactive, unphosphorylated CPC interacts with nucleophosmin/nucleoplasmin proteins, which are known to oligomerize into pentamers and decamers. Autophosphorylation of the CPC causes it to dissociate from nucleophosmin/nucleoplasmin. We propose that nucleophosmin/nucleoplasmin complexes serve as chaperones that negatively regulate the CPC and/or stabilize its inactive form, preventing CPC autophosphorylation and recruitment to chromatin and microtubules in mitosis.
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA 02114-5701.|Department of Chemistry, Harvard University, Cambridge, MA 02138-2902.
authors.forename: Mariah L
authors.initials: ML
authors.lastname: Hanley
authors.affiliation: John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138-2902.
authors.forename: Tae Yeon
authors.initials: TY
authors.lastname: Yoo
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA 02114-5701.
authors.forename: Matthew
authors.initials: M
authors.lastname: Sonnett
authors.affiliation: John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138-2902.|Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138-2902.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Needleman
authors.affiliation: Department of Systems Biology, Harvard Medical School, Boston, MA 02114-5701 timothy_mitchison@hms.harvard.edu.
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mitchison
mesh_terms: D000818:Animals; D002455:Cell Division; D002843:Chromatin / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D002875:Chromosomes; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D057446:Hydrodynamics; D008870:Microtubules / Q000378:metabolism; D008938:Mitosis; D018832:Molecular Chaperones / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D000090243:Nucleophosmin; D056489:Nucleoplasmins / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism; D014982:Xenopus laevis / Q000378:metabolism
chemical_list: D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D018832:Molecular Chaperones; C000716967:NPM1 protein, human; D009687:Nuclear Proteins; D056489:Nucleoplasmins; D029867:Xenopus Proteins; D000090243:Nucleophosmin