title: Human TPX2 is required for targeting Aurora-A kinase to the spindle.
abstract: Aurora-A is a serine-threonine kinase implicated in the assembly and maintenance of the mitotic spindle. Here we show that human Aurora-A binds to TPX2, a prominent component of the spindle apparatus. TPX2 was identified by mass spectrometry as a major protein coimmunoprecipitating specifically with Aurora-A from mitotic HeLa cell extracts. Conversely, Aurora-A could be detected in TPX2 immunoprecipitates. This indicates that subpopulations of these two proteins undergo complex formation in vivo. Binding studies demonstrated that the NH2 terminus of TPX2 can directly interact with the COOH-terminal catalytic domain of Aurora-A. Although kinase activity was not required for this interaction, TPX2 was readily phosphorylated by Aurora-A. Upon siRNA-mediated elimination of TPX2 from cells, the association of Aurora-A with the spindle microtubules was abolished, although its association with spindle poles was unaffected. Conversely, depletion of Aurora-A by siRNA had no detectable influence on the localization of TPX2. We propose that human TPX2 is required for targeting Aurora-A kinase to the spindle apparatus. In turn, Aurora-A might regulate the function of TPX2 during spindle assembly.
authors.affiliation: Department of Cell Biology, Max Planck Institute of Biochemistry, Am Klopferspitz 18a, D-82152 Martinsried, Germany.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Kufer
authors.forename: Herman H W
authors.initials: HH
authors.lastname: Silljé
authors.forename: Roman
authors.initials: R
authors.lastname: Körner
authors.forename: Oliver J
authors.initials: OJ
authors.lastname: Gruss
authors.forename: Patrick
authors.initials: P
authors.lastname: Meraldi
authors.forename: Erich A
authors.initials: EA
authors.lastname: Nigg
mesh_terms: D064127:Aurora Kinases; D018797:Cell Cycle Proteins; D004789:Enzyme Activation; D006367:HeLa Cells; D006801:Humans; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins / Q000502:physiology*; D008870:Microtubules / Q000378:metabolism* / Q000502:physiology*; D008938:Mitosis / Q000502:physiology*; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D011233:Precipitin Tests; D011485:Protein Binding / Q000187:drug effects; D011494:Protein Kinases / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering; D022661:RNA, Untranslated / Q000494:pharmacology; D008941:Spindle Apparatus / Q000502:physiology*; D013379:Substrate Specificity; D029867:Xenopus Proteins
chemical_list: D018797:Cell Cycle Proteins; D046911:Macromolecular Substances; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D034741:RNA, Small Interfering; D022661:RNA, Untranslated; C122167:TPX2 protein, human; D029867:Xenopus Proteins; D011494:Protein Kinases; C112134:AURKA protein, Xenopus; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases