Human TPX2 Is Required for Targeting Aurora-A Kinase to the Spindle

• Published in: The Journal of cell biology Vol. 158; no. 4; pp. 617 - 623
• Main Authors: Kufer, Thomas A., Herman H. W. Silljé, Körner, Roman, Gruss, Oliver J., Meraldi, Patrick, Nigg, Erich A.
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 19.08.2002; The Rockefeller University Press
• Subjects: Antibodies; Aurora Kinases; Cell biology; Cell cycle; Cell Cycle Proteins; Cell division; Cells; Cellular biology; Centrosomes; DNA; Enzyme Activation; Enzymes; HeLa Cells; Humans; Macromolecular Substances; Mass spectroscopy; Microtubule-Associated Proteins - physiology; Microtubules - metabolism; Microtubules - physiology; Mitosis - physiology; Mitotic spindle apparatus; Neoplasm Proteins; Nuclear Proteins; Phosphoproteins; Precipitin Tests; Protein Binding - drug effects; Protein Kinases - physiology; Protein-Serine-Threonine Kinases; RNA, Small Interfering; RNA, Untranslated - pharmacology; Small interfering RNA; Spindle Apparatus - physiology; Substrate Specificity; Xenopus Proteins
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.200204155

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.