title: Aurora-A and an interacting activator, the LIM protein Ajuba, are required for mitotic commitment in human cells.
abstract: Aurora family kinases contribute to regulation of mitosis. Using RNA interference in synchronized HeLa cells, we now show that Aurora-A is required for mitotic entry. We found that initial activation of Aurora-A in late G2 phase of the cell cycle is essential for recruitment of the cyclin B1-Cdk1 complex to centrosomes, where it becomes activated and commits cells to mitosis. A two-hybrid screen identified the LIM protein Ajuba as an Aurora-A binding protein. Ajuba and Aurora-A interact in mitotic cells and become phosphorylated as they do so. In vitro analyses revealed that Ajuba induces the autophosphorylation and consequent activation of Aurora-A. Depletion of Ajuba prevented activation of Aurora-A at centrosomes in late G2 phase and inhibited mitotic entry. Overall, our data suggest that Ajuba is an essential activator of Aurora-A in mitotic commitment.
mesh_terms: D000818:Animals; D064096:Aurora Kinase A; D064127:Aurora Kinases; D016203:CDC2 Protein Kinase / Q000378:metabolism; D019556:COS Cells; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002460:Cell Line; D018385:Centrosome / Q000648:ultrastructure; D019926:Cyclin B / Q000378:metabolism; D056744:Cyclin B1; D016195:G2 Phase; D017353:Gene Deletion; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D060588:LIM Domain Proteins; D008856:Microscopy, Fluorescence; D008938:Mitosis; D008954:Models, Biological; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D011494:Protein Kinases / Q000378:metabolism / Q000502:physiology*; D017346:Protein Serine-Threonine Kinases; D034622:RNA Interference; D011994:Recombinant Proteins / Q000378:metabolism; D013696:Temperature; D013997:Time Factors; D020798:Two-Hybrid System Techniques; D029867:Xenopus Proteins
chemical_list: C485608:AJUBA protein, human; C119385:Ajuba protein, rat; C534699:CCNB1 protein, human; C534701:Ccnb1 protein, rat; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D018398:Homeodomain Proteins; D060588:LIM Domain Proteins; D011994:Recombinant Proteins; D029867:Xenopus Proteins; D005982:Glutathione Transferase; D011494:Protein Kinases; C112134:AURKA protein, Xenopus; C576920:Aurka protein, rat; D064096:Aurora Kinase A; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase