Aurora-A and an interacting activator, the LIM protein Ajuba, are required for mitotic commitment in human cells.
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.
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
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