title: Aurora-A kinase phosphorylation of Aurora-A kinase interacting protein (AIP) and stabilization of the enzyme-substrate complex.
abstract: Aurora-A is an oncogenic kinase that plays essential roles in mitosis as well as cell survival. Aurora-A interacting protein (AIP) was identified as a negative regulator of Aurora-A with its ectopic over expression inducing destabilization of Aurora-A protein. Here we present evidence that in human cells, contrary to the earlier report, AIP functions in stabilizing rather than destabilizing Aurora-A. Furthermore, AIP is phosphorylated on Serine 70 by Aurora-A but not Aurora-B and expression of phosphorylation mimic mutant of AIP results in prolonged protein stability compared to unphosphorylatable mutant. We observed that when co-expressed with AIP, protein levels of both Aurora-A and Aurora-B are markedly elevated regardless of their kinase activities and phosphorylation state of AIP. Interaction of Aurora kinases with AIP is necessary for this elevated stability. This phenomenon is commonly detected in several human cancer cell lines used in this study. Depletion of AIP by RNA interference decreased Aurora-A but not Aurora-B in two of the three cell lines analyzed, indicating that under physiological condition, AIP functions in stabilization of Aurora-A but not Aurora-B, though this regulation may be dependent on additional factors as well. Further, AIP siRNA induced cell cycle arrest at G2/M, which is consistent with anticipated loss of function of Aurora-A in these cells. Thus, our study provides the first evidence of a role for AIP in G2/M cell cycle progression by cooperatively regulating protein stabilization of its up-stream regulator, Aurora-A kinase through protein-protein interaction as well as protein phosphorylation.
authors.affiliation: Department of Molecular Pathology, Division of Pathology and Laboratory Medicine, The University of Texas M.D. Anderson Cancer Center, Houston, Texas 77054, USA.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katayama
authors.forename: Kaori
authors.initials: K
authors.lastname: Sasai
authors.forename: Bogdan A
authors.initials: BA
authors.lastname: Czerniak
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Carter
authors.forename: Subrata
authors.initials: S
authors.lastname: Sen
mesh_terms: D064107:Aurora Kinase B; D064127:Aurora Kinases; D002453:Cell Cycle; D045744:Cell Line, Tumor; D018076:DNA, Complementary; D004795:Enzyme Stability; D015723:Gene Library; D005822:Genetic Vectors; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D012516:Osteosarcoma / Q000473:pathology; D010766:Phosphorylation; D011233:Precipitin Tests; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity; D014162:Transfection
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D012694:Serine; D005982:Glutathione Transferase; C576921:AURKB protein, human; D064107:Aurora Kinase B; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases