Phosphorylation by aurora kinase A induces Mdm2-mediated destabilization and inhibition of p53 |
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Authors: | Katayama Hiroshi Sasai Kaori Kawai Hidehiko Yuan Zhi-Min Bondaruk Jolanta Suzuki Fumio Fujii Satoshi Arlinghaus Ralph B Czerniak Bogdan A Sen Subrata |
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Affiliation: | Department of Molecular Pathology, Division of Pathology & Laboratory Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030, USA. |
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Abstract: | Aurora kinase A (also called STK15 and BTAK) is overexpressed in many human cancers. Ectopic overexpression of aurora kinase A in mammalian cells induces centrosome amplification, chromosome instability and oncogenic transformation, a phenotype characteristic of loss-of-function mutations of p53. Here we show that aurora kinase A phosphorylates p53 at Ser315, leading to its ubiquitination by Mdm2 and proteolysis. p53 is not degraded in the presence of inactive aurora kinase A or ubiquitination-defective Mdm2. Destabilization of p53 by aurora kinase A is abrogated in the presence of mutant Mdm2 that is unable to bind p53 and after repression of Mdm2 by RNA interference. Silencing of aurora kinase A results in less phosphorylation of p53 at Ser315, greater stability of p53 and cell-cycle arrest at G2-M. Cells depleted of aurora kinase A are more sensitive to cisplatin-induced apoptosis, and elevated expression of aurora kinase A abolishes this response. In a sample of bladder tumors with wild-type p53, elevated expression of aurora kinase A was correlated with low p53 concentration. We conclude that aurora kinase A is a key regulatory component of the p53 pathway and that overexpression of aurora kinase A leads to increased degradation of p53, causing downregulation of checkpoint-response pathways and facilitating oncogenic transformation of cells. |
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