Gadd45a Interacts with Aurora-A and Inhibits Its Kinase Activity

Abstract

Centrosome stability is required for successful mitosis in mammalian cells. Amplification of the centrosome leads to chromosomal missegregation and generation of aneuploidy, which are closely associated with cell transformation and tumorigenesis (Doxsey, S. J. (2001) Nat. Cell Biol. 3, E105-E108; Hinchcliffe, E. H., and Sluder, G. (2001) Genes Dev. 15, 1167-1181; Pihan, G. A., Purohit, A., Wallace, J., Malhotra, R., Liotta, L., and Doxsey, S. J. (2001) Cancer Res. 61, 2212-2219). However, there are currently limited insights into mechanism(s) for this critical biological event. Here we show that Gadd45a, a DNA damage-inducible protein that is regulated by tumor suppressors p53 and BRCA1, participates in the maintenance of centrosome stability. Mouse embryonic fibroblasts derived from gadd45a knock-out mice exhibit centrosome amplification (designated as increased centrosome numbers). Introduction of exogenous Gadd45a into mouse embryonic fibroblasts isolated from gadd45a-null mice substantially restored the normal centrosome profile. In contrast to p21waf1/cip1, which ensures coordinated initiation of centrosome, Gadd45a had no significant effect on centrosome duplication in S phase. Interestingly Gadd45a was found to physically associate with Aurora-A protein kinase, whose deregulated expression results in centrosome abnormality. Furthermore Gadd45a was demonstrated to strongly inhibit Aurora-A kinase activity and to antagonize Aurora-A-induced centrosome amplification. These findings identify a novel mechanism for Gadd45a in the maintenance of centrosome stability and broaden understandings of p53- and BRCA1-regulated signaling pathways in maintaining genomic fidelity. Centrosome stability is required for successful mitosis in mammalian cells. Amplification of the centrosome leads to chromosomal missegregation and generation of aneuploidy, which are closely associated with cell transformation and tumorigenesis (Doxsey, S. J. (2001) Nat. Cell Biol. 3, E105-E108; Hinchcliffe, E. H., and Sluder, G. (2001) Genes Dev. 15, 1167-1181; Pihan, G. A., Purohit, A., Wallace, J., Malhotra, R., Liotta, L., and Doxsey, S. J. (2001) Cancer Res. 61, 2212-2219). However, there are currently limited insights into mechanism(s) for this critical biological event. Here we show that Gadd45a, a DNA damage-inducible protein that is regulated by tumor suppressors p53 and BRCA1, participates in the maintenance of centrosome stability. Mouse embryonic fibroblasts derived from gadd45a knock-out mice exhibit centrosome amplification (designated as increased centrosome numbers). Introduction of exogenous Gadd45a into mouse embryonic fibroblasts isolated from gadd45a-null mice substantially restored the normal centrosome profile. In contrast to p21waf1/cip1, which ensures coordinated initiation of centrosome, Gadd45a had no significant effect on centrosome duplication in S phase. Interestingly Gadd45a was found to physically associate with Aurora-A protein kinase, whose deregulated expression results in centrosome abnormality. Furthermore Gadd45a was demonstrated to strongly inhibit Aurora-A kinase activity and to antagonize Aurora-A-induced centrosome amplification. These findings identify a novel mechanism for Gadd45a in the maintenance of centrosome stability and broaden understandings of p53- and BRCA1-regulated signaling pathways in maintaining genomic fidelity. The essence of successful mitosis in mammalian cells is the generation of two genetically identical daughter cells. This requires the assembly of a strictly bipolar mitotic apparatus that will ensure that all daughter chromosomes are segregated to opposite sides of the cell before the completion of mitosis. This process is controlled by the centrosomes that organize the spindle poles during mitosis. In a manner similar to the chromosomal DNA of a cell, centrosomes replicate only once per cell cycle, generating two centrosomes, which then form the two poles of the mitotic spindle. If the centrosome duplicates more than once in a cell cycle then a multiple spindle may be assembled, and the chromosomes may be unequally distributed to the daughter cells, leading to genetic imbalances that generate genomic instability and produce cells with aggressive growth characteristics. Therefore, centrosome abnormalities may result in chromosomal missegregation and generation of aneuploidy, which are closely associated with cell transformation and tumorigenesis (1Doxsey S.J. Nat. Cell Biol. 2001; 3: E105-E108Crossref PubMed Scopus (81) Google Scholar, 2Hinchcliffe E.H. Sluder G. Genes Dev. 2001; 15: 1167-1181Crossref PubMed Scopus (227) Google Scholar, 3Pihan G.A. Purohit A. Wallace J. Malhotra R. Liotta L. Doxsey S.J. Cancer Res. 2001; 61: 2212-2219PubMed Google Scholar, 4Raff J.W. Curr. Biol. 2001; 11: R159-R161Abstract Full Text Full Text PDF PubMed Scopus (26) Google Scholar). Centrosome amplification has been linked to numerous genetic aberrations (5Salisbury J.L. Whitehead C.M. Lingle W.L. Barrett S.L. Biol. Cell. 1999; 91: 451-460Crossref PubMed Google Scholar, 6Duensing S. Munger K. Biochim. Biophys. Acta. 2001; 2: M81-M88Google Scholar), including the loss of the tumor suppressor protein p53 (7Fukasawa K. Choi T. Kuriyama R. Rulong S. Vande Woude G.F. Science. 1996; 271: 1744-1747Crossref PubMed Scopus (727) Google Scholar, 8Chiba S. Okuda M. Mussman J.G. Fukasawa K. Exp. Cell Res. 2000; 258: 310-321Crossref PubMed Scopus (53) Google Scholar) or disruption of its downstream target genes such as p21 (9Tarapore P. Horn H.F. Tokuyama Y. Fukasawa K. Oncogene. 2001; 20: 3173-3184Crossref PubMed Scopus (125) Google Scholar, 10Tokuyama Y. Horn H.F. Kawamura K. Tarapore P. Fukasawa K. J. Biol. Chem. 2001; 276: 21529-21537Abstract Full Text Full Text PDF PubMed Scopus (185) Google Scholar) and GADD45a (11Hollander M.C. Sheikh M.S. Bulavin D.V. Lundgren K. Augeri-Henmueller L. Shehee R. Molinaro T.A. Kim K.E. Tolosa E. Ashwell J.D. Rosenberg M.P. Zhan Q. Fernandez-Salguero P.M. Morgan W.F. Deng C.X. Fornace Jr., A.J. Nat. Genet. 1999; 23: 176-184Crossref PubMed Scopus (440) Google Scholar). Mouse embryonic fibroblasts (MEFs) 3The abbreviations used are: MEF, mouse embryonic fibroblast; MMS, methyl methanesulfonate; GFP, green fluorescent protein; GST, glutathione S-transferase; ERK, extracellular signal-regulated kinase; FBS, fetal bovine serum; CHO, Chinese hamster ovary; PBS, phosphate-buffered saline; MBP, myelin basic protein; p21, p21waf1/cip1. 3The abbreviations used are: MEF, mouse embryonic fibroblast; MMS, methyl methanesulfonate; GFP, green fluorescent protein; GST, glutathione S-transferase; ERK, extracellular signal-regulated kinase; FBS, fetal bovine serum; CHO, Chinese hamster ovary; PBS, phosphate-buffered saline; MBP, myelin basic protein; p21, p21waf1/cip1. derived from gadd45a-null mice display aneuploidy, chromosomal aberrations, gene amplification, and centrosome amplification (11Hollander M.C. Sheikh M.S. Bulavin D.V. Lundgren K. Augeri-Henmueller L. Shehee R. Molinaro T.A. Kim K.E. Tolosa E. Ashwell J.D. Rosenberg M.P. Zhan Q. Fernandez-Salguero P.M. Morgan W.F. Deng C.X. Fornace Jr., A.J. Nat. Genet. 1999; 23: 176-184Crossref PubMed Scopus (440) Google Scholar). Other genetic alterations reported to affect centrosome numbers concern proteins involved in the response to DNA damage, including BRCA1 (12Hsu L.C. White R.L. Proc. Natl. Acad. Sci. U. S. A. 1998; 95: 12983-12988Crossref PubMed Scopus (270) Google Scholar), BRCA2 (13Tutt A. Gabriel A. Bertwistle D. Connor F. Paterson H. Peacock J. Ross G. Ashworth A. Curr. Biol. 1999; 9: 1107-1110Abstract Full Text Full Text PDF PubMed Scopus (258) Google Scholar), and ATR (14Smith L. Liu S.J. Goodrich L. Jacobson D. Degnin C. Bentley N. Carr A. Flaggs G. Keegan K. Hoekstra M. Thayer M.J. Nat. Genet. 1998; 19: 39-46Crossref PubMed Scopus (71) Google Scholar). In addition, several protein kinases have been implicated in the centrosome cycle, particularly in centrosome amplification. These include Aurora-A kinase, Aurora-B kinase (15Giet R. Prigent C. J. Cell Sci. 1999; 112: 3591-3601Crossref PubMed Google Scholar, 16Zhou H. Kuang J. Zhong L. Kuo W.L. Gray J.W. Sahin A. Brinkley B.R. Sen S. Nat. Genet. 1998; 20: 189-193Crossref PubMed Scopus (1140) Google Scholar, 17Takahashi T. Futamura M. Yoshimi N. Sano J. Katada M. Takagi Y. Kimura M. Yoshioka T. Okano Y. Saji S. Jpn. J. Cancer Res. 2000; 91: 1007-1014Crossref PubMed Scopus (105) Google Scholar), Polo kinase 1 (18do Carmo Avides M. Tavares A. Glover D.M. Nat. Cell Biol. 2001; 3: 421-424Crossref PubMed Scopus (114) Google Scholar, 19Donaldson M.M. Tavares A.A. Hagan I.M. Nigg E.A. Glover D.M. J. Cell Sci. 2001; 114: 2357-2358Crossref PubMed Google Scholar, 20Goepfert T.M. Brinkley B.R. Curr. Top. Dev. Biol. 2000; 49: 331-342Crossref PubMed Google Scholar), and NIMA-related kinase 2 (21Fry A.M. Meraldi P. Nigg E.A. EMBO J. 1998; 17: 470-481Crossref PubMed Scopus (342) Google Scholar, 22Fry A.M. Descombes P. Twomey C. Bacchieri R. Nigg E.A. J. Cell Sci. 2000; 113: 1973-1984PubMed Google Scholar, 23Ha Kim Y. Yeol Choi J. Jeong Y. Wolgemuth D.J. Rhee K. Biochem. Biophys. Res. Commun. 2002; 290: 730-736Crossref PubMed Scopus (41) Google Scholar). It has been reported that overexpression of Aurora-A kinase results in centrosome hypertrophy (16Zhou H. Kuang J. Zhong L. Kuo W.L. Gray J.W. Sahin A. Brinkley B.R. Sen S. Nat. Genet. 1998; 20: 189-193Crossref PubMed Scopus (1140) Google Scholar). The precise function of Aurora-A is not known, but it may be involved in centrosome separation, spindle assembly, and spindle maintenance. Furthermore Aurora-A is considered as an oncogene and is capable of conferring transformed phenotypes to non-oncogenic cells (16Zhou H. Kuang J. Zhong L. Kuo W.L. Gray J.W. Sahin A. Brinkley B.R. Sen S. Nat. Genet. 1998; 20: 189-193Crossref PubMed Scopus (1140) Google Scholar). Interestingly absence of p53 appears to exacerbate the Aurora-A-induced centrosome amplification, providing a plausible explanation for why cells with inactivated p53 function display increased centrosome numbers (8Chiba S. Okuda M. Mussman J.G. Fukasawa K. Exp. Cell Res. 2000; 258: 310-321Crossref PubMed Scopus (53) Google Scholar, 24Meraldi P. Honda R. Nigg E.A. EMBO J. 2002; 21: 483-492Crossref PubMed Scopus (572) Google Scholar). GADD45a is a p53- and BRCA1-regulated stress gene and is highly induced by a variety of genotoxic agents, such as methyl methanesulfonate (MMS), UV radiation, and hydroxyurea (25Fornace Jr., A.J. Alamo Jr., I. Hollander M.C. Proc. Natl. Acad. Sci. U. S. A. 1988; 85: 8800-8804Crossref PubMed Scopus (560) Google Scholar). In addition to the response to base-damaging agents and certain other stress-related growth arrest treatments including hypoxia and growth factor withdraw, the human GADD45a gene is induced by ionizing radiation (26Papathanasiou M.A. Kerr N.C. Robbins J.H. McBride O.W. Alamo Jr., I. Barrett S.F. Hickson I.D. Fornace Jr., A.J. Mol. Cell. Biol. 1991; 11: 1009-1016Crossref PubMed Scopus (249) Google Scholar). The ionizing radiation induction of GADD45a is transcriptionally dependent on cellular p53 function. Recently GADD45a has been characterized as a downstream gene of BRCA1 (27Harkin D.P. Bean J.M. Miklos D. Song Y.H. Truong V.B. Englert C. Christians F.C. Ellisen L.W. Maheswaran S. Oliner J.D. Haber D.A. Cell. 1999; 97: 575-586Abstract Full Text Full Text PDF PubMed Scopus (512) Google Scholar, 28Jin S. Zhao H. Fan F. Blanck P. Fan W. Colchagie A.B. Fornace Jr, A.J. Zhan Q. Oncogene. 2000; 19: 4050-4057Crossref PubMed Scopus (85) Google Scholar), a breast cancer-associated gene that plays roles in the control of cell cycle progression, apoptosis, DNA repair, and gene Gadd45a is an and It physically to multiple cellular including cell protein kinase, and an of the protein kinase The of Gadd45a with that Gadd45a may be involved in the control of cell cycle progression, DNA repair, and the of signaling GADD45a has been implicated in maintenance of genomic the precise mechanism(s) to be findings have demonstrated that the derived from gadd45a knock-out mice exhibit aneuploidy, chromosomal aberrations, gene amplification, and centrosome amplification. In addition, gadd45a-null mice are to DNA including induced by ionizing radiation, UV radiation and Interestingly Gadd45a has been to to tumor and In this we that with Gadd45a exhibit centrosome amplification as by increased centrosome Gadd45a was found to physically associate with Aurora-A The Gadd45a and Aurora-A was to strongly inhibit Aurora-A kinase These a Gadd45a and centrosome a for Gadd45a in the maintenance of genomic fidelity. and Gadd45a expression Q. M.J. F. Fornace Jr., A.J. Oncogene. 1999; PubMed Scopus Google Scholar, S. M.J. Zhao H. Fan F. Colchagie A.B. Blanck P. Fornace Jr., A.J. Zhan Q. J. Biol. Chem. 2000; Full Text Full Text PDF PubMed Scopus Google Scholar). and are the expression for by of the from human for GADD45a and The into the in downstream from and by of p21, and p53 into of These green fluorescent proteins was by the of Aurora-A into of Aurora-A was by the of Aurora-A into of was by GADD45a into the of the and by into the of was by the of The used in the Gadd45a, and by Aurora-A was from Cell Cell and derived from normal and gadd45a knock-out mice in with fetal bovine human fibroblasts in with cells and Chinese hamster cells in with cell or cells 1 to In of DNA and of to of in The to for with of and to the for of with and was the and cells Cell UV cells in with and with UV radiation a of cell to UV radiation, was in and the cells in the cells in a of for was and cells the and cells with PBS, and in 2 2 and by and by of cellular protein by and to for 1 in with with and with the for 2 in and was in 1 and by and to cellular with of the and of protein for as protein expression was as with for protein by and in 1 with with and and to with a of the with several with PBS, proteins for in the of human fibroblasts in cells with in for and with with by and bovine in for with to and Gadd45a, and with or with PBS, cells an and a with to and with with PBS, cells a Aurora-A cells in with and with of Aurora-A expression cells for of cellular of cell with of for and the Aurora-A proteins with the of and then in the of of myelin basic protein and of in the with an of protein by and by In 1 of cellular protein was by to and kinase as then Centrosome Amplification in addition to its in the control of cell cycle DNA damage, have demonstrated that Gadd45a is involved in the maintenance of chromosomal and centrosome stability (11Hollander M.C. Sheikh M.S. Bulavin D.V. Lundgren K. Augeri-Henmueller L. Shehee R. Molinaro T.A. Kim K.E. Tolosa E. Ashwell J.D. Rosenberg M.P. Zhan Q. Fernandez-Salguero P.M. Morgan W.F. Deng C.X. Fornace Jr., A.J. Nat. Genet. 1999; 23: 176-184Crossref PubMed Scopus (440) Google Scholar). the of Gadd45a on genomic the derived from or gadd45a-null mice used for of centrosome on and with which is with centrosome numbers then It be that in addition to the to was used to that are centrosomes, and we found that similar results not in isolated from mice or two However, from gadd45a-null mice more than two The results are in of cells display centrosome amplification as centrosome or than per with of centrosome amplification. These results that disruption of gadd45a results in overexpression of Gadd45a protein in cells normal centrosome a expression that was into cells. cells with and centrosomes in cells. in with of cells or more than of expression into centrosomes by that expression of exogenous Gadd45a substantially restored the normal centrosome in In the p21, a was p21 has been characterized as a in centrosome duplication and of cellular p21 centrosome overexpression of p21 in cells not centrosome that p21 and Gadd45a on involved in the process of centrosome However, of p53 expression into centrosome exogenous of proteins p21, and we cellular and found that proteins in cells was overexpression of Gadd45a in cells, and no cell was in the not Gadd45a Centrosome in S amplification has been to S and mitotic (8Chiba S. Okuda M. Mussman J.G. Fukasawa K. Exp. Cell Res. 2000; 258: 310-321Crossref PubMed Scopus (53) Google Scholar, P. Horn H.F. Tokuyama Y. Fukasawa K. Oncogene. 2001; 20: 3173-3184Crossref PubMed Scopus (125) Google Scholar, 16Zhou H. Kuang J. Zhong L. Kuo W.L. Gray J.W. Sahin A. Brinkley B.R. Sen S. Nat. Genet. 1998; 20: 189-193Crossref PubMed Scopus (1140) Google Scholar, 24Meraldi P. Honda R. Nigg E.A. EMBO J. 2002; 21: 483-492Crossref PubMed Scopus (572) Google Scholar). The is associated with centrosome that is by kinase and the is associated with that be to of kinases or numbers of have demonstrated that p21 plays a critical in centrosome in S its of the have that Gadd45a has no effect on kinase, we Gadd45a on S centrosome amplification or expression into cells and cells S which is a of DNA by more than of cells increased centrosome numbers or than Introduction of p21 expression substantially centrosome amplification. In the of p21 cells centrosome from to that p21 kinase and then ensures coordinated initiation of In Gadd45a had no significant effect on centrosome amplification, that Gadd45a not on centrosome duplication S phase. These results are with the findings in that p21 and Gadd45a on involved in centrosome stability. Gadd45a with have demonstrated that Gadd45a is a kinase a the of Gadd45a in maintenance of centrosome stability be its with certain involved in centrosome a we of the of which is Aurora-A kinase, which is a in centrosome and deregulated expression of Aurora-A has been to result in centrosome to the of Gadd45a with In cells with Gadd45a and cellular with a of Gadd45a was by as as by and which reported to with In and not Gadd45a protein was with cell from cells and by in Aurora-A protein was in a was by cellular Gadd45a and proteins was and proteins with cellular isolated from cells, which of and which of Gadd45a and by In and to Gadd45a, but or not associate with cellular the Gadd45a and Aurora-A proteins from cells with UV radiation and with in Gadd45a protein was highly induced cell to UV radiation by the to Gadd45a was Interestingly the Gadd45a and Aurora-A proteins by DNA increased of Gadd45a protein in Aurora-A UV the to was in the Gadd45a and Aurora-A proteins not in results a of Gadd45a with Gadd45a Aurora-A kinase activity of Aurora-A is closely associated with Aurora-A-induced centrosome abnormalities the that overexpression of Aurora-A kinase the control of centrosome Interestingly overexpression of Aurora-A or a of the kinase in or cells leads to more aggressive but that was not the an Aurora-A was that activity of Aurora-A is with genomic instability and Gadd45a protein Aurora-A Aurora-A expression was into cells. cells for of protein Aurora-A protein was with and then an in kinase was in the of and In the Aurora-A kinase of protein In addition, protein and protein in the in of Gadd45a protein on Aurora-A kinase The Gadd45a of Aurora-A activity was the addition of of Aurora-A activity to be In and not effect on Aurora-A kinase and Aurora-A for and by kinase These kinase activity or as of proteins in of for and Aurora-A kinases but not affect kinase that Gadd45a of Aurora-A is a It be that the to Aurora-A Gadd45a but to results not the that the of by Aurora-A be to of Gadd45a with the effect of Gadd45a on cellular Aurora-A in Aurora-A kinase activity was in derived from and gadd45a-null mice of with UV radiation and which are agents and highly cellular Gadd45a Cell and with to kinase was then in the of and in the of Aurora-A kinase activity similar in UV radiation or a in Aurora-A kinase but from gadd45a-null mice not display significant on Aurora-A kinase It be that of Aurora-A used in the kinase as the of with with the findings in and results that Gadd45a Aurora-A kinase Gadd45a Aurora-A-induced Centrosome was that deregulated expression of Aurora-A results in centrosome the effect of Gadd45a on Aurora-A-induced centrosome amplification, cells with or expression and centrosome in cells centrosome amplification as by the that of cells Aurora-A or than In only of cells increased centrosome numbers or than centrosomes per However, was with a Gadd45a expression the cells increased centrosome numbers from to but of p21 was to Aurora-A-induced centrosome amplification. These that Gadd45a induction of centrosome amplification by GADD45a is a downstream target gene for p53 and BRCA1 and is highly induced by a of genotoxic agents, including ionizing radiation, MMS, and UV radiation (25Fornace Jr., A.J. Alamo Jr., I. Hollander M.C. Proc. Natl. Acad. Sci. U. S. A. 1988; 85: 8800-8804Crossref PubMed Scopus (560) Google Scholar). In addition to its roles in the control of cell cycle and induction of apoptosis, Gadd45a appears to be of the in centrosome stability. derived from gadd45a-null mice display aneuploidy, chromosomal aberrations, and gene amplification (11Hollander M.C. Sheikh M.S. Bulavin D.V. Lundgren K. Augeri-Henmueller L. Shehee R. Molinaro T.A. Kim K.E. Tolosa E. Ashwell J.D. Rosenberg M.P. Zhan Q. Fernandez-Salguero P.M. Morgan W.F. Deng C.X. Fornace Jr., A.J. Nat. Genet. 1999; 23: 176-184Crossref PubMed Scopus (440) Google Scholar). The that with Gadd45a increased centrosome and that Gadd45a plays a critical in the maintenance of centrosome stability. cell cycle that cell or a that cells mitotic and centrosome numbers but found that centrosome amplification in cells in all and was of cell cycle not In of expression of exogenous Gadd45a in cells was to normal centrosome centrosome abnormalities are associated with the that disruption of Gadd45a leads to centrosome amplification in for of the knock-out to DNA by ionizing radiation, UV radiation, and Centrosome abnormalities are linked to genetic alterations in the tumor suppressors p53 and p53 with Aurora-A kinase and its kinase In addition, the p21, a of cell cycle has been to centrosome its of In contrast to characterized mechanism(s) by which p53 plays an in maintenance of centrosome the that the of BRCA1 in normal centrosome is currently BRCA1 has been to centrosome its with a of the by and by have demonstrated that GADD45a is transcriptionally by BRCA1 in a that Gadd45a the of BRCA1 in the control of genomic and cell cycle Recently genetic BRCA1 and Gadd45a characterized by genetic of BRCA1 and Gadd45a W. Hollander M.C. Fornace Jr., A.J. Deng C.X. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar). centrosome amplification was to in the mice with this effect that the BRCA1 and Gadd45a in centrosome duplication is not BRCA1 plays a function not only Gadd45a, this BRCA1 downstream target gene be to in the of BRCA1 in centrosome GADD45a and p21 are transcriptionally by p53 and roles in the control of cell cycle However, two proteins to on of the cell p21 has been demonstrated to of and function in the initiation of centrosome In Gadd45a on Aurora-A kinase to ensure centrosome or completion of that Gadd45a and cell into Gadd45a centrosome stability its effect on Aurora-A and the have the pathways involved in the control of centrosome stability. protein kinases have been implicated in the centrosome cycle, particularly in centrosome amplification. These include Aurora-A kinase, Aurora-B kinase (15Giet R. Prigent C. J. Cell Sci. 1999; 112: 3591-3601Crossref PubMed Google Scholar, 16Zhou H. Kuang J. Zhong L. Kuo W.L. Gray J.W. Sahin A. Brinkley B.R. Sen S. Nat. Genet. 1998; 20: 189-193Crossref PubMed Scopus (1140) Google Scholar, 17Takahashi T. Futamura M. Yoshimi N. Sano J. Katada M. Takagi Y. Kimura M. Yoshioka T. Okano Y. Saji S. Jpn. J. Cancer Res. 2000; 91: 1007-1014Crossref PubMed Scopus (105) Google Scholar), kinase 1 (18do Carmo Avides M. Tavares A. Glover D.M. Nat. Cell Biol. 2001; 3: 421-424Crossref PubMed Scopus (114) Google Scholar, 19Donaldson M.M. Tavares A.A. Hagan I.M. Nigg E.A. Glover D.M. J. Cell Sci. 2001; 114: 2357-2358Crossref PubMed Google Scholar, 20Goepfert T.M. Brinkley B.R. Curr. Top. Dev. Biol. 2000; 49: 331-342Crossref PubMed Google Scholar), and NIMA-related kinase 2 (21Fry A.M. Meraldi P. Nigg E.A. EMBO J. 1998; 17: 470-481Crossref PubMed Scopus (342) Google Scholar, 22Fry A.M. Descombes P. Twomey C. Bacchieri R. Nigg E.A. J. Cell Sci. 2000; 113: 1973-1984PubMed Google Scholar, 23Ha Kim Y. Yeol Choi J. Jeong Y. Wolgemuth D.J. Rhee K. Biochem. Biophys. Res. Commun. 2002; 290: 730-736Crossref PubMed Scopus (41) Google Scholar). of Aurora-A kinase results in centrosome hypertrophy (16Zhou H. Kuang J. Zhong L. Kuo W.L. Gray J.W. Sahin A. Brinkley B.R. Sen S. Nat. Genet. 1998; 20: 189-193Crossref PubMed Scopus (1140) Google Scholar). The precise function of Aurora-A is not known, but it may be involved in centrosome separation, spindle assembly, and spindle maintenance. Furthermore Aurora-A is considered as an oncogene and is capable of conferring transformed phenotypes to non-oncogenic cells (16Zhou H. Kuang J. Zhong L. Kuo W.L. Gray J.W. Sahin A. Brinkley B.R. Sen S. Nat. Genet. 1998; 20: 189-193Crossref PubMed Scopus (1140) Google Scholar). In the we a effect of Gadd45a on Aurora-A kinase activity of protein in of Aurora-A activity and Interestingly UV radiation or derived from mice a of Aurora-A kinase the was in the cells with Gadd45a, that Gadd45a of Aurora-A is in response to DNA The Gadd45a of Aurora-A kinase activity is to be its with Aurora-A Gadd45a has been to physically associate with whose activity is required for the Gadd45a and or Aurora-A to be The is characterized the of Gadd45a, but was found to be the of the Gadd45a protein not overexpression of Aurora-A leads to centrosome This was by the in hamster cells with Aurora-A expression with the that Gadd45a Aurora-A kinase activity the Aurora-A-induced centrosome amplification was by of Gadd45a, but expression of p21 had no effect on centrosome abnormality. the that centrosome amplification in cells with Gadd45a is with which to of results the that the to results in centrosome amplification in addition to of of centrosome in J. Fornace and M. Hollander the of for providing with gadd45a knock-out In addition, we Sen the of M. D. Cancer for providing with Aurora-A