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"Genetic interactions between Brca1 and Gadd45a in centrosome duplication, genetic stability, and neural tube closure."
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Wang X, Wang RH, Li W, Xu X, Hollander MC, Fornace AJ Jr, Deng CX
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Published July 9, 2004
in J Biol Chem
volume 279
.
Pubmed ID:
15123655
Abstract:
GADD45a is a transcription target of the breast tumor suppressor gene BRCA. It was recently shown that mouse embryonic fibroblast cells carrying a targeted deletion of exon 11 of Brca1 (Brca1(Delta11/Delta11)) or a Gadd45A-null mutation (Gadd45a(-/-)) suffer centrosome amplification. To study genetic interactions between these genes during centrosome duplication, we generated Brca1(Delta11/Delta)(11)Gadd45a(-/-) mice by crossing each mutant. We found that all Brca1(Delta11/Delta11)Gadd45a(-/-) embryos at embryonic days 9.5-10.5 were exencephalic and exhibited a high incidence of apoptosis accompanied by altered levels of BAX, BCL-2, and p53. The trigger for these events is likely the genetic instability arising from centrosome amplification that is associated, at least in part, with decreased expression of the NIMA-related kinase NEK2. We demonstrate that small interfering RNA-mediated suppression of Brca1 decreased Nek2 more dramatically in Gadd45a(-/-) cells than in wild-type cells and, conversely, that overexpression of Brca1 and/or Gadd45a up-regulated transcription of Nek2. Furthermore, we show that overexpression of Nek2 in Brca1-specific small interfering RNA-treated wild-type and Gadd45a(-/-) cells repressed abnormal centrosome amplification. These observations suggest that NEK2 plays a role in mediating the actions of BRCA1 and GADD45a in regulating centrosome duplication and in maintaining genetic stability.
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Last modification of this entry: Oct. 6, 2010
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