Genomic instability in Gadd45a-/- cells is coupled with S-phase checkpoint defects

M. C. Hollander, R. T. Philburn, A. D. Patterson, M. A. Wyatt, A. J. Fornace

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Gadd45a is a p53-regulated gene whose protein product, like p53, is involved in maintenance of genome stability. Specifically, deletion of Gadd45a leads to extensive aneuploidy as a consequence of centrosome amplification and subsequent abnormal segregation of chromosomes during mitosis. S-phase checkpoints were investigated in Gadd45a-/- cells to determine possible defects contributing to the uncoupling of centrosome duplication and DNA replication. In the presence of hydroxyurea, Gadd45a-/- mouse embryo fibroblasts show increased centrosome amplification coupled with loss of a sustained S-phase checkpoint. Gadd45a deletion allows another form of genomic instability, gene amplification, when p21 (Cdkn1a gene product) is deleted also. Gene amplification in Gadd45a-/-p21-/- cells correlated with loss of both G1 and S-phase checkpoints. Multiple conditions of nutrient deprivation failed to prevent DNA synthesis in Gadd45a-/- cells. Gadd45a is therefore required for proper S-phase control and checkpoints under multiple conditions of nutrient deprivation. It is proposed that loss of S-phase control may account for both the uncoupling of DNA replication and centrosome duplication, and conferring gene amplification proficiency in cells lacking Gadd45a-/-. This is of particular importance for solid tumors, which may lack sufficient nutrients yet are unable to elicit checkpoints preventing genomic instability under these conditions.

Original languageEnglish (US)
Pages (from-to)704-709
Number of pages6
JournalCell Cycle
Issue number5
StatePublished - May 2005

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Developmental Biology
  • Cell Biology


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