14-3-3Sigma is required to prevent mitotic catastrophe after DNA damage.
14-3-3Sigma is a member of a family of proteins that regulate cellular activity by binding and sequestering phosphorylated proteins. It has been suggested that 14-3-3sigma promotes pre-mitotic cell-cycle arrest following DNA damage, and that its expression can be controlled by the p53 tumour suppressor gene. Here we describe an improved approach to the generation of human somatic-cell knockouts, which we have used to generate human colorectal cancer cells in which both 14-3-3sigma alleles are inactivated. After DNA damage, these cells initially arrested in the G2 phase of the cell cycle, but, unlike cells containing 14-3-3sigma, the 14-3-3sigma-/- cells were unable to maintain cell-cycle arrest. The 14-3-3sigma-/- cells died ('mitotic catastrophe') as they entered mitosis. This process was associated with a failure of the 14-3-3sigma-deficient cells to sequester the proteins (cyclin B1 and cdc2) that initiate mitosis and prevent them from entering the nucleus. These results may indicate a mechanism for maintaining the G2 checkpoint and preventing mitotic death.
Chan
T A
TA
The Johns Hopkins Oncology Center, Program in Human Genetics, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21231, USA.
Hermeking
H
H
Lengauer
C
C
Kinzler
K W
KW
Vogelstein
B
B
D048948:14-3-3 Proteins; D018797:Cell Cycle Proteins / Q000502:physiology; D003001:Cloning, Molecular; D019926:Cyclin B / Q000502:physiology; D056744:Cyclin B1; D004249:DNA Damage; D016195:G2 Phase / Q000502:physiology; D006801:Humans; D008938:Mitosis / Q000502:physiology*; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D014407:Tumor Cells, Cultured; D014446:Tyrosine 3-Monooxygenase; D020687:cdc25 Phosphatases / Q000502:physiology
D048948:14-3-3 Proteins; C534699:CCNB1 protein, human; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; D011506:Proteins; D014446:Tyrosine 3-Monooxygenase; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases