title: Krüppel-like factor 4 prevents centrosome amplification following gamma-irradiation-induced DNA damage.
abstract: Centrosome duplication is a carefully controlled process in the cell cycle. Previous studies indicate that the tumor suppressor, p53, regulates centrosome duplication. Here, we present evidence for the involvement of the mammalian Krüppel-like transcription factor, KLF4, in preventing centrosome amplification following DNA damage caused by gamma-irradiation. The colon cancer cell line HCT116, which contains wild-type p53 alleles (HCT116 p53+/+), displayed stable centrosome numbers following gamma-irradiation. In contrast, HCT116 cells null for the p53 alleles (HCT116 p53-/-) exhibited centrosome amplification after irradiation. In the latter cell line, KLF4 was not activated following gamma-irradiation due to the absence of p53. However, centrosome amplification could be suppressed in irradiated HCT116 p53-/- cells by conditional induction of exogenous KLF4. Conversely, in a HCT116 p53+/+ cell line stably transfected with small hairpin RNA (shRNA) designed to specifically inhibit KLF4, gamma-irradiation induced centrosome amplification. In these cells, the inability of KLF4 to become activated in response to DNA damage was directly associated with an increase in cyclin E level and Cdk2 activity, both essential for regulating centrosome duplication. Cotransfection experiments showed that KLF4 overexpression suppressed the promoter activity of the cyclin E gene. The results of this study demonstrated that KLF4 is both necessary and sufficient in preventing centrosome amplification following gamma-radiation-induced DNA damage and does so by transcriptionally suppressing cyclin E expression.
authors.affiliation: Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Hong S
authors.initials: HS
authors.lastname: Yoon
authors.forename: Amr M
authors.initials: AM
authors.lastname: Ghaleb
authors.forename: Mandayam O
authors.initials: MO
authors.lastname: Nandan
authors.forename: Irfan M
authors.initials: IM
authors.lastname: Hisamuddin
authors.forename: William Brian
authors.initials: WB
authors.lastname: Dalton
authors.forename: Vincent W
authors.initials: VW
authors.lastname: Yang
mesh_terms: D045744:Cell Line, Tumor; D018385:Centrosome / Q000502:physiology*; D003110:Colonic Neoplasms; D019927:Cyclin E / Q000235:genetics; D004249:DNA Damage / Q000528:radiation effects*; D004268:DNA-Binding Proteins / Q000502:physiology*; D005720:Gamma Rays; D017353:Gene Deletion; D016158:Genes, p53; D006801:Humans; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D012313:RNA / Q000235:genetics; D014157:Transcription Factors / Q000502:physiology*; D014162:Transfection
chemical_list: D019927:Cyclin E; D004268:DNA-Binding Proteins; C000715467:KLF4 protein, human; D000090062:Kruppel-Like Factor 4; D051741:Kruppel-Like Transcription Factors; D014157:Transcription Factors; D012313:RNA