title: FOXO forkhead transcription factors induce G(2)-M checkpoint in response to oxidative stress.
abstract: Members of the FOXO family of mammalian forkhead transcription factors, including AFX, FKHRL1, and FKHR, are homologs of DAF-16, which regulates genes that contribute both to longevity and to resistance to various stresses (including oxidative stress) in Caenorhabditis elegans. We have generated mouse myoblastic C2C12 cell lines in which expression of a constitutively active form of AFX (AFX-TM) is inducible by Cre-mediated recombination at loxP sites. Here we show that forced expression of AFX-TM blocked cell cycle progression at the G(1) and G(2) phases and that FOXO family members regulated the expression of stress-inducible genes such as GADD45. AFX and FKHRL1 each directly activated the GADD45 promoter through interaction with FOXO binding motifs. Oxidative stress activated the GADD45 promoter in a FOXO-dependent manner, resulting in an increased abundance of GADD45 mRNA and protein as well as G(2) arrest. These responses were evident in cells in which the tumor suppressor protein p53 was inactivated. Our results suggest that the FOXO family of transcription factors plays an important role in the regulation of GADD45 in response to oxidative stress and thereby contributes to G(2)-M checkpoint.
authors.affiliation: Department of Geriatric Research, National Institute for Longevity Sciences, 36-3 Gengo, Morioka, Obu, Aichi 474-8522, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Furukawa-Hibi
authors.forename: Kiyomi
authors.initials: K
authors.lastname: Yoshida-Araki
authors.forename: Tsutomu
authors.initials: T
authors.lastname: Ohta
authors.forename: Kyoji
authors.initials: K
authors.lastname: Ikeda
authors.forename: Noboru
authors.initials: N
authors.lastname: Motoyama
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D015152:Blotting, Northern; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002460:Cell Line; D018076:DNA, Complementary / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000502:physiology*; D000939:Epitopes; D000071161:Forkhead Box Protein O1; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D016195:G2 Phase; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008938:Mitosis; D020411:Oligonucleotide Array Sequence Analysis; D018384:Oxidative Stress; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism* / Q000502:physiology*; D000097642:GADD45 Proteins
chemical_list: D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D000939:Epitopes; D000071161:Forkhead Box Protein O1; D000071316:Forkhead Box Protein O3; D051858:Forkhead Transcription Factors; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases; D011506:Proteins; D014157:Transcription Factors; D000097642:GADD45 Proteins; C085126:FOXO1 protein, human; C499517:FOXO3 protein, human; C108803:FOXO4 protein, human; C474033:FoxO3 protein, mouse; C467200:Foxo1 protein, mouse