title: Forkhead transcription factor FOXO3a protects quiescent cells from oxidative stress.
abstract: Reactive oxygen species are required for cell proliferation but can also induce apoptosis. In proliferating cells this paradox is solved by the activation of protein kinase B (PKB; also known as c-Akt), which protects cells from apoptosis. By contrast, it is unknown how quiescent cells that lack PKB activity are protected against cell death induced by reactive oxygen species. Here we show that the PKB-regulated Forkhead transcription factor FOXO3a (also known as FKHR-L1) protects quiescent cells from oxidative stress by directly increasing their quantities of manganese superoxide dismutase (MnSOD) messenger RNA and protein. This increase in protection from reactive oxygen species antagonizes apoptosis caused by glucose deprivation. In quiescent cells that lack the protective mechanism of PKB-mediated signalling, an alternative mechanism is induced as a consequence of PKB inactivity. This mechanism entails the activation of Forkhead transcription factors, the transcriptional activation of MnSOD and the subsequent reduction of reactive oxygen species. Increased resistance to oxidative stress is associated with longevity. The model of Forkhead involvement in regulating longevity stems from genetic analysis in Caenorhabditis elegans, and we conclude that this model also extends to mammalian systems.
authors.affiliation: Department of Physiological Chemistry, University Medical Center Utrecht and Center for Biomedical Genetics, 3584 CG Utrecht, The Netherlands.
authors.forename: Geert J P L
authors.initials: GJ
authors.lastname: Kops
authors.forename: Tobias B
authors.initials: TB
authors.lastname: Dansen
authors.forename: Paulien E
authors.initials: PE
authors.lastname: Polderman
authors.forename: Ingrid
authors.initials: I
authors.lastname: Saarloos
authors.forename: Karel W A
authors.initials: KW
authors.lastname: Wirtz
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Coffer
authors.forename: Ting-T
authors.initials: TT
authors.lastname: Huang
authors.forename: Johannes L
authors.initials: JL
authors.lastname: Bos
authors.forename: René H
authors.initials: RH
authors.lastname: Medema
authors.forename: Boudewijn M T
authors.initials: BM
authors.lastname: Burgering
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000378:metabolism; D017209:Apoptosis; D002470:Cell Survival; D002843:Chromatin / Q000378:metabolism; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D004790:Enzyme Induction; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D005947:Glucose / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D008136:Longevity / Q000502:physiology; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic / Q000235:genetics; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D013482:Superoxide Dismutase / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D000099156:Superoxide Dismutase 2
chemical_list: D000975:Antioxidants; D002843:Chromatin; D016895:Culture Media, Serum-Free; D004268:DNA-Binding Proteins; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D005947:Glucose; D007328:Insulin; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D013482:Superoxide Dismutase; D014157:Transcription Factors; D000099156:Superoxide Dismutase 2; C085126:FOXO1 protein, human; C494918:AKT1 protein, human