title: Redox regulation of the embryonic stem cell transcription factor oct-4 by thioredoxin.
abstract: Oct-4 is a transcriptional regulator required to maintain the totipotentiality of embryonic stem (ES) cells. Downregulation of its activity is required for proper differentiation of the blastocyst during uterine implantation. Uterine implantation and subsequent vascularization increase oxygen exposure of the developing embryo, thereby altering the intracellular reduction-oxidation status. We tested whether Oct-4 could be regulated by these changes in reduction-oxidation status. We found that Oct-4 DNA binding was exquisitely sensitive to abrogation by oxidation but that the DNA binding of another ES cell transcription factor, FoxD3, was much less sensitive to oxidation. The reducing enzyme Thioredoxin (but not Ape-1) could restore DNA-binding activity of Oct-4. Thioredoxin was less effective at restoring the DNA-binding ability of FoxD3. It was also found that Thioredoxin (but not Ape-1) could physically associate with cysteines in the POU domain of Oct-4. Finally, overexpressing normal Thioredoxin increased the transcriptional activity of Oct-4, while overexpressing a mutant Thioredoxin decreased the transcriptional activity of Oct-4. These data imply that ES cell transcription factors are differentially sensitive to oxidation and that Thioredoxin may differentially regulate ES cell transcription factors.
authors.affiliation: The Walther Oncology Center, James Whitcomb Riley Hospital for Children, Indiana University Medical Center, Indianapolis, Indiana, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Guo
authors.forename: Lawrence
authors.initials: L
authors.lastname: Einhorn
authors.forename: Mark
authors.initials: M
authors.lastname: Kelley
authors.forename: Kiichi
authors.initials: K
authors.lastname: Hirota
authors.forename: Junji
authors.initials: J
authors.lastname: Yodoi
authors.forename: Rolland
authors.initials: R
authors.lastname: Reinbold
authors.forename: Hans
authors.initials: H
authors.lastname: Scholer
authors.forename: Heather
authors.initials: H
authors.lastname: Ramsey
authors.forename: Robert
authors.initials: R
authors.lastname: Hromas
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004622:Embryo, Mammalian / Q000378:metabolism; D051858:Forkhead Transcription Factors; D051379:Mice; D009154:Mutation; D050814:Octamer Transcription Factor-3; D010084:Oxidation-Reduction; D012097:Repressor Proteins / Q000378:metabolism*; D013234:Stem Cells / Q000378:metabolism*; D013879:Thioredoxins / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D004268:DNA-Binding Proteins; D051858:Forkhead Transcription Factors; C101757:Foxd3 protein, mouse; D050814:Octamer Transcription Factor-3; C494174:Pou5f1 protein, mouse; D012097:Repressor Proteins; D014157:Transcription Factors; D013879:Thioredoxins