Displacement of sequence-specific transcription factors from mitotic chromatin.
The general inhibition in transcriptional activity during mitosis abolishes the stress-inducible expression of the human hsp70 gene. Among the four transcription factors that bind to the human hsp70 promoter, the DNA-binding activities of three (C/EBP, GBP, and HSF1) were normal, while Sp1 showed reduced binding activity in mitotic cell extracts. In vivo footprinting and immunocytochemical analyses revealed that all of the sequence-specific transcription factors were displaced from promoter sequences as well as from bulk chromatin during mitosis. The correlation of transcription factor displacement with chromatin condensation suggests an involvement of chromatin structure in mitotic repression. However, retention of DNase I hypersensitivity suggests that the hsp70 promoter was not organized in a canonical nucleosome structure in mitotic chromatin. Displacement of transcription factors from mitotic chromosomes could present another window in the cell cycle for resetting transcriptional programs.
Martínez-Balbás
M A
MA
Laboratory of Biochemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Dey
A
A
Rabindran
S K
SK
Ozato
K
K
Wu
C
C
D001483:Base Sequence; D022762:CCAAT-Enhancer-Binding Proteins; D002843:Chromatin / Q000378:metabolism*; D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism; D051790:G-Box Binding Factors; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics*; D006367:HeLa Cells; D006360:Heat-Shock Proteins; D006801:Humans; D007399:Interphase; D008938:Mitosis; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D029701:Saccharomyces cerevisiae Proteins; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D022762:CCAAT-Enhancer-Binding Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D051790:G-Box Binding Factors; C067168:HSF1 protein, S cerevisiae; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors