Cell cycle regulation of E2F site occupation in vivo.
DNA-binding E2F complexes have been identified throughout the mammalian cell cycle, including the transcriptionally inactive complexes with pocket proteins, which occur early in the prereplicative G1 phase of the cycle, and the transactivating free E2F, which increases in late G1. Here, a regulatory B-myb promoter site was shown to bind with high affinity to free E2F and to E2F-pocket protein complexes in an indistinguishable way in vitro. In contrast, in vivo footprinting with NIH 3T3 cells demonstrated E2F site occupation specifically in early G1, when the B-myb promoter is inactive. These observations indicate that a novel mechanism governs E2F-DNA interactions during the cell cycle and emphasize the relevance of E2F site-directed transcriptional repression.
Zwicker
J
J
Institut für Molekularbiologie und Tumorforschung, Philipps-Universität Marburg, Germany.
Liu
N
N
Engeland
K
K
Lucibello
F C
FC
Müller
R
R
D016475:3T3 Cells; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D050684:E2F Transcription Factors; D016193:G1 Phase; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic; D056465:Retinoblastoma-Binding Protein 1; D050720:Retinoblastoma-Like Protein p107; D016196:S Phase; D015534:Trans-Activators; D050680:Transcription Factor DP1; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic
C533431:Arid4a protein, mouse; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D050684:E2F Transcription Factors; C499306:Mybl2 protein, mouse; D009687:Nuclear Proteins; C489485:Rbl1 protein, mouse; D056465:Retinoblastoma-Binding Protein 1; D050720:Retinoblastoma-Like Protein p107; D015534:Trans-Activators; D050680:Transcription Factor DP1; D014157:Transcription Factors; D004247:DNA