Precisely positioned nucleosomes are not essential for c-fos gene regulation in vivo.
Chromatin architecture plays a decisive role in many aspects of transcription regulation. We have tested the role of specific chromatin structures in c-fos gene regulation, using a gene transfer system based on episomes derived from the Epstein-Barr virus (EBV). This system reproduces in several respects the chromatin structure and regulation of the chromosomal c-fos gene. Using this approach, we first demonstrate that the pausing of RNA polymerase II downstream of the transcriptional start site does not require precisely positioned nucleosomes. Indeed, changing the pattern of MNase hypersensitive sites along the transcribed sequence does not perturb RNA polymerase II pausing or the regulation of the c-fos gene. Next, we show that a putative nucleosome positioned between the SIE/SRE elements (-300) and the CRE/TATA elements (-36) is not necessary for activation by a variety of inducers. Accordingly, total or partial deletion of the putative nucleosome sequence does not disturb c-fos regulation while the two regulatory sites flanking the nucleosome sequence remain hypersensitive to MNase. As described in this paper, EBV episomes are useful vectors to critically examine the role of the chromatin structure in gene transcription for human cells.
Fivaz
J
J
Swiss Institute for Experimental Cancer Research (ISREC), Chemin des Boveresses 155, CH-1066, Epalinges, Switzerland.
Bassi
M C
MC
Price
M
M
Pinaud
S
S
Mirkovitch
J
J
D000818:Animals; D002460:Cell Line; D002843:Chromatin / Q000235:genetics; D005576:Colforsin / Q000494:pharmacology; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D004854:Herpesvirus 4, Human / Q000235:genetics; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D019169:Jurkat Cells; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D051379:Mice; D009707:Nucleosomes / Q000235:genetics*; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos / Q000235:genetics*; D012319:RNA Polymerase II / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D002843:Chromatin; D009707:Nucleosomes; D016760:Proto-Oncogene Proteins c-fos; D011993:Recombinant Fusion Proteins; D005576:Colforsin; D015759:Ionomycin; D004247:DNA; D008156:Luciferases; D012319:RNA Polymerase II; D013755:Tetradecanoylphorbol Acetate