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Mol Cell Biol 1991 Oct 01;1110:5259-65. doi: 10.1128/mcb.11.10.5259-5265.1991.
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Inhibition of chromatin assembly in Xenopus oocytes correlates with derepression of the mouse mammary tumor virus promoter.

Perlmann T , Wrange O .

The mouse mammary tumor virus (MMTV) promoter is positively regulated by glucocorticoid hormone via binding of glucocorticoid receptor to a specific response element. Upon addition of hormone, a nucleosome containing the glucocorticoid response element is removed or structurally altered, suggesting that the nucleosome interferes with transcription. Accordingly, inhibition of chromatin assembly should relieve the repression and result in an increased constitutive activity. We have tested this hypothesis by injecting nonspecific competitor DNA into Xenopus laevis oocytes to titrate endogenous histones. The coinjection of competitor DNA altered chromatin structure: nucleosomal ladders produced by micrococcal nuclease were disrupted, and the unique helical setting of the MMTV promoter in a nucleosome was lost, as shown by in situ DNase I footprinting. Basal MMTV transcription was drastically increased by competitor DNA, whereas a coinjected, constitutively active adenovirus 2 major late promoter was not stimulated. These results show that the uninduced MMTV promoter is under negative control and provide direct support for the theory that the nucleosomal organization maintains the repression of this promoter in its uninduced state.

PubMed ID: 1656227
PMC ID: PMC361577
Article link: Mol Cell Biol

Species referenced: Xenopus laevis

References [+] :
Almer, Nuclease hypersensitive regions with adjacent positioned nucleosomes mark the gene boundaries of the PHO5/PHO3 locus in yeast. 1987, Pubmed